制造技术与机床

Mathematical modeling and simulation optimization of three-axis linkage steering mechanism based on Newton-Euler method

YANG Feixue, KANG Shaopeng, LIU Kailei, QIANG Hongbin, WU Hao

2022, (3): 9-16. doi: 10.19287/j.cnki.1005-2402.2022.03.001

[Abstract] FullText HTML PDF(20158KB)

Abstract:
Aiming at the problem of low steering accuracy in the steering process of three-axis vehicle, with the help of the advantages of Newton-Euler method in multi-body modeling, the mathematical model of three-axis linkage steering mechanism is established, the position, angular velocity and force equations of the mechanism are derived, and the kinematic model and dynamic model are established by using MATLAB software and ADAMS software, The key points of the three-axis linkage steering mechanism are simulated and optimized through the joint simulation of Simulink and Adams. The simulation results show that after optimization, the steering accuracy of the three-axis linkage steering mechanism is improved, the angle error is reduced to less than 2.2 °, and the force on each articulated point is more stable, which improves the steering stability.

Lightweight of welded box for marine gearbox based on static-dynamics

SHI Yuelin, TONG Yanhua, LIU Cong

2022, (3): 17-23. doi: 10.19287/j.cnki.1005-2402.2022.03.002

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Using the gearbox system analysis software MASTA and the large-scale general CAE software MSC Patran & Nastran, the meshing analysis model and the box finite element model of the marine gearbox are established.The load of the gearbox under multiple loading cases is analyzed and compared, and the structural efficiency are analyzed and evaluated.Based on the principle of stress field balance and the constraint of strength and stiffness, the lightweight structure of the box is designed to reduce redundant materials.Through the modal analysis of the lightweight box, the resonance of the gearbox system is avoided.At present, the high power marine gearbox with this method has been mass-produced, and the weight of the gearbox box has been reduced by 19% after lightweight, so as to achieve the purpose of lightweight.

Machining simulation of point-contact curvilinear cylindrical gears based on six-axis CNC milling machine tools

ZHANG Xuegang, XIE Yongchun

2022, (3): 24-29. doi: 10.19287/j.cnki.1005-2402.2022.03.003

[Abstract] FullText HTML PDF(16263KB)

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The point-contact curvilinear cylindrical gear is a novel gear in the parallel shaft transmission systems. Traditional machine tools are difficult to handle the efficient manufacturing of such gears. In this paper, a six-axis CNC milling machine tool with the face-milling cutter are used to carry out the simulation of machining processes of the gear. Firstly, the mathematical model of the tooth surface is derived based on the theory of gearing, and the point cloud data of the tooth surface is solved by the mathematical model. Furthermore, the solid model of the gear is built in 3D software based on the point cloud data. Secondly, building the CNC gear milling machine tool and the face-milling tool in VERICUT software, and then, writing the CNC program for the machining simulation of the gear. Finally, the precision of the be-generated gear is analyzed by the original gear model. The results show that the point-contact curvilinear cylindrical gear can be manufactured by the six-axis CNC milling machine tool and the face-milling cutter. This study can establish the foundation for the efficient manufacturing and industrialized application of the point-contact curvilinear cylindrical gears.

Simulation of machining equidistant profile by orthogonal turning milling

KONG Fanya, JIANG Zenghui, SHAO Zhongwei, JIANG Zhiyong

2022, (3): 30-33. doi: 10.19287/j.cnki.1005-2402.2022.03.004

[Abstract] FullText HTML PDF(9295KB)

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The equidistant profiles are more and more widely used in connection structures. Because the section profile curve of the equidistant profile is special, it is generally processed by copying turning and CNC turning. The equidistant profile machining by orthogonal turning milling is proposed. The UG processing module and the post processor are applied for generating program of machining the equidistant profile by orthogonal turning milling. The virtual horizontal turning milling machining center is established, and it is emulated to machining the equidistant profile by orthogonal turning milling by VERICUT, and the processing results were compared and analyzed.The results show that the equidistant profile can be machined by orthogonal turning milling better.

