Founded in 1951 monthly
ISSN 1005-2402
CN 11-3398/TH
Responsible Department：China Association for Science andTechnology
Sponsors：China Mechanical Engineering Society
Beijing Machine Tool Research Institute Co., Ltd.
Chief Editor： Huang Zhenghua
Deputy Managing Editor: TAN Hongying
Director ofMachine Tool Magazine Agency: HUANG Zuguang
Post Distribution: 2-636
External Code: M397
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Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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2023, (6): 5-10.
doi: 10.19287/j.mtmt.1005-2402.2023.06.001
Abstract:
In order to explore the factors affecting the forming quality of powder-bonded 3D printing process, this paper uses the sand bed laying stage of sand mold printing to analyze the law between the roll radius and the sand laying quality based on solid mechanics, and obtains the change of the sand laying quality with the roller radius trend. Through the derived formula, the value range of the roller radius under the specified sand bed scale is given. The discrete element simulation software EDEM is used to establish the numerical simulation model of the sand laying stage, and the quality measurement of the sand bed after sand laying with rollers of different sizes is completed on the constructed sand bed. The results are in good agreement with the calculation results of the proposed theoretical formula, and the validity of the theoretical formula is verified by simulation.
In order to explore the factors affecting the forming quality of powder-bonded 3D printing process, this paper uses the sand bed laying stage of sand mold printing to analyze the law between the roll radius and the sand laying quality based on solid mechanics, and obtains the change of the sand laying quality with the roller radius trend. Through the derived formula, the value range of the roller radius under the specified sand bed scale is given. The discrete element simulation software EDEM is used to establish the numerical simulation model of the sand laying stage, and the quality measurement of the sand bed after sand laying with rollers of different sizes is completed on the constructed sand bed. The results are in good agreement with the calculation results of the proposed theoretical formula, and the validity of the theoretical formula is verified by simulation.
2023, (6): 11-15.
doi: 10.19287/j.mtmt.1005-2402.2023.06.002
Abstract:
The extrusion and accumulation of the slurry under different layer height were analyzed aiming at extrusion ceramic 3D printing for the preparing of casting shell. After 3D printing test, appropriate process parameter values were obtained by comparative studying the effect of extrusion head inner diameter, layer height and printing speed on printing process and printing quality, and the maximum space tilt angle and minimum angle in the printing plane of the printed part were obtained by comparative studying the quality of the printed part under different space tilt angle and the angle in the printing plane. The results show that appropriate process parameters are extrusion head inner diameter of 0.6 mm~0.8 mm, layer height of about 0.6 mm, printing speed of 20 mm/s. The maximum exterior and interior tilt angle of the printed part are 40°. The minimum angle in the printing plane of the printed part is 30°.
The extrusion and accumulation of the slurry under different layer height were analyzed aiming at extrusion ceramic 3D printing for the preparing of casting shell. After 3D printing test, appropriate process parameter values were obtained by comparative studying the effect of extrusion head inner diameter, layer height and printing speed on printing process and printing quality, and the maximum space tilt angle and minimum angle in the printing plane of the printed part were obtained by comparative studying the quality of the printed part under different space tilt angle and the angle in the printing plane. The results show that appropriate process parameters are extrusion head inner diameter of 0.6 mm~0.8 mm, layer height of about 0.6 mm, printing speed of 20 mm/s. The maximum exterior and interior tilt angle of the printed part are 40°. The minimum angle in the printing plane of the printed part is 30°.
2023, (6): 16-20.
doi: 10.19287/j.mtmt.1005-2402.2023.06.003
Abstract:
The problem of dimensional deviation caused by material shrinkage in the hot forming process of fused deposition manufacturing (FDM) should be solved. Thus, contour compensation method that based on the initial design model is carried out to reduce dimension deviation to improve dimension accuracy. A series of ellipsoidal cylinders, regular prisms are designed by orthogonal test. Two contour compensation methods are proposed, and the two methods are used to compensate the contour of the initial design model of the test pieces. The results show that there are differences in the forming dimensional accuracy of the elliptical cylinder, the triangular prism and the square prism for the examples in this article. Both of the two methods can improve dimensional accuracy. Dimensional accuracy of regular elliptical cylinder, regular triangular prism and square prism is promoted in different degrees by the same compensation method. The second has better compensation effect than the one.
The problem of dimensional deviation caused by material shrinkage in the hot forming process of fused deposition manufacturing (FDM) should be solved. Thus, contour compensation method that based on the initial design model is carried out to reduce dimension deviation to improve dimension accuracy. A series of ellipsoidal cylinders, regular prisms are designed by orthogonal test. Two contour compensation methods are proposed, and the two methods are used to compensate the contour of the initial design model of the test pieces. The results show that there are differences in the forming dimensional accuracy of the elliptical cylinder, the triangular prism and the square prism for the examples in this article. Both of the two methods can improve dimensional accuracy. Dimensional accuracy of regular elliptical cylinder, regular triangular prism and square prism is promoted in different degrees by the same compensation method. The second has better compensation effect than the one.
2023, (6): 21-25.
doi: 10.19287/j.mtmt.1005-2402.2023.06.004
Abstract:
Based on the surface model of the work piece generated by Rhinoceros,the Grasshopper software platform is used to extract the welding curve and weld path planning from the workpiece model, and output the path planning result data, which is input to the control system to drive the mechanical structure; the mechanical structure uses two degrees of freedom to control the torch position to ensure that the torch always welds from directly above the welding point. The two-degree-of-freedom rotating mechanism controls the position of the workpiece so that the gun is in the most favorable position to avoid workpiece interference, and the two sets of mechanism movements cooperate to achieve automatic continuous welding of spatial curves, which improves the welding quality and simplifies the path solving method.
Based on the surface model of the work piece generated by Rhinoceros,the Grasshopper software platform is used to extract the welding curve and weld path planning from the workpiece model, and output the path planning result data, which is input to the control system to drive the mechanical structure; the mechanical structure uses two degrees of freedom to control the torch position to ensure that the torch always welds from directly above the welding point. The two-degree-of-freedom rotating mechanism controls the position of the workpiece so that the gun is in the most favorable position to avoid workpiece interference, and the two sets of mechanism movements cooperate to achieve automatic continuous welding of spatial curves, which improves the welding quality and simplifies the path solving method.
