WO2011095917A1 - Apparatus and process for forming a spectacle frame - Google Patents

Apparatus and process for forming a spectacle frame Download PDF

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Publication number
WO2011095917A1
WO2011095917A1 PCT/IB2011/050375 IB2011050375W WO2011095917A1 WO 2011095917 A1 WO2011095917 A1 WO 2011095917A1 IB 2011050375 W IB2011050375 W IB 2011050375W WO 2011095917 A1 WO2011095917 A1 WO 2011095917A1
Authority
WO
WIPO (PCT)
Prior art keywords
sheet
mould
moulds
transversal
frame
Prior art date
Application number
PCT/IB2011/050375
Other languages
French (fr)
Inventor
Mario Mollo
Original Assignee
Luxottica S.R.L.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Luxottica S.R.L. filed Critical Luxottica S.R.L.
Publication of WO2011095917A1 publication Critical patent/WO2011095917A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/021—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D12/00—Producing frames
    • B29D12/02—Spectacle frames
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/021—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface
    • B29C2043/023—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles characterised by the shape of the surface having a plurality of grooves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2012/00—Frames
    • B29L2012/005—Spectacle frames

Definitions

  • This invention relates to an apparatus and a process for making a sheet made of thermoplastic material, for forming a spectacle frame.
  • the invention relates to the eyewear sector and in particular the working of thermoplastic material to make preforms for a spectacle frame.
  • the invention relates to the production of performed elements designed to form the front part of the spectacle frame.
  • the nose pads are made of the same material as the rest of the frame, forming projections from the frame.
  • preforms are obtained from sheets of thermoplastic material, which are heated until the material softens, so that it can then be worked.
  • the nose pads are made by removing material, that is to say, removing the material surrounding the nose pads.
  • That technique has the disadvantage of being complex and expensive. It also produces significant waste material, since the thickness of the sheets must be equal to at least the length of the nose pads. Therefore, the sheet is well oversized compared with the thickness of the front portion of the frame.
  • the nose pads are made by preparing the front part of the frame in the form of a fiat sheet and gluing to it a block of material added at the nose pads (or in general the zones to be thickened).
  • the block of material glued on is then subjected to mechanical working (milling) to produce the nose pads, that is to say, the relevant projecting zones.
  • That technique has the disadvantage of requiring complex, expensive working procedures.
  • patent document GB436421 describes a mould set up to receive the front portion of the frame which is ready-shaped (to form the annular lens rims and the bridge which connects them) and to thicken the bridge.
  • the front portion of the frame is shaped in such a way that it has excess material around the bridge zone, said material being moved laterally into the bridge zone to thicken it.
  • the mould is shaped in such a way that it folds and thickens the bridge, by folding the front portion of the frame already obtained from the sheet, taking care to leave excess material in the zone to be folded.
  • GB436421 is disadvantageous because it is very complex and delicate, requiring the sheet to be softened a first time, in order to be able to shape it as required, and then softened again to carry out the working which consists of moulding for thickening the bridge.
  • the pressure is applied to the softened preform (i.e. the blanked sheet) in a non uniform way; in particularly, in zones neighbouring the bridge the preform is squeezed with a stronger pressure, to force the material in said zone to laterally migrate to the zone of the bridge, in order to render the bridge thicker.
  • the injection moulding technique does not allow special chromatic effects to be achieved, that is to say, the production of adjacent layers or zones in very different colours in the frame.
  • the induction technique the grains of plastic material are fused together. Therefore, the injection moulding technique can only be used for monochrome frames. Disclosure of the Invention
  • This invention has for an aim to provide an apparatus and a process for making a spectacle frame made of thermoplastic material which overcomes the above-mentioned disadvantages of the prior art.
  • this invention has for an aim to provide an apparatus and a process for making in a particularly rapid and simple way a spectacle frame made of thermoplastic material having integrated projections, that is to say, formed by the frame, at the nose pads (where the term nose pads refers to the projections used to rest the spectacle on the wearer's nose) and/or side edges (where the term side edge refers to projections positioned at the lateral ends of the frame and projecting towards the rear of the spectacle, that is to say towards the sidepieces, for connecting the sidepieces).
  • nose pads are also called tabs.
  • This invention also has for an aim to propose an apparatus and a process for making a spectacle frame made of polycliiOmatic thermoplastic material with integrated projections (nose pads and/or side edges), having a particularly attractive appearance, in particular thanks to the fact that zones having different colours are set side by side, forming continuous and uniform contact lines.
  • zones having different colours may be set side by side longitudinally, forming coloured layers placed on top of one another, or trans vers ally, forming patches of colour set side by side laterally, or they may be positioned in any way in the material of which the frame is made (for example, forming any text or designs).
  • the zones having different colours form contact lines, that is to say dividing lines.
  • the aim in terms of appearance is to avoid any breaks in said lines and said coloured zones, despite making projecting zones.
  • the apparatus comprises an oven for heating the sheet of thermoplastic material until the material softens.
  • the sheet is preferably made of cellulose acetate.
  • the apparatus comprises a first and a second half-mould having opposite transversal faces.
  • One the two half-moulds can move longitudinally towards the other to compress the softened sheet placed therein.
  • the apparatus of the invention is an apparatus for making a sheet made of thermoplastic material, for forming a spectacle frame having nose pads and/or side edges.
  • the apparatus comprises:
  • an oven configured for heating a compact-shaped sheet of the thermoplastic material to a predetermined temperature at which the material softens
  • first and a second half-mould at least one of the half-moulds being movable towards the other along a longitudinal direction, wherein the half-moulds are configured to define a compression space for housing the softened compact- shaped sheet and have opposite transversal faces perpendicular to said longitudinal direction, which are operatively in contact with corresponding opposite faces of the sheet, when the sheet is arranged in the compression space.
  • the oven is not necessarily connected mechanically to the mould.
  • the operation of transferring the heated (i.e. softened) sheet form the oven to the mould can be performed either by automatic means (e.g. a robotic arm) can be used, or manual ly by an op erator .
  • transversal face of the second half-mould comprises at least a recess (arranged symmetrically with respect to an axis of symmetry).
  • the transversal face of the second half-mould does not comprise a corresponding recess (neither a protrusion) in correspondence to the recess of the transversal face of the second half-mould.
  • the apparatus comprises moving means connected to said at least one the half-moulds to move it towards the other half-mould, to reduce progressively said compression space defined between the half-moulds, applying a uniformly distributed pressure at the interface between the transversal face of the first half-mould and the sheet, whereby a plastic deformation of the compact-shaped sheet occurs by migration of material from the bulk of the sheet into said recess, thus generating corresponding projection in the sheet, protruding (symmetrically) from only one of the faces of the sheet, for forming the nose pads and/or side edges of the spectacle frame.
  • the protrusion thus formed in the sheet protrude form one of the faces of the sheet only; indeed, the face of the sheet opposite to the protrusions is flat.
  • the transversal face of the second half-mould comprises a plurality of recesses arranged symmetrically with respect to an axis of symmetry (which divides in two equal portions the opposite sides of the transversal face of the second half-mould having larger extension), the apparatus comprising moving means connected to said at least one the half- moulds to move it towards the other half-mould to reduce progressively said compression space defined between the half-moulds, whereby a plastic deformation of the compact-shaped sheet occurs by migration of material from the bulk of the sheet into said recesses, thus generating corresponding projections in the sheet, protruding at symmetrical positions only from one of the faces of the sheet, for forming the nose pads and/or side edges of the spectacle frame.
  • the two half-moulds preferably form a closed space in which the sheet is contained.
  • the transversal face of the second half-mould comprises at least one recess positioned at the frame nose pads, so that compressing the sheet causes a plastic deformation by migration of material from the bulk of the sheet into said at least one recess.
