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

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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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Ultraprecision Machining
Structure design of four-axis linkage precision machine tool for hydrostatic motion pair
ZHAO Huiying, HAO Lei, ZHOU Chunlin, XUE Fei, ZHAO Lingyu, ZHAO Jianing
2024, (2): 9-17.   doi: 10.19287/j.mtmt.1005-2402.2024.02.001
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Large aperture planar, spherical and aspherical optical components are widely used in optical systems of lithography machine, high energy lasers, high resolution cameras and other high-end equipment. In the grinding stage of large aperture optical components, the size ≥400 mm×400 mm, surface profile accuracy Root Mean Square (RMS) ≤1 μm are the key technical indicators. The main problems in grinding process are high smooth surface profile machining and depth control of sub-surface damage layer. According to the available results, the high precision hydrostatic motion pair is used in grinding machine, which can effectively improve the smoothness of the surface profile and reduce the thickness of the sub-surface damage layer after polishing the optical element. High-performance grinding machines with the above characteristics are prohibited to China abroad, and there are no mature products in China. In this paper, a four-axis linkage precision machining machine tool with hydrostatic motion pair is developed. The main configuration of the machine tool is analyzed. The precision distribution for the main moving parts of the machine tool is carried out. The design scheme of the X/Y/Z/C four axis based on the hydrostatic motion pair has been completed. Finally, experiments on the grinding process of optical components were conducted. For the 380 mm×541 mm size microcrystalline glass, the surface shape accuracy and surface roughness reached ±0.471 μm and Ra 0.3 μm, respectively.
The research on the steady characteristics of aerostatic thrust bearing for machine tool spindles with different parameters
DING Boyao, ZHANG Jianbo
2024, (2): 18-23.   doi: 10.19287/j.mtmt.1005-2402.2024.02.002
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The spindle of ultra precision machine tools is generally supported by aerostatic bearings. In this paper, fitting functions between different parameters and bearing load capacity and mass inflow rate are obtained by combined Fluent software with MATLAB neural network fitting toolbox. Then the effects of different parameters on the steady characteristics of aerostatic thrust bearings are studied by the fitting functions. Firstly, the numerical pressure distribution results calculated by the Fluent in the paper are compared to experimental data in the literature published in the past to verify the correctness of the calculation model and boundary condition. Secondly, the fitting functions between bearing diameter, orifice diameter, gas film thickness, supply pressure with load capacity and mass inflow rate are obtained by using MATLAB neural network fitting toolbox. Then, the influence of the external supply structure on the pressure distribution and the effects of gas film, orifice diameter and supply pressure on the load capacity and mass inflow rate are analyzed. The results shown that the external supply structure has no significant effect on the pressure distribution and the load capacity is increased with the decreasing the film thickness, the increasing the orifice diameter and supply pressure. Moreover, the mass inflow rate is increased with the increasing the film thickness, orifice diameter and supply pressure.
Study on the micro vibration of viscous and inertial coupling aerostatic bearings
YANG Guangwei, SUN Mubang, YU Liqing
2024, (2): 24-30.   doi: 10.19287/j.mtmt.1005-2402.2024.02.003
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Because of the simple structure and high stiffness,the orifice-restrictor air bearings are widely used in ultra-precision machining. However, increasing the roughness of ultra-precision surface is limited due to the micro-vibration in the orifice aerostatic bearings. In order to suppress the micro vibration, a novel viscous and inertial restrictor aerostatic bearing is designed in this paper. By employing the CFD method,the influences of the structure parameters on the stability of the novel aerostatic bearing are studied carefully. And the experimental test-beds are designed to test the bearing performances. The results show that the viscous and inertial restrictor aerostatic bearings can reduce the micro vibration compared with orifice air bearings efficiently. Meanwhile, increasing the permeability of porous materials, increasing the orifice diameter, and reducing the height of the pressure equalizing chamber can also reduce the micro vibration of the viscous and inertial restrictor aerostatic bearings.
