EP0631942A1

EP0631942A1 - A plastics cap with a snap hinge

Info

Publication number: EP0631942A1
Application number: EP94610037A
Authority: EP
Inventors: Fritz Gross
Original assignee: Bojco AS
Current assignee: Bojco AS
Priority date: 1993-07-01
Filing date: 1994-06-30
Publication date: 1995-01-04
Also published as: DK78093D0

Abstract

A plastics cap (1) comprising a mounting member (3) and a lid member (4) as well as a snap hinge (2) comprising a single connecting band (5) connected with curved areas on the sides (8, 9) of the mounting member and the lid member, respectively, via film hinges (10, 11). During an opening or closing movement of the cap (1) the lid member (4) passes two bistable positions. The connecting band (5) is provided with weakenings (20) in areas spaced within its longitudinal side edges (12, 13). The connecting band hereby has a particularly good flexing action in use, while the plastics cap (1) will always operate reliably, in particular during cooling to refrigerator temperature.

Description

The present invention concerns a plastics cap comprising a mounting member and a lid member which are interconnected via a snap hinge which extends past their common closing plane and comprises a single connecting band connected at its opposite ends with curved areas on the sides of the mounting member and the lid member, respectively, via film hinges, said opposed film hinges, on their extent from the center of the connecting band out toward its longitudinal side edges, receding from each other with curvatures which substantially correspond to the curvatures of said areas on the sides of the mounting member and the lid member, respectively, seen in cross-section, said lid member passing two bistable positions during an opening or closing movement of the cap.
US patent specification 3 135 456 discloses a cap of the type mentioned above, wherein the mounting member and the lid member may be made of many different types of materials, such as composition paper, plastics, wood, metal, which are joined e.g. by glueing with a resilient connecting band preferably made of a plastics material, such as polyethylene or polypropylene. It is also mentioned in said specification that it is contemplated to make the cap of plastics in one piece with the snap hinge by injection moulding.
However, plastics caps with snap hinges of the above-mentioned type have not yet been mass-produced by the ever increasing package industry in spite of the fact that within the last 10-20 years the package market has taken an ever increasing amount of plastics caps with snap hinges.
Instead, the package industry has exclusively concentrated on the manufacture of plastics caps with snap hinges constructed in such a manner that the lid member passes just one bistable position during an opening or closing movement of the cap. In plastics caps with snap hinges of this type the mounting member and the lid member are connected directly via a main hinge as well as two connecting bands or elements of quite negligible extensibility arranged on their respective sides of the main hinge. During opening and closing of the cap the snap effect is due to the fact that other parts than the connecting bands are flexible and capable of yielding; in practice the main hinge and/or the sides of the mounting member and the lid member with which the connecting bands are connected, yield to provide the desired snap effect.
However, mass-production of plastics caps with snap hinges of this last-mentioned type by injection moulding involves high tool costs owing to the complicated structure with both main hinge and connecting bands, and the tools are moreover particularly subject to damage and breakdown. The reason is that the plastics caps are always moulded in an open position, which therefore leaves a wall in the tool of small thickness and consequently low strength between the sides of the mounting member and the lid member in the open position of these.
In use, the plastics caps with snap hinges of this type frequently malfunction because the snap effect not infrequently diminishes considerably or perhaps disappears completely because of plastic deformation of parts of the cap in use. This may e.g. be due to excessive stretching of the connecting bands. When the package with the plastics cap is taken out for storage in a refrigerator and the cap is opened and closed repeatedly, it frequently happens that the main hinge breaks down, or the connecting bands are torn off at their connection with the sides of the mounting member or the closure member so that the cap completely loses its snap effect to the user's great annoyance. A plastics cap with a snap hinge of this type is known e.g. from EP 0 056 469.
Therefore, there has been a long-felt need for a plastics cap with a snap hinge which can be produced in simple and reliable tools by injection moulding, and which is moreover reliable in use and capable of withstanding repeated opening and closing movements at low temperatures, in particular when the package with the plastics cap is taken directly out of a refrigerator and the cap is subsequently to be opened at once for dispensing of part of the contents of the package.
Consequently, the present use of the plastics cap with a snap hinge of the type mentioned in the opening paragraph in mass-production of it by plastics injection moulding means that a prejudice within the package industry has been overcome.
The plastics cap with a snap hinge according to the present invention is characterized in that the connecting band is provided with weakenings in areas spaced within its longitudinal side edges. The invention thus provides a plastics cap with a snap hinge which both has a simple structure and is always reliable in use with a dependable snap effect of the connecting band only, and which can moreover be mass-produced in simple and reliable injection moulds.
According to the invention, the said areas having weakenings may at least extend near the end of the connecting band which is connected with the lid member, so that the film hinge of the lid member will be activated first, thereby causing the lid member to assume the correct position when the lid member is moved down into engagement with the mounting member during closing.
Further, according to the invention, the weakenings may be provided as film hinge like reductions in thickness which extend between adjoining parts of the connecting band of substantially uniform thickness, thereby providing a particularly good and reliable flexing action of the connecting band during opening and closing of the cap.
Further, according to the invention, the weakenings may comprise film hinge like reductions in thickness which extend longitudinally of the connecting band, resulting in a particularly simple connecting band.
Moreover, according to the invention, the weakenings may comprise film hinge like reductions in thickness which extend transversely to the connecting band. The longitudinal and/or transverse film hinge like reductions in thickness of the weakenings may be mutually parallel in a particularly expedient manner according to the invention.
Further, according to the invention, the transverse film hinge like reductions in thickness of the weakenings may extend across the longitudinal center of the band and between a pair of longitudinal film hinge like reductions in thickness, spaced within their respective adjoining side edges on the connecting band.
According to the invention, the weakenings may also be provided as areas of a lower thickness than areas located in adjoining longitudinal relationship with the side edges of the connecting band, so that the connecting band will be stretched in a particularly expedient manner and therefore does not protrude beyond the sides of the lid member and the mounting member when the cap is closed.
According to the invention, the weakenings of the lowest thickness may be located at the longitudinal center of the band in a particularly expedient manner. Finally, according to the invention, the connecting band, seen in cross-section transversely to its longitudinal extent, may have an evenly decreasing thickness in a direction from the side edges inwardly toward the longitudinal center of the band.
The invention will be explained more fully below with reference to particularly preferred embodiments as well as the drawing, in which

