制造技术与机床

Research on teaching of rehabilitation robot arm based on variable admittance and compliant strategy

CHENG Yang, PAN Shangfeng, SUN Jianghong

2022, (4): 13-20. doi: 10.19287/j.mtmt.1005-2402.2022.04.001

[Abstract] FullText HTML PDF(2287KB)

Abstract:
Aiming at the problem of poor follow-up effect of the rehabilitation robot arm in the rehabilitation teaching process, an admittance controller combining the torque differential term in the joint space is designed, and an improved variable admittance control strategy is designed in combination with the hyperbolic tangent function. The teaching simulation was carried out on the Adams and MATLAB/Simulink joint simulation platform, and a physical teaching experiment platform was built for verification. The results show that the variable admittance controller can better realize the teaching function, while reducing the trajectory following error and the size of the human-computer interaction torque, improving the follow-up effect, and the teaching repeatability.

Design and simulation model construction of mobile welding robot based on ARM

XIA Jindi

2022, (4): 21-25. doi: 10.19287/j.mtmt.1005-2402.2022.04.002

[Abstract] FullText HTML PDF(1012KB)

Abstract:
In order to realize the universal design of mobile welding robot and meet various welding scenarios, the research adds two swing arm expansion control axes to realize the ten axis control of the robot based on the track type eight axis mobile robot. At the same time, the robot vision and body perception system are designed to improve the control accuracy of the robot. Compared with the artificial welding team composed of advanced welding technicians, the robot compressed the welding hours to 4.10%, the weld defect rate decreased 96.69%, the welding spot defect rate decreased 92.63%, the welding rod consumption decreased by 55.26%. At the same time, the robot welding greatly improved the welding quality while fully reducing the construction cost.

Design and analysis of fixed tapping robot based on RPP series mechanism

GAO Feng, SUN Jianghong, HE Yufan, LI Naizheng, GAO Keke

2022, (4): 26-31. doi: 10.19287/j.mtmt.1005-2402.2022.04.003

[Abstract] FullText HTML PDF(1504KB)

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Aiming at the problems of high labor intensity, high technical requirements and low operation efficiency of manual rubber tapping, a new fixed rubber tapping machine with three degrees of freedom is designed. The device is equivalent to the RPP model, the kinematics and the dynamics of the device are analyzed by the D-H coordinate method, the Monte Carlo numerical analysis method and the Lagrange dynamic method respectively. The operation status of the rubber tapping machine is verified by simulation. The results show that the position, speed, acceleration, torque and driving force of each joint of the new fixed rubber tapping machine show a smooth curve with time, and the predicted trajectory can be achieved.

Design of automated and cleaner production line for wheel hub in automobile manufacturing

XU Shuaiqiang, ZHANG Yanbin, ZHOU Zongming, LIU Bo, LI Changhe

2022, (4): 32-37. doi: 10.19287/j.mtmt.1005-2402.2022.04.004

[Abstract] FullText HTML PDF(4471KB)

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The manufacturing of automobile wheel hub plays an important role in transportation field. However, the existed production line of wheel hub was inefficient and unfriendly to the environment, which could not meet the requirements of automation and sustainable manufacturing, due to usage of manual operation and mineral cutting fluids. Therefore, an automated production line of wheel hub is designed in this paper. A feeding and blanking system, which layout is expandable, is composed of racks, transfer robotic arms and conveying rollers. Firstly, the workpiece could be grabbed precisely and efficiently to fixed point, thanks to axially arranged suction cups equipping on gripper. Secondly, a self-centering special clamp for inside/outside circle cutting is designed, in which four claws are controlled by pneumatic synchronisation circuit. The clamping force could be set up adaptively according to cutting force model, in which workpiece material and processing parameters were considered. Finally, to achieve green manufacturing, minimum quantity lubrication devices are embedded in the manufacturing unit and the traditional flood lubrication is replaced. As a result, the production efficiency of the automated production line is increased by more than 22%, based on the average production beat.

