Laser processing method, programming tool, and laser processing machine

Abstract

Provided is a laser processing method for forming a through-hole in a workpiece by using a laser processing machine that performs drilling processing by scanning laser light emitted from a laser oscillator with a galvano mirror and condensing the laser light onto the workpiece placed on a table, the laser processing method including a first processing hole forming step and a second processing hole forming step. The first processing hole forming step includes executing, on a first processing surface of the workpiece, a processing hole forming process in which a scanning area that can be scanned by the galvano mirror is moved by the movement of the table every time the drilling processing within one scanning area is completed, such that a circulation path for circulating the scanning area along a direction parallel to the outer periphery of a processing surface of the workpiece moves from the outer peripheral side toward the inner side of the workpiece. The second processing hole forming step includes performing the processing hole forming process on a second processing surface. The first processing hole forming step and the second processing hole forming step are executed a plurality of times, such that the positions of the through-holes to which the processing holes formed by one set of the first processing hole forming step and the second processing hole forming step connect are different.

Description

Laser processing method, programming tool and laser processing machine

[0001] The present disclosure relates to a laser processing method, a programming tool, and a laser processing machine for forming a through hole in an object to be processed by irradiating it with laser light.

[0002] A laser processing method using a laser beam is used to form through holes in printed circuit boards. Patent Document 1 discloses a laser through-hole (LTH) processing method for forming through holes by connecting holes formed by laser processing on the front and back surfaces of a three-layer printed circuit board having copper foil on both sides of a resin plate. The method involves defining multiple scanning areas on the printed circuit board, where a laser beam can be scanned using a galvanometer mirror, and drilling holes in the scanning areas in a spiral pattern from the edge of the printed circuit board toward the center. This laser processing method can prevent sudden and partial shrinkage of the printed circuit board and prevent misalignment of the holes from the target positions of the holes that occur before and after shrinkage.

[0003] Patent No. 6793892

[0004] Although it depends on the type of material constituting the printed circuit board to be processed, the technique described in Patent Document 1 can be used to form approximately 1.3 million to 1.5 million through holes in a single printed circuit board. However, in recent years, the number of through holes formed in printed circuit boards has been increasing, exceeding 1.3 million to 1.5 million. When the technique described in Patent Document 1 is used to form such a large number of through holes in printed circuit boards, the holes are formed densely, which causes a problem of warping in the printed circuit board when the front surface is processed. Furthermore, even if the printed circuit board is fixed to a table with a clamp or the like after processing the front surface to suppress warping and then process the back surface, there is a problem that the positional deviation between the holes formed on the front surface and the holes formed on the back surface becomes large, making it impossible to form through holes with high precision.

[0005] The present disclosure has been made in consideration of the above, and aims to provide a laser processing method that, when forming through holes by forming holes on the front and back surfaces of a workpiece, can suppress the occurrence of warping of the workpiece after forming holes on one side, and can suppress misalignment of the holes formed on the front and back surfaces, compared to conventional methods.

[0006] To solve the above-mentioned problems and achieve the object, the present disclosure provides a laser processing method for forming a through hole in a workpiece using a laser processing machine that scans a laser beam emitted from a laser oscillator with a galvanometer mirror and focuses the laser beam on a workpiece placed on a table to perform a drilling process, the method including a first hole forming step and a second hole forming step. In the first hole forming step, a hole forming process is performed on the first workpiece surface of the workpiece, in which the table is moved to move the scanning area so that a circular path in which a scanning area scannable by the galvanometer mirror revolves along a direction parallel to the outer periphery of the workpiece surface moves from the outer periphery toward the inside of the workpiece. In the second hole forming step, a hole forming process is performed on a second workpiece surface opposite the first workpiece surface. The first hole forming step and the second hole forming step are performed multiple times so that the positions of the through holes connected to the pair of holes formed by the first hole forming step and the second hole forming step are different.

[0007] The laser processing method according to the present disclosure has the advantage that, when forming through holes by forming holes on the front and back surfaces of a workpiece, warping of the workpiece after forming holes on one surface can be suppressed and misalignment of the holes formed on the front and back surfaces can be suppressed compared to conventional methods.

[0008] FIG. 1 is a diagram schematically illustrating an example of the configuration of a laser processing machine according to embodiment 1. FIG. 2 is a diagram illustrating an example of the arrangement of scanning areas and the processing sequence in a laser processing method according to the prior art. FIG. 3 is a diagram illustrating an example of the state of a workpiece after a processed hole has been formed according to the prior art. FIG. 4 is a diagram for explaining an overview of the laser processing method according to embodiment 1. FIG. 5 is a diagram illustrating an example of the functional configuration of a programming tool for the laser processing machine according to embodiment 1. FIG. 1 shows an example of the procedure of the laser processing method according to embodiment 1. FIG. 1 shows an example of the procedure of the laser processing method according to embodiment 1. FIG. 2 explains the case where laser processing is performed by simply dividing through-hole position data into three in the prior art. FIG. 3 shows characteristic information representing an example of the relationship between the number of revolutions and the amount of positional deviation of the processed hole in the laser processing method according to embodiment 2. FIG. 4 schematically shows an example of the processing sequence in the laser processing method according to embodiment 2. FIG. 5 schematically shows an example of the processing sequence in the laser processing method according to embodiment 2. FIG. 6 schematically shows an example of the processing sequence in the laser processing method according to embodiment 2. FIG. 7 schematically shows an example of the configuration of a laser processing machine according to embodiment 3. FIG. 8 shows an example of the configuration of a control circuit that realizes a control device for the laser processing machines according to embodiments 1 to 3.

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser processing method, a programming tool, and a laser processing machine according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0010] Embodiment 1. FIG. 1 is a diagram schematically illustrating an example of the configuration of a laser processing machine according to embodiment 1. The laser processing machine 10 is an apparatus that performs a drilling process on a workpiece W, which is an object to be processed, by irradiating it with pulsed laser light L. An example of the workpiece W is a printed circuit board or IC (Integrated Circuit) package board mounted on an electronic device or the like. An example of the printed circuit board is a resin board with copper foil formed on the front and back surfaces. Note that the workpiece W may be any object in which a through hole can be formed, and may be an object other than the above-described printed circuit board or IC package board.

[0011] In Figure 1, the X-axis, Y-axis, and Z-axis are three axes that are perpendicular to one another. The X-axis and Y-axis are two axes that are perpendicular to one another and are located within the mounting surface of the table 15. The Z-axis is an axis that is perpendicular to both the X-axis and the Y-axis. The laser processing machine 10 performs drilling to quickly form multiple holes distributed in the X-axis and Y-axis directions.

[0012] The laser processing machine 10 comprises a laser oscillator 11 that emits laser light L, galvanometer mirrors 12Y, 12X that deflect and scan the laser light L, galvanometer scanners 13Y, 13X that rotate the galvanometer mirrors 12Y, 12X, an fθ lens 14 that is a focusing lens that focuses the laser light L, a table 15 that holds the workpiece W, a camera 16 that images the table 15 and the workpiece W, and a control device 20 that controls the entire laser processing machine 10.

[0013] The laser oscillator 11 emits pulsed laser light L. The pulsed laser light L is, for example, infrared light. An example of the laser oscillator 11 is a carbon dioxide (CO2) laser. The peak wavelength of the pulsed laser light L is in the range of 9.3 μm to 10.6 μm. Hereinafter, the pulsed laser light L will be referred to as laser light L.

[0014] The galvanometer mirror 12Y is driven by a galvanometer scanner 13Y to scan the laser light L. The galvanometer scanner 13Y is a servo motor used to position the galvanometer mirror 12Y. The galvanometer scanner 13Y rotates the galvanometer mirror 12Y by control according to a position command. In other words, the galvanometer scanner 13Y adjusts the position and angle of the laser light L incident on the fθ lens 14 by driving the galvanometer mirror 12Y. In this example, the galvanometer scanner 13Y moves the irradiation position of the laser light L in the Y-axis direction by rotating the galvanometer mirror 12Y within a specific range of deflection angles.

[0015] The galvanometer mirror 12X is driven by a galvanometer scanner 13X to scan the laser light L. The galvanometer scanner 13X is a servo motor used to position the galvanometer mirror 12X. The galvanometer scanner 13X rotates the galvanometer mirror 12X by control according to a position command. In other words, the galvanometer scanner 13X adjusts the position and angle of the laser light L incident on the fθ lens 14 by driving the galvanometer mirror 12X. In this example, the galvanometer scanner 13X moves the irradiation position of the laser light L in the X-axis direction by rotating the galvanometer mirror 12X within a specific range of deflection angles.

[0016] In this example, the laser light L from the laser oscillator 11 is incident on the galvanometer mirror 12Y, and the laser light L from the galvanometer mirror 12Y is incident on the galvanometer mirror 12X, but it is also possible to have the laser light L from the laser oscillator 11 incident on the galvanometer mirror 12X, and the laser light L from the galvanometer mirror 12X incident on the galvanometer mirror 12Y.

