Casting forming method of valve body with inner surface alloy layer

Abstract

The invention discloses a casting forming method of a valve body with an inner surface alloy layer. A lost foam casting method is adopted for casting forming of the valve body. An alloy lining part capable of being matched with the inner surface of the valve body is prefabricated before casting forming, the alloy lining part is embedded in a foam model, and the outer surface of the alloy lining part and the inner surface of the foam model are attached to form an integrated casting model. In the casting forming process, molten steel can partially melt the outer surface of the alloy lining piece through high-temperature heat of the molten steel, so that the base metal of the valve body and the alloy lining piece are metallurgically bonded, the alloy layer which is approximately integrally formed is formed on the inner surface of the valve body in a cladding mode, the bonding strength between the alloy layer and the valve body is very high, and the service life of the valve body is prolonged. The inner cavity of the valve body has better wear resistance and corrosion resistance; construction does not need to be conducted in the inner cavity of the valve body, limitation of the structure of the inner cavity of the valve body is avoided, and due to the fact that the valve body and the alloy layer are produced in a combined mode, the production process can be effectively shortened, and energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of valve production and preparation methods, in particular to a casting method for a valve body with an inner surface alloy layer. Background Art

[0002] For valves made of ordinary carbon steel and low alloy steel, when there are special requirements for the corrosion resistance and wear resistance of the cavity surface according to the medium flowing through, the common practice in the industry is to weld special alloy materials on the surface of the inner cavity of the valve body of such valves to form an alloy layer. However, due to the complex shape of the valve body cavity and the small size of the inner cavity space, the construction time and difficulty of the welding operation are long, and the welded alloy layer is also prone to quality defects.

[0003] A Chinese invention patent application with publication number CN113427129A discloses a method for additive forming of a valve body and an inner wall wear-resistant layer thereof and the resulting valve body, the technical solution of which includes remodeling the three-dimensional model of the valve body before printing; importing the model of the valve body into slicing software for layered slicing processing, and separating the valve body part and the wear-resistant layer part for layered slicing processing during layered slicing; then exporting the slicing data and importing it into the control system of the additive equipment; setting the forming trajectory parameters on the additive equipment according to the forming path of the valve body and the wear-resistant layer; and using double gun heads for printing during the printing process, with the first gun head printing the valve body and the second gun head printing the wear-resistant layer to complete the printing of the valve body.

[0004] A Chinese invention patent application with publication number CN102635721A discloses a multi-metal composite wear-resistant valve and a production method thereof. The technical solution is that a multi-metal composite wear-resistant tube is provided in the flow channel on the valve body. The multi-metal composite wear-resistant tube is composed of a multi-metal layer with a thickness of 3-15 mm evenly composited on the wall of a steel pipe. The multi-metal composite wear-resistant tube is welded to the valve body. The multi-metal layer is composed of a mixture of copper-chromium alloy powder, iron oxide powder, aluminum powder, and nano-silicon carbide powder, which is centrifugally cast on the wall of the steel pipe.

[0005] The technical solutions disclosed in the above patents respectively use additive processing and casting to add a wear-resistant layer to the valve body, both of which belong to the processing of the finished valve body. Therefore, the processing work is still limited by the inner cavity structure of the valve body, and fails to solve the technical problem of the difficulty of alloy layer construction. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a casting method for a valve body having an inner surface alloy layer which can effectively improve production efficiency and alloy layer processing quality.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a casting method for a valve body with an inner surface alloy layer, adopting the lost foam casting method to cast the valve body; before casting, prefabricating an alloy lining component that can be matched with the inner surface of the valve body, embedding the alloy lining component in a foam model, so that the outer surface of the alloy lining component and the inner surface of the foam model are fitted to form an integrated casting model.

[0008] As an improvement of the above scheme: the following steps are included:

[0009] Step S1, preparing an alloy lining member according to the inner cavity specifications of the valve body, wherein the outer surface of the alloy lining member can be fitted with the inner surface of the formed valve body;

[0010] Step S2, preparing a foam model, embedding an alloy lining member in the foam model, caulking the periphery where the alloy lining member intersects with the foam model, and coating the foam model with a refractory material and drying it;

[0011] Step S3, arranging the foam models obtained in the multiple steps S2 in a sand box, arranging the runner structure and filling the sand box;

[0012] Step S4, pouring molten steel, and obtaining a valve body with an inner surface covered with an alloy layer after cooling.