Structural design and functional analysis of propeller CNC polishing machines

LIU Shihao, HUANG Pengfei, WANG Fei, LI Binyong

2022, (4): 38-42. doi: 10.19287/j.mtmt.1005-2402.2022.04.005

[Abstract] FullText HTML PDF(1009KB)

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Marine propellers are a relatively important component of all marine engines. The processing quality of the propellers and the qualification of various indicators have a very critical impact on the power output of the marine engine. By studying the various indicators of the propeller, the overall layout of the propeller CNC polishing machine and the design plan of the transmission system are determined, and a relatively complete structure design and function analysis are carried out. Finally, a CNC polishing machine specially designed for the polishing of marine propeller blades is designed. The CNC polishing machine can greatly improve the basic performance such as the polishing accuracy and service life of the propeller blade, and reduce the manpower and material resources required for manufacturing and installation and the work intensity of manual polishing, thereby solving the problem of difficult polishing of propellers.

Research on laser polishing process of polycrystalline diamond composite sheet

WANG Jianwu, CHEN Xuebing, HUANG Jingang, ZHAO Pan, JIA Zhixin

2022, (4): 43-49. doi: 10.19287/j.mtmt.1005-2402.2022.04.006

[Abstract] FullText HTML PDF(1475KB)

Abstract:
Polycrystalline diamond composite sheet is widely used as cutting tool material because of its ultra-high hardness, wear resistance and good thermal stability. When using PCD composite sheets to make tools, laser polishing can obtain better processing characteristics than traditional processing techniques. In order to explore the characteristics of the laser polishing process of the PCD composite sheet and obtain the best surface roughness, the line roughness of the femtosecond polished area was used to systematically study the influence of the level changes of the laser power, scanning speed, and scanning distance on the roughness and polishing efficiency. The law of influence. The orthogonal test method is used to optimize the combination of the three factor levels, and the mechanism of the femtosecond laser polishing PCD is initially explored. The results show that the main factor that affects the roughness is the scanning speed. Selecting the process parameters of 7 MW laser power, 1 000 μm/s scanning speed, and 12 μm scanning distance can obtain an excellent PCD composite sheet with a roughness of 33.95 nm.

Design of wireless energy transmission device for power ultrasonic machining

TAN Yaowen, CAO Shiyu, HUANG Wenjian, LIU Chenyang, WU Chaoqun

2022, (4): 50-56. doi: 10.19287/j.mtmt.1005-2402.2022.04.007

[Abstract] FullText HTML PDF(2268KB)

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The power ultrasonic machining of CNC machine tools can effectively reduce the cutting force by superimposing high-frequency axial ultrasonic vibration on the rotating tool. It is suitable for processing all kinds of special materials. The traditional ultrasonic machining system is usually powered by a contact slip ring, which has disadvantages such as easy wear of the brush and poor interchangeability. By designing a wireless power supply device based on a non-contact transformer and a compensation circuit on the primary and secondary sides of the transformer, and using Maxwell software to carry on electromagnetic simulation to it. The influence of the air gap on the transmission efficiency is studied, and the performance of the CNC machining system is finally verified by experiments. The results show that the power transmission efficiency decreases with the increase of the air gap, and the compensation circuit design can effectively improve the vibration performance of the ultrasonic machining tool of the CNC machine tool.

