制造技术与机床

RV reducer fault diagnosis based on order tracking and improved wavelet threshold noise reduction

LIN Mengxiong, WANG Shuang, WEI Keji, ZHANG Xianghui, CAO Hongxin, ZHANG Jingcai

2022, (11): 9-14. doi: 10.19287/j.mtmt.1005-2402.2022.11.001

[Abstract] FullText HTML PDF(1997KB)

Abstract:
In view of the characteristics of the vibration signal collected during the swing fatigue test of the RV reducer, the vibration source is complex, the noise influence is strong, and the nonlinear transformation is used. phenomenon, the fault wear point cannot be accurately extracted. In view of the above problems, this paper proposes an order tracking analysis combined with an improved wavelet threshold noise reduction method to extract the fault features of the vibration signal collected during the fatigue test of the RV reducer. Firstly, the collected non-stationary time-domain vibration signal is transformed into the equi-angle domain by the order tracking method; then the equi-angle domain signal is denoised by threshold using the improved wavelet threshold noise reduction method; The signal is subjected to FFT transformation to obtain an order map. Compared with the traditional wavelet noise reduction analysis results, the method can effectively extract the fault information of the internal parts of the RV reducer in the swing fatigue experiment, which provides a basis for the fault diagnosis of variable-speed rotating machinery.

Research on fault diagnosis of self-aligning ball bearing based on FCMMWPE-BSASVM combined algorithm

ZHANG Zhaohan, QI Junping, LI Feng, CUI Jinwei

2022, (11): 15-19. doi: 10.19287/j.mtmt.1005-2402.2022.11.002

[Abstract] FullText HTML PDF(1533KB)

Abstract:
In order to improve the ability of feature extraction and fault identification of allocatable ball bearings in mechanical rotating system, A fault feature extraction method combined FCMMWPE and BSASVM was designed. and Isomap was used for fault identification. And the fault diagnosis case analysis was carried out. The results show that the FCMMWPE algorithm achieves the highest state entropy and forms a smoother entropy curve, and the generalized coarse-grained method has obvious advantages. When local faults occur, vibration signals with regular characteristics are formed, which indicates that FCMMWPE can meet the reliability conditions and has obvious advantages in extracting fault features of self-allot ball bearings. When FCMMWPE and Isomap feature sets constructed in this paper are used for operation fault identification, 99.9% accuracy is achieved, and self-aligning ball bearing fault identification is realized efficiently. BSASVM provides better fault identification performance, pattern recognition performance, and processing efficiency. The research can be extended to other mechanical transmission fields and has good application value.

Workspace analysis and structure optimization of parallel robot

GUO Jianye, LIU Jun

2022, (11): 20-26. doi: 10.19287/j.mtmt.1005-2402.2022.11.003

[Abstract] FullText HTML PDF(3392KB)

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In this paper, 3-TPT parallel robot is taken as the research object, the inverse kinematics solution of the parallel mechanism and the forward kinematics solution of the constraint structure are established, and the expressions of the limit constraints of the connecting rod and hinge are given. Then, the set of workspace points is obtained by numerical method, and the definition of effective workspace is determined according to the actual application environment of parallel robot. Finally, aiming at the maximum volume of effective workspace, the length of connecting rod and the rotation range of restraint structure are optimized based on the basic structure size of parallel robot. The results show that the optimized volume of effective workspace is about 1.5 times of the initial volume.

Kinematics simulation of 6R mechanical arm based on MATLAB

HU Yuhang, ZHANG Shangying, ZHANG Xiaoyan

2022, (11): 27-32. doi: 10.19287/j.mtmt.1005-2402.2022.11.004

[Abstract] FullText HTML PDF(1539KB)

Abstract:
In order to better control the operation of the hydraulic manipulator in industrial production, the 6R hydraulic manipulator is taken as the research object, the improved D-H method is used to model it, and the forward kinematics equation is established. Eight sets of solutions for the angle variables of each joint of the manipulator are obtained. The robotic arm is modeled by Robots Toolbox in MATLAB software, the motion trajectory of the robot was simulated in the joint space, and the smooth curves of angular displacement, angular velocity and angular acceleration of each joint axis with the time were obtained. The simulation results proved that the kinematics equation established is correct and the parameters of the robot are reasonable. It provides the necessary theoretical basis and correct kinematics model for the subsequent motion planning and real-time control of the hydraulic manipulator.

