US 3654074 A
Description (OCR text may contain errors)
April 4, 1972 JACQUELIN 3,654,74
MANUFACTURE OF A PAPER SHEET HAVING A UNIFORM NC! BY PROJECTION OF A SLURRY UNDER PRESSURE CONTINUOUS CONSISTE Filed March 18, 1.970
4 Sheets-Sheet l NCY BY PROJECTION OF A SLURRY UNDER PRESSURE G. JACQUELIN April 4, 1972 CONTINUOUS MANUFACTURE OF A PAPER SHEET HAVING A CONSISTE Filed March 18, 1970 3,654,074 uuIFonu G. JACQUELIN April 4, 1972 OF A PAPER SHEET HAVING A CONTINUOUS MANUFACTURE CONSISI'ENCY BY PROJECTION OF A SLURRY UNDER PRESSURE Filed March 18, 1970 4 Sheets-Sheet 5 April 4, 1972 JACQUELIN 3,654fi74 CONTINUOUS MANUFACTURE OF A PAPER SHEET HAVING A UNIFORM CONSISTENCY BY PROJECTION OF A SLURRY UNDER PRESSURE Filed larch 18, 1.970
4 Sheets-Sheet 4- United States Patent 3,654,074 CONTINUOUS MANUFACTURE OF A PAPER SHEET HAVING A UNIFORM CON SISTENCY BY PROJECTION OF A SLURRY UNDER PRESSURE Guy Jacquelin, Grenoble, France, asslgnor to Centre Technique de IIndustrie des Papiers, Cartons et Celluloses, Grenoble-Gare, Isere, France Filed Mar. 18, 1970, Ser. No. 20,611 Claims priority, applicfiaisorzills rance, Mar. 20, 1969, Int. Cl. D21f 11/00, 11/04 U.S. Cl. 162--213 14 Claims ABSTRACT OF THE DISCLOSURE A method of continuous manufacture of a sheet or element of regular consistency, comprising the uniform depositing at high speed of a liquid, pasty or fibrous-tenture product on one or more Wide travelling bands, said band being deformed laterally during a part of its travel so as to follow, at least in part, the internal shape of a surface of revolution inside which the product is deposited on the band, said method comprising the distribution of said product on said band by projecting the product under pressure from one or more nozzles located close to the axis of said surface, whereby all points of the travelling band are supplied in identically the same manner from the source of said product. The invention further covers the devices employed in carrying the method into effect.
The present invention relates to a continuous method of manufacture of a sheet or an element formed by a uniform fabric obtained by depositing a liquid, pasty or fibrous-texture product on a wide travelling band.
Sheets or elements of this kind, composed of a uniform fabric, may be for example articles such as paper or socalled non-woven fabrics. The use of these articles necessitates that their structure should be very uniform and of constant thickness.
Now, the known methods of manufacture of these sheets or elements do not make it possible to obtain the qualities indicated above in a satisfactory manner.
In fact, for the manufacture of these sheets or elements there is always employed a filtering open-mesh band, on which is distributed a product generally consisting of fibres in suspension in a liquid. The fibres are deposited on the band and the liquid, filtered through this latter, is evacuated. The difficulties of formation of a structure of the sheet or element which is very uniform and of constant quality become increasingly great as the width of the band employed increases, and with the known methods it is very difiicult to obtain a uniform distribution of the basic product on the band.
A first conventional method, which may be termed the pouring method, consists of pouring the product on a flat travelling band from a distribution tank provided with a slot through which flows a curtain of the product which covers the band from one edge to the other, transversely to its direction of travel.
With this method, it is particularly difficult to control the flow of the product, and it will be understood that a given material can only be adapted to a relatively narrow range of production rates. In fact, the product coming into the distribution tank through the supply pipe has to pass over different distances in order to reach the various points of the formation band of the sheet or element. This necessity presents complicated hydraulic problems which can only be satisfactorily resolved, for a given circuit, over a limited range of flow-rates. Outside this range, turbulence and faulty distribution occur, due to the fact that the source of supply of product to the tank is not equidistant from the various points on the width of the forming band.
