EP2543451B1 - Device for joining workpieces - Google Patents

Abstract

The device has a tool (5) with a contour (5.1) and another tool (6) with another contour (6.1), where the contours are pressed against each other over a deformation area (4). A radiation source (7) is formed for providing an electro-magnetic radiation which serves a heating of the workpieces (1,2) between the tools. The radiation source is arranged lateral to the tools such that the electro-magnetic radiation is directed from the workpieces and in the deformation area.

Description

The invention relates to a device for joining workpieces according to the preamble of claim 1, as this generic from the DE 10 2004 062 896 B4 is known.

The increasing demand for lightweight yet sturdy components and constructions is increasingly being taken into account by the use of high-strength materials. In the field of steel development, a large number of developments have taken place in recent years, which make it possible to produce steels with strengths well above 1000 N / mm ² and in series products, eg. In automobiles.

With increasing strength, however, in steels and metallic materials, in general, the flowability and hence the ductility decreases, that is, a strain that ends with a break is set by the enormously increasing yield stresses a narrow limit, which is less than 5% can be.

For further processing of the metallic materials, eg. B. in the form of sheets as moldings or semi-finished products (workpieces), this means that the materials can be deformed only slightly and then at very high forces. If such workpieces are welded (fusion welding), the material is melted. After solidification of the melt, the weld is formed. In the weld seam and in a heat-affected zone adjoining the weld seam, a structural change of the materials of the workpieces welded together was effected by the melting. Such structural changes usually reduce the strength or the energy absorption capacity of the weld in comparison to areas of the workpieces without microstructural changes.

If the workpieces have a coating, for example aluminum coatings on press-hardened workpieces, residues of the coatings can remain distributed in the weld seam and influence the fatigue strength.

In the application of mechanical joining processes workpieces, for example, in a forming plane, forming a positive and / or frictional, reshaped. An example is the clinching, in which two superimposed workpieces are deformed so that a positive and non-positive connection between the two arises. For this it is necessary that the materials of the workpieces have a minimum ductility. If this is too low, brittle fracture occurs during forming. At the same time, the tools can be damaged by large forces occurring. For this reason, currently apply materials such. B. Usibor® as not suitable for joining.

Mechanical processes cause no thermally-induced microstructural changes, but come at high strengths, eg. B. at more than 600 MPa, and thus high yield stress occurring, to their limits of use, if at the same time for a joining process deformations are required.

To effect a reduction of the flow stress of the materials, the forming is thermally supported, that is, the workpieces are before forming. As a result, sufficient energy is present in the materials to induce deformation-induced dislocation movements and to allow plastic deformation without brittle fracture occurring. In this case, a structural change at temperatures up to 900 ° C is considered to be non-harmful.

In a method according to the DE 10 2004 062 896 B4 two or more metal workpieces are positively connected with each other by being thermally assisted over a forming area. For this purpose, at least two tools are available, which can be pressed against each other with a compressive force. The workpieces adjoin one another in a forming plane between the tools and are irradiated with an electromagnetic radiation from a laser light source in such a way that a thermal activation or heating of the workpieces over the forming area is achieved. In this case, the electromagnetic radiation is directed by a transparent material for the electromagnetic radiation in at least one of the tools on the forming area.

A disadvantage of this solution is that within the tool, a passage or opening must be present to accommodate the transparent material for the electromagnetic radiation. This is the production of the Tool complicated and costly. In addition, the strength of the tool is adversely affected and the size of a focal spot, in which the electromagnetic radiation is imaged in the forming plane on a workpiece, can not be easily adapted to changing requirements of the joining process.

Without an implementation comes a solution after the US 2003/0037428 A1 out. In this, the tools are associated with electrodes. If the tools are brought into contact with the workpieces to be joined, a current can flow in the workpieces over approximately the forming region between the electrodes and through the electrically conductive workpieces. As a result of the current flow, the forming area is heated. The tools are designed to accommodate the electrodes and their electrical insulation complicated and weakened in their strength.

