The disclosure relates to a laser machining method and a laser machining apparatus.
Laser machining methods for various types of machining such as drawing letters, graphics, and the like onto the surface of a workpiece, opening a hole, exfoliation, and cutting, as well as laser machining apparatuses for performing such laser machining have been proposed so far. For example, JP-A-2007-268576 (Patent Document 1) discloses a laser machining method using laser light with a diameter smaller than the diameter of a hole to be machined. In this laser machining method, laser light is moved along a spiral trajectory that connects the center and the outer edge of a hole or a trajectory of concentric circles that are centered at the center of the hole. The start point of a trajectory is at a position of mutual rotation about the center of the hole.
For example, JP-A-2011-170359 (Patent Document 2) discloses a laser machining method for forming a plurality of recessed portions in a glass substrate for mask blanks using laser light. In this laser machining method, recessed portions are formed by moving laser light along spiral trajectories or circulating trajectories centered on the centers of the recessed portions, such that trajectories of an engraved portion that is being engraved by the laser light overlap at least partially.
Patent Document 1: JP-A-2007-268576
Patent Document 2: JP-A-2011-170359
The energy amount per unit area is an element that determines a result of laser machining such as clearness of a letter or graphics on the surface of a workpiece and the depth of a hole formed in the workpiece. The energy amount per unit area depends on the power of the laser light and the scanning speed of the laser light.
By outputting a high-powered laser light from a laser machining apparatus, it is possible to increase the energy amount per unit area on a workpiece surface. On the other hand, if the power of laser light that is output from the laser machining apparatus is low, it is necessary to decrease the scanning speed of the laser light in order to increase the energy amount per unit area. However, the lower the scanning speed of laser light is, the longer the time required for machining is. In the case of machining using low-powered laser light, there is an issue that it is difficult to achieve desired machining quality while preventing the machining time from being longer.
One or more aspects provide a laser machining method and a laser machining apparatus that make it possible to increase the machining quality while preventing a decrease in the machining speed.
A laser machining method according to one aspect is performed using a laser machining apparatus including a laser light source that emits laser light and a scanning mechanism for causing the laser light to scan, and includes a step of causing the laser light to scan a region to be machined. The scanning step includes changing a scanning direction of the laser light a plurality of times in a direction change portion within the region to be machined.
Accordingly, it is possible to increase the machining quality while preventing a decrease in the machining speed. In the direction change portion, the scanning speed decreases by changing the scanning direction of the laser light. Therefore, by changing the scanning direction of the laser light a plurality of times in the direction change portion in the region to be machined, it is possible to increase the energy amount per unit area in the direction change portion. When machining the region to be machined using low-powered laser light, it is possible to perform machining (for example, marking and opening a hole) that provides desired quality, while keeping a time required for the laser light to scan the region to be machined from being longer.
The region to be machined is a unit region in which processing of laser machining is performed. For example, when forming a hole in a certain region through laser machining, the region is equivalent to the region to be machined.
Typically, the direction change portion is positioned at the center of the region to be machined. However, there is no limitation thereto. The direction change portion may be at a position separated from the center of the region to be machined.
It may be preferable that the changing of the scanning direction in the direction change portion include changing the scanning direction of the laser light in a direction that forms an acute angle with respect to a scanning direction before being changed, in the direction change portion.
Accordingly, it is possible to further decrease the scanning speed of the laser light in the direction change portion to a degree to which the machining speed does not decrease largely. Therefore, it is possible to further increase the energy amount per unit area in the direction change portion.
It may be preferable that the changing of the scanning direction in the direction change portion include changing the scanning direction in the direction change portion every time the laser light scans in a direction toward the direction change portion.
Accordingly, it is possible to further increase the energy amount per unit area in the direction change portion.
It may be preferable that the scanning step include a combination of changing the scanning direction in the direction change portion and changing the scanning direction outward of the direction change portion.
Accordingly, if it is not preferable that the power of laser light concentrates excessively in the direction change portion, the power of the laser light can be dispersed in a region outward of the direction change portion.
It may be preferable that the scanning step include at least one of a step of causing the laser light to scan from points on a curve outward of the direction change portion toward the direction change portion and a step of causing the laser light to scan from the direction change portion toward the points on the curve.
Accordingly, a machining shape having a curve in planar view (typically, a circular hole) can be formed in the region to be machined.
It may be preferable that the scanning step include at least one of a step of causing the laser light to scan from points on sides of a polygon that surrounds the direction change portion toward the direction change portion and a step of causing the laser light to scan from the direction change portion toward the points on the sides of the polygon.
Accordingly, a machining shape having a polygon in planar view can be formed in the region to be machined.
It may be preferable that the direction change portion be positioned at a center of the region to be machined. Accordingly, it is possible to maximize the energy amount per unit area at the center of the region to be machined.
It may be preferable that the laser machining method further include a step of repeatedly executing the scanning step on the next region to be machined so as to form a plurality of cells.
