Laser processing method and laser processing apparatus
By controlling the irradiation position and cross-sectional shape of the laser beam, combined with a galvanometer scanner and an fθ lens, the problem of inconsistent hole shapes in laser processing was solved, achieving circular processing of workpiece holes and improving processing accuracy and consistency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UHT CORP
- Filing Date
- 2021-07-12
- Publication Date
- 2026-06-16
AI Technical Summary
In existing laser processing methods, astigmatism of the laser beam causes circular holes to form on the upper surface of the workpiece, while elliptical holes are formed on the lower surface, making it impossible to guarantee the consistency of hole shape.
By controlling the irradiation position and cross-sectional shape of the laser beam, combined with a galvanometer scanner and an fθ lens, the laser beam can be made to change along a circular or elliptical trajectory in the depth direction of the workpiece, forming a circular hole that penetrates the workpiece.
This method ensures that the shape of the workpiece hole is circular throughout the entire axial direction, eliminating the shape inconsistency problem caused by astigmatism and improving machining accuracy and consistency.
Smart Images
Figure CN113953690B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a laser processing method and a laser processing apparatus for forming holes in a workpiece by using a laser beam for perforation. Background Technology
[0002] Conventional laser processing methods include, for example, the method disclosed in Japanese Patent Application Publication No. 2007-38287. In such a laser processing method, the laser beam, having a circular cross-section, is positioned so that its irradiation position coincides with the upper surface of the workpiece, causing the laser beam to orbit along a circular path. This forms a circular hole in the workpiece.
[0003] However, laser beams exhibit astigmatism. Therefore, the position on the optical axis where the longitudinal beam width is minimized differs from the position on the optical axis where the transverse beam width is minimized. Consequently, when using the laser processing method described above, the cross-sectional shape of the laser beam is circular on the upper surface of the workpiece, but elliptical on the lower surface. Therefore, the resulting hole is also circular on the upper surface of the workpiece, but elliptical on the lower surface, rather than circular. Summary of the Invention
[0004] The purpose of this invention is to provide a laser processing method and a laser processing apparatus capable of forming a circular shape of a hole formed on a workpiece throughout the entire axial direction of the hole.
[0005] To address the aforementioned issues, one aspect of the present invention provides a laser processing method in which a laser beam is irradiated onto a workpiece's processing surface, and a hole is formed by perforation while varying the irradiation position of the laser beam on the processing surface. In this method, based on the cross-sectional shape of the laser beam corresponding to the depth of the processing surface, the irradiation position of the laser beam on the processing surface is varied along a circular orbit around the hole formed on the processing surface at the depth. Attached Figure Description
[0006] Figure 1 This is a schematic structural diagram of a laser processing apparatus according to one embodiment.
[0007] Figure 2 This is a schematic three-dimensional diagram showing the change in the cross-sectional shape of the laser beam.
[0008] Figure 3 It is shown Figure 2 A schematic diagram of the XY cross-sectional shape of the laser beam at various positions.
[0009] Figure 4A This is a side sectional view showing the state of machining the upper surface of a workpiece using a laser beam.
[0010] Figure 4B It is shown Figure 4A A top view of the shape and trajectory of the electron beam spot of the laser beam at that time.
[0011] Figure 5A This is a side sectional view showing the state of machining the vertical central part of a workpiece using a laser beam.
[0012] Figure 5B It is shown Figure 5A A top view of the shape and trajectory of the electron beam spot of the laser beam at that time.
[0013] Figure 6A This is a side sectional view showing the state of machining the lower surface of a workpiece using a laser beam.
[0014] Figure 6B It is shown Figure 6A A top view of the shape and trajectory of the electron beam spot of the laser beam at that time.
[0015] Figure 7 It is a top view showing the positional relationship between the electron beam spot and the elliptical orbit when the electron beam spot of the laser beam is elliptical.
[0016] Figure 8A This is a top view showing the orbits of multiple circles when the electron beam spot is circular in the modified example.
