Method for cutting riser and patch of ball valve casting with shaft
A cutting method and casting technology, applied in the direction of furnace type, furnace, heat treatment equipment, etc., can solve problems such as cutting and cracking of ball valves with shafts, achieve the effects of shortening the production cycle, improving the quality of castings, and reducing the welding repair rate
Pending Publication Date: 2021-11-12
KOCEL STEEL
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Problems solved by technology
[0004] The purpose of the present invention is to solve the problem of cutting and cracking of ball valves with shafts in the prior art, and to provide a cutting method for ball valve castings with shafts whose thickness exceeds 900 mm for the riser subsidy in the cavity, so as to reduce the risk of cracks in the subsidy area of the thick and large riser and achieve cutting After the purpose of no crack generation
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Embodiment Construction
[0020] In order to facilitate the understanding of the present invention, the following will describe the present invention more fully. The preferred embodiments of the present invention are given. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.
[0021] In this embodiment, the riser subsidy thickness of the ball valve with shaft is more than 900mm and the weight is more than 50 tons as an example. Since the effective thickness of the shaft part of the ball valve with shaft and the contact part of the ball valve reaches more than 1000mm during casting, in order to ensure the casting quality, in the inner cavity of the ball valve Place 800mm ~ 1000mm thick subsidy. For this reason, for this kind of thick subsidized castings, medium temperature preheating is...
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The invention belongs to the technical field of casting riser cutting, and mainly relates to a method for cutting a riser and a patch of a ball valve casting with a shaft, which is characterized in that secondary cutting repair is carried out after preheating process optimization, cutting process step control and performance heat treatment, and the influence on a casting body caused by serious cracks generated by one-time in-place cutting is completely eradicated, wherein the preheating temperature ranges from 550 DEG C to 600 DEG C, the casting stress is effectively reduced, meanwhile, the structure is softened, the cutting thermal stress is reduced, and a cutting part is prevented from cracking. After performance heat treatment, when the temperature of a casting is reduced to be greater than or equal to 200 DEG C, secondary repair cutting allowance is reserved, and low-temperature stress relief is performed at 450-500 DEG C after repair. By the adoption of the cutting method for the riser and the patch, cracks generated after the thick and large riser and the patch of the ball valve with the shaft are cut off can be effectively avoided, the repair welding rate or the scrap loss caused by the extra-large crack defect is reduced, the casting quality is remarkably improved, the production period is shortened, and the cost is saved.
Description
technical field [0001] The invention belongs to the technical field of cutting risers of castings, and mainly relates to a method for cutting risers and subsidy of castings of ball valves with shafts. Background technique [0002] Due to the large tonnage and complex structure of valve body castings with shafts, it is difficult to cast them. Especially in the casting process, extra large risers and subsidies need to be added to some thick and large structures of castings. The thickness reaches more than 900mm. Before heat treatment, the thicker the larger part, the more serious the segregation of the composition, plus the combined effects of various unfavorable factors such as poor as-cast plastic toughness, uncertain defects under the riser subsidy, and the influence of casting stress. Once thermal stress occurs, the risk of cracking is extremely high, and cracks are easy to occur, which will have a huge impact on the quality and cost of castings. If it is light, it will fa...
Claims
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IPC IPC(8): B22D31/00C21D1/28C21D1/30C21D9/00
CPCB22D31/00C21D1/28C21D1/30C21D9/0068C21D2261/00Y02P10/20
Inventor 纳学洋冯周荣郭小强马进晁博嗣
Owner KOCEL STEEL