Influence of nozzle parameters on flow field in jet electrodeposition region

HAN Hongjiang, LI Yongfeng, YANG Zongju, LENG Haoyuan, ZHANG Chenming, LIU Mengyu

2022, (4): 57-62. doi: 10.19287/j.mtmt.1005-2402.2022.04.008

[Abstract] FullText HTML PDF(1631KB)

Abstract:
In order to solve the problems of low machining precision, difficult control of deposition area and poor uniformity of deposition layer using jet elec-trodeposition processing, the influence of long-hole jet nozzle parameters on deposition area and deposition profile was analyzed. By establishing a system hydrodynamics model, the effects of the oblique angle of the long-hole nozzle section and the length of the nozzle cavity on the flow field in the deposition area were studied, and the contour distribution of the depo-sition layer under the coupling effect of the electric field and flow field was discussed. The simulation results show that with the continuous increase of the oblique angle of the nozzle section from 30° to 70°, the localized range of the deposition liquid at the nozzle outlet can be reduced by about 3 mm, and the localization is significantly improved. With the increase of nozzle cavity length from 40 mm to 80 mm, the fluid velocity, pressure and localization did not change much. The thickness of the deposition layer is the largest in the area directly below the nozzle, and then gradually be-comes thinner symmetrically from the center to both sides. The corresponding nozzle is processed according to the simulation parameters, and the experi-mental verfication shows that the experimental results are basically con-sistent with the simulation results.

Experimental research on the axial force in rotary ultrasonic trepanning drilling of GFRP

ZHU Zhuozhi, ZHENG Lei, XU Subai, DONG Xianglong, WEI Wendong, LIU Ziwen, SONG Chunyang

2022, (4): 63-68. doi: 10.19287/j.mtmt.1005-2402.2022.04.009

[Abstract] FullText HTML PDF(1550KB)

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As one of the most important parameters reflecting drilling process and state, axial force has a direct impact on the quality of fiber reinforced plastic drilling. In order to analyze the variation regulations of axial force with process parameters in rotary ultrasonic trepanning drilling, the mathematical model of drilling force was established based on the kinematic characteristics of single abrasive, and the drilling experiment on glass fiber reinforced plastic was made. The results show that the axial force increases with the increase of spindle speed or decreases with the decrease of feed rate, and the variation trend is consistent with mathematical prediction model. Compared with conventional drilling, in rotary ultrasonic drilling process, the axial force and exit delamination factor decrease by 6%~25% and 8%~15% ,and the hole quality has effectively improve.

Configuration design and branch chain stiffness analysis of 4-URU fully compliant parallel mechanism

ZHANG Wangwang, BO Ruifeng, HUANG Daoyang, CHEN Zhenya

2022, (4): 69-74. doi: 10.19287/j.mtmt.1005-2402.2022.04.010

[Abstract] FullText HTML PDF(1231KB)

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A new method for solving the branch chain stiffness of 4-URU type flexible parallel mechanism was proposed, and the effectiveness of the method was verified by software simulation results. Firstly, the degree of freedom of the 4-URU rigid parallel mechanism was analyzed by using the screw theory, and the corresponding flexible parallel mechanism was designed by using the flexible hinge replacement method. Based on the flexible hinge stiffness matrix, the hinge stiffness matrix of the branch chain was obtained by the transformation matrix method, the stiffness of each flexible rod of the branch chain was obtained by the finite element theory, and the total stiffness matrix of the branch chain was obtained by linear superposition. Finally, the deformation of the branch chain in the X, Y and Z directions was obtained by theoretical calculation with MATLAB. The model is simulated and analyzed by ANSYS software, and the results show that the theoretical calculation is basically consistent with the simulation results. Effectiveness of the method to solve the stiffness of branch chain is verified, which provides a theoretical basis for solving the stiffness of the whole flexible parallel mechanism by using the method, and helps to study the precision of the flexible parallel positioning platform.