[0013] As an improvement of the above scheme: in the step S1, the material for preparing the alloy lining is an iron-nickel based alloy material, a nickel based alloy material or a cobalt based alloy material; the iron-nickel based alloy material includes Fe-12Cr-43Ni-7W-4.5Ti-2Al; the nickel based alloy material includes Ni-21Cr-9Mo, Ni-19Cr-19Fe-3Mo-5Nb, Ni-23Cr-18Mo, Ni-22Cr-13Mo-3W, Ni-16Cr-16Mo-5Fe-4W; the cobalt based alloy material includes Co-29Cr-4.5W, Co-27Cr-6Mo, Co-20Cr-15W-10Ni, Co-26Cr-7W-10Ni, Co-8.5Cr-28Mo-2.5Si, Co-17.5Cr-28.5Mo-3.4Si, Co-18Cr-23Mo-16Ni-2.7Si.

[0014] As an improvement of the above scheme: in the step S1, the minimum wall thickness of the alloy lining is set to no less than 3 mm, and the alloy lining is prepared by a powder metallurgy production process or a vacuum precision casting process; in the step S2, the minimum wall thickness of the foam model is set to no less than 6 mm, and the thickness of the refractory material is set to no less than 3 mm.

[0015] As an improvement of the above scheme: in the step S3, the runner structure adopted includes a pouring cup, a straight runner, a cross runner, an ingode, a first riser and a second riser; the area ratio of the straight runner, the cross runner and the ingode is 1:1.25:0.75, and the corners of each runner are set to arc corners; the number of ingodes corresponds one-to-one to the foam models and is connected with the corresponding foam models, the pouring cup is connected with the cross runner through the straight runner, and the cross runner is connected with multiple ingodes; each foam model is provided with a first riser and a second riser, the first riser corresponds to the valve cavity part and one of the flow channel parts of the foam model, and the second riser corresponds to another flow channel part of the foam model.

[0016] As an improvement to the above solution: the first riser is configured to consist of a lower rectangular riser portion and an upper cylindrical riser portion; the second riser is configured to consist of two sections of cylindrical riser portions.

[0017] As an improvement of the above scheme: a cylindrical sprue nest is provided at the bottom of the sprue, the length of the sprue nest is twice the diameter of the sprue, and the diameter of the sprue nest is 1.5 times the diameter of the sprue; a filter is arranged on the ingrown.

[0018] As an improvement of the above solution: a flange dam is provided at the inner bottom of the pouring cup, the flange dam is a circular arc convex structure, and a slope transition is provided between the flange dam and the inner wall of the pouring cup, and the inclination angle of the slope is 40 to 45 degrees.

[0019] As an improvement of the above scheme: in the step S4, the foam model is burned before pouring, and the sand box is kept at a negative pressure during the pouring process until the pouring is completed; during the pouring process, the water head height is controlled not to exceed 650mm, and the pouring temperature is controlled not to exceed 1600°C; the pouring speed is controlled to be 600kg / 25s to 600kg / 20s, and the pouring speed is controlled according to the fast-slow-fast speed interval.

[0020] The beneficial effects of the present invention are as follows: the present invention improves the processing method of the alloy layer on the inner surface of the valve body, adopts the lost foam casting method to cast the alloy layer together with the valve body, and pre-prepares an alloy lining part and embeds it in the foam model adopted by the lost foam casting method. During the casting process, the molten steel can melt the outer surface part of the alloy lining part through its own high-temperature heat, so that the valve body mother material and the alloy lining part are metallurgically bonded, thereby cladding on the inner surface of the valve body to form an alloy layer that is nearly integrally formed, and the alloy layer and the valve body have a strong bonding strength, so that the inner cavity of the valve body has better wear resistance and corrosion resistance; the process method of the present invention does not require construction in the inner cavity of the valve body, so it will not be subject to the structural limitations of the inner cavity of the valve body, and since the valve body and the alloy layer are produced in combination, the production process can be effectively shortened and energy consumption can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an alloy lining component;

[0022] Figure 2 It is a cross-sectional view of the overall structure of the alloy lining and the valve body;

[0023] Figure 3 is a schematic diagram of a runner structure used in the present invention;

[0024] Figure 4 This is a structural cross-sectional view of the pouring cup.

[0025] Markings in the figure are: 100-valve body, 200-alloy lining, 300-foam model, 410-pouring cup, 411-flange dam, 420-sprue, 430-cross runner, 440-ingate, 450-first riser, 460-second riser, 470-filter screen. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention is further described below in conjunction with the accompanying drawings.

