FR2647374A1 - DEVICE FOR MANUFACTURING LIDS OR SIMILAR OBJECTS IN METAL SHEET - Google Patents

Abstract

The lower tool of a stamping press consists of two concentric drawing cores 20, 24. The outer drawing core 24 is moved downward by a drive device when the upper tool 10 comes into contact with it. In this way, the upper tool 10 can bend the angled cover edge inwards by means of a bell segment 16. During the return stroke, the outer drawing core 24 engages, via a forming recess. , the cover edge partially rolled inward and completes the inward winding process, a forming surface of the upper tool 10 which remains stationary during the first part of the return stroke constituting the counter surface .

Description

The invention relates to a device for manufacturing covers

  or similar sheet metal objects that have an inwardly rolled edge portion. More specifically, the invention relates to a device of this type, and which comprises an upper tool actuatable by a press punch, a lower tool which, in cooperation with the upper tool, gives the lids, by press work, the predetermined shape, a tool segment which concentrically surrounds and is movable relative to the upper tool, a pleat holding device which surrounds the lower tool, is movable relative to it and is compressed by a drive device towards the upper tool, a cutting tool surrounding the fold holding device, comprising an annular cutting edge cooperating with the tool segment when the upper tool approaches the tool lower, the lower tool comprising an inner drawing core and an outer drawing core annularly surrounding the latter, mounted movably with respect to the inner drawing core and driven by a driving device in such a way that the outer drawing core can be moved relative to the inner core, because the upper and lower tools cooperate, the tool segment also having an upper part, of a smaller inner diameter and a lower inner diameter larger, the latter being slightly larger than the outer diameter of the outer drawing core such that, when the tool segment continues to descend, the edge of lid can be folded down and inward in a free space formed by the descent of the core

external stretch.

  Lids for boxes and other containers are made from sheet metal by simultaneous punching and forming in the press. Following this forming, the lids have a curved edge which, after application to the container, is shaped, folded over the edge of the container, and shaped to it, so as to constitute a tight connection. For this purpose, the cover edge is deformed by rolling so that it engages the container edge from below. It is desired to give the edge of the lid a curved shape, in cross-section view, so that it has a suitable starting shape for rolling on the edge of the container. DE-A-35 34 362 discloses a device in which the upper and lower tools give the cover, by passing through the press, the predetermined shape. The upper tool is surrounded concentrically by a segment of tool movable relative to it, which aims to cooperate with a cutting tool to cut the blank cover. The lower tool consists of an inner drawing core and an outer drawing core annularly surrounding the previous one, housed in a movable manner with respect to the latter, and driven by a drive device. Around the outer drawing core is housed what is known as a pleat holding device. When moving the upper and lower tools towards each other, the cover blank is first cut between the tool segment and the cutting tool, then the free edge of the cover blank is curled at right angles around

  of the outer drawing core using the tool segment.

  During this movement of the tools, the tool segment moves the pleat holding device relative to the outer drawing core. This is made up of two annular segments, one of which is an outer segment which is moved downwards by the pleat holding device, in order to provide a free space in which the folded portion of the cover edge can be pushed inwards. This forming is carried out using a conical part of the tool segment, which comes into contact with the cover edge when the movement of the tool continues.

lowering the tool segment.

  In the known device, a special forming of the cover edge can be carried out in a working cycle. This forming is in fact carried out, during the only displacement, that is to say during a single stage of the cycle. However, it is quite difficult to reproducibly produce a cover edge rolled towards

  the interior satisfactorily.

  The object of the invention is to provide a device for manufacturing covers or the like of sheet metal, by means of which satisfactory winding from the edge of the cover inwards can be carried out.

reproducible way.

  This object is achieved according to the invention by the fact that the bell-shaped tool segment has, at its end turned towards the lower tool, a forming recess, which the outer drawing core has at its upper end. , on the side facing the inner drawing core, a second forming recess, and that the drive device, after the press punch has passed the bottom dead center, pushes up the outer drawing core , before the upper and lower tools are separated from each other, to continue deformation of the cover edge in

the second forming recess.

  In the device according to the invention, the tool segment, in the form of a bell, has a forming recess which, when the spacing is displaced, first curves the cover edge segment which has already bent at right angles between the tool segment and the outer drawing core. The outer core has, on the side facing the inner drawing core, a second forming recess, and the device for driving the drawing core presses the latter upwards, before the upper and lower tools are separated from each other, so that the cover edge which has been previously rolled inwards comes into contact with the second forming recess and continues to be rolled inwards sufficiently far into the space of forming formed between the forming recess, the inner drawing core and the upper tool. It is only after this process that the

  forming tools return to their starting position.