Comparative study on dynamics of redundant parallel robot based on two modeling methods

HAO Liangliang, LIU Xiaojuan, DU Ting, YAN Xianguo

2022, (11): 33-39. doi: 10.19287/j.mtmt.1005-2402.2022.11.005

[Abstract] FullText HTML PDF(1417KB)

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A new type of 2-UPR/2-RPU redundant parallel robot is proposed and used as the research object. The dynamic modeling and dynamic comparison research of it is carried out by using the spiral theory and Lagrangian method. First, the closed vector method is used to establish the kinematic inverse equation of the 2-UPR/2-RPU parallel robot in the global coordinate system; Secondly, the Lagrangian method is used to solve the velocity relationship of each component of the parallel robot and its dynamic model is established; Then, the velocities and accelerations of the joints and rods in the four branches of the parallel robot are analyzed using the screw theory, at the same time, the dynamic model of the parallel robot is established based on the principle of virtual work; Finally, based on the dynamic model of the parallel robot, the algorithm of the parallel mechanism is obtained by programming in MATLAB, and the numerical simulation results of the driving force of each branch chain of the dynamic model is established based on the screw theory and Lagrangian equation are obtained. The simulation verification and error analysis are carried out through the dynamic simulation results with ADAMS software.The results show that the dynamic model established by the screw theory has relatively high accuracy, convenient method and simple calculation, and is more suitable for the establishment of the dynamic model of the parallel mechanism with few degrees of freedom and the control of the mechanism dynamics; it greatly improves the 2-UPR/2-RPU,the response speed and control accuracy of the parallel robot meet the precision requirements of the grinding machine for grinding curved surfaces, which provides a reliable theoretical basis and an important foundation for the practical application of the mechanism.

Design development and experimental research of positioner for industrial robot

CAI Lei, GUO Jianfei, LI Bin, ZHANG Jin

2022, (11): 40-44. doi: 10.19287/j.mtmt.1005-2402.2022.11.006

[Abstract] FullText HTML PDF(1322KB)

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The paper designs a positioner that can coordinate with the robot, and establishes a set of calculation methods and design processes which from the load side to the motor side. The above work mainly includes the formulation of performance indicators, the calculation and selection of reducers and motors, the design and calculation of transmission systems, and use finite element analysis to optimize the structural design of key components. In order to verify the actual performance of the positioner, the experimental test for key parameters is designed and implemented, which has important reference significance for the design and verification of positioner products.

Temperature field simulation of fiber laser cutting Nitinol stent based on ANSYS

LIU Xudong, LI Zhiyong, LIU Yuchen, CHAI Mingxia, WANG Yongqi, GAO Cunfu

2022, (11): 45-51. doi: 10.19287/j.mtmt.1005-2402.2022.11.007

[Abstract] FullText HTML PDF(1868KB)

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In order to study the temperature field distribution in the process of cutting Nitinol cardiovascular stent by fiber laser, a three-dimensional simulation model of Nitinol cardiovascular stent was established by ANSYS finite element software, and the Gaussian heat source was moved along the trail by APDL programming language. The influence of laser power and cutting speed on temperature distribution and variation of different cutting trails was investigated by single factor variable method. The results show that the temperature field distribution of Nitinol tube is almost oval, and the isotherm distribution is dense near the center of heat source, and sparse away from the center of heat source. The cutting area temperature increases with the increase of laser power and decreases with the increase of cutting speed. If the laser power is too high or the cutting speed is too low, the dross will accumulate seriously on the inner surface of the Nitinol tube. When the laser power is too low or the cutting speed is too high, the heat transferred to the tube wall is insufficient, and the workpiece is difficult to cut through. The simulation results can be used to select the actual cutting parameters.

