EP0013206A1 - Bending apparatus, in particular for working zinc sheets on sites - Google Patents

Abstract

1. A bending machine of the type comprising a fixed lower beam (10), an upper beam (16) which is mounted so as to be movable between a downwardly turned closing position, in which it cooperates with the lower beam (10) to hold a metal sheet (17) to be worked, and an opened-out position, in which there is free access to the said lower beam (10), a rotary table (24) which is adjacent to the lower beam (10) along a straight working line and which is pivotally mounted about the said working line, and disengageable locking means of the toggle-joint type which are designed to couple the upper beam (16) to the lower beam (10) in the closing position of the said upper beam (16), the said toggle-joint locking means comprising, for each end of the said upper beam (16), a connecting linkage articulated to the upper beam (16) and a link (34A, 34B) which is articulated to the said connecting rod and to the lower beam (10), such a bending machine being characterized in that the said connecting linkage consists of a removable end plate (33A, 33B), and in that the said removable end plate (33A, 33B) incorporates, firstly, a first hole (36A, 36B ; 70-72-74), called the upper hole, by means of which it is rotatably engaged on a cylindrical bar (38) carried by the upper beam (16), and, secondly, a multiplicity of second holes (39A, 39B), called lower holes, by means of one of which it is rotatably engaged on a pin (40A, 40B) projecting from the link (34A, 34B), with which it is associated, and the centres of which are at different distances from that of the upper hole (36A, 36B ; 70-72-74), the said distances being predetermined and fixed permanently before the bending machine is used for the first time.

Description

The present invention relates generally to bending machines, that is to say machines capable of allowing the folding and / or rolling of any metal sheets.

It relates more particularly, but not exclusively, to those of these machines which are intended for galvanizing work on roofing sites.

Such folding machines have been known for a long time.

They generally comprise a lower bed base, which is fixed, an upper bed base, which is mounted movable between a folded closed position, for which, with the lower bed base, it cooperates in maintaining a sheet of metal to be worked, and a deployed opening position, for which it leaves free access to said lower bed base, and a rotary apron, which is adjacent to the lower bed base, along a rectilinear working line, and which is pivotally mounted around said working line.

In the standby position, the rotary apron extends in line with the lower bed base; in service, it makes, by tilting, a dihedral, straight or arbitrary, with this box spring.

Once the metal sheet to be worked securely held by pinching by the upper and lower bases, either directly if it is a simple folding, or via a rod or a mandrel if rolling, the rotary apron is tilted from its standby position to a service position for which it forces the sheet to work to take the desired configuration by deformation.

One of the difficulties to be overcome in the production of bending machines of this type is due to the disengageable locking means which it is necessary to provide between the upper base and the lower base for an effective and secure holding of the sheet of metal to be worked in. the closed position of the upper box spring.

Indeed, the quality of the work obtained depends in particular on these locking means.

Most often, these are locking means of the eccentric type.

However, the safety of the locking provided by means of such eccentric locking means depends, to a significant extent, on the force exerted by the operator on these locking means.

In addition, such eccentric locking means most often lead to relatively heavy embodiments, hardly acceptable for site machines.

In the French patent published under No. 2,356,462, the locking means used are of the cam type, the upper base being provided with hooks which gradually come to engage in fixed handles by jointly developing a tightening effect. , when the upper bed base is in the closed position.

But, here again, the effectiveness of the tightening sought depends on the effort developed by the operator.

In addition, a particular action of engagement of the hooks is necessary to obtain the desired tightening, independently of the tilting action applied to the upper bed base to bring it into the closed position, and these two actions can contradict each other.

Finally, bending machines, hemming machines or the like have been proposed, in particular by the German patents Nos. 825,392 and 1,452,919 as well as by the American patents Nos. 3,482,427 and 2,716,436, in which the locking means used are knee type: it the operator suffices for the stable locking of the upper base to the lower base, to extend the action which made it possible to move the upper base into the closed position so that the toggle locking means coupling the latter to the base lower cross elastically, by simple elastic work of the material, the line of maximum resistance for which the various axes of articulation involved in these toggle locking means are all in the same plane.

