A high temperature alloy pressure casting mold and casting process for impeller and guide vane

Abstract

This invention relates to the field of casting technology, specifically to a high-temperature alloy pressure casting mold and casting process for impellers and guide vanes. The mold includes a main casting pipe, a pouring pipe, and forming steel mold components. Several forming steel mold components surround the main casting pipe. The main casting pipe is equipped with a pressure device. The bottom of the main casting pipe is connected to the pouring port at the bottom of the forming steel mold components via the pouring pipe, and casting is performed by applying pressure through the main casting pipe. Compared with existing technologies, this invention, through improvements to the mold structure, enables the casting mold to adapt to high-temperature alloy casting at temperatures above 1400℃ and achieves one-time molding of multiple sets of impellers and guide vanes, thus improving production efficiency. The pressure design of the main casting pipe reduces risers and shrinkage cavities, improving casting quality while also increasing process yield and reducing production costs.

Description

Technical Field

[0001] The invention relates to the technical field of casting, in particular to a high-temperature alloy pressure casting mold and a casting process for an impeller and a guide vane. Background Art

[0002] The impellers and guide vanes of traditional pumps and valves are all made by precision lost wax casting. Although the precision lost wax casting process solves the problem of complex product shapes, the castings made by this process have the following disadvantages: 1. There are many risers, the process yield is low, and the cost is difficult to be effectively controlled. 2. The shrinkage problem cannot be effectively solved, and the quality of the casting is difficult to guarantee. 3. Each casting can only form one finished casting.

[0003] The castings of precision lost wax casting process have many risers, which need the pressure of molten steel with the deadweight of the risers that is heavier than the main body to compensate for shrinkage. This also leads to the same weight of molten steel to produce only a small number of castings, and the cost is difficult to be effectively controlled. For example, the double-suction impeller of KSB Germany, OMEGA 200 casting weight is 67.85kg, the riser weight is 110.27kg, the total weight is 178.12kg, and 1425kg of molten steel can only cast 8 double-suction impeller finished products. According to calculations, the process yield of precision lost wax casting process is about 40%, and about 60% of waste materials are generated.

[0004] The shrinkage holes of the castings made by the precision lost wax casting process need to be compensated by the pressure of the riser's deadweight steel liquid, which is heavier than the body, but the compensation effect is not ideal and the problem cannot be effectively solved, so welding is required. This also makes it difficult to guarantee the quality of castings. Therefore, in some fields with high requirements for casting product quality, such as nuclear power, finished castings made by the precision lost wax casting process cannot be used.

[0005] Due to the limitations of mold structure and process methods, the precision lost wax casting process can only form one finished casting each time, which has low production efficiency. Taking the double-suction impeller of KSB in Germany as an example, 1425kg of molten steel needs to be cast in 8 times, which is time-consuming and labor-intensive.

[0006] In addition, common casting molds are generally all-steel molds, which are generally suitable for temperatures of 1100℃-1300℃. When the casting temperature exceeds 1400℃, the steel mold will melt. The casting material of the impeller and guide vane is stainless steel, the melting point of stainless steel is 1450℃, and the actual casting temperature is 1520℃. In addition, the inner cavity shape of the impeller and guide vane is extremely complex. Therefore, the common all-steel mold casting mold cannot be used for the casting of impellers and guide vanes.

[0007] Therefore, it is necessary to design a high-temperature alloy pressure casting mold and casting process for impellers and guide vanes to adapt to the casting of high-temperature alloys above 1400°C, while being able to reduce risers and shrinkage holes, improve casting quality, improve process yield and production efficiency, and reduce costs. Summary of the invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a high-temperature alloy pressure casting mold and casting process for impellers and guide vanes to adapt to the casting of high-temperature alloys above 1400°C. At the same time, it can achieve the reduction of risers and shrinkage holes, improve the quality of castings, improve the process yield and production efficiency, and reduce costs.

