Method and device for fast positioning of laser focus position

Abstract

The application provides a laser focus position quick positioning method and device, determines the motion resolution and initial position of the laser focus position positioning, controls the laser galvanometer system to move to the initial position, controls the laser galvanometer system to move multiple times along the direction perpendicular to the processing plane based on the motion resolution, controls the laser galvanometer system to process a marking line on the processing plane and acquires the line width when the laser galvanometer system moves to the target position each time, until the line width corresponding to the current target position is less than the line width corresponding to the last target position and the next target position respectively and the distance between each adjacent two target positions in the last three target positions is the motion resolution, controls the laser galvanometer system to stop moving, and takes the position of the laser used for processing the marking line corresponding to the current target position and intersecting with the processing plane as the laser focus position. The application can improve the efficiency and accuracy of finding the laser focus position.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser processing, and particularly to a laser focus position quick positioning method and device. BACKGROUND

[0002] In the field of high-precision laser processing, due to the stringent requirements on precision indicators, it is necessary to comprehensively improve each item of precision which has a greater impact on overall precision from multiple aspects. For a laser processing system which realizes laser deflection through a galvanometer, the following ways are usually needed to comprehensively improve the laser processing precision: first, collimate the light path to ensure that the laser light is perpendicular to the processing plane in the initial state of the processing system; second, accurately adjust the focus to ensure that the laser focus waist position is located inside the processing reference plane in the initial state of the processing system; and third, correct the distortion of the galvanometer by measuring and updating the iteration correction table multiple times to reduce the distortion error of the galvanometer. It can be seen that accurately adjusting the position of the laser focus has an important influence on the processing quality and is a very important link in improving the precision of laser processing.

[0003] However, the conventional laser focus position adjustment method is prone to jumping back and forth near the laser focus position due to the unclear adjustment direction and idea, and the efficiency of finding the laser focus position is low, and the positioning accuracy of the focus position is difficult to guarantee. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a laser focus position quick positioning method and device to alleviate the above-mentioned problems existing in the prior art laser focus position adjustment technology.

[0005] In a first aspect, an embodiment of the present application provides a method for quickly positioning a laser focus position, comprising: determining a movement resolution for positioning the laser focus position based on a target accuracy of positioning the laser focus position, a preset movement resolution of a machine table for driving a laser galvanometer system to move up and down, and a focal depth of a laser beam; determining an initial position of positioning the laser focus position based on a working distance of a field lens, and controlling the laser galvanometer system to move to the initial position; controlling the laser galvanometer system to move multiple times along a direction perpendicular to a processing plane based on the movement resolution, so as to control the laser galvanometer system to process a marking line on the processing plane and acquire a line width of the marking line each time the laser galvanometer system moves to a target position; wherein, after the laser galvanometer system moves each time and completes the processing of the marking line, a next target position is determined based on a current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and a previous target position; until the line width corresponding to the current target position is smaller than the line widths corresponding to the previous target position and the next target position, and the distance between each two adjacent target positions in the last three target positions is the movement resolution, the laser galvanometer system is controlled to stop moving, and a position where the laser used to process the marking line corresponding to the current target position intersects with the processing plane is taken as the laser focus position.

[0006] In a second aspect, an embodiment of the present application further provides a device for quickly positioning a laser focus position, comprising: a determining module configured to determine a movement resolution for positioning the laser focus position based on a target accuracy of positioning the laser focus position, a preset movement resolution of a machine table for driving a laser galvanometer system to move up and down, and a focal depth of a laser beam; a first control module configured to determine an initial position of positioning the laser focus position based on a working distance of a field lens, and control the laser galvanometer system to move to the initial position; a second control module configured to control the laser galvanometer system to move multiple times along a direction perpendicular to a processing plane based on the movement resolution, so as to control the laser galvanometer system to process a marking line on the processing plane and acquire a line width of the marking line each time the laser galvanometer system moves to a target position; wherein, after the laser galvanometer system moves each time and completes the processing of the marking line, a next target position is determined based on a current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and a previous target position; and a positioning module configured to control the laser galvanometer system to stop moving until the line width corresponding to the current target position is smaller than the line widths corresponding to the previous target position and the next target position, and the distance between each two adjacent target positions in the last three target positions is the movement resolution, and take a position where the laser used to process the marking line corresponding to the current target position intersects with the processing plane as the laser focus position.

