Correction and compensation of tooth forming shrinkage corresponding to the shape and size of the helical gear cavity

In the injection molding of precision small-module plastic helical gears, the molding shrinkage of the tooth shape is a key issue that affects the molding quality. Due to the particularity of the tooth profile structure of the helical gear (its molded parts shrink, especially the shrinkage of the helical tooth profile shows a non-uniform change). After the plastic helical gear injected into the mold is taken out and cooled, its shape may differ from the mold due to shrinkage. The inner cavity has a big difference. Therefore, injection molding numerical simulation technology can be used to analyze the melt filling, holding pressure, cooling, and shrinkage and warpage deformation of molded parts during injection molding of precision small modulus plastic helical gears. Make predictions to obtain the tooth-forming shrinkage characteristics; then through the analysis of the plastic helical gear injection molding shrinkage mechanism, shrinkage rules and shrinkage characteristics, a comprehensive estimate of the changes in the geometric dimensions of the plastic helical gear, and then derive the relevant calculation formula, and This is the basis for correcting and compensating the working size of the helical gear cavity, thereby effectively shortening the trial period and improving the mold design accuracy and injection molding quality of the plastic helical gear.