In addition, such a method of distribution of the product makes it difficult to obtain uniform laying of the product on the band, and the sheet formed inevitably exhibits defects (over-thicknesses, lumps, etc.), resulting from the unsatisfactory dispersion of the fibres in the product tobe distributed.
In order to find a remedy for the major disadvantages of this method, and in order to restrict the bulk of the equipment employed, a known alternative form of this method consists of utilizing a deformable travelling band which is led to be deformed by passing into a hollow body, and to cause the product to fall by gravity on a disc housed inside the hollow body and held in. fluid-tight contact against the deformed band, the liquid being extracted from the product by suction and filtration through the meshes of the band.
While this alternative form of the pouring method makes it possible to control the flow of product and its distribution more easily as a function of the speed of travel of the band, and thus makes it possible to manufacture sheets at relatively high speeds, it remains incapable of remedying the other defect, namely the regularity of the final structure of the sheet, since in fact, the mass of product poured on to the disc is relatively stagnant and does not permit perfect dispersion of the fibres throughout all the product, these fibres having on the contrary a tendency to become agglomerated in lumps.
There should be mentioned, furthermore, another known method utilized for the distribution of the product on a fiat travelling band. This method consists of replacing the linear supply by pouring, by a supply from a nozzle with a to-and-fro alternating movement, emitting a small round jet; this method may be termed a projection method. The advantage of this method resides in the fact that the projection nozzle ensures an excellent dispersion of the fibres and prevents the deposit on the band of tufts of fibres, which was previously the case in the pouring method.
In addition, the nozzle then permits suitable regulation of the flow-rates of the product as a function of variable speeds of the band, but this method of distribution in which the nozzle is subjected to a to-and-fro movement from one edge of the band to the other, results in a non-uniform distribution of the product over the whole width of the band, due to the differences in speeds of the nozzle above the various points of the travelling band.
In addition, this alternating method of distribution presents mechanical problems for the manufacture of sheets at high speed.
The object of the present invention is to obtain at high speed a uniform deposit on a wide moving band of a liquid, pasty or fibrous-texture product, without necessitating the provision of complicated mechanical devices.
To this end, the present invention contemplates a method of distribution of the product, in which there is employed an endless deformable band which is caused to be laterally deformed over a portion of its travel and to follow all or part of a regulated surface or a surface of revolution having its generator lines parallel to the direction of movement of the band, this method being characterized in that the product to be distributed is deposited on the band by projection under pressure from at least one jet of product from a source located close to the centre of the directrix of the surface of revolution. In this way, all the points of the band are fed in identically the same manner from this source.
It will be understood that the flow-rate of the source will be a function of the speed of ejection of the product, and may therefore be easily regulated. In addition, the elfect of projection will produce an ideal dispersion of the fibres in the product and in consequence a uniform distribution of the fibres on the band.
In order to pass into the regulated surface, the deformable band is curved and provisionally takes the shape of this surface, which serves as a guide. The shape of this surface has a certain symmetry, all the points of the band being located substantially at the same distance from the source of distribution, which enables a continuous and uniform distribution of the product to be obtained.
The jet of the product may have the form of a radial beam, and in this case, the point source will be caused to rotate on itself in order that the beam can sweep over the entire width of the band.
According to an alternative form, the jet may have the shape of a peripheral layer extending from the axis of the regulated surface over the whole transverse section of this surface, and in this case the source may be fixed, if so required.
In the case of use of a single band, at the outlet of the said regulated surface, the sheet or fabric formed may be slit along the edges of the band and will accompany the straightening action of this latter back to the fiat form, before being separated from the band. However, in the case of a sheet of sufiicient strength, this may also be extracted in the form of a cylindrical sheath. It is then separated from the carrier band immediately after its outlet from the surface of revolution. The cylinder obtained may then be cut to lengths and then each section can be cut along a generator line if it is desired to obtain flat sheets.