[0017] Figure 8B This is a top view showing the vortex-shaped trajectory when the electron beam spot is circular.
[0018] Figure 9A This is a top view showing the orbits of multiple circles when the electron beam spot is elliptical in the modified example.
[0019] Figure 9B This is a top view showing the vortex-shaped trajectory when the electron beam spot is elliptical.
[0020] Figure 10A This is a top view showing the orbits of multiple circles when the electron beam spot is elliptical in the modified example.
[0021] Figure 10B This is a top view showing the vortex-shaped trajectory when the electron beam spot is elliptical. Detailed Implementation
[0022] Hereinafter, one embodiment of the laser processing apparatus will be described with reference to the accompanying drawings.
[0023] like Figure 1As shown, the laser processing apparatus 11 irradiates a laser beam LB onto the processing surface 12 of the workpiece W, and forms a hole 13 (see reference) by performing a perforation process while changing the irradiation position of the laser beam LB on the processing surface 12. Figure 6A ).
[0024] The laser processing apparatus 11 includes: a support platform 14 supporting a plate-shaped workpiece W having a processing surface 12; an fθ lens 15 with a telecentric optical path disposed directly above the support platform 14; a galvano-scanner 16, which is an example of an irradiation direction changing unit, disposed directly above the fθ lens 15; a laser oscillator 17 disposed to the side of the galvano-scanner 16; and a control unit 18.
[0025] The laser oscillator 17 causes the laser beam LB to oscillate relative to the horizontal machining surface 12 of the upper surface of the workpiece W, which is disposed on the support stage 14, via the galvanometer scanner 16 and the fθ lens 15. The galvanometer scanner 16 is configured to include two rotatable mirrors (not shown). By coordinating the rotation of the two mirrors (not shown), the galvanometer scanner 16 causes the irradiation position of the laser beam LB oscillating from the laser oscillator 17 to vary two-dimensionally on the machining surface 12 of the workpiece W.
[0026] The fθ lens 15 corrects the direction of the laser beam LB reflected by the galvanometer scanner 16 to be perpendicular to the machining surface 12 of the workpiece W. The workpiece W is, for example, constructed from a substrate made of synthetic resin.
[0027] like Figure 2 and Figure 3 As shown, the optical axis of the laser beam LB is defined as the Z direction, and two directions orthogonal to and mutually orthogonal to the Z direction are defined as the X and Y directions. In this case, the laser beam LB oscillating from the laser oscillator 17 has different divergence angles in the X and Y directions. Therefore, the laser beam LB exhibits astigmatism. Consequently, the laser beam LB has a portion with an elliptical cross-sectional shape and a portion with a circular cross-sectional shape. Figure 3 Show Figure 2 The XY cross-sectional shape of the laser beam LB at positions A to E.
[0028] Regarding the XY cross-sectional shape of the laser beam LB, it is an ellipse with the smallest width in the Y direction at position B, an ellipse with the smallest width in the X direction at position D, and a circle at position C, which is the middle between positions B and D. In the laser processing apparatus 11, the position C where the cross-sectional shape of the laser beam LB is circular coincides with the processing surface 12 of the upper surface of the workpiece W.
[0029] Therefore, the cross-sectional shape of the laser beam LB changes from a circle to an ellipse along the Z direction from the upper surface of the workpiece W, and the flatness of the ellipse gradually increases as it advances further towards the lower surface of the workpiece W. That is, in the laser processing apparatus 11, as an example, a hole 13 (see reference 13) is formed in the workpiece W at positions C to D of the laser beam LB. Figure 6A ).
[0030] Next, the electrical structure of the laser processing device 11 will be described.
[0031] like Figure 1 As shown, the control unit 18 is configured, for example, to include a microcomputer and a memory for storing various information, and centrally controls the laser processing apparatus 11. The control unit 18 is electrically connected to the laser oscillator 17 and the galvanometer scanner 16 respectively, and controls the laser oscillator 17 and the galvanometer scanner 16 respectively.
