A. Injection molding mold blow molding process

During the injection blow molding process, the injection molding preform is sent to the core and blow molded into the blow mold cavity.

The quality and wall thickness of the product depend on the shape of the injection mold cavity. Changing the injection parameters only has a slight adjustment to the weight of the product.

The material used for the injection mold is steel. In order to improve the filling quality, the mold surface is often chemically treated.

For blow molding of blow-molding material, blow molding rods intruded into the material chamber. After the neck ring is filled, the blowing rod pulls back. “The axial wall thickness of the parison can be changed by designing the piston of the nip chamber. The production of the parison is shown in Fig. 4-20. The parison is then blow moulded. After removing the blow moulded products, after which the blow-off rods are retracted and the blow-moulding process is continued with an auxiliary blow-molding rod, since the injection blow moulding and the slush-molding blow moulding do not require trimming, their moulds can be made of aluminium .

II. Application of Computer in Blow Molding

Blow molding is usually designed using a computer. For product design and NC programming, three-dimensional (3D) systems are preferred. Die design is more inclined to use two-dimensional (2D) computer-aided design system (CAD).

It is the automotive industry that has promoted the adoption of 3D CAD systems. Automakers mainly use 3D technology to develop their products and give their suppliers the right to use all VDA-FS data files. Moldmakers then use these data to design molds and program their washing machines.

Due to the complexity of the product, the direct transfer of the model to a blow mold has not proven to be practical. In most cases, the model is a transitional step in the manufacture of blow molds. This can be considered useful because: in the automation industry, product designers are not experts in extruding blow-molding; products often change before real production starts; a 1.l model is very Useful; manufacturing of molds

It is not always simple, especially in the parting line area. In order to facilitate the blow molding process and meet the needs of mold manufacturing, it may be necessary to change the product.

The 3D surface data can easily be used to determine the reference point to verify the article and program any measuring machine. The 3D CAD design enables the user to accurately depict the product's geometry. In addition, using it to make a model is impossible.

As shown in Figure 4-21, the shaded part of the plane model is the gas pipeline. For packaging products, using the 3D design method to determine the necessary mold volume, and then repeatedly determine the external dimensions of the product is relatively easy. This method can reduce errors in size and size, which can lead to repetitive work and significant cost increases.

Advantages of CAD: Can accurately depict products; Eliminate errors caused by data conversion; Easy to change design, reduce all errors caused by major changes; Can extract any data to check the size of models, molds and products; Fast access to data. Disadvantages: Planar position modeling (3D design) is more expensive than ordinary 2D design.

In general, the increase in cost caused by the design can be compensated by the reduction in cost when the model is applied.