Furthermore, in order to limit the deformation stresses in the carrier band and to reduce the final width of the sheet, use may advantageously be made of two identical bands travelling at the same speed and located face to face in the interior of the surface of revolution, the said bands extending over all or part of this surface. In this case, the sheet extracted is cut along the edges of the two bands, thus forming two separate sheets, each of which may be conveyed by the band in contact with which it has been formed, or alternatively they may be transferred on to a single band.
The invention also relates to a device for the continuous mariifacture, especially at high speed, of uniform sheets or fabrics, from a liquid, pasty or fibrous-texture product. This device comprises at least one deformable endless band supported, guided and driven by appropriate means, and a chamber with an internal surface of revolution in which the band passes while being deformed, the said device further comprising means for distribution by projection of the product, having at least one projection orifice directed towards the surface of the band, the axis of these means being arranged close to the axis of the said chamber, or coincident with this latter. These distribution means may have a diameter in the vicinity of that of the chamber.
During the part of the travel in which the product is distributed--that is to say in the interior of the chamber this device permits the creation of a uniform distribution about an axis and the supply to all the points of the band under the same conditions, which is necessary in order to obtain a uniform distribution of the product.
According to a simple form of construction, the chamber of the device is constituted by a cylinder, and there is employed a single band having a width substantially equal to the circumference of the internal wall of the cylinder.
According to an alternative form, the device may be provided with two identical bands of width substantially equal to the half-circumference of the cylinder.
According to another alternative form, the internal surface of the chamber has a director curve with a large 4 radius of curvature, defining a small deformation of a number of bands travelling through the said chamber.
The projection nozzle or nozzles with which the device is provided in a first form of construction, have at least one ejection orifice of small section capable of emitting a radial point jet and the nozzle is driven in rotation in a continuous manner and at constant speed so as to permit a sweeping movement over the entire width of the band. The flow-rate, the speed and/or the direction of rotation of the nozzle or nozzles to be regulated with accuracy, these various parameters determining the value of the emission speed of the jet and the intersecting arrangements of the projected systems on the manufactured sheet.
In accordance with a second form of construction, the nozzle or nozzles are provided with ejection orifices of small section capable of emitting a peripheral layer which forms an annular liquid film of the product to be deposited on the band. In this case, the nozzle or nozzles may remain fixed, if so desired.
The use of nozzles is very advantageous, since in addition to the advantages already mentioned, they can preferably be fixed on orientatable means, intended to give the possibility of varying and regulating the incidences of the emitted jets.
It is known that the speed of emission of the jet and its incidence are essential parameters which determine the anisotropic characteristics of the sheet or fabric obtained. The device according to the invention thus enables these characteristics to be varied and regulated. Furthermore, the device according to the invention is usefully equipped with means for recovering excess quantities of products projected; these means may simply consist of a receptacle in the form of a funnel, in which the edge of the flared side is provided with a flexible joint coming into contact with the deformed band or the internal surface of the chamber. The excess product streams along this band or this surface and is finally collected by means of the flexible joint, in the receptacle of funnel shape, from which it is evacuated by a conduit before being re-cycled.
The invention finally relates to the application of the method and the device to the manufacture of a sheet of paper, the product to be distributed being a paper pulp.
The description which follows below of this latter application, given by way of example, will enable the principle and the advantages of the invention to be better understood, reference being made to the accompanying drawings, in which:
FIG. 1 is a simplified view in perspective of a device according to the invention;
FIG. 2 shows diagrammatically a test carried out by means of a cylinder of paper slit along part of its height;
FIG. 3a is a diagrammatic section of a chamber according to the invention, taken along an axial plane;
FIG. 3b shows an alternative form of distributor intended for mounting in a chamber according to the invention, in an enlarged view;
FIGS. 4 and 5 show diagrammatically two methods of extraction of sheets of paper formed in the devices according to the invention;
FIG. 6 shows a second alternative form of construction of the supply mechanism for a device according to the invention.
In FIG. 1 is shown a parallelepiped frame, open on its front face and carrying rollers 2, 3, 4 and 5, identical and capable of being driven at equal speed in rotation about their own axes, by conventional driving means (not shown). These rollesr 2, 3, 4 and 5 guide, support and drive an endless deformable canvas band 6. This band 6 is made up of two series of perpendicular strands forming flexible meshes. These elements are capable of being deformed and sliding on each other, so that the band can be subjected to very considerable deformation.
