Totally-smooth screw rotor

Abstract

The invention discloses a totally-smooth screw rotor, and belongs to the technical field of dry type double-screw vacuum pumps. The molded lines of the end face of the screw rotor are composed of seven sections of curves, the adjacent curves are totally in smooth connection, and sharp points do not exist. A tooth crest arc CD and a tooth root arc FG are in smooth connection through a section of arc DE and a section of cycloid equal-distance curve EF which are engaged in a conjugate manner, the tooth root arc FG and a circle involute AB are in smooth connection through a cycloid equal-distance curve GA, and the circle involute AB and the tooth crest arc CD are in smooth connection through an arc BC. During work, the molded lines of the end faces of two screw rotors are the same and can be in accurate engagement. The screw rotor spirally unfolded in the axial direction from the molded lines of the end face of the screw rotor is composed of seven tooth faces, all tooth faces of the screw rotor are in smooth transition, and the area where stress concentration is likely to happen is eliminated. The screw rotor has the beneficial effects of being high in strength, good in sealing performance, small in abrasion and long in 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 profile of the screw rotor along the axial direction; therefore, the end surface profile of the screw rotor and its conjugate meshing performance directly affect The sealing performance, efficiency and area utilization factor of the twin-screw vacuum pump. [0003] The commonly used screw rotor end surface profile is a ...

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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