BENDING APPARATUS

Abstract: The invention relates to apparatus for bending a flange (5) against piece (2). A bending tool (6) is mounted on a tool holder (14) carried by a parallelogram mechanism (7-12) for movement in relation to a stand (1) carrying the workpiece. A drive arrangement (17) is connected to the tool holder (14) by a toggle linkage (25-27). The tool holder (14) includes a main part (13) connected to the parallelogram mechanism (7-12), and a part (15) movable in relation to the main part and carrying the tool (6) and urging resilient element (32) towards a starting position. The toggle linkage (25-27) is acting on the movable part (15) of the tool holder (14) away from the starting position, when the main part (13) is located near an end position and the tool (6) engages the flange (5).

Description: 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 the workpiece, the apparatus in¬ cluding a bending tool which is mounted on a tool holder carried by a parallelogram mechanism for movement in relation to a stand on which the workpiece is placed, and further including a drive arrangement which is drivingly connected to the tool holder. Apparatus of this kind are previously known in various forms. Such apparatus are used, for instance, to bend a margin flange on a sheet metal workpiece around the margin of another sheet metal workpiece, to effect a clinching or hemming joint which joins the two workpieces together. This type of operation is common, for instance, within the vehicle manufacturing industry, in the production of different vehicle body parts. One drawback with such known apparatus, however, is that a relatively large free area is required around the margin flange to be bent, in order for the apparatus to function satisfactory. This makes it difficult, or even impossible, to use such apparatus for certain kinds of working operations where said space is extremely limited. The object of the invention is to provide apparatus of the aforesaid kind which do not suffer these drawbacks and which can also be used in confined spaces with satis¬ factory results. This object is achieved in accordance with the invention in that the drive arrangement is connected to the tool holder by means of a toggle linkage; in that the tool holder includes a main part which is connected to the parallelogram mechanism, and a part which is movable in relation to the main tool holder part and which carries the tool and which is urged towards a start- ing position by means of a resilient element; and in that the toggle linkage is constructed to act upon the movable part of the tool holder in a direction away from the starting position, when the main part of the tool holder is located in the vicinity of an end position and the tool is in engagement with the margin flange on the workpiece. Advantageous embodiments of the invention are set forth in the depending claims. The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 is a somewhat schematic side view of one em¬ bodiment of the inventive bending apparatus; 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 or pre-form positions, during a working sequence; and Figure 4 is a schematic view of the apparatus of Figure 1, and shows the apparatus components in their respective final bending or clinching positions during a working sequence. The apparatus illustrated in Figure 1 comprises a stand 1 which is mounted on a support surface (not shown) , which also supports a workpiece 2. The illustrated workpiece 2 comprises a sheet metal rail 3, in which a sheet metal profile section 4 is placed. The sheet metal rail 3 has two margin flanges 5, of which one flange is shown in Figure 1 to be bent over a lower flange on the sheet pro- file section 4. Bending of the flange has been effected with the aid of a tool 6. The stand 1 carries two journal pins 7 and 8 which are mutually parallel. Respective one ends of pivot arms 9 and 10 are journalled on a respective journal pin 7 and 8. and the other ends of the arms 9 and 10 are journalled on a respective journal pin 11 and 12. The journal pins 11 and 12 are carried by a main part 13 of a tool holder 14. which in addition to said main part 13 also includes a movable part 15, which is pivotally mounted on a journal pin 16 carried by the main part 13. The spacing between the journal pins 7 and 8 is equal to the spacing between the journal pins 11 and 12, and the pivot arms 9 and 10 are of mutually equal lengths, and consequently the members 7-12 form a parallelogram mechanism. Consequently, the tool holder 14 can be moved relative to the stand 1, with the aid of the parallelogram mechanism 7-12. The movable part 15 of the tool holder 14 carries the tool 6, therewith enabling the tool 6 to be moved towards and away from the workpiece 2, when the tool holder 14 is moved with the aid of the parallelogram mechanism 7-12. The stand 1 also carries a drive arrangement for effecting movement of the tool holder 14. This drive arrangement includes a pressure-medium operated piston-cylinder device 17, which is pivotally connected to the stand 1 by means of journal pins 18. The outer end of the piston rod 19 of the piston-cylinder device 17 is provided with an end piece 20, which is pivotally connected to one arm 22 of a double-arm lever 23, by means of a journal pin 21. The lever 23 is pivotally journalled on the stand 1 by means of a journal pin 24. The free end of the other arm 25 of the double-arm lever 23 is pivotally connected, by means of a journal pin 26, to the one end of a link 27, the other end of which is journalled on the journal pin 12 of the parallelogram mechanism 7-12. between the stand 1 and the tool holder 14. The other arm 25 of the lever 23 and the link 27 therewith form a toggle linkage, which controls movement of the tool holder 14 in relation to the stand 1. In the position of the apparatus components illustrated in Figure 1, the toggle linkage 25-27 is essentially fully extended. As will be seen from Figure 1. a projection 28 on said other arm 25 of the lever 23 will therewith abut an abutment 29 on the movable part 15 of the tool holder 14. In this position of the apparatus components, contact between the projection 28 and the abutment 29 has caused the movable part 15 to pivot about the journal pin 16, such as to mutually separate two shoulders 30, 31 on the main part 13 and the movable part 15 respectively of said tool holder 14. This movement is effected against the action of a spring 32, which urges a pin 33 into abutment with the movable part 15 of the tool holder 14. such as to pivot the movable part 15 in a direction towards mutual contact of the shoulders 30 and 31. Figures 2-4 illustrate schematically the different posi¬ tions adopted by the apparatus components described with reference to Figure 1 when carrying out a working sequen¬ ce. Figure 2 illustrates the apparatus components in their respective starting positions., in which the tool 6 is spaced from the workpiece 2. In this position, the piston rod 19 of the hydraulic piston-cylinder device 17 is fully extended, and consequently the lever 23 is rotated in an anti-clockwise direction around the journal pin 24 to the maximum possible extent. The toggle linkage 25-27 has therewith drawn the tool holder 14, by means of the paral¬ lelogram mechanism 7-12, as far to the right as possible, when seen in the drawing. The projection 28 is spaced from the abutment 29, and the pin 33, under the influence of the spring 32, has rotated the movable part 15 of the tool holder 14 as far as possible around the journal pin 16 in a clockwise direction, so that the shoulders 30 and 31 are in abutment with one another. Figure 3 illustrates the apparatus components in a posi¬ tion in which the tool 6 has bent the margin flange 5 of the workpiece 2 through an angle of about 45°. In order for the apparatus to have reached this operating position, the piston rod 19 has been withdrawn to a given extent into the cylinder of the piston-cylinder device 17, such as to rotate the lever 23 clockwise about the journal pin 24. In conjunction herewith, the journal pin 26 of the toggle linkage 25-27 has been moved upwards, as seen in the drawing, and, at the same time, the parallelogram mechanism 7-12 has moved the tool holder 14 to the left to an extent such that the tool 6 has come into engagement with the margin flange 5. Figure 4 illustrates the apparatus components in a posi¬ tion in which the projection 28 has just come into contact with the abutment 29. The piston rod 19 has, in this case, been withdrawn further into the cylinder of the piston- -cylinder device 17, and has therewith caused the lever 23 to rotate further about the journal pin 24. The parallel¬ ogram mechanism 7-12 has therewith moved the tool holder 14 further to the left, as seen in the drawing, so that the tool 6 has substantially completely bent the margin flange 5. The shoulders 30, 31, however, are still in mutual abutment. In order to effect final bending of the margin flange 5 to the position illustrated in Figure 1, the piston rod 19 is withdrawn slightly from the position illustrated in Figure 4. This will cause the lever 23 to pivot slightly about the journal pin 24, so that the projection 28, with the aid of the abutment 29, will pivot the movable part 15 of the tool holder 14 about the journal pin 16, so as to press the tool 6 harder against the margin flange 5, to complete bending of the flange. Subsequent to carrying out the aforedescribed working sequence, the apparatus components are returned to the starting position illustrated in Figure 2, by extending the piston rod 19 from the cylinder of the piston-cylinder device 17. The spring 32 and the pin 33 therewith swing the movable part 15 of the tool holder 14 to an extent such that the shoulders 30 and 31 will abut one another. The apparatus is then ready to carry out a new working sequence. The invention is not restricted to the aforedescribed exemplifying embodiment thereof, since modifications can be made thereto within the scope of the following claims.