In the vertical rising portion, the band passes into a cylindrical chamber 7, which is fixed to the frame 1, for example by means of collars such as 8.
As shown in FIG. 3a, this chamber 7 is constituted by an internal wall 9, filtering and cylindrical, and by an outer wall 10. The circular section of this internal wall 9 has a length equal to the width of the band 6. In contact with this internal wall 9, the band 6 is deformed and follows the cylindrical form of this latter, the two edges of the band coming into contact with each other along a generator line of this wall. In addition, suction means (not shown) are capable of acting through a conduit 11 so as to create a depression in the annular space comprised between the internal wall 9 and the external wall 10.
In addition, the chamber 7 is provided at its base with a funnel-shaped receptacle 12, extended by a conduit 13. On the upper edge of this receptacle 12 is fixed a flexible joint 14 coming closely into contact with the surface 9.
Finally, the chamber 7 is equipped with a nozzle 15 of the type permitting the ejection of a jet of fluid, of a thermo-plastic material for example, which cools in the form of a thread. This nozzle, utilized in this case to project paper pulp, is mounted on conventional orientatable means shown dagrammatically at 16, for example a ball-joint permitting regulation of the angle of incidence of the jet with respect to the vertical, and provided with any suitable locking means enabling the ball-joint to be kept locked after adjustment. In addition, this nozzle may be given a continuous movement of rotation about the axis of the chamber by means of a driving device indicated at 17, and it is supplied with fluid through a conduit 18. The driving device may be constituted by a small motor.
It will however be understood that the drive may be effected by an external motor coupled to a shaft arranged in the axis of the chamber, the device 17 being then a driving system, with gears for example.
In order to form a sheet 21 having given anisotropic characteristics, the speed of travel of the band 6 is regulated, the orientation of the nozzle and the speed of rotation of this latter are adjusted, together with the flowrate of paper pulp in the conduit 18, to predetermined values, obtained for example by means of charts.
It should be noted that the ratio of the speed of rotation of the nozzle 15 to the speed of travel of the band 6 should not be less than a certain value, if it is desired to obtain a sheet having a continuous surface. In the case where this condition is not observed, there would be formed on the band a helix of pulp having a more or less large pitch, depending on the value of the above-mentioned ratio.
In an alternative form, FIG. 3b shows a distributor intended for mounting along the axis of a chamber. This distributor is constituted by a conduit 22, at the inner extremity of which is fixed a rod 23. This rod is threaded on its portion which is outside the conduit 22, so as to permit the fixing on this portion of a disc 24 having an adjustable height, and arranged to co-operate with the flared edge of the conduit 22 in order to regulate the flow-rate and also the angle of incidence of the emitted jet. To this end, the disc may be flat, as shown, or it may be incurved.
This distributor thus projects a fluid screen which has a symmetry of revolution with respect to the axis of the chamber and has the advantage that it does not comprise any moving part.
This device is particularly advantageous in discharging an annular screen of paper pulp which flows in a uniform stream carried away by the rising band. It will be noted that the diameter of the annular outlet of the distributor may be variable and in particular it may be in the vicinity of the diameter of the chamber. The suction produced through the band 6 and the wall 9 enables the deposit of fibres in suspension to be accelerated, and permits the evacuation of the carrier fluid. The excess quantities of paper pulp flow over the band 6 and are then recovered at the base of the chamber 7 in the funnel 12 by means of the flexible joint 14.
At the outlet of the chamber 7 (see FIG. 1) the sheet formed is slit and the band 6 is caused to return to its flat form by means of the roller 2. This change of shape must obviously not interfere with the distribution of paper pulp on the band, in particular by creating stresses inside the sheet formed. FIG. 2 makes it easy to see that the stresses developed in the sheet during the course of this change of shape are entirely negligible. This figure shows a cylinder 25 of paper slit from a point 26 along one of its generator lines. It is found that the slit cylinder opens naturally and tends to give a flat band of paper at a very short distance from the point 26.
