The threaded components are arranged in a building block style on the shaft and can be arranged and combined according to different requirements. There are three rows of pins installed on the inner liner, and the pins are divided into six types. The solid long pins are used to fix the inner liner sleeve and enhance the mixing effect; the hollow long pins are used to fix, mix, install the temperature measuring head, and inject liquid additives. The long flat-head pin fixes the inner liner; the flat-head pin is used to block the spare hole; the solid pin plays the role of mixing; the short solid pin crushes the material at the feed port.
As the screw reciprocates, the relative motion trajectory of the pin and each screw block forms a ∞ curve. When the kneading pin passes through the thread gap, axial material exchange occurs. During one revolution of the screw, the relative movement of the pin with the side of the screw shuttle causes shearing of the material, and at the same time, the screw and barrel are cleaned in the axial and radial directions. This is the basis for the thorough mixing, kneading, and self-cleaning action of a reciprocating compounding extruder.
These pins act like a series of agitators to redistribute the material. The interrupted threads cause the material to flow back, allowing the material to undergo a continuous process of shearing, orientation, cutting, folding, and stretching. Part of the melt is recombined, and part of the melt is further divided. In each L/D channel, the melt has to be divided four times. From this, we can see why the reciprocating extruder can operate within a very short aspect ratio. It achieves effective mixing of the melt, and the inner surface of the barrel is swept by thread elements. There are no dead ends in logistics. It has good self-cleaning ability, high conveying efficiency and stable and uniform material residence time.