最新刊期
期 12 ， 2019
- 摘要：Taking an involute cylindrical speed-increasing gear pair as the research object, the tooth surface contact pressure and the relative sliding velocity are deduced to establish the non-uniform wear model of the spur gear pair based on the Hertz contact theory and the Archard’s wear formula. And the tooth surface wear depth under different cycles is calculated. Then, based on the potential energy method, the non-uniform wear time-varying mesh stiffness formula of spur gear under different positions of base circle and root circle is developed. The effect of non-uniform wear on the time-varying mesh stiffness is studied. The results show that the wear depth is unevenly distributed on the involute profile, the wear around the pitch circle is the smallest, the wear depth at the tooth root and addendum is larger, and the cumulative wear depth at the top of the tooth is the largest. As the number of cycles increases, the time-varying meshing stiffness of the gear decreases with the increase of the wear depth. The stiffness reduction of the double-tooth meshing zone is greater than that of the single-tooth meshing zone.关键词：Involute gear
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发布时间：2022-10-25 - 摘要：In order to improve the fuel economy of coaxial parallel hybrid electric vehicle, the driver intention is used as the input variable of the fuzzy design to realize the fuzzy recognition of the driver intention, with considering the structural characteristics, working process and energy flow mode of coaxial parallel hybrid system. Fuzzy control torque distribution strategy based on recognition of driving intention is established in Matlab/Simulink, and joint simulation is performed with Cruise under NEDC cycle condition. The results show that, under the premise of satisfying the dynamic performance, compared with the logic threshold based on torque distribution control strategy, the proposed control strategy can effectively improve the working point of the engine, and can reduce the comprehensive fuel consumption of 100 kilometers about 3.2%, which satisfies the vehicle dynamics, and further improves the fuel economy.关键词：Coaxial parallel hybrid
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发布时间：2022-10-25 - 摘要：In order to improve the smoothness of the transmission process of spiral bevel gears, the influence of speed and load on meshing impact in the transmission process is clarified. Firstly, the mathematic model of meshing impact of spiral bevel gear is established, and the force analysis of driven wheel is carried out. Then, the multi-body dynamics model of spiral bevel gear transmission system is established by using Adams software, and the variation law of meshing force and angular acceleration of driven wheel in the transmission process under different rotational speeds and loads is analyzed. If the load is fixed, the increase of the speed will aggravate the meshing impact between the teeth, if the speed is constant, the intensity of meshing impact between the teeth can be reduced and the stability of transmission can be improved by properly increasing the load. It has certain theoretical significance for vibration reduction and noise reduction of spiral bevel gear transmission system.关键词：Spiral bevel gear
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发布时间：2022-10-25 - 摘要：A new method for determining the workspace boundary of planar parallel mechanism by using improved particle swarm optimization (MPSO) algorithm is proposed. A general objective function is formulated to give the best value that the planar parallel mechanism reaches its limit point. The workspace boundary of the parallel manipulator can be constructed by finding these points by using MPSO, the MPSO method is used to obtain the mapping of workspace boundary of 3RRR planar parallel mechanism in order to verify the effectiveness of this method. At the same time, the influence of initial position on workspace search is studied. The results show that the selection of initial point is the key to solving workspace boundary. Compared with discretization method, MPSO search process is more efficient and the obtained workspace boundary points are accurate.关键词：Particle swarm algorithm
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发布时间：2022-10-25 - 摘要：The application of numerical control forming method machining in circular arc profile bevel gear is discussed, it is proved that the circular arc profile spiral bevel gear based on this method conforms to the basic law of tooth profile meshing, and the principle of determining the guiding line (the line of the tooth profile along the conical surface of the joint) is given. This work provides technical support for efficient machining of circular arc profile spiral bevel gear.关键词：Circular arc tooth profile
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发布时间：2022-10-25 - 摘要：In order to reduce the energy consumption of pure electric vehicles in actual driving, the gear shift law of the two-speed mechanical automatic transmission is optimized. According to the actual needs of urban, suburban and comprehensive driving cycle in Taiyuan city, the driving motors of the vehicles are matched, and the traditional economic shifting rules are formulated based on the motor efficiency. Then, the optimal gear shifting points under different driving cycle in Taiyuan city are solved by dynamic programming, and the optimal two-parameter shift schedule is discovered. Through Matlab/Simulink modeling and simulation, the energy consumption of the two shifting laws under different Driving cycle is compared. The results show that compared with the traditional economic shift law, the optimized two-parameter shift law can better reduce vehicle energy consumption and improve the endurance mileage.关键词：Pure electric vehicle
