A method for precise control of laser spiral scanning trajectory

Abstract

The invention discloses a method for precisely controlling a laser spiral scanning trajectory, which mainly solves the problem that the scanning trajectory of a spiral scanning processing head in the prior art is uneven and cannot be precisely controlled. In the process of laser spiral scanning, firstly, the upper deflection optical wedge and the lower deflection optical wedge are controlled to change speed at a final speed slightly greater than and slightly less than the parallel plate, respectively, so that the relative angle generated by the upper deflection optical wedge and the lower deflection optical wedge during the rotation process gradually increases, then the upper deflection optical wedge and the lower deflection optical wedge are controlled to change speed at a final speed slightly less than and slightly greater than the parallel plate, respectively, so that the relative angle generated by the upper deflection optical wedge and the lower deflection optical wedge during the rotation process gradually decreases to 0, and finally, the upper deflection optical wedge and the lower deflection optical wedge are controlled to change speed at a final speed slightly greater than and slightly less than the parallel plate, respectively, so that the relative angle generated by the upper deflection optical wedge and the lower deflection optical wedge during the rotation process gradually increases.

Description

Technical Field

[0001] The invention relates to a scanning trajectory precision control method, and in particular to a laser spiral scanning trajectory precision control method. Background Art

[0002] Due to the characteristics of laser processing such as no cutting stress, high precision, and flexibility, it has been widely used in aerospace, electronics and other fields, and it can achieve precision drilling of parts. Commonly used laser drilling mainly includes four drilling methods, namely: single pulse processing, percussion processing, circular cutting processing and spiral processing. Among them, the spiral processing method has obvious advantages over other processing methods due to its high micro-hole manufacturing precision and controllable taper. The commonly used spiral scanning laser processing head realizes the spiral movement of the laser on the surface of the material through the high-speed coordinated movement of the internal optical wedge device, thereby realizing micro-hole processing with controllable taper.

[0003] In the prior art, the commonly used laser spiral scanning processing device structure is as follows Figure 1 As shown, the laser 1, the reflector 2, the parallel plate 3, the upper deflection wedge 4, the lower deflection wedge 5, the focusing mirror 6, the motion mechanism 8, the laser processing head control unit 9, the laser control unit 10 and the spiral scanning laser processing head 11, wherein the motion relationship between the upper deflection wedge 4, the lower deflection wedge 5 and the parallel plate 3 is as shown in FIG. Figure 2 As shown in the figure (in which ΔP is position and T is time), the laser beam emitted by the spiral scanning laser processing head 11 forms a spiral scanning track with sparse inside and dense outside under the action of the above optical device (such as Figure 3 As shown in Figure 2), the depth of material removal at the bottom of the micropores is uneven (as shown in Figure 2). Figure 4 As shown in the figure, high-precision micro-hole processing cannot be achieved, and the processing efficiency is low. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the prior art that the spiral scanning trajectory is uneven, high-precision micro-hole processing cannot be achieved, and the processing efficiency is low, and to provide a method for precise control of the laser spiral scanning trajectory.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A laser spiral scanning trajectory precision control method is based on a laser spiral scanning processing device, and its special feature is that it is implemented according to the following steps:

[0007] Step 1, aligning the output end of the spiral scanning laser processing head with the predetermined drilling position, controlling the parallel plate, the upper deflection optical wedge, and the lower deflection optical wedge to rotate synchronously at the same initial rotation speed v1, wherein the initial rotation speed v1 ranges from 2000 rpm to 3000 rpm;

[0008] Step 2: Control the upper deflection wedge to rotate at the second speed v2 and the lower deflection wedge to rotate at the third speed v3 as the final speed, and v2>v1, v3<v1, v2-v1=v1-v3, v2=v1+(0.1-0.6)%v1, v3=v1-(0.1-0.6)%v1;

[0009] When the relative angle between the upper deflection wedge and the lower deflection wedge during the rotation increases to α, 65°≤α≤80°, the spiral scanning action of the laser beam from the minimum diameter to the maximum diameter is completed;

[0010] Step 3: When the laser beam is spirally scanned to the maximum diameter, the upper deflection optical wedge is controlled to rotate at the third speed v3 and the lower deflection optical wedge is controlled to rotate at the second speed v2 as the final speed;

[0011] When the relative angle between the upper deflection wedge and the lower deflection wedge during the rotation is reduced to 0°, the spiral scanning action of the laser beam from the maximum diameter to the minimum diameter is completed;

[0012] Step 4: When the laser beam is spirally scanned to the minimum diameter, the upper deflection wedge is controlled to rotate at the second speed v2 and the lower deflection wedge is controlled to rotate at the third speed v3 as the final speed;

[0013] When the relative angle between the upper deflection wedge and the lower deflection wedge during the rotation increases to α, the spiral scanning action of the laser beam from the minimum diameter to the maximum diameter is completed;

[0014] Step 5: Control the spiral scanning laser processing head to feed downward at a preset increment, and return to step 3 to process the next layer of microholes until the microhole processing of the preset depth is completed.

