The present invention relates to a bending press or “press brake” having tables with controlled deformation.
Bending presses are machine tools of a type that is itself well known. As shown in accompanying
A metal sheet or lamination F is placed on the bending matrices 18 of the lower table 12. The sheet F may be of a length that varies widely depending on the circumstances. Under drive from the pistons of the actuators V1 and V2, the punches 22 mounted on the upper table move towards the metal sheet or lamination F placed on the matrices of the lower table. As soon as the punch 22 comes into contact with the sheet, force begins to increase within the sheet as the punch penetrates therein, initially in the elastic range and subsequently in the plastic range, thereby enabling the sheet to be bent permanently.
Because the force is applied to the upper table 14 by the actuators V1 and V2 acting on the ends of the table, the linear load distributed between the two ends of the tables corresponds to the upper table being deformed along a line in the form of a concave arc with deformation maximas close to the midplane of the table. This means that, for bending purposes, at the end of bending, the central portions of the punches 22 have penetrated into the sheet F less than have the end portions. If bending were to be performed on a matrix that, itself, were to remain perfectly straight during bending, then the result would be that a workpiece would be obtained having a bend angle that was wider in its central portion than at its ends. Such a result is naturally unacceptable.
In order to remedy that drawback, various solutions have been proposed for the purpose of controlling these deformations at the edges of the tables by using various means in order to obtain a bend that is substantially identical over the entire length of the bent workpiece.
Conventionally, these solutions involve providing slots, such as the slots 24 and 26 shown in
In addition to the difficulty of proposing a bending press that is suitable for enabling the metal lamination or sheet F for bending to be deformed substantially uniformly over the entire length of said lamination or sheet F, regardless of whether its length is short compared with the length of the tables 12, 14 of the press or, on the contrary, is equal to the length of the tables 12, 14 of the press, there exists an additional difficulty related to managing the deformation of the top edges 24″, 26″ of the slots 24, 26 while the bending force of the moving table 14 is being applied to the stationary table 12, and said force is being taken up on the bottom edges 24′, 26′ of the slots 24, 26, such management of said management being hitherto poorly mastered.
An object of the present invention is to remedy these two problems by proposing to place at least one pair of wedges, each wedge of the pair being disposed in a respective one of the slots 24, 26. The invention also further comprises adjustment means that are common to both of the wedges of the pair of wedges and that are suitable for moving said wedges of the pair of wedges in their respective slots 24, 26 for adjusting as well as possible the force take-up.
The invention thus provides a press brake for bending at least one metal sheet, said press brake comprising:
one of said tables having two slots, each slot having a first edge and a second edge, and an open first end opening out in a side edge of the table, as well as a closed end;
wherein said press brake further comprises:
the adjustment means comprise a primary control lever for moving the two wedges of the pair of wedges together, preferably by the same distance.
In embodiment, each wedge of the pair of wedges is connected to the primary control lever via at least one link.
In an embodiment, the adjustment means move the wedges of the pair of wedges in opposite directions. In these circumstances, the links that connect the two wedges of the pair of wedges respectively to the primary control lever are coupled to said lever on either side of the fulcrum of said lever.
In another embodiment of the invention, the adjustment means move the wedges of the pair of wedges in the same direction. In these circumstances, the links that connect the two wedges of the pair of wedges respectively to the primary control lever are coupled to said lever on the same side of the fulcrum of said lever.
Preferably, the press brake of the invention has at least two pairs of wedges, the two wedges of each pair of wedges being disposed in respective ones of the two slots.
In an aspect of the invention, the wedges of the two pairs of wedges are moved by the primary control lever.
In a possibility offered by the invention, in addition to the primary control lever suitable for moving the wedges of the first pair of wedges, said press brake has a secondary control lever suitable for moving the wedges of a second pair of wedges. In this embodiment, the secondary control lever is advantageously associated with the primary control lever so that the position of the secondary control lever is adjustable relative to the position of the primary control lever and so that, by actuating the primary control lever, the wedges of the first and second pairs of wedges can be moved together.