In order that the stresses developed in the sheet conveyed on the band 6 may be negligible, it is therefore only necessary to place the roller 2 in such manner that it imposes on the band 6 a change of shape which would be natural for a sheet alone. The association of FIGS. 1 and 2 shows that this condition is verified for the device shown in FIG. 1.
After its passage over the roller 2, the sheet of paper 21 is separated from the band 6 by a press 27, and is directed towards the conventional devices which will subject it to all the necessary subsequent treatments.
The advantage of such a device is clear which, during the distribution, creates symmetry of revolution around the distributor and, by supplying all points of the band under the same conditions, makes it possible to obtain, even at high speed, a perfectly uniform distribution of the paper pulp. In addition, a device of this kind provides the possibility of obtaining a sheet having the desired anisotropic characteristics.
Numerous alternative forms may be envisaged for the device described, which obviously do not depart from the scope of the invention. For example, the device may comprise two bands 28 and 29 in FIG. 4, 30 and 31 in FIG. 5, each having a width equal to the length of the halfcircumference of the cylindrical chamber. This arrangement makes it possible to reduce the deformation of the bands employed. At its outlet from the chamber, the sheet formed is cut along the edges of the two bands, thus giving two separate sheets 32 and 33 in FIG. 4, 34 and 35 in FIG. 5. In the device shown in FIG. 4, each of the sheets is conveyed by the band on which it has been formed, before being separated from this band. On the other hand, in the device of FIG. 5, the sheet 35 formed on the band 31 is transferred by the press 36 to the band 30, on top of the sheet 34.
Devices may also be envisaged which comprise a number of multiple bands, or which are provided with chambers having varied interior surfaces: (surface with elliptical directrices, etc.) without departing from the scope of the invention.
Furthermore, in connection with FIG. 3b, there has been described an annular distributor of fairly small diameter. It would of course be possible to contemplate. distributors having a fixed or adjustable diameter which could vary between a point size and the dimensions of the formation chamber. In addition, the annular sheet of fluid passing out of the distributor could be given a movement of rotation about its axis.
On the other hand, although there has been shown in the drawings a device in which the nozzle 15 or the distributor 24 comprise a single orifice or projection slot, it will be understood that it would be possible to provide a nozzle or a distributor with a number of orifices without departing from the scope of the invention.
Similarly, in an alternative form, there could be provided a plurality of nozzles superimposed along a common vertical shaft, as shown in FIG. 6. In this alternative form, on an axial shaft 40 is mounted a first tube 41, terminating at its upper portion in a rotating head 42 provided with curved radial arms 43. These arms 43 have a central channel 44 communicating with the interior 45 of the tube 41 into which is sent a first flow of pulp under pressure, in the direction of the arrows 46.
The tube 41 is surrounded by a second tube 4-9 provided with a head 48 having identically the same structure as the head 42, and into which is sent a second flow of pulp 47.
The free extremity of each of the rotating arms 43 is open towards the exterior, for example in the form of a vertical slot in order to permit the evacuation of the pulp on to the band 50 passing through the chamber 51, which is also provided at its lower portion with a recovery receptable shown diagrammatically at 52 and similar to the funnel 12 of FIG. 3a.
Rotation of the revolving heads 42 and 48 may be effected by driving in rotation the central shaft 40 by an external motor (not shown), and in this case the shaft 40 will be coupled for rotation to the heads 42 and 48 by any appropriate couplings. The rotation of the heads could be effected in opposite directions, the arms of one of the heads being oriented in the opposite direction to the arms of the other head.
It will however be understood that the structure described may operate by reaction like a rotating garden spray, the heads 42 and 48 rotating under the effect of the pressure of the pulp. In this case, the shaft 40 will be fixed and the heads 42 and 48 would be freely mounted on this shaft, thereby avoiding the use of any source of motive power for the rotation of the heads 42 and 48.
In addition, the angle of incidence of the jets emitted by the arms 43 may be easily adjusted if these arms are mounted so as to be able to turn in the heads 42 and 48, the arms being maintained in the inclined position desired by any suitable locking means.