  • the moving means are connected to control means (e.g. a PCB or a processor), which are programmed to control the extent of the approaching of the half-moulds, whereby the volume of the compression space is controlled.
  • control means e.g. a PCB or a processor
  • the half-moulds approached until the compression space has a volume about equal to the volume of the sheet.
  • the half-moulds approached until the recesses are completely filled with the material constituting the sheet are completely filled with the material constituting the sheet.
  • the first half-mould preferably has a flat transversal face, for generating a uniform pressure on the sheet and making the front part of the frame with a flat surface (the surface visible from the outside when the spectacle are worn).
  • the transversal face of the second half-mould comprises projections at the zones of the sheet intended to be removed to obtain the holes for the nose and for the lenses. That is to say, the transversal face of the second half- mould is shaped in such a way that it comprises projections in zones of said face adjacent to said recesses.
  • one of the two half-moulds (preferably the second half-mould) is preferably positioned underneath and forms a housing designed to receive the sheet to be compressed.
  • the housing formed by the half-mould preferably extends on a surface which is larger than the side of the sheet, so that, before the compression, there is an open space at the side of the sheet (not occupied by the sheet) formed by the recess (preferably around one millimetre thick).
  • the sheet when it is compressed between the two half-moulds, the sheet also deforms longitudinally, becoming wider and flatter, becoming identical to the shape of the space formed by the two half-moulds.
  • the two half-moulds may also be shaped in such a way that the sheet is pressed in the longitudinal direction, without necessarily forming a closed space, that is to say, leaving the sheet the freedom to extend laterally without encountering constraints.
  • the two half-moulds are preferably shaped in such a way that they form a closed space.
  • the apparatus comprises control means set up to stop mould closing depending on the pressure inside the mould (that is to say, when a predetermined pressure value is reached).
  • control means are configured in such a way that they perform a double control function, stopping the two half-moulds during the closing step when a predetermined minimum distance between the half- moulds is reached (if the pressure condition is not satisfied).
  • this allows a particularly reliable moulding process and reduces the risk of damaging the sheet.
  • the transversal face of the second half-mould is shaped according to two alternative embodiments.
  • the transversal face of the second half-mould comprises at least a first and a second recess which are separate from each other, shaped to match the desired shape of the frame nose pads. It also comprises a third and a fourth lateral recess, positioned so that they generate thickened sections of material in the lateral zones of the front part of the frame, that is to say, in the zones where the sidepieces will be applied (thus forming the side edges).
  • the shape of the first and second recesses matches the shape of the nose pads of the finished frame. That minimises working after moulding of the preform.
  • the transversal face of the second half-mould comprises a single recess so that it interacts with the sheet in the nose pads zone.
  • Said face also comprises the lateral recesses, positioned so that they generate thickened sections of material in the lateral zones of the front part of the frame, that is to say, in the zone where the sidepieces will be applied (as in the first embodiment).
  • moulding of the preform comprises generating a single projection in the nose pads zone. This necessitates subsequent working (for example milling) to obtain the nose pads from said projection.
  • the advantage of the second embodiment, compared to the first, is that the same moulds can be used for all frame models, while minimising the subsequent working step and the consequent waste material.
  • the sheet preferably comprises at least two layers having different colours, placed one on top of another longitudinally. Therefore, the sheet has an outer face (the face visible from the outside when the spectacle are worn, intended to be flat) which has a different colour to an inner face (the face which is not visible from the outside when the spectacle are worn, intended to be shaped to form the nose pads and if necuney lateral projections, that is to say, side edges, at the joints with the sidepieces).
  • the preform (and therefore the related frame) made in accordance with this invention allows a significant saving in terms of production costs, since it reduces both waste material and the amount of processing required after the preform has been moulded.
  • the preform (and therefore the related frame) made in accordance with this invention is particularly excellent in terms of its appearance, since the projections formed by the frame (in particular the nose pads) have a uniformity and continuity of the material, in particular emphasised by the continuous and curved trend of the separating lines between the layers having different colours.
  • the invention makes available also a process for making a sheet made of thermoplastic material for forming a spectacle frame having nose pads and/or side edges.
  • the process comprises the following steps:
  • thermoplastic material - heating a compact- shaped sheet of the thermoplastic material to a predetermined temperature at which the material softens
  • the reduction of the compression space causes a plastic deformation of the compact-shaped sheet by migration of material from the bulk of the sheet into said recess, thus generating corresponding projections in the sheet, protruding at symmetrical positions from one of the faces of the sheet, for forming the nose pads and/or side edges of the spectacle frame.
  • FIG. 1 is a schematic cross-section of an apparatus according to this invention.
  • Figure 2 illustrates an alternative embodiment of the apparatus of Figure l ;
  • FIG. 3 illustrates a front portion of a spectacle frame made according to this invention
  • FIG. 4 is an open plan view of the apparatus of Figure 2, with a dashed line representation of the portion of Figure 3 ideally placed on top of the apparatus half-mould;
  • FIG. 5 is a cross-section of the apparatus of Figure 4 according to the plane labelled A - A in Figure 4;
  • FIG. 6 is a perspective view of the apparatus of Figure 4.
  • Figure 7 illustrates a sheet moulded by the apparatus of Figure 2;
  • FIG. 8 illustrates an alternative embodiment of the second half-mould of the apparatus of Figure 2;
  • FIG. 9 is a cross-section of the apparatus of Figure 4 according to the plane labelled A - A in Figure 8;
  • FIG. 0 is a cross-section of the apparatus of Figure 4 according to the plane labelled B - B in Figure 8;
  • FIG. 1 1 is a perspective view of the apparatus of Figure 8;
  • Figure 12 illustrates a sheet moulded by the apparatus of Figure 8.
  • the numeral 1 denotes an apparatus for making a spectacle frame 2 made of thermoplastic material
  • the apparatus 1 is an apparatus 1 for making a sheet made of thermoplastic material, for forming a spectacle frame 2 having nose pads 21 and side edges 22, comprising.
  • the frame 2 is made of cellulose acetate.
  • the apparatus 1 comprises an oven (of the known type and not illustrated) configured to heat the sheet 3 of thermoplastic material to a predetermined temperature at which the material softens.
  • the sheet is preferably heated to a temperature between 90°C and 130°. More preferably, the sheet is heated to a temperature of around 120°C (said temperature is established in an internal zone of the sheet), or around 100°C (said temperature is established in a peripheral zone of the sheet).
  • the sheet 3 preferably has a compact, uniform unworked shape (for example, the shape of a parallelepiped).
  • the oven is preferably an electromagnetic induction oven, operating at a frequency between 25 MHz and 30 MHz.
  • the oven power rating is preferably between 3 kW and 5 kW.
  • this prevents the formation of water droplets or air bubbles in the sheet during heating.
  • the oven is preferably configured to heat the whole sheet 3,
  • the apparatus 1 comprises a structure 4 configured to compress the softened sheet 3 in order to give it a desired shape.
  • the structure 4 comprises a first half-mould 5 and a second half-mould 6.
  • the first half-mould has a transversal face 7 opposite (that is to say, giving onto) a corresponding transversal face 8 of the second half-mould 6.
  • the opposite transversal faces 7 and 8 are set up to interact with the sheet 3 interposed between them.
  • the half-moulds 5 and 6 are configured so that they form a compression space in which the sheet 3 can be inserted and compressed.
  • the compression space is preferably a closed space.
  • At least one of the half-moulds 5 and 6 can move in a longitudinal direction (that is to say, perpendicularly to the planes in which the half-mould transversal faces lie) towards the other to form said space and compress the softened sheet 3 placed therein.
  • the half-moulds 5 and 6 can move towards and away from each other between a position in which the mould that they form is open and a position in which it is closed.
  • the half-moulds 5 and 6 are positioned with the transversal faces 7 and 8 in horizontal planes.