2023, (6): 26-32.
doi: 10.19287/j.mtmt.1005-2402.2023.06.005
Abstract:
For the trajectory planning problem in the collaboration process of dual industrial robots, modeling the IRB200 robot and solving the forward and reverse kinematics of the robot. The coupled motion under tight constraint and superposition motion under loose constraint algorithms are proposed in combination with the solved forward and inverse kinematics. The tight constraint establishes the constant constraint relationship between the robot end-effectors to realize the coupling motion between the robot end-effectors; the loose constraint establishes the time-varying constraint relationship between the robot end-effectors to realize the superposition motion between the robot end-effectors. Finally, the algorithm is verified by the simulation experiments of cooperative handling and cooperative drawing of “copper coins” in MATLAB. The adaptive planning of the trajectory can avoid the separate trajectory planning of the dual industrial robots.
For the trajectory planning problem in the collaboration process of dual industrial robots, modeling the IRB200 robot and solving the forward and reverse kinematics of the robot. The coupled motion under tight constraint and superposition motion under loose constraint algorithms are proposed in combination with the solved forward and inverse kinematics. The tight constraint establishes the constant constraint relationship between the robot end-effectors to realize the coupling motion between the robot end-effectors; the loose constraint establishes the time-varying constraint relationship between the robot end-effectors to realize the superposition motion between the robot end-effectors. Finally, the algorithm is verified by the simulation experiments of cooperative handling and cooperative drawing of “copper coins” in MATLAB. The adaptive planning of the trajectory can avoid the separate trajectory planning of the dual industrial robots.
2023, (6): 33-38.
doi: 10.19287/j.mtmt.1005-2402.2023.06.006
Abstract:
Aiming at the problem of inaccurate workpiece position in the assembly process of infrared sensor, an automatic assembly system of infrared sensor based on visual recognition and positioning technology is designed. The mechanical structure of the system is composed of industrial robot, feeding unit, conveying unit, visual detection unit, quick-change tool unit, the seventh axis of industrial robot, etc. The position and angle of the sensor end cover are recognized by the vision system, and the result is converted to the robot world to make the workpiece can be grasped accurately. A PLC control system based on Ethernet communication is built to complete the discharging, conveying, grabbing and automatic assembly control of infrared sensor parts. The experiment shows that the designed system has high degree of automation, reliable operation and high promotion application value.
Aiming at the problem of inaccurate workpiece position in the assembly process of infrared sensor, an automatic assembly system of infrared sensor based on visual recognition and positioning technology is designed. The mechanical structure of the system is composed of industrial robot, feeding unit, conveying unit, visual detection unit, quick-change tool unit, the seventh axis of industrial robot, etc. The position and angle of the sensor end cover are recognized by the vision system, and the result is converted to the robot world to make the workpiece can be grasped accurately. A PLC control system based on Ethernet communication is built to complete the discharging, conveying, grabbing and automatic assembly control of infrared sensor parts. The experiment shows that the designed system has high degree of automation, reliable operation and high promotion application value.
2023, (6): 39-43.
doi: 10.19287/j.mtmt.1005-2402.2023.06.007
Abstract:
In order to reveal the distribution and technological rule of temperature field during laser cutting of 6061 aluminum alloy sheet by scanning speed, the temperature field of 2 mm thick aluminum alloy sheet under different laser cutting speed was simulated by finite element software, and the simulation results were verified by experiments. The simulation results show that when the laser cutting speed is 80 mm/s, the heat affected zone of the workpiece is wide and the melting depth is large, and the materials in a wide range of the slit have reached the melting point temperature. With the increase of the cutting speed, the width of the heat affected zone, the melting amount and the melting depth of the material in the slit gradually decrease. When the cutting speed is 120 mm/s, the melting depth of the workpiece just reaches the thickness of the material. The experimental results show that when the cutting speed is too low, the material melting amount at the slit is too much, and thick hanging slag is formed at the bottom. With the increase of the cutting speed, the quality of the slit is effectively improved, but if the cutting speed is too large, the material melting amount at the slit is reduced, and the roughness is increased. The cutting speed is 120 mm/s, and the quality of the slit is the best. The experimental results are in good agreement with the simulation results, which proves the accuracy of simulation results.
In order to reveal the distribution and technological rule of temperature field during laser cutting of 6061 aluminum alloy sheet by scanning speed, the temperature field of 2 mm thick aluminum alloy sheet under different laser cutting speed was simulated by finite element software, and the simulation results were verified by experiments. The simulation results show that when the laser cutting speed is 80 mm/s, the heat affected zone of the workpiece is wide and the melting depth is large, and the materials in a wide range of the slit have reached the melting point temperature. With the increase of the cutting speed, the width of the heat affected zone, the melting amount and the melting depth of the material in the slit gradually decrease. When the cutting speed is 120 mm/s, the melting depth of the workpiece just reaches the thickness of the material. The experimental results show that when the cutting speed is too low, the material melting amount at the slit is too much, and thick hanging slag is formed at the bottom. With the increase of the cutting speed, the quality of the slit is effectively improved, but if the cutting speed is too large, the material melting amount at the slit is reduced, and the roughness is increased. The cutting speed is 120 mm/s, and the quality of the slit is the best. The experimental results are in good agreement with the simulation results, which proves the accuracy of simulation results.
2023, (6): 44-48.
doi: 10.19287/j.mtmt.1005-2402.2023.06.008
Abstract:
High-feed milling is a milling method that adopts small depth of cut and large feed, and has high processing efficiency and processing quality in deep cavity processing. A simulation model of high-feed milling 34CrNi3Mo high strength steel was established to study the effect of cutting parameters on cutting temperature. The simulation research plan is designed by orthogonal test method, the cutting temperature obtained by simulation is studied by means of range analysis and variance analysis, and the empirical formula of cutting temperature is obtained according to multiple regression analysis method. The results show that the cutting efficiency of machining high-strength steel is improved by high-feed milling with increasing the cutting depth, which is conducive to avoiding a large increase in cutting temperature.
