制造技术与机床

Spatial error modeling and sensitivity analysis of ultra-precision micro-compound turn-milling machine tool

ZHENG Zhongpeng, JIN Xin, GUO Jiajing, GAO Ruilin, JING Hao, LI Erbo

2022, (6): 5-10. doi: 10.19287/j.mtmt.1005-2402.2022.06.001

[Abstract] FullText HTML PDF(2049KB)

Abstract:
The micro-compound turn-milling machine tool can complete most parts processing processes in one clamping process. It is an indispensable CNC equipment for processing micro complex structural parts. As a precision machining CNC equipment, its own spatial geometric error directly affects the machining accuracy of parts. The ultra-precision micro-compound turn-milling machine tool CXKG25-I developed by Beijing Institute of Technology was used as the research object in this paper. First, the spatial geometric error elements of the ultra-precision turn-milling compound machine tool were analyzed, and the 57 spatial geometric errors were obtained. The spatial geometric error model was established based on the multi-body system theory method. Then, the sensitivity analysis of the spatial geometric error project was carried out, and the key sensitive factors of machining errors were revealed. These analysis results guide and optimize the structural design and manufacturing of ultra-precision turn-milling machine tool.

Hydrodynamic effect polishing characteristics of ultra-smooth surfaces of optical components

FU Zhenfeng, WANG Zhenzhong, WANG Biao, SHEN Bingyi, HUANG Xuepeng

2022, (6): 11-17. doi: 10.19287/j.mtmt.1005-2402.2022.06.002

[Abstract] FullText HTML PDF(2249KB)

Abstract:
Hydrodynamic effect polishing can achieve non-contact micro removal based on fluid shear effect, and can obtain ultra-smooth surface with roughness below 1 nm, which has good application prospects in the field of advanced optical and microelectronic material processing. In this paper, the fluid-driven polishing ball is designed based on the sphere elastic emission processing method, and the fluid velocity as well as the pressure and shear force distribution on the surface of the workpiece are analyzed by the simulation of the flow field in the polishing area with Fluent software.Three parameters, such as polishing gap, tool ball diameter and spindle speed, were used to investigate the laws of their effects on the maximum pressure and shear force applied to the workpiece surface. A single-factor polishing test was designed for parameter optimization, and a small-diameter (20 mm × 20 mm) polishing test was carried out, and the results of workpiece surface roughness RMS decreased from 16.939 nm to 2.467 nm, and the preliminary experiments showed the feasibility of this processing method in the application of optical components.

Cross-experimental study on the influence mechanism of the secondary section of the polished ribbon on the pressure field creation

YANG Hang, GU Jianhua, HUANG Wen, HE Jianguo

2022, (6): 18-24. doi: 10.19287/j.mtmt.1005-2402.2022.06.003

[Abstract] FullText HTML PDF(1521KB)

Abstract:
The secondary cross-section geometry and embedding depth of magnetorheological polishing ribbons are important factors that affect the pressure field during magnetorheological polishing. Three experimental models of plane, spherical and convex are established, and cross-combination experiments are carried out on the embedding depth and shape of the experimental section. The effects of different shapes of quadratic cross-sections on the creation of the pressure field of magnetorheological polishing are compared. The influence of the embedding depth on the creation of the pressure field strength of the polished ribbon and the effect of the removal efficiency of the polished ribbon are explored. The experimental results show that the overall pressure value of the convex quadratic section under different embedding depths is the largest among the three models.In the planar quadratic section, the embedding depth is positively correlated with the level of the pressure field. In the spherical quadratic section in the model, with the continuous change of the embedding depth of the spherical quadratic cross-section, the pressure value presents a concentrated distribution phenomenon. Only a few areas are existed where the pressure value deviates from the pressure value concentrated distribution area, and the pressure value concentrated distribution area is 5.57~8.24 MPa.In the convex quadratic section model, the embedding depth of the convex quadratic section is also positively correlated with the overall pressure value.