[0032] like Figure 1 and Figures 4A to 6B As shown, when a hole 13 is formed on the machining surface 12 of the workpiece W using a laser beam LB, the control unit 18 controls the galvanometer scanner 16 in such a way that the irradiation position of the laser beam LB in the machining surface 12 varies on a single circular track K1 or a single elliptical track K2, K3, where the hole 13 formed on the machining surface 12 at that depth is circular, based on the cross-sectional shape of the laser beam LB corresponding to the depth of the workpiece W.
[0033] In this case, the control unit 18 controls the galvanometer scanner 16 by having the electron beam spot BS of the laser beam LB repeatedly orbit a single circular track K1 or a single elliptical track K2, K3. The information of the single circular track K1 and the information of the single elliptical track K2, K3 are pre-stored in the control unit 18.
[0034] The control unit 18 determines the depth of the machined surface 12, measured from the upper surface of the workpiece W, based on the number of times the electron beam spot BS in the machined surface 12 of the workpiece W orbits a single circular orbit K1 or a single elliptical orbit K2 or K3. The relationship between the number of times the electron beam spot BS in the machined surface 12 of the workpiece W orbits a single circular orbit K1 or a single elliptical orbit K2 or K3 and the depth of the machined surface 12, measured from the upper surface of the workpiece W, is determined in advance through experiments, simulations, etc., and stored in the control unit 18.
[0035] In three stages—when the machining surface 12 is located at the upper part WA of the workpiece W, when the machining surface 12 is located at the middle part WB of the workpiece W, and when the machining surface 12 is located at the lower part WC of the workpiece W—the control unit 18 switches the orbit around the electron beam spot BS of the laser beam LB to a circular orbit K1, an elliptical orbit K2, or an elliptical orbit K3. The upper part WA, the middle part WB, and the lower part WC of the workpiece W all become the same thickness.
[0036] That is, when the machining surface 12 is located at the upper part WA of the workpiece W, the electron beam spot BS in the machining surface 12 is circular. Therefore, the control unit 18 makes the electron beam spot BS revolve around a single circular track K1 by forming a circular hole 13 in the machining surface 12. Furthermore, when the machining surface 12 is located at the middle part WB of the workpiece W, the electron beam spot BS in the machining surface 12 becomes elliptical. Therefore, the control unit 18 makes the electron beam spot BS revolve around a single elliptical track K2 corresponding to this elliptical shape by forming a circular hole 13 in the machining surface 12.
[0037] Furthermore, when the machining surface 12 is located at the lower part WC of the workpiece W, the electron beam spot BS becomes an elliptical shape with a larger flatness ratio than when the machining surface 12 is located at the middle part WB of the workpiece W. Therefore, the control unit 18 causes the electron beam spot BS to revolve on a single elliptical orbit K3 corresponding to this elliptical shape by forming a circular hole 13 on the machining surface 12.
[0038] Figure 7 The diagram illustrates a case where the electron beam spot BS is elliptical and orbits within the processing surface 12 on a single elliptical orbit K2, K3. In this case, the major axis J1 of the elliptical electron beam spot BS and the major axis J2 of the single elliptical orbit K2, K3 around which the electron beam spot BS orbits are always orthogonal to each other.
[0039] Next, the function of the laser processing device 11 in forming a hole 13 in the workpiece W will be explained.
[0040] like Figure 1 , Figure 4A and Figure 4B As shown, when forming a hole 13 on a workpiece W using a laser processing apparatus 11, a laser beam LB is first irradiated onto the processing surface 12 on the upper surface of the workpiece W. At this time, the shape of the electron beam spot BS of the laser beam LB on the processing surface 12 is circular.
[0041] Next, as Figure 4A and Figure 4B As shown, the electron beam spot BS is made to orbit around a single circular track K1 in the machining surface 12. Thus, in the upper part WA of the workpiece W, the machining surface 12 is gradually carved into a circle by the laser beam LB. Furthermore, through the laser beam LB, the machining surface 12 gradually descends, and a circular hole 13 begins to form in the upper part WA of the workpiece W.
