Plastic Extruder Screw Barrel

Product Introduction:

Screw (pinyin: luo gan) is a cylinder with a spiral groove on the outer surface or a cone with a conical spiral groove. The screw has a different head, the head is called the outer hexagonal screw. There are others, such as large flat screw, hex screw and so on.

Extruder screw can be divided into ordinary type screw, new type screw and exhaust type screw according to the screw structure and the geometric shape of the screw part. 1, ordinary screw: it is one of the most used, the most common screw, widely used in various types of extruder. According to the screw pitch and thread depth, can be divided into equal distance unequal depth type screw, equal depth unequal distance type screw, unequal distance unequal depth type screw. 2, new screw: compared with the ordinary type screw, its difference is pointed out that in the screw thread position set up some non-threaded components, such as adding the round pin, or add a thread with the original thread distance different, to improve the mixing of plastics, plasticizing effect, improve the material melting plasticizing quality, shorten the extrusion time, improve the production. Commonly used new types of screw are barrier type screw, separation type screw and split type screw three. 3, exhaust screw: it is in order to be able to successfully exclude the air in the extruded material, volatile gas and water vapor and specially designed a special type of screw.

The movement of the material in the extruder screw is divided into three sections, so the design of the screw is often segmented. Because each section is a continuous channel, so in the actual production, as long as it can meet the requirements, it is not necessary to divide the screw into three sections. In fact, some screw only has two sections, and some are not segmented. For example, when extrusion nylon this kind of crystalline material, only the feeding section and the homogenization section, the general screw extrusion of soft PVC plastic screw, can use all the compression section, and need not be divided into the feeding section and the homogenization section. The subsection type of screw obtained from experience mainly depends on the nature of the material. The length of the feeding section can be from 0 to 75% of the total length of the screw. Generally speaking, the extrusion time of crystalline polymer is the longest, followed by hard amorphous polymer and soft amorphous polymer. The length of the compression section is usually 50% of the total length of the screw, with the exception of nylon and soft PVC as described above. When extruding polyethylene, the length of homogenizing section should be 20 to 25% of the full length. But for some heat-sensitive materials (such as polyvinyl chloride), the material should not stay too long in this section, can not be homogenized section. Some high – speed extruder homogenization section length as 50%.

Plastic extruder extrusion molding with a variety of plastic, a screw can not form all the plastic. We should design the screw according to the characteristics of raw materials and consider the commonness of various raw materials as far as possible, so that a screw can extrude several plastics at the same time, which is of economic significance in industrial production. The reverse thread at the back end of the screw prevents leakage. Screw length-diameter ratio L/D, screw diameter D refers to the outer diameter of the screw thread. Effective length of screw L indicates the length of the working part of the screw. The effective length is different from the screw length. Length-diameter ratio is the ratio of the effective length of a screw to its diameter. Early extruders had smaller screw length to diameter ratios of 12 to 16. With the development of plastic molding processing industry, the length-diameter ratio of extruder screw gradually increases, commonly used for 15, 20, 25, up to 43. Increasing length-diameter ratio has the following advantages: 1, screw pressure is sufficient, the physical and mechanical properties of products can be improved. 2.,the material is plasticized well and the product appearance is of good quality. 3,extrusion capacity is increased by 20-40%. At the same time, the characteristic curve of the screw with large length-diameter ratio has small slope, relatively flat, and stable extrusion amount. 4, conducive to powder molding, such as PVC powder extrusion pipe. But increasing the length-diameter ratio makes it difficult to manufacture the screw and assemble the screw and barrel. Therefore, the aspect ratio cannot be increased without limit.

Our company has been engaged in the screw industry for more than ten years, specializing in the design and manufacture of various specifications, models, purposes of the screw barrel, according to the customer’s product design of different proportions, specifications. Our company strictly selects alloy steel, after tempering, tempering, precision machining, nitriding & bimetal treatment, the company introduces foreign high-tech, research and development of nickel base alloy, cobalt base alloy screw barrel, high wear resistance, strong corrosion resistance, high hardness, with a value of service life, and undertake all kinds of mapping, design of old screw barrel back to new, repair and other businesses. Welcome new and old customers to inquire and exchange guidance. TEL/Wechat /WhatsAPP:+86 135 6767 2668 Email:[email protected]

Product advantages:

1) High temperature resistance, no deformation at high temperature;

2) Wear resistance, long life;

3) Corrosion resistance, corrosive materials;

4) High strength, can withstand large torque, high speed;

5) Good cutting performance;

6) Small residual stress and small thermal deformation after heat treatment.