|
(11) | EP 0 213 667 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
|
|
|
|
|||||||||||||||||||||||||||
| (54) | Method and apparatus for bending sheet-like work pieces |
| (57) An apparatus for bending sheet-like work pieces comprise a main frame, a die having
a longitudinally extending groove, a stamp, a stop for determining the position of
a work piece with respect to the die, clamping means for clamping a working piece
and a frame. The frame supports the stop and the clamping means and is pivotably around
a pivot axis substantially coinciding with the groove of the die. Further the apparatus
includes a lifting arm for the work pieces pivotably connected with the main frame. The frame is pivoted into a position extending obliquely downwardly form the pivot axis and a work piece is picked up from a storage location by the lifting arm and is laid on the obliquely pivoted frame Thereby the work piece automatically shifts against the stop. whereafter the work piece is clamped in the position as determined by the stop and the frame is pivoted into a substantially horizontal position. |
[0001] The invention relates to a method for bending sheet-like work pieces in an apparatus comprising a die having a longitudinally extending groove, a stamp, a stop for determining the position of a work piece with respect to the die, clamping means for clamping a work piece and a frame for supporting the stop and the clamping means and being pivotable around a pivot axis substantially coinciding with the groove of the die, and to an apparatus for carrying out this method.
[0002] Such an apparatus is described in EP-A-0 140 394, wherein a work piece has to be shifted from the front of the apparatus against the stop, whereafter the clamping means clamp the work piece. During bending a work piece the frame pivots with the bending work piece under control of a control unit. At this known apparatus the accuracy of the products obtained is also determined by the accuracy with which the operators place the work piece against the stop. Moreover at this known apparatus one or two persons should continuously be present for operating the apparatus and feeding the work pieces, whereby the costs of the products obtained are increased.
[0003] The invention aims to provide a method and apparatus of the above-mentioned kind, wherein these disadvantages are obviated in a simple manner.
[0004] To this end the method according to the invention is characterized in that the frame is pivoted into a position extending obliquely downwardly from the pivoting axis and in that a work piece is picked up from a storage location by a lifting arm and is laid on the obliquely pivoted frame so that the work piece automatically shifts against the stop, whereafter the work piece is clamped in the position as determined by the stop and the frame is pivoted into a substantially horizontal position.
[0005] Thereby it is obtained that the work piece is fed automatically into the apparatus and will abut the stop in the right manner, so that for the same series of products an operation of the apparatus is not required anymore and the products will be manufactured with a high accuracy.
[0006] Preferably after bending the work piece the frame is pivoted into the position extending obliquely downwardly from the pivoting axis and the bent work piece is removed from the frame and laid down at a discharge location by the lifting arm.
[0007] The apparatus according to the invention is provided with a main frame, a die having a longitudinally extending groove, a stamp, a stop for determining the position of a work piece with respect to the die, clamping means for clamping a work piece and a frame for supporting the stop and the clamping means and being pivot able around a pivot axis substantially coinciding with the groove of the die, and is characterized by a lifting arm for the work pieces pivotably connected with the main frame.
[0008] According to a preferred embodiment the lifting arm is supported by a carrying plate rotatably borne around a vertical axis in a holder. Thereby, during bending the work piece, this work piece can be taken up from the frame by the lifting arm and after an angular rotation along each angle desired can be laid down on the frame again. In this manner different sides of for example a rectangular work piece can be bent.
[0009] According to a favourable embodiment of the apparatus, the lifting arm comprises a carrier movable upwards and downwards and provided with a plurality of nozzles connectable to a source of underpressure and being cardan suspended to pins of the carrier. Thereby the position of the nozzles can be easily adapted to the position of the work piece during taking up and lying down of a work piece.
[0010] As in the known apparatus, the frame may be provided with two clamping jaws each being carried by an arm, said arms being slidable longitudinally and laterally with respect to the die, wherein according to the invention the frame comprises a plurality of supporting arms extending laterally to the die for supporting a work piece, wherein a supporting arm is connected with each clamping jaw arm, while the remaining supporting arms are fixedly mounted to the frame between the clamping jaw arms. Thereby a stable supporting of the work piece is obtained.
