制造技术与机床

Fault diagnosis of rolling bearing based on visual spectrum signal feature extraction

ZHOU Jianmin, HUANG Xiliang, XIONG Wenhao, WANG Yunqing, XIA Xiaofeng

2022, (9): 5-12. doi: 10.19287/j.mtmt.1005-2402.2022.09.001

[Abstract] FullText HTML PDF(1982KB)

Abstract:
Aiming at the problem that the traditional fault feature extraction method of rolling bearing is easy to be disturbed by external noises and contains a lot of redundant information, a fault diagnosis method of feature extraction of visible spectrum signal was proposed. Firstly, the vibration signal is converted into viewable map signal, the adjacency matrix and Laplace matrix of each visual map signal are calculated, and various map indexes are obtained. The appropriate fault features are selected as the fault feature vector by using the double sample Z-value method. Finally, support vector machine (SVM) classification algorithm for bearing fault diagnosis classification results. The experimental analysis shows that, compared with the traditional fault feature extraction method, for different types of fault diagnosis of rolling bearing, the accuracy of fault feature extraction method based on visual map signal is improved by 8.34%; In order to further prove this method, for different degrees of fault diagnosis of the outer ring of rolling bearing, the accuracy of this method is improved by 16.67%, which shows the superiority of the signal feature extraction method based on visual spectrum .

FTA-based analysis of the parameters influencing the failure of gear-shaft interference couplings

GONG Qingshan, XU Hao, GUO Qinghe, LV Jiang, CAO Zhanlong

2022, (9): 13-19. doi: 10.19287/j.mtmt.1005-2402.2022.09.002

[Abstract] FullText HTML PDF(1829KB)

Abstract:
The failure tree analysis method was used to analyse the failure parameters for the gear fracture failure problem occurring in the gear-shaft interference coupling. A fault tree analysis model was established to identify the various potential factors of failure, and the importance of each factor was analysed to find the five main influencing factors of interference, friction factor, press-fit speed, assembly deviation and shape error. A transient dynamic analysis of the gear-shaft interference coupling system was carried out using the finite element method to study the stress influence law of the five main factors. The results show that the contact stress between gear and shaft increases with the increase of interference and friction factor, but does not affect the trend of stress distribution; the increase of assembly deviation and shape error will increase the contact stress, and the press fitting speed has almost no effect on the contact stress.

Research on rotating machinery fault diagnosis based on SPGAP-ResLSTMnet

XU Min, WANG Ping

2022, (9): 20-26. doi: 10.19287/j.mtmt.1005-2402.2022.09.003

[Abstract] FullText HTML PDF(1954KB)

Abstract:
Accurate and timely diagnosis of rotating machinery faults can avoid economic losses and even casualties. Based on this, a SPGAP-ResLSTMnet fault diagnosis method for rotating machinery is proposed in this paper. The method combined multi-manifold LSTM elements, which can remove repeated data in time and save the required data. The combined residual structure can effectively alleviate the gradient dispersion problem caused by the increase of network layers, so as to fully extract fault features. GAP and ELM are used to achieve efficient and accurate fault classification. Case Western Reserve University laboratory data set is selected to complete the comparative experiment between the proposed method and the methods[3,6]. The results show that the proposed method has higher recognition accuracy for normal signals, rolling body,inner and outer ring fault signals under various loads and different pits, as well as noisy signals in comparison with methods[3,6]. In addition, higher accuracy and lower loss values can be achieved with fewer training sessions by our method.

Research on calibration method of tool coordinate system for robot measurement system

LIAN Shaoxun, NAN Xiaoxuan, WANG Zhurong, XI Wenming

2022, (9): 27-32. doi: 10.19287/j.mtmt.1005-2402.2022.09.004

[Abstract] FullText HTML PDF(2163KB)

Abstract:
Constructing robot simulation system and calibrating robot end tools can improve robot machining accuracy and realize fast trajectory programming. In this paper, the mirror relationship between the actual robot system and the robot simulation system is used to calibrate the end tool of the robot. Firstly, a calibration probe was installed at the end of the robot to measure the position and pose of the cuboid calibration block of known size in the robot space, and the image model of the cuboid was established in the robot simulation system. Secondly, the position and pose of the tool model relative to the end of the robot model are adjusted under the condition that the position and pose of the tool model relative to the edge and face of the cuboid model are consistent with that of the tool model relative to the edge and face of the cuboid model, and the mirror relationship of the tool model in the two systems is established. Finally, a calibrated tool is used to measure the blank, and the image of the blank is built by the measurement matrix in the simulation system, and the tool path conversion is realized in the simulation system. The experimental and practical machining results show that the calibration method has the advantages of simple calibration process and high calibration precision, and the dislocation error of two-way through groove machining is less than 0.73 mm.

