LU86729A1 - PREPRESSING APPARATUS AND METHOD - Google Patents

Description

Prepressing apparatus and method.

The present invention relates generally to the production of laminated panes and, in particular, to an improved apparatus for prepressing panes of the anti-laceration type intended, in particular, for use in motor vehicles.

GM.YD.SF - 1 - 13-5808 ► * "Μ

In the early stages of the automotive industry, simple sheets of ordinary glass were used as windshields. When it appeared that this type of windshield constituted a considerable safety hazard, the simple sheets of ordinary glass were replaced by simple sheets of heat-treated or toughened glass. Then, when laminated safety glass was developed to reduce the severity of laceration injuries, its use in automobile windshields has increased significantly until today when almost all windshields automobiles are made of a certain type of laminated glass.

Laminated glass of the type used in vehicle windshields is typically formed from two sheets of glass joined to each other by a thin interlayer of plastic material, for example, a sheet of polyvinyl butyral. In the event of an impact on a windscreen made of laminated glass sufficient to break the glass, the intermediate plastic layer intervenes to adhere the glass fragments to each other, thereby reducing the risk of injury to a conductor or a passenger by flying fragments of glass or by contact with the windshield. Other advances with this type of laminated glass, such as those described in United States Patent No. 3,231,461, have resulted in laminated windshields having better penetration resistance. As a result, with the ever-increasing awareness of the need for increased safety precautions, efforts have been made and are being made to significantly reduce the risk of injury from automobile windshields. .

Recently, it has been found that the addition of a GM.YD.SF - 2 - 13-5808 '', Μ second layer of plastic bonded to the internal glass surface of the laminated windshield further increases the efficiency of the windshield from the safety point of view. The second layer of plastic has typically been referred to as a shredding protective layer because the additional layer of plastic has been found to significantly reduce the number and severity of laceration injuries to people thrown against the windshield in all areas. impact conditions. In addition, it has been found that the anti-laceration protection, when produced under certain manufacturing conditions, improves the ability of the laminated windshield to slow the movement of a person projected against the windshield, while increasing the resistance to penetration of the windscreen, compared to that of conventional laminated windscreens. In addition, the anti-laceration protection reduces the quantity of flying glass fragments and thus the injuries of the occupants of an automobile following objects which can be thrown against the windshield from gangways placed above the roadway or from any other place outside the vehicle.

An example of an automobile windshield which includes, as part of its laminated structure, an anti-laceration protection bonded to its internal glass surface, is described in United States Patent No. 4,242,403. In this patent, the anti-laceration protection comprises a multilayer body resistant to penetration comprising an inner layer of relatively flexible extensible plastic material such as polyvinyl butyral, which is bonded to the internal surface of the windshield, an intermediate layer of plastic material. more durable such as polyester and an outer coating in GM.YD.SF - 3 - 13-5808 A- v abrasion resistant material.

While the effectiveness of a laminated windshield with anti-laceration protection is obvious, very few vehicles use such a windshield. The main reason for this limited use lies in the difficulties encountered when an attempt has been made to manufacture a windshield with anti-laceration protection on an industrial basis. In the automotive industry, the standards of windshields are very high, in particular as regards their optical qualities and it has proved very difficult to manufacture a windshield comprising an anti-laceration protection which is free of optical defects. Even when the individual sheets of the laminated vitraqe are free from optical defects before being joined to each other, it is difficult to assemble them and to preserve their optical qualities.

A method of applying a layer of plastic to a surface of a single glass sheet is described in United States Patent No. 3,806,387. In this method, a glass sheet, a layer of adhesive and a thin transparent sheet plastic layer are assembled in a stack to produce an assembly for further laminating. A second glass sheet (called a cover or forming sheet) matching the configuration of the glass sheet of the stacked assembly is then placed on the upper face of the plastic sheet. The surface of the glass forming sheet which is adjacent to the plastic sheet is coated with a release agent to prevent adhesion between the glass forming sheet and the plastic sheet. Typically, the glass forming sheet is bent to the same shape as GM.YD.SF - 4 - 13-5808

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the glass sheet of the laminate assembly. The gaps between the individual layers are then removed under vacuum and the assembly is placed in an autoclave. The autoclave exerts pressure on the exterior surfaces of the assembly while heating this assembly to a temperature which causes a junction between the glass sheet and the plastic sheet. When the assembly is removed from the autoclave, the forming sheet can be separated from the stack.