Research on wear state monitoring of ultrasonic vibration drilling bits based on dual signal fusion

TANG Wusheng, WEI Zhiyuan, YIN Chunmei, SHI Yaochen

2022, (3): 34-39. doi: 10.19287/j.cnki.1005-2402.2022.03.005

[Abstract] FullText HTML PDF(15615KB)

Abstract:
In order to monitor the wear status of the drill bit in the process of ultrasonic vibration drilling, an acquisition system for the vibration signal and AE signal of the ultrasonic vibration drilling bit is constructed. By collecting the vibration signal and AE signal of the drill bit under different wear conditions, it is subjected to wavelet decomposition. Obtain the eigenvalues related to the wear of the drill bit, merge the two as the input of the neural network, and input it into the constructed 12-10-3 BP neural network to identify the wear status of the drill bit. The test results show that the built BP neural network has an effective recognition rate of 91.7% for the drill bit through the fusion signal of vibration and AE, which can effectively identify the wear state of the drill bit.

Simulation analysis of cutting effect of double chamfered structure of turning tool

WEI Ziyang, SHI Guangfeng, SHI Guoquan, LI Junye, ZHANG Jingran, LI He

2022, (3): 40-43. doi: 10.19287/j.cnki.1005-2402.2022.03.006

[Abstract] FullText HTML PDF(3905KB)

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Taking Al-6061 aluminum alloy as the research object, three-dimensional cutting simulation analysis was carried out based on Deform finite element analysis software. The orthogonal experimental design method was used to study the influence of the structural parameters of double chamfers on cutting force and cutting temperature. The simulation results show that the cutting force and cutting temperature are significantly reduced compared with those of chamfering with a single fixed value under the appropriate double chamfering width and angle. The research results can provide theoretical guidance for the optimization of the nose structure of chamfering tools and the actual cutting process.

Monitoring cutting tool wear based on spindle current signal multi-feature fusion

WU Ying

2022, (3): 44-48. doi: 10.19287/j.cnki.1005-2402.2022.03.007

[Abstract] FullText HTML PDF(13136KB)

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In order to gain long-term online monitoring cutting tool wear data under normal cutting conditions, a new method for monitoring cutting tool wear was proposed based on the spindle current signal and particle swarm optimization support vector machine (PSO-SVM) model. Firstly, the spindle motor current signals of CNC machine tool were analyzed. Multiple feature parameters related to tool wear and the EMD energy entropy were fused as an input feature vector. Secondly, the SVM model parameters were optimized by the PSO algorithm. The tool wear condition recognition model was established based on the spindle current signal and PSO-SVM theory. Finally, the spindle current signals of the vertical machining center under different tool wear conditions were collected by the experiment. The proposed method was compared with traditional SVM model and BP neural network model. The results show that the proposed method has higher recognition accuracy and better generalization ability. The proposed method can realize the long-term online monitoring of the tool wear condition.

Motion planning for improved operational reliability of composite industrial robots

PEI Yanhu, LIU Zhifeng, XU Jingjing, YANG Congbin, ZHENG Jigui

2022, (3): 49-54. doi: 10.19287/j.cnki.1005-2402.2022.03.008

[Abstract] FullText HTML PDF(18117KB)

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The application of the composite industrial robot can effectively improve the production efficiency of the intelligent manufacturing shop. In the problem of its motion planning, the initial posture of the manipulator adjusted by the mobile device directly determines whether the target task can be executed reliably. To solve the above problem, a motion planning optimization method considering the initial posture of the manipulator was proposed. Based on the previous foundation, the proposed method solved the kinematics modeling and the minimum obstacle avoidance distance modeling of the composite industrial robot respectively by using screw description and slices characterization methods, which provided the model basis for trajectory optimization. The motion planning optimization model is established to minimize the equivalent energy consumption and the motion time. The hybrid variable set is designed by considering the initial station, including parameters of the mobile device and the manipulator, redundant joint angle. Constraints of kinematic constraints and obstacle avoidance are both considered to guarantee the movement stability and safety of the manipulator. Results indicate that the composite industrial robot based on planning optimization has high operational reliability

Research on the robot’s compliant force control device

SUN Mingjian, GUO Kai, SUN Jie

2022, (3): 55-61. doi: 10.19287/j.cnki.1005-2402.2022.03.009

[Abstract] FullText HTML PDF(18284KB)

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The control of the contact force between the tool and the workpiece is particularly important in the robot's automated polishing and grinding process. Based on the principle of active compliance control, this paper proposes a compliance force control device and control method for industrial robots. The structural design and dynamic modeling of the system are carried out. Based on the BP neural network PID algorithm, the adaptive control strategy of the compliant force control device is designed. Finally, the force control tracking experiment is carried out. The experimental results show that the compliance force control device can ensure the constant contact force between the workpiece and the tool during the grinding process, thereby improving the surface processing quality.