[0017] The fθ lens 14 is a lens that condenses the laser light L reflected by the galvanometer mirror 12X and irradiates the laser light L perpendicularly onto the workpiece W.

[0018] The table 15 carries the workpiece W to be drilled, and is movable by a table drive mechanism in a direction parallel to the mounting surface, i.e., in at least one of the X-axis direction and the Y-axis direction. The table drive mechanism has an X-axis direction drive mechanism and a Y-axis direction drive mechanism. At least one of the X-axis direction drive mechanism and the Y-axis direction drive mechanism is driven in accordance with a position command, thereby changing the position of the table 15 within the XY plane.

[0019] The movable range of the galvanometer mirrors 12Y, 12X by driving the galvanometer scanners 13Y, 13X, i.e., the change in the irradiation position of the laser light L in the X-axis and Y-axis directions by the galvanometer mirrors 12Y, 12X, is limited to an extremely narrow range. For this reason, it is difficult to drill holes throughout the entire workpiece W simply by changing the irradiation position of the galvanometer mirrors 12Y, 12X by driving the galvanometer scanners 13Y, 13X. Therefore, after machining within the movable range of the galvanometer mirrors 12Y, 12X by driving the galvanometer scanners 13Y, 13X is completed, the position of the workpiece W is changed using the table 15, and machining is performed again within the movable range of the galvanometer mirrors 12Y, 12X by driving the galvanometer scanners 13Y, 13X. This allows drilling to be performed throughout the entire workpiece W.

[0020] The table 15 has a fixing mechanism. In the example of FIG. 1 , the fixing mechanism is a suction mechanism. That is, the suction mechanism has a plurality of suction holes 151 provided in the table 15 and a vacuum pump (not shown) connected to the suction holes 151 via piping or the like. By operating the vacuum pump, the workpiece W placed on the mounting surface of the table 15 is vacuum-sucked and fixed. Note that the fixing mechanism is not limited to a suction mechanism, and may be any mechanism capable of fixing the workpiece W. In one example, the workpiece W may be fixed to the table 15 by a clamping mechanism.

[0021] The camera 16 captures an image of an alignment mark provided for measurement of the workpiece W fixed on the table 15. The camera 16 outputs the captured image data to the control device 20.

[0022] The control device 20 has a programming tool 21 that generates a machining program from through-hole position data having position data indicating the positions of through-holes to be formed in the workpiece W, and a numerical control (NC) device 22 that controls the operations of the laser oscillator 11, the galvano scanners 13Y and 13X, the table drive mechanism of the table 15, etc. based on the machining program. The control device 20 is connected to the laser oscillator 11, the galvano scanners 13Y and 13X, the table 15, and the camera 16 via wiring 18.

[0023] The programming tool 21 reads the through-hole position data and generates a machining program in a format that can be read by the NC device 22 so that holes are drilled at the positions specified by the through-hole position data. The NC device 22 generates a position command for the table 15, a laser output command for the laser oscillator 11, and a position command for the galvanometer scanners 13Y and 13X. The position command for the table 15 is output to a drive mechanism for driving the table 15 in the X-axis direction and a drive mechanism for driving the table 15 in the Y-axis direction. The laser output command is output to the laser oscillator 11. The position commands for the galvanometer scanners 13Y and 13X are output to the galvanometer scanners 13Y and 13X.

[0024] When laser processing a workpiece W that is larger than the scanning area SA that can be scanned by only the galvanometer mirrors 12Y and 12X, the scanning area SA that can be scanned by only the galvanometer mirrors 12Y and 12X is defined as one section, and multiple scanning areas SA are set on the workpiece W. After the settings are made, the galvanometer mirrors 12Y and 12X are controlled to scan the laser light L in one scanning area SA to perform hole processing, and then the table 15 is controlled to move to the next scanning area SA and perform hole processing, and this processing of forming holes is repeated to process the entire workpiece W.

[0025] Here, we will explain drilling using the laser processing method described in Patent Document 1 and the problems associated with it. When drilling a workpiece W, material constituting the workpiece W is removed from the portion of the workpiece W where the hole is drilled, so stress is generated in the workpiece W toward the center of the hole. This stress acts in a direction that causes the workpiece W to shrink toward the center of the hole. Although the stress generated by a single hole is minute, when more than 100,000 holes are laser-machined in the workpiece W, the number of holes in the entire workpiece W increases, and the sum of all the stresses generated by the numerous holes becomes a non-negligible value. Therefore, when drilling fine holes, the impact of shrinkage of the workpiece W becomes greater.

[0026] When drilling holes in the workpiece W, the programming tool 21 converts through-hole position data, which lists the position data of holes to be laser-machined, into a machining program in a format readable by the NC device 22. The NC device 22 also reads this machining program and corrects the positions of the holes using correction information generated based on alignment marks measured using the camera 16, and controls the laser light L to irradiate the corrected positions. If the workpiece W shrinks and changes shape during laser machining, the positions of the alignment marks measured before machining will shift as the workpiece W shrinks, resulting in a discrepancy between the coordinates where the holes should be drilled as written in the machining program and the coordinates on the workpiece W where the holes are actually to be drilled. This results in the production of defective workpieces W with misaligned machining positions.

[0027] When a large number of machined holes are present in the central portion of the workpiece W, shrinkage occurs in the central portion, resulting in a large degree of deformation near the periphery of the workpiece W. On the other hand, when a large number of machined holes are present near the periphery of the workpiece W, shrinkage occurs near the periphery but the central portion of the workpiece W does not shrink, and as a result, the degree of shrinkage of the entire workpiece W is suppressed compared to when a large number of machined holes are present in the central portion of the workpiece W.

[0028] The technology described in Patent Document 1 solves the problem of shrinkage of the workpiece W that occurs when forming multiple holes in the workpiece W. FIG. 2 shows an example of the arrangement of scanning areas and the processing sequence in a conventional laser processing method. For ease of explanation, the number of holes 51 shown here is smaller than the actual number. This also applies to the following examples. In the laser processing method described in Patent Document 1, first, a scanning area SA61 that can be scanned only by the galvanometer mirrors 12Y and 12X is set at the corner of the outermost periphery of the workpiece W. Next, a scanning area SA62 that can be scanned only by the galvanometer mirrors 12Y and 12X is sequentially set at the outermost periphery, i.e., along the path Pa. This corresponds to the first circumferential processing. After laser processing of the outermost periphery is completed, a scanning area SA63 that can be scanned only by the galvanometer mirrors 12Y and 12X is set inside the outermost periphery, and scanning areas SA that can be scanned only by the galvanometer mirrors 12Y and 12X are sequentially set along the path Pb inside the outermost periphery. This corresponds to the second round of orbital machining. After laser machining one area inside the outermost periphery is completed, a scanning area SA64 that can be scanned only by the galvanometer mirrors 12Y and 12X is set two areas inside the outermost periphery, and scanning areas SA that can be scanned only by the galvanometer mirrors 12Y and 12X are sequentially set along the path Pc two areas inside the outermost periphery. This corresponds to the third round of orbital machining. In this way, by sequentially setting the scanning areas SA from the outermost periphery of the workpiece W to the inside and performing multiple orbital machining, the above-mentioned sudden and partial shrinkage of the workpiece W can be suppressed, and it is possible to suppress the positional deviation of the processed hole 51 from the target position to be drilled in the workpiece W that occurs before and after the shrinkage of the workpiece W.

[0029] For the back surface, starting from the scanning area SA on the back surface of the workpiece W, which is located in the same position as the scanning area SA61 on the front surface of the workpiece W, circular machining is performed on the outermost periphery in the order of path Pa as viewed from the back surface, so that machined holes are formed in the same order as on the front surface. Then, circular machining is similarly performed from the outermost periphery toward the inside. This causes the positions of the machined holes 51 formed on the front surface to match the positions of the machined holes formed on the back surface, resulting in the formation of through holes.

[0030] In recent years, the number of through holes formed in a workpiece W has exceeded 3 million, with reports of over 9 million holes. When the number of through holes is approximately 1.3 million to 1.5 million, the technology described in Patent Document 1 can accurately form the through holes. However, when forming through holes exceeding 1.3 million to 1.5 million using the technology described in Patent Document 1, the workpiece W warps when the formation of the holes 51 on the front surface is completed. FIG. 3 is a diagram showing an example of the state of the workpiece W after the holes are formed using conventional technology. As shown in FIG. 3, when more than 1.3 million to 1.5 million holes 51 are formed on the front surface Wf, which is the processing surface, the front surface Wf shrinks in the in-plane direction relative to the back surface Wb, causing warpage.

