Method for correcting a predetermined cutting path for cutting a sheet metal blank

• US 10,586,320 B2
• Filed: 04/25/2016
• Issued: 03/10/2020
• Est. Priority Date: 02/23/2015
• Status: Active Grant

• Current Assignee: Schuler Pressen GmbH & Company KG
• Original Assignee: Schuler Pressen GmbH & Company KG
• Inventors: Seitz, Alexander, Grosse, Jan-Peter
• Primary Examiner(s): Chen, Xuemei G
• Application Number:
  US15/552,734
• Publication Number:
  US 20180047151A1
• Time in Patent Office: 1,415 Days
• Field of Search: 72324, 72337, 83 768, 83 34, 83 49, 83 74, 83 84, 83100, 83375, 83422, 21912167, 21912172, 409 80, 700130
• CPC Class Codes: B23K 26/0846 for moving elongated workpieces longitudinally, e.g. wire or strip material
• CPC Class Codes: B23K 26/38 by boring or cutting
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/04 specially adapted for measuring length or width of objects while moving
• CPC Class Codes: G05B 19/402 characterised by control arrangements for positioning, e.g. centring a tool relative to a hole in the workpiece, additional detection means to correct position G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/37593 Measure correct setting of workpiece
• CPC Class Codes: G05B 2219/50062 Measure deviation of workpiece under working conditions, machine correction
• CPC Class Codes: G06T 2207/30136 Metal
• CPC Class Codes: G06T 2207/30204 Marker
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

The invention relates to a method for correcting a predetermined cutting path for cutting a metal blank from a metal strip continuously transported in a transport direction x with the following steps:

Simultaneously determining a first x coordinate x1 and a first y coordinate y1 of a point on a surface of the metal strip with respect to an x and a y reference;

Determining a second coordinate y2 of the point with respect to the y reference at precisely the time when the metal strip has been moved in the transport direction x by a predetermined first distance dx1 with respect to the first x coordinate x1;

Determining a first y correction value K_y1 by taking the difference between the first y coordinate y1 and the second y coordinate y2; and

Using the first y correction value K_y1 to correct the cutting path coordinates describing the predetermined cutting path.

Claims

1. A method for cutting a metal blank from a metal strip continuously transported in a transport direction x, comprising:

preparing a laser cutting apparatus comprising at least one laser moving in a transport direction x and in a transverse direction y running perpendicular to the transport direction x, and a computer storing cutting path coordinates describing a predetermined cutting path for moving the at least one laser;

simultaneously determining a first x coordinate x1 and a first y coordinate y1 of an arbitrary point on a surface of the metal strip with respect to an x and a y reference, the arbitrary point not being a separate mark put on the metal strip;

determining a second coordinate y2 of the point with respect to the y reference precisely when the metal strip has been moved in the transport direction x by a predetermined first distance dx1 with respect to the first x coordinate x1;

determining a first y correction value K_y1 by taking a difference between the first y coordinate y1 and the second y coordinate y2;

using the first y correction value K_y1 to correct cutting path coordinates describing the predetermined cutting path; and

cutting the metal blank by moving the at least one laser along the predetermined cutting path corrected by the first y correction value K_y1 while the metal strip is continuously transported in the transport direction x.

2. The method according to claim 1, further comprising:

providing a first y measurement device (M_y1) to measure the first y coordinate y1 of the metal strip with respect to the y reference;

providing a second y measurement device (M_y2) to measure the second y coordinate y2 of the metal strip with respect to the y reference, the second y measurement device (M_y2) being arranged at the predetermined first distance dx1 downstream of the first y measurement device (M_y1); and

providing a first displacement measurement device (M_x1) to measure the x coordinates of the metal strip with respect to the x reference.

3. The method according to claim 1, further comprising:

determining a third y coordinate y3 at a predetermined second distance dx2 from a place of determination of the second y coordinate y2;

determining a second y correction value K_y2 by taking a difference between the second y coordinate y2 and the third y coordinate y3; and

correcting the cutting path coordinates describing the predetermined cutting path by taking into consideration change in the second y correction value K_y2 with respect to the first y correction value K_y1 over the transport path or over time.

4. The method according to claim 3, further comprising:

providing a third y measurement device (M_y3) to measure the third y coordinate y3 of the metal strip with respect to the y reference, the third y measurement device being arranged at the predetermined second distance dx2 downstream of the second y measurement device (M_y2).

5. The method according to claim 1, wherein in the step of simultaneously determining the first x coordinate x1 and the first y coordinate y1 of the arbitrary point, one point on the surface of the metal strip is detected as the arbitrary point, and the one point is a part of the surface of the metal strip.

6. The method according to claim 1, wherein in the step of simultaneously determining the first x coordinate x1 and the first y coordinate y1 of the arbitrary point, the arbitrary point is not physically marked on the metal strip.

7. A method for cutting a metal blank from a metal strip continuously transported in a transport direction x, comprising:

preparing a laser cutting apparatus comprising at least one laser moving in a transport direction x and in a transverse direction y running perpendicular to the transport direction x, and a computer storing cutting path coordinates describing a predetermined cutting path for moving the at least one laser;

simultaneously determining a first x coordinate x1 and a first y coordinate y1 of an arbitrary point (P) of a surface of the metal strip with respect to an x and a y reference, the arbitrary point not being a separate mark put on the metal strip, this determination being done by means of a strip flow measuring device (BF), which allows a determination of positional coordinates xy of the point and their change over time or travel;

simultaneously determining a second x coordinate x2 and a second y coordinate y2 of the point (P) of the surface of the metal strip with respect to the x and y reference by means of the strip flow measuring device (BF), if the metal strip has been moved in the transport direction x by a predetermined third distance dx3;

determining a third y correction value K_y3 using a vector (V) determined by the strip flow measuring device (BF) from coordinate pairs (x1, y1) and (x2, y2);

using the third y correction value K_y3 to correct cutting path coordinates describing the predetermined cutting path; and

cutting the metal blank by moving the at least one laser along the predetermined cutting path corrected by the third correction value K_y3 while the metal strip is continuously transported in the transport direction x.

8. The method according to claim 7, further comprising:

measuring a fourth y coordinate y4 of the metal strip by means of a fourth y measurement device (M_y4) arranged at a predetermined fourth distance dx4 from the strip flow measuring device (BF) and correcting the third y correction value K_y3 using the fourth y coordinate y4.

9. The method according to claim 7, further comprising:

measuring a fourth x coordinate x4 of the metal strip by means of a second displacement measurement device (M_x2) and using the fourth x coordinate x4 for correction of the third y correction value K_y3.

10. The method according to claim 7, wherein the first coordinate pair (x1, y1) is determined from a surface structure detected at a time point t1 with the strip flow measuring device (BF).

11. The method according to claim 10, wherein the surface structure is determined from a 2- or 3-dimensional surface image produced at time point t1.

12. The method according to claim 11, wherein the surface image is produced using a strip flow measuring device (BF), which comprises one of the following components:

a camera, an optical mouse sensor, a distance sensor, or a confocal chromatic distance sensor.

13. The method according to claim 10, wherein the second coordinate pair (x2, y2) is calculated from another surface structure detected at other time points to following the time point t1 with the strip flow measuring device (BF).

14. The method according to claim 7, wherein in the step of simultaneously determining the first x coordinate x1 and the first y coordinate y1 of the arbitrary point, one point on the surface of the metal strip is detected as the arbitrary point, and the one point is a part of the surface of the metal strip.