How to deal with the expansion of hot runner system parts?
It is assumed that the value of A is much smaller than the lateral thermal expansion of the runner plate when planning. After the heating, the stop pin will inhibit the lateral extension of the runner plate, which will cause the warpage deformation of the runner plate, which will cause the seal between the runner plate and the nozzle to fail, resulting in failure. The melt leaks. The axial thermal expansion of the support ring 3, the runner plate 4, and the gate nozzle 5 will eliminate the cold space C. It is assumed that the cold space is too large, and the axial thermal expansion is short, and then the lateral thermal expansion of the warm runner plate is restrained, forming a melt leakage between the nozzle and the warm runner plate. Therefore, when planning the mold, the correct calculation system has a lot of thermal expansion, leaving a reasonable space for thermal expansion is a condition to avoid melt leakage. The thermal expansion of the components of the warm runner system causes the relative orientation changes between the mold parts of the equipment at room temperature. In order to compensate for the thermal expansion of the parts, it is necessary to leave a suitable expansion space. The warm runner plate is fixed on the fixed platen 8 through the intermediate positioning pin 2 and is extended to the vicinity after being heated.
The lateral thermal expansion of the warm runner plate will reduce the vacancy A of the runner plate and the positioning pin 7. When the needle is injected, the melt pressure will cause the nozzle 5 and the warm runner plate 4 to cause melt leakage. It is assumed that the cold space is too small and the system thermal expansion pressure is too large, which will cause system parts to twist and turn. Perhaps the compressive stress exceeds the yield stress of the fixed template part, and the support ring crushes the fixed template.