A highly efficient laser shaping method for forming grinding wheels based on zoom profiling feed control

Abstract

The invention discloses a high-efficiency laser shaping method for a formed grinding wheel based on zoom profiling feed control. In the processing process, the actual profile line of the grinding wheel is monitored visually, and the relative feed amount of the laser beam is intermittently and adaptively designed, so that the laser beam performs reciprocating relative feeding in the vertical direction according to the ideal profile line of the grinding wheel while scanning horizontally, so that the tool tip (focus) of the super-hard abrasive grinding wheel in the laser shaping process is stripped and removed from the material, and the problem of large fluctuation of the defocus amount in the existing laser shaping technology is solved, and the laser shaping efficiency of the formed grinding wheel is improved; at the same time, the cutting depth-feed relationship in the laser dressing process of the grinding wheel is clarified, and the purpose of always matching the focus of the laser beam with the ideal profile line of the grinding wheel is achieved without changing the scanning trajectory of the laser beam in the horizontal direction, and the situation of excessive material removal will not occur, and visual measurement error and single excessive removal error will not be introduced, so as to ensure the ultra-precision processing requirements of the laser dressing of the formed grinding wheel.

Description

Technical Field

[0001] The invention belongs to the technical field of laser finishing, and in particular relates to a high-efficiency laser finishing method for a forming grinding wheel based on zoom profiling feeding control. Background Art

[0002] Superabrasive grinding wheels are used as tools for grinding optical glass, cemented carbide, ceramics and other materials. They have excellent grinding performance, but due to their extremely high hardness and strong bond holding force, they are very difficult to shape and trim.

[0003] The dressing methods of superabrasive grinding wheels are mainly divided into mechanical dressing, electric spark dressing and pulsed laser dressing. The laser dressing method uses a high-power short-pulse laser to continuously irradiate the surface of the moving and rotating grinding wheel. The surface material is evaporated and vaporized by the high-energy laser beam, so that the grinding wheel can regain the ideal microscopic morphology and macroscopic contour.

[0004] Grinding wheel laser dressing can be divided into two stages: shaping and sharpening. During shaping, the laser beam is required to efficiently remove excess material on the grinding wheel surface to obtain a certain shape accuracy. During sharpening, the laser beam is required to selectively remove the binder material on the grinding wheel surface, leaving abrasive grains and obtaining a certain blade height, so that the grinding wheel can obtain a sharp "blade tip" and sufficient chip space. Figure 1 (a) is a schematic diagram of the tangential laser shaping of arc-shaped grinding wheels. Currently, the dressing method based on single-layer large cutting depth and intermittent feeding is widely used. That is, before dressing, the laser scanning trajectory line must be aligned with the ideal contour line of the grinding wheel after shaping. During dressing, the laser beam reciprocates in the horizontal plane and feeds intermittently along the feed line. Due to the focal depth characteristics of the laser Gaussian beam, when the laser scanning trajectory line that is exactly the same as the ideal contour line of the grinding wheel is used for processing, the height position and area of ​​the laser irradiation spot on the grinding wheel surface in a single scan always show periodic changes. The defocus amount of the laser irradiation position changes in a single scan, the energy density of the spot changes, and the material removal rate changes periodically. It is difficult to maintain a high laser dressing rate, and the dressing efficiency is low.

[0005] In addition, although the laser high-efficiency shaping method for forming grinding wheels based on constant defocus control proposed by me above has greatly improved the laser shaping efficiency, in terms of processing accuracy, on the one hand, the cutting depth verification will introduce visual measurement errors, and on the other hand, because the laser scanning trajectory line in the horizontal direction through adaptive design during the processing cannot be guaranteed to fit the ideal contour line of the grinding wheel, it is possible that the grinding wheel material will be excessively removed during a single scanning process due to the factors of the laser beam focal depth energy characteristics, that is, the actual cutting depth changes discontinuously during the processing process, and the cutting depth verification can only prevent the second excessive cutting scan of the grinding wheel surface, which will introduce a single excessive cutting error, and fail to achieve the same ultra-high shaping accuracy as the traditional single-layer large cutting depth, intermittent feed dressing method.