One cause of failure in laminated glass structures is the air trapped between the layers. It has been found that these defects are alleviated if, before treatment in the autoclave, the assembly is pressed and / or a vacuum is applied at its edges. The preliminary pressing, or "prepressing", is typically carried out by an apparatus comprising upper and lower series of pressing rollers arranged in parallel positions in the axial direction and in contact in the tangential direction. In general, the rollers are mounted in a cage or a frame which can be moved in an arc from a position for receiving the assembly towards a position for unloading the assembly. It has also been found that it is advantageous to use a peripheral vacuum chamber with a thickness less than that of the assembly auauel it is attached, which allows the vacuum chamber and the assembly to pass between the prepress rollers. Such an apparatus is described in United States patent 4,040,888.

One of the difficulties encountered with the known vacuum chamber is the fact that it requires a thin flexible strip of air-impermeable material in order to be tightly adapted to the assembly GM.YD.SF - 5 - 13- 5808 laminate. Then, at the end of the prepressing, the ribbon must be torn off from the laminated or laminated assembly.

All of this wrapping takes time and labor and leaves a tacky residue of adhesive on both surfaces of the laminated glazing. In addition, the use of rigid tubes makes the processing of bent assemblies extremely difficult and requires that the pinch rollers are positioned at a fixed distance from each other, less than that which would allow the most prepressing operation. effective.

However, the invention aims to provide a prepressing device which allows the use of a conventional vacuum molding on laminating assemblies comprising one or more sheets of bent glass.

The invention also aims to provide an apparatus for prepressing laminate assemblies which automatically adapts to the changing curvature * of the thicknesses when the assembly passes between the pressure rollers.

In the accompanying drawings: FIG. 1 is a schematic top plan view of prepressing apparatuses according to the invention, the upper prepressing rollers being removed to show an assembly in three different positions as it passes through the prepressing apparatus; Fig. 2 is a front elevation view of the prepressing apparatus shown in FIG. 1, along line 2-2 of FIG. 1, and, on a larger scale; Fig. 3 is a cross-sectional view of the prepressing apparatus on line 3-3 of FIG. 2, and, on a larger scale, showing the upper rollers in pressure contact with the assembly, and GM.YD.SF - S - 13-5808 FIG. 4 is a rear elevation view of the prepressing apparatus taken along line 4-4 of FIG. 3 and, on a larger scale.

According to the invention, there is provided a method for eliminating the air present in the interfaces of a set of superimposed sheets, this set comprising an anterior edge, a posterior edge and opposite lateral edges, and according to this method the enclosure is enclosed. peripheral edge of the superimposed sheets by means of a continuous air evacuation molding, this air evacuation molding being in communication with the interfaces of the superimposed sheets and being connected to a vacuum source, characterized in that a vacuum is applied to the molding to extract air through this molding, several pairs of opposite rollers are provided, spaced apart from each other, the axes of rotation of the opposite rollers being arranged in the same plane and the rollers correspondents of each pair having a common axis of rotation, the anterior edge of the sheet assembly is positioned internally with respect to the exhaust air molding, between the spaced rollers, this edge anterior being substantially parallel to the plane passing through the axes of rotation of the rollers, the number of pairs of opposite rollers determining a length measured along the axes of rotation of the rollers, less than the distance between the front edges of the exhaust molding of air which encloses the opposite lateral edges, a relative displacement is produced between the pairs of opposite rollers so that the rollers come into contact under pressure with the opposite faces of the sheet assembly internally with respect to the molding air evacuation, advance the assembly between the opposite rollers while continuing to apply vacuum to the eva molding GM.ro.SF - 7 - 13-5808 cuation of air until the molding at the rear edge of the assembly is adjacent to the rollers without, however, already being in contact with them, the opposite rollers are separated to eliminate the pressure contact imposed on the sheet assembly and the e One of the opposite rollers.

In addition, according to the invention, there is provided an apparatus for prepressing sets of stacked sheets for their subsequent stratification, characterized by a frame, a feed conveyor for supporting and advancing an assembly arranged horizontally along a path in the horizontal assembly on one side of the frame, a device for aligning the assembly with a view to introducing it into the frame, a device mounted on the frame for exerting pressure on the assembly, and a device for moving the together through the frame and through the device applying the pressure, the displacement device comprising several drive rollers of different diameters mounted for rotation along an axis of rotation inclined with respect to the horizontal path so that each of the rollers attack a surface of the assembly, and a device for driving the rollers in rotation in order to pass the assembly through the frame and through the device intended for appl ick the pressure.