[0015] Furthermore, considering that the rated power of a general AC servo motor is 3000 rpm, in step 1, the first speed v1 is 3000 rpm.

[0016] Furthermore, considering the influence of the difference between the second speed and the third speed and the first speed on the density of the spiral scanning track, in step 2, step 3 and step 4, the second speed v2 is 3005 rpm; the third speed v3 is 2995 rpm.

[0017] Furthermore, in step 2 and step 4, the value of α is 72°.

[0018] Furthermore, according to the material of the processing object, in step five, the spiral scanning laser processing head is fed downward in increments of 0.01 mm each time.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] During the laser spiral scanning process, firstly, the upper deflection optical wedge and the lower deflection optical wedge are controlled to change speed at a final speed slightly greater than and slightly less than the parallel plate, respectively, so that the relative angle generated by the upper deflection optical wedge and the lower deflection optical wedge during the rotation process gradually increases; then, the upper deflection optical wedge and the lower deflection optical wedge are controlled to change speed at a final speed slightly less than and slightly greater than the parallel plate, respectively, so that the relative angle generated by the upper deflection optical wedge and the lower deflection optical wedge during the rotation process gradually decreases to 0; finally, the upper deflection optical wedge and the lower deflection optical wedge are controlled to change speed at a final speed slightly greater than and slightly less than the parallel plate, respectively, so that the relative angle generated by the upper deflection optical wedge and the lower deflection optical wedge during the rotation process gradually increases, thereby realizing precise control of the spiral trajectory during the laser spiral scanning process, obtaining a uniform laser spiral scanning trajectory, and during the processing of the microhole, the microhole is processed layer by layer according to the laser control method, and when the bottom of the microhole is processed, the material depth at the bottom of the microhole can be uniformly removed, thereby realizing high-precision microhole processing and improving the processing efficiency of the microhole. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an existing laser spiral scanning processing device;

[0022] Figure 2 It is a motion relationship diagram between the upper deflection optical wedge, the lower deflection optical wedge and the parallel plate in the existing spiral scanning laser processing head;

[0023] Figure 3 It is a schematic diagram of a spiral scanning trajectory generated by an existing spiral scanning processing head;

[0024] Figure 4 It is a schematic diagram of the depth distribution of the bottom of the micro-hole when the existing spiral scanning processing head performs micro-hole processing;

[0025] Figure 5 It is a schematic diagram of the motion relationship between the upper deflection optical wedge, the lower deflection optical wedge and the parallel plate in the spiral scanning laser processing head of the present invention;

[0026] Figure 6 Schematic diagram of the spiral scanning trajectory of the present invention.

[0027] In the figure, 1-laser, 2-reflecting mirror, 3-parallel plate, 4-upper deflection wedge, 5-lower deflection wedge, 6-focusing mirror, 7-workpiece, 8-movement mechanism, 9-laser processing head control unit, 10-laser control unit, 11-spiral scanning laser processing head. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1As shown, a laser spiral scanning processing device in the prior art includes a laser control unit 10, a laser processing head control unit 9, a laser 1, a reflector 2 arranged on the outgoing light path of the laser 1, a spiral scanning laser processing head 11 arranged on the reflected light path of the reflector 2, and a motion mechanism 8 connected to the spiral scanning laser processing head 11 (used to control the layer-by-layer feeding of the spiral scanning laser processing head 11 to process the micro-holes layer by layer, so as to ensure that the laser focus accurately acts on the surface of the workpiece during the processing);

[0030] Laser 1 is specifically a femtosecond laser with a wavelength of 1030nm, a laser power of 50mw~10w, a pulse width ≤190fs, and an adjustable repetition frequency of 1K~1MHz. It should be noted that the laser in this embodiment is only a preferred model, and those skilled in the art can reasonably select the laser in the prior art according to the processing requirements.

[0031] The spiral scanning laser processing head 11 includes a parallel plate 3, an upper deflection optical wedge 4, a lower deflection optical wedge 5 and a focusing lens 6 which are sequentially arranged along the optical path. The laser can act vertically on the workpiece 7 through the coordinated control of the parallel plate 3, the upper deflection optical wedge 4 and the lower deflection optical wedge 5, and the parallel plate 3, the upper deflection optical wedge 4 and the lower deflection optical wedge 5 can rotate respectively, so as to control the parallel plate 3, the upper deflection optical wedge 4 and the lower deflection optical wedge 5 to rotate at different speeds respectively; the parallel plate 3, the upper deflection optical wedge 4 and the lower deflection optical wedge 5 are driven by connecting AC servo motors respectively.