Design and research of 6-DOF automatic fiber laying machine

CAO Zhongliang, LIN Guojun, GUO Dengke, CAO Qinglin

2022, (4): 75-81. doi: 10.19287/j.mtmt.1005-2402.2022.04.011

[Abstract] FullText HTML PDF(1574KB)

Abstract:
Based on the operating principle of the automatic laying molding equipment, the three-dimensional model of each component of the fiber laying molding machine was established by SolidWorks software. Taking the key parts of 6-DOF fiber laying virtual prototype as the research object, the software ABAQUS was used for statics analysis and modal analysis, and the simulation results of the key parts were obtained. By analyzing the simulation data of the key parts, it was verified that the structure of the laying machine can meet the requirements of the strength, stiffness and stability of the laying equipment. The simulation model of the laying virtual prototype was established, and the variation rules of the speed and acceleration at the connection of the core die and the laying head and the manipulator arm were obtained. The rationality of the design of the 6-DOF fiber laying virtual prototype was verified by analyzing the variation range of the laying speed and acceleration.

Data acquisition and storage of Siemens 828D CNC system

SI Xingyao, LIAO Yinghua, XU Yun, HUANG Yu, YANG Ming

2022, (4): 82-87. doi: 10.19287/j.mtmt.1005-2402.2022.04.012

[Abstract] FullText HTML PDF(1185KB)

Abstract:
Siemens 828D CNC system is a full digital high-end CNC system . This paper mainly studies the OPC UA of Siemens machine tool itself, and develops a client that conforms to the OPC UA specification. Using the client to obtain the information of variables, the data in OPC UA server is collected through the program developed by python, and the collected data is stored in MySQL database after processing. The results show that on the basis of the data table, the single table storage is reduced by using the data table differentiation function, and the read-write separation architecture of the database is adopted to avoid data blocking, so as to improve the performance of the database.

Automatic tightening machine system for multi-specification nuts

HAO Xinni, GAO Yan, Mohammed Ahmed Ebrahim Alaghbari, ZOU Hao

2022, (4): 88-93. doi: 10.19287/j.mtmt.1005-2402.2022.04.013

[Abstract] FullText HTML PDF(1322KB)

Abstract:
There are many specifications and types of nuts that need to be tightened during assembly, due to the great differences in the structure of different types of automobile fuse boxes. Manual assembly requires multiple replacement of electric batches, not only the efficiency is low, but also the tightening torque cannot be accurately controlled. An automatic tightening machine for multi-specification nuts based on torque monitoring is designed, which can automatically achieve the functions of loading, positioning, tightening, tightening torque real-time detection of multi-specification nuts and automatic wrench replacement. The prototype test shows that the system is reliable and the tightening effect is good, the production efficiency is increased by more than 20% compared with manual assembly, and the flexibility of automobile fuse box assembly is improved.

Design of lifter core-pulling mechanism for side hole in narrow space

XIONG Yi, CHEN Jianxue, LI Shuaijie

2022, (4): 94-97. doi: 10.19287/j.mtmt.1005-2402.2022.04.014

[Abstract] FullText HTML PDF(1272KB)

Abstract:
In view of the core-pulling problem of the inner hole in the narrow space inside the plastic part, the method of combining the insert with the slanting top was put forward. Taking the plastic shell as an example, the narrow cylinder is first divided into inserts from the core to reduce the processing difficulty of the core, and the lifter is used to shape the side holes in the cylinder, aiming at the interference between the lifter and the plastic part when pulling the core outwards, the core-pulling direction is adjusted to be in the radial direction of the cylinder, and then the interference problem of the slanting top mechanism in the narrow space is solved by embedding the slanting top mechanism on the insert.

Turn-milling composite and five-axis machining technology based on ASX400 milling cutter head

SHI Yaotang

2022, (4): 98-102. doi: 10.19287/j.mtmt.1005-2402.2022.04.015

[Abstract] FullText HTML PDF(1532KB)

Abstract:
Turn-milling composite and five-axis machining belong to the multi-axis machining technology, the article research on the multi-axis machining process of the milling cutter head, expounds the principle of cylindrical and end-face milling of turn-milling composite, the programming method of the spiral groove, the operation and practice of human-machine interact programming; Explain the principle of five axis directional machining and the CAM process based on UG, analysis of the causes and principles of RPCP programming, and gives the method of measuring the RPCP parameters and five-axis system coordinate , and provides experience and guidance for the relevant practitioners.

