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- 01Tribological Behaviors Comparison of Several Stainless Steels under Seawater Lubrication
- 02Comparison of different optimization algorithms used in torque converter design optimization
- 03Research on High Efficient Flank Milling Machining Technology for Similar Ruled 〖JZ〗Surface Integral Impeller Based on Inspection at Original Position
- 01Research on Periodic Verification Method for Repetitive Accuracy Test System
- 02Research on Fuzzy Adaptive Sliding Mode Control for Position Servo System
- 03An Overview on Intelligent Technique of Fault Diagnosis
- 04Chao Solution of Non-linear Equations and Its Application to Mechanism Synthesis
- 05Pneumatic Muscle Actuator
- 06Water Hydraulics and Its Future
- 07Simulation of Electrohydraulic Servo System Based on AMESim/Matlab
- 08A Study of High Pressure Waterjet Characteristics by CFD Simulation
- 09The Study of the Key Problem on the Transformation from Normal Machine Tool into NC Machine Tool
- 10Modal Analysis of the Large and High Effective CNC Milling Machine
- 01Colsed-loop control of hydraulic synchronization and its application
- 02Chao Solution of Non-linear Equations and Its Application to Mechanism Synthesis
- 03Giant magnetostrictive actuator and its application to fluid control components
- 04Overviews of AC Servo system and Its Advanced Control Strategies
- 05Pneumatic Muscle Actuator
- 06The Application of MATLAB in the Simulation of Vehicle Semi-active Suspension
- 07On Skill of Adjusting-tool of the Numerical Control Machining
- 08A Study of High Pressure Waterjet Characteristics by CFD Simulation
- 09The Study of the Key Problem on the Transformation from Normal Machine Tool into NC Machine Tool
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Tooth Surface Modeling and Load Performance Analysis of Large Modulus Cycloidal Bevel Gear Based on Conjugate Modification
CHEN Jinyu; NIE Shaowu; LI Daqing
Abstract:Aiming at the problem that large modulus cycloidal bevel gear is difficult to be machined on dedicated gear milling machine,a method of constructing the tooth surface model of cycloidal bevel gear suitable for machining centers was proposed.Based on the processing principle of cycloidal bevel gear and the geometric relationship between the cutter head and the gear,a calculation method of gear processing parameters was established.The gear theoretical tooth surface was deduced according to the mathematical model of the gear cutting tooth processing,and the gear numerical tooth surface was obtained through the tooth surface discretization method.Based on the gear meshing mathematical model,the pinion tooth surface which was completely conjugated with the gear tooth surface was derived.By constructing a second-order modification difference surface in the normal direction of the fully conjugated pinion tooth surface and superimposing it,the pinion numerical tooth surface which was partially conjugated with the gear tooth surface was obtained.Finally,the loaded tooth contact analysis flow with finite element was established.Taking a pair of large modulus cycloidal bevel gear applied to the mine reducers as an example,the gear 3D modeling and loaded tooth contact simulation with finite element were conducted using ABAQUS software.The results show that under actual loading conditions,the pinion tooth surface constructed by conjugate modification is in local internal diagonal contact with the gear tooth surface,and the loaded contact area moves inside the gear tooth surface due to meshing dislocation,and it does not leave the tooth surface to produce edge contact,so the tooth contact area can meet the engineering need.The simulation results verify the feasibility of modeling method of conjugate tooth surface modification.
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Research on Stacked Part Instance Segmentation Based on Improved YOLOv8
WANG Zhongxuan; ZOU Guangming; GU Haowen; XU Yantao; LI Chenjiarui
Abstract:In order to achieve rapid recognition and selection of stacked parts by robots in complex industrial environments,an improved YOLOv8s instance segmentation model was constructed and applied to real-time recognition and segmentation of stacked parts.To address the issue of difficult segmentation of stacked industrial parts,the original model′s backbone network was replaced with a PoolFormer backbone network with stronger feature extraction capabilities to improve the edge segmentation effect of stacked parts;in order to better filter out excess background information and retain key information,a better CARAFE upsampling module was introduced.The experimental results show that the average segmentation accuracy and prediction box accuracy of the improved model are 93.57% and 97.47%,respectively,which are 1.89% and 1.23% higher than the original model,and far higher than the YOLACT++and SOLOv2 models with the same type,verifying the effectiveness of the improved model.
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Study on the Effect of Different Process Parameters on the Micro-milling Performance of FeCoNiCrMnAlx High-Entropy Alloy
WANG Pengjia; LI Tan; WANG Zhe; ZHU Yushuo
Abstract:In order to investigate the micro-milling performance of FeCoNiCrMnAlx(x=0,0.6,1) high-entropy alloys,the effects of different process parameters such as spindle speed,feed per tooth,and milling depth on their micro-milling force,cutting specific energy,and surface roughness were investigated by single factor experiment.The results show that Al1 alloy has the largest milling force and the worst surface quality; Al0 alloy has better machinability due to lower milling force,cutting specific energy and surface roughness; the micro-milling force and surface roughness of the three alloys increase firstly and then decrease with the increase of spindle speed and feed per tooth,and increase with the increase of milling depth.In order to reduce the milling force and surface roughness of the alloy,the spindle speed and feed per tooth can be appropriately increased,and the milling depth can be reduced.
