制造技术与机床

Accuracy reliability analysis of industrial robots considering manufacturing errors

LI Guofa, HAN Liangsheng, HE Jialong, WANG Jili

2022, (5): 5-11. doi: 10.19287/j.mtmt.1005-2402.2022.05.001

[Abstract] FullText HTML PDF(1625KB)

Abstract:
Aiming at the problem of the positioning accuracy failure of industrial robots, a reliability analysis method considering the processing errors and assembly errors of the six-degree-of-freedom industrial robots is proposed. The ideal positive kinematics model of a six-degree-of-freedom industrial robot was established through the D-H model, and the error transmission path of each joint's mating surface was established. Combined with the small displacement spin method (SDT) and the MD-H model, the six-degree-of-freedom industrial robot was constructed with joint errors. Kinematics model, and use Monte for simulation test. Designed the Latin Hypercube Sampling (LHS) experiment, constructed the Kriging proxy model of the functional function of the six-degree-of-freedom industrial robot, and conducted reliability analysis and sensitivity analysis based on the proxy model and Monte Carlo method, and determined the impact on the six-degree-of-freedom industrial robot The main factor of positioning accuracy.

Optimization of grinding posture based on inverse kinematics of robot

XU Yuan, YIN Xuwei, WU Chaoqun

2022, (5): 12-18. doi: 10.19287/j.mtmt.1005-2402.2022.05.002

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For the series structure characteristics of industrial robots, the stiffness of industrial robots is lower than CNC machine tools, which will cause poor processing accuracy and processing quality of the robots. In order to improve the stiffness of industrial robots, a method for solving the processing posture of the robot was proposed based on the inverse kinematics of the robot. This paper takes the IRB6700 robot as the research object. Firstly, the optimal inverse posture configuration of the robot can be obtained by comparing the processing stiffness corresponding to the different inverse postures of the robot. Furthermore, considering the redundancy of robot processing, the inverse attitude of the robot is solved, the robot posture optimization model is established, and the optimization results under the given processing condition are obtained. Finally, finite element simulation is used to verify the correctness of the optimization of grinding posture based on inverse kinematics of robot.

Research on path planning of AGV transport robot based on improved A* algorithm

SHI Yingtuo, CHEN Hua, ZHANG Lianxin, SUN Pengfei, PEI Pei, LI Daiyang

2022, (5): 19-22. doi: 10.19287/j.mtmt.1005-2402.2022.05.003

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Based on the project of efficient production line, this paper aims to propose an improving A* path planning algorithm which is applied to the motion control of AGV. After detecting obstacles, it can be used in real-time path planning. So the safety of AGV robots application is improved without affecting the efficiency of transport. In this paper, the working environment of the AGV robot is analyzed, and the environmental model is established. Then the traditional A* algorithm was explained and analyzed, and the improvement measures were put forward for its shortcomings. Finally, the validity of the algorithm is verified by simulation.

Generation of foot-end trajectory of legged robot based on optimal time interval

XIN Yuhong, ZHANG Yongnian

2022, (5): 23-28. doi: 10.19287/j.mtmt.1005-2402.2022.05.004

[Abstract] FullText HTML PDF(1357KB)

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When the foot-end trajectory planning of the legged-robot is carried out in the task space, the nonlinear mapping relationship between the task space and the joint space will cause the speed and acceleration of the joint motor to exceed the limit or mutate, thus affecting the motion stability of the robot. In order to solve this problem, a trajectory generation algorithm of legged- robot based on optimal time interval is proposed in this paper. Firstly, a series of discrete points of the foot-end trajectory are planned in the task space, and the corresponding joint angles are calculated by using the inverse kinematics solution. Secondly, the joint angles are taken as constraints, and the time interval between the trajectory points is taken as the optimization object. The functional relationship between the robot joint speed, acceleration, acceleration speed and time interval is established, and a multi-objective optimization model oriented to the optimal time interval is constructed. Finally, egmented chromosome segment mutation are introduced to improve the traditional genetic algorithm to obtain the optimal solution of robot motion performance. The comparative experiments show that the peak acceleration in joint space is reduced by 73.58%, the peak jerk is reduced by 77.15%, and the acceleration in Y-direction is reduced by 61.82% in task space.