Fig. 1 illustrates a part of a production line intended for laminating sets of sheets comprising a prepressing apparatus 10 installed between a supply or entry conveyor 11 and a discharge or exit conveyor 12. Sets to be laminated such as the assembly 13 move along the production line in the direction of the arrow 14. These assemblies typically have the form of sheets of glass and plastic GM.YD.SF - 3 - 13-5808 t ' s arranged in a sandwich-like stack.

Given the final orientation of the assembly 13 in a vehicle, after it has been laminated, this assembly 13 has an upper edge 15, a lower edge 16 and side edges 17 and 18. The stacked assembly 13 is brought to l prepressing apparatus 10 on the feed conveyor 11 and comprises two parallel driven belts defining an opening therebetween. The assembly 13 is supported along its downwardly facing surface by the belts, the upper edge 15 being the front edge.

The assembly 13 of stacked stacked sheets approaches the prepressing apparatus 10 with its upper edge 15 and its lower edge 16, in the assembly transverse to the direction of advance 14 of the conveyor 11. When the upper edge 15 which is the front edge of the assembly 13 in FIG. 1 approaches the prepressing apparatus 10, the assembly 13 is, generally centered on a rotary suction cup 19 which is placed between the belts of the supply conveyor. This position of the assembly 13 is illustrated in broken lines and is designated by the reference 21. Two spaced aligning arms 22 and 23 are arranged between the belts of the conveyor 11 to attack the upper edge 15 of the assembly 13 and stop it above the rotary suction cup 19. The rotary suction cup 19 is raised in contact with the underside of the assembly 13 and the arms 22 and 23 are retracted. The suction cup 13 is rotated in the direction of the arrow 20 approximately 90 ° to position the lateral edge 18 of the assembly 13, as indicated in solid lines, between the spaced upper and lower pressure rollers (only the lower rollers being shown on Fig. 1 for clarity). The suction cup holds the assembly by vacuum and it releases it and retracts when the upper rollers are lowered into pressure contact with the assembly as described in more detail below. The assembly 13 is then moved through the prepressing apparatus 10 and is brought to the evacuation conveyor 12 in the evacuation position represented by the dashed line 24.

During the orepressing operation and during the approach and the distance from the prepressing apparatus 10, an air or vacuum evacuation molding 25 remains attached around the peripheral edge of the assembly 13. The molding 25 is connected to a vacuum source (not shown) by a flexible connecting pipe 26. During the prepressing operation, a vacuum is created in the molding to contribute to the evacuation of the air present between the adjacent sheets of the 'assembly 13. As clearly shown in FIG. 3, the vacuum molding 25 has, overall, a C-shaped cross section whose opening has a width slightly less than the thickness of the assembly 13 to guarantee an airtight seal. The vacuum molding 25 and the edges of the assembly 13 form a vacuum chamber 27 which is in communication with the entire periphery of the assembly 13 and with the connection pipe 26.

The prepressing apparatus 10 is shown in more detail in FIGS. 2 to 4, This apparatus 10 comprises a frame 30 comprising a lower horizontal base 31 and an upper horizontal arm 32 each having one end attached to a vertical post 33 in contact with the ground. The base 31 and the arm 32 are spaced parallel to each other and the other end of the base 31 is supported by a foot 34 in contact with the ground.

As shown in Figs. 2 and 3, the upper arm GM.YD.SF - 10 - 13-5808 "* 32 supports several pairs of rubber prepress rollers 35. The rollers 35 are typically mounted in pairs, each pair being articulated in the middle of a crosspiece 36, the ends of which are supported between the opposite ends 1 of a stirrup in the C-shaped assembly 37. The stirrup 37 is connected to one end of a vertical axis 38 the other end of which is attached to a piston extension 39 of a pneumatic cylinder 40. The pneumatic cylinder 40 is mounted on a console 41 which is attached to the horizontal arm 32. A roller guide 42 is also mounted on the console 41 to position the axis 38 so that 'it moves vertically between the upper position indicated by the broken lines 43 and the lower position indicated by the solid lines in FIG. 3. The number and spacing of the prepress rollers 25 depend on the width of the assembly 13 as well as on the value and the distribution of the pressure to be exerted.

