Die for a joining tool

Abstract

A die for a joining tool, in particular for clinching, comprising an anvil (12) and a shoulder (11, 51) coaxially surrounding the anvil (12), which is formed on a base body (10) of the anvil (12) or by an end (51) of a bushing (50), and a sleeve (20) surrounding the base body (10) or the bushing (50), which sleeve has radial slots (22) extending through its wall (21) over its circumference, in each of which a sliding piece (30) is movably guided in the radial direction (R), which is supported in the axial direction (A) at least on the shoulder (11, 51), characterized in that the wall (21) of the sleeve (20) has, at the end (20.1) surrounding the shoulder (11, 51), radially inwardly widened regions (23) in the region between the slots (22), which each extend between two adjacent sliding pieces (30) and at least partially project beyond the shoulder (11) in the radial direction (R).

Description

The invention relates to a die for a joining tool, in particular for clinching, having an anvil and a shoulder which coaxially surrounds the anvil and is formed on a base body of the anvil or by an end of a bushing, and a sleeve which surrounds the base body or the bushing and has radial slots which pass through its wall over its circumference and in each of which a sliding piece is guided movably in the radial direction and is supported at least on the shoulder in the axial direction.Such a die is known, for example, from EP 1 468 758 B1. The slots in the jacket of the sleeve create guideways for the slide members, by means of which the latter, in addition to the supporting surface on the shoulder of the base body, receive additional guidance. Such a die is of compact construction in terms of its height and diameter. The die cooperates with a tool punch and serves to connect together with the tool punch two joining parts, for example metal sheets, to one another by forming the material. Particularly during the clinching (clinching), high forces act on the die. The counter tool used for joining consists of a holding-down device and a punch. While the punch acts on the base body or anvil, the holding-down device is supported on the sleeve. In order that sufficiently high forces can be transmitted, the sleeve must be made of a hard and tough material which not only entails the disadvantage of correspondingly high costs, but is also relatively difficult to machine, which in turn requires high-quality tools for introducing the slots into the wall of the sleeve, so that the production of the sleeve is correspondingly costly and time-consuming.Similar matrices are known from DE 10 2004 033 228 A1 or DE 101 16 736 A1. Here, however, neither the anvil is provided with a shoulder, nor is a sleeve arranged in the base body. The base body is formed in one piece and the sliding pieces slide exclusively in the slots on bearing surfaces provided in the base body or in grooves provided in the anvil.Starting from this problem, the matrix described at the beginning is to be improved in such a way that the forces which can be transmitted by the sleeve can be increased and, as a result, either cost-effective material can be used or higher hold-down forces can be absorbed.For solving the problem, a die of the generic type is characterized in that the wall of the sleeve has, at the end surrounding the shoulder, areas which are widened radially inward in the region between the slots and each extend between two adjacent sliding pieces and project at least partially beyond the shoulder in the radial direction.As a result of this configuration, the holding-down device bears on a large surface during joining, as a result of which the sleeve can absorb higher forces and its load is reduced by the force of the holding-down device.Preferably, the sliders are L-shaped in cross section with a foot and a head, and the slots have upper and lower walls in the axial direction. This embodiment ensures the guidance of the sliding pieces in the sleeve.If the feet of the sliding pieces have a groove in the radial direction and the wall of the sleeve is provided with a circumferential groove at the level of the slots, a spring element engaging around all the sliding pieces can be inserted into the grooves, causing the restoring forces on the sliding pieces. The spring element can be a steel spring ring or a polymer spring.Preferably, the widened portions of the sleeve start at the level of the lower walls of the slots. This optimizes the areas that can serve for the transmission of force.In order to further improve the guidance of the sliding pieces, at least one of the walls of the slots can have a guide element and the associated sliding piece can have a counter-guide congruent therewith. This guiding / counter-guiding can be realized by projections and grooves.If the wall of the sleeve protrudes beyond the sliding pieces in the axial direction, radially continuous axial milled-out portions are provided above the slots. This configuration ensures that the force of the hold-down device is introduced into the widened regions of the wall even if the die or the sleeve is not arranged absolutely parallel to the joining parts but is slightly angled with respect thereto, so that no full-surface contact is produced on the underside of the workpiece.By increasing the force that can be absorbed by the sleeve, different materials can be selected for the anvil and the sleeve, wherein the anvil consists of a harder material than the sleeve. The anvil may be fixed or driven in the axial direction.Exemplary embodiments of the invention are described in more detail below with the aid of a drawing. The following are shown: FIG. 1 shows the arrangement of a joining device; FIG. 2 shows a first exemplary embodiment of a die in a perspective illustration; FIG. 3 is a view of the die of FIG. 2; FIG. 4 is a sectional view taken along the line IV--IV of FIG. 3; FIG. 5 is a view according to the arrow V of FIG. 3; FIG. 6 is a sectional view taken along the line VI--VI of FIG. 5; FIG. 7 is a view of a second embodiment of a die; FIG. 8 is a sectional view taken along the line VIII--VIII of FIG. 7.The joining tool consists essentially of the die 1 and the tool carrier 2 arranged above it and serves to connect the two metal sheets 3, 4 to one another by forming. In the tool carrier 2 (not shown here) a punch is arranged, which is coaxially surrounded by the holding-down device 5. The holding-down device 5 is supported on the upper metal sheet 3 during joining, while the punch causes the deformation of the two metal sheets 3, 4 and connects the metal sheets 3, 4 to one another in the form of a point.The die 1 consists of the base body 10, on which an upper circumferential shoulder 11 is formed, which is adjoined coaxially by an anvil 12, and of the sleeve 20 with the sliding pieces 30 arranged thereon. The base body 10 can be driven displaceably or fixedly mounted in the sleeve 20 in the axial direction A. When the anvil 12 is arranged displaceably in the axial direction A, it is surrounded by an additional bushing 50 (FIG. 8 ). The following applies to both embodiments. The sliders 30 are L-shaped in cross section with a foot 31 and a head 32 Slots 22 are provided in the wall 21 of the sleeve 20 corresponding to the number of sliders 30 in the radial direction R, in which slots the feet 31 of the sliders 30 are slidably received. At the level of the slots 22, the wall 21 of the sleeve 20 is provided with an outer peripheral groove 23 into which the slots 22 open. The feet 31 of the sliders 30 have a groove 33 into which a spring element 40, for example a steel ring spring or a polymer element, is inserted, which forces the sliders 30 radially inward, so that in the unloaded state they lean against the anvil 12 and rest on the shoulder 11.In the embodiment with fixed anvil 12, the task of the shoulder 11 takes over the bushing 50 or its upper end 51, on which the sliding pieces 30 slide.In the region of its upper end 20.1, the wall 21 of the sleeve 20 is widened radially inward between the slots 22, resulting in widened regions 23, which each extend between two adjacent sliding pieces 30 and project in the radial direction R beyond the shoulder 11 of the base body 10 or the shoulder 51 formed by the upper end of the bushing 50. The holding-down device 5, which acts on the metal sheets 3, 4, is supported in these widened regions 23 of the sleeve 20 of the die 1. When the punch deforms the sheets 3, 4 further in the axial direction, it is supported on the anvil 12 and the material displaced from the sheets 3, 4 forces the base body 10 downward in the axial direction A and the sliding pieces 30 outward in the radial direction R against the force of the spring element 40.Grooves 22.3, 22.4 are provided in the upper wall 22.1 and the lower wall 22.2 of the slots 22, in which grooves projections 33.1, 33.2 provided on the feet 31 of the slide pieces 30 are slidingly guided.Above the slots 22, the sleeve 20 is provided with axial milled-out portions 24 which are continuous, whereby the widened regions 33 project upwards. This ensures that the die 1 or the sleeve 20 always rests with the widened regions 23 against the underside of the sheet 4, even if the die 1 is not aligned exactly plane-parallel to the sheet 4. Overloading of the wall 21 in the region of the slots 22 is thereby reliably avoided because no force can act on it by the holding-down device 5.List of reference characters1 Die 2 Stamping tool 3 Sheet 4 Sheet 5 Holding-down device 10 Base body 11 Shoulder 12 Anvil 20 Sleeve 20.1 End 21 Wall 22 Slot 22.1 Upper wall 22.2 Lower wall 22.3 Groove 22.4 Groove 23 Widened region 24 Circumferential groove 30 Sliding piece 31 Foot 32 Head 33 Groove 33.1 Projection 33.2 Projection 40 Spring element / ring spring / polymer element 50 Bushing 51 Upper end A Axial direction R Radial direction Re / rog-ydr

