Research On The Dynamic Analysis For Cam And Crank Of Spindle-type Cotton Picker

With the gradual establishment and continuous development of the Xinjiang cotton industry advantage, mechanized harvesting cotton is an important part of the whole mechanization of cotton production, which must be break. At present, the china domestic cotton picker has to fill the gaps and began mass production, but the core technology is still the monopoly by foreign, the domestic cotton picker in Xinjiang possession gradually decline. Therefore, accelerating the pace of research and localization of the domestic cotton picker, which is a positive role to improve the efficiency and performance reliability of the domestic cotton picker.The spindle or intermediate shaft fracture of domestic cotton picker is caused by working performance instability, and the working state of the cam and crank mechanism is the main cause of this problem.Cam is the main working parts of cam and crank mechanism, its significant influence on the working state of the cam structure, therefore, optimization of the cam structure is particularly important. Research on vibration modes and transient analysis of cam mechanism under working the conditions, can understand the structure of vibration-sensitive feature. Using the method of combining experimental modal and the finite element modal analysis technology n this paper, study the characteristic of structural natural vibration; the cam structure sensitive areas is obtained by transient analysis. Research results provide the basic data for the cam structure optimization and experimental studies, and has a certain theoretical and practical value. The main content of topic research is as follows:(1) Analysis of the structure characteristics and operating conditions of the cotton picker cam mechanism; connecting the cam profile360points is used by spline curve order, and through isometric entity, stretching, remove command to establish3d entity model by three-dimensional design software SolidWorks; complete cam finite element model by the finite element software Ansys Workbench, and calculation of cam free modal and constrained modal analysis in the Modal module, respectively extracted first six order modal frequency and modal vibration mode, and analyze cam modal vibration mode change in the two boundary conditions, the free modal main vibration form:the overall bending deformation、expansion-shrinkage determination、bending and torsional combination deformation. In the approximation of the actual working state constraints modal main vibration form:the local bending deformation expansion-shrinkage and bending deformation combination. (2) Using experimental modal analysis theory and parameter identification method, using INV306intelligent signal acquisition and processing analysis system developed by Beijing Orient Vibration And Noise Technology Research Institute. The test is adopts the simple and practical, widely used hammer-hitting method, and using the Beijing Oriental independent research and development variable time base sampling technology, for the cam parts axial and radial tests.After a number of pre-test to determine the basic parameters of the test, ultimately get satisfaction experimental modal data, compared with the finite element modal results indicate:each order modal vibration mode is almost the same and the modal frequency relative error is within7%, the maximum relative error of6.34%in the fifth-order, the minimum relative error of3.23%in the fourth-order; determine the accuracy of the finite element model and can be used for the cam mechanism subsequent parameters optimization.(4) The transient dynamic analysis of cam mechanism is conducted by Ansys Workbench Transient Structural module. the cam part’s equivalent stress、strain and displacement ect parameters changing with time curve is obtained in a cam mechanism work cycle, and extracting the cam part’s equivalent stress curve in the doff cotton region、 damping region and working region and its region’s largest equivalent stress nephogram. the maximum theoretical equivalent stress appears in the work area, which is30.15MPa, and strain variation is3.6095e-4mm/mm.