Kinematics analysis and simulation of large marine propeller insertion milling robot

WANG Lin, ZHANG Chunyan, QUAN Hongjie, ZHANG Shengwen

2022, (9): 33-39. doi: 10.19287/j.mtmt.1005-2402.2022.09.005

[Abstract] FullText HTML PDF(2187KB)

Abstract:
A design scheme of 4-DOF robot for insert milling was proposed, and the 3D structure model of the robot was established. The improved D-H parameters were used to establish the kinematics model of the robot, and the forward and inverse solutions of the robot kinematics were obtained. Based on the kinematics model, the simulation model of the robot is established with the help of Matlab toolbox. Monte Carlo method was used to calculate the reachable space of the robot's end cutter. The robot's trajectory was planned under the conditions of given initial and final positions of the robot, and compared with the profile of the propeller blade surface. The results show that the workspace of the robot terminal cutter is consistent with the surface profile of the large propeller blade, and the trajectory planning is reasonable, which can meet the actual machining requirements.

Research on structural design method of drilling end-effector for aircraft components based on neural network algorithm

WU Chengxu, LEI Pei, SUN Hailong, TAN Hong, CHEN Qiang, ZENG Chao

2022, (9): 40-46. doi: 10.19287/j.mtmt.1005-2402.2022.09.006

[Abstract] FullText HTML PDF(1854KB)

Abstract:
Drilling end-effector is the main function integrated equipment for automatic drilling of aircraft components, and its design method has a significant impact on the drilling process. Starting from the part of structural design, based on the neural network fitting algorithm, 80 groups of 5-Dimensional vector sample data including three types of frame components material, displacement and mass are used to train the network model with a mean square value MSE of 0.06, and the key dimensional parameters of the end-effector frame through prediction are obtained, and then the topology optimization method is used to design for lightweight of the frame components. Before topology optimization, the maximum deformation of the frame structure under actual working conditions is 0.04 mm, the maximum stress value is 44 Mpa, and the requirements of the stiffness and strength are met; Under the same working condition, the maximum deformation of the frame structure after topology optimization is 0.026 mm and the maximum stress value is 42 MPa. While the mass is reduced by 43%, the performance of the frame structure of the drilling end-effector is also improved. The prediction of the key dimension parameters of the frame based on the neural network fitting algorithm makes the empirical judgment is no longer simply relied on to design, and the new idea and method for the structural design of the end-effector is developed.

Robotic grinding posture smoothing optimization for triangular mesh surface

JIN Xin, LIU Qiguang, LV Jie, XU Feifei, SUN Xiaonan

2022, (9): 47-51. doi: 10.19287/j.mtmt.1005-2402.2022.09.007

[Abstract] FullText HTML PDF(1528KB)

Abstract:
At present, robotic grinding theory for mesh surfaces has been widely studied. However, existing methods often have the problem of poor smoothness, as well as neglecting the local differential characteristics of mesh surfaces. Therefore, in this paper, a robotic grinding posture smoothing optimization algorithm based on mesh surface and quaternion interpolation is proposed. Firstly, the local differential characteristics of mesh surface is reconstructed by estimating the normal vector of mesh surface and fitting the local geometric characteristics of mesh surface, in order to obtain the corresponding curvature information. Then, identification of key areas of the grinding process is conducted on basis of the obtained local differential characteristics, and key grinding postures are assigned at those grinding points with locally maximum curvature. Next, the technique of quaternion interpolation is performed among those assigned grinding postures to optimize motion smoothness and to improve the uniformity of grinding. The simulation experiment and practical grinding test have been carried out, and the results show that the proposed algorithm can generate smoother grinding postures along the path with less fluctuation, and can accommodate well with the changes of curvature on triangular surface, which ensures the smoothness of grinding and the uniformity of the surface after grinding.