Study on collection method and influence analysis of environmental pollution in dry cutting

WANG Yangmin, LIU Qianjun, PAN Yi, XU Guoda, SUN Yuxin, HE Yan, WANG Yulin

2022, (5): 29-35. doi: 10.19287/j.mtmt.1005-2402.2022.05.005

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As the mainstream technology of green machining, dry cutting technology has been widely used. In order to control the environmental pollution of dry cutting, a machine added environmental pollution acquisition tool which could integrate the data of dust, oil mist and noise was developed. An on-line acquisition method of environmental pollution was proposed. The single factor test and orthogonal test were carried out, and the effects of cutting speed, feed rate per tooth, cooling conditions and material types on environmental pollution were studied. The results show that the best sampling orientation and distance are in front of the protective door of the machine tool and 0.5m; Compared with traditional cutting, dry cutting process has higher dust pollution and lower oil mist pollution; The cutting speed and material type have a great impact on the environmental pollution emission, the feed rate per tooth has a small impact, and the cooling mode has a certain impact on the dust concentration. The research results can provide reference acquisition equipment and methods for the acquisition of dry cutting environment data, and provide data support for process optimization and green evaluation.

Cyclone milling technology and its application in precision ball screw machining

SONG Xianchun, SUN Yue, ZHUANG Lijun, ZHUANG Ran, GUO Yingjie

2022, (5): 36-41. doi: 10.19287/j.mtmt.1005-2402.2022.05.006

[Abstract] FullText HTML PDF(1209KB)

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Precision ball screw pair as the “core key parts” of high-end equipment manufacturing industry, its processing and manufacturing accuracy directly affects the performance level of equipment. At present, the main manufacturing technology of thread processing is grinding technology, cyclone milling and so on. In this paper, the characteristics and application of cyclone hard milling technology are studied, and the temperature field distribution and thermal deformation law of ball screw in cyclone hard milling process are obtained by virtual simulation technology combined with field experiment. Whirl hard milling can realize high efficiency, green, environmental protection, low consumption and no pollution in the process of machining screw. It has important theoretical and application value to carry out in-depth research on whirl hard milling technology of precision ball screw.

Optimization of milling parameters of thin-walled parts based on Kriging-MIGA algorithm

HAN Jun, CAO Longkai, XU Rui, YAO Sheng, XIONG Fengsheng

2022, (5): 42-46. doi: 10.19287/j.mtmt.1005-2402.2022.05.007

[Abstract] FullText HTML PDF(1295KB)

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Aiming at the machining deformation problem of an aluminum alloy thin-walled shell part, with the milling force as the optimization goal, through the Isight platform, a milling parameter optimization method based on the Kriging-MIGA algorithm is proposed. The optimal Latin hypercube experimental design method was used to establish the parameter sample points, and the Kriging approximate model between the milling parameters and the milling force was built using the sample points. The MIGA algorithm was used to globally optimize the approximate model, and a set of milling that could minimize the milling force was obtained. Combine the parameters and get the predicted value. The research results show that the optimization of milling parameters based on the Kriging-MIGA algorithm reduces the milling force by 39.37% and effectively reduces the deformation of the aluminum alloy thin-walled shell. The research method in this paper is of great significance to the selection of milling parameters of thin-walled parts.

Research on multi-objective flexible job scheduling based on improved genetic algorithm

LI Changyun, GU Pengfei, LIN Duo

2022, (5): 47-52. doi: 10.19287/j.mtmt.1005-2402.2022.05.008

[Abstract] FullText HTML PDF(1355KB)

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Aiming at the problems of excessive machine load and idle machines caused by uneven production time distribution of processing machines in the workshop production process, a multi-objective flexible job shop scheduling model including balanced machine utilization was established, and an improved genetic algorithm was designed. Using POX crossover operator and multi-point crossover method, using neighborhood-based mutation operator. Finally, the experimental results verify that the algorithm is suitable for solving this kind of multi-objective flexible job shop scheduling problem, and the improved algorithm is also better than other comparison algorithms.

