最新刊期
期 1 ， 2020
- 摘要：There is no analytical calculation method and formula for the calculation of the bending strength of the face gear.For this reason，based on the principle of tooth surface contact analysis，the formula for calculating the length of the bending arm is derived，reference the calculation standard （ISO 10300（3）：2014） of bevel gear bending strength，an analytical calculation method for the root bending strength of non-orthogonal helical face gear is proposed.Taking a parameter face gear transmission pair as an example，the Abaqus finite element software is used to calculate the root bending strength，and the root bending stress value of the non-orthogonal helical face gear is extracted.The finite element results are compared with the analytical calculation results，the error is about 8.5%.The results show that the calculation method of the calculation method of the root bending stress of non-orthogonal helical face gears is correct and feasible.The problem that the calculation of the bending strength of the face gear has no analytical formula is solved.After refinement and perfection，it is expected to form a basic calculation formula for the bending strength design of the face gear.关键词：Bending strength
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发布时间：2022-11-10 - 摘要：Taking the circular arc tooth trace cylindrical gear（CATT gear） processed by parallel link mechanism as an object of study， a 3D model of CATT gear with eccentric error is created by UG NX10.0， and then the dynamics model of CATT gear with eccentricity excitation is created by Adams further to study the meshing characteristics of CATT gear under eccentricity excitation. Three working conditions of driving system， namely， the existence eccentricity of driving wheel， the existence eccentricity of driven wheel and the common eccentricity of driven and driven wheel are simulated to obtain the meshing characteristics of CATT gear under eccentric excitation. The results show that， the transmission system meshing forces of the three working conditions all periodically changes. The maximum meshing force， the average meshing force and the root mean square of meshing force all increase with the increase of transmission system eccentricity， indicating that the greater the impact in the meshing process， the worse the stationarity. The research results provide the theoretical basis for the design and application of the CATT gear.关键词：Parallel link mechanism processed;Circular arc tooth trace cylindrical gear;Eccentricity excitation;3D modeling
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发布时间：2022-11-10 - 摘要：According to the topology design theory and method of parallel mechanism(PM) based on position and orientation characteristic(POC) equations， a novel semi-symmetrical PM with two translation and one rotation (2T1R) output motion is designed. And the three main topological characteristics of the PM， such as the POC， degrees-of-freedom (DOF) and coupling degree are calculated and analyzed， and the coupling degree of the mechanism is 1.Then， based on the kinematics modeling principle of the ordered single open chain (SOC) units， the positive kinematics solution and inverse kinematics solution formula are achieved. According to formula， the workspace and rotational ability of PM are got and analyzed. The singularity condition of mechanism is studied. The velocity and acceleration of the mechanism are simulated and analyzed. Finally， the principle of the mechanism applied to ankle massage is analyzed.关键词：2T1R
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发布时间：2022-11-10 - 摘要：Tapered roller bearing is an important key component of the mechanical transmission system that supports the rotating shaft system. Its performance parameters and working state will have an important impact on the transmission characteristics of the equipment. The temperature rise effect in the bearing operation is the key factor to the bearing performance. In order to deeply study the influence mechanism of the fitting accuracy of the tapered roller bearing on the temperature rise characteristics， a bearing intelligent test bench is developed. The temperature rise of the bearing under different fitting accuracy conditions is studied by experimental means. The coupling law of the ring inside and outside fitting accuracy fitting accuracy and temperature rise of the tapered roller bearing are analyzed， the temperature rise characteristic curve of the tapered roller bearing with different fitting accuracy is obtained， and the theoretical support for the precise selection of tapered roller bearing parameters in high-end equipment is provided.关键词：Tapered roller bearing
