Casting method of large thin-walled valve body castings

Abstract

A casting method for a large thin-wall valve body steel casting comprises the following steps: 1, manufacturing a composite physical model: manufacturing an upper half valve body external mold, a lower half valve body external mold, the overall frame of a second core box, and an irregular-shaped section template; filling a mixed filler between the frame and the section template; tamping, smoothly trimming the filler; performing natural curing after the dimensional requirement is met; 2, sand mulling; 3, modeling and core manufacturing; 4, painting, mounting the core, and combining boxes; 5, smelting and casting; 6, performing post-treatment. The large thin-wall valve body steel casting is prepared through the steps. The casting method adopting the composite model can improve the model manufacturing efficiency, saves wood, and reduces the model manufacturing cost; through the adoption of stepped flat ingate system, as well as the manner that a chiller, a riser and compensation are combined, the thin-wall valve body steel casting is protected from fracture, insufficient casting, cold shut, wrinkling, and other casting defects, so as to realize the sequential solidification of the valve body steel casting, and meet the technical requirement of the valve body steel casting.

Description

technical field [0001] The invention relates to a casting method, in particular to a casting method of a large thin-walled valve body casting. Background technique [0002] Large thin-walled valve body castings are key castings for hydraulic machinery and equipment. The length, width and height are 2050mm×1750mm×1000mm. There are three-direction connecting water pipe flanges on the shape, and 16 water-guiding arc-shaped plates in the inner cavity ( 14) and 16 upper and lower shaft-hub connection columns (15), see Figure 4 , Most of the water cavity and shape are irregular linear, the main wall thickness is 32mm, and the mass is 4100kg. It requires magnetic particle testing and ultrasonic testing of the flange surface to be class II, and other blank surfaces require magnetic particle testing class III. [0003] Under the existing technical conditions, the model production needs to use wood to make the actual casting sample and the shape structure of the core box, and then us...

AI Technical Summary

Problems solved by technology

Making models in this way not only consumes a lot of wood, but also requires a lot of manpower and a long construction period

[0004] The surface area of ​​the steel casting of the valve body is very large, while the section wall thickness of the water chamber is only 32mm. Under the existing technical conditions, the circular inner sprue with bottom injection is adopted, the pouring temperature is 1550±15°C, and the riser method is set on the top surface. The water chamber of the casting Defects such as insufficient pouring, cold shut, and wrinkle are prone to occur on the surface far away from the ingate and riser, while crack defects are prone to occur at the junction of the ingate of the casting due to overheating of molten steel and poor feeding channels

If these defects are within the scope of the repair standard, they need to be treated by grinding, magnetic particle inspection, carbon planing, welding repair, etc., and when the defects exceed the standard, quality accidents that lead to the scrapping of castings will occur

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