Production process equipment and development of th

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Production process, equipment and development of plastic hollow containers (3)

process comparison:

(1) extrusion blowing: This is commonly referred to as slipping

a. it is applicable to PVC, PE, pp

b. the mold closing line is deep, which affects the appearance and strength

c. there is a head of tailings, which requires more manual and auxiliary equipment for recycling

d. poor accuracy of bottle mouth thread.

(2) injection blowing:

a. it is applicable to PE, Pp

b. not suitable for containers over 300ml

c. not suitable for flat and special-shaped containers

d. containers produced by horizontal injection and blowing machines are prone to uneven wall thickness due to the effect of gravity

(3) injection, drawing and blowing

a. suitable for pet, PP, PC, PMMA plexiglass, etc.

b. the accuracy of parisons is high to ensure the accuracy of bottle mouth and thread

c. the products have no flash and save materials, No need of crusher and mixer

d. extremely low product scrap rate

e. good impact toughness, increased rigidity, improved barrier performance, good surface transparency and gloss

f. no clamping line, good fall resistance

2. development process:

the first stage: until the late 1970s and early 1980s, a large number of glass containers and PVC and PE plastic medicine bottles produced by extrusion blowing process were used

the second stage: from the late 1980s to the 1990s, many glass containers were still used, but the injection blowing process replaced the extrusion blowing process with its progressiveness. In order to improve the quality of pharmaceutical packaging containers, the state has supported a number of state-owned enterprises, such as Shanghai Haichang, Wuxi Hongguang, Wuhan Xiamei, Shandong Xinhua, Qinhuangdao plastics, etc., and introduced a number of injection and blowing machines made by American weaton, which has greatly improved the market share and quality of PE medicine bottles

the third paragraph: in the early 1990s, with the gradual development of injection, drawing and blowing technology in China, pet drug bottles began to enter the drug packaging stage. Guangdong Nanfang packaging company, represented by Guangdong Nanfang packaging company, introduced a farad blowing equipment from Aoki Institute of Japan to mass produce pet drug bottles and successfully rolled out pet drug bottles in southern China. At the same time, due to the impact of glass production process on the environment, the pharmaceutical Bureau issued a policy to replace glass containers with plastic products

until 2001, a pattern was formed: the plastic PET bottles produced by one-step green wood machine in Southern Packaging won most of the Southern markets, while PE bottles were still the main market in central, East and North China, but some pet bottles produced by two-step injection, drawing and blowing machine (represented by Huangyan machine) appeared

3. development history of equipment:

China's pharmaceutical packaging products have developed rapidly in recent years. The demand for plastic packaging containers is increasing day by day, and the plastic packaging container forming equipment is also growing. During the operation of the blow molding equipment, the bottle mouth is first injected to ensure the accuracy of the bottle mouth, and then the bottle body is blow molded. Therefore, the gas in the bottle can be prevented from penetrating into the bottle, ensuring the close performance between the bottle mouth and the bottle cap. Although the equipment for plastic injection blow molding hollow containers in China can be produced in a small amount during the "sixth five year plan" and "Seventh Five Year Plan", the accuracy and performance of the equipment itself are inferior to those of foreign equipment

at present, efforts should be made to improve the precision in the production of such equipment to become a real precision injection blower. The so-called "precision injection blower" not only means that the high-speed and high-pressure equipment during the forming process has good stability so that it will not produce liquid leakage when solid-liquid phase change occurs, but also requires that the produced container achieve high stability in terms of size fluctuation and quality fluctuation, that is to say, the dimensions and geometric shapes of the produced container should have high accuracy, and the appearance, internal quality, production efficiency and other indicators of the container can also reach a high level, In this paper, the development of injection blower in China at present and in the future is predicted as follows:

(1) hydraulic control system with high sensitivity, high reproducibility and stability

in the hydraulic system, in order to play the functions of energy conversion, transmission and control, the plunger screw of the precision injection blower is driven by the hydraulic motor, and the injection molding is controlled by the hydraulic system. The injection pressure, injection speed and plasticizing pressure are controlled and uniformly adjusted by the control valve installed in the hydraulic system

the adjustment of the screw speed of the blower depends on the electronic instrument. The electronic indicator consists of a sensor and a display. According to the different differences of unidirectional pulses, the screw speed value determined by the computer can be accurately displayed on the display

(2) it has fine-tuning control performance, excellent and reliable operation and easy-to-use electronic control system

the adjustment of screw speed of injection blower depends on the electronic instrument. The electronic indicator is composed of sensor and display. According to the difference of unidirectional pulse, the screw speed value determined by the computer can be accurately displayed on the display

(3) it can carry out high-speed and high-pressure injection parison, and minimize the shrinkage of the container during blow molding

another feature of the precision injection and blowing machine is the development in the direction of high injection pressure. Its purpose is to reduce the shrinkage after blow molding and increase the density of the container. As the injection pressure is high and the injection speed is fast, the rigidity of the clamping system is better than that of the ordinary injection blower. 1) it is used for the round rib joint sample at room temperature;, It has good durability, sufficient clamping force of injection mold blowing, and can resist the pressure of high-pressure and high-speed injection of molten plastic. The mold deformation is minimal

(4) it has an excellent plasticizing device, which can fully plasticize the plastic at a uniform temperature and correctly measure it.

when the molten material is injected into the parison mold and begins to form into the blow mold, the plunger screw of the inner cylinder of the injection blower rotates, so that the feeder can transport the plastic particles loaded with the juice to the front end of the screw, and plasticize the material under the action of heat. When the process melt accumulated at the front end of the barrel is equivalent to the set injection volume, it will generate a certain thrust on the screw, so that the screw can accurately measure the melt and appear on the display, ensuring the accuracy of the pre molding amount

(5) design and manufacturing technology of precision injection mold blank film and blow mold. Therefore, the shrinkage of plastic raw materials and the factors that affect the container accuracy in the design of the blow mold of the blank mold should be considered to reduce these factors as much as possible. These factors roughly include the shrinkage of raw materials, the distribution of shrinkage, the position and size of injection molding blanks and injection flow ports, the distribution of blank mold temperature control pipes and blow mold cold water pipes, as well as the selection of mold materials

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