  • the lower half-mould is preferably stationary, whilst the upper half-mould can move vertically towards and away from the other half-mould, to close and open the mould formed by the two half-moulds 5 and 6.
  • the transversal face 8 of the second half- mould 6 comprises two recesses 9B positioned at the frame side edges 22 (that is to say, positioned so that they interact with a portion of the sheet 3 positioned at the frame 2 side edges 22), so that compressing the sheet 3 causes a plastic deformation by migration of material from the bulk of the sheet 3 into said recesses 9B.
  • the transversal face 8 of the second half-mould 6 comprises at least one recess 9 configured in such a way that compressing the sheet 3 causes a plastic deformation by migration of material from the bulk of the sheet 3 into said at least one recess 9, generating at least one projection in the sheet, the projection being positioned at the frame 2 nose pads 21 and/or side edges 22.
  • the apparatus 1 comprises:
  • an oven configured for heating a compact-shaped sheet 3 of the thermoplastic material to a predetermined temperature at which the material softens
  • the transversal face 8 of the second half-mould 6 comprises a plurality of recesses 9A, 9B arranged symmetrically with respect to an axis X of symmetry, the apparatus 1 comprising moving means connected to said at least one the half-moulds to move it towards the other half-mould to reduce progressively said compression space defined between the half-moulds 5, 6, whereby a plastic deformation of the compact-shaped sheet occurs by migration of material from the bulk of the sheet 3 into said recesses 9 A, 9B, thus generating corresponding projections in the sheet, protruding at symmetrical positions from one of the faces of the sheet, for forming the nose pads 21 and/or side edges 22 of the spectacle frame 2.
  • the axis X of symmetry divides in two equal portions the opposite sides of the transversal face of the second half-mould having larger extension.
  • the at least one recess 9 A is located in the transverse face 8 of the second half-mould 6 in a position symmetrical with respect to the X axis and substantially intermediate between the sides of the transverse face 8 perpendicular to the X axis (i.e. the sides having longer extension).
  • further recesses 9B are provided, located at opposite end portions of the transverse face 8 of the second half-mould 6, symmetrical with respect to the X axis.
  • the transversal face 7 of the first half-mould 5 is preferably flat. This ensures that the pressure is applied uniformly to the face of the sheet in contact with the transverse face 7 of the first half-mould 5, i.e. the face 7 opposite to the face of the sheet in contact with the transverse face 8 of the second half-mould 6.
  • the material which flows into the recess 9 is not moved from lateral adjacent zones by a mechanical action (for example by folding). Instead, the material flows into the recess 9 due to sheet 3 compression in the mould.
  • the half-moulds 5 and 6 form a predetermined closed space which is substantially equal to the space occupied by the sheet, but having a desired shape.
  • the transversal face 7 of the first half-mould 5 is configured in such a way to be inserted precisely into a housing defined by the second half-mould 6, whereby said closed space (compression space) is progressively decreased, along with the movement of the half-moulds 5 and 6 one with respect to the other.
  • control means are provided (e.g. constituted by an electronic device, per se known), connected to the moving means, to control the stroke imparted to the first half-mould 5 (or to the second half-mould 6) from the moving means, in order to control the extent of reduction of the compression space (by controlling the extent of insertion of the transversal face 7 of the first half-mould 5 into the housing defined by the second half-mould 6).
  • the transversal face 8 of the second half-mould 6 preferably comprises projections 10 at the zones of the sheet 3 intended to be removed in order to make the holes for the nose and for the lenses (that is to say, the projections 10 are positioned on the transversal face 8 of the second half- mould 6 in such a way that they interact with portions of the sheet 3 intended to be removed to make the holes for the nose and the lenses).
  • the projections are positioned in zones adjacent to said at least one recess 9.
  • the invention provides two embodiments of the recesses 9 A for moulding the nose pads (and in particular their shape and position in the transversal face 8 of the second half-mould 6).
  • the transversal face 8 of the second half-mould 6 comprises at least a first and a second recess 9A which are separate from each other, shaped to match the shape of the nose pads of the frame to be made.
  • the transversal face 8 of the second half-mould 6 comprises a single recess 9A extending in a zone of the face 8 which interacts with both portions of the sheet 3 intended to form the nose pads of the frame to be made.
  • the first embodiment has the advantage of allowing substantially complete and final moulding of the nose pads by plastic deformation of the sheet 3 in the mould,
  • the apparatus 1 is substantially dedicated to a frame model in which the nose pads have a predetermined shape.
  • the apparatus 1 allows frames to be made with nose pads that have any shape. Therefore, in this case the apparatus is particularly versatile. Obviously, to achieve the final shape of the nose pads, in this case minor working of the projection formed in the mould is required, to give the nose pads the desired shape.
  • the transversal face 8 of the second half-mould 6 also comprises two other recesses 9B in lateral positions, for interacting with the portions of the sheet 3 designed to constitute lateral thickened sections of the frame, for connecting the sidepieces.
  • At least one of the half-moulds 5 and 6 is equipped with ducts 11 configured for blowing air into the space, that is to say, into an interface between the transversal face of the mould and the sheet 3 placed in it.
  • the second half-mould 6 is preferably positioned with the (shaped) transversal face 8 facing upwards.
  • the first half-mould 5 is positioned above the second half-mould 8 and can move vertically towards and away from it.
  • the second half-mould 6 forms the ducts 11.
  • the half-moulds 5 and 6 are configured in such a way that the inner space has a transversal dimension which is greater than the transversal dimension of the sheet. That is to say, the transversal faces 7 and 8 of the half-moulds 5 and 6 have a surface area which is greater than that of the corresponding faces of the sheet 3 operatively in contact with them.
  • the sheet 3 has a thickness of intermediate value between the minimum thickness of the preform 2 (in the zones without projections) and the maximum thickness of the preform 2 (in the zones with projections, in particular the nose pads).
  • the apparatus 1 operates as follows.
  • the sheet 3 (a block of thermoplastic material having the shape of a parallelepiped, as described above) is placed in an oven and heated until it softens.
  • the softened sheet 3 is placed between the half-moulds 5 and 6, so that it will interact with their transversal faces 7 and 8.
  • the half-moulds 5 and 6 are moved towards each other until the mould is in a closed position, forming a predetermined space interposed between the half- moulds, in which the sheet 3 is positioned and therefore compressed.
  • the material of which the sheet 3 is made is forced to flow from the bulk of the sheet 3 into the recesses 9 in the second half-mould 6.
  • the half-moulds 5 and 6 are kept in the closed position for a preset time
  • the half-moulds 5 and 6 are moved away from each other to a mould open position.
  • a fluid for example air
  • the mould preferably to the interface between the sheet 3 and the second half-mould 6 (that is to say, the stationary, lower half-mould), to promote sheet 3 detachment from the half-mould.
  • the shaped sheet is subjected to further mechanical working, in particular removal of the portions of sheet 3 positioned at the lenses and the nose, to obtain the frame.
  • this invention also provides a process for making a spectacle frame 2 made of thermoplastic material.
  • the process comprises the following steps:
  • thermoplastic material - heating a sheet 3 of the thermoplastic material to a predetermined temperature at which the material softens
  • the transversal face 8 of the second half-mould 6 comprises at least one recess 9A at the frame 2 nose pads 21 and deformation of the sheet 3 comprises a plastic deformation by migration of material from the bulk of the sheet 3 into said at least one recess 9A.
  • Said step comprises again heating to the softening point the parts of the preform to be treated (therefore, in this case, localised or partial heating).
  • the sheet preferably comprises at least two adjacent zones having different colours, as described above.
  • the step of heating the sheet before sheet moulding in the mould preferably comprises heating the entire sheet.
