Created on:2021-11-24 10:06

Introduction and working principle of screw pump

Introduction and working principle of screw pump

(1) Introduction of screw pump

In recent years, the development and demand situation of domestic screw pump is good. In the past, domestic screw pump can only be used in more important industrial and military departments because of its great difficulty in manufacturing, high precision requirements, lack of relevant technical data and theoretical understanding, and high price. Due to its own advantages, screw pumps are preferred in various fields to transport various liquid media. Such as petrochemical industry, machinery manufacturing, shipping, beverage, food, textile industry, construction industry, environmental protection, etc. Because of its simple structure, high efficiency and energy saving, good white suction capacity, stable and continuous liquid delivery without stirring, long service life, convenient maintenance and operation, low vibration and noise, it is gradually recognized and selected by people, and its application field is becoming more and more extensive.

Due to the wide range of uses of screw pump and more and more types of media input, especially in the occasions of high temperature, high pressure, high viscosity, granular impurities or mixed oil and gas transportation, different considerations must be made in the structural design, profile combination, selection of main parts and materials, processing technology and heat treatment methods of screw pump according to different occasions, Especially in terms of model selection, screw pumps currently include single screw pump, twin screw pump (composed of various profile combination specifications, single suction and double suction structure), three screw pump (with single double suction structure) and five screw pump (with single double suction structure), otherwise the failure rate of screw pump will be increased due to unreasonable model selection.

(2) Working principle of screw pump

Screw pump is essentially an external meshing cycloidal gear pump. There can be 2 or 3 screws in the pump. Figure 3 24 shows the working principle of the three screw pump. Three mutually meshing double headed screws are installed in the shell, the driving screw 4 is a convex screw, and the driven screw 5 is a concave screw. The outer circle of the three screws keeps a good fit with the corresponding arc surface of the shell. In the cross section, their tooth profiles are composed of several pairs of cycloidal conjugate curves. The meshing line of the screw separates the spiral grooves of the driving screw and the driven screw into a plurality of mutually isolated sealed working cavities. With the rotation of the screw, these sealing working cavities are formed one by one at the left end, constantly moving from left to right (each sealing working cavity moves a screw lead every time the active screw rotates one cycle), and disappear at the right end. When the sealed working chamber is formed, its volume gradually increases to absorb oil; When it disappears, the volume decreases gradually, and the oil pressure is discharged. The larger the screw diameter of the screw pump, the deeper the spiral groove, and the greater the displacement; The longer the screw, the more sealing layers between the oil suction port and the oil pressure port, the better the sealing, and the higher the rated pressure of the pump.

Screw pump has the advantages of simple and compact structure, small volume, light weight, stable movement, uniform oil delivery, low noise, high speed, high volumetric efficiency (up to 90% ~ 95%), and is not sensitive to oil pollution. Therefore, it has been applied in the hydraulic system of some precision lathes. The main disadvantage of screw pump is that the screw shape is complex, the processing is difficult, and it is not easy to ensure the accuracy.

Home    Article    Introduction and working principle of screw pump