JP2018065146A - Laser processing method and laser processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing method capable of flattening properly a surface to be processed, and to provide a laser processing apparatus.SOLUTION: A laser processing method has a flattening step of forming a processed flat surface flattened by processing a projecting part on a surface to be processed by irradiating a pulse laser beam onto the surface to be processed. In the laser processing method, when assuming that a region of the pulse laser beam capable of processing the projecting part on the surface to be processed in the flattening step is an energy sphere, a lower end part L in a laser beam irradiation direction of the energy sphere is positioned to a position for forming the processed flat surface on the surface to be processed.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a laser processing method and a laser processing apparatus.

  Conventionally, there is a laser processing method for processing a processing surface by irradiating a processing surface of the processing object with a laser beam. As a laser processing method, for example, there is a method of irradiating a processing surface of a workpiece with laser light to remove a deposit and flatten the processing surface (for example, Patent Document 1). Further, there are laser processing methods for processing a workpiece with a pulse width of nanoseconds or more (Non-Patent Documents 1 and 2).

JP 2008-119735 A

Temmler A. et al., “Laser Polishing”, Proc. Of SPIE, 2012, Vol. 8243, p. 82430W-1-P. 82430W-13 Vadali M. et al., “Effects of pulse duration on laser micropolishing”, Journal of Micro- and Nano-Manufacturing, March 2013, Vol. 011006-1-1-P. 011006-9

  However, the laser processing method has room for improvement in terms of flattening the processing surface.

  Therefore, the present invention has been made in view of the above, and an object thereof is to provide a laser processing method and a laser processing apparatus capable of appropriately flattening a processing surface.

  In order to solve the above-mentioned problems and achieve the object, the laser processing method according to the present invention is a process in which a processing surface having irregularities is irradiated with laser light to process the projections of the processing surface to be flattened. A flattening step for forming a flat surface, wherein the flattening step is a laser in the laser beam processing region when the laser beam region capable of processing the convex portion of the processing surface is a laser beam processing region. The lower end portion in the light irradiation direction is aligned with a position for forming the processed flat surface on the processed surface.

  In the laser processing method, the flattening step includes at least a length from the upper end to the lower end in the laser light irradiation direction of the laser light processing region that is the maximum of the convex portion of the processing surface before flattening. It is preferable to process the convex portion of the processing surface with the laser beam in the first laser beam processing region that is equal to or less than the height.

  Further, in the laser processing method, the flattening step has a height from the focal position where the beam diameter of the laser light is √2 times the beam diameter of the focal position of the laser light is 2 μm to 72 μm. It is preferable that the convex portion of the processing surface is processed by the laser light in the first laser light processing region.

In the laser processing method, the flattening step includes at least a length from the upper end to the lower end in the laser light irradiation direction of the laser light processing region that is the maximum of the convex portion of the processing surface before flattening. It is preferable to process the convex portion of the surface to be processed by the laser beam in the second laser beam processing region that is larger than the height.

  In the laser processing method, the flattening step may be performed by scanning the laser processing region in the laser beam processing region parallel to an orthogonal direction orthogonal to a scanning direction for flattening the processing surface while scanning along the processing surface. It is preferable to process the convex portion of the processing surface with a laser beam.

  Further, in the laser processing method, the flattening step includes the laser beam processing inclined with respect to an orthogonal direction orthogonal to a scanning direction for flattening the processing surface while scanning along the processing surface. It is preferable to process the convex portion of the surface to be processed by the laser beam in the region.

  Further, in the laser processing method, the flattening step aligns the lower end portion of the second laser beam processing region with a position for forming the processing flat surface on the processing surface, A first processing step of irradiating the processing surface with the laser beam having a laser beam processing region to process a part in the height direction of the convex portion of the processing surface; and after the first processing step, The lower end of one laser beam processing region is aligned with a position for forming the processing flat surface on the processing surface, and the laser beam having the first laser beam processing region is irradiated to the processing surface. And a second processing step of forming the processed flat surface obtained by processing and flattening the remaining portion in the height direction of the convex portion of the surface to be processed.

  Further, in the laser processing method, the planarizing step irradiates the surface to be processed with the laser light having the first laser beam processing region to process a part in the height direction of the convex portion of the surface to be processed. The processing step is repeated a plurality of times, and in the final processing step, the lower end portion of the first laser beam processing region is positioned at a position for forming the processing flat surface on the processing surface. It is preferable that the processed flat surface is formed by combining them.

  Further, a laser processing apparatus according to the present invention controls a laser beam irradiation unit that irradiates a processing surface having irregularities with laser light, and the laser beam irradiation unit, and processes a convex portion of the processing surface to be flat. A control unit that forms a flattened processing flat surface, and the laser light processing region when the laser light region capable of processing the convex portion of the processing surface is a laser light processing region. The lower end portion in the laser beam irradiation direction is aligned with a position for forming the processing flat surface on the processing surface.

  In the laser processing apparatus, at least the length from the upper end portion to the lower end portion in the laser light irradiation direction of the laser light processing region is equal to the maximum height of the convex portion of the processing surface before flattening. The following is preferable.

  In the laser processing apparatus, the first laser beam processing region has a height from the focal position where the beam diameter of the laser beam is √2 times the beam diameter of the focal position of the laser beam is 2 μm to 72 μm. It is preferable.

