High-precision automatic grinding method for water-guided laser chopper based on PLC

Abstract

The invention discloses a PLC-based high-precision automatic grinding method for a water-guided laser chopper, which effectively reduces a heat affected zone through the cooling effect of water-guided laser, reduces heat damage and ensures the smoothness and dimensional precision of the surface of the chopper. A PLC (programmable logic controller) control system is introduced, an industrial robot and a high-precision sensor are combined, four key procedures including FA, OR, BP and IC and full-automatic control and monitoring of a grinding path, laser power and water flow pressure are achieved, the machining efficiency of a production line is greatly improved, and precise machining and intelligent management of the production process are achieved. The result shows that the method shows excellent performance in the aspects of surface quality, grinding precision, production efficiency and environmental protection, and particularly has obvious advantages in the aspects of fine machining, continuous production and green manufacturing. Through automatic and intelligent control, the PLC technology can improve the production efficiency to the maximum extent, the labor cost is reduced, and meanwhile, the stability of the product quality is ensured.

Description

Technical Field

[0001] The invention relates to a high-precision automatic grinding method for a water-conducting laser splitting tool based on PLC, and relates to the fields of laser processing, precision material surface treatment and automatic control. Background Art

[0002] In recent years, with the rapid development of medical, aviation, aerospace, semiconductor, and energy fields, the performance requirements for key components have become increasingly higher, which has promoted the improvement and improvement of parts processing methods and equipment. In the field of parts cutting, compared with traditional mechanical cutting, high-pressure water cutting and laser cutting, water-guided laser cutting technology, as a new cutting technology, has obvious advantages in processing efficiency, processing accuracy, and workpiece quality and environmental protection. Water-guided laser cutting meets the requirements of high precision and high efficiency of parts; achieves environmental pollution-free, in line with the concept of green manufacturing; reduces thermal damage to materials and extends the service life of materials. The advantages of laser cutting give it a good application prospect in many fields.

[0003] The current methods of cleaver grinding mainly include mechanical grinding, laser grinding, chemical mechanical polishing (CMP), and ultrasonic assisted grinding. The mechanical grinding method mainly consists of three stages: rough grinding, fine grinding, and polishing, and the whole process requires the use of coolant to avoid overheating and cracking of the material. The laser grinding method mainly uses high-power ultrashort pulse lasers for non-contact processing, and removes micron-level material layers layer by layer through laser scanning to ensure the fineness and high finish of the blade. Chemical mechanical polishing is the removal of materials by combining chemical reaction and mechanical cutting under the joint action of polishing pads and chemical polishing liquid. Ultrasonic assisted grinding mainly introduces ultrasonic vibrations into traditional mechanical grinding to reduce processing stress, and enhances the cutting effect of the grinding wheel on the ceramic surface through micro-vibration, thereby improving surface finish and processing efficiency.

[0004] In modern manufacturing, the precision and surface flatness of workpieces are key. The current mainstream grinding methods are prone to thermal damage and microcracks, making it difficult to meet sub-micron precision and ineffective for complex shapes; it is difficult to achieve high surface finish; abrasive wear is severe and processing consistency is poor. Although some methods such as chemical mechanical polishing have high precision, they are inefficient and have a heavy environmental burden, especially on complex workpieces. Water-guided laser grinding makes up for the shortcomings of the above methods and has significant advantages. Its water-guided technology quickly dissipates heat, avoids thermal damage, and ensures the integrity of the surface structure; the processing accuracy can reach the nanometer level, and high finish can be obtained without additional processing; non-contact processing is suitable for complex shapes and fine structures, without shape restrictions. In addition, this technology does not require chemical reagents and abrasives, is green, environmentally friendly and efficient.

[0005] On this basis, considering the high requirements for precision, thermal damage control and processing efficiency in the splitting knife processing process, we proposed a solution that combines PLC control with water-guided laser technology. We use the high precision and significant cooling effect of water-guided laser to process heat-sensitive ceramic materials. At the same time, we use PLC to dynamically adjust and feedback key processing steps, optimize the path through interpolation algorithm, adjust laser power and water flow pressure based on PID closed-loop control, and monitor surface quality data through real-time sensors and implement compensation strategies. Summary of the invention

[0006] The purpose of the present invention is to address the problems of low precision, low efficiency, large thermal damage to the workpiece and easy environmental pollution in the existing splitting knife grinding method, and propose a high-precision automatic grinding method of water-guided laser splitting knife based on PLC. This method uses water-guided laser for splitting knife grinding, combined with PLC full-automatic control, to maximize the precision and efficiency of splitting knife grinding, and minimize workpiece damage, environmental pollution and consumption of manpower and material resources. The proposed method can greatly improve the durability of the splitting knife.

[0007] The key technology proposed by the present invention to solve the technical problem is: a high-precision automatic grinding method of a water-guided laser whet cutter based on PLC, the method comprising the following steps:

[0008] Step 1: Initialization and parameter setting;

[0009] Step 1-1: Start the PLC control system, load the preset processing program, and enter the processing parameters;

[0010] Step 1-2: Run the self-diagnosis program;

[0011] Step 1-3: calibrate the laser beam focal position;

[0012] Step 1-4: Adjust the water jet nozzle angle and laser focus offset;

[0013] Step 2: Workpiece positioning;

[0014] Step 2-1: Precise positioning of the riving knife;

[0015] Step 2-2: Confirm the workpiece boundary and angle;

[0016] Step 2-3: Determine whether the workpiece is aligned with the processing starting point;

[0017] Step 3: Surface chamfering and grinding;

[0018] Step 3-1: Start the laser and control the relative movement between the laser head and the workpiece;

[0019] Step 3-2: Generate chamfering processing path and adjust the position of XYZ axis servo motor in real time;

[0020] Step 3-3: Automatically keep the laser focus on the workpiece surface;

[0021] Step 3-4: Dynamically adjust the water jet pressure to maintain cutting thermal balance and avoid overheating and cracking of the ceramic material surface;

[0022] Step 3-5: Collect the processing surface data in real time and make compensation based on the deviation data;

[0023] Step 4: External chamfer R grinding;

[0024] Step 4-1: Generate smooth machining trajectory;

[0025] Step 4-2: The laser head tracks the R corner contour according to the path;

[0026] Step 4-3: Adjust the laser power in real time to ensure processing accuracy;

[0027] Step 5: Tungsten wire expansion and polishing;