[0009] In order to achieve the above-mentioned purpose, the present invention is a high-temperature alloy pressure casting mold for impellers and guide vanes, including a pouring main pipe, a down-pouring pipe, and a forming steel mold assembly, characterized in that: a plurality of forming steel mold assemblies are surrounded by the pouring main pipe, the pouring main pipe is provided with a pressure device, the bottom of the pouring main pipe and the pouring port at the bottom of the forming steel mold assembly are connected by a down-pouring pipe, the pouring main pipe includes a steel sleeve and a ceramic layer, the ceramic layer is attached to the inner surface of the steel sleeve, the down-pouring pipe includes a steel pipe and a ceramic pipe, and the steel pipe sleeve is arranged outside the ceramic pipe.

[0010] The volume of the pouring port is larger than the local volume of any part of the impeller and the guide vane casting.

[0011] The forming steel mold assembly comprises a plurality of forming steel molds, and the forming steel mold comprises an upper steel mold, a lower steel mold and a mud core. The surfaces of the upper steel mold and the lower steel mold are coated with pickling powder coating, and the upper steel mold and the lower steel mold are provided with a mud core.

[0012] The forming steel mold is provided with a cooling water circulation pipeline.

[0013] A metal bracket is arranged inside the clay core.

[0014] The pressure device is a pressure column, which is located on the top of the pouring main pipe.

[0015] A high-temperature alloy pressure casting process for impellers and guide vanes, characterized in that it is prepared according to the following steps: step 1, injecting molten steel into a pouring main pipe in the middle of the mold, metal inclusions in the molten steel are suspended on the liquid surface of the molten steel, and the height difference between the liquid surface of the molten steel and the top of the inner surface of the forming steel mold is 120mm-400mm; step 2, applying pressure to the pouring main pipe, the molten steel in the pouring main pipe flows into the down-pouring pipe, and flows into each forming steel mold from bottom to top through the pouring port; step 3, during the crystallization process of the molten steel in the forming steel mold, the pressure obtained by the pouring main pipe is transmitted to the molten steel in the forming steel mold in liquid form, so that the molten steel fills the inner cavity of the forming steel mold; step 4, after 3-5 minutes, the molten steel in the forming steel mold crystallizes and forms impeller and guide vane castings, and the molten steel at the pouring port is in liquid state; step 5, the molten steel at the pouring port supplements the shrinkage cavity and forms a riser; step 6, the impeller and guide vane castings are cooled and demolded.

[0016] The pouring temperature of the molten steel is 1470°C to 1520°C, the weight of the molten steel is 1420kg, and the number of formed impeller and guide vane castings is 18.

[0017] The process of applying pressure by the pouring main pipe is as follows: within 3-4 minutes, the pressure increases uniformly from 100 kg to 10,000 kg.

[0018] During the crystallization process of the molten steel in the forming steel mold, water cooling is carried out.

[0019] Compared with the prior art, the present invention improves the mold structure, so that the casting mold can adapt to the casting of high-temperature alloys above 1400°C, and can form multiple sets of impellers and guide vanes at one time, thereby improving production efficiency. The pressure supply design of the pressure casting main pipe is adopted to reduce the riser and shrinkage cavity, improve the quality of the casting, and also improve the process yield and reduce the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the present invention.

[0021] Figure 2 It is a cross-sectional schematic diagram of the present invention. DETAILED DESCRIPTION

[0022] The present invention will now be further described with reference to the accompanying drawings.

[0023] See also Figure 1 , Figure 2The present invention is a high-temperature alloy pressure casting mold for impellers and guide vanes, including a pouring main pipe, a down-pouring pipe, and a forming steel mold assembly. A plurality of forming steel mold assemblies 2 surround the pouring main pipe 1. The pouring main pipe 1 is provided with a pressure device. The bottom of the pouring main pipe 1 is connected to the pouring port at the bottom of the forming steel mold assembly 2 by a down-pouring pipe 3. The pouring main pipe 1 includes a steel sleeve 11 and a ceramic layer 12. The ceramic layer 12 is attached to the inner surface of the steel sleeve 11. The down-pouring pipe 3 includes a steel pipe 31 and a ceramic pipe 32. The steel pipe 31 is sleeved outside the ceramic pipe 32.

