2023 No. 7

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Cover Catalogue
Fault Diagnosis
Research on fault diagnosis of rolling bearing based on ALIF and TMFDE
ZHAO Jiahao, LUO Na, LIANG Yongwen
2023, (7): 9-15. doi: 10.19287/j.mtmt.1005-2402.2023.07.001
[Abstract] FullText HTML PDF(1689KB)
Abstract:
In order to improve the fault identification accuracy of rolling bearing, a fault diagnosis method based on adaptive local iterative filtering (ALIF) and time-shifted multi-scale fluctuation dispersion entropy(TMFDE) was proposed. Firstly, the vibration signal of rolling bearing was decomposed by ALIF to obtain a set of IMF components. Secondly, to obtain more integrated IMF components, the importance of each IMF component was evaluated based on the energy method, and the first three components were regarded as effective components. Then, the TMFDE was used to quantify the feature information in the effective component and construct the fault feature vector. Finally, the fault features were input into the extreme learning machine optimized by particle swarm optimization for fault identification. The method was tested by using the rolling bearing data of Southeast University. The results show that the method can accurately identify the type of fault, and compared with other methods, this method still has excellent stability when the amount of data is small.
Fault diagnosis of rolling bearing based on wavelet threshold noise reduction EMD-AR spectrum analysis and extreme learning machine
YAO Fenglin, YANG Xu, DING Fanzhi, ZHAO Mingjie, LI Shuai
2023, (7): 16-20, 31. doi: 10.19287/j.mtmt.1005-2402.2023.07.002
[Abstract] FullText HTML PDF(2356KB)
Abstract:
In the traditional rolling bearing fault diagnosis, vibration characteristics are easy to be interfered by redundant noise, and fault characteristics can not be accurately classified, a rolling bearing fault diagnosis method based on wavelet denoising, EMD-AR spectrum analysis and ELM (extreme learning Machine) was proposed. The vibration signals of rolling bearings are firstly de-noised by wavelet threshold, then the de-noised one-dimensional signals are decomposed by EMD and the first six IMF components are extracted. The AR spectra of the first six IMF components are accumulated to obtain the EMD-AR spectra of the de-noised vibration signals, from which different fault conditions of bearings can be seen as a prior diagnosis. Finally, six eigenvalues of the denoised signal were extracted as samples. In order to avoid the contingency of the experiment, the ELM classification diagnosis model based on K-fold cross-validation was established. The diagnosis results show that the method can clearly classify the bearing fault situation, the classification accuracy is up to 100%, and can provide a new method for the bearing fault diagnosis.
Fault diagnosis of high speed ball bearing based on elastic kernel convex hull tensors
YUAN Liukui, JIA Guanghui, LI Hui
2023, (7): 21-25. doi: 10.19287/j.mtmt.1005-2402.2023.07.003
[Abstract] FullText HTML PDF(1493KB)
Abstract:
In order to improve the fault diagnosis accuracy of mechanical transmission system, a fault diagnosis method of high-speed ball bearing based on elastic kernel convex hull tensor was designed. The time-frequency distribution is established by using the continuous wavelet transform method with mature technology, and then the feature set is established according to the data of the gray co-occurrence matrix of the time-frequency graph, from which the accurate texture features of the time-frequency graph are calculated. The model of training elastic kernel convex hull tensor is used to identify test set samples and realize fast fault diagnosis. The research results show that the proposed method can obtain higher accuracy than the initial elastic convex hull classification method, and the texture features of time-frequency maps achieve higher accuracy than the traditional time-frequency features. The elastic kernel convex hull tensor has excellent generalization performance and achieves the optimal classification accuracy. The training set and test set were divided by the ratio of 8∶2, and the elastic kernel convex hull tensor was used to achieve the highest accuracy. The elastic kernel convex hull tensor showed better anti-noise and robustness. The research can be applied to other mechanical transmission systems and has a good value for practical promotion.
