EP3569323A1 - Folding press in which the fixed apron has slots - Google Patents

Abstract

The press brake comprises an upper apron (10) and a lower apron (12) vis-à-vis, one of the aprons being fixed while the other apron is configured to be moved in a vertical plane. The fixed deck (12) has a pair of horizontally elongated main slots (20) arranged symmetrically with respect to a median transverse plane (T) of this deck. This apron also has at least a first pair of additional slots (22, 24), also arranged symmetrically with respect to the median transverse plane (T) and horizontally elongated. The inner (22A) and outer (22B) ends of each slot (22) of the first pair of additional slots are located horizontally on either side of the inner end (20A) of the corresponding main slot (20).

Description

The present disclosure relates to a press brake for folding metal sheets or sheets, comprising an upper apron and a lower apron vis-à-vis, one of the aprons being fixed while the other apron is configured to be moved in a vertical plane.

Folding presses of this type are known, for example by patent applications FR 2 782 942 , EP 1 075 880 and FR 2 942 980 . In the following, we will consider for simplicity that it is the lower deck which is fixed, while the upper deck is moved vertically to bend a sheet disposed between these two aprons. Of course, the situation could be reversed, the upper deck being fixed while the lower deck being movable.

Starting from the principle that the upper deck is mobile, it undergoes deformation during the folding of a sheet disposed between the two aprons. More specifically, the folding edge of the upper deck both to adopt a concave shape, the arrow depends on the bending force and the distance between its areas to which the thrust force is applied. In general, the thrust to the lower deck is applied by jacks or the like located at the lateral ends of the upper deck.

However, it is important to make the fold of the sheet as accurately as possible. Therefore, it is sought to ensure that the lower deck tends to adopt a deformation similar to that of the upper deck. In particular, it can be sought to ensure that the folding edge of the lower deck adopts a convex shape complementary to the concave shape of the folding edge of the upper deck.

For this purpose, the patent application FR 2 782 942 proposes that the lower deck be provided with slots in which are arranged cylinders which control the spacing between the opposite edges of the slots, thus controlling the deformation of the folding edge of the lower deck. This solution is interesting, but it can be relatively expensive since it requires an adjustment and precise control of the control cylinders of the deformation of the slots.

The patent application EP 1 075 880 proposes that the lower deck be provided with slots extended by bores in which can be arranged sleeves for distributing the stresses.

The demand FR 2 942 980 also recommends to provide the lower deck two slots arranged symmetrically with respect to the median transverse plane of the deck, adjustable shims being arranged in these slots. Adjusting the wedges, which can adopt several configurations, allows to control the deformation of the slots and, consequently, the deformation of the folding edge of the lower deck.

These solutions are suitable for medium-sized machines, capable of processing sheets of length ranging from 1 to about 3 meters, or even 4 meters when controlled deformation control devices such as adjustable shims are used.

The patent application WO 0143896 also proposes a press brake whose folding edge of the lower deck can be deformed. For this purpose, this application recommends providing the lower deck two sets of slots, arranged symmetrically with respect to the median transverse plane of the deck. Each set includes several slots connected by points aimed, despite the large length of the slots, to control their deformation. However, the slots described in this document are either too close to the sides of the deck (on which they are open) to allow the processing of long-length sheets, or very extensive towards the inside of the deck.

However, the Applicant has found that slits of great lengths may reduce the yield strength of the lower deck, so that if the folding forces are important, the folding edge may undergo irreversible plastic deformation. Thus, there is a risk that the life of the press is significantly reduced.

Thus, the solution proposed in the application WO 0143896 does not give satisfaction, because this limit of plastic deformation is also quickly reached.

Thus, the present disclosure aims to propose a simple solution, substantially free of the aforementioned drawbacks, to allow the elastic deformations of the folding edge of the lower deck, even for presses adapted to the processing of long-length sheets, for example 3 meters, 4 meters or more.

