Development status and technical progress of the h

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Development status and technical progress of plastic hollow containers (II)

5. Large chemical liquid packaging containers have become a new development hotspot

barrels for chemical liquids, lubricants, coatings and other industries are new large packaging containers developed in recent years. At present, they have become a new development hotspot in China's packaging containers. By the end of 2004, China has introduced 20 production lines from abroad, with a total production capacity of 900000. The larger manufacturers are Shanghai Fanshun Industrial Co., Ltd. and Changzhou Yueyang plastic container company. Because the requirements of large-scale hollow container manufacturing equipment are much higher than those of general small-scale blow molding machines, in addition to the storage head, it also has the function of high-precision control of the parison, so China's early large-scale blow molding machines were imported from abroad. For example, the equipment that first produced 200L closed plastic barrels and lined barrels in China was introduced from bekum company in Germany, and then the 200L l ring plastic barrel production line was introduced. Qilu Petrochemical and Jinling Petrochemical plastic plants imported bm-201 blow molding machines from German Mauser company to produce 200L self-supporting L-shaped closed rigid plastic barrels for international dangerous goods and transportation and packaging. In 1993, Qinchuan machine tool factory designed and manufactured the first domestic large-scale blow molding machine, which was put into operation in Qingyun plastic factory in Wujiang, Jiangsu Province, and achieved good results. Subsequently, many companies produced large and medium-sized blow molding machines in the form of cooperation and joint venture with German and Taiwan manufacturers. For example, Guangdong Jinming Plastic Equipment Co., Ltd. introduced a large barrel blow molding machine with a production capacity of 230L using foreign technology. 6. Plastic pallets have a broad prospect in logistics transportation

pallets are consumables used in warehousing and transportation, with a domestic circulation of about 80million per year. Among them, 20million ports are used for exporting goods alone. The materials used to make pallets can be wood, metal and plastic. At present, 95% of the pallets in China are made of wood, which not only consumes a lot of wood resources (each wooden pallet needs to consume 0.05m3 of wood), but also must be cooked or treated at high temperature to prevent pests from being carried in (Anoplophora glabripennis), otherwise foreign countries will refuse entry. If plastic pallets are used, the above problems do not exist, and it can also be water-resistant, sun resistant, save freight, be conducive to open-air operation and storage, so as to save the port turnover warehouse. In addition, compared with wooden pallets, its hardness and turnover utilization rate are also increased by 3-5 times. Therefore, it is imperative for China to vigorously develop plastic pallets

at present, three kinds of process equipment are used to produce plastic pallets in China. One is injection method, which requires injection machines of more than 10000 grams and large molds, and the cost is high; The second is the combination method, which first uses the extrusion method to produce laths, and then cuts and combines them. This method has low cost but poor use strength; The third is the special-shaped hollow blow molding method developed in recent years, which is simple and saves raw materials. At present, only three enterprises in Beijing and Shanghai can produce plastic pallets in the industry, and the plastic pallets they produce have become popular new products in the market. For example, how to solve the 1.4m external interference of the electronic universal experimental machine produced by Beijing Huadun company × The 1.2m containerized plastic pallet has a good effect in large chemical enterprises

7. Plastic gasoline tanks are in the ascendant

the plasticization of fuel tanks is the trend of modern automobile fuel tank manufacturing. With the development of automobile industry, plastic fuel tanks are used more and more widely in various countries. The utilization rate of plastic fuel tanks in developed countries in Europe and America has accounted for more than 90% of the market share, and the utilization rate of Ford company in the United States has even reached 100%

China began to introduce single-layer fuel tank production lines in the late 1980s, and multi-layer fuel tank production lines have been introduced in recent years. This is because with the development of automotive industry technology and the continuous improvement of environmental protection and safety requirements, the requirements for the impermeability of plastic fuel tanks are becoming higher and higher. According to European ECE rules, the average fuel loss of the oil tank in 8 weeks at a temperature of 40 ℃ cannot exceed 20g/24hr, while the impermeability of single-layer HDPE oil tank cannot meet this requirement. At present, through independent research and development, Qinchuan machinery development company has manufactured a hollow molding machine that can blow mold a 6-layer coextruded fuel tank containing a high barrier EVOH functional layer. The products blown with it have been widely used in Shanghai Buick cars. It is understood that the demand for multi-layer fuel tanks in China has reached 1million in 2004, which shows that the development of its market is in the ascendant

progress in plastic hollow container molding technology

in recent years, China's plastic hollow container molding technology has made considerable progress, and the output of hollow blow molding machines has increased rapidly. The annual output in 2004 has reached 3973 units, an increase of 22% over 2003

with the progress of hollow blow molding technology (extrusion blowing, injection blowing, injection drawing blowing), especially the development of large-scale hollow molding equipment, multi-layer co extrusion hollow molding process and equipment, it has driven the latest development of other hollow molding technologies, including gas assisted injection molding, shell technology, rotational molding, blister molding technology, etc

