The molding process of the screw barrel
is as follows: firstly, the granular or powdery plastic is added to the barrel, and the plastic is melted by the rotation of the screw and the heating of the outer wall of the barrel, and then the machine is clamped and the injection seat is moved forward to make the nozzle. Close to the gate of the mold, and then pass pressure oil to the injection cylinder to advance the screw, so that the melt is injected into the closed mold with a low temperature at a high pressure and a fast speed.
After a certain period of time and Pressure maintenance (also known as pressure holding), cooling to solidify and form, and then the mold can be opened to take out the product (the purpose of pressure holding is to prevent the backflow of the molten material in the mold cavity, replenish materials into the mold cavity, and ensure that the product has a certain density and dimensional tolerances). The basic requirements of injection molding are plasticizing, injection and molding. Plasticization is the premise to realize and ensure the quality of molded products, and in order to meet the requirements of molding, injection must ensure sufficient pressure and speed.
At the same time, due to the high injection pressure, a correspondingly high pressure is generated in the mold cavity (the average pressure in the mold cavity is generally between 20 and 45MPa), so there must be a sufficient clamping force. It can be seen that the injection device and the clamping device are the key components of the injection molding machine. The adjustment of the process in the production process of the screw and barrel is a necessary way to improve the quality and output of the product.
Since the injection molding cycle itself is very short, if the process conditions are not well mastered, there will be an endless stream of waste products. When adjusting the process, only change one condition at a time, and observe it several times. If the pressure, temperature and time are all adjusted together, it is easy to cause confusion and misunderstanding, and there is no reason for the problem. There are many measures and means to adjust the process of double alloy screw.