Thus, the present disclosure relates to a press brake for folding metal sheets, comprising an upper apron and a lower apron vis-à-vis, one of the aprons being fixed while the other apron is configured to be displaced in a vertical plane, the fixed deck having a pair of horizontally elongated main slots disposed symmetrically with respect to a median transverse plane of said deck, the stationary deck further having at least a first pair of additional slots, also arranged symmetrically with respect to the median transverse plane and horizontally elongated, the inner and outer ends of each slot of the first pair of additional slots being located horizontally on either side of the inner end of the corresponding main slot.

By convention, it will be considered that the upper deck moves in a vertical plane, the horizontal direction being perpendicular to this plane. The indication that a slot is elongated horizontally is not limited to the case where this slot extends strictly horizontally. It is actually to mean that the horizontal dimension of the slot is greater than its vertical dimension. In other words, the orthogonal projection of the slot in a horizontal plane gives a length that is greater than that given by the orthogonal projection of the slot in a vertical plane. The slot can be horizontal, or be inclined relative to the horizontal, have a rectilinear shape or have a more complex shape, provided that its horizontal dimension is greater than its vertical dimension.

The Applicant has found that the presence of the additional slots, which are independent slots, distinct from the main slots and which have internal and external ends distant from the lateral sides of the deck makes it possible to increase the flexibility of the folding edge of the lower deck without as far as this flexibility becomes too important, insofar as the inner end of the main slot is located between the inner and outer ends of the additional slot.

For example, the main slots are open at their lateral ends on the sides of the lower deck, while the outer lateral ends of the additional slots are located at a distance from the sides of the lower deck and are closed in particular. A main slit and an additional slit located on the same side of the lower median transverse plane are considered. On the one hand, the inner end of the main slot is located between the inner and outer ends of the additional slot and, on the other hand, the outer end of the additional slot is located at a distance from the side edge of the lower deck, between the inner end of the main slot and the edge of this deck.

For the purposes of this presentation, the term "internal" an element disposed towards the median transverse plane and "external" an element disposed opposite the median transverse plane. Thus, when considering a slot, its inner end and the one that is close to the median transverse plane and its outer end is its opposite end, which is closer to the side of the deck.

Optionally, the horizontal distance between the inner end of each slot of the first pair of additional slots and the inner end of the corresponding main slot is between 20% and 60%, preferably between 35% and 55% of the length, measured horizontally, of the slots of the first pair of additional slots.

Optionally, the length of the slots of the first pair of additional slots is between 50% and 120%, preferably between 70% and 100%, of the length of the main slots.

Optionally, the fixed deck also has at least a second pair of additional slots, also arranged symmetrically with respect to the median transverse plane and horizontally elongated, the inner and outer ends of each slot of the second pair of additional slots being located horizontally from and other of the inner end of the corresponding slot of the first pair of additional slots.

Optionally, the inner end of each slot of the second pair of additional slots is located horizontally between the inner end of the corresponding main slot and the median transverse plane and, optionally, the outer end of each slot of the second pair of Additional slots are located horizontally between the inner end of the corresponding main slot and the median transverse plane.

Optionally, the horizontal distance between the inner end of each slot of the second pair of additional slots and the inner end of the corresponding slot of the first pair of additional slots is between 30% and 80%, preferably between 45% and 65% of the length, measured horizontally, of the slots of the second pair of additional slots.

Optionally, the length, measured horizontally, of the slots of the second pair of additional slots is between 40% and 80%, preferably between 50% and 70%, of the length, measured horizontally, of the slots of the first pair of slots additional.

Optionally, the additional slots are vertically located between the main slots and the folding edge of the fixed deck.

Optionally, the main slots are open on the sides of the fixed deck opposite the median transverse plane, while the additional slots have a closed contour.

Optionally, the inner end of each main slot is open in a bore that extends at an angle close to 360 °, this bore being configured to receive a removable rod.

Optionally, at least one of the ends of each slot of the first pair of additional slots, preferably both ends, is open in a bore which extends at an angle close to 360 °, this bore being configured to receive a removable rod.

Optionally, at least one of the ends of each slot of the second pair of additional slots, preferably both ends, is open in a bore which extends at an angle close to 360 °, this bore being configured to receive a removable rod.

Optionally, the slots of at least one of the slot pairs are configured to receive shims.