  In the laser processing apparatus, at least the length from the upper end portion to the lower end portion in the laser light irradiation direction of the laser light processing region of the laser light processing region is greater than the maximum height of the convex portion of the processing surface before flattening. It is preferable.

  In the laser processing apparatus, it is preferable that a laser light irradiation region of the laser light is parallel to an orthogonal direction orthogonal to a scanning direction in which the processing surface is flattened while scanning along the processing surface.

  In the laser processing apparatus, a laser light irradiation region of the laser light is inclined with respect to an orthogonal direction orthogonal to a scanning direction for flattening the processing surface while scanning along the processing surface. preferable.

  Further, the laser processing method according to the present invention includes a planarization step of forming a processed flat surface by irradiating a processed surface having irregularities with a laser beam and processing the convex portion of the processed surface to be flattened, In the planarization step, when the laser beam region capable of processing the convex portion of the processing surface is a laser beam processing region, at least from the upper end to the lower end in the laser beam irradiation direction of the laser beam processing region. You may process the said convex part of the said to-be-processed surface with the said laser beam of the 1st laser beam processing area | region which is equal to or less than the maximum height of the convex part of the said to-be-processed surface before planarization.

  Further, the laser processing method according to the present invention includes a planarization step of forming a processed flat surface by irradiating a processed surface having irregularities with a laser beam and processing the convex portion of the processed surface to be flattened, In the planarization step, when the laser beam region capable of processing the convex portion of the processing surface is a laser beam processing region, at least from the upper end to the lower end in the laser beam irradiation direction of the laser beam processing region. You may process the said convex part of the said to-be-processed surface with the said laser beam of the 2nd laser beam processing area | region larger than the maximum height of the convex part of the said to-be-processed surface before planarization.

  In the laser processing method and the laser processing apparatus according to the present invention, the lower end portion in the laser light irradiation direction of the laser light processing region is aligned with the position for forming the processing flat surface on the processing surface. Can be flattened.

FIG. 1 is a block diagram illustrating a configuration example of a laser processing apparatus according to the first embodiment. FIG. 2 is a diagram illustrating an example of an energy sphere according to the first embodiment. FIG. 3 is a diagram illustrating an example of a temperature rise distribution of the energy sphere according to the first embodiment. FIG. 4 is a diagram illustrating an example of a focal length according to the first embodiment. FIG. 5 is a diagram illustrating an example of an energy sphere according to the first embodiment. FIG. 6 is a diagram illustrating an example of ablation processing by energy density change according to the first embodiment. FIG. 7 is a diagram showing an example of ablation processing by energy density change according to the first embodiment. FIG. 8 is a diagram showing an example of ablation processing by energy density change according to the first embodiment. FIG. 9 is a diagram showing an example of ablation processing by energy density change according to the first embodiment. FIG. 10 is a diagram illustrating an example of forming a processed flat surface according to the first embodiment. FIG. 11 is a flowchart illustrating an operation example of the laser processing apparatus according to the first embodiment. FIG. 12 is a diagram illustrating an example of a focal length according to the second embodiment. FIG. 13 is a diagram illustrating an example of an energy sphere according to the second embodiment. FIG. 14 is a diagram illustrating an example of ablation processing according to the second embodiment. FIG. 15 is a flowchart illustrating an operation example of the laser processing apparatus according to the third embodiment. FIG. 16 is a diagram illustrating an irradiation example of energy spheres according to the fourth embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment 1
A laser processing method and a laser processing apparatus according to Embodiment 1 will be described. The laser processing method is a method of processing the processing surface Wa by irradiating the processing surface Wa of the workpiece W with pulsed laser light LB as laser light. In the laser processing method, a processing flat surface W1 (see FIG. 10) is formed by irradiating a processing surface Wa having irregularities with a pulsed laser beam LB and processing the convex portion P of the processing surface Wa to make it flat (smooth). . Here, the workpiece W is formed of, for example, a metal material. Hereinafter, the laser processing method and the laser processing apparatus will be described in detail.

  In the following description, the first direction (X direction), the second direction (Y direction), and the third direction (Z direction) are orthogonal directions. The first direction and the second direction are directions orthogonal to each other on a placement surface 81b on which a workpiece W to be described later is placed. The third direction is a direction orthogonal to the placement surface 81b. Note that the first direction and the second direction are typically directions orthogonal to each other on the virtual plane when a plane orthogonal to the thickness direction of the workpiece W is a virtual plane, and the third direction is The direction is orthogonal to the virtual plane.

  The laser processing apparatus 1 is an apparatus for performing a laser processing method, and processes the workpiece W by irradiating the workpiece W with pulsed laser light LB. For example, the laser processing apparatus 1 fixes the focal point of the pulsed laser beam LB and focuses the pulsed laser beam LB on the processing surface Wa of the workpiece W for processing. As shown in FIG. 1, the laser processing apparatus 1 includes a laser beam irradiation unit 10, a shutter 20, an attenuator 30, a beam expander 40, a beam transmission optical system 50, an episcopic optical system 60, and an objective lens 70. A drive unit 80, a lamp illumination 90, a camera 100, and a control unit 110.

