Study of the manufacturing technology of an ejector with an internal cavity made of polymer material
Ejectors are very efficient devices, paired with a pump, to transfer kinetic energy from one medium moving at high speed to another. Ejectors are mainly designed to transfer various liquids with varying degrees of aggressiveness of the medium. Therefore, the surface of the ejector body is made of materials resistant to corrosion, diffusion, chemical degradation, etc. In the case of forming an ejector by extrusion of a polymer material, surface and internal defects often occur in finished products. This leads to an increased percentage of defects in finished products, as well as to a decrease in the quality of ejectors and a decrease in their service life. To identify the parameters of the technological process in this study, a number of laboratory tests were carried out. In the first experiment, the inner cavity of the ejector was filled with high-pressure polyethylene at an extrusion temperature of 120 ± 5 °C; but with heating of the mold 80 ± 5 °C, in the fourth - with the adjustment of the design of the base of the ejector to the profile of its inner part. The test results show that various defects are present on the surface and in the depth of the material: cracks, air cavities, material retractions. As a result of an experimental study, it was possible to establish that high-pressure polyethylene mixed with polypropylene is most suitable for the manufacture of the inner part. To obtain a high-quality product, it is necessary to reduce the cooling rate of the polymer material, reduce the volume of extruded material by optimizing the design of the metal part of the ejector.