Dynamic And Thermal Characteristics Analysis And Experimental Study Of Hob Spindle System Of High-Speed Dry Hobbing

Sustainable development is particularly important for becoming the strong manufacturing country.Strengthening the research,development and promotion of environmentally friendly technology,process and equipment is the only way to speed up the green upgrade of China's manufacturing industry and achieve the sustainable development.At present,the main processing method of gear at home is still wet hobbing process,which consumes massive cutting oil and leads to problems such as environmental pollution of workshop and health hazard of operator.High-speed dry hobbing owns the advantages of high efficiency and green property for greatly improving the machining efficiency and completely eliminating cutting oil.In general,high-speed dry hobbing has been the development direction of gear hobbing.However,without the cooling and lubrication of cutting oil,and with the characteristics of larger spindle speeds and wider range of processing parameters,the dynamic and thermal characteristics of hob spindle system of high-speed dry hobbing is influenced,and thus affecting the working stability of machine tool,hobbing accuracy and hobbing cutter life.In this context,with the support of projects as National Natural Science Foundation of China(Grant No.51475058)and so on,research on the dynamic and thermal characteristics of hob spindle system of high-speed dry hobbing is carried out in this paper.Based on theoretical analysis,the finite element simulation analysis,optimization and a series validating experiments of the dynamic and thermal characteristics of hob spindle system have been conducted.These works would provide effective support for the study on issues such as structure optimization of hob spindle system of high-speed dry hobbing,process improvement and machining parameter optimization.Firstly,the modal analysis model and vibration response analysis model of hob spindle system of high-speed dry hobbing are established based on the vibration analysis theory.Heat transfer mechanism of hob spindle system is analyzed from these aspects as heat conduction and heat convection,and the thermal-structural coupling model is proposed.Above analysis would provide theoretical foundation for the study on the dynamic and thermal characteristics of hob spindle system of high-speed dry hobbing.Secondly,the cutting force is analyzed and calculated by the method of numerical simulation and related experiments,and the force load characteristics of hob spindle system are analyzed.The finite element model of hob spindle system is established based on ANSYS Workbench,and the natural frequencies and vibration modes are derived by modal analysis.The vibration response analysis of hob spindle system under cutting load with multi-parameter mixedly impacted is conducted via frequency bands-divided vibration harmonic response analysis method.Dynamic optimization of hob spindle system is carried out from these aspects as bearing stiffness and damping and processing parameter selection.Then,the thermal load characteristics of hob spindle system are analyzed mainly from the heat generated by high speed angular contact ball bearings and high-speed dry cutting process.The heat transfer and heat dissipation of hob spindle system are analyzed and thermal boundary conditions are determined based on the heat transfer mechanism.The finite element model of hob spindle system thermal analysis is established,and the thermal distribution and thermal-structural coupling results under the given condition of machining parameters are derived.Thermal optimization of hob spindle system is carried out from these aspects as change of spindle speeds and the flow or temperature of compressed air.Finally,an experiment platform is developed for carrying out the performance tests on the hob spindle system of high-speed dry hobbing.Include: 1)spindle tapping modal test;2)vibration response test of machining process under different machining parameters;3)temperature test of key components in machining process.The reliability of simulation analysis are verified by these experimental results.