最新刊期
卷 47 ， 期 6 ， 2023
- 摘要：The time-varying meshing force caused by the transmission characteristics of non-circular gears has an important influence on gear drive wear. The elliptic gear pair of the key core components in combing machine is taken as the research object, and a calculation model of gear wear based on the time-varying meshing force is established by applying Hertz basic theory and Archard wear formula. The meshing stiffness of non-circular gears is solved by using the equivalent tooth number method, and the dynamic meshing force and wear of single tooth profile are analyzed. On this basis, the effects of order and eccentricity on dynamic meshing force and wear of elliptical gears are studied. The results show that the dynamic meshing force and wear of gear surfaces increase with the increase of eccentricity and order of elliptical gears. The time-varying meshing force changes at the junction of single and double tooth meshing zone. The tooth profile wear is close to zero near the pitch circle, and the wear is larger at the root and the crown. It is found that the root wear at the radial of the smallest section curve is significantly larger than that at the radial of the largest section curve. The results provide a theoretical basis for using the modification method to reduce the dynamic meshing force and wear, thus prolonging the life of gears.关键词：Non-circular gear;Gear wear;Time-varying meshing force;Dynamics model;Number of equivalent gears
- 69
- |
- 29
- |
- 0
发布时间：2023-08-14 - 摘要：For spur gears with more than 41 teeth, based on the geometry of cutting teeth and the principle of gear meshing, the difference between the starting point of the involute profile and the intersection of the involute and the base circle is clarified, and the transition curve parameter equation is introduced to calculate the time-varying meshing stiffness based on the energy method. The formula has been improved, and the faulty gear tooth models with different crack degrees are comprehensively established. On this basis, the oblique line is used as the effective tooth thickness reduction limit line, which makes the crack tooth model stricter and the considerations more comprehensive. With reference to the calculation results of the finite element method, the effects of model correction, crack extent, and the specific form of the effective tooth thickness reduction limit line on the time-varying meshing stiffness are discussed respectively. The calculation results show that the uncorrected gear tooth model will lead to a small calculation result of the time-varying meshing stiffness of gears with large numbers of teeth; the reduction degree of meshing stiffness increases with the increase of the crack level. According to the degree of cracks, the modeling suggestion for the effective tooth thickness reduction limit line is given: when the crack level is low, the effective tooth thickness reduction limit line should be a straight line; when the crack level is high, using a straight line will cause significant errors. Using a diagonal line is not only convenient for calculation, but also can meet the requirements of calculation accuracy and has stronger practicability.关键词：Large numbers of teeth;Tooth root crack;Different degrees of cracks;Effective tooth thickness reduction limit line;Time-varying meshing stiffness
- 37
- |
- 14
- |
- 0
发布时间：2023-08-14 - 摘要：In order to study the dynamic characteristics of flap transmission mechanism with clearance joints, based on an improved nonlinear normal impact force model with variable stiffness, and the elastic factor of connecting rod, the angular velocity and angular acceleration of the steering gear are simulated and analyzed with the conditions of different clearance joints （c=0、c=δ and c=1.6δ） , and different friction parameters （0.06、0.08 and 0.1）. The dynamic output angular velocity and angular acceleration of the flap transmission exhibit obvious oscillation, and the amplitude of the angular acceleration is larger than that of the angular velocity oscillation; at the same time, when the driving load changes, the angular velocity and angular acceleration fluctuate greatly, but the fluctuation degree in the case of c=0 is greater than that with clearance; in addition, the higher the friction coefficient at the clearance joint is, the greater the amplitude of angular velocity and angular acceleration oscillation are, accompanied by high-frequency oscillation and delay phenomenon.关键词：Clearance joint;Flap transmission mechanism;Rigid flexible coupling;Dynamic characteristics
- 32
- |
- 15
- |
- 0