Non-traditional Machining
Effect of electrode materials on the surface quality of aero-engine honeycomb ring with short arc grinding
MIAO Lijun, ZHOU Bisheng, ZHOU Jianping, WANG Zijian, DING Shengwei
2023, (7): 26-31. doi: 10.19287/j.mtmt.1005-2402.2023.07.004
[Abstract] FullText HTML PDF(3961KB)
Abstract:
SEAM grinding of aero-engine honeycomb ring is a new machining method for aerospace disk ring parts. In view of the characteristics of low stiffness and thin wall of such parts, Seam grinding is adopted to achieve high precision, high efficiency and high quality machining requirements. Because the electrode with different materials will produce different machining effects, in order to study its performance, the short arc grinding test of aero-engine honeycomb ring was carried out by using cast iron, copper, brass and graphite. The thickness of recast layer, surface roughness (Ra), surface morphology (SEM), machining surface elements, machining current waveform and electrode loss ratio (TWR) were analyzed. The results show that the recast layer thickness of cast iron electrode after discharge grinding is the lowest, and there is no micro-crack on the surface, while the recast layer thickness of graphite electrode is the largest, and the TWR of graphite electrode is the highest, which affects the machining accuracy, so it is not suitable for short arc grinding of such parts. The discharge is stable and the electrolytic current is the largest during the processing of copper electrode.If the idling time is prolonged, electrolytic reaction can be effectively generated to remove the recast layer.
Advances in surface laser cladding remanufacturing technology for shaft parts
ZHAO Changlong, YANG Junbao, LI Ming, ZHAO Qinxiang, MA Hongnan, JIA Xiaoyu, ZHANG Haifeng
2023, (7): 32-37. doi: 10.19287/j.mtmt.1005-2402.2023.07.005
[Abstract] FullText HTML PDF(1157KB)
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In high-end manufacturing areas such as transportation, mining, and petrochemicals, shaft components often failed due to wear, corrosion, and fatigue under the high temperatures and pressures. Nowadays, laser cladding is widely used for shaft components surface repair and strengthen because of its low dilution rate, small heat-affected zone, and good metallurgical bonding between the coating and the substrate. This paper provides an overview of the commonly used process methods for laser cladding, including pre-set powder feeding, simultaneous powder feeding and wire feeding cladding, and provides researchers with an initial understanding of this direction through an introduction to the above processes. At the same time, the performance of the cladding layer of shaft parts processed under different process parameters, such as the influence of comprehensive parameters such as laser power, scanning speed, lap rate and powder feed rate, is reviewed, as well as the application of numerical simulation techniques to the simulation of stress fields when laser cladding processing is carried out on the surface of shaft parts. The research on ultra-high speed laser cladding of shaft components is discussed. Finally, the problems in the current research on laser cladding of shaft components are summarized and the development directions are outlined.
Microstructure and mechanical properties of low-alloy high-strength steel for ship fabricated by wire-arc additive manufacturing
DONG Hao, GUO Xuming, XU Rongzheng, ZHAO Ling, XIONG Yunlong
2023, (7): 38-42. doi: 10.19287/j.mtmt.1005-2402.2023.07.006
[Abstract] FullText HTML PDF(1509KB)
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The multiple-pass multilayer steel wall was fabricated by wire-arc additive manufacturing (WAAM) technology using self-made low-alloy high-strength steel wire for ship. The microstructure and mechanical properties of the as-deposited and annealing heat treated samples were studied. The results showed that the low-alloy high-strength steel wall fabricated by WAAM had good forming quality and realized effective metallurgical combination between layers. The microstructure of the as-deposited sample was mainly composed of granular bainite and irregular polygonal ferrite, which had high strength, plasticity and good low temperature impact toughness. The martensite-austenite (M-A)components were continuously decomposed to form ferrite and many fine carbides after annealing at 400°C and 600°C, which reduced the number of granular bainite and increased the number of ferrite, resulting in strength reduction and plasticity and low temperature toughness improvement.