Analysis of key factors of extrusion speed of FDM-3D printing melt

WANG Jun, YANG Bo, REN Qiancheng, JIANG Rongjun

2022, (6): 25-30. doi: 10.19287/j.mtmt.1005-2402.2022.06.004

[Abstract] FullText HTML PDF(1488KB)

Abstract:
Aiming at the nozzle blockage and model drawing phenomenon caused by the disproportion of the melt extrusion speed and the nozzle scanning speed during the FDM molding process, the orthogonal test method and the ANSYS Fluent software are used to analyze the flow channel structure parameters and different printing in the nozzle carry out simulation calculation under parameter conditions, and carry out range analysis and single factor test result analysis to the orthogonal test results. The results show that the biggest factor affecting the melt extrusion speed is the wire feeding speed, followed by the nozzle inner diameter, and the smallest is the convergence angle, the length of the exit section and the printing temperature. The wire feeding speed is 60 mm/s, the nozzle inner diameter is 0.4mm, and the printing temperature is proposed. 210 °C, the length of the discharging section L=1.5 mm, and the convergence angle of 150° is the optimal process plan. Finally, an exponential prediction model between melt extrusion speed and influencing factors was established and the accuracy of the model was verified.

Design of multi-color switching modules based on fused deposition molding 3D printers

WANG Yonggang, WU Xuecheng, GAO Wenjie, ZHI Shanjie, HUANG Shuangjun, GAO Tai

2022, (6): 31-36. doi: 10.19287/j.mtmt.1005-2402.2022.06.005

[Abstract] FullText HTML PDF(2493KB)

Abstract:
Currently, most of the traditional fused deposition molding (FDM) 3D printers can only print monochromatic or dual-color models. To achieve rapid prototyping of multi-color models of 3D objects, a multi-color switching modules that can be installed in any dual sprinkler 3D printer is designed via deeply study the mechanical structures and control logic of traditional FDM 3D printers in this paper. Actual multi-color printing tests show that the multi-color switching module fabricated based on design schemes can accurately and stably complete the rapid prototyping of the multi-color model 3D objects. Experiments show that the printing quality of the products is better under the printing temperature of 180 ℃ and the printing speed of 200 mm/s. This work provides new ideas for FDM multi-color 3D printing.

Design and research on control system of laser melting metal additive manufacturing equipment

HUNAG Kaijun, LIU Yuwen, WEN Shanshan, LI Peng, ZHU Yaqi, KUANG Tingyu, ZHANG Chunjie

2022, (6): 37-43. doi: 10.19287/j.mtmt.1005-2402.2022.06.006

[Abstract] FullText HTML PDF(1952KB)

Abstract:
This article aims at the design of the control system of laser melting metal additive manufacturing equipment in selected areas, and strives to improve the stability and reliability of the operation of metal additive manufacturing equipment. By optimizing the control system architecture and designing a structured communication protocol, we designed a SLM metal additive manufacturing equipment control system based on the QT+PLC+RTC platform. And focusing on the coordination and control of peripheral equipment, such as lasers, galvanometers, and motor controllers, we had implemented a highly reliable control system for the metal additive manufacturing equipment with following features, self-controllable in the complete printing process, multi-threaded and coordinated, with a set of friendly human-computer interfaces.

Gearbox fault diagnosis based on LMD energy entropy and support vector machine

XU Le, ZHU Yubin, LANG Chaonan

2022, (6): 44-49. doi: 10.19287/j.mtmt.1005-2402.2022.06.007

[Abstract] FullText HTML PDF(1653KB)

Abstract:
Aiming at the problem that it is difficult to extract and classify multiple fault features of gearbox in the case of small samples, a fault diagnosis method based on local mean decomposition (LMD) energy entropy and support vector machine (SVM) is proposed. Firstly, the collected gearbox vibration signal is decomposed by LMD method to obtain finite pf components; Then, according to the uneven distribution of gearbox vibration signals in frequency domain under different faults, the dispersion of PF component energy in different frequency domain is analyzed, that is, the LMD energy entropy is calculated; Finally, SVM multi fault classifier is used to train and test the extracted features for gearbox fault classification. The experimental results show that even in the case of small samples and non single and multiple gearbox faults at the same time, the feature extraction and accurate classification of gearbox faults can be realized based on LMD energy entropy and SVM.

