1. Setting of venting grooves
In the venting design of Beverage bottle preform mold, venting grooves are a common way to achieve this. Venting grooves are usually set on the parting surface of the mold, because the parting surface is the end of the plastic melt flow, and air tends to gather here. The depth of the venting groove is generally shallow, which is to prevent the plastic melt from overflowing while allowing air to be discharged. For example, for common PET preform molds, the depth of the venting groove may be between 0.02 and 0.05 mm. Its width depends on the size of the mold and the size of the preform, generally around a few millimeters. By reasonably designing the length, width and depth of the venting groove, the air in the cavity can be effectively discharged, ensuring that the plastic melt can evenly fill the cavity, thereby improving the molding quality of the preform.
2. Application of breathable steel materials
Breathable steel is a special material that is also widely used in the venting design of Beverage bottle preform mold. The breathable steel material has many tiny pores inside, which are interconnected to form an air channel. When the mold uses breathable steel to make part of the cavity or core, the air in the cavity can be discharged through these pores. In practical applications, the permeability of breathable steel can be adjusted as needed, for example, by changing its porosity to adapt to different preform molding requirements. Moreover, while ensuring the exhaust function, the breathable steel material also has a certain strength and wear resistance, which can meet the use requirements of the preform mold in the injection molding process.
3. Exhaust through the gap of the mold structure
The structure of the beverage bottle preform mold itself can also provide a way to exhaust. For example, at the matching gap between the core and the cavity, although this gap is very small, it can still be used as a channel for air exhaust. When designing the mold, it is necessary to accurately control the size of this gap to ensure that the air can be discharged smoothly and to prevent the plastic melt from seeping out of the gap. Generally speaking, this gap is about 0.01-0.03 mm. In addition, in the matching parts of the push rod, inserts, etc. with the mold body, small gaps can also be used for exhaust. This method of exhausting through the gap of the mold structure does not require the additional setting of a complex exhaust structure, but requires high manufacturing accuracy of the mold.
4. Use of exhaust components
In addition to the above methods, special exhaust components can also be used to achieve the exhaust of Beverage bottle preform mold. For example, the exhaust plug is a common exhaust component. The exhaust plug is usually installed in the appropriate position of the mold cavity or core, and has a special structure inside to guide the air to be discharged from the channel inside the plug. The advantage of the exhaust plug is that it has a good exhaust effect and can be flexibly installed according to the specific layout of the mold. There are also some exhaust valves that can be used for mold exhaust. It can automatically control the opening and closing of the exhaust according to the pressure changes in the cavity, ensuring that the air can be discharged in time during the preform molding process, and preventing the plastic melt from flowing back during the plastic melt pressure holding stage. By reasonably selecting and arranging these exhaust components, the exhaust performance of the mold can be effectively improved, thereby improving the molding quality of the preform.