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发布时间：2022-11-10 - 摘要：At present， the main nonlinear factors that lead to the trajectory tracking error of multi-axis industrial robots are the joint nonlinearity on each axis and the dynamics coupling effect between different axes. For this， a motion control method for industrial robots is proposed， which considers the joint nonlinearity in a series of two-link manipulators. The kinematics and dynamics model of the manipulator is constructed， and a parametric modeling method is proposed. The nonlinear stiffness and friction force of the connecting rod are directly identified as joint nonlinearity. The method is applied to the series two-link manipulator of a typical multi-axis industrial robot with low-frequency vibration characteristics and important influence on trajectory performance. The motion state of the serial double-link manipulator reproduced， the validity of the method is verified by numerical simulation and experimental comparison. Two control schemes， feedback closed-loop control with variable notch filter and two-degree-of-freedom control with dynamic feed-forward compensation are adopted to improve the performance of trajectory tracking and residual vibration suppression. Combining four different motion forms， the experimental study is carried out and compared with the conventional PI trajectory tracking control method. The results show that the two-degree-of-freedom control scheme with identifiable two-link dynamics model and feedback loop with variable notch filter can improve the trajectory tracking and residual vibration suppression performance.关键词：Joint nonlinearity
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发布时间：2022-11-10 - 摘要：Abrscat For the cycloid gear of RV reducer used in robot， on the basis of the isometric modification method， the modification quantity is changed in linear and polynomial ways， and the cycloid tooth profile equations after profile modification are derived. Based on the change rule of pressure angle， by controlling the maximum pressure angle and the maximum profile modification of tooth root and top， the tooth profile modification at different positions in the modification interval of the tooth profile curve can be controlled. The biggest difference between profile modification method based on the pressure angle and the traditional method is that in the working section of cycloid gear， the tooth profile of cycloid gear is standard， and the non-working section and the working section are smoothly connected. The modification program of cycloid tooth profile is compiled in VB， and modification interval and meshing force are compared under different profile modification and pressure angle. Different pressure angles correspond to different working areas， and the meshing force distribution based on pressure angle sectional modification method is more uniform.关键词：RV reducer;Cycloid gear;Modification;Tooth profile equation;Pressure angle
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发布时间：2022-11-10 - 摘要：By using the three-parameter shift law， the algorithm and parameter optimization are carried out to overcome the shortcomings of traditional BP neural network in optimized BP neural network of gear position decision， and then the optimized BP neural network is obtained. Taking the dual motor multiple speeds AMT of pure electric vehicle as the object， the experimental data are collected， the neural network before and after optimization is constructed， and then the training and simulation analysis are carried out. It can be concluded that the neural network has a faster learning speed by training the neural network. By analyzing the training process， it is concluded that the optimized neural network has faster learning speed， and the optimized neural network gear position decision model has higher accuracy through simulation analysis of the corresponding model after training， and the optimized parameters provide reference value for the corresponding theoretical research.关键词：Three-parameter
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发布时间：2022-11-10
Theory·Reserach
- 摘要：A series of six-degree-of-freedom mechanism is proposed for the needs of wind tunnel capture trajectory experimental equipment. The kinematics positive solution model of the mechanism is established. For the problem of the inverse kinematics of the series mechanism， the inverse kinematics of this mechanism is explored by BP neural network and numerical method. In the face of the problem that the initial value estimation is difficult when the inverse method of numerical method is solved， a new method is proposed. The correctness of the method is verified by an example analysis. The problem of initial value estimation when solving numerical method is solved， which makes the numerical method solve the inverse solution smoothly. Compared with BP neural network， the numerical method has higher precision.关键词：Serial mechanism