[0007] The embodiment of the present application provides a laser focus position quick positioning method and device, determines the motion resolution and initial position of the laser focus position positioning, controls the laser galvanometer system to move to the initial position, controls the laser galvanometer system to move in the direction perpendicular to the machining plane multiple times based on the motion resolution, controls the laser galvanometer system to process a marking line on the machining plane and acquires the line width of the marking line when the laser galvanometer system moves to a target position each time, until the line width corresponding to the current target position is smaller than the line width corresponding to the last target position and the next target position respectively and the distance between each adjacent two target positions in the last three target positions is the motion resolution, the laser galvanometer system is controlled to stop moving, and the position of the laser used for processing the marking line corresponding to the current target position and intersecting with the machining plane is taken as the laser focus position. By using the above technology, the motion resolution of the laser focus position positioning can be used to control the laser galvanometer system to move to different positions to form multiple marking lines on the machining plane, and the laser focus position can be quickly and accurately found by comparing the line widths of the different marking lines, so that the efficiency and accuracy of finding the laser focus position can be improved, and then the laser machining precision is ensured.

[0008] Other features and advantages of the present application will be set forth in the descriptions below, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the description, claims and drawings.

[0009] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are described in detail as follows. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without any creative labor.

[0011] Figure 1 A flowchart of a laser focus position quick positioning method in the embodiment of the present application is shown in the figure.

[0012] Figure 2 A laser focus position quick positioning scene in the embodiment of the present application is shown in the figure.

[0013] Figure 3 A coarse positioning process in the embodiment of the present application is shown in the figure.

[0014] Figure 4A schematic diagram of a fine positioning process in an embodiment of the present application is shown in the figure;

[0015] Figure 5 A structure schematic diagram of a laser focus position quick positioning device in an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described below in connection with the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0017] At present, in the field of high-precision laser processing, accurately adjusting the position of laser focus is a very important link in improving the precision of laser processing. However, the conventional laser focus position adjustment method is prone to jumping back and forth near the laser focus position due to the unclear adjustment direction and idea, and the efficiency of finding the laser focus position is low, and the positioning accuracy of the focus position is difficult to guarantee.

[0018] Based on this, the laser focus position quick positioning method and device provided by the embodiments of the present application can alleviate the above problems existing in the existing laser focus position adjustment technology.

[0019] Referring to Figure 1 the figure, the laser focus position quick positioning method can include the following steps:

[0020] Step S102, determining the motion resolution of the laser focus position positioning based on the target accuracy of the laser focus position positioning, the preset motion resolution of the machine table for driving the laser galvanometer system to move up and down, and the focal depth of the laser beam.

[0021] The preset motion resolution represents the minimum allowable motion step length of the machine table for driving the laser galvanometer system to move up and down.

[0022] Referring to Figure 2 the figure, the laser galvanometer system 201 can be driven to move up and down perpendicular to the processing plane 202 by the external shaft 205 (i.e. the shaft on the machine table for driving the laser galvanometer system 201 to move up and down). In actual laser processing, the laser galvanometer system 201 needs to ensure that the laser focus point 204 is on the processing plane 202 as much as possible to ensure the precision of laser processing. The motion resolution MinStepLength in the focus positioning process is determined by three factors: the motion resolution ShaftResolution of the external shaft 205, the focus positioning accuracy requirement PosPrecision, and the focal depth DOF of the laser beam.

[0023] Step S104, determining an initial position of the laser focus position based on the working distance of the field lens, and controlling the laser galvanometer system to move to the initial position.

[0024] In the foregoing example, referring to Figure 2 As shown in the figure, a theoretical position can be determined as the initial position of the laser focus position according to the working distance of the field lens, the distance between the initial position and the field lens is equal to the working distance of the field lens, and moving the laser galvanometer system 201 to the initial position can ensure that the laser focus point 204 is on the processing plane 202 and further ensure the laser processing precision.

[0025] Step S106, controlling the laser galvanometer system to move multiple times along the direction perpendicular to the processing plane based on the motion resolution, so as to process a marking line on the processing plane and obtain the line width of the marking line when the laser galvanometer system moves to the target position each time.

[0026] In which, after the laser galvanometer system moves and completes the marking line processing each time, the next target position is determined based on the current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and the last target position respectively.

[0027] In the foregoing example, referring to Figure 2 As shown in the figure, the laser of the laser galvanometer system 201 is turned on, and the laser 203 marks a straight line with a certain line width on the processing plane 202, the straight line is the marking line, and the line width of the straight line can reflect the range of the laser 203 being cut off by the processing plane 202. When the laser focus point 204 is on the processing plane 202, the range of the laser 203 being cut off by the processing plane 202 is the smallest, so the process of finding the laser focus point 204 can be converted into finding the position along the emission direction of the laser 203 that makes the range of the laser 203 being cut off by the processing plane 202 the smallest.

[0028] Step S108, until the line width corresponding to the current target position is smaller than the line widths corresponding to the last target position and the next target position respectively and the distance between each adjacent two target positions in the last three target positions is the motion resolution, controlling the laser galvanometer system to stop moving, and taking the position where the laser used to process the marking line corresponding to the current target position intersects with the processing plane as the laser focus position.

