Method for Laser Welding of Steel Plates

Abstract

A device and method that allows bipolar plates to be welded in a rotating transport device in a vertical position at high speed, thereby fulfilling the high requirements for loading, fixing, welding and unloading the components to a high degree. Overall, a high level of productivity is achieved with the device and method.

Claims

1-12. (canceled)

13. A method for laser welding workpieces (14) with a device using a transport device (1) rotating in a transport plane XY, the transport device (1) comprising a chain-like conveyor belt (2) with chain links (3), each chain link (3) provided with a clamping device (8) having a base plate (11) and a folding lever (13), the workpiece (14) being fixed to the base plate (11) via clamping plates (10a, 10b) for the welding process, the device having at least one laser optical system (22) for welding the workpiece (14), the transport plane XY lying in a horizontal plane and the welding process taking place in a welding plane XZ, comprising: loading the clamping device (8) with at least one workpiece (14) to be welded and fixing the workpiece (14) to be welded on a clamping plate B (10b) in a loading zone (15); rotating the folding lever (13) about a swivelling axis (12) by approximately 90 degrees from an approximately horizontal position to an approximately vertical position, and fixing the workpiece (14) to be welded and the clamping plate B (10b) to the base plate (11) and a clamping plate A (10a) in a welding device/loading zone (16); turning back the folding lever (13) of the clamping device (8) by approximately 90 degrees from the approximately vertical position to the approximately horizontal position in the welding device-loading zone (16); welding the workpiece (14) that is fixed between the clamping plate A (10a) and the clamping plate B (10b) in a welding/cutting zone (17); rotating the folding lever (13) about the swivelling axis (12) by approximately 90 degrees from an approximately horizontal position to an approximately vertical position and taking over the welded workpiece (19) and the clamping plate-B (10b) in a welding device/unloading zone (18); turning back the folding lever (13) with the welded workpiece (19) and the clamping plate-B (10b) from an approximately vertical position by 90 degrees to an approximately horizontal position in the welding device/unloading zone (18); and removing the welded workpiece (19) from the clamping plate-B (10b) in the unloading zone (15).

14. The method according to claim 13, wherein the circulating transport device (1) follows an oval-shaped path in the transport plane XY and is divided into two linear movement regions (5a, 5b) and two rotary movement regions (6a, 6b).

15. The method according to claim 13, wherein the transport device (1) rotating in the transport plane XY moves linearly in the welding/cutting zone (17) and moves rotationally in the welding device/unloading zone (18), the welding device/loading zone (16) and the loading/unloading zone (15).

16. The method according to claim 14, wherein the transport device (1) rotating in the transport plane XY moves linearly in the welding/cutting zone (17) and moves rotationally in the welding device/unloading zone (18), the welding device/loading zone (16) and the loading/unloading zone (15).

17. The method according to claim 13, wherein the workpiece (14) to be welded is fixed perpendicular to the transport plane XY in the clamping device (8) on the circulating transport device (1) and is welded in the welding/cutting zone (17).

18. The method according to claim 14, wherein the workpiece (14) to be welded is fixed perpendicular to the transport plane XY in the clamping device (8) on the circulating transport device (1) and is welded in the welding/cutting zone (17).

19. The method according to claim 15, wherein the workpiece (14) to be welded is fixed perpendicular to the transport plane XY in the clamping device (8) on the circulating transport device (1) and is welded in the welding/cutting zone (17).

20. The method according to claim 13, wherein the laser source (23) provides coverage of an entire working area (20) with the at least one laser optic (22).

21. The method according to claim 14, wherein the laser source (23) provides coverage of an entire working area (20) with the at least one laser optic (22).

22. The method according to claim 15, wherein the laser source (23) provides coverage of an entire working area (20) with the at least one laser optic (22).

23. The method according to claim 17, wherein the laser source (23) provides coverage of an entire working area (20) with the at least one laser optic (22).

24. The method according to claim 13, wherein the workpiece (14) to be welded is loaded and unloaded in the loading/unloading zone (15) directly onto the clamping plate-A (10a).

25. The method according to claim 14, wherein the workpiece (14) to be welded is loaded and unloaded in the loading/unloading zone (15) directly onto the clamping plate-A (10a).

