CN103147117A - Directional solidification device of a high-temperature alloy and use method thereof - Google Patents

Abstract

The invention provides a directional solidification device for high-temperature alloys, which includes a heating chamber and a mold cold chamber. The heating chamber and the mold cold chamber are vacuum chambers that are connected up and down and are insulated from each other. The mold shell is placed on the workbench, and the high-temperature alloy melt is poured into the mold shell in the heating chamber, and then enters the mold cold room with the lifting table to be directional solidified; the mold cold room is equipped with a jet cooling device, including sequentially connected nozzles, cooling The liquid conduit and the cooling liquid container, a circle of nozzles are uniformly arranged at the outlet of the heating chamber bottom, the spray end of the nozzle corresponds to the outer peripheral surface of the mold shell, and a jet pump is arranged on the cooling liquid conduit. The device of the present invention is simple and compact, with a slight addition to the existing directional solidification furnace, without building a new furnace and changing the original structure; without adding a heating device for melting and heat preservation, the operation is greatly simplified; the cooling effect is superior; the blade can be solved simply and effectively The problem of heat dissipation of the mold shell can be solved, and the growth conditions of the single crystal blade can be improved.

Description

A device for directional solidification of superalloy and its application method

technical field

The invention relates to the precision casting of superalloy parts, in particular to a directional solidification device and its application method used in the precision casting of high temperature alloy parts. the

Background technique

In order to improve the performance of aero-engines and industrial gas turbines, high-temperature alloy turbine blades need to be made into columnar or single-crystal structures by precision casting and directional solidification. In the vacuum furnace, the superalloy is melted and poured into the high-temperature ceramic mold shell and slowly descends into the cold zone at a set speed, resulting in the bottom-up cooling of the ceramic mold shell and the directional solidification of the casting in the ceramic mold shell to form a superalloy columnar or single crystal structure. However, due to the poor thermal conductivity of the ceramic formwork, the efficiency of heat dissipation through radiation in a vacuum is low, resulting in low cooling speed and temperature gradient during the solidification process of the blade casting, which affects the quality of the product. In particular, the large blades used in heavy-duty gas turbines have a more serious heat dissipation problem due to their large volume. the

Now the world is actively developing new processes to improve the growth conditions of single crystal blades. One of the most famous is the liquid metal bath cooling process. As shown in Fig. 1, a molten pool of liquid metal is set at the bottom of the heating chamber A, and the ceramic formwork 3 descends into the pool to dissipate heat through conduction. However, this method has huge additional equipment, requires a huge amount of money to build a new furnace, and is cumbersome to operate. Tons of tin or aluminum must be melted and kept warm with expensive heating oil 11 as a liquid coolant. Due to the high production cost and low efficiency, this process has been difficult to be applied to production even though it has been invented for decades. the

Another method to improve the heat dissipation of the blades is the gas cooling method, which is to spray an inert gas such as argon to the mold shell drawn out of the furnace for forced cooling. However, because the gas will be blown into the furnace and the temperature of the furnace will be greatly reduced, which will reduce the quality of the blades, so this method has not been applied. the

Metallurgical enterprises use the continuous casting process to produce simple-shaped metal wire, plate or pipe semi-finished products, or to manufacture single crystal or columnar crystal metal products of low-melting point metals (such as copper and aluminum). continuous casting. In continuous casting without mould, it is one of the essential processes to spray and cool the continuously casted products or semi-finished products. Dangerous, also consider using other coolants such as liquid metal or molten salts (ionic liquids). However, since the above-mentioned products or semi-finished products are generally common ferrous metals or non-ferrous metals, the processing precision requirements are not high, and there may be a large amount of processing allowance. Oxidation reaction occurs on the surface, and the working environment is not demanding, generally carried out in the air environment, which is not suitable for the cooling of the directional solidification process of the superalloy with a shell of the present invention. the

Contents of the invention

The object of the present invention is to provide a directional solidification device for superalloys and its application method, which can simply and effectively solve the heat dissipation problem of the blade formwork and improve the growth conditions of single crystal blades. the

The technical scheme adopted in the present invention is:

A directional solidification device for high-temperature alloys, comprising a heating chamber and a mold cold chamber, the heating chamber and the mold cold chamber are vacuum chambers connected up and down and insulated from each other, and a lifting worktable is arranged in the chamber, and the lifting workbench is placed The mold shell, the superalloy melt is poured into the mold shell in the heating chamber, and enters the mold cold room with the lifting table to be directional solidified; the mold cold room is equipped with a spray cooling device, including sequentially connected nozzles, coolant pipes and cooling A liquid container, a circle of nozzles is uniformly arranged at the furnace exit at the bottom of the heating chamber, the ejection end of the nozzle corresponds to the outer peripheral surface of the mold shell, and a jet pump is arranged on the cooling liquid conduit.