Energy-efficient path planning for a single-load AGV executing multiple transport tasks

LI Junlan, ZHANG Zhongwei, WU Lihui, WU Zhaoyun

2022, (3): 62-67. doi: 10.19287/j.cnki.1005-2402.2022.03.010

[Abstract] FullText HTML PDF(17502KB)

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Energy-efficient path planning has been proved to be a feasible approach to improve the energy efficiency of an automated guided vehicle (AGV) and promote the energy saving of a manufacturing workshop. Current research on AGV energy consumption (EC) optimization from the perspective of path planning mainly focuses on a single transport task, and rarely involves multiple transport tasks. To fill the gap, with a single load AGV as the research object, an energy-efficient AGV path planning model is established, which is oriented to multiple transport tasks and takes transport distance and EC as the optimization objectives. Then, a two-stage solution method is proposed. In the first stage, the energy-efficient AGV path planning is executed for the load transport stage associated with each transport task, and the possible no-load transport stages, to obtain the corresponding optimal paths. In the second stage, the non-dominated sorting genetic algorithm-Ⅱ is adopted to determine the optimal transport task execution order and select the best transport path for each transport stage. Finally, the case study verifies the energy-saving effect of the presented model.

Hilbert curve path optimization algorithm based on FDM technique

GE Xiao, SHI Tingchun, HUANG Zhipeng, YUE Xiuyan

2022, (3): 68-73. doi: 10.19287/j.cnki.1005-2402.2022.03.011

[Abstract] FullText HTML PDF(17546KB)

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The fill path of FDM is discontinuous, and frequent stopping of the motor can easily lead to warping and deformation. A path optimization algorithm based on contour offset and Hilbert curve fitting is proposed by combining contour offset method and Hilbert curve filling in space filling curve. In this algorithm, Hilbert curve was fitted with three B-spline curves, which reduced the motor change rate and the stopping times of the motor in the printing process, thus reducing the warpage deformation of the printed parts and improving the precision of the printed parts. The experimental results show that the average maximum warpage of the model is reduced by 60.70% and the total average warpage is reduced by 62.26%.

Time-optimal trajectory planning based on improved genetic algorithm

YANG Xingtao, KU Xiangchen, ZHAO Huanle, MI Xian, MA Dongyang

2022, (3): 74-79. doi: 10.19287/j.cnki.1005-2402.2022.03.012

[Abstract] FullText HTML PDF(14556KB)

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A time-optimal trajectory planning method for industrial robots is proposed. The trajectory of robot joint space is regarded as the cubic spline curve fitting the key points. The mathematical model of optimal time trajectory planning was established with the objective of optimal time. At the same time, the constraints of joint trajectory velocity, acceleration and acceleration were considered. Combining the objective function value and constraint conditions, a sorting method for evolutionary algorithm was proposed, and the cubic spline trajectory of joint space was optimized with the improved genetic algorithm as an example. The Sheffield genetic algorithm toolbox was used to calculate the optimization results of genetic algorithm, and the D-H method was used to establish the robot kinematics model. Combined with the Robotics Toolbox, the 3D simulation model of the robot was built, and the simulation environment for cubic spline trajectory optimization of the robot was established. The simulation results of Stanford robot show that compared with the traditional pattern search method, the total trajectory time of the improved genetic algorithm is significantly reduced.

A circular strategies signal extraction method based on CEEMD and permutation entropy

YIN Yudong, MING Yong, BIAN Yu

2022, (3): 80-85. doi: 10.19287/j.cnki.1005-2402.2022.03.013

[Abstract] FullText HTML PDF(18636KB)

Abstract:
In order to solve the problem of the poor timeliness and the difficulty of accurate noise estimation of EEMD threshold de-noising method, a circular strategies signal extraction method based on CEEMD permutation entropy was proposed. The original signal was processed by CEEMD, and the reconstruction error caused by white noise was suppressed by superimposing the opposite white noise on the signal. The noise component and signal component were determined by calculating permutation entropy of the intrinsic mode functions. Considering the unknown prior knowledge of noise of the signal, the signal extraction method of circular strategies was established on the basis of singular value decomposition without prior knowledge of signal and noise, the useful signal could be well preserved while noise was suppressed. Through the noise reduction of simulation signal and chaotic signal, the results showed that the proposed method not only effectively eliminated the noise interference, but also reduced the loss of useful details.