  • the transversal face 8 of the second half-mould 6 preferably comprises projections 10 at the zones of the sheet 3 intended to be removed in order to make the holes for the nose and for the lenses, for generating an intensified compression in zones of the sheet 3 adjacent to the zones interacting with the recesses 9 (9 A and 9B).
  • the half-moulds are kept in the closed position for a predetermined period of time, before moving the half-moulds 5 and 6 away from each other, thus allowing extraction of the preform (that is to say, the deformed sheet 3),
  • control step comprises stopping closing of the half-moulds when a predetermined pressure value is reached inside the mould (that is to say, the pressure applied to the sheet 3).
  • the half-moulds are stopped in any case when a predetermined minimum value is reached for the distance between them (if the predetermined pressure value has still not been reached).
  • the invention allows a frame to be made of thermoplastic material with integrated nose pads in a particularly simple and effective way, minimising process waste,
  • the invention allows frames of that type to be made with multicoloured layers which have a particularly attractive appearance, since the projections of the nose pads do not have any irregularities or breaks in the continuity of the contact lines between the different coloured layers.

Abstract

An apparatus (1) for making a spectacle frame (2) made of thermoplastic material comprises an oven configured for heating a sheet (3) of the thermoplastic material to a predetermined temperature at which the material softens; a first and a second half-mould (5, 6) having opposite transversal faces (7, 8), at least one the half-moulds being able to move longitudinally towards the other to form a compression space for the softened sheet (3) placed therein. The transversal face (8) of the second half-mould (6) comprises at least one recess (9) configured in such a way that compressing the sheet (3) causes a plastic deformation by migration of material from the bulk of the sheet (3) into said at least one recess (9), generating at least one projection in the sheet which is positioned at frame (2) nose pads (21) and/or side edges (22).

Description

Description
Apparatus and process for making a spectacle frame
Technical Field
This invention relates to an apparatus and a process for making a sheet made of thermoplastic material, for forming a spectacle frame.
The invention relates to the eyewear sector and in particular the working of thermoplastic material to make preforms for a spectacle frame.
More particularly, the invention relates to the production of performed elements designed to form the front part of the spectacle frame.
Background Art
In such types of frames, the nose pads are made of the same material as the rest of the frame, forming projections from the frame.
In this context, preforms are obtained from sheets of thermoplastic material, which are heated until the material softens, so that it can then be worked.
Two solutions are basically used for working the softened sheets.
In a first solution the nose pads are made by removing material, that is to say, removing the material surrounding the nose pads.
That technique has the disadvantage of being complex and expensive. It also produces significant waste material, since the thickness of the sheets must be equal to at least the length of the nose pads. Therefore, the sheet is well oversized compared with the thickness of the front portion of the frame.
According to a second solution the nose pads are made by preparing the front part of the frame in the form of a fiat sheet and gluing to it a block of material added at the nose pads (or in general the zones to be thickened).
The block of material glued on is then subjected to mechanical working (milling) to produce the nose pads, that is to say, the relevant projecting zones.
That technique has the disadvantage of requiring complex, expensive working procedures.
Moreover, application of the additional material interrupts the continuity of the material used to make the frame, compromising the appearance of the frame, especially if the frame consists of coloured layers placed on top of one another.
Another factor compromising appearance is the fact that it is not possible (or it is extremely difficult) to glue on blocks of additional material having the same colours as the sheet without leaving a noticeable break in the coloured zones at the end of the working. In practice, only transparent or in any case monochrome additional materials are used.
Again, that technique results in wasted additional material.
It should be noticed that there are various prior art techniques for working the sheet of softened thermoplastic material, which involve cutting or folding the sheet, or even compressing the material to strengthen and bend the bridge connecting the lens rims.
For example, patent document GB436421 describes a mould set up to receive the front portion of the frame which is ready-shaped (to form the annular lens rims and the bridge which connects them) and to thicken the bridge. The front portion of the frame is shaped in such a way that it has excess material around the bridge zone, said material being moved laterally into the bridge zone to thicken it.
In that solution, the mould is shaped in such a way that it folds and thickens the bridge, by folding the front portion of the frame already obtained from the sheet, taking care to leave excess material in the zone to be folded.
That solution does not allow the creation of the desired thickened sections in the nose pad zone, since said thickened sections are thin tabs projecting from the front part of the frame.
Moreover, the solution of GB436421 is disadvantageous because it is very complex and delicate, requiring the sheet to be softened a first time, in order to be able to shape it as required, and then softened again to carry out the working which consists of moulding for thickening the bridge.
Furthermore, in the solution of GB436421 the pressure is applied to the softened preform (i.e. the blanked sheet) in a non uniform way; in particularly, in zones neighbouring the bridge the preform is squeezed with a stronger pressure, to force the material in said zone to laterally migrate to the zone of the bridge, in order to render the bridge thicker.
This is disadvantageous, because it makes it impossible to obtain special chromatic effects to be achieved in the spectacle frame, that is to say, the production of adjacent layers or zones in very different colours in the frame, which are not subjected to any interruption or break. Therefore, the prior art solutions do not allow the production of a spectacle frame made of thermoplastic material in which the nose pads or other projections are made in a simple, effective way.
It should also be noticed that, to make plastic frames, use of the technique of injecting material in the liquid phase into a closed mould is also known.
However, that technique is very expensive, due to the cost of the mould, and so is only justified for models of spectacle to be made in particularly large quantities.
Moreover, the injection moulding technique does not allow special chromatic effects to be achieved, that is to say, the production of adjacent layers or zones in very different colours in the frame. In the induction technique the grains of plastic material are fused together. Therefore, the injection moulding technique can only be used for monochrome frames. Disclosure of the Invention
This invention has for an aim to provide an apparatus and a process for making a spectacle frame made of thermoplastic material which overcomes the above-mentioned disadvantages of the prior art.
In particular, this invention has for an aim to provide an apparatus and a process for making in a particularly rapid and simple way a spectacle frame made of thermoplastic material having integrated projections, that is to say, formed by the frame, at the nose pads (where the term nose pads refers to the projections used to rest the spectacle on the wearer's nose) and/or side edges (where the term side edge refers to projections positioned at the lateral ends of the frame and projecting towards the rear of the spectacle, that is to say towards the sidepieces, for connecting the sidepieces).
It should be noticed that the nose pads are also called tabs.
This invention also has for an aim to propose an apparatus and a process for making a spectacle frame made of polycliiOmatic thermoplastic material with integrated projections (nose pads and/or side edges), having a particularly attractive appearance, in particular thanks to the fact that zones having different colours are set side by side, forming continuous and uniform contact lines.
It should be noticed that such zones having different colours may be set side by side longitudinally, forming coloured layers placed on top of one another, or trans vers ally, forming patches of colour set side by side laterally, or they may be positioned in any way in the material of which the frame is made (for example, forming any text or designs).
In any case, the zones having different colours form contact lines, that is to say dividing lines. In light of this, the aim in terms of appearance is to avoid any breaks in said lines and said coloured zones, despite making projecting zones.
These aims are fully achieved by the apparatus and the process according to this invention as characterised in the appended claims.
In particular, the apparatus according to the invention comprises an oven for heating the sheet of thermoplastic material until the material softens.
The sheet is preferably made of cellulose acetate.
Moreover, the apparatus comprises a first and a second half-mould having opposite transversal faces. One the two half-moulds can move longitudinally towards the other to compress the softened sheet placed therein.
In particular, the apparatus of the invention is an apparatus for making a sheet made of thermoplastic material, for forming a spectacle frame having nose pads and/or side edges.
The apparatus comprises:
- an oven configured for heating a compact-shaped sheet of the thermoplastic material to a predetermined temperature at which the material softens;
- a first and a second half-mould, at least one of the half-moulds being movable towards the other along a longitudinal direction, wherein the half-moulds are configured to define a compression space for housing the softened compact- shaped sheet and have opposite transversal faces perpendicular to said longitudinal direction, which are operatively in contact with corresponding opposite faces of the sheet, when the sheet is arranged in the compression space.