1. Squeeze blow hollow molding technology

squeeze blow hollow plastic molding machine is the main equipment for the molding of hollow containers. 80% - 90% of the world's hollow containers are formed by extrusion blow molding. In the development process of hollow plastic molding machine in China, extrusion blow hollow plastic molding machine is the fastest developing and most perfect machine. In recent years, the latest development of extrusion blow molding technology is mainly reflected in three-dimensional (3D) blow molding of complex hollow containers and large packaging containers

(1) three dimensional (3D) blow molding process

three dimensional (3D) blow molding is also known as less waste or blow molding without flash to promote the transformation and upgrading of EPS materials in China. In recent years, the market demand for complex and tortuous conveying pipe products has promoted the progress of this technology. 3D blow molding process usually uses 6~8 axis manipulator to transport the parison and place it in the blow mold for blowing

(2) large scale hollow blow molding technology

large scale hollow blow molding technology belongs to the extrusion blow molding process from the government level. At present, the containers formed by large blow molding machines are mainly IBC barrels (500~2000l) and 200L double L all plastic barrels

large hollow blow molding machine generally includes extruder, head, clamping device, blowing device, parison wall thickness control system, product taking out device, hydraulic station and strong and weak current control system. General external auxiliary equipment includes mixed feeding system and residual material crushing and recycling system. According to the way of extruding the parison, the large hollow machine can be divided into storage type and continuous extrusion type, and according to the structure of the parison, it can be divided into single-layer or multi-layer. At present, the vast majority of domestic 200L double L all plastic barrels are blown by single-layer storage type hollow machines. The following takes this kind of large-scale blow molding machines as an example, and introduces the technical progress of large-scale blow molding machines from its most important system components

● extruder

the raw materials processed by large hollow machines are generally HMWPE. If the configured extruder adopts conventional design, its plasticizing efficiency is obviously insufficient. For example, using domestic f150/25 extruder to process HMWPE powder, its plasticizing capacity is only 250kg/h. Therefore, the large hollow machine should adopt the single screw extruder with forced feeding structure and forced cooling section structure, that is, the extruder with IKv structure. Under the same length diameter ratio, the plasticizing capacity of this extruder can be increased by more than 50% compared with the conventional design, and the extrusion capacity is stable. Combined with the reasonable design of barrier section and mixing section, it can also obtain high plasticizing quality

● storage head

the flow passage of storage head mainly has three forms, namely, single-layer heart-shaped envelope flow passage, double-layer heart-shaped envelope flow passage and double-layer spiral flow passage

the early hollow machine heads mostly used single-layer heart-shaped envelope flow channels, mainly because the requirements for molded products were not high at that time. With the continuous improvement of the quality requirements of users for containers, especially in large containers, there is a problem of insufficient strength of fusion joints, so the design of double-layer heart-shaped envelope channel and spiral channel has appeared. The reason why the double-layer heart-shaped envelope channel can improve the strength of the fusion seam area is that the extruded parison can be covered by a complete melt layer, unlike the single-layer heart-shaped envelope channel, there will be obvious fusion seam areas on the circumference of the parison. The advantage of double-layer spiral channel is that the inner and outer layers are fed by two extruders and stored at the same time. In particular, because the inner layer of the product can use non coloring materials, this kind of runner is very competitive

for the storage type hollow machine head, an important aspect to measure its level is its refueling speed. Although users hope that the faster the refueling, the better, it is actually difficult to achieve. Even for a well-designed handpiece, the refueling time often takes several hours. Although a hydraulic device that can lift the flow channel has appeared in recent years, through which the external cleaning can be achieved, so as to speed up the refueling, the device also brings problems such as the huge structure of the machine head, high requirements for manufacturing and assembly accuracy, and the poor labor environment of workers during actual cleaning. Therefore, in order to speed up the refueling speed, the primary task is to use the correctly designed flow channel and minimize the detention area

● clamping device

in recent years, the clamping device of large hollow machine gradually tends to adopt two plate pin locking mechanism. The die movement of the device is realized by the oil cylinder or servo motor through the ball screw. Due to the adoption of roller linear guide rail, it has the advantages of high rigidity, high motion accuracy, light motion and fast lighting of 257 buildings. The clamping force of the two plate clamping device is realized by two or three pairs of pin locking cylinders with adjustable positions. In order to facilitate the installation of the die, these pin lock cylinders can be simply removed from the die and adjusted along the axial direction to adapt to different die thicknesses. Similarly, there is also a mode locking device called "Hu's mechanism". Its principle is basically the same as that of the pin locking mechanism, but it can be used in the mode clamping mechanism requiring greater mode locking force. In terms of hydraulic control of mold closing device, proportional hydraulic valve is generally used now to accurately control the speed of mold closing, which is conducive to the molding of products

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