最新刊期
期 10 ， 2018
- 摘要：In order to improve the absolute positioning accuracy for the drill rod of the three-arm rock-drilling jumbo,firstly,based on the finite element simulation,the main parameters that affect the flexible error of the arm are determined by the orthogonal test method, and the flexible error compensation formula is obtained. Then,after the transformation of the force joint coordinate system,the calibration model is set up based on the kinematics position error,and the redundant parameters are eliminated in the model by redundancy analysis. Finally,the laser total station is used as the measuring device,and the LM algorithm is used to solve the calibration parameters to verify the kinematics calibration effect. The results show that the method effectively compensates the absolute positioning error of the drill rod,the absolute positioning error of the drill rod is reduced by 79. 6%.关键词：Three-arm rock-drilling jumbo;Kinematics calibration;Orthogonal test;Flexible compensation
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发布时间：2022-10-20 - 摘要：A detection method of gear tooth flank bump is presented,which is used to determine the position of bump surface of spiral bevel gear. A meshing model of hypoid gear pair is established,and the V,H,J adjustment is solved by changing the offset of the contact zone to obtain the position of the TCA contact zone under the planned path. The V,H,J calculation result is used to guide the rolling inspection experiment. In YX-HTT600 gear error measurement and analysis of comprehensive testing machine rolling test,the transmission error measurement results of the two cases of hypoid gear pair normal tooth surface and the existence of bump tooth surface are got. By comparing the measurement results of the two kinds of transmission errors,the feasibility of the proposed tooth surface measurement method is verified. The experimental results show that the proposed tooth surface detection method can be used to detect the entire tooth surface of spiral bevel gears. The test results can reflect the position of the bump surface and the number of the tooth surface with bumping points,which can lay a foundation for further improving the meshing performance of the spiral bevel gear basis.关键词：Hypoid gear;Path planning;TCA simulation analysis;Transmission error
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发布时间：2022-10-20 - 摘要：The numerical simulation of spray lubrication and improvement of lubricant condition in a complex gearbox are researched. An experimental rig for spray lubrication of a pair of high-speed gears is set up and relevant experiments are carried out firstly. The experimental results are used to verify the correctness of numerical simulation method. Then numeric model of spray lubrication in a complex gearbox is established and simulation as well as analysis are conducted. The results show that overlong spray distance,angle of end face and jet flow on out of mesh side make against to lubrication. Then optimization of spray angle based on single-phase flow computational method is studied. Result show that,there is a weakest trace of air in the center plane of meshed gears. And if the axis of the nozzle lays on this trace,the meshed gears will have their best lubricant performance.关键词：Complex gearbox;High-speed gear;Spray lubrication;Experimental rig;Numerical simulation;Single-phase flow;Optimum spray angle
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发布时间：2022-10-20 - 摘要：The noise orthogonal test of the automotive synchronous belt transmission system is carried out based on two wheels of unloaded test method. The influence law of the three parameters of the active wheel speed,synchronous belt bandwidth and tensioning force on the synchronous belt transmission noise is analyzed systematically. The orthogonal table is extended by regression,without any increase in testing time,a regression mathematical model is established based on the objective function of automobile synchronous belt transmission,and the accuracy of the mathematical model is verified by experiment. A method for the research of the influence factors of transmission noise of automobile synchronous belt is provided,and the prediction of transmission noise of automobile synchronous belt is realized.关键词：Automotive synchronous belt;Noise;Orthogonal test;Regression analysis
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发布时间：2022-10-20 - 摘要：The internal excitation of gear meshing transmission is the key factor that causes gear vibration and noise. Taking a pair of constant meshing helical gears in an 8-speed automatic transmission as the research object,the internal excitation of meshing transmission process is studied thoroughly,including the tooth surface contact state,time-varying meshing stiffness,error excitation and meshing impact. The finite element method is used to analyze the static and dynamic contact process of helical gears to get the magnitude and distribution of tooth contact stress. The change of contact line length is used to represent the time-varying meshing stiffness. The time-varying meshing stiffness of helical gear is obtained by theoretical analysis and finite-element simulation. Theoretical analysis and finite-element method are used to analyze the error excitation of helical gears,including the meshing error,the static transmission error and the dynamic transmission error. The finite-element method is used to analyze the meshing impact to obtain the root stress of gear transmission. The stress distribution on tooth contact line is calculated by the finite-element method. The above research lays the foundation for the improvement of helical gear transmission state.关键词：Helical gear;Meshing contact analysis;Meshing stiffness;Error excitation;Meshing impact