  The device according to the invention allows in this way the punching and the complete forming of a cover, including its curved edge, in a working cycle, the forming of the cover edge being carried out in three successive stages, without requiring costs. important for forming tools. The device according to the invention allows in particular, even for a reduced thickness and greater hardness of the sheet, a uniformly wound cover. In the device according to the invention, even with relatively small dimensions

  from the edge of the cover rolled inwards, i.e.

  say for a substantially smaller length, it is possible to obtain a uniform coiled shape. For reasons of economy of material, we endeavor not to employ

  as little material as possible for the edge.

  According to one embodiment of the invention, the external drawing tool is made in one piece. This constitutes a simplification compared to the known device described in the introduction, in which must be

  provided an exterior stretching core in two parts.

  Another embodiment of the invention provides that the press punch acts by an elastic device on the upper tool and that the bell segment is rigidly connected to the press punch and that the outer drawing core is pressed by means of an elastic device in the direction of the upper tool against a stop of the drawing core. Whereas, in the known device, the individual tool segments are actuated hydraulically and must therefore be controlled correspondingly, it is sufficient in the device according to the invention to have a normal punch actuation of the upper tool to carry out the forming process described. By means of suitable elastic devices between the punch and the upper tool, between the outer drawing core and a fixed counter-support, and the fold-holding device and the fixed counter-support, an automatic control of the relative movements of the parts is obtained. forming. A device of such a structure can therefore be produced very economically and there are other

part little exposed to wear.

  When the invention conforms to the above feature, a dimension of the elastic device of the outer drawing core can advantageously be such that the outer drawing core maintains its position when the lower part of the bell segment curls the edge of the cover around the upper side of the drawing core. According to another embodiment of the invention, the largest diameter of the second forming recess of the outer drawing core is approximately equal to the smallest

  inner diameter of the bell segment.

  We will now explain in more detail an embodiment of the invention using the drawings in which: FIG. 1 schematically represents a section of a device according to the invention, FIGS. 2 to 5 represent a part of the device according to FIG. 1 in various operating states. An upper tool 10 is supported by elastic devices 11 or 12 on a plate 13, which is rigidly connected to a press punch 14, which is moved alternately in the direction of the double arrow 15 by press drive not shown. The upper tool 10 is surrounded by a bell-shaped tool segment 16, which is rigidly connected to the plate 13, as indicated by threaded rods 17. In the position shown in FIG. 1,

264737L

  a portion 18, of larger diameter, of the upper tool 10 rests on an annular step 19 of the segment

tool 16.

  An internal drawing core 20 is rigidly connected to a fixed plate 21, as indicated by threaded rods 22 and an intermediate ring 23. The internal drawing core 20 is surrounded by an annular external drawing core 24. The outer drawing core 24 rests on a pusher 25, which is itself resiliently mounted. The outer drawing core 24 is surrounded by an annular pleat holding device 26, which rests on a rod 27, with which is associated a spring 28 and which pushes up the pleating holding device 26. A cutting tool 29 is rigidly connected to the plate 21, as indicated by the threaded rod 30. The cutting tool 29 limits upward the

  displacement of the fold holder 26.

  The operating mode of the device shown in Figure 1 is shown in Figures 2 to 5. In Figures 2 to 5, the tool device is shown on a larger scale and in more detail. In particular, it can be seen that the upper tool 10 consists of an inner tool segment 10a and an outer tool segment 10b which surrounds it annularly. Both are connected to the press punch 14 by elastic devices. The lower forming surface of segment 10b is shifted upward relative to the lower forming surface of segment O10a. However, the forming surfaces can also be located in a plane. It can also be seen that the bell-shaped segment 16 comprises a portion 16a of greater thickness and a portion 16b of thinner thickness, thanks to which a forming recess 16c, of annular shape, which is turned towards the surface, is produced. upper tool 10. The inside diameter of the part 16a corresponds to the outside diameter of the tool segment 10b. Is the inner diameter of part 16b slightly larger than the diameter?

  inside of the fold holder 26.

  It can also be seen that the external drawing core 24 has at its lower end an enlargement 24a, which cooperates on the one hand with a step 20a of the internal drawing core 20, whereby the displacement of the external drawing core 24 upwards is limited with respect to the inner drawing core 20. On the other hand, the enlargement 24a cooperates with the fold holding device 26 when the latter is moved downwards in

  opposition to the elastic device 28.

  The outer drawing core 24 has, at its upper end, on the side facing the inner drawing core 20, a forming recess 24b, the largest internal diameter of which roughly corresponds to the

  outside diameter of the tool segment 10b.

