What is the design process of the preform mold?

               
Update: 18-06-2021
               
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Consumers have higher and higher requirements for the q […]

Consumers have higher and higher requirements for the quality and appearance of the bottles. Only by applying modern CAD/CAM technology can the design and manufacturing cycle of beverage bottles and their molds be shortened, and the quality of the molds can be improved to quickly respond to the rapid changes in the market. So what is the design and manufacturing process of the PET beverage bottle mold?
1. The preform mould is made by first preheating the injection molded preform, and then moving the preform into the mold cavity and passing high-pressure air into the preform to inflate the preform to the mold cavity and cooling it. Generally, it must meet the following basic requirements The volume of the bottle. The volume of a beverage bottle generally refers to the volume of water in the bottle when water is poured into the bottle so that the difference between the height of the liquid level and the height of the bottle mouth reaches the point value. The allowable error range is generally about 1%.

2. The height of the bottle. Since the beverage bottle of each volume specification must be packed in a packing box of the correct size specification, the height of the beverage bottle is determined according to the volume specification and cannot be changed at will. ) Bottle mold exhaust. When high-pressure air is injected into the preform, the preform rapidly expands around the bottle cavity. The air in the bottle cavity must be discharged immediately to obtain a full bottle sample.

3. Generally, an exhaust groove is opened on the mating surface of one of the two-piece cavities. The groove width is 6~8mm, and the groove depth is 0.05~0.1mm. Because the clamping force of the bottle blowing machine is not large, the pressure of the two mold cavities should be increased. The outer side of the cavity matching surface should be milled and sunk by about 03mm to make the area of ​​the matching surface Decrease. Several vent holes should also be provided at the bottom of the bottle cavity. ) The bottom of the bottle. In order for the bottle to stand smoothly, the middle part of the bottom of the bottle must be recessed upwards. In addition, to prevent the bottom of the bottle from cracking when the beverage is poured into the bottle, the concave part of the bottom of the bottle must be designed with a bad groove.

4. The CAD modeling design of beverage bottles is based on the basic requirements of PET beverage bottles. The general method of designing beverage bottles using UG is: according to the two-dimensional drawings or bottle samples provided by the user, and other requirements, use the Modeling module to initially design the bottle samples . Use the Analysi analysis tool to test the initial bottle sample if the volume does not meet the requirements, adjust the volume by modifying the diameter of the bottle or modifying the bottom of the bottle under the premise of ensuring the same height until it meets the requirements. With volume means that the actual volume inside the bottle plus the volume outside the bottle is below the liquid level. The volume of the bottle can be calculated by dividing its weight by its specific gravity. Because the weight of the bottle is fixed, its volume is also fixed. Use Scale to enlarge the bottle-like model to compensate for the cooling shrinkage after the bottle is ejected from the mold. The shrinkage rate of PET plastic is 0.7'0.8%. We generally set the magnification factor to 1+0.0075. Use the Boolean function of UG to convert the bottle solid model into a mold cavity. Reuse the basic features to form the design of the guide post, the guide sleeve walking hole, the cooling water channel and the exhaust groove.

5. Beverage bottle mold design and processing method When high-pressure air is injected into the preform, the preform rapidly expands around, and the air in the bottle cavity must be discharged immediately to obtain a full bottle sample. In order to obtain a good exhaust effect, it is necessary to set an exhaust groove on the parting surface, and punch an exhaust hole in the bottom corner of the bottle where air is easy to trap. Generally, only the parting surface of one of the two cavities is vented. For this 500ml beverage bottle, the width of the slot is 5mm and the depth is 0.05'0.1mm, and three are opened on the sea side. Because the clamping force of the bottle blowing machine does not greatly increase the bonding pressure and adhesion of the two cavities, a 5mm wide contact surface is left along the circumference of the cavity. The outer side of the contact surface is milled and sinks about 0.3mm.

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