Optionally, the height of the fixed deck being measured between its edge facing the apron vis-à-vis and its opposite edge, the minimum distance between the main slots and said opposite edge is at least equal to 35% of said height.

The additional slots can be closed at both ends, internal and external, or at least almost closed, ie behave like closed slots from the beginning of the application of the bending force. . For example, at their outer ends, the edges can be very close together, so that they come into contact from the beginning of folding, before deformation of the rest of the slot.

The main slots may have conventional lengths, of the type commonly used on press brake aprons used for folding sheets of length of the order of one to three meters. The length of these slots may for example be of the order of 50 cm to 110 cm. Rather than extending these slots, the present disclosure provides for adding additional closed or near-closed slots at both ends, thereby increasing the deformability of the folding edge of the lower deck in regions going to the median transverse plane, without as much as creating a zone of continuous weakness in the apron.

In particular, the present disclosure is compatible with aprons made with a single plate, without the need for sandwich type structures, which are expensive. The tests carried out by the Applicant have found that the additional slots and the main slots in the conformations specified above make it possible to obtain good results. The additional slots may in particular be shorter, horizontally, than the main slots. The additional slots may be vertically located between the main slots and the folding edge of the lower deck. In other words, they are closer to this fold edge than the main slots and more located towards the median transverse plane than the latter. They thus come to create the desired flexibility in the plate forming the apron towards the folding edge, and near the median transverse plane, that is to say at a distance from the jacks or the like which request the displacement of the upper deck and apply the effort of folding against the lower apron.

• la figure 1 est une vue schématique en élévation d'une presse plieuse selon le présent exposé ;
• la figure 2 montre en élévation le tablier inférieur selon une variante.

The presentation will be well understood and its advantages will appear better on reading the detailed description which follows, of an embodiment shown by way of non-limiting example. The description refers to the accompanying drawings in which:

• the figure 1 is a schematic elevational view of a press brake according to the present disclosure;
• the figure 2 shows in elevation the lower apron according to a variant.

The press brake represented on the figure 1 comprises an upper apron 10 and a lower apron 12 vis-à-vis. In this case, the lower deck 12 is stationary, while the upper deck 10 is configured to be moved in a vertical plane back and forth from in order to fold sheets arranged between the respective folding edges 10A and 12A of the aprons.

For this purpose, for example, the press brake comprises cylinders 14 (here schematized by arrows) arranged towards these lateral ends, and which are controlled by control means such as an electronic control unit (not shown) to cause the movement back and forth of the upper deck 10. This movement is also guided by guide means such as flanges, rods or the like 16, also arranged at the lateral ends of the press brake.

The press brake has a median transverse plane T, which is here vertical and with respect to which it is generally symmetrical.

We see on the figure 1 that the lower deck has a pair of main slots 20. These slots are arranged symmetrically with respect to the median transverse plane T. In this case, these main slots are open on the sides 13A and 13B of the lower deck 12. In other cases In other words, the outer ends of these slots 20 are open. In contrast, their inner ends 20A are closed.

The lower deck 12 also has a first and a second pair of additional slots, respectively 22 and 24. These slots are also arranged symmetrically with respect to the median transverse plane T and, as the main slots, are elongated horizontally, that is to say that their orthogonal projections on a horizontal plane XX give lengths greater than their orthogonal projections on a vertical plane YY perpendicular to the plane XX. The horizontal plane XX is parallel to the orientation of the folding edges 10A and 12A of the aprons in their undistorted state, and is perpendicular to the median transverse plane T which is parallel to the vertical plane YY. On the figure 1 the respective projections of the slots 20, 22 and 24 on the plane XX are indicated by the references X20, X22 and X24 and, by the references Y20, Y22 and Y24, the projections of these slots on the vertical plane YY are indicated. In this case, on the diagram of the figure 1 the slots are oriented horizontally. As will be seen in the following, this is not necessarily the case, because the slots can be inclined relative to the horizontal plane, and be linear or have more complex shapes, with bent or curved portions.