Study on material removal rate and tool wear in EDM of SiCp/Al composite

LIU Yu, QU Jiawei, LI Xiaoming, YAN Changgang, ZHANG Shengfang, WANG Ziguang

2022, (11): 52-58. doi: 10.19287/j.mtmt.1005-2402.2022.11.008

[Abstract] FullText HTML PDF(1507KB)

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SiCp/Al composites are widely used in various fields because they have the combined properties of both aluminium matrix and silicon carbide particles, and therefore have low density, high thermal conductivity and high hardness. However, the high hardness of brittle SiCp/Al composites makes traditional contact machining difficult due to high cutting temperatures, severe tool wear and machining accuracy. In this paper, the effect of material etching rate and electrode loss on the machining of SiCp/Al composites under different machining parameters was investigated on a self-built EDM test bench with SiCp/Al composites, and the reasons for the effect on the machining were analysed in terms of the etching characteristics of the composites.

The simulation and experimental study of the shell structure on laser output power

JI Xiaogang, ZHANG Zhixin, WANG Duan, CHEN Yan, LU Fei, FU Shibin

2022, (11): 59-64. doi: 10.19287/j.mtmt.1005-2402.2022.11.009

[Abstract] FullText HTML PDF(3780KB)

Abstract:
As a precision instrument, the shell structure of the semiconductor laser is crucial to the stability of the laser’s output power. Based on the finite element analysis of the shell with the software ANSYS Workbench, the first 8 natural characteristic frequencies and corresponding vibration modes of the shell have been obtained, and the weak links of the shell have been found. The experiment verifies the effect of the optical path module installed in the weak and non-weak parts of the shell on the output power of the semiconductor laser. The simulation results show that the vibration mode of the shell is characterized by global and local deformation, and the weak links are mainly located at the geometric center of the shell. The experimental results show that the maximum error of the output power is 10% in the weak part while 4% in the non-weak part by comparing the actual output power under different positions of the shell. It provides a reference for optimizing the structure design of the semiconductor laser and improving the stability of its output power.

Multi-conditions and multi-objective dynamic topology optimization of laser cutting machine beam

ZHANG Yu, LIN Yupei, SHU Lei, DONG Junhong

2022, (11): 65-70. doi: 10.19287/j.mtmt.1005-2402.2022.11.010

[Abstract] FullText HTML PDF(2253KB)

Abstract:
Firstly, the vibration system simulation model is established with the servo motor of the laser cutting machine as the vibration excitation source and the vibration response of the laser head as the processing accuracy evaluation parameter. The secondly, the vibration response of the laser head under multiple conditions is calculated by using the IPI and VTF evaluation methods. Then, a multi-condition and multi-objective dynamic topology optimization method is proposed, and the distribution of the beam lightening holes is optimized under the premise of controlling the quality. Finally, through the comparative analysis of the laser head vibration responses of the original beam structure, the beam without lightening holes and the optimized lightening holes under multiple conditions, it is known that: the multi-condition and multi-objective dynamic topology optimization method can reasonably optimize the distribution of the beam lightening holes, which is an effective measure to reduce the vibration response of the laser head and improve the machining accuracy. The above research results not only can provide reference for the analysis of the frequency domain dynamic mechanical properties of the laser cutting machine, but also can provide reference for the matching between the servo motor and structural performance, so have a good engineering application value.

Present situation and analysis of micro drilling of nickel base alloy

ZHANG Haoqiang, ZHANG Ao, WU Yuxin, WANG Xinge, HOU Suoxia

2022, (11): 71-77. doi: 10.19287/j.mtmt.1005-2402.2022.11.011

[Abstract] FullText HTML PDF(1443KB)

Abstract:
Nickel base alloy is widely used in aviation turbine engine because of its excellent physical properties. Many precision parts of aviation turbine engine need to be processed with micro drill. When drilling nickel base alloy, the material work hardening phenomenon is serious, resulting in increased machining difficulty, serious tool wear and affecting the drilling quality. This paper analyzes the difficulties faced by nickel base alloy micro hole drilling, summarizes and discusses the micro drilling mechanism from the aspects of chip formation mechanism, drilling force and torque, drilling heat and drilling temperature, analyzes the wear form, influencing factors and wear mechanism of the bit, and discusses the factors affecting the hole processing quality such as burr, white layer, roundness, from the aspects of tool geometry, tool material some measures to improve the hole processing quality are put forward from the aspects of auxiliary drilling methods.

