Research On Hobbing Errors And Its Compensation Technique

Gear is a widely used element in manufacturing industry and plays a very important role in manufacturing. Hobbing is an important means for gear manufacturing. With the development of hobbing technology, high rigidity and precision is needed for hobbing machine and its process system, and therefore it makes sense to increase precision and diminish error of the machine. The errors of YKX3132G six axes hobbing machine are studied in the dissertation. An error model is proposed and errors caused by thermal- and force-induced deformation etc. are analyzed theoretically in detail. A complete experimental system is developed and a thermal error model for hobbing is built based on a series of tests.The factors effecting hobbing precision are analyzed systematically, including relative position and velocity variation between cutter and workpiece. A mathematical model of errors for six axes hobbing machine is built by coordinates transformation.Force-induced deformation and process system rigidity of YKX3132G six axes hobbing machine are studied in detail according to the characteristic and variation rule of cutting force in hobbing, and a theoretical formula for system rigidity is proposed.The error of cutter and workpiece caused by thermal-induced deformation and its compensating technique is studied systematically, including theoretical analyses for machine error, experiment setup, experimental study, data processing, system identification of thermal-induced deformation, and error compensation etc.Heat source of hobbing and method for thermal-induced deformation decrease are analyzed according to structural characteristic of hobbing machine, and its mathematical model for position and angle error between cutter and workpiece caused by thermal-induced deformation. Practical data processing is studied and data screening is focused. The use of neural network (NN), regression analyses etc. in gear manufacturing is explored. The system of thethermal-induced deformation of the hobbing machine is identified by combining stepwise regression and radial base neural network. It is applied successfully to error modeling for thermal-induced deformation and results in a good performance.Error compensating technique for the process system of hobbing is studied. Characteristic of hobbing error compensation is discussed. Error compensating techniques for geometric error and errors caused by thermal- and force-induced deformation are proposed according to their characteristic.