High-feed milling is a milling method that adopts small depth of cut and large feed, and has high processing efficiency and processing quality in deep cavity processing. A simulation model of high-feed milling 34CrNi3Mo high strength steel was established to study the effect of cutting parameters on cutting temperature. The simulation research plan is designed by orthogonal test method, the cutting temperature obtained by simulation is studied by means of range analysis and variance analysis, and the empirical formula of cutting temperature is obtained according to multiple regression analysis method. The results show that the cutting efficiency of machining high-strength steel is improved by high-feed milling with increasing the cutting depth, which is conducive to avoiding a large increase in cutting temperature.
2023, (6): 49-54.
doi: 10.19287/j.mtmt.1005-2402.2023.06.009
Abstract:
The vibration suppression effect in the machining of thin-wall parts is often analyzed qualitatively and the vibration severity is difficult to be determined quantitatively. In order to quantitatively analyze the suppression effect of machining vibration and evaluate the severity of machining vibration, this paper carried out the research on the machining vibration evaluation method based on the measurement test of machining vibration signal. Based on the analysis of the mechanism of machining vibration signal acquisition, the design of machining vibration test was carried out. The acceleration signal and the sound signal in machining vibration and the surface roughness after machining were collected. The empirical models were established by fitting method, which reflected the mapping relationship of three kinds of measurement signals. According to the workpiece surface quality and machining accuracy, the quantitative evaluation methods of free vibration, mild vibration and severe vibration are presented. The evaluation method provided theoretical support for the measurement and judgment of machining vibration and the evaluation of machining vibration suppression effect.
The vibration suppression effect in the machining of thin-wall parts is often analyzed qualitatively and the vibration severity is difficult to be determined quantitatively. In order to quantitatively analyze the suppression effect of machining vibration and evaluate the severity of machining vibration, this paper carried out the research on the machining vibration evaluation method based on the measurement test of machining vibration signal. Based on the analysis of the mechanism of machining vibration signal acquisition, the design of machining vibration test was carried out. The acceleration signal and the sound signal in machining vibration and the surface roughness after machining were collected. The empirical models were established by fitting method, which reflected the mapping relationship of three kinds of measurement signals. According to the workpiece surface quality and machining accuracy, the quantitative evaluation methods of free vibration, mild vibration and severe vibration are presented. The evaluation method provided theoretical support for the measurement and judgment of machining vibration and the evaluation of machining vibration suppression effect.
2023, (6): 55-60.
doi: 10.19287/j.mtmt.1005-2402.2023.06.010
Abstract:
In the process of tool wear, the amount of sample data collected in the normal wear stage is usually more than that in the initial wear stage and the sharp wear stage, which leads to the imbalance of the tool wear state data set, thus reducing the accuracy of the deep learning network model in predicting the tool wear state. To solve this problem, this paper proposes a data augmentation method based on cGAN for tool wear state monitoring. The category information as condition in cGAN is helpful for the generator to better capture the data distribution characteristics of tool wear samples, so as to generate samples similar to the real tool wear sample distribution. Specifically, the vibration signals in the milling process are collected. The vibration signals are converted into spectral data and input into the cGAN. The cGAN is trained by adversarial training between the generator and discriminator to learn data distribution characteristics and generate tool wear state sample data. The enhanced data set is input into the deep learning network model for classification to test the availability of the generated sample data. Experimental results show that training the deep learning network model with the enhanced tool wear states dataset can effectively improve the accuracy of the model in monitoring tool wear states, and the prediction accuracy reaches 98.1%.
In the process of tool wear, the amount of sample data collected in the normal wear stage is usually more than that in the initial wear stage and the sharp wear stage, which leads to the imbalance of the tool wear state data set, thus reducing the accuracy of the deep learning network model in predicting the tool wear state. To solve this problem, this paper proposes a data augmentation method based on cGAN for tool wear state monitoring. The category information as condition in cGAN is helpful for the generator to better capture the data distribution characteristics of tool wear samples, so as to generate samples similar to the real tool wear sample distribution. Specifically, the vibration signals in the milling process are collected. The vibration signals are converted into spectral data and input into the cGAN. The cGAN is trained by adversarial training between the generator and discriminator to learn data distribution characteristics and generate tool wear state sample data. The enhanced data set is input into the deep learning network model for classification to test the availability of the generated sample data. Experimental results show that training the deep learning network model with the enhanced tool wear states dataset can effectively improve the accuracy of the model in monitoring tool wear states, and the prediction accuracy reaches 98.1%.
2023, (6): 61-67.
doi: 10.19287/j.mtmt.1005-2402.2023.06.011
Abstract:
Surface defect detection is a key part of product quality inspection, and with the rapid development of deep learning technology in recent years, the surface defect detection technology of metal materials has been greatly improved. This paper compares and analyzes the surface defect detection methods of metal materials based on deep learning in recent years, and discusses the status of research and application effects in recent years from three aspects: supervised methods, unsupervised methods, and weakly supervised methods. Finally, the key problems and solutions in the detection of surface defects in metal materials are systematically summarized. The further development of surface defect detection is considered and foreseen in the light of industrial needs.
Surface defect detection is a key part of product quality inspection, and with the rapid development of deep learning technology in recent years, the surface defect detection technology of metal materials has been greatly improved. This paper compares and analyzes the surface defect detection methods of metal materials based on deep learning in recent years, and discusses the status of research and application effects in recent years from three aspects: supervised methods, unsupervised methods, and weakly supervised methods. Finally, the key problems and solutions in the detection of surface defects in metal materials are systematically summarized. The further development of surface defect detection is considered and foreseen in the light of industrial needs.
2023, (6): 68-72.
doi: 10.19287/j.mtmt.1005-2402.2023.06.012
Abstract:
Brief analysis of the domestic and foreign development present situation and the development characteristics of machine tool industry, machine tool industry are summarized in detail the development situation and problems faced by the surrounding the important strategy of China's economic and social development and national security needs, put forward the focus of the development of machine tool industry, According to the present situation of domestic machine tool industry, systematic development measures and suggestions are put forward.
Brief analysis of the domestic and foreign development present situation and the development characteristics of machine tool industry, machine tool industry are summarized in detail the development situation and problems faced by the surrounding the important strategy of China's economic and social development and national security needs, put forward the focus of the development of machine tool industry, According to the present situation of domestic machine tool industry, systematic development measures and suggestions are put forward.