Research on the algorithm for recognizing chipping of square shoulder milling cutter machining the webs of titanium alloy

MAO Yiyan, JIANG Zhenxi, ZHU Shaowei, LIU Kuan, ZHAO Zhonggang

2022, (11): 78-83. doi: 10.19287/j.mtmt.1005-2402.2022.11.012

[Abstract] FullText HTML PDF(4294KB)

Abstract:
In order to recognize chipping of square shoulder milling cutter effectively which machining the aerospace structural part of titanium alloy,an algorithm for chipping of square shoulder milling cutter is proposed. Firstly,by building a milling test platform for square shoulder milling cutter, a set of experimental protocol is designed. X,Z,Y-direction vibration data of intact and chipping conditions is acquired by performing the experimental protocol. Then, according to the amplitude interference of the idling vibration data, the Y-direction vibration data is selected for calculation of moving average of RMS per revolution. Three eigenvalues are selected as input to the SVM model, and the classification training of the SVM model is obtained by two eigenvalues. Finally, through the vibration data under the same working conditions as identification input, the reliability of the SVM model of square shoulder milling cutter which machining the aerospace structural part of titanium alloy is successfully verified, and its average prediction accuracy is over 97%.

Study on the performance of different tools in high-speed dry cutting of 2219 aluminium alloy

WANG Lili, LIU Xuefeng, CUI Xin, ZHAO Erhua, WANG Xingran, LI Shipeng, QIN Xuda

2022, (11): 84-91. doi: 10.19287/j.mtmt.1005-2402.2022.11.013

[Abstract] FullText HTML PDF(4020KB)

Abstract:
There are a large number of 2219 aluminum alloy cutting requirements in launch vehicle manufacturing process, and its processing efficiency is one of the important factors affecting the manufacturing cycle of fuel tanks. Although 2219 aluminum alloy is a kind of free-cutting-material, the performances of different tools is quite different in their high-speed cutting. In this paper, the changing rules of cutting load, cutting edge morphology and chip morphology with tool wear in the high speed cutting of 2219 aluminum alloy at 1004 m/min are studied with uncoated, aurora DLC coated and diamond coated tools, which are popularly used in the market for aluminum alloy. Results show that the uncoated tool and the aurora DLC coated tool wear faster. As tool wearing, the chip curling effect decreases and the surface roughness increases. There is a lot of adhesion on the tool surface and the shape of cutting edge varies significantly. The diamond coated tools showed a small amount of micro-chipping but no significant wear, maintaining great cutting edge integrity throughout. Based on the comprehensive consideration of tool cost and cutting efficiency, diamond coated tools are the highly recommended with the highest cost performance in 2219 aluminum alloy high-speed dry cutting.

Development of hob design system based on knowledge engineering

YANG Chen, ZHANG Qiaoli, XU Min, LI Xining, LIU Yuzhi

2022, (11): 92-96. doi: 10.19287/j.mtmt.1005-2402.2022.11.014

[Abstract] FullText HTML PDF(1176KB)

Abstract:
With the gear is widely used in precision transmission and other fields, in order to meet the needs of various fields, the kinds of gear are increasing, the precision requirements are improving, and the hob needs to meet the needs of gear processing. There are a lot of interrelated parameters in the hob and the calculation is large, so the design process of the hob is more complicated and difficult, and it is difficult to meet the requirements of the production cycle and accuracy of the hob with the conventional design method. So this paper company in cylindrical spur involute gear hob design experience, developed a hob design based on knowledge engineering system, the system basic parameters of the gear processed by input, use of expert experience formula to calculate the related parameters of gear hob, then generate 3 D models and 2 D drawings of gear hob, reduce the workload of design personnel, The efficiency and precision of hob design are improved. The research and development of the system has great reference value for the digital design and intelligent manufacturing of cutting tools.