Comparative study on application of normal alignment technology in aircraft digital drilling

WANG Dongming, JIANG Zhihua

2022, (5): 53-58. doi: 10.19287/j.mtmt.1005-2402.2022.05.009

[Abstract] FullText HTML PDF(1475KB)

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With the comprehensive application of digital drilling system in aircraft assembly, it is especially important to master the key technology of normal vector finding technology in digital drilling system. Based on three different digital drilling systems, the hardware selection, hardware layout, calculation model and workflow in the application of normal vector finding technology are introduced and compared and analyzed respectively. The key technologies of the digital drilling system include: in hardware selection, the measurement sensor with high accuracy and good reliability should be preferred; in layout, rectangular layout should be used as much as possible to ensure that the sensor ray normal intersects with the spindle axis; in presser foot size, the presser foot plane needs to be perpendicular to the spindle axis, and the presser should be made of softer material as much as possible to ensure that the area to be made is not crushed; in the calculation of the normal sensor, the presser foot plane should be perpendicular to the spindle axis. In the normal sensor calculation model, based on the robot drilling system, the least-squares model is used to solve with higher accuracy; based on the five-axis CNC machine tool drilling system, the binary angle model is used with higher accuracy.

Optimal design of double position films intelligent feeding system and the research of its deviation correction and motion planning

XU Xiaohua, LV Yong, JIANG Guiping, ZHANG Zhengpo

2022, (5): 59-65. doi: 10.19287/j.mtmt.1005-2402.2022.05.010

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This paper studies the scheme of intelligent feeding system for double station conductive films with automatic azimuth recognition and deviation correction function. The combined evaluation method of comprehensive calculation evaluation-overall experience evaluation based on the method of weight coefficient and empirical fuzzy interval are proposed and adopted to evaluate and optimize the feeding system,which gives consideration to both multi index synthesis and experience evaluation of assembly effect. Through the evaluation and selection of various schemes of the feeding system, the optimal design scheme is determined. The 4-dimensional coordinate system and coordinate rotation transformation method are used to analyze the azimuth deviation and correction algorithm of the double films , and then the concept and parameter of generalized correction and generalized deviation are proposed, finally the comprehensive relationship and calculation formula between the two are deduced. The movement process of the feeding system is planned to ensure the high efficiency of the system.

Design of constant current drive circuit for high voltage and high current piezoceramics

HUANG Junyuan, ZHANG Wei, JIANG Buhui

2022, (5): 66-71. doi: 10.19287/j.mtmt.1005-2402.2022.05.011

[Abstract] FullText HTML PDF(1134KB)

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Piezoelectric ceramic drivers mostly use high-voltage operational amplifiers to amplify the voltage amplitude and power of the piezoelectric ceramic control voltage, which has high voltage control accuracy and is widely used in driving power supplies. However, due to the limitation of its power dissipation, the output power of the high-voltage op-amp of the piezoelectric ceramic drive power supply is limited and cannot be adjusted flexibly. This article provided a high-voltage and high-current piezoelectric ceramic constant current drive circuit. Based on single-chip control, photoelectric isolation, high-precision digital-to-analog conversion, power amplification, MOSFET constant current amplification, digital closed-loop control, and other technologies, the piezoelectric ceramic constant current high current drive was realized, the output current could reach more than ten amperes, and the output voltage could be up to several hundred or even thousands of volts. At the same time, the charging, discharging current, and voltage control of piezoelectric ceramic was also realized through the closed-loop feedback regulation of current and voltage digital.