Task planning and experiment of robot auto-locking screw

LIU Peng, QIN Tao, YU Weiwei, LI Bo

2022, (9): 52-56. doi: 10.19287/j.mtmt.1005-2402.2022.09.008

[Abstract] FullText HTML PDF(1641KB)

Abstract:
Aiming at the problems of low work efficiency and low degree of automation in locking screw assembly in industrial automation production, For the automation needs of screws and screw plates auto-locking loading and unloading, automatic locking screw assembly, and so on, A robotic auto-locking screw assembly system was designed, the components and working principle of the system were introduced,the realization path of the automatic locking screw assembly task was planned.The hardware and software of the controller of the robotic auto-locking screw assembly system were designed and the I/O address configuration was made, the robotic auto-locking screw assembly control program was Wrote, the goal of robot auto-locking screw assembly was achieved. Finally, the number of automatic locking screw assemblies through continuous experimental testing was counted. the work efficiency was Analyzed, and the feasibility of robot automatic locking screw assembly was verified. the engineering has a certain value.

Analysis of static stiffness characteristics of parallel mechanisms based on stiffness matrix method

ZHU Chunxia, SUN Jianing, ZHAO Yuan

2022, (9): 57-61. doi: 10.19287/j.mtmt.1005-2402.2022.09.009

[Abstract] FullText HTML PDF(1004KB)

Abstract:
Stiffness is one of the important characteristics of the parallel mechanism. Taking the 3-TPT parallel mechanism as the research object, the static stiffness is solved by the stiffness matrix method. The static analysis is carried out using the principle of virtual work, and the statics Jacobian matrix is solved to deal with the connection between the power and the load of the parallel mechanism when the force is balanced. At the same time, the stiffness matrix method is used to construct the static stiffness model of the mechanism, and the stiffness of the branch chain and the whole of the mechanism is solved. Through research, it is found that the active part has the greatest influence on the stiffness of the branch chain; and when the external force on the end is determined, the force deformation of its end decreases with the increase of the x, y, z coordinates of the force point. This pair of parallel mechanisms provides a theoretical basis for design in production practice.

Study on multi-cutting process of copper tungsten alloy tool electrode by WEDM

LI Wenming, ZHOU Changwu

2022, (9): 62-68. doi: 10.19287/j.mtmt.1005-2402.2022.09.010

[Abstract] FullText HTML PDF(3224KB)

Abstract:
Copper tungsten alloy tool electrode has excellent processing performance in EDM, and WEDM multiple cutting is an important technical method for tool electrode manufacturing. The influence of the first cutting pulse width, peak current and servo voltage on the cutting speed was studied by response surface method, and the combined process parameters under the maximum cutting speed were optimized. On this basis, the influence of different cutting times on the machining quality of tool electrode was studied. The results showed that when the first cutting pulse width is 50 μs, the peak current is 12 A and the servo voltage is 12 V, the maximum cutting speed is 25.08 mm²/min. Moreover, the dimension error of one cutting is less than 10 μm and the surface roughness is Ra 2.582 μm. The dimension error of secondary cutting is less than 5 μm, the surface roughness is Ra 1.177 μm. The dimension error of three times cutting is less than 3 μm, the surface roughness is Ra 0.732 μm. With the increase of cutting times, the carbon deposited on the cutting surface increases, which helps to improve the low loss performance of the electrode.

Research on key technology of EDM milling for diffuse film hole of air turbine blade

WANG Haojie, CAO Ziyang, ZHANG Yangjing

2022, (9): 69-76. doi: 10.19287/j.mtmt.1005-2402.2022.09.011

[Abstract] FullText HTML PDF(2443KB)

Abstract:
According to the processing requirements of the complex three-dimensional micro-cavity in the processing of the diffused air film hole of the Inconel 718 aviation turbine blade, the micro-EDM milling process is adopted. The influence of key processes such asservo acceleration and deceleration control on the profile of the longitudinal and cross-section of the three-dimensional structure is studied. A general mathematical model of the bottom surface profile of EDM milling is established, and MATLAB is used to simulate and analyze the influence of different initial layer thicknesses on the bottom surface of the profile. he initial machining depth of 0.005 mm was obtained through experiments, and the longitudinal section of three-dimensional diffusion film hole with surface profile less than 0.01 mm was processed. Aiming at the 90° large turning angle existing in the transverse section of the three-dimensional structure, the hybrid S-type servo feed control strategy is adopted to reduce the concave transverse section caused by the excessive speed drop at the 90° turning angle, The transverse section of high precision diffusion film hole is obtained through experiments.

