Three screw pump is the use of screw rotation to suction and discharge liquid. The middle of the screw for the active screw, driven by the prime mover rotation, the screw on both sides of the driven screw, with the active screw for reverse rotation. The main, driven screw thread are double-headed thread. Due to the mutual engagement of the screws and the tight fit of the screw with the inner wall of the liner, one or more sealed spaces are separated between the suction and discharge of the pump. As the screw is rotated and engaged, these sealed spaces are constantly formed at the suction side of the pump, the liquid in the suction chamber is enclosed therein and continuously displaced in the axial direction of the screw from the suction chamber to the discharge end, to be enclosed in the spaces Continued discharge of liquid, like a nut in the screw rotation is continuously pushed forward the case, that is the basic working principle of three screw pump. The sealing surface between the screw and the housing is a curved surface. There are unsealed areas such as ab or de on this surface and a number of triangular notches abc, def with the groove portion of the screw. The notches of these triangles form a passage for the liquid, allowing the drive screw groove A to communicate with the grooves B, C in the driven screw. The grooves B, C, along with their spiral around the back, respectively, and the back of the grooves D, E communicated. Since there is also a triangular notch a "" b "" c "" similar to the front surface on the sealing surface where the grooves D, E engage with the groove F (which belongs to the other thread), D, F, E will also be connected. In this way, the groove ABCDEA also form a ∞-shaped sealing space (such as the use of single-head thread, the groove will be along the axial disc Rao screw, the suction port through, can not form a seal). Not hard to imagine, in such a screw, will form a number of independent ∞-shaped seal space, seal space occupied by each axial length just equal to the lead t of the tired rod. Therefore, in order to make the suction and discharge of the screw, the length of the screw thread should be longer than one lead. It can be seen from the above principle, three screw pump has the following advantages: 1) wide range of pressure and flow. A pressure of about 3.4-340 kgf / cm 2, a flow rate of up to 18,600 cm 3 / min; 2) a wide range of types and viscosities for transporting the liquid; and 3) a high rotational speed ; 4) good suction performance, self-priming capability; 5) uniform flow rate, low vibration, low noise; 6) compared with other rotary pumps, the gas and dirt into the less sensitive; 7) solid structure, installation Easy to maintain. The disadvantage of the three screw pump is that the screw machining and assembly requirements are higher; the performance of the pump is sensitive to changes in the viscosity of the liquid. (B) the working principle Three screw pump is a positive displacement pump, the main components are the rotor and stator, the rotor is a large gear teeth large and small spiral inner screw (rotor) stator is a matching double-headed spiral And the sleeve, thus forming a space between the rotor and the stator to store the medium, and the medium is axially moved from the suction end to the discharge direction when the rotor runs in the stator. (C) Features ★ Helical seal line between the stator and the rotor completely separates the income chamber from the discharge chamber, so that the pump has the function of the valve. ★ It can realize the multiphase mixing of liquid, gas and solid. Change, there is no Swiss flow agitation and pulse ★ elastic stator cavity volume can effectively reduce the transmission of solid particles containing medium wear ★ input medium viscosity up to 50000Mpa · s solid content of up to 50% ★ flow and speed proportional , With the governor can achieve the amount of automatic adjustment pump can be transported forward and reverse. Three-screw pump has the following advantages: 1, compared with the centrifugal pump without the installation of three-screw pump flow is a stable linear flow 2, and the three-screw pump piston pump with self-absorption ability, high suction height 3, and Compared to the three screw pump diaphragm pump can deliver a variety of mixed impurities containing gas and solid particles or fibers of the medium, but also can convey a variety of corrosive substances 4, compared with the gear, the three screw pump can deliver high viscosity material 5, and Piston pump, diaphragm pump and gear pump is different, three screw pump can be used for filling and metering