A method and device for automatic positioning of workpiece grinding based on laser displacement measurement

Abstract

This invention discloses a method and device for automatic workpiece positioning during polishing based on laser displacement measurement. Currently, this method is primarily used for machining circular workpieces with high precision requirements, such as engine blisks and casings. The device comprises a robot, a laser displacement sensor, a computer, a rotary table, and a positioning tool. The method enables online measurement and positioning of workpieces on the rotary table, quickly determining the workpiece's offset error. It utilizes both automatic pre-machining adjustment and angular error compensation to achieve precise workpiece positioning.

Description

Technical Field

[0001] The present invention relates to a workpiece grinding automatic positioning method and device based on laser displacement measurement, belonging to the technical field of intelligent processing and intelligent detection. Background Art

[0002] In industrial manufacturing, many components, such as engine cases and blisks, have complex curved surfaces, leading to the widespread use of manual grinding and polishing processes using handheld pneumatic and electric tools for deburring and polishing. This manual process can lead to increased product defect rates, low efficiency, and uneven surface roughness in finished products. Grinding also generates large amounts of dust, which is harmful to human health.

[0003] In recent years, with the widespread adoption of industrial robots, more and more manufacturers have begun using robots to install electric or pneumatic tools for automated polishing. Robotic polishing solutions generally fall into two categories: one in which the robot loads the tool and secures the workpiece, and the other in which the robot grasps the workpiece and secures the tool. Compared to hand-held polishing, robotic deburring can significantly improve production efficiency and product yield. However, with increasing demands for product process standards, many manufacturing processes are no longer able to rely solely on traditional manual tool setting by operators. Traditional manual tool setting relies on visual judgment and experience, making it impossible to quantitatively assess the workpiece's positioning error range, leading to quality issues. Summary of the Invention

[0004] In order to overcome the problem of high workpiece positioning error during the above-mentioned grinding and polishing, the present invention proposes a method for accurately measuring the workpiece and automatically adjusting the workpiece position based on a laser displacement sensor, and achieves the purpose of precise workpiece positioning by combining theoretical calculation analysis with automatic control.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a workpiece grinding automatic positioning method based on laser displacement measurement, comprising the following steps:

[0006] Step 1: Set the position of the workpiece to be polished, and calculate the target position of the positioning and clamping slider according to the position of the workpiece to be polished and the contour shape of the workpiece; the workpiece position is the center of the circle of the workpiece to be polished;

[0007] Step 2: Control several positioning and clamping slides on the rotary table to slide to the target position on the rotary table to push the workpiece to the set position;

[0008] Step 3: Control the robot to drive the laser displacement sensor to move to the edge of the workpiece, control the rotary table to rotate so that it carries the workpiece to be polished and rotates around the center of the circle; at the same time, control the laser displacement sensor to collect circumferential data of the workpiece to be polished according to the sampling time interval;

[0009] Step 4: Calculate the radial eccentricity of the workpiece according to the circumferential data of the workpiece to be polished;

[0010] Step 5: Control the robot to drive the laser displacement sensor to measure the position of the positioning pin block on the workpiece and calculate the angular deviation;

[0011] Step 5: Calculate the movement amount of each positioning and clamping slider according to the radial eccentricity of the workpiece, so that the positioning and clamping slider slides on the rotary table, thereby pushing the workpiece to move to the set center position;

[0012] Step 6: Compensate and control the angular processing parameters of the rotary table according to the angular deviation, so that the angular deviation of the workpiece to be polished is corrected;

[0013] Step 7: The laser sensor detects the position and steering angle of the workpiece to be polished in real time, and determines whether the difference with the set position and angle exceeds the error threshold range. If so, it returns to step 1 and continues to iterate and perform correction several times until the error threshold is met and correction stops.

[0014] The plurality of positioning and clamping sliders are evenly distributed on the circumference of the rotating table and can slide on the rotating table from outside to inside or from inside to outside along the radius; the positioning and clamping sliders are slidably connected to the rotating table along the radial direction.

