Close the mold-high pressure and low speed mold clamping-move the needle seat forward-inject the melt material-hold pressure-enter the mold and cool the melt (the plasticizing screw is withdrawn with the needle seat and the screw rotates to plasticize the material) in this process. The molding melt is cooled and solidified, the mold is opened (the product is ejected at the same time), and the mold is closed (the next injection product cycle is initially produced).
The material for the plastic hollow board is added to the barrel of the injection molding machine from the hopper according to the amount of material used for forming the plastic product at a time, and the rolling screw pushes the material forward, and the material receives the heating from the outside of the barrel. Because the material in the barrel not only needs to be heated up, but also compressed due to the gradual reduction in the volume of the screw thread. In addition, the continuous rolling of the screw thread causes the material to move forward and the conflict between the material and the barrel. Conditional effect, the material is gradually plasticized into a molten state while being pushed forward. The melting material to the front end of the screw produces a reverse screw thread pushing pressure due to the resistance of the nozzle. As the screw pushes the melt forward to increase the amount of the melt, the melting material reverse pushing pressure also gradually increases. When it is greater than the thrust and conflict resistance of the cylinder piston to the screw (this resistance is the back pressure of the screw), the screw is initially withdrawn and the hopper is initially metered. The size of the screw evacuation distance is determined by the amount of injection material of the one-time molding injection product, and is controlled by the stroke limit switch adjusted before production. After the evacuated screw touches the travel switch, it stops rolling and evacuation, and ends a pre-plasticized material program.
After the pressure maintaining, cooling and shaping reach the preset time, the solid molding of the product is finished. The injection seat is pulled and evacuated by the cylinder piston, the second pre-plasticization of the preliminary screw, the forming mold is opened, the product is ejected out of the cavity, and the whole process of injection molding of the plastic hollow plate is ended.
After the clamping action is completed, the injection seat is pushed forward by the cylinder piston until the nozzle is close to the bushing port; then the injection cylinder piston pushes the screw to move forward quickly, according to the pressure and movement speed required for the melt to enter the forming mold , Inject the melt into the cavity of the forming mold. In order to avoid filling the molten material in the cavity of the molding die and replenish the shortened amount of the molten material before the melt is cooled and solidified in time, the nozzle after the injection is still close to the bushing mouth and maintains a certain pressure. This process is called Holding pressure, cooling and setting
