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CN-122007339-A - Casting technology of vanishing film valve body

CN122007339ACN 122007339 ACN122007339 ACN 122007339ACN-122007339-A

Abstract

The invention discloses a casting process of a valve body of a lost foam valve, which comprises the following steps of S1, pre-foaming and curing expandable polystyrene particles, molding under the conditions that the mold temperature is 90-105 ℃ and the steam pressure is 0.15-0.25MPa to obtain a foam model with the same size as the valve body, S2, bonding and combining split parts of the foam model of the valve body by hot melt adhesive, polishing a splicing joint after bonding, and S3, configuring special paint for the lost foam. The valve body produced by the process has high dimensional accuracy and low surface roughness, does not need a large amount of subsequent machining, reduces the production cost, does not deform a foam model, adopts special coating, improves the high temperature resistance and air permeability of the coating, effectively reduces phenomena of air holes, sand sticking and the like, improves the filling capacity of molten metal, reduces defects of shrinkage cavity, cold insulation and the like, refines casting grains, and eliminates casting stress.

Inventors

  • PAN YUEE
  • LI JIANCHENG
  • WU XIONGZHI

Assignees

  • 江苏曜曜机械科技有限公司

Dates

Publication Date
20260512
Application Date
20260228

Claims (7)

  1. 1. A casting process of a vanishing film valve body is characterized by comprising the following steps: S1, pre-foaming and curing expandable polystyrene particles, and then molding under the conditions that the temperature of a mold is 90-105 ℃ and the steam pressure is 0.15-0.25MPa to obtain a foam model with the same size as a valve body of a valve; s2, bonding and combining foam model split parts of the valve body by adopting hot melt adhesive, and polishing a splicing seam after bonding; s3, configuring a special paint for the lost foam; The coating consists of the following raw materials, by weight, 60-70 parts of quartz powder, 5-8 parts of bentonite, 2-3 parts of sodium carboxymethylcellulose and 25-30 parts of water; S4, immersing the foam model into the paint for 10-15S, taking out, draining off the excessive paint, air-drying for 1-2h at room temperature, and then placing into a drying room for drying for 8-12h at 40-50 ℃; S5, paving dry quartz sand at the bottom of the sand box, putting the dried foam model into the sand box, carrying out three-dimensional vibration sand filling by adopting a vibration table, wherein the vibration frequency is 30-50Hz, the vibration amplitude is 0.5-1.0mm, and adding the quartz sand in the sand filling process until the foam model is completely covered, and the thickness of a sand layer is not less than 8cm; S6, pouring molten metal at 1520-1560 ℃ at a pouring speed of 0.8-1.2m/S, wherein a negative pressure pouring process is adopted during pouring, the negative pressure is controlled at 0.04-0.06MPa, and the negative pressure is maintained until the casting is solidified; S7, cooling the casting to room temperature, performing shakeout treatment to remove surface sand, performing shot blasting on the casting at the shot blasting speed of 50-60m/S, performing heat treatment at last, heating to 650-700 ℃ and preserving heat for 2-3h, heating to 900-950 ℃ and preserving heat for 3-4h, and cooling to below 300 ℃ along with a furnace and discharging to obtain the finished valve body.
  2. 2. The casting process of the vanishing film valve body according to claim 1, wherein in the step S1, the density of the foam model is 18-22kg/m3, and the surface roughness Ra is less than or equal to 5 μm.
  3. 3. The casting process of the vanishing film valve body according to claim 1, wherein the particle size of the expandable polystyrene particles is 0.2-0.5mm, the pre-foaming temperature is 80-85 ℃, the pre-foaming time is 15-20min, and the curing time is 24-48h.
  4. 4. The casting process of the vanishing film valve body according to claim 1, wherein in the step S2, reinforcing ribs are adhered to the easily deformable parts of the foam model, the reinforcing ribs are made of EPS, and the thickness is 3-5mm.
  5. 5. The casting process of the vanishing film valve body according to claim 1, wherein in the step S5, the particle size of the quartz sand is 0.8-1.2mm, the mud content is less than or equal to 0.5%, and the water content is less than or equal to 0.2%.
  6. 6. The casting process of the vanishing film valve body according to claim 1, wherein in the step S6, the molten metal is carbon steel or stainless steel liquid, and the sulfur content is controlled to be less than or equal to 0.03% and the phosphorus content is controlled to be less than or equal to 0.04% in the smelting process.
  7. 7. The casting process of the vanishing film valve body according to claim 1, wherein in the step S7, after shot blasting, surface defects of the casting are repaired, welding rods matched with the casting are adopted for repairing, and polishing and leveling are carried out after repairing.

