制造技术与机床

Design of robot experiment platform based on digital twin

ZHAO Junying, LI Yunlong, SHAO Xin, HU Chenglin, DENG Jiu

2022, (7): 5-10. doi: 10.19287/j.mtmt.1005-2402.2022.07.001

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Abstract:
A large number of experiments are needed to verify the robot during its secondary development and factory inspection. At present, the experimental platform has some disadvantages such as high cost, independent virtual-reality, high closure and heavy computation workload. Based on the above problems, digital twin technology is introduced to design a robot platform based on digital twin.Based on the digital twin technology, a robot experimental platform was developed. An open hardware platform was designed and built to directly show the motion axis and control system of the robot. The digital twin model was established in Tecnomatix and an communication network based on Modbus TCP, OPC UA and other communication modes was constructed. The data to be collected was analyzed, and the relevant data processing programs were written, which realized the virtual reality synchronization and reduced the operation and maintenance cost. A series of experiments were carried out on the experimental platform. The results show that the platform has reliable accuracy and can accurately and reliably realize the coordinate system calibration of industrial robot, and the body control of industrial robot and the cooperative control with peripheral equipment.

Obstacle avoidance trajectory planning based on improved particle swarm optimization algorithm

MA Dongyang, KU Xiangchen, MI Xian, YANG Xingtao, ZHAO Huanle

2022, (7): 11-17. doi: 10.19287/j.mtmt.1005-2402.2022.07.002

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Aiming at the problem of global obstacle avoidance trajectory planning of task space robot, a parameter optimization method is proposed to complete obstacle avoidance. Firstly, the polynomial function for trajectory description is derived, and the trajectory shape is changed by changing the parameter value, so as to avoid obstacles. Secondly, aiming at the minimum increment of robot joint angle and the shortest movement time, the penalty function is used to deal with the obstacle avoidance conditions, the optimization model is established, the problem is transformed into solving the optimal parameters, the exponential curve decreasing and dynamic adjustment strategy are proposed, and the particle swarm optimization algorithm is improved to complete the optimization. Finally, the kinematics modeling and workspace analysis of the robot are completed by Matlab, the trajectory planning results are verified by simulation, and the joint data curve of the robot's real-time motion is drawn at the same time. The results show that the improved particle swarm optimization algorithm optimizes the parameters and uses the quintic polynomial as the trajectory description to complete the obstacle avoidance planning, which improves the convergence speed and obtains the global optimal solution compared with the standard algorithm.

Modeling and simulation of robot joint friction based on mixed hybrid friction model

DONG Yawen, WANG Hongfei, ZHANG Baofeng, SONG Shuanjun

2022, (7): 18-22. doi: 10.19287/j.mtmt.1005-2402.2022.07.003

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Abstract:
In view of the problem that the single friction model can′t accurately describe the robot joint friction, the dynamic equation of the robot joint servo system is established. Firstly, a mixed friction model is established based on the analysis of Static friction, Coulomb friction and Lorentzian friction model. Secondly, a mixed friction dynamic model of the robot joint is established to describe the friction problem inside the robot joint. The purpose is to improve the modeling and control accuracy of the robot. Finally, the proposed model is simulated by MATLAB/Simulink. Compared with other models, the results show that the accuracy of proposed model for robot joint is better.

Flexibility analysis and simulation for multi-robot collaboration

TAO Ping, ZOU Chengwen, WANG Tianrui

2022, (7): 23-27. doi: 10.19287/j.mtmt.1005-2402.2022.07.004

[Abstract] FullText HTML PDF(1767KB)

Abstract:
In multi-robot collaboration operation tasks, its movement flexibility is related to the holistic movement performance of a collaborative system, which reflects the multi-robot coordination operability, and is very important to the coordinated motion planning of the system. Using a collaborative system of three robots, D-H kinematics model of each manipulator is established, and its collaboration space is obtained through Monte Carlo method, with leveraging the operability index for system flexibility assessment, the mathematical evaluation model to check the flexibility of the multi-robot collaboration system is developed, and MATLAB is used to simulate and analyze the flexibility of the multi-robot collaboration system to obtain its visual distribution. By analyzing the distribution of flexibility in the collaborative space, a suitable coordinated operation space is determined to ensure the optimal flexibility of the multi-robot collaboration system when operating tasks.