[0011] In this case it is to be preferred that the fixed supporting arms are provided with holding means for temporarily holding a work piece. In this manner it is possible to temporarily hold the work piece by the holding means of the fixed supporting arms and to shift the clamping jaws laterally to the die, whereafter the clamping jaws again clamp the work piece and a bending operation can be carried out on a next part of the work piece.
[0012] According to a preferred embodiment of the invention the apparatus comprises means for rotating a work piece around an axis lying substantially in the plane of the work piece.
[0013] In this manner an apparatus is obtained wherein the work piece can be rotated around two axes which cross each other perpendicular, whereby the work piece each time can be placed against the stop of the apparatus in such a manner that a next bending operation of the work piece is possible without the possibility that a part of the work piece is pressed against the stamp or die during bending.
[0014] The invention will hereinafter be further explained with reference to the drawings in which two embodiments of the apparatus according to the invention are schematically shown.
Fig. 1 schematically shows a cross-section of an embodiment of the apparatus according to the invention for bending sheet-like work pieces, wherein the lifting arm is shown in a first position by a full line and in a second and third position by dashed lines.
Fig. 2 schematically shows a top view of the frame with the clamping jaws and the supporting arms.
Fig. 3 is a cross-section of a nozzle of the apparatus of fig. 1.
Fig. 4 is a cross-section corresponding with fig. 3, wherein the nozzle engages a schematically shown work piece.
Fig. 5 schematically shows a cross-section of a second embodiment of the apparatus according to the invent ion.
Fig. 6 shows two cross-sections of a work piece to be supplied to the apparatus of fig. 5 and of a profile bent by the apparatus, respectively, wherein the different bending lines are indicated by a-f.
Fig. 7a-7f show the subsequent steps for making the profile of fig. 6.
[0015] Fig. 1 schematically shows a cross-section of an apparatus for bending sheet-like work pieces comprising a main frame 1 with two web plates 2 lying on both sides of the apparatus and only one of which being shown in fig. 1. The main frame 1 further comprises a lower beam 3 and an upper beam 4 which is movable towards the lower beam 3 by means of two cylinder piston assemblies 5 one of which being shown in fig. 1. The lower beam 3 and the upper beam 4 each are provided with a rotatably mounted carrier 6, said carriers each having a die part 7 with a longitudinally extending groove and a stamp part 8 with a line-shaped contact zone. The die part 7 and the stamp part 8 of each carrier each can be rotated into a working position directed towards the other carrier 6. Thereby the apparatus described can bend a work piece in any desired shape. The construction of this part of the apparatus is further disclosed in the above-indicated European patent application.
[0016] The apparatus further is provided with a frame 9, a top view of which is schematically shown in fig. 2. The frame 9 is supported by the main frame 1 pivotably around a pivot axis by means of two arms 10 in a manner not further shown. With the stamp part 8 directed towards the carrier 6 of the upper beam 4 this pivot axis substantially coincides with the line-shaped contact zone of the stamp part 8. Both arms 10 are interconnected by a box beam 11. Laterally with respect to the box beam 11 two boxes 12 are mounted slidably supporting a support beam 13. The support beam 13 is movable by screw spindles 14 which can be driven through drive belts 15 by a motor 16 supported on the box beam 11. Two slide - blocks 17 are slidably mounted on the support beam 13, each of said slide blocks 17 carrying an arm 18 directed towards the die part 7 or the stamp part 8. On the end of each arm 18 a clamping jaw 19 is mounted which can grip the side of a work piece. By shifting the support beam 13 the distance of the clamping jaws 19 from the die part 7 or the stamp part 8 can be varied.
[0017] A supporting arm 20 is mounted on each slide block 17 for supporting a work piece to be placed on the frame 9. Further two fixed supporting arms 21 are provided attached to the box beam 11. The upper sides of the supporting arms 20 and 21 lie in one plane and thus provide a stable support for a work piece to be placed on the frame 9.
[0018] The slide blocks 17 each have a lowered part 22, the upper surface of which lies in one plane with the upper sides of the supporting arms 20 and 21. With the clamping jaws 19 in the open position a work piece of big sizes may thus extend beyond the slide blocks 17 if required.
