The injection device is a device that melts the resin material and injects it into the mould. As shown in the figure, the resin is squeezed into the barrel from the feed head, and the melt is conveyed to the front of the barrel by the rotation of the screw. In that process, under the action of heater, the resin material in the barrel is heated by heating. Under the action of shear stress of screw, the resin becomes melting state, which is equivalent to the moulding product and the main channel. The melting resin in the shunt channel is retained at the front of the barrel (called metering). The material is continuously injected into the mould by the screw. Cavity. When the molten resin flows in the mould, the screw's moving speed (ejection speed) must be controlled, and the pressure (holding pressure) must be used to control the resin when it fills the cavity. When the screw position and injection pressure reach a certain value, we can switch the speed control to the pressure control.

How to maintain injection moulds?

1. Processing enterprises should first equip each die with a resume card to record and count its use, nursing (lubrication, cleaning, rust prevention) and damage. According to this, we can find out which parts and components have been damaged and the extent of wear and tear, in order to provide information for finding and solving problems, as well as the forming process parameters of the die. The material used in the product can shorten the test run time of the die and improve the production efficiency.

2. Processing enterprises should test all kinds of properties of moulds under normal operation of injection moulding machines and moulds, and measure the size of the final moulded parts. Through these information, the existing state of moulds can be determined, and the damages of cavity, core, cooling system and parting surface can be found out. According to the information provided by the moulds, it can be done. Judge the damage status of the die and maintenance measures.

3. Important parts of the die should be tracked and inspected. The function of ejection and guide parts is to ensure the opening and closing movement of the die and ejection of the plastic parts. If any part of the die is blocked due to damage, it will lead to shutdown. Therefore, the lubrication of the ejector pin and guide pillar of the die should be maintained regularly (the most suitable lubricant should be selected) and checked regularly. Whether there is deformation or surface damage of pins and guide pillars should be replaced as soon as they are found; after a production cycle, professional anti-rust oil should be coated on the working surface, movement and guide parts of the die, especially the protection of the elastic strength of the bearing parts of the die with gears and racks and the spring die, so as to ensure the safety of the die. With the continuous production time, the cooling channel is easy to deposit scale, rust, silt and algae, which makes the section of cooling channel smaller and the cooling channel narrower, greatly reduces the heat exchange rate between coolant and die, and increases the production cost of enterprises. Therefore, attention should be paid to the cleaning of the cooling channel. For the hot runner die, the maintenance of heating and control system is helpful to prevent production failure, so it is particularly important. Therefore, at the end of each production cycle, the ohmmeter should be used to measure the belt heater, rod heater, heating probe and thermocouple on the die. If there is damage, it should be replaced in time, and compared with the die resume to make a good record so as to find the problem in time and take corresponding measures.

4. Attention should be paid to the surface maintenance of the die, which directly affects the surface quality of the product, with emphasis on the prevention of rust. Therefore, it is particularly important to select a suitable, high-quality and professional rust-proof oil. When the mold is finished, the residual injection moulding should be carefully removed by different methods according to different injection moulding. Copper rod, wire and professional mould cleaner can be used to remove the residual injection moulding and other deposits in the mold, and then air-dried. It is forbidden to clean hard objects such as iron wire and steel bar so as to avoid scratching the surface. If there are rust spots caused by corrosive injection moulding, grinding and polishing with a grinder, spraying professional rust-proof oil, and then storing the mould in a dry, cool, dust-free place.