2023, (6): 73-80.
doi: 10.19287/j.mtmt.1005-2402.2023.06.013
Abstract:
As a key project of aero-engine, precision gear, 5G intelligence and other countries, high speed and ultra-high speed forming grinding technology, superhard material electroplated grinding wheel has become one of the indispensable tools.By the United States, Japan and other countries technology blockade, current in our country electroplating wheel start late, the technology of electroplating wheel is backward.The main reason is lack of professional precision shaping equipment, low manufacturing accuracy, which seriously restrict it’s industrial application.It is great guiding significance and strategic significance for promoting the industrialization of high-speed and ultra-high-speed forming grinding technology, improving the manufacturing accuracy of key parts of complex surface in aerospace, military and other industries, and ensuring the national security to overcome the precision shaping technology of complex surface of electroplating wheel and break through the technological blockade.In this paper, the dressing technology of superhard material products at home and abroad was reviewed, the contour characteristics and dressing mechanism of superhard material electroplated grinding wheels were analyzed, and the technical barriers existing in the precision shaping of complex profile of electroplated grinding wheels were revealed. By analyzing the relevant dressing equipment in the current industry, it is deduced that "hard dressing" is the reliable technological means to ensure the contour of grinding wheel at present. It is pointed out that the future dressing equipment should be customized, and focus on the development of special equipment from the precision tool setting technology, dressing interference CNC intervention technology, tool grinding wheel loss avoidance/quantitative compensation and other aspects. At the same time, it is pointed out that industrial laser ablation is one of the key research directions of superhard material dressing in the future.
As a key project of aero-engine, precision gear, 5G intelligence and other countries, high speed and ultra-high speed forming grinding technology, superhard material electroplated grinding wheel has become one of the indispensable tools.By the United States, Japan and other countries technology blockade, current in our country electroplating wheel start late, the technology of electroplating wheel is backward.The main reason is lack of professional precision shaping equipment, low manufacturing accuracy, which seriously restrict it’s industrial application.It is great guiding significance and strategic significance for promoting the industrialization of high-speed and ultra-high-speed forming grinding technology, improving the manufacturing accuracy of key parts of complex surface in aerospace, military and other industries, and ensuring the national security to overcome the precision shaping technology of complex surface of electroplating wheel and break through the technological blockade.In this paper, the dressing technology of superhard material products at home and abroad was reviewed, the contour characteristics and dressing mechanism of superhard material electroplated grinding wheels were analyzed, and the technical barriers existing in the precision shaping of complex profile of electroplated grinding wheels were revealed. By analyzing the relevant dressing equipment in the current industry, it is deduced that "hard dressing" is the reliable technological means to ensure the contour of grinding wheel at present. It is pointed out that the future dressing equipment should be customized, and focus on the development of special equipment from the precision tool setting technology, dressing interference CNC intervention technology, tool grinding wheel loss avoidance/quantitative compensation and other aspects. At the same time, it is pointed out that industrial laser ablation is one of the key research directions of superhard material dressing in the future.
2023, (6): 81-87.
doi: 10.19287/j.mtmt.1005-2402.2023.06.014
Abstract:
In order to find the weak links in the precision CNC grinder, the modal analysis and harmonious response analysis were used to identify the vertical plate as the key component to be optimized. Firstly, the topological optimization method is used to optimize the material distribution of vertical plate. Then, the maximum deformation, mass and first-order natural frequency of the vertical plate are taken as the optimization objectives, and the response surface method is used to conduct multi-objective optimization of the vertical plate. The optimal Pareto solution is calculated based on the multi-objective genetic algorithm. Finally, the maximum deformation of the vertical plate is reduced by 3.83%, the mass is reduced by 25.35%, and the first-order natural frequency is increased by 22.33%. At the same time, the amplitude of the grinder in all directions is also reduced, and the dynamic performance of the machine is improved.
In order to find the weak links in the precision CNC grinder, the modal analysis and harmonious response analysis were used to identify the vertical plate as the key component to be optimized. Firstly, the topological optimization method is used to optimize the material distribution of vertical plate. Then, the maximum deformation, mass and first-order natural frequency of the vertical plate are taken as the optimization objectives, and the response surface method is used to conduct multi-objective optimization of the vertical plate. The optimal Pareto solution is calculated based on the multi-objective genetic algorithm. Finally, the maximum deformation of the vertical plate is reduced by 3.83%, the mass is reduced by 25.35%, and the first-order natural frequency is increased by 22.33%. At the same time, the amplitude of the grinder in all directions is also reduced, and the dynamic performance of the machine is improved.
2023, (6): 88-93.
doi: 10.19287/j.mtmt.1005-2402.2023.06.015
Abstract:
In response to the needs of intelligent production line CNC machining center, a electrospindle support bearing was designed, the design bearing is a four-cavity hydrostatic plain bearing, and the core design parameters include inner diameter, oil sealing surface width, oil return groove width, throttle ratio and radius clearance. A calculation model of the support stiffness of hydrostatic bearings was established, and the stiffness value of the design bearing at a load of 100 ~ 700 N was calculated to be 6.0×107 ~ 10.2×107 N/m. The effects of oil sealing surface width, oil return groove width, throttle ratio and radius clearance on stiffness were analyzed, and the bearing design parameters were optimized, and the stiffness value of the optimized bearing was 11.4 ~ 29.8×107 N/m. The static stiffness test of the bearing was carried out, and the horizontal stiffness was 3.1×107 ~ 25×107 N/m and the vertical stiffness was 2.5×107 ~ 23×107 N/m when the load was 100~700 N. The results show that the width of the oil sealing surface and the clearance of the radius have a great influence on the stiffness of hydrostatic bearings and are important design parameters. The stiffness test test value is smaller than the theoretical calculation value, which may be caused by manufacturing and assembly errors caused by the performance of bearing throttle, oil cavity and other structures being more sensitive to dimensional errors.
