FR2647052A1 - MACHINE FOR FOLDING SHEETS OF THERMOPLASTIC MATERIAL - Google Patents

Abstract

A machine for folding thermoplastic sheets, of the type which contains, on a frame (3, 4, 5) fitted with a support surface (6) for the sheet to be folded, a movable element (14) for gripping said sheet positioned opposite the support surface and movable towards said surface, a heating element (42) for softening the fold area of the sheet and a pivotable surface (11) which does not, when at rest, project beyond said support surface, characterized in that the folding element (1) is linked to means for controlling the relative elevation of its folding surface (11) and its pivot axle.

Description

Machine for folding sheets of thermoplastic material
The present invention relates to a machine for folding sheets of thermoplastic material, which comprises, on a frame provided with a bearing surface for the sheet to be folded, a movable member for clamping the latter positioned opposite the bearing surface to which it can be moved, a heating member for softening the area to be folded of the sheet, and a pivoting folding member which has a folding surface not exceeding, in the rest position, said surface support.

 Such a folding machine makes it possible, from a raw sheet or plate of thermoplastic material, to make all kinds of light and angular articles with thin walls, in particular object holders, display stands for magazines and brochures, such as those that can be found on the counters of banks or post offices, display media, etc ...

 The main drawback of current folding machines of the above-mentioned type is that they are not designed to automatically produce folds beyond 120-130 ′, and in particular folds at 180 ′, to which is added the the fact that the heating and cooling of the more or less wide folding zone of the sheet is not carried out under optimum conditions of efficiency and rapidity, which very often adversely affects the quality and the aesthetics of the fold produced and, on the other hand, the productivity of the machine.

The present invention proposes to remedy these drawbacks and, to do this, it relates to a folding machine of the type specified in the introduction, which is characterized in that its folding member is associated with means for adjusting the position. in relative height of its folding surface and its pivot axis,
Advantageously, the folding member has a defined pivot axis, at its two ends transverse to this axis, by two shafts connected respectively to the latter and supported in rotation by the frame of the machine, at least one of them. being further coupled to an angular pivoting control means, and in this case said position adjusting means are constituted, between the folding member and each shaft, by a removable connection assembly which is supported on one of 'them and is fixed at a point of the other chosen along a positioning axis substantially perpendicular to said folding surface.

 According to a preferred embodiment, each of these connecting assemblies is constituted, on the respective end of the folding member, by a projecting stud with threaded end and, on the opposite end of the corresponding shaft, by a collar thereof, pierced with a slot defining said positioning axis and in which said stud engages to be immobilized therein by a tightening nut screwed onto its threaded end.

 Thanks to these arrangements, it is in particular possible to lower the folding member with respect to its pivot axis generally situated in the plane of the bearing surface in order to shift its folding surface downwards with respect to this axis d 'a sufficient distance, at least equal to twice the thickness of the sheet to be folded, so that it can pivot by turning completely or almost completely and thus automatically produce folds beyond the 120-130' at which is currently limited, including folds at 180-.

To produce such folds, in particular on very thick sheets or plates, it may be necessary to use the clamping member as a folding counterpart and this will then, according to a complementary characteristic of the present invention, consist of a thin element in a direction perpendicular to the bearing surface, and preferably by a leaf spring curved in the direction of the latter
It will also be advantageous to provide the clamping member with a possibility of displacement parallel to the bearing surface, in order to be able to adjust its position relative to the latter depending on the nature of the fold to be produced and in particular, in the case of thin sheets, to be able to place it above the rear part of the support surface, this in order to refine as much as possible the folding that takes place at the front, especially when you want to produce folds very closed as is the case on photograph holders or other articles of the same type.

 Of course, by giving the position adjustment slot the appropriate length, it is also possible to raise the folding member to bring its folding surface up to its pivot axis in the plane of the bearing surface of the sheet to fold, and thus, using a traditional folding counterpart, make common folds not exceeding 120-130 ".

 Whatever the mode of use envisaged of the folding machine according to the invention, provision is further made for optimizing and adapting, with a view to its softening before folding, the conditions for heating the area to be folded of the sheet of thermoplastic material, depending on a certain number of parameters, such as its thickness, the nature of its constituent material and the radius of curvature of the fold to be produced.