<p>Hyperbolic ion trap rod fabricated using precision turning method</p>

LI Jiawei, JI Fang, ZHAO Shun

2022, (4): 103-109. doi: 10.19287/j.mtmt.1005-2402.2022.04.016

[Abstract] FullText HTML PDF(2717KB)

Abstract:
<p>The performance of hyperbolic ion trap requires that each pole rod has a smooth surface and contour precision, while it’s not easy to achieve such results by conventional machining. In order to meet the requirements of smooth surface quality and sub-micron contour precision of hyperbolic ion trap rod, a non-circular section turning method based on slow tool servo technology is proposed. Firstly, the turning process of non-circular section was analyzed, and tool working angle was analyzed to avoid tool interference caused by large additive angle in non-circular section turning. The results showed that eccentric clamping could reduce tool additive angle. Secondly, factors concerned with contour accuracy were discussed, and the simulation results showed that tool centering error had a great influence on contour accuracy, this error needed to be controlled below 1 μm to realize sub-micron contour accuracy. Finally, experiment was carried out to testify and also measurement error was discussed due to measuring misalignment. Through trial fabrication, the contour error of hyperbolic surface can reach 0.3 μm.</p>

Forming process and die structure optimization of super large size GH4169 superalloy bolt

LIU Le, YIN Yinyin, JIN Hong, GUAN Yue, LIU Xiuyan

2022, (4): 110-115. doi: 10.19287/j.mtmt.1005-2402.2022.04.017

[Abstract] FullText HTML PDF(1671KB)

Abstract:
The paper aims to study the forming process and die structure of large size GH4169 superalloy bolt in order to solve the problems of difficult forming, easy cracking and low service life of the die. Combined with the theory of metal plastic forming, the forming process scheme is put forward. The proposed process scheme is numerically simulated by Deform-3D finite element analysis software. The load stroke curve and metal flow law in the forming process are analyzed. According to the forming process, the corresponding die structure is designed and optimized. Finally, the process test is carried out. Through numerical simulation, the process parameters in the forming process are obtained, and the deformation mechanism of GH4169 superalloy bolt forming process is revealed. When the double-layer prestressed composite die is used, the die cracks. After the die structure is optimized, the three-layer prestressed composite die is used to meet the forming requirements, the die life is high, and the GH4169 superalloy bolt forgings trial produced in small batch are fully filled. The data obtained are basically consistent with the simulation results. The forming process and die structure of GH4169 superalloy bolt proposed in this paper are feasible. The formed superalloy bolt meets the practical application requirements in the aerospace field, provides a certain theoretical basis for the production of large-size GH4169 superalloy bolt, and has guiding significance for the actual production and other similar parts.

Optimization of manufacturing process of AFA 3G spider finger

XU Chao, GAN Lu, HUANG Fan

2022, (4): 116-120. doi: 10.19287/j.mtmt.1005-2402.2022.04.018

[Abstract] FullText HTML PDF(1121KB)

Abstract:
This paper studies the manufacturing processing of the traditional AFA 3G spider finger, According to the problem that the AFA 3G spider finger cannot be automatically and continuously machined in the traditional manufacturing process. By improving U-shaped slot milling cutter and the ϕ 5.5 drill and the inner hole reamer the number of maching has increased signifisant; Milling product quantity from 50 improving to 300, drilling product quantity from 200 improving to 2000, the reaming product quantity from 100 improving to 500. The optimization of the manufacturing process of the AFA 3G spider finger not only can solve the problem of the abnormal breakage of the cutting tool and achieved the continuous maching of the product. In addition,the process not only reduces the labor intensity and improves the productivity, but also effectively improves the quality of product and reduce the cost of raw materials and tools.

