The auxiliary machines of the plastic extrusion unit in the injection molding plant mainly include setting out device, straightening device, preheating device, cooling device, traction device, meter counter, spark tester and take-up device. The purpose of extrusion unit is different, and the auxiliary equipment used for its selection is also different. For example, there are cutter, dryer, printing device, etc. The main types of straightening devices are: roller type (divided into horizontal type and vertical type); Pulley type (divided into single pulley and pulley block).

Winch type, which also plays a variety of roles such as driving, straightening and stabilizing tension; Roller type (divided into horizontal type and vertical type), etc. Straightening device: the most common type of plastic extrusion waste is eccentricity, and various types of bending of wire core is one of the important reasons for insulation eccentricity. During sheath extrusion, the scratch on the sheath surface is often caused by the bending of the cable core. Therefore, the straightening device in various extrusion units is essential.

In recent years, the main change of the clamping mechanism of hollow machine is to further develop in the direction of energy saving. The clamping mechanism shall have the properties of high motion precision, fast speed, large capacitance modulus and easy loading and unloading of molds. From the early four plate hydraulic direct acting type to the widely used four pull rod three plate linkage type and the more advanced oblique symmetrical two pull rod three plate linkage type.