Research on knowledge extraction of semi-structured assembly data and construction method of machine tool assembly knowledge graph

YIN Yudong, WANG Baojian

2022, (11): 97-101. doi: 10.19287/j.mtmt.1005-2402.2022.11.015

[Abstract] FullText HTML PDF(1619KB)

Abstract:
If the information of parts and components in the machine tool and the relationship between parts are displayed in the form of graph, which can more effectively learn the information of parts connected around the parts and the positioning details of current parts. It can also assist the assembly of factory CNC machine tools, and solve the current problems of machine tools such as scattered assembly data, non-standard and low assembly efficiency. At present, there are many software describing 3D information of machine tools, so there are many corresponding file formats, which makes it difficult to digitally manage complex assembly products. At the same time, the traditional single connection relationship is difficult to comprehensively depict 3D graphics, so that the efficiency of in-depth learning model in this respect is not high, the knowledge of machine tool model cannot be truly understood, and the knowledge reasoning ability is almost not available. The knowledge graph, in the form of graph, can represent the connection relationship of various model components. The ability to understand knowledge is far beyond the single connection relationship, which can improve the ability of knowledge reasoning. The construction from three-dimensional model to knowledge graph is completed through the steps of machine tool assembly data preparation, assembly knowledge extraction, knowledge reasoning, knowledge storage and knowledge visualization.

Research on automatic NC programming method for slender plane features

LIU Dakun, FANG Xifeng, WANG Nan, ZHANG Shengwen, WANG Zhan, XU Jingying

2022, (11): 102-108. doi: 10.19287/j.mtmt.1005-2402.2022.11.016

[Abstract] FullText HTML PDF(2037KB)

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In order to improve the efficiency and quality of NC programming efficiency and quality for slender planes, an automatic NC programming method was studied. The process information of slender plane feature was obtained in the MBD model and the feature image was generated. The machining reference trajectory extracted from the feature image was optimized. The optimized reference trajectory was projected onto the original feature plane in order to generate tool path and NC codes automatically. Finally, the prototype system based on this method was developed on the NX platform and the key parts of a marine diesel engine were used as the tested objects in this system. The results showed that this method realized the automatic generation of NC programming and reduced the frequent human-cam interaction effectively. Moreover, the NC codes generated by this method, compared with traditional programming method, reduced the processing time by nearly 65% on average.

Contact characteristic analysis of bolted joint on machine tools considering temperature effect

LEI Sheng, MAO Kuanmin, LI Ming, ZHAO Feiyu

2022, (11): 109-115. doi: 10.19287/j.mtmt.1005-2402.2022.11.017

[Abstract] FullText HTML PDF(2263KB)

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Bolt connection is widely used in mechanical equipment and has a significant effect on the mechanical properties of the whole structure. Due to the difference in thermal expansion coefficient of bolt rod and the connect structures, the thermal deformation of bolt rod and connect structures caused by temperature change will change the bolt preload, thus affecting the contact characteristics of the contact surface and the dynamic characteristics of the whole structure. This paper studied the influence of temperature on the contact characteristics of bolted structures based on finite element analysis. The iron material which widely used in machine tools is taken as an example and the contact characteristics of connecting plate thickness, bolt diameter, bolt preload coupling with temperature are studied. The contact characteristics parameter database of bolts was constructed by Kriging interpolation method. The results show that when the thickness of the connecting plate is small, the influence of temperature change on the contact characteristics is not significant. While the change of the contact area and contact pressure will be significantly increased by temperature change when the thickness of the connecting plate increases to a certain value. The temperature change will affect the size of contact area and the average contact pressure when the preload is small, while this influence is not obvious when the preload increases to a certain value.