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发布时间：2022-10-20 - 摘要：The magneto-rheological fluid brake of electric vehicle is regarded as the research object,the internal structure of the magneto-rheological fluid is analyzed and its structure is optimized,and the theoretical model before and after optimization are established,the relationship between the braking torque and coil current and brake speed and braking time are calculated by Matlab,the experimental method is used to verify the calculation results. The theoretical calculation and experimental results show that there is a large optimization space for the internal structure of magneto-rheological fluid brake,the braking performance of the magneto-rheological fluid braking system can be improved by optimizing the internal structure of the brake,at the same time,it provides an important foundation for the precise control of the electric vehicle brake system,the experimental results and the theoretical calculation results are basically similar to verify the accuracy of theoretical calculation. This research can provide the theoretical basis and important reference for the braking efficiency improvement of electric vehicle and precise brake control.关键词：Electric vehicle;Magneto-rheological fluid brake;Optimization;Braking characteristic
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发布时间：2022-10-20 - 摘要：The initially curved flexible beam is considered as a straight beam with the free end loaded a moment Mi,and the theoretical trajectory and corner of the initially curved flexible beam’s end are derived according to the Bernoulli-Euler equation. The theoretical results are given with example,and are compared with ANSYS simulation to verify the effectiveness of the theory. Secondly,based on the1 R pseudo-rigid-body model（ PRBM） of the straight beam subjected to the moment,the 1 R PRBM of the initially curved flexible beam subjected to the moment is firstly developed and is compared with the theoretical results to verify its effectiveness. Finally,aiming at the deficiency of the PRBM model,the modified model of the 1 R PRBM of initial curved flexible beam subjected to moment is put forward and compared with the theoretical results and the 1 R PRBM model to verify its effectiveness,which lays the foundation for studying the compliant mechanism with the initially curved flexible beam.关键词：Initially curved flexible beam;Pseudo-rigid-body model（PRBM）;Trajectory
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发布时间：2022-10-20 - 摘要：Aiming at the problem of frequent shift phenomenon of the vehicle running in the uphill condition,and the unexpected upshift phenomenon of the vehicle running in the downhill condition. The value of slope is identified based on the EKF algorithm and the dynamics model of ramp. On the basis of ramp identification model and traditional shift schedule,a real time online optimization of dual clutch transmission（ DCT） gear is presented based on fuzzy control method. A simulation model of vehicle fuzzy shift control is established by using MATLAB/Simulink,and the simulation and comparison analysis of the shift schedule of the vehicle before and after the optimization are carried out. The results indicate that the optimized vehicle shift schedule could effectively avoid the frequent shift and unexpected upshift of vehicle. The riding comfort of driver and the vehicle safety are improved.关键词：DCT;Ramp identification;Shift schedule;Fuzzy control
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发布时间：2022-10-20 - 摘要：A rolling bearing remaining useful life prognostics method based on improved Continuous hidden semi-Markov model（ CHSMM） is proposed,aiming at the problem that the CHSMM algorithm prognostics accuracy is low for remaining useful life of rolling bearings. The feature vectors of the time and time frequency domain are extracted from the vibration signal of bearing and then the PCA algorithm is used to reduce the dimension of the feature vectors. Then,the degradation state recognition model and the remaining useful life prediction model are established based on improved CHSMM into which the Gauss mixture probability density function is introduced aiming at solving the low accuracy of remaining useful life prediction caused by the dwell time probability density function which does not conform to reality. Finally,the whole life cycle data of the bearing is input into the model,and the degenerate state and residual life of the bearing are obtained. The experimental results show that the proposed method can accurately predict the remaining useful life of bearings.Compared with the original CHSMM algorithm,the accuracy of the degradation state recognition is increased by12%,and the accuracy of remaining useful life prediction is increased by 23%.关键词：Bearing;CHSMM;PCA;Remaining useful life
