The injection device is a device for making the resin material melt into the mold after being heated and melted. The resin is squeezed into the cartridge from the material head, and the melt is transported to the front end of the barrel through the rotation of the screw. In that process, the resin material in the barrel is heated by heating under the action of the heater, and the resin becomes melted under the shear stress of the screw. The melted resin equivalent to the molding product and the main channel is retained at the front of the barrel (called metering), and the screw continuously injects the material into the die forward. Cavity.

When the molten resin flows in the mold, the moving speed of the screw (injection speed) must be controlled, and the pressure (retaining pressure) should be controlled after the resin fills the mold cavity. When the screw position and injection pressure reach a certain value, we can switch speed control into pressure control.