Casting method of low temperature-resisting hard sealing check valve casting

Abstract

The invention provides a casting method of a low temperature-resisting hard sealing check valve casting. The casting method comprises the following steps of: 1, preparing the mould; 2, sand-discharging, core-making and modeling; 3, drawing, shaping; 4, applying a temperature-resistant coating, baking a casting mould; 5, core-matching and mould-assembling; 6, making a quantitative shifting type sprue cup and a conical plug, wherein the capacity of the quantitative shifting type sprue cup is slightly more than the pouring weight of molten iron; 7, placing the sprue cup; 8, melting the molten iron; 9, rapidly analyzing materials of the molten iron before pouring; 10, pouring the molten iron; 11, pouring a test block, analyzing a sample block; 12, insulating the casting mould; and 13, mould-disassembling and cleaning. According to the casting method, the product defect caused by an existing casting process can be effectively eliminated, the production quality of the low temperature-resisting hard sealing check valve casting is improved, and the casting cost is lowered.

Description

technical field [0001] The invention relates to the field of casting, in particular to a casting method of a low-temperature-resistant hard-sealed check valve casting. Background technique [0002] Hard-sealed check valves are widely used in seawater desalination treatment and industrial sewage treatment systems. The characteristics of the product need to be resistant to corrosion, impact, wear of various fluid media and the influence of various harsh weather conditions. It has low temperature resistance and high temperature resistance. Under special conditions, it will not affect the performance and other characteristics of the product. Traditional casting generally adopts the sprue to connect the annular runner and distribute the pouring method, and the top of the three flanges adopts the casting process of setting a large riser and strong feeding. There are deficiencies in the production of its method: [0003] ①The position of the sprue is placed too long, the time for...

AI Technical Summary

Problems solved by technology

[0003] ① The position of the sprue is placed too long, the time for the molten iron to pour into the mold is too long, and the time of contact with the air is too long, which will easily cause the formation of an oxide layer on the surface of the casting

[0004] ②At the sprue, the molten iron rushes directly into the runner, which is easy to suck in impurities and accumulate on the upper part of the mold and at the concave and convex dead corners, resulting in casting defects

When the molten iron enters through the ingate at the annular part, it is easy to produce molten iron splash and form iron beans. The upper and lower spaces of the mold enter the molten iron at the same time, which is not conducive to exhaust and slag discharge, and easily causes subcutaneous needle-like pores, cold shut, Wrinkled skin, slag inclusion and lack of meat caused by low pouring temperature

[0005] ③Adopt the cold iron method and set it in the thick and large cross-section casting mold. Because the surface treatment of the cold iron is not clean, such as rust, sand, slag holes, etc., the use of the cold iron is not strictly managed, and the chilling of the cold iron is lost or reduced. On the contrary, it will cause the thick and large section of the casting, which is prone to increase the tendency of defect parts (such as shrinkage, porosity, and holes)

[0006] ④The method of connecting the sprue to the annular sprue increases the amount of sand used in the mold and increases the production cost

[0007] ⑤Using a large riser to feed the castings increases the production cost and at the same time makes it difficult to clean the castings. Hammering with an iron hammer can easily cause casting defects. Cutting with flames will cause uneven hardness of the castings. Thermal stress is generated, and it is easy to deform after machining, which affects the dimensional accuracy

[0008] The above-mentioned shortcomings are likely to cause the castings of hard-sealed check valves to directly affect the use function or cause scrapping due to the existence of defects, which greatly affects the production quality of hard-sealed check valves castings and increases the manufacturing cost.