[0028] Step 5-1: The laser head is positioned at the tungsten wire hole, and the laser outputs high-power pulses. The water jet is sprayed synchronously to take away the cutting debris and prevent secondary thermal effects;

[0029] Step 5-2: Interaction between laser beam and water jet to reduce surface roughness;

[0030] Step 5-3: Optimize the laser head motion trajectory to improve surface finish;

[0031] Step 6: Grinding the inner chamfer;

[0032] Step 6-1: The laser head enters the inner cavity of the workpiece and completes the inner chamfer path tracking;

[0033] Step 6-2: Detect processing pressure and adjust laser output;

[0034] Step 6-3: Control laser power to avoid micro cracks in ceramic materials;

[0035] Step 7: End of processing and cleaning;

[0036] Step 7-1: The laser and water jet are turned off, and the servo motor stops;

[0037] Step 7-2: Move the workpiece to the unloading area;

[0038] Step 7-3: The laser head nozzle and water jet pipeline perform an automatic flushing procedure to prevent impurities from remaining;

[0039] Step 7-4: The waste processing module removes the cutting debris into a designated container;

[0040] Step 8: Data recording and storage;

[0041] Step 8-1: Processing parameters, quality inspection data and path deviation data are uploaded to the industrial database through PLC;

[0042] Step 8-2: Upload data to the cloud platform for subsequent production optimization and process improvement;

[0043] Further, step 1 of the present invention includes starting the PLC control system, loading a preset processing program, inputting or confirming processing parameters through a human-machine interface (HMI), the system running a self-diagnosis program, checking the status of key components, calibrating the laser beam focus position using a laser alignment module (LDAM), adjusting the laser power using a proportional integral differential (PID) controller, controlling the water jet pressure in a closed loop through a proportional valve and a pressure sensor, importing a processing path file generated by CAD / CAM, generating a coordinate point cloud using offline programming, optimizing the path through a PLC interpolation algorithm, adjusting the water jet nozzle angle and the laser focus offset to ensure that the two are coaxial, and the specific steps are:

[0044] Step 1-1: Start the PLC control system, load the preset processing program, and enter or confirm the processing parameters through the human-machine interface (HMI).

[0045] Step 1-2: Run the self-diagnosis program to collect the signals of the spindle system, grinding tool, cooling system, motor and transmission system sensors, and calculate the mean μ and variance σ of the signals. 2 , Kurtosis γ 2 , kurtosis β and other basic statistical characteristics, N is the sample size, x i is the i-th data under the same index, μ, σ 2 , γ 2 and β can be expressed as:

[0046]

[0047]

[0048] Use Fast Fourier Transform (FFT) to convert the signal from the time domain to the frequency domain and identify the characteristic frequency components. X(k) is the kth frequency component of the frequency domain signal, x(n) is the nth sample of the time domain signal, N is the total number of samples of the signal, k is the frequency index, and FFT can be expressed as:

[0049]

[0050] Use wavelet transform to perform time-frequency analysis to capture transient features in non-stationary signals. ψ (a, b) is the wavelet transform coefficient, a is the scale parameter, b is the translation parameter, ψ is the wavelet function, t is the time, and the mathematical expression of the wavelet transform is:

[0051] Through the support vector machine (SVM), set the feature vector x and classification label K dj y, diagnose the system working status by constructing a decision boundary,

[0052] Step 1-3: Use the laser alignment module (LDAM) to calibrate the laser beam focus position, and use the proportional-integral-differential (PID) controller to achieve precise adjustment of the laser. e(t) is the laser target deviation error, Kp, Ki, Kd are control gains, and the control output signal u(t) can be expressed as:

[0053]

[0054] u(t) acts as a control signal and acts on the actuator or regulating element that controls the laser calibration to adjust the system state and achieve accurate laser calibration.

[0055] Steps 1-4: Use the PID controller to adjust the water jet nozzle angle and laser focus offset to ensure that they are coaxial.

[0056] Furthermore, step 2 of the present invention includes: accurately positioning the splitting knife by a pneumatic or servo-driven clamping device, confirming the boundary and angle of the workpiece by using an industrial camera and an image processing algorithm, and receiving a sensor feedback signal by a PLC to determine whether the workpiece is aligned with the processing starting point. The specific steps are:

[0057] Step 2-1: Use a closed-loop control system to feedback the real-time position error and adjust the motor speed and position to achieve precise positioning of the chopper.

[0058] Step 2-2: Use an industrial camera to extract a color image of the workpiece, and use Canny edge detection, morphological processing, feature extraction, and geometric analysis to identify the boundaries and angles of the workpiece. The Sobel operator in Canny edge detection is defined as:

[0059]

[0060] The calculation formula of gradient amplitude G and direction angle θ is:

[0061]

[0062] Morphological processing operates on binary images using structural elements and repairs edge discontinuities or extracts specific shapes, using geometric analysis to calculate the exact boundaries and angles of artifacts by fitting straight lines using the least squares method;

[0063] Step 2-3: Receive the sensor feedback signal through PLC, substitute the signal parameters into the PID controller, determine whether the workpiece is aligned with the processing starting point and make adjustments.

[0064] Furthermore, step 3 of the present invention includes starting the laser, controlling the relative movement of the laser head and the workpiece according to the path planning, generating the chamfering processing path through the spatial interpolation algorithm, adjusting the position of the XYZ axis servo motor in real time, automatically keeping the laser focus on the workpiece surface through the real-time tracking algorithm, dynamically adjusting the water jet pressure, maintaining the cutting thermal balance, avoiding overheating and cracking of the ceramic material surface, the photoelectric sensor and the thermal sensor collect the processing surface data in real time, and the PLC compensates based on the deviation data. The specific steps are:

[0065] Step 3-1: Determine the position and posture of the laser head relative to the workpiece through forward and inverse kinematics modeling. T represents the spatial position and posture of the tool end, f is the kinematic function, Θ is the joint angle set, x, y, z are the spatial coordinates of the tool end, and forward and inverse kinematics can be expressed as:

[0066] T=f(θ1,θ2,…,θn) Θ=f-1(x, y, z);

[0067] The circular interpolation algorithm is used to generate the optimal path from the starting point to the end point, (x c ,y c ) is the center of the circle, r is the radius of the circle, θ(t) is the angle parameter, x(t), y(t) are the positions of the center of the circle at time t. The mathematical formula related to the circular interpolation algorithm can be expressed as:

[0068] x(t)=x c + r·cos(θ(t)),y(t)=y c + r·sin(θ(t));

[0069] Use gradient descent to solve the optimality of the path to minimize the objective function such as moving time or path length, construct the loss function L related to path smoothness, speed, and acceleration, and define the loss function L related to the moving time T. 0 T f , path length L and energy dissipation The relevant objective function f(x) is as follows:

[0070]

[0071] The path is smoothed using the B-spline interpolation algorithm, and accurate path tracking is performed using the PID controller. P(t) is the anchor point at time t, n is the number of control points, and B i , k(t) is the control point P i The spline basis function of order k, P i is the control point. The B-spline interpolation algorithm can be expressed as:

[0072]

[0073] Step 3-2: Generate the chamfering processing path through the spatial interpolation algorithm and adjust the position of the XYZ axis servo motor in real time;

[0074] Step 3-3: Combine the camera, distance sensor and PID controller to dynamically adjust the position of the laser head;

[0075] Step 3-4: According to the temperature data provided by the temperature sensor, the water jet pressure is dynamically adjusted to maintain the cutting thermal balance and avoid overheating and cracking of the ceramic material surface;

[0076] Step 3-5: Photoelectric sensors and thermal sensors collect processing surface data in real time, and PLC performs compensation based on deviation data.

[0077] Furthermore, step 4 of the present invention includes external chamfering R angle grinding, using NURBS curve fitting to generate a smooth processing trajectory, the servo system synchronously controls the three-axis linkage, the laser head tracks the R angle contour according to the path, the laser power is adjusted in real time by the PLC, and the processing accuracy is ensured by sensor feedback and PID closed-loop control algorithm. The specific steps are:

[0078] Step 4-1: Generate a smooth machining trajectory using NURBS curve fitting and determine the number of control points, where n is the number of control points minus 1, P i is the control point, set the weight w of the control point i , N i,p (t) is the i-th B-spline basis function, with order p, and the knot vector U = {u 0 ,u 1 ,...,u m}, where m = n + p + 1, define the B-spline basis function N i,p The recursive relation of (t) is:

[0079]

[0080] n is the number of control points. A NURBS curve C(t) is defined at parameter t as:

[0081]

[0082] By adjusting the control points and weights, and using NURBS to adjust the control points and other parameters, the curve is made as close to the data points as possible, thus generating a smooth machining trajectory.

[0083] Step 4-2: Design the contour path through the CAD or CAM system, use the circular interpolation algorithm to calculate the instant position of each axis to form a smooth motion trajectory. Each axis is driven by a servo motor, the feedback system provides position information, and the PID controller adjusts the motion parameters in real time to ensure high-precision tracking. The central controller coordinates the synchronous movement of each axis to achieve accurate path tracking in three-dimensional space.

[0084] Step 4-3: PLC adjusts the laser power in real time, and ensures processing accuracy through sensor feedback and PID closed-loop control algorithm. Position control requires error correction of the XYZ axes at the same time. pj , K ij , K dj (j=x,y,z) is the proportional gain, integral gain and differential gain, e x (t), e y (t), e z (t) is the position signal error of each axis. The formula for controlling the XYZ axis is as follows:

[0085]

[0086] Through precise PID parameter adjustment, PLC can ensure accurate tracking of the laser head on complex surfaces and achieve the required processing accuracy.

[0087] Furthermore, step 5 of the present invention includes tungsten wire expansion and polishing, the laser head is positioned at the tungsten wire hole position, the PLC controls the laser to output high-power pulses, the water jet is sprayed synchronously, the cutting debris is taken away, and the secondary heat effect is prevented, the PLC switches to a low-power pulse mode, the laser beam and the water jet interact to reduce the surface roughness, the PLC executes a dynamic model prediction algorithm, optimizes the laser head motion trajectory, and improves the surface finish. The specific steps are:

[0088] Step 5-1: The laser head is positioned at the tungsten wire hole, the PLC controls the laser to output high-power pulses, and the water jet is sprayed synchronously to take away the cutting debris and prevent secondary thermal effects.

[0089] Step 5-2: The PLC switches to low-power pulse mode, and the interaction between the laser beam and the water jet reduces the surface roughness.

[0090] Step 5-3: Design the objective function J to minimize the deviation of the future output from the reference trajectory and the change in the control input, where r(t+k) is the desired reference trajectory and y(t+k) is the actual trajectory. represents the quadratic norm with weight matrices Q and R, which is used to constrain the change of deviation and control force, Δu(t+k)=u(t+k)-u(t+k-1) represents the change of control input, N p 、N eis the control point, and the objective function J can be expressed as:

[0091]

[0092] By continuously adjusting the motion path of the laser head, MPC can solve the above optimization problem to obtain the optimal control input and provide real-time feedback on the optimized trajectory, thereby effectively improving the surface finish.

[0093] Furthermore, step 6 of the present invention includes: inner chamfer grinding, the laser head enters the inner cavity of the workpiece, completes the inner chamfer path tracking by small radius arc interpolation, uses a force sensor to detect the processing pressure, and the PLC adjusts the laser output according to the feedback. The inner wall adopts adaptive laser power control (ALPC) technology to avoid micro cracks in the ceramic material. The specific steps are:

[0094] Step 6-1: The laser head enters the inner cavity of the workpiece and completes the inner chamfer path tracking through small radius arc interpolation.

[0095] Step 6-2: Use a force sensor to detect the processing pressure, and the PLC adjusts the laser output based on the feedback.

[0096] Step 6-3: Use adaptive laser power control (ALPC) technology to monitor the temperature or molten pool characteristics in the ceramic material processing process in real time and dynamically adjust the laser power; use sensor feedback to obtain the status data of the processing point, and calculate the required laser power adjustment through PID to keep the processing conditions at the optimal state at all times, thereby avoiding the formation of microcracks caused by overheating.

[0097] Furthermore, step 7 of the present invention includes the end of processing and cleaning, turning off the laser, water jet and servo motor, PLC controlling the clamping system to release the workpiece, and moving the workpiece to the unloading area through the conveying device, the laser head nozzle and the water jet pipeline perform an automatic flushing procedure to prevent impurities from remaining, and the waste processing module removes the cutting debris to a designated container.

