Laser processing apparatus and laser processing method

Patent metadata

Field	Value
Publication number	US-9415465-B2
Application number	US-201214113120-A
Country	US
Kind code	B2
Filing date	Sep 26, 2012
Priority date	Oct 20, 2011
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

[Object]
To provide a laser processing apparatus and a laser processing method which are capable of reducing roughness of a cut surface in laser cutting using laser beams transmitted through optical fibers.
[Solution]
A laser processing apparatus according to the present invention includes at least one laser oscillator configured to emit laser beams, a plurality of optical fibers configured to transmit the emitted laser beams, and at least one optical element configured to focus the laser beams emitted from the optical fibers and irradiate a surface of a workpiece with the focused laser beams. At output ends of the optical fibers, the output ends of the plurality of optical fibers are placed in one or a plurality of ring shapes. Laser beams transmitted through the plurality of optical fibers placed on at least an outermost ring of the ring shapes each have a linear polarization, and polarization directions of the linearly polarized laser beams emitted from the output ends of the plurality of optical fibers are arranged radially around a center of the outermost ring.

First claim

The invention claimed is:

1. A laser processing apparatus which processes a workpiece by guiding polarized laser beams emitted from a laser oscillator, focusing the polarized laser beams, and irradiating a surface of the workpiece with the focused polarized laser beams, the laser processing apparatus comprising:
at least one laser oscillator configured to emit polarized laser beams;
a plurality of polarization maintaining optical fibers configured to transmit the emitted polarized laser beams, at the end of each optical fiber, a surface is formed that is perpendicular to the polarization direction of the linearly polarized light; and
at least one optical element configured to focus the polarized laser beams emitted from the optical fibers and irradiate the surface of the workpiece with the focused polarized laser beams,
wherein, at output ends of the optical fibers, the output ends of the plurality of optical fibers are placed in one or a plurality of ring shapes,
wherein the polarized laser beams transmitted through the plurality of optical fibers placed on at least an outermost ring of the one or plurality of ring shapes each have a linear polarization, and polarization directions of the linearly polarized laser beams emitted from the output ends of the plurality of optical fibers are arranged radially around a center of the outermost ring, and
wherein the polarized laser beams have an intensity of greater than or equal to 400 W per 1 mm of a thickness of the workpiece.

2. The laser processing apparatus according to claim 1 , wherein one of the optical fibers is further placed at a central part of the ring.

3. The laser processing apparatus according to claim 1 , wherein the output ends of the plurality of optical fibers are placed in a plurality of ring shapes which share a common center, and
wherein, through the optical fibers placed in the ring shapes inside the outermost ring, the polarized laser beams are transmitted, the polarized laser beams having polarization directions arranged radially around a center of the ring.

4. The laser processing apparatus according to claim 1 , further comprising:
at least one laser oscillator configured to emit non-polarized laser beams;
a plurality of optical fibers configured to transmit the emitted non-polarized laser beams,
wherein the output ends of the plurality of optical fibers are placed in a plurality of ring shapes which share a common center, and
wherein, through the optical fibers placed in the ring shapes inside the outermost ring, laser beams are transmitted, the laser beams being non-polarized laser beams.

5. The laser processing apparatus according to claim 1 , wherein the at least one optical element includes a collimator lens that changes the polarized laser beams emitted from the optical fibers into parallel light beams, and a focusing lens that focuses the parallel light beams emitted from the collimator lens.

6. The laser processing apparatus according to claim 5 , wherein the plurality of optical fibers are connected to a collimator fixing holder in which a plurality of collimators each having the collimator lens are placed in one or a plurality of ring shapes,
wherein the focusing lens is a spherical lens having spherical aberration or an aspherical lens having a predetermined curved surface, and
wherein the polarized laser beams emitted from the focusing lens are focused and the surface of the workpiece is irradiated with the focused polarized laser beams.

7. A laser processing method for processing a workpiece by guiding polarized laser beams emitted from a laser oscillator, focusing the polarized laser beams, and irradiating a surface of the workpiece with the focused polarized laser beams, the laser processing method comprising:
transmitting polarized laser beams emitted from at least one laser oscillator through a plurality of polarization maintaining optical fibers, and, by using at least one optical element that focuses the polarized laser beams and irradiates the surface of the workpiece with the focused polarized laser beams, focusing the polarized laser beams emitted from the respective optical fibers, and irradiating the surface of the workpiece with the focused polarized laser beams,
wherein, at output ends of the optical fibers, the output ends of the plurality of optical fibers are placed in one or a plurality of ring shapes,
wherein the polarized laser beams transmitted through the plurality of optical fibers placed on at least an outermost ring of the one or plurality of ring shapes each have a linear polarization, and polarization directions of the linearly polarized laser beams emitted from the output ends of the plurality of optical fibers are arranged radially around a center of the outermost ring, and
wherein the polarized laser beams have an intensity of greater than or equal to 400 W per 1 mm of a thickness of the workpiece.

8. The laser processing method according to claim 7 , wherein one of the optical fibers is further placed at a central part of the ring.

9. The laser processing method according to claim 7 ,
wherein the output ends of the plurality of optical fibers are placed in a plurality of ring shapes which share a common center, and
wherein, through the optical fibers placed in the ring shapes inside the outermost ring, the polarized laser beams are transmitted, the polarized laser beams having polarization directions arranged radially around a center of the ring.

10. The laser processing method according to claim 7 , further comprising:
at least one laser oscillator configured to emit non-polarized laser beams;
a plurality of optical fibers configured to transmit the emitted non-polarized laser beams,
wherein the output ends of the plurality of optical fibers are placed in a plurality of ring shapes which share a common center, and
wherein, through the optical fibers placed in the ring shapes inside the outermost ring, laser beams are transmitted, the laser beams being non-polarized laser beams.

11. The laser processing method according to claim 7 ,
wherein the at least one optical element includes a collimator lens that changes the polarized laser beams emitted from the optical fibers into parallel light beams, and a focusing lens that focuses the parallel light beams emitted from the collimator lens.

12. The laser processing method according to claim 11 ,
wherein the plurality of optical fibers are connected to a collimator fixing holder in which a plurality of collimators each having the collimator lens are placed in one or a plurality of ring shapes,
wherein the focusing lens is a spherical lens having spherical aberration or an aspherical lens having a predetermined curved surface, and
wherein the polarized laser beams emitted from the focusing lens are focused and the surface of the workpiece is irradiated with the focused polarized laser beams.

13. A laser processing apparatus which processes a workpiece by guiding polarized laser beams emitted from a laser oscillator, focusing the polarized laser beams, and irradiating a surface of the workpiece with the focused polarized laser beams, the laser processing apparatus comprising:
at least one laser oscillator configured to emit polarized laser beams;
a plurality of polarization maintaining optical fibers configured to transmit the emitted polarized laser beams, at the end of each optical fiber, a surface is formed that is perpendicular to the polarization direction of the linearly polarized light; and
at least one optical element configured to focus the polarized laser beams emitted from the optical fibers and irradiate the surface of the workpiece with the focused polari

Assignees

• Nippon Steel & Summitomo Metla Corp
• Nippon Steel & Sumitomo Metal Corp

Inventors

• Hirano Koji
• Imai Hirofumi

Classifications

• B23K26/0648

  comprising lenses · CPC title

• B23K26/0734

  into an annular shape · CPC title

• B23K26/0604

  by a combination of beams · CPC title

• B23K26/0617

  and with spots spaced along the common axis · CPC title

• B23K26/38

  by boring or cutting · CPC title