[0019] As appears from fig. 1 and 2 the boxes 12 each carry a guiding roller 23 running along a corresponding guide way 24. Pivoting of the frame 9 is controlled by a control mechanism not shown which can be made in any desired manner. The control takes place by means of a programmable control unit in response to the movement of the upper beam 4 with respect to the lower beam 3. This movement can be measured in the usual manner by means of two potentiometers supported by the web plates 2, the movable contacts of which are connected with the respective ends of the upper beam 4. Thereby the control unit is able to cause the frame 9 to follow the bending of the work piece so that no undesired bending of the work piece can take place and the work piece will be maintained in position continuously by the clamping jaws 19.
[0020] The apparatus further is provided with a lifting arm 25 by means of which the plate-shaped work pieces schematically indicated in fig. 1 by reference sign 26 can be taken up from a storage location 27 and can be laid down on the frame 9. The lifting arm 25 is supported by a carrying plate 28 borne in a holder 30 rotatably around a vertical axis 29. This holder 30 is suspended substantially in the centre of the apparatus by two support beams 31, only one of which is shown in fig. 1. These support beams 31 each are pivotably connected by one end with a bearing roller 32 movable in a support rail 33. The support rail 33 laterally extending with respect to the die part 7 or the stamp part 8 is mounted on the corresponding web plate 2. The end of the support beam 31 connected with the bearing roller 32 is connected with an upward bracket 35 of the support rail 33 by a cylinder piston assembly 34. Further this end of the support beam 31 is connected with a second bearing roller 37 by a rod 36 extending in the support rail 33. A second cylinder piston assembly 39 is provided between this second bearing roller 37 and a lever 38 attached to the support beam 31.
[0021] By means of the cylinder piston assembly 39 the lifting arm 25 with the support beams 31 can be pivoted into any desired position. A possible position is shown in fig. 1 with a dashed line 40. By means of the cylinder piston assembly 34 the lifting arm 25 with the support beam 31 can be moved to a discharge location 31, which position is indicated by a dashed line 32. The cylinder piston assemblies 34 and 39 are controlled by the programmable control unit mentioned above.
[0022] The lifting arm 25 comprises a cylinder piston assembly 43 supported by the carrying plate 28, a carrier 44 being fixed on the free end of the piston rod of this cylinder piston assembly 43. On both sides of the piston rod guiding rods 45 are mounted on the carrier 44, only one of which being shown in fig. 1. These guiding rods 45 are slidably guided through the carrying plate 28. The carrier 44 is provided with pins 46 which are slidably mounted in the carrier 44 against the action of springs 47. The downwardly projecting ends of the pins 46 carry nozzles 48 which may engage a work piece 26.
[0023] When a work piece 26 to be bent must be placed in the apparatus, the frame 9 is brought into a position extending obliquely downwardly from the pivot axis by the control unit; for example the position shown in fig. 1. The control unit actuates the cylinder piston assembly 43 of the lifting arm 25 whereby the nozzles 48 are pressed on the upper work piece 26 in the storage location 27. As will be described further hereinafter, these nozzles 48 are connected to a source of underpressure not shown, so that the work piece 26 is sucked against the nozzles 48. The lifting arm 25 than can be moved to the position shown in fig. 1 in full lines. Subsequently the cylinder piston assembly 39 is actuated and the lifting arm arrives in the position indicated with the dashed line 40, whereafter the work piece is laid down on the obliquely extending frame 9 by actuating the cylinder piston assembly 43. The underpressure is now removed, so that the work piece 26 is released and the control unit moves the lifting arm 25 into the position shown in full lines again.
[0024] Due to the oblique position of the frame 9 the work piece 26 automatically slides downwards until it abuts the stop projections 49, 50 or 51 carried by the fixed supporting arms 21. Thereby it is obtained that a work piece 26 laid down on the oblique frame 9 will lie against the stop projections 49, 50 or 51 with certainty so that the work piece 26 will have an accurately determined position on the frame 9.
