最新刊期
期 5 ， 2020
- 摘要：Abstract In view of the important influence of tooth surface contact temperature on gear meshing process， the calculation formulas of tooth surface contact temperature of spur gear under four different lubrication conditions are established based on Blok flash temperature theory. The distribution of tooth surface contact temperature along the meshing line and the effects of rotational speed， torque， lubricant viscosity and backlash on tooth surface contact temperature are analyzed. The tooth contact temperature under different working conditions is measured. The numerical results and experimental results show that the contact temperature of the tooth surface reaches the highest at the meshing position and addendum and it is close to the room temperature near the pitch circle. It is found that the contact temperature of tooth surface increases with the increase of lubricant viscosity under EHL condition， but it is opposite under mixed lubrication condition. The lubricant viscosity has no obvious effect on the contact temperature of tooth surface under boundary lubrication condition， and the contact temperature of tooth surface increases with the increase of rotational speed， torque and backlash. The research results can provide a basis for the calculation and experimental measurement of the contact temperature of tooth surface.关键词：Spur gear
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发布时间：2022-11-10 - 摘要：Abstract The application of the concentric torque-split face gear transmission on the main gearbox of helicopter is analyzed. Based on the definition of equivalent displacement and equivalent stiffness, the mechanism of the uneven load sharing of the concentric torque-split face gear transmission is revealed. The load sharing calculation model of the concentric torque-split face gear transmission is established by an analytic method. With the help of numerical method, the influences of the factors of the system on the load sharing behaviors are preliminarily explored. The results show that the load sharing performance of the system is less sensitive to the backlash when the support stiffness of the input pinion is low.关键词：Face gear
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发布时间：2022-11-10 - 摘要：In addition to affecting the residual stress field on the gear surface, shot peening also changes the surface roughness of the gear. The surface roughness at the tooth root and the pitch circle will strongly affect its service performance. Therefore, it is necessary to study the evolution process of the gear surface roughness during the shot peening process. In this study, a random shot finite element model is established to simulate the shot peening process in the vicinity of the root and the pitch circle, and all discrete data in the impact region are extracted to calculate the surface roughness parameters. The results obtained by numerical simulation are basically consistent with the test results after gear shot peening. Subsequently, the effects of shot peening time, shot size and impact velocity on the surface roughness parameters near the root and the pitch circle are studied. The blasting process parameters can be reasonably selected to achieve the purpose of controlling the surface roughness of the gear after shot peening. The research shows that, under the same shot peening parameters, the surface roughness Ra and Rz values of the pitch circle are significantly smaller than the root. The surface roughness increases at the root with the increase of the impact velocity and the diameter of the shot, the Ra and Rz increase obviously and the impact of the shot diameter on the roughness parameter is greater than the impact velocity. With the increase of the impact velocity and the diameter of the shot, the surface roughness Ra and Rz of the indexing circle increase significantly, and the Rmr(-1) value decreases. And the effect of the diameter of the shot on the roughness parameter is greater than the impact velocity.关键词：Shot peening;Gear;Surface roughness;Numerical method
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发布时间：2022-11-10 -
- 摘要：Abstract The vehicle group chain conveyor is the new kind of continuous material conveying equipment in bulk materials field. For its essential structure， which is the continuous track group car carrying the conveyor belt and relying on the rail runs. Curve passing performance at curve working conditions is studied. A nonlinear dynamics model of the conveyor track group passing the curve is established and analyzed. The multi-body dynamics simulation software SIMPACK is used to build the track group car model. Based on the different working conditions and the structure of the car， the variation of the curve passing performance of the track car is analyzed. The simulation results show that dynamics performance index of the track car in vehicle group chain conveyor under various working conditions decreases with the increase of the vehicle speed and spacing， and increases with the increase of the curve radius and transition curve length. Track car with smaller wheelbase and articulated body can adapt to curved track. The curve of the track car has good performance and all indicators are within the safe limit range.关键词：Vehicle group chain conveyor