Based on multi-strategy improved grey wolf algorithm for robot path planning

QI Pengfei, DING Xin

2022, (7): 28-33. doi: 10.19287/j.mtmt.1005-2402.2022.07.005

[Abstract] FullText HTML PDF(1389KB)

Abstract:
Aiming at the shortcomings of basic grey wolf algorithm(GWO) in robot path planning, such as falling into local extremum and low exploration efficiency, a multi-strategy improved grey wolf optimization algorithm was proposed. Firstly, a random walk strategy is proposed to improve the global search capability of the algorithm. At the same time, in the search stage, a reverse learning mechanism based on convex lens principle is introduced to reverse learn the inferior individuals in the population, so as to improve the hunt range of individuals of wolves and avoid the algorithm falling into local optimal. Finally, to improve the smoothness of the path, B-spline is used to smooth the path. The simulation results show that compared with the traditional gray wolf algorithm, the improved gray wolf algorithm has better performance in the global optimal path planning and is more conducive to the robot to complete the task in the common environment and trap environment.

Narrow space combination machining technology for thin-walled shell structure

YANG Kai, LIU Hanliang, HU Xingping, FENG Changxi, WANG Peng, WU Di

2022, (7): 34-39. doi: 10.19287/j.mtmt.1005-2402.2022.07.006

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In this paper, according to the characteristics of the structure of right-angle milling head through the installation of right-angle milling head and the tip point compensation algorithm research, such as reference point by the cutting tool offset compensation method, controllers, two-way blade length compensation method, break through the narrow space of the complex structure is easy to appear when processing spindle interference and movement axis overtravel common bottlenecks; At the same time, the principle, error analysis and datum conversion of precision assisted off-line machining technology are discussed in detail to solve the coordinate system conversion problem of precision assisted off-line machining. The problem of narrow space combination machining of thin-walled shell structure is solved, which lays a good foundation for promoting the further improvement of spacecraft manufacturing level in China.

A method for machining the curved surface of the contraction section of large-diameter thin-wall stainless steel wind tunne

YANG Xiaofeng, JIANG Shui, MA Dongping, HAN Yong, LI Duo, ZHOU Rongtian

2022, (7): 40-44. doi: 10.19287/j.mtmt.1005-2402.2022.07.007

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The contraction section is an important part of the high-speed wind tunnel. The surface accuracy of the contraction section has a great impact on the flow field quality of the high-speed wind tunnel. The contraction section of a special wind tunnel is made of stainless steel. Its flow channel is a large-diameter, thin-walled and high-precision curved surface at the inlet of 7 m. The wall thickness of the contraction section is thin, the ribs are sparse, the overall stiffness is weak, and the processing is easy to deform. Through process research, a process method of mutually verifying deformation by using coated blade, differentiated cutting parameters, zonal alternating normal machining, on-line monitoring and sample measurement is explored, which not only ensures the requirements of profile accuracy, but also greatly improves the work efficiency, and successfully solves the problem of high-precision surface machining of thin-walled shrinkage section of large-diameter stainless steel.

