Working principle of screw barrel

The working principle of screw barrel is based on the rotation of the screw in the barrel to achieve specific functions. Different types of screw barrels have different working principles due to different application scenarios, but generally they all involve the interaction between the screw and the barrel wall and the conveying, mixing, and compression of materials.

1. Take the common screw pump screw barrel as an example In the screw pump, the screw barrel plays the role of containing the screw and working with the screw. The middle screw is the active screw, which is driven by the prime mover to rotate, and the two sides are the driven screws, which rotate in the opposite direction with the active screw. Due to the mutual meshing of the screws and the close fit between the screw and the inner wall of the liner, the inlet and the outlet are divided into multiple sealed spaces. When the screw rotates, these sealed spaces are continuously formed at the suction end of the pump, sealing the liquid in the suction chamber, and continuously pushed to the discharge end along the axial direction of the screw, so that the liquid enclosed in each space is continuously discharged, just like the nut is continuously pushed forward when the thread rotates. Moreover, since the screw rotates at a constant speed, the liquid outflow rate is also relatively uniform. This working mode enables the screw pump to meet the working requirements such as conveying lubricating oil, fuel oil, various oils and high molecular polymers, and conveying viscous liquids, and has the advantages of small loss, good economic performance, high and uniform pressure, and can be directly connected to the prime mover.

2. The screw barrel principle of screw drilling tools The screw drilling tool is an energy conversion device that converts the pressure energy of the liquid into mechanical energy. When the high-pressure liquid enters the space inside the drilling tool containing the screw (the screw is located in the screw barrel), it forces the rotor in the screw to roll in the stator (the relevant structure of the inner wall of the barrel can be regarded as a part of the stator). For the screw drilling tool driven by the rotation of the motor, the torque and speed generated by the motor are transmitted to the drive shaft and the drill bit through the universal shaft to achieve the purpose of drilling. After the rotor and the stator are assembled, a series of continuous, conjugate, meshing sealed cavities will be formed along their contact points. Under the action of the liquid with pressure energy, as the sealed cavity is formed, changed and disappeared, the rotor will move continuously in the stator. The structure of the screw barrel (the part connected to the stator) and its matching mode with the screw (rotor) are crucial to the performance of the drilling tool. The appropriate screw barrel structure can ensure the efficiency and stability of torque transmission and ensure that it can work effectively in different drilling environments. For example, in horizontal wells, cluster wells and well repair operations, the economic benefits of drilling can be significantly improved. Behind these benefits, there are factors behind the role of the screw barrel.

3. Principle in screw extruder In the extrusion processing of polymer materials such as plastics or rubber, the principle of the screw barrel and the screw working together is similar. The external heating of the screw barrel conducts heat to the extruded raw material in the barrel. When the screw rotates and pushes the extruded raw material forward, due to the gradual reduction of the volume of the screw thread groove, the raw material is evenly mixed after being squeezed, flipped and sheared during the forward movement, and gradually softened into a molten state, completing the plasticization of materials such as plastics or rubber. In this process, the plasticization process, mixing degree and extrusion speed of the raw materials can be changed by controlling parameters such as the screw speed and the temperature of the barrel, and ultimately plastic products of various shapes or mixed and plasticized rubber products can be produced.