fig. 1 is a lateral view in longitudinal section through the axis of symmetry of a circular plastics cap having a snap hinge in the open position,
fig. 2 is a view analogous to fig. 1 of the plastics cap having a snap hinge in the closed state,
fig. 3 is a top view of the same in the open state,
fig. 4 is a cross-section through the connecting band of the cap of fig. 3, said band being comprised by the snap hinge,
fig. 5 is an analogous view of another embodiment of a connecting band,
fig. 6 is a view of a further embodiment of the connecting band, analogous to the view of fig. 3,
fig. 7 is an analogous view of a last embodiment of the connecting band.

The plastics cap 1 shown in fig. 1 comprises a mounting member 3 and a lid member 4 which are interconnected via a snap hinge 2 extending past the common closing plane L of the parts 3, 4 in the closed state of the plastics cap, see fig. 2. The plastics cap 1 is manufactured by injection moulding in closed moulds and in the open position of the cap shown in fig. 1.
In the shown embodiment the snap hinge 2 comprises a single connecting band 1 which is connected at its opposite ends 6, 7 with curved areas on the sides 8, 9 of the mounting member and the lid member 3, 4, respectively, via film hinges 10, 11.
On their extent from the center of the connecting band 5 out towards its longitudinal side edges 12, 13, the opposite film hinges 10, 11 extend away from each other with curvatures which substantially correspond to the curvatures of the said areas 8, 9 on the sides 8, 9 of the mounting member and the lid member, respectively.
The shown embodiment of the plastics cap involves a plastics cap of circular cross-section, and the film hinges of the connecting band 5 extend with the same radius of curvature as the radius of curvature of the circular cross-section of the cap 1.
During an opening or closing movement of the cap the lid member 4 passes two bistable positions corresponding to first activating one film hinge 10 and then the other film hinge 11, or vice versa.
The length 1 of the connecting band 5 need not correspond to the full heigth of the cap 1, but should be sufficient to provide a sufficient length of flexible plastics material in the connecting band between the film hinges 10, 11, so that the band 5 has no difficulty in curving in and out during opening and closing of the cap 1.
The width b of the connecting band 5 depends on the angular boundary β, which should preferably be between 30 and 60°, but not above 90°. In the shown embodiments the angle β is 42°.
Experiments have shown that the length/width ratio 1/b of the connecting band 5 should be between 1/5 and 1/2 and preferably about 1/3 like in the shown embodiment.
The lid member 4 may internally be provided with a central ring 14 having an annular internal groove 15, which engages with an external annular bead 16 on the dispensing spout 17 of the mounting member 3 in the closed state of the lid member 4. This ensures in an expedient manner that the lid member 4 is always intimately engaged with the mounting member 3 in the closed state.
According to the invention, the connecting band 5 comprises weakenings in areas extending within the longitudinal side edges 12, 13 of the connecting band 5. The weakenings may expediently be provided as parallel, longitudinal film hinge like reductions in thickness 20 extending between the film hinges 10, 11 at the ends of the connecting band 5. This ensures that it is particularly easy for the connecting band 5 to curve in or out during opening or closing of the cap 1, so that the film hinges 10, 11 will just be loaded to a very small degree. This embodiment has been found to be particularly expedient as regards the mode of operation and service life of the snap hinge when the plastics cap 1 has been cooled to refrigerator temperature and is to be opened or closed repeatedly.
The film hinge like reductions in thickness may extend in many different orientations on the connecting band, provided that a more flexible and resilient state is obtained for the connecting band in relation to a connecting band having a constant thickness throughout.
As shown in fig. 6, the film hinge like reductions in thickness 20' may e.g. extend transversely to the longitudinal direction of the connecting band 5'.
As shown in fig. 7, the transverse film hinge like reductions in thickness 20' might also be restricted in their extent by longitudinal film hinge like reductions in thickness 20 which extend in internal spaced relationship with the side edges of the connecting band 5''.
Fig. 5 shows a further expedient embodiment in which the connecting band 5''', seen in cross-section transversely to its longitudinal extent, has an evenly decreasing thickness in a direction from the side edges 12', 13' inwardly toward the longitudinal center of the band 5'''. The greater thickness of the side edges 12', 13' of the connecting band 5''' hereby ensures that the connecting band 5''' is nicely stretched and does not protrude much beyond the sides of the lid member and the mounting member 4, 3, respectively, in the closed state of the cap 1.
In relation to a connecting band of a constant and uniform thickness, areas of weakenings should at least extend near the end 7 of the connecting band 5 which is connected with the lid member 4. This ensures that the film hinge 11 of the lid member 4 will be activated before the film hinge 10 of the mounting member 3 during closing of the cap 1, so that the lid member 4 will always be engaged correctly over the mounting member 3. In the embodiments shown in figs. 3, 4, 6 and 7 the number of film hinge like reductions in thickness might simply just be increased near the end 7 of the connecting band 5 which is connected with the lid member 4.
It should also be mentioned that the curvature of the film hinge 10 on the mounting member 3 might be amended somewhat from the curvature of the area on the mounting member across which the film hinge 10 extends, i.e. the curvature of the circular cross-section of the mounting member, so that during opening and closing of the cap 1 the film hinge 10 will operate somewhat more "tightly" than the film hinge 11 for correct engagement of the closure member 4 with the mounting member 3 during closing.
Many modifications can be made within the scope of the invention. Thus, the weakenings might be provided in many different ways, e.g. as larger areas of low thickness seen in relation to the rest of the connecting band; the essential feature is that the connecting band is provided with weakenings seen in relation to a connecting band of uniform even thickness. However, the connecting band might also be provided with up to several perforations.