Bearing fault diagnosis method based on MRE and EigenClass

LI Fuguo, WANG Junyuan, WU Zengrong, LIN Bingqian, LV Pinde, FAN Ruitian

2022, (6): 50-54. doi: 10.19287/j.mtmt.1005-2402.2022.06.008

[Abstract] FullText HTML PDF(1293KB)

Abstract:
Aiming to extract the faint vibration signal from rolling bearing and classify extracted fault features, the paper fuses together multiscale range entropy (MRE) with EigenClas, and proposes a MRE-EigenClass method to diagnose bearing fault modes. Firstly, the MRE extracts the feature vectors with 20 scales from the vibration signals of bearings in different working states. Then, the extracted feature vectors are input into EigenClass classifier to obtain the final results. The experiments show that the proposed MRE-EigenClass algorithm can effectively extract the features of vibration signals and realize high-precision classification for rolling bearings. Compared with other fault classifiers, this method has the higher fault classification accuracy(98.86%).

Study on the effect of electrode materials on the performance of short electric arc-electrochemical compound machining stainless steel

ZHANG Ru, HU Guoyu, ZHOU Jianping, ZHANG Shengsheng, DAI Xiangyu

2022, (6): 55-61. doi: 10.19287/j.mtmt.1005-2402.2022.06.009

[Abstract] FullText HTML PDF(1700KB)

Abstract:
Short electric arc-electrochemical compound machining (SEACM) is a new type of composite machining, which uses short arc discharge for material removal and the bottom gap electrochemical action for surface finishing. Different electrode materials have different material characteristics, which will directly affect machining performance, workpiece surface quality, electrode loss and dimensional accuracy of composite machining. This article uses the aluminum, graphite, stainless steel, red copper as electrode material, to explore the influence of different electrodes on 304 stainless steel in short electric arc-electrochemical compound machining mode, from the material removal rate (MRR), relative tool electrode wear ratio (RTWR), the surface roughness (SA), surface macroscopic and microscopic morphology, etc. The results show that the red copper electrode has higher material removal rate, lower relative tool electrode wear ratio, better surface quality and thinner recasting layer, so it is more suitable for composite machining electrode material, which provides a theoretical basis for the subsequent selection of electrode materials in short electric arc-electrochemical compound machining mode.

Surface texture laser processing on 304 stainless steel with liquid-phase assisted method

ZHAI Shuaijie, FENG Qigao, ZHANG Qiuchen, PANG Minghua, MA Lijie

2022, (6): 62-68. doi: 10.19287/j.mtmt.1005-2402.2022.06.010

[Abstract] FullText HTML PDF(3180KB)

Abstract:
To improve the oxidation and melt bonding phenomenon and obtain a particular surface texture with better wetting and tribological properties on 304 stainless steel, the liquid-phase assisted laser processing method was introduced. The 304 stainless steel samples were placed in the air and the mixed liquids of anhydrous ethanol and hydrogen peroxide (volume ratio is 50∶1) respectively. The cross-interference laser scanning processing was carried out. Then, the oxidation, surface morphology, and wettability characteristics of test sample surface were evaluating with white light interferometer, scanning electron microscope, energy spectrum, and contact angle measuring instrument. The oxygen content on the sample surface with laser processing in air is increased by 41.5%, and the phenomenon of processed melt bonding is clearly observed. With liquid assisted laser processing condition, the oxygen content on the sample surface is reduced by 19.4%, and the phenomenon of processed melt bonding is eliminated. It is indicated that the oxidation and processed melt bonding phenomenon on the sample surface are improved under liquid assisted condition. In addition, one dimensional properties of surface topography is obviously observed for air laser processing condition. For liquid assisted laser processing method, the situation is completely different. In this case, the assisted liquid on the solid-liquid interface is rapidly vaporized and a lot of bubbles are formed due to the function of laser beam. Thus, dispersive and negative pressure impact action are existed simultaneously with laser beam and solid-liquid material respectively. A three dimensional surface topography with spray characteristics is formed, which have a better wetting and tribological properties. The liquid assisted laser processing technology can improve the surface manufacture quality of 304 stainless steel, and a better performance three-dimensional surface morphology is obtained.