Cutting Processing
Research on optimization of milling parameters of 15-5PH stainless steel based on response surface method
SHI Jiaxing, JIN Chengzhe, GAO Ke
2023, (7): 43-47. doi: 10.19287/j.mtmt.1005-2402.2023.07.007
[Abstract] FullText HTML PDF(1335KB)
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15-5PH precipitation hardening stainless steel is a difficult material,so it will produce large cutting force and great plastic deformation during processing. Therefore, it is necessary to optimize its cutting parameters to optimize the cutting process. In this paper, the spindle speed, feed speed, axial cutting depth and radial cutting depth are taken as the optimization design variables, and the cutting force, surface roughness and material removal rate are taken as the response performance indicators. The response analysis model of high-speed milling precipitation hardening stainless steel is designed, and the response function analytical formula of the optimization design variables was analyzed and obtained. The influence of the interaction of various optimization design variables on the optimization objectives was studied. The optimal combination of reducing low cutting force and roughness and improving cutting efficiency for high-speed milling precipitation hardened stainless steel was obtained, which is vc = 100 m/min, fz = 0.02 mm/z, ap=1.5 mm, ae = 0.4 mm.
Research on milling temperature of GH4169 based on neural network
LI Feng, ZHAO Dezhong, LI Chenxu, LIU Weiwei
2023, (7): 48-53. doi: 10.19287/j.mtmt.1005-2402.2023.07.008
[Abstract] FullText HTML PDF(1659KB)
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To study the influence of milling parameters on milling temperature in milling GH4169,an orthogonal test between milling parameters and milling temperature was designed. Based on the data obtained from the orthogonal test, the prediction models of GH4169 milling temperature were established by using radial basis function neural network,back propagation neural network and generalized regression neural network algorithms respectively, and the models were trained, tested and verified.In addition,the influence laws of milling parameters on milling temperature was analyzed by the range analysis method. The results showed that the average prediction error of GH4169 milling temperature prediction models based on RBF neural network、GRNN neural network、BP neural network were 3.27%、4.24%、5.05%, and the the average prediction accuracy were 96.73%、95.76%、94.95%. The model based on radial basis function neural network had the highest prediction accuracy, followed by back-propagation neural network model and generalized regression neural network model.The milling temperature of GH4169 increased with the increase of milling speed, feed per tooth and milling depth; The most important factor affecting milling temperature was milling speed, followed by feed rate per tooth and milling depth.
Modeling and experimental study on wear overlap distribution per cutter tooth in multi-axis milling
QUAN Hongjie, ZHANG Chunyan, GUO Jianfeng
2023, (7): 54-60. doi: 10.19287/j.mtmt.1005-2402.2023.07.009
[Abstract] FullText HTML PDF(2160KB)
Abstract:
To solve the problem of inaccurate prediction of wear distribution per tooth caused by continuous change of tool contact points in the processing of multi-axis machine tool, a wear overlap distribution model with tool run-out was established. The element wear distribution per tooth model was developed by tool geometry model and worn cutting edge trajectory model. The wear overlap distribution per tooth model with actual cutting depth and contact point of each flute was proposed by the milling mechanism per tooth and tool run-out. A case study was carried out to validate the prediction accuracy of the proposed model. The comparison results show that there is a good agreement between simulation and experiment results.