[0025] The stop projections 49 and 50 lying closest to the die part 7 or the stamp part 8 are retractable, for example because they can be pressed downwardly against the action of a spring. The stop projections 51 are mounted fixedly. Work pieces of lower sizes will abut the stop projections 49 after being released by the nozzles 48 of the lifting arm 25, whereas work pieces with bigger sizes will abut on the stop projections 50 or 51. In the position determined by the stop projections 49, 50 or 51, the work piece 26 is clamped by the clamping jaws 19. The frame 9 with the clamped work piece 26 now is brought in a substantially horizontal position, whereafter the work piece can be bent in the desired shape. During bending the frame 9 follows the movement of the work piece 26 under control of the control unit. As the die part 7 and the stamp part 8 of the carriers 6 of the lower beam 3 and the upper beam 4 can be interchanged, the work piece 26 can be bent in two directions, so that the work piece needs not to be turned upside down. Thereby the accuracy of the product manufactured will be very high.
[0026] When the support beam 13 can not be brought closer to the die part 7 or the stamp part 8 anymore, holding means 52 mounted in the fixed supporting arms 21 are energized and the clamping jaws 19 opened. Thereafter, the support beam 13 can be moved backwards, wherein in a new position the clamping jaws 19 again clamp the work piece 26 and the holding means 52 are de-energized. The required bending operations can now be carried out on a further part of the working piece 26. The arms 18 carrying the clamping jaws 19 are also provided with holding means 52. These holding means 52 may for example be made as nozzles connectable to a source of underpressure.
[0027] When a bending operation should be carried out on the side part of the work piece 26 opposite of the die part or the stamp part 8, the frame is pivoted into an oblique position again, whereafter the lifting arm 25 is moved to the position 40. After actuating the cylinder piston assembly 43 and when the nozzles 48 engage the work piece 26, the carrying plate 28 is rotated in the holder 30 along 180° so that said side part of the work piece is directed towards the die part 7 or stamp part 8. Of course it is also possible to rotate the carrying plate 28 along a different angle, for example 900, so that an other side of the work piece 26 can be treated.
[0028] When all operations on the work piece 26 are carried out and the product is finished, the frame 9 is again pivoted into an oblique position and the finished product is taken up from the frame 9 by the lifting arm 25. By actuating the cylinder piston assembly 34 the lifting arm 25 is brought into the position indicated by the dashed line 42 and the product is discharged on the discharge location 47.
[0029] From the foregoing it appears that the apparatus described is adapted to bend fully automatically work pieces into the desired end products under control of the control unit, wherein the dimensions of the end products meet high accuracy requirements.
[0030] The position of the lifting arm 25 indicated by the dashed line 40 generally will not be completely adapted to the oblique position of the frame 9 without accurate angular measurements. In order to obtain nevertheless a good engagement of the nozzles 48 on the surface of a work piece 26, the nozzles 48 are cardan suspended on the pins 46 of the carrier 44. As appears from fig. 3 and 4, to this end each pin 46 is provided with a rounded head 53 accommodated with clearance in a chamber 54. Thereby each nozzle 48 is freely movable in all directons so that the position of the nozzle 48 can be adapted to the position of a work piece 26.
[0031] Each nozzle 48 is provided with a body 55 carrying a ring 56 consisting of a flexible material, for example rubber. The ring 56 has a sealing face 57 extending obliquely upwardly from a lowest circular edge 58. The ring 56 surrounds an open chamber 59 which is connected through a passage 60 and a channel 61 with a connector for a source of underpressure. The passage 60 is normally closed by a closing valve 63, which is maintained in the closed position by a spring 64. The closing valve 63 has an actuating pin 65 projecting downwardly.
[0032] When the nozzle 48 is pressed against a work piece 26, the position of fig. 4 will be reached. The work piece 26 forces the closing valve 63 open through the actuating pin 65, wherein the chamber 59 is connected to the source of underpressure. The edge 58 will initially sealingly engage the surface of the working piece 26, whereby the ring 56 is sucked inwards somewhat and the sealing face 57 is drawn sealingly on the surface of the work piece 26. Thereby a very good sealing engagement on the surface of the work piece 26 is obtained so that the nozzle 48 will not get loose easily. Relatively heavy work pieces 26 can already be lifted with a low number of nozzles 48.
