Fully-smooth screw rotor of twin-screw vacuum pump

Abstract

The invention discloses a fully-smooth screw rotor of a twin-screw vacuum pump, and belongs to the technical field of dry-process twin-screw vacuum pumps. An end surface molded line of the screw rotor consists of 7 sections of curves which are smoothly connected without cuspidal points; a circular-arc DE and an equidistant curve EF of a cycloid are used for smoothly connecting a tooth-crest circular arc CD with a tooth-root circular arc FG; a circular arc GA is adopted for smoothly connecting the tooth-root circular arc FG with a circle involute AB; an equidistant curve BC of the cycloid is used for smoothly connecting the circle involute AB with the tooth-crest circular arc CD; and two screw rotor end surface molded lines which are conjugated and engaged with each other are the same, so that correct engagement can be realized in work; and the screw rotor generated by the screw rotor end surface molded lines consists of 7 tooth surfaces, and all tooth surfaces of the screw rotor are in smooth transition for eliminating an area which easily generates stress focus. The screw rotor has the advantages of high strength, good tightness, small abrasion and a long service life.

Description

technical field [0001] The invention relates to a dry twin-screw vacuum pump, in particular to a fully smooth screw rotor suitable for the dry twin-screw vacuum pump. Background technique [0002] The dry twin-screw vacuum pump is a positive displacement vacuum pump, which forms a periodically changing working chamber volume between the two screw rotors and the inner cavity of the pump through the synchronous counter-rotating double-rotation motion of two screw rotors that can be meshed. Realize the suction, pressurization and discharge of gas, and form a vacuum at the inlet of the pump; the screw rotor is generated by the spiral expansion of the end surface of the screw rotor along the axial direction; therefore, the performance of the end surface of the screw rotor and the two screw rotors The conjugate meshing performance between the end surface profiles directly affects the performance of the twin-screw vacuum pump; therefore, the end surface profile of the screw rotor h...

AI Technical Summary

Problems solved by technology

[0004] In the profiled line of the above-mentioned screw rotor end surface, a long cycloid is used to connect the addendum arc and the dedendum arc, but the connection between the addendum arc and the long cycloid is not smooth, and there is a cusp; in theory, Points and cycloids can achieve correct meshing; however, the screw rotor end surface profile with sharp points has the following disadvantages: the sharp point of the screw rotor end surface profile leads to the generation of screw rotors with rough tooth surfaces, and the tooth surface is not smooth Stress concentration is easy to occur at the place, easily deformed and worn by the scouring of the fluid, the life of the screw rotor is low, the sealing performance is poor, and the gas leakage is large, which affects the ultimate vacuum degree and pumping speed of the twin-screw vacuum pump.

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