Design of suspended membrane insulating glass assembly line based on virtual simulation technology

LI Naizheng, SUN Jianghong, HE Xueping, HE Yufan, GAO Feng

2022, (5): 72-76. doi: 10.19287/j.mtmt.1005-2402.2022.05.012

[Abstract] FullText HTML PDF(1589KB)

Abstract:
Taking double suspended film insulating glass production line as the research object, a simulation scheme of glass production line in double suspended film was constructed based on virtual simulation software platform. Firstly, the process of production line design based on virtual simulation technology is introduced. Secondly, the design of the film welding manipulator was completed and the robot was selected according to the parameters of the manipulator. Then the robot and the overall production line planning, using simulation software to set up the process of each action, to achieve the workspace and motion trajectory analysis, to prove its rationality; Finally, the production beat of the whole process is calculated, and the balance rate of the assembly line shows that the production line meets the expected goal. This scheme can reasonably plan and configure each production unit, shorten the development cycle, reduce the risk of equipment damage, and provide a basis and verification platform for the design of entity production line.

Study on speed-regulation mechanism of cone-rotor magnetic coupler

GE Yanjun, LIU Shuliang, WANG Jianshuai

2022, (5): 77-83. doi: 10.19287/j.mtmt.1005-2402.2022.05.013

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A cone-rotor magnetic coupler, CRMC, is designed in this paper. The CRMC is simplified as a radial and axial combination model, and the expressions of air gap flux density and electromagnetic torque of each model are obtained by equivalent magnetic circuit method. The relationship between electromagnetic torque and slip ratio is calculated and verified, which provided conditions for analyzing the operation characteristics of CRMC. The function curves of output speed, torque and power with the axial coupling length of CRMC has been obtained by the finite element model simulation, it is verified that CRMC has good energy-saving effect and high speed regulation efficiency when applied to centrifugal load.

Design and co-axiality analysis of non-rotating conical workpiece fixture

XU Qiusong, ZHU Xianglong, DONG Zhigang, KANG Renke, ZHANG Lianxin

2022, (5): 84-88. doi: 10.19287/j.mtmt.1005-2402.2022.05.014

[Abstract] FullText HTML PDF(1378KB)

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Aiming at the problems of low positioning accuracy and complex replacement process of special fixtures for non-rotating cone-shaped workpieces, combined with the structural shape characteristics of non-rotating cone-shaped workpieces and the clamping and positioning requirements, a positioning scheme was designed according to the six-point positioning principle, the design and research of a fixture system for fast clamping and positioning of non-rotating conical workpieces was presented. A three-dimensional model of a non-rotating conical workpiece fixture was established, and the method of adjusting the co-axiality of the non-rotating conical workpiece was explored, and the influence of the radial adjustment device on the accuracy of the concentricity was analyzed. The tool positioning adjustment experiment realizes that the co-axiality of the workpiece can achieve ≤ Φ0.01 mm, which provides theoretical guidance for the design of the fixture and the co-axiality positioning adjustment of this type of workpiece.

Research on compound layered anti-disturbance control method of linear motor

CHEN Ke, HOU Ming, LIU Yunlong

2022, (5): 89-94. doi: 10.19287/j.mtmt.1005-2402.2022.05.015

[Abstract] FullText HTML PDF(1372KB)

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Aiming at the influence of different types of disturbance on the motor during the operation of the linear motor, a composite layered control method is proposed. The disturbance received during the operation of the motor is divided into two types: the first type is periodic disturbance, and the second type is norm-bounded disturbance. The full-order disturbance observer and H_∞ control are designed separately, and the two are combined to form a compound control. In the dSPACE hardware-in-the-loop simulation platform, the strategy was verified by experiments. The experimental results show that the composite hierarchical control method divides the disturbance into different types and adopts different methods to deal with it. Compared with the traditional method, which treats all the disturbance as one type, it has a better anti-disturbance effect.

Design of inner support fixture with joint expansion for circumferential welding of friction stir welding

YANG Zhongbao, ZHANG Jie, ZHANG Yanfeng, WANG Weixin, FANG Haodi, XIAO Benkang

2022, (5): 95-98. doi: 10.19287/j.mtmt.1005-2402.2022.05.016

[Abstract] FullText HTML PDF(1287KB)

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According to the actual production demand of friction stir welding circumferential welding, a special fixture with fixed diameter inner support is designed. The fixture can realize joint expansion between the combined support blocks in the whole operation process, and has the functions of automatic centering and self-locking, which solved the technical problems such as time difference in place, collision impact and poor circularity between positioning elements. The fixture can not only effectively improve the manufacturability and assembly of product welding, but also provides a new method and idea for the fixture design.

