Apparatus for bending a metal sheet

Abstract: An apparatus for bending a metal sheet (1) comprises a frame (2), a stationary lower beam (3) with a lower clamp (4), a movable upper beam (5) with an upper clamp (6), said clamps each having a clamping face for clamping a metal sheet in a working position, a lower bending beam (7) and an upper bending beam (8) for bending a clamped metal sheet upwardly and downwardly, respectively, said bending beams each at both sides being supported rotatably around a corresponding axis in a support plate (9), said support plates being movably mounted in the frame in such a manner that the lower or upper bending beam can be moved into a working position, in which its axis is substantially in the plane of the clamping face of the lower or upper clamp, respectively. Further a device (12) for holding the metal sheet is provided, said holding device being provided with a mainly C-shaped frame (13) with a slide (14) movable backwards and forwards between a front and a back position on a slide bed (15), the legs (17,18) of the C-shaped frame carrying a lower and upper disc (19,20), respectively, adapted to engage a metal sheet in a working position. In the front position of the slide the legs of the C-shaped frame extend between the upper and lower beams and the lower and upper discs adjoin the clamps.

Description: The invention relates to an apparatus according to the preamble of claim 1. Such an apparatus is disclosed in DE-A-36 05 815. Although the lower and upper discs of the holding device of this known apparatus can be moved near to the clamps, this is only possible because the C-frame is located at the side opposite of the support of the support plates in the frame. US-A-5 138 865 discloses an apparatus for bending a metal sheet comprising a device for rotating a metal sheet around a vertical axis and a gripping assembly movable with respect to the rotation device. By means of the gripping assembly the metal sheet can be located between the upper and lower clamps of the bending apparatus. The invention aims to provide an improved apparatus of the above-mentioned type. To this end the apparatus according to the invention shows the features of claim 1. The invention will be further explained by reference to the drawings, in which an embodiment of the apparatus according to the invention is schematically shown. Fig. 1 shows schematically a side view of an embodiment of the apparatus according to the invention. Fig. 2 shows schematically a top view of the apparatus of Fig. 1. Fig. 3 is a section of the support table of the apparatus of Fig. 1. Fig. 4 is a top view of the part of support table shown in Fig. 3. Fig. 5 shows schematically a side view partially in cross-section of an auxiliary device for the apparatus of Fig. 1. Fig. 6 is a partially shown top view of the auxiliary device of Fig. 5. Fig. 7 is a side view partially in cross-section of the clamp of the auxiliary device of Fig. 5. Fig. 8 is a front view partially in cross-section of the clamp of Fig. 7. Figs. 1 and 2 show an apparatus for bending a metal sheet 1, comprising an only schematically indicated frame 2, a stationary lower beam 3 with a lower clamp 4, a movable upper beam 5 with an upper clamp 6. In the side view of Fig. 1 the clamps 4, 6 have a cross-section with a thickness and a height, wherein the height is substantially greater than the thickness. Further, the apparatus comprises a lower bending beam 7 and an upper bending beam 8 for bending upwardly or downwardly, respectively, the clamped metal sheet 1. The bending beams 7, 8 each are at both sides rotatably supported around a corresponding axis in a pivot plate 9 (see Fig. 2), wherein the pivot plates are rotatably supported in the frame 2 independent of the upper beam 3. Thereby the lower bending beam 7 or the upper bending beam 9 can be moved into a working position, in which the corresponding axis lies substantially in the plane of the clamping face of the lower clamp 4 or the upper clamp 5, respectively. In Fig. 1 the lower bending beam 7 is in the working position. The pivot plates 9 are not shown in Fig. 1 for the sake of clarity. It is noted that instead of pivot plates 9, support plates can be used if desired, which are connected with the frame 2 slidably upwards and downwards. Fig. 1 shows that the lower clamp 4 and the upper clamp 6 in their working position in which they engage the metal sheet 1, determine a V-shape in cross-section, the top thereof being directed towards the axis of the bending beam 7 or 8 being in the working position. Such a V-shaped position of the clamps 4, 6 shows the advantage that the reaction forces on the clamps 4, 6 occurring during bending can be received without deformation of these clamps. Moreover, these reaction forces will only result in increasing the force by which the clamps 4, 6 clamp the metal sheet 1. The lower beam 3 and the upper beam 5 each have a triangular shape in cross-section, wherein the front triangular side is mainly aligned with the web of the lower clamp 4 and the upper clamp 6, respectively. Due to the elongated rectangular shape of the clamps 4, 6, the triangular sides of the lower beam 3 and the upper beam 5 facing each other lie at a relatively large distance from each other, whereby a rather large free space is available between these beams 3, 5. As shown in Fig. 1, the upper beam 5 is rotatably mounted in the frame 2 around an axis 11 by means of pivot plates 10. In the embodiment described