Beyond this line of maximum resistance, any uncontrolled retrograde movement of the upper base is impossible, by bracing of the toggle locking means.

Only an appropriate action of the operator can ensure such a retrograde movement, until a new elastic crossing of the line of maximum resistance.

The clamping force provided by the toggle locking means advantageously only depends on the configuration of the latter after they have crossed their maximum resistance line.

In other words, this clamping force does not depend on the force deployed by the operator, insofar as this force was sufficient to cross the maximum resistance line.

In addition, it is advantageously with a single movement that successively occurs the passage into the closed position of the upper base and its locking.

However, in the embodiments of this type known to date, either a change in the configuration of the toggle locking means used has not been provided for, or else this change is made by varying the length of a levers constituting these toggle locking means, such a lever being wholly or partly formed by a screw jack.

However, such a modification is desirable, to adapt the folder to a hemmer work, which requires the implementation of a rod or a mandrel between the lower base and the upper base, and if this modification is made using screw jacks, it is not certain that it affects both ends in a similar manner, at the risk of imperfect work thereof .

The present invention relates to a folder free of this drawback and also having other advantages.

This folder is of the type comprising a lower bed base, which is fixed, an upper bed base, which is mounted movable between a folded position of closures for which with the lower bed base, it cooperates in maintaining a sheet of metal to be worked, and a deployed open position, for which it leaves free access to said lower bed, a rotary apron, which is adjacent to the lower bed, along a straight working line, and which is pivotally mounted around said working line, and means disengageable locking mechanism of the toggle type suitable for coupling the upper box spring to the lower bed base for the closed position of said upper bed base, and is characterized in that said toggle locking means comprise, for each end of said upper bed base, a removable flange , which is articulated to the upper base, along a first axis of articulation, and a link, which is articulated to said flange, along u n second articulation axis parallel to the previous one, and to the lower bed, along a third articulation axis parallel to the previous two, the distance separating the two most distant articulation axes from one another being slightly different from the sum of the distances separating these two axes from each other, for crossing a line of maximum resistance between the open position and the closed position of the upper bed base.

In practice, each flange has a multiplicity of holes through each of which it can be articulated to the link with which it is associated.

To adapt the folder to hemming work, it suffices to remove each of the two flanges that this folder contains, to choose, depending on the extra thickness due to the rod or mandrel used, the distance which should be adopted between the axis by which said flanges are articulated to the upper base and that by which they are articulated to the rods with which they are associated, and to replace said flanges by engaging them on said rods through the corresponding holes.

• la figure 1 est une vue en perspective d'une plieuse suivant l'invention, pour la position de fermeture de celle-ci ;
• les figures 2A, 2B reprennent chacune une partie de la figure 1, et illustrent l'amovibilité des flasques que comporte la plieuse suivant l'invention ;
• la figure 3 est, à échelle différente, une vue en coupe transversale de cette plieuse, suivant la ligne III-III de la figure 1, et abstraction faite de ses piétements de support et des organes de maintien de ceux-ci ;
• la figure 4 est une vue analogue à celle de la figure l, pour la position d'ouverture du sommier supérieur ;
• la figure 5 est une vue analogue à celle de la figure 3, et illustre la ligne de résistance maximale que doivent franchir les moyens de verrouillage à genouillère mis en oeuvre suivant l'invention ;
• la figure 6 est une vue analogue à celle de la figure 3, pour un roulage et non plus un pliage ;
• la figure 7 est, à échelle différente, une vue partielle en coupe longitudinale de la plieuse suivant l'invention illustrant l'un des piétements qu'elle comporte.
• la figure 8 est une vue en perspective d'une variante de réalisation de plieuse suivant l'invention, pour la position de fermeture de celle-ci ;
• la figure 9 est, à échelle supérieure, une vue partielle en coupe de cette variante, suivant la ligne IX-IX de la figure 8 ;
• la figure 10 en est une autre vue en coupe partielle, suivant la ligne X-X de la figure 9 ;
• la figure 11 en est, à échelle différente, une vue partielle en coupe transversale, pour un travail de plieuse ;
• la figure 12 est une vue en coupe longitudinale du sommier supérieur de la plieuse de la figure 8, suivant la ligne XII-XII de la figure 11 ;
• les figures 13 et 14 sont des vues analogues à celle de la figure 11 et illustrent le travail en ourleuse de la plieuse concernée.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which:

• Figure 1 is a perspective view of a folder according to the invention, for the closed position thereof;
• FIGS. 2A, 2B each show a part of FIG. 1, and illustrate the removable nature of the flanges which the folder according to the invention comprises;
• Figure 3 is, on a different scale, a cross-sectional view of this folder, along the line III-III of Figure 1, and disregarding its support legs and the holding members thereof;
• Figure 4 is a view similar to that of Figure l, for the open position of the upper base;
• Figure 5 is a view similar to that of Figure 3, and illustrates the line of maximum resistance that must cross the toggle locking means implemented according to the invention;
• Figure 6 is a view similar to that of Figure 3, for rolling and no longer folding;
• Figure 7 is, on a different scale, a partial view in longitudinal section of the folder according to the invention illustrating one of the legs it comprises.
• Figure 8 is a perspective view of an alternative embodiment of the folding machine according to the invention, for the closed position thereof;
• Figure 9 is, on a larger scale, a partial sectional view of this variant, along the line IX-IX of Figure 8;
• Figure 10 is another partial sectional view along line XX of Figure 9;
• Figure 11 is, on a different scale, a partial view in cross section, for a folder work;
• Figure 12 is a longitudinal sectional view of the upper base of the folder of Figure 8, along the line XII-XII of Figure 11;
• Figures 13 and 14 are views similar to that of Figure 11 and illustrate the hemming work of the folder concerned.

In the embodiment illustrated by these figures, the lower base 10 of the folder according to the invention, which is fixed, is constituted by a section of U-shaped beam, the middle part 11 of which is horizontal and forms a work table, and whose lateral wings 12 are directed downwards, FIGS. 2A and 3 to 7.

For reasons which will appear below, the middle part 11 of this beam has longitudinally, from place to place, at a distance from its lateral wings 12, passages or housings 13.

At the ends of the lower bed base 10, two lateral cheeks 14A, 14B are attached vertically, for example by welding.

These cheeks constitute, with the lower bed base 10, the frame of the folder according to the invention, and, in the embodiment shown, this rests on the ground by two end legs 15A, 15B which will only be described later, with reference to Figure 7.

For better clarity of the figures, these legs have only been shown in single lines in FIG. 1 and they have been omitted in FIGS. 3 to 6.

The lower base 10 is associated with an upper base 16 which, in general, is movably mounted between a folded closed position, shown in Figures 1 and 3, for which, with the lower base 10, it cooperates in maintaining d 'a metal sheet 17 to be worked, as described in more detail below, and a deployed opening position, shown in Figure 4, for which it leaves free access to the lower bed base 10.

In the embodiment shown, and in a manner known per se, the upper base 16 is formed by an angle iron, one wing 18 of which has its beveled edge 19, for cooperation with the lower base 10, and the other wing 20 of which is secured at its ends, for example by welding, two links 21A, 21B each articulated respectively by studs 22A, 22B to the side cheeks 14A 14B.

In addition to the lower base 10, there is associated a rotary platform 24, which, in general, is adjacent to the lower base 10, along a rectilinear working line. and which is pivotally mounted around this working line.

In the embodiment shown, and in a manner known per se, this rotary apron is constituted by an angle iron, a wing 25 of which extends in the extension of the lower bed base 10 for the waiting position of this rotary apron shown in line full in FIG. 3, and the other wing 26 of which, for this standby position, is in contact with the corresponding wing 12 of said lower bed base 10.

The lower base 10 and the rotary apron 24 thus have two rectilinear edges in contact with one another, and it is these edges which define the rectilinear working line mentioned above.

In the axis of this working line, two pins 28A, 28B are each respectively attached, for example by welding, to the ends of the rotary apron 24, by means of notches 29, 30 provided for this purpose for each of them on the rotary apron 24 on the one hand and the upper bed 16 on the other hand.

These pins 28A, 28B are pivotally engaged in passages provided for this purpose in a complementary manner in the side cheeks 14A, 14B.