Experimental study on pulse laser cutting 46MnVS5 connecting rod cracking groove

ZHANG Chuanyou, WANG Guan, LIU Zanfeng, ZHANG Yawen

2022, (6): 69-73. doi: 10.19287/j.mtmt.1005-2402.2022.06.011

[Abstract] FullText HTML PDF(1975KB)

Abstract:
In this paper, the influence of different pulse fiber laser processing parameters (pulse power, pulse frequency, pulse width and cutting speed) on the geometry of 46MnVS5 cracking groove of a new expanded connecting rod material is analyzed and summarized. The results show that with the increase of pulse power, pulse frequency and pulse width, the depth and width of cracking tank increase in varying degrees. Among them, the pulse power has a great influence on the opening angle, but the change of pulse frequency and pulse width on the opening angle is not obvious; The groove depth and width decrease with the increase of cutting speed, and the opening angle changes in a certain size range. When the processed groove depth is between 450~700 μm and the groove width is between 150~200 μm, the opening angle changes in the range of 15°~20°, which can meet the processing requirements.

Analysis and validation of grinding force in TC4 titanium alloy surface grinding

WANG Xiaosong, HU Hui, ZHANG Xiaomin, LIU Xin

2022, (6): 74-79. doi: 10.19287/j.mtmt.1005-2402.2022.06.012

[Abstract] FullText HTML PDF(1291KB)

Abstract:
Grinding force has important influence on grinding temperature and grinding wheel wear, and is a key index to evaluate TC4 titanium alloy grinding performance. Due to the size and shape differences and randomness of distribution of grains of wheel, it is difficult to describe the grinding process quantitatively. The derivation of existing grinding force models is based on certain assumptions, which is deviated from the practice. Therefore, the derivation of existing grinding force models is based on certain assumptions, which is deviated from the practice. In this paper, a single abrasive grinding force model is established based on the relationship between chip deformation force and the cross-sectional area of the abrasive and the relationship between normal pressure and the pressing depth. Based on the cross-sectional area of the chip and the volume removal rate of the workpiece, the relation between the grinding force of single grain and the grinding force of unit width was established and then the grinding force model of TC4 titanium alloy was deduced. Combined with the experimental data, the analytical formula of grinding force under the experimental conditions was obtained. The analysis shows that the average relative error of normal grinding force is 4.9%, and that of tangential grinding force is 5.1%.

Simulation study of influence of cutting parameters on cutting force of 316H stainless steel

WANG Lin, JIANG Zenghui, WANG Shuli, ZHANG Wenjie

2022, (6): 80-83. doi: 10.19287/j.mtmt.1005-2402.2022.06.013

[Abstract] FullText HTML PDF(1255KB)

Abstract:
316H stainless steel is difficult to machine due to its low thermal conductivity, high strength, high ductility and high work hardening properties. In order to explore the influence of three cutting factors on cutting force, a simulation model of turning 316H stainless steel was established and studied by orthogonal simulation experiment. The range analysis method and variance analysis method are used to analyze, and finally the different cutting parameters that affect the primary and secondary order of cutting forces are obtained, and the most reasonable cutting parameters under the minimum cutting force are given.

Evaluation system of machine tool technology gap in China based on fuzzy data processing

SU Zheng, LI Li, Xu Jingjing, LIU Bingye, LIU Zhifeng, YANG Congbin

2022, (6): 84-91. doi: 10.19287/j.mtmt.1005-2402.2022.06.014

[Abstract] FullText HTML PDF(2039KB)

Abstract:
For a long time, the technology gap of key products in equipment manufacturing industry represented by CNC machine tools is lack of quantitative measurement research, which makes it impossible to use objective characterization methods to measure and evaluate the technical development level of NC machine tools. In view of the above problems, an evaluation system for the technical gap of high-end CNC machine tools is constructed, starting from the four directions of common technology, typical host products, CNC system and key functional components, which are subdivided into the technical element items. A quantitative characterization method of the age gap between China's machine tool technology level and the International (regional) advanced level, is proposed. Evaluation models for the sub item technology level, common technology/product level evaluation model and product key technology are established based on fuzzy data processing. Finally, a large sample data survey is carried out based on the system, and a quantitative analysis of the age gap of machine tool technology is carried out based on the proposed evaluation models. Evaluation results can provide the important support for the government′s scientific decision-making and industry development planning.

