Development of pultrusion process

日期:2020/1/6 9:09:28 / 阅读: / 来源:本站

6.1.4. Development of pultrusion process

Foreign countries began research in this area in the early 1950s. Firstly, simple shapes such as fishing rods and insulating rods produced by squeezing appeared in the United States. Although the United States started using pultrusion products very early, it did not develop quickly in the first few years. This method is because at the beginning, it can only produce bars with simple cross-section shapes, and the cost is higher than metal and wood. Therefore, it has not been widely used quickly. With the development of science and technology, as the main raw material of glass fiber reinforced composite materials, the variety of glass fiber has gradually increased, the output has gradually increased, the quality has gradually improved, and the cost has decreased. On the other hand, the improvement of resin, another major raw material of glass fiber reinforced composite materials, has resulted in low shrinkage and rapid molding resins, creating extremely favorable conditions for continuous production of glass fiber reinforced composite products. During the year, extrusion molding has developed rapidly, from the original production of small products with simple shapes to the production of products with complex shapes and many specifications, such as downpipes, I-beams, channel steel, etc.

Pultrusion products are widely used in the construction industry, national defense, and mining. In recent years, the characteristics of high tensile strength of the bars formed by the extrusion method have been used in mines and tunnels to strengthen roadways. Although the price of glass fiber reinforced composite rods is slightly higher than that of steel rods, it is rapidly popularized and widely used because it is corrosion-resistant and can be used again. In some coal mines in China, in order to increase the mining speed, they have also begun to use extruded rods as resin anchors to strengthen roadways, with good results.

The new process of pultrusion is still under development. From the perspective of foreign development trends, it is developing towards the production of large-scale products, improvement of existing equipment, improvement of product appearance quality and lateral strength. At present, the largest pultrusion products in foreign countries are

A plate with a width of 1219.2 mm and a thickness of (6.35 to 25.4) m has an I-beam with a size of 304.8 m and an outer diameter of

The 228.6mm round pipe and the solid bar with a diameter of 20mm are even larger.

Pultrusion is the product of modern science and technology. Without computers and automatic control technology, without high-strength fibers and fast-curing resins, pultrusion technology cannot be developed; there is no demand for high-performance materials in modern industries, and there is no market for pultrusion products.

At present, the annual growth rate of pultruded products in the United States reaches 20%, which greatly exceeds the average annual growth rate of about 4% in the industry. The US pultrusion production equipment also grows rapidly, especially large pultrusion equipment, with an annual growth rate of 40%. CE is a leading company in pultrusion production and research in the United States. In addition, there are nearly 100 companies such as PI Company, Scientific research units and universities are also conducting production and research of pultrusion products. Japan's pultrusion production is also very developed. There are now 4 companies, including Ito and Yasu Trading, which provide pultrusion equipment for various material manufacturers. British molded products started late, but quickly. By 1985, 12 companies had produced pultruded products.

Now the linear speed of pultrusion has reached more than 4m / s, the maximum cross-section that can be produced is 1524mmx305mm, and it has already produced 2.4m ~ 3m. Wide product capabilities. In addition to the production of various tubes, rods, plates, I-beams, etc., various specifications can also be produced in large quantities.

Grid of corrugated tiles and kilometers of fiber optic cables.

Pull and pull equipment is almost controlled by computer, mechanically controlled pull and pull equipment is rare. Reinforced materials are still mainly composed of glass fiber and carbon fiber, and other organic, inorganic fibers and metal wire reinforced pultruded composites are in the discussion stage. The resin matrix is mainly two types of unsaturated polyester and epoxy. Other thermoplastic thermosetting resins are also used, but the amount is small. In particular, thermoplastic resins have great development prospects, and are the main development targets of pultrusion resins.

China's pultruded composite materials and research and production are still in their infancy. Beijing University of Aeronautics and Astronautics has carried out research on pultrusion technology, and Beijing 251 Factory designed its own mechanical pultrusion machine. In addition, Harbin FRP Research Institute and Xi'an Insulation

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