Table of Content

10 April 2023, Volume 34 Issue 07

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Research Progresses of Finishing Technology for Inner Channel of Additive Manufacturing Parts

WANG Lei, WU Yuliang, ZHAO Jiyuan, LU Bingheng,

2023, 34(07):  757-769.  DOI: 10.3969/j.issn.1004-132X.2023.07.001

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In the field of aerospace, metal additive manufacturing technology had broad application prospects in the formation of parts with complex inner channels. However, the finishing of additive manufacturing parts with complex inner channels was a bottleneck problem in industrial applications. The principle, technology and development of mechanical polishing, chemical and electrochemical polishing and electrolyte plasma polishing on inner channel were reviewed herein. In addition, the adaptability and exploration direction of mechanical polishing, chemical and electrochemical polishing and electrolyte plasma polishing for the finishing of inner channel of additive manufacturing parts were studied respectively. Finally, the development trend of the key technologies for the finishing of inner channel of additive manufacturing parts was put forward: ①the finishing technology research of the inner channel of the additive parts for functionally graded materials and polymetallic materials; ②the research on compound finishing technology for complex inner channel with complex geometry, bifurcation, gradual capillary structure, topology and so on; ③the research on high-precision detection method for the finishing quality of inner channel and the three-dimensional reconstruction technology of geometric errors.

Cutting Performance of Microwave-sintered Complex-shaped SiAlON Ceramic Cutting Tools in Milling GH4169 Superalloys

HONG Dongbo, YIN Zengbin, CHEN Weiyou, ZHENG Yitong, YUAN Juntang

2023, 34(07):  770-779，788.  DOI: 10.3969/j.issn.1004-132X.2023.07.002

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In view of the drawbacks of current ceramic cutting tools, such as low manufacturing efficiency and simple structure(flat mainly), microwave manufacturing of complex-shaped SiAlON ceramic cutting tools was studied. Finite element simulation was applied to investigate the influences of tool geometry of SiAlON ceramic cutting tools on cutting force and temperature when milling GH4169 superalloys. Then, the designed flat and complex-shaped SiAlON cutting inserts were fabricated by microwave sintering. Finally, the effects of tool geometry on the cutting performance of SiAlON ceramic cutting tool in milling GH4169 superalloys were studied and the optimal structure was determined. The results indicate that the designed tool structures are obtained in the complex-shaped SiAlON ceramic cutting inserts by the microwave sintering, and the tool edge possesses excellent density and well mechanics properties. Compared with flat SiAlON cutting inserts, the wear resistance of complex-shaped SiAlON cutting inserts with optimized tool geometry is well improved, of which the tool life is increased by approximately 71.4% in milling GH4169 superalloys.

Deformation Law　Model and Simulation Verification of Pod Structures with Large Exhibition-to-receive Ratio for Aerospace Applications

YANG Shuo, ZHANG Jie, KONG Ning, WANG Haowei, WANG Xiaoyu, ZHUANG Yuan

2023, 34(07):  780-788.  DOI: 10.3969/j.issn.1004-132X.2023.07.003

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The pod rod, also named as CTM(collapsible tubular mast), was an elastic stretching structure with large exhibition-to-receive ratio. It might be compressed into a plate and loaded on the spacecraft and self-deployed into a hollow cylinder when needed, which might be used to expand solar wings, satellite antennas and other components, and might reduce the volume of spacecraft during launch. The mechanics properties of pod structure should be considered when designing the structure size. A numerical model was established by means of mechanics analysis in order to solve the problems of large amount of calculation, and frequent variation of the factors that affecting mechanics properties. The numerical model might be applied to calculate the compressive force variation during the entire compression processes for the pod structure with different size parameters. The finite element analysis software ABAQUS was used to simulate and analyze the compression deformation. The deviations between the calculation results and the simulation ones are less than 10%. The influences of size parameters of the pod structure on the compressive force were obtained through numerical model analyses.