[0015] The collected circumferential data sample set is (θ i , δ i ),i∈(1,2,…,n),n is an equal fraction of the circumference, θ i is the angle of the i-th circle dividing point, δ i is θ i Radial deviation at position.

[0016] The eccentricity of the workpiece is calculated by The Fit method iteratively calculates the workpiece center position (X c ,Y c ), and compare it with the set target circle center position to obtain the circle center offset.

[0017] The angular calculation process is:

[0018] Control the laser displacement sensor to move to the position of the positioning pin block on the rotating table so that the laser sensor, the positioning pin block and the center of the circle are in a straight line. By controlling the rotating table to move several times, the laser displacement sensor measures the parameter value M of the positioning pin block and calculates the deviation angle. in, is the average value of M multiple measurements, R is the radius of the measurement position circle of the processed workpiece, is the desired angular deviation.

[0019] A workpiece grinding automatic positioning device based on laser displacement measurement includes a measuring device, an analysis and calculation system, and an adjustment device. The measuring device is used to collect workpiece position information and feed it back to the analysis and calculation system. The analysis and calculation system analyzes the measured information, determines the offset of the workpiece placement, and sends a position adjustment instruction to the adjustment device to change the workpiece offset to control the processing error within the allowable range.

[0020] The measuring device includes a laser displacement sensor at the end of the robot arm, which is used to collect workpiece position information and feed it back to the analysis and calculation system;

[0021] The analysis and calculation system includes a program installed on a computer; the computer communicates with the robot and the laser displacement sensor via a communication cable 1, and communicates with the rotary table and a plurality of positioning and clamping slides via a communication cable 2;

[0022] The adjustment device includes a rotary table on which are provided a plurality of positioning and clamping slide blocks for positioning and clamping the workpiece to be polished. The rotary table rotates to drive the workpiece to be processed to rotate.

[0023] The rotation range of the rotary table is not less than 360 degrees.

[0024] There are three positioning and clamping sliders: positioning and clamping slider 1, positioning and clamping slider 2, and positioning and clamping slider 3, which are evenly distributed on the rotating workbench at intervals of 120 degrees.

[0025] The three slides are controlled to rise and fall by means of pneumatic signals to complete the clamping and loosening of the workpiece. Each slide is equipped with a servo motor. The computer controls the feed amount of each slide individually through the communication cable 2 to complete the adjustment of the workpiece in a single direction.

[0026] The present invention has the following advantages:

[0027] This invention integrates control of the platform's various subsystems, enabling workpiece position measurement, analysis, and adjustment for loading and unloading deviations. This control process matches the workpiece model with the robot program and integrates control signals from the positioning measurement block, making the entire measurement process safe and efficient. This invention eliminates manual tool setting by the operator, significantly improving the operator's working environment and workpiece processing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Flow chart of the method of the present invention;

[0029] Figure 2 This is a system structure diagram of the present invention;

[0030] Figure 3 This is a modeling diagram for adjusting the workpiece position of the rotating platform of the present invention;

[0031] Figure 4 This is a top view of the positional relationship among the laser, workpiece, and positioning pin block during angular measurement of the present invention; DETAILED DESCRIPTION

[0032] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, the specific implementation methods of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the invention. Therefore, the present invention is not limited to the specific implementation methods disclosed below.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art of the art to which the present invention pertains. The terms used in the specification of the invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention.

[0034] The present invention provides a method and device for automatic positioning of workpiece grinding based on laser displacement measurement. The present invention will be further described in detail below with reference to an example of positioning of a casing part.

[0035] The present invention relates to a device for automatic positioning of workpiece grinding based on laser displacement measurement. The device adopted in the implementation of the present invention consists of an industrial robot, a robot end clamping tool, a laser displacement sensor, a computer control system, a rotary worktable, and three positioning tool slides. The present invention adopts a Kuka KR60 industrial robot and a Keyence displacement sensor.