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发布时间：2022-11-10 - 摘要：Serial and parallel configurations are mutually exclusive in performance and structure， this prevents performance advantages from being combined. To solve this problem， a novel hybrid configuration which can realize serial and parallel switching based on a motion bifurcation mechanism is proposed， and a reconfigurable dual operation manipulator is designed. The structure of the new manipulator is introduced， the degrees of freedom under each configuration of the reconfigurable manipulator are analyzed， and the characteristics of degrees of freedom of 3-RSR/S parallel base are analyzed by using screw theory. By comparing the constrained screw systems with the adjacent configurations of the reconfigure manipulators， the feasibility analysis is carried out. According to the motion characteristics of the manipulator in different modes， based on the control theory of CPG (central pattern generator)， the multi-mode control and mode switching are realized， the feasibility of the manipulator mode switching is verified by simulation experiments. The results show that the design scheme is reasonable and feasible， and the further prototype model design is completed. The new configuration is a new attempt in the innovation and development of complex advanced equipment， and can be extended to the special working conditions with more station properties.关键词：Hybrid configuration
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发布时间：2022-11-10 - 摘要：In order to improve the stability of the lower extremity exoskeleton robot climbing the stair， the reasonable gait planning and error correction are two important aspects. To this end， an online correction method of zero moment point (ZMP) during the stair step is proposed. Firstly， the movement model of the lower limbs climbing the stairs is established， the kinematics analysis is performed， and the lower limb joint trajectory planning is performed by using the 5 times B-spline curves. Secondly， the online ZMP correction is used to adjust for large errors between the actual and planned ZMP trajectories caused by unstable disturbances in the wear process. Finally， through simulation and actual experiments， this online correction can significantly reduce the ZMP error of the robot， improve the stability margin of the robot ZMP， and ensure the overall stability of the lower limb robot system.关键词：Lower extremity exoskeleton robot
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发布时间：2022-11-10 - 摘要：In order to study the ultra-short harmonic reducer with high performance， the topology optimization theory is introduced into the design of harmonic flexspline design. The objective function of stiffness is defined based on compromise programming method， and the topology optimization model of flexspline is constructed with constraints of volume fraction and processing technology. The optimization problem is solved by using the criterion of optimization algorithm based on Abaqus/ATOM software. The secondary design is carried out by using the SolidWorks， and through the finite element analysis， the rationality of results before and after optimization are verified. The method has practical significance for the design and optimization of ultra-short harmonic flexspline.关键词：Ultra-short harmonic lexspline
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发布时间：2022-11-10 - 摘要：In order to meet the requirements of the configuration innovation of the multi-axis linkage processing platform， a new type of 2R1T 3-PzPxS parallel mechanism is synthesized， which contains a planar pantograph structure unit in the branching chain. The branch chain configuration is proposed and optimized to verify the degree of freedom of the mechanism. The forward and inverse analytical solutions of the mechanism position are derived and obtained， which is convenient for subsequent motion planning and control. Based on the Jacobian matrix of mechanism， the parameter conditions resulting in positive kinematic singularities are confirmed. After obtaining the workspace of the mechanism by using the boundary search method， it is determined that the mechanism has a large rotational capacity. The related results lay a theoretical foundation for the research of high efficiency NC machining center.关键词：Pantograph structural unit
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发布时间：2022-11-10 - 摘要：Aiming at the design of transmission ratio for two-speed transmission of pure electric vehicle， under the condition that parameters of vehicle and motor are all determined， choosing the transmission ratios as the design variables， the optimization objective function and constraint conditions are established according to the power consumption of 100 kilometers under NEDC(The New European Driving Cycle) working condition and the dynamic performance design requirements of vehicle， then the improved harmony search algorithm is used to calculate the optimal solution of the optimization model under constraint conditions. The result shows that the selected two-speed transmission basically meets the design requirements. Compared with the original single-speed transmission， the design results obtained by this method improve the economy of the vehicle to a certain extent.关键词：NEDC working condition