[0031] Furthermore, even if the warped workpiece W is fixed on the table 15 with a clamp or the like to suppress the warp and process the back surface Wb, the positional deviation between the machined holes 51 formed on the front surface Wf and the machined holes formed on the back surface Wb becomes large, making it impossible to form through holes with high accuracy. For this reason, when the number of through holes to be formed in the workpiece W exceeds 1.3 million to 1.5 million holes, there has been a demand for a technology that suppresses warping when processing one side is completed and that improves the accuracy of the positions at which the machined holes are formed on the front surface Wf and the back surface Wb.

[0032] Therefore, in the laser processing method and laser processing machine 10 according to the first embodiment, the through-hole position data, which indicates the positions at which through holes are to be formed, is divided into m pieces of divided hole position data so that the number of holes formed per unit area is equal to or less than the reference hole number, and the holes are dispersed throughout the entire processing surface of the workpiece W. The laser processing for forming holes on the front and back surfaces is then performed m times, where m is an integer of 2 or greater. The reference hole number is the maximum number of holes formed by the laser processing machine 10 without warping the workpiece W and with the positional deviation of the holes formed on the front and back surfaces within the tolerance range. The reference hole number may vary depending on the characteristics of the workpiece W, such as the material, size, and thickness. Therefore, the reference hole number may be determined for each characteristic of the workpiece W. Alternatively, if the type of workpiece W to be machined by the laser processing machine 10 is predetermined, the workpiece W with the smallest standard number of holes among the types to be machined may be adopted as the standard number of holes for the laser processing machine 10, regardless of the characteristics of the workpiece W. The standard number of holes may be, for example, 1.5 million holes. The standard density is the value obtained by dividing the standard number of holes by the area of ​​the front or back surface, which is the processing surface of the workpiece W. Like the standard number of holes, the standard density may also vary depending on the characteristics of the workpiece W, such as the material, size, and thickness, and therefore a standard density may be determined for each characteristic of the workpiece W. Alternatively, if the type of workpiece W to be machined by the laser processing machine 10 is predetermined, the workpiece W with the smallest standard density among the types to be machined may be adopted as the standard density for the laser processing machine 10, regardless of the characteristics of the workpiece W.

[0033] 4 is a diagram for explaining an overview of the laser processing method according to the first embodiment. The through-hole position data D0 includes position data that indicates the position of a through-hole to be formed in the workpiece W. In one example, the through-hole position data D0 is a list of position data in which the position of the through-hole is indicated using XY coordinates set on the table 15. The processing image I0 is an image that schematically shows the state in which a processed hole 51 has been drilled in the workpiece W in accordance with the through-hole position data D0.

[0034] Here, it is assumed that the through-hole position data D0 contains position data for the number of processed holes 51 that exceeds the reference number of holes. For this reason, when the through-hole position data D0 is used to form processed holes 51 on one processing surface of the workpiece W with the technology described in Patent Document 1, warping occurs in the workpiece W, and when double-sided processing is performed, misalignment occurs between the positions of the processed holes 51 on the front and back surfaces, making it impossible to perform processing as shown in the processing image I0.

[0035] Therefore, the through-hole position data D0 is divided into multiple data so as to satisfy the following conditions A and B: A. The number of holes 51 formed in one hole forming process is equal to or less than the reference number of holes that will prevent warping of the workpiece W and will cause the positional deviation of the holes 51 formed on both sides to be within the error range. B. The holes 51 formed in one hole forming process are distributed over the entire working surface of the workpiece W.

[0036] In B, it is sufficient to confirm by visual inspection or observation using a magnifying device such as a microscope that the machined holes 51 are dispersed throughout the entire machining surface of the workpiece W. This only requires that it be confirmed that the machined holes 51 are not concentrated in a specific area, but it is also possible to confirm by calculation that the machined holes 51 are dispersed throughout the entire machining surface of the workpiece W.

[0037] In the example of Figure 4, the through hole position data D0 is divided into three divided machining hole position data D1-D3. Machining image I1 is an image that schematically shows the state in which a machined hole 51 is formed in a workpiece W using the divided machining hole position data D1 according to the technology described in Patent Document 1. Machining image I2 is an image that schematically shows the state in which a machined hole 51 is formed in a workpiece W using the divided machining hole position data D2 according to the technology described in Patent Document 1. Machining image I3 is an image that schematically shows the state in which a machined hole 51 is formed in a workpiece W using the divided machining hole position data D3 according to the technology described in Patent Document 1.

[0038] Using the divided machining hole position data D1, machined holes 51 are formed on the front surface of the workpiece W, and then machined holes 51 are formed on the back surface using divided machining hole position data whose positions are mirror images of the positions formed by the divided machining hole position data D1. At this time, since the number of position data for machined holes 51 included in the divided machining hole position data D1 is equal to or less than the reference hole number, the workpiece W is not warped by this machining, and through holes can be formed in which the positional deviation of the machined holes 51 formed on the front and back surfaces is within the error range.

[0039] Next, using the divided machining hole position data D2, machined holes 51 are formed on the front surface of the workpiece W in which through holes have been formed using the divided machining hole position data D1. Thereafter, machined holes 51 are formed on the back surface using divided machining hole position data whose positions are mirror images of the positions formed by the divided machining hole position data D2. At this time, since the number of position data for machined holes 51 included in the divided machining hole position data D2 is less than the reference hole number, the workpiece W will not be warped by this machining, and through holes can be formed in which the positional deviation of the machined holes 51 formed on the front and back surfaces is within the error range. Note that the machining image I2 only shows machined holes 51 corresponding to the position data included in the divided machining hole position data D2.

[0040] Then, using the divided machining hole position data D3, machined holes 51 are formed on the front surface of the workpiece W in which through holes have been formed using the divided machining hole position data D1 and D2. Then, machined holes 51 are formed on the back surface using divided machining hole position data whose positions are mirror images of the positions formed by the divided machining hole position data D3. Since the number of position data for machined holes 51 included in the divided machining hole position data D3 is less than or equal to the reference hole number, the workpiece W is not warped by this machining, and through holes can be formed in which the positional deviation of the machined holes 51 formed on the front and back surfaces is within the tolerance range. Note that the machining image I3 only shows machined holes 51 corresponding to the position data included in the divided machining hole position data D3.

[0041] In this way, by machining both sides of the workpiece W using the divided machining hole position data D1, machining both sides of the workpiece W using the divided machining hole position data D2, and machining both sides of the workpiece W using the divided machining hole position data D3, a workpiece W is obtained that has through holes in excess of the standard number of holes as shown in the machining image I0, while suppressing the occurrence of warping and ensuring that the positional deviation of the machining holes 51 formed on both sides is within the error range.

[0042] A laser processing machine 10 according to a first embodiment that can perform laser processing using this method will now be described. As described above, the process of generating divided processing hole position data for the front and back surfaces from the through-hole position data and controlling the laser oscillator 11, galvanometer scanners 13Y, 13X, and table 15 is performed by the control device 20 of the laser processing machine 10 shown in Figure 1. Below, the functions of the programming tool 21 and NC device 22 of the control device 20 will be described in more detail. Note that it is assumed here that the through-hole position data includes position data for a number of holes that exceeds the reference number.

[0043] The programming tool 21 divides the through hole position data to generate divided machining hole position data, and generates a divided machining program, which is a machining program for drilling, for each of the generated divided machining hole position data.

[0044] 5 is a diagram showing an example of the functional configuration of a programming tool for the laser processing machine according to embodiment 1. The programming tool 21 has a data reading unit 211, a data dividing unit 212, a back surface processing data generating unit 213, and a processing program generating unit 214.

[0045] The data reading unit 211 reads through-hole position data. The data reading unit 211 may read the through-hole position data from a storage unit (not shown) of the control device 20, or may read the data via a communication line such as a network, or may read the data from a storage medium such as a memory card. The through-hole position data is, for example, text data in which position data indicating the position on the XY coordinate system where the through-hole is to be formed is recorded. Although not shown in FIG. 4 , the through-hole position data also has header information indicating the position data of an alignment mark provided on the workpiece W. The through-hole position data indicates design position data, and for example, is generated using the XY coordinate system provided on the table 15.

[0046] The data dividing unit 212 divides the position data in the through hole position data into a plurality of divided machining hole position data for the front surface of the workpiece W so that the number of through holes per unit area is equal to or less than a reference density, specifically, so that the number of position data is equal to or less than a predetermined reference number of holes, and so that the positions indicated by the position data are dispersed throughout the entire machining surface of the workpiece W. The front surface corresponds to the first machining surface. In one example, when m is an integer equal to or greater than 2, the data dividing unit 212 divides the position data in the through hole position data into m divided machining hole position data so that the positions indicated by the position data for each of the plurality of divided machining hole position data are dispersed throughout the entire machining surface of the workpiece W. Here, the number of position data included in each of the m divided machining hole position data is the quotient when the number of all position data of the through hole position data is divided by m, or this quotient plus "1." Furthermore, the data dividing unit 212 divides the position data in the through hole position data into m pieces of divided machining hole position data so that the density of the machining holes 51 formed in the scanning area SA in the machining hole forming process using one piece of divided machining hole position data is 1 / m of the density of the through holes ultimately formed on the machining surface. Here, it is not necessary for the density to be 1 / m exactly, as long as it is 1 / m within the margin of error. In this way, the data dividing unit 212 generates divided machining hole position data for the front surface.