Claims: CLAIMS 1. Apparatus for bending a margin flange (5). which pro¬ jects at an angle to a surface on a workpiece (2), against said workpiece. the apparatus including a bending tool (6) which is mounted on a tool holder (14) carried by a paral- lelogram mechanism (7-12) for movement in relation to a stand (1) on which the workpiece (2) is placed, and fur¬ ther including a drive arrangement (17) which is drivingly connected to the tool holder (14). characterized in that the drive arrangement (17) is connected to the tool holder (14) by means of a toggle linkage (25-27); in that the tool holder (14) includes a main part (13) connected to the parallelogram mechanism (7-12) and a part (15) which is movable in relation to the main part (13) and which carries the tool (6) and by means of which a resilient element (32) is urged towards a starting position; and in that the toggle linkage (25-27) is intended to cause the movable part (15) of the tool holder (14) to move away from the starting position when the main part (13) of said tool holder (14) is located in the vicinity of an end position and the tool (6) is in engagement with the margin flange (5) on the workpiece (2). 2. Apparatus according to claim 1, characterized in that the movable part (15) of the tool holder (14) is pivotal about a journal pin (16) which is substantially parallel with the journal pins (7, 8, 11, 12) of the parallelogram mechanism; and in that the toggle linkage (25-27) includes a projection (28) for co-action with an abutment (29) on the movable part (15) of the tool holder (14) when the toggle linkage (25-27) is in the proximity of its fully extended state. 3. Apparatus according to claim 1 or 2, characterized in that the drive arrangement comprises a pressure-medium operated piston-cylinder device (17), the cylinder of which is pivotally connected to the stand (1) and the piston-rod (19) of which is pivotally connected to the toggle linkage (25-27).

Inventors: DORSETT MICHAEL W, DORSETT, MICHAEL, W.
Applicants: VOLVO AB, AB VOLVO
Application year: 1989
Main classification: B21D5
IPC codes: B21D5, B21D19, B21D39