A sand mold casting method for a plug valve housing

Abstract

A sand mold casting forming method of a cock valve shell relates to the technical field of sand mold casting and adopts the technical scheme of S1, determining a pouring position to ensure that the sealing surface is located on the side of the mold cavity; S2, determining a parting surface; S3, manufacturing a core and preventing the core from floating up; S4, determining the arrangement positions of a pouring system, a riser and a chill to make the valve shell sequentially solidify; and S5, drawing a process design drawing. The sealing surface and the thick part of the valve shell are located on the side of the mold cavity, defects such as slag inclusion, sand inclusion and pores are effectively avoided, the product quality is improved, and the density is also improved. The solidification sequence is fixed to prevent the valve shell from being loose and porous, and the density is improved. The core is stable and does not float up.

Description

Technical Field

[0001] This invention relates to the field of sand casting technology, and in particular to a sand casting method for forming a plug valve body. Background Technology

[0002] The plug of a plug valve can be cylindrical or conical. Rotating it 90 degrees allows the plug's passage to connect or separate from the valve body's passage, thus opening and closing the valve. In traditional plug valve casting processes, the valve body is often cast on its side, frequently resulting in shrinkage cavities and other defects on one side. This leads to a less dense structure on both sides of the valve body and defects such as slag inclusions, sand inclusions, and porosity on the sealing surface. As a result, the valve is prone to leakage after a period of use. Therefore, foundries need to address valve body quality issues to ensure product lifespan. Summary of the Invention

[0003] To address the problem of defects in the valve body and sealing surface in existing technical solutions, this invention provides a sand casting method for the valve shell of a plug valve.

[0004] This invention provides the following technical solution: a sand casting method for a plug valve housing, the valve housing comprising a valve body and flanges disposed on both sides of the valve body, wherein the bottom end of the valve body is a large volume end and the other end is a small volume end, and a sealing surface is provided inside the valve body, comprising the following steps: S1, Determine the pouring position to ensure that the sealing surface is located on the side of the cavity; S2, determine the parting surface; S3, for making the core and preventing the core from floating; S4, determine the arrangement of the gating system, risers, and chills to ensure the valve body solidifies sequentially; S5, Draw the process design diagram.

[0005] Preferably, in step S1, the valve body is cylindrical, the inner wall of the valve body sidewall is the sealing surface, and the casting position is determined so that the valve body sidewall is located on the side of the cavity.

[0006] Preferably, in step S1, the pouring position is as follows: the central axis of the valve body is set vertically, the central axes of the two flanges are set horizontally, and the large volume end is oriented towards the lower part of the mold.

[0007] Preferably, in step S2, the mold is divided into an upper mold and a lower mold using the horizontal plane where the center axis of the flange is located as the parting plane.

[0008] Preferably, in step S3, a core is made according to the shape of the valve housing cavity. The top, bottom, and two protruding parts of the core are all provided with core heads. The core head at the top of the core mates with the upper surface of the inner wall of the upper mold, and the core head at the bottom of the core mates with the bottom surface of the inner wall of the lower mold.

[0009] Preferably, limiting cavities are also provided on both sides of the cavity, and the core head located on the protruding part on both sides cooperates with the limiting cavity.

[0010] Preferably, in step S4, two low ingates are provided on both sides of the bottom of the flange, and the four low ingates are connected.

[0011] Preferably, in step S4, risers are provided on both sides of the top of the two flanges and on both sides of the valve body.

[0012] Preferably, in step S4, a plurality of chills are provided at the bottom of the large volume end, and chills are provided at the top and bottom of the two flanges on the side away from each other.

[0013] Preferably, in step S4, a pipe connection is provided between the valve body and the flange, and the pipe connection is provided with a plurality of chills along its circumferential direction.