CNC Technology
Secondary development of helical bevel gear tooth chamfering software based on FAGOR
LI Weiyuan, HONG Rongjing, SUN Xiaomin, XU Chen, GAO Han, LI Shuaikang
2023, (7): 61-66. doi: 10.19287/j.mtmt.1005-2402.2023.07.010
[Abstract] FullText HTML PDF(2008KB)
Abstract:
On the basis of studying the theory of helical bevel gear top chamfering, the development process of helical bevel gear top chamfering software is introduced with FAGOR CNC8070-OL numerical control system as the development object. The human-machine interface design of the software uses VB.net cross-platform development, the parameter calculation logic program is written in C++ language, the parameters required by the software are supported by ACCESS 2010, and the FGUIM development software that comes with FAGOR system is used as the connection between the third-party software and the numerical control system, and the helical bevel gear tooth top chamfer software is developed, and embedded in the FAGOR 8070-OL numerical control system to realize the functions of parameter calculation, NC numerical control code generation, database management and so on.
Architecture design of high-end CNC system based on distributed
DAI Chaoyong, CHEN Miaoling
2023, (7): 67-71. doi: 10.19287/j.mtmt.1005-2402.2023.07.011
[Abstract] FullText HTML PDF(1262KB)
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Based on the distributed architecture, this paper designs the architecture of the CNC system. A new system architecture is proposed from the perspective of system hardware architecture and system software architecture ,which is characterized by modular superposition, separation, independent optimization and easy iteration.At the same time, it can also meet the computational requirements of high accuracy, high efficiency and high surface quality.Meet the requirements of intellectualization, networking and informatization of future CNC system.This paper verifies the feasibility of this new system architecture. It constructs a new design idea for the architecture design of high-end CNC system.
Special Reports
Review of deformation control on bearing manufacturing
LUO Taimin, CAO Huajun, JIANG Yanhong, XU Jun, LI Jingyang, LI Kun, ZHANG Jin
2023, (7): 72-82. doi: 10.19287/j.mtmt.1005-2402.2023.07.012
[Abstract] FullText HTML PDF(2945KB)
Abstract:
Advances in construction machinery technology are driving an increasing demand for the high-performance bearings. Due to the existence of problems such as clamping deformation, cutting deformation and thermal deformation during bearing machining, the accuracy of finished bearings is seriously restricted, so the deformation control technology during bearing machining has become the focus of research by various manufacturers and institutions. This paper aims to present a comprehensive overview of the current research progress in bearing machining deformation control, analyzes the causes of bearing machining deformation (including cutting force, cutting temperature, cutting tools and other factors). The paper provides a detailed discussion of prevalent methods for controlling bearing machining deformation, such as changing the machining method, changing the structure of the chuck and machining parameters control, etc. Finally, this paper analyzes the advantages and disadvantages of the various bearing processing deformation control methods currently employed. The future trends in research on bearing processing deformation control are also discussed. Given that researching bearing machining deformation control is an important direction in the machining field, this paper will have a positive impact on improving the quality and efficiency of bearing machining.
Design and Research
Design of multi-station special machine tool for aerospace special-shaped fastener processing
LI Kuo, WANG Xianlong, ZHAO Changzhen, SHI Xianming, HOU Yongpeng, XIE Changchao, GAO Jianshe
2023, (7): 83-88. doi: 10.19287/j.mtmt.1005-2402.2023.07.013
[Abstract] FullText HTML PDF(2331KB)
Abstract:
In order to improve the machining precision and efficiency of special-shaped aerospace fasteners, centralizing and optimizing the original fastener production process, the compound multi-station special machine tool is designed. By analyzing the requirements of dimensional tolerance, surface roughness and shape and position tolerance of parts, the mechanical structural design of the machining unit and rotary plate dividing feeding were completed to satisfy the process requests. Through a single clamping, four fasteners can be processed by the machine tool at one time, reaming, reaming, chamfering angle, tapping four basic processes included. Adopting custom special composite cutting tool, the size requirements and precision requirements of the parts are satisfied. The trial production of batch samples has been complete. It meets the drawing requirements of the parts after processing verification.The processing time meets the company’s requirements of production rhythm. It provides an effective solution for the full automatic processing of similar special-shaped fasteners in the aerospace field.