[0033] It is noted that as an alternative for said three stop projections 49-51 on each fixed supporting arm 21, a slidable stop projection can be mounted.
[0034] Referring to fig. 5 there is schematically shown a cross-section of a second embodiment of the apparatus for bending sheet-like work pieces comprising a main frame 101 with two web plates 102 lying on both sides of the apparatus, only one of which being shown in fig. 5. The main frame 101 further comprises a lower beam 103 and an upper beam 104, which is movable towards the lower beam 103 by means of two cylinder piston assemblies 105, only one of which is shown in fig. 5. The lower beam 103 is provided with an rotatably mounted lower carrier 106 while the upper beam 104 is provided with a rotatably mounted upper carrier 107. The lower carrien 106 and the upper carrier 107 each are equiped with a die part 108 with a longitudinal groove and a stamp part 109 with line-shaped contact zone. The die part 108 and the stamp , part 109 of the upper and lower beams 106, 107 each can be brought into a working position directed towards the upper or lower beam 107, respectively. The construction of this part of the apparatus is further described in European patent application 0 140 394.
[0035] The apparatus further is provided with a frame 110 corresponding to the frame 9 of the apparatus of fig. 1. The frame 110 is supported by the main frame 100 pivotably around a pivot axis by two arms 111 in a manner not further shown. This pivot axis substantially coincides with the line-shaped contact zone of the stamp part 109 when the stamp part 109 is directed towards the upper carrier 107 of the upper beam 104. The frame 110 supports two clamping means 112 which are adapted to grip both sides of a work piece fed into the apparatus. The distance between the two clamping means 112 can be adapted to the size of the work piece as the clamping means 112 are slidably mounted on a support beam 114 by arms 113. The frame 110 further is provided with stops not shown in the drawing which determine the position of a work piece placed in the apparatus with respect to the die part 108 or the stamp part 109 of the lower carrier 106. Further the frame 110 is provided with supports 115 for supporting the work piece. These supports 115 are slidably mounted on a box beam 116.
[0036] It is noted that the frame 110 with its pivot axis is movable substantially in a vertical direction by means further described in Dutch patent application 85.00410.
[0037] The frame 110 on both sides is provided with a guiding roller 117 guided by a corresponding guide way 118. The guide ways 118 are attached on the web plates 102 of the apparatus. The pivoting movement of the frame 110 takes place by means of a control mechanism not shown which can be made in any desired manner. The control is carried out by means of a programmable control unit in response to the movement of the upper beam 104 with respect to the lower beam 103. This movement can be measured in the usual manner by two potentiometers supported by the web plates 102, the movable contacts of which are connected with the corresponding ends of the upper beam 104. Thereby the control unit can cause the frame 110 to accurately follow the bending of the work piece so that no undesired bending of the work piece can take place and the work piece is continuously maintained in the correct position by the clamping means 112.
[0038] The apparatus described further is provided with a lifting arm 119 by means of which plate-shaped work pieces 120 can be taken up from a storage location 121 and can be laid upon the frame 110. With the example of the work pieces 120 shown in the drawings, these work pieces are pre-processed. The lifting arm 119 comprises a cylinder piston assembly 122 which is rotatably borne in a housing 124 together with guiding means 123 on both sides. The housing 124 is suspended substantially in the centre of the apparatus in two loading arms 125, the ends of which opposite of the housing 124 are rotatably connected_with a beam 126 fixed on the corresponding web plate 102. A coupling rod 127 between the housing 124 and the beams 126 provides for an accurate positioning of the housing 124 in the starting position of fig. 5 and the loading position indicated by a dashed line. The pivoting movement of the lifting arm 119 takes place by means of a cylinder piston assembly 128, wherein the control is carried out by the above-mentioned programmable control unit.