In response to the needs of intelligent production line CNC machining center, a electrospindle support bearing was designed, the design bearing is a four-cavity hydrostatic plain bearing, and the core design parameters include inner diameter, oil sealing surface width, oil return groove width, throttle ratio and radius clearance. A calculation model of the support stiffness of hydrostatic bearings was established, and the stiffness value of the design bearing at a load of 100 ~ 700 N was calculated to be 6.0×107 ~ 10.2×107 N/m. The effects of oil sealing surface width, oil return groove width, throttle ratio and radius clearance on stiffness were analyzed, and the bearing design parameters were optimized, and the stiffness value of the optimized bearing was 11.4 ~ 29.8×107 N/m. The static stiffness test of the bearing was carried out, and the horizontal stiffness was 3.1×107 ~ 25×107 N/m and the vertical stiffness was 2.5×107 ~ 23×107 N/m when the load was 100~700 N. The results show that the width of the oil sealing surface and the clearance of the radius have a great influence on the stiffness of hydrostatic bearings and are important design parameters. The stiffness test test value is smaller than the theoretical calculation value, which may be caused by manufacturing and assembly errors caused by the performance of bearing throttle, oil cavity and other structures being more sensitive to dimensional errors.
2023, (6): 94-99.
doi: 10.19287/j.mtmt.1005-2402.2023.06.016
Abstract:
To solve the numerical control system when handling consecutive micro line segment, frequent start-stop, adding velocity mutation to interpolation problem, through the establishment of circular arc transition switching model, according to the constraint conditions that the turning point in planning out the optimal convergence speed, the transition arc based on the new flexible deceleration control algorithm to track speed forward planning. Through experimental verification, the trajectory error output of the lookahead interpolation algorithm does not exceed the maximum value given by the system, and the velocity and acceleration curves are continuous and smooth, which can not only meet the machining requirements but also maximize the machining efficiency. Achieved the original design of the experiment.
To solve the numerical control system when handling consecutive micro line segment, frequent start-stop, adding velocity mutation to interpolation problem, through the establishment of circular arc transition switching model, according to the constraint conditions that the turning point in planning out the optimal convergence speed, the transition arc based on the new flexible deceleration control algorithm to track speed forward planning. Through experimental verification, the trajectory error output of the lookahead interpolation algorithm does not exceed the maximum value given by the system, and the velocity and acceleration curves are continuous and smooth, which can not only meet the machining requirements but also maximize the machining efficiency. Achieved the original design of the experiment.
2023, (6): 100-104.
doi: 10.19287/j.mtmt.1005-2402.2023.06.017
Abstract:
The 6-DOF parallel platform is a typical closed chain spatial mechanism, in order to better plan the attitude trajectory of the parallel platform and reduce the vibration amplitude. The unit quaternion is expressed as a three-dimensional vector with simple interpolation through logarithmic transformation, and then the attitude interpolation of the parallel platform is carried out by the quintic polynomial algorithm. Finally, the interpolation points obtained by the attitude interpolation are mapped to the quaternion space to verify the rationality of quaternion multi attitude interpolation, and the 6-ucu parallel platform is built for experimental verification. Conclusion: the unit quaternion is simple to interpolate after logarithmic transformation, and the quintic polynomial algorithm can ensure that there is no sudden change in speed and acceleration, and the smoothness of the fitting curve is high, which ensures the stability of the motion of the parallel platform and prolongs the service life of the parallel platform.
The 6-DOF parallel platform is a typical closed chain spatial mechanism, in order to better plan the attitude trajectory of the parallel platform and reduce the vibration amplitude. The unit quaternion is expressed as a three-dimensional vector with simple interpolation through logarithmic transformation, and then the attitude interpolation of the parallel platform is carried out by the quintic polynomial algorithm. Finally, the interpolation points obtained by the attitude interpolation are mapped to the quaternion space to verify the rationality of quaternion multi attitude interpolation, and the 6-ucu parallel platform is built for experimental verification. Conclusion: the unit quaternion is simple to interpolate after logarithmic transformation, and the quintic polynomial algorithm can ensure that there is no sudden change in speed and acceleration, and the smoothness of the fitting curve is high, which ensures the stability of the motion of the parallel platform and prolongs the service life of the parallel platform.
2023, (6): 105-111.
doi: 10.19287/j.mtmt.1005-2402.2023.06.018
Abstract:
This paper targets the Siemens 840D sl SINUMERIK Operate as the system application framework, and based on the Trace Service data acquisition function, a five-axis linkage accuracy evaluation module for CNC machine tools is developed, which targets the trajectory of S part as the object. Based on data requirements of the trajectory of the S part during operation, this paper analyzes the core principle of the Trace Service data acquisition mechanism, sorts the data acquisition process and designs the sub-module of the coordinate axis data acquisition through the data requirements of the trajectory of the S part during operation, analyzes and extracts the results of the data acquisition to convert the axis coordinates to tool tip points, and completes the display of graph and index of the contour error with the graphical-digital method, so as to achieve the evaluation of the five-axis linkage accuracy of the CNC machine tool. This module uses the excellent linkage accuracy evaluation performance of S part, integrates efficient data acquisition and contour evaluation display, avoids the fussy process of traditional acquisition and evaluation, and effectively improves the economy and efficiency of the evaluation.
This paper targets the Siemens 840D sl SINUMERIK Operate as the system application framework, and based on the Trace Service data acquisition function, a five-axis linkage accuracy evaluation module for CNC machine tools is developed, which targets the trajectory of S part as the object. Based on data requirements of the trajectory of the S part during operation, this paper analyzes the core principle of the Trace Service data acquisition mechanism, sorts the data acquisition process and designs the sub-module of the coordinate axis data acquisition through the data requirements of the trajectory of the S part during operation, analyzes and extracts the results of the data acquisition to convert the axis coordinates to tool tip points, and completes the display of graph and index of the contour error with the graphical-digital method, so as to achieve the evaluation of the five-axis linkage accuracy of the CNC machine tool. This module uses the excellent linkage accuracy evaluation performance of S part, integrates efficient data acquisition and contour evaluation display, avoids the fussy process of traditional acquisition and evaluation, and effectively improves the economy and efficiency of the evaluation.
2023, (6): 112-118.
doi: 10.19287/j.mtmt.1005-2402.2023.06.019
Abstract:
After long-term use and research on CA6136 horizontal lathe, it is found that the positioning accuracy and impact resistance of the front tool rest are poor, and it is easy to get stuck in case of tool collision or impact. If you forcibly move the tool rest pull rod to change the tool, the pull rod will break and damage the machine tool parts, making subsequent maintenance difficult. In order to prolong the service life of the tool rest, it is necessary to study and improve its positioning mode. After analysis, three improvement schemes are proposed, and the optimal scheme is selected after structural design, force analysis and comparative study. The improvement is completed through machining, assembly and debugging, and the ideal effect can be achieved through long-term testing. The research results are worth reference and use for machine tool manufacturers.