In this case, the slots are arranged in steps. If we look at the set of slots located on the same side of the median transverse plane T, we see that the slots are shifted so that the closer a slot is near the median transverse plane T, the closer it is of the folding edge 12A. We also see that the horizontal projections of these slots overlap partially. Indeed, the inner ends 22A and outer 22B of the additional slot 22 are located on either side of the inner end 20A of the main slot 20. Similarly, the inner ends 24A and outer 24B of the slot 24 are located horizontally on either side of the inner end 22A of the slot 22. Thus the horizontal projection X22 of the slot 22 in the plane XX partially overlaps the horizontal projection X20 of the slot 20. Similarly, the horizontal projection X24 of the slot 24 partially overlaps that of the slot 22.

The inner end 24A of the slot 24 is located horizontally between the inner end 20A of the slot 20 and the median transverse plane T. It is also seen that, unlike the slot 22, the slot 24 is not overlapping Thus, in this case, the outer end 24B of the slot 24 is located horizontally between the inner end 20A of the slot 20 and the median transverse plane T.

In regions where the slots are in horizontal overlap, the ability of the folding edge 12A to deform under the load is locally increased. The staggered arrangement of the various slots and the partial overlap thus makes it possible to locally increase the deformation capacity of the edge 12A in the zones Z1 and Z3 in which the slots 20 and 22 on the one hand and the slots 22 and 24 on the other share overlap horizontally. In this case, between the zones Z1 and Z3, a non-overlap zone Z2 is provided in which only the slot 22 is present. This makes it possible to distribute the deformation capacity of the folding edge of the fixed deck over its length and to avoid that a limit of plastic deformation is too easily reached.

As will be seen in the following, stiffening or adjustment devices may be arranged in the slots to obtain the desired distribution of the deformation arrow.

With reference to the figure 2 a particular configuration of the slots is now described by way of example. For simplicity, we have not shown in this figure that the fixed deck 112. The slots of this deck comprise a pair of main slots 120 and a first and a second pair of additional slots 122 and 124. The slots of the different pairs are arranged symmetrically with respect to the transverse plane median T. In addition, the fixed deck has a central slot 126 disposed in its central region, on either side of the median transverse plane T.

This central slot 126 has a closed contour. In this case, its face 126 'opposite to the folding edge 112A is convex, while its opposite edge 126' is rectilinear.The fact of providing a central slot makes it possible to separate the folding edge 112A with respect to the opposite edge 112B, in order to prevent the folding edge from being influenced by the possible deformation of the edge 112B.

Like those of the embodiment of the figure 1 the slots 120, 122 and 124 are horizontally elongated. We indicated on the figure 2 their horizontal projections X120, X122 and X124, as well as their vertical projections Y120, Y122 and Y124. Overall, the additional slots 122 and 124 are oriented horizontally. Slots 124, the closest to the folding edge 112A, which are in this case the slots of the second pair of additional slots, are generally thin, that is to say they only allow deformation on one side. low vertical amplitude. The slots 122 have thin end sections between which extends a wider median section. This wider section locally has an increased deformation capacity, however, it is noted that it is not in horizontal overlap with the slot 124 and that it is slightly overlapping with the slot 120 and with a bore 120C, in which s opens slit 120 and will be described later.

The slots 120 have a particular shape since, at their outer ends open in the sides 113A and 113B of the deck 112, they are closer to the folding edge 112A than their inner ends 120A. As in the embodiment of the figure 1 the additional slots 122 and 124 are vertically located between the main slots 120 and the folding edge 112A. Similarly, the main slots are open on the sides of the aprons while the additional slots have a closed contour.

Bores 124C and 122C are respectively formed at the ends 124A, 124B and 122A, 122B of the slots 122 and 124. As will be seen below, these bores can be used for the introduction of rods.

Because of their conformation and their particular function, the aforementioned bores are not taken into account to measure the lengths of the slots corresponding to their horizontal projections X120, X122 and X124. Similarly, the outer end 120B of the slot 120 opens on the side 113A of the deck 112 in a cavity 120D. This cavity, which can be used to house a shim, is also not taken into account to measure the length of the slot 120, corresponding to its horizontal projection X120.