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发布时间：2022-11-10 - 摘要：Abstract Taking the four-point contact ball bearing as the research object，the research of the rotation accuracy of the four-point contact ball bearing is carried out， and the numerical calculation method of the bearing rotation accuracy considering the roundness error of the inner ring and the outer ring of the bearing is proposed. The radial runout of bearing is used to describe the rotation accuracy. According to the structural characteristics and motion relationship of the four-point contact ball bearing， the mathematical model of the bearing radial runout is constructed，and the program is programmed on Matlab for simulation calculation. The results show that when the harmonic order of the inner raceway is constant， the rotation accuracy of the bearing will decrease with the increase of the harmonic amplitude. When the harmonic order of roundness error of the inner ring is 3，that is，the profile of inner raceway is a triangular circle，the radial runout of the bearing is lowest and the rotation precision of bearing is the highest. The radial runout of the outer ring is the largest when the harmonic order of roundness error of the outer ring is the integral relationship of the number of steel balls. The value of the outer ring radial runout is the smallest when the harmonic order of roundness error of the outer ring is an odd multiple of half the number of steel balls.关键词：Four-point contact ball bearing
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发布时间：2022-11-10 - 摘要：Abstract A whole order vibration reduction method for electric powertrain is proposed. Firstly， motor control strategy is optimized and the output torque ripple is reduced by inhibiting main harmonic currents of motor d-q axial，based on harmonic optimization theory. Secondly，in consideration of active control effect，the best gear modification parameters are obtained，transmission error volatility is reduced by joint optimization with elitist retention genetic algorithm and gear engagement finite element model. Finally， order vibration control effect after tooth modification is verified by establishing electric vehicle power train mechanical simulation model. The results show that， comprehensive consideration of the motor harmonic current control and the microscopic modification of gear tooth， can effectively reduce the order vibration of electric vehicle power train.关键词：Electric vehicle
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发布时间：2022-11-10
Theory·Reserach
- 摘要：Abstract A system approach is proposed for the analysis and design of dual mode power split continuously variable transmission. The characteristic equations of speed ratio， torque ratio and power split ratio of power split continuously variable transmission based on mechanical point are established. By setting the limit on the speed ratio， torque ratio and power split ratio， the feasible region of mechanical points is obtained. The schematic diagrams of power split continuously variable transmission are given. The feasible region of the basic speed ratio is obtained from the feasible region of the mechanical point. By using 2K-H（NGW） type simple planetary gear set， the feasible structure schemes are obtained. By setting the mode shift conditions， the input split and the compound split are synchronously switched at mechanical point of the lower speed ratio and 3 structural diagrams are obtained. By setting two mechanical points to 0.66 and 1.33， the structural scheme of the dual mode power split continuously variable transmission is obtained. Through mode shift， the structural scheme can effectively reduce power， speed， torque of the continuously variable transmission branch. When the speed ratio range is
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发布时间：2022-11-10 - 摘要：Abstract A new 3-DOF parallel mechanism 3-UPS/RPP is designed， which can realize two shifts and one rotation. Based on the traditional 3-UPS structure， a constrained branched chain of RPP structure is added to the structure. The spiral theory is applied to analyze the constrained chain. It is found that the proposed 3-UPS/RPP parallel mechanism can realize one-dimensional rotation and two-dimensional movement in the plane. On the basis of degree of freedom analysis， the kinematics model of 3-UPS/RPP parallel mechanism is further constructed. Through the decomposition analysis of driving and constrained branching chains， the analytical expression of inverse solution of position of 3-UPS/RPP parallel mechanism is given. Based on the results of inverse solution of position， a workspace search process is constructed， and the workspace of the mechanism is solved in Matlab software. Finally， the kinematics control simulation of the 3-UPS/RPP parallel mechanism is carried out. The simulation results show that the system has high dynamic trajectory tracking control accuracy and is suitable for practical application.关键词：Parallel mechanism