The oven is not necessarily connected mechanically to the mould. The operation of transferring the heated (i.e. softened) sheet form the oven to the mould, can be performed either by automatic means (e.g. a robotic arm) can be used, or manual ly by an op erator .
According to the invention, transversal face of the second half-mould comprises at least a recess (arranged symmetrically with respect to an axis of symmetry). The transversal face of the second half-mould does not comprise a corresponding recess (neither a protrusion) in correspondence to the recess of the transversal face of the second half-mould. In addition, according to the invention, the apparatus comprises moving means connected to said at least one the half-moulds to move it towards the other half-mould, to reduce progressively said compression space defined between the half-moulds, applying a uniformly distributed pressure at the interface between the transversal face of the first half-mould and the sheet, whereby a plastic deformation of the compact-shaped sheet occurs by migration of material from the bulk of the sheet into said recess, thus generating corresponding projection in the sheet, protruding (symmetrically) from only one of the faces of the sheet, for forming the nose pads and/or side edges of the spectacle frame.
Indeed, the protrusion thus formed in the sheet protrude form one of the faces of the sheet only; indeed, the face of the sheet opposite to the protrusions is flat.
Preferably, according to the invention, the transversal face of the second half-mould comprises a plurality of recesses arranged symmetrically with respect to an axis of symmetry (which divides in two equal portions the opposite sides of the transversal face of the second half-mould having larger extension), the apparatus comprising moving means connected to said at least one the half- moulds to move it towards the other half-mould to reduce progressively said compression space defined between the half-moulds, whereby a plastic deformation of the compact-shaped sheet occurs by migration of material from the bulk of the sheet into said recesses, thus generating corresponding projections in the sheet, protruding at symmetrical positions only from one of the faces of the sheet, for forming the nose pads and/or side edges of the spectacle frame.
It should be noticed that, in the position in which they are near to each other, the two half-moulds preferably form a closed space in which the sheet is contained.
According to the invention, the transversal face of the second half-mould comprises at least one recess positioned at the frame nose pads, so that compressing the sheet causes a plastic deformation by migration of material from the bulk of the sheet into said at least one recess.
Preferably, the moving means are connected to control means (e.g. a PCB or a processor), which are programmed to control the extent of the approaching of the half-moulds, whereby the volume of the compression space is controlled.
Preferably, the half-moulds approached until the compression space has a volume about equal to the volume of the sheet. Indeed, the half-moulds approached until the recesses are completely filled with the material constituting the sheet.
The first half-mould preferably has a flat transversal face, for generating a uniform pressure on the sheet and making the front part of the frame with a flat surface (the surface visible from the outside when the spectacle are worn).
Moreover, the transversal face of the second half-mould comprises projections at the zones of the sheet intended to be removed to obtain the holes for the nose and for the lenses. That is to say, the transversal face of the second half- mould is shaped in such a way that it comprises projections in zones of said face adjacent to said recesses.
In that way, when the half-moulds are moved towards each other at a predetermined distance in a closed position, said projections generate on the sheet an intensified compression in zones of the sheet adjacent to the zones interacting with the recesses, promoting the migration of material from the bulk of the sheet towards the recesses.
It should be noticed that one of the two half-moulds (preferably the second half-mould) is preferably positioned underneath and forms a housing designed to receive the sheet to be compressed.
The housing formed by the half-mould preferably extends on a surface which is larger than the side of the sheet, so that, before the compression, there is an open space at the side of the sheet (not occupied by the sheet) formed by the recess (preferably around one millimetre thick).
This means that, when it is compressed between the two half-moulds, the sheet also deforms longitudinally, becoming wider and flatter, becoming identical to the shape of the space formed by the two half-moulds.
It should also be noticed that the two half-moulds may also be shaped in such a way that the sheet is pressed in the longitudinal direction, without necessarily forming a closed space, that is to say, leaving the sheet the freedom to extend laterally without encountering constraints.
However, the two half-moulds are preferably shaped in such a way that they form a closed space.
That allows improved control of the moulding process, by controlling the pressure created inside the mould during pressing.
The apparatus comprises control means set up to stop mould closing depending on the pressure inside the mould (that is to say, when a predetermined pressure value is reached).
It should also be noticed that the control means are configured in such a way that they perform a double control function, stopping the two half-moulds during the closing step when a predetermined minimum distance between the half- moulds is reached (if the pressure condition is not satisfied).
Advantageously, this allows a particularly reliable moulding process and reduces the risk of damaging the sheet.
The transversal face of the second half-mould is shaped according to two alternative embodiments.
In a first embodiment, the transversal face of the second half-mould comprises at least a first and a second recess which are separate from each other, shaped to match the desired shape of the frame nose pads. It also comprises a third and a fourth lateral recess, positioned so that they generate thickened sections of material in the lateral zones of the front part of the frame, that is to say, in the zones where the sidepieces will be applied (thus forming the side edges).
In that first embodiment, the shape of the first and second recesses matches the shape of the nose pads of the finished frame. That minimises working after moulding of the preform.
In a second embodiment, the transversal face of the second half-mould comprises a single recess so that it interacts with the sheet in the nose pads zone. Said face also comprises the lateral recesses, positioned so that they generate thickened sections of material in the lateral zones of the front part of the frame, that is to say, in the zone where the sidepieces will be applied (as in the first embodiment).
In that second embodiment, moulding of the preform comprises generating a single projection in the nose pads zone. This necessitates subsequent working (for example milling) to obtain the nose pads from said projection.
The advantage of the second embodiment, compared to the first, is that the same moulds can be used for all frame models, while minimising the subsequent working step and the consequent waste material.
The sheet preferably comprises at least two layers having different colours, placed one on top of another longitudinally. Therefore, the sheet has an outer face (the face visible from the outside when the spectacle are worn, intended to be flat) which has a different colour to an inner face (the face which is not visible from the outside when the spectacle are worn, intended to be shaped to form the nose pads and if necessaiy lateral projections, that is to say, side edges, at the joints with the sidepieces).
Therefore, the preform (and therefore the related frame) made in accordance with this invention allows a significant saving in terms of production costs, since it reduces both waste material and the amount of processing required after the preform has been moulded.
Moreover, the preform (and therefore the related frame) made in accordance with this invention is particularly excellent in terms of its appearance, since the projections formed by the frame (in particular the nose pads) have a uniformity and continuity of the material, in particular emphasised by the continuous and curved trend of the separating lines between the layers having different colours.
The invention makes available also a process for making a sheet made of thermoplastic material for forming a spectacle frame having nose pads and/or side edges.
According to the invention, the process comprises the following steps:
- preparing a first and a second half-mould, at least one of the half-moulds being movable towards the other along a longitudinal direction, wherein the half- moulds have opposite transversal faces perpendicular to said longitudinal direction and wherein the transversal face of the second-half mould comprises at least a recess arranged symmetrically with respect to an axis of symmetiy;
- heating a compact- shaped sheet of the thermoplastic material to a predetermined temperature at which the material softens;
- placing the softened compact-shaped sheet in a compression space defined between the half-moulds, in such a way that said transversal faces are in contact with corresponding opposite faces of the sheet;
- moving said at least one of the half-moulds towards the other half-mould, to progressively reduce said compression space applying a uniformly distributed pressure at the interface between the transversal face of the first half-mould and the sheet, until the recess is completely filled with the material of the sheet, whereby the softened compact-shaped sheet is deformed to a desired shape to obtain a preform for forming the spectacle frame,
whereby the reduction of the compression space causes a plastic deformation of the compact-shaped sheet by migration of material from the bulk of the sheet into said recess, thus generating corresponding projections in the sheet, protruding at symmetrical positions from one of the faces of the sheet, for forming the nose pads and/or side edges of the spectacle frame.
