During the grinding process of the screw air compressor machine tool system, the grinding wheel diameter is continuously reduced. When the reduction reaches a certain step distance $D, it means that the grinding error caused by the reduction of the grinding wheel diameter on the rotor tooth profile can no longer be ignored. At this time, the KWS control device will automatically detect the actual diameter of the grinding wheel and transmit the data to the configuration computer, which will recalculate the grinding wheel profile and diamond wheel data and feed it back to the KWS control device to control the CNC dresser to ensure the correct grinding wheel profile, thereby ensuring the machining accuracy of the rotor tooth surface. The rotor is detected through PNC, which can quickly detect the rotor lead error, tooth indexing error, helix parallelism error and rotor tooth profile error, etc. The accuracy level is 011Lm, and the detection results can be automatically printed out to display the machining accuracy of the rotor in a very intuitive form.
The tooth profile data of the yin and yang rotors during processing can be about the end face tooth profile or the axial section tooth profile, but the internal calculation of the system is based on the data of the axial section tooth profile. Therefore, when inputting tooth profile data, it should be distinguished whether it is end face tooth profile data or axial section tooth profile data to prompt the program whether conversion is required. When determining the number of points of each curve coordinate point in the tooth profile, the air compressor should follow the principle that the number of points of the curve segment with large curvature should be more and denser to ensure the processing accuracy of the tooth profile. The selection of the grinding wheel installation angle is very important. The selected grinding wheel installation angle should ensure that the grinding wheel profile can be smoothly connected, and the pressure angle of the grinding wheel profile should not be too small to avoid grinding difficulties. For asymmetric profile rotors, the tooth profile has front and rear edges. During grinding, the grinding wheel profile direction should be determined according to the rotation direction of the rotor tooth surface and the selected rotor clamping direction. If the grinding wheel profile direction is opposite to the direction required by the rotor tooth profile, the mirror function in the ROTOR software should be used to mirror the tooth profile data to obtain the correct grinding wheel profile. Since the diamond wheel cannot repair concave points on the grinding wheel, it is difficult to grind rotors with sharp points in the profile.
To ensure the machining accuracy of the curved section, the fillet radius of the diamond wheel should not be greater than half of the minimum fillet radius of the rotor end face tooth profile. Due to the large difference in the grinding state of each part of the tooth profile, the first piece of a batch of rotors often needs to be manually corrected on the diamond wheel (i.e., grinding wheel) after the first rough grinding of the teeth to compensate for the local out-of-tolerance defects of the tooth profile. After 12 corrections, the actual tooth profile that is very close to the theoretical tooth profile can generally be obtained. There are three methods for manual correction of tooth profile: linear correction, arc correction, and point-by-point correction. The correction method can be selected according to the actual situation of the tooth profile. Before the final fine grinding of the rotor, the grinding wheel should be trimmed for the last time, and then fine grinding and blanching should be performed on each tooth to improve the machining accuracy.