Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/362—Laser etching
  • B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/16—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of sheets

Definitions

• This disclosure relates to a laser processing device and a laser processing method.
• the manufacturing process for grain-oriented electrical steel sheets mainly consists of hot rolling, cold rolling, primary recrystallization (decarburization) annealing, secondary recrystallization (finishing) annealing, flattening annealing, and coating.
• a magnetic domain control technology has been put into practical use to reduce iron loss by applying linear thermal strain at regular intervals in a direction approximately perpendicular to the rolling direction, i.e., extending in the sheet width direction, to the surface of the grain-oriented electrical steel sheet after the coating process (Patent Document 1).
• a method for improving iron loss by forming grooves using laser irradiation has also been disclosed (Patent Document 2).
• Patent Document 3 a technology has been disclosed in which, after cold rolling and before finish annealing, a localized heated area is formed by irradiating the sheet with a laser in a direction approximately parallel to the sheet width, generating grain boundaries in the area after finish annealing, thereby improving magnetic properties such as reducing iron loss and increasing magnetic flux density (Patent Document 3).
• localized heat treatment is performed by irradiating a steel sheet surface transported in the rolling direction L at a transport speed VL with laser light focused in a thin linear, circular, or elliptical shape in the rolling direction L, while scanning the laser light in the sheet width direction C, which is approximately parallel to the rolling direction, at a speed Vc .
• the laser power is P [W]
• the focused shape is an ellipse
• the major axis diameter in the scanning direction is Dc
• the minor axis diameter which is the focused diameter in the direction perpendicular to the scanning direction is Dl
• the focused area which is the product of Dc and Dl
• Patent Document 1 describes a technique for calculating and setting an inclination angle, which is the angle between the scanning direction of the laser beam and the major axis of the focused beam shape, from the conveying speed V L of the steel sheet and the scanning speed V C of the laser beam.
• the width of the heated area in the rolling direction should ideally be 0.1 mm, equal to the minor axis diameter D L .
• the width of the heated area in the effective rolling direction L becomes approximately 0.2 mm, which is approximately twice the width of the target heated area, i.e., I p is halved.
• the present disclosure aims to provide technology for laser processing the surface of a transported workpiece.
• a laser processing device that processes the surface of a workpiece by irradiating it with laser light
• the laser processing device having an output device that outputs laser light, a focusing device that focuses the laser light into a predetermined focused shape, and a deflection device that moves the irradiation position of the focused laser light on the surface of the workpiece at a moving speed that is the same as the transport speed of the workpiece being transported in a first direction by a transport device.
• a laser processing method for processing the surface of a workpiece by irradiating the workpiece with laser light comprising: a focusing step of focusing the laser light on the workpiece while the workpiece is being transported in a first direction at a predetermined transport speed; and a moving step of moving the irradiation position of the focused laser light on the surface of the workpiece at a moving speed that is the same as the transport speed in the first direction.
• FIG. 1 is a schematic diagram of an example of a laser processing apparatus according to an embodiment of the present invention, viewed from the Z direction (vertical direction).
• FIG. 2 is a schematic view of an example of a laser processing apparatus according to an embodiment of the present invention, viewed from the arrow C direction.
• FIG. 3 is a schematic view of an example of a laser processing device according to an embodiment of the present invention, viewed from the arrow L direction.
• FIG. 4 is a schematic diagram of a heating region according to an embodiment of the present invention.
• FIG. 5 is a schematic diagram showing an example of a laser processing apparatus according to an embodiment of the present invention.
• FIG. 6 is a schematic diagram showing an example of a laser beam deflected by a polygon mirror according to an embodiment of the present invention.
• FIG. 1 is a schematic diagram of an example of a laser processing apparatus according to an embodiment of the present invention, viewed from the Z direction (vertical direction).
• FIG. 2 is a schematic view of an example of
• FIG. 7 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction.
• FIG. 8 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction.
• FIG. 9 is a schematic diagram showing another example of laser light deflected by a polygon mirror according to an embodiment of the present invention.
• FIG. 10 is a schematic view of another example of a laser processing apparatus according to an embodiment of the present invention, viewed from the arrow C direction.
• FIG. 11 is a flow chart showing a laser processing method according to an embodiment of the present invention.