After long-term use and research on CA6136 horizontal lathe, it is found that the positioning accuracy and impact resistance of the front tool rest are poor, and it is easy to get stuck in case of tool collision or impact. If you forcibly move the tool rest pull rod to change the tool, the pull rod will break and damage the machine tool parts, making subsequent maintenance difficult. In order to prolong the service life of the tool rest, it is necessary to study and improve its positioning mode. After analysis, three improvement schemes are proposed, and the optimal scheme is selected after structural design, force analysis and comparative study. The improvement is completed through machining, assembly and debugging, and the ideal effect can be achieved through long-term testing. The research results are worth reference and use for machine tool manufacturers.
Research on parameter optimization of tooth-shaped support of three-degree-of-freedom spherical gear
2023, (6): 119-126.
doi: 10.19287/j.mtmt.1005-2402.2023.06.020
Abstract:
During the SLM forming process, the tooth profile support structure in contact with the new spherical gear tooth surface affects the tooth surface forming accuracy. In this paper, the Simufact simulation software is used to simulate the SLM forming process of spherical gears. Using BBD's response surface analysis method, the average deformation of the tooth surface is used as the evaluation index. Through the establishment of a parameter analysis and optimization model, the width of the tip of the teeth, the spacing of the teeth and the hollow are studied. The influence of the three tooth profile parameters on the average deformation of the tooth flank determines the optimum level for each element. As a result, the significant impact of each factor on the mean strain is addendum width>dendum root width>tooth spacing. The optimal combination of tooth shape structure parameters is determined as tooth top width 1.0 mm, tooth spacing 0.71 mm, tooth root width 1.0 mm, and the optimization results meet the requirements.
During the SLM forming process, the tooth profile support structure in contact with the new spherical gear tooth surface affects the tooth surface forming accuracy. In this paper, the Simufact simulation software is used to simulate the SLM forming process of spherical gears. Using BBD's response surface analysis method, the average deformation of the tooth surface is used as the evaluation index. Through the establishment of a parameter analysis and optimization model, the width of the tip of the teeth, the spacing of the teeth and the hollow are studied. The influence of the three tooth profile parameters on the average deformation of the tooth flank determines the optimum level for each element. As a result, the significant impact of each factor on the mean strain is addendum width>dendum root width>tooth spacing. The optimal combination of tooth shape structure parameters is determined as tooth top width 1.0 mm, tooth spacing 0.71 mm, tooth root width 1.0 mm, and the optimization results meet the requirements.
2023, (6): 127-132.
doi: 10.19287/j.mtmt.1005-2402.2023.06.021
Abstract:
In order to make a real and effective numerical simulation of the dynamic rounding process of the workpiece in the centerless grinding system and make a scientific and reasonable prediction of the final roundness of the workpiece, a dynamic rounding model of centerless grinding considering the instantaneous position change of the workpiece center is established and numerically simulated. Firstly, the influence of the center displacement of the workpiece caused by the change of the surface morphology of the workpiece during the grinding process and the center displacement of the workpiece caused by the vibration of the grinding system on the instantaneous position change of the workpiece center is analyzed. Then, considering the mutual coupling between the grinding wheel and the workpiece in the centerless grinding process and the material removal relationship, the dynamic rounding model of the workpiece grinding is established. Finally, the dynamic rounding model and the iterative algorithm for simulating the material removal and roundness change of the workpiece are used to simulate the dynamic rounding process of the workpiece, and the whole process of material removal and contour formation of the workpiece is reproduced. Through the analysis of the simulation results, the authenticity and rationality of the proposed centerless grinding dynamic rounding model and iterative algorithm are confirmed, which has certain guiding significance for the study of centerless grinding rounding process.
In order to make a real and effective numerical simulation of the dynamic rounding process of the workpiece in the centerless grinding system and make a scientific and reasonable prediction of the final roundness of the workpiece, a dynamic rounding model of centerless grinding considering the instantaneous position change of the workpiece center is established and numerically simulated. Firstly, the influence of the center displacement of the workpiece caused by the change of the surface morphology of the workpiece during the grinding process and the center displacement of the workpiece caused by the vibration of the grinding system on the instantaneous position change of the workpiece center is analyzed. Then, considering the mutual coupling between the grinding wheel and the workpiece in the centerless grinding process and the material removal relationship, the dynamic rounding model of the workpiece grinding is established. Finally, the dynamic rounding model and the iterative algorithm for simulating the material removal and roundness change of the workpiece are used to simulate the dynamic rounding process of the workpiece, and the whole process of material removal and contour formation of the workpiece is reproduced. Through the analysis of the simulation results, the authenticity and rationality of the proposed centerless grinding dynamic rounding model and iterative algorithm are confirmed, which has certain guiding significance for the study of centerless grinding rounding process.
2023, (6): 133-138.
doi: 10.19287/j.mtmt.1005-2402.2023.06.022
Abstract:
An improved particle swarm optimization method for milling parameters of ring thin-walled parts was proposed to address the issue of excessive local deformation of a ring thin-walled part during machining. By using finite element software, the simulation of the region with large local deformation is carried out to obtain the simulated milling force, and the objective function between the machining parameters and the milling force is established using Design- Expert13's orthogonal experimental response surface method. The improved particle swarm optimization algorithm is then used to optimize the objective function. Finally, the results demonstrate that the method of milling parameters optimization of annular thin-walled parts with an improved particle swarm algorithm can reduce the milling force in this region of the part with large local deformation by 24.9%, effectively reducing the deformation of annular thin-walled parts, and providing a new reference scheme for technicians in selecting milling parameters for annular thin-walled parts.
An improved particle swarm optimization method for milling parameters of ring thin-walled parts was proposed to address the issue of excessive local deformation of a ring thin-walled part during machining. By using finite element software, the simulation of the region with large local deformation is carried out to obtain the simulated milling force, and the objective function between the machining parameters and the milling force is established using Design- Expert13's orthogonal experimental response surface method. The improved particle swarm optimization algorithm is then used to optimize the objective function. Finally, the results demonstrate that the method of milling parameters optimization of annular thin-walled parts with an improved particle swarm algorithm can reduce the milling force in this region of the part with large local deformation by 24.9%, effectively reducing the deformation of annular thin-walled parts, and providing a new reference scheme for technicians in selecting milling parameters for annular thin-walled parts.