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发布时间：2022-10-20 - 摘要：For the problem that the friction power loss of the deep groove ball bearing will directly affect the transmission efficiency of the gearbox,the composition of the friction torque of deep groove ball bearing under quasi-static condition is analyzed. By changing the size of the bearing clearance to reduce the friction power loss is also proposed and a bench test to explore the influence of the bearing clearance on the transmission efficiency of the gearbox is designed. Finally,the experiments of the whole vehicle taxiing resistance and fuel consumption are verified. The result shows that properly increasing the bearing clearance can reduce the friction power loss of deep groove ball bearing and improve transmission efficiency,it also can increase the vehicle taxi distance and reduce the vehicle fuel consumption. This study provides a reference for the selection of bearing clearance of gearbox.关键词：Bearing clearance;Gearbox;Transmission efficiency;Fuel consumption
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发布时间：2022-10-20 - 摘要：To improve the dynamic performance of the pusher device in an ultra high-speed packaging machine,the optimization design and analysis on dynamic balance are performed. Based on the multi-rigid-body dynamics theory,a dynamic model of the pusher device is established. Major components for producing inertia force and torque are acquired according to the dynamic model. The equations of shake force and torque are derived by building a mathematical model for the components. Taking the root-mean-square of shake force and torque into account,dynamic balance of the components with variables of mass and barycentre location is optimized based on a micro multi-objective genetic algorithm. According to the optimal value of variables,the structure of the pushing hands is redesigned. After optimization,the shake force and torque of the packaging machine are reduced by 23. 6% and 29. 5% respectively,and natural frequency of pushing hands is not close to260 Hz anymore. The results show that dynamic performance of the pusher device is improved obviously and the resonance is avoided.关键词：Ultra high-speed packaging machine;Pusher device;Micro multi-objective genetic algorithm;Dynamic balance optimization
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发布时间：2022-10-20 - 摘要：Aiming at the globoidal indexing cam mechanism,through the theoretical analysis of conjugate surface theory and the differential geometry,the construction method of the universal surface equation of globoidal indexing cam is presented based on transformation of homogeneous coordinate. Then the software of surface points collection system of the globoidal indexing cam is developed based on VB. The 3 D modeling and motion simulation of the globoidal indexing cam mechanism are set up in Pro/E. The mechanism design and motion simulation verification example shows that the designed globoidal indexing cam mechanism satisfied the indexing expectation.关键词：Homogeneous coordinate;Globoidal indexing cam;Modeling;Motion simulation
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发布时间：2022-10-20 - 摘要：Taking the stereo garage as the research object,the advantages and disadvantages of the stereo garage is analyzed. The vertical circular stereo garage is selected as example,the structural improvement of lift system is carried out,the issue of the chain structure is analyzed,and the innovative design of a bias fork chain drive mechanism is carried out. The design idea of the chain drive and the design method of the main parameters are expounded. The comparison and elaboration of the core non-standard parts before and after the improvement are carried out. The Pro/E software is used to model the bias fork chain drive mechanism. The motion simulation module of software is used to simulate the trajectory curvature of the chain plate and the feasibility of the motion of the detection mechanism. The rationality of meshing of the movement of the simulated chain plate is determined. The accuracy of the mechanism transmission ratio is verified by simulated chain plate movement. The results show,bias fork chain drive mechanism is able to reduce mechanical vibration,reduce transmission noise,ease the polygon effect,the performance is more stable.关键词：Vertical cycle stereo garage;Bias fork chain drive mechanism;Motion simulation
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发布时间：2022-10-20 - 摘要：Facing with the urgent need of tools for the elderly and disable,which is brought by the rapid increase in the number of the elderly in recent years,plan to design an exoskeleton-assisted robot from a bionic angle. After determining the use of a push-pull flexible shaft to drive a motion joint,the design of mechanism and structure of shoulder and elbow joint of exoskeleton robot is completed first. Then the ankle joint and other flexible drive are designed,and the activity range of each joint is analyzed. Finally,the dynamics analysis of the leg joint and the foot joint and kinematics analysis of robot’s gait are carried out in the dynamics simulation software. In summary,as a kind of assist tool for the elderly and disable,the robot can meet the requirements of motion smoothness and speed stability.