As indicated, the slots of the first pair of additional slots are in partial horizontal overlap with the corresponding main slots. In the present case, the horizontal distance LI1 between the inner end 22A or 122A of each slot 22 or 122 of the first pair of additional slots and the inner end 20A or 120A of the corresponding main slot 20 or 120 is between 20 % and 60%, preferably between 35% and 55%, of the length X22 or X122 respectively.

In other words, the horizontal overlap length between the additional slot and the main slot may be of the order of 40% to 80% of the length of this additional slot, preferably between 45% and 65% of this slot. length.

In addition, in the present case, the length X22 or X122 of the slots of the first pair of additional slots 22 or 122 may be between 50% and 120%, preferably between 70% and 100%, of the length X20 or X120. main slots 20 or 120, respectively.

Rather than extending the main slots to increase the capacity of the folding edge of the fixed deck to deform, we add the additional slots that are located in a region of the fixed deck different from that of the main shapes, in this case in a region located between these slots and the folding edge, to both obtain a deformability effect specific to these additional slots in the region where they are not in horizontal overlap with the main shapes, and an effect combined with that of the main shapes in the region where they are recovering.

In this case, the horizontal distance LI2 between an inner end 24A or 124A of the slot 24 or 124 and the inner end 22A or 122A of the additional slot 22 or 122 is between 30%, preferably between 45% and 65%. % of the X24 or X124 length of slot 24 or 124, respectively. Thus, the horizontal overlap length between the slots 22 and 124 is of the order of 20 to 70%, preferably 35% to 55% of the length of the slot 24 or 124.

In this case, the length X24 or X124 of the slot 24 or 124 is between 40% and 80%, preferably between 50% and 70%, of the length X22 or X122 of the slot 22 or 122 respectively.

By focusing on the figure 2 it can be seen that the horizontal distance LIC between the central slot 126 and the inner end 124A of the slot 124 is of the order of 20% to 40% of the length X126 of the central slot, for example of the order of half that length. In general, when the central slot is present, it is desirable that sufficient length exists between the inner end of the nearest slot of the main and additional slots and the adjacent end of this central slot. Sufficient length means a length generally greater than 10% of the half-length LT of the folding edge 112A measured between one side of this edge and the median transverse plane T.

As indicated, the inner ends of the main slots, as well as the inner and outer ends of the additional slots, are in this case open on bores, respectively 120C, 122C and 124C which extend on an angle close to 360 °. This means that the junction zone between the considered end of the slot and the bore in which it is open extends over a small part of the contour of this bore, representing for example an angular sector of the order of 5 to 15 mm. ° measured with respect to the geometric center of the bore.

As stated in the patent application EP 1 075 880 this conformation makes it possible, thanks to the curvature of the bore, to avoid the stress peaks at the end of the slot and to stiffen the slots concerned, in particular by arranging in the bores of the rods (which may be solid or formed by sleeves) that can be tightly mounted in the bores to distribute the bending stresses in the regions surrounding the bores.

In addition, the main slots and / or the slots of the first or second pairs of additional slots can accommodate stiffening wedges. These shims can for example be arranged and configured as indicated in the patent application. FR 2 942 980 . They are generally arranged symmetrically with respect to the median transverse plane T and their positions in the slots allow to control the deformations. However, it should be noted that, thanks to the presence and the arrangement of the additional slots according to the present disclosure, it is possible to treat sheet lengths of more than 3 meters, for example of the order of 4 meters with a correct folding accuracy, without necessarily having to use controlled deformation control devices such as adjustable shims. On the other hand, such devices may become useful for long lengths of sheet metal, in order to further improve the bending accuracy.

We found out about figures 1 and 2 the height H of the fixed deck, measured between the folding edge 12A or 112A and the opposite edge, 12B or 112B of the deck. The height D between the main slots and the said opposite edge 12B or 112B is preferably at least equal to 35% of the height H. As it is a slot of complex shape that is not strictly horizontal, this height D is the minimum distance between the slot and the opposite edge, without taking into account the possible presence of 120C bores mentioned above.