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发布时间：2022-11-10 - 摘要：Abstract In order to improve the fuel economy of hybrid buses and solve the problem of power interruption during shifting, a new hybrid transmission with an auxiliary gearbox is proposed. The parameters of the key components such as the motor and the engine are re-matched to the original bus, and the specific shifting process of the hybrid transmission is introduced. In the Matlab/Simulink software, the electric vehicle simulation software ADVISOR is redeveloped, the parallel hybrid bus model is built, and compared with the original bus by simulation analysis. By susing the AMEsim software, the new hybrid system is modeled, simulation analysis of shift quality is carried out. The simulation results show that, the fuel consumption rate of the proposed new hybrid variable speed system is reduced by more than 18% under the working conditions of C-WTVC and UDDS. The power performance meets the design requirements, the gear shifting process is relatively smooth, impact is small. And the shift without power interruption is realized.关键词：Hybrid bus
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发布时间：2022-11-10 - 摘要：The residual stress state of grinding gear has great influence on its performance, the accurate prediction and calculation of residual stress of tooth surface after grinding is the important content of gear anti - fatigue manufacture. Based on the motion analysis of form grinding and the thermo-mechanical coupling finite element simulation calculation method, the calculation method of residual stress of the tooth surface after grinding is proposed. Subsequently, the forming grinding experiment is carried out, and the residual stress of the tooth surface after grinding is measured. The measured values of the residual stress and the finite element calculation value are compared, and the correlation law between the grinding parameters and the residual stress is analyzed. The research indicates that the calculation result of the proposed form grinding model is in good agreement with the experimental results. And in the form grinding, a larger feed depth results in a smaller residual tensile stress on the tooth surface after grinding.关键词：Form grinding;Gear;Residual stress;Thermo-mechanical coupling;Calculation method
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发布时间：2022-11-10 - 摘要：Abstract Aiming at the problems of high data repeatability, low utilization rate and low construction accuracy of the damaged part model in the remanufacturing process of helical gear parts, a modeling method for constructing a complete part model using local area point cloud data is proposed. Using the local area point cloud data, the complete intact gear part model with the characteristics of the helical gear itself is built. Meanwhile, the damage tooth region model is constructed separately, and the high-precision damage gear model is obtained by model splicing. The coordinate model of the intact gear model and the damage gear model are used for registration to obtain the damage amount model. Finally, through the practice case, the proposed method is verified.关键词：Helical gear
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发布时间：2022-11-10 - 摘要：Abstract Aiming to develop economical and practical milling machine， and reduce the production cost of spiral bevel gear， the processing method based on four axis milling machine is proposed. Firstly， the machine model of four axis milling machine is established， and the processing motion is analyzed. Secondly， the motion mathematical model of four axis milling machine and basic generating mathematical model are established. By means of motion equivalent from NC machine to mechanical machine， the motion axis coordinate of four axis milling machine is calculated. Finally， the machining process of four axis milling machine is simulated based on VERICUT， and the cutting experiment is executed. The results verify that the machine model and motion position solution is correct and effective.关键词：Spiral bevel gear
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发布时间：2022-11-10 - 摘要：Abstract RV reducer is the core transmission component of industrial robots. It is a new type of transmission device suitable for high-precision transmission developed on the basis of conventional cycloidal pinwheel and planetary gear transmission. Taking the RV reducer parts design as the research object, the transmission principle and system composition of RV reducer are introduced, the parametric equation of standard cycloidal gear is expounded, and the parametric modeling method of cycloidal pinwheel based on Autodesk Inventor software platform is mainly discussed. In view of the three-dimensional model of the virtual prototype of RV reducer, the physical model is made by the rapid prototyping technology of light curing. The dimension and surface accuracy of the parts are high, which provides a feasible help for the following demonstration of the overall structure and the research and development of important parts and components.关键词：RV reducer
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发布时间：2022-11-10 - 摘要：Abstract In order to obtain lightweight formula racing sprocket， the topological optimization method is introduced into the design of sprocket structure， the mathematical model of lightweight optimization design is constructed， and the geometric model of initial sprocket design is optimized by reducing the weight three times， and the sprocket with 49.59% mass reduction is obtained. Finally， the optimized model is processed and manufactured with the simulated check for strength， safety factor and life， and the prototype is fabricated and assembled into the racing car. The physical experiments are carried out on the racing car. The results show that the sprocket optimized meets the working requirements.关键词：Racing sprocket