Non-traditional Machining
Study on surface quality and tool wear of TiAl alloy in ultrasonic longitudinal torsion assisted milling
SONG Yangxuan, WANG Zhenhua, HUANG Lei
2024, (2): 31-37.   doi: 10.19287/j.mtmt.1005-2402.2024.02.004
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TiAl alloy is a typical challenging material to process, and standard machining is difficult to achieve acceptable surface quality. As a result, this research proposes ultrasonic longitudinal torsion aided milling. Using a single factor control experiment, it was determined how the machining parameters affected the surface roughness, surface morphology, and microhardness of TiAl alloy during ultrasonic longitudinal twist milling and conventional milling. The outcomes demonstrate that TiAl alloy surface roughness may be improved using ultrasonic longitudinal torsional milling, leading to typically low roughness (Ra<0.6 μm). The TiAl alloy’s surface hardness may often be increased by more than 10% thanks to ULTM. The workpiece and chip obtained by ULTM have improved surface quality. The tool bottom edge wear of ULTM is greatly decreased while milling 150 mm3 TiAl alloy, and the primary wear types are oxidation wear and diffusion wear.
Analysis and optimization of laser cutting process of carbon steel plate
ZHONG Yi, LUAN Xianye, LI Xiaoyu, XUE Haifeng, LI Tianxiang, WU Lupeng
2024, (2): 38-45.   doi: 10.19287/j.mtmt.1005-2402.2024.02.005
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With the continuous development of science and technology, laser cutting technology has become one of the indispensable technologies in modern industrial production. Carbon steel laser cutting parts processing technology is also getting more and more applications, with the quality of the processed workpiece increasingly demanding, the optimization of the laser processing process in order to obtain a higher quality of cutting and cutting accuracy of the steel plate is of great significance, in order to optimize the laser processing of carbon steel, this paper to 3 mm carbon steel as the object, using a 1 500 W laser systematic study of the laser power, cutting speed, the amount of out-of-focus, Auxiliary gas pressure and other cutting parameters on the cutting quality. The cutting width, surface roughness and slag height are selected as the standards for evaluating the cutting quality, and the influence law of process parameters on cutting quality is comprehensively analyzed and the influence mechanism is studied. At the same time, the data are predicted and analyzed by convolutional neural network, and the genetic algorithm with the non-dominated sorting of the elite strategy is adopted to optimize the process parameters, so as to get the optimal process parameters for laser cutting of carbon steel under the condition of the auxiliary gas is oxygen. The optimal process parameters for laser cutting carbon steel under the condition of oxygen as auxiliary gas are P=1 500 W, v=64 mm/s, F=2.6 bar, and h=2.9 mm. It is found that the cut surface of the optimized piece is smooth without slagging phenomenon and the width of the slit is small, which meets the expected standard.
Experimental study on effect of short arc turning on recast layer of honeycomb ring
WANG Zijian, ZHOU Bisheng, ZHOU Jianping, WANG Bingbing, ZHANG Shengsheng, DING Shengwei
2024, (2): 46-52.   doi: 10.19287/j.mtmt.1005-2402.2024.02.006
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The honeycomb sealing structure is the advanced and efficient sealing structure of contemporary aviation engines. It is difficult to meet the processing quality requirements of traditional processing, and the general electricity processing efficiency is low. Therefore, the short arc car is selected. Experiments for honeycomb seals with GH3536. In order to study the impact of different parameters on the post -processing layer of the processing layer, set the single factor test, and use the thickness and micro -appearance of the recasting layer as the test index, analyze the current and voltage waveform diagram, the surface scanning electron microscopy, cross -sectional gold phase diagram, and the cross -section gold phase diagram, and Surface can spectrum. The results prove that the thickness of the reconstruction layer increased with the voltage and the rate of feed, and the speed of the workpiece and electrode decreased, and the surface quality has the same trend. The casting layer is smaller and the surface quality is better. Therefore, properly reduce voltage and feed speed, improve workpiece and electrode speed, and use wide groove baffle electrodes, which can reduce the phenomenon of micro -cracks, erosion pit, folds, and melting particles, layer thickness.