Research and Optimization of Key Parameters of High Temperature Atomization Dust Removal Efficiency

SHEN Fan, ZHAO Gang, CHEN Yancai, XIONG Wen

2023, 34(07):  789-795，802.  DOI: 10.3969/j.issn.1004-132X.2023.07.004

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In order to stably improve the efficiency of atomization and dust removal in high temperature environment, the droplet evaporation factor with evaporation rate structure was introduced. The atomization processes in high temperature environment were simulated by numerical simulation, and the interactions of nozzle structure, atomization performance and high temperature dust removal efficiency were explored. The L25 Taguchi method was used to design the test, and the outlet diameter, inlet pressure and axial distance of the X swirl pressure nozzle were selected as key parameters, and the influences of each parameter on atomization performance were explored to obtain the optimal parameter combination. Results show that the atomization zone is affected by temperature, and the mass concentration of droplets is a key indicator to improve the efficiency of high temperature atomization and dust removal. The importance of the three key parameters from high to low is as follows:axial distance, inlet pressure and outlet diameter. In the hot rolling processes of HIB steel, the optimal working parameters of the nozzle are as 2 mm nozzle outlet diameter, 8 MPa inlet pressure and 90 cm axial distance. The dust removal efficiency at high temperature is increased to more than 80%.

Study on Influences of Base Fluid Type of External Fluid on Nanofluid Coaxial Electrostatic Atomization Cutting

SU Yu, WU Shikai, JIANG Hai

2023, 34(07):  796-802.  DOI: 10.3969/j.issn.1004-132X.2023.07.005

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Based on the construction of coaxial electrostatic atomization cutting test platform, taking castor oil, soybean oil, rapeseed oil, palm oil, LB2000 and its carbon nanotube oil-based nanofluid as external fluid, taking deionized water and its carbon nanotube water-based nanofluid as internal fluid, the charging performance of coaxial electrostatic atomization and the electrowetting performance of composite droplets under different types of base fluid of external fluid were analyzed. The effects of base fluid type of external fluid on the cutting force and temperature of nanofluid coaxial electrostatic atomization cutting were studied. Results show that LB2000 is suitable as the base fluid of external fluid for nanofluid coaxial electrostatic atomization cutting, which may effectively reduce the cutting force and temperature, and the comprehensive effects of force reduction and cooling are the best when LB2000/water-based nanofluid used as external/internal fluid.

Research on Robot Abrasive Belt Grinding Parameters Considering the Change of Normal Contact Force

CHEN Geng, XIANG Hua, YE HanXIAO Fei

2023, 34(07):  803-811，820.  DOI: 10.3969/j.issn.1004-132X.2023.07.006

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 The surface roughness and surface dimensional accuracy of blades had important influence on the overall performance and service life of the aero-engines. In order to solve the influences of the changes of normal contact forces on the surface roughness and the uniformity of material removal depth on the cut-in or cut-out stages of robotic abrasive belt grinding and the changes of normal contact forces on the parts with large curvature changes， orthogonal center combination design （CCD） test was designed and width learning algorithm was used to establish the prediction model of grinding process parameters， surface roughness and material removal depth. The prediction model of normal contact force and surface roughness and material removal depth measured by sensors was used to solve the adaptive processing parameters by combining multiple learning backtracking search algorithm. Finally， grinding tests were carried out with the obtained processing parameters. The maximum errors between the test values of surface roughness and material removal depth and that of the model predictions are as 14.2% and 13.4% respectively. The proposed method may ensure good consistency between surface roughness and material removal depth. 

Effects of High Speed Tangential Turn-milling on Surface Integrity of 18CrNiMo7-6 Steels

WANG Dong, LIN Hongxu, ZHAO Jingwen, QIAO Ruiyong, ZHANG Junyu, ZHAO Rui

2023, 34(07):  812-820.  DOI: 10.3969/j.issn.1004-132X.2023.07.007

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In order to improve the anti-fatigue performance of 18CrNiMo7-6 gear steel, high-speed tangential turn-milling experiments were conducted. Results show that with high-speed tangential turn-milling, the three-dimensional surface roughness value Sa are close to those with grinding. The influences of workpiece rotating speed nw and milling cutter rotating speed nc on Sa are significant. The Sa decreases with the increase of nc, and increases with the increase of nw. There are residual compressive stresses on the machined surfaces of high-speed tangential turn-milling(up milling). The nc and axial feed fa have significant effects on surface residual stress. With the increase of nc, the axial residual stress σx and the tangential residual stress σy show the trends of increasing at first and then decreasing, and with the increase of fa, σx and σy decrease significantly. The maximum residual stress appears on the machined surfaces, decreases gradually within 40~60 μm thickness from the machined surface and then stabilizes. The fa has the greatest overall impact on the surface integrity and the surface integrity deteriorate rapidly with the increase of fa. Under the orthogonal test conditions of high-speed tangential turn-milling, the optimal test parameter combination obtained is as nc=6500 r/min, nw=75 r/min, fa=0.02 mm/r, radial depth of cut ap=0.1 mm. Under the conditions of optimal cutting parameters, the Sa is as 0.30 μm, σx is as -400.5 MPa, σy is as -415.9 MPa, and the depth of residual stress affected layer is as 60 μm. The surface integrity with high-speed tangential turn-milling is better than that with conventional turning. The cutting method herein provides a better machining method for machining external cylindrical surfaces.