• FIG. 12 is a diagram illustrating laser illumination parameters and polygon mirror parameters for various embodiments of the present disclosure.
• FIG. 12 is a diagram illustrating laser illumination parameters and polygon mirror parameters for various embodiments of the present disclosure.
• FIG. 18 is a schematic view of another example of a laser processing device according to an embodiment of the present invention, viewed from the arrow C direction.
• FIG. 19 is a schematic view of another example of a laser processing apparatus according to an embodiment of the present invention, viewed from the arrow C direction.
• FIG. 20 is a schematic diagram showing two or more laser processing devices according to an embodiment of the present invention arranged in the width direction of a plate.
• FIG. 21 is a schematic diagram showing another example of a laser processing device according to an embodiment of the present invention.
• FIG. 22 is a schematic diagram of another example of a heating region according to an embodiment of the present invention.
• the conveying device 110 conveys the grain-oriented electrical steel sheet 10 at a predetermined conveying speed VL in a conveying direction L perpendicular to the sheet width direction C.
• the conveying device 110 includes a plurality of rollers for moving the grain-oriented electrical steel sheet 10 in the conveying direction L, and by rotating the rollers in the conveying direction L, the grain-oriented electrical steel sheet 10 placed on the rollers is moved in the conveying direction L at a predetermined conveying speed VL .
• the conveying direction L is the same as the rolling direction of the rolled steel sheet.
• the sheet width direction C is a direction perpendicular to the rolling direction of the steel sheet.
• the output device 120 is a device that outputs laser light 20. Specifically, it may be a fiber laser, YAG laser, CO2 laser, etc., and the type of laser is not particularly important as long as it is used for processing.
• the output laser light 20 propagates toward the focusing device 130 and the polygon mirror 140.
• the linear grooves or linear strains are set to extend in a plane parallel to the steel sheet surface in a direction perpendicular to the conveyance direction (sheet width direction C) or in a direction within 45 degrees from the sheet width direction C (0 degrees ⁇ approximately parallel ⁇ 45 degrees).
• the extension direction of the linear grooves or linear strains may be between 0 degrees and 10 degrees relative to the sheet width direction C.
• the focused beam shape can be adjusted using the focusing device 130. That is, the focusing device 130 may form the laser beam 20 in a focused beam shape that is short in a first direction and long in a second direction perpendicular to the first direction.
• the focusing device 130 includes a lens 131 that adjusts a width-direction focused beam diameter D C (i.e., the length of the diameter passing through the intersection of the major axis and minor axis and parallel to the conveying direction L) that is the focused beam diameter in the width direction C of the grain-oriented electrical steel sheet 10, and a lens 132 that adjusts a minor axis diameter D L of the focused beam in the conveying direction L of the grain-oriented electrical steel sheet 10.
• the focused beam shape of the laser beam 20 is adjusted to be an oblong ellipse such that D L ⁇ D C.
• a concave lens may be used as the lens 131 to expand the diameter of the laser beam 20, and Dc may be set to a desired value by adjusting the distance between the lens 131 and the steel sheet.
• a convex lens may be used as the lens 132, and the position of the lens 132 may be adjusted so that the focal position of the lens 132 coincides with the steel sheet surface, thereby setting the minor axis diameter DL to a desired value.
• the polygon mirror 140 has multiple reflecting surfaces and is rotatable about a rotation axis that is parallel to the steel sheet surface and perpendicular to the conveyance direction of the workpiece, specifically, the grain-oriented electrical steel sheet 10 in this embodiment.
• the polygon mirror 140 may also rotate at a rotation speed corresponding to the movement speed of the irradiation position.
• the rotation axis is rotatably supported by a support device (not shown) so that it rotates in a direction that deflects the laser beam 20 incident from one direction by reflection on each reflecting surface of the polygon mirror 140 and moves it in the conveyance direction L.
• the angle of incidence of the laser beam 20 sequentially changes within each reflecting surface, thereby moving the irradiation position of the laser beam 20 on the surface of the grain-oriented electrical steel sheet 10 in the same direction and at the same speed as the conveyance direction L at a movement speed V C that corresponds to the rotation speed.
• the angle of incidence returns to the original, and the irradiation position returns upstream in the conveyance direction L. This is repeated as many times as the number of reflecting surfaces during one rotation of the polygon mirror 140.