Thermal simulation and test research on nozzle of FDM 3D printer

YU Xian, YOU Xiaoping, DONG Qiyuan, SUN Manqian

2022, (5): 99-104. doi: 10.19287/j.mtmt.1005-2402.2022.05.017

[Abstract] FullText HTML PDF(1777KB)

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The material form of FDM 3D printer and printing quality are affected by the temperature control system of nozzle assembly.Taking the nozzle of self-made FDM 3D printer as the research object and PLA as the test material, 3 heat sinks(blade shape, turbine shape, chuan shape) were designed according to the design criteria; the thermal simulation was completed by ANYSYS based on the transient temperature heat transfer theory; the turbine temperature test was completed by contact thermometer. The results show that the heat dissipation of the nozzle is affected by the shape and layout of the heat sink.For the forced air cooling structure with the fan arranged on the heat sink,the radiating fins arranged radially on the curved surface are more conducive to wind guidance and which has better heat dissipation.The heat flux density at the throat of the turbine heat sink (between the heating block and the heat sink) is large,the temperature decreases obviously from bottom to top and can be reduced by about 51.6%, the heat dissipation efficiency is high.

Research on feedrate planning algorithm with multi-constraints for CNC machining

JIN Xin, LIU Qiguang, LV Jie, XU Feifei, SUN Xiaonan

2022, (5): 105-111. doi: 10.19287/j.mtmt.1005-2402.2022.05.018

[Abstract] FullText HTML PDF(2143KB)

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As a key technique in multi-axis CNC machining, feedrate planning plays an important role to improve the machining accuracy for a given mechanical part, and receives extensive attention of domestic and overseas scholars. However, the current planning methods are mainly focused on the process limits, and rarely consider the constraints of axis velocity and axis acceleration in the planning. To cope with this issue, an adaptive feedrate planning algorithm is developed on the basis of proportional adjustment strategy in this paper. Firstly, curve scanning is performed on a given NURBS tool path, and the maximum reachable feedrate at each sample point can be calculated according to a decoupled mathematical model, which concludes the parallel constrains of the chord error, axis velocity and axis acceleration limits. Then, the initial feedrate curve is derived through B-spline fitting with these discrete velocity points. Finally, a proportional adjustment strategy is used to adjust the initial feedrate curve and realize the feedrate scheduling with multi-constraints. The performance of the proposed method is validated by performing experiments on a two-dimensional NURBS tool path, and the results demonstrate that both the chord error and drive constraints are confined into the preset ranges, which not only improve the kinematic characteristic of drive axes, but also further enhance the machining accuracy and efficiency.

Technology optimization of milling Ti40 burn resistant titanium alloy based on the optimal milling temperature

LV Dongsheng, WANG Baosheng

2022, (5): 112-116. doi: 10.19287/j.mtmt.1005-2402.2022.05.019

[Abstract] FullText HTML PDF(1532KB)

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In order to optimize the milling technology of Ti40 burn resistant titanium alloy, experimental study on milling parameters is carried out based on the principle of optimal cutting temperature. Firstly, the orthogonal experiment is carried out to build the empirical formula for milling temperature and parameters through regression analysis, and the effect of each parameter on milling temperature is analyzed. Secondly, the single factor experiment is conducted to determine the optimal cutting temperature value. Also, the empirical formula for the optimal milling temperature and milling parameters is obtained and validated with experiments. Finally, comparison analysis of the surface roughness under different milling temperature is completed. It is shown that the optimal milling temperature of Ti40 burn resistant titanium alloy is around 437 ℃, tool wear results is consistent with the optimal parameters, and better surface roughness with the optimal parameters can be acquired than common parameters. This investigation shows that it is reliable to optimize the cutting technology using the principle of the optimal temperature.