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发布时间：2022-10-20 - 摘要：An iterative rapid search algorithm of spherical coordinate variable step size is used to analyze the reachable workspace of a 3 T1 R parallel mechanism. The size of the mechanism is optimized by using the beetle antennae search algorithm. Firstly,the position of the mechanism is analyzed and its kinematic inverse solution is obtained. Then,an iterative rapid search algorithm with spherical coordinate variable step size is used to solve the reachable workspace of the 3 T1 R parallel mechanism. The workspace is measured by the size of workspace index,the influence of the structural parameters of the parallel mechanism on the working space volume is quantitatively analyzed. Finally,taking the maximum working space volume as the target,the structural parameters of the parallel mechanism are optimized by using the beetle antennae search algorithm,and the optimal value is obtained. The algorithm has fewer calculation steps and fast solution speed,which provides a theoretical basis for the practical application of such parallel mechanism.关键词：Parallel mechanism;Workspace;Spherical coordinate;Beetle antennae search algorithm;Parameter optimum
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发布时间：2022-10-20 - 摘要：The three-dimension coordinate equation of tooth surface of spiral bevel gear is obtained based on the forming principle of spiral bevel gear. According to the spiral bevel gear computational adjustment cards provided by the Gleason company,the three-dimensional model of spiral bevel gear pair is established by writing the MATLAB program to solve out the 3 D coordinates of discrete points on the tooth surface and using three dimensional modeling software. The contact analysis of bevel gear pair is completed by importing the 3 D model into the finite element software Abaqus to create the finite element model of spiral bevel gear. According to the analysis results,the change of the contact positive pressure of a pair of gear teeth in a complete meshing cycle is obtained,and the accuracy of the simulation results is verified by experiments which provides reference and technical support for the design,manufacture and optimization of spiral bevel gear.关键词：Spiral bevel gear;Tooth surface equation;ABAQUS;Contact analysis
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发布时间：2022-10-20 - 摘要：The locomotive traction gear is the key component to power transmission and speed control of locomotive drive system,which plays a key role in locomotive running speed and Bearing torque. With the need of different locomotive design,the parameterized modeling of the traction gear can effectively reduce the development cycle. The formation equation of involute tooth profile and transition curve is introduced,and the tooth profile modeling is carried out in the SolidWorks 3 D modeling software environment by Program-driven method. Taking a certain type of locomotive traction gear as an example,the finite element simulation of the gear is carried out. The comparison and analysis of the contact stress of the tooth surface and the bending stress of the tooth root are compared with the theoretical results,and the accuracy and rationality of the design and modeling of the traction gear is verified. It is of great value to the rapid design and simulation of the traction gear.关键词：Traction gear;Parameterized modeling;Finite element simulation;SolidWorks
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发布时间：2022-10-20 - 摘要：The stair climbing wheelchair is mainly used to assist vulnerable groups to achieve stair climbing process,so its reliability and stationarity is particularly important. By adopting composite stair climbing wheelchair structure,a new crawler chassis which overcomes the problems existing in the traditional crawler structure ladder climbing process is designed. Under the environment of the Track LM module of RecurDyn,the repeated simulation and modification of the climbing process of the designed wheelchair are carried out. Finally,a modified dynamic simulation process is obtained,and the driving torque,the vibration displacement and the acceleration curve of the center of gravity in vertical direction are extracted. The realization of the simulation process has important guiding significance for the type selection and assembly of a new type of physical prototype of the staircase wheelchair.关键词：Stair climbing wheelchair;Crawler;Recurdyn;Simulation;Design
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发布时间：2022-10-20 - 摘要：In consideration of the effect of the work stroke of lifting cylinder and bucket cylinder on the working performance of loader,the work strokes of the two cylinders are then selected to be design variables together with the position coordinates of the pivot points of the reverse-six-link mechanism,at the same time,the optimization objective is set to improve the ratio of transferring force of lifting cylinder under the condition of meeting the performance indexes and other constraints. With the help of ADAMS/View software,a parameterized model of reverse-six-link mechanism of type ZL50 loader is built,and optimization design is carried out. The design result shows that the translation performance and the unload distance,as well as the ratio of transferring force of lifting cylinder are greatly improved,those requirements of the optimal design are achieved.关键词：Loader;Reverse-six-link mechanism;Optimal design
