Bending apparatus

The present invention relates to apparatus for bending a margin flange, which projects at an angle to a surface on a workpiece, against said surface, said apparatus in¬ cluding a bending tool which is mounted on a tool holder. by means of which a linkage mechanism is connected to a stand which carries the workpiece, and further includes a drive arrangement which is connected to the tool holder in a manner to move said tool holder in relation to the stand.

Apparatus of this kind are previously known and are used, for instance, for bending a margin flange on a metal sheet workpiece around the margin of another metal sheet work- piece, such as to produce a clinching or hemming joint which joins the two workpieces together. Operations of this kind are common, for instance, within the vehicle manufacturing industry, in the production of different vehicle body parts.

The object of the invention is to provide an improved apparatus of the aforedescribed kind. This object is achieved in accordance with the invention in that the linkage mechanism which connects the tool holder to the stand includes two mutually parallel carrier links, each of which is pivotally mounted at one end thereof on a respective journal pin located on the tool holder; in that the other end of the first carrier link is pivotally mounted on a fixed journal pin on the stand, said journal pin also pivotally carrying one end of a connecting link, the other end of which is pivotally connected to the other end of the second carrier link, by means of a pivot pin; and in that the drive arrangement includes a drive member which is attached to the stand and connected to the second carrier link for movement of said link and therewith of the tool holder, and also a camming device which is driven

by the drive member and intended for activation of a cam follower which is mounted on the first carrier link and which projects upwardly from the other end of said carrier link in a direction away from the tool holder.

The invention will now be decribed in more detail with reference to the accompanying drawings, in which Figure 1 is a somewhat schematic side view of a bending apparatus constructed in accordance with one exemplifying embodiment of the invention;

Figure 2 is a schematic side view of the apparatus of Figure 1, and shows the apparatus components in their respective starting positions prior to commencing a working sequence; Figure 3 is a schematic side view of the apparatus of Figure 1, and shows the apparatus components in their respective preliminary bending positions while carrying out a working sequence; and Figure 4 is a schematic side view of the apparatus of Figure 1, and shows the apparatus components in their respective bend finishing or clinching positions.

The bending apparatus illustrated in the drawings com¬ prises a stand 1 which is intended to be secured to a supporting surface (not shown) by means of fastener bolts 2, of which only one is shown in Figure 1. The stand 1 carries a holder 3, on which a workpiece 4 is placed. In the illustrated embodiment, the workpiece 4 comprises a sheet metal rail having the margin flange 5, which, in the starting position illustrated in Figure 2, extends upwards from the major part of the workpiece 4. Figure 3 shows the margin flange in a preliminary bent or pre-form state, whereas Figures 1 and 4 show the flange subsequent to being fully bent, in which it clinches against an adjacent surface on the workpiece 4. Perpendicularly to the plane of the drawing the workpiece 4 may have considerable length, and may be straight or curved in different direc-

tions, the holder 3 naturally being configured to provide support for the workpiece 4 over the whole of its length.

Bending of the margin flange 5 from the starting position illustrated in Figure 2 to the pre-bend position ilustrat- ed in Figure 3 and further to the fully bent or clinching position illustrated in Figure 4, is effected with the aid of a bending tool 6. When seen at right angles to the plane of the drawing, the bending tool 6 has a shape which conforms with the shape of the workpiece 4 and its margin flange 5, so that the tool 6 will co-act with the margin flange 5 over the whole of its length, during a bending operation.

The bending tool 6 is carried by a tool holder 7, which in turn is carried by the stand 1. To this end, there is provided a first carrier link 8, one end of which is pivotally mounted on a journal pin 9 on the tool holder 7 and the other end of which is pivotally mounted on a jour- nal pin 10 on the stand 1. The apparatus also includes a second carrier link 11, one end of which is pivotally journalled on a journal pin 12 on the tool holder 7 and the other end of which is pivotally journalled on a jour¬ nal pin 13. Also provided is a connecting link 14, one end of which is journalled on the journal pin 10 and the other end of which is journalled on the journal pin 13.

The journal pin 13 is arranged for movement in relation to the stand 1, so as to move the tool holder 7 and the bend- ing tool 6 in a manner to carry out a bending operation, as described in more detail hereinafter. To this end, there is provided a drive arrangement which includes a pressure-medium operated piston-cylinder device 15 which is pivotally suspended in the stand 1 by pivot pins 16. The piston-cylinder device 15 includes a piston rod 17, which carries on its free end, directed upwards in the drawing, an end piece 18. The end piece 18 is pivotally

connected by a pivot pin 19 to one arm 20 of a double-arm lever, which is pivotally mounted on a journal pin 21 on the stand 1, and the other arm 22 of which is pivotally connected by means of a pivot pin 23 to one end of a drive link 24, the other end of which is pivotally journalled on the pin 13.

The lever 20, 22 also carries a substantially upwardly extending camming device 25, which is detachably mounted on the lever 20, 22. The camming device 25 presents on the surface thereof distal from the lever 20, 22 a camming surface which comprises a part-circular or curved portion 26a and a lifting portion 26b. The part-circular portion 26a is so configured that its centre of curvature coin- cides with the geometric axis of the journal pin 21 on which the lever 20, 22 is journalled. In the case of the illustrated embodiment, the lifting part 26b is substan¬ tially linear, although it will be understood that other configurations can be used to provide the effect desired, as described in more detail hereinafter.