Brief Description of the Drawings
This and other features of the invention will become more apparent from the following detailed description of a preferred, non-limiting example embodiment of it, with reference to the accompanying drawings, in which:
- Figure 1 is a schematic cross-section of an apparatus according to this invention;
- Figure 2 illustrates an alternative embodiment of the apparatus of Figure l ;
- Figure 3 illustrates a front portion of a spectacle frame made according to this invention;
- Figure 4 is an open plan view of the apparatus of Figure 2, with a dashed line representation of the portion of Figure 3 ideally placed on top of the apparatus half-mould;
- Figure 5 is a cross-section of the apparatus of Figure 4 according to the plane labelled A - A in Figure 4;
- Figure 6 is a perspective view of the apparatus of Figure 4;
- Figure 7 illustrates a sheet moulded by the apparatus of Figure 2;
- Figure 8 illustrates an alternative embodiment of the second half-mould of the apparatus of Figure 2;
- Figure 9 is a cross-section of the apparatus of Figure 4 according to the plane labelled A - A in Figure 8;
- Figure 0 is a cross-section of the apparatus of Figure 4 according to the plane labelled B - B in Figure 8;
- Figure 1 1 is a perspective view of the apparatus of Figure 8;
- Figure 12 illustrates a sheet moulded by the apparatus of Figure 8.
Detailed Description of the Preferred Embodiments of the Invention
In the accompanying drawings the numeral 1 denotes an apparatus for making a spectacle frame 2 made of thermoplastic material, In particular, the apparatus 1 is an apparatus 1 for making a sheet made of thermoplastic material, for forming a spectacle frame 2 having nose pads 21 and side edges 22, comprising.
In particular, the frame 2 is made of cellulose acetate. The apparatus 1 comprises an oven (of the known type and not illustrated) configured to heat the sheet 3 of thermoplastic material to a predetermined temperature at which the material softens. The sheet is preferably heated to a temperature between 90°C and 130°. More preferably, the sheet is heated to a temperature of around 120°C (said temperature is established in an internal zone of the sheet), or around 100°C (said temperature is established in a peripheral zone of the sheet).
It should be noticed that, below 90°C, sheet 3 softening is not sufficient to guarantee a correct flow of material into the recesses 9 during moulding. Above 130°C a problem occurs linked to the formation of bubbles in the sheet 3, which are defects and may compromise the moulding result.
It should be noticed that the sheet 3 preferably has a compact, uniform unworked shape (for example, the shape of a parallelepiped).
The oven is preferably an electromagnetic induction oven, operating at a frequency between 25 MHz and 30 MHz. The oven power rating is preferably between 3 kW and 5 kW.
Advantageously, this prevents the formation of water droplets or air bubbles in the sheet during heating.
It should be noticed that the oven is preferably configured to heat the whole sheet 3,
Advantageously that allows the coloured zones of the sheet to be rendered uniform (if the sheet 3 is made of polychromatic material).
Moreover, the apparatus 1 comprises a structure 4 configured to compress the softened sheet 3 in order to give it a desired shape.
The structure 4 comprises a first half-mould 5 and a second half-mould 6.
The first half-mould has a transversal face 7 opposite (that is to say, giving onto) a corresponding transversal face 8 of the second half-mould 6. The opposite transversal faces 7 and 8 are set up to interact with the sheet 3 interposed between them.
In particular, the half-moulds 5 and 6 are configured so that they form a compression space in which the sheet 3 can be inserted and compressed.
The compression space is preferably a closed space.
In light of this, at least one of the half-moulds 5 and 6 can move in a longitudinal direction (that is to say, perpendicularly to the planes in which the half-mould transversal faces lie) towards the other to form said space and compress the softened sheet 3 placed therein.
Therefore, the half-moulds 5 and 6 can move towards and away from each other between a position in which the mould that they form is open and a position in which it is closed.
In particular, the half-moulds 5 and 6 are positioned with the transversal faces 7 and 8 in horizontal planes.
The lower half-mould is preferably stationary, whilst the upper half-mould can move vertically towards and away from the other half-mould, to close and open the mould formed by the two half-moulds 5 and 6.
According to the invention, the transversal face 8 of the second half-mould
6 comprises at least one recess 9A positioned at the frame nose pads 21 (that is to say, positioned so that it interacts with a portion of the sheet 3 positioned at the frame 2 nose pads), so that compressing the sheet causes a plastic deformation by migration of material from the bulk of the sheet 3 into said at least one recess 9A.
In addition (or alternatively), the transversal face 8 of the second half- mould 6 comprises two recesses 9B positioned at the frame side edges 22 (that is to say, positioned so that they interact with a portion of the sheet 3 positioned at the frame 2 side edges 22), so that compressing the sheet 3 causes a plastic deformation by migration of material from the bulk of the sheet 3 into said recesses 9B.
Therefore, the transversal face 8 of the second half-mould 6 comprises at least one recess 9 configured in such a way that compressing the sheet 3 causes a plastic deformation by migration of material from the bulk of the sheet 3 into said at least one recess 9, generating at least one projection in the sheet, the projection being positioned at the frame 2 nose pads 21 and/or side edges 22.
Hence, the apparatus 1 comprises:
- an oven configured for heating a compact-shaped sheet 3 of the thermoplastic material to a predetermined temperature at which the material softens;
- a first and a second half-mould 5, 6, at least one of the half-moulds being movable towards the other along a longitudinal direction, wherein the half-moulds 5, 6 are configured to define a compression space for housing the softened compact-shaped sheet 3 and have opposite transversal faces 7, 8 perpendicular to said longitudinal direction, which are operatively in contact with corresponding opposite faces of the sheet, when the sheet is arranged in the compression space. According to the invention, the transversal face 8 of the second half-mould 6 comprises a plurality of recesses 9A, 9B arranged symmetrically with respect to an axis X of symmetry, the apparatus 1 comprising moving means connected to said at least one the half-moulds to move it towards the other half-mould to reduce progressively said compression space defined between the half-moulds 5, 6, whereby a plastic deformation of the compact-shaped sheet occurs by migration of material from the bulk of the sheet 3 into said recesses 9 A, 9B, thus generating corresponding projections in the sheet, protruding at symmetrical positions from one of the faces of the sheet, for forming the nose pads 21 and/or side edges 22 of the spectacle frame 2.
The axis X of symmetry divides in two equal portions the opposite sides of the transversal face of the second half-mould having larger extension.
Preferably, the at least one recess 9 A is located in the transverse face 8 of the second half-mould 6 in a position symmetrical with respect to the X axis and substantially intermediate between the sides of the transverse face 8 perpendicular to the X axis (i.e. the sides having longer extension).
Preferably, further recesses 9B are provided, located at opposite end portions of the transverse face 8 of the second half-mould 6, symmetrical with respect to the X axis.
The transversal face 7 of the first half-mould 5 is preferably flat. This ensures that the pressure is applied uniformly to the face of the sheet in contact with the transverse face 7 of the first half-mould 5, i.e. the face 7 opposite to the face of the sheet in contact with the transverse face 8 of the second half-mould 6.
Therefore, the material which flows into the recess 9 is not moved from lateral adjacent zones by a mechanical action (for example by folding). Instead, the material flows into the recess 9 due to sheet 3 compression in the mould.
In other words, in the closed position the half-moulds 5 and 6 form a predetermined closed space which is substantially equal to the space occupied by the sheet, but having a desired shape.
In addition, preferably the transversal face 7 of the first half-mould 5 is configured in such a way to be inserted precisely into a housing defined by the second half-mould 6, whereby said closed space (compression space) is progressively decreased, along with the movement of the half-moulds 5 and 6 one with respect to the other.
