JP5861494B2 - Laser processing apparatus and laser processing method - Google Patents

Description

  The present invention relates to a laser processing apparatus and a laser processing method capable of three-dimensional processing of an inclined surface or the like with a small surface roughness.

  In recent years, a laser processing apparatus that performs processing by irradiating a laser beam (laser light) is also used for form formation (shape formation) of a member or the like that has been ground using a grindstone. As a method for processing this three-dimensional shape, a method is proposed in which laser light is scanned in layers. Patent Document 1 proposes a laser processing apparatus that uses an elliptical cross-sectional shape of laser light and performs rotation control for processing.

  In this laser processing apparatus, an elliptical shaping means for shaping an elliptical laser beam from a circular laser beam, a branching means for branching an elliptical laser beam obtained by the elliptical shaping means, and each obtained by the branching means Rotating means for rotating the elliptical laser beam, a combining means for combining the elliptical laser beam obtained by the rotating means, and a mask mechanism for cutting out the combined laser beam into a predetermined shape so that the elliptical angles are different have.

JP 2008-49361 A

The following problems remain in the conventional technology.
Regarding the method of processing the inclined surface by scanning the laser beam in layers, various studies have been made on the shape of the scanning beam and the scanning method. However, in order to process the inclined surface more smoothly by processing into a layer shape, there has been no method for obtaining sufficient surface roughness by using a laser beam pulse mark or the like. In addition, it is not a method for processing an inclined surface, but as a processing method using an elliptical beam, two elliptical beams are overlapped and rotated into a mask pattern as in the laser processing apparatus described in Patent Document 1. However, since this method aims to obtain a homogeneous beam, the effect of reducing the surface roughness of the processed surface cannot be obtained.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a laser processing apparatus and a laser processing method capable of processing an inclined surface with a small surface roughness in three-dimensional processing.

  The present invention employs the following configuration in order to solve the above problems. That is, the laser processing apparatus of the present invention is an apparatus for irradiating a workpiece with a laser beam and processing the laser beam that oscillates the laser beam to irradiate the workpiece with a constant repetition frequency and can scan the laser beam. An irradiation mechanism; a position adjustment mechanism capable of holding the object to be processed and adjusting a relative positional relationship between the object to be processed and the laser beam; and a control unit for controlling these mechanisms; An elliptical beam shaping optical unit that forms an elliptical beam by shaping the cross-sectional shape of the laser beam into an elliptical shape, and an elliptical beam rotation that rotates the elliptical beam and orients the minor axis of the elliptical shape in a predetermined direction. An optical unit, and the control unit obtains a normal vector on the surface of the designed post-processed shape in the processing region of the processing target object, and the elliptic vector of the normal vector is obtained. And performing control to direct the minor axis of the elliptical shape in the direction of the orthogonal projection vector of the plane perpendicular to the irradiation direction of.

  Further, the laser processing method of the present invention is a method of processing by irradiating a processing target with a laser beam, and oscillating the laser beam to irradiate the processing target with a constant repetition frequency and perform laser irradiation. And a position adjustment step of adjusting the relative positional relationship between the processing object and the laser beam while holding the processing object, and the laser irradiation step includes a beam cross-sectional shape of the laser beam. An ellipse beam shaping step for shaping an ellipse into an ellipse beam, and an ellipse beam rotation step for rotating the ellipse beam to direct the minor axis of the ellipse in a predetermined direction. A normal vector on the surface of the post-processed shape in design in the region is obtained, and the elliptical shape in the direction of the orthogonal projection vector onto the surface perpendicular to the irradiation direction of the elliptical beam of the normal vector Wherein the directing the minor axis of the.

  That is, with these laser processing apparatuses and methods, a normal vector on the surface of the designed post-processed shape is obtained in the processing region of the processing object, and the normal vector is applied to a surface perpendicular to the irradiation direction of the elliptical beam. Since the elliptical minor axis is directed in the direction of the projection vector, the surface roughness can be reduced on the inclined machining surface.

  Furthermore, in the laser processing apparatus of the present invention, when the control unit performs the scanning of the elliptical beam, the processing region is set as a stack of a plurality of processing layers in the irradiation direction of the elliptical beam. Irradiate the elliptical beam to the layer, remove a predetermined portion for each processing layer, and control to form a three-dimensional processing surface, and after the design processing in the two adjacent processing layers The normal vector is calculated from the coordinates of the start point or end point of the scan for determining the shape.