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发布时间：2022-10-20 - 摘要：A kind of dual-motor driven walking mechanism which consist of six upright walking legs made up of connecting rods is designed. Firstly,through analyzing the principle of walking leg mechanism,the simple planar four-bar linkage is decomposed by unilateral walking leg mechanism. Based on complex vector method,the kinematical equation is established. According to the kinematics equation,the analysis of the position of the movement,the limit position is find out,the position map of the walking leg mechanism is drawn,the movement space of the walking leg is determined,and whether the interference occurs is judged. Finally,a prototype is built to verify the feasibility of the design scheme. The prototype test results show that walking leg mechanism can meet to working requirements of six-legged walking robot,this design scheme is feasible. The basis for the next optimization design and development of new walking robots is provided,it has important research significance.关键词：Walking mechanism;Six-legged;Link mechanism;Kinematics analysis
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发布时间：2022-10-20 - 摘要：The nutation gear drive is a new type of planetary transmission with wide application prospects.In order to improve the serviceability of the nutation reducer,it is necessary to clarify its dynamic characteristics. Taking the nutation reducer with bilateral meshing and two-stage spiral bevel gears drive as the research object,the 3 D modeling and virtual assembly of the reducer is completed based on the SolidWorks platform.The multibody dynamics model of the nutation reducer with bilateral meshing and two-stage spiral bevel gears drive is established by ADAMS,and the dynamic characteristic simulation of the reducer is carried out. The simulation results show that the rotation speed and meshing force of each gear are consistent with the theoretical values,which indicates that the proposed model can accurately predict the dynamic characteristics of the reducer,thus provides a model basis for the analysis of the dynamic characteristics and the parameter optimization design of the nutation reducer.关键词：Nutation reducer;Double circular arc gear;Multibody dynamics;Meshing characteristic
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发布时间：2022-10-20 - 摘要：Based on the meshing theory of the roller enveloping end face engagement worm drive and the contact finite element analysis method,the finite element analysis software of ANSYS is used to establish the finite element analysis model of the roller enveloping end meshing worm drive,and the contact finite element analysis is carried out. The results show that the roller enveloping worm gears are in line contact and the number of meshing teeth of single-segment worm gear reaches 5 pairs at the same time. The studies are practicably instructive for developing new worm riving with high loading capacity.关键词：Roller envelope;Finite element;Contact analysis
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发布时间：2022-10-20 - 摘要：The helical gear is an important form of transmission in subway vehicles,helical gear failure has a great impact on the subway operation. In order to investigate the influence of fault parameters on the nonlinear dynamics of metro gear system,the stiffness failure and tooth surface fault parameters of 6-DOF subway bending-torsion-shaft coupling mode are established,by using the variable step fourth-order Runge-Kutta numerical integration method the gear dynamics model with fault parameters is analyzed to get the dynamic response process of the system. With the system status judgment criteria of speed-time process graph,phase plane graph,Poincare cross-section graph and bifurcation diagram,the system excitation frequency,the evolution of system periodic motion,quasi-periodic motion and chaotic motion with fault parameters changing are qualitatively analyzed. The results show that the failure parameters have different effects at different speeds.关键词：Subway helical gear;Fault parameter;Runge-Kutta;Dynamics response
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发布时间：2022-10-20 - 摘要：The torque of magnetic couplers can be transferred by utilizing the magnetic field coupling,which changes the rigid connection into non-contact soft connection. It has the advantages of soft starting,vibration reduction,locked-rotor protection,high reliability,and is applied in industry. The magnetic couplers can also be used in specific conditions,such as superconducting flywheel energy storage system（ SFESS）,which can realize the motor placed out of vacuum chamber with no need for stator cooling system,the completely dynamic sealing of vacuum chamber,and long time energy storage. Due to rare application and research in the condition of high speed for magnetic couplers,the transfer characteristics at high speed of asynchronous axial magnetic coupler is studied based on the application of SFESS. The finite element model is built by using the general simulation method based on slip speed,the performance parameters of transferred torque,axial force,and magnetic flux density in the air-gap are calculated,and the temperature rise characteristic of critical components is analyzed. The prototype is manufactured,and the test platform of transfer characteristics at high speed is established. The experiments are conducted at the synchronous speed 9 500 r/min and the conventional modeling method is validated by comparing the experimental results with simulated results. Also the torque transfer characteristic at various speeds is compared. The feasibility of asynchronous axial magnetic coupler for high speed application is validated.关键词：Asynchronous axial magnetic coupler;Finite element;Transfer characteristic;Temperature rise characteristic
