Laser processing apparatus and laser irradiation method
View Patent ↗A laser processing apparatus includes a laser irradiation unit has a structure providing an intensity distribution of the laser beam focused on the grain-oriented electrical steel sheet on a cross-section in a direction perpendicular to the scanning direction on the grain-oriented electrical steel sheet so as to satisfy Ib/Ia≦2, where Ra 1 and Ra 2 are distances between the centroid of the intensity distribution and positions at which the intensity integration value from the centroid of the intensity distribution is 43% of the total intensity integration value, beam intensities Ia 1 and Ia 2 are intensities of the laser beam corresponding to Ra 1 and Ra 2 , respectively, Ia is the average value of Ia 1 and Ia 2 and Ib is the beam intensity at the centroid of the intensity distribution.
1. A laser processing apparatus for reducing a magnetic domain size of a grain-oriented electrical steel sheet by focusing a laser beam on the grain-oriented electrical steel sheet and scanning the grain-oriented electrical steel sheet in a scanning direction with the laser beam, the laser processing apparatus comprising:
a laser oscillator emitting the laser beam; and
a laser irradiation unit applying the laser beam transmitted from the laser oscillator to the grain-oriented electrical steel sheet,
wherein the laser irradiation unit has a structure providing an intensity distribution of the laser beam focused on the grain-oriented electrical steel sheet on a cross-section in a direction perpendicular to the scanning direction on the grain-oriented electrical steel sheet so as to satisfy Ib/Ia≦2, where, when an integral of the intensity distribution is calculated from a centroid of the intensity distribution in each of a first direction and a second direction which are both perpendicular to the scanning direction, Ra 1 is a distance between the centroid of the intensity distribution and a position at which an intensity integration value from the centroid of the intensity distribution in the first direction is 43% of a total intensity integration value, Ra 2 is a distance between the centroid of the intensity distribution and a position at which an intensity integration value from the centroid of the intensity distribution in the second direction is 43% of the total intensity integration value, a beam intensity Ia 1 is an intensity corresponding to the Ra 1 , the beam intensity Ia 2 is an intensity corresponding to the Ra 2 , Ia is an average value of the beam intensity Ia 1 and the beam intensity Ia 2 and Ib is a beam intensity of the laser beam at the centroid of the intensity distribution.
2. The laser processing apparatus according to claim 1 ,
wherein the structure of the laser irradiation unit provides a C direction intensity distribution of the laser beam focused on the grain-oriented electrical steel sheet on a cross-section in the scanning direction on the grain-oriented electrical steel sheet so as to satisfy 1.5≦Id/Ic≦10, where, when an integral of the C direction intensity distribution is calculated from a centroid of the C direction intensity distribution in each of a third direction and a fourth direction which are both along the scanning direction, Rc 1 is a distance between the centroid of the C direction intensity distribution and a position at which an intensity integration value from the centroid of the C direction intensity distribution in the third direction is 43% of a total C direction intensity integration value, Rc 2 is a distance between the centroid of the C direction intensity distribution and a position at which an intensity integration value from the centroid of the C direction intensity distribution in the fourth direction is 43% of the total C direction intensity integration value, a beam intensity Ic 1 is an intensity corresponding to the Rc 1 , a beam intensity Ic 2 is an intensity corresponding the Rc 2 , Ic is an average value of the beam intensity Ic 1 and the beam intensity Ic 2 and Id is a beam intensity of the laser beam at the centroid of the C direction intensity distribution.
3. The laser processing apparatus according to claim 1 ,
wherein the Ib/Ia is within a range of 1.0 to 2.0.
4. The laser processing apparatus according to claim 1 ,
wherein Ra is within a range of 5 μm to 100 μm, where the Ra is an average value of the Ra 1 and the Ra 2 .
5. The laser processing apparatus according to claim 4 ,
wherein the Ra is within a range of 5 μm to 60 μm.
6. The laser processing apparatus according to claim 1 ,
wherein a beam parameter product of the laser beam focused on the grain-oriented electrical steel sheet is within a range of λ/π to 10 mm·mrad, where λ is a wavelength of the laser beam in units of μm.
7. The laser processing apparatus according to claim 1 ,
wherein the laser oscillator is a fiber laser or a disc laser.