The laser beam irradiation unit 10 is a laser beam oscillator that oscillates a pulsed output (pulsed laser beam) at a constant repetition frequency. For example, the laser beam irradiation unit 10 is a master oscillator output amplifier (MOPA) using a pulse width variable light source as a seed light source. When the laser beam irradiation unit 10 uses MOPA, an example of output characteristics of the pulsed laser beam LB is as follows. That is, the operating wavelength of the pulse laser beam LB is about 1030 nm ± 1 nm, the repetition frequency is about 1 kHz to 1 MHz, the pulse width is about 50 ps to 1 ns, and the output power is about 10 W or more. The polarization is a straight line, the beam quality square (M ² ) is less than 1.4, and the roundness is more than 80%. The laser beam irradiation unit 10 outputs (emits) the pulsed laser beam LB to the shutter 20. The pulse width is the time interval between the rising edge and the falling edge at a point that is half the peak power of the pulse laser beam LB.

  The shutter 20 switches between transmission and blocking of the pulse laser beam LB. The shutter 20 is installed between the laser beam irradiation unit 10 and the attenuator 30, and transmits or blocks the pulse laser beam LB output from the laser beam irradiation unit 10. The shutter 20 outputs the transmitted pulsed laser beam LB to the attenuator 30.

  The attenuator 30 is an attenuator that adjusts the intensity of the pulse laser beam LB. The attenuator 30 is installed between the shutter 20 and the beam expander 40, adjusts the intensity of the pulsed laser light LB output from the shutter 20, and outputs it to the beam expander 40.

  The beam expander 40 widens the beam diameter of the pulse laser beam LB. The beam expander 40 is installed between the attenuator 30 and the beam transmission optical system 50, widens the beam diameter of the pulse laser beam LB output from the attenuator 30, and outputs it to the beam transmission optical system 50.

  The beam transmission optical system 50 is an optical system including a light guide mirror that guides the pulse laser beam LB. The beam transmission optical system 50 is installed between the beam expander 40 and the epi-illumination optical system 60, guides the pulse laser beam LB output from the beam expander 40, and outputs it to the epi-illumination optical system 60.

  The epi-illumination optical system 60 is an optical system including a direction change mirror that changes the direction in which the pulse laser beam LB travels. The epi-illumination optical system 60 is installed between the beam transmission optical system 50 and the objective lens 70, changes the traveling direction of the pulsed laser light LB output from the beam transmission optical system 50, and outputs it to the objective lens 70.

  The objective lens 70 collects the pulse laser beam LB and irradiates the workpiece surface Wa of the workpiece W with the pulse laser beam LB. The objective lens 70 is installed between the epi-illumination optical system 60 and the drive unit 80, collects the pulsed laser light LB output from the epi-illumination optical system 60, and the workpiece W placed on the drive unit 80. The processing surface Wa is irradiated with pulsed laser light LB.

  The drive unit 80 holds the workpiece W and moves the workpiece W relative to the objective lens 70. The drive unit 80 includes an XY axis drive unit 81 and a Z axis drive unit 82. The XY-axis drive unit 81 includes a flat plate-like mounting table 81a as a mounting unit, a fixing unit (not shown), and an XY-axis driving mechanism (not shown) configured by a ball screw or the like. The XY-axis driving unit 81 fixes the workpiece W to the mounting surface 81b of the mounting table 81a by the fixing unit, and the workpiece W is relative to the objective lens 70 in the X direction or the Y direction by the XY axis driving mechanism. Move. The Z-axis drive unit 82 includes a Z-axis drive mechanism (not shown) composed of a ball screw or the like, and moves the workpiece W relative to the objective lens 70 in the Z direction by the Z-axis drive mechanism.

  The lamp illumination 90 illuminates the workpiece W with illumination. The lamp illumination 90 is installed, for example, facing the placement surface 81b of the drive unit 80, and illuminates the workpiece W placed on the placement surface 81b.

  The camera 100 images the workpiece W. The camera 100 is installed to face the mounting surface 81b of the drive unit 80, and images the unevenness of the processing surface Wa of the workpiece W mounted on the mounting surface 81b. The camera 100 outputs the captured image to the control unit 110.

  The control unit 110 controls the laser processing apparatus 1. The control unit 110 includes an electronic circuit mainly composed of a well-known microcomputer including a CPU, a ROM that constitutes a storage unit, a RAM, and an interface. The control unit 110 controls the optical system such as the laser beam irradiation unit 10 and the shutter 20 and adjusts the output of the pulse laser beam LB.

