Injection system is one of the key subsystems of squeeze casting equipment. In the production process of squeeze casting, the metal melt is pressed into the mold cavity to complete filling under the action of injection punch, and solidified under the high pressure of injection punch. It can be seen that the injection system has a direct impact on the quality of squeeze, and its performance is directly related to the process performance of squeeze casting. The injection mechanism and docking structure are shown in the figure.
The injection system is mainly composed of transverse moving feeding mechanism, barrel (pressure chamber) and die docking mechanism and injection mechanism.
(1) Injection feeding mechanism: the power is provided by the lateral displacement oil cylinder, and the translational feeding and injection are adopted by the guide rail, and the translational feeding distance can reach 1m. Compared with other injection feeding devices using complex linkage mechanism to realize inclined pouring, the device has the advantages of simple structure, high reliability, stable operation, large pouring space, convenient operation and maintenance, and has been authorized by the national invention patent. The production efficiency and product quality of squeeze casting machine can be significantly improved by using the device.
(2) The docking structure of the pressure chamber and the die is as shown in the figure: the discharge cylinder (pressure chamber) is driven by the displacement oil cylinder to move out of the bed to receive the material. After receiving the material, the pressure chamber moves horizontally back to the centering position of the machine tool, and then the material cylinder (pressure chamber) is tightly butted with the vertically descending die gate sleeve through four guide rods and the injection hammer under the action of two docking oil cylinders. After the docking is completed, the docking is completed The cylinder maintains a certain pressure to make the connection tight. At the same time, the diagonal and transverse positioning cylinder pins on the machine tool extend to lock the pressure chamber and the die, so as to prevent the leakage of liquid metal from the contact surface between the pressure chamber and the gate sleeve during injection, so as to ensure the smooth progress of subsequent injection.
(3) The injection mechanism is shown in the figure: it is composed of injection cylinder, injection chamber and injection rod. The equipment adopts three-stage injection system with one-stage pressurization and two-stage injection speed. The slow and fast injection speed is controlled by Electro-hydraulic Directional Valve and cartridge valve respectively. The injection pressure is set by the pressure reducing valve, the pressurization ratio is 2.8 times, and the pressurization time is 0.02 ~ 0.04s. The injection chamber has the function of material cylinder, and the injection hammer has the function of ejecting the parts from the ejector bar. This clock has the composite function design, reliable structure, convenient and reasonable operation, and saves space. The material cylinder (pressure chamber) is equipped with a heating and insulating sleeve, and the resistance heating wire is evenly distributed inside. It has the function of pre heating (up to 550 ℃) and certain heat preservation.