Intelligent Manufacturing
Twin research of intelligent logistics lab based on Unity3D
SUN Li, LI Jiubo, QIAO Wenxuan, ZHANG Hanwen, HAO Liucheng, XU Zhongxun
2024, (2): 53-58.   doi: 10.19287/j.mtmt.1005-2402.2024.02.007
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Aiming at the problems of limited experimental equipment; According to the digital twin technology, the logistics and transportation equipment was studied and a virtual simulation experiment system was designed through the Unity3D virtual reality development platform. According to the existing logistics and transportation equipment, including conveying materials, stacker storage and other equipment as the research object, the use of SolidWorks and 3DMax to complete the establishment of the three-dimensional model of the experimental equipment, the use of S7-PLCSIM Advancde to complete the control program of the logistics equipment, through the PLC and Unity3D communication and data interaction, and finally in the virtual environment of Unity3D to complete the virtual simulation experimental system of logistics transportation. Through the system, the logistics and transportation process such as material transfer, warehousing and outbound can be realized in the virtual space, and the virtual visualization of the logistics and transportation work process can be realized, and the working action of logistics equipment can be completed through the PLC program written, which can effectively solve the problems of insufficient experimental equipment, so that the trainers can get the due experimental operation and improve the experimental efficiency.
Scheduling of dual-arm multi-cluster tools considering wafer residency time constraints
MA Liping, LIU Yumin, ZHAO Yanping, WANG Jipeng, CHENG Zixin
2024, (2): 59-66.   doi: 10.19287/j.mtmt.1005-2402.2024.02.008
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Multi-cluster tool represents the current trends of wafer fabrication equipment, resulting that its scheduling and control can directly affect the overall economic efficiency of semiconductor chip manufacturers. Considering the wafer residency time constraint in semiconductor chip fabrication, a feature-transformation-based scheduling approach is presented to improve the productivity of dual-arm multi-cluster tools. Firstly, a conceptual wafer fabrication system called the characteristic dual-arm cluster tool is proposed, and its steady-state scheduling method is investigated as well. Secondly, by using a feature transformation approach, a multi-cluster tool with arbitrary topology can be effortlessly reduced into a characteristic dual-arm cluster tool. Thirdly, according to the transformed characteristic dual-arm cluster tool, the individual robot activity sequence is reassigned, and then a feasible steady-state schedule for the multi-cluster tool can be obtained. Finally, illustrative examples are offered to validate the effectiveness of the presented approach.
Construction and application of a digital twin system for data-driven intelligent manufacturing line
HUANG Hanyu, MAO Kefu, YUAN Minghai, ZHENG Liang, PEI Fengque
2024, (2): 67-74.   doi: 10.19287/j.mtmt.1005-2402.2024.02.009
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In response to the demand for the intelligent development of production lines, a data-driven digital twin system for the production line has been constructed, addressing challenges such as lengthy on-site debugging cycles, limited three-dimensional visualization capabilities, asynchronous production data, and high on-site monitoring costs typically encountered in traditional production lines. Initially, the digital twin models for various equipment on the production line were constructed using Process Simulate. Real-time data from production line equipment was retrieved via OPC UA and Modbus communication protocols, based on the data communication network and data acquisition architecture diagram. This data was subsequently stored in the corresponding database, serving as the data source driving the digital twin model, thereby enabling the real-time mapping of physical entities by the digital twin model. Finally, a virtual simulation environment was established for the virtual commissioning of the digital twin system. Additionally, the effectiveness and feasibility of the production line digital twinning system were verified by constructing an example verification platform. This paper highlights the successful construction of the production line digital twin system and emphasizes the potential impact of digital twinning technology on the intelligent evolution of modern production lines.
