The plastic molding machine uses the thrust of the screw (or plunger) to inject the plasticized plastic in the molten state (that is, the viscous fluid state) into the closed mold cavity, and the process of obtaining the product after solidification and shaping.
Injection molding is a cyclic process, each cycle mainly includes: quantitative feeding-melting and plasticizing-pressure injection-filling and cooling-mold opening and taking parts. After taking out the plastic part, the mold is closed again for the next cycle.
1. Locking the mold: The mold board quickly approaches the fixed mold board (including slow-fast-slow speed), and after confirming that there is no foreign matter, the system is turned to high pressure, and the template is locked (maintaining the pressure in the cylinder).
2. The shooting table moves forward to the position: the shooting table advances to the specified position (the nozzle is close to the mold).
3. Plastic injection: The screw can be set to inject the molten material at the front end of the barrel into the mold cavity at multiple speeds, pressures and strokes.
4. Cooling and pressure keeping: According to the setting of various pressures and time periods, the pressure of the barrel is maintained, and the mold cavity is cooled and formed.
5. Cooling and pre-molding: The products in the mold cavity continue to cool, while the hydraulic motor drives the screw to rotate to push the plastic particles forward. The screw retreats under the control of the set back pressure. When the screw retreats to the predetermined position, the screw stops rotating and injects The oil cylinder is released according to the setting, and the expectation is over.
6. The shooting table retreats: After the pre-plasticizing, the shooting table retreats to the designated position.
7. Die opening: the die plate moves back to the original position (including slow-fast-slow speed).
8. Ejection: The thimble ejects the product. The basic requirements of injection molding are plasticization, injection and molding. Plasticization is a prerequisite for realizing and ensuring 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 cavity (the average pressure in the cavity is generally between 20 and 45 MPa), 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.