From the WO 02/062499 A1 It is known that a radiation source emitting radiation source can be arranged next to the tools. The tools used are rollers by means of which a flat workpiece can be formed into a profile without cutting. By the radiation source, for example, a laser radiation is directed into a focal spot on the surface of the workpiece. The focal spot is generated in an area of a roll inlet, that is to say before the actual forming area, as a result of which undesired heat losses occur.

The invention has for its object to provide a device with easy to produce tools that can be easily adapted to changing requirements of the joining process.

The object is achieved by a device for joining a first workpiece and a second workpiece according to claim 1, wherein the device has a first tool, having a first contour, and a second tool, having a second contour. Between the tools, the first workpiece and the second workpiece can be arranged one above the other in a forming plane. The first contour and the second contour can be pressed against each other via a forming area. The device has at least one radiation source for providing electromagnetic radiation which serves to heat the workpieces between the tools. The device according to the invention is characterized in that at least one respective radiation source is arranged laterally of the tools such that their electromagnetic radiation is respectively directed to the workpiece facing the radiation source and into the deformation region. Each of the radiation sources is formed by at least one direct-radiating diode emitter. In this case, each radiation source is formed by annularly arranged around the tool direct radiating diode emitter.

The one or more diode emitters may be arranged in a module. There may also be an optical system by means of which the electromagnetic radiation of each of the radiation sources is influenced, for example focused and directed. The radiation sources are advantageously connected to a controller, by means of the parameters of the electromagnetic radiation emitted by the radiation sources, for. B. emission duration and intensity are controllable.

The at least one diode emitter of a radiation source is preferably arranged such that a focal spot is formed in the deformation region by the electromagnetic radiation emitted by the radiation source and directed onto the deformation region.

The radiation source is preferably arranged such that the electromagnetic radiation is directed from a tool-side direction into the forming plane and into the forming area.

It is particularly preferred if the radiation source is arranged near and adjacent to the forming area facing side of the tools.

Preferably, these are directed from an area near and adjacent to the side of each tool in the forming area, which faces the forming area.

For joining, a first workpiece and a second workpiece between the first tool, having a first contour, and the second tool, having a second contour, are superimposed in the forming plane so that they touch each other via a forming area. Now, the electromagnetic radiation is directed over the forming area on each outwardly facing side of the workpieces and the forming area on the side of each workpiece is simultaneously exposed to the electromagnetic radiation.

After heating, the first contour and the second contour are pressed against each other, so that the workpieces are formed over the heated forming area corresponding to the first contour and the second contour.

Electromagnetic radiation can be all radiations that are suitable for heating the materials to be formed. The electromagnetic radiation is preferably a laser radiation.

The use of direct-radiating diodes or diode emitters has the advantage that the emitted radiation can be directed into the deformation area without major absorption and scattering losses and an energy-efficient heating of the workpieces can take place. By directing the electromagnetic radiation from each side of each of the tools, tools without apertures or similar radiation-transmissive devices can be used. In addition, a focal spot in the forming plane can be easily controlled and corrected in terms of its size, shape, position and (spatial / temporal) intensity distribution. The aforementioned parameters are, for example, to adapt to the material, the material thickness, etc. of the workpieces to be reshaped or corrected during a series of forming operations.

It is possible to use pulsed electromagnetic radiation, wherein a simultaneous application is also present when the electromagnetic radiation, which is applied to the one workpiece and the electromagnetic radiation, which is applied to the other workpiece, are mutually phase-shifted. As a result of the application occurring from both sides, the workpieces are heated at least over their forming area. The workpieces are then reshaped by squeezing the tools.

Fig. 1

eine erste Ausführung der Vorrichtung als Prinzipskizze;

Fig. 2

eine zweite Ausführung der Vorrichtung mit einem Diodenemittermodul;

Fig. 3

eine dritte Ausführung der Vorrichtung mit zwei Strahlungsquellen je Werkzeug;

Fig. 4

eine Ausführung der erfindungsgemäßen Vorrichtung mit einer ringförmigen Strahlungsquelle an einem Werkzeug.

