Laser welding method, laser welding apparatus, and cylindrical body

Patent metadata

Field	Value
Publication number	US-2016228989-A1
Application number	US-201415022263-A
Country	US
Kind code	A1
Filing date	Jan 29, 2014
Priority date	Oct 15, 2013
Publication date	Aug 11, 2016
Grant date	—

Abstract

A laser welding method of the present invention is a laser welding method for irradiating with a laser beam a groove portion 6 formed along a circumferential direction by butting axial end portions of cylindrical bodies 5 a, 5 b together to weld the groove portion, the method comprising: a welding process S 2 of irradiating the groove portion 6 with the laser beam over the entire circumference to weld the groove portion; and a strain correction process S 4 of irradiating the groove portion 6 with the laser beam over the entire circumference, the laser beam having a heat input amount smaller than a heat input amount per unit area of the laser beam emitted in the welding process S 2.

First claim

1 . A laser welding method for irradiating a groove portion formed along a circumferential direction by butting axial end portions of cylindrical bodies with a laser beam to weld the groove portion, the method comprising:
a welding process of irradiating the groove portion with the laser beam over the entire circumference to weld the groove portion; and a strain correction process of irradiating the groove portion with the laser beam over the entire circumference, wherein the laser beam used in the strain correction process has a heat input amount smaller than a heat input amount per unit area of the laser beam emitted in the welding process.

2 . The laser welding method according to claim 1 , wherein a surface temperature of the groove portion heated by the laser beam in the strain correction process is a temperature at which a residual plastic strain occurs.

3 . The laser welding method according to claim 1 , wherein a surface temperature of the groove portion heated by the laser beam in the strain correction process becomes higher than a temperature at which a residual plastic strain occurs.

4 . The laser welding method according to claim 1 , wherein in the strain correction process, a distance between a focal point of the laser beam and the groove portion is longer than that of the welding process.

5 . The laser welding method according to claim 1 ,
wherein in the welding process, a plastic strain region is formed around the groove portion by irradiating the groove portion with the laser beam, and in the strain correction process, an irradiation width in the axial direction of the laser beam is longer than an irradiation width in the axial direction of the plastic strain region.

6 . A laser welding apparatus comprising:
a holding jig that holds cylindrical bodies in a state of butting axial end portions of the cylindrical bodies together; a laser welding unit that irradiates a groove portion formed along a circumferential direction by butting the axial end portions of the cylindrical bodies with a laser beam; and a control unit that controls the laser welding unit, wherein the control unit controls the laser welding unit to irradiate the groove portion with the laser beam over the entire circumference to weld the groove portion, and to irradiate the groove portion with the laser beam over the entire circumference again after reducing a heat input amount per unit area of the laser beam.

7 . The laser welding apparatus according to claim 6 , wherein the control unit sets a surface temperature of the groove portion heated by the laser beam to a temperature at which a residual plastic strain occurs.

8 . The laser welding apparatus according to claim 6 , wherein the control unit sets a surface temperature of the groove portion heated by the laser beam to be higher than a temperature at which a residual plastic strain occurs.

9 . The laser welding apparatus according to claim 6 , wherein the control unit sets a distance between a focal point of the laser beam and the groove portion after welding to be longer than a distance between the focal point of the laser beam and the groove portion at the time of welding.

10 . The laser welding apparatus according to claim 6 , wherein the control unit forms a plastic strain region around the groove portion by irradiating the groove portion with the laser beam at the time of welding, and the control unit sets an irradiation width in the axial direction of the laser beam to be longer than an axial width of the plastic strain region.

11 . A cylindrical body that is welded by the laser welding method according to claim 1 .

12 . A cylindrical body that is welded using the laser welding apparatus according to claim 6 .

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Kamitani Keisuke
• Tsubota Shuho
• Aoyama Takafumi
• Fujiya Yasuyuki

Classifications

• C21D9/50

  for welded joints · CPC title

• C21D9/08

  for tubular bodies or pipes · CPC title

• B23K37/0538

  for rotating tubes, e.g. rollers · CPC title

• B23K33/006

  for cylindrical workpieces · CPC title

• B23K26/352

  for surface treatment · CPC title