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发布时间：2022-10-25 - 摘要：Through the patent database of 5074 patent data, the patent map of technical progress of RV reducer in recent 74 years at home and abroad is studied. The patent map of the technical field of RV reducer is drawn by using international patent classification (IPC classification), patent map method and patent information data mining technology. From the global application number, application trend, the main application countries, the main competition institutions, patent distribution pattern, the main technology hot spot changes, key technology development areas and other aspects of a detailed analysis. The current situation of the research in the field of RV reducer is analyzed, and the development trend of the future technology is predicted, and the reference for the localization strategy layout of RV reducer is provided.关键词：RV reducer
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发布时间：2022-10-25
Theory·Reserach
- 摘要：The traditional method of calculating time-varying meshing stiffness of spiral bevel gears mostly adopted finite element static analysis method, but it needed to be calculated many times, also the single tooth meshing stiffness calculated by the mean value of the node elastic deformation has a large error. For this reason, a calculation method for time-varying meshing stiffness of spiral bevel gear is improved. The meshing stiffness of single node was introduced into the traditional calculation method, and the meshing stiffness of each node on the working tooth surface is superimposed to obtain single tooth meshing stiffness, the calculation accuracy is higher. The time-varying meshing stiffness and transmission error of spiral bevel gears are calculated based on explicit dynamic finite element analysis. The calculation time period is reduced by calculating once without repeating multiple finite element analysis. The variation law of time-varying meshing stiffness and transmission error under different load torques is researched. Also the influence of two contact parameters such as contact ellipse axis length and contact path direction on time-varying meshing stiffness and transmission error are analyzed. The research results show that the time-varying meshing stiffness and transmission error increase with the increase of load torque, but the peak-to-peak value of time-varying meshing stiffness and transmission error decrease with the increase of load torque. The time-varying meshing stiffness and the peak-to-peak value of transmission error (PPTE) are improved with the increase of contact ellipse long axis length. As the contact path increase, the time-varying meshing stiffness has a sudden increase, and the transmission error changes little.关键词：Spiral bevel gear
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发布时间：2022-10-25 - 摘要：A new tooth profile curve equation of the cycloid gear is proposed based on the gear meshing transmission principle. Due to the problem that complex cycloid equation is difficult to be substituted directly with the software for modeling, the method of designing the cycloid gear tooth profile curve is obtained by using data fitting. Therefore, the solution to repair the cycloid gear is suggested. The method is simple in principle and has significant and practical value for the design and manufacturing of the cycloid speed reducer.关键词：Cycloid gear
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发布时间：2022-10-25 - 摘要：Construction method of the universal surface equation of the globoidal indexing cam mechanism with tapered roller is presented based on transformation of homogeneous coordinate after the theoretical analysis of conjugate surface theory and the differential geometry. Data collection system of the undeveloped ruled surface points is developed based on VB and the 3D modeling of the indexing mechanism is set up in Creo. Motion simulation and analysis of the mechanism is carried out in Adams. Simulation example is carried out by the proposed method. The result shows that the designed globoidal indexing cam mechanism with tapered roller satisfied the indexing expectation.关键词：Globoidal indexing cam mechanism
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发布时间：2022-10-25 - 摘要：Based on the concept of forward engineering design, a fast static-dynamic joint design method is proposed to study the mechanical properties and the range of design and operation parameters of the structure of high-speed multi-feature gear shafts. The safety factor of dangerous interface is used to check the strength of shaft, and the ratio of three safety factor, i.e. contact strength of tooth surface, bending strength of tooth root and dangerous interface, is weighed to calculate the operating parameter interval under static condition. The natural frequency and displacement modes of multi-feature gear shafts, and the Cambell damping diagram, and the relationship between the accuracy of dynamic balance and the response of rotational speed and vibration amplitude are output by dynamics analysis. Finally, the reliable parameter intervals of multi-feature gear shafts can be obtained by the fusion of static and dynamic parameters intervals, which can provide auxiliary design support for the development of new multi-feature shafts in engineering applications.关键词：Multi-feature gear shaft
