Blow moulding is a rapidly developing plastic processing method, which is divided into extrusion blow moulding and injection blow moulding. At present, it has developed into the third largest plastic product moulding method after injection moulding and extrusion moulding. The development of blow moulding industry is also more and more rapid. The plastic bottle shampoo
is a typical blow moulding part. It can be seen everywhere in daily life. The structure of the bottle mouth is generally much smaller than the bottle body. It can not be moulded by injection moulding at one time. It needs to be produced by blow moulding. The extrusion blow molds have the advantages of simple structure, low cost, simple process and high efficiency.
1. Structure analysis of shampoo bottle
High density polyethylene (PE-HD) container has good handle, light weight, non-toxic and tasteless. It is suitable for shampoo packaging. PE-HD material is used for bottle body, and its density is 0.95g/cm3. The volume of shampoo bottle is 450 mL and the wall thickness is about 1.0 mm. It is required that the molded product has no flying edge and the parting line should be combined smoothly, no dislocation and no obvious marks of parting line.
2. Structural Design of Extrusion Blow Mold
In the production of plastic hollow products, the quality and output of blow moulding products are mainly affected by the structure of blow molds and the processing quality of molds, besides the precision and automation of blow moulding equipment.
In the aspect of die structure, the structure of the cutting edge, the proper setting of the exhaust system and cooling system have a great influence on the quality and output of the products.
3. Overall structure of extrusion blow molds
The extrusion blow molds are mainly composed of two concave die chambers (negative molds). The molds should meet the following requirements in blow moulding:
(1) Hollow products with complex shapes can be formed; (2) It can effectively clamp the billet and ensure the strength of the joint line of the product. (3) Effective and rapid exhaust; (4) It can quickly and evenly cool plastic products, and reduce the temperature gradient in the die wall, so as to reduce the forming time and warpage of the products.