Process for laser cutting a workpiece

• US 7,297,897 B2
• Filed: 04/20/2004
• Issued: 11/20/2007
• Est. Priority Date: 03/16/2001
• Status: Expired due to Fees

• Current Assignee: Antonios Nicholas, Michael Towler
• Original Assignee: Antonios Nicholas, Michael Towler
• Inventors: Nicholas, Antonios, Towler, Michael
• Primary Examiner(s): Johnson; Jonathan
• Assistant Examiner(s): Aboagye; Michael
• Application Number:
  US10/828,087
• Publication Number:
  US 20040195215A1
• Time in Patent Office: 1,309 Days
• Field of Search: 219/121.7, 219/121.67, 219/121.71, 219/121.73, 219/121.74, 219/121.75, 219/121.76, 219/121.78, 219/121.82, 219/121.83, 219/121.79, 250/559.29, 250/559.38
• US Class Current: 219/121.7
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 2103/34 Leather
• CPC Class Codes: B23K 2103/38 Fabrics, fibrous materials
• CPC Class Codes: B23K 2103/42 Plastics B23K2103/16 takes precedence
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/034 Observing the temperature of the workpiece
• CPC Class Codes: B23K 26/0342 Observing magnetic fields related to the workpiece
• CPC Class Codes: B23K 26/389 of fluid openings, e.g. nozzles, jets laser machining of inkjet nozzles B41J2/1634
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B29C 2791/009 Using laser curing using laser B29C2035/0838, welding using laser beams B29C65/16
• CPC Class Codes: B29C 59/007 Forming single grooves or ribs, e.g. tear lines, weak spots by moulding B29C37/0057; folding lines B29C53/06; in metal articles B21D17/00; by cutting B26D3/08
• CPC Class Codes: B29L 2031/3008 Instrument panels

Abstract

An apparatus is disclosed for cutting a workpiece. A laser beam is directed at successive points along a workpiece surface to be cut and a sensor emits a sensing beam directed at the same successive points as the cutting beam. A beam combining device receives both the sensor beam and the cutting beam and causes downstream beam segments to be collinear with each other as they impinge the workpiece surface. The cutting is thereby able to be carried out in a single pass, and is precise, repeatable and independent of cutting depth, angle of cutting, scoring patterns, material inconsistency, material color, and surface grain variability.

Claims

1. A process for cutting lines of weakness into an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said lines of weakness enabling formation of an airbag deployment door opening therein by pressure developed by deployment of said airbag, said trim piece having at least one layer, comprising:

partially cutting into a surface of the trim piece by directing a cutting beam from a cutting beam source onto to said surface and moving said trim piece relative to said source of said cutting beam in a predetermined weakening pattern;

monitoring the depth of cutting produced by said cutting beam by sensor beams produced from a first sensor and a second outer sensor respectively located on opposite sides of said trim piece and directed towards the trim piece location being cut by said cutting beam, said first sensor located on the same side of said trim piece as said cutting beam source;

said monitoring of the depth of cutting produced by said cutting beam including analyzing said first sensor beam and a return beam reflected from said surface after impingement by said first sensor beam by a conoscopic holography process;

combining said first sensor sensing beam with said cutting beam so that combined respective segments are collinear with each other when impinging said trim piece surface so as to be continuously directed at the same points along said weakening pattern;

controlling the extent of material removed by said cutting beam at each point along said predetermined weakening pattern by controlling said cutting in correspondence with feedback signals generated by said first and second sensors during said cutting; and

,

moving said trim piece relative to said cutting beam to partially cut said trim piece along said predetermined scoring pattern.

2. The process according to claim 1 wherein said cutting beam is a laser.

3. The process according to claim 1 wherein said cutting beam source is an ultrasonic generator.

4. The process according to claim 1 wherein said feedback signals provided by said first and second sensors together correspond to the material thickness remaining at each trim piece point being partially cut.