[0039] A carrier.129 is fixed on the free end of the piston of cylinder piston assembly 122, said carrier 129 being provided with a plurality of rows of suction-cups 130 which can engage a work piece. The row of suction-cups 130 adjacent the apparatus is slidably connected with the carrier 129 so that the distance between the suction-cups 130 is adjustable in correspondence with the width of a work piece to be bent.
[0040] At the side of the apparatus opposite of the lifting arm 119 two arms 131 are mounted, one end of each of said arms being rotatably connected with a corresponding support 132. The supports 132 are slidably mounted on the lower beam 103, the supports 132 each resting against the lower beam 103 with a roller 133. At the upper side the supports 132 engage a supporting shaft 134, both halves of which are provided with a screw-thread with opposite pitch so that by rotating the shaft 134 the supports 132 can be moved towards and away from each other in order to accommodate to the length of the work piece.
[0041] At their free end each of the arms 131 is provided with a rotatably driven clamping means 135 only schematically indicated. By these clamping means 135 a work piece can be taken up from the frame 110 in the position 136 indicated with a dashed line, when the pivot axis of the frame is displaced upwardly in vertical direction. Thereafter the arms 131 are displaced to a rotating position 137 also indicated by a dashed line, in which position the clamping means 135 are driven, whereby the work piece is rotated around a horizontal axis which lies substantially in the plane of at least a portion of the work piece.
[0042] As already mentioned above and described in detail for the apparatus of fig. 1, the cylinder piston assembly 122 with the carrier 129 is rotatably mounted in the housing 124, so that it is possible during a bending operation on a work piece to take up this work piece from the frame 110 and to rotate the same around an axis perpendicular to the plane of the work piece.
[0043] Therefore, the apparatus according to fig. 5 provides the possibility to rotate the work piece around two axes crossing perpendicular, whereby substantially any profile can be bent without any problems.
[0044] The control of the lifting arm 119, the arms 131 and the clamping means 135 takes place by the above-mentioned control unit. This control unit is also adapted for bringing in the working position the die part 108 or the stamp part 109 of the lower and upper beams 106, 107.
[0045] Fig. 6 shows a work piece 120, the subsequent bending lines where the work piece has to be bend being indicated by a-f. Further fig. 6 shows the profile 138 obtained by bending the work piece 120. In fig. 7a-7f the subsequent bending operations on the work piece are shown, wherein the die part 108 and the stamp part 109 of the lower and upper carriers 106, 107 are partially shown. The bending operations shown in fig. 7a-7f correspond with the indications a-f in fig. 6.
[0046] The complete bending process described hereinafter by which the profile 138 is formed from the work piece 120, is controlled automatically by the said control unit which is equiped with a microprocessor, memories, and suitable input devices for the input of the required data.
[0047] By actuating the cylinder piston assembly 122 the lifting arm 119 takes a work piece 120 from the storage location 121, whereafter the lifting arm is brought into the loading position indicated by a dashed line by the cylinder piston assembJy 128. The frame 110 is in the shown oblique position. By again actuating the cylinder piston assembly 122, the work piece 120 is placed on the supports 115 of the frame 110, wherein the downwardly directed edge of the work piece 120 will abut the stop elements not shown. The clamping means 112 then clamp the work piece 120. The lifting arm 119 is moved to the shown position by the cylinder piston assembly 128, while the frame 110 is brought in a horizontal position.
[0048] By rotating the lower and upper carriers 106 and 107, the stamp 109 of the upper carrier 107 and the die part 108 of the lower carrier 106 are brought in the working position for carrying out the first bending on the bending line a, as shown in fig. 7a. The support beam 114 of the frame 110 is displaced in a direction lateral to the lower beam 103 until the product 120 lies with the bending line a in the correct position with respect to the die part 108 and the stamp part 109. Subsequently the cylinder piston assemblies 105 are actuated for making the desired bending, wherein the frame 110 follows the movement of the product 120 held by the clamping means 112.
[0049] After carrying out the bending according to fig. 7a, the die part 108 of the lower carrier 106 and the stamp part 109 of the upper carrier 107 are changed so that the situation of fig. 7b is obtained. The support beam 114 is moved again until the bending line b is in the correct position, whereafter by actuating the cylinder piston assemblies 105 the bending of fig. 7b can be made.