Accordingly, for example, when machining a plurality of machining regions, it is possible to repeat the same machining at a precise pitch.
It may be preferable that the plurality of cells be arranged two-dimensionally. Accordingly, marking can be performed, for example.
It may be preferable that the plurality of cells be arranged one-dimensionally. Accordingly, a groove can be formed, for example.
A laser machining apparatus according to one aspect includes a laser light source that emits laser light, a scanning mechanism for causing the laser light to scan, and a control unit that controls the scanning mechanism, and the control unit controls the scanning mechanism so as to change a scanning direction of the laser light a plurality of times in a direction change portion within a region to be machined.
Accordingly, it is possible to realize a laser machining apparatus that can increase the machining quality while preventing a decrease in the machining speed.
It may be preferable that the control unit control the scanning mechanism so as to change the scanning direction of the laser light in a direction that forms an acute angle with respect to a scanning direction before being changed.
Accordingly, it is possible to further decrease the scanning speed of the laser light in the direction change portion to a degree to which the machining speed does not largely decreases. Therefore, it is possible to further increase the energy amount per unit area in the direction change portion.
It may be preferable that the control unit control the scanning mechanism such that the laser light scans in accordance with a scanning pattern that includes a plurality of straight lines extending radially from the direction change portion.
Accordingly, it is possible to further increase the energy amount per unit area in the direction change portion.
It may be preferable that the scanning pattern include a pattern in which the scanning direction of the laser light is folded back outward of the direction change portion.
Accordingly, when it is not preferable that the power of laser light concentrates excessively in the direction change portion, the power of the laser light can be dispersed in a region outward of the direction change portion.
It may be preferable that the scanning pattern include a straight line that connects a curve that surrounds the direction change portion and the direction change portion. Accordingly, it is possible to form a machining shape having a curve in planar view (typically, a circular hole) in the region to be machined.
It may be preferable that the scanning pattern include a straight line that connects the direction change portion and sides of a polygon that surrounds the direction change portion. Accordingly, a machining shape that includes a polygon in planar view can be formed in the region to be machined.
According to one or more embodiments, it is possible to provide a laser machining method and a laser machining apparatus that make it possible to increase the machining quality while preventing a decrease in the machining speed.
Embodiments will be described in detail with reference to the drawings. Note that the same reference numerals are assigned to the same or equivalent portions in the following drawings, and their description is not repeated.
The controller 101 includes a laser light source 111 that emits laser light and a control unit 112. The type of the laser light source 111 is not particularly limited. For example, a fiber laser can be used for the laser light source 111. The laser light source 111 may be a solid-state laser such as a YAG laser or a gas laser such as a CO2 laser. The laser light from the laser light source 111 is pulse light, for example. However, the laser light may also be continuous (CW) light. The control unit 112 integrally controls the laser machining apparatus 100.
In an embodiment, the power (average power) of laser light is not limited particularly. In an example of an embodiment, the average power of laser light is 20 W. In the laser machining apparatus and laser machining method according to an embodiment, it is possible to use laser light with less power than the average power (e.g., 50 W or more) of a conventional laser machining apparatus. However, it should be noted that an embodiment is not limited to use of low-powered laser light.
The head portion 102 is connected to the controller 101 using the cable 103. For example, the cable 103 can include an optical fiber cable for transmitting light from the laser light source 111 to the head portion 102, a signal cable for transmitting a control signal from the control unit 112 to the head portion 102, and a power supply cable for supplying power to the head portion 102, or the like.
The head portion 102 includes a scanning mechanism 120 for causing laser light generated by the laser light source 111 to scan. The scanning mechanism 120 includes a mirror 121 and a driving unit 122 that drives the mirror 121. Laser light generated by the laser light source 111 is reflected by the mirror 121, and the surface of a workpiece 11 placed on a stage 10 is irradiated. A region 11a to be machined within the surface of the workpiece 11 is irradiated with laser light 20, and thereby the region 11a to be machined is machined.
The driving unit 122 drives the mirror 121 in response to a control signal from the control unit 112. Accordingly, the laser light 20 scans. The scanning mechanism 120 can be realized by a galvano mirror, for example. The scanning mechanism 120 may cause laser light to scan in a primary direction or secondary direction, or both the primary direction and secondary direction.
In an embodiment, the controller 101 and the head portion 102 are separate bodies. However, the controller 101 and the head portion 102 may also be accommodated in one housing.
In a peripheral edge portion of the region 11a to be machined, the scanning direction of laser light is changed, and thus the scanning speed of the laser light decreases. In a central portion of the region 11a to be machined, the scanning speed of laser light is higher than at the peripheral edge portion of the region 11a to be machined.