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发布时间：2022-10-20 - 摘要：Forming grinding process is one of the methods for finishing the cycloidal gear. When the grinding process parameters are not suitable,the instantaneous heat generated in the grinding zone will cause the tooth surface burn. In order to optimize the grinding process parameters and prevent tooth surface burn,it is necessary to simulate the temperature field distribution of tooth surface. Using theoretical analysis to calculate the grinding energy and heat distribution ratio in the process of grinding,using finite element method and the computer simulation software of cycloid gear form grinding temperature field distribution in the process of simulation,the tooth surface temperature with the change of grinding time and temperature field distribution in gear tooth surface are got. Through the simulation analysis,it is found that the velocity vw of the grinding wheel and the radial feed grinding depth ap have a great influence on the distribution of the temperature field of the tooth surface,during the entire grinding process,the maximum temperature of the transient temperature field of the tooth surface appears near the tip of the tooth surface of the cycloid gear. And the maximum error of the simulation results and theoretical analysis is within 10%,which is of great value for the prediction of the distribution of the temperature field of the tooth surface and the reasonable selection of the grinding process parameters.关键词：Cycloid gear;Formed grinding tooth;Grinding process parameter;Temperature field;Finite element simulation;Grinding tooth burn
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发布时间：2022-10-20 - 摘要：In order to research the influence of stochastic meshing parameters on vibration of shearer cutting unit gear transmission system,taking the MG500/1180-WD shearer as the research object,considering about the effects of the factors such as meshing stiffness,meshing damping,combined error and gear backlash,the pure torsion nonlinear dynamics model of gear transmission system for shearer cutting unit is established,takes the meshing stiffness,meshing damping,combined error and gear backlash as the random variable,and also using the variable step size Runge-Kutta methods,the system model is solved,the statistical characteristic for the transient response of the system is obtained through statistic analysis. The research indicates that the mean value and mean-square deviation of the vibration displacement for solar wheel and planet gear increases with the degree of dispersion of the random clearance,meshing error and meshing stiffness,and random clearance has the maximum influence on the vibration displacement of planetary,random meshing stiffness comes second,the least influence is random meshing error. The research results provide the theoretical basis for structural optimization of shearer cutting unit transmission system and improvement of working stability.关键词：Stochastic meshing parameter;Gear transmission system;Shearer cutting unit;Vibration characteristic
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发布时间：2022-10-20 - 摘要：The temperature distribution of rubber parts of high elastic coupling will affect lifetime of product and reliability of the shaft system. The heat transfer theory and finite element method of uncoupling analysis is adopted to analyze the change process of temperature field of rubber parts and temperature change curve under dynamic torsion load. A dynamic thermal mechanical analysis is conducted,according to the relationship between damping factor and temperature,the loss analysis iteration is carried out. The temperature distribution test of rubber parts is performed on the torsion vibration test bench,the error of two calculation methods and measured values are compared and the validity of the numerical simulation method is verified. It is shown that the calculation accuracy of method which considering the temperature dependence of the damping factor is higher than method which assuming the loss factor is constant. On this basis,the allowable vibration torque of coupling is obtained,the theoretical basis for the performance monitor and design optimization is provided.关键词：High elastic coupling;Transient temperature field;Temperature field test;Loss factor;Allowable vibration torque
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发布时间：2022-10-20 - 摘要：The dynamic modeling for gear transmission system is studied for solution of the problems relating to the reliability of dynamic response characteristics analysis in gearboxes. A one-dimensional finite element model of gear transmission system is created by using lumped parameter method. The stiffness and mass matrices of total degrees of freedom are established for axes based on the theory of Timoshenko Beam and material mechanics theory. And the damping matrix is determined by a given modal damping coefficient. An additional stiffness matrix is established in consideration of the effect of gear coupling and bearing stiffness. The dynamic response of bearing is calculated by using dynamic flexibility method in combination of the dynamic meshing force obtained from the calculation of transmission error of a meshed gear pair and the dynamic meshing stiffness,which is used as the exiting force to be derived in dynamic equations. The result of bearing dynamic response is analyzed based on this mentioned modeling method for a certain type of gearbox. Comparison is made with the result from bench test and both are in good consistence. It proves the reliability of this modeling theory and provides the basis for the optimization of gearboxes in initial design.关键词：Lumped parameter method;Additional stiffness matrix;Dynamic flexibility method;Bench test