For its operation, a handle 32 is attached, for example by welding, to the wing 26 of the rotary apron 24.

Releasable locking means of the toggle type are provided between the upper base 16 and the lower base 10 to couple the base to the lower base 10 upper 16 in the closed position thereof.

According to the invention, these toggle locking means comprise, for each of the ends of the upper base 16, beyond the corresponding side cheek 14A, 14B, a removable flange 33A, 33B, which is articulated to the upper base 16, according to a first articulation axis A1, FIGS. 2A, 2B and 3, and a link 34A, 34B, which is articulated to said flange 33A, 33B, along a second articulation axis A2, parallel to the previous one, and to the lower bed base 10, and more precisely to the corresponding side cheek 14A, 14B, along a third axis of articulation A3, parallel to the previous two.

The distance separating from one another those of the articulation axes A1, A2, A3 which are the most distant, or distant, is slightly different from the sum of the distances separating these axes from the other.

In the embodiment shown, the most spaced or distant axes are the axes A1, A2 of the flanges 33A, 33B, and the distance Dl separating one from the other these axes is slightly less than the sum of the distances D2 , D3 separating, the first, the axis A3 from the axis Al, and the second, the axis A2 from the axis A3, Figure 3.

Preferably, and as shown, a multiplicity of possible hinge axes A2 is provided between each of the flanges 33A, 33B and the link 34A, 34B with which it is associated, these hinge axes A2 being each established at a different distance from the articulation axis A1.

For example, and as shown in FIGS. 2A, 2B, each flange 33A, 33B has a first hole 36A, 36B, hereinafter called the upper hole, by which it is rotatably engaged on the corresponding end 37A, 37B of a cylindrical bar 38, which is carried by the upper base 16 and runs all along it, and which is thus common to the two flanges 33A, 33B, and at least one second hole 39A, 39B, hereinafter called hole lower, by which it is rotatably engaged on a cylindrical lug 40A, 40B carried for this purpose projecting by the link 34A, 34B with which it is associated.

For the constitution of a multiplicity of possible axes of articulation between each flange 33A, 33B and the corresponding link 34A, 34B, such a flange 33A, 33B comprises a multiplicity of lower holes, the centers of which are two by two at different distances from that of the upper hole.

In the embodiment shown, for each flange 33A, 33B, and in correspondence of one of these flange to the other, three lower holes 39A, 39B, 39'A, 39'B, and 39 "A, 39 "B, are thus provided.

The center of a lower hole 39A, 39B is at a distance D1 from the center of the upper hole 36A, 36B, the center of the lower hole 39'A, 39'B is at a distance D'1 from the center of the upper hole 36A, greater than the distance Dl, and the center of the lower hole 39 "A, 39" B is at a distance D "l from the upper hole 36A, 36B, greater than the distance D'l, and therefore greater than the distance Dl.

Of course, the ends 37A, 37B of the cylindrical bar 38, and the studs 40A, 40B of the rods 34A, 34B, are associated with pins 42, for retaining the flanges 33A, 33B.

According to one aspect of the invention, the cylindrical bar 38 also constitutes a tensioner, this bar being connected to the upper bed 16 only punctually, near its ends, for example at two fixing points 43A, 43B, spaced apart. 'from one another, and produced by welding, and spacers being established from place to place between this cylindrical bar 38 and the upper base 16, in a manner known per se for a long time.

In the embodiment shown, three spacers 44 are thus provided, and each consists of a single screw, which is screwed into a threaded bore of the bar 38, and which bears on the wing 20 of the upper box spring 16, figure 30

Finally, and as visible in dotted lines in FIGS. 3 to 5, the lateral cheek 14B carries two projecting studs ('stop 46, 47, for the definition of the opening and closing positions of the upper bed base 16, and , for allow the operation thereof, an operating rod 48 is attached, for example by welding, on the rod 34B.

For the opening position of the bed base 16, the flange 33B bears on the stop pin 46.

Free access is thus left to the lower base 10, which allows the metal sheet 17 to be worked, FIG. 4, to be placed thereon and on the rotary apron 24 which is then in the standby position.