Tool axis trajectory planning for flank milling based on SA-PSO hybrid algorithm

HAN Jun, YAO Sheng

2022, (6): 92-99. doi: 10.19287/j.mtmt.1005-2402.2022.06.015

[Abstract] FullText HTML PDF(2251KB)

Abstract:
Aiming at the problem of principle error of non-developable ruled surface, the error determination function of single tool axis position is proposed as the objective function, that is, the distance from each point on a single tool axis to the non-developable straight surface minus the square of the tool axis radius is minimum. In MATLAB, the SA-PSO (simulated annealing algorithm and particle swarm optimization) hybrid algorithm is used to solve it. The hybrid algorithm solves the problem of finding the optimal position of tool axis in the case of single tool position. By comparing the envelope errors of PSO algorithm and SA-PSO algorithm, it is shown that the undercutting and overcutting errors of SA-PSO hybrid algorithm are 14.7% less than the single particle swarm optimization algorithm. The feasibility of the method is verified by actual machining and surface error detection of blade finishing.

Research on accurate modeling method of bearing joint based on sub region virtual material method

CHEN Yongjiang, TANG Wencheng, GUO Hun, HUA Hongliang

2022, (6): 100-107. doi: 10.19287/j.mtmt.1005-2402.2022.06.016

[Abstract] FullText HTML PDF(2046KB)

Abstract:
Aiming at the problem that the uneven distribution of contact stress between the rolling element and the raceway is not considered in the virtual material model of rolling contact movable joint, a method of virtual material joint modeling in different regions is proposed. Taking the ball bearing as an example, the theoretical model of ball bearing which can be used to analyze the contact stress distribution at different ball phase angles is established, then based on the contact stress distribution characteristics of the ball and raceway obtained by this model, the non-uniform contact characteristics are equivalently represented by the zonal virtual material joint model. Finally, the virtual material model of the ball bearing joint considering the non-uniform contact is established. The experimental platform of headstock with different sizes of ball bearings is built, and the effectiveness of this modeling method is verified by experiments. The results show that the virtual material joint modeling method is an effective method to characterize the uneven distribution of contact stress between ball and raceway.

Thermodynamic analysis and research on laser cleaning of corrosion layer of steel plate

ZHANG Zhong, SUN Xingwei, YANG Heran, DONG Zhixu, LIU Yin

2022, (6): 108-112. doi: 10.19287/j.mtmt.1005-2402.2022.06.017

[Abstract] FullText HTML PDF(1542KB)

Abstract:
In order to explore the mechanism of laser cleaning and removal of rust layer on steel surface. Based on the heat conduction equation, a mathematical model of the surface temperature rise of the steel corrosion layer is established, and the laser power density for removing the corrosion layer is obtained. The error of the laser power density and the known experimental results is about 2%. On this basis, the finite element software is used to analyze the temperature field and thermo-mechanical coupling of the cleaning area, and the temperature distribution characteristics of the rust layer and the substrate are obtained. The analysis shows that when the calculated threshold is used for cleaning, a certain thickness of the rust layer can be removed. At the same time, the substrate temperature is lower than the melting point of the steel, and the surface is not damaged. In addition, the elastic deformation caused by thermal-mechanical coupling facilitates the separation of the rust layer from the steel substrate. The mathematical model of surface temperature rise and the results of thermodynamic analysis presented in this paper can provide theoretical guidance for laser cleaning of the rust layer on the steel surface.

Research on RBF-PID self-learning control of magnetic levitation linear synchronous motor drive system of motion platform

PENG Jingqi, LAN Yipeng

2022, (6): 113-118. doi: 10.19287/j.mtmt.1005-2402.2022.06.018

[Abstract] FullText HTML PDF(2094KB)

Abstract:
Aiming at the non-linearity, coupling and uncertainty of external disturbance in the magnetic levitation linear synchronous motor drive system of the moving platform, a RBF neural network PID self-learning controller is proposed. Firstly, the structure and operating mechanism of the magnetic levitation linear synchronous motor are introduced in detail; the mathematical model of the magnetic levitation linear synchronous motor is established, and the expressions of the voltage equation, flux linkage equation, horizontal thrust equation and horizontal motion equation are derived; a design based on The PID self-learning controller of RBF neural network. In the RBF neural network, the gradient method is generally used to adjust the parameters w、b、c. In order to effectively shorten the learning time of the network and reduce the oscillation of the system, the paper is in the RBF neural network. The momentum factor item is introduced in, and the control system is simulated through MATLAB to verify that the RBF-PID self-learning algorithm has better stability and anti-disturbance than the PI controller.