[0036] The overall structure of this system is as follows Figure 2 As shown, it includes a robot 1, a connecting device 2, a laser displacement sensor 3, a computer 4, a rotary table 5, a workpiece 6, a first positioning and clamping slider 7, a second positioning and clamping slider 8, a third positioning and clamping slider 9, an angular positioning pin block 10, a first communication cable 11, and a second communication cable 12. Among them, the robot 1 and the laser displacement sensor 3 are fixedly connected through the connecting device 2, and the workpiece 6 to be processed is fastened to the rotary table 5 through the first positioning and clamping slider 7, the second positioning and clamping slider 8, and the third positioning and clamping slider 9. The rotary table 5 drives the workpiece 6 to be processed to rotate by rotating. The computer 4 communicates with the robot 1 and the laser displacement sensor 3 through the first communication cable 11, and communicates with the rotary table 5 and the first positioning and clamping slider 7, the second positioning and clamping slider 8, and the third positioning and clamping slider 9 through the second communication cable 12. The control system is installed on the industrial computer, and the upper computer is connected to the robot, the displacement sensor, and the rotary table through a network cable. The positioning tooling is installed on the rotary table. The layout of the rotary table is as shown Figure 3 As shown, the rotary table 5 has three grooves for slide rails evenly distributed from the center outward. Positioning and clamping sliders are slidably connected to the slide rails. Each slider is equipped with a servo motor that receives control signals from the computer 4 and moves according to the feed rate. Pneumatic suction cups are installed on the positioning and clamping sliders to clamp the workpiece to be polished.

[0037] The present invention relates to a method for automatic positioning of workpiece grinding based on laser displacement measurement, comprising the following steps:

[0038] During the grinding and polishing process, the grinding and polishing equipment needs to first determine the position of the workpiece through the measurement and analysis software system on the computer. The specific steps include:

[0039] 1) The operator selects the model and specifications of the workpiece to be processed on the computer. The measurement and analysis software system sends a motion clamping instruction to the positioning clamping slider according to the set target position of the positioning clamping slider based on the model of the workpiece to fix the workpiece.

[0040] 2) The measurement and analysis software system sends motion instructions to robot 1 and rotary table 5 based on the workpiece model to measure a standard circumferential feature of the workpiece. Robot 1 and rotary table 5 work in tandem to collect circumferential data. Rotary table 5 resets, and robot 1 drives laser displacement sensor 3 to measure the positioning block on workpiece 6, determining angular deviation.

[0041] 3) Based on the circumferential data of workpiece 1, the eccentricity of workpiece 1 is analyzed and calculated. The measurement and analysis software system controls the positions of the first, second, and third positioning slides to align workpiece 1. The angular deviation is calculated and corrected during the machining process.

[0042] 4) When the positioning accuracy requirement is high, the workpiece 1 can be measured and aligned multiple times until the processing requirements are met.

[0043] Among them, the sample set (θ i , δ i ),i∈(1,2,…,n),n is an equal fraction of the circumference, θ i is the angle of the i-th circle dividing point, τ i is θ i Radial deviation at position, applying classic The Fit method is used to iteratively calculate the center position of workpiece 1 (X c ,Y c ), and compare it with the standard circle center position (0,0) to get the circle center offset.

[0044] The specific calculation steps are:

[0045] Sample set (θ i , δi ) is transformed into a plane coordinate set (X i ,Y i ).

[0046] Where: R is the radius of the workpiece 1;

[0047] X i =(R+δ i )*cosθ i ;

[0048] Y i =(R+δ i )*sinθ i ;

[0049] make:

[0050] The sum of the original data point X SUM_X;

[0051] The sum of the original data Y points SUM_Y;

[0052] The sum of squares of the original data X SUM_XSquare;

[0053] The sum of squares of the original data Y SUM_YSquare;

[0054] The cube of the original data X and SUM_XCube;

[0055] The cube of the original data Y and SUM_YCube;

[0056] The sum of the original data XYY is SUM_XYY;

[0057] The sum of the original data XY SUM_XY;