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Multivariate Statistical Process Control of Surface Uniformity in Electrochemical Processing
FAN Shuangjiao; LI Dengbang; YANG Yi; PANG Guibing
Abstract:Surface roughness of a part has a significant impact on its performance.In order to solve the problem that the single roughness parameter of the part surface cannot fully reflect the surface defects of the part,a method of applying multivariate statistical process control based on correlation analysis and principal component analysis was proposed to evalute the surface uniformity of electrochemical finishing parts.Two samples without and with surface defects were designed for comparative experiments,and a set of surface roughness parameters of the two samples were recorded after electrochemical finishing.Univariate statistical process control of multiple parameters was carried out,and then correlation analysis and principal component analysis of multiple roughness parameters were carried out to obtain the comprehensive evaluation value and to draw statistical control charts.The comparative analysis results show that for the surface with local defects,compared with the single roughness parameter,the comprehensive evaluation control chart is more accurate in detecting the surface defects of the parts.Multivariate statistical process control based on correlation analysis and principal component analysis is an effective method to evaluate the surface uniformity of electrochemical finishing parts.
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Research on Integrity of Micro-milling Laser Melting WC/Ni Alloy Powder Surface
WANG Bin; GAO Qi; SUN Wenqiang
Abstract:In order to explore the relationship between the micro-milling processing parameters of laser melting WC/Ni alloy powder coating and surface quality of the processing materials,mold steel Cr12MoV was selected as the substrate and WC/Ni alloy powder as the melting material.The laser melting processing experiments were carried out by fiber laser and experimental samples were prepared.Micro-milling experiments were carried out with tungsten steel carbide milling cutter with diameter of 1 mm.Single-factor and orthogonal experiments were designed respectively,and the influence of micro-milling parameters on the surface quality of WC/Ni powder melting coating was investigated by taking surface roughness Ra as the evaluation standard,and the milling mechanism was expounded.The results show that the effect of spindle speed on machining surface roughness is most significant,followed by feed rate,and the effect of milling depth is least.When the spindle speed is 9 000 r/min,the feed speed is 6 mm/min,and the milling depth is 0.04 mm,the minimum roughness is 0.014 μm.When micro-milling WC/Ni alloy powder molten coat,smaller processing parameters could be selected in order to obtain better processing surface quality.
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Inverter Nonlinear Compensation for PMSM Used in Industrial Robot Based on Current Estimation Lookup Table
LIU Guohe; ZHANG Jun; LONG Jiang
Abstract:Aiming at the problem that the traditional method can not fully consider all the nonlinear factors of inverters,a precise calculation method for error voltage based on the phase current estimation lookup table was proposed.On the basis of considering the influence of many nonlinear factors such as switch-off/on delays,dead time,and parasitic capacitance,the filtered current was used to perform error voltage lookup,which effectively avoided the influence of interference factors such as harmonics introduced by feedback current and current clamping on the nonlinear compensation strategy of the inverter by the meter lookup method.The servo motor support platform was built to verify the effectiveness of the proposed method in industrial robot control.The experimental results show that compared with the traditional nonlinear compensation strategy,the proposed algorithm has better current harmonic suppression ability and can achieve better compensation effect,and the compensated phase current THD is less than 1.5%.
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Multi-objective Modification of Cycloidal Gear Profile of RV Reducer Based on Improved MOPSO
WANG Cheng; WANG Shijun; RAN Chuandong; WANG Guanzhong
Abstract:In the process of RV reducer cycloidal gear modification,it is difficult to comprehensively improve the return difference and transmission error of RV reducer,and most of the cycloidal gear modification methods are single objective modification or weighted single objective modification,which is not in line with the actual engineering situation.Therefore,the transmission error model and return difference model were established by TCA method.A multi-objective particle swarm optimization algorithm with exponential nonlinear decreasing inertia weights and iterative updating learning factors was proposed.The return error and transmission error were taken as objective functions,the modified algorithm was used to optimize the compound modification quantity,and the optimal solution was obtained by membership function.Adams and MATLAB were used to analyze the return difference and transmission error of RV reducer under different modification methods. The results show that the return difference of the final optimized modification is reduced by 0.02′ and 0.04′ respectively,and the transmission error is reduced by 6.6% and 7.8% respectively.
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Research on Virtual Debugging Technology for Motor Base Stacking Line Based on Digital Twin
LIU Mengyuan; LI Huanfeng; SHA Jie; ZHOU Gaowei; LU Qingyang
Abstract:A virtual debugging method for motor base palletizing line based on simulation platform NX MCD was proposed to address the high cost of on-site debugging of production systems jointly controlled by PLC and ABB industrial robots,as well as the difficulty of driving robot simulations on simulation platforms.A simulation model of the production line was constructed in NX MCD based on digital twin technology.A communication framework for virtual debugging solutions was designed,mainly including secondary development of robot simulators to achieve control and data reading of robots.Finally,the real-time transmission and feedback of signals and data between PLC control,robot control,and NX MCD model were completed using OPC UA technology to complete the joint debugging of the production line.The simulation results show that the virtual debugging scheme for the motor base stacking line based on NX MCD is feasible,can timely avoid production line defects,shorten debugging cycles,and reduce development costs.