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发布时间：2022-11-10 - 摘要：In order to study the temperature characteristics of a corrugated Magnetorheological Brake(MRB) applied to the vehicle under the strong coupling of magnetic fluid thermal field， the finite element analysis models of magnetic fluid coupling and thermal fluid coupling are established. The magnetic field distribution， temperature distribution under steady non-braking condition， and the transient temperature distribution under normal braking， emergency braking and frequency interval braking conditions are obtained by using direct sequential coupling method. The results show that the temperature distribution of corrugated MRB is nearly uniform under steady non-braking condition， while the maximum temperature under normal braking， emergency braking and frequency interval braking conditions are 92.4 ℃， 111.2 ℃ and 80.4℃ respectively， the temperature in the brake clearance shows a tendency of rising first and then falling. With the increase of excitation current， the maximum temperature of MRB device gradually increases in the process of breaking， but， its rising range is smaller and smaller. The results can provide reference for the design and application of MRB.关键词：Magnetorheological brake
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发布时间：2022-11-10 - 摘要：A new structure of underactuated manipulator is proposed to meet the need of multi-functional end fixture of robot. The most innovative point of the manipulator is that its end knuckle is completely passive envelope， which improves the grasping stability. The grasping attitude analysis and stability analysis are carried out， the feasibility of the scheme is verified， and the grasping attitude of different objects is verified. The prospect of the control strategy research is put forward.关键词：End fixture
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发布时间：2022-11-10 - 摘要：A new idea for dynamics modeling of multibody systems is provided by the Udwadia-Kalaba equation. The generalized constrained relationship is established to obtain the constraint relations in analytical form. The improved Udwadia-Kalaba equation is proposed to eliminate the error which generates during the modeling process by Udwadia-Kalaba equation. The stimulation results show that the proposed methods can be more effectively utilized in dynamics modeling of dual-arm robot.关键词：Udwadia-Kalaba equation
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发布时间：2022-11-10 - 摘要：Based on the principle of passive walking， a passive two-bar walking model is established， the system dynamics equation is derived and the numerical solution is carried out. On this basis， four energy conversion modules and passive assistant power joints are designed. Combining ergonomics， a powerless exoskeleton structure is designed and kinematics simulation is carried out. Using the theoretical research results， a principle prototype is processed， and the related tests and experiments are carried out.关键词：Passive walking
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发布时间：2022-11-10
Design· Calculation
- 摘要：With the consideration of the thermal effect and piezo-viscous characteristic of lubricants， the numerical model of line contact elastohydrodynamic grease lubrication between cycloid gear and pin wheel is established， and the fully numerical solution of the model is obtained and the grease film pressure distribution， grease film temperature rising distribution and the grease film shape of are obtained. Combined with the profile of the cycloidal wheel， the effect of the tooth profile modification schemes and the modification quantity on grease film pressure， grease film shape， grease film temperature rising and friction power loss are analyzed. The results indicate that as the radial clearance between the modified tooth profile and the theoretical tooth profile increases， the friction loss power increases， and the minimum grease film thickness increases first and then decreases. Under the condition of the same radial clearance between the modified tooth profile and the theoretical tooth profile， the lubrication performance of the anti-bow profile modification is better that the positive equidistant modification with positive radial-moving modification. The negative equidistant modification with negative radial-moving modification has the worst lubrication performance. This study provides a new method for tooth profile modification of the cycloidal gear of the RV reducer by considering lubricity.关键词：Tooth profile modification
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发布时间：2022-11-10 - 摘要：In order to accurately estimate the fatigue life of the wind power planetary gear train under actual working conditions， the 1.5 MW 2K-H helical gear planetary gear train is taken as the research object. By establishing an accurate three-dimensional geometric model， using the Hyper-Mesh finite element hexahedron mesh and transient dynamics analysis， the stress history and stress structure response of the planetary gear train meshing are obtained， and combined with nCode DesignLife for fatigue analysis. The results show that the planetary gear train will have an eccentric load during the meshing process. The stress is concentrated at the contact between the sun gear and the planetary gear. The fatigue damage is concentrated at the contact between the planetary gear and the ring gear. When the tooth surface roughness is in the range of 1~2 μm， the fatigue life decreases with the increase of the roughness.关键词：Helical planetary gear train