Multi station cold heading process of A286 superalloy twelve point flange bolt

ZHENG Penghui, GUAN Yue, XU Jixing, FU Jianjian, ZHAO Wenlong, GAO Cheng, LIU Le

2022, (7): 45-50. doi: 10.19287/j.mtmt.1005-2402.2022.07.008

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Abstract:
A286 superalloy 12 point flange bolt is usually formed by hot upsetting, but its production process is cumbersome, processing efficiency is low and manufacturing cost is high. In this paper, according to the structural characteristics of an aerospace A286 superalloy twelve corner flange bolt, a multi station cold heading process is proposed. The real stress-strain curve of A286 superalloy is obtained by room temperature compression experiment and imported into the numerical simulation software DEFORM-3D. The multi station cold upsetting process of A286 superalloy twelve corner flange bolt is numerically simulated. The load time curve, equal effect force field distribution, equal effect variable field distribution and damage value distribution of each station are comprehensively analyzed, and the forming process parameters are determined. Finally, according to the numerical simulation results and the forming process, the corresponding die structure is designed, and the process test is carried out on the multi station cold heading machine. The test results show that the cold upsetting forming of A286 superalloy twelve corner flange bolt can be realized within the allowable stress range of the die by reasonably designing the number of cold upsetting processes. The A286 superalloy twelve corner flange bolt forgings obtained from the process test are fully filled and in good agreement with the simulation results. It has certain guiding significance for the multi station cold heading of this kind of parts and other similar parts.

Simulation and experimental analysis of ultrasonic assisted laser cladding Ni60 alloy coating on die steel

LI Chuanyu, LI Jinhua, YAO Fangping

2022, (7): 51-57. doi: 10.19287/j.mtmt.1005-2402.2022.07.009

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The Ni-base alloy coating was prepared on H13 steel by ultrasonic assisted laser cladding technology. The analysis model was established by COMSOL simulation software to explore the influence of ultrasonic frequency on the temperature and temperature gradient of the cladding layer, and the influence of ultrasonic frequency on the macroscopic morphology and microstructure was explored through experiments. The results show that the temperature of the cladding layer increases with the increase of ultrasonic frequency, while the temperature difference decreases first and then increases. With the increase of ultrasonic frequency, the longitudinal temperature along the cladding plane increases, and the temperature difference increases first and then decreases. The temperature gradient of cladding layer with ultrasonic application is smaller than that without ultrasonic application, and the temperature gradient decreases with the increase of ultrasonic frequency. With the increase of ultrasonic frequency, the dilution rate increases, and the cladding width and depth increase. The higher the ultrasonic frequency, the better the grain separation and refinement; Ultrasonic promotes element diffusion between cladding layer and matrix and improves element segregation.

Molecular dynamics simulation and experimental research on crater formation in short electric arc milling

QIN Caoyang, ZHOU Jianping, XU Yan, WANG Bingbing, JI Yu, TANG Wei

2022, (7): 58-64. doi: 10.19287/j.mtmt.1005-2402.2022.07.010

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In order to intensively study the formation process of crater in short electric arc milling(SEAM) and reveal the material removal mechanism in SEAM from the micro point of view, the molecular dynamics model of nickel in SEAM was established to simulate the formation process of crater and lattice change zone under different discharge energy, and the experimental research was carried out. The results show that the depth to diameter ratio and depth of the crater and lattice change zone increase first and then decrease during discharge, and with the increase of discharge energy, the diameter and depth of discharge crater and lattice change zone increase.

Research on high efficiency and low loss machining of WEDM based on SiC nano working fluid medium

MA Xiuli, TENG Kai, SUN Tao, ZHANG Lei

2022, (7): 65-68. doi: 10.19287/j.mtmt.1005-2402.2022.07.011

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SiC nano-medium is adopted to the HS-WEDM Test of Cr12MoV Die Steel and the machining effects are compared with the conventional medium in order to improve the cutting speed, improve the machining surface quality and reduce the electrode wire loss. The research shows that the cutting speed of SiC nano-medium is increased by 22.16%, the surface roughness of SiC nano-medium is reduced by 15.05% and the reduction of electrode wire of SiC nano-medium is reduced by 21.87% under the processing conditions of pulse width 45 μs, pulse interval 200 μs, peak current 25 A and mixed powder concentration 0.3 g/L. The intervention of nanoparticles improves the discharge conditions between the electrodes and increases the machining stability and the cutting speed through enlarging discharging-gap. At the same time, the intervention of nanoparticle improves the surface processing quality and reduces the wire electrode wear through increasing the spark discharge channel between the electrodes and dispersing the discharging points.