  Next, the energy sphere E of the pulse laser beam LB irradiated by the laser processing apparatus 1 will be described with reference to FIGS. The energy sphere E is a first laser beam processing region, and is a region of the pulse laser beam LB that can process the convex portion P of the processing surface Wa (see FIG. 2). That is, the energy sphere E is a portion that can actually cut the convex portion P in the pulse laser beam LB irradiated to the convex portion P of the processing surface Wa. Here, the convex portion P of the processing surface Wa is a portion protruding in the Z direction with reference to the deepest portion of the processing surface Wa (the bottom of the concave portion Q) (see FIG. 5). The energy sphere E is parallel to the orthogonal direction (Z direction) orthogonal to the scanning direction of scanning along the workpiece surface Wa. That is, the energy sphere E is parallel to the thickness direction of the workpiece W. In the energy sphere E, at least the length from the upper end H to the lower end L in the laser light irradiation direction (Z direction) of the energy sphere E is the maximum height of the convex portion P of the processing surface Wa before flattening. It is equal to or less than ha (see FIG. 5). The length from the upper end H to the lower end L in the laser irradiation direction (Z direction) of the energy sphere E is also referred to as the size of the energy sphere E. The size of the energy sphere E can be changed by setting the optical system such as the objective lens 70 or setting the energy density irradiated from the laser light irradiation unit 10. As shown in FIG. 2, the energy sphere E is formed to extend from the focal position K of the pulsed laser beam LB to the same extent on the one side and the other side in the laser beam irradiation direction. In the left side view of FIG. 2, the vertical axis is the coordinate in the laser light irradiation direction (Z direction), and the horizontal axis is the coordinate in the X direction. Moreover, the right side view of FIG. 2 shows the energy density. As shown in FIGS. 2 and 3, the energy sphere E has the highest energy density at the focal position K, and the energy density decreases as the distance from the focal position K increases.

Next, an example in which the size of the energy sphere E is adjusted by an optical system such as the objective lens 70 will be described. The height h of the energy sphere E is obtained by the following (Formula 1). In Equation 1, λ is a wavelength, f is a focal length, M ² is a beam quality, and D is a beam diameter before lens focusing.

  For example, the size of the energy sphere E is adjusted by changing the focal length f. The energy sphere E has, for example, a focal length f of about 5 mm to 30 mm. In this case, the energy sphere E has a height h2 from the focal position K at which the beam diameter of the pulsed laser light LB becomes √2 times the beam diameter D of the focal position K of the pulsed laser light LB according to (Equation 1) described above. Is about 2 μm to 72 μm (see FIG. 4). Preferably, the energy sphere E has a focal length f of 20 mm. In this case, the energy sphere E has a height h2 from the focal position K at which the beam diameter of the pulsed laser light LB becomes √2 times the beam diameter D of the focal position K of the pulsed laser light LB according to (Equation 1) described above. Is 32 μm. In this case, as shown in FIG. 5, in the energy sphere E, the maximum height of the convex portion P of the processing surface Wa is about 50 μm, whereas the size of the energy sphere E is about 20 μm. Is smaller than the maximum height (50 μm) of the convex portion P of the processing surface Wa. Thereby, the energy sphere E has selectivity with respect to the height direction (Z direction) of the convex portion P of the workpiece surface Wa, and can selectively cut (ablate) the convex portion P. Here, the ablation processing is removal processing performed by instantaneously evaporating and scattering a portion irradiated with the pulse laser beam LB. Ablation processing is processing in which the processing portion is instantly evaporated, scattered, and removed, so that there is little thermal influence on the periphery of the processing portion and little thermal damage. Further, when the energy sphere E cuts the convex portion P of the work surface Wa, the energy sphere E can be easily aligned with the convex portion P because the size of the energy sphere E is smaller than the convex portion P. it can. In addition, since the energy sphere E has a small size, the energy density is relatively high and cutting accuracy is improved.

Next, an example in which the size of the energy sphere E is adjusted by the energy density irradiated by the laser beam irradiation unit 10 will be described. In the energy sphere E, when the energy density of the pulse laser beam LB is relatively increased, the size of the energy sphere E is relatively increased. For example, as shown in FIG. 6, when the energy density of the energy sphere E is 1.0 J / cm ² , the cutting amount for cutting the convex portion P of the work surface Wa is about 7 μm. In the energy sphere E, for example, the focal position K is set to a position equivalent to the tip position of the convex portion P of the processing surface Wa before flattening. In FIG. 6, the vertical axis represents the height (μm) of the convex portion P of the processing surface Wa, and the horizontal axis represents the distance (mm) in the plane direction.

In addition, as shown in FIG. 7, when the energy density is 3.8 J / cm ² , the energy sphere E is larger than the size of the energy sphere E in FIG. 6, and the convex portion P of the work surface Wa is cut. The cutting amount to be performed is about 12 μm. Further, as shown in FIG. 8, when the energy density is 7.5 J / cm ² , the energy sphere E becomes larger than the size of the energy sphere E in FIG. 7, and the convex portion P of the work surface Wa is cut. The cutting amount to be performed is about 18 μm. Further, as shown in FIG. 9, when the energy density is 10.5 J / cm ² , the energy sphere E is larger than the size of the energy sphere E in FIG. 8, and the convex portion P of the work surface Wa is cut. The cutting amount to be performed is about 22 μm. Thus, the energy sphere E can change the size of the energy sphere E by changing the energy density. 7 to 9, the vertical axis represents the height (μm) of the convex portion P of the processing surface Wa, and the horizontal axis represents the distance (mm) in the plane direction.

  Next, an operation example of the laser processing apparatus 1 will be described with reference to FIG. In the laser processing apparatus 1, processing conditions are set in advance by an operator (step S1). Here, the processing conditions are, for example, the energy density of the pulse laser beam LB, the overlap of spot diameters during scanning, the number of repeated irradiations, the processing time, and the like. These processing conditions are obtained in advance by experiments based on the material of the workpiece W, the roughness of the unevenness of the processing surface Wa, and the like. As the processing conditions, the energy density of the pulse laser beam LB irradiated from the laser beam irradiation unit 10 is set, so that the size of the energy sphere E is set according to the energy density as described above, and the cutting with the energy sphere E is performed. The amount is set.