In this light, preferably control means are provided (e.g. constituted by an electronic device, per se known), connected to the moving means, to control the stroke imparted to the first half-mould 5 (or to the second half-mould 6) from the moving means, in order to control the extent of reduction of the compression space (by controlling the extent of insertion of the transversal face 7 of the first half-mould 5 into the housing defined by the second half-mould 6).
It should also be noticed that the transversal face 8 of the second half-mould 6 preferably comprises projections 10 at the zones of the sheet 3 intended to be removed in order to make the holes for the nose and for the lenses (that is to say, the projections 10 are positioned on the transversal face 8 of the second half- mould 6 in such a way that they interact with portions of the sheet 3 intended to be removed to make the holes for the nose and the lenses).
In particular, the projections are positioned in zones adjacent to said at least one recess 9.
This promotes and speeds up said migration of material into the recesses 9. The invention provides two embodiments of the recesses 9 A for moulding the nose pads (and in particular their shape and position in the transversal face 8 of the second half-mould 6).
In a first embodiment (illustrated in Figure 3), the transversal face 8 of the second half-mould 6 comprises at least a first and a second recess 9A which are separate from each other, shaped to match the shape of the nose pads of the frame to be made.
In a second embodiment (illustrated in Figure 4), the transversal face 8 of the second half-mould 6 comprises a single recess 9A extending in a zone of the face 8 which interacts with both portions of the sheet 3 intended to form the nose pads of the frame to be made.
The first embodiment has the advantage of allowing substantially complete and final moulding of the nose pads by plastic deformation of the sheet 3 in the mould,
This avoids any further working on the nose pads and therefore makes the apparatus particularly simple and rapid.
In that embodiment, the apparatus 1 is substantially dedicated to a frame model in which the nose pads have a predetermined shape.
In the second embodiment, the apparatus 1 allows frames to be made with nose pads that have any shape. Therefore, in this case the apparatus is particularly versatile. Obviously, to achieve the final shape of the nose pads, in this case minor working of the projection formed in the mould is required, to give the nose pads the desired shape.
Irrespective of the embodiment adopted, the transversal face 8 of the second half-mould 6 also comprises two other recesses 9B in lateral positions, for interacting with the portions of the sheet 3 designed to constitute lateral thickened sections of the frame, for connecting the sidepieces.
Moreover, at least one of the half-moulds 5 and 6 is equipped with ducts 11 configured for blowing air into the space, that is to say, into an interface between the transversal face of the mould and the sheet 3 placed in it.
That facilitates sheet 3 removal from the mould at the end of moulding, that is to say, when the mould is opened.
The second half-mould 6 is preferably positioned with the (shaped) transversal face 8 facing upwards. The first half-mould 5 is positioned above the second half-mould 8 and can move vertically towards and away from it.
Moreover, the second half-mould 6 forms the ducts 11.
This means that the apparatus 1 has a veiy simple structure.
According to another aspect of this invention, the half-moulds 5 and 6 are configured in such a way that the inner space has a transversal dimension which is greater than the transversal dimension of the sheet. That is to say, the transversal faces 7 and 8 of the half-moulds 5 and 6 have a surface area which is greater than that of the corresponding faces of the sheet 3 operatively in contact with them.
Advantageously, that results in transversal stretching and therefore flattening of the sheet 3.
Advantageously, that allows the formation of a preform having a desired predetermined thickness.
It should be noticed that, according to the invention, the sheet 3 has a thickness of intermediate value between the minimum thickness of the preform 2 (in the zones without projections) and the maximum thickness of the preform 2 (in the zones with projections, in particular the nose pads).
The apparatus 1 operates as follows.
The sheet 3 (a block of thermoplastic material having the shape of a parallelepiped, as described above) is placed in an oven and heated until it softens.
The softened sheet 3 is placed between the half-moulds 5 and 6, so that it will interact with their transversal faces 7 and 8.
The half-moulds 5 and 6 are moved towards each other until the mould is in a closed position, forming a predetermined space interposed between the half- moulds, in which the sheet 3 is positioned and therefore compressed.
During compression, the material of which the sheet 3 is made is forced to flow from the bulk of the sheet 3 into the recesses 9 in the second half-mould 6.
The half-moulds 5 and 6 are kept in the closed position for a preset time
(for example five seconds), allowing consolidation of the shape of the deformed sheet 3.
The half-moulds 5 and 6 are moved away from each other to a mould open position.
A fluid (for example air) is blown into the mould, preferably to the interface between the sheet 3 and the second half-mould 6 (that is to say, the stationary, lower half-mould), to promote sheet 3 detachment from the half-mould.
The shaped sheet is subjected to further mechanical working, in particular removal of the portions of sheet 3 positioned at the lenses and the nose, to obtain the frame.
Therefore, this invention also provides a process for making a spectacle frame 2 made of thermoplastic material.
The process comprises the following steps:
- heating a sheet 3 of the thermoplastic material to a predetermined temperature at which the material softens;
- deforming the softened sheet 3 to give it a desired shape and obtain a preform, by compressing the sheet 3 between two half-moulds 5 and 6 having opposite transversal faces 7 and 8;
- removing portions of the preform which are positioned at least at the lenses and the nose.
According to the invention, the transversal face 8 of the second half-mould 6 comprises at least one recess 9A at the frame 2 nose pads 21 and deformation of the sheet 3 comprises a plastic deformation by migration of material from the bulk of the sheet 3 into said at least one recess 9A.
It should be noticed that, after the above-mentioned moulding, there is a step of bending the bridge and fitting (of the known type). Said step comprises again heating to the softening point the parts of the preform to be treated (therefore, in this case, localised or partial heating).
The sheet preferably comprises at least two adjacent zones having different colours, as described above. In contrast, according to the invention, the step of heating the sheet before sheet moulding in the mould preferably comprises heating the entire sheet.
The transversal face 8 of the second half-mould 6 preferably comprises projections 10 at the zones of the sheet 3 intended to be removed in order to make the holes for the nose and for the lenses, for generating an intensified compression in zones of the sheet 3 adjacent to the zones interacting with the recesses 9 (9 A and 9B).
Moreover, after the half-mould 5 and 6 movement step, there is a step of blowing fluid into the space, for separating the deformed sheet 3 from at least one of the half-moulds.
Also after the half-mould 5 and 6 movement step from the open position to the closed position, the half-moulds are kept in the closed position for a predetermined period of time, before moving the half-moulds 5 and 6 away from each other, thus allowing extraction of the preform (that is to say, the deformed sheet 3),
There is also a step of controlling movement of the half-moulds 5 and 6 towards each other, to stop them in the position in which the mould is closed, when predetermined values of suitable parameters are reached.
In particular, the control step comprises stopping closing of the half-moulds when a predetermined pressure value is reached inside the mould (that is to say, the pressure applied to the sheet 3).
Moreover, the half-moulds are stopped in any case when a predetermined minimum value is reached for the distance between them (if the predetermined pressure value has still not been reached).
This avoids the risk of damaging the sheet and allows particularly high levels of uniformity and reliability for the moulding process.
Therefore, this invention offers the following advantages.
First, the invention allows a frame to be made of thermoplastic material with integrated nose pads in a particularly simple and effective way, minimising process waste,
Moreover, the invention allows frames of that type to be made with multicoloured layers which have a particularly attractive appearance, since the projections of the nose pads do not have any irregularities or breaks in the continuity of the contact lines between the different coloured layers.