Design of numerical control system for small magnetic abrasive finishing machine

LU Xinsheng, WANG Jiong

2022, (3): 86-91. doi: 10.19287/j.cnki.1005-2402.2022.03.014

[Abstract] FullText HTML PDF(16167KB)

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Magnetic abrasive finishing, as a new surface finishing technology, has unique advantages in lapping the inner wall of slender tubes, but there are few CNC machine tools for magnetic lapping in the market. Aiming at the defects of traditional numerical control system applied to small machine tools, this paper designs the embedded software and hardware of numerical control machine tools based on STM32+FreeRTOS real-time operating system, and establishes a three-layer topological software system. The spindle speed servo control was studied, the spindle mathematical model was established through system identification, and PID parameters were set based on Ziegler-Nichols method. Taking biopsy needle as an example, a practical grinding experiment was carried out. The experimental results show that the grinding process of the machine is stable and the machining accuracy is high.

The position and workspace analysis of (2PSR+PUU)&RP hybrid machine tool

HUANG Daoyang, BO Ruifeng, ZHANG Wangwang, CHEN Zhenya

2022, (3): 92-97. doi: 10.19287/j.cnki.1005-2402.2022.03.015

[Abstract] FullText HTML PDF(13771KB)

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A novel (2PSR+PUU) &RP hybrid machine tool was proposed to solve the disadvantages of small swing angle and difficulty in machining complex curved parts.Firstly, the screw theory and modified K-G formula were used to analyze, calculate and verify the degree of freedom of the mechanism.The closed-loop vector method was used to analyze the kinematics of the mechanism, and the inverse solution and the positive solution based on the particle swarm optimization algorithm were given to determine the position and pose relationship between the driving block and the moving platform.In SolidWorks, the working space is drawn by static and static method, and the pendulum angle is calculated by ADAMS, which verifies the correctness of the mechanism model and the realizability of the mechanism motion.The results show that the hybrid machine tool has 3T2R five degrees of freedom, has a large working space, and the tool swing angle can reach (0°~90°), through the large swing angle of the tool rotation and five-axis linkage can be applied to the turbine, hydraulic turbine and aero-engine blade and complex surface parts processing.

Control system design for the new forming machine of high-speed traveller

MA Zhen, WANG Junbo, LIU Jiangnan, JIANG Fengyang, SUN Guoliang, WEI Jinbo

2022, (3): 98-102. doi: 10.19287/j.cnki.1005-2402.2022.03.016

[Abstract] FullText HTML PDF(13977KB)

Abstract:
A control system of the new forming machine of high-speed traveller is designed in the research. The system is made up of feeding, wire feeding, forming, human-computer interaction, and feedback alarm. Programmable controller (PLC)is used as the control core, servo motors and asynchronous motors are used as power sources, and the traditional cam drive is replaced by a synchronous belt drive. The fuzzy position positioning algorithm is applied to ensure the consistency of blanking length. Meanwhile, stepless speed change and high-speed operation of the forming spindle are realized by controlling the output frequency. The touch screen is the monitoring equipment of the upper computer, which realizes the mechatronics through the feedback of the sensors in each station. By calculation, the production efficiency of the machine is 1.5 times that of the old at rated power operation and the quality error is reduced to within ± 1.37%.

Innovative design of a device of filling powder into cavity based on TRIZ

ZHANG Hui, WU Jie, HUANG Yuming, DENG Bingbing, TANG Shaoyu

2022, (3): 103-106. doi: 10.19287/j.cnki.1005-2402.2022.03.017

[Abstract] FullText HTML PDF(9915KB)

Abstract:

In order to solve the problems that the devices of filling powder into cavity have a low efficiency and a slow filling speed, and the outlet is easily blocked, the patents of devices of filling powder into cavity in our patent database have been searched and analyzed. Firstly, the existing devices have been analyzed using causality analysis method. Then, the algorithm of the method of the small people is used to obtain the theoretical model to solve the problem. After that, the technical contradictions of the original model have been analyzed by 40 invention principles and 39 general engineering parameters of TRIZ theory. Finally, an innovative device of filling powder into cavity has been designed. The design can improve the filling speed and reliability of powder filler.