[0047] Specifically, the data dividing unit 212 calculates a quotient by dividing the number of position data in the through-hole position data by the number of reference holes. If there is no remainder, this quotient is used as the division number m. If there is a remainder, the quotient is added by "1" to obtain the division number m. As shown in FIG. 4 , the data dividing unit 212 generates m divided machining hole position data from the first divided machining hole position data to the mth divided machining hole position data. The m divided machining hole position data generated here include only header information and do not include position data. Next, the data dividing unit 212 divides the position data in the through-hole position data into m equal parts so that, in one example, the density of machining holes 51 in a certain scanning area SA formed by the m divided machining hole position data is 1 / 3 of the hole density of the through holes on the machining surface formed by the through-hole position data. In one example, the data dividing unit 212 divides the position data in the through hole position data in the order of arrangement, from the first divided machining hole position data to the mth divided machining hole position data, such that the first position data is the first divided machining hole position data, the second position data is the second divided machining hole position data, ..., the mth position data is the mth divided machining hole position data, the (m+1)th position data is the first divided machining hole position data, ... In other words, when the through hole position data includes text data listing position data indicating the coordinates of the through holes, the data dividing unit 212 divides the position data in the through hole position data into m divided machining hole position data in order from the top. As a result, m divided machining hole position data are obtained.

[0048] Before generating the through-hole position data, the data dividing unit 212 may sort the included position data according to at least one of the X and Y coordinates. By dividing the sorted through-hole position data into m groups, the positions of the machined holes 51 can be dispersed within the machined surface of the workpiece W.

[0049] The back surface machining data generation unit 213 generates split machining hole position data for the back surface using the split machining hole position data for the front surface generated by the data division unit 212. For through holes formed in the workpiece W at positions indicated by the through hole position data, the positions of the through holes when the front surface is the upper surface and the positions of the through holes when the back surface is the upper surface are mirror images. Therefore, by specifying the size and shape of the workpiece W, split machining hole position data for the back surface can be obtained by mirroring the split machining hole position data for the front surface. In other words, the back surface machining data generation unit 213 generates split machining hole position data for the back surface opposite the front surface, including position data indicating positions that are mirror images of the positions indicated by the included position data for each of the multiple split machining hole position data for the front surface. The back surface corresponds to the second machining surface. The back surface machining data generation unit 213 also corresponds to the second machining surface machining data generation unit.

[0050] The machining program generation unit 214 converts each of the plurality of divided machining hole position data for the front surface and the back surface into a divided machining program, which is a computer program in a format that enables the NC device 22 to perform drilling using the laser machining machine 10. That is, the machining program generation unit 214 generates a divided machining program that controls the operation of the laser oscillator 11, the galvanometer scanners 13Y, 13X, and the table 15 so that machined holes 51 are formed by irradiating the laser light L at the positions of the position data included in the divided machining hole position data. The divided machining program generated at this time is a program that sets a plurality of scanning areas SA, which are ranges that can be scanned by the galvanometer mirrors 12Y, 12X, within the machining surface of the workpiece W, as described in FIG. 2 , and executes a machined hole forming process on the machining surface of the workpiece W by moving the table 15 to move the scanning area SA each time drilling within one scanning area SA is completed, so that the orbital path of the scanning area SA revolving in a direction parallel to the outer periphery of the machining surface of the workpiece W moves from the outer periphery toward the inside of the machining surface of the workpiece W. The machining program generation unit 214 is realized by a tool generally called CAD (Computer Aided Design) conversion. Hereinafter, one of the m divided machining programs will be referred to as the i-th divided machining program, where i is an integer between 1 and m. Furthermore, the divided machining programs for the front and back surfaces will be referred to as divided machining programs when there is no need to distinguish them individually.

[0051] The NC device 22 reads the division processing program generated by the programming tool 21 and controls the operations of the laser oscillator 11, the galvano scanners 13Y and 13X, and the table 15. The processing order in the NC device 22 is such that the ith division processing program for the front surface is executed first, followed by the ith division processing program for the back surface, in the order of the division number i from "1" to "m".

[0052] Before executing the divided machining program, the NC device 22 captures an image of the machining surface of the workpiece W using the camera 16 and generates first correction information using the positions of multiple alignment marks provided on the workpiece W in the captured image data. The first correction information is information indicating a deviation of the state of the machining surface of the workpiece W fixed on the table 15 from a design value. In one example, the alignment marks are provided at the four corners of the machining surface of the workpiece W. In one example, the NC device 22 uses the four alignment marks to calculate the length of the machining surface of the workpiece W based on the alignment marks, the angular deviation of the XY coordinate system provided on the machining surface of the workpiece W when viewed from the XY coordinate system provided on the table 15, and the offset amount of the origin of the XY coordinate system provided on the machining surface of the workpiece W from the origin of the XY coordinate system provided on the table 15. Then, the NC device 22 uses these as first correction information to correct the coordinates of the machining hole 51 that are read when the divided machining program is executed, and generates a position command for the table 15, a laser output command for the laser oscillator 11, and a position command for the galvanometer scanners 13Y and 13X.

[0053] Next, a laser processing method according to embodiment 1 will be described. The laser processing method according to embodiment 1 is generally a method for forming a through hole in a workpiece W using a laser processing machine 10 that performs drilling by scanning a laser beam L emitted from a laser oscillator 11 with galvanometer mirrors 12Y and 12X and focusing the laser beam L on the workpiece W placed on a table 15. The laser processing method according to embodiment 1 also includes a first hole forming step in which a hole forming process is performed on the front surface of the workpiece W, in which the table 15 is moved to move the scanning area SA so that the scanning area SA, which can be scanned by the galvanometer mirrors 12Y and 12X, revolves in a direction parallel to the outer periphery of the processing surface of the workpiece W, and the scanning area SA moves from the outer periphery toward the inside of the workpiece W each time drilling within one scanning area SA is completed, and a second hole forming step in which the hole forming process is performed on the back surface opposite the front surface. The first and second machined hole forming steps are then performed multiple times so that the positions of the through holes connected to the machined holes 51 formed by a set of the first and second machined hole forming steps are different. Also, the first and second machined hole forming steps may be performed alternately.

[0054] Next, the laser processing method will be described in detail. Figures 6 to 8 are flowcharts showing an example of the procedure of the laser processing method according to embodiment 1. Note that when the number of position data included in the through-hole position data is equal to or less than the reference number of holes, processing is possible using the laser processing method according to conventional technology, so a description of this will be omitted. Here, an example will be described in which the number of position data included in the through-hole position data exceeds the reference number of holes.

[0055] First, the programming tool 21 reads through-hole position data including position data indicating the positions of through-holes to be formed in the workpiece W (step S11), and the programming tool 21 determines the number of divisions m of the through-hole position data (step S12). In one example, the programming tool 21 obtains a quotient by dividing the number of position data pieces in the through-hole position data by the number of reference holes, and determines the quotient as the number of divisions m if there is no remainder, or determines the number of divisions m by adding "1" to the quotient if there is a remainder. Next, m pieces of divided machining hole position data for the front surface are generated, each including header information of the through-hole position data but not including position data (step S13).

[0056] Thereafter, the programming tool 21 distributes all position data included in the through hole position data into m divided machining hole position data for the front surface (step S14). At this time, the programming tool 21 distributes the positions indicated by the position data so that they are distributed over the entire machining surface of the workpiece W, so that the positions indicated by the position data are not concentrated in a particular region within the machining surface. In one example, the through hole position data is distributed into m divided machining hole position data for the front surface, starting from the first position data included in the through hole position data. The above steps S12 to S14 correspond to a data dividing step of dividing the through hole position data into a plurality of divided machining hole position data for the front surface so that the number of through holes per unit area is equal to or less than a reference density, specifically, so that the number of position data is equal to or less than a predetermined reference number of holes, and so that the positions of the through holes are distributed over the entire machining surface.

[0057] Thereafter, the programming tool 21 generates a front surface division machining program for each of the generated m front surface division machining hole position data (step S15). Here, a plurality of scanning areas SA, which are ranges that can be scanned by the galvanometer scanners 13Y and 13X, are set within the machining surface of the workpiece W, and the m front surface division machining programs are generated in which a machining hole formation process is performed on the machining surface of the workpiece W by moving the table 15 to move the scanning area SA each time drilling within one scanning area SA is completed, so that the circular path that rotates the scanning area SA in a direction parallel to the outer periphery of the machining surface of the workpiece W moves from the outer periphery side toward the inside of the machining surface of the workpiece W.