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Lightweight and Fatigue Behavior Research of the Rotor on Scroll Oil-Free Compressor
HAN Binbin; YUAN Yanxing; QIU Haifei
Abstract:According to the eccentric structure and high-speed characteristics of scroll compressor rotor,a parametric finite element modeling program for spindle components was developed by equivalent configuration of the elements like finite strain beam,2D bearing and 3D space mass etc.The Campbell diagram and critical speed of the spindle were obtained by running the rotor dynamics analysis under the influence of gyro effect.On the basis of the variables that consisted of the counterweight mass (m1,m2) and its centroid position ( R1,R2),the dynamic optimization of the rotor assembly was conducted,not only its first-order critical speed was increased by 4.2%,but also the total weight of the counterweight and the maximum stress amplitude were reduced by 0.413 kg and 0.21 MPa,respectively,reaching the expectation of the lightweight design.The simulation flow of fatigue analysis project in S-N stress form was constructed by using nCode DesignLife software,and the crankshaft fatigue analysis and damage assessment were realized under time series load mapping with multiple working conditions.The results show that the lightweight design can improve the minimum fatigue life of the crankshaft,significantly reduce the extent of damage and fatigue risk area near the crank end,and is conducive to improving the fatigue life and anti-damage ability of the crankshaft.
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BTA Deep Hole Connector Design and Oil Film Pressure Study
CHEN Zhenya; MA Zhuoqiang; LI Xiang; MIAO Hongbin; YANG Shangjin; LI Jian
Abstract:Aiming at the problem of insufficient rigidity of the tool system and unbalanced radial force during BTA machining process,a BTA deep hole connector was designed based on the fluid dynamic pressure lubrication principle.The connector included double-bridge strain gauges and tiltable tiles,which could increase the rigidity of the tool system by using the oil film support stiffness and offset the unbalanced radial force of synchronous detection by adjusting the oil film pressure in real time.The mathematical model of the tiltable tile was established,the oil film thickness equation was derived,and the oil film pressure calculation equation was further derived.The fluid simulation of the connector was carried out based on Fluent software,and the single factor experiment method was used to analyze the change law of the oil film pressure of tilting tile under different conditions.The results show that the oil film pressure can be adjusted by adjusting the parameters of workpiece speed,cutting fluid viscosity,tile tilt angle and tile wrap angle during BTA machining,so as to achieve the purpose of increasing the rigidity of the tool system and offsetting the unbalanced radial force.
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Evaluation of Roundness Error Based on Improved Crow Search Algorithm
ZHANG Zhiyong; ZHENG Peng; WANG Shiqiang; HAO Yongxing
Abstract:In order to solve the problem that the conventional heuristic optimization algorithms is inefficient in evaluating roundness error and easy to fall into local optimal solution,an improved crow search algorithm was introduced to evaluate roundness error.The mathematical model for evaluating roundness errors of crow search algorithm was formulated based on the minimum zone circle(MZC) fitting criterion,and the weight coefficient was introduced to enhance the global search capability of the algorithm.At the same time,the initialization of the starting position in proximity to the center of the least squares circle was implemented to improve the algorithm′s search efficiency.Finally,the accuracy and precision of the proposed algorithm were validated through simulations and experiments.It is found that the global search ability of the improved crow search algorithm is significantly improved compared with genetic algorithm (GA),particle swarm optimization (PSO) and traditional crow search algorithm (CSA) by comparing multiple sets of data.
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Artificial Intelligence-Based Machine Tool Spindle Fault Diagnosis Research
CHEN Qi; LIAO Linzhi; WU Niyan
Abstract:With the development of information and communication technology (ICT),the application of artificial intelligence techniques in machinery fault diagnosis has attracted the attention of researchers.In order to verify the trialability of artificial intelligence technology in machine tool spindle fault diagnosis,a test bench was constructed to collect the fault data by artificially changing the spindle eccentricity,and three kinds of artificial intelligence models (CNN,LSTM and AE) were used for learning,and their accuracy in classifying seven kinds of spindle fault states was analyzed and compared.The experimental results show that both CNN and LSTM models have high accuracy,with the CNN model achieving the highest accuracy at 99.3%,while the AE model has a relatively low accuracy of 76.9%.The feasibity of applying artificial intelligence technology in machine tool spindle fault diagnosis in verified.