  The laser processing apparatus 1 performs a flattening process after the processing conditions are set (step S2). For example, the laser processing apparatus 1 first drives the workpiece W placed on the mounting table 81a of the drive unit 80 by the drive unit 80 to move the workpiece W to the machining start position. And the laser processing apparatus 1 images the unevenness | corrugation of the to-be-processed surface Wa of the to-be-processed object W with the camera 100, and moves the to-be-processed object W to the X direction or the Y direction by the XY-axis drive part 81 based on the imaged image. The projection P of the processing surface Wa is irradiated with the energy sphere E of the pulse laser beam LB and scanned, and a part of the projection P in the height direction is cut over the entire processing surface Wa. (Processing process). Next, the laser processing apparatus 1 determines whether or not the cutting process has been completed over the entire surface Wa and the flattening process for forming the processed flat surface W1 (see FIG. 10) has been completed (step S3). ). If the laser processing apparatus 1 determines that the flattening process for forming the processed flat surface W1 is not completed (step S3; No), the laser processing apparatus 1 returns to the above-described step S2, and the laser processing apparatus 1 uses the camera 100 to process the workpiece. The unevenness of the work surface Wa of W is imaged, and the work W is moved in the Z direction by the Z-axis drive unit 82 based on the captured image, and the work W is made according to the cutting amount of the work surface Wa. Set to desired height. And the laser processing apparatus 1 implements the above-mentioned processing process again. In the final processing step, the laser processing apparatus 1 aligns the lower end L of the energy sphere E in the laser light irradiation direction with the position for forming the processing flat surface W1 on the processing surface Wa, and the processing flat surface W1. (See FIG. 10). If the laser processing apparatus 1 determines that the flattening step for forming the processed flat surface W1 has been completed (step S3; Yes), the process ends.

  As described above, in the laser processing method according to the first embodiment, the processing surface Wa is irradiated with the pulsed laser light LB to process the convex portion P of the processing surface Wa to form a processing flat surface W1 that is flattened. It has a conversion process. Then, in the laser processing method, when the region of the pulse laser beam LB that can process the convex portion P of the processing surface Wa in the planarization step is an energy sphere E, the lower end portion L of the energy sphere E in the laser light irradiation direction is changed. The processing target surface Wa is aligned with a position for forming the processing flat surface W1. The laser processing apparatus 1 is an apparatus that performs a planarization process. Thereby, the laser processing method and the laser processing apparatus 1 grasp the position of the lower end L of the energy sphere E and adjust the position of the lower end L, thereby easily adjusting the convex portion P to a desired height. be able to. Therefore, since the laser processing method and the laser processing apparatus 1 can cut the convex portion P of the processing surface Wa in alignment with the target processing flat surface W1, the processing surface Wa can be appropriately flattened. it can. Further, the laser processing method and the laser processing apparatus 1 have a pulse width of about 50 ps to 1 ns, and do not process the workpiece W with a pulse width exceeding nanoseconds as in the related art. Thereby, the laser processing method and the laser processing apparatus 1 can flatten the relatively large convex part P, and can suppress the thermal influence to the inside of the material of the workpiece W. Further, the laser processing method and the laser processing apparatus 1 can reduce the thermal influence on the workpiece W because it is not necessary to consider contact resistance or the like, as compared with conventional machining using a milling machine. This makes it possible to obtain a machined shape that does not have an adverse effect such as deformation or waviness of the workpiece W. In addition, the laser processing method and the laser processing apparatus 1 can perform selective processing with a smaller area or processing with a more complicated shape compared to machining. In addition, the laser processing method and the laser processing apparatus 1 can perform processing independent of the hardness of the workpiece W as compared with machining, and can reduce the number of consumables that are periodically replaced. Further, the laser processing method and the laser processing apparatus 1 can perform processing in a state where the cleanliness in the processing apparatus is maintained by sucking processing waste with a fume collector (not shown).

  Further, in the laser processing method, the flattening step has a length from the upper end H to the lower end L of the energy sphere E in the laser light irradiation direction at least the maximum height of the convex portion P of the processing surface Wa before flattening. The convex portion P of the processing surface Wa is processed by the pulse laser beam LB of the energy sphere E that is equal to or less than the above. Thereby, the laser processing method and the laser processing apparatus 1 can make the energy change of the energy sphere edge part (lower end part L) steep by making the energy sphere E relatively small, and the energy sphere E The convex part P of the processing surface Wa can be cut more sharply. Therefore, the laser processing method can flatten the processing surface Wa with high accuracy. For example, in the laser processing method, the surface roughness (unevenness) Ra of the processing surface Wa can be made submicron or less. The surface roughness Ra is a value obtained by a known mathematical formula, and is an arithmetic average roughness as an example, but may be other than this. In the laser processing method, the cutting amount can be arbitrarily changed in units of microns by changing the energy density irradiated from the laser light irradiation unit 10, the focal length f (defocus amount), and the repetition frequency. Moreover, the laser processing method can suppress energy consumption by processing with smaller energy.