Design and static dynamic characteristics analysis of small five-axis engraving machine

LIU Bin, LI Wei, WANG Jun, GUO Zhiwei, WEI Xinyu, WANG Taiheng

2022, (6): 119-128. doi: 10.19287/j.mtmt.1005-2402.2022.06.019

[Abstract] FullText HTML PDF(3822KB)

Abstract:
UG was used to design and model the structure of the five-axis engraving machine, and analyze the static and dynamic characteristics of the model, it is to ensure that the mechanical structure of the designed small five-axis engraving machine can meet its mechanical characteristics. To begin with, UG was employed to calculate the static characteristics of the guide rail under different loads and different restraint conditions. In addition, UG was applied to analyze the static characteristics of the frame structure. Finally, UG technology was used for modal analysis and harmonious response analysis of the entire engraving machine. The analysis results show that the maximum displacement and deformation of the guide rail is 1.838×10^–6 mm, and the maximum stress is 1.034 MPa, which meets the design requirements. Resonance occurs when the excitation force frequency of the engraving machine is close to the two natural frequencies of 900 Hz and 1950 Hz, but the actual working frequency of the engraving machine is between 0 and 400 Hz, so resonance will not occur. From the analysis, prototype experiment and comparison results that it is concluded that the five-axis engraving machine has good static rigidity, which has reached the design requirements and is better than other engraving machines. This analysis provides a theoretical basis for the optimal design of the five-axis engraving machine structure.

Study on sensitivity of technical parameters of abrasive belt grinding of titanium alloy surface roughness

WU Ya, QIAO Hu, CAO Yan

2022, (6): 129-133. doi: 10.19287/j.mtmt.1005-2402.2022.06.020

[Abstract] FullText HTML PDF(963KB)

Abstract:
In order to obtain the optimal range of process parameters for abrasive belt grinding of titanium alloy surface roughness within a given range, titanium alloy TC4 was used as the research object to conduct abrasive belt grinding surface roughness tests. The empirical formula of grinding titanium alloy surface roughness was established, analyzed the sensitivity of the surface roughness to the process parameters, and obtained the stable and non-stable regions of the process parameters. Based on the range analysis of the orthogonal experiment, the influence curve of the process parameters on the surface roughness was obtained, and the interval optimization of the process parameters was carried out. The research results showed that the surface roughness is the most sensitive to changes in abrasive grain size, and the least sensitive to changes in abrasive belt linear velocity; the preferred range of abrasive grain size is 120#~150#, and the preferred range of abrasive belt linear velocity is 15~20 m/s, the preferable range of grinding pressure is 10~15 N. The theoretical method and experimental basis for the surface roughness control of titanium alloy grinding with abrasive belts are provided.

Process improvement and experimental research on increasing the parallelism of large and small holes in the connecting rod

HAN Yanlong, WANG Feng

2022, (6): 134-139. doi: 10.19287/j.mtmt.1005-2402.2022.06.021

[Abstract] FullText HTML PDF(1680KB)

Abstract:
The main factors that lead to the poor parallelism of the center line of the connecting rod large and small holes are obtained based on the process flow of the connecting rod of a reciprocating compressor. The finite element method is used to explore the optimal value of the clamping force of the fine boring process. Based on the mathematical statistics theory, the relationship between the drop of the positioning surface and the parallelism of the center line of the large and small holes in the fine boring process and the honing process has been experimentally studied. The results show that the optimal clamping force of the fine boring process is about 3.5 MPa. The positioning surface drop has a certain influence on the parallelism of the connecting rod size and hole in the fine boring process and the honing process, but the influence trend is not uniform, and the drop is 0 or close to 0, the parallelism of large and small holes is the best. The process improvement plan as follows. The clamping force of the fixture in the fine boring process is reduced from 4.5 MPa to 3.5 MPa. The fine boring process increases the positioning reference surface of the large end of the connecting rod by 25 μm, and the honing process increases the positioning reference surface of the small end of the connecting rod by 18μm. Use a floating honing fixture of the honing process . After continuous production verification for one year, the pass rate of parallelism of the center line of connecting rod large and small holes under the same production line process improvement program can be increased by about 1%.

