Research On Digital Design And Manufacturing Method For Beveloid Variable Ratio Tooth Profile Of Recirculating Ball Variable Ratio Steering Gear

Recirculating ball variable transmission ratio(referred to asvariable ratio)steering gear changes the transmission ratio by its involute beveloid gear's meshing with beveloid variable ratio tooth profile that is a kind of non-involute tooth profile difficult to describe with mathematical expressions.In order to solve the design and manufacturing problem of beveloid variable ratio tooth profile,a digital design method based on the meshing theory and a manufacturing method based on the forming principle for beveloid variable ratio tooth profile were presented in this thesis,and a virtual machining system was also developed.The main research work of this thesis includes:(1)Digital design method for beveloid variable ratio tooth profile of recirculating ball variable ratio steering gearThe segmentation method of beveloid variable ratio tooth profile based on envelope interval by analysis of its forming principle and the calculation method of beveloid variable ratio tooth profile point based on gear element method were proposed.And key technical problems such as establishing the coordinate system and its transformation,calculating the design parameters,and determining the envelope interval were solved.Besides,the mathematical model solving beveloid variable ratio tooth profile point was established,and the algorithms of calculating interval envelope and beveloid variable ratio tooth profile point cloud were designed respectively.(2)Research of manufacturing method for beveloid variable ratio tooth profile and development of virtual machining systemTaking the actual processing difficulty of beveloid variable ratio tooth profile as a starting point,the processing method of beveloid variable ratio tooth profile was put forward.The forming principle of beveloid variable ratio tooth profile was discussed,the machining tool processing beveloid variable ratio tooth profile was designed based on the forming tool of involute tooth profile and the calculating method of cutting dosage was presented by combining the actual manufacturing conditions with relevant standards of forming.On these bases,the parametric modeling system of cutting tool and the virtual machining system were developed by secondary development technology of CATIA.(3)Verification of digital design method and manufacturing method for beveloid variable ratio tooth profileBased on actual engineering requirements,the digital designing and virtual machining of a beveloid variable ratio tooth profile were carried out by methods proposed in this thesis.And taking theoretical transmission ratio curve as the verification goal,the meshing movement of involute beveloid gear tooth profile and beveloid variable ratio tooth profile was simulated to get the simulation transmission ratio curve by virtual prototyping technology.Through the comparison and analysis of the theoretical transmission ratio curve and the simulation transmission ratio curve,the validity of the digital design method and the processing method of beveloid variable ratio tooth profile are verified.This thesis takes beveloid variable ratio tooth profile as the research object and aims at solving its design and manufacturing problem.The proposed digital design method of beveloid variable ratio tooth profile will provide a new idea for design of non-involute tooth profile.At the same time,the research about processing principle of beveloid variable ratio tooth profile,cutting tool structure and cutting dosage will play a role in guiding the production of beveloid variable ratio tooth profile,thus promote the extension and application of recirculating ball variable ratio steering gear.