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发布时间：2022-11-10
Design· Calculation
- 摘要：Abstract In the manufacturing process of cycloidal gear, the tooth profile errors will be emerged inevitably because of the influences of machine precision, cut tool precision, fixture precision and gear blank precision. In order to estimate the influence of tooth profile errors on transmission precision of cycloidal-pin gear, the coordinate datum of actual flank are calculated based on the measured tooth profile errors of cycloidal gear. The measured coordinate datum of actual flank are fitted by use of the non-uniform rational B-spline（NURBS）curve, and the digital tooth profile of cycloidal gear including the tooth profile errors is obtained. The digital tooth contact analysis of cycloidal gear is executed based on the gear meshing principle, and the transmission error curve of cycloidal-pin gear considering the tooth profile errors is obtained. The simulation results of an example indicate that the tooth profile errors can change the shape and amplitude value of transmission error curve.关键词：Cycloidal gear
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发布时间：2022-11-10 - 摘要：Cross-axis magnetic gears have a good application prospect in the industrial and aerospace fields. The advantage compared with mechanical gears is that the 90° space interleaving between the output and the input can be achieved by the one-stage transmission. In order to improve the feasibility of the cross-axis magnetic gear application， based on its structure and working principle， the finite element model of the cross-axis magnetic gear is established. The transient magnetic field is used for simulation analysis， then the influence of gear meshing clearance， number of magnetic pole， magnetic ring thickness， gear size， helix angle and width-to-diameter ratio on the maximum transmission torque of magnetic gear is obtained. Finally， the optimized structure of the cross-axis magnetic gear and its magnetic induction intensity cloud map are obtained. The results show that the reasonable structure and working characteristics of the cross-axis magnetic gear can be obtained by simulation， and the larger torque and better magnetic induction distribution can be obtained. The simulation results can provide a reference to structure design and the working characteristics analyze of the cross-axis magnetic gear， and greatly shorten its design and development cycle.关键词：Magnetic gear;Cross-axis;Transient magnetic field;Torque
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发布时间：2022-11-10 - 摘要：Abstract In the process of harmonic drive（HD），the double-circular-arc tooth profile（DCTP） can effectively avoid cusp meshing. In order to further optimize the double arc profile and improve the performance of the HD，based on the modified kinematic method exact conjugate theory，and using Matlab programming calculation，the influence and laws of the main parameters in the flexspline profile（FSP） on the conjugate zone and conjugate tooth profile are compared and analyzed. The results show that the convex tooth profile radius，concave tooth profile radius and radial deformation amount of FSP have significant influence on the shape of conjugate tooth profile. The obliquity and length of common tangent have significant influence on the conjugate zone and arc length of conjugate tooth profile. Reasonable selection of flexspline profile parameters can effectively improve the transmission performance of harmonic gear device.关键词：Harmonic drive
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发布时间：2022-11-10 - 摘要：Abstract The design of the base tangent length deviation is generally selected according to the design manual. The study of the relationship between the base tangent length deviation design and the meshing dynamics performance has not been reported in literature. Through deducing the formula for calculating the meshing stiffness and meshing clearance under the deviation of the common normal line， the dynamics model of a 12-DOF helical gear transmission system with nonlinear factors such as time-varying mesh stiffness and backlash is established. Four base tangent length deviation groups under 6-level precision are considered， and the peak-to-peak curve， amplitude-frequency response and root mean square curve of transmission error of the system are obtained by calculation， the design flow of optimal base tangent length deviation is given. The analysis result shows that， the influence on the system at low speed is stable， when the system is at high speed， it will jump and enter chaos. The base tangent length deviation has a significant influence on the impact characteristics of the gear pair system， and an appropriate increase in the base tangent length deviation can improve the impact of the system. The analysis found that the gear pair system is the best dynamic characteristic in the third base tangent length deviation group. A dynamics evaluation method for the design of base tangent length deviation is provided by the research result， it has reference value for high-performance gear design research.关键词：Base tangent length deviation