发布时间：2023-08-14 - 摘要：Loaded transmission error is an important parameter in evaluating the meshing performance of gears. The smaller the fluctuant amplitude of the loaded transmission error is, the better the meshing performance is. In view of the insufficient research on loaded transmission error of internal spur gears, software Romax is used to establish models of internal short tooth spur gear pairs in this research. The influence of tooth profile and gear helix modification parameters on fluctuant amplitude of loaded transmission error is studied, and some influence laws of the modification parameter on the fluctuant amplitude are obtained. A modification optimization method for internal short tooth spur gear pairs is investigated using the particle swarm algorithm. The research results lay a foundation for improving the meshing performance of internal short tooth spur gears.关键词：Internal spur gear;Short tooth;Loaded transmission error;Modification;Optimization
- 39
- |
- 17
- |
- 0
发布时间：2023-08-14 - 摘要：The main transmission system in a spent fuel reactor is a face gear drive, which works in concentrated nitric acid with high-temperature, and requires not to be damaged under earthquake. To design its strength reasonably, the dynamic performance of the face gear drive is studied. Its meshing principle and characteristics are briefly elaborated. The dynamic model of the face gear drive is established based on the centralized mass method.The influence of factors such as manufacturing errors and misalignments, time-varying meshing stiffness, corrosion on tooth surfaces, earthquakes on the dynamic performance are taken into consideration to deduce the differential equations of the face gear drive. Runge-Kutta method is applied to solve the differential equation, the dynamic loads under excitations of misalignment, earthquake and corrosion are obtained, and the influence law of these excitations on the dynamic load coefficient is further analyzed. The corrosion and earthquake are the key factors that cause significant increase of dynamic load coefficients, the dynamic load caused by the combined action of the considered various factors is less than twice the driving load.关键词：Spent fuel;Reactor;Face gear drive;Meshing stiffness;Dynamic load coefficient
- 21
- |
- 15
- |
- 0
发布时间：2023-08-14
Theory·Research
- 摘要：Based on the topology design theory and method of parallel mechanism of position and orientation characteristic (POC) theory, a new 3-DOF parallel mechanism with cylindrical translation and one rotation (2T1R) is designed, and the topological characteristics of the mechanism are analyzed, including the calculation of the position and orientation characteristic set, degrees of freedom and coupling degrees; then the kinematics of the mechanism is analyzed, the forward and inverse solutions of the position of the mechanism are solved and verified; finally, based on the forward and inverse position solutions of the mechanism, the work space and rotation capacity of the mechanism are analyzed. The work of this research lays a foundation for the subsequent scale optimization, error analysis and dynamic analysis of the mechanism.关键词：Parallel mechanism;Bending translation;Kinematic analysis;Workspace
- 27
- |
- 10
- |
- 0
发布时间：2023-08-14 - 摘要：A station in the Chinese Baijiu box packaging production line has a height difference between the two production lines due to the workshop layout, and the height difference will increase the defective rate of the Chinese Baijiu box base of the station. Aiming at the problem of high defective rate, a 1R2T parallel mechanism is proposed in this research. Based on the screw theory and screw reciprocity principle, a variety of parallel mechanisms that can meet the needs of the station are synthesized. According to the field working conditions, a 2RPS-RPR parallel mechanism is designed, which can realize the 1R2T function and has three degrees of freedom. The inverse solution analysis and workspace description of the parallel mechanism are carried out, and the three-dimensional model of the parallel mechanism is drawn according to the layout of the production line. The rationality of the mechanism motion is analyzed. It is obtained that the combination of configuration design based on the screw theory and actual working conditions is a very effective theoretical analysis method.关键词：Chinese Baijiu box packaging;1R2T motion;Parallel mechanism;Screw theory;Configuration design;Workspace
- 29
- |
- 14
- |
- 0
发布时间：2023-08-14 - 摘要：Focusing on the demand of energy and heavy machinery for high efficiency and high output capacity of transmission equipment, this research studies the multi-objective optimization of the NN type small tooth difference transmission with the highest efficiency and maximum output capacity. Firstly, traverse all tooth number combinations in the optimization space under different tooth number difference, different staggered tooth difference in a certain range of teeth, and get the tooth combinations table. Then, the multi-objective optimization model of the NN type small tooth difference transmission is established, taking the number of teeth combination, standard pressure angle, meshing angle, addendum height coefficient and displacement coefficient as the optimization design variables and considering the overlap ratio, tooth profile overlap interference and addendum thickness constraints. The multi-objective differential evolution algorithm based on Pareto is used to solve the optimization model, and the distribution of Pareto optimal solution set is obtained. The results obtained in this study are compared with those in the standard design manual. The comparison results show that the results in this study are better than those in the standard design manual, which can provide reference for the design of NN type small tooth difference transmission.关键词：Small tooth difference transmission;Efficiency;Multi-objective optimization;Evolutionary algorithms