[0027] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, and “inside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of description. They do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0028] Compared with the prior art method of processing an alloy layer on the inner surface of the valve body 100, the casting method of the valve body with an inner surface alloy layer disclosed in the present invention combines the alloy layer processing with the production of the valve body 100, and uses the lost foam casting method to combine the alloy layer processing with the casting production of the valve body 100. By prefabricating the alloy liner 200 before casting the valve body 100, as shown in FIG. Figure 1 and Figure 2As shown, the shape of the alloy lining component 200 is adapted to the inner shape of the valve body 100, that is, the outer surface of the alloy lining component 200 can fit with the inner surface of the valve body 100, and after the valve body 100 is cast, the alloy lining component 200 can cover the inner surface of the valve body 100 to form an alloy layer with corrosion resistance and wear resistance. The principle of combining the valve body 100 and the alloy lining component 200 in the casting method of the valve body with an inner surface alloy layer described in the present invention is as follows: since the lost foam casting method is used to cast the valve body 100, the lost foam casting method requires a foam model 300 to form a mold cavity, and the alloy lining component 200 is embedded in the foam model 300, so that the outer surface of the alloy lining component 200 and the inner surface of the foam model 300 are fitted to form an integrated casting model; during the casting production, the foam model 300 will be heated and vaporized, leaving the alloy lining component 200, and the poured molten steel will fill the mold cavity formed by the foam model 300 and replace the original foam model 300, and then after the molten steel is cooled, it will be combined with the surface of the alloy lining component 200 to form a valve body 100 with an alloy layer as a whole.

[0029] Specifically, when performing the casting method of the valve body having the inner surface alloy layer according to the present invention, the following steps are performed in sequence:

[0030] Step S1, prepare the alloy lining member 200 according to the inner cavity specifications of the valve body 100, the outer surface of the alloy lining member 200 can be fitted with the inner surface of the formed valve body 100; the structure of the alloy lining member 200 designed in combination with the inner cavity shape and size specifications of the valve body 100 is as follows Figure 1 As shown, the outer contour structure of the alloy lining member 200 is the same as the inner cavity structure of the valve body 100, so that after the valve body 100 is cast and formed, the alloy lining member 200 can be completely attached to the inner cavity surface of the valve body 100 to form a Figure 2 The valve body shown has an inner surface alloy layer. The alloy lining component 200 is prepared by a powder metallurgy production process or a vacuum precision casting process to obtain a high-quality alloy lining component 200 having a density close to the theoretical density of the material.

[0031] In order to enable the alloy lining component 200 to form a good bonding relationship with the valve body 100; on the basis of ensuring that the alloy lining component 200 has good wear resistance and corrosion resistance, the material of the alloy lining component 200 needs to be able to wet and dissolve with the substrate of the valve body 100, and have good thermal expansion and contraction matching performance to form a good metallurgical bond, and no adverse interfacial chemical metallurgical reaction will occur after bonding. In addition, it is also necessary to consider that the material of the alloy lining component 200 needs to have a suitable melting point, preferably in the range of not less than 1280°C, to ensure that during the casting process of the valve body 100, the alloy lining component 200 can form a metallurgical bond with the substrate of the valve body 100, and avoid excessive melting of the alloy layer and causing a large amount of loss, to ensure that an alloy layer with a thickness that meets the design performance requirements is obtained; therefore, the material selection for the alloy lining component 200 in the present invention includes iron-nickel based alloy material, nickel based alloy material and cobalt based alloy material.

[0032] Among them, the iron-nickel based alloy material used in the alloy lining part 200 includes Fe-12Cr-43Ni-7W-4.5Ti-2Al; the nickel based alloy material used in the alloy lining part 200 includes Ni-21Cr-9Mo, Ni-19Cr-19Fe-3Mo-5Nb, Ni-23Cr-18Mo, Ni-22Cr-13Mo-3W, Ni-16Cr-16Mo-5Fe-4W; the cobalt based alloy material used in the alloy lining part 200 includes Including Co-29Cr-4.5W, Co-27Cr-6Mo, Co-20Cr-15W-10Ni, Co-26Cr-7W-10Ni, Co-8.5Cr-28Mo-2.5Si, Co-17.5Cr-28.5Mo-3.4Si, Co-18Cr-23Mo-16Ni-2.7Si; by limiting the material of the alloy lining 200, the valve body 100 can eventually obtain a bimetallic composite layer with a carbon steel-special alloy layer.