The above arrangement may be particularly advantageous when it is desired to distribute in two stages the product intended to form the sheet. Similarly, it will be possible to utilize streams of pulp 46 and 47 of different natures. In this latter case, the filtration chamber 50 will preferably be constituted by two superimposed units identical to the chamber 10, as shown in FIG. 6, and each provided with an evacuation pipe for the re-cycling of the liquid extracted from the device.
It will of course be understood that the invention is not restricted to the terms of the foregoing description but that on the contrary it comprises all the alternative forms within the scope of those skilled in the art.
What I claim is:
1. A method of uniformly depositing especially at high speed a suspended fibrous product on at least one wide travelling band for the purpose of forming a continuous sheet of uniform consistency, said method comprising deforming said band laterally along part of its travel so as to take the internal form of a cylindrical surface inside Which the depositing of said product takes place, and distributing said product on said deformed band by projection under pressure of at least one jet of said product derived from a source located in the vicinity of the center of the directrix of and within said cylindrical surface, whereby all points of said band are supplied in identically the same manner from said source, said cylindrical surface being formed when the band is travelling in a vertical direction.
2. A method as claimed in claim 1, in which said product is distributed in the form of a radial punctual jet and said source is rotated about its own axis so that said punctual jet sweeps over the entire width of said band.
3. A method as claimed in claim 1, in which said product is projected in the form of a peripheral sheet extending from the source over the whole transverse section of said cylindrical surface, which surface constitutes a surface of revolution.
4. A method as claimed in claim 2, including adjusting the angle of incidence of said jet with the surface of said band in order to regulate the anisotropic characteristics of the final sheet.
5. A method as claimed in claim 3, including adjusting the angle of incidence of said peripheral sheet with the surface of said band in order to regulate the anisotropic characteristics of the final sheet.
6. A method as claimed in claim 1, in which, at the outlet of said cylindrical surface of revolution, the sheet formed is slit along the edges of said band on which it is supported, and in which the profile of said band changes, when moving away from said surface to a flat profile in such manner that said sheet is subjected to the same change in form as said band without the production of appreciable stresses.
7. A method as claimed in claim 1, in which in the case where said sheet formed is sufficiently strong it is extracted from said cylindrical surface of revolution in the form of a cylindrical sheet.
8. A method as claimed in claim 7, and further com prising laterally deforming two bands which together form the cylindrical surface of revolution wherein two sheets are formed at the outlet of said surface of revolution, each of said sheets being conveyed by the band in contact with which it has been formed.
9. A method as claimed in claim 7, and further comprising laterally deforming two bands which together form the cylindrical surface of revolution wherein two sheets are formed at the outlet of said surface of revolution, both said sheets being transferred on to one of said bands.
10. A device for continuous manufacture especially at high speed of sheets of uniform consistency, from a suspended fibrous product, said device comprising at least one deformable endless band supported guided and driven especially at high speed by appropriate means, and a chamber with an internal surface of revolution into which said band passes and is thereby deformed, said device comprising product-distributing means including a nozzle mounted within the chamber for distributing said product and provided with a projection orifice directed towards the surface of said band and disposed in the vicinity of the axis of said chamber, the axis of said chamber being vertical.
11. A device as claimed in claim 10, in which said nozzle is provided with at least one orifice for emitting a punctual jet, and means for driving said nozzle in rotation.
12. A device as claimed in claim 10, in which said nozzle is provided with at least one peripheral projection slot for emitting a peripheral sheet which forms an annular curtain of the product to be deposited on said band.
13. A device as claimed in claim 10, in which said nozzle is fixed on orientatable means for varying and regulating the angle of incidence of the projection of said product with respect to the direction of travel of said band.
14. A device as claimed in claim 10, and further comprising at the base of said chamber means for recovcering excess quantities of said projected product, said means consisting of a receptacle in the form of a funnel having its wider edge fitted with a flexible joint which comes into contact with said deformed band.
References Cited UNITED STATES PATENTS 6/1957 Muller l62295 X l0/1965 Grauss et al 162295 X US. Cl. X.R.