When the PP bottle preform mold is produced by high-speed injection molding, how to ensure the temperature uniformity of the mold to improve the quality of the preform?
Publish Time: 2024-08-10
When the PP bottle preform mold is produced by high-speed injection molding, ensuring the temperature uniformity of the mold is crucial to improving the quality of the preform.
First of all, a reasonable heating system design is the basis. Advanced hot runner technology can be used to accurately control the temperature in the hot runner so that the molten PP material can maintain a suitable and uniform temperature before being injected into the mold cavity. For example, a hot runner system with multi-point temperature control is used, and temperature sensors and heating elements are set at different positions to monitor and adjust the temperature in real time to ensure that the material temperature fluctuation from the injection port to each cavity is within a small range. At the same time, for the heating of the mold itself, evenly distributed heating rods or heating coils can be used to quickly and evenly increase the mold surface temperature to the set value.
The optimization of the cooling system is also indispensable. In the high-speed injection molding process, rapid cooling is critical to the molding quality and production efficiency of the preform. Design a reasonable cooling waterway layout, such as using a waterway around the cavity, so that the cooling water can evenly take away the heat. By adjusting the flow rate and flow of cooling water, the cooling speed can be controlled to avoid local overcooling or overheating. For example, the cooling water flow rate can be appropriately reduced in the thicker parts of the preform, and the cooling time can be extended to ensure that the temperature drops evenly with the thinner parts, and prevent the internal stress caused by uneven cooling, which may cause the preform to deform or crack and other quality problems.
The material selection and processing accuracy of the mold will also affect the temperature uniformity. The selection of mold steel with good thermal conductivity can enable heat to be transferred more quickly and evenly. High-precision processing technology can ensure the dimensional accuracy and surface flatness of the mold cavity, and reduce the temperature unevenness caused by the structural differences of the mold itself. For example, the uneven roughness of the cavity surface may lead to different local heat dissipation speeds.
In addition, the adjustment of process parameters during the production process is also very important. Appropriately reduce the sudden change of injection speed to avoid local overheating caused by the high-speed impact of the material on the cavity. At the same time, according to different product requirements and the actual situation of the mold, reasonably adjust the parameters such as injection temperature and holding time to cooperate with the temperature uniformity control of the mold. In short, by comprehensively optimizing the heating system, cooling system, mold materials and process parameters, the temperature uniformity of the PP bottle preform mold during high-speed injection molding production can be effectively guaranteed, thereby improving the quality of the preform and the stability of production.