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Failure Analysis and Response Surface Optimization Design of Engine Crankshaft under High Speed and Heavy Load
YAO Xingju; YU Jie; ZHU Shuailun; YUAN Wei; CHI Baotao; CONG Jianchen
Abstract:In the process of engine operation,the wear condition of crankshaft journal at different corners is different,which results in the reduction of the matching accuracy of crankshaft surface.Based on the stress and strain analysis of the crankshaft of the internal combustion engine,a 3D model of the crankshaft of the in-line six-cylinder was established based on the finite element method.According to the actual load of the internal combustion engine,constraints and loads were applied to the crankshaft and static simulation analysis was carried out.The results show that the maximum stress on the crankshaft occurs at the transition corner between the crankshaft journal and the crank pin,and the maximum deformation occurs in the center of the crank pin.The optimal analysis of crankshaft based on response surface method shows that:after optimization,the maximum stress and maximum deformation of the crankshaft are reduced,among which the maximum stress is reduced by 12.42% and the maximum deformation is reduced by 16.83%.To verify the feasibility of the optimization,an enterprise survey was conducted on the optimized crankshaft.Combined with the crankshaft failure rate and repair situation of the enterprise,it is concluded that the structure of the crankshaft can be effectively optimized by the response surface optimization method to improve the strength and reliability of the crankshaft.
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A Wind Turbine Blade Inverse Modeling Method Based on Design Intent Recognition
CAI Jiayi; CHENG Siyuan; HE Jinhan; YANG Xuerong
Abstract:Airfoil is the basic unit of wind turbine blades and plays a decisive role in blade performance.For the study of inverse modeling and redesign of blade structures,a method that combined airfoil extraction and design intent into blade inverse modeling was proposed.A laser scanner was used to extract the blade model,and the blade model was processed in Geomagic Design X.Through the coordinate system alignment of the blade model and the extraction of geometric features of the section profile,parameters such as blade thickness and chord length were measured,and the airfoil type of the section profile of the blade was derived.The airfoil curve expression was then used to calculate the key points which the contour curve passed through,and the blade cross-section contour line was obtained by fitting the key point positions as constraints,and its solid model was established.Through body deviation detection,it can be seen that this method can be used to obtain a CAD model that conforms to the airfoil characteristics and forward design intention under the condition of meeting the tolerance requirements,which verifies the feasibility of the method.
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Multi-objective Optimization Design of 4.1 MN Hydraulic Climbing Mechanism Based on Response Surface Method
SUN Xuan; HU Xianxuan; JU Chengwei
Abstract:Taking the hydraulic climbing mechanism,the main load-bearing core of the portal hydraulic lifting system,as the research object,in view of the different degrees of stress,deformation and large mass of the geometric structure of the hydraulic climbing mechanism after bearing 4.10 MN,SolidWorks software was used to carry out 3D modeling under the condition of ensuring that the structure met strength requirements,and a simulation analysis platform was built in combination with ANSYS software.Taking the angle of the wedge and anchor block,the thickness of the wedge,anchor block and square steel as the design variables,the maximum stress,maximum deformation and mass of the hydraulic climbing mechanism as the response,the MOGA optimization algorithm based on the response surface was used to carry out the multi-objective optimization design of the hydraulic climbing mechanism.The results show that the maximum stress of the optimized hydraulic climbing mechanism is reduced by 26.47%,the maximum deformation is reduced by 26.26%,and the quality of the geometric structure is reduced by 2.05%.After optimization,not only lightweight of the hydraulic climbing mechanism is realized,but also the comprehensive performance of the hydraulic climbing mechanism is significantly improved,and the multi-objective optimization optimal solution of the hydraulic climbing mechanism can be quickly and effectively obtained.
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Automatic Verification System of Pressure Meter Based on Machine Vision
DENG Yulan; LIN Feizhen; LIN Yanbo; SUN Tao; HUANG Feng
Abstract:Aiming at the problems of low efficiency and easy introduction of errors in visual readings when manually verification pressure meter,an automatic verification system of pressure meter based on machine vision was designed,and the control software and recognition method were developed.The control software was designed for automation processes,introducing multi-threading,containerization,and monitoring event technology.It controlled hardware such as PLC,robotic arm,industrial camera,and standard pressure generator in the system to achieve automation of the calibration process,and supported simultaneous verification of multiple pressure meter.Considering the low configuration of industrial computers,a lightweight recognition method was designed based on the deep learning model Paddle and the OpenCV library.This method not only takes up less memory and has fast operation speed,but also has richer recognition information and higher recognition accuracy.The experimental results show that the system can effectively improve verification,reduce human error,and has application and promotion value.
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Multi-objective Optimization Allocation of Mechanical System Accuracy Based on Cost Function and Precision Stability
LI Gang; LI Yanwei
Abstract:At present,when studying the motion precision allocation of mechanical transmission system,only the cost factor is considered,and the influence of the system motion precision stability on the precision allocation is ignored.Therefore,a multi-objective optimization allocation method of mechanical system based on cost function and precision stability was proposed.The meta-action theory was introduced and a precision cost function model for meta-action unit was established,and the comprehensive complexity coefficient was used to represent the relationship between meta-action unit precision improvement and the cost.Based on the motion error transmission model of the mechanical transmission system,the stability analysis model for the motion precision of the mechanical system was established.With the comprehensive cost and the system motion accuracy stability of mechanical system as the goal,a multi-objective optimization allocation model for mechanical system motion precision was established.The fuzzy set method was used to analyze the Pareto non-dominated solution set and to determine the optimal solution.Finally,taking the motion precision allocation of the NC rotary worktable system as an example,the proposed multi-objective optimal distribution method was compared with the single objective optimization allocation method,and the effectiveness of the proposed method was verified.