The depth of a hole that is formed at the position of the spot 21 depends on the energy density per unit area. In the peripheral edge portion of the region 11a to be machined, the scanning speed of laser light is low, and thus the energy density per unit area is high. Therefore, as shown in the plan view and cross-sectional view in
In an embodiment, due to improvement in scanning of laser light, desired machining such as marking or forming of a hole can be performed in the region 11a to be machined even using low-powered laser light. An embodiment will be described below in detail.
In an embodiment, the control unit 112 and the scanning mechanism 120 of the laser machining apparatus 100 change, in the central portion 11b of the region 11a to be machined, the scanning direction of laser light in a direction that forms an acute angle with respect to the scanning direction of the laser light before being changed. Accordingly, for example, it is possible to further decrease the scanning speed of laser light in the central portion 11b of the region 11a to be machined to a degree to which the machining speed does not largely decreases. Therefore, it is possible to further concentrate the energy in the central portion of the region 11a to be machined.
As shown in (A) of
In addition, if the ordinary scanning method of laser light shown in
As described above, according to an embodiment, the machining speed can be increased without increasing the power (output) of laser light. Accordingly, the machining time can be shortened. Alternatively, according to an embodiment, the same machining (for example, marking and forming a hole) can be realized with lower-powered laser light. Therefore, the laser machining apparatus can be realized inexpensively.
The “predetermined direction change portion” is typically the central portion 11b of the region 11a to be machined, but there is no limitation thereto. As will be illustrated later, “direction change portion” may also be a location separated from the central portion 11b of the region 11a to be machined.
As shown in
Next, in step S2, it is determined whether or not all of the regions 11a to be machined in the workpiece 11 have been machined. This determination is executed by the control unit 112. If it is determined that all the regions 11a to be machined have been machined (YES in step S2), the processing ends. On the other hand, if it is determined that there is a region 11a yet to be machined (NO in step S2), the procedure advances to step S3.
In step S3, the control unit 112 controls the laser machining apparatus 100 so as to machine the next region 11a to be machined. This control can include control of the laser light source 111 and control of the driving unit 122 of the scanning mechanism 120, for example. After the processing in step S3 is executed, overall processing returns to step S1, and the processing in step S1 is executed on all the regions 11a to be machined.
In the patterns shown in
Note that, in the pattern in
Furthermore, the direction change portion that is at a position at which the scanning direction of laser light changes does not need to be limited to the central portion of the region 11a to be machined.
Scanning patterns shown in
Furthermore, an embodiment is not limited to a configuration in which the start point or the end point of scanning of the laser light is on a curve. As shown in
The laser machining apparatus 100 causes the laser light to scan along one of the above-described scanning patterns. For this reason, the control unit 112 can store programs for executing all or some of the above-described scanning patterns, for example. The control unit 112 may select a scanning pattern illustrated above by executing such a program.
The above-described scanning of laser light is executed repeatedly in order to form the cells 12. Accordingly, marks with high visual recognizability can be formed. For example, it is conceivable that, at a manufacturing site, after marking the code 15 on the surface of the workpiece 11, an oil film or paint film adheres over the code 15. If a hole formed in the region 11a to be machined is shallow, it is highly likely that the hole is buried by an oil film or a paint film, and thus the visual recognizability of the code is likely to decrease. Therefore, reading of the code is likely to fail. However, according to an embodiment, a deeper hole can be formed in the central portion of the region 11a to be machined, and thus it is possible to reduce the likelihood that the hole is completely buried by an oil film. Therefore, according to an embodiment, if an oil film or a paint film adheres over the code 15, it is possible to maintain the high visual recognizability of the code 15.
In addition, depending on a workpiece, cutting machining, polishing, and the like are required in postprocessing in some cases. According to an embodiment, a deeper hole can be formed in the region 11a to be machined. Therefore, even if postprocessing as described above is performed, it is possible to further decrease the likelihood of a formed code being lost.
Furthermore, according to an embodiment, by adopting the above-described scanning patterns shown in
In addition, regarding printing of a bar code or two-dimensional code, the more precise the pitch of a cell center is, the higher the quality of the code is. According to an embodiment, it is possible to engrave most deeply the central portion 11b of the region 11a to be machined, and thus it is possible increase the accuracy of the pitch of a cell center. Therefore, it is possible to print a code with high quality on a workpiece surface.
Furthermore, the laser machining method according to an embodiment is not limited to a method for printing a code onto a workpiece surface.
The disclosed embodiments here are exemplary in all respects, and are to be considered to be non-limitative. The scope of the present invention is indicated by claims, not by the above embodiments, and is intended to include meanings equivalent to claims, and all the modifications in the claims.
Number | Date | Country | Kind |
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2016-138630 | Jul 2016 | JP | national |
This application is a continuation application of International Application No. PCT/JP2017/022337, filed on Jun. 16, 2017, which claims priority based on the Article 8 of Patent Cooperation Treaty from prior Japanese Patent Application No. 2016-138630, filed on Jul. 13, 2016, the entire contents of which are incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/JP2017/022337 | Jun 2017 | US |
Child | 16221675 | US |