Thermal Mechanics Coupling Analysis of Angular Contact Ball Bearings Installed in Pairs in Feed System

LI Zhenjun, ZHAO Chunyu

2023, 34(07):  821-829.  DOI: 10.3969/j.issn.1004-132X.2023.07.008

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The prediction and analysis of thermal mechanics coupling performance of angular contact ball bearings was the key to ensure the working accuracy of machine tools. Based on Hertz contact theory and thermal network method, a dynamic thermal mechanics coupling model of ball screw feed system pair-installed bearings was established under working conditions, the internal lubrication state and the thermal expansion of ball bearings were considered under temperature rise effect, and a numerical calculation method was proposed for dynamic thermal mechanics coupling analysis of bearings. The time-varying laws of internal contact parameters and friction heat generation of the bearings were proved. Results show that the rotational speed and the external load affect the frictional contact characteristics of bearings, and the performance of bearings is significantly affected by the thermodynamics behavior. The dynamic thermal mechanics coupling analysis model proposed herein may effectively predict the contact characteristics of bearings under nonlinear thermal behavior. 

Analysis and Calculation of Comprehensive Axial Deformations of Ball Screw-Bearing in Ball Screw Support Units

XU Xiaohua, JIANG Guiping, HAN Xingguo, ZHANG Zhengpo

2023, 34(07):  830-837.  DOI: 10.3969/j.issn.1004-132X.2023.07.009

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The ball screw-bearing of two kinds of common ball screw support units were analyzed. Using three-broken-line approximation method, the bivariate function of comprehensive axial deformations of ball screw-bearing in ball screw support units was derived with the change of position and load. The comprehensive axial deformations with the change of position was approximately asymmetric arc with the opening downward, and the calculation formula of maximum comprehensive axial deformations and the position coordinate were derived. Analysis and experimental results show that the change form of the comprehensive axial deformations of ball screw-bearing tends to flat while the ratio of maximum deformation between ball screw and bearing decreasing gradually, and the position coordinates of maximum deformation move away gradually from the center of the two supporting spans along the load direction.

Research on Stamping Springback of Automobile Beam Parts Based on Deep Learning

NIE Xin, TAN Tian, SHEN Danfeng

2023, 34(07):  838-846.  DOI: 10.3969/j.issn.1004-132X.2023.07.010

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A method was proposed herein for springback prediction of automobile beam parts based on deep learning. Based on the two-dimensional springback theory, the three-dimensional beam parts were discretized into several sections, and the cross-section curve of the beam parts was converted into a dual-channel image that could be recognized by neural network model using the method of double-plane projection and the image binarization method. Based on Latin hypercube sampling method, the stamping process parameters and sheet material parameters of the beam structure parts were sampled, and the subsequent deep learning network training samples were obtained by CAE springback simulation. In order to study the springback of beam structures under different geometric cross-sections, material parameters, and processing parameters, convolutional neural network models based on LeNet-5, AlexNet and NiN were used as geometric cross-section recognition models. Meanwhile, the fully connected neural network model was used to couple material parameters and processing parameters to obtain the springback algorithm model of beam parts. Car beam structural parts were taken as the research object. Based on Gaussian mixture clustering, the springback samples were divided into three types: small springback, medium springback, and large springback. Each type of springback sample was verified by the springback algorithm model. Verification results show that the deep learning model has the highest accuracy based on AlexNet, and the algorithms robustness is also stronger than that of the other two, which is more suitable for springback prediction of beam parts.

Investigation on Hydroforming with Axial-circumferential Feeding of Preformed Tubes with D-shaped Cross-section of Heavy Truck Axle Housing