Research on structure optimization and geometric accuracy analysis of laser cutting machine

SI Weizheng, CHEN Min, LIU Jianhua, ZHU Yingbin, GONG Xu

2022, (3): 107-113. doi: 10.19287/j.cnki.1005-2402.2022.03.018

[Abstract] FullText HTML PDF(22514KB)

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This study is focusing on a working area of 720 mm×600 mm on a laser cutting machine. Use finite element analysis method to analyze its overall structure.The geometric error model of laser cutting machine is established. In order to analyze the geometric accuracy and position accuracy of the machine, the laser interferometer was used to test straightness, angle deviation and motion speed of the machine under dynamic and static situation.The finite element structural optimization design method is used to improve the structure and reduce the deformation gap at both ends of the gantry frame of the laser cutting machine. Meanwhile the errors in straightness and angle deviation have greater impact on machine accuracy. The straightness under static situation is larger than it is under dynamic situation. The motion speed, assistant pressure did not affect the straightness. Results show that to improve machine′s geometric accuracy, position accuracy and machining accuracy, it is useful to apply design and assembly optimizations.

Research on tracking and grinding control of inner wall spiral weld seam in super long cylinder section

QIAN Chen, LI Fangxin, WEN Shanshan, CHEN Yan, KUANG Tingyu, ZHANG Yong, ZHAO Weigang

2022, (3): 114-118. doi: 10.19287/j.cnki.1005-2402.2022.03.019

[Abstract] FullText HTML PDF(13531KB)

Abstract:

According to the grinding requirements of inner wall spiral weld of super long cylinder section, one kind of high-precision inner wall spiral weld grinding control method is designed. Through multiple means such as speed feedback matching and visual image compensation, a real-time tracking and detection mechanism is established, the problem of asynchronous tracking of spiral weld is solved, and the accurate grinding of weld is realized. The feasibility of this control method is verified by experiments. A full closed-loop software and hardware control system platform is built by using Siemens control system, servo driver, encoder and visual image system, combined with mechanical structure system, including roller frame, compliant grinding tool, motor and walking track. After debugging and verification, through the combination of real-time monitoring of image system and actual grinding effect, the effectiveness of this method applied to inner wall spiral grinding is verified, and accurate tracking grinding is realized.

Research on precision NC machining technology of large conical integral thin-walled shell

LI Yang, CUI Xin, ZHAO Yi, GUO Dongliang, WANG Yuanjun

2022, (3): 119-122. doi: 10.19287/j.cnki.1005-2402.2022.03.020

[Abstract] FullText HTML PDF(11794KB)

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In the industry, it′s the first time that a large conical integral thin-walled shell was adopted cnc manufacturing method using integral forging. In the process of machining, the main problems are complicated structure, high precision requirements, high material removal rate and difficulty in prcessing defommation control. Through analyzing the features of the workpiece, this paper degigns a reasonable tuming-milling processing plan, which realizes the effective clamping, stress change control and compensation processing of the shell workpicce, and ensures the design requirements of the finished workpiece.

Application of adjustable "one side two pins" positioning device

LV Liwei

2022, (3): 123-126. doi: 10.19287/j.cnki.1005-2402.2022.03.021

[Abstract] FullText HTML PDF(4244KB)

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"One plane and two pins" positioning is the most common mode of workpiece-fixture positioning and fixture-machine tool positioning. This paper introduces the design characteristics of an adjustable "one plane and two pins" positioning device, which can be used to connect the positioning pin with the machine tool fixture through the positioning pin base. The positioning device is also position-adjustable, facilitating optimized location of the positioning pin. Compared with the fixed "one plane and two pins" positioning device, this device features much greater operability, superiority and compatibility in the design and application of special fixtures, and can compensate and correct for the positioning error of fixtures to effectively eliminate the impact of various positioning errors, thereby improving the positioning accuracy of one plane and two pins positioning, and maximizing the positional precision of workpiece processing.

