METHOD AND DEVICE FOR PRODUCING A SHEET METAL BLANK BY MEANS OF LASER CUTTING

Abstract

The invention relates to a device for producing a sheet-metal blank by means of laser cutting, including a laser cutting device having a laser cutting head movable back and forth in a transport direction and in a y-direction extending vertically to the transport direction, and a stretching device for stretching a metal sheet accommodated in the laser cutting device. The device includes a first clamping device provided upstream of the laser cutting device for clampingly gripping a first portion of the metal sheet, a second clamping device provided downstream of the laser cutting device for clampingly gripping a second portion of the metal sheet, and a mechanism for changing a distance between the first and the second clamping device such that a tensile stress is exerted onto a metal sheet that is clampingly gripped therewith.

Claims

1. A method for producing a sheet-metal blank (9) by means of laser cutting, comprising the following steps: feeding a metal sheet (1) in a transport direction (T) to a laser cutting device (7), which has a laser cutting head (12) movable back and forth in the transport direction (T) and in a y-direction extending vertically to the transport direction (T), clampingly gripping a first portion of the metal sheet (1) upstream of the laser cutting device (7) by means of a first clamping device (16) and clampingly gripping a second portion of the metal sheet (1) downstream of the laser cutting device (7) by means of a second clamping device, stretching the metal sheet (1) accommodated in the laser cutting device (7) by generating a tensile stress on the metal sheet (1) clampingly held between the first (16) and the second clamping device, relaxing the metal sheet (1), and cutting the sheet-metal blank (9) from the metal sheet (1) by moving the laser cutting head (12) along a predefined cutting path.

2. The method according to claim 1, wherein the metal sheet (1) is held at most by one of the clamping devices (16) during the cutting.

3. The method according to claim 1, wherein the metal sheet (1) is fed in a clocked manner to the laser cutting device (7).

4. The method according to claim 1, wherein the metal sheet (1) is a sheet-metal strip, which is unwound continuously from a coil (2) and is guided through a loop pit (4) upstream of the first clamping device (16).

5. A device for producing a sheet-metal blank (9) by means of laser cutting, comprising: a laser cutting device (7) having a laser cutting head (12) movable back and forth in a transport direction (T) and in a y-direction extending vertically to the transport direction (T), and a stretching device (6) for stretching a metal sheet (1) accommodated in the laser cutting device, comprising a first clamping device (16) provided upstream of the laser cutting device (7) for clampingly gripping a first portion of the metal sheet (1), a second clamping device provided downstream of the laser cutting device (7) for clampingly gripping a second portion of the metal sheet (1), and a mechanism for changing a distance between the first (16) and the second clamping device such that a tensile stress is exerted onto a metal sheet (1) that is clampingly gripped therewith, in such a way that that the yield point of a metal forming the metal sheet (1) is exceeded, so that the metal sheet (1) is plastically deformed.

6. The device according to claim 5, wherein the stretching device (6) comprises a frame formed of two longitudinal struts (13) extending in the transport direction (T), a first stretching crossmember (14) accommodating the first clamping device (16) and extending in the y-direction, and a second stretching crossmember (15) accommodating the second clamping device and extending in the y-direction.

7. The device according to claim 6, wherein the laser cutting device (7) is arranged within the frame in plan view.

8. The device according to claim 5, further comprising a feeding device (5) for feeding the metal sheet (1) in the transport direction (T) to the laser cutting device (7).

9. The device with a metal sheet (1) according to claim 5, wherein the metal sheet (1) is a sheet-metal strip accommodated on a coil (2).

10. The device according to claim 5, wherein a loop pit (4) is provided upstream of the feeding device (5).

11. The device with a metal sheet (1) according to claim 5, wherein the metal sheet (1) can be fed in a clocked manner to the laser cutting device (7) by means of the feeding device (5).

12. The device according to claim 6, wherein the mechanism for changing the distance between the first (16) and the second clamping device is a hydraulic device (17), by means of which at least one of the two stretching crossmembers (14, 15) can be moved back and forth in the transport direction (T).

Description

[0028] Exemplary embodiments of the invention will be explained in greater detail hereinafter with reference to the drawings, in which:

[0029] FIG. 1 shows a schematic side view of a laser cutting line,

[0030] FIG. 2 shows a schematic side view of the combined stretching and laser cutting device in FIG. 1,

[0031] FIG. 3 shows a plan view according to FIG. 2, and

[0032] FIG. 4 shows a front view according to FIG. 2.

