Application Status and Development Prospect of Domestic Extrusion Equipment

In recent years, the output of China's plastic products has stabilized at more than 20,000 kt/a, ranking second in the world, and it has become a veritable producer of plastic products. According to relevant department statistics, the growth rate of China's plastics processing industry is obviously higher than the average growth rate of the national economy. The rapid growth in the production of plastic products provides a good opportunity for the development of plastics processing equipment manufacturers. This article mainly discusses the current situation and development trend of domestic extrusion equipment.

(I) Production and Application Status of Domestic Extrusion Equipment

At present, China produces more than 25,000 sets of various types of extrusion equipment annually, including a variety of single-screw extruders, parallel twin-screw extruders for compounding pellets, and tapered doubles for the production of PVG pipes and profiles. Screw Extrusion Units, as well as a small number of different-direction parallel twin-screw extruders, Brinell mixing extruders, Planetary Mixing Extruders, etc.

There are hundreds of extrusion equipment manufacturers in China, mainly in Shandong, Liaoning, Zhejiang, Jiangsu, and Guangdong. Among them, Dalian Bingshan Group, Shandong Huaguan Group, Weifang Zhongyun Machinery Co., Ltd., Qingdao Deyili Group, Zhejiang Jinwei Group, Zhejiang Jinhu Group, Shanghai Shenweida Company, Nanjing Keya Industrial Co., Ltd., Beijing Futian Building Material Co., Ltd., etc. The output value of more than 20 backbone enterprises exceeded 70% of the total output value of domestic extrusion equipment. Table 1 shows the statistics of the top 10 extrusion equipment manufacturers in China in 2002.

The annual export volume of domestic plastic machinery is about 100 million U.S. dollars, of which the export volume of extrusion equipment does not exceed 3 million U.S. dollars. The total value of imported plastic machinery in the country is about 1.5 billion U.S. dollars each year, of which more than 2,000 sets of extrusion equipment are imported each year, worth about 200 million U.S. dollars.

The gap with the international advanced level

In recent years, the technological level of domestic extrusion equipment, especially the supply of complete sets of equipment and supporting software technologies, has greatly improved, and the gap with the international advanced level has narrowed. At present, we can provide extrusion molding production lines for various shapes, tubes, plates, sheets and films, as well as mixing and granulation and reactive extrusion production equipment.

(II) Technical level of domestic extrusion equipment

(1) Parallel co-rotating twin-screw extruder
The processing industry of modified plastics has maintained a strong momentum of development. In recent years, the market demand for domestic parallel twin-screw extruders has remained at around 1,000 units per year. The domestic twin screw manufacturers represented by Nanjing Keya Industrial Co., Ltd., Dalian Bingshan Rubber & Plastics Co., Ltd., and Lanzhou Lantai Plastic Machinery Co., Ltd. have been able to produce series products with screw diameters of 165 mm or less. The screw speed has increased from 300 r/min several years ago to 600 to 800 r/min, and the stand-alone output has been greatly improved.

(2) Single Screw Extrusion Production Equipment

Single-screw extrusion production equipment is the main equipment for the production of plates, sheets, membranes, tubes, profiles, cables and other products, and it is also the equipment with the largest market demand. In recent years, the domestic extrusion tube and extruded film production equipment has developed particularly rapidly.

The driving force for the development of plastic pipe production equipment and technology is mainly due to the increased efforts of the state to promote the construction of hot and cold water for building and plastic pipe for municipal water supply and drainage. One-step silane cross-linked polyethylene pipe extrusion equipment, aluminum-plastic composite pipe production equipment, random copolymer polypropylene pipe extrusion equipment, ultra-high-molecular-weight polyethylene pipe extrusion equipment, and steel-plastic composite pipes have been successively developed in China. Production equipment, peroxide cross-linked polyethylene pipe production equipment, large-diameter (below 800mm in diameter) polyethylene solid wall pipe extrusion production equipment, large-caliber hollow wall winding pipe production equipment, and double-wall corrugated pipe production equipment with a diameter of 800mm or less .

A group of domestic plastic film manufacturers represented by Guangzhou Jinming Plastics Equipment Co., Ltd. can produce various films with a width of 20m or less; in recent years, China has also developed a five-layer/seven-layer co-extrusion blowing and water-cooling film blowing machine. It can produce a symmetrical structure of the barrier film, but also can produce asymmetric structure of the barrier film.

(3) Conical twin screw extrusion equipment

The conical twin-screw extrusion equipment is mainly used for the production of PVC pipe and PVG profiles. In recent years, the production and sales volume of conical twin-screw extrusion equipment in China has reached 1200 sets/year. The plastic profile equipment manufacturers represented by Shanghai Shenweida Machinery Co., Ltd., Zhejiang Jinhu Plastic Machinery Co., Ltd., Beijing Futian Building Material Co., Ltd., etc., can produce various types of common tapered, double-cone and high-efficiency double-cone twin-screws. Extruder.

(4) Scale and level of screw barrel machining

The domestic screw and barrel processing industry has formed a pattern of large-scale production. There are more than 300 screw barrel manufacturers in Zhoushan City, Zhejiang Province. The annual production value is about 1.5 billion yuan, and in addition to satisfying domestic requirements, it is also partially exported. Although in recent years, some key enterprises have introduced special machining centers from Europe, the machining accuracy and interchangeability of screw barrels have been greatly improved. However, the production equipment of most screw barrel manufacturers still lags behind.

(5) Extrusion molding auxiliary machine

Zhangjiagang City, Jiangsu Province has developed into the largest production base for plastic molding auxiliary equipment in China. There are hundreds of plastic molding auxiliary equipment manufacturers, which can provide various plastic mixing equipment, drying equipment, crushing equipment, traction equipment, cutting equipment, etc. Auxiliary machine, can also provide pipe, sheet, film, profiles and other sets of extrusion molding auxiliary machine.

The gap with foreign advanced level

Some domestic plastics machinery enterprises have seized the golden opportunity in recent years and achieved leap-forward development. They not only accounted for the larger domestic market share, but also exported a considerable number of products abroad. However, as far as the overall level of technology is concerned, there is still a large gap between China's plastics machinery and foreign developed countries. At present, equipment such as biaxially stretched film (BOPP, BOPET, BOPA, BOPS, etc.) production lines, drip irrigation pipe production lines, medical catheter production lines, audio-visual film-based and photosensitive film-based production lines, and large twin-screw extrusion granulation equipment for petrochemical use mainly depend on imports. . The main gap between domestic extrusion molding equipment and foreign products is mainly reflected in the following aspects:

(1) The gap in stand-alone production speed

Reifenhäuser and KraussMaffei produced single-screw extruders with a screw diameter of 125 mm (length-to-diameter ratio of 30) for the production of high-density polyethylene with a throughput of up to 950 kg/h; screw diameters from Nokia Maillefer With a single screw extruder of 150 mm (30 aspect ratio), the production of PVC cables has reached 1300 kg/h.

According to the data, the single-screw extruder abroad screw diameter from 6mm to 600mm, the maximum length to diameter ratio of 60; Japan Chiba's D30 single screw extruder speed up to 3000r/min, the output up to 300kg / h . Conical twin-screw extruder for the production of PVC pipe, single machine output up to 1100 ~ 1500kg / h; parallel twin-screw extruder screw diameter has exceeded 300mm, length-diameter ratio up to 100, the maximum screw speed up to 1500r/min , WP's ZSK133 series of machine production reached 7000 ~ 11000kg / h. (to be continued)