2021-11-23 10:27:12 Source: sand dredge pump-slurry pump parts-China Do Pump
What are the casing technologies of dredging pump impeller? Dredging impeller is the heart of sand dredging, which is designed with abrasive, high efficiency, long durable working life etc, however, without high technology of casing progress, the impeller is failed on what it should be, therefore, China Do Pump which is a professional manufacture of sand dredging pump is sharing what are the casing technologies of dredging pump impeller in this chapter.
After the impeller is cast for 3 hours, the weight is removed. After 24 hours, the sand around the shaft head riser is loosened. After 3 days, the upper box is loosened. After 15 days (generally the temperature drops below 250 ℃), the casting is out of the box. bump. The castings are shot blasted after cleaning the drape seams, fins, etc., and then annealed. After the annealing is completed, the castings are further cleaned, and the pouring riser is removed, and then quenching and tempering are performed. (7) Other process parameters and operating points: Alkali phenolic resin sand molding, the pattern is made of glass fiber reinforced plastic, the draft angle is 1.5°, and the casting shrinkage rate is 2%. Operating points: ①The proportion of new sand used in modeling should account for 35% to 40%, and the core iron should be wrapped with a sufficient amount of straw rope to ensure the concession of the sand core, and a vent hole should be opened in the middle of the sand core. ②Use refined silica sand to pound the neck of the riser tightly. ③The coating on the working surface of the casting, including the runner and the riser seat, should be applied tightly and evenly, with a thickness of 2mm, especially the arc part of the blade root should ensure the quality and thickness of the painting. ④ After pouring, make supplemental pouring on the shaft head riser after 5-10 minutes, and add heat-generating covering agent. ⑤There should be a number of straw ropes between the location of the box and the lower box to facilitate the discharge of gas, and all the air-entraining straw ropes should be led to the outside of the box. ⑥ The gap of the 5 blades should be adjusted evenly when assembling the core.
After the process design is completed, we are most worried about the stress of the impeller casting. Because the CAE software does not have the function of calculating, analyzing and predicting the stress of the casting, the artificial auxiliary analysis of the stress of the casting is now carried out from the perspective of the temperature field of the casting CAE software, as shown in Figure 4 and Figure 5. It can be seen from Figure 4a and Figure 4b that the temperature in the high temperature zone at the root of the shaft head is 1364°C, and the temperature in the low temperature zone of the drive side cover is 1345°C (the edge of the cover is about 1280°C, which has no substantial effect on the position of the shaft head). The temperature difference is about 20°C; Figure 5 shows the temperature field cooled to about 300°C, and the difference between the central part and the outer part of the middle is only 20°C. According to the previous calculation results of the conventional impeller of our company, the temperature difference between the two is 70～80℃. The temperature difference is smaller than the conventional one because the process measures that are conducive to the uniform temperature distribution are taken in advance, which minimizes the tendency of thermal stress caused by the excessive temperature difference.
According to the established process, the first batch of two productions was implemented. After boxing and cleaning, the castings were found to have good appearance, no cracks, no shrinkage or porosity in the riser, and the size measurement was also qualified. After magnetic particle non-destructive testing, the internal structure of the castings was dense and no defects. After the heat treatment, the hardness measured at multiple points is above 50HRC, and the user is satisfied with the quality of the casting after inspection. Since then, our company has produced more than a dozen such castings, the quality has been relatively stable, and the products have been recognized by users and the market.
According to the characteristics of the wall thickness disparity on the impeller structure of this kind of dredging pump, this paper analyzes in detail the problems that may occur in the production. Through reasonable selection of material composition and establishment of reinforcements, the stress of the casting is well controlled, and the production is successful. We have produced qualified impeller castings and accumulated a lot of useful production experience, which provides a strong technical guarantee for our company to expand the dredging product market.