• Fig. 6 is a schematic diagram showing the laser light 20 reflected and deflected by the polygon mirror and the irradiation interval P L in the conveying direction.
• Fig. 6 is an enlarged view of the portion shown in A in Fig. 2. Focusing on one surface of the polygon mirror 140, consider a case where the laser light 20 is reflected by the surface. When the polygon mirror 140 is viewed from the sheet width direction C, the boundary between the surface and a surface located ahead of the surface in the rotation direction is defined as vertex A', and the boundary between the surface and a surface located behind the surface in the rotation direction is defined as vertex B'.
• the position on the steel sheet where the reflected laser beam 20 is irradiated is defined as irradiation position I
• the position on the steel sheet where the reflected laser beam 20 is irradiated is defined as irradiation position II.
• the reflection point R where the laser beam 20 is reflected moves from the vertex A' to the vertex B' of the polygon mirror 140, so that the laser beam 20 moves from irradiation position I on the surface of the grain-oriented electrical steel sheet 10 to irradiation position II on the surface of the grain-oriented electrical steel sheet 10.
• the reflected laser beam 20 is again irradiated at irradiation position I, and this operation is repeated. If the moving distance from irradiation position I to irradiation position II on the surface of the grain-oriented electrical steel sheet 10 is defined as the laser irradiation interval PL , then as the polygon mirror 140 rotates, thermally processed areas are formed by laser irradiation at intervals of PL in the conveying direction of the steel sheet.
• ⁇ P 360/N p (4)
• ⁇ P corresponds to 1 ⁇ 2 of the deflection angle of the laser light 20 reflected by the polygon mirror, so if the distance of the perpendicular line from the reflection point R of the polygon mirror to the steel sheet surface is h, then P L is given by equation (5).
• P L 2 ⁇ h ⁇ tan ⁇ P (5)
• the moving speed V C of the irradiation point of the laser beam 20 by the polygon mirror 140 (for example, a specific position such as the center position between the start and end points of the laser beam irradiation positions resulting from the deflection of the laser beam 20 due to a change in the reflection angle of one mirror as the polygon mirror 140 rotates ) on the grain-oriented electrical steel sheet 10 is made the same as the conveying speed V L of the grain-oriented electrical steel sheet 10 by the conveying device 110.
• the speed of movement of the irradiation shape due to the rotation of one of the reflecting surfaces of the polygon mirror 140 slows down from the start point to the center point O and increases from the center point O to the end point.
• the rotation of the polygon mirror 140 causes the deflection of the laser beam 20 due to a change in the reflection angle of one mirror
• the movement speed Vc is defined as the movement speed at the center point O between the start point and the end point of the laser beam irradiation position (hereinafter, also referred to as the irradiation position).
• the moving speed and the transport speed are perfectly matched, but a certain degree of change in power density caused by such a speed difference is acceptable depending on the processing purpose. For example, if the change in power density is within about 10%, it will not affect the purpose of thermal distortion or groove processing.
• the same region is continuously irradiated with the laser beam 20 while it moves at the conveying direction irradiation interval PL on the surface of the grain-oriented electrical steel sheet 10.
• the region hereinafter referred to as the heated region
• the region that is continuously irradiated with the laser beam 20 for the time required for the laser beam 20 to travel at the conveying direction irradiation interval PL forms a linear or dot-series groove or linear distortion having the length of the major axis of the focused shape.
• the repeated movement of the laser beam 20 by each reflecting surface of the polygon mirror 140 switches instantaneously from irradiation position II to irradiation position I, so the interval at which the linear groove or linear distortion is formed can be considered to be equal to the irradiation interval PL in the conveying direction L.
• the heated area refers to the area on the surface of the grain-oriented electrical steel sheet 10 that is irradiated with the focused shape of the laser light 20.
• the polygon mirror 140 has a polygonal cross section depending on the number of faces, with the center of this cross section being the rotation axis RX.
• the direction of rotation is the same as the conveyance direction L of the grain-oriented electrical steel sheet 10, in which the deflection direction of the reflected laser light due to rotation is the same as the conveyance direction L of the grain-oriented electrical steel sheet 10.