- 21
- |
- 19
- |
- 0
发布时间：2023-08-14 - 摘要：In order to solve the problem of fracture failure of the existing vibration grinding mill connecting rod within the design service life, the structural optimization design of the connecting rod is proposed. Firstly, the kineto-static analysis is used to solve the external force applied to the crank-slider mechanism in one motion cycle, which is used as the theoretical basis for the subsequent strength analysis. Secondly, Ansys Workbench is used to complete the static strength analysis and fatigue strength analysis of the connecting rod. It is determined that the failure of the connecting rod is caused by insufficient fatigue strength. Finally, the response surface methodology is used to optimize the design of the connecting rod. The objective of the optimization is to minimize the mass of the connecting rod, and the optimized constraint is that the fatigue strength of the connecting rod meets the standard. This optimization design determines the appropriate transition fillet radius, thin end ring thickness and shaft width. The maximum tensile load equivalent stress of the optimized connecting rod is reduced by 58.7%, and the fatigue life is increased by 1.4 times. The optimized connecting rod meets the operation requirements.关键词：Connecting rod;Crank-slider mechanism;Kineto-static analysis;Finite element analysis;Response surface optimization design
- 23
- |
- 11
- |
- 0
发布时间：2023-08-14 - 摘要：The traditional calculation of roller contact load and contact deformation includes a number of calculation, which is prone to system collapse. In this research, three equivalent mathematical models are established by using the equivalent substitution method, the deformation of rollers is solved by using the Newton iterative principle, and then the contact deformation and contact load of different rollers under the three mathematical models are obtained. According to the number arrangement from small to large, the change range of contact deformation and contact load of any roller at different times is obtained. Compared with the traditional calculation method, the program generated in this study is fast, not prone to system collapse, and the calculation results meet the numerical value of the traditional method.关键词：Cylindrical roller bearing;Contact load;Contact deformation
- 22
- |
- 10
- |
- 0
发布时间：2023-08-14 - 摘要：The forming mechanism of large modified flexspline is studied based on hobbing simulation calculation, the theoretical machining error of tooth surface and its causes are analyzed, and the hob is redesigned to improve the hobbing accuracy of large modified flexspline. The parameter equation of a series of hob cutting edges is established, the mutual position and spatial motion relationship of the hob and the workpiece are determined according to the geometric parameters of hob and workpiece and machining parameters, and the gear hobbing simulation is carried out. According to the forming characteristics of hob multi-edge cutting, the theoretical machining error evaluation model of tooth surface is established to simulate the hobbing error. The hob is redesigned based on the principle that the normal base pitch of hob is equal to that of gears during hobbing to reduce the hobbing tooth surface error. It is found that the tooth profile error near the tooth top will be large when the standard hob is used to machine the large modified flexspline, because the number of cutting edges of standard hob is insufficient and the tooth top will be under-cut; the new hob which module and pressure angle are different from that of the standard hob can realize the complete cutting of each tooth of large modified flexspline with only a few cutting edges, and the machining error of the tooth surface is smaller than that of the standard hob when the tooth surface is completely cut. The research results can provide important reference for the study of hobbing accuracy control of large modified flexspline and the selection of hob parameters.关键词：Harmonic gear;Large modified flexspline;Hobbing simulation;Tooth surface error;Hob design
- 39
- |
- 19
- |
- 0
发布时间：2023-08-14
Design· Calculation