[0029] In the foregoing example, referring to Figure 2As shown, in the process of driving the laser galvanometer system 201 to move up and down on the machining plane 202 perpendicularly by the external shaft 205, the laser galvanometer system 201 will open the laser to emit the laser 203 to mark a marking line on the machining plane 202 every time it reaches a target position. If a certain target position and other target positions adjacent to it before and after the certain target position satisfy that the line width of the marking line corresponding to the certain target position is less than the line width of the marking lines corresponding to the other target positions and the distance between the certain target position and the other target positions adjacent to it before and after the certain target position is the movement resolution MinStepLength, it indicates that the laser focal point 204 is near the target position and the distance between the laser focal point 204 and the target position is less than the movement resolution MinStepLength. The position where the laser 203 used by the laser galvanometer system 201 to mark the marking line at the target position intersects with the machining plane 202 (i.e. the intersection point of the laser 203 and the machining plane 202) is taken as the laser focal position, so as to ensure the laser processing precision when subsequent laser processing is performed at the laser focal position.

[0030] The laser focal position quick positioning method provided by the embodiment of the application determines the movement resolution and initial position of the laser focal position positioning and controls the laser galvanometer system to move to the initial position. The laser galvanometer system is controlled to move along the direction perpendicular to the machining plane multiple times based on the movement resolution, so as to mark a marking line on the machining plane by the laser galvanometer system every time the laser galvanometer system moves to a target position and acquire the line width of the marking line, until the line width corresponding to the current target position is less than the line widths corresponding to the last target position and the next target position and the distance between every two adjacent target positions in the last three target positions is the movement resolution. The laser galvanometer system is controlled to stop moving, and the position where the laser used to process the marking line corresponding to the current target position intersects with the machining plane is taken as the laser focal position. By using the above technology, the movement resolution of the laser focal position positioning can be used to control the laser galvanometer system to move to different positions to form multiple marking lines on the machining plane, and the laser focal position can be quickly and accurately found by comparing the line widths of the different marking lines, so as to improve the efficiency and accuracy of finding the laser focal position and further ensure the laser processing precision.

[0031] As a possible implementation manner, the step S106 (i.e. controlling the laser galvanometer system to move along the direction perpendicular to the machining plane multiple times based on the movement resolution, so as to mark a marking line on the machining plane by the laser galvanometer system every time the laser galvanometer system moves to a target position and acquire the line width of the marking line) can include:

[0032] Step 1: determining the initial movement step length of the laser galvanometer system based on the movement resolution.

[0033] The initial movement step length is greater than the movement resolution and is an integer multiple of the movement resolution.

[0034] As a continuation of the previous example, referring to Figure 2 As shown in the figure, after obtaining the movement resolution MinStepLength in the focusing positioning process, the step length S of the laser galvanometer system 201 moving up and down perpendicular to the machining plane 202 can be set to N x MinStepLength, N being an integer, so that the laser galvanometer system 201 can be moved by the external shaft 205 to reach the next target position from the current target position by one step length S in the direction perpendicular to the machining plane 202.

[0035] Step 2: When the laser galvanometer system moves to the first target position, control the laser galvanometer system to process a marking line on the machining plane and obtain the line width of the marking line.

[0036] Step 3: For each target position after the first target position, perform the following steps A to D:

[0037] A. Determine the direction of the next target position based on the current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and the previous target position.

[0038] B. Take the position between the current target position and the next target position in the direction of the next target position as the next target position, control the laser galvanometer system to move to the next target position, process a marking line on the machining plane, and obtain the line width of the marking line; wherein the current movement step length is the initial movement step length for the second target position.

[0039] C. If the line width corresponding to the current target position is less than the line widths corresponding to the previous target position and the next target position, adjust the current movement step length based on the movement resolution, and take the adjusted movement step length as the movement step length, re-execute steps A and B until the current movement step length is the movement resolution.

[0040] As a possible implementation, the step of determining the direction of the next target position based on the current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and the previous target position can include: if the current target position is the first target position reached by the laser galvanometer system after adjusting the current movement step length, randomly determine the direction consistent with or opposite to the current moving direction of the laser galvanometer system as the direction of the next target position; if the current target position is not the first target position reached by the laser galvanometer system after adjusting the current movement step length, compare the line widths corresponding to the current target position and the previous target position to determine the direction of the next target position.

[0041] In actual application, the operation mode of comparing the line widths corresponding to the current target position and the last target position respectively to determine the direction of the next target position can be: if the line width corresponding to the current target position is smaller than the line widths corresponding to the last target position respectively, it is determined that the direction of the next target position is consistent with the current moving direction of the laser galvanometer system; if the line width corresponding to the current target position is greater than the line widths corresponding to the last target position respectively, it is determined that the direction of the next target position is opposite to the current moving direction of the laser galvanometer system.