  Further, in the laser processing method of the present invention, when the elliptical beam is scanned, the processing region is set as a plurality of processing layers stacked in the irradiation direction of the elliptical beam, Irradiating an elliptical beam, removing a predetermined portion for each processing layer, forming a three-dimensional processing surface, and starting the scanning to determine the designed post-processing shape in two adjacent processing layers The normal vector is calculated from the coordinates of the point or the end point.

  That is, in these laser processing apparatuses and methods, the normal vector is calculated from the coordinates of the start point or end point of scanning that determines the post-design shape after the design in two adjacent processing layers, so that the method can be calculated by simple calculation. A line vector can be calculated, and the minor axis direction of the elliptical beam can be easily determined.

The present invention has the following effects.
That is, according to the laser processing apparatus and the laser processing method of the present invention, the normal vector on the surface of the designed post-processed shape is obtained in the processing region of the processing target object, and the elliptical beam irradiation direction of the normal vector Since the minor axis of the elliptical shape is directed in the direction of the orthogonal projection vector onto the vertical surface, it is possible to reduce the surface roughness on the inclined processing surface.
Therefore, the laser processing apparatus and laser processing method of the present invention are suitable for, for example, three-dimensional shape processing with high surface accuracy, such as a cutting tool.

In the laser processing apparatus and laser processing method concerning this invention, it is a rough whole block diagram which shows a laser processing apparatus. In this embodiment, it is a figure which shows the cross-sectional shape in each optical path of a laser beam. In this embodiment, it is explanatory drawing which shows the relationship between the intersection of a post-process shape and a process layer, the short-axis direction of an elliptical beam, and a scanning direction. In this embodiment, it is explanatory drawing which shows a major axis and a minor axis regarding the beam cross-sectional shape of an elliptical beam. In the laser processing method of this embodiment, it is explanatory drawing which shows the method of calculating the direction of a normal vector based on three points of the adjacent process layer. In this embodiment, it is explanatory drawing which shows the processing state (a) by an elliptical beam, and the processing state (b) by a circular beam. In the Example of the laser processing apparatus and laser processing method concerning this invention, it is a side view which shows the shape (a) before a process of a process target object, and the shape (b) after a process on design. In a present Example, it is a flowchart which shows the laser processing method in order of a process. It is explanatory drawing which shows the processing range in the laser processing method of a present Example. It is explanatory drawing shown in order of a process in the laser processing method of a present Example. It is explanatory drawing shown in the exception process in the laser processing method of a present Example. In a present Example, it is an enlarged photograph image which shows the process target object in the middle of a process.

  Hereinafter, an embodiment of a laser processing apparatus and a laser processing method according to the present invention will be described with reference to FIGS. In each drawing used in the following description, there is a portion where the scale is appropriately changed as necessary in order to make each member recognizable or easily recognizable.

  As shown in FIG. 1, the laser processing apparatus 1 of the present embodiment is an apparatus that processes a workpiece W by irradiating the workpiece W with a laser beam (laser light), and oscillates the laser beam L1 to process the workpiece W. A laser irradiation mechanism 2 capable of irradiating and scanning with a constant repetition frequency, and a position adjustment mechanism 3 capable of holding the workpiece W and adjusting the relative positional relationship between the workpiece W and the laser beam L1. And a control unit 4 for controlling these mechanisms.

The laser irradiation mechanism 2 pulse-oscillates a laser beam having a circular cross section as shown in FIG. 2A, which becomes the laser beam L1, and also has a spot shape having a circular cross section as shown in FIG. 2A. A laser light source 5 having an optical system for condensing light is also provided.
The laser irradiation mechanism 2 also has an elliptical beam shaping optical unit 6 that shapes the beam cross-sectional shape of the laser beam L1 into an elliptical shape to make the elliptical beam L2, and rotates the elliptical beam L2 so that the short axis of the elliptical shape has a predetermined axis. And an elliptical beam rotating optical unit 7 directed in the direction.
The laser irradiation mechanism 2 includes a mirror 8 that reflects the rotated elliptical beam L2 to change the optical path, a galvano scanner 9 that scans the elliptical beam L2 to be irradiated, and an f-θ lens that condenses the elliptical beam L2. The condensing lens 10 is provided.