[0098] Furthermore, step 8 of the present invention includes data recording and storage, and processing parameters, quality inspection data and path deviation data are uploaded to the industrial database through PLC, and the data is uploaded to the cloud platform for subsequent production optimization and process improvement.

[0099] Beneficial effects:

[0100] 1. The water-conducting laser used in the present invention utilizes its high energy density and combines the thermal conductivity of water to not only greatly improve the processing accuracy, but also effectively avoid the thermal stress and mechanical stress generated in the traditional grinding process, and reduce workpiece damage; water-conducting laser grinding realizes non-contact processing, does not directly contact the workpiece, is more suitable for processing brittle ceramic materials, can reduce cracks and defects, and avoid mechanical wear and secondary pollution problems; water-conducting laser grinding technology does not generate a large amount of dust and thermal pollution, and through the heat conduction and cleaning effect of water flow, it greatly reduces the generation of pollutants in the processing process, is environmentally friendly and clean, and meets the requirements of modern green manufacturing.

[0101] 2. The present invention introduces PLC (Programmable Logic Controller), which realizes closed-loop control of the entire processing flow by real-time monitoring of the positioning, laser power, water flow and other parameters of the polished workpiece, thereby ensuring the consistency and reliability of the processing, reducing human errors and improving production efficiency; the PLC system realizes integrated sensor feedback and real-time adjustment of processing parameters (such as laser power and scanning speed) to adapt to different workpiece characteristics and surface requirements. It can dynamically adjust after detecting defects or uneven areas on the workpiece surface to achieve intelligent and adaptive polishing; through PLC control, the laser processing equipment can maintain stable operation under high load conditions, while real-time monitoring of water flow temperature, laser intensity and environmental conditions, thereby avoiding risks caused by improper operation or equipment overload.

[0102] 3. The present invention achieves nanometer-level (nm) grinding accuracy for the first time by precisely controlling the synergistic effect of the laser action area and the water flow. This accuracy greatly meets the stringent requirements of high-end splitters in the fields of semiconductors, optical devices, etc.; this technical solution achieves a double breakthrough in the accuracy and efficiency of water-guided laser grinding, setting a new standard for future high-precision ceramic grinding technology. The successful application of this technical solution of the present invention is expected to become a key process in the field of high-end manufacturing, providing a technical reference for the processing of other complex materials.

[0103] 4. The present invention utilizes a water-cooled laser combined with laser focusing and energy transmission technology to achieve high-precision, high-efficiency, low-loss, zero-pollution grinding of the splitter. Through the cooling effect of the water-cooled laser, the heat-affected zone is effectively reduced, thermal damage is reduced, and the surface finish and dimensional accuracy of the tool are guaranteed. In addition, the present invention introduces a PLC (programmable logic controller) control system, combined with industrial robots and high-precision sensors, to achieve four key processes: FA, OR, BP, IC, as well as fully automated control and monitoring of the grinding path, laser power, and water flow pressure, which greatly improves the processing efficiency of the production line, reduces manual intervention and errors, and realizes precision processing and intelligent management of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 The figure is a diagram of the overall system structure of the method proposed in the present invention.

[0105] Figure 2 The internal structure of the water-conducting laser polishing system of the present invention and a detailed schematic diagram of the laser transmission in water are shown.

[0106] Figure 3 The process flow chart of fully automatic grinding using PLC is shown.

[0107] Figure 4 A schematic diagram showing the comparison of the grinding quality, grinding accuracy, grinding efficiency and pollutant generation of the method proposed in the present invention and the traditional method when grinding high-purity silicon nitride ceramics. DETAILED DESCRIPTION

[0108] The invention is further described in detail below in conjunction with the accompanying drawings.

[0109] like Figure 1-Figure 4 As shown, the present invention provides a high-precision automatic grinding method for a water-guided laser whet cutter based on PLC, the method comprising the following steps:

[0110] Step 1: Start the PLC control system, load the preset machining program, and enter or confirm the machining parameters through the human-machine interface (HMI). The system runs the self-diagnosis program to check the status of key components. Use the laser alignment module (LDAM) to calibrate the laser beam focus position. Use the proportional integral differential (PID) controller to adjust the laser power, and control the water jet pressure in a closed loop through the proportional valve and pressure sensor. Import the machining path file generated by CAD / CAM, use offline programming to generate the coordinate point cloud, and optimize the path through the PLC interpolation algorithm. Adjust the water jet nozzle angle and laser focus offset to ensure that the two are coaxial.

[0111] Step 1.1: Start the PLC control system, load the preset processing program, and input or confirm the processing parameters through the human-machine interface (HMI).

[0112] Step 1.2: Run the self-diagnosis program to collect the signals of the spindle system, grinding tool, cooling system, motor and transmission system sensors, and calculate the mean μ and variance σ of the signals. 2 , Kurtosis γ 2 , kurtosis β and other basic statistical characteristics. N is the sample size, x i is the i-th data under the same index, μ, σ 2 , γ 2 and β can be expressed as:

[0113]

[0114]

[0115] Use Fast Fourier Transform (FFT) to convert the signal from the time domain to the frequency domain and identify the characteristic frequency components. X(k) is the kth frequency component of the frequency domain signal, x(n) is the nth sample of the time domain signal, N is the total number of samples of the signal, k is the frequency index, and FFT can be expressed as:

[0116]

[0117] Use wavelet transform to perform time-frequency analysis and capture transient features in non-stationary signals. ψ (a,b) is the wavelet transform coefficient, a is the scale parameter, b is the translation parameter, ψ is the wavelet function, and t is time. The mathematical expression of wavelet transform is:

[0118] Through the support vector machine (SVM), the feature vector x and the classification label y are set, and the system working status is diagnosed by constructing the decision boundary.

[0119] Step 1.3: Use the laser alignment module (LDAM) to calibrate the laser beam focus position and use the proportional-integral-differential (PID) controller to achieve precise adjustment of the laser. e(t) is the laser target deviation error, and Kp, Ki, and Kd are control gains. The control output signal u(t) can be expressed as:

[0120]

[0121] As a control signal, u(t) acts on the actuator or regulating element that controls the laser calibration to adjust the system state and achieve accurate calibration of the laser.

[0122] Step 1.4: Use the PID controller to adjust the water jet nozzle angle and laser focus offset to ensure that they are coaxial.