[0006] Therefore, for laser dressing of formed grinding wheels, the current methods are difficult to achieve constant defocus, high efficiency, and ultra-precision processing. Summary of the invention

[0007] The purpose of the present invention is to provide a method for high-efficiency laser shaping of a formed grinding wheel, so as to overcome the influence of the change in defocus amount within a single scan, realize constant defocus high-efficiency laser shaping of the grinding wheel by adaptively designing the relative feed amount of the laser beam during the shaping process, and solve the technical problem of low efficiency of laser shaping of formed grinding wheels at present. In addition, since the laser beam scanning trajectory adopts a processing method that fits the ideal profile line of the grinding wheel, the laser beam scanning trajectory in the horizontal direction is not changed during the processing process, so that there is no possibility of excessive removal of the grinding wheel material due to factors such as the laser beam focal depth energy characteristics during the processing process, which greatly ensures the ultra-high precision laser shaping of the formed grinding wheel.

[0008] To achieve the above purpose, Figure 1 As shown in (b), the present invention proposes to combine visual monitoring of the actual profile line of the grinding wheel during the processing, and to intermittently and adaptively design the relative feed amount of the laser beam during the processing, so that the laser beam can be relatively fed in the vertical direction of the grinding wheel surface while scanning horizontally, so that the laser irradiation spot always maintains a high energy density state to interact with the grinding wheel material, and realizes the exploitation and removal of the material by the tool tip (focus) during the laser shaping of the super-hard abrasive grinding wheel, solves the problem of large fluctuations in the defocus amount in the existing laser shaping technology, and improves the laser shaping efficiency of the formed grinding wheel. Specifically:

[0009] A method for efficiently shaping a grinding wheel by laser based on zoom profiling feed control comprises the following steps:

[0010] Step 1. Establish the base plane coordinate system: Establish the grinding wheel base plane coordinate system xoy in the horizontal plane.

[0011] Step 2, obtaining the actual profile line of the grinding wheel: using a CCD camera to collect a cross-sectional view of the actual profile line of the grinding wheel within the base surface and obtain the coordinates of each point of the actual profile line within the base surface.

[0012] Step 3: Calculate the remaining feed amount of the laser beam focus: Calculate all the spot (focus) scanning trajectory points P i (x i ,y i ,z i ), (i=1,2,3...n) corresponding to the remaining feed amount z i (i=1,2,3...n);

[0013] Step 4: Fitting the relative feed function of the laser beam: The remaining feed amount z corresponding to all focal scanning trajectory points i (i=1,2,3...n) perform least squares quadratic curve fitting to obtain the relative feed function s and the relative feed amount dz of the laser beam for a single scan i (i=1,2,3...n).

[0014] Step 5: Cutting depth calibration without feed: Based on the cutting depth-feed relationship proposed in step 3, the cutting depth calibration in the vertical direction of the grinding wheel without laser beam feed is performed.

[0015] Step 6: Precise and targeted removal of grinding wheel high points: Based on the cutting depth and feed relationship proposed in step 3, the high points of the surface profile are precisely removed during the grinding wheel laser dressing process.

[0016] The present invention combines visual monitoring of the actual profile line of the grinding wheel during the processing, and intermittently and adaptively designs the relative feed amount of the laser beam, so that the laser beam performs reciprocating relative feeding in the vertical direction while scanning horizontally, imitating the ideal profile line of the grinding wheel, and realizes the exploitation and removal of the material by the tool tip (focus) during the laser shaping of the super-hard abrasive grinding wheel, solves the problem of large fluctuations in the defocus amount in the existing laser shaping technology, and improves the laser shaping efficiency of the formed grinding wheel. The present invention clarifies the cutting depth-feed relationship during the laser finishing of the grinding wheel, so that the laser beam focus and the ideal profile line of the grinding wheel are always in contact without changing the scanning trajectory of the laser beam in the horizontal direction, so that there will be no excessive material removal, and no visual measurement error and single excessive removal error will be introduced, which greatly guarantees the ultra-precision processing requirements of the laser finishing of the formed grinding wheel. In addition, the method proposes auxiliary methods such as feed-free cutting depth setting and precise targeted removal of grinding wheel high points to optimize the processing process, and improve the efficiency and profile accuracy of the laser shaping of the formed grinding wheel.

[0017] After adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art.

[0018] 1. High-efficiency shaping: During the processing, the present invention intermittently and adaptively designs the relative feed amount of the laser beam, so that the laser beam can be relatively fed in the vertical direction of the grinding wheel surface while scanning horizontally, so that the laser irradiation spot always maintains a high energy density state to interact with the grinding wheel material, thereby realizing the exploitation and removal of the material by the tool tip (focus) during the laser shaping of the super-hard abrasive grinding wheel, solving the problem of large fluctuations in the defocus amount in the existing laser shaping technology, and improving the laser shaping efficiency of the formed grinding wheel.