Deformation control and process optimization of thin-walled and hollowed-out workpiece

CUI Yachao

2022, (4): 121-125. doi: 10.19287/j.mtmt.1005-2402.2022.04.019

[Abstract] FullText HTML PDF(1139KB)

Abstract:
The thin-walled and hollowed-out workpiece with complex free-form surface as its component is prone to deformation and vibration in traditional processing due to its poor rigidity, complex structure and large amount of material removal, which leads to defects such as poor surface roughness of the workpiece and heavy trace of tool connection. This paper optimized design processing scheme of thin-walled hollow artifacts, by multi axis positioning combined with multi-axis linkage machining of high speed milling process. The influence of the workpiece surface quality and machining partition scheme was studied on the mechanical deformation, thermal deformation process system, and reducing the vibration of the cutting tool system, adopting the appropriate cutting parameters such as the processing conditions on the thin wall type hollow out. The results show that the workpiece can be machined in one loading by using the optimization scheme, and the machining error and tool connection marks can be avoided by repeated positioning.

Research on NC turning technology of tiny narrow groove

SONG Jiajie, ZHU Gang, CHEN Lu

2022, (4): 126-131. doi: 10.19287/j.mtmt.1005-2402.2022.04.020

[Abstract] FullText HTML PDF(1421KB)

Abstract:
Taking tiny narrow groove as the research object, the structure characteristics of Inner Core workpiece are introduced. The machining difficulties of the workpiece were analyzed from the aspects of turning vibration and taper, tiny narrow groove turning, turning surface quality and programming efficiency. A reasonable numerical control turning process has been worked out. A special turning tool for tiny narrow groove was designed based on the structure of separated replaceable tool head. On the premise of ensuring the rigidity of the tool, the geometric Angle of the tool was determined through three factors orthogonal test, and the special turning tool was prepared. Reasonable cutting fluid was chosen to improve the surface quality of the machined surface. Method of macroprogram was applied to finish NC program efficiently, which has simplified the machining program and improved the production efficiency.

Point cloud error compensation method for stereo structured light 3D reconstruction system

LIU Zhongqiang, MA Songhua, HU Tianliang, ZHANG Tongjia, DUAN Yuefei

2022, (4): 132-139. doi: 10.19287/j.mtmt.1005-2402.2022.04.021

[Abstract] FullText HTML PDF(2339KB)

Abstract:
In order to improve the accuracy of stereo structured light 3D reconstruction system, a point cloud error compensation method is proposed. The method is divided into three parts: error calibration, error modeling and error compensation. Firstly, a new error calibration method is proposed, which divides the measurement space of stereo vision structured light system into discrete feature points, and calibrates the error of feature points in the whole space. Secondly, the error modeling method based on neural network is proposed, and the error model of this space is established. Finally, a point cloud error compensation method suitable for stereo vision structured light system is proposed. After experiments, it is proved that the proposed error compensation method reduces the diameter error by 51.96% and the sphere center distance error by 14.16%, respectively. The effectiveness and feasibility of this algorithm are also verified.

Design of light-pen vision measurement system for large-scale spherical parts

JIANG Lingbo, LI Yunlei

2022, (4): 140-144. doi: 10.19287/j.mtmt.1005-2402.2022.04.022

[Abstract] FullText HTML PDF(1277KB)

Abstract:
In order to measure the three-dimensional shape, spherical diameter and sphericity error of the large-size spherical parts, a light-pen vision measurement system is designed. The system is mainly composed of high-resolution camera, light pen and supporting image processing software. Firstly, this paper introduces the measurement principle of the system, and then gives the key technologies in turn: the structural design of the light pen and the light pen calibration method based on close-range photogrammetry, and the method of establishing the conversion relationship between the light-pen coordinate system and the camera coordinate system by using the homography matrix. The accuracy evaluation experiment based on grating ruler shows that the relative measurement accuracy is better than 0.05 mm/m in 2000 mm×1500 mm field of view. Taking the large-size metal ball as the measured object, the three-dimensional coordinates of multiple points on the balll surface are extracted to generate the fitting ball, and then the sphericity error is calculated to be 2.068 mm.