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Hydraulic System Design and Analysis of High-Pressure Actuator Pulse Test Bench
TONG Yibo; FANG Weisong; ZHANG Xu
Abstract:A high-pressure actuator pulse test bench was designed to evaluate whether hydraulic parts could effectively withstand pressure pulses during their service life.It was controlled by servo valve to simulate three pressure pulse waveforms in the working environment.Using AMESim,the model of the pulse bench hydraulic system was built and the pressure curves obtained by simulation were compared with the standard waveforms.Simulation analysis shows that the water hammer waveform generated by the hydraulic system meets the standard and technical requirements.The test bench was built according to the simulation results and selection calculation.Under the conditions of setting the test frequency at 1 Hz and the steady-state pressure of water hammer wave at 20 MPa,the measured peak pressure was 30.195 MPa and the rise rate was 1 338.9 MPa/s.All parameters meet the technical requirements,and the generated pulse waveform meets the national military standards.
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Research on Simulation and Optimization Design of Spinning Head Structure for High Speed Wire
LUO Liangchuan; CHENG Xiping; CHEN Min; LI Yunsheng; MAO Luyao
Abstract:In response to the common problems of high vibration,low continuous operation stability,and unstable wire drawing ring shape in high-speed wire rolling production,simulation optimization research was conducted on the wire drawing head,which is a key component of the wire drawing machine.Theoretical methods such as modal analysis dynamic control equation and dynamic balance calculation equation were used to establish geometric models,finite element models,kinematic models,etc,and critical speed analysis,modal analysis and dynamic balance simulation analysis were carried out to grasp the main reasons for high vibration of the wire drawing head.In order to eliminate the dynamic balance of the spinning head as much as possible during the design phase,finite element simulation software was used to perform modal analysis on the original spinning head.The obtained first critical speed of the original spinning head is 72.2 r/s,which is higher than the maximum speed of 40 r/s.Therefore,the spinning head can be dynamically balanced according to a rigid rotor.Then,a virtual prototype of the spinning head was established using dynamic simulation software,and double-sided dynamic balance simulation analysis was conducted to obtain the required correction mass of the spinning head on two calibration faces.The counterweight structure was designed according to the installation position.By optimizing the action balance of the spinning head,the dynamic unbalance mass of the spinning head on the two front faces decreased from 8.199 1 kg and 6.655 4 kg before optimization to 4.843 9×10-4 kg and 3.603 8×10-4 kg,and the first critical speed increased from 72.2 r/s to 72.75 r/s,meeting the design requirements.Finally,the optimized spinning head was installed on the hollow shaft of the spinning machine for on-site online dynamic balance testing experiments.The initial unbalance of the spinning head online dynamic balance was 27.4 g,with a phase of 232°.The horizontal vibration amplitudes of the two bearing position measurement points were 1.02 μm and 6.63 μm respectively.All are smaller than 10 μm,meeting design requirements.
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Research on Iron Roughneck Flexibility Control Based on Electromechanical-Hydraulic Joint Simulation
ZHANG Kaige; LIU Yanjun; XUE Gang; SHI Zhenjie; YIN Song
Abstract:There is a large load disturbance in the operation process of the iron roughneck,and it is necessary to realize force control under specific working conditions,and the control accuracy does not meet the expected requirements,which can easily cause damage to the pipeline.The impedance control method was used to control the movement of iron roughneck,and the displacement and force tracking of the hydraulic cylinder were simulated.The motion sketch of iron roughneck mechanism was established,and the equations of positive and negative kinematics were obtained by analytical method.In order to improve the flexibility of the trajectory,the motion trajectory of iron roughneck was planned by the method of fifth degree polynomial interpolation.The impedance control method was designed,the position control of inner loop was realized by the PID controller and the force was controlled by the outer loop.The dynamics model,hydraulic system model and impedance control model of iron roughneck were established by AMESim and Simulink respectively,and the operation process of iron roughneck was simulated by joint simulation.The results show that the iron roughneck has good position control accuracy in both non-environmental and environmental contact conditions,and the force tracking accuracy is increased by 42.4% compared with no impedance controller.
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Simulation Research on Characteristics of Proportional Directional with Pilot Flow Amplification
WANG Lijun; ZHAO Xingyu; QUAN Long
Abstract:Due to the lack of high dynamic flow measurement methods,it is difficult to directly measure the flow of pilot stage.A dynamic flowmeter with flow-displacement conversion function was designed,and the flowmeter was applied to the pilot stage of the displacement-flow feedback type proportional direction valve to measure and control the flow of the pilot valve,and form a proportional direction flow valve with pilot flow amplification.The simulation model of the proportional directional flow valve with pilot flow amplification was built in SimulationX,and the dynamic and static characteristics of the valve were studied.The results show that the valve has good static control precision and can accurately control the output flow;the larger the pressure difference between the inlet and outlet of the main valve is,the faster the dynamic response of the spool is;the load change will cause the flow overshoot,but the adjustment time is short.