[0019] 2. Ultra-precision machining: The laser beam scanning trajectory adopts a processing method that always fits the ideal contour line of the grinding wheel. This eliminates the possibility of excessive removal of grinding wheel material due to factors such as the laser beam focal depth energy characteristics, and does not introduce visual measurement errors and single excessive removal errors, which greatly ensures ultra-high precision laser shaping of the formed grinding wheel.

[0020] 3. Optimize the processing process: The cutting depth-feed relationship in the grinding wheel laser dressing process is clarified, and based on this, auxiliary methods such as feed-free cutting depth setting and precise targeted removal of grinding wheel high points are proposed to optimize the processing process, thereby improving the efficiency and accuracy of laser shaping of formed grinding wheels. At the same time, through the method of precise targeted removal of grinding wheel high points, the high points generated in unknown difficult-to-process areas on the grinding wheel surface can be accurately removed, thereby enhancing the fault tolerance of the dressing process.

[0021] 4. Automated laser trimming: The method provided by the present invention can realize the adaptive optimization of the relative feed of the laser beam during the laser shaping process of the grinding wheel, without the need for manual readjustment, thus realizing automated laser trimming.

[0022] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are part of this application and are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0024] Figure 1 Schematic diagram comparing the processing effects of a conventional shaping method and a zoom profiling feeding method; (a) is a schematic diagram of the conventional shaping method, and (b) is a schematic diagram of the zoom profiling feeding method of the present invention.

[0025] Figure 2 It is a schematic diagram of the coordinate system, where the curve m in the base plane is the actual profile line of the grinding wheel; n is the ideal profile line of the grinding wheel, that is, the profile of the grinding wheel after dressing.

[0026] Figure 3 It is a schematic diagram of the relative feed of the laser beam, in which the spot (focus) scanning trajectory is the curve of the actual contour line of the grinding wheel in the base plane projected onto the grinding wheel surface along the positive Z axis; the laser beam relative feed function is the projection of the focus scanning trajectory in the cutting plane (xoz plane); the relative feed amount refers to the difference dz between the remaining feed amounts of each focus position relative to the focus position of the scanning starting point when the laser beam is scanned horizontally.

[0027] Figure 4 It is the calculation diagram of the remaining feed amount of the laser beam focus.

[0028] Figure 5 is the relative feed function fitting diagram. Curve m is the actual profile line of the grinding wheel in the base surface; n is the ideal profile line of the grinding wheel, that is, the grinding wheel profile after dressing; s is the relative feed function of the laser beam focus in a single scan, and P0' is the starting point of the relative feed function, which is also the starting point of the focus scanning trajectory.

[0029] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0031] Example 1

[0032] like Figures 1 to 5 As shown, the present embodiment describes a method for high-efficiency laser shaping of a forming grinding wheel based on zoom profiling feed control, comprising the following steps:

[0033] Step 1: Establish the base coordinate system: Figure 2 As shown, the grinding wheel axis section parallel to the horizontal plane is taken as the base plane, and the base plane coordinate system xoy is established within the base plane.

[0034] In this step, xoy is the plane rectangular coordinate system in the base plane, where O is the shortest radial point on the ideal contour line n of the grinding wheel in the base plane, the OX axis is parallel to the rotation axis of the grinding wheel, O-xyz is the spatial rectangular coordinate system, and the vertical upward direction is the positive direction of the Z axis, and the direction away from the center of the grinding wheel is the positive direction of the Y axis.

[0035] Step 2: Get the actual profile of the grinding wheel: Use a CCD camera to collect the coordinates of each point of the actual profile of the grinding wheel m on the base surface: Q1" (x1, y1), Q2" (x2, y m2 ), Q3”(x3,y m3)...Q i ”(x n ,y mn );

[0036] Step 3: Calculate the remaining feed amount of the laser beam focus: Figure 3 As shown, for any point P on the laser beam focus scanning trajectory, the remaining feed amount of the laser beam focus is PQ, and its projection in the cutting plane xoz is P'. According to the geometric relationship, the remaining feed amount PQ of the laser beam focus is determined and calculated.