2023, (6): 139-145.
doi: 10.19287/j.mtmt.1005-2402.2023.06.023
Abstract:
The propeller blade is a key component in industrial applications. The shape of this surface often contains multiple complex surfaces, and the traditional measurement methods have defects of accuracy and timeliness. To address this problem, a quality assessment method of regional feature difference facing multi-faceted surfaces is proposed based on an automatic propeller blade measurement device. Firstly, the measurement device is constructed and the simulation attributes are designed based on mechatronic platform. Secondly, a regional energy clustering segmentation method driven by feature vector is proposed. The problem of multi-faceted concentration on the propeller blade surface is solved by segmenting the surface measurement region. Then, the local optimal measurement points are extracted based on segmentation regions and the layout of measurement point is also planned based on segmentation regions. Then, the non-linear regional accuracy difference hierarchical alignment method is proposed. The method achieves the positional transformation by hierarchical alignment through differences in accuracy between measurement regions, and the algorithm efficiency is optimized by combining non-linear calculation to achieve fast and efficient quality assessment. Finally, the feasibility of the method is verified by joint simulation and physical test.
The propeller blade is a key component in industrial applications. The shape of this surface often contains multiple complex surfaces, and the traditional measurement methods have defects of accuracy and timeliness. To address this problem, a quality assessment method of regional feature difference facing multi-faceted surfaces is proposed based on an automatic propeller blade measurement device. Firstly, the measurement device is constructed and the simulation attributes are designed based on mechatronic platform. Secondly, a regional energy clustering segmentation method driven by feature vector is proposed. The problem of multi-faceted concentration on the propeller blade surface is solved by segmenting the surface measurement region. Then, the local optimal measurement points are extracted based on segmentation regions and the layout of measurement point is also planned based on segmentation regions. Then, the non-linear regional accuracy difference hierarchical alignment method is proposed. The method achieves the positional transformation by hierarchical alignment through differences in accuracy between measurement regions, and the algorithm efficiency is optimized by combining non-linear calculation to achieve fast and efficient quality assessment. Finally, the feasibility of the method is verified by joint simulation and physical test.
2023, (6): 146-151.
doi: 10.19287/j.mtmt.1005-2402.2023.06.024
Abstract:
To realize flexible intelligent tool failure detection for production line, a mobile tool failure inspection system is designed. Through the analysis of system requirements, the structure design of the image acquisition module and the tool change module are targeted; by coupling the denoising module and the classification module, the tool fault diagnosis model has been trained; By analyzing the signal such as machine tool current, on-line failure diagnosis is realized and combined with in-place detection, which solves the problem of insufficient real-time detection. After experimental verification, it can be proved that there is no wrong diagnosis when the mobile tool failure inspection is carried out in the actual CNC machining process.
To realize flexible intelligent tool failure detection for production line, a mobile tool failure inspection system is designed. Through the analysis of system requirements, the structure design of the image acquisition module and the tool change module are targeted; by coupling the denoising module and the classification module, the tool fault diagnosis model has been trained; By analyzing the signal such as machine tool current, on-line failure diagnosis is realized and combined with in-place detection, which solves the problem of insufficient real-time detection. After experimental verification, it can be proved that there is no wrong diagnosis when the mobile tool failure inspection is carried out in the actual CNC machining process.
2023, (6): 152-156.
doi: 10.19287/j.mtmt.1005-2402.2023.06.025
Abstract:
Aiming at the technical problems of machining allowance detection and coordination of large 3D printing titanium alloy parts, the new 3D scanning technology was used to scan and compare the blank accurately, and the remaining quantity distribution results were obtained. According to the margin distribution results, the rough machining allowance coordination of the blank was realized, which effectively solved the problem of margin coordination with large blank margin difference and small local margin. It provides important technical support for the margin detection and analysis of irregular and large structural parts.
Aiming at the technical problems of machining allowance detection and coordination of large 3D printing titanium alloy parts, the new 3D scanning technology was used to scan and compare the blank accurately, and the remaining quantity distribution results were obtained. According to the margin distribution results, the rough machining allowance coordination of the blank was realized, which effectively solved the problem of margin coordination with large blank margin difference and small local margin. It provides important technical support for the margin detection and analysis of irregular and large structural parts.
2023, (6): 157-161.
doi: 10.19287/j.mtmt.1005-2402.2023.06.026
Abstract:
Aiming at the problems of shaft diameter measurement method in accuracy, reliability and adaptability, a precision and on-line measurement method of shaft diameter based on 2D laser measurement and full range calibration is proposed. In this method, 2D coordinate data of the inspection section is collected synchronously using the 2D laser profile sensor, and the radius of the measured shaft is solved based on the collected coordinate data and the least squares fitting algorithm. The test profile is optimized and determined based on the principle of minimum area. The full range calibration method is used to establish the error model of shaft diameter measurement, and the error compensation algorithm is used to compensate the nonlinear error of the system in real time to improve the measurement accuracy of shaft diameter. The research results show that the relative error of the method is less than 1%, and the non-contact, on-line and high-precision measurement of shaft diameter is achieved without disassembly.
Aiming at the problems of shaft diameter measurement method in accuracy, reliability and adaptability, a precision and on-line measurement method of shaft diameter based on 2D laser measurement and full range calibration is proposed. In this method, 2D coordinate data of the inspection section is collected synchronously using the 2D laser profile sensor, and the radius of the measured shaft is solved based on the collected coordinate data and the least squares fitting algorithm. The test profile is optimized and determined based on the principle of minimum area. The full range calibration method is used to establish the error model of shaft diameter measurement, and the error compensation algorithm is used to compensate the nonlinear error of the system in real time to improve the measurement accuracy of shaft diameter. The research results show that the relative error of the method is less than 1%, and the non-contact, on-line and high-precision measurement of shaft diameter is achieved without disassembly.
