Study On Fundamental Theory Of Ausform Finishing Process For Hardened Gears

In this thesis, a new advanced technology, called ausform finishing, is first presented in our country for manufacturing hardened gears. Unlike other common gear machining process, ausform finishing integrates heat treatment and tooth profile machining press into one single manufacturing operation, which is beneficial to enhance productivity, obtain high machining accuracy and high performance of the gear.The project of this thesis is supported by the science and technology funds from Liaoning Education Department (serial number: 004402).At first, the developing trend of modern gear technology is analyzed, the present condition on gear manufacturing technology is stated, and the customary finishing methods for hardened gears are summarized. Then, necessity of applying ausform finishing process is demonstrated.On basis of its relative technology, it is demonstrated that ausform finishing process is possible in application. Then its technology principle is studied, its key technologies are put forward, and the rolling methods are analyzed and demonstrated.The application of ausforming principle in rolling process is an important problem studied in this thesis, which should be given consideration in order to achieve material characteristics required. After investigating the transformation rule of metal tissue during heat treatment, the optimum type of ausforming and its process parameters are chosen.A distinct feature of ausform finishing process is that the workpiece gear is in double-face engagement with dies without spacing. The process of double-face engagement is described in details in this thesis. The accurate model of changes of slide factor in both sides of the tooth on the condition of double-face engagement is established, and its influence on plastic deformation of the tooth surface is investigated. The model of position parameters of contact point under engagement is provided, too. Meanwhile,the basic double-face engagement equations are deduced.The value of tooth deformation is the key-influencing factor on machining accuracy of tooth profile. This thesis presents a summary of factors affecting tooth deformation. A single tooth is investigated on the hypothesis that the tooth body is a cantilever beam, and the deformation formulas of contact point are obtained considering both elastic and plastic deformation. And it is proved by numerically simulating calculation of the deformation through an example that the deformation theory is correct and reasonable.At last, the design of the prototype machine for ausform finishing process is carried out, and compensating measures of machining error are put forward. All of this shows that this new technology is correct in theory, and has potential advantages and wide applying future.