The material of the corrosion-resistant and wear-resistant plastic pump is steel-lined plastic, and the lining material used is ultra-high molecular weight polyethylene. This material has good corrosion resistance and wear resistance, so the pump has superior corrosion resistance and wear resistance. High cost performance and a wide range of uses. However, ultra-high molecular weight polyethylene has low melting index and poor melt flowability, and it is difficult to form in the plastic-lined pump casing (see Fig. 1) because the shape of the pump casing is complicated, especially the outlet portion of the pump casing, and the center point of the compression mold. Farther, the plastic mold is often used to make the pressure difficult to transfer to the exit part when pressing, and it is impossible to obtain a complete, ideal and dense plastic layer.
The common pump casing lining plastic mold (see Fig. 2) is a lining pump casing casting as an outer mold, and then a positioning mold sleeve 1 and a stamper 2 and an upper pressing plate 6 are added on the pump casing flow passage cavity, and the bottom mold 3 and The lower plate 5, the outlet portion is composed of an outlet mandrel 7, an outlet platen 8, and the like. When the lining, the lining plastic is quantitatively added into the pump casing cavity, and after heating the mold to be melted by the plastic, the mold is pressurized, and after being cooled, the mold is released to obtain a complete lining plastic centrifugal pump casing. Such a mold can meet the requirements of lining plastic for some plastics with high melting and good meltability in the lining. However, for ultra-high molecular weight polyethylene, such a material with low melting point and poor melt flowability cannot meet the requirements. If a modification method such as incorporating low molecular weight polyethylene or a fluidity improver is used to increase the melting index and increase the fluidity, Adapting to the requirements of plastic forming, it greatly reduces the performance of the raw material lining plastic layer, and brings certain restrictions and influences on the use.
In order to overcome the shortcomings of the above-mentioned molds, after repeated research, a pump casing lining mold specially designed for this material was designed (see Fig. 3). The mold mainly adds a lining plastic molding device at the exit portion of the original mold, so that the pump chamber cavity and the outlet portion are respectively molded under the respective molding devices, and the lining of the pump casing is completed at one time. The specific structure of the mold is to mold the pump casing casting 4 as an outer mold, and the mold sleeve 1 is mounted on the joint with the mold. The mold sleeve is provided with a stamper 2 and an upper press plate 6, and the upper press plate 6 is a stamper. Molding is provided to the limit of the position to ensure the thickness of the plastic layer at the bottom of the pump chamber. An outlet die sleeve 8 is externally connected to the outlet portion of the pump casing, and a pump outlet mandrel 7 and an outlet die 9 and a pump outlet screw thrusting head 10 are housed in the outlet die sleeve 8. The function of the outlet die sleeve 8 is mainly as a pump outlet lining the plastic cylinder, and at the same time, the screw propulsion head 10 is coupled. When lining plastic, quantitatively insert the plastic lining plastic, heat the mold, and when the plastic melts, pressurize the pump cavity and the pump outlet die at the same time, press the press when the pump cavity is pressed, and press the outlet die. Rotate the screw to advance the indenter. After forming, remove all the external parts on the pump casing to obtain a complete and dense plastic-lined pump casing.
The improved mold has adopted a molded structure in two directions. Compared with the original single-directional lining plastic mold, the yield is high, the density and chemical stability after lining plastic are good, and the product performance is guaranteed, which brings great Good economic benefits.
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