Force state of the injection molding machine screw

Update:27-07-2018
Summary:

The injection molding machine injects molten plastic in […]

The injection molding machine injects molten plastic into the mold and cools it into a product. It is very versatile and varies from plastic to plastic. The injection molding machine is the most used processing machine in the plastics processing industry. Not only is there a large number of products that can be directly produced by injection molding machines, but it is also a key device that constitutes the injection-blowing process. What is the force and strength of the screw of the injection molding machine? The screw injection molding machine consists of four parts: injection unit, clamping unit, hydraulic transmission and electrical control system.

The injection device is composed of a barrel, an injection molding machine screw, a nozzle, a hopper, a metering device, a screw transmission device, an injection molding cylinder, and an injection base moving cylinder. Its main function is to melt and plasticize the plastic evenly, and then inject a certain amount of molten material into the injection mold under a certain pressure and temperature. The clamping device, also known as the clamping device. It consists of a clamping cylinder, a moving die plate, a fixed plate, a clamping mechanism, a tie rod, and a safety gate of the demoulding device. Its main function is to ensure that the mold opens and closes according to the specified procedure and speed, and that there is sufficient clamping force to close the mold tightly. The clamping device is divided into three categories: hydraulic, mechanical and hydraulic/mechanical hybrid. The hydraulic drive and electrical control system ensure that the injection molding machine operates accurately according to the pressure, speed, temperature and time specified in the injection molding process. The hydraulic transmission system consists of a power oil pump, a directional valve, a throttle valve, a pressure valve and a fuel tank. The electrical control system consists of systems such as power control, motion process control and heating control. The injection molding machine injects molten plastic into the mold and cools it into a product. It is very versatile and varies from plastic to plastic. The injection molding machine is the most used processing machine in the plastics processing industry. Not only is there a large number of products that can be directly produced by injection molding machines, but it is also a key device that constitutes the injection-blowing process. What is the force and strength of the screw of the injection molding machine? When the screw of the injection molding machine and the main shaft of the reduction box are matched with a long cylindrical surface, the screw of the injection molding machine can be used as a cantilever beam fixed at one end.

The force state of the injection molding machine screw during the extrusion process can simplify the screw stress: self-weight G; the torque M required to overcome the material resistance; the axial force P generated by the material pressure. The screw is generally worn due to long-term wear, and the gap between the screw and the barrel is too large to be properly extruded and scrapped, but there are also examples in which the working stress generated by improper design or operation exceeds the strength limit. Therefore, the screw should also meet certain strength requirements. The dangerous section of the screw of the injection molding machine is generally at the minimum of the root diameter of the feeding section. For the case where the screw tail is floatingly coupled with the main shaft of the reduction gearbox, since the screw of the injection molding machine floats in the cylinder, the bending stress caused by the self-weight of the screw is equal to zero, so it is calculated only by the compressive stress and shear stress of the screw. Since the bending stress caused by the screw's own weight is small (the material around the screw is filled with material), even in the former case, it can be omitted, so the two methods are actually the same. There is also a simple twist to estimate the screw diameter.