[0037] In this step, the specific calculation process of the remaining feed amount PQ is as follows:

[0038] like Figure 4 As shown, to obtain the remaining feed amount PQ, for any laser beam focus scanning trajectory point P i (x i ,y i ), (i=1,2,3...n), that is, find the coordinate value z of the point i (x i ,y i ), (i=0,1,2,3...n). The basic conditions that can be obtained by measurement and design before the grinding wheel is processed are that the ideal radius NQ' of the grinding wheel is r0, the coordinates of each point on the ideal grinding wheel profile line n are Q1(x1,y n1 ), Q2(x2,y n2 ), Q3(x3,y n3 )...Q n (x n ,y nn ); and the coordinates of each point on the actual grinding wheel profile line m have been obtained by step 2" (x1, y m1 ), Q2”(x2,y m2 ), Q3”(x3,y m3 )...Q n ”(x n ,y mn ).

[0039] Calculate the ideal rotation radius of the grinding wheel:

[0040] like Figure 4 As shown, Q i Distance to grinding wheel axis NQ i , that is, the ideal radial distance (ideal rotation radius) of the grinding wheel r i for

[0041] r i =NQ i =r0+y ni

[0042] Furthermore, calculate the grinding wheel rotation radius:

[0043] Q i ” Distance to the grinding wheel axis NQ i ”, namely the radial distance (rotation radius) of the grinding wheel R i for

[0044] R i =NP i =NQ i ”=r0+y mi

[0045] Laser beam focus scanning trajectory point P i The remaining cutting depth QQ" is p i for

[0046] p i =R i -r i

[0047] The remaining feed amount PQ is z i for

[0048]

[0049] It can be seen that for any processing position on the grinding wheel surface, the remaining feed amount z i and the remaining cutting depth p i The following relationship exists:

[0050]

[0051] This formula is named the cutting depth-feed relationship. It is not difficult to see that when the remaining cutting depth is zero, the remaining feed amount is also zero. At this time, the laser beam feed is completed and the processing is completed. At the same time, based on the cutting depth-feed relationship, the laser dressing process of superabrasive grinding wheels can be further optimized, as shown in steps 5 and 6.

[0052] So far, this step has obtained all the laser beam focus scanning trajectory points P i The corresponding remaining feed amount z i and relative feed amount dz i , then P i (x i ,y i ,z i ), (i=1,2,3,...,n) corresponds to the point set projected on the cutting plane is P i '(x i ,0,z i ),(i=1,2,3,...,n).

[0053] Step 4: Fitting the relative feed function of the laser beam: Repeat step 3 to obtain the remaining feed amount z corresponding to all focal scanning trajectory points i (i=1,2,3...n) perform least squares quadratic curve fitting to obtain the relative feed function s and the relative feed amount dz of the laser beam for a single scan i (i=1,2,3...n).

[0054] In this step, the least squares fitting relative feed function s is calculated as follows:

[0055] Suppose the linear combination of the function to be solved is z(x)=a0+a1x+a2x 2

[0056] Assume that the point set corresponding to the projection of all laser beam focus scanning trajectory points on the cutting plane has been measured in step 3 as P i '(x i ,0,z i ), (i=0,1,2,3,...,n). Then we can calculate

[0057]

[0058]

[0059] The values ​​of a0, a1, and a2 are calculated and solved, that is, the relative feed function s-curve equation z(x) = a0 + a1x + a2x in a single scan is obtained. 2 , the relative feed amount of the laser beam at each point during a single scan is

[0060] dz i =z i -z0

[0061] Where z0 is the remaining feed amount of the laser beam focus scanning trajectory point P0'(0,0,z0) as shown in Figure 5 shown.

[0062] Step 5: No-feed cutting depth setting:

[0063] Based on the cutting depth-feed relationship proposed in step 3, a cutting depth setting method in the vertical direction of the grinding wheel without laser beam feeding is proposed. This method consists of the following steps:

[0064] Step (1), adjust and set the focal plane of the laser beam in the vertical direction to the same height as the motor spindle (grinding wheel rotation center).

[0065] Step (2), using the trial cutting method to perform tangential tool alignment of the grinding wheel, adjusting the focus of the laser beam to just cut the tangential surface of the grinding wheel.