A cam follower device in the form of a cam follower roller 27 is arranged for co-action with the camming surface 26a. 26b. The cam follower roller 27 is journalled on a journal pin 28, which is mounted on an arm 29. The arm 29 is con¬ nected with the first carrier link 8 and projects there¬ from in a direction away from the tool holder 7 on the opposite side of the journal pin 10, as seen from the tool holder 7. The arm 29 is also provided with a downwardly directed shoulder 30, which is intended to co-act with an upwardly directed abutment 31 on the other arm 22 of the lever.

The other carrier link 11 is provided with an arm 32 which projects out on the opposite side of the journal pin 12, as seen from the carrier link 11, and is connected at its outer end with a spring device 32, which is connected at

one end thereof to the stand 1 and which is so configured as to urge the end of said arm 32 in an upward direction. This means that the force exerted by the spring device 33 will act on the cam follower roller 27 in a direction towards the camming surface comprising the part-circular portion 26a and the lifting portion 26b.

A working sequence in which the margin flange 5 is bent against the workpiece 4 will now be described with refer- ence to Figures 2-4, which illustrate the various posi¬ tions of the apparatus components during said working sequence.

Figure 2 illustrates the starting position, in which the bending tool 6 is spaced from the margin flange 5 on the workpiece 4, in which position the piston rod 17 is ex¬ tended to a maximum from the piston-cylinder device 15 and the double-arm lever 20, 22 has therewith been rotated clockwise (seen on the drawing) about the journal pin 21. The camming device 25 ha been swung together with the lever 20, 22, and the cam follower roller 27 has been moved therewith, upwardly along the lifting part 26b, therewith causing the arm 29 and the first carrier link 8 to be swung anti-clockwise (seen on the drawing) about the journal pin 10. The spring device 33 therewith holds the cam follower roller 27 pressed against the lifting part 26b of the camming device. The drive link 24 holds the pin 13 in a given position.

When carrying out a working sequence, the piston rod 17 is withdrawn into the piston-cylinder device 15, primarily to the pre-bend position illustrated in Figure 3. The lever 20, 22 is therewith swung anti-clockwise around the jour¬ nal pin 21, therewith moving the cam follower roller 27 along the lifting part 26b. down to the part-circular portion 26a of the camming surface of the camming device 25. This enables the arm 29 and the first carrier link 8

to be swung anti-clockwise around the journal pin 10. The journal pin 9 will therewith move the tool holder 7 and the bending tool 6 upwards, while, at the same time, the drive link 24 will move the pin 13 to the right in the Figure, to the position illustrated in Figure 3, wherewith the tool holder 7 and the bending tool 6 are swung about the journal pin 9, so that the tool 6 will be moved to the left, to the pre-bend position illustrated in Figure 3. The tool 6 will then bear against the margin flange 5 and bend said flange.

Continued withdrawal of the piston rod 17 into the piston- -cylinder device 15 initiates essentially the movements described in the aforegoing. Thus, the bending tool 6 is moved further to the left by the tool holder 7, such as to bend the margin flange 5 to the clinching position illustrated in Figure 4. In this case, the cam follower roller 27 moves along the part-circular portion 26a, meaning that the arm 29 and the first carrier link 8 will retain their respective positions. The drive link 24, on the other hand, moves the pin 13 co the right, to the position shown in Figure 4, and the bending tool 6 and the tool holder 7 are moved to the left in conjunction with this movement of the pin. At the end of the withdrawal movement of piston rod 17 into the piston-cylinder device 15, the shoulder 30 located on the arm 29 will be in abutment with the abutment 31 located on the other arm 22 of the lever. During the final part of movement of the piston rod 17 into the cylinder, the abutment 31 will urge the shoulder 30 upwards, so that the arm 29 and the first carrier link 8 are pivoted slightly clockwise about the journal pin 10. This causes the tool holder 7 and and the bending tool 6 to be moved substantially downwards, so as to finally bend the margin flange 5 into clinching en- gagement with the workpiece 4. The bending sequence is then complete and the apparatus components can be returned to their respective Figure 2 starting positions, by ex-

tending the piston rod 17 from the piston-cylinder device 15. The apparatus is then ready for the next working sequence.

The invention is not restricted to the aforedescribed exemplifying embodiment, since modifications thereto can be made within the scope of the following claims. For example, the lifting part 26b of the camming device 25 can be given a configuration which is commensurate with de- sired movement of the tool holder 7 and the bending tool 6. The lifting part 26b may be replaced with a lifting part which extends from the part-circular portion 26a obliquely inwards towards the journal pin 21, such that the bending tool 6 and the tool holder 7 will be posi- tioned at a higher level than the workpiece 4 in the starting positions thereof. This can be desirable for different reasons, for instance when several bending apparatus are to work in mutually adjacent and mutually sequential relationship, therewith enabling work to be carried out without the apparatus obstructing one another.