With the help of the operating bar 48, the upper bed 16 is then tilted to the closed position, along the arrow F in FIG. 4.

At the end of this tilting, the upper base 16 comes to bear against the metal sheet 17 to be worked, and therefore clamp it against the lower base 10, FIG. 5.

However, the movement of folding down the upper bed base 16 is continued so as to constrain the toggle locking means used, to pass elastically, by simple elastic work of the material, the line of maximum resistance for which, as illustrated in FIG. 5, the axes A1, A2, A3 of the flanges 33A, 33B and the corresponding links 34A, 34B are in the same plane P.

It is only beyond this line of maximum resistance that the link 34B comes to bear on the stop stud 47, FIG. 3, and that in this way the closing position of the upper bed base is rigorously defined. 16.

The return to the open position thereof is made by again crossing the line of maximum resistance materialized by the trace of the plane P in FIG. 5.

And, in both cases, such a crossing is obtained in the same movement which ensures the operation of the upper base 16.

In a manner known per se, when the bed base 16 is in the closed position, it suffices to pivot the rotary table 24 around its axis to obtain the folding, at right angles or otherwise, of the metal sheet 17 to be worked, such shown schematically in broken lines in Figure 3.

If a rolling of such a sheet must be ensured, it is necessary to use a rod or a mandrel 49, FIG. 60

The maintenance of the latter is ensured by a rule 50, which bears pins 51 on its underside for engagement in the holes or housings 13 of the lower bed base 10.

These pins are apart from the center line of the rule 50, for adaptation thereof to rods or mandrels 49 of different diameters, by simple turning.

In the closed position, the upper base 16 comes, for such rolling, bear on the rod or mandrel 49 used.

To take account of the change thus made in the tilting capacity of the upper base 16, the flanges 33A, 33B are removed, and, depending on the diameter of the rod or mandrel 49 used, a choice is made between the distances d 'articulation D'l, D "1 able to compensate for the effects of this difference.

After such a choice, the flanges 33A, 33B are replaced.

Thus, in the example of implementation illustrated in FIG. 6, it is through their lower hole 39 "A, 39" B that the flanges 33A, 33B are engaged on the studs 40A, 40B of the rods 34A, 34B, and no longer by their lower hole 39A, 39B, as previously.

Leaving aside such an adaptation, the folding machine according to the invention is made, for such rolling, according to the same process as previously.

Figure 7 relates to the legs 15A, 15B which is provided with this folder.

On the underside of the lower base 10 are reported transversely, at a distance from each other, two cylindrical crosspieces 53 of which only one is visible in the figures, and more precisely in FIG.

It is understood that provisions similar to those which will be described for this crosspiece 53 are adopted for the other.

Such a cross-member 53 can be established between two flanges 54 attached by welding to the wings 12 of the lower bed base 10.

Anyway, on such a cross 53 the base 15B is pivotally engaged, and it is thus articulated between a folded waiting position, not shown, for which it extends substantially parallel to the lower base 10, in below it, and a deployed position of use for which, as shown, it is in abutment against an abutment flange 56 secured to the lower bed base 10, and more precisely flanges 54 extending downwardly thereof.

A wing nut screw 58 allows the legs 15B to be locked on this abutment flange 56.

Preferably, and as shown, for its articulation with the cross-member 53, the base 15B comprises a hook 59.

It is thus removable, such a hook 59 being able to be brought into a position for which it can escape from the crosspiece 53.

In the embodiment shown, the base 15B consists of two feet 60, which diverge from one another, and which are connected to each other, in addition to the hook 59, by a crosspiece 61, and by a flange 62 capable of cooperating in support with the abutment flange 56.

According to the embodiment shown in Figures 8 to 14, each flange 33A, 33B is adjustable in position vis-à-vis the cylindrical bar 38, transversely vis-à-vis this bar.

In practice, for its engagement on the bar 38, each flange 33A, 33B has an elongated recess 70, it is a slot opening to the outside in the embodiment shown, and, in the axis d 'elongation of this recess 70, it has a threaded bore 71 in which is engaged by screwing an adjustment screw 72 capable of acting transversely on the bar 38.