this axis 11 coincides with the axis of the pivot plates 9 carrying the bending beams 7, 8. The above-described apparatus is described in more detail in the earlier Dutch patent application 1000459 of the applicant. The construction of this apparatus itself is not the subject of the present application. The apparatus described further comprises a device 12 for holding the metal sheet 1, said holding device 12 being provided with a mainly C-shaped frame 13. The C-shaped frame 13 is mounted on a slide 14 movable forwards and backwards on a slide bed 15. The slide 14 is movable backwards and forwards between a front position shown in Fig. 1 and a back position indicated by a dashed line 16. The legs 17, 18 of the C-shaped frame 13 carry at their free end a lower disc 19 and an upper disc 20, respectively, engaging the metal sheet 1 in the working position shown in Fig. 1. These discs 19, 20 are rotatably connected with the legs 17, 18, so that the metal plate 1 can be rotated in the apparatus described. As shown in Fig. 1, the legs 17, 18 of the frame 13 project between the lower beam 3 and the upper beam 5 in the front position of the slide 14 in such a manner that the discs 19, 20 are adjacent the clamps 4, 6. In order to be able to bring the discs 19, 20 as close as possible near the clamping face of the clamps 4, 6 a recess is preferably provided in each clamp 4, 6 as indicated by a dashed line 21, so that the discs 19, 20 can be partially received in the same. In this manner it is obtained that it is also possible to hold working pieces with the device 12 which protrude along a very small distance only from the clamps 4, 6. Preferably each leg 17, 18 has an extension 22, 23, said extensions 22, 23 extending in a V-shaped manner corresponding to the V-shape of the clamps 4, 6. The upper leg 18 of the C-shaped frame 13 is connected rotatably to the remaining part of the frame 13 at 24', wherein the actuation takes place by means of a driving member 24 which is for example made as a cylinder-piston assembly. By actuating the driving member 24 the upper disc 20 is removed from the metal plate 1 and the working piece can be removed or the metal sheet to be bended can be placed in the apparatus. The C-shaped frame 13 is rotatably connected to the slide 14 at 25, whereas at the other side of the slide 14 a driving member 26, for example a cylinder-piston assembly, is provided between the slide 14 and the frame 13 for pivoting the frame 13 around the axis 25. Thereby the discs 19, 20 in their working position can be pivoted into a position indicated by a dashed line 27, so that the metal sheet 1 with a part bent downwardly can be lifted above the lower clamp 4 and the lower bending beam 7. For the sake of completeness it is noted that instead of a pivot movement of the frame 13 another movement for lifting the discs 19, 20 is possible, for example a movement up and down. The bending apparatus described is further provided with a support table 28 for supporting the metal sheet 1, which support table is movable between the position shown in Fig. 1 and a position indicated by a dashed line 29. Thereby it is possible to support also working pieces with downwardly projecting parts on the support table 28. In the embodiment described the direction of movement of the support table 28 is mainly obliquely substantially parallel to the direction of the lower clamp 4. Driving the support table 28 takes place in the described embodiment in the manner schematically indicated in Fig. 1 by means of a cylinder-piston assembly 56 driving at both sides of the slide bed 15 two L-shaped levers 57 through a coupling rod 58. The levers 57 are rotatably supported at 59 and the front levers 57 are interconnected by a shaft in the rotation point 59. The top view of Fig. 2 shows that the support table 28 includes a central intermediate space 30, in which the slide bed 15 and the slide 14 with the C-shaped frame 13 are located. At both sides of the slide bed 15 the support table 28 is provided with a support 31 and a plurality of hollow support profiles 32 extending substantially transverse to the axis of the bending beams 7, 8. The support profiles 32, one of which being shown in more detail at a larger scale in Figs. 3 and 4, are slidably mounted on the support 31. To this end the support 31 is provided with V-shaped guides 33 and each support profile 32 has guiding blocks 34 cooperating with these guides 33. One of the guiding blocks 34 is slidably in longitudinal direction of the support profile 32 by means of a pulling rod 35 which can be operated by a handle 36. Thereby the support profiles 32 can be fixed in any desired position on the support 31 with an adjustable mutual intermediate space between the adjacent support profiles 32. It is also possible to remove one or more support profiles 32 from the support 31. In this manner downwardly bended edges of a working piece can be received in the intermediate space between adjacent support profiles 32. The end of the support profiles 32 adjacent the lower clamp 4 extends obliquely mainly parallel to the lower clamp 4. It is noted that the support table 28 is of course provided with retractable stop elements known per se for determining the starting position of a metal sheet to be bended. These stop elements are not shown in the drawings. The holding device 12 can be equipped in an advantageous manner with an auxiliary device for holding a metal plate at the side edges extending transverse to the axis