Wuhan Handern Injection Molding Principles and Features
DATE：2020/6/6 8:28:34 / READ： / SOURCE：This station
Wuhan Handern Injection Molding Principles and Features
One, the principle of injection molding
Injection molding refers to putting the raw materials for injection (generally granular plastic) in a heatable material and heating it. After compression molding, a screw is used to form a plunger to apply pressure, so that the melt is injected into the desired material through the nozzle at the end of the material Fill the mold cavity in the shape of the mold, lightly cool and set the mold, and then release the mold to obtain the product with the required shape. www.handern.com The process of breathable membrane equipment is usually achieved by injection molding machines and molds. We call plastics, injection molding machines and molds the three elements of injection molding, and we refer to molding pressure, molding temperature and molding cycle. Three principles for injection molding. In evaluating its importance, the former is 30% and the latter is 70%, which means that controlling process conditions is the most important. www.handern.com Breathable membrane equipment
The requirements for injection materials are able to melt and flow under the action of heat and pressure, because most of the thermoplastics and hot round plastics can be applied to the injection molding process. The injection molding of thermosetting plastics has been introduced in Chapter 8, Section 3, because this chapter only deals with the injection molding of thermosetting plastics. www.handern.com Breathable membrane equipment
1. Basic principles of injection molding
The operation of the injection machine is as follows: the resin is added to the hot material feed device. The plunger is equipped with a plunger driven by an injection cylinder to form a screw, which can send the material to the heating zone of the plunger, where the material is softened and heated to the required temperature. As the column or screw moves, the thermoplastic melt is injected into the closed mold under pressure. The injection molding system is fixed on the mounting template of the injection machine. The mold spreading system ensures the closing of the injection mold and provides the necessary mold clamping force of the injection machine. The injection machine is equipped with a time adjustment system that can control the operating procedures of the injection cycle. www.handern.com Breathable membrane equipment
2. Features of injection molding machine
At present, according to the structural characteristics of injection molding machines, they can generally be divided into plunger injection molding machines and screw injection molding machines. www.handern.com Breathable membrane equipment
The cycle of the screw injection molding machine starts from the closing of the injection mold, and then the mouth is tightly closed to the injection mold. Under the action of the pressure generated by the hydraulic cylinder, the screw is in the front position, and the end of the screw closes the nozzle. www.handern.com Breathable membrane equipment. Therefore, the plastic melt does not enter the mold cavity when the screw starts to rotate.
When the screw continues to rotate, the pressure in the front of the barrel rises, and the screw moves backwards against the pressure of the cylinder. After that, the nozzle hole opens and the melt enters the mold. After filling the mold, the pressure in front of the screw gradually exceeds the pressure of the cylinder, and the screw rotating in the feed moves backward. When the cylinder reaches the specified pressure, the screw stops rotating. www.handern.com Breathable membrane equipment Under the pressure of the cylinder, the screw works like a plunger, sending a small amount of body into the mold to compensate for the shrinkage of the thermoplastic. During the pressure holding period, the screw moves in the spray direction. At the end of the pressure holding, the end of the screw approaches the nozzle, and the nozzle hole is sealed. Like normal injection, the product is released from the mold after cooling.
One of the characteristics of screw injection is that the molding of the hot type material, the filling of the mold and the partial cooling of the product are performed simultaneously. www.handern.com Breathable membrane equipment The materialization is carried out between the barrel and the rod end solution (generally made into a spiral shape) and the material. A high shear stress can be generated in the gap of this cone before the mass nozzle, so as to ensure that the melt can be further homogenized and heated before entering the mold.
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