Thermal characteristic analysis of cross beam in gantry machining center of moving beam

HU Yibo, GAO Zicheng, LI Lijun, ZOU Yang, QIAO Zhidong

2022, (11): 116-122. doi: 10.19287/j.mtmt.1005-2402.2022.11.018

[Abstract] FullText HTML PDF(2404KB)

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Aiming at the problem that the processing accuracy of the plug-in machine is affected by thermal deformation during the work process, the beam structure of a special-shaped plug-in machine of a company in Shenzhen is taken as the research object, based on the theories of theoretical mechanics, material mechanics, thermodynamics, etc., combined with relevant software, the stiffness characteristics of the beam under the joint action of external forces and temperature are studied. Based on the steady-state thermodynamic analysis, transient analysis is carried out, and the temperature field and shape variables of the beam and the slider change with time are obtained through the transient analysis, and the results show that the time when the beam temperature field reaches the steady state is after 1 875 s, and the temperature of the beam varies greatly from 100 s to 250 s. The maximum total deformation of the beam under the combined action of temperature and external force is 0.354 mm, and the shape variable affected by temperature accounts for about 52.9% of the total deformation; By calculating the position change of the center point of the slider and combining the experimental results, it provides a certain reference for the software compensation error and optimization design in the later stage.

Study on the effect of geometric errors of CFRP connection holes on the tensile strength of bolted structures

GAO Xuemin, SHI Dapeng, XU Yanwei, YIN Yinyin, ZHANG Qinying

2022, (11): 123-130. doi: 10.19287/j.mtmt.1005-2402.2022.11.019

[Abstract] FullText HTML PDF(2246KB)

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In this study, the effects of geometrical errors of CFRP countersunk bolt connection holes on the tensile strength of the connection structure are investigated. In order to obtain the stress distribution of the joint structure, the constitutive model of TC4ELI titanium alloy was developed by quasi-static experiments, and the material model of CFRP was established by combining the Hashin failure criterion and the bilinear constitution for the material interface. On this basis, a finite element model of the composite countersunk bolt joint structure was developed, and numerical simulations and experiments were conducted to verify the effects of three major hole-making errors on the mechanical properties of the bolted joint. The results showed that the proposed finite element model can accurately predict the failure pattern and tensile strength of the bolted joint. Secondly, the geometric error of countersink depth has the most significant impact on the final maximum stress value of the jointed structure compared to the error of countersink angle and fillet radius. Meanwhile, the influence of the upper and lower deviation of the countersink hole size on the tensile properties of the bolted joints has an obvious diversity.

Design and application of dynamic balance adjustment fixture for special-shaped eccentric part

GAO Yuan, ZHANG Xiaofei, YANG Peihui, CUI Tao, LI Jie, WU Weihong, ZHANG Peng, WANG Yongguo

2022, (11): 131-136. doi: 10.19287/j.mtmt.1005-2402.2022.11.020

[Abstract] FullText HTML PDF(10553KB)

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In view of the increasing production tasks of the aerospace industry, the research on the efficient processing technology of aerospace engine parts has become one of the important means for enterprises to deliver production tasks. For parts with large machining allowance, high precision requirements and eccentric structure, the dynamic imbalance of parts can be effectively adjusted through the design of special tooling, so as to effectively improve the machining efficiency of parts. For a large part with obvious eccentricity, by adding counterweight and adopting multi-point auxiliary support, the parts are fully restrained, the overall rigidity of the part processing system is increased, and its processing efficiency is greatly improved. The static simulation of the special fixture designed is carried out, the stress and displacement under high speed operation are analyzed, and the actual maximum machining speed of the part after the fixture is introduced is predicted. At the same time, the experimental verification is carried out, and finally the machining efficiency of the part is increased by at least one times.

Quality prediction model and sensitivity analysis of process parameters based on BP-PSO

WANG Feng, WAN Ye, TAO Xiaoliang, ZHAO Shijin, ZHAO Xin

2022, (11): 137-143. doi: 10.19287/j.mtmt.1005-2402.2022.11.021

[Abstract] FullText HTML PDF(1257KB)

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The quality prediction of mechanical products can effectively improve the product qualification rate and improve the efficiency of the factory. Based on the quality traceability and production process data in the electric drive production process, the paper uses the data collected by the MES system of the electric drive production line as the training and test samples, and establishes the BP-PSO electric drive quality prediction model. According to the actual production data, the air tightness monitoring is established as the key quality characteristic, and the key station data is extracted as the input of this model after data correlation analysis, and the air tightness detection value is used as the output. Comparative experiments show that the model has a good improvement over the traditional BP model in terms of average absolute error and average absolute error percentage, and can accurately predict the production quality. On the basis of this model, the total sensitivity and first-order sensitivity of production process parameters are obtained and sorted by Sobol global sensitivity analysis method, and the influence of production process parameters on production quality is analyzed.