In the embodiment shown, the threaded bore 71 is formed in a nut 73 added by welding on the flange 33A, 3jB concerned, in the vicinity of the end of the recess 70 thereof, transversely with respect to such a recess.

In addition, and as shown, between the bar 38 and such a flange 33A, 33B is interposed a sleeve 74 on which carries the corresponding adjustment screw 72, and which thus prevents it from opposing the rotation of this flange 33A, 33B opposite the bar 38.

This socket 74 has, at least locally, a groove 75, by which it is engaged on the edge of the flange 33A, 33B concerned, for its blocking in rotation thereon.

In the embodiment shown, two such grooves 75 are provided, parallel to each other, in diametrically opposite positions, for engagement on the edge of the two lips of the recess 70 of the flange 33A, 33B concerned.

As is easy to understand, by action on the adjustment screws 72, it is possible to absorb any possible play due to the inevitable manufacturing and mounting tolerances, in particular those resulting from the welding to which the bar 38 is subjected, each flange 33A, 33B coming, by means of the corresponding socket 74, to carry by the bottom of its recess 70 on the corresponding end of the cylindrical bar 38, and it is therefore possible to avoid untimely play when tightening between the upper base 16 and the lower base 10.

As before, the upper base 16 is constituted by a simple angle.

But this angle is internally reinforced by a wall 77, which transversely extends from one of its wings 18, 20 to the other, and which, longitudinally, is curved, being convex towards the outside, so that its width is reduced by a whistle from its central part to its ends.

The stiffening of the angle thus constituting the upper base 16 is advantageously improved.

Experience shows that, conditions being equal moreover, it is thus possible, for a given clamping force, to be satisfied with a relatively light upper bed base, thanks to the stiffening of which it is the object, and, in any case, with a notably lighter upper bed frame than those usually used for the execution of this same work.

According to the alternative embodiment of FIGS. 8 to 14, finally, it is associated with the folder at least one connecting rod 78 capable of being established transversely, in a removable manner, from the upper base 16 to the lower base 10, and, in practice, as shown, two such tie rods 78 to be distributed longitudinally along the upper base 16 are provided.

As can be seen in FIGS. 13 and 14, such a tie rod 78 comprises a screw 79, the head 80 of which is capable of bearing on the upper bed base 16, and a nut 81, which is carried by the bed base lower 10 for engagement in screwing of the threaded rod 82 of said screw 79.

To install a screw 79, the wing 18 of the upper base 16 has a passage 83, which can be circularly closed, as shown, or which can be opened with a notch downwards.

In correspondence with such a passage, the internal wall 77 of the upper base 16 itself comprises a passage 84, but this has a diameter less than that of the head 80 of a screw 79, so that this head 80 is thus able to bear on this internal wall 77.

In correspondence with the passages 83, 84, the lower base 10 itself comprises a passage 85, and it is the same for the wedge 50 usually implemented for a hemmer work.

Preferably, and as shown, the nut 81 participating in the constitution of a tie rod 78 is carried by a lever 87 articulated to the lower base 10, in the internal volume thereof, along an axis of articulation A4 parallel to the articulation axes A1, A2, A3 previously mentioned.

The realization of such an articulation axis A4 will not not described in detail here: it suffices for example to attach to the lower bed base 10 two sockets, in the extension of one another, on either side of the corresponding end of the lever 87, and there insert an axis.

At the same time, for the support of such a lever 87, a stop lug 90 is pivotally mounted on the lower bed base 10.

In the embodiment, this stop lug 90 is carried by a rod 91, which runs over the entire length of the lower bed base 10, and which, at its ends, materializes the hinge axis A3 by which the links 34A , 34B are articulated to said lower bed base 10.

The tie rods 78 according to the invention are used when it comes to hemming the sheet metal 17 to be worked, by forming this sheet metal around a mandrel 49.

For the folded closed position of the upper bed base 16 shown in FIG. 13, the lugs 90 carried by the rod 91 then come into contact with the levers 87 carrying the nuts 81 of these tie rods 78.

There is thus thus, in addition to the clamping force provided by the toggle locking means described above, a force for blocking the upper base 16, the latter being buttressed by the tie rods 78, themselves buttressed by the pins 90 integral with the lower base 10.