[0033] Step S2, prepare the foam model 300 required for the lost foam casting method, the foam model 300 is used to form the cavity required for casting the valve body 100, the structural shape of the foam model 300 is the same as that of the valve body 100, and the foam model 300 also has a cavity that is the same as the inner cavity of the valve body 100, and the prepared alloy lining component 200 is embedded in the inner cavity of the foam model 300, so that the outer surface of the alloy lining component 200 and the inner surface of the foam model 300 are fitted to form an integrated casting model; in order to ensure the sealing of the connection between the foam model 300 and the alloy lining component 200 after being combined, so as to ensure the precision of casting, the periphery where the alloy lining component 200 and the foam model 300 intersect can be further caulked, and the peripheral gap between the alloy lining component 200 and the foam model 300 can be coated with glue using cold adhesive. After the foam model 300 and the alloy lining component 200 are combined to obtain an integral casting model, the casting model is coated with refractory material and dried. The thickness of the refractory material is not less than 3 mm to ensure the supporting strength of the alloy lining component 200; the minimum wall thickness of the alloy lining component 200 is set to not less than 3 mm, and the minimum wall thickness of the foam model 300 is set to not less than 6 mm.

[0034] Step S3, according to the method of step S1 and step S2, a plurality of casting models formed by combining the alloy liner 200 and the foam model 300 are prepared, and then the plurality of casting models are evenly arranged in the sand box, the runner structure is arranged and the sand box is filled. The present invention adopts a semi-open pouring system for sub-contract pouring, and the specific runner structure is as follows Figure 3 As shown, it includes a pouring cup 410, a sprue 420, a runner 430, an ingode 440, a first riser 450 and a second riser 460; the sprue 420, the runner 430 and the ingode 440 all adopt a pipe structure with a circular cross section or a rectangular cross section, and the corners of each runner are set as arc corners. The area ratio of the sprue 420, the runner 430 and the ingode 440 is 1:1.25:0.75; the number of the ingode 440 is proportional to the foam model 300 correspond one by one and are connected with the corresponding foam model 300, the pouring cup 410 is connected with the runner 430 through the sprue 420, and the runner 430 is connected with multiple ingates 440; each foam model 300 is provided with a first riser 450 and a second riser 460, the first riser 450 corresponds to the valve cavity part and one of the flow channel parts of the foam model 300, and the second riser 460 corresponds to another flow channel part of the foam model 300. The first riser 450 is configured to be composed of a lower rectangular riser part and an upper cylindrical riser part; the second riser 460 is configured to be composed of two sections of cylindrical riser parts. The number and size specifications of the first riser 480 and the second riser 460 are selected accordingly according to the number and size specifications of the cast valve body 100.

[0035] A cylindrical sprue nest is provided at the bottom of the sprue 420, the length of which is twice the diameter of the sprue, and the diameter of which is 1.5 times the diameter of the sprue; the sprue nest is provided to buffer the impact of the molten steel to ensure smooth pouring. A filter screen 470 is arranged on the inner runner 440, and the filter screen 470 can be a ceramic filter screen. The filter screen 470 is provided to filter the poured molten steel to filter and block the slag of the molten steel.

[0036] like Figure 3 and Figure 4 As shown, the pouring cup 410 used in the present invention is an open basin-shaped pouring cup, the depth of the pouring cup 410 is not less than 7 times the diameter of the sprue 420, and a flange dam 411 is provided at the inner bottom of the pouring cup 410. The flange dam 411 adopts a circular arc convex structure, and the flange dam 411 and the inner wall of the pouring cup 410 are transitioned by an inclined surface, and the inclination angle of the inclined surface is 40 to 45 degrees. By providing the flange dam 411, the molten steel injected into the pouring cup 410 can be buffered to slow down the speed of the molten steel flowing into the sprue 420.

[0037] Step S4, pouring molten steel, the high-temperature molten steel melts the surface of the alloy liner 200 while filling the casting model, so that metallurgical bonding is generated between the valve body mother material and the alloy liner 200, and the valve body 100 with an alloy layer on the inner surface is obtained after cooling. The foam model 300 is burned off before pouring to reduce the flow resistance of the molten steel and avoid the carbon increase defect caused by the foam model 300; the sand box is kept at a negative pressure during the pouring process until the pouring is completed; the head height is controlled not to exceed 650mm during the pouring process to ensure that the molten steel can flow smoothly and completely fill the casting model; the pouring temperature does not exceed 1600℃; the pouring speed is controlled to be 600kg / 25s~600kg / 20s, that is, 600kg of molten steel is controlled to be poured within 20s~25s, and the pouring speed is controlled according to the fast-slow-fast speed interval.

Claims

1. A casting method for a valve body having an inner surface alloy layer, characterized in that: The valve body (100) is cast by using a lost foam casting method; before casting, an alloy lining component (200) that is compatible with the inner surface of the valve body (100) is prefabricated, and the alloy lining component (200) is embedded in a foam model (300) so that the outer surface of the alloy lining component (200) and the inner surface of the foam model (300) are fitted to form an integrated casting model.