  The elliptical beam shaping optical unit 6 is an optical system including two cylindrical lenses 6a and the like, and the laser beam L1 having a circular cross section is converted into an elliptical cross section as shown in FIG. It has a function of shaping into a beam L2. As shown in FIG. 4, the elliptical cross section of the shaped elliptical beam L2 preferably has a minor axis / major axis ≦ 0.5. That is, when the major axis diameter of the elliptical cross section of the elliptical beam L2 is a and the minor axis diameter is b, b / a ≦ 0.5.

As shown in FIG. 2C, the elliptical beam rotating optical unit 7 is an optical system including a dove prism 7a that rotates the elliptical beam L2 with its short axis having an elliptical cross section in a predetermined direction. The dove prism 7a is housed in the holder 7b.
The elliptical beam rotating optical unit 7 reflects the rotated elliptical beam L2 to change the optical path, the galvano scanner 9 that scans the irradiated elliptical beam L2, and the elliptical beam L2. And a condensing lens 10 of -θ lens.

The position adjusting mechanism 3 is movable in the X direction parallel to the horizontal plane, and moves in the Y direction perpendicular to the X direction and parallel to the horizontal plane provided on the X axis stage 10x. Direction Y-axis stage unit 10y, and a Z-axis stage unit 10z provided on the Y-axis stage unit 10y and capable of holding the workpiece W and movable in a direction perpendicular to the horizontal plane. .
The galvano scanner 9 and the condenser lens 10 are disposed immediately above the Z-axis stage unit 10z.

The laser beam L1 and the elliptical beam L2 emitted by the laser irradiation mechanism 2 are single mode, the light intensity distribution of the beam section is a Gaussian distribution, and as shown in FIG. The light intensity distribution is elliptical.
As the laser light source 5, a laser light source that can irradiate laser light having a wavelength of 190 to 550 nm can be used. For example, in this embodiment, a laser light source that can oscillate and emit laser light having a wavelength of 355 nm is used.

As shown in FIG. 3, the control unit 4 obtains a normal vector H on the surface of the designed post-processed shape in the processing region of the processing target W, and in the irradiation direction of the elliptical beam L2 of the normal vector H. It has a function of controlling the elliptical short axis in the direction of an orthogonal projection vector onto a vertical plane.
Further, as shown in FIG. 5, when the elliptical beam L2 is scanned, the control unit 4 sets the machining region as a stack of a plurality of machining layers LY in the irradiation direction of the elliptical beam L2 in the machining program. Each mechanism layer LY is irradiated with an elliptical beam L2, a predetermined portion is removed for each processing layer LY, and each mechanism is controlled to form a processing surface having a three-dimensional shape.

In addition, the control unit 4 calculates a normal vector H from the coordinates of the start point or end point of scanning that determines the designed post-processing shape in two adjacent processing layers LY.
For example, as shown in FIGS. 5A and 5B, these three points are based on the coordinates of the end positions P1, P2, and P3 of the scan that determine the designed post-processing shape in the two adjacent processing layers LY. A normal vector H with respect to the plane constituted by is calculated. Further, the control unit 4 directs the short axis of the elliptical shape in a direction perpendicular to the Z direction that is the irradiation direction of the elliptical beam L2 of the obtained normal vector H, that is, the direction of the orthogonal projection vector onto the XY plane. In this manner, the elliptical beam rotation optical unit 7 is controlled to rotate the elliptical beam L2.

  As described above, the control unit 4 controls each of the above mechanisms to perform processing by scanning the elliptical beam L2 rotated in a predetermined direction for each processing layer LY as shown in FIGS. At this time, as shown in FIG. 3, the scanning interval d of the elliptical beams L2 in the same processing layer LY is set so that the adjacent elliptical beams L2 overlap each other by 1/3 or more of the area in the major axis direction. It is preferable to scan by changing the scanning position so as to pass between scanning lines S1 (scanning direction) of the immediately preceding processing layer LY between the processing layers LY. For example, scanning is performed by changing the scanning position of ½ of the scanning interval between adjacent processing layers LY.

