In the entire injection cycle, the cooling time accounts for the main part of the entire cycle. In the injection molding process, the temperature of the mold directly affects the weight and production efficiency of the injection molded product. In order to ensure product weight and production efficiency, the cooling system uses straight-through cooling, and has been simulated and verified through two schemes.4.1 Simulation of injection molding process:When some liquid flows, the viscous shear stress is proportional to the relative velocity between the two layers, ie:type; is the viscous shear stress of the fluid unit along the X direction; the proportionality coefficient ; A speed gradient. Fluidwith such flow characteristics is called Newtonian, such as water, solvent and some polymers. Conversely, those that do not meet the above characteristics become non-Newtonian. For example, most thermoplastic melts, except for a few such as vinylidene chloride and monovinyl chloride copolymers, are similar to Newton in vitro. Under certain conditions, the ratio of shear stress to shear rate of other plastic melts is not constant, that is, they are non-Newtonian. •Melt flow during injection molding is done on the basis of rheology. The basic equations of rheology include continuity equation, motion equation and energy equation.(1) Continuity equation: Thefluid motion follows the law of conservation of weight. If the fluid is incompressible, the weight flowing into the control body is equal to the weight flowing out of the control body. Take any point M (x, y, z) in the spatial flow field as the base point, and use rectangular voxels & x, & y, & z as the control volume, as shown in Figure 4-1. The velocity and density of the fluid are both functions of the Euler variables x, y, z, and t.