 According to these arrangements according to the invention, the folding member delimits with a free edge close to the bearing surface a continuous slot for exposure of the zone to be folded of the sheet, of adjustable width, opening onto the 'heater which is in turn made in the form of a heat radiating element provided with positioning means for maintaining it in the median longitudinal plane of this slot.

 Preferably, the heating member is also coupled to a translational drive mechanism, making it possible to move it in the median longitudinal plane of the exposure slit.

 After the sheet has been folded, the cooling of the folded area, which is currently obtained by a simple interruption of the action of the heating element, should also be checked, and to this end the folding machine according to the the invention is advantageously equipped with a cooling blower provided at the outlet with a blowing sheath opening over the entire length of said exposure slot, and at least the part of which is located in the path of movement of the member heater is movable out of it under the control of a drive mechanism whose action is alternated with that of the drive mechanism in translation of the heating member.

 According to an additional characteristic of the invention, the heating member is mounted on a support movable in a direction perpendicular to the bearing surface, and its drive mechanism consists of at least one rack extending in said direction of movement on the rear of said support and meshing with a respective pinion driven in rotation on the frame, while the blowing sheath consists of a fixed body and a sliding element forming said part located in the path of movement of the member heater, the drive mechanism of which comprises at least one rack meshing with said pinion on its side opposite to that which meshes with the corresponding rack of the drive mechanism of the heating member.

A folding machine according to the preferred embodiment of the present invention will now be described in more detail, but only by way of non-limiting example, with reference to the accompanying drawings in which
- Figure 1 is a front view, slightly in perspective, of this folding machine
- Figure 2 is an enlarged cross-sectional view taken in the plane Il-Il of Figure 1
- Figure 3 shows an enlargement of part of Figure 2
- Figure 4 is a partial sectional view taken in the plane
IV-IV of figure 3
- Figure 5 is an enlarged front view, in partial section, of the left part of the machine of Figure 1
- Figure 6 is a sectional view taken in the plane VI-VI of Figure 5
- Figure 7 is a sectional view, on a larger scale, taken in the Vil-Vil plane of Figure 5
- Figure 8 is a sectional view taken in the Vili-Vili plane of Figure 7
- Figures 9 and 10 are schematic sectional views illustrating the operation of the machine
- Figure 11 is a view similar to Figure 10, but showing another mode of use of the machine; and
- Figure 12 is a view similar to Figure 10, illustrating an alternative embodiment.

 In FIGS. 1 and 2, which show all the basic functional elements of the exemplary folding machine, we can first of all see two long metal profiles in T 1.2, which by their two ends are mounted in positions substantially parallel, with their central branch la, 2a (foot of the T) directed downwards, between two lateral support cheeks 3,4 forming the frame of the machine with connecting crosspieces such as 5. The rear section 2 which is fixed and also constitutes an element of this frame, has a flat and horizontal upper face 6 defining a bearing or bearing surface for a sheet of thermoplastic material to be folded. The front section 1 is in turn pivoted between the two support cheeks 3,4, to form the actual folding member of the machine.

 The pivoting mounting of the folding member 1 is more precisely carried out using two short shafts 7, each of which is connected to a respective end of the folding member and crosses, by a rotation bearing 8, the wall 9 of the adjacent support cheek 3 or 4, as shown in FIG. 5. The two shafts 7 are centered on the same horizontal axis X defining the pivot axis of the folding member 1, this axis s' extending in the plane of the bearing surface 6 formed on the rear section 2 and in a direction parallel to the straight free edge 10 closest to the latter.

 The folding member I is also positioned so that at rest, as in FIG. 2, its upper face 11 which constitutes the folding surface proper, that is to say also located in a horizontal plane and that its edge free rectilinear rear 12 extends vertically from its pivot axis X and delimits with that 10 of the rear section 2, a continuous slot 13 of constant width. It will also be noted here that the bearing surface 6 defined on the rear section 2 is substantially twice as wide as the folding surface 11 of the folding member.