Application of improved gray wolf algorithm to optimize gray forecasting model in CNC machine tools

ZHANG Yingzhi, ZHU Jiwei, LIU Jintong, ZHAI Fenli, MU Liming

2022, (3): 127-131. doi: 10.19287/j.cnki.1005-2402.2022.03.022

[Abstract] FullText HTML PDF(3557KB)

Abstract:
Aiming at the problem of large prediction errors caused by the selection of background values in the traditional gray prediction model, a fault prediction model combined with the improved gray wolf algorithm is proposed. An improved gray wolf algorithm is designed to improve the algorithm parameters of the basic gray wolf algorithm and used to optimize the background value in the gray prediction model to obtain the optimal prediction model. Taking 8 fault data of CNC lathe spindle as an example, the prediction accuracy of the proposed method is compared with other gray models to verify the fitness and stability of the method.

Research on method of line structure light active vision weld seam detection

HU Dan, ZHANG Yanxi, WANG Jingjing, GAO Xiangdong

2022, (3): 132-137. doi: 10.19287/j.cnki.1005-2402.2022.03.023

[Abstract] FullText HTML PDF(6057KB)

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In order to realize weld dimension measurement and surface forming quality assessment, a weld forming quality inspection system based on line structure light was studied.Based on the principle of laser triangulation, the composition and calibration process of structured light vision sensor was discussed in detail, and the image processing is optimized, and the gray gravity center method based on boundary limit was proposed to extract the laser fringe center line. Using a single pixel laser fringe as the information source to characterize the weld contour, a multi-feature point extraction algorithm was used to detect the feature points of the laser fringe contour. The dimension calculation models of butt weld and fillet weld were established based on the identification of characteristic points of weld laser profile curve. Finally, the measurement of weld dimension were realized. The results show that the inspection system of weld forming can obtain satisfactory performance of weld inspection.

The identification and analysis of spatial geometric error and positioning error compensation of vertical machining center

YU Bo, ZHAO Wei, DU Xianchang, WANG Guilong, WANG Litao

2022, (3): 138-143. doi: 10.19287/j.cnki.1005-2402.2021.03.024

[Abstract] FullText HTML PDF(4495KB)

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In order to greatly improve the machining accuracy of the vertical machining center, so as to meet the high-precision requirements of contemporary CNC machine tools, for the three motion axes of the vertical machining center, an in-depth analysis of the geometric errors of the axial motion space is proposed, and the motion axis can be effectively identified to identify the six geometric errors in the motion space, the six spatial geometric error identification models are established, and the verticality errors of the associated axis linkage are effectively analyzed, and the verticality error identification analytical model is established. At the same time, for three independent motions based on the axial positioning error characteristics of the shaft, a highly applicable error compensation method is proposed, an error compensation model is established and the compensation implementation plan is refined. Experiments prove that the study of spatial geometric error identification analysis and positioning compensation methods can greatly improve the positioning accuracy of vertical machining centers.

Fatiguelife prediction model of carburized gear steel based on cumulative damage

DENG Hailong, LIU Bing, GUO Yang, KANG Heming, LI Mingkai, LI Yongping

2022, (3): 144-149. doi: 10.19287/j.cnki.1005-2402.2022.03.025

[Abstract] FullText HTML PDF(5925KB)

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Very high cycle fatigue tests were carried out on the axial high-frequency fatigue testing machine. The fatigue characteristics of carburized gear steel under different stress ratios (R=0 and R=0.3) were studied. The results show that when the stress ratio is 0 and 0.3, the failure modes of carburized gear steel are divided into surface failure and interior failure. The interior failure process is divided into fatigue crack initiation stage (from inclusion to fine granular area (FGA)), stable propagation stage (from FGA to fisheye) and instantaneous fracture (outside fisheye). Based on the cumulative damage method, the life prediction models of interior crack initiation and propagation stages are established, respectively. Finally, the fatigue life prediction model of carburized gear steel is established, prediction accuracy is higher.

Rotor fault diagnosis method of singular value entropy of Volterra model based on VMD

YANG Gongyong, DING Xiaonan, WANG Junqi, WEI Yingdong, ZHOU Xiaolong

2022, (3): 150-156. doi: 10.19287/j.cnki.1005-2402.2022.03.026

[Abstract] FullText HTML PDF(6873KB)