The invention will be explained in more detail with reference to figures and embodiments. Show

Fig. 1

a first embodiment of the device as a schematic diagram;

Fig. 2

a second embodiment of the device with a diode emitter module;

Fig. 3

a third embodiment of the device with two radiation sources per tool;

Fig. 4

an embodiment of the device according to the invention with an annular radiation source on a tool.

As essential components of a device according to the invention are in Fig. 1 a first tool 5 with a first contour 5.1 and a second tool 6 with a second contour 6.1 and two radiation sources 7, wherein a radiation source 7 next to the first tool 5 and the other radiation source 7 is arranged adjacent to the second tool 6.

The first tool 5 and the second tool 6 are movable in an advancing direction 11 or counter to the feed direction 11 and undeliverable. The first contour 5.1 and the second contour 6.1 are each in a direction perpendicular to Feed direction 11 extending end face of the first tool 5 and the second tool 6 as mutually complementary elevations and depressions available. The first contour 5.1 and the second contour 6.1 can be brought into direct contact with one another by delivering the first tool 5 and the second tool 6 in a forming plane 3.

In the forming plane 3, a first workpiece 1 and a second workpiece 2 are superimposed and movable along a transport direction 10. Mounts of the workpieces 1, 2 and means for transporting the workpieces 1, 2 in the transport direction 10 are not shown.

Are the first tool 5 and the second tool 6 delivered to each other, meet their first contour 5.1 and second contour 6.1 in the forming plane 3. A forming region 4 of the first tool 5 and the second tool 6 is by the extension of the first contour 5.1 and second contour 6.1 given in the forming plane 3.

The first contour 5.1 is formed as a survey and the second contour 6.1 as a depression, wherein the dimensions of the survey a depression of existing in the forming area 4 material of a first workpiece 1 and a second workpiece 2 in the recess of the second contour 6.1 allowed (not shown). By the first tool 5 and the second tool 6 and their contours 5.1 and 6.1, a die is formed.

On the side next to the first tool 5 and the second tool 6 there is a respective radiation source 7 for providing electromagnetic radiation. The radiation source 7 is formed by a direct-radiating diode emitter. The electromagnetic radiation is directed along each beam path (shown schematically) in each case in a radiation direction 8 to each workpiece 1 or 2, which faces the respective radiation source 7. The electromagnetic radiation is directed in each case in the forming plane 3 and in the forming region 4, so that on those surfaces of the workpieces 1 and 2, which face the respective radiation sources 7, the electromagnetic radiation in each focal spot 9 (see Fig. 2 ) is shown. Size and shape as well as the energy distribution over the focal spot 9 are selected so that the first workpiece 1 and the second workpiece 2 are heated via the forming region 4.

By means of a controller 13, which is connected to the radiation sources 7 signal-conducting, the radiation sources 7 are controllable with respect to the parameters of the emitted electromagnetic radiation, such as emission duration and intensity.

In further embodiments, the first contour 5.1 and the second contour 6.1 shaped differently, z. B. rounded, widening at the bottom (eg for clinching) or conical, be. There may also be more than two workpieces in the forming plane 3.

In a second embodiment of the device according to Fig. 2 the radiation source 7 arranged next to the first tool 5 is designed as a module consisting of a plurality of directly emitting diode emitters. The diode emitters are preceded by an optical system 12, by means of which the electromagnetic radiation emitted by the diode emitters is focused, guided along the radiation direction 8 and imaged in a focal spot 9 on the surface of the first workpiece 1. For the radiation source 7 arranged next to the second tool 6, the above applies accordingly (not shown). The module is connected to a controller 13.