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发布时间：2022-10-25 - 摘要：A four-bar linkage mechanism is designed based on the leg structure of the kangaroo. The four links are deformed by cam to stretch the spring to store the elastic potential energy. The sudden change of the cam stroke causes the tension spring to release the energy to jump. The experimental prototype is designed based on the mechanism principle. The simulation experiment is carried out by analysis software Adams, and the experimental prototype is verified experimentally. The experimental jump height is up to twice the length, elastic potential energy utilization rate of 70%. The correctness and rationality of the design and theoretical analysis of the four-bar linkage mechanism are verified by the result, then the main influencing factors that affect the jumping ability are analyzed, the conclusion is obtained and the improvement scheme is given.关键词：Jumping robot
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发布时间：2022-10-25 - 摘要：A heterogeneous double driving universal joint (HDD-UJ) is proposed, which can realize the pitching motion and the rolling motion. The HDD-UJ uses a universal joint as the prototype of the mechanism, with the motor as the main drive source and the electrostrictive material as the auxiliary drive source. Through the design of the HDD-UJ virtual prototype model, the integrated characteristics of the transmission integration are determined, and the transmission integration mechanism of the joint is described. The spatial motion coordinate system of the HDD-UJ is established, and its kinematics analysis is carried out and the kinematics equation is derived. Based on the mathematical principle of space geometry, the spatial motion range of the HDD-UJ is obtained, and the virtual simulation experiment of motion workspace is carried out. The simulation results show that the HDD-UJ structure is novel and simple, with high integration, and has two degrees of freedom. It can realize a wide range of space operations, and theoretical basis for the study of structural optimization and motion precision control strategies of subsequent joints is provided.关键词：Universal joint
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发布时间：2022-10-25 - 摘要：In order to balance the linear output of the exoskeleton power and the safety in the wearing process, a wearable flexible knee joint exoskeleton with two working modes of power assist and buffering is designed. Firstly, the parameter calculation and structural design of the knee bumper and whole machine model of the exoskeleton are carried out. Then, the dynamics analysis of the joint is carried out and the theoretical moment of the joint is calculated by Matlab. Finally, the calculated parameters and theoretical moments are substituted into Adams to simulate the exoskeleton under the two working modes. By comparing the simulation results with the human motion standard data, it is proved that the exoskeleton assist mode can basically meet the wearer's normal walking needs, and the buffer mode can buffer the rigid impact under sudden conditions. An important theoretical basis for the subsequent system control and prototype manufacturing is provided.关键词：Flexible knee joint
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发布时间：2022-10-25 - 摘要：Flexible mechanism can store and release energy by elastic deformation. Constant force can be achieved when the stored energy and released energy are approximately equal. Considering the common advantages of flexible metamorphic principle and constant force mechanism, a flexible metamorphic constant force manipulator is designed. Firstly, the structure design of the device is introduced, and the model is built according to the size relationship. Secondly, the motion of the device is analyzed according to the geometric relationship. Finally, the theoretical output force is calculated according to the principle of virtual work, and the constant force range is found by particle swarm optimization. The device does not need to install force sensors, and does not need a control system to achieve constant force clamping of the manipulator and has self-adaptability. It is suitable for clamping thin-walled and fragile articles such as cells, chips, glass and so on. It has good application prospects in biomedicine, production, life and scientific applications.关键词：Manipulator
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发布时间：2022-10-25 - 摘要：RV reducer has the characteristics of large transmission ratio, large carrying capacity, high transmission accuracy and stable transmission, so it is of great significance to research its dynamic characteristics. A RV reducer is taken as the research object, and the parametric three-dimensional model is established in SolidWorks. The rigid-flexible coupling dynamics model of RV reducer is established by Abaqus and Adams. Through simulation analysis, the dynamic response curve and transmission error of key components are obtained. Through spectrum analysis, the main factor affecting the transmission accuracy is the pure torsional elastic deformation of the crankshaft. The research method has certain guiding significance for precise design of RV reducer.关键词：RV Reducer
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发布时间：2022-10-25 - 摘要：Taking a 2T3R 5-DOF 4-SPRR-SPR parallel mechanism with rotating axis as the moving platform as the research object, the degree of freedom of the 4-SPRR-SPR parallel mechanism is analyzed by the screw theory, the inverse kinematics equation of the parallel mechanism is established by the vector method, the constraint of the pair of motion is analyzed in detail, and the workspace of the mechanism is obtained by the three-dimensional boundary search method. The results show that the workspace of the mechanism has the advantages of symmetry, no holes in the interior, regular cross-section shape, etc. At the same time, taking the workspace volume as the optimization objective, the influence curves of the constraints of the motion pair and the workspace volume are obtained, and the maximum factors affecting the workspace are obtained, it is the movement range of branch chain moving pair. The mechanism has good application prospects in cutting and grinding parts of complex space surface.关键词：Parallel mechanism