[0042] As a possible implementation, the step of adjusting the current motion step based on the motion resolution can include: if the current motion step is greater than the motion resolution, reducing the current motion step, and taking the reduced motion step as the adjusted motion step; if the current motion step is the motion resolution, keeping the current motion step unchanged.

[0043] In actual application, the motion step of the laser galvanometer system each time can be an integer multiple of the motion resolution; based on this, the operation mode of reducing the current motion step can be: determining the reduction amount of the current motion step, and reducing the current motion step according to the reduction amount; wherein the reduction amount is an integer multiple of the motion resolution and is not greater than half of the current motion step.

[0044] As a possible implementation, the ratio between the motion resolution and the focal depth can be not greater than 0.3; based on this, the step S102 (i.e., determining the motion resolution of the laser focusing position based on the target accuracy of the laser focusing position, the preset motion resolution of the machine table for driving the laser galvanometer system to move up and down, and the focal depth of the laser beam) can include: if the target accuracy is lower than the preset motion resolution, determining the target accuracy as the motion resolution; if the target accuracy is not lower than the preset motion resolution, determining the preset motion resolution as the motion resolution.

[0045] Following the previous example, refer to Figure 2As shown, in the case of known motion resolution of the external shaft 205, focus positioning precision requirement PosPrecision, and focal depth DOF of the laser beam, if PosPrecision > ShaftResolution, it means that the requirement for positioning precision can actually be met, and the motion resolution MinStepLength in the focus positioning process = PosPrecision, if PosPrecision ≤ ShaftResolution, it means that the requirement for positioning precision is too high, and the requirement for positioning precision cannot actually be met, and MinStepLength = ShaftResolution is taken, that is, when determining the motion resolution of the laser focus position positioning, the accuracy of the focus adjustment can only be maximally guaranteed under the motion resolution of the external shaft 205. In addition, the focal depth of a specific laser beam is also considered, and generally MinStepLength is less than or equal to 0.3 times DOF.

[0046] As a possible implementation, the step of acquiring the line width of the marking line can include: measuring the line width of the marking line by using a microscope with a preset magnification, or acquiring an image containing the marking line by using a vision system and calculating the line width of the marking line based on the image.

[0047] In actual application, the preset magnification is not less than 100, and specifically a metallographic microscope with a magnification of more than 100 times can be used to measure the line width of the marking line.

[0048] In the foregoing example, refer to Figure 2 As shown, a vision system 206 can be installed on the optical system, and the vision system 206 has the functions of image acquisition, identification of the marking line, and calculation of the line width, etc. After the laser 203 marks a marking line on the machining plane 202 every time the laser galvanometer system 201 reaches a target position, the vision system 206 can be controlled to automatically acquire an image containing the marking line, identify the marking line in the image, and calculate the line width of the marking line.

[0049] For ease of understanding, the implementation of the above laser focus position fast positioning method is described exemplarily as follows by taking a specific application as an example.

[0050] In the foregoing example, refer to Figures 2 to 4 As shown, the above laser focus position fast positioning method can mainly include the following steps:

[0051] First step: determine the motion resolution MinStepLength in the focusing positioning process. This parameter is determined by three factors: ① the motion resolution ShaftResolution of the external shaft 205 (driving the laser galvanometer system 201 to move up and down perpendicular to the processing plane 202); ② the focusing positioning precision PosPrecision; ③ the focal depth DOF of the laser 203.

[0052] The direction of the external shaft 205 is upward perpendicular to the processing plane 202, and the external shaft 205 is generally defined as the Z-axis.

[0053] If PosPrecision > ShaftResolution, then MinStepLength = PosPrecision; if PosPrecision ≤ ShaftResolution, then MinStepLength = ShaftResolution; MinStepLength is less than or equal to 0.3 times DOF.

[0054] Second step: determine the initial position Z = FocalLength in the focusing positioning process according to the working distance of the field lens.

[0055] The initial position corresponds to the working distance of the field lens. For example, in the case of a known optical system field lens working distance, the accurate value of the laser focusing position (i.e. the laser focal point 204) in theory is the position of the working distance, but considering the precision of related parts manufacturing and installation, the actual situation of the laser focusing position in the laser processing field is a random value near the accurate value, and the above-mentioned laser focusing position fast positioning method is to accurately find this random value.

[0056] Third step: turn on the laser, and the laser 203 emits light and marks a straight line on the processing plane 202.