[0058] Next, the programming tool 21 generates m pieces of split machining hole position data for the back surface using the m pieces of split machining hole position data for the front surface (step S16). Specifically, for each of the m pieces of split machining hole position data for the front surface, the programming tool 21 generates split machining hole position data for the back surface, which has position data indicating positions that are mirror images of the positions indicated by the split machining hole position data for the front surface. At this time, the position data in the split machining hole position data for the back surface are arranged in the same order as the corresponding position data in the split machining hole position data for the front surface. The process of step S16 corresponds to a second surface machining data generating process.

[0059] Thereafter, the programming tool 21 generates a rear surface divided machining program for each of the m rear surface divided machining hole position data generated (step S17). In one example, a plurality of scanning areas SA are set within the machining surface of the workpiece W, and a rear surface divided machining program is generated in which a machining hole forming process is performed on the machining surface of the workpiece W by moving the table 15 each time drilling within one scanning area SA is completed, so that the circulating path for the scanning area SA circulating in a direction parallel to the outer periphery of the machining surface of the workpiece W moves from the outer periphery toward the inside of the machining surface of the workpiece W. However, with regard to the order of circulating machining, the scanning areas SA are moved on the rear surface onto which the scanning areas SA in the circulating machining of the front surface are projected in the same order as the circulating machining of the scanning areas SA on the front surface.

[0060] Next, the workpiece W is placed on the table 15 and fixed thereon (step S18). The upper surface in this state is the front surface of the workpiece W. The workpiece W may be placed by an operator, or the workpiece W may be placed on the table 15 from a storage container by a loader (not shown).

[0061] The NC device 22 sets the number of executions i to "1" (step S19). Thereafter, the NC device 22 captures an image of the workpiece W with the camera 16 (step S20), and generates first correction information using the alignment marks of the workpiece W in the captured image data (step S21). The first correction information is information that represents the deviation of the state of the machined surface of the actual workpiece W fixed on the table 15 from the state of the machined surface of an ideal workpiece W fixed on the table 15 assumed in design.

[0062] The NC unit 22 reads the i-th divided machining program for the front surface (step S22). In this case, since i=1, the first divided machining program for the front surface is read.

[0063] Then, the NC device 22 performs hole forming processing to form machined holes 51 by irradiating the front surface of the workpiece W with laser light L while correcting the position of the i-th divided machining program for the front surface using the first correction information (step S23). The process of step S23 corresponds to a first machined hole forming process that performs machined hole forming processing using the divided machined hole position data for the front surface. As a result, about 1 / m number of machined holes 51 corresponding to the number of machining data included in the through hole position data are formed in the front surface of the workpiece W. At this time, circular machining along the outer periphery of the machining surface of the workpiece W is performed sequentially from the outermost periphery toward the inside.

[0064] Thereafter, the workpiece W on the table 15 is turned over and fixed (step S24). As a result, the upper surface of the workpiece W on the table 15 becomes the underside. The workpiece W may be turned over by an operator. Alternatively, the workpiece W may be stored in a storage container from the table 15 by an unloader (not shown), the storage container may be turned upside down, and the storage container may be moved to a loader, after which the loader may place the turned-over workpiece W from the storage container onto the table 15.

[0065] Next, the NC device 22 captures an image of the workpiece W with the camera 16 (step S25), and generates first correction information using the alignment marks of the workpiece W in the captured image data (step S26). The first correction information generated in step S21 is used when executing the i-th divided machining program for the front surface in step S23, and is overwritten by the first correction information generated in step S26.

[0066] Thereafter, the NC device 22 reads the i-th divided machining program for the back surface (step S27). In this case, since i=1, the first divided machining program for the back surface is read. The i-th divided machining program for machining the back surface is a program for forming a machining hole 51 from the back surface at the same position on the back surface as the machining hole 51 formed on the front surface.

[0067] Then, the NC device 22 performs hole forming processing to form machined holes 51 by irradiating the back surface of the workpiece W with laser light L while correcting the position of the i-th divided machining program for the back surface using the first correction information (step S28). At this time, on the back surface onto which the scanning area SA in the circular machining of the front surface is projected, laser machining is performed while moving the scanning area SA in the same order as the circular machining of the scanning area SA on the front surface. In one example, the machined holes 51 are formed on the back surface in the order in which the machined holes 51 are formed on the front surface. As a result, approximately 1 / m of the number of machined holes 51 corresponding to the number of machining data included in the through-hole position data are formed on the back surface of the workpiece W. The process of step S28 corresponds to a second machined hole forming process in which machined hole forming processing is performed using the divided machined hole position data for the back surface.

[0068] As described above, since the number of machining data included in the divided machining hole position data is equal to or less than the reference hole number, the workpiece W does not warp due to this machining, and misalignment between the machined holes 51 formed on the front surface and the machined holes 51 formed on the back surface is suppressed. Therefore, a through hole is formed at a desired position, connecting the machined holes 51 formed on the front surface and the machined holes 51 formed on the back surface.

[0069] Next, the NC device 22 adds "1" to the number of executions i (step S29) and checks whether all the divided machining programs have been executed (step S30). That is, it determines whether the number of executions i is greater than the number of divisions m. If all the divided machining programs have not been executed, that is, if the number of executions i is equal to or less than the number of divisions m (No in step S30), the workpiece W on the table 15 is turned over and fixed (step S31). As a result, the upper surface of the workpiece W on the table 15 becomes the front surface. The workpiece W may be placed by an operator. Alternatively, the workpiece W may be stored in a storage container from the table 15 by an unloader, the storage container may be turned upside down, the storage container may be moved to the loader, and the workpiece W may then be placed on the table 15 by the loader.

[0070] Thereafter, the process returns to step S20. Then, the processes from step S20 to step S31 are repeatedly executed until all the division machining programs are executed in step S30, that is, until the number of executions i becomes larger than the division number m. In other words, the machining hole forming process on the front surface and the machining hole forming process on the back surface are executed alternately, and through holes are formed at positions different from the positions formed previously.

[0071] If all the divided machining programs have been executed in step S30, that is, if the number of executions i is greater than the number of divisions m (if Yes in step S30), all the divided machining programs have been executed for the front and back surfaces, and the workpiece W is removed from the table 15 (step S32). The workpiece W may be removed by an operator, or may be stored in a storage container from the table 15 by an unloader. This completes the laser machining method.

[0072] 9 to 14 show an example of the procedure of the laser machining method according to the first embodiment. Here, the through-hole position data is divided into three divided machining hole position data, and the machining hole formation process on the front and back surfaces is performed three times. First, as shown in FIG. 9 , a first divided machining program for the front surface forms a machining hole 51 on the front surface Wf of the workpiece W at a position corresponding to the first divided machining hole position data. Here, machining starts from a scanning area SA1F located around the outermost corner of the workpiece W. After the laser beam L finishes scanning within the scanning area SA1F, the table 15 is moved along the path Pa so that the laser beam L irradiates the next scanning area SA2F. In this way, of the multiple scanning areas SA set on the machining surface of the workpiece W, the outermost scanning area SA is sequentially subjected to circular machining in a direction parallel to the outer periphery of the machining surface, i.e., along the path Pa.

[0073] After forming the machining hole 51 in the scanning area SA at the outermost periphery, the table 15 is moved to perform circular machining along the path Pb for the scanning area SA one area inside the outermost periphery. In this example, machining starts from scanning area SA3F, and when scanning of the laser light L within scanning area SA3F is completed, the table 15 is moved along the path Pb so that the laser light L is irradiated onto the next scanning area SA. Then, of the multiple scanning areas SA set on the machining surface of the workpiece W, circular machining is performed sequentially for the scanning area SA one area inside the outermost periphery in a direction parallel to the outer periphery of the machining surface, i.e., along the path Pb.

[0074] After forming the machining hole 51 in the scanning area SA located one position inside the outermost periphery, the table 15 is moved to perform circular machining along the path Pc for the scanning areas SA located two positions inside the outermost periphery. In this example, machining starts from scanning area SA4F, and when scanning of the laser light L within scanning area SA4F is completed, the table 15 is moved along the path Pc so that the laser light L is irradiated onto the next scanning area SA. Then, of the multiple scanning areas SA set on the machining surface of the workpiece W, circular machining is performed in sequence for the scanning areas SA located two positions inside the outermost periphery in a direction parallel to the periphery of the machining surface, i.e., along the path Pc.