ZHANG Jiaqi, WANG Liandong, SONG Xiliang, ZHANG Yansong, ZHAO Zhengyue

2023, 34(07):  847-858.  DOI: 10.3969/j.issn.1004-132X.2023.07.011

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In the bugling-pressing tests of large-size heavy truck axle housing, axle housing tubes were hydro-pressed by preformed tubes with approximate rotary shape, the wall thickness had large reduction in the middle part of tube, and rear cover had crackings. Therefore, the preformed tubes with D-shaped cross-section and the hydroforming process with axial-circumferential feeding were designed. The stress states and characteristics of deformation in axial feeding stage and axial-circumferential feeding stage were analyzed. The conditions of plastic deformation in different areas and the expressions of circumferential stress at typical nodes of the middle cross section were derived. For a axle housing of 10 t heavy truck, the FEA of hydroforming of preformed tube with D-shaped cross-section was carried out, the variation law of normal stress and shear stress in each area and the law of metal flow along the circumferential direction were revealed. The bulging-pressing test of heavy truck axle housing was carried out, the preformed tube with D-shaped cross-section was successfully produced with good forming. Results show that the circumferential distance of metal flow and distribution of wall thickness are consistent with the values of the FEA, and the thinning rate of wall thickness is significantly reduced. After hydro-pressing forming, the wall thickness in middle part of axle housing has increases, and the rear cover is formed with no cracking. Moreover, the weight of the front cover is decreased by 15.64%.

Predictive Analysis of Wheel Wear Based on Semi-Hertzian Contact

NIU Jiang, CHI Maoru, LI Dazhu, LUO Yun

2023, 34(07):  859-865，874.  DOI: 10.3969/j.issn.1004-132X.2023.07.012

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In order to compare the differences between Hertzian and semi-Hertzian contact algorithms in wheel-rail wear simulation processes, a dynamic model of CR400BF electric motor train unit(EMU) was established. Long-distance simulations were conducted based on Hertzian and semi-Hertzian contact algorithms(STRIPES), and the wear was calculated using Archard wear model. The calculated results of the two algorithms were compared respectively with the measured tread wear of 250 000 km. Results show that the wear amount and distribution of different rail profiles are obviously different. The shapes of the semi-Hertzian contact patch are obviously different under different wear mileages, the contact patch areas increase and the maximum contact stresses decrease gradually. At early stage of wear, the abrasion and distribution obtained by the two contact algorithms have little difference and are close to the measured results. But at later period, the abrasions of two kinds of algorithm are larger than the measured results， and the semi-Hertzian contact is more in line with the measured results than that of Hertzian contact. The reason is that with the increasing abrasion mileage, wheel/rail contact no longer meets the Hertzian contact hypothesis.

Analysis and Experimental Verification of Corner Filling Degree of Rectangular Tube Roll Forming

XING Menglong, DU Fengshan, FU Yutao

2023, 34(07):  866-874.  DOI: 10.3969/j.issn.1004-132X.2023.07.013

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In order to improve the forming accuracy of square rectangular tube corners formed by roller forming, the causes of underfilling rectangular tube corners were analyzed according to the law of constant volume and the principle of equal metal flow per second. The finite element model of roll forming was established according to the actual production parameters in the factories, and the influences of pipe diameter and wall thickness on the thickening coefficient and corner filling degree in the forming processes were analyzed. According to the linear relation of arc length of neutral layer in underfilled regions of the corner, the tube diameter was corrected and the coefficient correction relation was determined. The damage of the corner forming processes was judged, and the appropriate diameter of the round pipe was selected. The simulation results were compared with the experimental ones. The results show that the corners are underfilled with the increase of wall thickness during roll forming. The decrease of wall thickness leads to the decrease of thickening coefficient, and the required diameters of circular pipes are smaller. With the increase of pipe diameters, the corner filling degree is better, at the same time, the increase of pipe diameters will increase the possibility of damage in the inner corner at the exit of roll forming. The errors between the test results and the experimental results are small, which verifies the accuracy of the simulation model. 

Numerical Simulation and Experimental Verification of Pulling-riveting Process of New Non-plate Nuts

WANG Shoucai, SUN Ang, LIU Rugang

2023, 34(07):  875-881.  DOI: 10.3969/j.issn.1004-132X.2023.07.014

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Due to the excellent characteristics in improving installation efficiency and reducing fatigue sources, a new type of 304 stainless steel non-plate nut was generalized in aviation field. Based on Johnson-Cook model, the finite element model was built to analyze the pulling-riveting progress. The loading-curve, plastic-flow, clamping force and interference amount, and the influences of interlayer state on riveting quality were analyzed. Meanwhile, the riveting installation tests of nuts were carried out. Results show that the finite element simulation model is in good agreement with the test loading curve, and the maximum load deviation from test is as 2.4%. When the compression stress of the nut is much higher than the yield stress of the material, the instability of the structure occurs, and the bulge structure is formed rapidly. The plastic flow mainly develops along the radial direction. The pulling-riveting process may provide a certain amount of clamping force and interference to interlayer. The clamping force reaches the maximum value after complete riveting, yet in a certain range, the slope of the riveting interlayer does not affect the clamping force. The maximum interference in the riveting processes is about 4.6%.