[0058] The sum of the original data XXY is SUM_XXY;

[0059] Define the parameters D, C, E, G, H used for fitting;

[0060] The process of obtaining is:

[0061] D = N * SUM_XY - SUM_X * SUM_Y;

[0062] C=N*SUM_XSquare-SUM_X*SUM_X;

[0063] E=N*SUM_XCube+N*SUM_XYY-(SUM_XSquare+SUM_YSquare)*SUM_X;

[0064] G=N*SUM_YSquare-SUM_Y*SUM_Y;

[0065] H=N*SUM_YCube+N*SUM_XXY-(SUM_XSquare+SUM_YSquare)*SUM_Y;

[0066] Find the parameters a, b, and c.

[0067] a=(H*DE*G) / (C*GD*D);

[0068] b=(H*CE*D) / (D*DG*C);

[0069] c=-((SUM_XSquare+SUM_YSquare)+a*SUM_X+b*SUM_Y) / N;

[0070] The center value is:

[0071] X c =-0.5*1.00000*a;

[0072] Y c =-0.5*1.00000*b;

[0073] R=0.5*1.00000*sqrt(a*a+b*b-4*c);

[0074] Step 3: If Figure 4 As shown, the angular calculation process is that the laser displacement sensor 3 measures the positioning pin block multiple times at a fixed position, and the deviation angle is calculated based on the measurement value M of the laser displacement sensor 3. is the average value of M multiple measurements, R is the radius of the measurement position circle of the processing workpiece 1, is the desired angular deviation. This process requires specific angular machining positions for different features on the circumference to prevent angular deviation from damaging the workpiece 1. The line connecting the laser and the dowel block is located tangentially to the circle. The measured value M is the chord length corresponding to the difference between the actual and ideal dowel block arc lengths.

[0075] Step 4: The computer 4 sends a position adjustment instruction to the positioning and clamping slider on the workbench 5. The specific implementation process is to perform calculations in the measurement and analysis system to determine the movement amount of each positioning and clamping block. Figure 3 As shown, by (X c , Y c ) value to calculate the offset of M1, M2, and M3, defining the clamping slider to move outward as positive and inward as negative, specifically:

[0076] M1=X c *tan(30°)-Y c

[0077] M2=M1 / sin(30°)-X c / cos(30°)

[0078] M3=M1 / sin(30°)+X c / cos(30°)

[0079] The three positioning and clamping slides are controlled to move backward and then forward (making room for the slide to move) to push the workpiece to adjust its position. The angular deviation is compensated to the angular processing position in the processing program during processing.

[0080] Step 5: Each workpiece is assigned a set of measurement parameters (position and steering angle of the workpiece to be ground) and a measurement procedure. After setting the error threshold, the measurement and adjustment process is automated until the error is within the set threshold. Tool setting is completed quickly and safely using a non-contact method.

[0081] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should be regarded as within the scope of protection of the present invention.

Claims

1. A method for automatic positioning of workpiece grinding based on laser displacement measurement, characterized in that: The following steps are involved: Step 1: Set the position of the workpiece to be polished, and calculate the target position of the positioning and clamping slider according to the position of the workpiece to be polished and the contour shape of the workpiece; the workpiece position is the center of the circle of the workpiece to be polished; Step 2: Control several positioning and clamping slides on the rotary table to slide to the target position on the rotary table to push the workpiece to the set position; Step 3: Control the robot to drive the laser displacement sensor to move to the edge of the workpiece, control the rotary table to rotate so that it carries the workpiece to be polished and rotates around the center of the circle; at the same time, control the laser displacement sensor to collect circumferential data of the workpiece to be polished according to the sampling time interval; Step 4: Calculate the radial eccentricity of the workpiece according to the circumferential data of the workpiece to be polished; Step 5: Control the robot to drive the laser displacement sensor to measure the position of the positioning pin block on the workpiece and calculate the angular deviation; Step 6: Calculate the movement amount of each positioning and clamping slider according to the radial eccentricity of the workpiece, so that the positioning and clamping slider slides on the rotary table, thereby pushing the workpiece to move to the set center position; Step 7: Compensate and control the angular processing parameters of the rotary table according to the angular deviation, so that the angular deviation of the workpiece to be polished is corrected; Step 8: The laser sensor detects the position and steering angle of the workpiece to be polished in real time, and determines whether the difference with the set position and angle exceeds the error threshold range. If so, return to step 1 and continue to iterate and perform correction several times until the error threshold is met and correction stops.