[0057] Similar to the initial position, the processing plane 202 is also a theoretical position determined according to the working distance. Referring to Figure 2 , the processing plane 202 is generally installed on the base of the machine tool (processing system), and the processing plane 202 should be located at the position of the working distance in theory (i.e. the distance between the processing plane 202 and the lower surface of the field lens is equal to the working distance), so as to ensure that the laser focal point 204 is just on the processing plane 202.

[0058] Marking refers to processing a straight line on the surface of the workpiece on the reference plane (i.e. the processing plane 202) by the laser 203 as a marking line.

[0059] Fourth step: obtain the width of the marking line obtained in the third step, and record it as FirstLineWidth.

[0060] The width of the marking line (i.e. line width) can be measured under a high-precision microscope. The magnification of the microscope is more than 100 times, and the magnification of the microscope can be controlled in the interval [100, 400] in practice, for example, a metallographic microscope with 150 times can meet the demand. Referring to Figure 2 As shown, the width of the marking line can be considered to be determined by the area of the cross section (corresponding to the formed spot on the machining plane 202) obtained by the beam of the laser 203 being intercepted by the machining plane 202. The smaller the width of the marking line, the closer the machining plane 202 is to the laser focus point 204. It is generally considered that the cross section of the waist position of the focused beam of the laser 203 is the smallest, and therefore the above-mentioned rapid positioning method of the laser focus position is to find the accurate position of the minimum cross section of the focused beam of the laser 203 (i.e. the laser focus position). Figure 3 and Figure 4 Both show the focused waist of the laser 203, and the cross-sectional area of the focused waist of the laser 203 can be used to represent the line width of the marking line.

[0061] In addition to the microscope, the visual system 206 can also be used to take pictures to measure the line width and automatically return, and automatically adjust the movement of the external shaft 205 to drive the laser galvanometer system 201, so as to realize the full automation of the whole focus accurate adjustment. According to the depth of field range, the accuracy of the visual system 206 in measuring the line width needs to be more than 0.01 mm. The use of the visual system 206 to measure the line width improves the efficiency of obtaining the line width, thereby improving the overall efficiency of positioning the laser focus position.

[0062] Fifth step: randomly determine a moving direction (upward or downward perpendicular to the machining plane 202), control the laser galvanometer system 201 to move a certain distance (such as 10 x MinStepLength), and then repeat the third step and the fourth step, record the line width SecondLineWidth, and compare the two line widths FirstLineWidth and SecondLineWidth. If SecondLineWidth > FirstLineWidth, it means that the accurate laser focus position is on the opposite side of the moving direction determined in the fifth step, otherwise (i.e. SecondLineWidth≤FirstLineWidth) it means that the accurate laser focus position is on the moving direction determined in the fifth step.

[0063] If the accurate laser focus position is on the moving direction determined in the fifth step, the following sixth step to ninth step are executed after the first step to fifth step are executed.

[0064] Step 6: Move the laser galvanometer system 201 by a certain distance S (e.g. 10 x MinStepLength) in the direction determined in Step 5 by the external axis 205, and repeat Step 3 and Step 4 to record the line width.

[0065] Step 7: If the line width recorded in Step 6 is smaller than the line width recorded in Step 5, it means the real laser focus position is in the current moving direction. If the line width recorded in Step 6 is larger than the line width recorded in Step 5, it means the real laser focus position is in the opposite direction of the current moving direction. See Figure 3 Step 8: Repeat the operation (i.e. Step 3 to Step 7) n times until the line width recorded in Step 7 is larger than the line width recorded in Step 5. See Figure 3 Step 9: If the line width recorded in Step 7 is larger than the line width recorded in Step 5, it means the real laser focus position is between the (n-2)th mark and the (n-1)th mark. See Figure 3 Step 10: If the line width recorded in Step 7 is smaller than the line width recorded in Step 5, it means the real laser focus position is between the (n-1)th mark and the nth mark. See

[0066] Step 11: If the real laser focus position is between the (n-1)th mark and the nth mark, move the laser galvanometer system 201 by S / 2 (e.g. 5 x MinStepLength) in the opposite direction of the current moving direction from the laser focus position determined in Step 7. If the real laser focus position is between the (n-2)th mark and the (n-1)th mark, move the laser galvanometer system 201 by 3S / 2 (e.g. 15 x MinStepLength) in the opposite direction of the current moving direction.

