Key Technology Of Screw Compressor Rotor’s Tooth Profile’s Grinding

Screw compressor has been widely applied in many industrial fields because of its great high speed performance, excellent multiphase transportability, stable exhaust performance and easy operability. As the core part of compressor, screw rotor’s manufacture is complicated because the rotor’s structural parameters are complex and diversified, its helical surface is hard to process and its manufacturing accuracy can’t be guaranteed. Therefore the research for the technology of screw rotor that relates to the forming principle and sophisticated manufacturing has always been an important topic of the industrial development. With the development of the closer combination of Computer Science and Mechanical Engineering Science, and the great progress of the Modern Manufacturing Technology, a large number of specific CNC machines and relevant auxiliary software have emerged, but the core technologies are still possessed by foreigners. Although Chinese researchers have made a great progress in the manufacturing of screw rotor, there is still a big gap between our technology and the other sophisticated world-leading technology, which are mainly showed in the following aspects:manufacturing inefficiency, low accuracy and less stable quality.Under this background, this thesis will study the key technology of screw compressor rotor’s tooth profile’s grinding, aiming at efficiently and accurately manufacturing the screw rotor of high-precision, abnormity and complexity. The main contents these papers discuss are as follows:1. Upon the forming principle of the helical surface, the condition equation of contact line between helical surface and form grinding wheel has been established. On the basis of numerical analysis on the rotor’s form line, accumulated chord length parameter cubic spline has been applied to calculate the first derivative of data points of screw rotor’s sectional profile, and has solved the problem of some data points’ large deflection in the rectangular coordinate system.2. The mathematical model of form grinding wheel’s edge has been derived. Numerical analysis has been applied to the rotor’s sectional profile and forming wheel’s axis profile, and the forming wheel’s profile has been evaluated and optimized through the2D and3D interference between rotor and grinding wheel.3. After analyzing the milling and grinding process of screw rotor’s tooth profile, some rotor’s tooth profile errors after machining has been discussed and relevant solutions to improve the manufacturing accuracy has been proposed. A specific profile error compensation technology has been put forward which has been proved to be reliable and easily operated by the practice of actually manufacturing, then the technology has been extensively applied to the adjustment of original profile of screw rotor to modify the design flaws and origin measurement errors of screw rotor’s tooth profile, and thus the overall performance of screw compressor has been improved.4. This paper has developed a set of software to calculate the forming cutter’s profile and generate the G-code for forming grinding wheel’s dress. At last, we have simulated the rotor’s manufacturing process with the help of CAD/CAM technology and done lots of field test of rotor’s machining, and the result shows that the forming cutter’s profile and the theory these papers proposed are right.