Analysis on the development of industrial internet of things and the transformation of intelligent manufacturing in manufacturing enterprises-based on the case study of Sany Group

HE Zheng, LI Yanni, YANG Xiaohong

2022, (7): 69-74. doi: 10.19287/j.mtmt.1005-2402.2022.07.012

[Abstract] FullText HTML PDF(1943KB)

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The connotation and development mode of intelligent manufacturing are studied. By adopting the descriptive case study and taking the intelligent manufacturing development of Sany Group as an example, the development mode at various stages and the construction of the Internet of Things platform have been studied and analyzed comparatively. The intelligent manufacturing transformation process of Sany Group is summarized as three stages, including product intelligence, manufacturing intelligence and service intelligence. Based on this, some enlightenments are put forward for Chinese manufacturing enterprises to carry out intelligent manufacturing transformation and develop industrial Internet of things.

Research on intellectual property of CNC technology for high-grade machine tools

LIU Meng, CHEN Jianfeng, HE Wuwei, ZHAO Hanzhuo

2022, (7): 75-80. doi: 10.19287/j.mtmt.1005-2402.2022.07.013

[Abstract] FullText HTML PDF(1883KB)

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High grade CNC system is related to industrial security and national security. In order to further break through the development of China′s national defense technology, the patent application and layout of major enterprises and research institutions in the field of CNC at home and abroad were analyzed based on Thomson data analyzer (TDA) patent data analysis tool. The results showed that the number of NC technology related patents has increased explosively since 2006 from a global perspective. China, Japan, the United States and Germany are the main output places of NC machine tool patents, and the patent output of the four countries exceeds 85% of the total patents. However, compared with other three countries, the international competitiveness of China′s patented technology is weak, and the technical strength of Chinese enterprises has obvious disadvantages. In addition, China′s universities and scientific research institutes have strong knowledge and technology output capacity, but they have not been truly transformed into industrial achievements. In the future, it is necessary to strengthen industry university cooperation and improve the transformation capacity of technology industry.

Design and analysis of the tooth profile of external shock wave swing movable teeth transmission

LI Jianhong, WANG Shijun, LI Jiapeng, WANG Jian, XU Chuanfa, WANG Ran

2022, (7): 81-84. doi: 10.19287/j.mtmt.1005-2402.2022.07.014

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In order to enrich the types of movable tooth transmission and design a reduction device with higher transmission efficiency and better performance, this paper proposes an external shock wave swing movable tooth transmission system and conducts an in-depth study on the tooth profile of its center wheel. Using the equivalent mechanism of the external shock wave and the swing movable tooth and the tooth profile envelope mechanism, the theoretical tooth profile equation and the actual tooth profile equation of the center wheel are derived, and the changes in the center wheel tooth profile and the actual tooth profile equation are analyzed. The relationship between the parameters. The curvature equation of the theoretical tooth profile of the center wheel is deduced, and the regularity of the curvature is verified through an example.

Design of measurement and control system of bearing tester for speed increase box of high-power offshore wind turbine based on LabVIEW

QIN Yongjin, GUO Liang, FU Liyang, CHEN Zhiyong

2022, (7): 85-90. doi: 10.19287/j.mtmt.1005-2402.2022.07.015

[Abstract] FullText HTML PDF(2001KB)

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In order to simulate the actual working conditions of the speed-increasing box bearings of high-power offshore wind turbines and carry out bearing reliability analysis, a set of bearing testing machine measurement and control system was developed and designed based on LabVIEW software. The system uses the industrial computer as the upper computer, and the SIMATIC S7-1200 series PLC as the lower computer. The data interaction is established through the Profinet bus to realize the precise control of the driving, hydraulic loading, and bearing lubrication parts of the testing machine. At the same time, it can run automatically according to the preset load spectrum, with multi-parameter collection and display such as speed, vibration, temperature, pressure, abnormal alarm and automatic protection functions.