Positioning system of aerospace monolithic reinforced frames based on digital twin

TANG Wenxian, WU Fengfeng, WU Tian

2022, (9): 77-81. doi: 10.19287/j.mtmt.1005-2402.2022.09.012

[Abstract] FullText HTML PDF(1281KB)

Abstract:
In order to improve the controllability and real-time during the positioning process of aerospace monolithic reinforced frames, the positioning method of aerospace monolithic reinforced frames based on digital twin is proposed. The digital twin models of the positioned object and the flexible tooling are created, based on the process number that correspond to the assembly progress and the feedback on the state data of the end positioners on flexible tooling and the aerospace monolithic reinforced frames in practice. The magnitude of the contact forces and the coordinates of the monitoring points are analysed by “ANSYS” software, the positioning quality can be predicted, and the adjustment value can be optimized. In order to guarantee the adjusting movement for the design requirement and the operating security in practice, the adjusting movement of the end positioners on flexible tooling is monitored by “Unity3D” software. The controllability and real-time during the positioning process of aerospace monolithic reinforced frames can be improved.

Design of digital platform for multi axis linkage steering system based on Python

CHEN Jun, LAN Xi, KANG Shaopeng, QIANG Hongbin, LIU Kailei

2022, (9): 82-89. doi: 10.19287/j.mtmt.1005-2402.2022.09.013

[Abstract] FullText HTML PDF(2014KB)

Abstract:
With the rapid increase of transportation and construction tasks of various heavy equipment and large components, the demand for large carrying equipment is increasing. Aiming at the design problem of steering linkage system of modular axis transport vehicle, a digital design method of steering linkage system is proposed. Based on the theory of the connecting rod steering system of multi axis vehicle, the function modules of SolidWorks and the optimization algorithm of MATLAB are developed and called by python, the digital design platform of the connecting rod steering system is established, and the graphical user interface of human-computer interaction is designed. The hole position layout of the connecting rod steering system can be optimized and adjusted according to the needs of users, so as to realize the optimal steering angle, and the parameters are transmitted to the three-dimensional model, Realize parametric design and automatic assembly. Taking the three-axis connecting rod steering system as an example, the parametric design and optimization are carried out. The angle error is reduced to less than 2.4°, which improves the steering accuracy of the axis vehicle. The design efficiency is increased by about 45%.

Research on cutting force prediction in milling process based on StackNet

WANG Zhenghuan, ZHANG Chaofeng

2022, (9): 90-96. doi: 10.19287/j.mtmt.1005-2402.2022.09.014

[Abstract] FullText HTML PDF(1368KB)

Abstract:
In order to analyze the cutting force prediction in the milling process of titanium alloy materials, a method based on multi-layer StackNet network structure is proposed to predict the cutting force. Firstly, the milling experiments of titanium alloy with different speed, feed rate and axial cutting depth are carried out on VMC600 machining center, and the collected experimental data are predicted and analyzed by StackNet. Secondly, the single model and the 2-layer StackNet structure of the two different methods are used to carry out prediction analysis. In the case of clarifying the prediction advantages of two-layer StackNet, we conducted the research of StackNet with different layers furtherly. The results of the prediction experiments show that the prediction effect of multi-layer StackNet structure is improved by 78.19%. When the number of network layers is 6, the prediction accuracy is the best. The multi-layer StackNet structure is used to predict the change of cutting force in the process of aluminum alloy milling, which provides an important reference for the rational formulation of machining technology.

Research on intelligent workshop production management system based on disturbance event

MAO Kefu, YUAN Minghai, SUN Chao, PEI Fengque, GU Wenbin

2022, (9): 97-103. doi: 10.19287/j.mtmt.1005-2402.2022.09.015

[Abstract] FullText HTML PDF(1784KB)

Abstract:
Intelligent workshop heterogeneous manufacturing resources and workshop disturbance are complex. Moreover, production service modules are more diverse and complex, so in order to realize the clear management of different functional modules in the workshop, design and development of an intelligent workshop production management system based on disturbance events is particularly important. According to users’ requirements for uniqueness and timeliness of products, the business flow and overall architecture of intelligent workshop scheduling management system based on disturbance events were proposed. Using B/S(Browser/Server) architecture, and based on VisualStudio.NET integration platform, using WebASP.NET database development, five functional modules to realize the full use of workshop manufacturing data information were designed, and the main functional interface of the system was displayed.The feasibility and rationality of intelligent manufacturing workshop monitoring and processing abnormal event and production scheduling model are verified.