- 摘要：In order to grasp the dynamic characteristics of the gear transmission system of high-speed trains under the torque excitation of the driving end and the load end, the pure torsional vibration model of the gear transmission system of high-speed trains is established. The analytical solution of the system under the torque excitation of the driving end and the load end is obtained by using the incremental harmonic balance method (IHBM). The rationality of IHBM is verified by comparing with the numerical solution of the system. By drawing the frequency response curve of the system, the influence of the change of the main parameters in the torque excitation of the driving end and the load end on the dynamic characteristics of the system is analyzed. The results show that there are several high-order super harmonic resonance regions, amplitude jumps, one or more multi-valued solution regions and other nonlinear characteristics in the system under the parameter changes of the driving end and the load end torque excitation. The research results have a unique reference value for in-depth analysis of the dynamic characteristics of the gear transmission system of high-speed trains under the torque excitation of the driving end and the load end.关键词：High-speed train;Gear transmission system;Pure torsional vibration;IHBM;Analytical solution
- 23
- |
- 10
- |
- 0
发布时间：2023-08-14 - 摘要：An experimental study is conducted to investigate the surface integrity in spindle barrel finishing of 14CrMnSiNi2MoA aviation cylindrical spur gears. The surface morphology, residual stress, microhardness, microstructure of aviation gears before and after barrel finishing are systematically studied by professional instruments. The results indicate that the gear surface integrity can be significantly improved by spindle barrel finishing. The surface roughness of the gear reduces to less than 0.2 μm and the average residual compressive stress of the gear surface increases by about 45%. The hardness of the gear surface also increases. The results of surface roughness and residual stress distribution before and after barrel finishing reveal that the increase of residual compressive stress and decrease of roughness of the gear surface increase gradually from the root to the top of the gear, which provides a basis for the setting and designing of processing parameters in barrel finishing.关键词：Aircraft gear;Barrel finishing;Surface morphology;Residual stress;Microhardness
- 27
- |
- 14
- |
- 0
发布时间：2023-06-19 - 摘要：Aiming at the problem that the speed of the contact point of the multi-section pipeline robot changes abruptly during the turning process, which will affect the stability of the robot's motion, the turning process of the robot is explored. Based on the pose model in the pipe bend of the pipe robot, the position and velocity of the contact point between the robot and the pipe are solved. Firstly, the turning process of the robot is briefly described; secondly, the pose model of the pipeline robot in the pipe bend is established and the position of the contact point between the robot and the pipeline is solved; then the speed of the robot is analyzed to find the attitude angle where the speed of the robot does not change suddenly. Finally, the correctness of the conclusion and the solution process is verified by the Matlab numerical solution and Adams simulation, which lays a foundation for the continuous and stable control of robot turning process.关键词：Pipeline robot;Turning process;Stability analysis;Attitude angle;Simulation verification
- 30
- |
- 11
- |
- 0
发布时间：2023-08-14 - 摘要：The application of the multi-branch gear transmission in the power transmission system of high-power ships is increasing gradually. The elastic shaft structure used to realize the uniform load of each branch will lead to the reduction of the natural frequency of the transmission system, which will increase the possibility of resonance during operation. Based on the commercial finite element software (Ansys), a finite element model of a marine six-branch coaxial herringbone gear transmission system is established. The rotational degrees of freedom are reserved at each support, and the remaining degrees of freedom are constrained. The first 20 orders of natural frequencies and vibrations of the transmission system are calculated. Based on the Campbell diagram, the resonance characteristics of the system are analyzed for cruise speed. The influence law of the elastic shaft stiffness on the natural frequency of the system is studied, and the value range of the elastic shaft stiffness to avoid the resonance of the transmission system is obtained, which provide some reference for the vibration reduction design of the six-branch coaxial herring gear transmission system.关键词：Herring gear;Split transmission;Natural characteristics;Resonance analysis;Elastic shaft stiffness
- 19
- |
- 14
- |
- 0