Robotic compliance assembly system based on multidimensional admittance control
DAI Na, GE Hailong, CHENG Wei, ZHANG Yu, HOU Xingqiang
2024, (2): 75-79.   doi: 10.19287/j.mtmt.1005-2402.2024.02.010
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Aiming at the problem of excessive contact force and damage to the workpiece caused by jamming or wedge phenomenon encountered in the peg-in-hole assembly process, a robot flexible assembly system based on admittance force control is proposed. The peg-in-hole assembly process is divided into the search phase and the adjustment insertion phase. Firstly, a search strategy based on Archimedes spiral is proposed in the search stage. Secondly, a admittance force control assembly method based on the multi-dimensional direction of equivalent mass-damping-spring is proposed in the adjustment insertion stage. Finally, the circular shaft hole is selected for the actual assembly experiment, and the results show that the proposed method can achieve the robot compliance jack and achieve the expected effect.
Simulink-based study on visualized loading of robotic arms
YU Zijiang, LI Cunzhi, YU Fei, XIE Aijun, LIU Guoliang
2024, (2): 80-84.   doi: 10.19287/j.mtmt.1005-2402.2024.02.011
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Automatic loading equipment can realize data acquisition and analysis through modern technology to optimize the manufacturing process, improve production efficiency and product quality, so as to better realize intelligent manufacturing. In order to realize the automatic loading process of chain plates and other parts, this paper introduces the construction process of the three-dimensional visual human-computer interaction platform model of the robotic arm, takes the Gluon robotic arm as the object of analysis, carries out the positive kinematics analysis and the inverse kinematics validation, and builds the control system model through Simulink, realizing the joint simulation of the Gluon robotic arm. During the simulation process, the rotation angle and angular velocity of each joint and the chi-square transformation matrix of the end-effector are displayed in real time. Through the verification, the feasibility support is provided for the later construction of the physical platform, which lays the foundation for further optimization and improvement of the system functions.
Machine Vision and Detection
Object recognition and grabbing detection based on deep learning
SHEN Guangpeng, MIAO Hongbin, YU Lang, SU Hepeng
2024, (2): 85-90, 98.   doi: 10.19287/j.mtmt.1005-2402.2024.02.012
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Aiming at the problem of complex operating environment and interference between different parts in the industrial production of robotic arm grasping, this paper proposes a target recognition and grasping method based on deep learning, so as to reduce the uncertainty of object position in the grasping scene and improve the success rate of detection and grasping. The Convolutional Block Attention Module (CBAM) is used to improve YOLO-V5 to enhance the attention and extraction ability of convolutional networks on image features and improve the detection accuracy. The average recognition rate of the improved network increased by 5.26%, proving that the improvement was effective and successful. In this paper, a set of robotic arm grasping system is built by AUBO-i5 manipulator, electric gripper, camera, and six-axis force sensor, and the experimental results show that the proposed method can adapt to different grasping scenarios in real grasping, reduce external interference, improve the success rate of grasping, and have good application prospects.
Research on the recognition and localization method of small mechanical parts based on improved U-Net
ZHOU Lin, HE Li, WANG Chen, HUANG Yuchun, ZHOU Zhixiao, WANG Shenghuai
2024, (2): 91-98.   doi: 10.19287/j.mtmt.1005-2402.2024.02.013
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Aiming at the problem of slow recognition and inaccurate localization of small mechanical parts based on machine vision, this paper proposes a method of recognition and localization of small mechanical parts by combining Improve U-Net (IU-Net) and minimum bounding rectangle(IU-Net-MBR). Firstly, a visual sorting test platform is built to produce a data set of small mechanical parts.Secondly, in order to improve the feature extraction efficiency, the feature extraction network of U-Net is replaced by a lightweight MobilenetV2 network, which reduces the parameters of the model and the amount of computation.Then, in order to improve the segmentation accuracy and the robustness of the U-Net, the SE (squeeze and excitation) attention module.Finally, the length and width basic parameters of the parts are obtained using the minimum outer connection matrix to realize the part identification and localization. The experiments show that IU-Net improves 4.39% and 3.82% in mean intersection over union (Miou) and pixel accuracy (PA) relative to U-Net. In processing images, the speed of IU-Net is improved by 76.92% relative to U-Net. compared to mainstream segmentation models, IU-Net achieves better segmentation results and effectively improves the segmentation accuracy of small mechanical parts. In the grasping test, IU-Net-MBR achieves 100% and 96.67% in recognition rate and grasping rate, respectively.