Milling cutter wear monitoring based on the energy ratio of the harmonic frequency

HE Zhoujie, HU Qiu, MA Xiaolong

2022, (5): 117-122. doi: 10.19287/j.mtmt.1005-2402.2022.05.020

[Abstract] FullText HTML PDF(1672KB)

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Based on the vibration signal and the theory of the second-order time synchroextracting transform, the energy ratio of the harmonic frequency and the energy ratio of the main harmonic frequency are proposed to meet the needs of condition monitoring of milling cutter abrasion. Three T45 milling cutters with different wear states were used for corresponding milling experiments. The results show that the proposed indicators can effectively evaluate the severity of milling cutter wear and can be used to monitor the wear status of milling cutters.

Tandem mold design for 90° elbow pipe fittings

YU Jinjie, RAO Pan, SUN Kuan, MA Sheng, JIANG Mengqi

2022, (5): 123-127. doi: 10.19287/j.mtmt.1005-2402.2022.05.021

[Abstract] FullText HTML PDF(1450KB)

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Tandem mold as a new molding technology can fully tap the potential of the injection molding machine, but the application of tandem mold is less interiorly. In this paper, tandem mold was introduced into the molding of plastic tubing coupling, and the tandem mold was designed in combination with the structural characteristics of 90° electric melting elbow PE pipe fitting. The tandem mold structure was composed of an upper and lower two-layer mold with one mold and two cavities. A needle-valve type hot runner system was designed to achieve alternate injection and holding. The T-lock with cylinder was designed to cooperate with the CAM plate to realize sequential mold opening and core pulling. The production results show that the use of tandem mold molding technology can greatly reduce the inactivity time of the injection molding machine and reduce the time cost of a single product.

Surface roughness prediction for Ti-48Al-2Cr-2Nb micro-milling based on 1DCNN-LSTM neural network

WANG Zhiyong, MA Xuan, DU Jinjin

2022, (5): 128-133. doi: 10.19287/j.mtmt.1005-2402.2022.05.022

[Abstract] FullText HTML PDF(1302KB)

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Surface roughness is the main index to measure the surface quality of micro machined parts. In order to improve the accuracy of surface roughness prediction in micro milling, a deep neural network prediction model based on one-dimensional convolution-long short-term memory (1DCNN-LSTM) is proposed. Using the efficient data processing mechanism of one-dimensional convolution network and the accurate prediction ability of long-term and short-term memory network, the problems of batch sequence data processing, sample key feature learning and small sample data surface roughness prediction are effectively solved. Taking spindle speed, feed speed, milling depth and micro milling cutter spiral angle as control variables, the prediction model of micro milling surface roughness is trained and verified by experimental data. The results show that compared with the traditional machine learning model, the average prediction error of 1DCNN-LSTM neural network is only 5.9%, which verifies the high-precision prediction performance of the model based on small sample data, and provides a new method for the prediction of micro-milling surface roughness.

Research on mechatronics modeling and simulation technology for propeller inspection

ZHANG Zhen, ZHANG Hui, WANG Yu, GAO Zhaolou, ZHANG Chunyan, FANG Xifeng

2022, (5): 134-140. doi: 10.19287/j.mtmt.1005-2402.2022.05.023

[Abstract] FullText HTML PDF(2043KB)

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A new propeller automatic inspection method is developed to improve the R&D efficiency of the marine propeller. The method is based on the mechatronic simulation platform NX MCD to tackle the difficulty of real debugging and improper precision fluctuation in its modeling and simulation. Firstly, 3D mechanical model is constructed and the mechatronic attributes are defined as the simulation ontology corresponding to physical parts according to the logic requirements. Then, an adaptive planning procedure of surface survey points is proposed based on mesh mapping. Finally, NX MCD, TIA portal, and S7-PLCSIM Advanced platform are connected to simulate PLC end control, real-time data interaction, and monitoring verification. In this way, virtual debugging in multiple fields of mechatronics is realized. Consequently, the feasibility of the proposed scheme is verified by simulation experiments, which provide a technical reference for the inspection of marine propellers and similar symmetrical free-form surface.