• the rotational speed V ⁇ [degrees/sec] of the polygon mirror 140 is controlled so that the moving speed VC at the center point O of the moving distance P L of the laser light 20 moved by the polygon mirror 140 matches the conveyance speed VL of the grain-oriented electrical steel sheet 10 (see FIG. 6 ).
• a rotational speed signal of the motor driving the rollers of the conveyance device 100 is input to a control device (not shown) of the rotary motor of the polygon mirror 140, thereby controlling (e.g., feedback control) the motor rotational speed V rpm of the rotary motor of the polygon mirror 140.
• the rotational speed of the motor and the rotational speed of the polygon mirror 140 do not necessarily need to match, and a rotation speed conversion gear may be inserted between the motor and the polygon mirror 140.
• the gear ratio may be appropriately set to set the rotation speed of the polygon mirror 140 so that the moving speed V C of the irradiation position of the laser light matches the moving speed V L of the workpiece.
• the focused shape formed on the surface of the grain-oriented electrical steel sheet 10 by using the focusing device 130 is maintained substantially constant, while the irradiation position moves in the conveying direction L in accordance with the conveyance of the grain-oriented electrical steel sheet 10.
• the power density IP can be maintained at a desired value during the irradiation time Tt , while irradiating the irradiation position of the grain-oriented electrical steel sheet 10.
• the laser irradiation parameters and the design parameters of the polygon mirror 140 can be set by the following procedure.
• Important parameters for properly forming linear grooves or linear distortions in grain-oriented electrical steel sheet 10 are power density I p , irradiation time T t , and conveyance direction irradiation interval P L .
• the conveyance speed V L of grain-oriented electrical steel sheet 10 is set to a predetermined speed.
• the conveyance direction irradiation interval P L of the grooves or distortions is preferably approximately 3 to 10 mm, and the width of the grooves or distortions in the rolling direction is preferably narrow, so these parameters should be determined in advance. Therefore, the conveyance speed V L, the conveyance direction irradiation interval P L , and the ellipse focusing minor axis diameter D L are set to given fixed parameters.
• Step 1 Laser Irradiation Parameters
• Tt P L /V L [msec] (7)
• Step 2 Polygon Mirror Design Parameters
• the central angle ⁇ P of each facet of the polygon mirror 140 is determined by the following equation (8).
• ⁇ P tan ⁇ 1 (P L /(2 ⁇ h)) [degrees] (8)
• h is the distance from the reflection point R of the polygon mirror 140 to the vertically downward surface of the grain-oriented electrical steel sheet 10.
• h may be finely adjusted so that the number of faces N_P of the polygon mirror 140 is an integer.
• the rotational angular velocity V ⁇ of the polygon mirror 140 is determined by the following equation (9).
• V ⁇ ⁇ P /(T t /1000) [degrees/sec] (9)
• the motor rotation speed V rpm of the polygon mirror 140 is determined by the following equation (10).
• V rpm (V ⁇ /360) ⁇ 60[rpm] (10)
• the number of faces N P of the polygon mirror 140 is determined by the following equation (11).
• N P 360/ ⁇ P (11)
• FIG. 8 is a schematic diagram of the laser beam 20 deflected by the polygon mirror 140 according to an embodiment of the present invention, as viewed from the sheet width direction C.
• FIG. 9 is an enlarged view of portion A in FIG. 8, showing the laser beam 20 represented by its optical axis E.
• This is a schematic diagram of the conveying direction irradiation interval PL according to an embodiment of the present invention.
• the laser power P of the output device 120, the distance h between the reflection point R of the polygon mirror 140 and the grain-oriented electrical steel sheet 10, and the motor rotation speed V rpm of the polygon mirror 140 are changed.
• the conveying direction irradiation interval PL is multiplied by n, as shown in FIG. 9, by multiplying the distance h by n (where n is any number greater than 0) to h', it is possible to make the physical distance of the conveying direction irradiation interval PL n times PL '.
• the position of the focusing device 130 is appropriately adjusted in accordance with the movement of the polygon mirror 140 so as to maintain a constant distance from the focusing device 130 to the grain-oriented electromagnetic steel sheet 10 and prevent focus shift.
• the focusing device 130 is configured, for example, with a concave lens 131 and a convex lens 132 to focus the laser beam 20 linearly, and the distance between these lenses is maintained.