Measurement method of arc dimension of slide section based on machine vision
LV Qinghai, WANG Zhongren, ZHOU Shuming, KE Xilin, LIU Haisheng, YAN Ming
2024, (2): 99-104.   doi: 10.19287/j.mtmt.1005-2402.2024.02.014
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In order to solve the problems of low efficiency and poor consistency in manual detection of the arc dimension of the slide section of car seat, a measuring method based on the combination of caliper edge detection and Tukey algorithm was proposed, which realized the detection of the arc dimension of the slide section with high efficiency and high precision. First, the collected images were processed by bilateral filtering to remove the noise in the images, and a emphasize operator in the HALCON algorithm library was used to process the images and highlight the edge information of the images. Then the arc edge points were extracted by caliper edge detection algorithm. Finally, the outliers were separated by the least square method of weighted Tukey and the circle fitting was completed. The experimental results showed that this method could realize the rapid detection of the arc dimension of the slide section, and the measuring system had a good stability and high reliability. The measuring errors were all within 0.08 mm, and the repeated measurement accuracy could reach 0.02 mm.
Design and Research
Research on synchronous error compensation method of internal mesh powerful honing based on electronic gear box
KONG Jian, HAN Jiang, XIA Lian
2024, (2): 105-110, 121.   doi: 10.19287/j.mtmt.1005-2402.2024.02.015
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As a special multi-axis linkage control technology, the electronic gear box is the control core in the CNC system of the gear spreading machine tool, and its synchronization control accuracy determines the gear machining accuracy. As an important gear precision machining process, the development machining accuracy of internal meshing power honing is largely determined by the control accuracy of the electronic gear box. Combined with the kinematics model of power honing, the paper establishes the electronic gearbox model of internal mesh power honing. The relative difference of tracking error of each motion axis of power honing is defined as synchronization error, and mapped to tooth pitch deviation, tooth profile deviation and helix deviation. A synchronization error compensation control method based on the electronic gear box is proposed, and a synchronization compensation control model is established.The motion control experiments of internal meshing power honing are carried out on the dSPACE semi-physical multi-axis motion simulation platform. The experimental results show that the proposed synchronization error compensation method based on electronic gear box can effectively reduce the synchronization error of internal mesh power honing.
Wear simulation of diamond cutting tools based on lamellar aluminium film
ZHANG Baoqing, MA Qun, AN Yangjie, JIRI Galantu, SHI Guangfeng, WU Tiehua
2024, (2): 111-116.   doi: 10.19287/j.mtmt.1005-2402.2024.02.016
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Mastering the tool wear mechanism is the key to the stable preparation of large area gratings. Aluminum film with layered structure determined by plating process is the first choice of film blank for machine gratings. In order to obtain the rule of the effect of the middle layer aluminum film on the wear of diamond cutting tools during the grating mechanical marking process, the mechanical properties of the layer aluminum film and the rule of tool marking wear were tested for the first time. The hardness and elastic modulus of the layer aluminum film were measured by the nanoindentation experiment, which were 0.48 GPa and 65.2 GPa respectively, meeting the Hall-Petch strengthening theory. Therefore, Deform 3D finite element analysis software was used for the first time to establish a layered layered aluminum film model, and the engraving depth was set at the aluminum film layer interface. It was found that the layered film interface had a significant effect on its stress transfer after the engraving depth of 2 μm and 4 μm for single-layer and 4-layer aluminum films. The barrier effect of the interface on stress transfer disappears; The tool wear pattern and wear position are roughly the same when cutting single and 4 layers of aluminum film, but the tool wear is small when cutting 4 layers of aluminum film, which is consistent with the results of subsequent machine cutting test.