 The folding machine shown also comprises a member for clamping the sheet to be folded, which according to the invention consists of a leaf spring 14 held in the direction of its length above the rear section 2 towards which it is curved. The leaf spring, which has a width substantially equal to half that of the bearing surface 6, is more precisely fixed by its two ends to the ends of the rods 17 of two vertical pneumatic cylinders 18, each retained on a bracket 19 protruding on the inner face of a respective cheek 3 or 4. It will be observed in FIG. 1 that the rod 17 of each jack 18 passes through a slot 20 of direction substantially perpendicular to the axis X, formed in the respective support bracket 19 , the upper body 15 of each cylinder 18 being further bolted to the edges of this slot, in a variable position along the latter. The leaf spring 14 is itself connected by means of simple bolts to the free ends of the rods 17 of these jacks.

 Figures 5 and 6 illustrate, at one end of the folding member 1, the mechanism 21 which controls the pivoting of the latter. This mechanism 21 comprises, on a square console 22 housed inside the cheek considered 3 of the frame of the machine, a horizontal pneumatic cylinder 23 whose rod 24 directed perpendicularly to the axis X, is extended by a rack 25 The latter, sliding inside a rail 26 supported by a support 27 fixed to the console 22, meshes with a toothed pinion 28 wedged at the end of the corresponding shaft 7, which freely crosses the console .

22 just before its rotation bearing 8.

 As shown in Figures 7 and 8, the shaft 7 carries, at the end of its section which extends on the other side of the wall 9 of the cheek 3, a disc 29 projecting radially by a flange 30 in which a slit 31 is made which extends perpendicular to the folding surface 11, in the front half of the disc 29 and over a little less than the length of the corresponding cord of the latter. The opposite end of the folding member 1 projecting, very close to the folding surface 11, a stud with threaded end 32 parallel to the axis X, stud which engages through the slot 31 of the disc 29 and receives on the other side thereof a locking nut 33. It will be noted here that the stud 32 is distant from the rear free edge 12 of the folding member 1 by a distance substantially equal to that which separates the axis of the slot 31 of the disc 29 of the pivot axis X.

 It should also be observed, with reference simultaneously to Figures 2 and 8, that the bearing 8 of the shaft 7 is slidably mounted in a horizontal slot 34, perpendicular to the axis X, of the wall 9 of the cheek of support 3 and that, on the inner face of this wall, the console 22 for supporting the mechanism 21 is movably mounted along two horizontal rails 35,36. The position of the console along these rails can be modified using a threaded operating rod 37 screwed into a cleat 38 secured to the console 22 and ending in a crank 39 beyond. the front wall 40 of the cheek 3, which it crosses by a bearing 41 immobilizing it in translation.

 The structure which has just been described with reference to FIGS. 5 to 8 is found in a symmetrical position at the other end (that on the right in FIG. 1) of the folding machine according to the invention, with this difference however that the shaft 7 is not coupled thereto beyond the mobile console 22, to a mechanism such as 21. Therefore, thanks to the mounting method, according to the invention, of the folding member 1 on the two shafts 7, it can at rest lower it below the bearing surface 6 formed on the rear section 2 and adjust at will the distance in height separating its folding surface it from the latter, while maintaining its rear free edge 12 in the vertical plane of its pivot axis X. In addition, by simultaneously operating the threaded rods 37 using the cranks 39, the spacing between the folding member 1 and the profile can be adjusted as desired back 2 for supporting the sheet to be folded, that is to say the width of the slot 13 (FIG. 2). Finally, by actuating the jack 23 in the direction of extension or retraction of its rod 24, which can be done from a control panel 100 of the machine, the folding member 1 will be pivoted in one direction or in the other around the axis X. It should be noted here that the extension stroke of the jacks 23, which determines the pivoting angle of the folding member 1 and therefore the desired folding angle of the sheet, is adjusted using a long rod 80 (see FIG. 6) pointing in front of at least one of the racks 25 while being on one side, freely supported, at 81, by the console 22 and , on the other side, screwed by a threaded section through the front wall 40 of the cheek 3 beyond which it ends with a rotation crank 82, this rod 80 thus playing the role of a stop in position adjustable for rod 24 of cylinder 23.

