Study Of Design And Performance Of The Rotors' Curve Of Dry-running Twin-screw Vacuum Pumps

The oil-free twin-screw vacuum pump is a new kind of rotational positive displacement pump. The structure of the pump is simple and liquids or solids are hard to accumulate when sucked with gas or are condensed or solidified in the pump. It is outstanding for its excellent efficiency, high vacuum, exhausting to the air directly, a long life, good sucking, reliable work, convenient maintenance, favorable dynamical balance, light vibration, no pressure fluctuate and noise, work placidly with high speed, strong adaptability, multi-phase duties, no quiver, easy to continuous exhausting, etc. It is used widely in industrial territory of metallurgy, electron, chemistry, pharmacy, food and environment, and so on. At present, all over the world have been trying their best to develop oil-free vacuum pumps, but our country has been fallen behind other countries. Although the demand of the oil-free vacuum pumps has been experiencing a rapid growth, the products of many multinational companies talce up the major market share of dry compression vacuum pumps and high vacuum pumps. Therefore it is very significant to develop economical, feasible and reliable dry-running vacuum pumps by us. For the sake of requirements of developing and researching in our country, the paper investigates the meshing theory of twin-screw pump, buildup of the rotors' curve, and leaks, under the leadership of my teacher I worked out such as:The vacuum technology and status and development of the vacuum pumps, then the rise of the oil-free vacuum pumps, the appearance and development of oil-free twin-screw vacuum pump are showed in the first part of the paper; confirming the principle of the screw rotors curve' design according to the theory of screw design and vacuum equipments' requirements; analyze the require of the curve based on meshing theory and work methods of the twin-screw pumps, combine coiTelative theory of screw compressors and pumps, work out a type of curve which is able to obtain absolute sealing and compare with the MONO theory; require and performance of screw pumps as the base, analyze the capability of the curve, calculate performance parameters and list the whole process, explain the sealing principle; according to the thermo dynamical, conservation of mass, dynamical theory and mathematic equations, build conservation equations and leak model, afford theatrical foundation for the evaluation of pumps; model with the Pro/Engineering Wildfire and analyze the dynamic characteristic, validate the reliable of the screw rotors, and study the reasonable leak.