8. The laser processing apparatus according to claim 1 ,
wherein a spot shape of the laser beam focused on the grain-oriented electrical steel sheet is an ellipse, and
a short axis direction of the ellipse is perpendicular to the scanning direction.
9. A laser irradiation method comprising a laser irradiation step for reducing a magnetic domain size of a grain-oriented electrical steel sheet by focusing a laser beam on the grain-oriented electrical steel sheet and scanning the grain-oriented electrical steel sheet in a scanning direction with the laser beam,
wherein Ib/Ia is 2.0 or less in an intensity distribution of the laser beam focused on the grain-oriented electrical steel sheet on a cross-section in a direction perpendicular to the scanning direction on the grain-oriented electrical steel sheet, where, when an integral of the intensity distribution is calculated from a centroid of the intensity distribution in each of a first direction and a second direction which are both perpendicular to the scanning direction, Ra 1 is a distance between the centroid of the intensity distribution and a position at which an intensity integration value from the centroid of the intensity distribution in the first direction is 43% of a total intensity integration value, Ra 2 is a distance between the centroid of the intensity distribution and a position at which an intensity integration value from the centroid of the intensity distribution in the second direction is 43% of the total intensity integration value, a beam intensity Ia 1 is an intensity corresponding to the Ra 1 , the beam intensity Ia 2 is an intensity corresponding to the Ra 2 , Ia is an average value of the beam intensity Ia 1 and the beam intensity Ia 2 and Ib is a beam intensity of the laser beam at the centroid of the intensity distribution.
10. The laser irradiation method according to claim 9 ,
wherein Id/Ic falls within a range of 1.5 to 10 in a C direction intensity distribution of the laser beam focused on the grain-oriented electrical steel sheet on a cross-section in the scanning direction on the grain-oriented electrical steel sheet, where, when an integral of the C direction intensity distribution is calculated from a centroid of the C direction intensity distribution in each of a third direction and a fourth direction which are both along the scanning direction, Rc 1 is a distance between the centroid of the C direction intensity distribution and a position at which an intensity integration value from the centroid of the C direction intensity distribution in the third direction is 43% of a total C direction intensity integration value, Rc 2 is a distance between the centroid of the C direction intensity distribution and a position at which an intensity integration value from the centroid of the C direction intensity distribution in the fourth direction is 43% of the total C direction intensity integration value, a beam intensity Ic 1 is an intensity corresponding to the Rc 1 , a beam intensity Ic 2 is an intensity corresponding the Rc 2 , Ic is an average value of the beam intensity Ic 1 and the beam intensity Ic 2 and Id is a beam intensity of the laser beam at the centroid of the C direction intensity distribution.
11. The laser processing apparatus according to claim 1 ,
wherein the laser irradiation unit includes a mirror adjusting the Ib/Ia so as to satisfy Ib/Ia≦2.
12. The laser irradiation method according to claim 9 ,
wherein the Ib/Ia is within a range of 1.0 to 2.0.
13. The laser irradiation method according to claim 9 ,
wherein Ra is within a range of 5 μm to 100 μm where the Ra is an average value of the Ra 1 and the Ra 2 .
14. The laser irradiation method according to claim 13 ,
wherein the Ra is within a range of 5 μm to 60 μm.
15. The laser irradiation method according to claim 9 ,
wherein a spot shape of the laser beam focused on the grain-oriented electrical steel sheet is an ellipse, and
a short axis direction of the ellipse is perpendicular to the scanning direction.
16. The laser processing apparatus according to claim 2 ,
wherein the Ib/Ia is within a range of 1.0 to 2.0.
17. The laser processing apparatus according to claim 2 ,
wherein Ra is within a range of 5 μm to 100 μm, where the Ra is an average value of the Ra 1 and the Ra 2 .
18. The laser processing apparatus according to claim 2 ,
wherein a beam parameter product of the laser beam focused on the grain-oriented electrical steel sheet is within a range of λ/π to 10 mm·mrad, where λ is a wavelength of the laser beam in units of μm.
19. The laser processing apparatus according to claim 2 ,
wherein the laser oscillator is a fiber laser or a disc laser.
20. The laser processing apparatus according to claim 2 ,
wherein a spot shape of the laser beam focused on the grain-oriented electrical steel sheet is an ellipse, and
a short axis direction of the ellipse is perpendicular to the scanning direction.