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Aiming at the non-stationarity of rotor fault signal and the inability to effectively extract sensitive fault features, a fault diagnosis method was proposed by combining the Volterra model of variational mode decomposition (VMD) and singular value entropy. The parameter selection methods affecting the accuracy of VMD decomposition were deeply studied, and the solutions to the related problems were given. Firstly, the measured rotor signals under different working conditions were decomposed by VMD, and the intrinsic mode function (IMF) sensitive to fault characteristics was selected by using the increment of energy entropy for phase space reconstruction, so as to establish the Volterra adaptive prediction model, and the model parameters were used as the initial eigenvector matrix. Then, the initial eigenvector was decomposed by singular value decomposition to obtain singular value entropy and singular value eigenvector matrix, which were used to describe the fault characteristics of rotor. Finally, the fuzzy C-means (FCM) algorithm was used to identify the rotor working state and fault type. The experimental results show that the proposed method can effectively realize the feature extraction and type recognition of rotor fault. Compared with ensemble empirical mode decomposition (EEMD), it is proved that this method has more effective fault feature extraction performance and is a feasible method.

Detection approach of metal surface defects by four-light-source photometric stereo method based on HALCON software

WANG Jinfeng, ZHANG Bingyu, WEN Congchuan, YAN Lixin, FAN Jiacheng, CHEN Kaile

2022, (3): 157-161. doi: 10.19287/j.cnki.1005-2402.2022.03.027

[Abstract] FullText HTML PDF(5081KB)

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In order to improve the detection efficiency of metal surface defects, a detection method based on four light source photometric stereo method is proposed. Firstly, CCD camera is used to collect images of four perforated metal samples from different spatial angles. Secondly, HALCON operator is used to calculate the surface gradient image based on the principle of photometric stereo technology of four-light-source, then it is converted to the average curvature image. Finally, the curvature value of each point of the image is converted to gray value, and the global threshold is used to segment the defect area. Compared with the classical photometric stereo method, the results show that the four-light-source photometric stereo method can accurately construct the surface gradient information of the image, and the average curvature information of the image can be used to detect the defects of the metal surface quickly.

Differential procurement management strategy based on material classification

YU Junfu, YU Zhen

2022, (3): 162-165. doi: 10.19287/j.cnki.1005-2402.2022.03.028

[Abstract] FullText HTML PDF(4107KB)

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Manufacturing companies have a wide variety of materials. A differentiated procurement management strategy based on the Kraljic model is proposed to address the procurement management of different materials. According to the characteristics of materials, from the two dimensions of profit impact and supply risk, materials are divided into four categories: strategic materials, leveraged materials, non-critical materials and bottleneck materials. From the above strategic materials, the core materials with extremely high supply risks are classified. By analysing the characteristics of the five categories of materials, the corresponding procurement strategy, supplier management strategy and inventory strategy are proposed. Through precise and differential procurement management, the purposes of ensuring the stability of material supply and reducing costs and supply risks are achieved.

Design of lean logistics system in assembly workshop in discrete SME

LIU Lei, WANG Shuo, FU Yajie

2022, (3): 166-169. doi: 10.19287/j.cnki.1005-2402.2022.03.029

[Abstract] FullText HTML PDF(3081KB)

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In accordance with lean idea, this paper established a make-to-stock mode for the intelligent whole-types-drug dispensers by analyzing the production characteristics of its functional modules. Based on Systematic Layout Planning (SLP), the U-shaped layout design of the assembly shop was completed. According to the layout, the pull material flow model was set up and the material classification and storage method based on modules was put forward. The proposed logistics system can greatly shorten the delivery period and effectively control waste and reduce costs to ensure high quality delivery of products.

Construction and implementation of data center for discrete equipment manufacturing enterprise

FENG Xianfeng

2022, (3): 170-176. doi: 10.19287/j.cnki.1005-2402.2022.03.030

[Abstract] FullText HTML PDF(8206KB)

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An enormous amount of data is generated by various types of information systems, CNC equipment, and elevated warehouses of discrete equipment manufacturing enterprises. However, how to achieve effective management, analysis, utilization of data, and making data becomes a core asset is a major problem faced by enterprises. By analyzing multiple dimensions such as data management, data governance, data resources and data storage, combined with the current situation of enterprise data and business development needs, the design concept of "unified planning and unified deployment" is adopted, the construction of the data center with business as the chain, data as the core, and data asset management as the support is carried out. Including various practical scenarios for the executive, management, and decision-making levels of the enterprise, realizing the management objectives of "business digitization, data capitalization and asset value", building the foundation for the digital transformation of the enterprise and the construction of the digital factory.

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2022 No. 3

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