In a third embodiment of the device are according to Fig. 3 two radiation sources 7 are each arranged laterally of the tools 5, 6, the emitted electromagnetic radiation of which is reproduced in a common focal spot 9 on the surface of the first workpiece 1 or of the second workpiece 2. In other embodiments, the radiation sources 7 can each also be designed as a module consisting of a plurality of directly emitting diode emitters, to which an optic 12 is arranged upstream. The radiation sources 7 can be controlled individually via the controller 13.

In Fig. 4 an embodiment of the device according to the invention is shown, in which the radiation source 7 is formed by ring-shaped around a tool 5, 6 arranged directly radiating diode emitter (shown very schematically). Shown is, merely by way of example, a view in the feed direction 11 on the first contour 5.1 of the first tool 5 and on the radiation source. 7

In further embodiments of the device according to the invention, the radiation sources 7 on both sides of the forming plane 3 similar. z. B. as in Fig. 1 or in Fig. 2 shown, or be different. So can those in the FIGS. 1 and 2 be shown combined in a device. There may also be other numbers of radiation sources 7 on one side of the forming plane 3, which in turn may be the same or different.

The following is the operation of the device according to Fig. 1 be explained. A first workpiece 1 and a second workpiece 2 are placed one above the other in the forming plane 3 and held there. The first workpiece 1 points upward, the second workpiece 2 points downward. The two workpieces 1 and 2 are set up so that an area over which the two workpieces 1 and 2 are to be reshaped coincides with the forming area 4. The radiation sources 7 are switched on and the electromagnetic radiation is directed in each case into the forming plane 3 and into the forming region 4, as a result of which the first workpiece 1 and the second workpiece 2 are heated via the forming region 4. If the two workpieces 1 and 2 sufficiently heated, the radiation sources 7 are turned off and the upper tool 5 and the lower tool 6 along the feed direction 11 moves toward each other until the material of the two workpieces 1 and 2 on the forming region 4 through the first contour 5.1 is pressed into the second contour 6.1. In this case, the first workpiece 1 and the second workpiece 2 are plastically deformed over the forming area 4. After reshaping, the upper tool 5 and the lower tool 6 along the feed direction 11 are separated again and the workpieces 1 and 2 along a transport direction 10 in the forming plane 3 shifted so far until the next Area over which the first workpiece 1 and the second workpiece 2 are to be reshaped comes to rest in the forming area 4.

The device according to the invention can be used in the technological fields of joining technology, for. B. in the body shop, are applied.

reference numeral

1

first workpiece

2

second workpiece

3

Umformebene

4

forming region

5

first tool

5.1

first contour

6

second tool

6.1

second contour

7

radiation source

8th

radiation direction

9

focal spot

10

transport direction

11

infeed

12

optics

13

control

Claims (2)

1. Device for joining a first workpiece (1) and a second workpiece (2), with a first tool (5) having a first contour (5.1) and with a second tool (6) having a second contour (6.1), between which the first workpiece (1) and the second workpiece (2) can be arranged on top of each other in a forming plane (3), wherein the first contour (5.1) and the second contour (6.1) can be pressed against each other via a forming area (4), and at least one radiation source (7) for providing electromagnetic radiation to heat the workpieces (1, 2) between the tools (5, 6), characterized in that

   - at least one radiation source (7) is arranged to the side of each of the tools (5, 6) in such a way that electromagnetic radiation emitted by each radiation source (7) is directed to the respective workpiece (1, 2) facing the radiation source (7) and into the forming area (4) and

   - each of the radiation sources (7) is made up of at least one direct-radiating diode emitter, wherein each radiation source (7) is made up of direct-radiating diode emitters arranged in a ring around the tool (5, 6).
2. Device according to claim 1, characterized in that
   at least one diode emitter of a radiation source (7) is arranged in such a way that a focal spot (9), whose size, form, location and spatial/temporal intensity distribution can be controlled, is generated on the surface of the workpiece (1, 2) facing the radiation source (7), the surface being located in the forming area (4), through electromagnetic radiation emitted by the radiation source (7) and directed to the forming area (4).

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