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The rubber extruder is a basic equipment of the rubber industry and is one of the key equipments that affect the product quality. It plays a very important role in the production of tires and rubber products. The development of foreign rubber extruders has experienced plunger-type extruder, screw-type hot-feed extruder, ordinary cold-feed extruder, main and auxiliary thread cold-feed extruder, cold-feed exhaust extrusion Machine, pin cold feed extruder, compound extruder and other stages.
The extruder originated in the 18th century. The manual piston extruder for seamless lead pipes manufactured by Joseph Bramah in England in 1975 was considered the world's first extruder. . Since then, in the first 50 years of the 19th century, extruders were basically used only in the production of lead pipes, macaroni and other foods, the brick-making and ceramics industries.
During the development of the extruder as a manufacturing method, the first clear record was R. B r o o m a n applied for a patent for producing Goodyear rubber wire with an extruder in 1845. H. Goodwave Bew lg y subsequently improved the extruder and used it in 1851 to cover the copper wire of the first submarine cable between Dover and Caalais. In the next 25 years, the extrusion method 13 became more and more important, and the electric extruder gradually replaced the manual extruder. The early mechanically operated plunger-type extruder produced thousands of kilometers of insulated wires and cables, thus firmly establishing the status of the extrusion method for cable production. Early cable extruders, whether manual, mechanical or hydraulic, were all plunger-type. In this production process, the plunger presses the hot Gutapo glue into the die with the copper wire, and the Gutapo glue is extruded from the die, so that it covers the copper wire to form an insulating layer.
The rubber extruder that appeared in 1870 was a hot-feed extruder. The rubber material fed by it must be hot-melted, and the material supply is uniform, stable, and constant speed, and the temperature of the material is maintained at 50 ~ 70 ° C. The screw is short, the thread groove is deep, and the homogenizing effect is not ideal. Since the 1970s. At one time, the aspect ratio became smaller. Because the hot-feed extruder can be continuously extruded, the operation is simple, the production efficiency is high, and the shape of the extruded product is stable, in many products, the hot-feed extruder is still used. It is used for the extrusion of various treads and various types of rubber in the production of tires, and for the extrusion of rubber and rubber preforms in the production of hoses, cables and other rubber products.
Cold feed extruder appeared in the 1940s, began to be popularized and popularized in the 1960s, and became the mainstream of development in the 1980s. By the early 1990s, the products produced by cold-feed extruder in developed countries such as Europe and the United States accounted for 95% of the total production. Separate screw extruder, baffle screw extruder, cavity screw extruder, transfer mixing extruder, pin screw extruder and multi-channel transfer mixing screw (MCT) extruder, etc. .
From the perspective of equipment structure, compared with hot-feed extruder, cold-feed extruder generally has a longer body, the length-to-diameter ratio (L / D) is 8-20, and the thread groove is shallow. Due to the long body, multiple functions, and low feed temperature, its power is much larger than that of a hot-feed extruder, which is about 2-4 times that of a hot-feed extruder of the same specification. For example, the cold-feed extruder with a diameter of 250ram produced by the German company Berstov has a power of 500kw, while the hot-feed extruder of the same specification has only 105kw, but its production capacity is lower than that of a hot-feed extruder . The emergence of cold-feed extruder simplifies the production process. The fed rubber material no longer needs to be hot-melted. The rubber material is fed into the extruder at room temperature to obtain the product blanks of various shapes. It can completely replace the hot-feeding extruder, and can eliminate the rubber hot-melting process, simplify the production process, and enable the head to establish a higher pressure, which has a certain effect on improving the quality of the extruded products. It has been widely used in the production of products.