• the distance between the focusing device 130 and the grain-oriented electromagnetic steel sheet 10 is, for example, the distance along the optical axis E from the convex lens 132 to the grain-oriented electromagnetic steel sheet 10, and the position of the focusing device 130 is moved so as to maintain this distance when the polygon mirror 140 is moved.
• the irradiation interval P L in the transport direction L is multiplied by n
• the time during which the heating region is continuously irradiated (laser irradiation time T t ) is multiplied by n.
• the laser power P is set to 1/n in order to maintain a constant power density I p irradiated to the grain-oriented electromagnetic steel sheet 10.
• the moving speed V C of the laser beam 20 becomes n times larger, and therefore, by multiplying the motor rotation speed V rpm by 1/n, the moving speed V C of the laser beam 20 becomes constant with the conveying speed V L.
• a laser irradiation device 100 may include one transport device 110, two output devices 120, two focusing devices 130, and one polygon mirror 140 (deflection device 150), and two laser beams 20 may be incident on the polygon mirror 140 from opposite directions.
• the two output devices 120 irradiate the laser beams 20 toward the corresponding focusing devices 130.
• the interval G between the two laser beams 20 in the movement direction of each irradiation position can be set to satisfy the following formula (12).
• G (m+1/2) ⁇ P L (12)
• m is an integer greater than or equal to 1.
• a method for setting G so as to satisfy equation (12) involves appropriately adjusting the diameter of the polygon mirror 140. According to the embodiment shown in FIG.
• the irradiation interval in the transport direction L of each output device 120 can be set to 2 ⁇ P L.
• the central angle ⁇ P of each face of the polygon mirror 140 doubles, and the number of faces N P of the polygon mirror 140 can be reduced by half, resulting in an advantage of reducing the manufacturing cost of the polygon mirror 140.
• the distance h between the polygon mirror reflection point R and the grain-oriented electromagnetic steel sheet 10 also increases, it is possible to prevent molten material, etc., scattering from the processed portion from adhering to the polygon mirror 140, for example, in the case of groove machining.
• a laser processing method according to an embodiment of the present invention will be described using Fig. 11 as an example in which the object to be processed is a grain-oriented electrical steel sheet 10.
• Fig. 11 is a diagram showing the laser processing method according to an embodiment of the present invention.
• a laser processing apparatus 100 irradiates the surface of the grain-oriented electrical steel sheet 10 with laser light 20 having the above-mentioned elliptically focused shape, thereby forming linear grooves or linear distortions extending in a direction approximately parallel to the sheet width direction C of the grain-oriented electrical steel sheet 10.
• the laser processing method includes a focusing step (S103) and a moving step (S104).
• the laser processing method further includes a preparation step (S101) and a transport step (S102).
• the linear grooves or linear strains are set to extend in a direction approximately perpendicular to the rolling direction (a direction approximately parallel to the plate width direction C). Therefore, the one direction is parallel to the direction in which the linear grooves or linear strains extend.
• step S102 the laser processing apparatus 100 uses the conveying device 110 to convey the grain-oriented electrical steel sheet 10 as the workpiece in a conveying direction L perpendicular to the sheet width direction C at a predetermined conveying speed VL .
• step S103 the laser processing apparatus 100 focuses the laser beam 20 output from the output device 120 onto the grain-oriented electrical steel sheet 10, which is being transported in the transport direction L at a predetermined transport speed VL .
• the laser processing apparatus 100 matches the conveying speed V L of the conveying device 110 with the moving speed V C of the laser beam 20 from the polygon mirror 140.
• the motor rotation speed V rpm of the rotary motor of the polygon mirror 140 is controlled so that the moving speed V C of the laser beam 20 coincides with the conveying speed V L of the grain-oriented electrical steel sheet 10 .
• the laser processing apparatus 100 and laser processing method according to the present invention can stably form thin linear heated regions on the surface of the grain-oriented electrical steel sheet 10 regardless of the length in the major axis direction of the focused shape of the laser beam 20, and can arbitrarily set the interval in the conveyance direction L of the linear grooves or linear distortions (irradiation interval P L in the conveyance direction L) while maintaining a constant conveyance speed V L of the grain-oriented electrical steel sheet 10.