[0067] Step 9: Randomly select a direction (upward or downward perpendicular to the processing plane 202) to control the laser galvanometer system 201 to move MinStepLength, repeat Step 3 and Step 4. During the process, if the line width continues to decrease, it means that the real laser focus position is in the direction selected in Step 9, and the laser galvanometer system 201 can be controlled to continue moving MinStepLength in the direction from the current position. If the line width becomes larger, it means that the accurate laser focus position is on the opposite side of the direction selected in Step 9, and the laser galvanometer system 201 can be controlled to move MinStepLength in the opposite direction from the current position. Repeat the above operation (i.e., control the laser galvanometer system 201 to move MinStepLength and perform Step 3 and Step 4) n times until the line width becomes larger again, and complete the first round of fine positioning. The real focus position can be taken as the position marked in the n-1th fine positioning, and the laser focus position finding is completed, and the implementation process is as shown in Figure 4 As can be seen, the position marked in the n-1th fine positioning and the theoretical focus position (i.e., the position of the laser focus point 204) are very close, meeting the required precision MinStepLength.

[0068] The above steps can ensure that the laser focus position is quickly found under the condition of meeting the focus positioning precision requirement MinStepLength.

[0069] Similarly, if the accurate laser focus position is on the opposite side of the movement direction determined in Step 5, the following steps are performed after Steps 1 to 5 are executed:

[0070] The laser galvanometer system 201 is driven by the external shaft 205 to move 3S / 2 (such as 15 x MinStepLength) in the opposite direction of the movement direction determined in Step 5, and then the similar steps as Step 6 are performed, that is, the laser galvanometer system 201 is driven by the external shaft 205 to continue moving S in the current movement direction for a single time while repeating Step 3 and Step 4, and the line width is recorded. Then the similar steps as Step 7 are performed, that is, if the currently recorded line width continues to decrease compared to the previously recorded line width, it means that the real laser focus position is in the current movement direction, and if the currently recorded line width becomes larger compared to the previously recorded line width, it means that the accurate laser focus position is in the opposite direction of the current movement direction, as shown in Figure 3As shown, the operation of repeating n times (i.e. controlling the laser galvanometer system 201 to move S at a time and comparing the line width recorded in the third step and the fourth step) is performed until the line width increases again, and the first round of coarse positioning is completed. Meanwhile, the line width recorded in the n-th step is compared with the line width recorded in the n-2-th step. If the line width recorded in the n-th step is greater than the line width recorded in the n-2-th step, the accurate laser focus position is between the n-2-th step and the n-1-th step. If the line width recorded in the n-th step is less than the line width recorded in the n-2-th step, the accurate laser focus position is between the n-1-th step and the n-th step. Then, a step similar to the eighth step is performed. If the accurate laser focus position is between the n-1-th step and the n-th step, the laser galvanometer system 201 is driven by the external shaft 205 to move S / 2 in the opposite direction of the current moving direction, and a straight line is marked. If the accurate laser focus position is between the n-2-th step and the n-1-th step, the laser galvanometer system 201 is driven by the external shaft 205 to move 3S / 2 in the opposite direction of the current moving direction. Then, the ninth step is performed to complete the first round of fine positioning.

[0071] If the second round of fine positioning is involved, the operation mode of the second round of fine positioning is the same as that of the first round of fine positioning, and thus will not be described herein.

[0072] The above steps mainly exemplarily describe finding the accurate laser focus position through one round of coarse positioning and one round of fine positioning. In actual applications, the coarse positioning can be arranged in multiple rounds (generally, 1-2 rounds of coarse positioning are sufficient to meet the requirements, and then fine positioning is performed). The steps described above are only one round of coarse positioning and one round of fine positioning for the sake of brevity. The principle of the above laser focus position fast positioning method can be clearly described by one round of coarse positioning and one round of fine positioning in combination with the drawings, but the number of rounds of the coarse positioning and the fine positioning is not limited. Generally, when the second round of coarse positioning is performed, the moving step length used in the first marking is 1 / 2 of the moving step length used in the previous round of coarse positioning. In actual cases, the moving step length used in the current round of coarse positioning is 1 / 4 or smaller of the moving step length used in the previous round of coarse positioning. However, the distance of each movement of the laser galvanometer system 201 is fixed as MinStepLength in the final fine positioning stage, so as to ensure that the positioning accuracy of the laser focus position is within the variation range of one MinStepLength.

[0073] The beneficial effects of the above laser focus position fast positioning method mainly include the following aspects:

[0074] First, high efficiency. The method can greatly improve the efficiency of finding the focusing position by continuously narrowing the search range, first narrowing the accurate focusing position in a smaller range, and then selecting a shorter search step.

[0075] Second, high precision. Combining coarse positioning and fine positioning, even if the precision requirement is set very high, the accurate focusing position can be quickly found under the condition that the hardware device allows, and the focusing position with high precision can be easily obtained.

[0076] Third, strong flexibility. One or more rounds of coarse positioning and fine positioning can be set according to different precision requirements and hardware device conditions to achieve the purpose of efficiently finding the focusing position; at the same time, in the fine positioning stage, the search step can be randomly set according to the required precision value under the condition that the hardware satisfies, and the focusing position with high precision can be easily obtained.