The working conditions of the folder when used as a hemmer are improved.

In such a case, in fact, the upper base 16, during tightening, bears only by a relatively small bearing surface on the mandrel 49 used for forming the sheet metal 17 to be hemmed, this surface reducing to a generator of such a mandrel.

As a result, the pressure developed on this upper base 16 during the hemming of the worked sheet 17 is very large, and it could lead to an untimely lifting of this upper base 16 in its central zone, in particular when the reach of that - between its ends is important.

The tie rods 78 according to the invention oppose to such an uprising,

The conditions being equal, moreover, the range of the folder can be increased, without risk of deformation of its upper base 16 when tightened.

This advantage, combined with that of a relatively low weight for this upper box spring 16 for the reasons explained above, makes it possible to extend the field of application of the folder according to the invention not only to site works only, for which it is more particularly intended for, but also for the more important work usually carried out in the workshop using more bulky, heavier, and more expensive folding machines.

Furthermore, the stop lugs 90 being driven in rotation by the rod 91 during a tilting of the assembly in the direction of the deployed position for opening the upper bed base 16, there is advantageously, taking into account the clearances at the crossing passages in which the tie rods 78 are engaged, the possibility of raising the upper bed base 16 by a sufficient amount to remove after hemming the sheet metal 17 worked or put in place a new sheet metal 17 to work, without prior removal tie rods 78, Figure 14.

Indeed, during such a limited opening, the assembly generally behaves, at each of its ends, like a deformable parallelogram.

When working in series, the use of tie rods 78 according to the invention therefore does not prohibitively increase the time necessary for the work to be carried out, no repetitive adjustment being necessary between two hemming operations. successive.

For a simple folding, FIG. 4, the tie rods 78 are not used, and, for example, as shown, the levers 87 carrying the nuts 81 rest freely on pins 92 carried by flanges 93 forming bearings intermediates for rod 91; alternatively, these levers 87 then hang freely.

The present invention is moreover not limited to the embodiments described and shown, but encompasses any variant.

For example, if rolling work is to be carried out with possible adaptation to a larger number of rod or mandrel diameters, a number of lower holes greater than three may be provided for the flanges 33A, 33B.

It is moreover not imperative that these flanges have holes for the production of the hinge pins to be formed.

They could on the contrary, and in a reverse arrangement to that described, projecting studs, for engagement in holes provided for this purpose on the organs to which they must be articulated.

Finally, the slot constituting the recess 70 of the flanges 33A, 33B in the variant embodiment of FIGS. 8 to 14 can be replaced by a buttonhole, and / or the threaded bore in which the adjustment screw 72 is engaged associated with a such a flange can be offset transversely with respect to the recess 70 while having an axis parallel to the direction of elongation of this recess 70.

Claims (20)