26. The method according to claim 15, wherein the workpiece (14) to be welded is loaded and unloaded in the loading/unloading zone (15) directly onto the clamping plate-A (10a).

27. The method according to claim 17, wherein the workpiece (14) to be welded is loaded and unloaded in the loading/unloading zone (15) directly onto the clamping plate-A (10a).

28. The method according to claim 20, wherein the workpiece (14) to be welded is loaded and unloaded in the loading/unloading zone (15) directly onto the clamping plate-A (10a).

29. The method according to claim 13, wherein the welded workpieces (14) are bipolar plates for fuel cells or for heat exchanger plates for transferring thermal energy.

30. The method according to claim 14, wherein the welded workpieces (14) are bipolar plates for fuel cells or for heat exchanger plates for transferring thermal energy.

31. The method according to claim 15, wherein the welded workpieces (14) are bipolar plates for fuel cells or for heat exchanger plates for transferring thermal energy.

32. The method according to claim 17, wherein the welded workpieces (14) are bipolar plates for fuel cells or for heat exchanger plates for transferring thermal energy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further explained in the following on the basis of example embodiments and referring to drawings. In the drawings,

[0025] FIG. 1 is a schematic top view of an embodiment of the transport device,

[0026] FIG. 2A is a first perspective view of a clamping device,

[0027] FIG. 2B is a second perspective view of a clamping device,

[0028] FIG. 2C is a third perspective view of a clamping device,

[0029] FIG. 2D a fourth perspective view of a clamping device, and

[0030] FIG. 3 is a schematic side view of the plant according to the invention.

DETAILED DESCRIPTION

[0031] FIG. 1 shows a top view of a rotating transport device 1 whose drive 7 moves the conveyor belt 2 clockwise in the transport plane XY, travelling through areas of translatory movement 5a,5b and rotary movement areas 6a,6b. The transport plane XY is essentially the horizontal plane. The conveyor belt 2 consists of a large number of conveyor links 3, which are equipped with a clamping device 8. A base plate 11 and a swivelling folding lever 13 are attached to each chain link 3. The workpiece 14 to be welded can be held between the base plate 11 and the folding lever 13. Loading 24 of the circulating conveyor belt 2 with the workpieces, i.e. with the steel plates, takes place in the translatory area 5a with the folding lever 13 folded out and horizontal in the loading/unloading zone 15. In the welding device loading zone 16 in the area of rotative movement 6a, the workpiece 14 is brought into a vertical position in the clamping device 8 by folding back (folding up) the folding lever 13 and fixed to the base plate 11 by means of clamping means (clamping plates B 10b and A 10a). In the next step, the folding lever 13 is brought back into the horizontal position. This is necessary so that the laser beam 23 of the welding laser 22 can be directed onto the workpiece 14 in the subsequent step. In the translatory area 5b, the workpiece 14 is welded in the welding/cutting zone 17 by means of the laser beam 23 of the laser optics 22. Here, the two steel plates of the workpiece 14 are welded together. It is also conceivable that the laser beam 23 could also be used for cutting or marking. In the unloading zone 18 of the welding device, the folding lever 13 is folded in a first step into a vertical position and the clamping device 8 with the now welded workpiece 19 is folded in a second step from a vertical into a horizontal position. In the loading/unloading zone 15, the welded workpiece 19 is removed from the circulating conveyor belt 2 by unloading 25. The cleaning station 26 is used to clean the clamping device 8.

[0032] FIG. 2A shows a first perspective view of the clamping device 8 in the state before loading, without the workpiece 14 to be welded. A clamping plate A 10a is attached, preferably fixed, to the base plate 11, which is firmly connected to the chain link 3. The clamping plate B 10b, possibly with several partial clamping plates 9, is detachably fixed on the folding lever 13. The clamping plate B 10b can be fixed and released on the folding lever 13 by magnetic force or mechanically. The folding lever 13 is located in a horizontal position in the XY plane and is connected to the clamping device 8 so that it can rotate around the swivelling axis 12.

[0033] FIG. 2B shows a second perspective view of the clamping device 8 in the loaded state, whereby the workpiece 14 to be welded is positioned and fixed relative to the clamping plate B 10b. The workpiece 14 is therefore placed on the clamping plate B 10b. The folding lever 13 is in a horizontal position in the XY plane.