Sliding mode control based on additive decomposition PMSM for machine tool

LIU Huibo, CHEN Haoxin

2022, (5): 141-145. doi: 10.19287/j.mtmt.1005-2402.2022.05.024

[Abstract] FullText HTML PDF(1314KB)

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In view of the complexity and control performance of PMSM control drive system for machine tools, which was easily affected by load disturbance and nonlinear disturbance, the advantages of additive decomposition theory were used to decompose PMSM drive control system into primary system and auxiliary system. Among them, the auxiliary system adopted the improved sliding mode control method, which not only ensured the stability and robustness of the system, but also effectively weakened the chattering characteristic of the traditional speed sliding mode controller. The main system adopted the tracking strategy based on the current double closed loop, which could better control the response performance of the drive system and improve the engineering practicability of the method. The simulation results had shown that the structure control improved the dynamic performance and robustness of the system, and could be used in machine tool motor drive system.

Reliability research of washing machine drum assembly line based on improved FMECA

BAI Ying, YAO Qi

2022, (5): 146-151. doi: 10.19287/j.mtmt.1005-2402.2022.05.025

[Abstract] FullText HTML PDF(1045KB)

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In the development of non-standard automation equipment, it is difficult to carry out accurate reliability analysis due to the lack of previous fault data. In order to solve the above problems, this paper first improves the traditional FMECA method, gives dynamic weights to different experts by depended uncertain ordered weighted averaging, and determines the relative weights between different evaluation indexes by analytic hierarchy process. Secondly, according to the improved FMECA method, the reliability of the washing machine drum assembly line newly developed by a household appliance enterprise is analyzed. Finally, the analysis results before and after the improvement are compared. The results obtained by the improved FMECA method are generally consistent with those before the improvement, but greatly reduce the impact of the occasional judgment errors of experts on the analysis results, and consider the relative weight between the evaluation indexes to improve the accuracy of the analysis results.

Robust control method for permanent magnet synchronous motor for NC machine tool using extended sliding mode observer

LI Tao

2022, (5): 152-158. doi: 10.19287/j.mtmt.1005-2402.2022.05.026

[Abstract] FullText HTML PDF(1677KB)

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To achieve high-precision speed control of permanent magnet synchronous motor (PMSM) for NC machine tool, a robust control method using extended sliding mode observer was designed, which considered the combined disturbance of load torque and circuit and magnetic circuit. Firstly, the model of PMSM with compound disturbance was established. Then the compound disturbance was taken as the extended state, and the extended sliding mode observer was designed to realize the accurate estimation of speed, rotational acceleration and compound disturbance, and the analysis of convergence and stability were carried out. Finally, a new sliding mode approach law was proposed to overcome chattering, which realized the robust control of PMSM under compound disturbance. The simulation results show that the tracking errors of speed and acceleration of the proposed robust control method are only 0.1 r/s and 0.05 r/s², the tracking errors of speed and acceleration of the extended sliding mode observer are only 0.08r/s and 0.04 r/s², and the estimation error of compound disturbance is only 0.03 r/s². In the test experiment, the maximum tracking error of the proposed method for motor speed is only 0.3 r/min, compared with other methods, which has better practicability, faster response speed and higher control accuracy.

Analysis and optimization of the clamping performance of thin-walled workpiece of magnetorheological fixture

SHI Nannan, ZHAO Ziyi, YANG Min, ZHU Haihua, LUO Liwei, JIANG Xiaohui

2022, (5): 159-163. doi: 10.19287/j.mtmt.1005-2402.2022.05.027

[Abstract] FullText HTML PDF(2322KB)