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发布时间：2022-10-25
Design· Calculation
- 摘要：Aiming at the two-phase flow characteristics of the automotive gear, based on the PLIC-VOF algorithm, the three-dimensional churning process model of the gear is numerically calculated by Matlab software. The influence of different rotational speed and immersion depth as well as viscosity on churning power loss of the gear is discussed. Then the three-dimensional churning model of the gear is simulated by Fluent. The power loss experimental and the visual experiment are conducted. The results show that the PLIC-VOF algorithm is suitable for calculating churning loss of the gear. The turbulence of oil distribution increased with the rotational speed. The churning power loss increased with rotational speed and immersion depth as well as viscosity, among which the rotational speed has the greatest influence.关键词：Gear
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发布时间：2022-10-25 - 摘要：A fault feature extraction method for rolling bearings based on sparse assisted smoothing (SAS) noise reduction and spectral kurtosis (SK) is proposed. Firstly, the simulation signal is de-noised by sparse assisted smoothing (SAS), and the performance of SAS de-noising and low-pass filtering is evaluated by RMSE index. Then, SAS de-noising and spectral kurtosis method are applied to fault diagnosis of rolling bearings, and clear characteristic frequency is extracted. Then the kurtosis index is used to compare the proposed method with the wavelet de-noising and EMD methods. The advantages of the proposed method in feature extraction are verified. The effectiveness of the proposed method is verified by simulation and data experiments.关键词：Sparse assisted smoothing
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发布时间：2022-10-25 - 摘要：Aiming at the problems of insufficient comprehensiveness and low accuracy in evaluating the operation status of wind power gearbox, an evaluation method based on grey cloud model clustering analysis and cloud gravity center deviation theory is proposed. A relatively complete evaluation system for wind power gearbox can effectively improve the accuracy of the evaluation results is established. A preliminary clustering analysis of the gearbox is carried out by using the grey cloud model, and the general evaluation results of the current operation of the wind power gearbox are obtained. On this basis, the cloud gravity center offset of standard cloud model and current cloud model is calculated, which further improves the reliability of the evaluation results. Through the state evaluation of the real wind power gearbox measurement data and comparing with the gear box record state, it is proved that the proposed evaluation method has certain accuracy and usability value.关键词：Wind power gearbox
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发布时间：2022-10-25 - 摘要：The efficiency of kinematic pairs is often formulated with work or force as it is done for the calculation of mesh efficiency of involute gear pair. Taking the distance between pitch point and contact point as a variable, two expressions of instantaneous efficiency of gear pair are derived from the perspective of work and force. Averaging the instantaneous efficiency along contact line leads to mesh efficiency of gear pair. Numerical examples are used to assess the validity of the presented calculation methods and the influences of the transmission ratio, pinion teeth number and friction coefficient on mesh efficiency are analyzed. Comparison of numerical results shows the calculation method based on the force is more appropriate than the method based on the work.关键词：Involute gear pair
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发布时间：2022-10-25 - 摘要：In the transmission process of coaxial magnetic gear, aiming at the problems of large torque ripple and high magnetic density in air-gap, a magnetic gear with thin metal sheet is studied. The structure fixates a layer of conductive and non-magnetic metal material respectively on the internal and external permanent magnets of the rotor in the magnetic gear. A magnetic gear model with 4 opposite poles for inner rotor and 21 opposite poles for outer rotor is established via finite element method. The internal and external air-gap magnetic field and torque of the magnetic gear are calculated. Meanwhile, high magnetic density and torque ripple are analyzed. The results demonstrate that the magnetic gear with metal sheet can not only reduce the high-order harmonic components of magnetic density but also reduce the torque ripple. A reference for the improvement of the stability in the magnetic gear transmission is provided.关键词：Magnetic gear
