Development status of extrusion die for the hottes

2022-10-19
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The development status of plastic profile extrusion die

machine information "Integration: Abstract: This paper summarizes the development process of China's extrusion die with the plastic door and window industry, and analyzes the gap with imported advanced extrusion die. It is proposed that the professional production of extrusion die should work together with large profile production enterprises to strengthen theoretical and experimental research, further improve the level of domestic extrusion die, and promote the healthy development of plastic profile doors and windows industry in China

key words: plastic profile; Extrusion die; Plastic doors and windows

1 The plastic door and window industry has developed rapidly

over the past decade, China's plastic door and window industry has experienced several ups and downs, but with the joint efforts of colleagues, it has always been in the process of continuous technological progress and market expansion. In recent years, due to the needs of national conditions and national policy guidance, another opportunity for rapid development has been obtained, and a considerable industry scale has been formed. According to relevant statistics, the consumption of plastic profiled materials in 1999 was more than 300000 tons, and the production of plastic doors and windows was 30 ~ 40 million m2, an increase of more than 50% over 1998. At present, the total number of domestic and imported plastic profile production lines exceeds 2500, the profile production capacity has exceeded 1million tons, and more than 10 large or super large plastic profile production plants of more than 10000 tons have been built. The production capacity of doors and windows exceeds 120million m2. Plastic profile extrusion die (hereinafter referred to as extrusion die) is one of the key technologies of plastic doors and windows. The production of extrusion die in China is developing with the development of plastic door and window industry.

2 development process and current situation of extrusion die

for a long time, plastic profile extrusion processing has been a relatively weak category in the new material industry with high thermal and electrical conductivity of plastic processors in China. The single screw extruder is used, and the extrusion die produces profiles with relatively simple cross-section at a low rate (about 1m/min). Since the mid-1980s, in order to accelerate the development of plastic door and window industry, China has begun to import a large number of foreign advanced twin-screw profile extrusion production lines. In addition to good compatibility with human skin, the cost shows that the setting of "breakpoint ratio value" is too small, which raises the production level of plastic profile with a range of 0 ~ 10 mm in China to a higher level. However, the development of plastic profile doors and windows production requires a large amount of extrusion die. However, several or more pairs of extrusion dies introduced with the extruder unit are far from meeting the needs of the changes and development of the building door and window market. At that time, the international market price of extrusion dies that could meet the requirements of these advanced extrusion units was about US $30000 to US $40000, or even more expensive. However, the lack of domestic support has become one of the main factors restricting further development. This situation and its business opportunities promote the research and development of extrusion dies. Because of this, the domestic research and development of extrusion dies are basically carried out with imported extrusion dies as samples, with more mapping and imitation, less experimental research, and less machine-based research and exploration. The practice of extrusion die is very strong, so far there is no strict theory and fixed mode. The design and manufacture of extrusion dies in China have developed rapidly with the introduction of foreign advanced extrusion dies and the active participation of some universities

however, the design of the extrusion die should solve the problems of the non Newtonian characteristics of the flow of the molding compound and the comprehensive effects of the bad mold release expansion, traction deformation and cooling shrinkage of the molding mold; It is also affected by many aspects, such as extrusion unit (mainly screw and barrel), molding compound formula (including formula components and mixing conditions) and operation process (temperature, speed, cooling water and vacuum degree). Therefore, it is difficult to design a high-quality extrusion die simply by mapping and copying. Especially in the face of the continuous improvement and development of complex profile and raw material formula, as well as the continuous improvement of the requirements for profile product quality and production efficiency, it shows the lack of theory and experiment. In addition, being limited to perceptual experience and relying too much on repeated debugging and die repair will inevitably lead to more failures and a lot of waste of manpower, energy and raw materials in the process of debugging and die repair, and it is also difficult to stably obtain high-quality extrusion dies. However, the market demand has a huge driving force. Over the past decade, with the development of the plastic door and window industry, China's extrusion die has formed a considerable production capacity. It is understood that at present, more than fiveorsix domestic manufacturers actually deliver more than 200 sets of extrusion dies every year. In addition, there are more mold factories that provide a large number of extrusion dies. In 1999, the total number of domestic extrusion dies actually delivered for use has exceeded 3000. In addition to the single cavity extrusion die for single melt extrusion, various extrusion dies such as the first mock examination multi cavity, two-color coextrusion, soft and hard coextrusion, post coextrusion, recycled material coextrusion and low foaming steel plastic coextrusion have also been manufactured. The production speed of plastic profile of the extrusion die has also been continuously improved, and the domestic leading extrusion die has achieved the extrusion speed of the main profile of more than 2.5m/min. The application of computer high-tech means has further promoted the development of extrusion dies in China. A practical extrusion die CAD system has been successfully developed and connected with wire cutting CNC machine tools to realize cad/cam integration; The extrusion die cavity is processed by slow wire four coordinate wire cutting machine tools (more than ten of which are imported) and imported abrasive flow extrusion grinding and polishing machine tools, which greatly improves the production efficiency and manufacturing accuracy. The mold industry formulated and issued the plastic extrusion die industry standard jb/t in 1998, which is more mature. 

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