[0075] In this way, circular machining along the outer periphery of the workpiece W is performed sequentially from the outer periphery toward the inside of the workpiece W. Any shrinkage of the workpiece W caused by circular machining of the outermost periphery occurs only in the outermost periphery, and does not affect the inside of the workpiece W. As a result, in laser machining that starts from a scanning area SA3F that is one area inward from the outermost periphery to be laser-machined next, and sequentially performs circular machining one area inward from the outermost periphery while rotating in the circumferential direction along path Pb, there is no discrepancy between the coordinates of the holes to be drilled as written in the machining program and the coordinates of the workpiece W where the holes are actually to be drilled. Similarly, in laser machining that starts from a scanning area SA4F that is even further inward from the next scanning area to be laser-machined next, and sequentially performs circular machining further inward along path Pc while rotating in the circumferential direction, there is no discrepancy between the coordinates of the holes to be drilled as written in the machining program and the coordinates of the workpiece W where the holes are actually to be drilled.

[0076] After laser processing of the front surface Wf of the workpiece W according to the first divided processing program for the front surface is completed, laser processing of the back surface Wb of the workpiece W is performed according to the first divided processing program for the back surface. As shown in Figure 10, laser processing is performed in the following order: circular processing, starting from scanning area SA1B on the back surface Wb of the workpiece W, which is located in the same position as scanning area SA1F on the front surface Wf, and moving the scanning area SA along path Pma; circular processing, starting from scanning area SA3B on the back surface Wb, which is located in the same position as scanning area SA3F on the front surface Wf, and moving the scanning area SA along path Pmb; and circular processing, starting from scanning area SA4B on the back surface Wb, which is located in the same position as scanning area SA4F on the front surface Wf, and moving the scanning area SA along path Pmc. As a result, the processed hole 51 formed on the front surface Wf and the processed hole 51 formed on the back surface Wb are connected, forming a through hole.

[0077] When laser processing of the back surface Wb of the workpiece W according to the first divided processing program for the back surface is completed, laser processing is performed on the front surface Wf of the workpiece W according to the second divided processing program for the front surface. As shown in Fig. 11, laser processing is performed in the following order: starting from scanning area SA1F on the front surface Wf of the workpiece W, circular processing is performed by moving scanning area SA along path Pa, starting from scanning area SA3F, circular processing is performed by moving scanning area SA along path Pb, and starting from scanning area SA4F, circular processing is performed by moving scanning area SA along path Pc.

[0078] After laser processing of the front surface Wf of the workpiece W according to the second divided processing program for the front surface is completed, laser processing of the back surface Wb of the workpiece W is performed according to the second divided processing program for the back surface. As shown in Fig. 12, laser processing is performed in the following order: starting from scanning area SA1B on the back surface Wb of the workpiece W, circular processing is performed by moving scanning area SA along path Pma; starting from scanning area SA3B, circular processing is performed by moving scanning area SA along path Pmb; and starting from scanning area SA4B, circular processing is performed by moving scanning area SA along path Pmc. As a result, the processed hole 51 formed on the front surface Wf and the processed hole 51 formed on the back surface Wb are connected, forming a through hole.

[0079] When laser processing of the back surface Wb of the workpiece W according to the second divided processing program for the back surface is completed, laser processing is performed on the front surface Wf of the workpiece W according to the third divided processing program for the front surface. As shown in Fig. 13, laser processing is performed in the following order: starting from scanning area SA1F on the front surface Wf of the workpiece W, circular processing is performed by moving scanning area SA along path Pa, starting from scanning area SA3F, circular processing is performed by moving scanning area SA along path Pb, and starting from scanning area SA4F, circular processing is performed by moving scanning area SA along path Pc.

[0080] After laser processing of the front surface Wf of the workpiece W according to the third divided processing program for the front surface is completed, laser processing of the back surface Wb of the workpiece W is performed according to the third divided processing program for the back surface. As shown in Fig. 14, laser processing is performed in the following order: starting from scanning area SA1B on the back surface Wb of the workpiece W, circular processing is performed by moving scanning area SA along path Pma; starting from scanning area SA3B, circular processing is performed by moving scanning area SA along path Pmb; and starting from scanning area SA4B, circular processing is performed by moving scanning area SA along path Pmc. As a result, the processed hole 51 formed on the front surface Wf and the processed hole 51 formed on the back surface Wb are connected, forming a through hole.

[0081] As described above, the shrinkage of the workpiece W caused by the circular machining of the outermost periphery occurs only in the outermost periphery, and the shrinkage does not affect the inner side of the workpiece W. As a result, in the next circular machining of a portion one step inward from the outermost periphery to be laser-machined, there is no deviation between the coordinates at which the hole should be drilled as written in the machining program and the coordinates on the workpiece W at which the hole is actually drilled. Similarly, in the next circular machining of a portion two steps inward from the outermost periphery to be laser-machined, there is no deviation between the coordinates at which the hole should be drilled as written in the machining program and the coordinates on the workpiece W at which the hole is actually drilled. In other words, by sequentially setting the scanning area SA from the outermost periphery of the workpiece W to the inner side and performing multiple circular machining operations, it is possible to suppress the positional deviation of the machined hole 51 from the target position at which the hole is to be drilled in the workpiece W, which occurs before and after the shrinkage of the workpiece W caused by the drilling.

[0082] Furthermore, since the drilling process is performed a number of times equal to or less than the reference number of holes when performing a single hole forming process, warping does not occur in the workpiece W after the hole forming process is completed. Furthermore, since the hole forming process on the back surface Wb of the workpiece W, which did not cause warping and was able to suppress shrinkage during the hole forming process on the front surface Wf, drills a number of holes equal to or less than the reference number of holes, warping does not occur in the workpiece W after the hole forming process is completed. Furthermore, by repeatedly performing the process of drilling a number of holes equal to or less than the reference number of holes, it is possible to finally form the desired number of through holes in the desired positions.

[0083] 15 is a diagram illustrating a case where laser processing is performed by simply dividing through-hole position data into three parts using conventional technology. Consider a case where the position data in the through-hole position data D10 is divided at positions that are one-third and two-thirds of the way from the beginning to generate divided machining hole position data D11, D12, and D13. That is, the position data from the beginning to one-third of the way through the through-hole position data D10 is divided machining hole position data D11, the position data from the beginning to two-thirds of the way through the through-hole position data D10 is divided machining hole position data D12, and the position data from the beginning to two-thirds of the way through the through-hole position data D10 is divided machining hole position data D13.

[0084] In this case, as shown in machining image I11, the machining holes 51 specified by the divided machining hole position data D11 are distributed in region R11 of the machining surface of the workpiece W. As shown in machining image I12, the machining holes 51 specified by the divided machining hole position data D12 are distributed in region R12 of the machining surface of the workpiece W. As shown in machining image I13, the machining holes 51 specified by the divided machining hole position data D13 are distributed in region R13 of the machining surface of the workpiece W. When the position data in the through hole position data D10 is divided in this manner, the machining holes 51 are not distributed over the entire machining surface of the workpiece W, making it impossible to use the technology described in Patent Document 1. Furthermore, when machining is performed using the divided machining hole position data D11, D12, and D13 divided in this manner, the machining holes 51 are concentrated in only specific regions, which causes the workpiece W to shrink significantly, making it impossible to form the desired number of through holes in the desired positions.

[0085] On the other hand, the laser processing method according to the first embodiment is a method for forming a through hole in a workpiece W using a laser processing machine 10 that performs drilling by scanning laser light L emitted from a laser oscillator 11 with galvanometer mirrors 12Y, 12X and focusing the laser light L on the workpiece W placed on a table 15, and includes a first machined hole forming process in which a machined hole forming process is performed on a first surface of the workpiece W, in which the table 15 is moved to move the scanning area SA each time drilling within one scanning area SA is completed, so that the circular path that moves the scanning area SA within the processing surface of the workpiece W in a direction parallel to the outer periphery of the workpiece W moves from the outer periphery side toward the inside of the workpiece W, and a second machined hole forming process in which the machined hole forming process is performed on a second surface opposite the first surface. The first and second machined hole forming processes are then performed multiple times so that the positions of the through holes connected to the machined holes 51 formed by a pair of the first and second machined hole forming processes are different. Specifically, when m is an integer greater than or equal to 2, the position data in the through hole position data is distributed into m divided machined hole position data so that the positions indicated by the position data for each of the multiple divided machined hole position data are distributed across the entire machined surface of the workpiece W. The number of position data included in each divided machined hole position data is set so that the number of machined holes 51 formed in one machined hole forming process is equal to or less than the reference number of holes that prevents warping of the workpiece W and ensures that the positional deviation of the machined holes 51 formed on both sides is within the error range. This achieves the effects of suppressing warping of the workpiece W after the formation of the machined holes 51 on one side and suppressing positional deviation of the machined holes 51 formed on the front and back surfaces Wb of the workpiece W compared to conventional methods.