Claims (14)

Press brake for folding metal sheets, comprising an upper apron (10) and a lower apron (12) vis-à-vis, one of the aprons being fixed while the other apron is configured to be moved in a vertical plane, the fixed deck (12) having a pair of horizontally elongated main slots (20; 120) disposed symmetrically with respect to a median transverse plane (T) of said deck, the fixed deck further having at least a first pair additional slots (22, 24; 122, 124), also arranged symmetrically with respect to the median transverse plane (T) and horizontally elongated, the inner (22A; 122A) and outer (22B; 122B) ends of each slot (22; 122) of the first pair of additional slots being located horizontally on either side of the inner end (20A; 120A) of the corresponding main slot (20; 120). A press brake according to claim 1, wherein the horizontal distance (LI1) between the inner end (22A; 122A) of each slot (22; 122) of the first pair of additional slots and the inner end (20A; 120A). the corresponding main slot (20; 120) is between 20% and 60%, preferably between 35% and 55% of the horizontally measured length (X22; X122), slots of the first pair of additional slots. Press brake according to claim 1 or 2, wherein the length (X22; X122) of the slots (22; 122) of the first pair of additional slots is between 50% and 120%, preferably between 70% and 100% the length (X20; X120) of the main slots (20; 120). A press brake according to any one of claims 1 to 3, wherein the fixed apron (12) further has at least a second pair of additional slots (24; 124), also arranged symmetrically with respect to the median transverse plane (T horizontally elongated, the inner (24A; 124A) and outer (24B; 124B) ends of each slot (24; 124) of the second pair of additional slots being located horizontally on either side of the inner end (22A; 122A) of the corresponding slot (22; 122) of the first pair of additional slots. A press brake according to claim 4, wherein the inner end (24A; 124A) of each slot of the second pair of additional slots (24; 124) is located horizontally between the inner end (20A; 120A) of the slot corresponding main end (20; 120) and the median transverse plane (T) and optionally the outer end (24B; 124B) of each slot (24; 124) of the second pair of additional slots is located horizontally between the end internal (20A; 120A) of the corresponding main slot (20; 120) and the median transverse plane (T). A press brake according to claim 4 or 5, wherein the horizontal distance (LI2) between the inner end (24A; 124A) of each slot (24; 124) of the second pair of additional slots and the inner end (22A 122A) of the corresponding slot (22; 122) of the first pair of additional slots is between 30% and 80%, preferably between 45% and 65% of the horizontally measured length (X24; X124) of slots (24; 124) of the second pair of additional slots. A press brake according to any one of claims 1 to 6, wherein the length (X24; X124) measured horizontally, slots (24; 124) of the second pair of additional slots is between 40% and 80%, preferably between 50% and 70%, horizontally measured length (X22; X122), slots (22; 122) of the first pair of additional slots. A press brake according to any one of claims 1 to 7, wherein the additional slots (22, 24; 122, 124) are vertically located between the main slots (20; 120) and the folding edge (12A; 112A). fixed deck (12; 112). Press brake according to any one of claims 1 to 8, wherein the main slots (20; 120) are open on the sides (13A, 13B; 113A, 113B) of the fixed deck opposite to the median transverse plane (T), while the additional slots (22, 24; 122, 124) have a closed contour. A press brake according to any one of claims 1 to 9, wherein the inner end (120A) of each main slot (120) is open in a bore (120C) which extends at an angle close to 360 °, this bore being configured to receive a removable rod. A press brake according to any one of claims 1 to 10, wherein at least one of the ends (122A, 122B) of each slot (122) of the first pair of additional slots, preferably both ends, is open in a bore (122C) extending at an angle close to 360 °, this bore being configured to receive a removable rod. A press brake according to claim 4 taken in combination with any one of claims 1 to 11, wherein at least one of the ends (124A, 124B) of each slot (124) of the second pair of additional slots, Preferably both ends, is open in a bore (124C) which extends at an angle close to 360 °, this bore being configured to receive a removable rod. A press brake according to any one of claims 1 to 12, wherein the slots of at least one of the pairs of slots (20, 22, 24; 120, 122, 124) are configured to receive shims . Press brake according to any one of claims 1 to 13, wherein the height (H) of the fixed deck being measured between its edge (12A; 112A) facing the deck opposite and its opposite edge, the Minimum distance (D) between the main slots and said opposite edge is at least 35% of said height.

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