Research on intelligent detection technology of micro threaded hole defects based on machine vision

LIN Jie, XUAN Hanyu, SONG Xueyong, ZHAO Min

2022, (9): 104-110. doi: 10.19287/j.mtmt.1005-2402.2022.09.016

[Abstract] FullText HTML PDF(2118KB)

Abstract:
Aiming at the problem of micro threaded hole quality detection in micro structure, an intelligent detection method is designed in this research for micro threaded hole defects based on machine vision through the research of image acquisition, data transmission, classification of various defects, defect image storage and analysis technologies involved in machine vision. This paper not only introduces the design method of the hardware system of the detection method, such as camera, lens and so on, but also introduces the thread detection algorithms and software design methods, such as the measurement algorithm of thread diameter, the detection algorithm of thread turns and so on. Finally, through experimental research, the progressiveness and feasibility of this technology method are verified, which lays a theoretical and experimental foundation for the popularization and application of this technology.

Application research on visual inspection and compensation of electrode wear in robotic spot welding

TONG Zhou, HAN Wei, TAN Yi, ZOU Hao

2022, (9): 111-116. doi: 10.19287/j.mtmt.1005-2402.2022.09.017

[Abstract] FullText HTML PDF(1796KB)

Abstract:
Aiming at the problem that the welding quality was affected by the reduction of the actual contact area between the electrode and the plate workpiece, and by the variation of the discharge distance and the density, because of the electrode length, electrode shape and the progressive insertion of the electrode rod after repeated grinding. The work process of FANUC robot spot welding electrode grinding, replacement and compensation was analyzed, and the function of visual technology to detect electrode grinding amount, electrode amount, electrode rod embedded amount and generate electrode work history database was studied. The FANUC macro program was used to compensate for the wear and tear of the electrode head grinding and the embedded amount of the electrode rod to ensure the stable and accurate electrode position of each welding spot. The robot resistance welding quality and refined management level were improved by management and control of electrode grinding accuracy and replacement loss cost.

Research on automatic assembly system based on machine vision

HUANG Bo, ZHAO Fei, WANG Jia, HE Qingzhong, WANG Yufeng

2022, (9): 117-122. doi: 10.19287/j.mtmt.1005-2402.2022.09.018

[Abstract] FullText HTML PDF(1817KB)

Abstract:
In the assembly process, most enterprises (especially small and medium-sized enterprises) use manual assembly at present, which results in large amount of labor and low assembly efficiency. Taking yb100 rotor oil pump as the research object, the 3D structure of virtual prototype is designed by SolidWorks software, the camera internal parameter calibration is done by Halcon, the hierarchical system control and human-computer interaction platform are built, and the physical construction and assembly process description are completed. Finally, through the calculation of repeatability test and the experimental analysis of assembly time, it can be concluded that the repeated positioning accuracy of automatic assembly is 0.02mm, and according to the positioning time of test parts, it can be concluded that each part is within 500ms, which meets the requirements of oil pump assembly in accuracy and efficiency.

Fractal model of contact thermal conductance of the joint surface based on semi-ellipsoid asperity

ZHAO Hailu, ZHANG Xueliang, XU Yongtai

2022, (9): 123-130. doi: 10.19287/j.mtmt.1005-2402.2022.09.019

[Abstract] FullText HTML PDF(1617KB)

Abstract:
Based on the K-E model and three-dimensional fractal theory, the contact point of the contact surface was extended to an ellipse, and a fractal model of the contact thermal conductance of the joint surface was established considering the elastic, elastic-plastic and plastic deformation mechanism of the semi-ellipsoid asperity. Based on the built model, the effects of elliptical eccentricity, fractal parameters, and normal load on the contact thermal conductance of the joint surface are studied, and the simulation results show that the contact thermal conductance of the interface in which the asperity is semi-ellipsoid increases with the increase of elliptic eccentricity, the fractal dimension, normal load and contact ratio, but decreases with increase of the fractal roughness parameter. Compared with the contact thermal conductance of hemispherical asperity, the built model is more suitable for the case of large normal load. The simulation results of the built model are also compared with the experimental data to verify the correctness of the built model, which provides a certain theoretical reference for solving the contact thermal conductance of the joint surface in practical engineering.