A fuzzy adaptive control method for brushless DC motor

SONG Lijun, WANG Yan

2022, (4): 145-148. doi: 10.19287/j.mtmt.1005-2402.2022.04.023

[Abstract] FullText HTML PDF(1083KB)

Abstract:
Aiming at the difficulty of changing the control parameters of traditional PID controllers, a fuzzy logic controller automatically constructed by the genetic algorithm is proposed, which is applied to the fuzzy adaptive control for brushless DC motors to improve the control performance. A comparative study is carried out between the adaptive fuzzy PID control and traditional PID control, which were used to separately drive the brushless DC motor. Simulation results show that the fuzzy PID control system has better dynamic performance and robustness than the traditional PID control system.

Research of machining precision of crankshaft bore based on a certain type of diesel engine

LI Shiyong, DING Ze, ZHANG Chunming, GUO Pengfei

2022, (4): 149-153. doi: 10.19287/j.mtmt.1005-2402.2022.04.024

[Abstract] FullText HTML PDF(1086KB)

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In order to resolve the cylindricity quality problem of crankshaft bore based on a certain type of diesel engine, processing 5M1E was researched, as a result, "machine" and "material" are the main factors, and deformation of workpiece is the root cause by further analysis. Based on the current situation of fixture, and to modify as little as possible, the number and position of fixture pressing bar were researched and optimized, and through the offline measurement and test cutting verification method, it is concluded that when the pressure of fixture pressing bar is 3 MPa, it can reliably press the workpiece and avoid the deformation of workpiece by pressing, thus solving the out-of-tolerance problem of crankshaft bore’s cylindricity machining. What’s more, the research method provides a reference for improving the machining quality of various crankshaft bores.

Lean improvement’s application of value stream analysis in connector assembly

WANG Xi, MEI Qingchen, JIA Lubing

2022, (4): 154-158. doi: 10.19287/j.mtmt.1005-2402.2022.04.025

[Abstract] FullText HTML PDF(939KB)

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Combined with value stream analysis and lean tools, the lean improvement of connector assembly process was studied in A workshop’s connector assembly process. In order to identify the non-value-added links in production, the current value stream mapping was drawn through field investigation firstly. Meanwhile, the causes of non value-added factors, including unreasonable logistics layout, backward production mode, low line balance rate, much WIP and low standardization level, were figured out by virtue of the lean thinking. Finally, with the help of various lean production tools and methods, it optimized workshop layout and logistics, designed pull production, implemented just-in-time distribution, improved line balance and implemented standard operation. It successfully reached that the per capita efficiency of the workshop was increased by 35.02%, the production cycle was shortened by 26.93%, and the WIP was reduced by 26.78%.

Design and application of scheduling algorithm based on multi-objective and multi- constraint

LUO Xiaofeng, HU Ying, YU Xiang

2022, (4): 159-164. doi: 10.19287/j.mtmt.1005-2402.2022.04.026

[Abstract] FullText HTML PDF(891KB)

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Aiming at the multi-objective production scheduling problem faced by machining enterprises under multi-constraint conditions such as dual-station, adjacent equipment and out-of-command process, the production factors required for scheduling are analyzed, and the mathematical model of optimal production scheduling is established. An improved genetic algorithm based on dynamic crossover and mutation operator is proposed. Molecular and fission molecules are introduced into the traditional scheduling algorithm based on three-stage coding. Chromosome offset is used to improve the compactness of scheduling and accelerate the convergence speed of algorithm. The scheduling results optimized by weighting coefficient are obtained. Finally, an example is solved and applied to actual production, which greatly improves the efficiency of production scheduling.