[0050] For carrying out the bending operations of figs. 7c-7f without any problems, the work piece has to be rotated around a horizontal longitudinal axis, for which purpose the pivot axis of the frame 110 is moved upwardly and arms 131 are brought in the position 136, in which the clamping means 135 may grip the work piece 120. The clamping means 112 are opened and the arms 131 are brought in the position indicated by 137, in which the work piece 120 is rotated by driving the clamping means 135, whereafter the arms 131 place the work piece again on the supports 115 of the frame 110 and the clamping means 112 again clamp the work piece 120.
[0051] For carrying out the bending operation of fig. 7c the die part 108 and the stamp part 109 of both carriers 106, 107 should be changed again, while the support beam 114 should be displaced also in order to bring the work piece 120 with the bending line c in the correct position. For carrying out the bending operation according to fig. 7d only the support beam 114 has to be displaced in order to bring the bending line d in the correct position.
[0052] For carrying out the bending operations of fig. 7e and 7f, the work piece 120 has to be rotated around an axis perpendicular to the surface of the work piece. To this end, the lifting arm 119 is brought in the position indicated by a dashed line. By actuating the cylinder piston assembly 122 the work piece 120 is taken up from the frame 110 and the cylinder piston assembly 122 and the guiding means 133, rotatably borne in the housing 124, are rotated along 1800. Thereafter the work piece 120 is placed on the supports 115 of the frame 110 again and the clamping means 112 again clamp the work piece 120. Subsequently, only the support beam 114 has to be displaced in order to sequentially bring the bending lines e and f in the correct position.
[0053] As appears from fig. 5 and 7 both stamp parts 109 each are provided with an end 139 obliquely extending with respect to the vertical. The end 139 of the stamp part 109 of the upper carrier 107 is oppositely directed to the end 139 to the stamp part 109 of the lower carrier 106. By mounting the stamp parts 109 in this manner on the lower carrier 106 and the upper carrier 107, respectively, and by the possibility to rotate a work piece around two axes crossing each other perpendicular by means of the lifting arm 119 and the arms 131, during manufacturing the most different profiles it is always possible to carry out certain bending operations for obtaining the desired profile each time with a stamp part 109 and the die part 108 without a portion of the work piece colliding with the stamp part or die part during carrying out the bending operation
[0054] As appears from fig. 5, the finished product 138 is taken from the frame 110 by the arms 131 and the arms are rotated to a discharge position shown in full lines, in which the finished product is put upon a pallet for example (not shown). During the discharge of the finished product 138, the lifting arm 119 may take up a next work piece to be bent from the storage location 121, so that it is possible to obtain a high production rate with the apparatus described.
1. Method for bending sheet-like work pieces in an apparatus comprising a die having
a longitudinally extending groove, a stamp, a stop for determining the position of
a work piece with respect to the die, clamping means for clamping a working piece
and a frame for supporting the stop and the clamping means and being pivot able around
a pivot axis substantially coinciding with the groove of the die, characterized in
that the frame is pivoted into a position extending obliquely downwardly from the
pivoting axis and in that a work piece is picked up from a storage location by a lifting
arm and is laid on the obliquely pivoted frame so that the work piece automatically
shifts against the stop, whereafter the work piece is clamped in the position as determined
by the stop and the frame is pivoted into a substantially horizontal position.
2. Method according to claim 1, characterized in that after bending the work piece
the frame is pivoted into the position extending obliquely downwardly from the pivot
axis and the bent work piece is removed from the frame and laid down at a discharge
location by the lifting arm.
3. Apparatus for carrying out the method according to claim 1 or 2, comprising a main
frame, a die having a longitudinally extending groove, a stamp, a stop for determining
the position of a work piece with respect to the die, clamping means for clamping
a work piece and a frame for supporting the stop and the clamping means and being
pivotable around a pivot axis substantially coinciding with the groove of the die,
characterized by a li.fting arm for the work pieces pivotably connected with the main
frame.
4. Apparatus according to claim 3, characterized in that the lifting arm is supported
by a carrying plate rotatably borne around a vertical axis in a holder.
