Research On Relife Grinding Method Of Large Spiral Groove Hob

Gear is an important part of most transmission systems,as an important tool for gear processing,hob manufacturing accuracy affects the transmission accuracy of gear to a certain extent,and then affects the transmission accuracy of mechanical transmission system.Relief grinding is an important process of hob finishing,which has a decisive impact on the accuracy of hob tooth profile.Therefore,it is important to improve the manufacturing accuracy of hob in the field of mechanical transmission.At present,disc grinding wheel is commonly used to relieve the hob in practical production,this method makes the profile of hob teeth deviate from the theoretical surface gradually,thus increasing the profile error and regrinding error;Existing research results show that disc grinding wheel relief grinding hob is also prone to interfere and cause damage to the next tooth rake face.The above problems are particularly prominent when relieving and grinding large spiral groove hobs,which become the bottleneck to improve the accuracy of hobs and need to be solved urgently.To solve this problem,a new method of relief grinding of hobs is proposed in this paper,in which finger grinding wheel is used instead of disc grinding wheel:1)Establishing the working coordinate system of finger grinding wheel according to the gear meshing principle and giving the coordinate transformation matrix between the coordinate systems and the normal vector of the tooth side contact surface;The calculating equation of grinding profile is established,and the corresponding grinding profile is solved by taking righthanded straight groove hob and right-handed spiral groove hob as examples.2)According to the actual relief grinding movement,a virtual machine tool for finger wheel relief grinding hob is established based on the simulation software VERICUT.The numerical control program is written for different types of hobs and the relief grinding process is simulated.3)The virtual machining accuracy based on VERICUT and the tooth profile errors at the representative positions of straight groove hob and spiral groove hob are analyzed.4)Aiming at the flaw of finger grinding wheel which is easy to wear,the profile of grinding wheel is optimized.The spiral groove hob model is simulated in VERICUT with the optimized grinding wheel as the tool,and the tooth profile error is analyzed.5)Based on the GUI module of MATLAB,a software for calculating the profile of finger grinding Archimedes hob is developed.The interface software realizes the functions of profile calculation and data preservation.Through simulation and error analysis,the relief grinding process of finger grinding wheel for straight groove hob can make the hob tooth profile accuracy reach AA grade in the range of qualified tooth length;The relief grinding of large spiral groove hobs(whose elevation angle is less than 24 degrees)keeps the tooth profile error within the A-level accuracy range and reaches AA-level within two-fifths of the tooth length.;Optimized finger grinding wheel relief grinding large spiral groove hob can make its tooth profile accuracy reach A level in the range of qualified tooth length;After optimization,the difference between the maximum and minimum radius of the sand profile in its axial direction decreases,so that the wear degree tends to be uniform.