Research on dynamic characteristics of fixed joint surface of grinder bed column
SHEN Jicheng, ZHU Xianglong, DONG Zhigang, KANG Renke, XU Jiahui
2023, (7): 89-93. doi: 10.19287/j.mtmt.1005-2402.2023.07.014
[Abstract] FullText HTML PDF(2509KB)
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The bed and column are important assemblies of the grinder, and the characteristics of the joint surface directly affect the dynamic performance of the grinder. In order to explore the impact of the joint surface stiffness on the dynamic performance of the system, an equivalent spring finite element model of the joint surface stiffness is proposed for the joint surface of the grinder's bed and column. The accuracy of the model is verified by modal test, and the joint surfaces X, Y, and The influence of the stiffness in three directions of Z on the system mode. The simulation results show that: when the stiffness of the joint surface is change in a certain range of 2×109~8×109 N/m, The influence of Z-direction stiffness on the first to three modal frequencies of the system is the largest, and the influence on the first modal frequency is the largest, accounting for 90.2%; The X-direction stiffness of the joint surface mainly affects the second mode frequency of the system, accounting for 32%; The Y-direction stiffness of the joint surface mainly affects the third-order modal frequency of the system, accounting for 38%. It provides a new method to improve the dynamic characteristics of the whole machine and optimize the structure of the machine tool.
Design of target positioning turntable servo system controller based on the backstepping terminal sliding mode algorithm
SU Fei, ZHANG Xi, DUAN Yanbin, WEI Wenkui
2023, (7): 94-99. doi: 10.19287/j.mtmt.1005-2402.2023.07.015
[Abstract] FullText HTML PDF(2133KB)
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During the operation of the target positioning turntable servo system, the problem of drive delay and response delay caused by backlash in transmission can seriously affect the stability of the tamable. In this paper, a novel backstepping terminal sliding mode control algorithm is proposed to deal with the problem of tracking control of servo system with backlash. Firstly, the state space of the target positioning turntable servo system is established, the dead zone function is introduced to describe the nonlinearity of the backlash, and the continuous differentiable function is designed to fit the dead zone function. Secondly, by utilizing the backstepping control method and terminal sliding mode control method, the virtual controller and actual controller are designed for the servo system. The asymptotic stability of the closed-loop system is proved by Lyapunov theory. Finally, the simulation system and experimental platform are performed. Compared with the result of conventional PID controller, the effectiveness and superiority of the control method proposed in this paper are verified.
Research on macromotion control strategy of macro-micro composite actuator based on active disturbance rejection control
YU Caofeng, XIAO Zhihao, WU Gan, YANG Kun, WEI Yijun, TAO Xuefeng
2023, (7): 100-107. doi: 10.19287/j.mtmt.1005-2402.2023.07.016
[Abstract] FullText HTML PDF(2663KB)
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Aiming to precise positioning field, A coaxial macro-micro composite actuator with voice coil motor as macromotion part and giant magnetostrictive actuator as micromotion part is designed. In order to realize the control of the macromotion part, a dynamic model of the macromotion part is established based on the principle of electromagnetic drive, the active disturbance rejection control system is designed for the macromotion part, which includes 4-order extended state observer and non-linear state error feedback controller. The 5-order S-type displacement curve path planning is used. The experimental results show that the maximum following error of the ADRC algorithm is about 0.155 mm, and the final location error is about 9 μm; Under load condition, the maximum following error of the ADRC algorithm is about 0.277 mm, and the final positioning error is 11 μm. The research results show that compared with PID algorithm, ADRC has lower following error and overshoot, and the final location error is within the micro positioning range of micromotion part, which meets the overall design requirements.