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发布时间：2022-11-10 - 摘要：In order to study the characteristics and variation of noise in vehicle V-ribbed belt transmission， the mechanism of V-ribbed belt noise is analyzed. By establishing the theoretical model of friction vibration， the unstable conditions of V-ribbed belt transmission system are deduced. The vibration and noise of V-ribbed belt transmission are measured on the designed vibration and noise test bench. The experimental results show that，the fluctuation of tension force results in low frequency vibration noise of V-ribbed belt， and the viscoelastic sliding between belt and pulley results in high frequency friction noise.关键词：Friction;Viscoelastic;Noise;Vibration
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发布时间：2022-11-10 - 摘要：To study the effect of the parameters of permanent magnet eddy-current flexible transmission on multiple performance objectives of output performance， the accurate analytical model is built. By using the method of separation of variables， the output performance under different parameters is calculated， the accuracy of the model of permanent magnet eddy-current flexible transmission is verified by using the finite element simulation software ANSOFT. After that， the sensitivity of the different parameters to multi-objective optimization is analyzed， and the main parameters of multi-objective optimization design are determined. The results show that， the analytical model of permanent magnetic eddy-current flexible transmission is very accurate. After analysis， it is shown that different parameters have different effects on output performance. It has a good reference for preliminary design and optimization design.关键词：Permanent magnet eddy-current
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发布时间：2022-11-10 - 摘要：Based on the bench test of oil pump， the influence of pump outlet pressure on flow pulsation of external gear oil pump is analyzed. The results show that the flow pulsation coefficient of the oil pump decreased with the increase of pump outlet pressure. The effects of different teeth number， modulus， pressure angle and end clearance on flow pulsation of oil pump are investigated by method of theoretical derivation and simulation. The analysis showed that the modulus had no effect on the flow pulsation of oil pump. The analysis shows that the pressure angle， the number of different teeth and the end clearance are the main factors affecting the flow pulsation. The flow pulsation coefficient decreased gradually with the increase of pressure angle. Increasing the number of driving gear teeth and driven gear teeth are beneficial to reducing the flow pulsation coefficient and improving the flow pulse phenomenon of oil pump. Among them， the number of driving gear teeth has a great influence on the flow pulsation. The flow pulsation coefficient of the oil pump decreased with the increase of the end clearance.关键词：External gear pump
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发布时间：2022-11-10 - 摘要：The radial permanent magnet coupling has the characteristics of high transmission efficiency， environment protection and easy assembly， due to the disconnection of the main and follower rotors， errors easily occur in the manufacturing and installation process， which affects the stability of the structure and causes the problem of vibration of the radial axis. Because of the complexity of the expression of magnetic force， it is difficult to solve by analytical mechanics. For this， the Lagrange equation of dissipative system is used to establish its dynamics equation from the angle of energy， and the bifurcation diagram of the system varying with the error value and displacement response diagram with different error values are obtained by solving it according to the actual parameters. The installation accuracy of the stable transmission of the system is obtained， meanwhile， the feasibility of the established dynamics model is also verified.关键词：Radial permanent magnet coupling
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发布时间：2022-11-10 - 摘要：The rolling bearing fault signal of the gearbox is difficult to extract effectively due to noise interference. A fault feature extraction method of gearbox rolling bearing based on VMD and fast-kurtogram is proposed. Firstly， the vibration signal of bearing is decomposed into several Intrinsic Mode Function (IMF) components by VMD， and the component signal with the most prominent fault information is selected by the correlated kurtosis， and then the bandpass filtering is adaptively determined by the fast-kurtogram. Finally， the filtered signal is subjected to squared envelope spectrum analysis to extract fault information. The effectiveness and feasibility of the proposed method are demonstrated by public bearing fault data analysis and gearbox bearing fault experiments.关键词：VMD
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发布时间：2022-11-10
Test·Analysis