[0123] Step 2: Use a pneumatic or servo-driven clamping device to accurately position the splitter, use an industrial camera and image processing algorithm to confirm the workpiece boundaries and angles, and receive sensor feedback signals through the PLC to determine whether the workpiece is aligned with the processing starting point.

[0124] Step 2.1: Use a closed-loop control system to feedback the real-time position error and adjust the motor speed and position to achieve precise positioning of the riving knife.

[0125] Step 2.2: Use an industrial camera to extract a color image of the workpiece, and use Canny edge detection, morphological processing, feature extraction, and geometric analysis to identify the boundaries and angles of the workpiece. The Sobel operator in Canny edge detection is defined as:

[0126]

[0127] The calculation formula of gradient amplitude G and direction θ is:

[0128]

[0129] Morphological processing operates on binary images using structural elements and repairs edge discontinuities or extracts specific shapes. Using geometric analysis, the exact boundaries and angles of artifacts are calculated by fitting straight lines using the least squares method.

[0130] Step 2.3: Receive the sensor feedback signal through PLC, substitute the signal parameters into the PID controller, determine whether the workpiece is aligned with the processing starting point and make adjustments.

[0131] Step 3: Start the laser and control the relative movement of the laser head and the workpiece according to the path planning. Generate the chamfering processing path through the spatial interpolation algorithm and adjust the position of the XYZ axis servo motor in real time. Through the real-time tracking algorithm, the laser focus is automatically kept on the workpiece surface. Dynamically adjust the water jet pressure to maintain the cutting thermal balance and avoid overheating and cracking of the ceramic material surface. Photoelectric sensors and thermal sensors collect processing surface data in real time, and the PLC compensates based on the deviation data.

[0132] Step 3.1: Determine the position and posture of the laser head relative to the workpiece through forward and inverse kinematics modeling. T represents the spatial position and posture of the tool end, f is the kinematic function, Θ is the joint angle set, and x, y, z are the spatial coordinates of the tool end. Forward and inverse kinematics can be expressed as:

[0133] T=f(θ1, θ2,…,θn) Θ=f-1(x, y, z).

[0134] The circular interpolation algorithm is used to generate the optimal path from the starting point to the end point. c ,y c ) is the center of the circle, r is the radius of the circle, θ(t) is the angle parameter, x(t), y(t) are the positions of the center of the circle at time t. The mathematical formula related to the circular interpolation algorithm can be expressed as:

[0135] x(t)=x c + r·cos(θ(t)),y(t)=y c +r·sin(θ(t)).

[0136] Use gradient descent to solve the optimality of the path to minimize the objective function such as moving time or path length. Construct a loss function L related to path smoothness, speed, and acceleration, and define the loss function L related to moving time T. 0 T f , path length L and energy dissipation The relevant objective function f(x) is as follows:

[0137]

[0138] The path is smoothed using the B-spline interpolation algorithm, and accurate path tracking is performed using the PID controller. P(t) is the anchor point at time t, n is the number of control points, and B i,k (t) is the control point P i The spline basis function of order k, P i is the control point. The B-spline interpolation algorithm can be expressed as:

[0139]

[0140] Step 3.2: Generate the chamfering processing path through the spatial interpolation algorithm and adjust the position of the XYZ axis servo motor in real time.

[0141] Step 3.3: Combine the camera, distance sensor and PID controller to dynamically adjust the position of the laser head.

[0142] Step 3.4: According to the temperature data provided by the temperature sensor, the water jet pressure is dynamically adjusted to maintain the cutting thermal balance and avoid overheating and cracking of the ceramic material surface.

[0143] Step 3.5: Photoelectric sensors and thermal sensors collect processing surface data in real time, and PLC performs compensation based on deviation data.

[0144] Step 4: External chamfering R corner grinding. Use NURBS curve fitting to generate a smooth processing trajectory. The servo system synchronously controls the three-axis linkage, and the laser head tracks the R corner contour according to the path. The laser power is adjusted in real time by the PLC, and the processing accuracy is ensured through sensor feedback and PID closed-loop control algorithm;

[0145] Step 4.1: Generate a smooth machining trajectory using NURBS curve fitting. Determine the number of control points, where n is the number of control points minus 1, P i is the control point, set the weight w of the control point i , N i,p (t) is the ith B-spline basis function with order p. The knot vector U = {u 0 ,u 1 ,...,u m}, where m = n + p + 1. Define the B-spline basis function N i,p The recursive relation of (t) is:

[0146]

[0147] N is the number of control points. A NURBS curve C(t) is defined at parameter t as:

[0148]

[0149] By adjusting the control points and weights, and using NURBS to adjust the control points and other parameters, the curve is made as close to the data points as possible, thus generating a smooth machining trajectory.

[0150] Step 4.2: Design the contour path through the CAD or CAM system, use the arc interpolation algorithm to calculate the instant position of each axis, and form a smooth motion trajectory. Each axis is driven by a servo motor, the feedback system provides position information, and the PID controller adjusts the motion parameters in real time to ensure high-precision tracking. The central controller coordinates the synchronous movement of each axis to achieve accurate path tracking in three-dimensional space.

[0151] Step 4.3: PLC adjusts the laser power in real time, and ensures processing accuracy through sensor feedback and PID closed-loop control algorithm. Position control requires error correction for the XYZ axes at the same time. pj , K ij , K dj (j=x,y,z) is the proportional gain, integral gain and differential gain, e x (t), e y (t), e z (t) is the position signal error of each axis. The formula for controlling the XYZ axis is as follows:

[0152]

[0153] Through precise PID parameter adjustment, PLC can ensure accurate tracking of the laser head on complex surfaces and achieve the required processing accuracy.

[0154] Step 5: Tungsten wire expansion and polishing. The laser head is positioned at the tungsten wire hole position, and the PLC controls the laser to output high-power pulses. The water jet is sprayed synchronously to take away the cutting debris and prevent secondary thermal effects. The PLC switches to low-power pulse mode, and the interaction between the laser beam and the water jet reduces the surface roughness. The PLC executes the dynamic model prediction algorithm to optimize the motion trajectory of the laser head and improve the surface finish.

[0155] Step 5.1: The laser head is positioned at the tungsten hole position, and the PLC controls the laser to output high-power pulses. The water jet is sprayed synchronously to take away the cutting debris and prevent secondary thermal effects.

[0156] Step 5.2: The PLC switches to low-power pulse mode, and the laser beam and water jet interact to reduce surface roughness.