[0066] Step (3), such as Figure 5 As shown in the figure, a CCD camera is used to collect and obtain the starting contour point Q0" (0, y0, 0) on the actual contour line m of the grinding wheel within the base surface. The initial cutting depth of this point is

[0067] p 初始 =y 0

[0068] Step (4), adjust the laser beam height to the initial feed position

[0069]

[0070] Tool setting completed

[0071] Step 6: Precise and targeted removal of high points of the grinding wheel:

[0072] Based on the cutting depth-feed relationship proposed in step 3, a targeted and precise removal method for high points of surface profile during grinding wheel laser dressing is proposed. The method consists of the following steps:

[0073] Step (1), use a CCD camera to collect and obtain the protruding high point (difficult-to-process point) Q on the actual profile line m of the grinding wheel within the base surface 高 ”(0,y 高 ,0), then the cutting depth of this point is

[0074] p 高 =y 高

[0075] Step (2), adjust the laser beam height to the highest point and remaining feed amount position

[0076]

[0077] At this point, the high point target position of the laser beam focus has been determined.

[0078] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A method for high-efficiency laser shaping of a forming grinding wheel based on zoom profiling feed control, characterized in that: The following steps are involved: Step 1. Establish the base plane coordinate system: Establish the grinding wheel base plane coordinate system xoy in the horizontal plane; where O is the shortest radial distance point on the ideal profile line of the grinding wheel in the base plane, the OX axis is parallel to the rotation axis of the grinding wheel, O-xyz is the spatial rectangular coordinate system, and the vertical upward direction is the positive direction of the Z axis, and the direction away from the center of the grinding wheel is the positive direction of the Y axis; Step 2, obtaining the actual profile line of the grinding wheel: using a CCD camera to collect a cross-sectional view of the actual profile line of the grinding wheel within the base surface and obtain the coordinates of each point of the actual profile line within the base surface; Step 3: Calculate the remaining feed amount of the laser beam focus: Calculate all focus scanning trajectory points P i (x i ,y i ,z i ), (i=1,2,3...n) corresponding to the remaining feed amount z i (i=1,2,3...n); remaining feed amount z i The calculation formula is as follows: For any processing position on the grinding wheel surface, the remaining feed amount z i and the remaining cutting depth p i The following cutting depth and feed relationship exists: In the formula, R i is the radial distance of the grinding wheel, r i is the ideal radial distance of the grinding wheel, r0 is the ideal radius of the grinding wheel, y mi is the Y-axis coordinate of the actual profile line of the grinding wheel, y ni is the Y-axis coordinate on the ideal profile line of the grinding wheel, p i =R i -r i ; Step 4: Fitting the relative feed function of the laser beam: Repeat step 3 to obtain the remaining feed amount z corresponding to all focal scanning trajectory points i (i=1,2,3...n) perform least squares quadratic curve fitting to obtain the relative feed function s and the relative feed amount dz of the laser beam for a single scan i (i=1,2,3...n); Step 5, cutting depth calibration without feed: Based on the cutting depth-feed relationship proposed in step 3, cutting depth calibration in the vertical direction of the grinding wheel without laser beam feed is performed; Step 6: Precise and targeted removal of grinding wheel high points: Based on the cutting depth and feed relationship proposed in step 3, the high points of the surface profile are precisely removed during the grinding wheel laser dressing process.

2. According to claim 1, a method for high-efficiency laser shaping of a forming grinding wheel based on zoom profiling feed control is characterized in that: In step 5, the feed-free cutting depth setting consists of the following steps: Step 51, adjusting the focal plane of the laser beam in the vertical direction to be at the same height as the rotation center of the grinding wheel; Step 52, use the trial cutting method to perform tangential tool setting of the grinding wheel, and adjust the focus of the laser beam to just cut the tangential surface of the grinding wheel; Step 53: Use the CCD camera to collect and obtain the starting contour point Q0" (0, y0, 0) on the actual contour line of the grinding wheel within the base surface. The initial cutting depth of this point is pinitial = y0; Step 54: Adjust the laser beam height to the initial feed position Tool setting is completed.

3. According to claim 1, a method for high-efficiency laser shaping of a forming grinding wheel based on zoom profiling feed control is characterized in that: In step 6, the precise targeted removal of the high points of the grinding wheel consists of the following steps: Step 61: Use the CCD camera to collect and obtain the high point Q high" (0, y high, 0) on the actual profile line of the grinding wheel within the base surface. The cutting depth of this point is pheight = yheight; Step 62: Adjust the laser beam height to the highest point and the remaining feed amount position At this point, the high point target position of the laser beam focus has been determined.

Images