Claims

Die for a joining tool, in particular for clinching, having an anvil (12) and a shoulder (11, 51) which coaxially surrounds the anvil (12) and is formed on a base body (10) of the anvil (12) or by an end (51) of a bushing (50), and a sleeve (20) which surrounds the base body (10) or the bushing (50) and has radial slots (22) which pass through its wall (21) over its circumference and in each of which a sliding piece (30) is guided movably in the radial direction (R) and is supported at least on the shoulder (11, 51) in the axial direction (A), characterized in that the wall (21) of the sleeve (20) has regions (23) widened radially inwards at the end (20.1) surrounding the shoulder (11, 51) in the region between the slots (22), which extend in each case between two adjacent sliding pieces (30) and project at least partially beyond the shoulder (11) in the radial direction (R).Die according to Claim 1, characterized in that the slide pieces (30) are of L-shaped cross section with a foot (31) and a head (33), and the slots (32) have an upper (22.1) and a lower (22.2) wall in the axial direction (A).Die according to Claim 2, characterized in that the feet (31) of the sliding pieces (30) have a groove (32) in the radial direction (R) and the wall (21) of the sleeve (20) has a circumferential groove (23) at the level of the slots (22), and a spring element (40) which surrounds all the sliding pieces (30) is inserted into the grooves (32).Die according to Claim 2 or 3, characterized in that the widened regions (23) begin at the level of the lower walls (22.2) of the slots (22).Die according to one of the preceding claims, characterized in that the sliding pieces (30) are guided in the slots (22).Die according to Claim 5, characterized in that at least one of the walls (22.1, 22.2) of the slots (22) has a guide element (22.3, 22.4) and the associated sliding piece (30) has a counter-guide (31.1, 33.1) congruent therewith.Die according to one of the preceding claims, characterized in that the wall (21) of the sleeve (20) terminates with the sliding pieces (30) in the axial direction (A) or projects beyond the latter and has continuous axial milled-out portions (24) in the region above the slots (22).Die according to one of Claims 3 to 7, characterized in that the spring element (40) is a steel ring spring or a polymer spring.Die according to one of the preceding claims, characterized in that the anvil (12) consists of a harder material than the sleeve (20).Die according to one of the preceding claims, characterized in that at least three, in particular exactly four, sliding pieces (30) are provided.Die according to one of the preceding claims, characterized in that the anvil (12) is driven displaceably in the vertical direction (V).

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