[0033] In the case of the laser cutting line shown in FIG. 1, a sheet-metal strip 1 is unwound from a coil 2 and is guided through a roll straightening machine 3 in a transport direction T. A loop pit 4 is disposed downstream of the roll straightening machine 3. Reference sign 5 denotes a feeding device formed for example of two mutually opposed clamping rollers for feeding the sheet-metal strip 1 to a combined stretching and laser cutting device. The stretching device is denoted by reference sign 6, and the laser cutting device is denoted by reference sign 7. A conveyor belt 8 for transporting away cut sheet-metal blanks 9 is disposed downstream of the combined stretching and laser cutting device.

[0034] FIGS. 2 to 4 show views of the combined stretching and laser cutting device according to FIG. 1.

[0035] The laser cutting device 7 comprises two rails 10 extending in the transport direction T, from which rails a bridge 11 is suspended and is movable back and forth in the transport direction T. A laser cutting head 12 is mounted on the bridge 11 so as to be movable back and forth in a y-direction extending vertically to the transport direction T. The laser cutting head 12 can be controlled arbitrarily in the y-direction and transport direction T by means of a controller. The laser cutting head is moved by means of the controller along a predefined cutting path. The predefined cutting path corresponds to a desired outer contour of the sheet-metal blank 9 to be produced.

[0036] The stretching device 6 comprises two longitudinal struts 13, which in plan view of the laser cutting device 7 extend on either side of the rails 10 in the transport direction T. Reference sign 14 denotes a first stretching crossmember, which is arranged upstream of the laser cutting device 7. Reference sign 15 denotes a second stretching crossmember, which is arranged downstream of the laser cutting device 7. A first clamping device 16 is accommodated on the first stretching crossmember 14 and comprises mutually opposed upper and lower clamping jaws. The clamping jaws can be moved relative to one another in order to clamp the sheet-metal strip 1. The clamping jaws are expediently guided so that, when stretching the clamped sheet-metal portion, a clamping force exerted onto the sheet-metal portion by means of the clamping jaws increases. At the second stretching crossmember 15 as wellsimilarly to the first stretching crossmember 14there is accommodated a second clamping device having upper and lower clamping jaws (not shown here).

[0037] Reference sign 17 denotes a hydraulic device, by means of which the second stretching crossmember 15 is movable back and forth relative to the first stretching crossmember 14 in the transport direction T. Of course, it can also be that the second stretching crossmember 15 arranged downstream of the laser cutting device 7 is fixed and the first stretching crossmember 14 arranged upstream of the laser cutting device 7 is movable back and forth relative to the second stretching crossmember 15 against the transport direction. Furthermore, it is also possible that both the first stretching crossmember 14 and the second stretching crossmember 15 are movable back and forth in the transport direction.

[0038] The device functions as follows:

[0039] The sheet-metal strip 1 unwound from the coil 2 is straightened by means of the roll straightening machine 3. The loop pit 4 is used as a store for the sheet-metal strip 1 continuously unwound from the coil 2. The sheet-metal strip is fed in a clocked manner to the combined stretching and laser cutting device by means of the feeding device 5. Once a predefined sheet-metal portion has been fed to the combined stretching and laser cutting device, the sheet-metal portion is clampingly gripped upstream and downstream by means of the clamping devices 16 provided at the first stretching crossmember 14 and the second stretching crossmember 15. The second stretching crossmember 15 is then moved in the transport direction T by means of the hydraulic device 17, so that the sheet-metal portion held between the stretching crossmembers 14, 15 is stretched. The sheet-metal portion is then relaxed. The second clamping device provided at the second stretching crossmember is opened. The sheet-metal portion can also be clampingly held by means of the first clamping device 16 provided at the first stretching crossmember 14.

[0040] A sheet-metal blank 9 having a predefined contour is then cut from the stretched sheet-metal portion by means of the laser cutting device 7. As soon as the sheet-metal blank 9 has been completely cut out from the sheet-metal portion, the cut sheet-metal portion, together with the sheet-metal blank 9, is transported out from the combined stretching and laser cutting device in the transport direction T by means of a suitable conveying device (not shown here).

[0041] Although not shown in the figures, the combined stretching and laser cutting device can also be loaded with sheet-metal plates instead of the sheet-metal strip 1.

[0042] The laser cutting device 7 can also comprise a plurality of laser cutting heads 12 movable independently of one another.