[0032] The laser processing head control unit 9 is electrically connected to the laser control unit 10, and controls the laser shutter in real time to achieve rapid switching light action. The laser processing head control unit 9 is electrically connected to the spiral scanning laser processing head 11, and can control the rotation of the parallel plate 3, the upper deflection optical wedge 4 and the lower deflection optical wedge 5, and can receive the rotation position feedback of the upper deflection optical wedge 4 and the lower deflection optical wedge 5, and fit the speed change process of the upper deflection optical wedge 4 and the lower deflection optical wedge 5.

[0033] In order to solve the problem of uneven scanning track of the existing spiral scanning processing head 11, the present invention proposes the following Figure 5 As shown in the figure (in which ΔP is position and T is time), the coordinated motion relationship between the parallel plate 3, the upper deflection wedge 4 and the lower deflection wedge 5 inside the spiral scanning laser processing head 11 is realized to realize a spiral scanning trajectory with uniform spacing (such as Figure 6 shown).

[0034] The present invention provides a laser spiral scanning trajectory precision control method, based on the above-mentioned laser spiral scanning processing device, and is specifically implemented according to the following steps:

[0035] Step 1: Align the output end of the spiral scanning laser processing head 11 with the predetermined punching position, and the laser processing head control unit 9 sends a command to control the parallel plate 3, the upper deflection wedge 4 and the lower deflection wedge 5 to rotate synchronously at the same initial rotation speed v1. In the field of laser processing, limited by the rated speed of the AC servo motor, the initial rotation speed v1 is generally controlled to be 2000-3000rpm, because the rated speed of the general AC servo motor is 3000rpm. Therefore, for the convenience of explanation, v1 is 3000rpm in this embodiment; however, because theoretically the higher the speed, the better the processing efficiency and processing quality, technical personnel in this field can also choose a servo motor with a higher rated speed for implementation.

[0036] Step 2: When the parallel plate 3, the upper deflection wedge 4 and the lower deflection wedge 5 all reach the first speed v1, the upper deflection wedge 4 is controlled to rotate at the second speed v2 and the lower deflection wedge 5 at the third speed v3 as the final speed, and the laser processing head control unit 9 is used to fit them as follows: Figure 5 The speed change process shown in the figure makes the motor driving the upper deflection wedge 4 and the lower deflection wedge 5 move more smoothly during the speed change to ensure the scanning accuracy of the spiral line. 2、 When the rotation speed difference of v3 is too large, the relative angle between the upper deflection wedge 4 and the lower deflection wedge 5 will increase too fast during the rotation process, which will cause the laser to change from the minimum diameter to the maximum diameter too fast, resulting in too few spiral scanning tracks. 2、 If the speed difference of v3 is too small, the relative angle between the upper deflection wedge 4 and the lower deflection wedge 5 will increase too fast during the rotation process, which will cause the speed of the laser changing from the minimum diameter to the maximum diameter to be too slow, resulting in too dense spiral scanning trajectory. Therefore, v1 and v3 are required to be 2、 The speed difference of v3 satisfies the following relationship: v2>v1, v3<v1, v2-v1=v1-v3, v2=v1+(0.1~0.6)%v1, v3=v1-(0.1~0.6)%v1. In this embodiment, v2=3005rpm and v3=2995rpm are used as examples.

[0037] When the relative angle generated by the upper deflection optical wedge 4 and the lower deflection optical wedge 5 during the rotation process increases to α, 65°≤α<80°. In this embodiment, α is 72°. In other embodiments of the present invention, α can be selected within a range to complete the spiral scanning action of the laser from the minimum diameter to the maximum diameter. In specific implementation, firstly, a target position is set for the upper deflection optical wedge 4 and the lower deflection optical wedge 5. This position is recorded as the maximum angle position or the minimum angle position of the upper deflection optical wedge 4 and the lower deflection optical wedge 5. An encoder is installed on the motor driving the upper deflection optical wedge 4 and the lower deflection optical wedge 5. The encoder records the rotation angle of the motor, thereby determining whether the upper deflection optical wedge 4 and the lower deflection optical wedge 5 have reached the target position, that is, reached the relative angle, and then completed a bolt scanning.

