With the market demand for its products, blow molding will have the following development trends in materials, machinery, auxiliary equipment, control systems, software, etc.

(1) Raw materials to meet the function and performance requirements of blow molding products (medicine, food packaging), the raw materials of blow molding grade will be more abundant and the processing performance will be better. Such as PEN materials, not only high strength, good heat resistance, strong gas barrier properties, transparency, UV resistance, can be suitable for blowing various plastic bottles, and high filling temperature, excellent barrier properties to carbon dioxide gas and oxygen, And chemical resistant.

(2) Product packaging containers and industrial products will have a greater growth, and injection blow molding, multi-layer blow molding, and hollow blow molding will have rapid development.

(3) Precision and high efficiency of blow molding machinery and equipment blow molding machinery; automation of auxiliary production (operation) equipment. "Precision and high efficiency" not only means that the mechanical equipment has high speed and high pressure during the production and molding process, but also requires the produced products to achieve high stability in terms of appearance size fluctuations and piece weight fluctuations, that is, It is said that the size and shape of each part of the product have high precision, small deformation and shrinkage, and the appearance, internal quality and production efficiency of the product must reach a high level. Auxiliary operations include deflashing, cutting, weighing, drilling, leak detection, etc. The process automation is one of the developing trends.

(4) The research on the blow molding mechanism of blow molding simulation is more in-depth, the reasonable construction of the mathematical model of blow molding simulation, and the fast and accurate numerical algorithm are the keys to the simulation. The blow molding simulation will play a role in product quality prediction and control. increasingly important role.

The molding parameters of each stage are analyzed from the blow molding process below. The blow molding process can be divided into four stages:

(1) During the parison formation stage, the polymer is transported, melted, kneaded, and pumped out of the extruder to form the parison; in this stage, the main process parameters that affect the wall thickness distribution are:

①Molecular weight distribution and average molecular weight of the material;

②The temperature control system and screw speed of the blow molding machine, in which the temperature control system includes the temperature of the hopper, the temperature of the 1st, 2nd, 3rd and 4th areas of the barrel, the flange temperature, and the storage die; Shanghai blow molding processing

(2) Parison blanking stage The parison is extruded from the gap between the die lip and the die core as the blanking stage. At this time, the two phenomena of parison release expansion and parison drawdown affect the parison forming. The main process parameters that affect the wall thickness distribution are the die diameter of the blow molding machine and the wall thickness control system. The air system includes an axial wall thickness control system and a circumferential wall thickness control system to adjust the gap between the die lip and the die core.

(3) In the pre-blowing stage of the parison, in order to avoid the contact and adhesion of the inner surface of the parison and improve the uniformity of the wall thickness of the product, the parison should be pre-blown. In the pre-blowing stage of the parison, the air is injected into the parison from below the parison to protect the parison and reduce its vertical extension. At this stage, the main process parameters that affect the wall thickness distribution are: pre-blowing pressure and pre-blowing time.

(4) High-pressure blowing stage of parison High-pressure blowing of the parison makes it close to the mold cavity and realizes the plastic forming stage of the product. At this stage, what affects the molding of the product is that the parison is deformed by high pressure inflation, and the parison is deformed by contact with the mold cavity. The main process parameters that affect the wall thickness distribution are: material shrinkage; blowing pressure, time; mold material, structure, mold exhaust system and mold cooling system, such as cooling water channel distribution, cooling water inlet temperature, etc. Although there are many factors that affect the quality of blow-molded products, when the production conditions and product requirements are determined, adjusting the blow-molding process parameters can effectively improve the quality of the products. Optimized process parameters can improve production efficiency, reduce raw material consumption, and optimize the overall performance of products.