Research on controlled synchronization of vibrating screen driven by two induction motors
WANG Guohui, JIA Lei, PAN Cheng, WANG Chun, YANG Jiankang
2023, (7): 108-115. doi: 10.19287/j.mtmt.1005-2402.2023.07.017
[Abstract] FullText HTML PDF(3605KB)
Abstract:
The vibrating screen with vibration synchronization as the working mechanism can no longer meet the process needs in the social generation, so the control method is introduced to achieve the zero phase difference state and achieve the purpose of increasing the amplitude. According to the mechanical dynamics theory, the motion state of the vibrating screen is transformed into the dynamic model of the two-machine drive vibration system, and the synchronization conditions and stability conditions of the synchronous motion of the vibration system are derived and analyzed. Based on the master-slave control strategy, the speed controller of a single induction motor is designed by using the model predictive flux control strategy, the feedforward control is introduced into the single-neuron PID control, and the phase controller is designed to realize the zero phase difference state of the two-eccentric rotor. According to the dynamic model, the simulation model is built in Matlab/Simulink, and the simulation shows that the proposed control strategy and method are effective and stable. The proposed control method is compared with other control methods, and the results show that the synchronous control effect of the proposed control method is better.
Optimization method for the balance and determinacy of initial residual stress based on blank selection
LI Xiaoyue, QI Hao, LI Liang, YANG Yinfei
2023, (7): 116-124. doi: 10.19287/j.mtmt.1005-2402.2023.07.018
[Abstract] FullText HTML PDF(2168KB)
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It is difficult to guarantee the uniformity and batch-to-batch consistency of the initial residual stress of large components, which will cause many problems such as high distortion, high uncertainty, and unstable contour distortion process of components. The paper presents an optimization method for the equilibrium and determinism of initial residual stress based on blank selection. A mechanical model of ‘stress-structure-distortion’ was constructed. Full-scale stress condition number and local stress condition number in the stress input module were extracted, which can be used to evaluate the equilibrium and determinism of complex initial residual stress. The influence law of stress condition number on machining distortion was studied. Furthermore, the method of blank selection and workpiece position selection based on stress condition number was proposed, which can be used to select optimal blank. An aviation single-sided stringer component was taken to carry out the verification test. The results showed that optimal workpiece position were 4 mm (65 mm-thick blank) and 7 mm (70 mm-thick blank) respectively and optimal blank thickness was 70 mm.
Research on optimization design and precision positioning of integrated 2PR-R type compliant parallel mechanism
SONG Xiaolei
2023, (7): 125-131. doi: 10.19287/j.mtmt.1005-2402.2023.07.019
[Abstract] FullText HTML PDF(1837KB)
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The positioning accuracy of precision positioning device in the plane is taken as the task-based requirement, a planar 2PR-R compliant parallel mechanism with two degrees-of-freedom was designed as the ontology configuration, its Jacobian matrix was built based on vector mapping relationship, so that its kinematic characteristics of multi-inputs and multi-outputs could be verified. Furthermore, a multi-objective function of the optimization problem was established by two sub-objectives of the static stiffness and first-order natural frequency as optimization objective, which was based on the kinematic characteristics of 2PR-R compliant parallel mechanism. Taking the Jacobian matrix of planar 2PR-R compliant parallel mechanism as motion constant and its material volume fraction as inequality constraint to build the numerical model for the optimization problem, and the optimization solution was solved by level-set algorithm. Finally, the boundary curve of optimization result is fitted by SolidWorks technology, and the static problem of the optimal configuration was analyzed based on OptiStruct. Results shown that the differential kinetic characteristics of planar 2PR-R compliant parallel mechanism optimal configuration is consistent with its parallel prototype mechanism, the positional accuracy is achieved at the micron level.