Claims

A plastics cap (1) comprising a mounting member (3) and a lid member (4) which are interconnected via a snap hinge (2) which extends past the common closing plane (L) of the members (3, 4) and comprises a single connecting band (5), which is connected at its opposite ends (6, 7) with curved areas on the sides (8, 9) of the mounting member and the lid member (3, 4), respectively, via film hinges (10, 11), said opposite film hinges (10, 11), on their extent from the center of the connecting band (5) out toward its longitudinal side edges (12, 13), receding from each other with curvatures which substantially correspond to the curvatures of said areas of the sides (8, 9) of the mounting member and the lid member (3, 4), respectively, seen in cross-section, said lid member (4) passing two bistable positions during an opening or closing movement of the cap (1), characterized in that the connecting band (5) is provided with weakenings (20) in areas spaced within its longitudinal side edges (12, 13).
A plastics cap according to claim 1, characterized in that said areas having weakenings extend at least near the end (7) of the connecting band (5) which is connected with the lid member (4).
A plastics cap according to claim 1 or 2, characterized in that the weakenings are provided as film hinge like reductions in thickness (20) which extend between adjoining parts of the connecting band (5) of substantially uniform thickness.
A plastics cap according to claim 3, characterized in that the weakenings comprise film hinge like reductions in thickness (20) which extend longitudinally of the connecting band (5).
A plastics cap according to claim 3 or 4, characterized in that the weakenings comprise film hinge like reductions in thickness (20') which extend transversely to the connecting band (5').
A plastics cap according to claim 4 or 5, characterized in that the longitudinal and/or transverse film hinge like reductions in thickness (20; 21') of the weakenings are mutually parallel.
A plastics cap according to claim 4 and 5 or 6, characterized in that the transverse film hinge like reductions in thickness (20') of the weakenings extend across the longitudinal center of the band (5'') and between a pair of longitudinal film hinge like reductions in thickness (20) spaced within their respective adjoining side edges on the connecting band (5'').
A plastics cap according to claim 1 or 2, characterized in that the weakenings are provided as areas which have lower thicknesses than areas located in adjoining longitudinal relationship with the side edges (12', 13') of the connecting band (5''').
A plastics cap according to claim 8, characterized in that the weakened areas of the lowest thickness are located at the longitudinal center of the band (5''').
A plastics cap according to claim 8 or 9, characterized in that the connecting band (5'''), seen in cross-section transversely to its longitudinal extent, has an evenly decreasing thickness in a direction from the side edges (12', 13') inwardly toward the longitudinal center of the band (5''').