• the deflection device 150 may be provided with a function to adjust the irradiation interval in the conveyance direction L.
• the present invention also allows two output devices 120 to be installed with polygon mirrors 140 facing each other, and the two laser beams 20 to be moved by the polygon mirrors 140.
• the grain-oriented electrical steel sheets 10 were subjected to continuous laser irradiation under the above conditions, and then decarburization annealing, finish annealing, flattening annealing, and coating processes. Thirty grain-oriented electrical steel sheets 10, each measuring 300 mm in the conveying direction and 60 mm in the sheet width direction, were sampled and their magnetic properties were evaluated. The magnetic properties were measured by measuring the iron loss W 17/50 in an alternating magnetic field with a magnetic flux density of 1.7 T and a frequency of 50 Hz, and the magnetic flux density B 8 generated in a magnetic field of 0.8 A/m. The smaller the iron loss W 17/50 and the higher the magnetic flux density B 8 , the better the magnetic properties.
• the magnetic flux density B 8 decreased by 0.02 T compared to the non-laser-irradiated portion, but the iron loss W 17/50 was 0.753 W/kg, meaning that the iron loss was reduced by approximately 10%. Therefore, according to the first embodiment, it is possible to provide a material suitable for a transformer in which iron loss is important.
• Example 2 In Example 2, based on the embodiment described above with reference to Figures 8 and 9, the conveying speed VL of the grain-oriented electrical steel sheet 10 was kept constant, but the conveying direction irradiation interval P L in the conveying direction of the linear heating region was increased from 10 mm to 15 mm. Based on the 1.5-fold increase in the conveying direction irradiation interval P L , the laser power P was set to 1/1.5, the distance h between the reflecting surface of the polygon mirror 140 and the grain-oriented electrical steel sheet 10 was set to 1.5, and the motor rotation speed V rpm of the polygon mirror 140 was set to 1/1.5.
• the position of the focusing device 130 was appropriately adjusted to maintain a constant distance between the focusing device 130 and the grain-oriented electrical steel sheet 10, i.e., to maintain a constant focused beam shape.
• the iron loss W 17/50 increased slightly, but the magnetic flux density B 8 increased. Therefore, according to the second embodiment, it is possible to provide a material suitable for a transformer that places importance on the magnetic flux density B8 .
• Example 3 In Example 3, as in the embodiment described above with reference to FIG. 10 , two output devices 120 were installed facing each other on the upstream and downstream sides of the conveyance direction L, and two laser beams 20 were moved by a single polygon mirror 140.
• the conveyance direction irradiation interval P L between the linear heating areas formed by each laser beam 20 in the conveyance direction L was set to 20 mm, and the interval G between the irradiation points of each laser beam 20 was set to 110 mm, so that the laser beam 20 was irradiated between the linear heating areas formed by the output devices 120.
• the laser power P was 5000 W
• the sheet width direction focused diameter D C was doubled
• the power density I p was halved.
• the conveyance direction irradiation interval P L was set to 20 mm and the irradiation time T t was doubled to 40 msec, so that the reduction in power density was offset and the input energy to the irradiation section was kept the same.
• the number of faces N P of the polygon mirror 140 can be halved, thereby reducing the manufacturing cost of the polygon mirror 140.
• the transport direction irradiation interval P L and other conditions were the same as in Example 1, similar magnetic properties were also obtained.
• the laser processing apparatus 100 irradiates the surface of the workpiece 10 with laser light 20 using a polygon mirror 140, but the laser processing apparatus 100 according to the present disclosure is not necessarily limited to this, and may use a deflection device 150 such as another type of lens.
• a deflection device 150 such as another type of lens.
• One variation is a method in which a galvanometer mirror 151 is used for the deflection device 150 shown in FIG. 13.
• the laser processing apparatus 100 according to this variation is composed of an output device 120, a focusing device 130, a deflection device 150 using a galvanometer mirror 151, and a synchronization device 160.
• the galvanometer mirror 151 is substantially parallel to the surface of the workpiece 10 and has a rotation axis RY perpendicular to the conveyance direction L, and the laser processing apparatus 100 includes a mechanism for repeatedly rotating the galvanometer mirror 151 forward and backward around the rotation axis RY.