Description

Casting technology of vanishing film valve body Technical Field The invention relates to the technical field of casting of non-valve bodies, in particular to a casting process of a vanishing film valve body. Background The lost foam casting is a near net shape casting technology, has the advantages of high casting dimensional accuracy, good surface quality, no need of parting, drawing and the like, has remarkable advantages in complex casting production, but the problems of easy deformation of a foam model, easy shrinkage cavity generation at a thick and large section and the like caused by poor air permeability of a coating still exist when the valve body of the valve is cast by lost foam casting at present, and the application of the valve body in valve body mass production is limited. Therefore, we propose a casting process of the vanishing film valve body to solve the above problems. Disclosure of Invention The invention aims to provide a casting process of a valve body of a vanishing film valve, which aims to solve the problems in the background technology. In order to achieve the above purpose, the present invention provides the following technical solutions: A casting process of a vanishing film valve body comprises the following steps: S1, pre-foaming and curing expandable polystyrene particles, and then molding under the conditions that the temperature of a mold is 90-105 ℃ and the steam pressure is 0.15-0.25MPa to obtain a foam model with the same size as a valve body of a valve; s2, bonding and combining foam model split parts of the valve body by adopting hot melt adhesive, and polishing a splicing seam after bonding; s3, configuring a special paint for the lost foam; The coating consists of the following raw materials, by weight, 60-70 parts of quartz powder, 5-8 parts of bentonite, 2-3 parts of sodium carboxymethylcellulose and 25-30 parts of water; S4, immersing the foam model into the paint for 10-15S, taking out, draining off the excessive paint, air-drying for 1-2h at room temperature, and then placing into a drying room for drying for 8-12h at 40-50 ℃; S5, paving dry quartz sand at the bottom of the sand box, putting the dried foam model into the sand box, carrying out three-dimensional vibration sand filling by adopting a vibration table, wherein the vibration frequency is 30-50Hz, the vibration amplitude is 0.5-1.0mm, and adding the quartz sand in the sand filling process until the foam model is completely covered, and the thickness of a sand layer is not less than 8cm; S6, pouring molten metal at 1520-1560 ℃ at a pouring speed of 0.8-1.2m/S, wherein a negative pressure pouring process is adopted during pouring, the negative pressure is controlled at 0.04-0.06MPa, and the negative pressure is maintained until the casting is solidified; S7, cooling the casting to room temperature, performing shakeout treatment to remove surface sand, performing shot blasting on the casting at the shot blasting speed of 50-60m/S, performing heat treatment at last, heating to 650-700 ℃ and preserving heat for 2-3h, heating to 900-950 ℃ and preserving heat for 3-4h, and cooling to below 300 ℃ along with a furnace and discharging to obtain the finished valve body. Further, in the step S1, the density of the foam model is 18-22kg/m3, and the surface roughness Ra is less than or equal to 5 mu m. Further, the particle size of the expandable polystyrene particles is 0.2-0.5mm, the pre-foaming temperature is 80-85 ℃, the pre-foaming time is 15-20min, and the curing time is 24-48h. Further, in the step S2, reinforcing ribs are adhered to the easily deformable portion of the foam model, wherein the reinforcing ribs are made of EPS and have a thickness of 3-5mm. Further, in the step S5, the particle size of the quartz sand is 0.8-1.2mm, the mud content is less than or equal to 0.5%, and the water content is less than or equal to 0.2%. Further, in the step S6, the molten metal is carbon steel or stainless steel liquid, the sulfur content is controlled to be less than or equal to 0.03% and the phosphorus content is controlled to be less than or equal to 0.04% in the smelting process. Further, in the step S7, after shot blasting, the surface defect of the casting is repaired, and the repairing is performed by using a welding rod matched with the casting material, and polishing and leveling are performed after repairing. Compared with the prior art, the invention has the beneficial effects that: The valve body produced by the process has high dimensional accuracy and low surface roughness, does not need a large amount of subsequent machining, reduces the production cost, does not deform a foam model, adopts special coating, improves the high temperature resistance and air permeability of the coating, effectively reduces phenomena of air holes, sand sticking and the like, improves the filling capacity of molten metal, reduces defects of shrinkage cavity, cold insulation and the like, refines casting grains, and eliminate