[0038] Step 3: When the laser reaches the maximum spiral scanning diameter, the upper deflection wedge 4 is controlled to rotate at the third speed v3 and the lower deflection wedge 5 is controlled to rotate at the second speed v2 as the final speed, and the upper deflection wedge 4 and the lower deflection wedge 5 are fitted as follows by the laser processing head control unit 9: Figure 5 The speed change process shown;

[0039] When the relative angle between the upper deflection wedge 4 and the lower deflection wedge 5 during the rotation is reduced to 0°, the spiral scanning action of the laser from the maximum diameter to the minimum diameter is completed;

[0040] Step 4: When the laser reaches the minimum spiral scanning diameter, the upper deflection wedge 4 is controlled to rotate at the second speed v2 and the lower deflection wedge 5 is controlled to rotate at the third speed v3 as the final speed, and the upper deflection wedge 4 and the lower deflection wedge 5 are fitted as follows by the laser processing head control unit 9: Figure 5 The speed change process shown;

[0041] When the relative angle between the upper deflection wedge 4 and the lower deflection wedge 5 during the rotation increases to α, the spiral scanning action of the laser from the minimum diameter to the maximum diameter is completed.

[0042] Step 5: Control the spiral scanning laser processing head 11 to feed downward at a preset increment, and return to step 3 to process the next layer of microholes, so as to ensure that the focus of the laser beam accurately acts on the surface of the workpiece 7 during the processing. In this embodiment, the bolt scanning laser processing head 11 is controlled to feed at an increment of 0.01 mm. It should be noted that the feed amount in this embodiment is only a preferred feed amount determined according to the processing object. Those skilled in the art can also determine the corresponding appropriate feed amount according to the processing object until the microhole processing of the preset depth is completed.

Claims

1. A laser spiral scanning trajectory precision control method, based on a laser spiral scanning processing device, characterized in that: Follow these steps to implement: Step 1: aligning the output end of the spiral scanning laser processing head (11) with a predetermined punching position, and controlling the parallel plate (3), the upper deflection optical wedge (4) and the lower deflection optical wedge (5) to move in coordination, thereby realizing a spiral scanning trajectory with uniform spacing; Controlling the parallel plate (3), the upper deflection optical wedge (4) and the lower deflection optical wedge (5) to rotate synchronously at the same initial rotation speed v1, wherein the initial rotation speed v1 ranges from 2000 rpm to 3000 rpm; Step 2, controlling the upper deflection optical wedge (4) to rotate at a second speed v2 and the lower deflection optical wedge (5) to rotate at a third speed v3 as the final speed, and v2>v1, v3<v1, v2-v1=v1-v3, v2=v1+(0.1-0.6)%v1, v3=v1-(0.1-0.6)%v1; When the relative angle between the upper deflection optical wedge (4) and the lower deflection optical wedge (5) during the rotation increases to α, 65°≤α≤80°, the spiral scanning action of the laser beam from the minimum diameter to the maximum diameter is completed; Step 3: When the laser beam is spirally scanned to the maximum diameter, the upper deflection optical wedge (4) is controlled to rotate at a third speed v3 and the lower deflection optical wedge (5) is controlled to rotate at a second speed v2 as the final speed; When the relative angle between the upper deflection optical wedge (4) and the lower deflection optical wedge (5) during the rotation process is reduced to 0°, the spiral scanning action of the laser beam from the maximum diameter to the minimum diameter is completed; Step 4: When the laser beam is spirally scanned to the minimum diameter, the upper deflection wedge (4) is controlled to rotate at a second speed v2 and the lower deflection wedge (5) is controlled to rotate at a third speed v3 as the final speed; When the relative angle between the upper deflection optical wedge (4) and the lower deflection optical wedge (5) during the rotation increases to α, the spiral scanning action of the laser beam from the minimum diameter to the maximum diameter is completed; Step 5: Control the spiral scanning laser processing head (11) to feed downward at a preset increment, and return to step 3 to process the next layer of micro-holes until the micro-hole processing of the preset depth is completed.

2. A laser spiral scanning trajectory precision control method according to claim 1, characterized in that: In step 1, the first speed v1 is 3000 rpm.

3. The method for precise control of laser spiral scanning trajectory according to claim 2, characterized in that: In step 2, step 3 and step 4, the second speed v2 is 3005 rpm; the third speed v3 is 2995 rpm.

4. The method for precise control of a laser spiral scanning trajectory according to claim 3, characterized in that: In steps 2 and 4, the value of α is 72°.

5. A laser spiral scanning trajectory precision control method according to any one of claims 1 to 4, characterized in that: In step five, the spiral scanning laser processing head (11) is fed downwards in increments of 0.01 mm each time.

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