发布时间：2023-08-14 - 摘要：In order to study the influence of relevant parameters of the swashplate engine pendulum mechanism on engine dynamic performance, a mathematical model which can express the relationship between its design parameters and engine dynamic performance is established through the derivation of relevant parameters of the swashplate engine pendulum mechanism. Combined with the mathematical model, the influence of the change of the number of cylinders of the pendulum mechanism on the output speed and the displacement of the center of mass of the swashplate are studied using the control variable method, and the Admas simulation analysis is carried out. The results show that when the number of cylinders is selected as the independent variable, the inclination angle of the swashplate decreases gradually from 29.93° to 14.26°, and the average deviation of speed is the smallest when the number of cylinders is 7, which is 0.005 4 r/min; the average displacement of the swashplate centroid on x-axis and y-axis is also the smallest, which are -0.005 9 mm and -0.016 7 mm respectively; the average displacement on the z-axis is 0.038 8 mm, which is not the minimum value, but the offset amplitude is smaller. The results show that when the number of engine cylinders is 7 and the inclined angle of the swashplate is 16.35°, the stability of the spindle speed and the stability of swashplate are the best, which provides some reference for the parameter design of swashplate engines.关键词：Swashplate engine;Pendulum mechanism;Mathematical model;Simulation;Dynamic performance
- 21
- |
- 9
- |
- 0
发布时间：2023-08-14 - 摘要：In order to improve the detection level of transmission error of worm gear pairs, an instrument suitable for measuring transmission error of middle and large worm gear pairs is designed. This research describes the basic framework of the transmission error detection system and the overall design of the instrument. The working principle of the instrument is introduced, and the idea of integrating the time-grating sensor and the related parts of the instrument is put forward. SolidWorks is used to design the key parts and complete the structure layout and virtual assembly. Finite element analysis and structural optimization are carried out on the beam assembly by the Ansys Workbench. After optimization, the first-order natural frequency increases by 23.95%, and the corresponding amplitudes of all natural frequencies decrease significantly.关键词：Worm gear pair;Transmission error;Time-grating sensor;SolidWorks;ANSYS Workbench
- 19
- |
- 8
- |
- 0
发布时间：2023-08-14
Test·Analysis
- 摘要：A new precision cycloidal reducer with movable output-pins is proposed. Firstly, the transmission principle and structural characteristics of the cycloidal reducer with movable output-pins are explained, and the new cycloidal reducer is equipped with the movable output-pin mechanism, which can significantly improve the transmission efficiency of the reducer by changing the sliding friction between the output-pin and the pin-hole into rolling friction. Secondly, the static characteristics of key transmission components are calculated, and the effects of cycloidal tooth profile modification and pin-hole fit clearance on the cycloidal transmission meshing force and movable output-pin contact force are analyzed, respectively. Then, the modal characteristics of the reducer are analyzed based on the finite element technology and the inherent frequencies and vibration characteristics of each order of the reducer are obtained. Finally, the physical prototype of the cycloidal reducer with movable output-pins is manufactured and the transmission efficiency is tested, which provides an effective technical solution for the product innovation of industrial robot precision reducers.关键词：Cycloidal reducer;Movable output-pin mechanism;Static analysis;Modal analysis;Prototype manufacturing
- 19
- |
- 11
- |
- 0
发布时间：2023-08-14 - 摘要：In view of the problem of difficulties in extracting low-dimensional sensitive features from rolling bearing vibration signals, a rolling bearing fault feature extraction method based on logistic regression optimization variation mode decomposition(VMD) and uniform manifold approximation and projection(UMAP) is proposed. Firstly,the method divides the original data into samples by the moving window method, and completes the construction of the training set as well as the test set. Secondly, a part of the training set is randomly selected for VMD with different number of modal decompositions, and features are extracted for each layer of sub-signals to complete the construction of multiple feature sets. Then, the complex correlation coefficients between each feature and the label in each feature set are calculated by logistic regression to determine the number of modal decompositions and highly correlated features, which are applied to the training set and the test set to obtain the high-dimensional feature data set. Finally, UMAP is used to obtain low-dimensional features with high discriminative power to complete the final feature set construction. Using the recognition accuracy of three commonly used intelligent algorithm and the ratio of intra-class cosine distance and inter-class cosine distance in the tested feature set as evaluation indexes, the results show that the method not only achieves effectively extract features of various bearing failures, but also has good noise immunity, which is of certain reference value for the feature extraction in the practical bearing fault diagnosis.关键词：Fault diagnosis;Rolling bearing;VMD;Logistic regression;UMAP