 Returning to FIG. 2, one can also see, in the median longitudinal vertical plane P of the slot 13, an infrared heating tube 42, which extends over the entire length of the latter, being, as shown Figures 1 and 5, held parallel to the axis X, at the top of a frame 43 slidably mounted in two vertical rails 44 respectively fixed, vis-à-vis, on the walls 9 of the support cheeks 3,4 .

Each of the lateral vertical uprights 45 of the frame 43 carries, along its rear side, a rack 46 which meshes with a toothed pinion 47 wedged on a horizontal shaft 48, of short length, passing through the wall 9 of the adjacent support cheek 3 or 4 by a rotation bearing not shown. FIG. 6 shows that, on the other side of this wall 9, the shaft 48 carries a second toothed pinion 50 which is engaged with a horizontal rack 51 extending the rod 52, perpendicular to the axis X, by pneumatic cylinder 53 carried, inside the respective support cheek 3 or 4, by a fixed console 54. As in the mechanism 21 located above, the rack 51 slides in a rail 55, integral with a support 56 formed in relief on this console 54. In FIGS. 1 and 2, it will also be noted the presence on the external face of the wall 9 of the cheek 3 or 4, of a compensating roller 57 placed in contact with the front side of each of the uprights 45 of frame 43, facing pinion 47.

 Figures 2,3 and 5 also show that the heating tube 42 rests, with the interposition of a cradle of refractory material 58, on three U-shaped stirrups 59 embracing the upper horizontal upright 60 of the frame 43, respectively to these two ends and in the middle. Each stirrup 59 is more precisely retained on this upright 60 by a short threaded rod with head 61, screwed through the latter and supported in free rotation by the two vertical branches of the stirrup 59.

 It will easily be understood that by acting on these threaded rods 61, it is possible at any time to bring the heating tube 42 back into the vertical median plane P of the slot 13, depending on the modification of its width and that the extension or the retraction of the jacks 53, controlled from the panel 100, makes it possible to raise or lower the heating tube 42 in this plane P, by means of the rack-and-pinion drive system 46,47. The height position of the heating tube 42 will therefore be determined by the extension stroke of the jacks 53 which, like the mechanism 21, can be easily adjusted by a rod 83 with an external rotation crank 84 acting as a adjustable position stop for at least one of the racks 51 and therefore for the rod 52 of the corresponding jack 53 (see FIG. 6).

 The folding machine according to the invention is completed by a cooling device, (shown only in FIGS. 2 to 4), the basic member of which is a fan 62 fixed to the inner wall 9 of one of the support cheeks 3. The suction 63 of this fan opens onto the open air while its discharge is connected to a long flexible pipe 64 which, at the other end, communicates with a metal blowing duct 65 tilting towards the high towards slot 13.

 The blowing duct 65 more precisely comprises a rear part 66 for connection to the flexible pipe 64, which widens from the latter until it covers substantially the entire free width between the two support cheeks 3, 4 and extends beyond by an inclined upper wall 67 fixed, by its free front edge 68, to the central branch 2a of the rear section 2. Under the upper wall 67 of the sheath 65 and along the side walls 66a, 66b and lower 66c of its rear connection part 66, a U-shaped sliding element 69 is maintained which completes the sheath by defining the bottom wall 70 and the side walls 71,72 of its front part. The side walls 71,72 of the sliding element each carry a lateral wing 73,74 substantially parallel to the lower wall 70, wing which is retained at two points distant from each other between two superimposed rollers 75175a and 76.76a, mounted with free rotation on the paro i close 9 to the respective support cheek 3 or 4. Along each of its edges parallel to the wings 73, 74, the lower wall 70 of the U-shaped element 69 externally carries a rack 77 which meshes with the toothed pinion 47 corresponding, opposite the gear point therewith of the rack 46 of the frame 43 for supporting the heating tube 42.

