| Spatial indexing cam mechanism is widely used in automatic machines, production lines and machining centers as the key component to realize the function from continuous input to intermittent output. According to point engagement processing technology, based on spherical envelope indexing cam mechanism this paper puts forward globoidal indexing cam mechanism with steel ball and makes research on geometric features, statics, kinematics and dynamics. Main tasks are as follows:Globoidal indexing cam mechanism with steel ball was proposed, and structural characteristics of the mechanism were analyzed. Cam profile raceway and indexing plate ball seat were modified based on spherical envelope indexing cam mechanism, and the structural characteristics of globoidal indexing cam mechanism with steel ball were analyzed. Profile equation of globoidal cam with double-circular-arc raceway was derived based on the rotation tensor transformation method and the spatial engagement principle. Pressure angle of globoidal cam was calculated; analysis of influences on pressure angles exerted by the center distance of mechanism, the radius of gyration of the indexing plate and the angular velocity ratio between cam and indexing plate was made; measures as to how to reduce pressure angles were come up with; the calculation formula of helix angle was given and the curvature of cam surface was analyzed, and then the induced main curvature at engaging point between cam profile and ball surface could be obtained. Geometric characteristic was the foundation of mechanism analysis, which could provide basis for structural design.Ball motion of globoidal indexing cam mechanism and mechanism statics were studied. Steel ball in globoidal indexing cam mechanism could rotate in any direction, and the rotation of steel ball had great influence on lubrication performance. Through analysis on the movement of steel ball can relative sliding velocity at engaging point between steel ball and cam and the curve of component velocity of steel ball with the rotation angle in each coordinate axis were obtained, and the redundant rotary motion of steel ball was also researched. Based on the analysis of steel ball motion to analyze the force of mechanism could get the force of cam, indexing plate and ball respectively. Analysis of the contact characteristics between cam and steel ball at the engaging point was carried out. contact stress was calculated, and the influence of structure parameters on contact characteristics was analyzed which could be improved by the conclusions. Based of three-dimensional model of the mechanism kinematics simulation was conducted, and simulation results could provide proof of accuracy of the model.Dynamics of globoidal indexing cam mechanism with steel ball was studied. To get the globoidal indexing cam mechanism with high speed and high accuracy, dynamic characteristics of mechanism must be researched. This dissertation mainly used lumped mass method to analyze the dynamic characteristics of the mechanism. Torsional dynamic model of the mechanism was firstly established, equivalent contact stiffness between cam and indexing plate was built, geometric displacement relation of minimal variation quantity of generalized coordinates was analyzed, and finally the torsional dynamic equation was established by using Lagrange equation. Based on torsional dynamic model, a more precise dynamic model of the mechanism can be obtained with further consideration of transverse and axial vibration of the input and output shaft, then the dynamic equations were established. Through solving the dynamic equation multiple natural frequencies, low-order vibration mode and velocity and acceleration response of mechanism were obtained. Torsional deformation of cam shaft and indexing plate and the influence of stiffness change on dynamic characteristics were analyzed.Motor factors considered, taking the permanent magnet synchronous motor as driving motor, dynamic analysis of the whole system was analyzed. Electromechanical coupling dynamic model of system was established. Through establishment of mechanics equations and voltage equations of system electromechanical coupling dynamic equations were obtained. Through solving the electromechanical coupling dynamic equations motor speed, current, and acceleration curve of indexing plate and load plate were obtained, and the influence of motor speed and load change on electromechanical coupling vibration characteristic was also obtained. Analysis on electromechanical coupling dynamic model can reveal the relationship between motor characteristic and dynamic characteristic of mechanism. By introducing PI control acceleration curves of indexing plate and load plate of the system were reached, and the dynamic characteristic of the system could be improved. Based on Simulink simulations of electromechanical coupling dynamic model based on PI control and fuzzy PI control respectively motor speed, current and the acceleration curve load plate were obtained, and the simulation results and the theoretical results were consistent. Results contrast of different control algorithms proved that the dynamic performance under fuzzy PI control was better.Experimental research of dynamic response of globoidal indexing cam mechanism with steel ball was conducted. Main geometric parameters of globoidal indexing cam mechanism with steel ball were introduced; test experiments of natural frequency and dynamic characteristics of mechanism were conducted to obtain both the acceleration response of load plate at different input speed and the natural frequency of mechanism at different engaging positions, which provided experimental data for modifying dynamic model and verifying the theoretical results.The present study lays foundations for further research on globoidal indexing cam mechanism with steel ball, and provides reference for point engagement globoidal indexing cam mechanism. The research in this dissertation is helpful to realizing a high-quality performance of globoidal indexing cam mechanism.
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