Technology and Manufacture
Precision control method of tooth profile for involute spline broach with secondary back Angle
SHEN Yanmin, XIN Yupeng, GUO Xingwen, LIU Runai, HAO Limin
2023, (7): 132-136. doi: 10.19287/j.mtmt.1005-2402.2023.07.020
[Abstract] FullText HTML PDF(1726KB)
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The production efficiency of involute spline broaching tool is limited due to the need of multiple grinding to ensure the preparation accuracy of subsequent spline holes. In order to solve this problem, it is necessary to study the determination method of the optimal correction tooth profile of involute spline broaching tool with a pair of back angles. In this paper, the involute replacement theory is used to correct the tooth profile and the least square method and numerical search method are combined to solve the alternative involute function. In the case analysis, the optimal pressure Angle is controlled to 0.01°, and the minimum of tooth profile error is obtained. In the same group of error points, the total error of tooth profile fitting by the substitute involute method is 0.001 mm better than that by the substitute circular arc method. The cross-bar distance error of the broach is less than 0.01 mm. The 5 level precision of the involute internal spline gear is tested by matching P26C tooth profile.
Machining feature recognition method for mechanical parts based on improved MeshCNN
ZHANG En, ZHANG Shengwen, JIA Jiale
2023, (7): 137-142. doi: 10.19287/j.mtmt.1005-2402.2023.07.021
[Abstract] FullText HTML PDF(1603KB)
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In order to solve the problem of low efficiency and low intelligence of feature recognition in traditional computer-aided process planning (CAPP) system, this paper proposed a novel machining feature recognition method for mechanical parts based on Mesh-Faster Region-based CNN (RCNN) by combining original MeshCNN with Faster RCNN. The method obtained the optimal neural network model by taking the customized processing dataset as the input of the neural network. Then MBD technology was used to label the machining model, and the characteristics to be processed were obtained by PMI information annotation, which were transformed into triangular mesh data. On this basis, combined with the algorithm of triangular mesh data processing, the processed machining feature data is imported into the optimal neural network model to complete the feature recognition process. Finally, the feasibility and effectiveness of the proposed method are verified by taking the key parts of the diesel marine engine as an example.
Effect of flushing mode on the performance of short electric arc and electrochemical compound machining
FU Fei, DAI Xiangyu, HU Guoyu, WANG Jiahao, ZHOU Jianping
2023, (7): 143-149. doi: 10.19287/j.mtmt.1005-2402.2023.07.022
[Abstract] FullText HTML PDF(1741KB)
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In order to solve the problems of unstable machining and low machining efficiency in the internal-external flushing mode of short electric arc and electrochemical compound machining, this paper proposes an external air-internal liquid flushing mode that is more suitable for short electric arc and electrochemical compound machining. In the machining process, high pressure air is injected into the side to realize the combination of short arc machining and electrochemical machining in the machining gap, improve the gap flow field distribution, and improve the efficiency of short electric arc and electrochemical compound machining and workpiece surface quality.Based on Fluent software, the flow field simulations of internal-external flushing and external air-internal liquid flushing were carried out to analyze the effect of flushing of side high-pressure gas on the flow field distribution of the gap and the electrical conductivity of the medium. The material removal rate, unit energy consumption volume ratio and surface thermal damage layer under the two flushing forms were investigated by comparative experiments. The results show that the material removal rate (MRR) of the external air-internal liquid flushing mode can reach 750 mm3/min, which is 1.9 times higher than that of the internal-external flushing mode, and the unit energy consumption volume ratio is only 149.98 kJ/cm3, and the surface of the workpiece is free of recast layer after machining, and the dimensional accuracy is also greatly improved, realizing the machining of material without recast layer.
Optimization of turning tool geometry parameters for thin-walled stainless steel bushing parts
HAN Jun, LI Zhenjie
2023, (7): 150-155. doi: 10.19287/j.mtmt.1005-2402.2023.07.023
[Abstract] FullText HTML PDF(1795KB)
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In the machining of a stainless steel thin-walled sleeve parts due to excessive cutting force caused by the machining accuracy of the parts difficult to guarantee the problem, where the geometric parameters of the tool is an important reason affecting the size of the cutting force. A method of optimizing the front angle, back angle and main deflection angle of the tool to reduce the cutting force is studied, a cutting simulation model is established, the maximum cutting force is calculated, the geometric parameters of the tool are established as a function of the cutting force, and the geometric parameters of the tool are optimized by the whale algorithm. The results show that the established function is more accurate and the cutting force is reduced by 16.99% after the optimization of tool parameters by the whale algorithm, which has a significant effect on improving the machining quality of the part.