2. The method for automatic positioning of workpiece polishing based on laser displacement measurement according to claim 1, characterized in that: The plurality of positioning and clamping sliders are evenly distributed on the circumference of the rotating table and can slide on the rotating table from outside to inside or from inside to outside along the radius; the positioning and clamping sliders are slidably connected to the rotating table along the radial direction.

3. The method for automatic positioning of workpiece polishing based on laser displacement measurement according to claim 1, characterized in that: The collected circumferential data sample set is (θ i , δ i ),i∈(1,2,…,n),n is an equal fraction of the circumference, θ i is the angle of the i-th circle dividing point, δ i is θ i Radial deviation at position.

4. The method for automatic positioning of workpiece polishing based on laser displacement measurement according to claim 1, characterized in that: The eccentricity of the workpiece is calculated by The Fit method iteratively calculates the workpiece center position (X c ,Y c ), and compare it with the set target center position to obtain the radial deviation of the center.

5. The method for automatic positioning of workpiece polishing based on laser displacement measurement according to claim 1, characterized in that: The angular calculation process is: Control the laser displacement sensor to move to the position of the positioning pin block on the rotating table so that the laser sensor, the positioning pin block and the center of the circle are in a straight line. By controlling the rotating table to move several times, the laser displacement sensor measures the parameter value M of the positioning pin block and calculates the deviation angle. in, is the average value of M multiple measurements, R is the radius of the measurement position circle of the processed workpiece, is the desired angular deviation.

6. A workpiece grinding automatic positioning device based on laser displacement measurement, characterized in that: The device includes: a measuring device, an analysis and calculation system, and an adjustment device; The measuring device includes a laser displacement sensor (3) at the end of the robot (1) arm, which is used to collect workpiece position information and feed it back to the analysis and calculation system; The analysis and calculation system includes a program installed on a computer (4), and when the program is loaded, the method described in any one of claims 1 to 5 is executed, and the measured information is analyzed to determine the offset of the workpiece placement, and a position adjustment instruction is sent to the adjustment device to change the offset of the workpiece to control the processing error within the allowable range, thereby realizing automatic positioning of the workpiece grinding; the computer (4) communicates with the robot (1) and the laser displacement sensor (3) through the communication cable 1 (11), and communicates with the rotary worktable (5) and a plurality of positioning and clamping slides through the communication cable 2 (12); The adjustment device comprises a rotary table (5) on which are provided a plurality of positioning and clamping slide blocks for positioning and clamping a workpiece (6) to be polished. The rotary table (5) rotates to drive the workpiece (6) to be polished to rotate.

7. The workpiece polishing automatic positioning device based on laser displacement measurement according to claim 6, characterized in that: The rotating range of the rotating workbench (5) is not less than 360 degrees.

8. The automatic positioning device for workpiece grinding based on laser displacement measurement according to claim 6, characterized in that: There are three positioning and clamping sliders: positioning and clamping slider 1 (7), positioning and clamping slider 2 (8), and positioning and clamping slider 3 (9), which are evenly distributed on the rotating workbench (5) at intervals of 120 degrees.

9. The automatic positioning device for workpiece polishing based on laser displacement measurement according to claim 6, characterized in that: The workpiece is clamped and released by controlling the rise and fall of three slides through pneumatic signals. Each slide is equipped with a servo motor. The computer (4) controls the feed rate of each slide individually through the communication cable 2 (12) to adjust the workpiece in a single direction.

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