Research on deformation control method during the machining of turbine disk fir-tree slot

YU Jianhua, LI Xun, DING Zhichun

2022, (11): 144-149. doi: 10.19287/j.mtmt.1005-2402.2022.11.022

[Abstract] FullText HTML PDF(2307KB)

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Internal residual stress formed during powder metallurgy preparation of turbine disk blank. It was an important factor affecting the dimensional accuracy and service stability of fir-tree slot. After analyzing the mechanism of deformation caused by material residual stress in machining process, this paper puts forward the combined machining technology of deformation control of "WEDM + Grinding". According to the machining deformation characteristics of fir-tree slot, V-groove experiment was designed to measure the residual stress deformation law of turbine disk. Furthermore, the machining technology of using large margin coarse cutting to release stress and then using small margin precision cutting to repair deformation was put forward. This method can effectively control the residual stress and deformation in tenon groove machining and ensure the uniform margin in grinding process. The remelting layer was removed by grinding and the precision was ensured so that the fine machining allowance of turbine disk mortise and groove can be well consistent. Finally, the grinding accuracy was improved by more than 50% compared with the design requirements.

Development of geometric location errors compensation system for power skiving

XUE Feng, LIN Xiaochuan, HONG Rongjing, HU Min

2022, (11): 150-155. doi: 10.19287/j.mtmt.1005-2402.2022.11.023

[Abstract] FullText HTML PDF(4090KB)

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For the geometric errors generated during the manufacturing and assembly of numerical control power skiving machine tool, a system for automatically generating geometric location error compensation code is developed. Firstly, based on the principles of gear power skiving and the homogeneous coordinate transformation to establish the kinematic chain of machine tool, and the skiving forming function is obtained. Then, the forming function is solved by the actual inverse kinematics error compensation method. Finally, functional modules of software were analyzed, using Qt cross-platform development framework to design interface, using C++ write program, and developing an geometric location errors compensation system for power skiving. The system can realize the calculation of tool parameters, workpiece parameters and the automatic generation of G code for geometric location errors compensation. Through VERICUT simulation processing, the correctness of the system is verified. The results show that the gear accuracy after compensation is improved. The development of this system provides a theoretical and practical basis for realizing the automatic compensation of geometric errors.

Health prediction of rolling bearing based on digital twin

TA Yuntian, CUI Jie, WANG Jinta, YANG Ningning, HAN Fei, LI Fuguo

2022, (11): 156-162. doi: 10.19287/j.mtmt.1005-2402.2022.11.024

[Abstract] FullText HTML PDF(1979KB)

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The health status of rolling bearings largely determines the reliability level of mechanical equipment. The health state prediction of rolling bearings can help the safe operation of mechanical equipment. Therefore, this paper proposes a real-time prediction method of the remaining life of rolling bearings based on digital twin. Firstly, the method is based on digital twin technology means to obtain real-time sensing information of rolling bearings, so as to establish a digital twin model of rolling bearings considering real-time working condition changes. Secondly, a remaining life prediction model considering the measurement error is established by non-linear Brownian motion. Then, the unknown parameters in the model are solved by using the great likelihood estimation method, and the parameters are updated in real time by using Bayesian theory, so that the remaining life of the rolling bearing can be predicted in real time. Finally, the feasibility and effectiveness of the method are verified by analyzing the information of the whole life cycle of rolling bearings.