  In FIG. 3, the scanning line S1 in the first processing layer LY is illustrated by a broken line arrow, and the scanning line S2 in the second processing layer LY is illustrated by a two-dot chain line arrow. Moreover, in FIG. 3, the code | symbol C has shown the intersection line of the process shape and the process layer LY. If the thickness of the processing layer LY is infinitely small, the intersection of the processing layer LY and the designed post-processing shape can be regarded as a line.

  By scanning the short axis direction of the elliptical cross section of the elliptical beam L2 as described above in accordance with the direction of the machining surface, which is an inclined surface or the like, as shown in FIG. As shown in FIG. 6 (b), the convex portion W1 formed by the processing mark by the beam L2 becomes smaller than when the laser beam L0 having a circular cross section is scanned, and the surface roughness on the processing surface is reduced. Is done.

Thus, in the laser processing apparatus 1 and the laser processing method of the present embodiment, the normal vector H on the surface of the designed post-processed shape is obtained in the processing region of the processing target W, and the elliptical beam L2 of the normal vector H is obtained. Since the minor axis of the elliptical shape is directed in the direction of the orthogonal projection vector to the plane (XY plane) perpendicular to the irradiation direction (Z direction) of the surface, it is possible to reduce the surface roughness on the inclined machining surface Become.
In addition, since the normal vector H is calculated from the coordinates of the start point or end point of scanning that determines the designed post-processing shape in the two adjacent processing layers LY, the normal vector H can be calculated by a simple calculation. It is possible to easily determine the minor axis direction of the elliptical beam L2.

  Next, an embodiment in which a workpiece is actually formed by the laser processing apparatus and laser processing method of the present invention will be described with reference to FIGS.

In the embodiment of the present invention, the thick flat plate-like workpiece W before processing shown in FIG. 7A is formed into a post-designed shape shown in FIG. Shaped into a quadrangular pyramid shape (pyramid shape). In addition, the said 4 inclined surfaces were made into the designated surface which processes, and it divided into four inclined surfaces and implemented.
In this embodiment, a laser beam L1 and an elliptical beam L2 having a wavelength of 355 nm and a repetition frequency of 166 kHz were used. Further, a ceramic sintered body (SiC, cBN, etc.) was used as the workpiece W.

  Furthermore, the elliptical shape after beam shaping was set to minor axis / major axis = 0.3. The scanning interval of the elliptical beam L2 on the same plane is scanned so that 1/3 of the elliptical shapes overlap, and the scanning interval d is set so as to pass between the scanning lines S1 of the immediately preceding processing layer LY between the processing layers LY. The scanning was performed by shifting the scanning position by 1/2 minute.

Next, rotation control of the elliptical beam L2 will be described with reference to flowcharts and explanatory diagrams shown in FIGS.
First, as shown in FIG. 9, the control unit 4 obtains the Z-direction range, that is, the machining depth of one designated surface among the four inclined surfaces (step S <b> 1), and two layers within the Z-direction range ( A program (for example, a program for two layers before and after the intermediate point in the Z direction) of the n-th layer and (n + 1) -th layer of two processed layers LY) is obtained (step S2).

Then, in the machining program for the nth machining layer LY, “m = 1” is set with the number m of scanning being the first (step S3). Next, the start or end point of the m-th, it is determined whether to match the specified value (step S4), and when does not match the specified value, sets the number of scanning lines m to "m = 1 + 1" (step S5) The determination in step S4 is performed again. That is, it is determined whether the scanning line is a line that forms an inclined surface for obtaining the normal vector H.
The specified value is a coordinate representing the position of the inclined surface at the z coordinate corresponding to the nth layer in the machining program for the nth machining layer LY. This is a numerical value for setting the position of the inclined surface for obtaining the normal vector H.

As shown in FIG. 10A, when the specified value is coincident, the coordinates (x1, y1, z1) are stored as the position P1 of the first point (step S6). Further, to set the scan number m to "m = m + 1", it is determined whether the start point or end point of the m-th matches the specified value again (step S8). As shown in (b) of FIG. 10, when it matches the specified value, the coordinates (x2, y2, z2) are stored as the second position P2 (step S9). Then, the scanning number m is set to “m = m”. If it does not match the default value, “m = m + 1” is set, and the determination in step S4 is performed again. That is, it is determined whether the corresponding two continuous scanning lines (m and m + 1) are lines that form an inclined surface for obtaining the normal vector H. Then, as shown in FIG. 11, when only one scanning line is applicable, an exception process (step S9 ′ ) is performed, which is the same process as step S9.