Optimization of hot melt welding process of PE pipeline based on finite element method
WANG Baohong, LI Jun, SHI Junlin, CHEN Ye, LI Tao
2023, (7): 156-162. doi: 10.19287/j.mtmt.1005-2402.2023.07.024
[Abstract] FullText HTML PDF(1514KB)
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In order to address the welding quality issues caused by inconsistent indoor and on-site construction environment during the hot melt welding of polyethylene pipes, the finite element method in Ansys software was employed to analyze the influence of different environment on temperature uniformity and melt layer thickness, and to evaluate the welding process. Based on the melt layer thickness, an optimization model for the welding process was established and the optimized welding process parameters were validated through tensile experiments. The results showed that under certain environmental conditions, the pipe temperature gradually approached the ambient temperature as the axial distance increased. The uniformity of temperature at the welding end decreased first and then gradually increased with an increase in cooling time, reaching a minimum at around 200 seconds. The melt layer thickness gradually decreased with a decrease in environmental temperature and an increase in wind speed, with a maximum reduction of 25%. The difference between the tensile strength of the optimized sample and that of the indoor standard welding process was within 5% and met the standard welding quality requirements.
Test and Quality
An FPGA implementation method for fast weld image processing
MU Xiangyang, XU Yi
2023, (7): 163-168. doi: 10.19287/j.mtmt.1005-2402.2023.07.025
[Abstract] FullText HTML PDF(1400KB)
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A fast pipeline weld image processing algorithm based on FPGA is proposed for the lack of real-time detection of pipeline weld by serial architecture processor and general computer. In the process of collecting pipeline weld image, there will be noise interference image, which directly affects the edge detection and target recognition of defects. The parallel computing and pipeline technology of FPGA are applied to median filtering and Sobel edge detection algorithm to realize parallel processing between modules, and pixel operation is performed by convolution kernel shift under pipeline coordination. A fast pipeline weld image processing algorithm is realized, which gives full play to the advantages of FPGA computing speed. Experiments show that for a 600 × 400 image, in the environment of a clock frequency of 100 MHz, it only takes 9.56821 ms from pixel reading to image processing completion. Compared with the general computer, the image processing algorithm has a great speed improvement. The algorithm can effectively improve the execution efficiency of image processing and can be used for high real-time pipeline weld image processing.
A high light vision measurement method based on adaptive fringe projection
MA Jun, ZHANG Fengmin, DUAN Chunyan, ZHANG Chunjie, GUO Chunsheng, WANG Yongsheng
2023, (7): 169-175. doi: 10.19287/j.mtmt.1005-2402.2023.07.026
[Abstract] FullText HTML PDF(2051KB)
Abstract:
In fringe projection profilometry, highlighting usually results in saturation of captured fringes and decreases measurement accuracy. In order to solve this problem, a new adaptive fringe projection method is proposed. The solid geometric phase solution method provided by binocular camera was used to reduce the number of fringe projections and improve the efficiency of adaptive projection. The intersection ratio invariant constraint is adopted to improve the corresponding accuracy between projector and camera. Compared with the traditional monocular FPP reconstruction results, the standard deviation of the fitting plane is reduced by 0.049 mm, and the flatness is increased by 84.5%. The distance between the front and rear surfaces is 8.829 mm, and the error with the standard value is 0.045 mm, which increases by 42.3%. The proposed method realizes the complete extraction of phase information in the local overexposure area, and effectively solves the problem of 3D shape measurement of highly reflective objects. Compared with the traditional FPP method, the reconstruction result is obviously improved, which shows the effectiveness of the improved algorithm in this paper.
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