The assembly 13 is supported on top of several pairs of prepress rolls or lower support rollers 44 which are of a construction similar to that of the rollers 35. However, these rollers are not mobile, but are fixedly mounted on supports 45 and 46 which are, in turn, attached to the horizontal base 31. The assembly 13 is therefore supported by the lower prepress rollers 44 and the pressure is applied by the upper prepress rollers 35 when they are lowered in place by pneumatic cylinders 40. The supports, 45 and 46 are spaced along the horizontal base 31 on either side of several drive rollers 47. The drive rollers 47 are typically mounted in pairs on a box 48 attached to an upper surface of the horizontal base 31. Each GM.YD.SF - 11 - 13-5808 * Λ * pair of drive rollers 37 is rotatably supported by a yoke 49. The yoke 49 is attached to an upper end of a vertical threaded rod 50 which passes through an opening 51 in an upper surface of the box 48. Two stop nuts 52 are screwed onto the rod 50, the lower nut attacking the upper surface of the box 48 and the upper nut blocking the nut lower in place on the rod 50. The rod 50 is articulated to the yoke 49 at the pivot point 53 for an end which will be explained below.

A reducer motor 54 drives a chain wheel 55 which in turn drives a roller chain 56 indicated in broken lines. The roller chain 56 in turn drives a chain wheel 57 attached to one end of a drive shaft 58. The drive shaft 58 is rotatably supported by several adjustable buttonhole consoles 59 which are attached to the box 48. Several driven chain wheels 60 are wedged on the shaft 58 so as to rotate with it. Each of the driven chain wheels 60 is associated with a pair of drive rollers 47. Between the rollers 47 of each pair is provided a chain wheel 61 which is integral with the rollers 47 so as to rotate with them. Each of the chain wheels 60 drives a chain wheel 61 associated by a chain 62.

In Fig. 4, the rollers 47 have been designated from right to left by the letters "A" to "F". According to the invention, the rollers "A" to "F" are of progressively increasing diameter and are preferably cut in a cone to form a truncated cone intended to move the assembly 13 through the prepressing apparatus 10 along a curved path towards the evacuation position 24. Since the lower edge 16 of the assembly is longer than the edge GM .YD.SF - 12 - 13-5808 upper 15, the roller "F" must travel a longer distance than the roller "A" along the lower surface of the assembly 13. The rollers of different diameters compensate for this difference distance to be traveled to prevent any slippage and / or slippage between the lower surface of the assembly 13 and the drive surfaces of the rollers 47. In addition, the curved path that the assembly travels ensures more efficient pressing and prevents any possible hooking between the rollers and the vacuum molding 25 which could, in this case, be moved. To maintain a horizontal support surface for the transparent assembly 13, the axis of rotation 63 of the rollers 47 is inclined relative to the horizontal, the drive roller "F" being located at a point lower than the roller drive "A".

The axis is tilted by loosening two screw-on connecting members 64 which pass through long buttonholes in each of the brackets 59 and which are screwed into a bottom plate 65. By loosening the joining members 64, can adjust the height of the brackets 59 and by screwing the stop nuts 52 in the desired direction, one can raise or lower the associated drive rollers 47. The drive rollers are pivotally mounted at 53 so that the pivot points of all the rollers 47 can be aligned on the axis of rotation 63. The displacement of the drive rollers 47 and the associated yokes 49 also causes a inclination of the drive axis 58 so that its longitudinal axis remains parallel to the axis of rotation 63. This movement is made possible by the adjustable brackets 59 and the screw-in assembly members 64 are then tightened at the same time as the stop nuts 52 in order to fix everything in place.

GM.YD.SF - 13 - 13-5808 * * *

It appears from the above that the aims of the invention have been fully achieved. However, the invention provides an improved apparatus for prepressing glass and plastic sheets for further autoclaving and lamination in a mass production operation.