of the bending beams 7, 8. This device is schematically shown in Figs. 5-8. As shown in Fig. 5, the device is mounted on the lower leg 17 of the C-shaped frame 13 of the holding device 12. The end of the lower leg 17 can be seen in Fig. 5, wherein the lower disc 19 which is normally provided, is removed and is replaced by a rotating disc 37 driven by a schematically indicated shaft 38 by means of which normally the lower disc 19 is driven. The auxiliary device comprises a support beam 39 fixed to the lower leg 17 by means of a schematically indicated coupling 40. This support beam 39 extends along the full width of the bending apparatus and carries at each end an arm 41, one of which is shown in the top view of Fig. 6. Each arm 41 can be fixed in any desired position on the support beam 39 by means of a clamp 42. Further, the support beam 39 supports a spline shaft 43 which is rotatably supported at its ends in a support 44. The spline shaft 43 is driven through the rotation disc 37 by the drive of the lower disc 19 not further shown. To this end the rotation disc 37 is provided with an arm 45 driving the driving shaft 46 of a right-angled transmission 47. Both arms 41 carry a pulley driven by the splined shaft 43, which pulley drives a driving belt 48'. A clamp 49 is rotatable by means of this driving belt 48', which clamp 49 is rotatably borne in the free end of the arm 41. In this advantageous manner the metal sheet 50 held by the clamps 49 can be rotated by means of the already available drive of the lower disc 19. The clamp 49 is shown in more detail in Figs. 7 and 8. The actuation of the clamp 49 takes place by means of an actuating member 51 which in this case is made as a cylinder-piston assembly. Actuation of the clamp can only take place in the position of the clamp 49 shown in Figs. 5 and 8. The piston pin 52 of the actuating member 51 can in this position cooperate with a wedge-shaped actuating element 53 of the clamp 49. When this actuating element 53 is pressed to the right according to the view of Fig. 8, the jaws 54 of the clamp 49 are opened against the action of schematically indicated springs 55. When the piston pin 52 is retracted, these springs 55 press the jaws 54 into the position shown in Fig. 7. In this manner a very compact construction of the clamp 49 is obtained, so that the main part of the working width of the bending apparatus can be used effectively. The invention is not restricted to the above-described embodiment which can be varied in a number of ways within the scope of the claims.

Claims: Apparatus for bending a metal sheet (1), comprising a frame (2), a stationary lower beam (3) with a lower clamp (4), a movable upper beam (5) with an upper clamp (6), said clamps (4, 6) each having a clamping face for clamping a metal sheet in a working position, a lower bending beam (7) and an upper bending beam (8) for bending a clamped metal sheet upwardly and downwardly, respectively, said bending beams (7, 8) each at both sides being supported rotatably around a corresponding axis in a support plate (9), said support plates being movably mounted in the frame in such a manner that the lower or upper bending beam can be moved into a working position, in which its axis is substantially in the plane of the clamping face of the lower or upper clamp, respectively, and further comprising a device (12) for holding the metal sheet, said holding device being provided with a mainly C-shaped frame (13) with a slide (14) movable backwards and forwards between a front and a back position on a slide bed (15), the legs (17, 18) of said frame carrying a lower (19) and upper disc (20), respectively, adapted to engage a metal sheet in a working position, characterized in that in the front position of the slide (14) the legs (17, 18) of the C-shaped frame (13) extend between the upper and lower beams (3, 5) and the lower and upper discs (19, 20) adjoin the clamps (4, 6). Apparatus according to claim 1, wherein a recess (21) is provided at the inner side of the lower and upper clamps (4, 6) for receiving the discs (19, 20). Apparatus according to claim 1 or 2, wherein the lower and upper clamps (4, 6) in the working position determine in cross-section a V-shape, the top of which is directed towards the axis of the bending beam (7, 8) being in the working position, wherein the legs (17, 18) of the C-shaped frame at their free ends each have an extension (22, 23), said extensions determining a V-shape in the working position, said V-shape corresponding with the V-shape of the clamps. Apparatus according to claim 1, 2 or 3, wherein at least the lower and upper discs (19, 20) in the working position are movable up and down with respect to the lower clamp (4). Apparatus according to claim 4, wherein the C-shaped frame (13) at the side opposite to the discs (19, 20) is connected to the slide (14) rotatably around an axis (25), wherein at the side of the slide facing the discs a driving member (26) is provided for pivoting the C-shaped frame around said axis. Apparatus according to anyone of the preceding claims, comprising a support table (28) for supporting the metal sheet, wherein the support table comprises a central intermediate space (30), in which the slide bed (15) and the slide (14) with the C-shaped frame (13) are located.

Inventors: LIET CORNELIS HENDRICUS, LIET, CORNELIS HENDRICUS
Applicants: LIET CORNELIS HENDRICUS, LIET, CORNELIS HENDRICUS
Application year: 1997
Main classification: B21D5
IPC codes: B21D5