[0034] FIG. 2C shows a third perspective view of the clamping device 8, in welded state. The workpiece 14 to be welded is fixed between the two plates clamping plate A 10a and clamping plate B 10b. The clamping plate B 10b is no longer present on the folding lever 13. The folding lever 13 is in a horizontal position in the XY plane. The workpiece 14, i.e. the two steel plates to be welded, are clamped between the two clamping plates A 10a and B 10b. Clamping can preferably be done using magnetic forces. The clamping plates A 10a and B 10b are designed in such a way that they sufficiently press the steel plates to be welded together over their entire surface, whereby the areas in which the laser beam 23 hits the workpiece 14 are excluded in the clamping plate B 10b.

[0035] FIG. 2D shows a fourth perspective view of the clamping device 8, in closed state. The folding lever 13 is folded out of the XY plane into the XZ plane, now rests on the base plate 11 and is in a vertical position. This state is assumed when the workpiece 14 is placed on the clamping plate A 10a and also when the workpiece 14 is lifted off the clamping plate A 10a.

[0036] FIG. 3 shows a side view of the welding/cutting area 17 of the circulating transportation device 1, whose chain links 3 move continuously in the plane XY in transport direction TR. The clamping device 8 is in the welding state. The workpiece to be welded 14 is fixed in the clamping device 8 between the clamping plate A 10a and the clamping plate B 10b. At welding plane XZ, the laser optics cover the entire working area 20. The folding levers 13 are in the Folding down DOWN or Folding up UP status. The folding lever 13 is folded down during welding.

[0037] The disclosed method for laser welding of workpieces 14 can proceed as follows:

[0038] In the loading zone 15, the folded-down folding lever 13 of the clamping device 8 is loaded with at least one workpiece 14 to be machined and the workpiece is fixed on the clamping plate B 10b, for example with the aid of magnetic forces. Thereby, the clamping plate B 10b rests on the folding lever 13. In the loading zone 16 of the welding device, the folding lever 13 is now turned about the swivelling axis 12 by approximately 90 degrees from the approximately horizontal to an approximately vertical position and the workpiece 14 to be welded and the clamping plate B 10b are fixed to the base plate 11 and to a clamping plate A (10a) which is attached to the base plate 11.

[0039] After this, the folding lever (13) without the clamping plate B 10b and the workpiece 14 is turned back by approximately 90 degrees from the vertical to an approximately horizontal position.

[0040] In the welding/cutting zone 17, the workpiece 14, which is clamped between the clamping plate A 10a and the clamping plate B 10b, is then welded by a welding laser. Then, in the unloading zone 18 of the welding device, the folding lever 13 is turned again about the swivelling axis 12 by approximately 90 degrees from the approximately horizontal to an approximately vertical position and then takes on the welded workpiece 19 and the clamping plate B 10b. The folding lever 13 with the welded workpiece 19 and the clamping plate B 10b is turned back from an approximately vertical position by 90 degrees to an approximately horizontal position.

[0041] The workpiece 14 and the clamping plate B 10b can be transferred and fixed in place using magnetic forces.

[0042] In the unloading zone 15, the welded workpiece 19 is then removed from the clamping plate B 10b and moved on to subsequent steps. The clamping plate B 10b always remains in the device.

REFERENCE NUMERALS

[0043] 1 Transport device [0044] 2 Conveyor belt [0045] 3 Chain link [0046] 5a,b Area of translatory movement [0047] 6a,b Area of rotative movement [0048] 7 Drive [0049] 8 Clamping device [0050] 9 Partial clamping plates [0051] 10a Clamping plate A [0052] 10b Clamping plate B [0053] 11 Base plate [0054] 12 Swivelling axis [0055] 13 Folding lever [0056] 14 Workpiece to be machined [0057] 15 Loading/unloading zone [0058] 16 Welding deviceloading zone [0059] 17 Welding/cutting zone [0060] 18 Welding deviceunloading zone [0061] 19 Machined workpiece/welded workpiece [0062] 20 Work area [0063] 22 Laser optics [0064] 23 Laser beam [0065] 24 Loading [0066] 25 Unloading [0067] 26 Cleaning station [0068] TR Transport direction [0069] XY Transport plane [0070] XZ Welding plane