Study On The Basic Theories Of Key Technology Of Two Helix Rotor

Helix rotor is the key component in screw vacuum pump or screw compressor. Two rotors driven by a pair of synchronous gears engage with each other during operation. It must be ensured that the tooth surface of two engaged rotors should not interfere and could form a mutually independent sealed volume in order to realize suction, compression and exhaust. Therefore, only these rotors can satisfy the requirements whose contact line’s projection of conjugate helical surface on the cross section of the screw is continuous and can separate adjacent spiral groove effectively. It is obvious that the design of molded line of two helix rotor is the research hotspot for screw vacuum pump and screw compressor.This paper focuses on two kinds of helix rotor, one is used in single thread and fixed pitch screw vacuum pump whose rotor consisted of common cycloid curve and involute, and another is used in screw compressor whose rotor consisted of unilateral asymmetric cycloid pin gear circular arc line. The theoratical study on the typical molded lines of these rotors including:1) design suitable molded lines for the spiral rotor, and verify the correctness of the molded lines.2) analyze the characteristics of the designed molded lines of the rotors, such as contact lines, leakage triangle, sealed volume between tooth, etc.3) deduce the equation of the contact line, calculate its length and the area of leakage triangle with the help of Matlab. A man-machine interactive interface under Matlab GUI is programmed so that any rotor’s geometry features can be calculated conveniently.4) verified by SolidWorks, the machinability of the designed screw rotor is simulated using UG software.5) carry on a dynamic balancing analysis to satisfy the requirement of screw rotor’s dynamic balance.6) analyze the characteristic of leakage and pressure within the sealed volume of two rotors based on fluid mechanics theory, calculate the relationship between clearance of the rotor and ultimate vacuum the pump can achieve. These work can provide a theoretical basis for the determination of pre-set clearance of screw pump or compressor.