Research on characteristics of chip formation and milling force fluctuation of Ti40 burn resistant titanium alloy

LV Dongsheng, WANG Baosheng, HOU Junming

2022, (9): 131-136, 142. doi: 10.19287/j.mtmt.1005-2402.2022.09.020

[Abstract] FullText HTML PDF(2307KB)

Abstract:
Ti40 burn resistant titanium alloy is one kind of beta phase titanium alloy. There existed complex cutting deformation, higher cutting temperature, higher cutting force and fluctuations, and serious tool wear and damage in the process of machining Ti40 alloy. In this paper, the chip formation characteristics, chip formation mechanisms and their relationships with dynamic fluctuation force of Ti40 beta titanium alloy are analyzed. It is shown that shear bands are formed inside the deformation of each beta phase grain, its chip thickness varies irregularly, and there exists micro-serrated teeth and micro-cracks on the serrated chips. With cutting speed increasing, the formation frequency of adiabatic shear bands is lifted, notable serrated teeth are formed and the sub-grains are formed more obvious and fine among adiabatic shear bands. At peaks of milling force, notable fluctuation is shown, and the fluctuation times and amplitude are corresponded to the formation of notable serrated teeth. The fluctuation of milling force is caused by adiabatic shear and cutting direction change due to vibration.

Aerospace hexagon socket screw fuse hole improved design of special processing equipment

WANG Lihua, ZHAO Chun, QIAO Yuanpeng

2022, (9): 137-142. doi: 10.19287/j.mtmt.1005-2402.2022.09.021

[Abstract] FullText HTML PDF(1276KB)

Abstract:
In view of the characteristics of aviation fastener hexagonal screw fuse hole (mostly nickel cobalt titanium material) which is easy to wear, easy to break, high processing cost and low efficiency. The high-speed EDM numerical control small hole machine tool is selected for improvement. Based on Mitsubishi FX3U series PLC, the automatic feeding and unloading clamping and indexing device for the hexagonal screw fuse hole of aviation fasteners is designed and developed. It has the functions of automatic feeding and unloading, automatic clamping and indexing according to requirements in the processing of hexagonal screw fuse hole, solves the problem that the hexagonal screw fuse hole is difficult to process, and greatly improves the production efficiency.

Analysis of metal flow characteristics in extrusion process of thin wall aluminum profile

HUANG Xuemei, PAN Dewen, LIN Yafang, LUO Yiru, DENG Rurong

2022, (9): 143-147. doi: 10.19287/j.mtmt.1005-2402.2022.09.022

[Abstract] FullText HTML PDF(1667KB)

Abstract:
With the increasing demand for thin-walled extruded profiles, it is necessary to understand the metal flow of aluminum bars and the metal flow into the die holes. Through the experimental method, the metal flow of aluminum profile extruded with simple thin-walled section is discussed.The results show that different flow patterns and material properties can be obtained by changing extrusion speed, temperature and wall thickness. The experiment provides the technology of using the contour map to represent the metal flow under different magnification; in different stages of extrusion, the state of the metal in the process of extrusion can be understood by testing the grain size, shape and orientation. Through the experiment, the main factors influencing the metal flow in the extrusion process of thin-walled section are obtained.

Research and application of 3D assembly process planning system based on MBD

ZENG Fenfang, DU Kunpeng, WANG Huachang

2022, (9): 148-152. doi: 10.19287/j.mtmt.1005-2402.2022.09.023

[Abstract] FullText HTML PDF(1260KB)

Abstract:
The 3D assembly process in the form of animation, audio and text, expresses the assembly process and assembly requirements vividly. As a result, workers could easily understand and improve the quality of assembly, and the information is not ambiguous. This paper studies focuses on how to use the information in the 3D model to complete the 3D assembly process effectively. Firstly, basing on the studies about MBD technologies, it establishes the MBD-based assembly information model. Secondly, it advances “disassembly definition assembly”, to plan assembly activities. The disassembly activities are summarized into spiral movement, linear motion and other types of disassembly activities, through the order of disassembly activities, the attributes of disassembly activities to do “reverse operation” to define the assembly activities. Finally, based on the MBD-based assembly information model and the “disassembly definition assembly” mode, the 3D assembly process planning system is developed to verify the feasibility and rationality of the scheme through the application of manufacturing enterprises, shorten the assembly process design cycle, and improve assembly′s efficiency and quality.