Multi direction forging process and die design of hollow planetary carrier

LIU Le, YIN Yinyin, JIN Hong, GUAN Yue, ZHENG Penghui, WANG Zhihui

2022, (6): 140-146. doi: 10.19287/j.mtmt.1005-2402.2022.06.022

[Abstract] FullText HTML PDF(2188KB)

Abstract:
The planetary carrier is the most stressed part in the planetary reducer. It must have sufficient strength and stiffness to evenly distribute the planetary gear load and transmit all power to the shaft. At present, it is mostly produced by round bar turning and split welding, but its processing efficiency is low and the cost is high. It is very difficult to process the four square holes in the circumferential direction of the end. In this paper, a new hollow multidirectional forging process is proposed to improve the efficiency and reduce the cost. According to the structural characteristics of the planetary carrier, the hollow multidirectional forging process is formulated, the forming process is simulated and analyzed by DEFORM-3D, and the metal flow law, equivalent stress distribution and load-time curve are analyzed. Finally, the corresponding die structure is designed and the process test is carried out according to the simulation results. The results show that in the multi-directional split forming process of planetary carrier, the metal flow is relatively stable, the maximum load is 5.94 ×10⁶ N, the die is within the allowable stress range, the metal streamline is basically distributed along the contour of the part, and the forging size obtained from the process test meets the design requirements. It shows that the hollow multi-directional forging process and die structure of planetary gear carrier designed in this paper are feasible, which plays a certain guiding role in the mass production of this kind of parts.

Optimization of injection molding parameters of ECG recorder shell based on PSO-LSSVM and NSGA-Ⅱ

WANG Dezhao, FAN Xiying, LIU Xin, WANG Changjing, LI Chunxiao

2022, (6): 147-152. doi: 10.19287/j.mtmt.1005-2402.2022.06.023

[Abstract] FullText HTML PDF(2150KB)

Abstract:
Electrocardiogram (ECG) recorder is a precision medical equipment, but affected by the injection molding process, its shell is easy to warp and shrink in the injection molding process, which greatly shortens the service life. To solve this problem, a multi-objective optimization method of injection molding process parameters based on particle swarm optimization least squares support vector machine model (PSO-LSSVM) and improved non dominated sorting genetic algorithm (NSGA-Ⅱ) is proposed. Firstly, based on the samples obtained from orthogonal test, the prediction models of warpage and volume shrinkage are established by PSO-LSSVM algorithm, and then combined with NSGA-Ⅱ for global optimization. Through critical comprehensive analysis of the optimized Pareto optimal solution set, the optimal process parameters are finally obtained. At this time, the minimum warpage of plastic parts is 0.438 3mm, and the minimum volume shrinkage is 8.729%, which is 6.98% and 14.92% lower than that before optimization. At the same time, the injection molding test is carried out for the optimal process parameters. Through the measurement, it is found that the molding quality of plastic parts is good and meets the actual production requirements. The research of this paper provides a theoretical basis for further improving the quality defects of injection molded parts.

Research on reliability allocation optimization of CNC grinder based on improved particle swarm optimization

FAN Jinwei, LIU Huipu, ZHANG Lixiang, LI Weihua

2022, (6): 153-157. doi: 10.19287/j.mtmt.1005-2402.2022.06.024

[Abstract] FullText HTML PDF(1276KB)

Abstract:
In order to study the reliability allocation scheme with the lowest cost under the same reliability of NC grinder, an improved particle swarm optimization algorithm is proposed by combining the objective function and limited optimization conditions. Firstly, the basic theory of improved particle swarm optimization is introduced. Secondly, the reliability cost function model of CNC grinding machine is established by combining the generalized reliability cost function model. Thirdly, the reliability relationship between subsystems of CNC grinding machine is analyzed, and the non-linear programming model of reliability allocation is constructed. Finally, the improved particle swarm optimization method is used to solve the model, which is compared with genetic algorithm. The results show that under the condition of ensuring reliability, the improved particle swarm optimization algorithm is more reasonable. The research results have been fed back to the manufacturer and approved, which is of great significance to improve the reliability level of CNC grinder.