Dimensional shrinkage of cylindrical parts fabricated by fused deposition modeling

WANG Yongzhou, LIU Jian, NAN Sihao, XI Darun, LIU Shanhui

2022, (7): 91-95. doi: 10.19287/j.mtmt.1005-2402.2022.07.016

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Abstract:
Heat shrinkage is a critical factor influencing the dimensional accuracy of FDM fabricated parts, full-factor experimental design method was adopted to investigate the influence of inner diameter, wall thickness and infill percentage on the inner diameter deviation of thin-walled cylindrical parts, and FDM experiments were carried out under the condition of five levels from each of factors in present study. Based on the measured data of the inner diameter deviation of the printed 125 samples, three dimensional scatter plots of the inner diameter deviation with respect to the structure parameters were drawn, and a statistical model for the inner diameter deviation of the printed cylindrical parts was established, of which the predicted values agree well with the measured values.

Design of main drive mechanism of servo press

JIANG Li, ZHU Denglin

2022, (7): 96-100. doi: 10.19287/j.mtmt.1005-2402.2022.07.017

[Abstract] FullText HTML PDF(1302KB)

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Based on the analysis of the existing servo pressure transmission mechanism, this paper shows a transmission mechanism scheme based on lead screw and wedge. By ADAMS for motion simulation, the virtual prototype of the transmission mechanism is established, the parameters that affect the torque of the servo motor in the transmission mechanism are analyzed. Finally, the inertia matching model is used to optimize the design, and the specifications of the drive motor and the specific parameters of the parts are determined. Compared with the traditional press transmission mechanism, the mechanism has the characteristics of low friction, high stiffness, stable precision and high dynamic response.

Optimization and decision-making method for low energy consumption and high quality of NC machining parameters

WU Yuhang, ZHANG Hua, YAN Wei

2022, (7): 101-108. doi: 10.19287/j.mtmt.1005-2402.2022.07.018

[Abstract] FullText HTML PDF(1385KB)

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In order to realise the green manufacturing of CNC machining system, a CNC machining parameter optimisation method oriented to low energy consumption and high quality is proposed. Firstly, the energy consumption characteristics of the CNC machining system and its subsystems under different operating conditions are analysed; then, with low energy consumption and low surface roughness as the objectives, the milling speed and feed amount are selected as the variables, a multi-objective optimisation model of the milling machining system is established, and the NSGA-II genetic algorithm is employed to solve the proposed model, then the most suitable machining parameters are decided from the equivalent solutions using the Topsis method. Finally, the validity of the proposed approach is verified with a cylinder stator endface machining case, and the feasibility of the optimisation model is further illustrated by the analysis of the results.

Effect of cryogenic treatment on the initial residual stress and deformation of hydrogen-resistant steel thin-walled components

SHANG Fengxiang, KONG Jinxing, LI Yunhua

2022, (7): 109-115. doi: 10.19287/j.mtmt.1005-2402.2022.07.019

[Abstract] FullText HTML PDF(2036KB)

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In order to reduce the effect of initial residual stress on the processing deformation of hydrogen-resistant steel thin-walled components, the effect of different cryogenic parameters and high-temperature compound aging on the initial residual stress was investigated based on the contour method, and the effect of initial residual stress release on the deformation of hydrogen-resistant steel thin-walled flat components was studied by simulating material removal using slow-walking processing. The results show that: the initial residual stresses in the forged hydrogen-resistant steel without aging treatment show the distribution characteristics of tensile stress on internal and compression stress on external, and the peak of residual tensile stress is 300 MPa; the spatial distribution characteristics of the residual stresses in the specimens after cryogenic treatment at 350 ℃ for 2 h, −130 ℃ for 10 h and 350 ℃ for 2 h remain stable, and the peak of residual tensile stress is reduced to 100 MPa, the stress amplitude is reduced by 66.7%. The specimens’ processing deformation of different aging treatments increased accordingly with the increase of material removal. The deformation of the untreated specimens after forging was the largest, and the deformation of the specimens treated at 350 ℃ for 2 h, −130 ℃ for 10 h and 350 ℃ for 2 h was the smallest, and the processing deformation of the thin-walled flat components with both types of aging was reduced by 66.7% and 44.4% when the removal amount was 1.6 mm and 3.2 mm.