[0042] Next, as the electron beam spot BS repeatedly orbits along a single circular track K1 within the machining surface 12, the machining surface 12 is further lowered while being shaped into a circle. Furthermore, when the machining surface 12 reaches the center WB of the workpiece W, a circular hole 13 with a depth equivalent to the thickness of the upper WA is formed in the upper WA of the workpiece W. At this point, the shape of the electron beam spot BS of the laser beam LB in the machining surface 12 becomes elliptical.
[0043] Next, as Figure 5A and Figure 5B As shown, the electron beam spot BS is made to orbit a single elliptical orbit K2 in the machining surface 12. Thus, at the center WB of the workpiece W, the machining surface 12 is gradually shaped into a circle by the laser beam LB. Furthermore, through the laser beam LB, the machining surface 12 gradually descends, and a circular hole 13 begins to form at the center WB of the workpiece W.
[0044] Next, as the electron beam spot BS repeatedly orbits along a single elliptical orbit K2 within the machining surface 12, the machining surface 12 is further lowered while being shaped into a circle. Furthermore, when the machining surface 12 reaches the lower part WC of the workpiece W, a circular hole 13 with a depth equivalent to the thickness of the middle part WB is formed in the middle part WB of the workpiece W. At this point, the shape of the electron beam spot BS of the laser beam LB in the machining surface 12 becomes an elliptical shape with a higher flatness ratio than when it is located in the middle WB.
[0045] Next, as Figure 6A and Figure 6B As shown, the electron beam spot BS is directed to orbit a single elliptical orbit K3 within the machining surface 12. Thus, at the lower part WC of the workpiece W, the machining surface 12 is gradually shaped into a circle by the laser beam LB. Furthermore, the laser beam LB causes the machining surface 12 to gradually descend, forming a circular hole 13 at the lower part WC of the workpiece W.
[0046] Next, as the electron beam spot BS repeatedly orbits along a single elliptical orbit K3 within the machining surface 12, the machining surface 12 is further lowered while being shaped into a circle. Furthermore, when the machining surface 12 reaches the lower surface of the workpiece W, a circular hole 13 with a depth equivalent to the thickness of the lower part WC is formed in the lower part WC of the workpiece W. Thus, a circular hole 13 is formed that penetrates the entire workpiece W. This hole 13 is circular from the upper surface to the lower surface of the workpiece W.
[0047] The diameter of the hole 13 formed through the workpiece W gradually decreases from the upper surface of the workpiece W toward the lower surface. This is so that, for example, when the hole 13 is formed in the lower part WC of the workpiece W, the circular hole 13 formed before the lower part WC but in the upper part WA and the middle part WB is not used to process the laser beam LB forming the hole 13 in the lower part WC into an elliptical shape.
[0048] Thus, in the laser processing apparatus 11, a laser beam LB, consisting of a portion with an elliptical cross-section and a portion with a circular cross-section, is used as is. Furthermore, the laser processing apparatus 11 performs a piercing process to form a hole 13 penetrating a workpiece W having a certain thickness. Even in this case, the shape of the hole 13 formed in the workpiece W can be made circular throughout the entire axial direction of the hole 13.
[0049] The following effects can be achieved according to the implementation methods described above.