Deformation analysis and compensation of gantry machining center beam guideway surface
CHEN Yi, GUAN Kaicheng, MA Yongwang, ZHANG Yang, LIU Liying, LIU Xingzhuo
2024, (2): 117-121.   doi: 10.19287/j.mtmt.1005-2402.2024.02.017
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The multi-source factors such as the weight of the beam and the weight of other functional components together cause the Z-direction depression and torsional deformation of the beam guideway Surface,it will leads to the distortion of the accuracy of the guideway surface and affects the Y-direction comprehensive straightness of the beam of the gantry machining center. In order to eliminate the influence of unfavorable factors on the surface of the guide rail, based on the finite element analysis method, this novel focuses on the upper and lower guideway Surfaces of the beam.Then the simulation analysis test scheme was established and the deformation at different positions were solved. According to the whole deformation curve drawn by the fitting, the deformation of the guide rail Surface was repaired and compensated. The actual measurement results show that: The Y -direction comprehensive straightness accuracy of the crossbeam of the gantry machining center is effectively improved after compensation.
Prediction of free bending forming result of TP2 pipe based on POA-BP
HAO Yongxing, ZHANG Xuhao, LIU Yahui
2024, (2): 122-128.   doi: 10.19287/j.mtmt.1005-2402.2024.02.018
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The wall thickness thinning rate and ellipticity are selected as evaluation criteria for the free bending forming results of the pipe. The influencing factors include the gap between the bending die and the pipe, the radius of the corner of the bending die, the length of the bending deformation zone of the pipe, the radius of the corner of the guide mechanism, and the gap between the guide mechanism and the pipe. A sample library for the evaluation criteria and influencing factors of free bending of pipes is established using numerical simulation method. Six random groups are selected as test samples, while the remaining samples are used for training. The POA-BP neural network prediction model is constructed by combining the BP neural network and the Pelican optimization algorithm to predict the free bending forming results of pipes. The results show that the maximum prediction error of the wall thickness reduction rate and ellipticity of the POA-BP prediction model does not exceed 2%. Therefore, the POA-BP prediction model can effectively predict the pipe forming results.
Technology and Manufacture
Finite element analysis of outlet burr for grinding nickel-based superalloy
HUANG Wenke, ZENG Xin, ZHOU Sheng
2024, (2): 129-135.   doi: 10.19287/j.mtmt.1005-2402.2024.02.019
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To reveal the formation mechanism of outlet burr during the grinding process of nickel-based superalloy, a two-dimensional finite element model of high-speed grinding of Inconel718 alloy with a single PCBN particle was established, and the feasibility of the model was verified. DEFORM-2D was used to study the outlet burr formation process, which was divided into eight periods. And the effects of grinding speed, grinding depth, abrasive particle cone angle and edge radius on the burr were analyzed by orthogonal experiment. The results show that the size of outlet burr is mainly composed of burr width and height, which are sensitive to the grinding depth. The greater the grinding depth, the greater the burr width and height. In addition, with the increase of grinding speed, abrasive particle cone angle and edge radius, the burr width also increases, but the burr height is insensitive to these three parameters.
