Method for making defined conical holes using a laser beam

• US 6,518,543 B1
• Filed: 12/26/2000
• Issued: 02/11/2003
• Est. Priority Date: 02/11/1999
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Benz, Gerhard, Schneider, Rainer, Wawra, Thomas, Eisemann, Achim
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US09/673,065
• Time in Patent Office: 777 Days
• Field of Search: 219/121.7, 219/121.71, 219/121.73, 219/121.75
• US Class Current: 219/121.71
• CPC Class Codes: B23K 26/0648 comprising lenses
• CPC Class Codes: B23K 26/0665 by beam condensation on the workpiece, e.g. for focusing
• CPC Class Codes: B23K 26/384 of specially shaped holes
• CPC Class Codes: B23K 26/389 of fluid openings, e.g. nozzles, jets laser machining of inkjet nozzles B41J2/1634

Abstract

A method for producing bore holes, including conical bore holes, having a definite hole geometry in the longitudinal direction of the bore hole by adjusting the beam geometry and/or the beam parameters of a laser beam.

Claims

1. A method for producing a bore hole in a workpiece, the method comprising the steps of:

providing a laser beam;

focusing the laser beam on the workpiece using a lens;

selecting a focal distance of the lens, a laser beam diameter at a point where the laser beam enters the lens, a focal diameter, and a power density of the laser beam for producing the bore hole having a conical shape;

causing the laser beam to perform a wobbling motion with respect to the workpiece to describe the conical shape in the bore hole; and

producing a definite;

hole geometry of the bore hole in its longitudinal direction using the laser beam.

2. The method of claim 1, wherein a diameter of the bore hole increases in a direction of an exit of the laser beam.

3. The method of claim 1, wherein the laser beam widens prior to reaching the lens.

4. The method of claim 1, wherein a focal area of the laser beam passing through the lens is on a workpiece surface at an entry point of the bore hole.

5. The method of claim 1, wherein a focal area of the laser beam at an entry point of the bore hole is on a surface of the workpiece.

6. The method of claim 1, further comprising the step of rotating the laserbeam about its own axis synchronously with the wobbling motion.

7. The method of claim 1, wherein the laser beam is a linearly polarized laser beam whose plane of polarization is rotated synchronously with the wobbling motion.

8. The method of claim 1, wherein a geometry of the bore hole is adjustable by selecting at least one of a direction of polarization and a type of polarization.

9. The method of claim 8, wherein the laser beam is a linearly polarized laser beam.

10. The method of claim 8, wherein the laser beam is a circularly polarized laser beam.

11. The method of claim 1, wherein the laser beam is polarized using a half-wave plate and a quarter-wave plate.

12. The method of claim 1, wherein the laser beam is polarized using a half-wave plate and a quarter-wave plate, and wherein the quarter-wave plate being rotatable with respect to the half-wave plate.

13. A device for producing a bore hole in a workpiece, the device comprising:

a laser beam source for providing a laser beam;

a lens for focusing the laser beam on the workpiece;

a device for producing a wobbling motion of the laser beam, wherein the wobbling motion of the laser beam describes a conical surface of the bore hole; and

a rotatably arranged polarization device including a half-wave plate and a quarterwave plate, the quarter-wave plate being rotatable with respect to the half-wave plate.