[0024] In the present invention, the volume of the pouring port is Φ130×400mm³, the maximum wall thickness of the impeller and the guide vane casting is 51mm, and the volume of the pouring port is greater than the local volume of any part of the impeller and the guide vane casting. The temperature of the molten steel at the pouring port is always higher than that of the impeller and the guide vane casting during the pouring process, so that the pressure can be transmitted in a liquid state until the inside of the impeller and the guide vane casting is completely crystallized.

[0025] In the present invention, the forming steel mold assembly 2 includes a plurality of forming steel molds 21, and the forming steel mold 21 includes an upper steel mold 211, a lower steel mold 212 and a mud core 213. The surfaces of the upper steel mold 211 and the lower steel mold 212 are coated with pickling powder coating, and the upper steel mold 211 and the lower steel mold 212 are provided with a mud core 213. Taking 18 impeller and guide vane castings as an example, there are three forming steel mold assemblies 2 and six forming steel molds 21. Among them, in order to facilitate rapid cooling, a cooling water circulation pipeline is provided on the forming steel mold 21. A metal bracket is provided in the mud core 213, which plays a supporting role and can be used repeatedly. The pressure device is a pressure column 4, which is located at the top of the pouring main pipe 1.

[0026] The high-temperature alloy pressure casting process for impellers and guide vanes is prepared according to the following steps: Step 1, injecting molten steel into the pouring main pipe in the middle of the mold, the pouring temperature of the molten steel is 1470℃~1520℃, the metal inclusions in the molten steel are suspended on the liquid surface of the molten steel, and the metal inclusions are prevented from entering the forming steel mold 21. The height difference between the liquid surface of the molten steel and the top of the inner surface of the forming steel mold is 120mm~400mm, and the height difference enables the molten steel to be injected into the forming steel mold faster.

[0027] Step 2: Pressurize the main pouring pipe, and the molten steel in the main pouring pipe flows into the pouring pipe and flows into each forming steel mold from bottom to top through the pouring port. The process of pressurizing the main pouring pipe is: within 3-4 minutes, the pressure increases from 100 kg to 10,000 kg at a uniform rate. This can reduce the weight of the riser, ensure that there are no shrinkage holes on the metal cutting surface layer inside the casting, and do not require repair welding of the impeller and guide vane castings, thereby improving the quality of the castings to meet the needs of various industries.

[0028] Step 3: During the crystallization of the molten steel in the forming steel mold, the pressure obtained by the pouring main pipe is transmitted to the molten steel in the forming steel mold in liquid form, so that the molten steel fills the inner cavity of the forming steel mold. During the crystallization of the molten steel in the forming steel mold, water cooling can be performed. When the temperature of the attached chip drops to 1300°C, the mold can be water-cooled to increase production capacity and protect the mold.

[0029] Step 4: After 3-5 minutes, the molten steel in the molding steel mold crystallizes and forms impeller and guide vane castings, and the molten steel at the pouring port is in liquid state.

[0030] Step 5, the molten steel from the pouring port compensates the shrinkage cavity and forms a riser.

[0031] Step 6: The impeller and guide vane castings are cooled and demoulded. The weight of the molten steel is 1420 kg, and there are 18 impeller and guide vane castings formed.

[0032] According to the test, the present invention starts to produce 28 ml of shrinkage cavities 26 seconds after pouring, and after 3 minutes, a total of 760 shrinkage cavities are produced, with a total weight of about 527g. The volume of the pouring port is Φ130×400mm³, the pouring port molten steel is about 37kg, and the total amount of liquid required for 18 impeller and guide vane castings is 527g×18, which is about 9.5kg, which greatly reduces the weight of the riser, thereby increasing the process yield to more than 85%.