Thermal error prediction of machine tool spindle based on GA-ACO-BP network

TIAN Chunmiao, JI Zeping, A Yongga, ZHANG Xuewei, TANG Shufeng, GUO Shijie

2022, (9): 153-161. doi: 10.19287/j.mtmt.1005-2402.2022.09.024

[Abstract] FullText HTML PDF(1810KB)

Abstract:
In order to solve the shortcomings of the spindle thermal error prediction model established by back propagation (BP) neural network, such as low accuracy, slow convergence speed and easy to fall into the local optimal solution, the K-means++ algorithm and correlation analysis were used to optimize the temperature measurement points and extract the thermal sensitive points, and the genetic algorithm (GA) was used to cross-variation the ant colony. GA-ACO network was constructed to determine the optimal number of hidden layer nodes, weights and thresholds, so as to realize the optimization of BP neural network topology. The thermal error prediction models of spindle based on BP and GA-ACO-BP networks were established, and the thermal error of spindle was measured by five-point method with the five-axis machining center of double turntable as the research object. The thermal error experiment results show that the K-means ++ algorithm combined with Person, Sperman and Kendall correlation analysis can effectively reduce the multicollinearity between temperature variables. Ga-aco-bp model can predict the thermal error of spindle with higher accuracy.

Weld width measurement system design based on STM32

LI Guohong, QIAO Ze

2022, (9): 162-166. doi: 10.19287/j.mtmt.1005-2402.2022.09.025

[Abstract] FullText HTML PDF(1254KB)

Abstract:
In order to reduce the human participation in specific welding situation, realize welding automation. With STM32 and OV2640 as the core hardware, a weld width measurement system is designed. The RGB565 format image returned by the camera is received through its own DIGITAL camera DCMI interface. Then the image is processed by graying, binarization and regional marking algorithms, and finally the pixels between the two steel plates are counted in real time. The actual distance between the two plates was calculated. Experimental data show that the measurement error of the system can be controlled within 2%, and high precision weld spacing measurement can be achieved, which provides necessary data for the subsequent realization of welding automation, and is expected to be applied in practical engineering.

The analysis and compensation experiment analysis of error identification and compensation of rotary axis in space with six azimuths

ZHANG Ying, YU Bo, HU Yue

2022, (9): 167-172. doi: 10.19287/j.mtmt.1005-2402.2022.09.026

[Abstract] FullText HTML PDF(1359KB)

Abstract:
The literature investigates that the six-axis spatial error of the rotary axis, which affects the machining accuracy of the five-axis CNC machine tool, is a key problem that needs to be solved urgently in the current motion axis. Mathematical basic theory modeled and analyzed the spatial six-azimuth errors of the rotary axis, obtained the magnitude and mutual influence of the six-azimuth errors of the rotary axis, and applied the dual-frequency laser interferometer angle detection component to carry out the online detection of the rolling errors of the rotary axis. With identification calculation, the existing characteristics of roll error are summarized, an adaptive compensation method is proposed, and a roll error compensation model is established. Experiments show that the researched identification theory and compensation method are effective and feasible. The variance has been reduced to 2.769×10⁻², which can meet the motion requirements of high-precision five-axis CNC machine tools.

Position-dependent geometric error detection and identification of swing axis for beam mobile five-axis gantry milling machine tool

WU Changjun, ZHENG Mingming, WANG Qiaohua, FAN Jinwei, WANG Liangwen, SONG Xiaohui

2022, (9): 173-180. doi: 10.19287/j.mtmt.1005-2402.2022.09.027

[Abstract] FullText HTML PDF(2703KB)

Abstract:
The beam mobile five-axis gantry milling machine tool is a kind of high-speed milling machine tool with double-swing head five-axis, which is suitable for large and heavy workpieces, as the end of the machine tool transmission chain, its swing axis is directly connected with the cutting tool. Therefore, the position-dependent geometric error detection and identification of swing axis is of great significance to improve the machining accuracy of the large five-axis machine tool. Took the XKAS2525×60 five-axis gantry milling machine tool as the research object, established the kinematic model of the machine tool swing axis (B axis) by using the multi-body system theory, and the geometric error identification model of machine tool swing axis is established based on the double ballbar. Finally, through the experiment, six position-dependent geometric errors of B-axis are detected and identified, and the experimental results were analyzed by regression and comparative. The results show that the proposed method for the geometric error detection and identification of machine tool swing axis is reliable and effective, the results of detection and identification are correct.

Download CenterMore

LinksMore

2022 No. 9

Journal DynamicsMore

Top ViewMore