GM.YD.SF - 14 - 13-5808

Claims (15)

1.- Method for eliminating the air present in the interfaces of a set of superimposed sheets, this set comprising an anterior edge, a posterior edge and opposite lateral edges, and according to this method the peripheral edges of the sheets superimposed are enclosed by means of a continuous air exhaust molding, this air exhaust molding being in communication with the interfaces of the superimposed sheets and being connected to a vacuum source, characterized in that: a vacuum is applied to the molding for extracting air by means of this molding; several pairs of opposite rollers are provided, spaced from one another, the axes of rotation of the opposite rollers being arranged in the same plane and the corresponding rollers of each pair having a common axis of rotation; the front edge of the sheet assembly is positioned internally relative to the air exhaust molding, between the spaced rollers, this front edge being substantially parallel to the plane passing through the axes of rotation of the rollers, the number of pairs of opposite rollers determining a length measured along the axes of rotation of the rollers, less than the distance between the front edges of the exhaust air molding which encloses the opposite side edges; a relative displacement is produced between the pairs of opposite rollers so that the rollers come into contact under pressure with the opposite faces of the sheet assembly internally with respect to the exhaust air molding; the assembly is advanced between the rollers GM.YD.SF - 15 - 13-5808 '* ·' opposite while continuing to apply vacuum to the exhaust air molding until the molding is level the rear edge of the assembly is adjacent to the rollers without, however, already being in contact with them; * the opposite rolls are separated to eliminate the pressure contact imposed on the sheet assembly, and the assembly is removed from among the opposite rolls. 2. Apparatus for precompressing sets of stacked sheets for subsequent stratification, characterized by: a frame; a feed conveyor for supporting and advancing an assembly arranged horizontally along a path in the horizontal assembly on one side of the frame; a device for aligning the assembly in order to introduce it into the frame; a device mounted on the frame for exerting pressure on the assembly, and a device for moving the assembly through the frame and through the device applying the pressure, the displacement device comprising several drive rollers of different diameters mounted rotatable along the axis of rotation inclined with respect to the horizontal path so that each of the rollers attacks a surface of the assembly, and a device for driving the rollers in rotation in order to pass the assembly through the frame and through the device for applying pressure. 3, - Apparatus according to claim 2, characterized in that the alignment device GM.YD.SF - 16 - 13-5808 to * comprises two spaced aligning arms placed near said side of the frame to attack an anterior edge of 1 'together. 4. Apparatus according to claim 3, characterized in that the aligning device further comprises a rotary suction cup which is vertically movable in order to attack a lower surface of the assembly and to be fixed therein under vacuum, a device for retract the aligning arms and a device to rotate the suction cup in order to align the assembly to introduce it into the device intended to apply pressure. 5. Apparatus according to any one of claims 2 to 4, characterized in that each of the drive rollers has the shape of a truncated cone whose bases are, in general, perpendicular to the rotation of the roller. 6. Apparatus according to any one of claims 2 to 5, characterized in that the device for applying the pressure comprises several movable prepress rollers vertically mounted on the frame and a device for moving the prepress rolls between a first spaced position of the horizontal path and a second position in which the prepress rollers attack a surface of the assembly and exert pressure thereon. 7. Apparatus according to claim 6, characterized in that the device for moving the prepress rollers comprises a piston and pneumatic cylinder, the cylinder being attached to the frame and the piston being attached to a vertical rod to which at least one of the rollers of prepress is attached to rotation. 8. Device according to claim 6, GM.YD.SF - 17 - 13-5808 V „> •. · T 9 characterized in that the prepress rollers are attached in rotation in pairs to each of several vertical rods connected, in turn, to the corresponding pistons of pneumatic cylinders whose cylinders are attached to the frame. 9. Apparatus according to any one of claims 2 to 8, characterized by several support rollers rotatably attached to the frame to attack and support a surface of the laminate assembly. 10. Apparatus according to claim 9, characterized in that the support rollers are positioned on either side of drive rollers of different diameters. 11. Apparatus according to any one of claims 2 to 10, characterized by a vacuum molding enclosing all the edges of the assembly. 12. Apparatus according to any one of claims 2 to 11, characterized in that the drive device comprises a first chain wheel driven by a drive device, a second chain wheel connected to the drive rollers so to turn with these and a chain connecting the first and the second chain wheel. 13. Apparatus according to any one of claims 2 to 12, characterized by a device for vertically adjusting the position of the drive rollers relative to the surface of the assembly thus attacked. 14. Method for extracting air present in the interfaces from a set of substantially superimposed sheets as described above. 15. Apparatus for prepressing sets of stacked sheets for subsequent lamination, essentially as described with reference to GM.YD.SF - 18 - 13-5808, ’'”' - ’i attached drawings. GM.YD.SF - 19 - 13-5808