Effect of process parameters on milling force and milling temperature of 30CrMnSiA high-strength steel
QI Ming, ZHANG Jian, HUANG Wentao, WANG Qijia, ZHENG Yaohui, WANG Lian
2024, (2): 136-141.   doi: 10.19287/j.mtmt.1005-2402.2024.02.020
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30CrMnSiA high-strength steel has high strength, good wear resistance, fatigue resistance, and impact resistance, and is widely used in aerospace and other fields. In order to study the influence of process parameters on milling force and milling temperature of 30CrMnSiA high strength steel, the orthogonal test method was used to carry out milling test. The range analysis, variance analysis and finite element simulation were used to study the milling force and milling temperature, and the empirical formula of milling force was obtained through multivariate regression analysis. The results show that the feed rate has a significant impact on milling force, while the milling width, milling depth, and spindle speed have a smaller impact. Moreover, each milling parameter mainly affects the milling force in the X direction, and has a smaller impact on the Y and Z directions; The degree of influence of milling parameters on milling temperature is as follows: milling depth>milling width>spindle speed>feed speed.
Research on machining method of cylindrical gear with micro-drum tooth
JIANG Kaijia, SONG Aiping, HUANG Jiaming, CHEN Zhongquan, ZHOU Qiangqiang
2024, (2): 142-146.   doi: 10.19287/j.mtmt.1005-2402.2024.02.021
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Based on the study of the existing grinding technology, a new grinding process which can realize tooth profile modification is put forward. The gear tooth surface is grinded by an inclined cubic boron carbide grinding disc. Based on Vericut machining simulation verification, this grinding method can realize gear tooth profile modification and full tooth width grinding. The contact analysis of the tooth surface of the gear pair is carried out by using the simulated gear, and it is found that the contact interval is mainly distributed in the middle part of the tooth surface, which can effectively reduce the meshing partial load of the gear pair and improve the stationarity of the gear transmission. According to the geometric position relationship between the grinding track of the grinding disc and the circular cutting plane of the machined gear section, the drum shape control adjustment model is constructed, and it is concluded that the drum shape can be controlled by the installation angle of the cubic boron carbide grinding disc, which can ensure the accuracy and stability of the tooth modification.
Test and Quality
Research on optimization of temperature measurement points for linear feed axis of CNC machine tools
CUI Zhanhua, YANG Heran, SUN Xingwei, ZHAO Hongxun, MU Shibo, ZHANG Weifeng
2024, (2): 147-151.   doi: 10.19287/j.mtmt.1005-2402.2024.02.022
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To analyze the temperature field of the linear feed system of CNC machine tools, it is necessary to arrange a certain number of temperature measurement points for temperature data collection. However, the research results will be directly affected by the location and number of measurement points. To achieve accurate placement of temperature measurement points, an improved Canopy FCM-GRA temperature measurement point optimization model based on statistical theory is proposed in this paper. Taking the X-axis linear feed axis of a certain CNC machine tool as an example, the pre clustering number is first determined based on the measured experimental data, and then the corresponding temperature sensitive points are selected through fuzzy matrix and grey correlation coefficient. Finally, based on SVR theory, temperature thermal error prediction models are established before and after temperature measurement point optimization. The effectiveness of temperature measurement point optimization is verified by comparing the accuracy of the two models. The results show that the optimization effect of temperature measurement points is good, and the optimized temperature measurement points can accurately explore the thermal characteristics of the feed system.
Full-angle bolt loosening detection method based on anti-loosening lines segmentation
KANG Jingjie
2024, (2): 152-158.   doi: 10.19287/j.mtmt.1005-2402.2024.02.023
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In response to the existing challenge of full-angle bolt loosening detection based on anti-loosening lines segmentation, a method based on color segmentation and directional vector operations is developed. Firstly, the anti-loosening line image is segmented using a method based on the nonlinear stretching of the 'a' component under Lab and RGB color space conversion, and the optimal threshold segmentation of the 'R' component. Secondly, morphological operations are performed on the image using an opening operation. Thirdly, the direction vector of the minimum external rectangle of the anti-loosening line connected domain is determined through an angle-progressive minimum enclosing method. Then, the full-angle of bolt loosening is solved based on the four-quadrant inverse tangent function and certain adjustments. Finally, an experimental scheme is designed to verify the feasibility and accuracy of the algorithm proposed in this paper. Experimental results show that the detection algorithm can realize 0 to 360 degree bolt loosening angle detection, with a maximum relative error of 1.43%. The accuracy of the method is satisfactory for engineering practice, demonstrating promising application prospects.