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发布时间：2022-11-10 - 摘要：Abstract The general methods of parameter calibration of parallel robot mechanism are analyzed， and a new parameter calibration method based on automatic cooperation principle for 3-R2U2S parallel robot is proposed. The principle is that all the influencing factors of positioning error are attributed to the change of robot mechanism parameters， and the comprehensive correction rod length influence factor including various error sources is obtained， then the more accurate kinematics inverse equation is finally obtained. In order to check the reliability of the method， the calibration experiment center of 3-R2U2S parallel robot prototype is built. In the workspace， 50 points are randomly selected for testing， and their coordinates are replaced into the modified inverse kinematic solution equation， and the theoretical input value of the driving angle of each branch chain is obtained. The test result shows that the deviation between the theoretical input value and the actual input value is controlled within the allowable range， which verifies the accuracy and reliability of using the automatic cooperation method to solve the modified rod length to establish the kinematic inverse solution equation of 3-R2U2S parallel robot.关键词：Parallel robot
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发布时间：2022-11-10 - 摘要：Abstract In order to effectively solve the motor dysfunction of lower limbs in the elderly caused by the degeneration of lower limb muscle function and stroke hemiplegia， the importance of rehabilitation exercise for the recovery of lower extremity dysfunction patients is analyzed from the perspective of rehabilitation medicine. Combining with the physiological structure of human body， a human musculoskeletal model is established and the musculoskeletal simulation analysis is carried out. In order to accurately judge the motion intention of patients， three kinds of special sensors for exoskeleton are designed. On this basis， a force sensing joint structure scheme is proposed， and the overall structure of the lower limb power exoskeleton is designed. The human-machine coupling kinematics simulation analysis is carried out. On the basis of structure design， the hardware and electrical system of lower limb exoskeleton are designed. In order to verify the correctness of theoretical research， the exoskeleton prototype is processed and related experiments are carried out. The experimental results show that the special exoskeleton sensor designed can accurately acquire the corresponding signals， and the assistant joints can provide greater joint assistance. The designed lower limb power exoskeleton can accurately judge the motion intention of patients， and can walk steadily and safely on the ground and on the slope for a long time.关键词：Musculoskeletal model
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发布时间：2022-11-10 - 摘要：A kind of mobile robot with deformation wheel is designed, the conversion between wheel structure and three spoke arc leg structure is realized by controlling the steering gear. On the basis of the working principle of the deformation wheel, the kinematic modeling and the analysis of the obstacle surmounting ability are carried out. The dynamic simulation of the obstacle surmounting ability of the deformation wheel mobile robot is carried out by using Adams software, the correctness of the kinematic analysis is verified, and the motion law curves of displacement, velocity and acceleration are obtained. The finite element simulation of the deformation wheel is carried out by using Abaqus software, and the stress-strain diagram is obtained and vibration mode diagram. The analysis shows that the strength, stiffness and vibration of the mobile robot meet the design requirements. The theoretical analysis has important reference value for the research of mobile robot with deformed wheels.关键词：Deformation wheeled;Kinematics analysis;Climbing obstacle capability;Simulation analysis
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发布时间：2022-11-10 - 摘要：Abstract For the phenomenon of broken teeth in the transmission， the causes are analyzed. The gear raw materials chemical composition， non-metallic inclusions， heat treatment hardness， carburized layer thickness， metallographic structure are checked. The metallographic structure of the abnormal wear site indicated that the friction burns have occurred. Combining with the characteristics of gearbox， the No.1 crack is considered to be the fatigue crack source of gear hub cracking. The gear hub cracking destroys the meshing relationship， reduce the bending fatigue strength， and cause teeth breakage. The analysis of assembly relationship of layshaft assembly， the axis clearance eliminated because of the synchronizer hub position shifting is the cause of tooth fracture. For gearbox shaft assembly included many components， correct assembly relationship between each other， and reliable fixation of assembly position have an important influence on the reliability of gear.关键词：Gearbox
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发布时间：2022-11-10
Test·Analysis
