Mold structure design for injection blow molding of plastic packaging bottles

Mold structure design for injection blow molding of plastic packaging bottles

In recent years, the demand for plastic packaging containers for pharmaceutical products and cosmetics has increased day by day, and the number of plastic packaging container forming equipment has also continued to grow. Medicinal plastic bottles and cosmetic packaging bottles have the advantages of light weight, no damage, hygienic and other advantages, and meet the special requirements of pharmaceutical packaging. Injection blow molding (referred to as injection blow molding) is a molding method that combines injection molding and blow molding to produce hollow products.

Since the injection blow molding equipment first injects the bottle mouth during operation to ensure the accuracy of the bottle mouth, and then blows the bottle body, it can prevent the gas in the container from volatilizing and the external gas from penetrating into the bottle, thus ensuring the bottle mouth. It has good sealing performance with the bottle cap.

For medical plastic packaging bottles, the sealing degree of the bottle mouth directly affects the food safety of the medicine. The injection blow molding method can ensure high dimensional accuracy of the bottle mouth and thread, good appearance dimensional accuracy, uniform bottle wall thickness, and good air tightness. , to adapt to the special requirements of pharmaceutical packaging, so the injection blow molding method is used to produce high-quality pharmaceutical plastic bottles.

This article studies the structural design of a one-step single-station injection blow mold. This mold can enable ordinary injection molding machines to complete the production of plastic hollow products in one go. It has the advantages of energy saving, low investment, low risk, high quality and high efficiency, and has good practical applications. value.

1 Injection blow molding plastic bottle process flow

The processing process of injection-blown hollow containers includes two processing stages: injection and blow molding. The injection stage consists of the following processes: injection molding machine mold closing, parison injection and mold opening. The blow molding stage consists of the following processes: closing of the blow molding module, blow molding, opening of the blow molding module, ejection of pre-molded and hollow-formed containers. From the closing of the blow molding mold to the opening of the blow molding mold, plasticization is carried out by the screw of the injection molding machine.

2 Injection blow mold structural design

The integral mold for the one-step single-station injection blow molding of hollow containers is directly used on an ordinary injection molding machine to complete the injection blow molding function in one go. Injection blown plastic hollow container molds are mainly composed of injection and blow molding structures combined into one.

In the injection stage and the blow molding stage, after the mold is opened, the molding mandrel is always fixed in the movable mold and does not move. The injection blank adheres to the mandrel. After the mold is fully opened, the blow molding module is closed and begins execution. When the blow molding module After it is completely closed, the inside of the mandrel is stretched and blown to complete the blow molding of the hollow container. In the injection stage, between injection and mold opening, only the injection blank is formed, without pressure holding and cooling and shaping. At this time, the injection molding machine is in the mold closing state. In the blow molding stage, the closing, blow molding and opening and ejection of the blow molding module are all completed on the same mold. The key technology in the mold injection blowing process is to control the molding temperature of the preform cavity and maintain uniform temperature at the top and bottom of the preform cavity.

3 Conclusion

The one-step single-station injection blow mold is used to produce pharmaceutical plastic packaging bottles. During the operation of the molding equipment, the bottle mouth is first injected to ensure the accuracy of the bottle mouth and prevent the gas in the container from evaporating and external gas from penetrating into the bottle. , thus ensuring good sealing performance between the bottle mouth and the bottle cap, and the molding mandrel is fixed, and the bottle body is evenly blown, adapting to the special requirements of pharmaceutical packaging.

Compared with the existing one-step multi-station injection blowing method to produce medicinal plastic packaging bottles, this method does not require special equipment and has a simple mold structure; different types of ordinary injection molding machines can be used to produce various medicinal packaging bottles of different volumes. It is suitable for the production of multiple specifications and varieties; it requires less investment, saves a lot of foreign exchange investment funds, and is suitable for production by small and medium-sized enterprises; in actual production, the production workshop space occupancy rate is small; the variety development is fast and the investment risk is small, so it is very competitive.