  Next, in the machining program for the machining layer LY of the (n + 1) th layer, as shown in FIG. 10C, the coordinate (x3, y3, z3) are recorded (step S11). The normal vector H of the inclined plane is obtained from the three points P1, P2 and P3 thus obtained, and only the XY plane component of the normal vector H is calculated (step S12). The rotational angle of the elliptical beam L2 is obtained based on the direction of the XY plane component of the normal vector H calculated in this way, and the elliptical beam L2 is rotated by the elliptical beam rotating optical unit 7 at the rotational angle to perform laser processing. To start.

Thus, when the said laser processing was implemented, Rmax was set to about 0.5 micrometer or less with the present Example, while Rmax was about 1.5 micrometers in the conventional method.
In this embodiment, an enlarged photograph image showing a state where two inclined surfaces are laser processed is shown in FIG. As can be seen from this photographic image, an inclined surface with very small surface roughness and high surface accuracy is obtained.

  The technical scope of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Laser processing apparatus, 2 ... Laser irradiation mechanism, 3 ... Position adjustment mechanism, 4 ... Control part, 6 ... Elliptical beam shaping optical part, 7 ... Elliptical beam rotation optical part, H ... Normal vector, L1 ... Laser beam, L2 ... elliptical beam, LY ... processing layer, W ... processing object

Claims (4)

An apparatus for irradiating a processing object with a laser beam,
A laser irradiation mechanism capable of oscillating a laser beam to irradiate the workpiece with a constant repetition frequency and capable of scanning;
A position adjustment mechanism capable of holding the workpiece and adjusting a relative positional relationship between the workpiece and the laser beam;
A control unit for controlling these mechanisms,
An elliptical beam shaping optical unit in which the laser irradiation mechanism forms an elliptical beam by shaping a beam cross-sectional shape of the laser beam into an elliptical shape;
An elliptical beam rotating optical unit that rotates the elliptical beam and directs the elliptical minor axis in a predetermined direction;
The control unit obtains a normal vector on the surface of the designed post-processed shape in the processing region of the processing object, and the direction of the orthogonal projection vector onto the surface perpendicular to the irradiation direction of the elliptical beam of the normal vector A laser processing apparatus for controlling the elliptical minor axis to the surface. In the laser processing apparatus of Claim 1,
When the control unit scans the elliptical beam, the processing region is set as a plurality of processing layers stacked in the irradiation direction of the elliptical beam, and the elliptical beam is irradiated to each processing layer. , Removing a predetermined part for each processing layer, performing control to form a processing surface of a three-dimensional shape, and determining the design post-processing shape in the two adjacent processing layers A laser processing apparatus that calculates the normal vector from coordinates of an end point. A method of processing by irradiating a workpiece with a laser beam,
A laser irradiation step of oscillating a laser beam to irradiate the workpiece with a constant repetition frequency and scanning;
A position adjustment step of holding the workpiece and adjusting a relative positional relationship between the workpiece and the laser beam,
The laser irradiation step is an elliptical beam shaping step in which a beam cross-sectional shape of the laser beam is shaped into an elliptical shape to form an elliptical beam;
An elliptical beam rotating step of rotating the elliptical beam and directing the minor axis of the elliptical shape in a predetermined direction;
A normal vector on the surface of the designed post-processed shape is obtained in the processing region of the processing object, and the elliptical shape is oriented in the direction of an orthogonal projection vector onto a surface perpendicular to the irradiation direction of the elliptical beam of the normal vector. A laser processing method characterized by directing a short axis. In the laser processing method of Claim 3,
Using the laser processing apparatus according to claim 1,
When the control unit scans the elliptical beam, the processing region is set as a plurality of processing layers stacked in the irradiation direction of the elliptical beam, and the elliptical beam is irradiated to each processing layer. The scanning start point or end point coordinates for removing a predetermined portion for each processing layer, forming a three-dimensional processing surface, and determining the designed post-processing shape in two adjacent processing layers The normal processing vector is calculated from the laser processing method.