1. Folder of the kind comprising a lower bed base (10), which is fixed, an upper bed frame (16), which is mounted movable between a folded closed position, for which with the lower bed frame (10), it cooperates in the maintenance of 'a sheet of metal (17) to be worked, and a deployed open position, for which it leaves free access to said lower bed (10), a rotary table (24), which is adjacent to the lower bed (10), along a straight working line, and which is pivotally mounted around said working line, and disengageable locking means of the toggle type suitable for coupling the upper bed base (16) to the lower bed base (10) for the closed position of said upper base (16), such a folding machine characterized in that said toggle locking means comprise, for each end of said upper base (16), a removable flange (33A, 33B), which is articulated to the upper base (16) , along a first axis of articulation (A1), and a link (34A, 34B), which is articulated to said flange (33A, 33B), along a second articulation axis (A2) parallel to the previous one, and to the lower bed base (10), along a third articulation axis (A3) parallel to the previous two, the distance separating the two most distant articulation axes from one another being slightly different from the sum of the distances separating these two axes from each other, for crossing a line of maximum resistance between the open position and the closed position of the upper bed base. 2. Folder according to claim 1, characterized in that each flange (33A, 33B) of its locking means comprises a first hole (36A, 36B) hereinafter called the upper hole, by which it is rotatably engaged on a bar cylindrical (38) carried by the upper base (16), and at least one second hole (39A, 39B), hereinafter called the lower hole, by which it is rotatably engaged on a lug (40A, 4 ₀ B) carried projecting from the link (34A, 34B) with which it is associated. 3. Folder according to claim 2, characterized in that each flange (33A, 33B) of its locking means comprises a multiplicity of lower holes (39A, 39B), the centers of which are two by two at different distances from that of the upper hole. 4. Folder according to any one of claims 2,3, characterized in that the cylindrical bar (38) on which is engaged a flange (33A, 33B) of its locking means runs all along the upper base (16) and is common to the two flanges (33A, 33B). 5. Folder according to claim 4, and in which, to the upper bed (16), is associated a tensioner between which and said upper bed is established at least one spacer cylinder (44), for example a single screw, characterized in that said tensioner is constituted by the cylindrical bar (38) on which the flanges (33A, 33B) are engaged, said bar (38) being connected to said upper base (16) by at least two fixing points (43A, 43B) spaced from each other, and the one or more jacks (44) being disposed between said attachment points. 6. Folder according to any one of claims 1 to 5, characterized in that each of the flanges (33A, 33B) of its locking means is adjustable in position vis-à-vis the bar (38) on which it is engaged in rotation, transversely with respect to this bar. 7. Folder according to claim 6, characterized in that, for its engagement on the bar concerned, a flange (33A, 33B) has an elongated recess (70), such as a slot or buttonhole, and, parallel to the direction elongation of this recess, and for example in the axis thereof, it has a threaded bore (71) in which is engaged to screw an adjustment screw (72) adapted to act transversely on said bar (38) . 8. Folder according to claim 7, characterized in that, between the bar (38) and a flange (33A, 33B), is interposed a sleeve (74) on which carries the adjusting screw (72). 9. Folder according to claim 8, characterized in that, externally, said sleeve (74) has, at least locally, a groove (75) by which it is engaged on the edge of the flange (33A, 33B), for its blocking rotating on it. 10. Folder according to any one of claims 1 to 9, in which the upper base (16) is constituted by an angle, characterized in that said angle is reinforced internally by a wall (77), which, transversely, s' extends from one of its wings to the other. 11. Folder according to claim 10, characterized in that, longitudinally said wall (77) is curved, being convex towards the outside, so that its width is reduced by a whistle from its central part to its ends. 12. Folder according to any one of claims 1 to 11, characterized in that it further comprises at least one tie rod (78) capable of being established transversely, in a removable manner, from the upper base (16) to the base lower (10). 13. Folder according to claim 12, characterized in that said tie rod (78) comprises a screw (79), the head (80) of which is capable of bearing on the upper base (16), and a nut (81 ), which is carried by the lower base (10) for screw engagement of the threaded rod (82) of said screw (79). 14. Folder according to claim 13, characterized in that the nut (81) of the tie rod (78) is carried by a lever (87) articulated to the lower base (10) along a hinge axis (A4) parallel to the previous ones. 15. Folder according to claim 14, characterized in that a stop lug (90) is pivotally mounted on the lower base (10), for support of the lever (87) carrying the nut (81) of the tie rod ( 78). 16. Folder according to claim 15, characterized in that the link (34A, 34B) associated with a flange (33A, 33B) is articulated to the lower base (10) by a rod (91) running over the entire length of it- ci, and in that the stop lug (90) is carried by said rod (91). 17. Folder according to claims 10 and 13, taken together, characterized in that the head of the tie rod (78) bears on the internal wall (77) of the upper base (16). 18. Folder according to any one of claims 12 to 17, characterized in that at least two tie rods (78) are provided. 19. Folder according to any one of claims 1 to 18, characterized in that on the underside of the lower base (10) are reported transversely, at a distance from each other, two cylindrical crosspieces (53), and on each of these is pivotally engaged a base (15A, 15B), which is thus articulated between a folded waiting position and a deployed position of use, a stop flange (56) being provided on the lower base (10) for definition of this position of use. 20. Folder according to claim 19, characterized in that, for its articulation to the corresponding crosspiece (53), each base (15A, 15B) has a hook (59), and it is thus removable.

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