Optimization of free-form surface measurement path based on improved genetic algorithm

XU Chuanfa, WANG Shijun, WANG Ran, LI Jianhong, QI Na

2022, (6): 158-163. doi: 10.19287/j.mtmt.1005-2402.2022.06.025

[Abstract] FullText HTML PDF(1402KB)

Abstract:
In order to improve the detection efficiency of the CMM for free-form surface measurement points, in view of the slow convergence of traditional genetic algorithms and easy to fall into the local optimal solution, the adaptive adjustment mechanism is introduced, from the fitness distribution of the population and the individual adaptation. The two aspects of the degree value realize the adaptive parameter adjustment of the crossover and mutation probability, which improves the efficiency of the algorithm and reduces the probability of prematurity; the use of the greedy crossover operator and the greedy inversion mutation operator accelerates the convergence speed of the algorithm. The experimental results show that the improved genetic algorithm can optimize the free-form surface measurement path more efficiently and with high quality.

Sensitivity analysis of gear bending fatigue reliability based on parameter uncertainty

LI Mingkai, KANG Heming, LI Yongping, YANG Pu, CHEN Yu, YU Huan, DENG Hailong

2022, (6): 164-169. doi: 10.19287/j.mtmt.1005-2402.2022.06.026

[Abstract] FullText HTML PDF(1579KB)

Abstract:
The purpose of this paper is to study the reliability calculation and reliability sensitivity analysis of gear bending fatigue under uncertain parameters. Under the condition of stress ratio of 0.04, the S-N curve and P-S-N curve of gear under different reliability were established. Considering the uncertainty factors, Monte Carlo method was used to simulate the reliability of gear bending fatigue based on the stress-strength interference model, and the results were good. Combined with the reliability simulation results and the sensitivity calculation model, the mean sensitivity and variance sensitivity of each random parameter under different reliability after dimensionless removal were obtained. The results show that the positive and negative correlations of each mean sensitivity exist together and the influence is gentle under different reliability. In variance sensitivity, except for parameter Y_F, which is negative at all reliability degrees and has gentle influence, the other six parameters are positive at all reliability degrees and have severe influence.

Analysis and optimization of thermal deformation of heavy NC machine tool bed

XU Yanyan, XIA Ziqiu, CHEN Yi, ZHAO Ming

2022, (6): 170-175. doi: 10.19287/j.mtmt.1005-2402.2022.06.027

[Abstract] FullText HTML PDF(2175KB)

Abstract:
The model of the bed and foundation transient temperature was established by ANSYS, meanwhile the temperature data of machine tool bed's key points was obtained by the temperature acquisition device. Based on the measured data, the parameters of the finite element model was modified to make the simulated temperature distribution similar to the actual temperature distribution, which ensured the reliability of the simulation results. According to the thermal characteristics of the machine, three methods were offered to reduce the thermal deformation of the bed: changing the material of structural parts, optimizing the structure and adopting heat capacity balance technology. Conclusion can be drawn that, in terms of thermal stability, the artificial granite material has a certain improvement compared with the traditional cast iron material. And the straightness error of the bed caused by thermal deformation could be eliminated by 31.8% when using the artificial granite material.

Software development of measuring and controlling system for the rotation error of nano aerostatic bearing

QIAN Linhong, FENG Yanbing, ZHANG Xinjiang, LEI Dajiang, LAN He, CUI Hailong, ZHENG Yueqing

2022, (6): 176-180. doi: 10.19287/j.mtmt.1005-2402.2022.06.028

[Abstract] FullText HTML PDF(1538KB)

Abstract:
Based on the research of the tester applied to test the rotation error of nano aerostatic bearing, a software development of measuring and controlling system for the rotation error of nano aerostatic bearing is introduced in this paper. The software of the measurement and control system has been programmed mixed with C++ and MATLAB, which can realize the functions of motion control, data acquisition, data processing and result display. At the same time, an angle error control method is designed to reduce the angle error introduced in the process of data acquisition, so as to obtain a more accurate spindle rotation error. The program debugging result shows that, the software capability of the test system is rational, and is satisfied the testing accuracy and qualification of the spindle rotation error, the sampling angle error can be controlled within ± 0.01°, and the relative error between the roundness error of reference artefact(test ball) and the nominal value (36nm) is less than 6%.

Download CenterMore

LinksMore

2022 No. 6

Journal DynamicsMore

Top ViewMore