• the galvanometer mirror 151 changes its reflection angle in accordance with the moving speed of the irradiation position, so that when the galvanometer mirror 151 rotates forward, the reflected deflection direction of the laser beam 20 coincides with the conveyance direction L of the workpiece 10, and when the galvanometer mirror 151 rotates backward, the reflected deflection direction of the laser beam 20 is opposite to the conveyance direction L.
• the synchronizer 160 adjusts the rotation speed so that when the laser beam is reflected by the forward-rotating galvanometer mirror 151, the moving speed of the laser irradiation position on the workpiece 10 coincides with the conveyance speed VL of the workpiece 10, and generates a signal for controlling (ON/OFF) the output of the laser beam 20 from the output device 120. Similar to the polygon mirror 140 described above, the galvanometer mirror 151 also decelerates from the start point of its forward rotation towards the center of its movement distance and then accelerates from the center towards the end point, but generates a signal to stop the laser output during the deceleration period and during the period when the galvanometer mirror 151 is rotating in the reverse direction. By repeating these steps, the laser irradiation position is matched with the transport speed of the workpiece 10, and heated areas that roughly match the focused shape are formed at regular intervals in the transport direction.
• the deflection device 150 is not limited to the above-mentioned galvanometer mirror 151, but may include any type of deflection mirror that moves the irradiation position in the forward and reverse directions relative to the transport direction L.
• FIGs 14 and 15 show another embodiment of the laser processing apparatus 100 using the deflection device 150 of Figure 13.
• the laser processing apparatus 100 is composed of one output device 120, two sets of laser processing devices 180-1 , 180-2 each consisting of a combination of deflection devices 150-1 , 150-2 using galvanometer mirrors 151-1 , 151-2 and focusing devices 130-1 , 130-2 , a laser beam guiding device 171 for guiding laser light 20 to each of the laser processing devices 180-1 , 180-2 , an optical path switching device 170 for switching the laser output to each of the laser beam guiding devices 171, the two deflection devices 150-1 , 150-2 , the optical path switching device 170, and a synchronization device 160 for controlling the operation of the output device 120.
• the laser processing apparatus 100 when the reflection deflection direction of the laser beam 20 by the galvanometer mirror 151-1 of one laser processing device 180-1 rotates forward, is the same as the conveying direction L of the workpiece 10, and the moving speed of the laser focusing position is the same as the conveying speed of the workpiece 10, the laser beam 20 is guided to that laser processing device 180 by the optical path switching device 170. Meanwhile, the galvanometer mirror 151-2 of the other laser processing device 180-2 rotates in the reverse direction. At the timing when the rotation directions of the two devices switch, the optical path switching device 170 controls so that the laser beam 20 is guided to the other device.
• the optical path switching device 170 may be, for example, as shown in FIG. 16, a rotating reflecting mirror 170 with slits 171 that transmit the laser light 20 and are spaced at regular intervals around its circumference.
• the optical path is switched by the laser light being reflected on the reflecting surface of the rotating reflecting mirror 170 and passing through the slits.
• the synchronizing device 160 synchronizes the timing of the laser output from the output device 120 with the reflection angle of the galvanometer mirror 151.
• the switching timing is determined by controlling the rotation of the motor of the rotating reflecting mirror 170 with the synchronizing device 160.
• any method that can divide the propagation direction of one laser light 20 in time, such as switching the reflection direction of the laser light 20, may be used.
• FIG. 17 is a diagram showing a laser processing apparatus 100 using a reciprocating laser irradiation device 190.
• the laser processing apparatus 100 includes an output device 120, a reciprocating laser irradiation device 190, a synchronization device 160, and a drive mechanism 194.
• the reciprocating laser irradiation device 190 includes a focusing device 130 composed of lenses 191 and 192, and a reflecting mirror 193 as a deflection device 150.
• the drive mechanism 194 moves the reciprocating laser irradiation device 190 back and forth in the conveying direction L parallel to the surface of the workpiece 10 while keeping the relative positional relationship between the lenses 191 and 192 and the reflecting mirror 193 fixed.
• the reciprocating laser irradiation device 190 itself moves in the conveying direction L of the workpiece 10 at a conveying speed VL , and the irradiation position on the surface of the workpiece 10 moves in the conveying direction L at a moving speed Vc that is the same as the conveying speed VL.