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Aiming at the problem of machining accuracy caused by the difficulty of clamping thin-walled parts in aerospace industry and other fields, a flexible fixture based on the magnetorheological fluid (MRF) was designed. Combined with the curing characteristics of MRF to improve the strength of the auxiliary support of the weak stiffness structure, and the key factors such as the magnetic field strength and position affecting the workpiece stiffness was considered. Maxwell was used for magnetic field simulation, and the experimental verification was carried out. The magnetic field strength, shear stress and milling force were tested, and the relationship among them was studied. It is found that the greater magnetic field strength, the greater shear stress and the smaller milling force. Compared with other traditional fixtures, the results are indicated that MRF fixture can improve the clamping performance. The acceleration value with MRF is 0.29g, which is 82.4% lower than that without MRF, and the vibration during machining is significantly reduced. Compared with machining without MRF, the concentricity value is reduced by 38.5% with MRF. The related achievements provide support for machining and clamping technology of thin-walled parts in aerospace field.

Design and implementation of machine tool machining system based on Unity3D

YIN Minting, DONG Lei, ZHANG Xing, SHI Ruimin

2022, (5): 164-168. doi: 10.19287/j.mtmt.1005-2402.2022.05.028

[Abstract] FullText HTML PDF(978KB)

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As an indispensable technical equipment in the machining industry, it is important to train the technicians skilled in CNC machine tools. However, the training of CNC machine tool technicians requires expensive equipment and a large area of space, which needs a lot of funds. This paper establishes a three-dimensional model of CY-K360n machine tool, and completes a machine tool processing system based on Unity3D animation effects and UI interactive control. Export the machine tool machining system to the front desk in WebGL format and display it to users in B/S mode by ASP.NET technology, Implement functions of machine tool machining mode introduction and interactive machine tool demonstration. By using this machine tool processing system with browser, the difficult problems such as expensive learning price of machine tool processing had been solved, and the defect that corresponding software must be downloaded when using machine virtual system is compensated at the same time. It provides a new mode for operation and training of virtual machine tools.

Parametric design and simulation of cam mechanism in turret tool holder of automatic lathe

WANG Zhisen, WEI Hongxin, WANG Zhaodong

2022, (5): 169-174. doi: 10.19287/j.mtmt.1005-2402.2022.05.029

[Abstract] FullText HTML PDF(1272KB)

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In order to solve the cam profile design of turret tool holder of automatic lathe suitable for various working conditions, an integrated collaborative design method based on VB is proposed to realize cam profile generation, data output, motion characteristic analysis and simulation. Based on the analysis of the combined motion law of cam mechanism, nine kinds of cam profiles are designed, and the visual interface software engineering is developed. The initial parameters of the cam are adjusted in real time according to the required working conditions, and the rationality of the cam profile is verified combined with the simulation analysis results of the kinematic characteristics of the follower. Practice has proved that the function of software engineering is perfect, the design time and software cost are saved by about 50% compared with the traditional graphic method, and the degree of popularization is high.

Nonlinear fitting of spindle load vibration of NC machine tool based on Levenberg Marquardt

LIN Haisen, ZOU Chaosheng, LIAO Nilan, LIAO Chenghong

2022, (5): 175-179. doi: 10.19287/j.mtmt.1005-2402.2022.05.030

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Abstract:
When the spindle of NC machine tool is loaded, the micro vibration of the spindle under different conditions affects the machining accuracy, machining efficiency, tool wear and service life of the machine tool.In order to ensure the stability of machine tool spindle under load, a method of monitoring the vibration velocity of machine tool spindle and estimating the vibration by multivariate nonlinear fitting is proposed. Firstly, according to the three variable factors of machine tool spindle load - feed speed, spindle speed and cutting amount, the relationship between them and machine tool spindle speed vibration is established based on Levenberg Marquardt algorithm.Then, one of the three relational function models is selected as the basic function and associated according to “addition”, “subtraction”, “multiplication” and “division”. Finally, the combined function is used as the basic model for multivariate nonlinear fitting, the coefficient parameters are obtained, and the final fitting function is obtained. The experimental results show that this method can effectively predict the speed vibration of the spindle when the machine tool spindle is loaded, and the accuracy is more than 97%.

2022, (5): 180-180.

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2022 No. 5

Journal DynamicsMore

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