In a particularly advantageous aspect of the invention, the adjustment means are suitable for moving the first pair of wedges by a first distance and the second pair of wedges by a second distance, the first and the second distances being proportional to each other.
Advantageously, the primary control lever and the secondary control lever are mounted to pivot about a common fulcrum.
In an advantageous aspect of the invention, each wedge of said at least one pair of wedges co-operates with a stationary second wedge to form a stopper set.
In these circumstances, each wedge of said at least one pair of wedges advantageously has a first end secured to the first slot edge and a second end forming a contact surface for coming into contact with the wedge with which it forms a stopper set.
In an advantageous aspect of the invention, at least in the zone of the wedges, the slots have a constant height so that the first edge and the second edge are parallel, in the absence of bending force for bending the metal sheet.
Advantageously, the contact surface of at least one of the wedges of each stopper set is inclined at a slope lying in the range 1% to 40% and preferably in the range 5% to 10%, relative to the parallel edges of the slots.
In an embodiment, the press brake has a vertical midplane P′P, the two slots being disposed symmetrically about said midplane. Preferably, the two slots extend through the entire thickness of the table.
Other characteristics and advantages of the invention appear more clearly on reading the following description of preferred embodiments of the invention given by way of non-limiting example. The description refers to the accompanying drawings, in which:
As shown in
Each of the wedges 28, 28′, 29, 29′ is mounted on a respective support 40, 41 connected to a respective edge 24′, 26′ or 24″, 26″ of a respective one of the slots 24 and 26. The function of each wedge 28, 28′, 29, 29′/stopper 27 is to control the extent to which the edges 24′, 24″ and 26′, 26″ of each slot 24, 26 move towards each other when the bending force is applied. By controlling the extent to which the edges 24′, 24″ and 26′, 26″ of the slot 24 or 26 move towards each other, it is possible to control the deformation of the top edge 24″, 26″ of the slot 24, 26, and therefore the deformation of the top edge 12a of the lower table 12.
At least one of the supports 40 or 41, and optionally both of the supports 40 and 41 is/are mounted to move laterally, i.e. along an axis parallel to the parallel edges 24′, 26′ and 24″, 26″ of the slots 24, 26 on which it is mounted.
In the examples chosen to illustrate the invention in the accompanying figures, only the supports 40 are suitable for being moved by adjustment means of the invention, but naturally the supports 41 of the wedges 28 or 28′ could also be movable. It should however be noted that it is the relative positioning of the two wedges 28, 29, or 28′, 29′ that belong to the same stopper, and thus that are designed to come into contact with each other, that is important, so that by moving only one of them 28, 28′ or 29, 29′, relative adjustment of the position of the wedges 28, 29 or 28′, 29′ is obtained so that the forces are taken up well from one wedge to the other. The relative position of two wedges 28, 29 or 28′, 29′ that are designed to come into contact with each other can be adjusted by the adjustment means of the invention to within one hundredth of a millimeter for the wedges of as many pairs of wedges as desired.
A first object of the invention lies in moving the two wedges of a pair of wedges 29, 29′ symmetrically, i.e. so that moving one wedge of the pair of wedges 29, 29′ towards or away from the midplane P′P results in the other wedge of the pair of wedges 29 or 29′ being moved towards or away from said midplane in exactly identical manner. Such an object is achieved by the embodiment shown in
In
The links 61 and 62 that are of the same length connect the wedges of the pair of wedges 29 that is situated closest to the midplane P′P to the primary control lever 50. Each of the two links 61, 62 has an end fastened to one of the wedges 29 and its other end 61′, 62′ fastened to the lever head 50A in the vicinity of the pivot axis O. The distance between each end 61′, 62′ of the links 61 and 62 and the axis O is equal to the same relatively short distance d, e.g. equal to 5 millimeters (mm). In this example, the ends 61′ and 62′ are fastened to the lever head 50A on either side of the axis O, symmetrically thereabout, and the ends 61′, 62′ and the fulcrum O are aligned.