[0086] Embodiment 2. When performing multiple revolutions as shown in FIG. 2, the amount of shrinkage of the workpiece W varies with each revolution. Therefore, if the amount of shrinkage varies significantly with each revolution, the machining position may be corrected by the amount of the shrinkage, using the galvanometer mirrors 12Y, 12X and the table 15, to account for the amount of positional deviation between the coordinates where the hole should be drilled as written in the machining program and the coordinates on the workpiece W where the hole is actually drilled. FIG. 16 is a diagram showing characteristic information representing an example of the relationship between the number of revolutions and the amount of positional deviation of the machined hole in the laser machining method according to embodiment 2. In FIG. 16, the horizontal axis represents the number of revolutions, and the vertical axis represents the amount of positional deviation. In FIG. 16, information indicating the relationship between the number of revolutions and the amount of positional deviation of the machined hole 51 is obtained for each execution number i and for each front and back surface in each execution number i. The NC device 22 refers to this Figure 16 to calculate the amount of positional deviation for each revolution and correct the machining position, so the information showing the relationship between the number of revolutions shown in Figure 16 and the amount of positional deviation of the machining hole 51 can be said to be second correction information.

[0087] The amount of shrinkage of the workpiece W varies depending on the type and thickness of the material. For this reason, it is advisable to acquire in advance as a database characteristic information representing the relationship between the number of revolutions and the amount of misalignment of the machined hole 51, as shown in Fig. 16, for each type and thickness of the material of the workpiece W. The relationship between the number of revolutions and the amount of misalignment of the machined hole 51 is calculated by actually laser processing the workpiece W and measuring the amount of shrinkage.

[0088] The laser processing method according to the second embodiment further includes a positional deviation measurement step of measuring, for each circular path, the amount of positional deviation caused by shrinkage of the workpiece W that occurs when drilling holes on the processing surface of the workpiece W while rotating the workpiece W, for each of the plurality of divided processing hole position data, for the front and back surfaces before the first processing hole forming step. Then, in the first processing hole forming step and the second processing hole forming step, the position data when performing the processing hole forming process using each of the plurality of divided processing hole position data is corrected by the corresponding positional deviation amount.

[0089] The specific processing sequence of the laser processing method according to the second embodiment is as follows. Figures 17 to 19 are diagrams schematically showing an example of the processing sequence of the laser processing method according to the second embodiment. As shown in Figure 17, first, the NC device 22 performs laser processing in accordance with the first divided processing hole position data for the front surface. At this time, the NC device 22 laser processes a scanning area SA221 located on the outermost periphery of the workpiece W and including one reference hole 52 serving as a reference, and the NC device 22 measures the position of the reference hole 52 with the position measurement camera 16. The reference hole 52 may be part of a product pattern within the scanning area SA21 located on the outermost periphery of the workpiece W where the processing hole 51 is actually drilled.

[0090] 18, when laser processing of scan area SA21 is completed, table 15 is moved to the next scan area SA located on the outermost periphery of workpiece W, and a first round of circular processing is performed along the outer periphery of the processing surface of workpiece W. As a result, a processed processing area PA is formed on the outermost periphery of workpiece W. When the first round of circular processing is completed, NC device 22 measures the position of reference hole 52 again with camera 16, compares the position measured by camera 16 before the first round of circular processing with the position measured by camera 16 after the first round of circular processing, and stores the difference, that is, the amount of positional deviation, as a correction value for the first round.

[0091] Once the machining area PA is formed on the outermost periphery of the workpiece W, as shown in FIG. 19 , a circular machining is performed one step inward from the outermost periphery. Similarly, in this case, a scanning area SA22, which is located inside the machining area PA machined on the outermost periphery of the workpiece W and includes a single reference hole 53 as a reference, is laser machined. The NC device 22 measures the position of the reference hole 53 using the position measurement camera 16. Then, a second circular machining is performed along the outer periphery of the machining surface of the workpiece W. After the second circular machining is completed, the NC device 22 again measures the position of the reference hole 53 using the camera 16 and stores the positional deviation, which is the difference between the positions measured by the camera 16 before and after the second circular machining, in the control device 20 as a correction value for the second circular machining. This process is then repeated each time a circular machining is performed. As a result, characteristic information representing the relationship between the number of circular machinings for the front surface of the first group and the positional deviation of the machined hole 51 is obtained.

[0092] By sequentially performing the above-described processing for the first round of the hole formation process on the front surface, the first round of the back surface, the second round of the front surface, the second round of the back surface, ..., the mth round of the front surface, and the mth round of the back surface, characteristic information is obtained that represents the relationship between the number of turns on each surface and the amount of misalignment of the hole 51. The characteristic information that represents the relationship between the number of turns on the front surface and the back surface from the first to mth rounds and the amount of misalignment of the hole 51 is compiled into the second correction information shown in FIG.

[0093] Acquisition of such characteristic information representing the relationship between the number of revolutions and the amount of positional deviation of the machining hole 51 is performed, for example, during laser machining of the first workpiece W. Then, when laser machining of the second or subsequent workpiece W is performed after completion of laser machining of the first workpiece W, the NC device 22 does not measure the positions of the reference holes 52, 53 with the camera 16, but performs revolution machining while correcting the position of the i-th divided machining program using the first correction information and second correction information acquired during laser machining of the first workpiece W.

[0094] In the laser processing method according to the second embodiment, since the amount of shrinkage of the workpiece W varies depending on the type and thickness of the material, second correction information, which is characteristic information representing the relationship between the number of revolutions and the amount of misalignment of the hole 51 for each type and thickness of the material of the workpiece W, is acquired by actually laser processing the workpiece W for each of the front and back surfaces that are divided and machined. In one example, the characteristic information representing the relationship between the number of revolutions and the amount of misalignment of the hole 51 is acquired when the first workpiece W is laser processed. Then, when laser processing the second or subsequent workpiece W, the second correction information, i.e., the amount of misalignment of the hole 51 for the number of revolutions on the corresponding machining surface, is used as a correction value for the laser processing. In this way, by performing position correction due to shrinkage of the workpiece W using the characteristic information representing the relationship between the number of revolutions and the amount of misalignment of the hole 51, it is possible to further suppress misalignment of the hole 51 relative to the target position of the workpiece W that occurs before and after shrinkage of the workpiece W.

[0095] Embodiment 3. In the laser processing method according to embodiment 2, the first workpiece W is laser processed to acquire second correction information including characteristic information representing the relationship between the number of revolutions and the amount of misalignment of the holes 51 for each type of material and thickness of the workpiece W, and when laser processing the second or subsequent workpieces W, the second correction information is used to perform revolution processing. In embodiment 2, even if the material, thickness, and number of through holes to be formed are the same as those of a previous workpiece W, the process of acquiring second correction information is performed for the first workpiece W. If it is experimentally known that the second correction information is substantially the same for workpieces W of the same material, thickness, and number of through holes to be formed, the already acquired second correction information can be used.

[0096] In the laser processing method according to the third embodiment, second correction information having characteristic information representing the relationship between the number of revolutions corresponding to the type of material, thickness, and number of through holes of the workpiece W on which laser processing has been previously performed and the amount of positional deviation of the processed holes 51 is stored as a database in the control device 20. That is, in the positional deviation amount measuring step of the laser processing method according to the third embodiment, the measured amount of positional deviation is stored in association with the material, thickness, and number of through holes to be formed in the workpiece W, and in the first processed hole forming step and the second processed hole forming step, the positional deviation amount corresponding to the material, thickness, and number of through holes to be formed in the workpiece W is used to correct the positional data when performing the processed hole forming process.

[0097] 20 is a diagram schematically illustrating an example of the configuration of a laser processing machine according to embodiment 3. Note that the same components as those described in embodiment 1 are assigned the same reference numerals, and their description will be omitted. In the laser processing machine 10 according to embodiment 3, the control device 20 further includes a second correction information storage unit 23. As described above, the second correction information storage unit 23 stores second correction information associated with the type of material of the workpiece W, its thickness, and the number of through holes to be formed.

[0098] When laser processing is performed, if second correction information for a workpiece W having the same material type, thickness, and through holes is stored in the second correction information storage unit 23, the NC device 22 acquires this second correction information and applies it during laser processing. This makes it possible to suppress positional deviation of the processed hole 51 from the target position at which a hole is to be drilled in the workpiece W, which occurs before and after shrinkage of the workpiece W. Note that, when laser processing is next performed, if second correction information for a workpiece W having the same material type, thickness, and through holes is not stored in the second correction information storage unit 23, the NC device 22 executes the process described in the second embodiment and stores the obtained second correction information in the second correction information storage unit 23 in association with the material type, thickness, and number of through holes to be formed of the workpiece W.