- 摘要：Abstract The variational mode decomposition （VMD） is widely used in fault diagnosis. Extracting fault characteristics from vibration signals is a critical part in the bearing fault diagnosis. It is difficult to extract early fault signatures under strong background noise and pulse interference. Thus， a new fault diagnosis method is proposed based on the variational mode decomposition and fruit fly optimization algorithm （FOA）. Firstly， the fruit fly optimization algorithm is used to optimize the penalty parameter α and the decomposition number K of the VMD adaptively to obtain the optimal parameter combination. Then， the VMD decomposition of the signal is performed to find K modal components. Finally， the optimal modal component is selected based on the kurtosis maximization criterion for envelope demodulation analysis and extracting the frequency of the fault feature. The effectiveness of the presented method is verified by simulation signal analysis， detecting bearing fault signal and comparing with multi-resolution singular value decomposition （MRSVD） approach based on fruit fly optimization algorithm.关键词：Variational mode decomposition
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发布时间：2022-11-10 - 摘要：Abstract Aiming at the pre-stretching and disassembling link in chain manufacturing process， a universal device for pre-stretching and disassembling chain is designed. On the premise of realizing continuous processing of pre-stretching and disassembling chain， the device sets up driving sprocket moving module， cylinder connecting parts with T-groove and punching nail installation module， chain limit plate with straight groove and chain block to improve the versatility and interchangeability of the device. The whole device has the function of replacing fewer parts to process many kinds of chains. The product quality is high and the service life is long.关键词：Universal
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发布时间：2022-11-10 - 摘要：Abstract The rectangular coordinate equation of the concave-convex gear is established， the convex tooth surface is simulated by Matlab， the three-dimensional model of the gear-rail system is established according to the tooth profile， and the stress state is analyzed. The contact and bending strength are analyzed in Ansys software， and the kinematics performance is analyzed by Adams software. The analysis results show that the gear-rail system has good mechanical properties and strong adaptability. Through analysis and selection of the processing equipment of the complex tooth surface walking wheel， the problem of production and processing is solved. The practical performance of the system is verified by means of 3D printing， tooling test and industrial test. The test results show that the system reduces the contact strength of the walking part and improves the service life of the system.关键词：Shearer
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发布时间：2022-11-10 - 摘要：Abstract Taking ZF 8HP 8-speed automatic transmission as the research object，it is composed of four single planetary gearsets and five shift elements. The transmission routes of the automatic transmission are analyzed. Based on basic theory of lever method， equivalent leverage diagrams of each gear are established. The formulas of transmission ratio of each gear are calculated. The research result provides a theoretical basis for the design of automatic transmission.关键词：Automatic Transmission （AT）
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发布时间：2022-11-10 - 摘要：Abstract In order to detect helical angle and other parameter quickly， the method of measuring standard helical gear is proposed based on machine vision. First of all， the overall structure and measurement process of the system are introduced. The digital image of upper gear face and lower gear face are morphologically processed to obtain the main characteristic parameters of the helical gear， and then， the helical angle is obtained. Experimental show that the method has high accuracy and efficiency， and can meet the needs of measurement requirement.关键词：Helical gear
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发布时间：2022-11-10
Development·Application
- 摘要：Abstract In the case of failure analysis of fracture of crankshaft with material 42CrMo, forged, tempered and nitriding treatment, it is found that there is an abnormal phenomenon of intersection of the scallop lines on the fracture surface. This is not possible in the general fracture surface. The crack dynamics and the theory of Wallner line are used to analyze the abnormal phenomenon, the crack at the source of fracture fatigue will produce stress wave in the material and propagate on the surface where the crack is located. When the crack encounters a discontinuous surface, a transverse stress wave is generated, thus forming a second set of concentric arcs centered at the wave source. This makes it possible for the shellfish lines to intersect. For the first time, it is observed that Wallner line cannot only appear on fracture surfaces of metallic and non-metallic brittle materials. It illustrates that Wallner line can also appear on the fracture surface of quenched and tempered steel.关键词：Fracture analysis
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发布时间：2022-11-10
Communication·Discussion
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