Simulation and experimental study on shrinkage of diameter in cold shrink assembly of shoulder bushing

YUAN Tian, LI Xiaobing, CHEN Baolin, ZHANG Anshun, ZHANG Li

2022, (7): 116-120. doi: 10.19287/j.mtmt.1005-2402.2022.07.020

[Abstract] FullText HTML PDF(1310KB)

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The cold shrink assembly process of shoulder bushing parts has been selected as the research object in this paper, and the finite element software ABAQUS has been adopted to simulate and calculate to research the relationship and variation law between the he shrinkage of the inner diameter of $ \phi$64 mm shoulder bushing. Then based on the simulation analysis, the regression calculation formula of the shrinkage of the inner diameter of the cold shrink assembly of the $\phi $34 mm shoulder bushing was fitted and verified by experiments. The results show that the error of the calculated value of the shrinkage of the inner diameter of the cold shrink assembly of the $\phi $34 mm shouldered bushing is less than 13%, and the tolerance zone of the shouldered bushing of this type is successfully adjusted in the actual processing and assembly, which reduces the risk of supplementary processing.

Research on full process forming simulation of side outer panel based on die surface engineering

JIANG Lei, LI Shiquan, WANG Long, WANG Dapeng, ZHANG Xiongfei, SHEN Junqi

2022, (7): 121-128. doi: 10.19287/j.mtmt.1005-2402.2022.07.021

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In order to quickly determine the full-process forming process plan for large automobile panels, shorten the number of full-process forming simulation iterations and calculation cycles, and improve the full-process forming simulation accuracy, the side outer panel of a certain car model was taken as the research target. According to the product structure characteristics, the side outer panel was divided into several regions, combined with the process characteristics of each region the key section parameters of the die surface was drew, the die surface was designed efficiently by using the key section parameters, and the feasibility of the full process plan was verified by using the finite element analysis software. The results shown that the side outer panel were fully formed as a whole, without cracks, wrinkles, and obvious surface defects and other forming problems. On this basis, the die tryout was verified, and the samples with good forming effect and basically consistent with the numerical simulation results were obtained. Research has shown that after applying the die surface engineering technology based on the key section parameters-driven die surface design, the side outer panel does not need to carry out die surface design, repeated adjustment and optimization in the finite element analysis software, which significantly improves the simulation accuracy and efficiency of the full process of the side outer panel.

Rotation axis velocity planning method for five-axis CNC system

LI Yongyang, LIU Yuankai, WANG Ke, GE Pengyao, HUANG Guohui

2022, (7): 129-133. doi: 10.19287/j.mtmt.1005-2402.2022.07.022

[Abstract] FullText HTML PDF(1133KB)

Abstract:
In order to avoid the impact of velocity fluctuation in five-axis CNC system when the rotation axis linearly follows XYZ axes, a flexible velocity planning method of rotation axis was proposed, which had less calculation and was easy to realize in embedded system. Based on the principle of time synchronization, the velocity planning of the rotation axis was realized by using the motion time constraint of the XYZ axes. The reasonable starting speed, acceleration, driving speed and final speed were calculated, and the T-type speed planning interpolation output was carried out to the servo motor to realize the motion control of the five-axis CNC machine tool. The experimental results verified the effectiveness of the proposed scheme. Compared with the linear following machining of the rotation axis, the proposed control method could also maintain the velocity continuity of the rotation axis when performing multi-segment continuous trajectory interpolation, and each joint ran in a reasonable kinematic threshold range.