- 26
- |
- 19
- |
- 0
发布时间：2023-08-14 - 摘要：As a typical synergistic minimal quantity lubrication (MQL) technology, oils on water（OoW） has almost the same cooling performance as a large amount of pouring cooling oil and excellent lubrication performance. Based on the technical mechanism of OoW, the MQL products with advanced functions are developed for gear hobbing production, and the processing parameters are optimized in practice. The product application results show that： the MQL of gear hobbing has excellent properties such as reducing machining oil fume, improving tool life, expanding the machining modulus range of dry cutting machine tool and reducing carbon dioxide emission. It is of great significance to upgrade the traditional gear industry, develop new types of near dry cutting machine tools, and build green factories.关键词：MQL;OoW;Gear hobbing;Green manufacturing
- 45
- |
- 11
- |
- 0
发布时间：2023-06-19 - 摘要：In order to optimize the structural performance of the heavy truck drive axle and realize the market supply goal of the whole axle lightweight, the corresponding research is carried out based on CAE/CAM technology. Using the systematic layout thinking, the mathematical model is scientifically built, a complete lightweight design axle is formed through CAE simulation analysis and CAM collaborative production, and the prototype test is conducted. The results show that the weight of the whole axle after the lightweight design is relatively reduced by 12.7% and the transmission efficiency is more than 95% on the premise of meeting the key performance parameters such as noise limit and B10 life. This design method and thinking can provide reference ideas for the improvement of other parts of heavy trucks, especially in the field of the lightweight research, and it would have great application and promotion prospects.关键词：Drive axle;Lightweight;CAE/CAM technology;Collaborative production;Transmission efficiency
- 25
- |
- 20
- |
- 0
发布时间：2023-08-14 - 摘要：Aiming at the installation of prefabricated wall panels in today's assembly building, a new type of wall panel vertical machine is designed, which realizes the adjustment of the pitch position and position of the end grabbing device through the arm turnover mechanism, thus realizing the positioning and installation of prefabricated wall panels. The boom turnover mechanism belongs to the hydraulic linkage mechanism. Through the mechanical simulation analysis, it is found that the boom landing mechanism belongs to the main bearing mechanism and the driving cylinder has the largest load. Therefore, a scale optimization model is established for the boom landing mechanism to minimize the maximum load of the driving cylinder as the objective function. Based on the complex method, the optimal scale parameters of the boom turnover mechanism are obtained, and the maximum load of the driving cylinder before and after optimization is reduced by about 36%. Drive cylinder performance is significantly improved. The virtual prototype is built by Creo software and the rigid body dynamics simulation analysis is carried out. The mechanism scale optimization model is validated. Finally, the prototype development and the construction test are carried out, and the working performance of the boom turnover mechanism meets the design requirements.关键词：Assembly building;Vertical plate machine;Simulation analysis;Scale optimization;Complex method
- 26
- |
- 18
- |
- 0
发布时间：2023-08-14
Development·Application
- 摘要：With the acceleration of the aging society, the incidence of knee osteoarthritis (KOA) tends to be younger, which brings great trouble to the society and patients. In order to effectively inhibit KOA lesions and assist KOA rehabilitation after joint replacement, all kinds of sports braces and rehabilitation training devices are used. Among them, rehabilitation aids play an important role in the rehabilitation training of KOA people. In order to study the application of rehabilitation robots in the rehabilitation training of KOA people more comprehensively, this research systematically reviews the research status of robot structure control in rehabilitation training for people with lower limb movement disorders based on the analysis of the rehabilitation needs of KOA population at different stages of disease. The key technologies of rehabilitation robots for KOA people are analyzed as well, which provides a theoretical basis for the design of rehabilitation robots for KOA people in the future.关键词：KOA population;Knee replacement surgery;Robot;Assisted rehabilitation;Intervention strategy
- 31
- |
- 19
- |
- 0
发布时间：2023-08-14
Review
- Technical support is provided by Beijing Founder electronics co., LTD 豫ICP备05013835号-5
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0