2023, (6): 162-166.
doi: 10.19287/j.mtmt.1005-2402.2023.06.027
Abstract:
Ultrasonic vibration cutting tests were carried out on 90W-7Ni-3Fe alloy and the influencing factors of surface integrity were analyzed. The microstructure morphology, surface structure, residual stress, roughness, surface hardness and crystal dislocation density of the workpiece were studied by experiments. The results show that the ultrasonic vibration cutting method has a smaller roughness than the conventional cutting mode, which has a significant restraining effect on furrows and scales, and has a smaller roughness of workpiece surface, and significantly improves the machining quality. When the same workpiece is cut, the tungsten phase and the bonded phase are located in the metamorphosed layer in the sub-surface region. The thickness of the tungsten phase metamorphosed layer is up to 400 nm, and the thickness of the bonded phase metamorphosed layer is up to 1 μm. The dislocation density of workpiece surface obtained by ultrasonic vibration cutting is relative to conventional cutting. Compared with the matrix hardness, the surface hardness of the samples cut by UEVC and CC is significantly increased, and the surface hardening of the samples cut by ultrasonic is more obvious. The higher residual stress is formed by ultrasonic vibration.
Ultrasonic vibration cutting tests were carried out on 90W-7Ni-3Fe alloy and the influencing factors of surface integrity were analyzed. The microstructure morphology, surface structure, residual stress, roughness, surface hardness and crystal dislocation density of the workpiece were studied by experiments. The results show that the ultrasonic vibration cutting method has a smaller roughness than the conventional cutting mode, which has a significant restraining effect on furrows and scales, and has a smaller roughness of workpiece surface, and significantly improves the machining quality. When the same workpiece is cut, the tungsten phase and the bonded phase are located in the metamorphosed layer in the sub-surface region. The thickness of the tungsten phase metamorphosed layer is up to 400 nm, and the thickness of the bonded phase metamorphosed layer is up to 1 μm. The dislocation density of workpiece surface obtained by ultrasonic vibration cutting is relative to conventional cutting. Compared with the matrix hardness, the surface hardness of the samples cut by UEVC and CC is significantly increased, and the surface hardening of the samples cut by ultrasonic is more obvious. The higher residual stress is formed by ultrasonic vibration.
2023, (6): 167-174.
doi: 10.19287/j.mtmt.1005-2402.2023.06.028
Abstract:
In order to realize the multiple-objective joint optimization of flexible workshop, such as completion time, machine load, delivery delay time and workshop energy consumption, a multi-objective scheduling method for flexible workshop based on adaptive penalty MOEA/D is proposed. The flexible workshop scheduling problem with multiple production machines, multiple processing tasks and multiple processes is described, and an optimization model is established. A flexible job shop scheduling method based on MOEA/D algorithm is proposed. Aiming at the problem that constant penalty factors cannot meet the different adjustment requirements of different neighborhoods for convergence and chromosome diversity, a penalty factor that can adjust adaptively with the density of adjacent chromosomes is proposed, and a flexible workshop scheduling process based on adaptive penalty MOEA/D algorithm is formulated. In the production scheduling experiment with 8 machine tools and 8 workpieces with 28 processes, the Pareto frontier solution searched by the adaptive MOEA/D algorithm can dominate that of the standard MOEA/D and the improved NSGA-II algorithm; In the production experiment of the equal weight optimal solution, the completion time, machine load, delivery delay time and workshop energy consumption of the adaptive MOEA/D algorithm scheduling scheme are less than those of the standard MOEA/D algorithm and the improved NSGA-II algorithm. The experimental results show that the adaptive penalty MOEA/D algorithm is effective and superior in flexible workshop scheduling.
In order to realize the multiple-objective joint optimization of flexible workshop, such as completion time, machine load, delivery delay time and workshop energy consumption, a multi-objective scheduling method for flexible workshop based on adaptive penalty MOEA/D is proposed. The flexible workshop scheduling problem with multiple production machines, multiple processing tasks and multiple processes is described, and an optimization model is established. A flexible job shop scheduling method based on MOEA/D algorithm is proposed. Aiming at the problem that constant penalty factors cannot meet the different adjustment requirements of different neighborhoods for convergence and chromosome diversity, a penalty factor that can adjust adaptively with the density of adjacent chromosomes is proposed, and a flexible workshop scheduling process based on adaptive penalty MOEA/D algorithm is formulated. In the production scheduling experiment with 8 machine tools and 8 workpieces with 28 processes, the Pareto frontier solution searched by the adaptive MOEA/D algorithm can dominate that of the standard MOEA/D and the improved NSGA-II algorithm; In the production experiment of the equal weight optimal solution, the completion time, machine load, delivery delay time and workshop energy consumption of the adaptive MOEA/D algorithm scheduling scheme are less than those of the standard MOEA/D algorithm and the improved NSGA-II algorithm. The experimental results show that the adaptive penalty MOEA/D algorithm is effective and superior in flexible workshop scheduling.
2023, (6): 175-179.
doi: 10.19287/j.mtmt.1005-2402.2023.06.029
Abstract:
In complex flexible manufacturing systems, it is important to conduct reasonable autonomous mobile robot (AMR) scheduling. In this study, the path planning and task assignment of AMR scheduling are studied to minimize the time for AMR to complete tasks. A mathematical model is established with the minimum AMR task completion time as objective function, and the map is modeled based on topology method. A greedy algorithm is used to assign tasks for orders with a constant length distribution for the interval time, and the algorithm calculation is reduced by classifying the AMR working state. Global path planning is based on the Dijkstra algorithm to search for the global shortest path of the AMR, and local obstacle avoidance path planning is performed through the AMR's laser radar. Finally, the effectiveness is verified through scheduling simulation experiments on the openTCS platform.
In complex flexible manufacturing systems, it is important to conduct reasonable autonomous mobile robot (AMR) scheduling. In this study, the path planning and task assignment of AMR scheduling are studied to minimize the time for AMR to complete tasks. A mathematical model is established with the minimum AMR task completion time as objective function, and the map is modeled based on topology method. A greedy algorithm is used to assign tasks for orders with a constant length distribution for the interval time, and the algorithm calculation is reduced by classifying the AMR working state. Global path planning is based on the Dijkstra algorithm to search for the global shortest path of the AMR, and local obstacle avoidance path planning is performed through the AMR's laser radar. Finally, the effectiveness is verified through scheduling simulation experiments on the openTCS platform.
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