Upgrade solutions and realization of digital workshop based on digital twin

PANG Jianjun

2022, (4): 165-171. doi: 10.19287/j.mtmt.1005-2402.2022.04.027

[Abstract] FullText HTML PDF(3958KB)

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With the development of new generation information technology and national strategic policy, CTB Co., Ltd. upgraded the digital workshop with the theory of digital twin workshop operation mode and digital workshop construction as the guide. It applied various technologies such as big data, industrial interconnection, digital simulation, to establish big data information platform and digital twin management system, integrate and interconnect various equipment, and simulate the product design and key processes. This greatly improve the level of intelligent manufacturing.

Accuracy test analysis of TD500A drilling and tapping center based on i5 system

CHEN Shuai

2022, (4): 172-175. doi: 10.19287/j.mtmt.1005-2402.2022.04.028

[Abstract] FullText HTML PDF(1350KB)

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The TD500A vertical drilling and tapping center independently produced by Dalian Machine Tool Co., Ltd. of general technology group is selected as the experimental prototype, which is matched with i5 intelligent system. The positioning accuracy and repeated positioning accuracy of TD500A drilling and tapping center with i5 system are tested by Renishaw laser interferometer to further verify the reliability of the accuracy. The results show that: the research conclusions have important reference value for the application of the system in machine tools.

Research on fault diagnosis model of rolling bearing based on ARIMA and XGBoost

ZHANG Tianrui, ZHOU Fuqiang, WU Baoku, ZHU Zhiyi, SONG Yuru

2022, (4): 176-182. doi: 10.19287/j.mtmt.1005-2402.2022.04.029

[Abstract] FullText HTML PDF(1253KB)

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In view of the low accuracy and accuracy of the existing fault prediction models of rolling bearing, a rolling bearing fault prediction model based on ARIMA time series prediction and XGBoost classification algorithm is proposed in this paper. Firstly, LMD combined with FPA is used to solve the problem of blind source underdetermination. Secondly, KPCA is used to select sensitive features as the input of the prediction model to improve the classification accuracy of bearing faults. Thirdly, Arima autoregressive model is used to predict the short-term change of bearing vibration signal in the future, and the prediction results are input into XGBoost model for fault classification and prediction, so as to realize rolling bearing fault identification and improve the prediction accuracy. Finally, an example is verified by the bearing data set used by Case Western Reserve University in the United States. The experimental results show that this method can more accurately predict the short-term vibration signal change of the bearing and diagnose the possible faults. It is proved that this method can effectively extract the features under the condition of rolling bearing signal noise. It is feasible and reliable in fault identification and fault early warning.

Research on the effect of inner raceway defects on the stiffness characteristics of rolling bearings

LI Leijun, ZHANG Bichuan, GAO Yuxiang, HAN Qin, CHEN Runlin

2022, (4): 183-188. doi: 10.19287/j.mtmt.1005-2402.2022.04.030

[Abstract] FullText HTML PDF(1743KB)

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Rolling bearings are widely used in mining motors and other large equipment. Under complex and changeable working conditions and harsh operating conditions, long-term and high load operation will lead to fatigue pitting corrosion of rolling bearings and defects on raceway surface, and the deterioration of defects will affect the normal operation of equipment. In this paper, for rolling bearings with defects in the inner raceway, the additional displacement caused by the defect is added to the elastic deformation of the bearing. According to the mechanical balance equation, the load distribution of each rolling element is analyzed, and the stiffness model of the rolling bearing with defects in the inner raceway is established. The influence of defect length and depth on rolling bearing stiffness characteristics is analyzed. The results show that when the defect is located in the non-loaded area, the average stiffness of the defective bearing is equal to the average stiffness of the non-defective bearing. When the defect moves from the loaded area to the non-loaded area with the rotation of the inner ring, the average stiffness of the bearing first decreases and then increase, and the average stiffness is negatively related to the length and depth of the defect.

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2022 No. 4

Journal DynamicsMore

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