[0077] Based on the above laser focusing position quick positioning method, the embodiment of the present application also provides a laser focusing position quick positioning device, as shown in Figure 5 The device can include the following modules:

[0078] The determination module 502 is configured to determine the motion resolution of the laser focusing position positioning based on the target precision of the laser focusing position positioning, the preset motion resolution of the machine table for driving the laser galvanometer system to move up and down, and the focal depth of the laser beam.

[0079] The first control module 504 is configured to determine the initial position of the laser focusing position positioning based on the working distance of the field lens, and control the laser galvanometer system to move to the initial position.

[0080] The second control module 506 is configured to control the laser galvanometer system to move multiple times along the direction perpendicular to the machining plane based on the motion resolution, so as to control the laser galvanometer system to process a marking line on the machining plane and obtain the line width of the marking line when the laser galvanometer system moves to the target position each time; wherein, after the laser galvanometer system moves and completes the processing of the marking line each time, the next target position is determined based on the current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and the last target position respectively.

[0081] The positioning module 508 is configured to control the laser galvanometer system to stop moving when the line width corresponding to the current target position is less than the line widths corresponding to the last target position and the next target position respectively and the distance between each adjacent two target positions in the last three target positions is the motion resolution, and the position of the laser used for processing the marking line corresponding to the current target position and intersecting with the machining plane is taken as the laser focusing position.

[0082] By using the laser focus position quick positioning device, the motion resolution of the laser focus position positioning can be used to control the laser galvanometer system to move to different positions to form a plurality of marking lines on the machining plane, and the more accurate laser focus position can be quickly found by comparing the line widths of different marking lines, so that the efficiency and accuracy of finding the laser focus position are improved, and the laser machining precision is ensured.

[0083] The ratio between the motion resolution and the focal depth can be no more than 0.3; based on this, the determination module 502 can also be used to: if the target precision is lower than the preset motion resolution, determine the target precision as the motion resolution; if the target precision is not lower than the preset motion resolution, determine the preset motion resolution as the motion resolution.

[0084] The second control module 506 can also be used to: use a microscope with a preset magnification to measure the line width of the marking line, or use a vision system to collect an image containing the marking line and calculate the line width of the marking line based on the image.

[0085] The laser focus position quick positioning device provided by the embodiment of the application has the same implementation principle and technical effects as the aforementioned laser focus position quick positioning method embodiment, and for brevity of description, the parts not mentioned in the laser focus position quick positioning device embodiment can refer to the corresponding contents in the aforementioned laser focus position quick positioning method embodiment.

[0086] Unless specifically stated otherwise, the relative steps, numerical expressions and values of the components and steps set forth in these embodiments do not limit the scope of the application.

[0087] If the functions are realized in the form of software function units and sold or used as independent products, the functions can be stored in a nonvolatile computer readable storage medium executable by a processor. Based on this understanding, the technical solutions of the application or the parts of the technical solutions that essentially contribute to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0088] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0089] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, and are not limiting. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can make modifications or easily think of changes to the technical solutions recorded in the foregoing embodiments within the technical range disclosed by the present application, or make equivalent replacements to some technical features; and these modifications, changes or replacements do not cause the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for quickly positioning a laser focus position, characterized by, The application comprises: determining the movement resolution of the laser focus position positioning based on the target accuracy of the laser focus position positioning, the preset movement resolution of the machine table for driving the up-and-down movement of the laser galvanometer system, and the focal depth of the laser beam; wherein, the preset movement resolution represents the minimum allowable movement step length of the machine table for driving the up-and-down movement of the laser galvanometer system; determining the initial position of the laser focus position positioning based on the working distance of the field lens, and controlling the laser galvanometer system to move to the initial position; controlling the laser galvanometer system to move multiple times along the direction perpendicular to the processing plane based on the movement resolution, so as to control the laser galvanometer system to process a marking line on the processing plane and obtain the line width of the marking line when the laser galvanometer system moves to a target position each time; wherein, after the laser galvanometer system moves and completes the processing of the marking line each time, the next target position is determined based on the current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and the last target position respectively; until the line width corresponding to the current target position is smaller than the line widths corresponding to the last target position and the next target position respectively and the distance between each adjacent two target positions among the last three target positions is the movement resolution, the laser galvanometer system is controlled to stop moving, and the position of the laser for processing the marking line corresponding to the current target position and intersecting with the processing plane is taken as the laser focus position; the ratio between the movement resolution and the focal depth is not greater than 0.3; determining the movement resolution of the laser focus position positioning based on the target accuracy of the laser focus position positioning, the preset movement resolution of the machine table for driving the up-and-down movement of the laser galvanometer system, and the focal depth of the laser beam comprises: if the target accuracy is lower than the preset movement resolution, the target accuracy is determined as the movement resolution; if the target accuracy is not lower than the preset movement resolution, the preset movement resolution is determined as the movement resolution.