- 摘要：Based on the accurate mathematical model， the meshing model of Hy-Vo silent chain with the plate-sprocket subsystem and hob-sprocket subsystem is established. Through building the auxiliary chain plate， a new algorithm to calculate the profile shift coefficient of involute sprocket based on meshing variation for Hy-Vo silent chain transmission system is proposed. Combined with a specific example， the profile shift coefficients are calculated by the new algorithm and the classical algorithm. Based on the virtual machining technology， the actual machining sprocket under different algorithms is obtained. Through measuring the tooth widths under different radius， the tooth profile deviations of actual sprocket are contrastingly analyzed. Based on the multi-body dynamics simulation， the meshing characteristic of the Hy-Vo silent chain transmission systems under different algorithms are analyzed. The results show that the new algorithm could effectively decrease the system performance deviation between the ideal condition and the actual condition. In addition， the new algorithm could not only the calculation results are more accurate， but also applicable to any variation combination of hub tooth angle and sprocket pressure angle.关键词：Meshing variation;Hy-Vo silent chain;Profile shift coefficient;Multi-body dynamics simulation;Virtual machining
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发布时间：2022-11-10 - 摘要：Based on the analysis of the results of the loss-of-lubrication test of helicopter reducer， the design and analysis method of the loss-of-lubrication capacity of reducer is studied from the aspects of gears， bearings， casing， lubrication system and lubricating medium. The detailed design of parts and components in the design stage of reducer is guided. The loss-of-lubrication test method is analyzed. The method is verified by the loss-of-lubrication test of design examples. The situations that only rely on prototype test results can be relied on to optimize the design in the past is changed， and the guiding opinions of previous loss-of-lubrication test conclusions are improved.关键词：Aircraft design
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发布时间：2022-11-10 - 摘要：For higher effective volume ratio of roots pump， from high output production and low inner leakage， the shaped-profile configuration of a ellipse basic rotor and its raised rotor of is constructed. Firstly， from ellipse coordinate equation of rotor shaped-profile and conjugate principle of rotor pairs and critical conjugate conditions， the optimum axial length ratio of ellipse arc and the maximum shape coefficient of basic rotor are calculated. Secondly， based on the geometric relationship when the endpoint of valley working shaped-profile on driving rotor is just perfect to avoid the peak corner point on driven rotor， the maximum shape factor of raised rotor under a given addendum angle is determined. Finally， all parameter coordinate equations of raised shaped-profiles are provided， and the comparative advantage results of raised rotor to common circular arc rotor is focused on. All results show that the elliptical arc foundation rotor and high-profile rotor profile construction method have significant improvement in both high yield and leakage prevention effects， and the fundamental problem of the optimal axial length ratio and maximum shape factor of the arcs arc of the Roots pump is solved.关键词：Roots pump
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发布时间：2022-11-10 - 摘要：In order to determine the significant characteristic factors affecting grinding burn， according to the actual conditions， the DOE（Design of Experimentation）of Six Sigma Quality Tool is used to carry out experiments， and the significant characteristic factors affecting grinding burn are researched， and the optimum grinding process parameters are fitted. The results show that， the optimal grinding parameters are obtained through simulation of rough grinding and fine grinding， and the experimental processing is carried out， and the grinding burn rate of the formed grinding teeth is effectively controlled， which provides a basis for improving efficient and reducing production cost of enterprises.关键词：Experimentation design
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发布时间：2022-11-10 - 摘要：Aiming at the problem of the poor working environment and the fault mode is difficult to identify of the gearbox of military armored vehicles， based on the existing methods， the noise assisted analysis， LMD and BP neural network are combined to apply to the fault diagnosis of armored vehicle gearbox. Firstly， the vibration signals under the four typical states of normal gearbox， bearing clearance fault， indentation of outer ring and broken tooth of gear of the gearbox are collected on the self-built test bench. Then， the signal is decomposed by the noise-assisted LMD method， and the energy eigenvalues of the first eight PF components are extracted. The extracted feature values are used as the input of the BP neural network. The fault type of the gearbox is identified based on the output result. The results show that the method can be effectively applied to the fault diagnosis of military armored vehicle gearbox， and the diagnostic accuracy rate is 92.5%. An effective reference way for other special gearbox diagnosis is provided by this study， and it has certain engineering practical value.关键词：Gearbox
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发布时间：2022-11-10
Development·Application
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