Part of the section:Design of Novel Screw for Plastics Extruder__Building Block Screw（Plastic science and technology NO.1005.3360 ）
The screw is the main working part of the extruder, which is called the "heart of the extruder". The structure and parameter design of the screw directly affect the performance of the equipment. The main parameters of the extruder screw are the diameter of the screw, the ratio of length to diameter and the ratio of compression. The new screw is composed of 3 parts： the shaft , the building block screw and pull bar, as shown in Figure 1.
The design of the building block screw is mainly based on several stages.
1 feeding section: the role of this segment of the screw is to transport and compact the glass material forward. Therefore, this section is designed as a hollow screw thread Luan equidistant etc..
2 melting section: the function of this section is to melt the material under the heat and compacted completely into the flow state and send it to the measuring section. This physical change is to make the material pressure by changing the ratio of the volume of the screw.
Realized. Therefore, this section to design into a series of deep pitch thread or thread block type variable offset Luan hollow screw section, according to the characteristics of products and production materials, to select the desired aspect ratio and compression ratio of modular hollow screw section of collocation and combination, the plasticizing and compression. This material. The pitch of the hollow screw segment is designed to be 30mm~lJ85mm, and the ratio of length to diameter is adjusted arbitrarily between 24 and 30. In order to facilitate assembly, the sleeve is also made into a building block. When the length of the screw is changed, the length of the sleeve also changes. When working, the material can be formed only by moving the head part of the machine.
3 metering section: the selection of the pitch is mainly determined by the compression ratio required by the material. According to the requirement of the product, the hollow screw section is designed into equal depth and equal distance thread.
The working principle of building block screw is: when processing different plastic products, according to the characteristics of materials and product quality requirements, we need to match and assemble hollow screw segments on the mandrel so as to achieve the long diameter I:L~u compression ratio required by materials.
4 mixing section: the advantage of the building block screw is that the mixing element can be added at will to change the type of the screw. The mixing elements of traditional screw and screw are integrated, and the mixing elements are also made into building blocks. The building blocks mixing elements can be chosen according to the characteristics of materials. For example, in order to enhance the plasticizing and homogenizing function of the screw, a barrier type mixing element is usually set up in the metering section. The experience shows that the screw with the barrier section is superior to the ordinary screw for the output, quality and single consumption of the plastic products. The addition of these building blocks can make the screw more functional and be more conducive to the extrusion of high quality plastic products.
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