 Thus, when the heating tube 42 is lowered in the plane P, by the rotation of the pinions 47, the latter cause the U-shaped element 69 of the blowing duct 65 to slide in synchronism upwards. In its high position illustrated in broken lines in Figure 3, it then defines, by a raised front spout 78, with the rear section 2, the outlet mouth 79 of the sheath 65, which covers substantially the entire length of the slot 13. At reverse, a counterclockwise rotation of the pinions 47 causes the U-shaped element 69 to retract from the blowing duct 65, which is then gradually extracted from the path of the heating tube 42 and the latter can then rise under the effect of this same rotation of the pinions to come to place in its high active position.

 The folding machine which has just been described is used more particularly for automatically making folds at 180 'on a sheet of thermoplastic material. With the machine stopped, as shown in FIG. 2, the height position of the folding member is adjusted by moving along the slots 31 of the discs 29 of the shafts 7, its threaded stud connection assemblies 32 and nut 33, so that its folding surface 11 is offset downward relative to its pivot axis X or to the bearing surface 6, by a distance b equal to twice the thickness e of the sheet F to fold (see Figure 9) increased by the height of the gap to be provided after folding between the two superposed sections of the sheet. By maneuvering the threaded rods 37, the width of the slot 13 is further adjusted to a predetermined value as a function also of the thickness e of the sheet but also of the nature of its constituent material and of the radius of curvature envisaged for the fold. By moving the jacks 18 along the slots 20 of the brackets 19, the position of the leaf spring 14 is also adjusted, in the present case placing it above the front part of the bearing surface 6, making it protrude beyond its free edge 10. By acting on the cranks 82 and 84 of the rods 80 and 83, the extension strokes of the jacks 23 and 53 are finally adjusted.

 Once these adjustments have been made, the sheet F to be folded is inserted between the raised leaf spring 14 and the bearing surface 6, making it rest on the latter and it is pushed into contact with a rear stop 85 whose position was previously adjusted along two horizontal rails 86 secured respectively to the walls 9 of the support cheeks 3, 4 so that the zone to be folded of the sheet F comes to be placed exactly above the slot 13.

 The actual folding of the sheet then begins under the synchronized control of the various jacks 18, 23 and 53 fitted to the machine, triggered from the control panel 100. As shown in FIG. 9, the leaf spring 14 is lowered very quickly. 'first to immobilize the sheet F against the bearing surface 6 and the heating tube 42, previously positioned in the plane P using the threaded rods 61, is raised to a predetermined height depending on the parameters of aforementioned adjustment, by the position of the free end of the rod 83, in order to ensure in this position optimal heating of the zone to be folded of the sheet F, exposed through said slot 13.

 After a sufficient period of time to ensure adequate softening of the zone to be folded of the sheet F, the folding member 1 pivots around the axis X and its folding surface 11 progressively raises the front section Fi of the sheet F , as symbolized by broken lines in FIG. 10, until it is completely folded down on the leaf spring 14.

 To fold thin sheets, we can do without a folding counterpart, and in this case, we can position the leaf spring 14 astride the rear edge of the bearing surface 6, as shown in the figure 11, to fold the front section Fi of the sheet F directly onto its rear section F2 and thus obtain a fold at 180 'as closed as possible.

 During the pivoting movement of the folding member 1, the heating tube 42 is gradually lowered which, as we saw above, causes the sliding U-shaped element 69 to rise up from the blowing sheath 65 and, at the end of folding, this is in position for, after switching on the fan 62, to cool the folded area optimally and freeze the fold at 180 '. This air blast cooling mode cuts the cooling time of the folded area in half.

 Of course by playing on the pivot angle of the shafts 7 using the rod 83, it is possible to limit the folding angle to a value less than 180 ′, more particularly between 150 and 180 ′. It is also possible to fold sheets of any thickness thanks to the possibility of adjusting the height position of the folding surface 11 of the folding member with respect to its pivot axis X, by displacement, along the slots 31 of the discs 29 of shafts 7, of its connection assemblies with threaded stud 32 and nut 33.