[0033] The present invention enables the casting mold to adapt to high-temperature alloy casting above 1400°C by setting the ceramic layer 12, the ceramic tube 32, and the quartz powder coating. The present invention can realize the one-time molding of 18 impellers and guide vanes, thereby improving production efficiency. The pressure supply design of the pressure casting main pipe is adopted to reduce the riser and shrinkage cavity, improve the quality of the casting, and increase the process yield to more than 85%, thereby reducing the production cost.

Claims

1. A high-temperature alloy pressure casting mold for impellers and guide vanes, comprising a pouring main pipe, a pouring pipe, and a forming steel mold assembly, characterized in that: A plurality of forming steel mold components (2) surround a pouring main pipe (1), the pouring main pipe (1) is provided with a pressure device, the bottom of the pouring main pipe (1) is connected to a pouring port at the bottom of the forming steel mold component (2) by a down-pouring pipe (3), the pouring main pipe (1) comprises a steel sleeve (11) and a ceramic layer (12), the ceramic layer (12) is attached to the inner surface of the steel sleeve (11), the down-pouring pipe (3) comprises a steel pipe (31) and a ceramic pipe (32), the steel pipe (31) is sleeved outside the ceramic pipe (32), The volume of the pouring port is larger than the local volume of any part of the impeller and guide vane castings. The temperature of the molten steel at the pouring port is always higher than that of the impeller and guide vane castings during the pouring process, so that the pressure can be transmitted in liquid state until the inside of the impeller and guide vane castings are completely crystallized. The pouring temperature of the molten steel is 1470℃~1520℃, the weight of the molten steel is 1420kg, and there are 18 impeller and guide vane castings formed.

2. The high temperature alloy pressure casting mold for impellers and guide vanes according to claim 1, characterized in that: The molding steel mold assembly (2) comprises a plurality of molding steel molds (21), wherein the molding steel mold (21) comprises an upper steel mold (211), a lower steel mold (212) and a mud core (213), wherein the surfaces of the upper steel mold (211) and the lower steel mold (212) are coated with a quartz powder coating, and the upper steel mold (211) and the lower steel mold (212) are provided with a mud core (213).

3. The high temperature alloy pressure casting mold for impeller and guide vane according to claim 2, characterized in that: The forming steel mold (21) is provided with a cooling water circulation pipeline.

4. The high temperature alloy pressure casting mold for impeller and guide vane according to claim 2, characterized in that: A metal bracket is provided inside the clay core (213).

5. The high temperature alloy pressure casting mold for impellers and guide vanes according to claim 1, characterized in that: The pressure device is a pressure column (4) located at the top of the pouring main pipe (1).

6. A high temperature alloy pressure casting process for impellers and guide vanes using the mold as claimed in claim 1, characterized in that: Preparation is carried out according to the following steps: Step 1, injecting molten steel into the pouring main pipe in the middle of the mold, the metal inclusions in the molten steel are suspended on the liquid surface of the molten steel, and the height difference between the liquid surface of the molten steel and the top of the inner surface of the forming steel mold is 120mm~400mm, Step 2, applying pressure to the pouring main pipe, the molten steel in the pouring main pipe flows into the down-pouring pipe, and flows into each forming steel mold from bottom to top through the pouring port, Step 3, during the crystallization process of the molten steel in the forming steel mold, the pressure obtained by the pouring main pipe is transmitted to the molten steel in the forming steel mold in liquid form, so that the molten steel fills the inner cavity of the forming steel mold, Step 4, after 3-5 minutes, the molten steel in the forming steel mold crystallizes and forms impeller and guide vane castings, and the molten steel at the pouring port is in liquid state, Step 5, the molten steel at the pouring port supplements the shrinkage cavity and forms a riser, Step 6, the impeller and guide vane castings are cooled and demolded.

7. The high temperature alloy pressure casting process for impellers and guide vanes according to claim 6 is characterized in that: The process of applying pressure by the pouring main pipe is as follows: within 3-4 minutes, the pressure increases uniformly from 100 kg to 10,000 kg.

8. The high temperature alloy pressure casting process for impellers and guide vanes according to claim 6 is characterized in that: During the crystallization process of the molten steel in the forming steel mold, water cooling is carried out.

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