[0050] (1) A laser processing apparatus 11 irradiates a laser beam LB onto the processing surface 12 of a workpiece W, and forms a hole 13 by performing a perforation process while changing the irradiation position of the laser beam LB in the processing surface 12. The laser processing apparatus 11 includes: a laser oscillator 17 that oscillates the laser beam LB relative to the processing surface 12 of the workpiece W; a galvanometer scanner 16 that changes the irradiation direction of the laser beam LB oscillating from the laser oscillator 17 in the processing surface 12; and a control unit 18 that controls the galvanometer scanner 16. The control unit 18 controls the galvanometer scanner 16 in a manner that changes the irradiation position of the laser beam LB in the processing surface 12 on a circular track K1 and elliptical tracks K2 and K3, which are circular in shape, based on the cross-sectional shape of the laser beam LB corresponding to the depth of the processing surface 12. According to this structure, based on the cross-sectional shape of the laser beam LB corresponding to the depth of the machining surface 12 of the workpiece W, the irradiation position of the laser beam LB in the machining surface 12 is varied on a circular orbit K1 and elliptical orbits K2 and K3, which are circular in shape, of the hole 13 formed on the machining surface 12 at that depth. Thus, the shape of the hole 13 formed on the workpiece W can be formed as circular throughout the entire axial direction of the hole 13.
[0051] (2) The trajectory by which the irradiation position of the laser beam LB in the processing surface 12 is changed by the laser processing device 11 is a single circular track K1 or a single elliptical track K2, K3. According to this structure, the shape of the hole 13 formed on the workpiece W can be easily and quickly formed into a circle throughout the entire axial direction of the hole 13.
[0052] (Example of Change)
[0053] The above-described embodiments can be implemented with the following modifications. Furthermore, the above-described embodiments and the following modifications can be combined and implemented within a technically compatible framework.
[0054] like Figure 8A As shown, the circular track K1 can also be changed into multiple (three in this example) circular tracks K4 of different sizes. Additionally, as... Figure 8B As shown, the circular track K1 can also be changed to a vortex-shaped track K5 formed by continuously connecting circular arcs.
[0055] Two or more of the circular track K1, circular track K4, and spiral track K5 can be combined. This allows the shape of the hole 13 formed in the workpiece W to be more precisely circular throughout the entire axial direction of the hole 13. Furthermore, when selecting the spiral track K5 as the track for changing the irradiation position of the laser beam LB in the machined surface 12, it is preferable to change the irradiation position of the laser beam LB in the machined surface 12 on the circular track K1 after changing the irradiation position on the spiral track K5. Typically, when changing the irradiation position of the laser beam LB in the machined surface 12 on the spiral track K5, a step 19 (see reference) may sometimes be formed on the inner surface of the hole 13 formed in the workpiece W. Figure 8B In this respect, according to this structure, by changing the irradiation position of the laser beam LB in the machining surface 12 on the vortex-shaped track K5 and then on the circular track K1, the step 19 formed on the inner surface of the hole 13 in the workpiece W can be eliminated.
[0056] like Figure 9A As shown, the elliptical orbit K2 can also be changed into multiple elliptical orbits K6 of different sizes (three in this example). Additionally, as... Figure 9B As shown, the elliptical orbit K2 can also be changed into a vortex orbit K7 formed by continuously connecting elliptical arcs.
[0057] Elliptical orbits K2 and K6, and spiral orbits K7 can be combined in combination. This allows the shape of the hole 13 formed in the workpiece W to be more precisely circular throughout its entire axial direction. Furthermore, when selecting the spiral orbital K7 as the orbital for changing the irradiation position of the laser beam LB in the machined surface 12, it is preferable to change the irradiation position of the laser beam LB in the machined surface 12 on the elliptical orbital K2 after changing it on the spiral orbital K7. Typically, when changing the irradiation position of the laser beam LB in the machined surface 12 on the spiral orbital K7, a step 20 (see reference) may sometimes form on the inner surface of the hole 13 formed in the workpiece W. Figure 9B In this respect, according to this structure, by changing the irradiation position of the laser beam LB in the machining surface 12 on the vortex-shaped orbit K7 and then on the elliptical orbit K2, the step 20 formed on the inner surface of the hole 13 in the workpiece W can be eliminated.
[0058] like Figure 10A As shown, the elliptical orbit K3 can also be changed into multiple (three in this example) elliptical orbits K8 of different sizes (flattening ratio). Figure 9A The elliptical orbit K6 is large. Additionally, such as... Figure 10BAs shown, the elliptical orbit K3 can also be changed to an elliptical arc (flattening ratio) Figure 9B The K9 is a vortex-shaped orbit formed by the continuous connection of large elliptical arcs.