5. The process according to claim 1 wherein said trim piece is held in a fixture shaped to provide intimate contact with the outer surface of said trim piece.

6. The process according to claim 1 wherein said feedback signals produced from said sensors are used to also control the relative movement of the trim piece and scoring beam.

7. A process for cutting lines of weakening into an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said lines of weakening enabling formation of an airbag deployment door opening by said trim piece having at least one layer, comprising the steps of:

partially cutting into a surface of said trim piece by directing a cutting beam at said inside surface from a cutting beam source, and relatively moving said trim piece and said cutting beam source in a predetermined pattern after loading said trim piece onto a fixture where a surface of said trim piece is in contact with a surface of said fixture;

monitoring the depth of cutting effected by said cutting beam by feedback signals produced by a sensor located on the same side of said trim piece as said cutting beam source, said sensor having a sensor beam directed at said trim piece surface to be partially cut by analyzing said sensor beam and a beam reflected back from said surface after impingement by said sensor beam, by a conoscopic holography process;

combining said sensor beam and said cutting beam so as to have collinear segments thereof impinging said surface so that both beams impinge the same points on said trim piece;

controlling the depth of said cutting effected by said cutting beam at each point along said predetermined pattern in accordance with said feedback signals provided by said sensor; and

,

moving said trim piece relative to said cutting beam to partially cut said trim piece along said predetermined pattern.

8. The process according to claim 7 wherein said cutting beam source is a laser beam source.

9. The process according to claim 7 wherein said sensor beam is electromagnetic radiation of a different wavelength than said cutting beam which is also electromagnetic, and in said combining step, said sensor and cutting beams are both directed at a reflector which selectively transmits one beam and reflects the other as a result of the difference in wavelengths to cause segments of said respective beams to be collinear.

10. The process according to claim 9 wherein said reflector is inclined at 45°

and in said combining step one beam is directed at a front face of said reflector to be reflected and the other beam is directed at a rear face of said reflector through which it is transmitted.

11. The process according to claim 7 wherein said sensor beam is of much smaller diameter than said cutting beam, and wherein in said combining step, said cutting beam is directed at an inclined reflector surface having a hole formed therein much smaller than said cutting beam, and said sensor beam is directed through said hole in a direction collinear to said cutting beam after being reflected from said reflector.

12. A process for weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling formation of an air bag deployment door opening by pressure developed by deployment of said airbag, said trim piece having at least one layer, comprising:

partially cutting into an inside surface of the trim piece by directing a cutting beam from a cutting beam source onto said inside surface and relatively moving said trim and said cutting beam in a predetermined pattern;

controlling the depth of said cutting effected by said cutting beam at each point along said predetermined pattern; and

,

monitoring the cutting produced by said cutting beam with feedback signals from a sensor located on the same side of said trim piece as said cutting beam source, said sensor having a sensing beam combined in a collinear relationship with said cutting beam and continuously impinging the same point on said trim piece as the cutting beam, said sensor determining the depth of cutting produced by said cutting beam by a conoscopic holography process.

13. The process according to claim 12 wherein said cutting beam source is a laser beam source.

14. The process according to claim 12 wherein said cutting beam source is an ultrasonic generator.

15. The process according to claim 12 wherein said trim piece is attached to a fixture shaped to provide intimate contact with an outer surface of said trim piece.

16. A process for weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling formation of an air bag deployment door opening by pressure developed by deployment of said airbag, said trim piece having at least one layer, comprising:

cutting into an inside surface of the trim piece by directing a cutting beam at said inside surface and relatively moving said trim piece and said cutting beam in a predetermined pattern;

controlling the depth of said cutting effected by said cutting beam at each point along said predetermined pattern; and

,

monitoring the depth of cutting effected by said cutting beam by feedback signals corresponding to the location of the bottom of said partial cutting produced by a sensor located on the same side of said trim piece as said cutting beam, said sensor located next to said cutting beam and directing a sensing beam at said trim piece, said sensor beam approximately collinear with said cutting beam, said sensor determining the location of the bottom of said cutting produced by said cutting beam by a conoscopic holography process.