[0099] In the laser processing machine 10 according to the third embodiment, second correction information associated with the type of material of the workpiece W, its thickness, and the number of through holes to be formed is stored in the second correction information storage unit 23. As a result, if the second correction information for the workpiece W that is the same as the type of material, thickness, and number of through holes to be formed is stored in the second correction information storage unit 23, there is no need to measure the amount of shrinkage of the workpiece W before processing. This reduces the time required to calculate the position correction due to shrinkage of the workpiece W, and also eliminates the need for the material of the workpiece W used to calculate the position correction due to shrinkage of the workpiece W, thereby enabling a reduction in material costs.

[0100] Next, hardware for realizing the control device 20 of the laser processing machine 10 according to the first to third embodiments will be described. The control device 20 is realized by a processing circuit. The processing circuit may be a circuit in which a processor executes software, or may be a dedicated circuit. When the processing circuit is realized by software, the processing circuit is, for example, a control circuit.

[0101] 21 is a diagram showing an example of the configuration of a control circuit that realizes the control device for a laser processing machine according to embodiments 1 to 3. The control circuit 100 includes an input unit 101, a processor 102, a memory 103, and an output unit 104. The input unit 101 is an interface circuit that receives data input from outside the control circuit 100 and provides the data to the processor 102. The output unit 104 is an interface circuit that sends data from the processor 102 or the memory 103 to outside the control circuit 100.

[0102] When the processing circuit is the control circuit 100 shown in FIG. 21 , the control device 20 is realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in memory 103. The processing circuit realizes each function of the control device 20 by having the processor 102 read and execute the program stored in memory 103. In other words, the processing circuit includes memory 103 for storing the program that results in the processing of the control device 20 being executed. It can also be said that these programs cause a computer to execute the procedures and methods of the control device 20.

[0103] The processor 102 is a central processing unit (CPU). The processor 102 may be a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or digital signal processor (DSP). The memory 103, for example, is a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM (registered trademark)), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a digital versatile disk (DVD).

[0104] 21 shows an example of hardware in which the control device 20 is realized by a general-purpose processor 102 and memory 103, but the control device 20 may also be realized by a dedicated hardware circuit. Also, the control device 20 may be realized by combining the control circuit 100 with a hardware circuit.

[0105] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0106] 10 Laser processing machine, 11 Laser oscillator, 12Y, 12X Galvanometer mirror, 13Y, 13X Galvanometer scanner, 14 fθ lens, 15 Table, 16 Camera, 18 Wiring, 20 Control device, 21 Programming tool, 22 NC device, 23 Second correction information storage unit, 51 Processing hole, 52, 53 Reference hole, 100 Control circuit, 101 Input unit, 102 Processor, 103 Memory, 104 Output unit, 151 Suction hole, 211 Data reading unit, 212 Data division unit, 213 Back surface processing data generation unit, 214 Processing program generation unit, D0, D10 Through hole position data, D1, D2, D3, D11, D12, D13 Split processing hole position data, I0, I1, I2, I3, I11, I12, I13 Processing image, L Laser light, PA: processing area, Pa, Pb, Pc, Pma, Pmb, Pmc: path, R11, R12, R13: area, SA, SA1B, SA1F, SA2F, SA3B, SA3F, SA4B, SA4F, SA21, SA61, SA62, SA63, SA64: scanning area, W: workpiece, Wb: back surface, Wf: front surface.

Claims

1. A laser processing method for forming a through hole in a workpiece using a laser processing machine that scans a laser beam emitted from a laser oscillator with a galvanometer mirror and focuses the laser beam on a workpiece placed on a table to perform a drilling process, the method comprising: a first machined hole forming step in which a machined hole forming process is performed on a first machined surface of the workpiece, the table being moved to move the scanning area each time drilling within one scanning area is completed, so that a circular path that causes a scanning area that can be scanned by the galvanometer mirror to circle in a direction parallel to the outer periphery of the machined surface of the workpiece moves from the outer periphery side toward the inside of the workpiece; and a second machined hole forming step in which the machined hole forming process is performed on a second machined surface opposite the first machined surface, the method being characterized in that the first machined hole forming step and the second machined hole forming step are performed multiple times so that the positions of the through holes connected to the machined holes formed by a pair of the first machined hole forming step and the second machined hole forming step are different.

2. The laser processing method according to claim 1, further comprising: a data dividing step of dividing through hole position data including position data indicating the positions of the through holes into a plurality of divided machining hole position data for the first machining surface so that the number of the through holes per unit area is equal to or less than a reference density; and a second surface machining data generating step of generating divided machining hole position data for the second machining surface having position data indicating a position that is a mirror image of the position indicated by the divided machining hole position data for the first machining surface for each of the plurality of divided machining hole position data for the first machining surface, wherein in the first machining hole forming step, the divided machining hole position data for the first machining surface is used to perform the machining hole forming process, and in the second machining hole forming step, the divided machining hole position data for the second machining surface is used to perform the machining hole forming process, and the first machining hole forming step and the second machining hole forming step are performed alternately.

3. The laser processing method described in claim 2, characterized in that in the data division step, when m is an integer greater than or equal to 2, the position data in the through hole position data is distributed into m pieces of divided processing hole position data so that the positions indicated by the position data for each of the multiple divided processing hole position data are distributed across the entire processing surface of the workpiece.

4. The laser processing method described in claim 3, characterized in that in the data division process, the position data is divided into the m divided processing hole position data so that the density of the processing holes formed in the scanning area in the first processing hole formation process and the second processing hole formation process is 1 / m of the density of the through holes finally formed on the processing surface.

5. The laser processing method described in claim 3, characterized in that the through hole position data includes text data in which the position data indicating the positions of the through holes are listed, and in the data division process, the position data in the through hole position data are divided into m divided processing hole position data in order from the beginning.

6. A laser processing method as described in any one of claims 2 to 5, characterized in that in the second surface processing data generation process, the position data in the divided processing hole position data for the second processing surface are arranged in the same order as the corresponding position data in the divided processing hole position data for the first processing surface.

7. A laser processing method according to any one of claims 2 to 6, characterized in that the reference density is a value obtained by dividing the maximum number of holes formed by drilling using the laser processing machine in such a way that no warping occurs in the workpiece and the positional deviation of the holes formed on the first processing surface and the second processing surface is within the error range by the area of ​​the first processing surface or the second processing surface of the workpiece.

8. A laser processing method according to any one of claims 2 to 7, further comprising a positional deviation measurement step for measuring the amount of positional deviation caused by shrinkage of the workpiece that occurs when drilling holes on the processing surface of the workpiece while rotating for each of the circular paths, for the first processing surface and the second processing surface for each of the plurality of divided processing hole position data before the first processing hole forming step, wherein in the first processing hole forming step and the second processing hole forming step, the position data when performing the processing hole forming process using each of the plurality of divided processing hole position data is corrected by the corresponding positional deviation amount.

9. The laser processing method of claim 8, wherein in the positional deviation amount measuring step, the measured positional deviation amount is stored in association with the material, thickness, and number of through holes formed in the workpiece, and in the first machined hole forming step and the second machined hole forming step, the position data when performing the machined hole forming process is corrected using the positional deviation amount corresponding to the material, thickness, and number of through holes formed in the workpiece to be machined.

10. A programming tool comprising: a data reading unit that reads through hole position data having position data indicating the positions of through holes to be formed in a workpiece; a data dividing unit that divides the position data in the through hole position data into a plurality of divided machining hole position data for a first machining surface of the workpiece so that the number of the through holes per unit area is equal to or less than a reference density; a second machining surface machining data generating unit that generates divided machining hole position data for a second machining surface opposite to the first machining surface, the divided machining hole position data including position data indicating a position that is a mirror image of the position indicated by the position data included in each of the plurality of divided machining hole position data for the first machining surface; and a machining program generating unit that converts each of the plurality of divided machining hole position data for the first machining surface and the second machining surface into a divided machining program in a format that can be used to perform hole drilling using a laser machining machine with a numerical control device.

11. The programming tool described in claim 10, characterized in that the through hole position data includes text data in which the position data is listed, and the data dividing unit distributes the position data in the through hole position data sequentially from the beginning into each of the multiple divided machining hole position data for the first machining surface.

12. A programming tool as described in claim 10 or 11, characterized in that the reference density is a value obtained by dividing the maximum number of holes formed by drilling using the laser processing machine in such a way that no warping occurs in the workpiece and the positional deviation of the holes formed on the first processing surface and the second processing surface is within the error range by the area of ​​the first processing surface or the second processing surface of the workpiece.

13. A laser processing machine comprising: a laser oscillator that emits the laser light; a galvanometer mirror that is driven by a galvanometer scanner and scans the laser light; a table on which a workpiece that is the target of the hole drilling is placed and which is movable in a direction parallel to the placement surface by a table drive mechanism; and a control device that controls the operation of the laser oscillator, the galvanometer scanner, and the table drive mechanism in accordance with the laser processing method defined in any one of claims 1 to 9.

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