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Mold is the key factor affecting the quality of UHMWPE pipe

UHMWPE pipe is the most widely used pipe at present because of its strong performance advantages. There are three main factors affecting the quality of UHMWPE pipe, of which mold is the most critical factor

1. Raw materials are the core

in the production of UHMWPE pipes, the core of raw materials is molecular weight. Theoretically, A. is the fixture convenient and safe to use? The higher the molecular weight of raw materials, the better the wear resistance. However, as a wear-resistant pipe, other mechanical performance indicators and its long-term stability should be considered. Therefore, raw materials with high molecular weight may not be able to produce UHMWPE pipes with good comprehensive performance, which depends on mold equipment and processing technology. At present, the processing technology of UHMWPE pipe has not been standardized, and there are great differences among manufacturers. Mainly on mold structure and process control. Therefore, the produced UHMWPE pipes are not different on the surface, but there is a big gap in indicators. Empirical things here still account for a large proportion

the raw material of UHMWPE pipe is elastomer when extruded, and the fluidity is zero, so it is difficult to extrude. At present, the core structure of the extruder is that the screw barrel has a full traffic slot, the screw is shallow thread, and the screw has a small rise angle; The core of its theory is to increase the thrust of the screw as much as possible and reduce the bonding of raw materials with the barrel and screw. The squeezing force is about 400 kg. Because of the high pressure in the extrusion process of polyethylene pipes, it is difficult to extrude thin-walled pipes, and the die is easy to deviate. Therefore, the mold is very important

2. Mold

the production mold of UHMWPE pipe is the key factor affecting the quality of UHMWPE pipe, because:

① if the design of mold compression ratio is unreasonable, it will lead to difficult extrusion of pipe, or insufficient compactness, poor pressure resistance and low mechanical performance

the development guide for new material industry jointly formulated by the Ministry of industry and information technology, the national development and Reform Commission, the Ministry of science and technology and the Ministry of finance has been officially issued recently. ② the flow channel is blocked, the raw materials are degraded too much in the extrusion process, and the performance of UHMWPE pipes is degraded

③ the structure is unreasonable, the plasticization is not good, or the fusion is not good, and the pipe is easy to crack

④ unreasonable structure, large extrusion fluctuation and difficult operation

the production operation of UHMWPE pipe is mainly based on experience, and the main reason is that the mold design is unreasonable. A good mold design will achieve the following results

① good operation and stable production. As long as the temperature does not change greatly, the appearance of the pipe will not be affected by the change of the external ambient temperature

② good internal indexes of pipes mainly refer to the compactness of UHMWPE pipes and the degradation of raw materials

3. Extrusion process

the extrusion process of UHMWPE pipe is also critical to the internal performance of the pipe. UHMWPE pipes with different molecular weights should have different processing and extrusion temperatures. When the molecular weight is 2.5 ± 500000, the plasticizing temperature should be about 240 degrees. It not only has the functions of microcomputer control, full digital closed-loop and graphic display lamp, but also has bumps on the surface of the pipe and poor plasticization; If it is too high, the pipe is easy to get out, but the degradation is increased; The specific temperature of each material should be summarized by experience. For the same raw material, generally one mold will cause abnormal operation of the machine, and the tool should be adjusted and set to a suitable temperature. Therefore, in order to produce high-quality UHMWPE pipes, raw materials, molds and processing technology are the three core technologies

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