2. The casting method of the valve body having an inner surface alloy layer according to claim 1, characterized in that: The following steps are involved: Step S1, preparing an alloy lining member (200) according to the inner cavity specifications of the valve body (100), wherein the outer surface of the alloy lining member (200) can be fitted with the inner surface of the formed valve body (100); Step S2, preparing a foam model (300), embedding an alloy lining member (200) in the foam model (300), performing a caulking treatment on the periphery where the alloy lining member (200) and the foam model (300) intersect, and coating the foam model (300) with a refractory material and drying it; Step S3, arranging the foam models (300) obtained in the multiple steps S2 in a sand box, arranging a runner structure and filling the sand box; Step S4, pouring molten steel, and after cooling, obtaining a valve body (100) with an inner surface covered with an alloy layer.

3. The casting method of the valve body having an inner surface alloy layer according to claim 2, characterized in that: In the step S1, the material for preparing the alloy lining component (200) is an iron-nickel based alloy material, a nickel based alloy material or a cobalt based alloy material; the iron-nickel based alloy material includes Fe-12Cr-43Ni-7W-4.5Ti-2Al; the nickel based alloy material includes Ni-21Cr-9Mo, Ni-19Cr-19Fe-3Mo-5Nb, Ni-23Cr-18Mo, Ni-22Cr-13Mo-3W, Ni-16Cr-16Mo-5Fe-4W; the cobalt based alloy material includes Co-29Cr-4.5W, Co-27Cr-6Mo, Co-20Cr-15W-10Ni, Co-26Cr-7W-10Ni, Co-8.5Cr-28Mo-2.5Si, Co-17.5Cr-28.5Mo-3.4Si, Co-18Cr-23Mo-16Ni-2.7Si.

4. The casting method of the valve body having an inner surface alloy layer according to claim 2, characterized in that: In the step S1, the minimum wall thickness of the alloy lining component (200) is set to be no less than 3 mm, and the alloy lining component (200) is prepared by a powder metallurgy production process or a vacuum precision casting process; in the step S2, the minimum wall thickness of the foam model (300) is set to be no less than 6 mm, and the thickness of the refractory material is set to be no less than 3 mm.

5. The casting method of the valve body having an inner surface alloy layer according to claim 2, characterized in that: In the step S3, the runner structure used includes a pouring cup (410), a straight runner (420), a horizontal runner (430), an ingrate (440), a first riser (450) and a second riser (460); the area ratio of the straight runner (420), the horizontal runner (430) and the ingrate (440) is 1:1.25:0.75, and the corners of each runner are set as arc corners; the number of ingrates (440) corresponds to the foam model (300) one by one and is consistent with the corresponding foam The foam model (300) is connected to the pouring cup (410) through the sprue (420) and the runner (430), and the runner (430) is connected to multiple ingates (440); each foam model (300) is provided with a first riser (450) and a second riser (460), the first riser (450) corresponds to the valve cavity part and one of the flow channel parts of the foam model (300), and the second riser (460) corresponds to another flow channel part of the foam model (300).

6. The casting method of the valve body having an inner surface alloy layer according to claim 5, characterized in that: The first riser (450) is configured to consist of a lower rectangular riser portion and an upper cylindrical riser portion; the second riser (460) is configured to consist of two sections of cylindrical riser portions.

7. The casting method of the valve body having an inner surface alloy layer according to claim 5, characterized in that: A cylindrical sprue nest is provided at the bottom of the sprue (420), the length of the sprue nest is twice the diameter of the sprue, and the diameter of the sprue nest is 1.5 times the diameter of the sprue; a filter screen (470) is arranged on the ingrowth (440).

8. The casting method of the valve body having an inner surface alloy layer according to claim 5, characterized in that: The inner bottom of the pouring cup (410) is provided with a flange dam (411), which is a circular arc convex structure. The flange dam (411) and the inner wall of the pouring cup (410) are transitioned through an inclined surface, and the inclination angle of the inclined surface is 40-45°.

9. The casting method of a valve body having an inner surface alloy layer according to claim 2, characterized in that: In the step S4, the foam model (300) is burned off before pouring, and the sand box is kept at a negative pressure during the pouring process until the pouring is completed; the water head height is controlled not to exceed 650 mm, and the pouring temperature is controlled not to exceed 1600° C. during the pouring process; the pouring speed is controlled to be 600 kg / 25 s to 600 kg / 20 s, and the pouring speed is controlled according to the fast-slow-fast speed interval.

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