There are many factors in the production process of the pipe of the bellows production line that will affect the final quality of the pipe. Therefore, in order to ensure the overall quality of the pipe, we need to master the following methods:
1. The selection of screw speed depends on the size of the extruder. The size of the screw depends on the size of the pipe, the speed is added, the amount of extrusion is added, and the shearing force of the material is large, which helps the plasticization of the material, but the material. The residence time in the screw is short, the excessive frictional heat makes the inner wall of the pipe rough and the strength of the pipe decreases. Therefore, the control of the screw speed should be balanced according to the output value, the appearance of the product and the physical and mechanical function requirements.
2. Selection of materials There are many kinds of standard trademarks for pipes. Numerous kinds of raw materials of the same trademark can produce HDPE double-wall corrugated pipes but can not produce PE water supply pipes. Here, it is still necessary for manufacturers to identify themselves, select suitable pipe materials, and test the material function at the time of selection.
3. Compressed air and traction speed Compressed air to shape the tube and maintain a certain degree of roundness, the pressure is usually 0.02 ~ 0.05mpa, and the traction speed should be matched with the extrusion speed, usually the traction speed is 1% higher than the tube extrusion speed ~10%. The structure of the double-wall corrugated pipe extrusion die is relatively complicated. The main feature is that it is divided into two inner and outer flow channels in the same mold, and the inner and outer flow channel interlayers pass compressed air to help the outer layer form ripples on the molding module. At the same time, the cooling water pipe of the sizing sleeve also passes through the core rod, and in order to compensate for the heat loss caused by the passage of the cooling water, it is generally required to heat the inner wall of the machine head. In the production of large-diameter pipes, since polyolefin pipes generally use single-screw extruders, the extrusion amount is much smaller than that of twin-screw extruders. Therefore, two extruders are used in two-layer coextrusion technology. Guaranteed production can also increase production. The forming mold of the bellows is mainly a module, which determines the basic structure and size of the pipe. The module structure is different depending on the molding method and the movement trajectory of the module. At present, most of the production lines are vacuumed by a module to adsorb the blank on the inner surface of the mold, and the module has a passage for vacuuming. Impact of the machine head on the product: Compared with the common pipe head structure, the bellows extruder head has a small die gap and a large die-to-thickness ratio. The pipe wall has a particularly long flow path and a small gap. Avoid excessive pressure and excessive shear to cause melt fracture.
4. When the unstable temperature bellows production line processes hard pvc pipe, the processing temperature and the differentiation temperature are relatively close. The material temperature at each point should be strictly controlled during production. The temperature is too low, the plasticization is not good, the temperature is too high, and the material is easy. Differentiation, temperature control should be based on the original formula, extruder and head structure, screw speed and other factors to determine, together with the temperature measurement of the appearance of the error and the position of the measurement point.