Blow molding machine, also known as hollow blow molding, is a rapidly developing plastic processing method. Blow molding machine is a machine that sprays liquid plastic and uses the wind force blown by the machine to attach the plastic body to a mold cavity of a certain shape, thereby producing products.
Blow molding machines can be divided into three categories: extrusion blow molding machines, injection blow molding machines, and special structure blow molding machines.
Hollow forming machine, mainly composed of extruder, head, hydraulic system, mold closing system, electrical control system, inflation system, automatic clamping and other parts, is used for blowing hollow products of PE and other various materials. Such as square barrels, round barrels, beer preservation containers, toolboxes, lampshades, etc. This machine has high performance, low energy consumption, and easy operation.
At present, the high-end hollow machine on the market is a leading updated product developed and researched based on China's national conditions. It uses high-quality hydraulic components, adopts PLC control, and the most advanced first in first out material storage head. On the basis of the advantages of traditional hollow machines and the most advanced technology today, its performance is more outstanding and reliable. High efficiency and applicability have reached the level of similar products in Japan and Germany.
The tubular plastic preform obtained by extrusion or injection molding of thermoplastic resin is placed in a split mold while it is hot (or heated to a softened state). After closing the mold, compressed air is immediately introduced into the preform to inflate it and tightly adhere to the inner wall of the mold. After cooling and demolding, it is removed by a robotic arm to obtain various hollow products.
The manufacturing process of blown film is very similar in principle to blow molding of hollow products, but it does not use molds. From the perspective of plastic processing technology classification, the molding process of blown film is usually included in extrusion. Blow molding technology began to produce low-density polyethylene small bottles using dry methods during World War II. In the late 1950s, with the birth of high-density polyethylene and the development of blow molding machines, blow molding technology was widely applied. The volume of hollow containers can reach thousands of liters, and some production has adopted computer control. Plastics suitable for blow molding include polyethylene, polyvinyl chloride, polypropylene, polyester, etc. The resulting hollow containers are widely used as industrial packaging containers. According to the production method of preforms, blow molding can be divided into extrusion blow molding and injection blow molding, with newly developed methods including multi-layer blow molding and stretch blow molding.
After more than 20 years of research, blow molding technology has made great progress both in theory and practice. However, based on relevant data, it has been found that the research on blow molding technology is generally focused on a certain period of the molding process, and numerical simulation of different process factors for the overall analysis of the entire process is relatively rare. The blow molding process can be roughly refined into three stages: billet forming, billet inflation, and cooling and solidification, which form a close correlation. The external structural shape and wall thickness distribution of the billet directly affect the surface contour and wall thickness uniformity of the billet inflation. For the billet inflation stage, the compressed air and the thickness and temperature distribution of the product obtained after inflation will affect the cooling and solidification process of the product, thereby affecting the performance of the product. Based on the above discussion, it is found that strengthening the systematic numerical simulation of the entire blow molding process has great practical significance and ensures the continuity of the simulation process, thereby more accurately explaining the entire process of product molding. The level of blow molding technology will also be correspondingly improved.
In the context of rapid socio-economic development, there is a growing demand for hollow plastic products in various industries, and higher requirements are being put forward for product quality. In addition, the geometric shapes of products are becoming increasingly complex. If enterprises are stuck in the production state of repeated mold testing in the manufacturing process of hollow plastic products for a long time, it is difficult to ensure that they have a foothold in the fierce market environment, and there is even a risk of being eliminated. Based on the current situation, it is found that China's hollow blow molding technology started relatively slowly, but developed rapidly in the later stage. Universities and major enterprises are actively involved in the research process of this technology, which promotes the output of new production methods and the diversification of equipment.