Research on the effect of minimal quantity lubrication on the machining properties of ultra-precision machining solid solution and aging maraging steel

ZHENG Zhongpeng, JIN Xin, GUO Xiaotian, GAO Ruilin, LI Chaojiang

2022, (7): 134-140. doi: 10.19287/j.mtmt.1005-2402.2022.07.023

[Abstract] FullText HTML PDF(2635KB)

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Maraging steel has excellent mechanical properties and mechanical properties and is widely used in aerospace, marine and vehicle manufacturing engineering fields. However, since this material is a typical difficult-to-machine material, the quality of the machined surface is poor, and the tool wear is serious. Therefore, the minimal quantity lubrication is of great significance for the machining performance of ultra-precision machining of solid solution and aging martensitic steel. In this paper, the research on the machining quality of ultra-precision machining maraging steel 3J33C, such as cutting force and surface roughness, is carried out in detail by using two heat treatment methods of solid solution and aging of maraging steel 3J33C. The material removal mechanism in the solid solution state and the aging state is revealed, which guides the processing technology of the difficult-to-machine maraging steel.

Research on the calibration method of structural parameters of five-axis magnetorheological machine tool with double swing table

ZENG Jingchao, WU Jianbo

2022, (7): 141-146. doi: 10.19287/j.mtmt.1005-2402.2022.07.024

[Abstract] FullText HTML PDF(2182KB)

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In order to realize the fast and accurate calibration of five-axis linkage structure parameters of AB double swing magnetorheological machine. An efficient and accurate measurement method was established. By analyzing the structural characteristics of the machine tool and the problems existing in the existing methods, the target calibration parameters are decomposed. The calibration methods and models of A-axis and probe, probe and polishing point, B-axis and polishing point are established respectively by using laser displacement sensor and on-board probe. On this basis, calibration and verification experiments were carried out. In the verification experiments, the errors of actual and predicted values in X, Y and Z directions were all less than 6 μm. The experimental results show that the proposed calibration method is used to verify the simpleness and reliability, which can meet the requirements of magnetorheological machine tools.

Defect detection of micromotor friction plate based on machine vision

LI Yuping, XIE Jun, WANG Zixian, ZHAO Yufan, YANG Qizhi

2022, (7): 147-151. doi: 10.19287/j.mtmt.1005-2402.2022.07.025

[Abstract] FullText HTML PDF(1547KB)

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The friction plate of micromotor is detected to judge whether it is complete by means of machine vision technology. Firstly, grayscale image of the friction plate is binarized according to the selected threshold, and then the connected region of the binary image is marked. Based on major semi axis of the minimum bounding rectangle of the target region, the region of the friction plate boundary is extracted. Secondly, gaps in the region of the friction plate boundary are eliminated through closing operation, then the region of boundary is transformed into sub-pixel contour. Finally, an improved least square method is used to fit the contour to obtain the center and radius of the friction plate. Distances between pixel points and the center of the friction plate are calculated in order to find the minimum distance. The minimum distance is compared with the radius to estimate whether the friction plate is incomplete. The experiment results show that the accuracy of the detection system reaches 98%. Therefore, the system can replace manual detection, effectively reduce labor cost and improve detection efficiency.

Influence of gear surface hardened layer on mechanical performance of heavy-duty gears

SHEN Yichen, CHEN Qidong

2022, (7): 152-157. doi: 10.19287/j.mtmt.1005-2402.2022.07.026

[Abstract] FullText HTML PDF(1806KB)

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During the production of heavy-duty gears, the surface is hardened to improve the overall performance. However, most of the existing analysis methods regard the gear surface as homogeneous material, without considering the influence of the hardened layer. In this paper, a gear solid modeling method is proposed, in which the hardened layer of gear surface is stratified and the material property changes gradually in the form of the power function. Based on the Hertz contact theory, a finite element numerical model is established to study the influence of the hardened layer on the stress field of the heavy-duty gear. The results are as follows: The meshing stress field is closer to the theoretical solution through the modeling method proposed in this paper; reasonable distribution indexes of the hardened layer can not only effectively reduce the stress of the gear but also increase the bonding strength; the thickness of hardened layer has a great impact on the contact stress, and when the thickness is between 1 mm and 1.5 mm, the stress field distribution of the gear is the most reasonable.