  The starting position of the forming operation is visible in Figure 2. A sheet metal plate 40 is slid between the tools, and the press punch 14 is moved back from part of its working stroke. The individual tool segments are then in the position which is shown in Figure 1. In the position shown in Figure 3, the segments O10a, 10b, of the upper tool, in cooperation with the inner drawing cores 20 and outside 24, have finished stamping the cover 41. The bell-shaped segment 16, rigidly connected to the press punch, cooperated with the punching tool 29 and cut by punching, at the start of the forming operation, the cover blank, the fold holding device 26 being shifted backwards in opposition to the associated elastic device 28. The elastic device associated with the outer drawing core 24 is arranged so that, during forming press described cover 41, this outer drawing core 24 remains in the position

shown in Figure 3.

  We will not describe in more detail the forming

the lid itself.

  It is recognized in FIG. 3 that, during the descent of the bell segment 16, the latter brings the device for holding the fold 26 in abutment on the enlargement 24a of the outer drawing core. As the upper tools 10a, 10b are coupled to the press punch by elastic devices, the latter can continue its downward movement. The bell-shaped segment 16 therefore also continues its downward movement by driving down the outer drawing core 24. In this way, the underside of the thick part 16a of the bell segment 16 comes into contact with the edge of the cover 41 curved at a right angle downwards. This bending at right angles to the edge is the result of the cooperation of the thin part 16b of the bell segment 16 and the outer side of the outer drawing core 24, as shown in FIG. 3. The lateral contact on one side of the part 16a of the bell segment 16 with the cover edge, causes the latter to bend inwards, as clearly shown in FIG. 4. The press punch has then reached its

bottom dead center.

  During the upward movement of the press punch 14, the bell segment 16 rises first, while the tool segments 10a and 10b still remain, due to the elastic arrangements, in contact with the cover and the drawing core inside 20. Due to the upward movement of the bell segment 16, the fold holding device 26 and, consequently, the outside drawing core 24 can move upwards. In this way, the forming recess 24b of the outer drawing core 24 comes to cooperate with the partially wound cover edge and ends the winding, as shown in FIG. 5. The cover edge receives a roughly semi-contour -circular, and it is in this way remarkably prepared to be able to be connected to the

  cover in a corresponding rolling pass.

  The upward movement of the press punch 14 continues, and the tool segments again return to a starting position as shown in Figure i or Figure 2. Another forming process can begin. It will be understood that the actuation of the outer drawing core 24 can also be carried out in another way, for example by an appropriate drive, to

cam control.

Claims (5)

  1. Device for manufacturing covers or similar objects made of sheet metal which have an edge part rolled inwards, comprising - an upper tool (10) actuatable by a press punch, - a lower tool which, in cooperation with the upper tool (10), gives the covers, by press work, the predetermined shape, a tool segment which concentrically surrounds the upper tool (10) and is movable relative to the latter, - a pleat holding device (24) which surrounds the lower tool (20), is movable relative thereto and is pressed by a drive device in the direction of the upper tool (10), - a tool cutting surrounding the fold holding device, and comprising an annular cutting edge cooperating with the tool segment (16) when the upper tool (10) approaches the lower tool (20), - the tool lower comprising an inner drawing core (20) and a core u outer drawing (24) annularly surrounding the latter, mounted movably relative to the inner drawing core (20) and driven by a driving device such that the outer drawing core (24) can be moved relative to the inner core (20), because the upper (10) and lower (20) tools cooperate, - the tool segment (16) also having an upper part, with an inner diameter more small, and a lower portion (1615) of larger inside diameter, the latter being slightly larger than the outside diameter of the outer drawing core (24) such that when the tool segment (16) continues its descent, the cover edge can bend downwards and inwards in a free space formed by the descent of the outer drawing core (24), characterized in that the bell-shaped tool segment (16) presents & its end turned towards the tool l lower (20) a forming recess (16c), in that the outer drawing core (24) has at its upper end, on the side facing the inner drawing core (20), a second forming recess (24b), and in that the drive device, after the press punch (14) has passed the lower dead center, pushes up the outer drawing core, before the upper and lower tools (10 , 20) are not separated from each other, to continue the deformation of the cover edge in the   second forming recess (24b).   2. Device according to claim 1, characterized in that the outer drawing core (24) is produced in one piece.   3. Device according to claim 1 or 2, characterized in that the press punch (14) acts by an elastic device (11, 12) on the upper tool (10), in that the bell segment (16) is rigidly connected to the press punch, and in that the outer drawing core (24) is pressed by means of an elastic device in the direction of the upper tool   (10) against a stop (20a) of the drawing core (20).   4. Device according to claim 3, characterized by a dimension of the elastic device of the outer drawing core (24) such that the outer drawing core (24) maintains its position when the lower part (16b) of the bell segment ( 16) curl the lid edge around the top side of the core drawing (24).   5. Device according to one of claims 1 & 4,   characterized in that the larger diameter of the second forming recess (24b) of the outer drawing core (24) is approximately equal to the smaller inner diameter of the bell segment (16).