How To Solve The Problem Of Drawing Of Modified Engineering Plastics In Injection Molding?
How to solve the problem of drawing of modified engineering plastics in injection molding?
In the process of injection molding production of modified engineering plastics, the temperature of the nozzle is too low, there is residual cold material, the pressure loss is large, and the surface of the product is prone to cold marks or stress marks, too high and easy to overflow, and there is drawing, modified engineering plastic injection molding. Common solutions for forming and drawing are:
(1) drop port temperature;
(2) increase the withdrawal position;
(3) reduce back pressure;
(4) use automatic seat retreat;
(5) add paper or metal sheet between the nozzle and the nozzle; --- In fact, it is to reduce the actual diameter of the nozzle;
(6) Add steel sheet to the Tsui ;
Analysis 1: There are two methods for back pumping---front pumping and back pumping; there are two control methods--time and position (some machines are controlled by front and rear sensors on the shooting platform, and most of them are still in control). Panel input) control; the majority of the front pumping is used when the holding pressure is particularly large. According to the characteristics of the force and the reaction force, when the external pressure (large holding pressure) is eliminated, the melt at the front end of the screw applies a large amount to the screw. The reaction force causes the screw to retreat, causing the screw to "offside" and the metering is inaccurate; the majority of the back pumping is to respond to the high-speed return, and is also afraid of the "offside" and the protection of the return oil seal (high-speed operation to sudden static, is very violation of mechanical conventions ).
Analysis 2: To understand the offside of the screw, it is necessary to know the process of retreating the screw melt. The screw retreat is completed under uniform cutting, compression, conveying and metering. If the material is not eaten or eaten, the actual amount cannot be obtained. However, the position is retreated to the corresponding amount. Then, the actual measurement and demand measurement will be different; in short, the so-called screw offside is that during the measurement process, the screw has no rotation measurement but a smooth back pumping. Distance, resulting in inaccurate measurement.