In the same way, each of the links 60 and 63, of the same length, has one end fastened to one of the wedges 29′ and another end 60′, 63′ fastened to the head 50A of the primary control lever 50 at the same distance D from the pivot axis O, e.g. equal to 40 mm. The two ends 60′ and 63′ of the two links 60, 63 are, like the ends 61′, 62′ of the links 61, 62, situated on either side of the pivot axis O, and the ends 60′, 63′ and the axis O are aligned.
When the primary control lever 50 is actuated so that its lever head 50A is pivoted through a certain angle, it pivots the respective ends 60′, 63′, and 61′, 62′ of the links 60, 63 and 61, 62 so that the links 61 and 62 move each wedge of the pair of wedges 29 by the same first distance, while the links 60, 63 move each wedge of the pair of wedges 29′ by a second distance. The ratio k of the second distance to the first distance is equal to the ratio of the distances D to d. The invention thus makes it possible to adjust the relative position of the wedges of the two pairs of wedges 29 and 29′ in proportional manner.
In this embodiment, the movement of the links 61, 62, and 60, 63 is a movement that moves the two wedges of each of the pairs of wedges 29 or 29′ towards or away from the midplane P′P due to the fact that the links 61, 62 and 60, 63 are mounted respectively in pairs with, for each link of a pair 61, 62 or 60, 63, their respective ends 61′, 62′ and 60′, 63′ situated on either side of the pivot axis O. In the embodiment shown in
When the ends 61′, 62′ of the two links 61, 62 are situated respectively on the same side of the pivot axis O, the wedges of the pair of wedges 29 are moved in the same direction so that if one of the wedges of the pair of wedges 29 moves away from the midplane P′P, the other wedge of the pair of wedges 29 moves towards the midplane P′P. Naturally, the ends 60′, 63′ of the two links 60, 63 being disposed in the same way on the same side of the pivot axis O has the same effect on the movement of each wedge of the pair of wedges 29′. In this embodiment (not shown in the accompanying figures), the movements of each of the pairs of wedges 29 and 29′ are movements that are not symmetrical about the midplane P′P.
Advantageously, the position of the primary control lever 50 is indexable.
This end 80 of the primary control lever 50 is provided with a handle having a rod suitable for being inserted into a plurality of indexing holes 100 so that, once the primary control lever 50 has been moved, said lever is retained in the desired position; each of the indexing holes 100 defines a pivot angle for the primary control lever 50 and thus, a degree of actuation for said lever. The end 80 of the primary control lever 50 is suitable for being manipulated by an operator or optionally by an automated system that is suitable for pivoting the primary control lever 50.
In the embodiment shown in
It should be noted that, in the example chosen to illustrate the invention, there exist nine indexing holes for moving the secondary control lever 52 relative to the primary control lever 50 (from the position “4” to the position “−4”, via the position 0 at which the two levers 50 and 52 coincide), as indicated in
As shown in
In this second embodiment, the primary control lever 50 is moved from its initial position (position 0) to its position “3”, thereby causing a respective proportional movement k of each of the wedges of the two pairs of wedges 29 and 29′. Then, the operator or the automated system has the possibility of moving only those wedges of the pair of wedges 29 that are situated closest to the midplane P′P, e.g. by causing the handle of the end 81 of the secondary control lever 52 to go from the position “4” to the position “−4” (i.e. from one extreme position to the other) so that, finally, after the two levers 50 and 52 have been moved, the proportional movement between the wedges of the two pairs of wedges 29 and 29′ is no longer equal to said ratio k but rather to a ratio (k+γ), where γ is a function of the movement of the secondary control lever 52 that is suitable for moving only the wedges of the pair of wedges 29.
It should be noted that it is also possible, within the ambit of the present invention, for the control levers 50 and 52 to be independent from each other. In such an embodiment (not shown in the accompanying figures), the primary control lever 50 may for example pivot the links 60, 63 only, while the secondary control lever 52 pivots the links 61, 62.
Even though the invention is illustrated with two pairs of wedges, one wedge of each of the pairs 29, 29′ being disposed in each of the slots 24, 26, the invention is applicable regardless of the number of wedges of pairs of wedges disposed in each of the slots 24, 26.
Number | Date | Country | Kind |
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0951613 | Mar 2009 | FR | national |