"Asia Rubber Expo & India Rubber Technology Exhibition 2020" is jointly sponsored by Aakar Exhibition Company and Zhonglian Rubber Co., Ltd. The exhibition will be held at the Chennai Trade Center...Read More
The rotary motion is produced by the friction between the rubber material and the screw. Due to the large friction force between the barrel wall and the rubber material, it cannot rotate with the screw at the same time. Therefore, there is a forward axis during the rotary motion. to move. The fluid-like rotary motion and the solid axial motion of the rubber material behave differently at different parts of the screw. For the convenience of analysis, the working parts of the screw can be divided into feeding section, compression section and extrusion section.
The rubber material is fed from the feeding port, and the rubber material is initially heated while pushing the rubber material to the compression section. This section starts from the feeding port and ends when the plastic material begins to plasticize, which is the solid conveying stage.
1. Feeding section
The strip rubber is supplied from the feeding port. Due to the pushing and shearing action of the rotating screw, the rubber forms a relative movement between the screw grooves, and continuously forms large and small rubber groups at the feeding port, and along the screw thread. The space of the groove rotates and continuously advances to the compression section.
2. Compression section
The function of this section is to accept the loose micelles conveyed from the feeding section, compact them and further heat and plasticize them, and at the same time squeeze out the air contained in the rubber material to the feeding section, so that the micelles are bonded to each other. At this time, the rubber material changes from partial plasticization to full plasticization, and gradually forms a continuous viscous fluid. Therefore, this section is also called the plasticizing section (or phase migration section). In the compression section, the rubber material is not only gradually compressed and the density increases, but also gradually fills the entire screw groove, and the rubber material in a viscous flow state is further pushed forward to the extrusion section under the rotation of the screw.
3. Extrusion section
The function of the extrusion section is to further plasticize the viscous rubber material evenly, pressurize and stir it, and transport it to the head and die for extrusion (the extrusion section is also called the homogenization section). In the extrusion section, the screw groove is filled with the rubber in a flowing state, and two kinds of forces are generated: one is the force generated by the rotation of the screw, so that the rubber is pushed forward along the screw groove; the other is the hydrostatic pressure This is caused by the fact that the rubber material is hindered by the head and mouth shape in front of the extrusion section, and a large amount of stagnation is generated at the head. This pressure has actually been generated from the feeding port, but only changes in the extrusion section. It's just very big (it appears at the nose).