Sparrow search algorithm to solve flexible job shop scheduling problem

YANG Hongxiong, WANG Huiming

2022, (7): 158-164. doi: 10.19287/j.mtmt.1005-2402.2022.07.027

[Abstract] FullText HTML PDF(1223KB)

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In order to solve the problem that the traditional meta-heuristic algorithm has slow convergence speed and is easy to fall into local optimum when dealing with the flexible job shop scheduling problem (FJSP), The sparrow search algorithm (SSA) is proposed to solve the FJSP problem. Firstly, the flexible job shop scheduling problem is analyzed and studied, and mathematical modeling and simulation are carried out according to the characteristics of the problem, in order to minimize the maximum completion time and optimize the total energy consumption. Then, the optimization research method to solve the problem and the coding method of flexible job shop scheduling analysis problem are proposed, and the SSA process to solve FJSP is established. Finally, according to the standard example data and the actual workshop production data to simulate the algorithm, proved that the application of SSA in solving FJSP problems in the feasibility, superiority and efficiency, to help the intelligent control of the workshop.

Optimal scheduling of partially ordered flexible job shop based on hierarchical neighborhood strategy

LI Changyun, LIN Duo, HE Pinjie, GU Pengfei

2022, (7): 165-172. doi: 10.19287/j.mtmt.1005-2402.2022.07.028

[Abstract] FullText HTML PDF(1605KB)

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Aiming at the scheduling problem of workpiece process with complex partially ordered relationship in garment job shop, the characteristics and difficulties of this kind of problem are analyzed, and the improved arithmetic optimization algorithm is used to solve the complex partially flexible job shop scheduling model with the optimization goal of minimizing the maximum completion time. In the algorithm, the multi constraints of decoding are fully considered, and the optimal processing time of subsequent processes is determined through the previous process of the workpiece and the available time period of the machine. In the exploration stage, a two-dimensional clustering based on fitness and process completion difference is designed, and the population diversity is expanded through inter class crossover and effective mutation strategies, In the development stage, a hierarchical neighborhood strategy is designed for bottleneck work orders and bottleneck machines to enhance the local search ability of the algorithm. Through simulation experiments, extended benchmark examples are used to verify the superiority of the improved arithmetic optimization algorithm based on hierarchical neighborhood strategy in partially ordered flexible job shop scheduling.

Multi-objective workshop layout optimization based on adaptive genetic simulated annealing algorithm

LU Yizhen, LI Xixing, ZHU Chuanjun, WU Rui

2022, (7): 173-179. doi: 10.19287/j.mtmt.1005-2402.2022.07.029

[Abstract] FullText HTML PDF(1323KB)

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Good layout of workshop facilities can effectively improve the manufacturing process, reduce the cost of logistics and transportation between processing equipment, and then enhance the degree of lean manufacturing enterprises. Based on the actual situation of manufacturing workshop of FK company, this paper designed the layout constraint conditions, constructed the mathematical model of workshop layout to minimize the logistics cost and logistics time, and proposed an improved genetic simulated annealing algorithm to solve the model. On the one hand, the adaptive genetic operator strategy is introduced to realize the dynamic modification of genetic operator in the process of solving the algorithm. On the other hand, the probability jump of simulated annealing algorithm can avoid premature convergence, improve its global optimization ability and further enhance the performance of the algorithm. The feasibility and effectiveness of the model and algorithm are verified and analyzed by design comparison test and practical application case. The results show that the algorithm has good optimization ability, can effectively reduce the cost and time of workshop logistics, and has a good role in improving the actual workshop layout.

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