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发布时间：2022-10-25 - 摘要：Parallel robot manipulator with the function of space three translations and one rotation (3T1R) is widely used in industry because of its advantages of large working space, easy to realize high speed and low cost. The stiffness performance of a new 3T1R asymmetrical parallel mechanism is analyzed. Firstly, the topological structure of the mechanism is described. Secondly, based on the virtual spring method, the stiffness model of each branch is established and its stiffness matrix is solved. Then, the changing trend of torsional stiffness and linear stiffness of the Descartes stiffness matrix is analyzed, and the influence of redundant branches on the overall stiffness performance is discussed. Finally, the numerical value of the method is verified by the finite element analysis of ANSYS. The work lays a foundation for the structural design and prototype development of the parallel manipulator.关键词：Parallel mechanism
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发布时间：2022-10-25 - 摘要：A profile optimization model of the fork head of universal coupling is established. Based on divide and conquer, an optimization strategy for the profile of fork head is proposed. The influence law of the six design variables on the maximum stress of the fork head is summarized. Research shows that the structural parameters of arc groove and shoulder have a significant effect on the maximum stress of fork head, which should be paid attention to in design. According to the case analysis of fork profile optimization, on the premise of keeping the rotary diameter unchanged, the maximum stress of the fork head can be reduced and the torsion transfer ability can be increased. A heavy-duty universal coupling with the largest torsion transfer capacity in China is manufactured, and the performance test is carried out, which provides a reference for the design and optimization of fork head’s profile of heavy-duty universal coupling.关键词：Universal coupling
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发布时间：2022-10-25
Test·Analysis
- 摘要：Aiming at the pre-stretching and disassembling link in the manufacturing process of double-row chain, a new type of pre-stretching and disassembling device for double-row chain is designed. The device consists of two modules of pre-stretching and disassembling. The pre-stretching module uses hydraulic cylinder to load to move the associated sprockets and then pre-stretching sprocket between groups. The disassembling module uses pneumatic sliding table to drive chain insert plate to stabilize the chain, the pneumatic-hydraulic booster cylinder to drive punching nails to remove pin shafts, and the cylinder to drive chain pusher plate to push chain plate. The structure of the pre-stretching and disassembling has high degree of conversion, good interchangeability of vulnerable parts, can effectively realize the function of dynamic pre-stretching and disassembly of double-row chain.关键词：Double-row chain
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发布时间：2022-10-25 - 摘要：Based on the finite element software Deform-3D, the electromagnetic-thermal coupling numerical model of induction heating of spiral bevel gear small wheel is established. The orthogonal experimental method is used to optimize the parameters of temperature, friction coefficient, die feed speed and wheel blank speed, which affect the ear protrusion defect of small wheel. The optimum process parameters are selected as follows: blooming temperature 950 ℃, friction coefficient 0.1, feed speed 0.2 mm/s and billet speed 30 r/min. When the feed of 3 mm in the rolling process is optimized, the ratio of the ear protrusion height is 20.33%, numerical simulation is conducted to verify the optimal parameter combination, and the results are good. A reference for further rolling experiment of bevel gear wheel is provided.关键词：Spiral bevel gear
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发布时间：2022-10-25 - 摘要：A spindle swing compound barrel finishing equipment for gear machining is proposed. The calculation model of cutting speed and cutting angle is established. The influence of various parameters on cutting speed and cutting angle is analyzed by using Matlab software. The rationality of the design of spindle swing compound barrel finishing equipment is theoretically verified. An experimental device with adjustable parameters is developed. Machining experiments shows that the surface roughness Ra decreased from about 0.8 μm to about 0.3 μm. The cutting trace is removed and the surface texture is the same. The result shows that the equipment can effectively improve the surface quality of gears and obtain the uniform surface of gears.关键词：Gear
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发布时间：2022-10-25
Development·Application
- 摘要：With the continuous development of engineering technology, bending fatiguestrength has become an important limiting factor for the further development of gears, and bending fatigue failure is more dangerous than tooth surface failure. Based on the mechanism of gear bending fatigue fracture and the process of crack propagation, the influence factors of tooth root crack initiation, including tooth root transition fillet, grinding step and residual stress field, on tooth root bending fatigue properties are described. Based on the residual stress and the controllable tooth surface strengthening mechanism of surface and subsurface structure, the surface strengthening technology to improve the bending fatigue performance of gear is further analyzed, including shot peening strengthening, tooth root grinding technology and their research progress. The influence of root grinding on the bending fatigue performance of gears is discussed. It provides theoretical basis and technical reference for optimizing gear design and manufacturing and improving gear bending fatigue performance in engineering practice.关键词：Residual stress
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发布时间：2022-10-25
Review
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