[0014] The beneficial effects of this invention are: redefining the casting position so that the sealing surface and the thick part of the valve body are located on the side of the cavity, effectively avoiding defects such as slag inclusion, sand inclusion, and porosity, improving product quality, and also contributing to increased density; by using chills and risers, the bottom of the valve body and the thinner pipe connection part are cooled first, while the top of the thicker part such as the side wall of the valve body is cooled last, causing shrinkage cavities to shift to the riser, preventing the valve body from shrinking and becoming loose, and improving density; the upper surface of the inner wall of the upper mold cooperates with the core head at the top of the core, which can prevent the core from floating. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of one embodiment of a plug valve.

[0016] Figure 2 This is a cross-sectional view of one embodiment of a plug valve.

[0017] Figure 3 This is a schematic diagram of an embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram of an embodiment of the present invention.

[0019] Figure 5 This is a schematic diagram of the core according to an embodiment of the present invention.

[0020] Figure 6 This is a schematic diagram showing the positions of the riser and chill in one embodiment of the present invention.

[0021] Reference numerals: 10, valve body; 11, large volume end; 12, small volume end; 13, sealing surface; 14, passageway; 20, flange; 30, pipe connection; 40, core; 41, core head; 51, low ingate; 52, chill; 53, riser. Implementation

[0022] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and reference numerals, so that those skilled in the art can implement them after reading this specification. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0023] Please refer to Figure 1 The valve body of the plug valve includes a valve body portion 10 and flanges 20 disposed on both sides of the valve body portion 10. The valve body portion 10 and the flanges 20 are connected by a pipe connection portion 30. The valve body portion 10 is generally cylindrical, with a large volume end 11 at the bottom and a small volume end 12 at the other end. The inner wall of the valve body portion 10 is a sealing surface 13. After a cylindrical or conical valve plug is installed inside, the valve plug mates with the sealing surface. By rotating 90 degrees, the valve plug passage opening is connected to or disconnected from the passage opening 14 of the valve body portion, thereby opening and closing the valve. Please refer to... Figure 1 , 2 The valve body 10 and flange 20 have thicker walls and larger volumes than the pipe connection 30. In the prior art, valve body casting generally adopts a side-lying casting position, which leads to shrinkage porosity and shrinkage defects on one side of the valve body 10, and slag inclusions, sand inclusions, and porosity defects on the sealing surface 13.

[0024] This invention provides a sand casting method for forming a plug valve body, comprising the following steps: S1, Determine the casting position. In this embodiment, the casting position of the valve body is specifically as follows: the central axis of the valve body 10 is set vertically, the central axes of the two flanges 20 are set horizontally, and the large volume end 11 faces the lower part of the mold. One advantage of this is that the thick parts such as the side wall of the valve body 10 and the flanges 20 are all located on the side of the mold cavity, and the sealing surface is also located on the side of the mold cavity, effectively avoiding defects such as slag inclusion, sand inclusion, and porosity, improving product quality, and also contributing to improved density. During the cooling process, the gas and slag inside the molten steel float to the surface, but have a slight impact on the thick parts on the side and the sealing surface.

[0025] S2, Determine the parting surface. Using the horizontal plane containing the flange's central axis as the parting surface, the mold is divided into an upper and lower mold. This simplifies the casting process, reduces errors, and facilitates mold removal. Please refer to the schematic diagram. Figure 3 , 4 .

[0026] S3, determine the core. Please refer to... Figure 5 A core is manufactured according to the shape of the valve body's inner cavity. The core 40 has a core head 41 at its top, bottom, and both protruding sides for positioning and support. The core head 41 at the top mates with the upper surface of the upper mold's inner wall. When the mold is closed, the upper surface of the upper mold's inner wall counteracts the buoyancy of the core in the molten steel, preventing the core from floating and shifting. The bottom surface of the core head 41 at the bottom mates with the bottom surface of the lower mold's inner wall. Limiting cavities are also provided on both sides of the cavity. The core heads 41 at the ends of the protruding sides fit into these limiting cavities with a clearance. When the mold is closed, the core heads 41 are engaged within the limiting cavities, facilitating the positioning and stability of the core.