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Simulation Analysis of Coupling Mechanism Between Fretting Wear Scar and Contact Stress Field
HAN Yiming; LI Xin; LIU Leqiang; YANG Jianwei
Abstract:Fretting wear is a main failure form affecting key mechanical structures.In order to study the evolution of wear scar and stress field and their coupling mechanism,a cylinder/plane finite element contact model was established by ABAQUS software,and the evolution process of fretting wear scar and contact stress field was simulated based on Archard wear model.Further,the coupling mechanism of wear scar and stress field during fretting wear was analyzed.The simulation results show that the wear scar is "W"-shaped under partial slip,the contact width and wear depth increase slightly and the maximum contact stress and shear stress increase slightly with the increase of cycle times;under the gross slip,the wear scar is "U"-shaped,with the increase of cycle times,the wear scar becomes wider and deeper significantly,the stress field in the contact zone widens and flattens.
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Characteristic Analysis of Hydraulic Control System of Paste Filling Support
CAO Lianmin; ZHANG Dekang; ZHAO Dongrui; CHEN Yixuan; ZHU Mingxing
Abstract:In order to improve the support performance and flexibility,and ensure the stability and reliability of the lifting and moving process,the dynamic characteristics of the column control circuit of the hydraulic system were studied and the overall stability was co-simulated.The results show that when the bearing pressure of the column does not exceed 1 000 kN,the maximum pressure of the rodless chamber of the outer cylinder and the middle cylinder is 42.2 MPa and 69 MPa respectively,and the stability of the column is good;when the bearing pressure is 1 100 kN,the maximum pressure of the rodless chamber of the outer cylinder and the middle cylinder is 52.5 MPa and 83.8 MPa respectively,and the maximum flow rate is about 400 L/min,which can release the pressure in time.Based on the co-simulation of ADAMS and AMESim,the time of falling column and rising column is 11.02 s and 24.98 s respectively,and the maximum inclination angle is about 1.3°.Through the field observation of the hydraulic system,it is concluded that the hydraulic support has good support and stability.It effectively solves the problems existing in the support of filling support in the past and realizes the efficient mining production mode of′coal mining-filling′ two shifts and one cycle.
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Magnetic Field Analysis of Permanent Magnet in Magnetron Sputtering Vacuum Device
GUO Hongyu; TENG Yan; HU Wanxing
Abstract:A solution to the high energy consumption issue of existing vacuum suction devices was proposed by integrating a magnetic control expansion vacuum generation and suction system.Magnetic field simulations were conducted using COMSOL to analyze the effects of different magnetic block shapes,distribution radii,and axial distances on the axial magnetic forces between permanent magnets.The simulation results indicate that among the four selected magnet arrangements,the cylindrical magnet arrangement exhibits the strongest axial magnetic force; to achieve maximum axial magnetic force,the magnets need to be separated; however,further increasing the distribution radius results in negligible changes on the magnetic force Fτ.Experiments were conducted using N38 neodymium-iron-boron cylindrical magnets with a thickness of 10 mm and a diameter of 20 mm.The magnetic forces at different axial distances and distribution radii were measured.The experimental results validate the simulation outcomes,demonstrating that the absolute value of the magnetic force between magnets is negatively correlated with the axial distance; when the axial distance is 5 mm and the distribution radius is 17 mm,the maximum magnetic attraction force is 109.7 N,and the maximum magnetic repulsion force is 88.71 N,satisfying the operational requirements of the magnetically controlled vacuum expansion device.
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Influence of Surface Texture on Tribological Properties of Slipper Pairs of Miniature-Axial Piston Pump
LI Jia; WU Huaichao; HOU Gang; WANG Peijin; CAO Mingyuan; ZHU Bin
Abstract:In order to reduce the friction coefficient of the slipper pair of the miniature-axial piston pump and improve the lubrication performance of the oil film,elliptical micro-texture was designed on the bottom of the slipper shoe,the geometric model of the slipper pair was established,and the oil film pressure field and shear field of the slipper bottom were solved and analyzed by using the flow field simulation.In order to further enhance the effect of dynamic pressure,increase the bearing force and reduce the friction coefficient,the experimental level table was designed by Design-Expert response surface analysis for calculation and analysis.The mathematical model was established with the minimum leakage,maximum bearing force and minimum friction coefficient as the objective functions,and the optimized size of the miniature-texture was finally obtained.After optimization,the oil film lubrication performance of the slipper pair is improved,and the optimized parameters can be used as the basis for structural optimization of the plunger pump.