5. Apparatus according to claim 4, characterized in that the holder is suspended substantially
in the centre of the apparatus by means of two support beams each being pivotably
connected with a corresponding web plate of the main frame.
6. Apparatus according to claim 5, characterized in that both web plates of the main
frame each comprise a support rail extending laterally to the die, in which support
rail an end of the corresponding support beam is borne rotatably and slidably.
7. Apparatus according to claim 6, characterized in that said end of each support
beam is borne in the corresponding support rail with a bearing roller, said end being
fixedly connected with the support rail by a cylinder piston assembly and being connected
with a second bearing roller in the support rail through a rod extending parallel
to the support rail, wherein a second cylinder piston assembly is provided between
the second bearing roller and a lever attached to said end.
8. Apparatus according to anyone of claims 3-7, characterized in that the lifting
arm comprises a carrier movable upwards and downwards and provided with a plurality
of nozzles connectable to a source of underpressure and being cardan suspended to
pins of the carrier.
9. Apparatus according to claim 8, characterized in that the pins are borne in the
carrier slidably against the action of springs.
10. Apparatus according to claim 8 or 9, characterized in that the carrier is attached
to the free end of the piston rod of a cylinder piston assembly mounted on the carrying
plate, wherein a guiding rod is mounted on the car- rier on both sides of the piston rod, said guiding rods being slidably borne in the
carrying plate.
11. Apparatus according to anyone of claims 8-10, characterized in that each nozzle
has a ring of flexible material surrounding an open chamber and provided with an obliquely
extending sealing edge which can sealingly engage the surface of a work piece.
12. Apparatus according to claim 11, characterized in that each nozzle has a closing
valve for closing a passage between the chamber and the connection to the underpressure
source, said closing valve carrying an actuating .pin downwardly projecting with respect
to the ring, by means of which the closing valve is movable into an open position
against t the act ion of a spring.
13. Apparatus according to anyone of the claims 3-12, wherein the frame is provided
with two clamping jaws each being carried by an arm, said arms being slidable longitudinally
and laterally with respect of the die, characterized in that the frame comprises a
plurality of supporting arms extending laterally to the die for supporting a work
piece, wherein a supporting arm is connected with each clamping jaw arm, while the
remaining supporting arms are fixedly mounted to the frame between the clamping jaw
arms.
14. Apparatus according to claim 13, characterized in that the fixed supporting arms
are provided with holding means for temporarily holding a work piece.
15. Apparatus according to claim 13 or 15, characterized in that the clamping jaw
arms are provided with holding means for temporarily holding a work piece.
16. Apparatus according to claim 13, 14 or 15, characterized in that the fixed supporting
arms each carry at least one stop projection.
17. Apparatus according to claim 16, characterized in that the stop projection of
each fixed supporting arm is movable laterally to the die.
18. Apparatus according to claim 16, characterized in that the fixed supporting arms
each carry two or more stop projections at an intermediate distance of each other,
wherein seen from the die, the stop projections lying between the last stop projection
and the die are retractable.
19. Apparatus according to anyone of the claims 3-18, characterized by means for rotating
a work piece around an axis lying substantially in the plane of the work piece.
20. Apparatus according to claim 19, characterized in that said rotating means comprise
two arms, one end of said arms being rotatably connected with the main frame and the
other end of said arms carrying a rotatably drivable clamping means for a working
piece.
21. Apparatus according to claim 20, characterized in that each arm with its end rotatably
connected with the main frame is mounted on a support being movable longitudinal of
the die.
22. Apparatus according to claim 20 or 21, characterized in that the arms are rotatable
to a discharge position in which the finished work piece can be discharged.
23. Apparatus according to anyone of claims 19-22, wherein the die and the stamp are
mounted on a lower carrier and an upper carrier, respectively, each being provided
with a die part and a stamp part, wherein said die and stamp parts can be brought
alternatingly in a working position direct towards the other stamp and die part respectively,
wherein each stamp part has an end extending obliquely with respect to the vertical,
characterized in that the end of the stamp part of the upper carrier extends in an
opposite direction with respect to the end of the stamp part of the lower carrier.