[0157] Step 5.3: Design the objective function J to minimize the deviation of the future output from the reference trajectory and the change in the control input. r(t+k) is the desired reference trajectory, y(t+k) is the actual trajectory, represents the quadratic norm with weight matrices Q and R, which is used to constrain the change of deviation and control force, Δu(t+k)=u(t+k)-u(t+k-1) represents the change of control input, N p 、N e is the control point, and the objective function J can be expressed as:

[0158]

[0159] By continuously adjusting the motion path of the laser head, MPC can solve the above optimization problem to obtain the optimal control input and provide real-time feedback on the optimized trajectory, thereby effectively improving the surface finish.

[0160] Step 6: Internal chamfer grinding. The laser head enters the inner cavity of the workpiece and completes the internal chamfer path tracking through small radius arc interpolation. A force sensor is used to detect the processing pressure, and the PLC adjusts the laser output based on the feedback. The inner wall uses adaptive laser power control (ALPC) technology to avoid micro cracks in ceramic materials.

[0161] Step 6.1: The laser head enters the inner cavity of the workpiece and completes the inner chamfer path tracking through small radius arc interpolation.

[0162] Step 6.2: Use a force sensor to detect the processing pressure, and the PLC adjusts the laser output based on the feedback.

[0163] Step 6.3: Use adaptive laser power control (ALPC) technology to monitor the temperature or molten pool characteristics in the ceramic material processing process in real time and dynamically adjust the laser power; use sensor feedback to obtain the status data of the processing point, and calculate the required laser power adjustment through PID to keep the processing conditions at the optimal state at all times, thereby avoiding the formation of microcracks caused by overheating.

[0164] Step 7: End of processing and cleaning. Turn off the laser, water jet and servo motor. The PLC controls the clamping system to release the workpiece and move the workpiece to the unloading area through the conveyor. The laser head nozzle and water jet pipeline perform an automatic flushing program to prevent impurities from remaining. The waste disposal module removes the cutting debris to the designated container.

[0165] Step 8: Data recording and storage. Processing parameters, quality inspection data and path deviation data are uploaded to the industrial database through PLC. Data is uploaded to the cloud platform for subsequent production optimization and process improvement.

[0166] The performance effect of the present invention can be further illustrated by the following experiments:

[0167] 1) Experimental conditions

[0168] The experiment of the present invention uses a high-precision Siemens S7-1200 PLC, and a laser interferometer has been used to calibrate the motion trajectory of the PLC-controlled mechanical arm to ensure that the repeated positioning accuracy reaches ±1μm. A 1kW UV solid laser with a wavelength of 355nm is used. The water guide system uses high-purity deionized water with a flow rate adjustment accuracy of ±0.1L / min. The raw material uses a density of 3.95g / cm 3 The standard size of the parts is 50mm x 50mm x 10mm high-purity silicon nitride ceramics, coated with top-grade diamond coating on the surface, with high thermal conductivity to reduce heat accumulation. The experimental environment temperature is constantly controlled at 22℃±0.5℃. The ambient humidity is constantly controlled at 50%±2%. The experimental workbench adopts anti-vibration design, and the vibration amplitude is less than 5 microns. Each sample is repeatedly polished 5 times to ensure the reliability of the data.

[0169] 2) Experimental content and results

[0170] Figure 4 The PLC-based high-precision automatic grinding method of water-conducting laser splitting knife proposed in the present invention is demonstrated, and various indicators after grinding the same high-purity silicon nitride ceramics are compared with traditional grinding methods (mechanical grinding, laser grinding, chemical mechanical polishing, ultrasonic assisted grinding), including surface quality, grinding accuracy, grinding efficiency and environmental protection. It can be observed that the method proposed by us has good performance in all aspects, and the performance in the three dimensions of surface quality, accuracy, production efficiency and environmental protection is particularly outstanding. This is mainly because the PLC control system makes the water-conducting laser grinding technology more flexible and adjustable. The operator can adjust the grinding parameters such as laser power, grinding path, cooling intensity, etc. according to the requirements of different workpieces, thereby improving the grinding accuracy and quality; water-conducting laser grinding combined with PLC technology realizes automatic control. PLC can monitor and adjust the grinding process in real time, optimize multiple parameters such as laser power and spray cooling, and ensure continuous operation on the production line without manual intervention. The automation system can also reduce the errors of human operation and greatly improve the efficiency of mass production. At the same time, the water cooling system can effectively reduce exhaust gas and heat pollution. Through the precise control of PLC, it can further reduce resource waste, avoid excessive energy consumption, and improve the green benefits of the overall production line.

[0171] Based on the above experimental results and analysis, the PLC-based high-precision automatic grinding technology of water-guided laser whetters proposed in this invention has excellent performance in terms of surface quality, grinding accuracy, production efficiency and environmental protection, especially in fine processing, continuous production and green manufacturing. Through automated and intelligent control, PLC technology can maximize production efficiency, reduce labor costs, and ensure the stability of product quality.

Claims

1. A high-precision automatic grinding method for a water-guided laser whet cutter based on PLC, characterized in that: The method comprises the following steps: Step 1: Initialization and parameter setting; Step 1-1: Start the PLC control system, load the preset processing program, and enter the processing parameters; Step 1-2: Run the self-diagnosis program; Step 1-3: calibrate the laser beam focal position; Step 1-4: Adjust the water jet nozzle angle and laser focus offset; Step 2: Workpiece positioning; Step 2-1: Precise positioning of the riving knife; Step 2-2: Confirm the workpiece boundary and angle; Step 2-3: Determine whether the workpiece is aligned with the processing starting point; Step 3: Surface chamfering and grinding; Step 3-1: Start the laser and control the relative movement between the laser head and the workpiece; Step 3-2: Generate chamfering processing path and adjust the position of XYZ axis servo motor in real time; Step 3-3: Automatically keep the laser focus on the workpiece surface; Step 3-4: Dynamically adjust the water jet pressure to maintain cutting thermal balance and avoid overheating and cracking of the ceramic material surface; Step 3-5: Collect the processing surface data in real time and make compensation based on the deviation data; Step 4: External chamfer R grinding; Step 4-1: Generate smooth machining trajectory; Step 4-2: The laser head tracks the R corner contour according to the path; Step 4-3: Adjust the laser power in real time to ensure processing accuracy; Step 5: Tungsten wire expansion and polishing; Step 5-1: The laser head is positioned at the tungsten wire hole, the laser outputs high-power pulses, and the water jet is ejected synchronously to take away the cutting debris and prevent secondary thermal effects; Step 5-2: Interaction between laser beam and water jet to reduce surface roughness; Step 5-3: Optimize the laser head motion trajectory to improve surface finish; Step 6: Grinding the inner chamfer; Step 6-1: The laser head enters the inner cavity of the workpiece and completes the inner chamfer path tracking; Step 6-2: Detect processing pressure and adjust laser output; Step 6-3: Control laser power to avoid micro cracks in ceramic materials; Step 7: End of processing and cleaning; Step 7-1: The laser and water jet are turned off, and the servo motor stops; Step 7-2: Move the workpiece to the unloading area; Step 7-3: The laser head nozzle and water jet pipeline perform an automatic flushing procedure to prevent impurities from remaining; Step 7-4: The waste processing module removes the cutting debris into a designated container; Step 8: Data recording and storage; Step 8-1: Processing parameters, quality inspection data and path deviation data are uploaded to the industrial database through PLC; Step 8-2: Upload data to the cloud platform for subsequent production optimization and process improvement.