  In the laser processing method, the flattening step has a height from 2 μm to 72 μm from the focal position K at which the beam diameter of the pulse laser beam LB becomes √2 times the beam diameter D of the focal position K of the pulse laser beam LB. The convex portion P of the processing surface Wa is processed by the pulse laser beam LB of a certain energy sphere E. Thereby, the laser processing method can make the size of the energy sphere E smaller than the height of the convex portion P of the processing surface Wa. Therefore, in the laser processing method, the energy density of the energy sphere E is relatively high, and the convex portion P of the processing surface Wa can be cut sharply. In the laser processing method, the energy sphere E has selectivity with respect to the height direction of the convex portion P of the surface Wa to be processed, and only an unnecessary portion of the convex portion P can be selectively cut. Further, in the laser processing method, since the size of the energy sphere E is small, it is easy to align the energy sphere E in the height direction of the convex portion P.

  In the laser processing method, the flattening step is performed by the pulse laser beam LB of the energy sphere E that is parallel to the orthogonal direction orthogonal to the scanning direction for flattening the processing surface Wa while scanning along the processing surface Wa. The convex portion P of the work surface Wa is processed. Thereby, the laser processing method can cut the convex part P of the to-be-processed surface Wa more sharply by the edge part (lower end part L) of the energy ball | bowl E with a sharp energy change. Accordingly, the laser processing method can further flatten the processing surface Wa.

  In the laser processing method, the flattening step is a processing step of irradiating the processing surface Wa with the pulse laser beam LB having the energy sphere E to process a part of the convex portion P of the processing surface Wa in the height direction. In the final processing step, the lower end portion L of the energy sphere E is aligned with the position for forming the processing flat surface W1 on the processing surface Wa, and the processing flat surface W1 Form. Thereby, the laser processing method can flatten the to-be-processed surface Wa with high precision by scanning the relatively small energy sphere E a plurality of times.

[Embodiment 2]
Next, a laser processing method according to the second embodiment will be described. The energy sphere E1 (see FIG. 13) as the second laser beam processing region according to the second embodiment is an example in which the focal length f is 30 mm. In this case, the energy sphere E1 has a height h1 from the focal position K at which the beam diameter of the pulsed laser light LB becomes √2 times the beam diameter D of the focal position K of the pulsed laser light LB according to (Equation 1) described above. Is 71.82 μm (see FIG. 12). As shown in FIG. 13, in the energy sphere E1, the maximum height of the convex portion P of the processing surface Wa is about 50 μm, whereas the size of the energy sphere E1 is about 72 μm, and the size of the energy sphere E1 is flat. It is larger than the maximum height of the convex portion P of the processing surface Wa before conversion. Thereby, the energy sphere E1 can cut most part in the height direction of the convex part P of the to-be-processed surface Wa at once. The upper limit size of the energy sphere E1 is smaller than 10 times the height of the convex portion P of the processing surface Wa. Preferably, the upper limit size of the energy sphere E1 is smaller than the equivalent height to twice the height of the convex portion P of the work surface Wa.

  The energy sphere E1 is parallel to the orthogonal direction (Z direction) orthogonal to the scanning direction of scanning along the workpiece surface Wa. That is, the energy sphere E1 is parallel to the thickness direction of the workpiece W. In the energy sphere E1, when the energy density of the pulse laser beam LB is relatively increased, the size of the energy sphere E1 is relatively increased. As shown in FIG. 14, the laser processing apparatus 1 appropriately adjusts the focal position K and the energy density irradiated from the laser light irradiation unit 10 with respect to the convex portion P of the processing surface Wa to form the energy sphere E1. To do. In the example shown in FIG. 14, the laser processing apparatus 1 sets the focal position K to a position where the Z coordinate is about 70 μm, and sets the position of the lower end L of the energy sphere E to a position where the Z coordinate is about 0 μm. . That is, the laser processing apparatus 1 aligns the position of the lower end portion L of the energy sphere E with the position for forming the processing flat surface W1 on the processing surface Wa. In this example, the laser processing apparatus 1 cuts the convex portion P of the processing surface Wa by one scan, and the maximum height Ry of the convex portion P of the processing surface Wa before processing is 50 μm to 60 μm. However, the maximum height Ry of the convex portion P of the processed surface Wa after processing was 7.6 μm. Since the size of the energy sphere E1 is larger than the size of the energy sphere E of the first embodiment and the energy density is high, the laser processing apparatus 1 can shorten the processing time. Further, the laser processing apparatus 1 can easily adjust the convex portion P to a desired height by grasping the position of the lower end portion L of the energy sphere E1 and adjusting the position of the lower end portion L. The processing surface Wa can be flattened. In FIG. 14, the vertical axis represents the Z coordinate (μm) and the horizontal axis represents the X coordinate (μm). FIG. 14 shows an example in which the convex portion P of the work surface Wa is cut by the energy sphere E1 so that the X coordinate is in a range of about 2000 μm to 4000 μm.

  As described above, in the laser processing method according to the second embodiment, in the flattening step, at least the length Wa from the upper end H to the lower end L in the laser beam irradiation direction of the energy sphere E1 is the processed surface Wa before flattening. The convex portion P of the processing surface Wa is processed by the pulse laser beam LB of the energy sphere E1 which is larger than the maximum height of the convex portion P of the workpiece. Thereby, the laser processing method according to the second embodiment can cut more convex portions P of the surface Wa to be processed, and can shorten the cutting time.