 Thanks to this possibility of height adjustment, it is also possible to raise the folding member 1 to bring its folding surface 11 substantially in the plane of its pivot axis X and of the bearing surface 6. As shown FIG. 12, the folding machine according to the invention can then be used to produce ordinary folds of less than 120-130 and, for this purpose, the leaf spring 4 will be replaced by the corresponding counter-folding element, such as that of substantially triangular section 87 visible in FIG. 12. The folding machine according to the invention will moreover be provided to the user with a set of counter-folding elements of various transverse sections which can very easily be substituted for the leaf spring 14, depending on the type of fold to be produced.

 It goes without saying, moreover, that the arrangements described above in connection with the heating of the zone to be folded and the cooling of the fold produced on the sheet of thermoplastic material are applicable to all types of folding machine, as their component folding either fixed or height adjustable.

Claims (10)

 1. Machine for folding sheets of thermoplastic material, of the type comprising, on a frame (3,4,5) provided with a bearing surface (6) for the sheet to be folded, a movable member (14) of clamping of the latter positioned opposite the bearing surface to which it can be moved, a heating member (42) for softening the area to be folded of the sheet and a pivoting folding member (1) which has a folding surface (11) not exceeding, in the rest position, said bearing surface, characterized in that the folding member (1) is associated with means for adjusting (31,32,33) the position in relative height of its folding surface (11) and its pivot axis (X).  2. Folding machine according to claim 1, characterized in that the folding member (1) has a pivot axis (X) defined, at its two ends transverse to this axis, by two shafts (7) respectively connected to the latter and supported in rotation by the frame of the machine, at least one of them being additionally coupled to an angular pivoting control means (21), and in that said position adjustment means are formed, between the folding member (1) and each shaft (7), by a removable connection assembly (32,33) which rests on one of them and is fixed at a point on the other chosen along a positioning axis perpendicular to said folding surface (11).  3. Folding machine according to claim 2, characterized in that each of said connecting assemblies is constituted, on the respective end of the folding member (1), by a protruding stud with threaded end (32) and, on the opposite end of the corresponding shaft (7), by a flange (30) thereof, pierced with a slot (31) defining said positioning axis and in which said stud engages and is immobilized therein by a tightening nut (33) screwed on its threaded end.  4. Folding machine according to any one of claims 1 to 3, characterized in that the clamping member is constituted by a # element # of thin thickness (14) in a direction perpendicular to said bearing surface (6 ).  5. Folding machine according to claim 4, characterized in that the clamping member has the form of a leaf spring (14) curved in the direction of the bearing surface (6).  6. Folding machine according to claim 4 or 5, characterized in that the clamping member (14) is movable parallel to the bearing surface (6).  7. Folding machine according to any one of claims 1 to 6, characterized in that the folding member (1) defines with a neighboring free edge (10) of the bearing surface (16) a continuous slot ( 13) of exposure of the zone to be folded of the sheet, of adjustable width, opening onto the heating member which is in turn produced in the form of a heat radiation element (42) provided with means for positioning (59,61) to maintain it in the median longitudinal plane (P) of this slot (13).  8. Folding machine according to claim 7, characterized in that the heating member (42) is also coupled to a drive mechanism in translation (46,47,50,51) making it possible to move it in the plane longitudinal median (P) of the exposure slit (13).  9. Folding machine according to claim 8, characterized in that it further comprises a cooling blower (62) provided at the outlet with a blowing sheath (65) opening over the entire length of said slot. exposure (13), at least the part of which is located in the path of movement of the heating element is movable therefrom under the control of a drive mechanism (47,69,50,51) whose l action is alternated with that of the drive mechanism in translation of the heating member (42).  10. Folding machine according to claim 9, characterized in that the heating member (42) is mounted on a support (43) movable in a direction perpendicular to the bearing surface (6), and its mechanism drive consists of at least one rack (46) extending in said direction of movement on the rear of said support t43) and meshing with a respective pinion (47) driven in rotation on the frame (3,4) while the sheath blower (65) consists of a fixed body (66,67) and a sliding element (69) forming said part located in the path of movement of the heating member, the drive mechanism of which comprises at least one rack (77) meshing with said pinion (47) on its side opposite to that which meshes with the corresponding rack (46) of the drive mechanism of the heating member.