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发布时间：2022-10-20 - 摘要：In order to study the dynamic characteristic of the escalator drive chain system and the effect of the sprocket wear and chain wear on the characteristic of chain drive,based on the theory of chain drive kinematics and multi-body dynamics,a simulation model of the escalator drive chain system is built by RecurDyn.Two conditions of no-load and load are set up,and the simulation analysis is made under the condition of adding wear fault. The changing characteristic of the chain drive under the normal condition and the wear condition is obtained. The results of analysis show that the dynamic load increases significantly after wear. Some reference for the study of the wear mechanism of escalator drive chain system and fault diagnosis can be provided by this method.关键词：Chain drive;Multi-body dynamics;Recurdyn;Wear fault;Simulation analysis
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发布时间：2022-10-20 - 摘要：The crack propagation analysis of the gearbox gear of a urban rail vehicle is carried out by combining the dynamics simulation and the extended finite element method（ XFEM）. Based on the dynamics analysis,the location of the initial crack and load loading in the finite element model are determined. An extended finite element model is established and the calculation results are analyzed. The law of tooth root crack growth is summarized. The results show,the location of the maximum bending stress at the root doesn’t change with the gear meshing process,and the crack initiation location should be near this location. At the crack tip stress,the low rate steadily increases until the crack length reaches 0. 61. After 0. 61,the crack enters the instantaneous region and the crack tip stress changes obviously. Based on the finite element analysis and finite element analysis,it is found that the initial crack belongs to type I crack and belongs to I and II mixed crack in the middle and later stages of crack propagation. The results of different loading positions show that the initial crack deflection angle decreases with the downward loading of the loading position,and the crack propagates laterally along the thickness direction.关键词：Gear;Dynamics;Crack propagation;XFEM
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发布时间：2022-10-20 - 摘要：On the consideration of the development trend of industrial robots and domestic market situation& research status of RV reducer,the difficult problems need to be solved in the domestic batch manufacturing of RV reducer are put forward,such as national standards for design,manufacture and inspection,machining equipment for special part,wear and lubrication and intelligent inspection and assembly. The relevant solutions are discussed and the strategic thinking and suggestion are provided for RV reducer technology and industry of robot field in China.关键词：RV reducer;Batch production;Localization;Key problem
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发布时间：2022-10-20 - 摘要：To recover ancient Chinese south-pointing chariot,the principle of planetary gear trains and differential gear trains is studied. The structure of Lanchester south-pointing chariot is made of gear trains and body frame manufactured by 3 D printer. By analyzing the error of chariot,it has the disadvantages such as low accuracy. In order to reduce the error and improve the gear structure,motor and microcomputer control are applied to realize high-precision orientation on the plane. By further scenario analysis of chariot movement,its movement condition on 3 D surface can be known. To align error on the plane,a three dimensional checking calculation method is put forward. By monitoring the axle’s movement angle,south-pointing on the plane can be realized. The checked south-pointing chariot is suitable for most conditions,and has great market prospects in machinery manufacturing,national defense and other fields.关键词：South-pointing chariot;Planetary gear train;Differential gear train;Electric machine control;Correction algorithm
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发布时间：2022-10-20 - 摘要：In order to analyze the low temperature friction characteristics of angular contact ball bearings.Firstly,the change of low temperature structure of bearing is analyzed by finite element software,the changes of the low temperature structure,the change of the clearance and the change of the contact angle of the bearing are simulated and analyzed. The decrease of temperature will make the clearance of bearing larger and the contact angle larger. The change of temperature on the viscosity of grease is analyzed. Then the friction torque calculation model of the existing bearing is cited,and the friction torque of the bearing is calculated with the change of speed,preload,the radius of curvature and the temperature of the inner ring. Analysis of the trend of bearing friction torque under low temperature,dynamic pressure bearing friction torque for the friction torque of the80% fluid bearing at low temperature,low temperature and friction properties of lubricating grease viscosity coefficient of bearing the greatest impact,under the condition of low temperature bearing due to friction torque caused by the decrease of elastic hysteresis. Finally,the friction torque of bearing is tested by experimental method,and the result is compared with the simulation result. The error is less than 12%,which proves the accuracy of the calculation and provides a theoretical basis for the use of bearings at low temperature.关键词：Angular contact bearing;Friction characteristic;Low temperature deformation;Low temperature test of bearing
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发布时间：2022-10-20
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