[Embodiment 3]
Further, the laser processing method and the laser processing apparatus 1 according to the third embodiment include an energy sphere E1 larger than the convex portion P of the processing surface Wa and an energy sphere E equal to or less than the convex portion P of the processing surface Wa. In combination, the convex portion P of the work surface Wa is cut. For example, as shown in FIG. 15, in the laser processing apparatus 1, processing conditions are set in advance by an operator (step S11). Here, the processing conditions are, for example, the energy density of the pulse laser beam LB, the overlap of spot diameters during scanning, the number of repeated irradiations, the processing time, and the like. Next, the laser processing apparatus 1 performs a first processing step using a relatively large energy sphere E1 (step S12). For example, the laser processing apparatus 1 first drives the workpiece W placed on the mounting table 81a of the drive unit 80 by the drive unit 80 to move the workpiece W to the machining start position. At this time, the laser processing apparatus 1 aligns the position of the lower end L of the energy sphere E1 with the position for forming the processing flat surface W1 on the processing surface Wa. And the laser processing apparatus 1 images the unevenness | corrugation of the to-be-processed surface Wa of the to-be-processed object W with the camera 100, and moves the to-be-processed object W to the X direction or the Y direction by the XY-axis drive part 81 based on the imaged image. The projection P of the processing surface Wa is irradiated with a relatively large energy sphere E1 of the pulse laser beam LB and scanned, and a part of the projection P in the height direction is spread over the entire processing surface Wa. Cut across. Thus, since the laser processing apparatus 1 cuts a part of the convex part P of the processing surface Wa using the energy sphere E1 larger than the size of the energy sphere E, the processing surface Wa is roughly flattened. Processing time can be shortened.

  Next, the laser processing apparatus 1 determines whether or not the first processing step is completed (step S13). When the laser processing apparatus 1 determines that the first processing process is completed (step S13; Yes), the laser processing apparatus 1 performs a second processing process using a relatively small energy ball E (step S14). For example, the laser processing apparatus 1 drives the workpiece W placed on the mounting table 81a of the drive unit 80 by the drive unit 80, and moves the workpiece W to the machining start position. At this time, the laser processing apparatus 1 aligns the position of the lower end L of the energy sphere E with the position for forming the processing flat surface W1 on the processing surface Wa. And the laser processing apparatus 1 images the unevenness | corrugation of the to-be-processed surface Wa of the to-be-processed object W with the camera 100, and moves the to-be-processed object W to the X direction or the Y direction by the XY-axis drive part 81 based on the imaged image. The remaining portion in the height direction of the convex portion P is scanned on the entire surface of the processing surface Wa while irradiating and scanning the convex portion P of the processing surface Wa with a relatively small energy sphere E of the pulse laser beam LB. Then, the processed flat surface W1 is formed by flattening. Thus, since the laser processing apparatus 1 cuts the remaining part of the convex part P of the to-be-processed surface Wa with the relatively small energy ball | bowl E, it can cut the convex part P of the to-be-processed surface Wa sharper. It is possible to form a flattened processed flat surface W1. Next, the laser processing apparatus 1 determines whether or not the second processing step for forming the processing flat surface W1 has been completed (step S15). If the laser processing apparatus 1 determines that the second processing step for forming the processing flat surface W1 has ended (step S15; Yes), the processing ends. Moreover, if the laser processing apparatus 1 determines with the 2nd process process not being complete | finished (step S15; No), it will return to step S14 and will implement a 2nd process process. In addition, if it determines with the laser beam machining apparatus 1 not having complete | finished the 1st process process by the above-mentioned step S13 (step S13; No), it will return to step S12 and will implement a 1st process process.

  As described above, in the laser processing method and the laser processing apparatus 1 according to the third embodiment, the flattening step is performed such that the lower end portion L of the energy sphere E1 is positioned at the position for forming the processing flat surface W1 on the processing surface Wa. A first processing step of performing a matching process, irradiating the processing surface Wa with the pulsed laser beam LB having the energy sphere E1, and processing a part in the height direction of the convex portion P of the processing surface Wa; After the process, the lower end L of the energy sphere E is aligned with the position for forming the processing flat surface W1 on the processing surface Wa, and the processing surface Wa is irradiated with the pulse laser beam LB having the energy sphere E. And a second processing step of forming a processed flat surface W1 obtained by processing and flattening the remaining portion in the height direction of the convex portion P of the processing surface Wa.

  As described above, the laser processing method and the laser processing apparatus 1 according to the third embodiment cut the most part of the convex portion P of the processing surface Wa with the relatively large energy sphere E1, and then the relatively small energy sphere. Since the processed flat surface W1 obtained by cutting and flattening the remaining portion of the convex portion P of the processing surface Wa is formed by E, the cutting time can be shortened and the processed flat surface W1 can be further flattened. .

