Screw conveyor is divided into two types: horizontal screw conveyor and vertical screw conveyor, which are mainly used for horizontal conveying and vertical lifting of various loose materials such as powder, granular and small pieces. The screw conveyor is characterized by simple structure, small cross-sectional size, good sealing and reliable operation, which is convenient for intermediate loading and unloading. The conveying direction can be reversed, or it can be conveyed in two opposite directions at the same time.