After more than 100 years of development,
plastic extruders have been derived from the original single screw twin screw, multi-screw, and even no screw. Plastic extruder (main machine) can be used with pipes, films, materials, monofilaments, flat yarns, packing belts, extruded nets, plates (sheets), profiles, granulation, cable coating, etc. Matching, forming a variety of plastic extrusion molding lines, producing a variety of plastic products. Therefore, plastic extrusion molding machines are one of the most widely used models in the plastics processing industry, now or in the future.
The development trend of plastic extruders is as follows:
(1) The extruder is developing in the direction of large-scale, high-speed and high-efficiency. It is not uncommon for a foreign extruder with a screw diameter of 200-250 mm to be a common extruder with a screw diameter of more than 400 mm. Increasing the screw diameter can increase the productivity of the extruder. When the diameter of the screw is doubled, the productivity of the extruder can be increased several times.
Another effective way to increase the production capacity is to increase the rotational speed of the screw. High-speed and ultra-high-speed extruders with a rotational speed of 300 r/min or more occur abroad, so that the productivity of the extruder is greatly improved. However, after the increase of the rotational speed, problems such as poor plasticization will be brought about, which prompts people to study and test the extrusion theory and the structure of the screw, so that many new types of screws have appeared, such as separation type, mixing type, barrier type, and split type. , combination type, etc. The aspect ratio of the screw also increased from 20:1 to 36:1, and some as high as 43:1. This is very effective in improving the quality and efficiency of plasticizing.
(2) The auxiliary equipment of the extruder has also been perfected and standardized to meet the requirements of different plastic products.
(3) Extrusion automation, using the microcomputer to test and control the process parameters of the extruder, the temperature difference can be controlled within ±1 °C. Extrusion equipment uses microelectronics technology to make plastic extrusion processing to the direction of accuracy, precision, energy saving and automation.
(4) In order to meet the requirements of new materials and new processes, new or special extruders are constantly appearing. Such as three-screw extruder and planetary multi-screw, no-screw extruder, reactive extruder, two-color extruder, foaming extruder and so on.
Today, modern plastic extruders have adopted modern electronic and computer control technology to perform on-line inspection of the entire extrusion process and use closed-loop control of the microcomputer. In order to meet the diversified needs of production development, plastic molding technology has been flourishing in the aspects of modern high-efficiency production and intelligent control.
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