Extruder and auxiliary equipment​

日期:2022/8/3 8:47:33 / 阅读: / 来源:本站

Extruder and auxiliary equipment
    Extruder is the main equipment of plastic extrusion molding production line. The main function of the extruder is to provide plasticized melt for plastic resin extrusion molding plastic products; Ensure that the production raw materials are within the temperature range required by the process, and all components are evenly mixed and plasticized fully; It provides molten materials with uniform flow and stable pressure for the forming mold, so that the plastic extrusion production can be carried out smoothly and smoothly. Auxiliary equipment refers to the equipment that requires the assistance and cooperation of other types of equipment when the extruder produces plastic products. These include the dryer for drying raw materials, the grinder for refining raw materials, the mixer for mixing various raw materials, the extrusion granulator for homogenizing the mixture, the feeding equipment for feeding the extruder, and the production line mainly composed of extruders when producing different plastic products. These auxiliary equipment are combined to form the working sequence of the feeding system in the extruder production line as follows.
3.1 extruder
3.1.1 type of extruder
    There are many kinds of extruders, and the classification methods are also different. According to the number of screws, extruders include single screw extruder, twin screw extruder and multi screw extruder. According to the functions of extruders, extruders can be divided into general-purpose single screw extruders, tandem extruders, feed extruders and step extruders. At present, the general single screw extruder and twin screw extruder are the most used in plastic products factories. Twin screw extruders are generally used to extrude profiles, pipes, plates and extrusion granulation.
3.1.2 production characteristics of plastic products formed by extruder
    Extruder equipment has simple structure, low cost, and less investment in extrusion molding production line. ② The output of products formed by the extruder is lower than ③ the production operation of the extruder is relatively simple, the product quality is easy to ensure, and the production cost of products is relatively low. ④ The extruder production line covers a small area and the production environment is relatively clean ⑤ the extruder has a wide range of applications, which can not only extrude plastic products, but also be used for the mixing, pre plasticization, granulation and feeding of raw materials. ⑥ The length of plastic products produced by the extruder can be extended indefinitely as needed.
3.1.3 types of extruded plastic products
    ① It can continuously extrude plastic products with different cross-section geometry, such as film, sheet, plate, hard pipe, hose, bellows, profile, wire, cable, packaging belt, rod, net and composite materials. ② It can periodically and repeatedly produce hollow products, such as bottles, barrels, etc.
3.1.4 working principle of extruded plastic products
According to the formula requirements of plastic products, the evenly mixed raw materials are sent into the barrel through the hopper of the extruder. With the rotation of the screw, the raw materials are forced to the front of the barrel. Due to the resistance of the filter screen, perforated plate and forming mold in front of the barrel, and the gradual reduction of the screw thread volume on the screw, the pressure of the raw materials in the barrel is gradually increased. At the same time, the raw materials are also affected by the heat supply outside the barrel. Under the action of extrusion, shear and mixing, plus the friction between the raw materials and the barrel and the threaded working surface, as well as the friction between the raw materials molecules, the temperature of the raw materials in the barrel is gradually increased, Its physical state also gradually changes from glass state to high elastic state, and finally becomes viscous flow state, reaching complete plasticization. As the screw keeps rotating, the uniformly plasticized molten material is extruded from the mouth of the molding die in equal pressure and equal amount to become plastic products. After cooling and shaping, the extrusion of plastic products is completed.
3.1.5 single screw extruder
3.1.5.1 structural features
    Single screw extruder is the most widely used general-purpose extruder in the extruder product series. Its structural feature is that the extrusion system of the extruder is composed of a screw and a barrel. Single screw extruder is widely used. For the extrusion of different thermoplastics, as long as the structural form of the screw is changed, the production of extruded products with different raw materials can be completed; The equipment structure is relatively simple, the cost is low, and the operation is easy to master. The machine is SJ; Plastic exhaust extruder is SJP; The plastic foaming extruder is SJF; The plastic feed extruder is SJW; The extruder for plastic shoes is sje; Step type plastic extruder is SJJ; Twin screw extruder is sjs: conical twin screw extruder is sjsf; The multi screw extruder is SJD. The fourth box represents editing machine, code f; If it is an extrusion unit, the code is e. The fifth parameter refers to the screw diameter and the length diameter ratio of the screw. The sixth box refers to the design sequence of products, which is arranged in the order of letters a, B, C, etc. the first design is not marked with the design number. For example, sj-45x25, this model means: plastic extruder, screw diameter is 45mm, and the length diameter ratio of screw is 25:1. Do not mark when the length diameter ratio of the screw is 20:1.

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