Claims

Claims
1. An apparatus (1) for making a sheet made of thermoplastic material, for forming a spectacle frame (2) having nose pads (21) and/or side edges (22), comprising:
- an oven configured for heating a compact-shaped sheet (3) of the thermoplastic material to a predetermined temperature at which the material softens;
- a first and a second half-mould (5, 6), at least one of the half-moulds being movable towards the other along a longitudinal direction, wherein the half-moulds (5, 6) are configured to define a compression space for housing the softened compact-shaped sheet (3) and have opposite transversal faces (7, 8) perpendicular to said longitudinal direction, which are operatively in contact with corresponding opposite faces of the sheet, when the sheet is arranged in the compression space, characterised in that the transversal face (8) of the second half-mould (6) comprises at least a recess (9), the apparatus (1) comprising moving means connected to said at least one the half-moulds to move it towards the other half- mould to reduce progressively said compression space defined between the half- moulds (5, 6), whereby a uniformly distributed pressure is applied at the interface between the transversal face (7) of the first half-mould (5) and the sheet and a plastic deformation of the compact-shaped sheet occurs by migration of material from the bulk of the sheet (3) into said recesses (9 A, 9B), thus generating at least a corresponding projection in the sheet, protruding from only one of the faces of the sheet, for forming the nose pads (21) and/or side edges (22) of the spectacle frame (2).
2. The apparatus according to claim 1, wherein the transversal face (7) of the first half-mould (5) is flat.
3. The apparatus according to claim 1 or 2, wherein the transversal face (8) of the second half-mould (6) comprises projections (10) at the zones of the sheet (3) intended to be removed in order to make the holes for the nose and for the lenses.
4. The apparatus according to any of the foregoing claims, wherein the transversal face (8) of the second half-mould (6) comprises at least a first and a second recess (9A) which are separate from each other and shaped to match the desired shape of the frame nose pads (21).
5. The apparatus according to any of the foregoing claims, wherein the second half-mould (6) is equipped with ducts (11) configured for blowing air into said space.
6. The apparatus according to any of the foregoing claims, wherein the second half-mould (6) is positioned with its transversal face (8) facing upwards and the first half-mould (5) is positioned above the second half-mould (6) and can move vertically towards and away from it.
7. The apparatus according to any of the foregoing claims, wherein the half- moulds (5, 6) are configured in such a way that the inner space has a transversal dimension which is greater than the transversal dimension of the sheet (3).
8. The apparatus according to any of the foregoing claims, comprising control means which are connected to an actuator operating on said at least one mobile half-mould for stopping the movement of the two half-moulds (5, 6) towards each other in response to a predetermined pressure value reached on the sheet (3), the space for compressing the sheet (3) being a closed space.
9. A process for making a sheet made of thermoplastic material for forming a spectacle frame (2) having nose pads (21) and/or side edges (22),
characterised by comprising the following steps:
- preparing a first and a second half-mould (5, 6), at least one of the half-moulds being movable towards the other along a longitudinal direction, wherein the half- moulds (5, 6) have opposite transversal faces (7, 8) perpendicular to said longitudinal direction and wherein the transversal face (8) of the second-half mould comprises at least a recess (9 A, 9B) arranged symmetrically with respect to an axis of symmetry;
- heating a compact-shaped sheet (3) of the thermoplastic material to a predetermined temperature at which the material softens;
- placing the softened compact-shaped sheet (3) in a compression space defined between the half-moulds (5, 6), in such a way that said transversal faces (7, 8) are in contact with corresponding opposite faces of the sheet;
- moving said at least one of the half-moulds towards the other half-mould, to progressively reduce said compression space and apply a uniformly distributed pressure at the interface between the transversal face (7) of the first half-mould and the sheet, until the recess (9) is completely filled with the material of the sheet, whereby the softened compact-shaped sheet (3) is deformed to a desired shape to obtain a preform for forming the spectacle frame (2),
whereby the reduction of the compression space causes a plastic deformation of the compact-shaped sheet by migration of material from the bulk of the sheet (3) into said recess (9), thus generating a corresponding projection in the sheet, protruding from only one of the faces of the sheet, for forming the nose pads (21) and/or side edges (22) of the spectacle frame (2).
10. The process according to claim 9, wherein the sheet (3) comprises at least two adjacent zones having different colours.
11. The process according to claim 9 or 10, comprising a step of stopping sheet (3) compression when a predetermined pressure value reached on the sheet (3).
12. The process according to any of the claims from 9 to 1 1, wherein the transversal face (8) of the second half-mould (6) comprises projections (10) at the zones of the sheet (3) intended to be removed in order to make the holes for the nose and for the lenses, for generating an intensified compression in zones of the sheet (3) adjacent to the zones interacting with the recesses (9).
13. The process according to any of the claims from 9 to 12, wherein after the half-mould (5, 6) movement, there is a step of blowing fluid into the space, for separating the deformed sheet (3) from at least one of the half-moulds.
14. The process according to any of the claims from 9 to 13, wherein after the half-mould (5, 6) movement from a position in which said space is open to a position in which it is closed, the half-moulds (5, 6) are kept in the closed position for a predetermined period of time, before moving the half-moulds away from each other to allow extraction of the preform.
15. Spectacle comprising a frame made of thermoplastic material,
characterised in that the frame is a frame made using an apparatus according to any of the claims from 1 to 7 or using a process according to any of the claims from 8 to 14.
PCT/IB2011/050375 2010-02-08 2011-01-28 Apparatus and process for forming a spectacle frame WO2011095917A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITBO2010A000068A IT1397832B1 (en) 2010-02-08 2010-02-08 APPARATUS AND PROCEDURE FOR REALIZING A FRAME OF GLASSES IN THERMOPLASTIC MATERIAL.
ITBO2010A000068 2010-02-08

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ITPD20110306A1 (en) * 2011-09-28 2013-03-29 Safilo Spa METHOD FOR THE MANUFACTURE OF FRAMES FOR GLASSES IN CELLULOSE ACETATE
US9208608B2 (en) 2012-05-23 2015-12-08 Glasses.Com, Inc. Systems and methods for feature tracking
US9236024B2 (en) 2011-12-06 2016-01-12 Glasses.Com Inc. Systems and methods for obtaining a pupillary distance measurement using a mobile computing device
US9286715B2 (en) 2012-05-23 2016-03-15 Glasses.Com Inc. Systems and methods for adjusting a virtual try-on
US9483853B2 (en) 2012-05-23 2016-11-01 Glasses.Com Inc. Systems and methods to display rendered images

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GB645356A (en) * 1947-07-11 1950-11-01 Leslie John Moncrieff Process and apparatus for shaping thermoplastic sheet material to form frames
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Publication number Priority date Publication date Assignee Title
ITPD20110306A1 (en) * 2011-09-28 2013-03-29 Safilo Spa METHOD FOR THE MANUFACTURE OF FRAMES FOR GLASSES IN CELLULOSE ACETATE
US9236024B2 (en) 2011-12-06 2016-01-12 Glasses.Com Inc. Systems and methods for obtaining a pupillary distance measurement using a mobile computing device
US9208608B2 (en) 2012-05-23 2015-12-08 Glasses.Com, Inc. Systems and methods for feature tracking
US9235929B2 (en) 2012-05-23 2016-01-12 Glasses.Com Inc. Systems and methods for efficiently processing virtual 3-D data
US9286715B2 (en) 2012-05-23 2016-03-15 Glasses.Com Inc. Systems and methods for adjusting a virtual try-on
US9311746B2 (en) 2012-05-23 2016-04-12 Glasses.Com Inc. Systems and methods for generating a 3-D model of a virtual try-on product
US9378584B2 (en) 2012-05-23 2016-06-28 Glasses.Com Inc. Systems and methods for rendering virtual try-on products
US9483853B2 (en) 2012-05-23 2016-11-01 Glasses.Com Inc. Systems and methods to display rendered images
US10147233B2 (en) 2012-05-23 2018-12-04 Glasses.Com Inc. Systems and methods for generating a 3-D model of a user for a virtual try-on product

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