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Research on Spool Frequency Response and Flow Output Characteristics of High Speed On-Off Valve
CHEN Nan; WEI Rulu; XIE Fangwei
Abstract:In order to solve the problem that it is difficult to accurately evaluate the frequency response rule and flow output of high speed on-off valve spool in the field of digital hydraulics,a dynamic performance analysis method of high speed on-off valve based on load force function was proposed.The spool dynamics model was derived,the simulation models of electromagnet and the flow field were established,and the no-load dynamic characteristics of the electromagnet were studied.The frequency response and flow output characteristics of the spool were finally obtained by adding the load function and adopting the machine-electric-hydraulic co-simulation method.The simulation results show that the model can reflect the spool frequency response and flow output rule well.The opening time of the high speed on-off valve is 13.9 ms,the closing time is 14.3 ms.When the control frequency is 20 Hz and the duty cycle is from 30% to 70%,the flow modulation linear region is from 1 L/min to 1.9 L/min.With the increase of control frequency,the flow adjustable interval of high speed on-off valve decreases.When the control frequency reaches 40 Hz,the flow rate of the high speed on-off valve is almost unmodulated.
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Analysis and Optimization of Oil Cooling Effect at the End of a Flat Wire Motor Used in a Certain Vehicle
CHEN Song; XU Pingxiang; LIU Yuxi
Abstract:The research object was an oil cooled flat wire motor with a rated power of 230 kW used in a certain electric vehicle. A finite element model was established based on relevant parameters and loss analysis under high-speed operating conditions was conducted.Based on heat transfer,fluid dynamics and finite element method,simulation calculations were conducted on the original structure.The results show that the uneven flow rate and pressure at the front and rear fuel injection ports result in uneven distribution of the motor temperature field and large temperature difference.In response to the uneven spraying and large temperature difference of the front and rear fuel injection rings,the key structure and parameters of the cooling system were optimized through calculation and analysis.Then,the fluid and temperature fields characteristics of the optimized cooling system were calculated and analyzed,and compared with the structure before optimization.The results show that the optimized fuel injection ring has a more balanced velocity and pressure difference at the front and rear outlets,and the temperature difference between the stator and its winding at the front and rear ends is significantly reduced.The highest temperature decreases by 9.1%,and the maximum temperature difference decreases by 17.3%.The overall cooling performance of the motor system is significantly improved.
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Review on Geometric Error Compensation of Gear Processing Machine Tools
YANG Jianjun; SI Linlin; LIN Shoujin; LIN Xin
Abstract:The machining accuracy of gears is a key bottleneck which limit the development of high-end equipment.The high-precision gears can be achieved based on the advanced gear manufacturing machine tool.Due to the complexity of the structure and movement of gear machine tools,the difficulty of geometric error compensation is increased greatly.By analyzing the geometric error compensation technology of multi-axis universal machine tools at home and abroad in recent years and combining with the development status of geometric error compensation of gear machine tools,the geometric error compensation technology of gear machine tools was summarized.The sources of geometric errors of gear machine tools were summarized.Four theories were introduced that could be applied to geometric error modeling,such as multi-body system theory,screw theory,differential motion matrix and stream-of-variation theory.The methods of measuring and identifying geometric errors of linear axis and rotating axis by laser interferometer and ball bar instrument were analyzed.The geometric error compensation method by modifying NC data to was summarized.It provides a reference for the geometric error compensation design of gear processing machine tools.
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Remaining Useful Life Prediction of Rolling Bearings Based on Transformer-GRU Parallel Network
TANG Guiji; LIU Shuhang; CHEN Jinpeng; XU Zhenli; TIAN Yinchu; XU Xinyi
Abstract:In order to effectively describe the performance degradation trend of rolling bearing and accurately predict its remaining useful life,a method for predicting the remaining useful life of rolling bearings based on multi-domain characteristics fusion in Transformer-GRU parallel network was proposed.An evaluation index was established to screen the sensitive features for the time domain,frequency domain,and time-frequency domain of the rolling bearing vibration signal,and the sensitive features with high scores were obtained and the degraded feature set was obtained.The degradation feature set dimension was reduced by using self-coding to reduce data complexity and redundancy,and the degradation curve of rolling bearing was obtained.Finally,the remaining useful life prediction was carried out using Transformer-GRU parallel network,and the method was applied to the analysis of the public bearing dataset.The results show that the Transformer-GRU parallel network can not only capture long-term dependencies in input sequences efficiently and accurately,but also process features between time series better.Compared with LSTM,GRU and other classical methods,the proposed method can effectively predict the remaining useful life of rolling bearings.
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Composite Fault Diagnosis of Rolling Bearing Based on Optimized VMD-MCKD and Spectral Kurtosis
WANG Fuke; GAO Bingpeng
Abstract:Aiming at the difficulty of fault diagnosis due to the difficulty of extracting complex fault features from the vibration signals of rolling bearings,a novel method for complex fault diagnosis of rolling bearings based on optimal variable mode decomposition (VMD) and maximum correlation kurtosis deconvolution (MCKD) combined with fast spectral kurtosis algorithm was proposed.The parameters of VMD and MCKD were optimized using the improved sparrow search algorithm (ISSA),and the compound fault signal was decomposed using the optimized VMD and the effective intrinsic mode functions (IMF) were screened according to the kurtotic criterion for signal reconstruction.The optimized MCKD was used to deconvolve the reconstructed signal and enhance the fault feature.The deconvolved signal was analyzed by envelope spectrum to extract the fault feature frequency.The fast spectral kurtosis algorithm was used to process the deconvolution signal without fault characteristic frequency extracted to obtain the frequency band parameters with the most abundant fault information and perform band-pass filtering.Finally,the envelope spectrum of the filtered signal was analyzed,and the fault characteristic frequency was extracted to realize the fault diagnosis.The simulation and experimental results show that the proposed method can be used to effectively separate the complex fault and extract the fault characteristic frequency,so the complex fault diagnosis is realized effectively.