[Embodiment 4]
Next, a laser processing method according to Embodiment 4 will be described. The laser processing method according to the fourth embodiment is different from the laser processing method according to the first embodiment in that the laser beam irradiation direction of the energy sphere E is different. In the laser processing method according to the fourth embodiment, the energy sphere E2 of the pulsed laser beam LB is inclined with respect to the orthogonal direction orthogonal to the scanning direction of scanning along the processing surface Wa. That is, the energy sphere E2 of the pulse laser beam LB is inclined with respect to the thickness direction (Z direction) of the workpiece W (see FIG. 16). Further, the laser beam irradiation direction of the energy sphere E2 is not irradiated along the orthogonal direction (Z direction) as in the laser beam irradiation direction of the energy sphere E of the first embodiment, but with respect to the orthogonal direction (Z direction). Intersect. Thereby, in the laser processing method according to the fourth embodiment, the projecting portion P of the processing surface Wa is made more by using the steep energy change portion in the short axis direction of the energy sphere where the energy density of the energy sphere E2 is steeply changed. It can cut sharply and can improve smoothness. That is, in the laser processing method according to the fourth embodiment, the edge of the energy sphere E2 is sharper near the focal position K than the lower end L, and the convex portion P can be cut by the energy sphere E2 near the focal position K. it can. Therefore, in the laser processing method according to the fourth embodiment, it is difficult to irradiate the processing surface Wa with a portion where the energy density of the energy sphere E2 is relatively low (for example, near the lower end L of the energy sphere E2). As compared with the energy sphere E irradiated in the vertical direction (Z direction), the thermal effect on the workpiece W can be suppressed.

  The laser processing method and the laser processing apparatus 1 may be flattened by melt processing or the like in addition to the ablation processing. For example, the laser processing method and the laser processing apparatus 1 melt the convex portion P of the processing surface Wa by the energy sphere E and flatten the processing surface Wa.

  The pulsed laser beam LB may be a continuous wave laser beam that continuously oscillates a constant output. That is, the pulse laser beam LB may form energy spheres E (E1, E2) in the continuous wave laser beam. In this case, the pulsed laser beam LB forms a processed flat surface W1 by melting the convex portion P of the processing surface Wa with a continuous wave laser beam.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 10 Laser beam irradiation part 81a Mounting stand (mounting part)
110 Controllers E, E1, E2 Energy sphere D Beam diameter LB Pulse laser beam (laser beam)
K Focus position P Convex part Q Concave part H Upper end part L Lower end part Work piece Wa Work surface W1 Work flat surface ha, h, h1, h2 Height

Claims (9)

A flattening step of forming a processed flat surface by irradiating a processed surface having irregularities with a laser beam and processing the convex portion of the processed surface to be flattened;
The planarization step includes
When the laser beam region that can process the convex portion of the processing surface is a laser beam processing region, the processing flat surface is formed on the processing surface at the lower end portion in the laser beam irradiation direction of the laser beam processing region. A laser processing method characterized by aligning with a position to be performed. The planarization step includes
At least the length of the laser beam processing region in the laser beam irradiation direction from the upper end portion to the lower end portion is equal to or less than the maximum height of the convex portion of the processing surface before flattening. The laser processing method according to claim 1, wherein the convex portion of the processing surface is processed by laser light. The planarization step includes
The laser beam in the first laser beam machining region having a height of 2 μm to 72 μm from the focal position where the beam diameter of the laser beam is √2 times the beam diameter of the focal position of the laser beam. The laser processing method of Claim 2 which processes the said convex part of a surface. The planarization step includes
At least the length from the upper end to the lower end in the laser beam irradiation direction of the laser beam processing region is greater than the maximum height of the convex portion of the processing surface before flattening by the laser beam in the second laser beam processing region. The laser processing method of any one of Claims 1-3 which process the said convex part of the said to-be-processed surface. The planarization step includes
The convex portion of the processing surface is processed by the laser beam in the laser beam processing region that is parallel to an orthogonal direction orthogonal to a scanning direction for flattening the processing surface while scanning along the processing surface. The laser processing method of any one of Claims 1-4. The planarization step includes
The convex portion of the processing surface by the laser beam in the laser beam processing region that is inclined with respect to an orthogonal direction orthogonal to a scanning direction for flattening the processing surface while scanning along the processing surface. The laser processing method of any one of Claims 1-4 which process. The planarization step includes
The lower end portion of the second laser beam processing region is aligned with a position for forming the processing flat surface on the processing surface, and the laser beam having the second laser beam processing region is aligned with the processing surface. A first processing step of irradiating a portion in the height direction of the convex portion of the processing surface;
After the first processing step, the lower end portion of the first laser beam processing region is aligned with a position for forming the processing flat surface on the processing surface, and the first laser beam processing region is provided. A second processing step of irradiating the processing surface with the laser beam to form the processing flat surface obtained by processing the remaining portion in the height direction of the convex portion of the processing surface. 4. The laser processing method according to 4. The planarization step includes
A processing step of irradiating the processing surface with the laser light having the first laser light processing region and processing a part of the processing surface in the height direction of the convex portion;
The processing step is repeated a plurality of times, and in the final processing step, the lower end portion of the first laser beam processing region is aligned with a position for forming the processing flat surface on the processing surface, and the processing The laser processing method according to claim 1, wherein a flat surface is formed. A laser beam irradiation unit for irradiating a processing surface having irregularities with a laser beam;
A control unit that controls the laser light irradiation unit and forms a processed flat surface obtained by processing and flattening the convex portion of the processing surface;
The laser beam is
When the laser beam region capable of processing the convex portion of the processing surface is a laser beam processing region, the lower end portion in the laser beam irradiation direction of the laser beam processing region forms the processing flat surface on the processing surface. A laser processing apparatus, wherein the laser processing apparatus is aligned with a position for performing the operation.

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