As plastic transparent tube
DATE：2022/3/22 8:51:39 / READ： / SOURCE：This station
As plastic transparent tube
1. Selection of raw materials(1) At present, as resin has many brands of s Resin in the market, with great performance differences. After many tests, it is determined that the performance index of the resin meeting the production requirements of as transparent tube is: light transmittance ≥ 90%; Impact strength > 2.0kj/m2; Melt flow rate 2 ~ 4G / 10min; Processing temperature 170 ~ 180 ℃.
(2) S resin is used alone in the production of additives. The processing temperature is very high, and the cooling and shaping of products is not easy to control; On the other hand, uneven plasticization occurs on the product surface, resulting in uneven product surface and refraction. Therefore, high-efficiency lubricants and special processing aids must be added to ensure that as resin has better processability and the smoothness and brightness of products.
2. Selection of production equipment and mold making (1) selection of production equipment. According to the size of the system, the mass of s plastic pipe is about 300g / m. If the output is 1m / min, the hourly output is 18-20kg / h. Therefore, the single screw extruder with screw diameter of 45mm and length diameter ratio of 25:1 can meet the requirements of raw material plasticization and production.
2. Mold making
1) Mold parameters. The fluidity of as plastic is worse than that of ABS, and the outlet expansion is also smaller. In the process of mold manufacturing, several key parameters are tested and compared repeatedly, and finally a group of ideal parameters are determined:
① Fixed length of die lip: die lip thickness = 30:1, product thickness: die lip thickness = 1.1:1: ② product circumference: die lip circumference = 1:1.2
2) Hardness and coarseness of die materials. As resin has high viscosity and is easy to stick to the mold. It is easy to form wire marks on the surface of the pipe, which affects the transparency and mechanical properties. Therefore, there are high requirements for the selection of surface roughness and hardness of die materials. The die is made of Q235 steel and heat treated with 50HRC, and the surface is plated with hard chromium and polished; The setting die is heat treated with 3Cr13 and 280 ~ 290hbs, so that the processed pipe has good surface smoothness and high dimensional accuracy.
3. Production process
(1) Process flow: drying of raw materials → extrusion → dry vacuum cooling and shaping → wet vacuum cooling and shaping → fixed length cutting → finished products.
(2) Process control
1) As plastic must be dried, otherwise there are silk marks or bubbles on the surface of the product. The drying hopper is used for drying, the temperature is 100 ~ 105 ℃, the air is blown, and the material is fed automatically.
2) Extrusion temperature control, die: 170 ℃; Machine profile: 180 ℃; Feeding port: 150 ℃. 3. Screw rotation: 40 ~ 45r / min. 4 drawing speed, im / min.
5) The cooling mode adopts dry and wet vacuum series shaping.
Dry vacuum cooling shaping is to ensure that the product has sufficient accuracy, and wet vacuum cooling shaping is to ensure that the product has sufficient output. Two series cooling methods are adopted to ensure the dimensional accuracy of products and high production capacity at the same time.
Author：admin