Guide rod: the basics of screw assembly

Guide rod: Basic knowledge of screw combination:

Conveying element

The conveying element is threaded and its function is to convey material (including liquid material). The shape of the spiral groove can be rectangular or special shapes produced according to the principle of relative movement (meshing type). Threaded components are divided into two types: forward and reverse, which can be divided into single-head, double-head and three-head threaded components.

Single thread element

It has an efficient solid conveying capacity and is usually used in the feed section to improve the extrusion volume limited by the feed volume and to convey materials with poor fluidity (such as low density materials). It is usually used to transport materials with particle sizes similar to water during the reaction process, and can also be used in the unloading section. The output capacity of a single-threaded thread is greater than the output capacity of a multi-threaded thread, and the torque is also greater than the output capacity of a multi-threaded thread, and its mixing characteristics are greater than the mixing characteristics of a multi-threaded thread.

Double-head thread compared to three-head thread

With the same central moment,D / D. It is relatively large and the groove depth is deeper, so under the same screw speed, it can provide a lower shear rate and is more suitable for processing powder materials, especially low-dispersion powder, glass fiber and other shear-sensitive materials. Compared with the three-thread assembly, under the same shear stress and torque, the two-thread assembly can work at a higher speed and have a higher production rate. At the same screw speed, the three-thread element can exert higher average shear rate and shear force on the material. In addition, due to the shallow thread groove, the material layer becomes thinner, and the heat transfer performance of the three-thread component is better than that of the double thread. The material is plasticized and melted. However, due to strong shear force, it is usually not easy to process shear-sensitive materials, such as glass fiber andPVC.

lead variation and characteristics:

InScrewIn combination, for output-oriented occasions, the choice of a larger lead thread helps to increase the output. For the extrusion of heat-sensitive polymers, the choice of larger lead can shorten the residence time of the material and reduce the thermal degradation of the material. Threaded leads have a great influence on the amount of extrusion, mixing characteristics and torque. Generally speaking, as the thread lead increases, the extrusion amount of the screw increases, the residence time of the material decreases, and the mixing effect of the material is relatively reduced, and the torque also becomes smaller. For mixed occasions, the middle lead thread is selected. For the thread of the screw in different working areas, the lead is gradually reduced. It is mainly used for the output and pressurization of solid materials to increase the melting speed or mixture. Speed and extrusion stability.