The parameters of four-point contact peach groove ball bearing are simulated and redesigned by orthogonal experiment method and response surface method

GAO Fusheng, JIA Ruichao, JIANG Shufeng, YAN Chaojun, WANG Junfeng

2022, (11): 163-168. doi: 10.19287/j.mtmt.1005-2402.2022.11.025

[Abstract] FullText HTML PDF(1179KB)

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According to the needs of the four-point contact peach groove ball bearing life improvement problem, taking the four-point contact ball bearing in a lathe servo motor as the original research model, taking the number of rollers, roller diameter, gasket angle and bearing clearance as the influencing factors, and taking the basic rating life of the bearing as the target function, it is conducive to the optimization design and analysis of the structural parameters of the four-point contact ball bearing based on the orthogonal experimental method and the response surface method, and the size of the load F value and the contour diagram are obtained to judge. The results show that increasing the number of rollers and increasing the diameter of the rollers are conducive to improving the service life of the bearing. Increasing the value of the gasket angle can increase the bearing life first, then decrease and then increase; Increasing the bearing clearance increases the bearing life first and then tends to be stable. This research method can make the influence of gasket angle and bearing clearance on the improvement of bearing service life be expressed linearly, and the service life of the four-point contact ball bearing after optimization is increased by 54.33%, which can improve the new design idea for the optimal design of this type of bearing.

Distributed assembly permutation flowshop scheduling problem based on IIGA

DONG Hai, WANG Zhibin

2022, (11): 169-176. doi: 10.19287/j.mtmt.1005-2402.2022.11.026

[Abstract] FullText HTML PDF(1474KB)

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In this paper, an improved iterative greedy algorithm is proposed to solve the distributed assembly Permutation Flowshop Scheduling Problem. First, establish a mathematical model with the optimization goal of minimizing the total elapsed time and an improved iterative greedy algorithm is proposed, which uses a heuristic method combining CDS (campbell dudek smith) and NEH (nawaz-enscore-ham) to generate higher-quality initial solutions and improve population diversity; Secondly, design the destruction and reconstruction process for reconfigurable products and jobs, insert the removed sequence into the specified position, and use the local search strategy to obtain new solutions; Finally, the algorithm proposed in this paper is compared with other four intelligent algorithms through simulation experiments of different scales. The experimental results show that the improved iterative greedy algorithm has high efficiency and stability in solving distributed assembly replacement flow shop scheduling.

Research on multi-objective optimization of production line based on genetic algorithm

HE Tianlong, SHAO Mingguo, BAI Xiaoqing, CAO Ze, LI Yanpeng

2022, (11): 177-182. doi: 10.19287/j.mtmt.1005-2402.2022.11.027

[Abstract] FullText HTML PDF(1415KB)

Abstract:
Automatic guided vehicle as the carrier of material transportation, make the production line material flow according to time, which is a key part of the production line design. Aiming at the problem that the AGV quantity, distribution quantity and speed parameters are not determined in the preliminary scheme of production line, which affects the optimal scheme of production line. The production cycle of production line, total capacity of temporary storage area of production line, average utilization rate of equipment and average utilization rate of AGV were taken as multi-objective. Full factor experiment method was used to study the influence of AGV quantity, distribution quantity and speed on multiple targets and its changing rules, identify key factors and optimization targets. A multi-objective mathematical model was established, and genetic algorithm was used to solve the problem, and adjust the number of parallel processes, the optimization scheme was obtained and verified by simulation. The results show that the method can solve the problem effectively, and reduce the number of working AGVs to 1, it improves resource utilization and reduces the investment cost of enterprises.

Combined rules based optimization for AGV joint scheduling in job shop

ZHONG Hongyang, PENG Chengfeng, LIAO Yong, LI Xiang

2022, (11): 183-192. doi: 10.19287/j.mtmt.1005-2402.2022.11.028

[Abstract] FullText HTML PDF(2166KB)

Abstract:
This paper takes material handling system in intelligent workshop with AGV(automated guided vehicle) as research background, and a joint scheduling optimization of machine and AGV in job shop is abstracted. This research is conducted as follows: Firstly, the mathematical model of AGV-machine joint scheduling is established at a full consideration of problem characteristics, the mathematical model is used in the exact algorithm; Then, the joint scheduling problem is decomposed into two strongly related sub-decisions, which are job sequencing and AGV selection decision, a combined rule generating framework is constructed, various combined rules are generated by embedding diverse heurstic rules into the framework; Finally, the effectiveness and scenario adaptability of combined rules are analyzed by comparing their experimental results with exact solutions of commercial solver Gurobi in differentiated test cases.

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2022 No. 11

Journal DynamicsMore

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