17. The process according to claim 16 wherein said cutting beam is a laser beam.

18. The process according to claim 16 wherein said cutting beam is a beam of ultrasonic waves.

19. The process according to claim 16 wherein said trim piece is held on to a fixture shaped to provide intimate contact with the outer surface of said trim piece.

20. A process for scoring a work piece, comprising:

cutting into a surface of the work piece by directing a cutting beam from a cutting beam source onto to said surface and moving said work piece relative to said source of said cutting beam in a predetermined pattern;

monitoring the depth of cutting produced by said cutting beam by sensor beams produced from a first sensor and a second outer sensor respectively located on opposite sides of said work piece and directed towards the work piece location being cut by said cutting beam, said first sensor located on the same side of said work piece as said cutting beam source;

said monitoring of the depth of cutting produced by said cutting beam including analyzing said first sensor beam and a return beam reflected from said surface after impingement by said first sensor beam by a conoscopic holography process;

combining said first sensor beam with said cutting beam so that combined respective segments are collinear with each other when impinging said work piece surface so as to be continuously directed at the same points along said predetermined pattern;

controlling the extent of material removed by said cutting beam at each point along said predetermined pattern by controlling said cutting in correspondence with feedback signals generated by said first and second sensors during said cutting; and

,

moving said work piece relative to said cutting beam to cut said work piece along said predetermined pattern.

21. The process according to claim 20 wherein said cutting beam is laser.

22. The process according to claim 20 wherein said cutting beam source is an ultrasonic generator.

23. The process according to claim 20 wherein said feedback signals provided by said first and second sensors together correspond to the material thickness remaining at each work piece point being partially cut.

24. The process according to claim 20 wherein said work piece is held in a fixture shaped to provide intimate contact with an outer surface of said work piece.

25. The process according to claim 20 wherein said feedback signals produced from said sensors are used to also control the relative movement of said work piece and scoring beam.

26. A process for cutting into a work piece, comprising the steps of:

cutting into a surface of said work piece by directing a cutting beam at said surface from a cutting beam source, and relatively moving said work piece and said cutting beam source in a predetermined pattern after loading said work piece onto a fixture where another surface of said work piece is in contact with a surface of said fixture;

monitoring the depth of cutting effected by said cutting beam by feedback signals produced by a sensor located on the same side of said work piece as said cutting beam source, said sensor having a sensor beam directed at said work piece surface to be partially cut by analyzing said sensor beam and a beam reflected back from said surface after impingement by said sensor beam, by a conoscopic holography process;

combining said sensor beam and said cutting beam so as to have collinear segments thereof impinging said surface so that both beams impinge the same points on said work piece;

controlling the depth of said cutting effected by said cutting beam at each point along said predetermined pattern in accordance with said feedback signals provided by said sensor; and

,

moving said work piece relative to said cutting beam to cut said work piece along said predetermined pattern.

27. The process according to claim 26 wherein said cutting beam source is a laser beam source.

28. The process according to claim 26 wherein said sensor beam is electromagnetic radiation of a different wavelength than said cutting beam which is also electromagnetic, and in said combining step, said sensor and cutting beams are both directed at a reflector which selectively transmits one beam and reflects the other as a result of the difference in wavelengths to cause segments of said respective beams to be collinear.

29. The process according to claim 28 wherein said reflector is inclined at 45°

and in said combining step one beam is directed at a front face of said reflector to be reflected and the other beam is directed at a rear face of said reflector through which it is transmitted.

30. The process according to claim 26 wherein said sensor beam is of much smaller diameter than said cutting beam, and wherein in said combining step, said cutting beam is directed at an inclined reflector surface having a hole formed therein much smaller than said cutting beam, and said sensor beam is directed through said hole in a direction collinear to said cutting beam after being reflected from said reflector.