[0027] S4. Determine the layout and location of the gating system, risers, and chills. Please refer to [reference needed]. Figure 6 The gating system includes an ingate. In this embodiment, two low ingates 51 are respectively provided on both sides of the bottom of the flange, and the four low ingates 51 are connected to each other, so that the molten steel enters the cavity more smoothly, reducing the turbulence of the molten steel and reducing the entrainment of impurities such as slag and sand.

[0028] Chills are cooling devices placed inside, on the surface of, or within the mold cavity to accelerate localized cooling of castings. Riseres are supplementary parts added to castings to prevent defects. Chills and risers are used together to control the solidification sequence of castings, ensuring sequential solidification. Shrinkage cavities in the casting are transferred to the risers, which helps improve the density of the casting. During the solidification of molten steel, a volume reduction phenomenon occurs. By altering the temperature field and creating differences in solidification time, risers are placed at the last solidified areas to replenish the volume of the molten steel that has decreased during solidification.

[0029] In this embodiment, chills 52 are provided at the bottom of the large-volume end 11 and along the circumferential direction of the pipe connection 30, and risers 53 are provided on both sides of the valve body 10. This promotes the cooling of the large-volume end 11 at the bottom of the casting and the thinner pipe connection 30 first, while the top of the thicker part of the valve body 10 sidewall is cooled last. This helps improve the density and prevents shrinkage porosity and shrinkage cavities in the valve shell. Chills 52 are provided at the top and bottom of the two flanges 20 on the side away from each other, and risers 53 are provided on both sides of the top of the two flanges 20, so that the top sides of the flanges are solidified last. The risers can be heated riser sleeves, and the chills can be round chills.

[0030] S5. Draw process design drawings, and mix sand, make molds, shape and pour according to the process design drawings. For specific methods, please refer to relevant technologies.

[0031] The above describes one or more embodiments of the present invention in a relatively specific and detailed manner, but it should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A sand casting method for a plug valve housing, the valve housing comprising a valve body and flanges disposed on both sides of the valve body, the valve body and the flanges being connected by a pipe connection, the bottom end of the valve body being a large-volume end and the other end being a small-volume end, and the inner wall of the side wall of the valve body being a sealing surface, characterized in that, Includes the following steps: S1, determine the pouring position to ensure that the sealing surface is located on the side of the cavity; the pouring position is: the central axis of the valve body is set vertically, the central axes of the two flanges are set horizontally, and the large volume end is oriented towards the lower part of the mold; S2, Determine the parting surface, and divide the mold into an upper mold and a lower mold using the horizontal plane where the flange centerline is located as the parting surface; S3, for making the core and preventing the core from floating; S4, determine the arrangement of the gating system, risers, and chills to ensure the valve body solidifies sequentially; chills are provided at the bottom of the large volume end and along the circumferential direction of the pipe connection, risers are provided on both sides of the valve body, and risers are provided on both sides of the top of the two flanges. S5, Draw the process design diagram.

2. The sand casting method for a plug valve body according to claim 1, characterized in that, In step S1, the valve body is cylindrical.

3. The sand casting method for a plug valve body according to claim 1, characterized in that, In step S3, a core is made according to the shape of the valve housing cavity. The top, bottom and two protruding parts of the core are provided with core heads. The core head at the top of the core mates with the upper surface of the inner wall of the upper mold, and the core head at the bottom of the core mates with the bottom surface of the inner wall of the lower mold.

4. The sand casting method for a plug valve body according to claim 3, characterized in that, Limiting cavities are also provided on both sides of the cavity, and the core head located on the protruding part on both sides cooperates with the limiting cavity.

5. The sand casting method for a plug valve body according to claim 1, characterized in that, In step S4, two low ingates are provided on both sides of the bottom of the flange, and the four low ingates are connected.

6. The sand casting method for a plug valve body according to claim 1, characterized in that, In step S4, chills are provided on the top and bottom of the two flanges on the side furthest from each other.

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