Technical scheme for improving the development accuracy of heavy-duty gas turbine compressor cylinder
XIE Longfei
2024, (2): 159-163.   doi: 10.19287/j.mtmt.1005-2402.2024.02.024
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In view of the current development problems of the introduced heavy-duty gas turbine compressor cylinder, such as poor positioning effect of the positioning structure of the surface flange, large processing deformation, unstable processing accuracy, and difficulty in ensuring assembly accuracy, the optimization of the positioning structure of the surface flange and the improvement of the manufacturing process were proposed to improve the design quality and ensure the manufacturing accuracy.
Function Units
Effect of micro-textures on the friction and wear characteristics of V-shaped sliding guideways
MA Kexin, DENG Jianxin, BAO Yichen, WANG Junyan, TIAN Runzhou, WANG Mingyuan
2024, (2): 164-171.   doi: 10.19287/j.mtmt.1005-2402.2024.02.025
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V-shaped sliding guideways are still used in many mechanical equipments due to their advantages of low cost, good load-bearing capacity, and good guidance. However, the guideways also have disadvantages such as high friction coefficient, high wear rate, and poor low-speed stability. To enhance the tribological performance of V-shaped sliding guideways, laser surface texturing technology was used to design and prepare linear and elliptical micro-textures on the contact surfaces of the guideways. Through different simulation software, it was verified that micro-textures can generate hydrodynamic action, and the influence of micro-textures on the contact stress of the guideway contact surface was analyzed. The friction and wear properties of different types of textured guideways were tested by a self-made reciprocating sliding guideway test platform under mixed lubrication condition. The results indicate that textured guideways can generate hydrodynamic action, and elliptical micro-textures can generate larger hydrodynamic action. In addition, the elliptical micro-textures located only on the surface of the lower guideway can significantly reduce its contact stress. Therefore, when the elliptical micro-textures are located on the surface of the lower guideway, the friction reduction effect is the best, with the lowest average friction coefficient, which is reduced by 31.7% compared to the guideways without textures.
Unsupervised domain-adaptive bearing fault diagnosis method based on simulation data
CHEN Junyang, YUAN Yiping, CHEN Caifeng
2024, (2): 172-178.   doi: 10.19287/j.mtmt.1005-2402.2024.02.026
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Aiming at the current problem that it is difficult to obtain effective rolling bearing fault data in practical diagnostic tasks and the poor generalization ability of the current diagnostic model, a fault diagnosis method based on dynamics simulation and unsupervised domain adaptation is proposed. Firstly, a rolling bearing dynamics simulation model is established, and a large amount of simulation data is obtained to serve as the source domain. Then, an unsupervised domain-adaptive transfer learning fault diagnosis approach is used, which introduces an adversarial learning strategy that maximizes and minimizes classifier differences on basis of global domain adaptation to further reduce the conditional distribution differences between source and target domain features. Finally, the feasibility and excellence of the proposed method is verified by comparing it with other transfer learning methods.
Analysis and solution to rotary error of motorized spindle of high-precision tool grinder
2024, (2): 179-183.   doi: 10.19287/j.mtmt.1005-2402.2024.02.027
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This paper aims to solve the problem of abnormal rotation error that occurred in a domestic brand motorized spindle. The abnormal rotation error of the motorized spindle is caused by the gas seal failing to play a good sealing effect, which causes the front bearing and disc spring polluted by grinding oil, thus resulting in the failure of the front bearing, the worn of the spindle shaft and the decay of broaching force. By improving gas seal pressure, the material of the spindle shaft, and the structure of the broach, the service life of a motoried spindle is increased by more than 100%.
2024, (2): 184-184.  
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