2. According to the PLC-based high-precision automatic grinding method of a water-guided laser wrecking tool according to claim 1, it is characterized in that: The step 1 includes starting the PLC control system, loading the preset processing program, inputting or confirming the processing parameters through the human-machine interface (HMI), the system running the self-diagnosis program, checking the status of key components, calibrating the laser beam focus position using a laser alignment module (LDAM), adjusting the laser power using a proportional integral differential (PID) controller, controlling the water jet pressure in a closed loop through a proportional valve and a pressure sensor, importing the processing path file generated by CAD / CAM, generating a coordinate point cloud using offline programming, optimizing the path through a PLC interpolation algorithm, adjusting the water jet nozzle angle and the laser focus offset to ensure that the two are coaxial, and the specific steps are: Step 1-1: Start the PLC control system, load the preset processing program, and enter or confirm the processing parameters through the human-machine interface (HMI). Step 1-2: Run the self-diagnosis program to collect the signals of the spindle system, grinding tool, cooling system, motor and transmission system sensors, and calculate the mean μ and variance σ of the signals. 2 , Kurtosis γ 2 , kurtosis β and other basic statistical characteristics, N is the sample size, x i is the i-th data under the same index, μ, σ 2 , γ 2 and β can be expressed as: Use Fast Fourier Transform (FFT) to convert the signal from the time domain to the frequency domain and identify the characteristic frequency components. X(k) is the kth frequency component of the frequency domain signal, x(n) is the nth sample of the time domain signal, N is the total number of samples of the signal, and k is the frequency index. FFT can be expressed as: Use wavelet transform to perform time-frequency analysis to capture transient features in non-stationary signals. ψ (a, b) is the wavelet transform coefficient, a is the scale parameter, b is the translation parameter, ψ is the wavelet function, and the mathematical expression of wavelet transform is: Through the support vector machine (SVM), the feature vector x and the classification label y are set, and the system working status is diagnosed by constructing the decision boundary. Step 1-3: Use the laser alignment module (LDAM) to calibrate the laser beam focus position, and use the proportional-integral-differential (PID) controller to achieve precise adjustment of the laser. e(t) is the laser target deviation error, Kp, Ki, Kd are control gains, and the control output signal u(t) can be expressed as: u(t) acts as a control signal and acts on the actuator or regulating element that controls the laser calibration to adjust the system state and achieve accurate laser calibration. Steps 1-4: Use the PID controller to adjust the water jet nozzle angle and laser focus offset to ensure that they are coaxial.

3. According to the method for high-precision automatic grinding of a water-conducting laser wrecking tool based on PLC in claim 1, the step 2 comprises: The pneumatic or servo-driven clamping device is used to accurately position the splitter, and the industrial camera and image processing algorithm are used to confirm the workpiece boundary and angle. The sensor feedback signal is received through the PLC to determine whether the workpiece is aligned with the processing starting point. The specific steps are as follows: Step 2-1: Use a closed-loop control system to feedback the real-time position error and adjust the motor speed and position to achieve precise positioning of the chopper. Step 2-2: Use an industrial camera to extract a color image of the workpiece, and use Canny edge detection, morphological processing, feature extraction, and geometric analysis to identify the boundaries and angles of the workpiece. The Sobel operator in Canny edge detection is defined as: The calculation formula of gradient amplitude G and direction θ is: Morphological processing operates on binary images using structural elements and repairs edge discontinuities or extracts specific shapes. Using geometric analysis, the exact boundaries and angles of the workpiece are calculated by fitting straight lines using the least squares method; Step 2-3: Receive the sensor feedback signal through PLC, substitute the signal parameters into the PID controller, determine whether the workpiece is aligned with the processing starting point and make adjustments.

4. The method for high-precision automatic grinding of a water-guided laser wrecking tool based on PLC according to claim 1 is characterized in that: The step 3 includes starting the laser, controlling the relative movement of the laser head and the workpiece according to the path planning, generating the chamfering processing path through the spatial interpolation algorithm, adjusting the position of the XYZ axis servo motor in real time, automatically keeping the laser focus on the workpiece surface through the real-time tracking algorithm, dynamically adjusting the water jet pressure, maintaining the cutting thermal balance, avoiding overheating and cracking of the ceramic material surface, the photoelectric sensor and the thermal sensor collect the processing surface data in real time, and the PLC compensates based on the deviation data. The specific steps are as follows: Step 3-1: Determine the position and posture of the laser head relative to the workpiece through forward and inverse kinematics modeling. T represents the spatial position and posture of the tool end, f is the kinematic function, Θ is the joint angle set, x, y, z are the spatial coordinates of the tool end, and forward and inverse kinematics can be expressed as: T=f(θ1,θ2,…,θn) Θ=f-1(x,y,z); The circular interpolation algorithm is used to generate the optimal path from the starting point to the end point, (x c ,y c ) is the center of the circle, r is the radius of the circle, θ(t) is the angle parameter, x(t), y(t) are the positions of the center of the circle at time t, and the mathematical formula related to the circular interpolation algorithm can be expressed as: x(t)=x c +r·cos(θ(t)),y(t)=y c +r·sin(θ(t)); Use gradient descent to solve the optimality of the path to minimize the objective function such as moving time or path length, construct the loss function L related to path smoothness, speed, and acceleration, and define the loss function L related to the moving time T0T f , path length L and energy dissipation The relevant objective function f(x) is as follows: The B-spline interpolation algorithm is used to smooth the path, and the PID controller is used to perform accurate path tracking. P(t) is the anchor point at time t, n is the number of control points, and B i,k (t) is the control point P i The spline basis function of order k, P i is the control point, and the B-spline interpolation algorithm can be expressed as: Step 3-2: Generate the chamfering processing path through the spatial interpolation algorithm and adjust the position of the XYZ axis servo motor in real time; Step 3-3: Combine the camera, distance sensor and PID controller to dynamically adjust the position of the laser head; Step 3-4: According to the temperature data provided by the temperature sensor, the water jet pressure is dynamically adjusted to maintain the cutting thermal balance and avoid overheating and cracking of the ceramic material surface; Step 3-5: Photoelectric sensors and thermal sensors collect processing surface data in real time, and PLC performs compensation based on deviation data.