• the synchronizer 160 synchronizes the driving of the reciprocating laser irradiation device 190 with the output and stop of the output device 120, outputting laser light from the output device 120 when the reciprocating laser irradiation device 190 moves in the same direction and at the same speed as the conveying direction L of the workpiece 10, and stopping the output from the output device 120 when the reflecting mirror 193 serving as the deflection device 150 moves in the opposite direction to the conveying direction L of the workpiece 10.
• the irradiation position is made to coincide with the conveying speed VL of the grain-oriented electrical steel sheet 10, and heated areas that substantially coincide with the focused shape are formed at regular intervals in the conveying direction L.
• the position and orientation of the reflecting mirror 193 are set so as to reflect the laser light 20 focused by the lenses 191 and 192 serving as the focusing device 130 to a predetermined irradiation position on the surface of the workpiece 10, as shown in FIG.
• the two reciprocating laser irradiation devices 1901 and 1902 operate differently from each other, and the laser beam 20 from the output device 120 is guided by the optical path switching device 170 to one of the reciprocating laser irradiation devices 1901 , which moves in the same direction as the conveying direction L at a moving speed Vc that is the same as the conveying speed VL .
• the other reciprocating laser irradiating device 190-2 moves in the direction opposite to the conveying direction L without irradiating the work-piece 10 with the laser beam 20.
• the optical path switching device 170 controls the laser beam 20 to be directed to the other device.
• the movement directions and timing of the reciprocating laser irradiating devices 190-1 , 190-2 are determined by controlling the drive mechanisms 194-1 , 194-2 using a synchronization signal from the synchronizer 160.
• the laser beam 20 is directed to one of the reciprocating laser irradiating devices 190-1 , 190-2 only when the laser beam 20 is moving in the same direction as the conveying direction L at the same speed.
• the timing to stop the laser output from the output device 120 which is required when there is only one reciprocating laser irradiating device 190 as shown in FIG. 17, becomes unnecessary, and production efficiency can be improved.
• the synchronization device 160 synchronizes the laser output timing from the output device 120 with the reciprocating movements of the reciprocating laser irradiation devices 190 1 and 190 2.
• the deflection device 150 is not limited to the above-described reflection mirror 193, and may include any type of mirror that reciprocates in the transport direction L to change the reflection direction.
• the deflection device 150 may include multiple deflection devices 150 that form multiple laser beams 20 in the plate width direction C.
• multiple laser processing devices 100 already described may be arranged side by side in the width direction of the workpiece 10. In this case, multiple processing regions spaced apart from each other in the width direction of the workpiece 10 are formed.
• the laser processing device 100 in FIG. 20 has polygon mirrors 140-1 to 140-4 as deflection devices 150, but the present invention is not limited to this embodiment.
• the deflection device 150 included in the laser processing device 100 may be any of the deflection devices 150 already described.
• FIG. 21 is a schematic diagram of another example of a laser processing apparatus 100 according to another embodiment of the present invention
• FIG. 22 is a schematic diagram of another example of a heating region according to another embodiment of the present invention.
• the light-focusing shape created by a single polygon mirror 140 may be a dot-array shape.
• Such a light-focusing shape can be achieved by adding, for example, a diffractive optical element 135 that utilizes the well-known diffraction phenomenon to one component of the light-focusing device 130, as shown in FIG. 21.
• the workpiece 10 according to the present disclosure is not limited to grain-oriented electromagnetic steel sheets.
• the workpiece 10 according to the present disclosure may be other electromagnetic steel sheets, or any other steel sheet other than electromagnetic steel sheets.
• the thermal processing according to the present disclosure is not limited to forming grooves on the surface of the workpiece 10 described above.
• the workpiece 10 may be a general steel plate, and the thermal processing according to the present disclosure may be used to make it easier to identify positions, areas, etc. on the steel plate surface.
• the thermal processing according to the present disclosure may be used to make defects detected on the steel plate surface easier to visualize. For example, when a defect is detected on the steel plate surface, a hole may be drilled at that position to make it easier to identify the location of the detected defect. In this way, when illumination light is irradiated onto the steel plate surface, the illumination light passes through the hole, making it easier to identify the location of the detected defect.

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  • 2025-02-07 JP JP2025533288A patent/JP7804248B2/ja active Active
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