2. The method of claim 1, wherein, controlling the laser galvanometer system to move multiple times along the direction perpendicular to the processing plane based on the movement resolution, so as to control the laser galvanometer system to process a marking line on the processing plane and obtain the line width of the marking line when the laser galvanometer system moves to a target position each time, comprises: determining the initial movement step length of the laser galvanometer system based on the movement resolution; wherein, the initial movement step length is greater than the movement resolution and is an integer multiple of the movement resolution; when the laser galvanometer system moves to the first target position, controlling the laser galvanometer system to process a marking line on the processing plane and obtain the line width of the marking line; for each target position after the first target position, the following steps A to D are performed: A, determining the direction of the next target position based on the current moving direction of the laser galvanometer system and the line widths corresponding to the current target position and the last target position respectively; B. taking a position, which is in a direction of the next target position and has a distance from the current target position as a current movement step, as the next target position, controlling the laser galvanometer system to move to the next target position to process a marking line on the processing plane and acquiring a line width of the marking line; wherein the current movement step is the initial movement step for the second target position; C. if the line width corresponding to the current target position is smaller than the line width corresponding to each of the last target position and the next target position, adjusting the current movement step based on the movement resolution, and taking the adjusted movement step as the movement step, re-executing steps A and B until the current movement step is the movement resolution, and stopping adjusting the current movement step.

3. The method of claim 2, wherein, The adjusting the current movement step based on the movement resolution comprises: if the current movement step is greater than the movement resolution, reducing the current movement step, and taking the reduced movement step as the adjusted movement step; if the current movement step is the movement resolution, keeping the current movement step unchanged.

4. The method of claim 2, wherein, The determining the direction of the next target position based on the current moving direction of the laser galvanometer system and the line width corresponding to each of the current target position and the last target position comprises: if the current target position is the first target position reached by the laser galvanometer system after adjusting the current movement step, randomly determining a direction consistent with or opposite to the current moving direction of the laser galvanometer system as the direction of the next target position; if the current target position is not the first target position reached by the laser galvanometer system after adjusting the current movement step, comparing the line width corresponding to each of the current target position and the last target position to determine the direction of the next target position.

5. The method of claim 4, wherein, The comparing the line width corresponding to each of the current target position and the last target position to determine the direction of the next target position comprises: if the line width corresponding to the current target position is smaller than the line width corresponding to each of the last target position, determining that the direction of the next target position is consistent with the current moving direction of the laser galvanometer system; if the line width corresponding to the current target position is greater than the line width corresponding to each of the last target position, determining that the direction of the next target position is opposite to the current moving direction of the laser galvanometer system.

6. The method of claim 3, wherein, The movement step of the laser galvanometer system each time is an integer multiple of the movement resolution; The reducing the current movement step comprises: determining a reduction amount of the current movement step, and reducing the current movement step by the reduction amount; wherein the reduction amount is an integer multiple of the movement resolution and is not greater than half of the current movement step.

7. The method of claim 1, wherein, The acquiring the line width of the marking line comprises: measuring the line width of the marking line by using a microscope with a preset magnification, or collecting an image containing the marking line by using a vision system and calculating the line width of the marking line based on the image.

8. The method of claim 7, wherein, The preset magnification is not less than 100.

9. A laser focus position quick positioning device, characterized in that, The method for quickly positioning a laser focus position is applied to any one of claims 1-8, and comprises: a determining module configured to determine a movement resolution of the laser focus position positioning based on a target accuracy of the laser focus position positioning, a preset movement resolution of a machine table configured to drive the laser galvanometer system to move up and down, and a focal depth of a laser beam. A first control module is configured to determine an initial position of the laser focus position based on a working distance of the field lens, and control the laser galvanometer system to move to the initial position. A second control module is configured to control the laser galvanometer system to move multiple times along a direction perpendicular to the processing plane based on the movement resolution, so as to control the laser galvanometer system to process a marking line on the processing plane and obtain a line width of the marking line each time the laser galvanometer system moves to a target position; wherein, after the laser galvanometer system moves and completes the processing of the marking line each time, a next target position is determined based on a current movement direction of the laser galvanometer system and the line widths corresponding to the current target position and a previous target position respectively. A positioning module is configured to control the laser galvanometer system to stop moving until the line width corresponding to the current target position is smaller than the line widths corresponding to the previous target position and the next target position respectively, and the distance between each adjacent two target positions among the last three target positions is the movement resolution, and then take a position where a laser used to process the marking line corresponding to the current target position intersects with the processing plane as the laser focus position.

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