5. The method for high-precision automatic grinding of a water-guided laser wrecking tool based on PLC according to claim 1 is characterized in that: The step 4 includes external chamfering R corner grinding, using NURBS curve fitting to generate a smooth processing trajectory, the servo system synchronously controls the three-axis linkage, the laser head tracks the R corner contour according to the path, the laser power is adjusted in real time by the PLC, and the processing accuracy is ensured by sensor feedback and PID closed-loop control algorithm. The specific steps are: Step 4-1: Generate a smooth machining trajectory using NURBS curve fitting and determine the number of control points, where n is the number of control points minus 1, P i is the control point, set the weight w of the control point i , N i,p (t) is the i-th B-spline basis function, with order p, and the knot vector U = {u0,u1,...,u m }, where m = n + p + 1, define the B-spline basis function N i,p The recursive relation of (t) is: N is the number of control points. A NURBS curve C(t) is defined at parameter t as: By adjusting the control points and weights, and using NURBS to adjust the control points and other parameters, the curve is made as close to the data points as possible, thus generating a smooth machining trajectory. Step 4-2: Design the contour path through the CAD or CAM system, use the circular interpolation algorithm to calculate the instant position of each axis to form a smooth motion trajectory. Each axis is driven by a servo motor, the feedback system provides position information, and the PID controller adjusts the motion parameters in real time to ensure high-precision tracking. The central controller coordinates the synchronous movement of each axis to achieve accurate path tracking in three-dimensional space. Step 4-3: PLC adjusts the laser power in real time, and ensures processing accuracy through sensor feedback and PID closed-loop control algorithm. Position control requires error correction of the XYZ axes at the same time. pj , K ij , K dj (j=x,y,z) is the proportional gain, integral gain and differential gain, e x (t), e y (t), e z (t) is the position signal error of each axis. The formula for controlling the XYZ axis is as follows: Through precise PID parameter adjustment, PLC can ensure accurate tracking of the laser head on complex surfaces and achieve the required processing accuracy.

6. The method for high-precision automatic grinding of a water-guided laser wrecking tool based on PLC according to claim 1 is characterized in that: The step 5 includes tungsten wire expansion and polishing, the laser head is positioned at the tungsten wire hole position, the PLC controls the laser to output high-power pulses, the water jet is sprayed synchronously to take away the cutting debris and prevent secondary thermal effects, the PLC switches to low-power pulse mode, the laser beam and the water jet interact to reduce surface roughness, the PLC executes the dynamic model prediction algorithm, optimizes the laser head motion trajectory, and improves the surface finish. The specific steps are: Step 5-1: The laser head is positioned at the tungsten wire hole. The PLC controls the laser to output high-power pulses. The water jet is sprayed synchronously to take away the cutting debris and prevent secondary thermal effects. Step 5-2: The PLC switches to low-power pulse mode, and the interaction between the laser beam and the water jet reduces the surface roughness. Step 5-3: Design the objective function J to minimize the deviation of the future output from the reference trajectory and the change in the control input, where r(t+k) is the desired reference trajectory and y(t+k) is the actual trajectory. and represents the quadratic norm with weight matrices Q and R, which is used to constrain the change of deviation and control force, Δu(t+k)=u(t+k)-u(t+k-1) represents the change of control input, N p 、N e is the control point, and the objective function J can be expressed as: By continuously adjusting the motion path of the laser head, MPC can solve the above optimization problem to obtain the optimal control input and provide real-time feedback on the optimized trajectory, thereby effectively improving the surface finish.

7. The method for high-precision automatic grinding of a water-guided laser wrecking tool based on PLC according to claim 1 is characterized in that: The step 6 includes: inner chamfer grinding, the laser head enters the inner cavity of the workpiece, completes the inner chamfer path tracking through small radius arc interpolation, uses a force sensor to detect the processing pressure, and the PLC adjusts the laser output according to the feedback. The inner wall adopts the adaptive laser power control (ALPC) technology to avoid micro cracks in the ceramic material. The specific steps are: Step 6-1: The laser head enters the inner cavity of the workpiece and completes the inner chamfer path tracking through small radius arc interpolation. Step 6-2: Use a force sensor to detect the processing pressure, and the PLC adjusts the laser output based on the feedback. Step 6-3: Use adaptive laser power control (ALPC) technology to monitor the temperature or molten pool characteristics in the ceramic material processing process in real time and dynamically adjust the laser power; use sensor feedback to obtain the status data of the processing point, and calculate the required laser power adjustment through PID to keep the processing conditions at the optimal state at all times, thereby avoiding the formation of microcracks caused by overheating.

8. The method for high-precision automatic grinding of a water-guided laser wrecking tool based on PLC according to claim 1 is characterized in that: The step 7 includes the end of processing and cleaning, turning off the laser, water jet and servo motor, PLC controlling the clamping system to release the workpiece, and moving the workpiece to the unloading area through the conveyor, the laser head nozzle and the water jet pipeline perform an automatic flushing procedure to prevent impurities from remaining, and the waste processing module removes the cutting debris to a designated container.

9. The method for high-precision automatic grinding of a water-guided laser wrecking tool based on PLC according to claim 1 is characterized in that: The step 8 includes data recording and storage. Processing parameters, quality inspection data and path deviation data are uploaded to the industrial database through PLC, and the data is uploaded to the cloud platform for subsequent production optimization and process improvement.

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