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Rolling Bearing Fault Diagnosis Model Based on Mel Spectral Data Enhancement and ResNet Network
GAO Zhikang; WANG Yanxue; YAO Jiachi; LI Xinming
Abstract:Aiming at the difficulties of industrial data acquisition and the limited ability of sparse data feature extraction,a rolling bearing fault diagnosis model based on Mel spectral data enhancement and ResNet network was proposed.In order to increase the diversity of training sample data,Mel spectral data enhancement technology was introduced,and the generalisation ability of the model was improved,so it could better adapt to variety rolling bearing fault situations.Through the stacking depth of the residual units of the ResNet network,the complex fault feature information could be captured,and the fault mode of rolling bearings was identified effectively.Finally,the rolling bearing fault data collected at the experimental site were validated and evaluated. The results show that the diagnostic accuracy of the proposed model on the enhanced dataset is as high as 99.83%,which is 1.39% higher than the original dataset.Compared with other methods,the model achieves significant improvements in accuracy and robustness,and is able to identify different fault types of rolling bearings more accurately.
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Fault Prediction Method for Electric Submersible Pumps Based on LSTM-PNN Neural Network
ZHOU Yifei; LIU Xinfu; CAO Yanfeng; YU Jifei; OUYANG Tiebing; LIU Chunhua; ZHOU Wei
Abstract:A fault prediction method for electric submersible screw pumps was proposed,addressing the challenges of timely fault detection and accurate fault type identification.The method combined long short-term memory networks (LSTM) and probabilistic neural networks (PNN).The LSTM network was employed as a regression model to predict the future trends of fault signals using time series analysis.The faulty signals of the screw pump were processed using wavelet packet decomposition to extract the fault features.Multiple operating parameters such as oil pressure and production yield were combined to construct the fault feature vector for the electric submersible screw pump.The PNN network was then utilized to classify and identify the predicted fault signals.A dataset of 120 sets of failure data from the Xinjiang Oilfield was collected for training the prediction model,and 90 sets of data were taken out as a fault database to train the model,30 sets of data were selected as the test set to evaluate the accuracy of the model.The LSTM-PNN neural network prediction model was applied to predict the faults in the electric submersible screw pumps using the two groups of data separately.The results show that performing fault feature extraction on the fault signals can effectively improve the accuracy of fault prediction for electric submersible screw pumps.Compared to traditional methods of fault prediction,the LSTM-PNN network demonstrates better predictive performance and its accuracy increases from 3% to 16%.
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Research on Improved Fault Diagnosis Method of Hydraulic Pump Based on Optimal NAS
ZHENG Zhi; LIU Tongyao; ZHAO Wenbo; LIU Weimin; WANG Zhijun
Abstract:In view of the low performance evaluation efficiency of neural architecture search (NAS) method in searching optimal structure,and the low diagnostic accuracy of hydraulic pump fault diagnosis due to poor model generalization ability,an improved Data-free NAS method was proposed.CAME optimizer and cosine annealing with warm restart algorithm were introduced to replace SGD optimizer and LambdaLR optimization algorithm,respectively,to improve the performance estimation and verification functions of Data-free NAS such as diagnostic accuracy and computational efficiency.Through the verified analysis of the hydraulic pump fault measured fault experiment,it can be seen that the improved method has obvious effectiveness and superiority over the original method;the CAME optimizer has obvious advantages in optimizing hyperparameters such as learning rate and momentum weight of the network,with accuracy and efficiency improved by 7.24% and 37.5%,respectively,with an accuracy up to 100%; the learning rate parameters can be improved by cosine annealing with warm restart algorithm,and the efficiency is improved by 81.25%.
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A New Method of Bearing Fault Intelligent Diagnosis Based on WGAN-div and DLA34 Models
LI Jingyu; DONG Zengshou; KANG Lin; SHI Hui
Abstract:Aiming at the problem that the equipment runs in normal operation state for a long time in actual industrial scenarios,the fault samples are not easy to obtain and the types of samples are not balanced,which lead to performance degradation of data-driven deep intelligent diagnostic model,a two-stage processing model based on Wasserstein-divergence generative adversarial networks(WGAN-div) and deep convolutional neural networks DLA was proposed.WGAN-div was used to generate fault samples to achieve class balance among samples,and the balanced data set was fed into DLA34 network for feature extraction and fault classification.DLA34 could integrate semantic and spatial information of each layer with its special aggregation structure to achieve deeper information sharing.Finally,the bearing failure dataset of Case Western Reserve University was used for verification.The experimental results show that WGAN-div in the proposed model can generate samples that are highly similar to the original samples,and the data balancing effect is better than that of the current mainstream GAN,WGAN and DCGAN.The accuracy of fault recognition completed by DLA34 can reach 100% on the set of data sets.