Active Precision Design Of Spiral Bevel Gear Milling Machine Tool

Spiral bevel gear is an important driving component in mechanical engineering. The structure and manufacturing adjustment of spiral bevel gear milling machine tool are complex, it is the typical representative of complex manufacturing equipment. Spiral bevel gear milling machine tool's precision directly influences spiral bevel gear's machining precision, and further influences the transmission performance and noise of the gear pair. Reasonable precision design is the key to influence the product's cost performance and obtain a successful design. The traditional precision design method is primarily to calculate the precision of every machine tool parts in the transmission chain based on the given precision of machine tool's terminal actuators, it is the precision design which is oriented to the manufacturing equipments, but it can't meet the machining precision requirement of the complicated space surface part similar to spiral bevel gear. Therefore, this paper explores the issues on spiral bevel gear milling machine tool's precision design from spiral bevel gear's precision requirement and machining mechanism, which aims to offer one feasible and effective solution on the problem of precision design of the NC spiral bevel gear milling machine tool, a typical representative of complex manufacturing equipment. The following contributions and main content have been made by this research:1. The spiral bevel gear's machining precision requirement-oriented active precision design method of spiral bevel gear milling machine tool is proposed. It designs spiral bevel gear milling machine tool's precision from spiral bevel gear's machining precision requirement and machining mechanism. The basic idea of this method is to establish the mapping relationship between the spiral bevel gear milling machine tool's motion error and spiral bevel gear's machining error, the error mapping modle, and then to establish the spiral bevel gear's machining precision modle based on the error mapping modle. Finally, transform spiral bevel gear's machining precision requirement to the motion precision of spiral bevel gear milling machine tool's axis of motion according to the machining precision modle.2. The machining model of the spiral bevel gear milling machine tool similar to Gleason Phoenix one is established based on analyzing the spiral bevel gear milling machine tool's structure and machining mechanism, and it is validated by virtual machining. 3. In order to obtain the coordinates of discrete points on spiral bevel gear's tooth surface used to establish the error mapping modle, the equation of spiral bevel gear's tooth surface and the coordinate calculation method of the discrete points on spiral bevel gear's tooth surface based on the rotational projection transformation are established with the method of space coordinate transformation and meshing theory. The equation and calculation method are validated by the three dimensional model of spiral bevel gear's tooth surface and the comparative analysis between the theoretical value and calculated value of the coordinates of discrete points on spiral bevel gear's tooth surface.4. The spiral bevel gear's tooth surface error model is established, based on analyzing the influencing factors and the influence characteristic of spiral bevel gear milling machine tool's motion error to spiral bevel gear's tooth surface machining error, choosing the circular pitch error as spiral bevel gear's machining error inspection item.5. The spiral bevel gear's machining precision modle is established based on the machining error mapping modle. Active precision design model of spiral bevel gear milling machine tool also is established with the accuracy distribution, machine tool precision reserve principle and sensitivity of spiral bevel gear's machining precision to the machine tool's kinematic precision by sensitivity analysis on the machining precision.6. The above result is applied to the precision design of YK2275 NC spiral bevel gear milling machine tool developed by Tianjin No.1 Machine Tool Works. And the design reference value of positioning accurcay of X, Y, Z axis and A, B rotation axis of YK2275 is determined as spiral bevel gear's machining precision grade is six.Although the research object of the active precision design method in this paper is spiral bevel gear milling machine tool, but as far as the design concept and principle are concerned, the method is universal and also is applicable to the other manufacturing equipment's precision design based on the complicated machining mechanism.