[0059] Elliptical orbits K3 and K8, and vortex orbits K9 can be combined in combination. This allows the shape of the hole 13 formed in the workpiece W to be more precisely circular throughout its entire axial direction. Furthermore, when selecting the vortex orbital K9 as the orbital for changing the irradiation position of the laser beam LB in the machined surface 12, it is preferable to change the irradiation position of the laser beam LB in the machined surface 12 on the vortex orbital K9, and then change it on the elliptical orbital K3. Typically, when changing the irradiation position of the laser beam LB in the machined surface 12 on the vortex orbital K9, a step 21 (see reference) may sometimes form on the inner surface of the hole 13 formed in the workpiece W. Figure 10B In this respect, according to this structure, by changing the irradiation position of the laser beam LB in the machining surface 12 on the vortex-shaped orbit K9 and then on the elliptical orbit K3, the step 21 formed on the inner surface of the hole 13 in the workpiece W can be eliminated.
[0060] In the above embodiments, when hole 13 is formed in workpiece W, the orbit around the electron beam spot BS of laser beam LB is switched between circular orbit K1 and elliptical orbits K2 and K3 in the three stages of upper WA, middle WB and lower WC of workpiece W. However, the orbit around the electron beam spot BS of laser beam LB can also be switched between two or more stages.
[0061] When a hole 13 is formed on the machining surface 12 of the upper part WA of the workpiece W, the shape of the electron beam spot BS in the machining surface 12 can also be elliptical. In this case, it is sufficient to make the hole 13 circular by making the electron beam spot BS orbit on an elliptical orbit corresponding to the elliptical shape of the electron beam spot BS.
[0062] When a hole 13 is formed on the machined surface 12 of the middle part WB or the lower part WC of the workpiece W, the shape of the electron beam spot BS in the machined surface 12 can also be circular. In this case, it is sufficient to make the hole 13 circular by making the electron beam spot BS circle on a circular track.
[0063] The depth of the machined surface 12, measured from the upper surface of the workpiece W, can also be detected using a distance sensor.
[0064] The workpiece W can be made of metal.
Claims
1. A laser processing method comprising irradiating a laser beam onto a workpiece surface, and forming a hole by perforation while changing the irradiation position of the laser beam on the workpiece surface, wherein in the laser processing method, Based on the case where the cross-sectional shape of the laser beam is circular or elliptical corresponding to different depths of the processing surface, the shape of the orbit around which the laser beam is surrounded is controlled in such a way that the shape of the hole formed on the processing surface at the depth is circular, so that the irradiation position of the laser beam in the processing surface varies along the orbit.
2. The laser processing method according to claim 1, wherein, The track is at least one of the following: a single circular track or elliptical track, multiple circular tracks or elliptical tracks of different sizes, or a vortex track formed by continuously connecting circular or elliptical arcs.
3. The laser processing method according to claim 2, wherein, The position of the laser beam is changed on the vortex-shaped orbit and then on a single circular or elliptical orbit.
4. A laser processing apparatus that irradiates a laser beam onto a processing surface of a workpiece and forms a hole by perforation processing while changing the irradiation position of the laser beam on the processing surface, the laser processing apparatus comprising: A laser oscillator that causes the laser beam to oscillate relative to the machined surface of the workpiece; An irradiation direction changing section that changes the irradiation direction of the laser beam oscillating from the laser oscillator in the processed surface; and The control unit controls the irradiation direction change unit. The control unit is configured to control the shape of the orbit around which the laser beam revolves, based on whether the cross-sectional shape of the laser beam is circular or elliptical according to different depths of the processing surface, so that the shape of the hole formed on the processing surface at the depth is circular, and to control the irradiation direction changing unit in such a way that the irradiation position of the laser beam in the processing surface changes along the orbit.