The cooling chamber of the mold is provided with a cooling liquid circulation device, including a cooling liquid collecting pan and a return pipe, the cooling liquid collecting pan is arranged on the top outer periphery of the lifting worktable, and the bottom of the cooling liquid collecting pan is provided with a cooling liquid return hole, Connect the coolant reservoir through the return line. the

A circle of shroud is arranged inside the bottom of the nozzle, the shroud is in the shape of an inverted umbrella, and the opening at the bottom corresponds to the inner side of the cooling liquid collecting plate. the

The nozzle is an atomizing nozzle. the

The cooling liquid is liquid gallium indium tin alloy. the

The mold shell is a ceramic mold shell. the

The method for using the directional solidification device of the superalloy, the specific steps are:

Installation work:

1) In the mold cooling chamber of the existing directional solidification furnace, a circle of nozzles is evenly arranged around the furnace outlet at the bottom of the heating chamber, and the nozzles are connected to the cooling liquid container through the cooling liquid conduit, and the jet pump is arranged on the cooling liquid conduit ;

2) Place the ceramic formwork on the lifting table, install a cooling liquid collection plate on the outer periphery of the top of the lifting table, and use a return pipe to connect the cooling liquid return hole at the bottom of the cooling liquid collecting plate to the cooling liquid container;

3) A circle of shrouds is arranged on the inner side of the bottom of the nozzle, the shrouds are in the shape of an inverted umbrella, and the opening at the bottom corresponds to the inner side of the cooling liquid collection plate;

4) Pour the indium tin liquid alloy into the cooling liquid container as the cooling liquid;

Use of directional solidification device:

5) Lift the ceramic mold shell into the heating chamber through the lifting workbench; close the furnace door of the directional solidification furnace, and vacuumize the cavity of the heating chamber and the mold cooling chamber;

6) Turn on the heater in the heating chamber, preheat the ceramic formwork, and then pour the melted superalloy melt into the ceramic formwork;

7) Slowly lower the ceramic mold shell to the mold cold room at a set speed through the lifting table;

8) When the ceramic formwork enters the cold chamber of the casting mold, the jet pump is turned on, so that the cooling liquid is sprayed to the ceramic formwork in the form of droplets, and the superalloy melt inside the ceramic formwork is forcibly cooled;

)9 The shutter inside the bottom of the nozzle prevents the coolant from splashing out, and the coolant after heat exchange flows down the ceramic mold shell. , thus completing the circulation of the coolant;

10) When the directional solidification process of the superalloy is about to end, turn off the jet pump, and open the cold chamber of the casting mold after evacuating, take out the ceramic mold shell, and take out the superalloy casting after directional solidification therefrom.

The beneficial effects produced by the present invention are:

Compared with the usual directional solidification of superalloys cooled by liquid metal molten pools, the present invention has the following characteristics:

(1) The device of the present invention is simple and compact, and the original directional solidification furnace can be used for minor additions, without the need to build a new furnace and change the original structure;

(2) Since the amount of cooling liquid is greatly reduced (from several tons of liquid metal bath cooling method to about one liter), gallium indium tin (Ga-In-Sn) alloy that is liquid at room temperature can be used. There is no need to add a heating device for melting and heat preservation, and the operation is greatly simplified;

(3) The liquid metal is at room temperature and kept at a low temperature by water cooling, which is better than the cooling effect of overheated tin or aluminum liquid.

Compared with the directional solidification of superalloys that adopt gas cooling, the present invention has the following characteristics:

(1) Since the cooling medium is liquid in the present invention, the cooling effect is much better than gas;

(2) Since the cooling medium is metal liquid, it will not rise into the furnace like gas and reduce the furnace temperature;

(3) The liquid cooling medium can automatically flow back to the storage container, and there is no need to set up a complicated recovery system;

(4) The liquid cooling medium will not affect the atmosphere and vacuum conditions in the furnace like gas.

Compared with the continuous casting without mold that adopts water spray cooling, the present invention has the following characteristics:

(1) The present invention is a high-temperature alloy precision casting with a ceramic mold, which is different from the above-mentioned continuous casting without a mold;

(2) The product material of the present invention is a high-temperature alloy, which is different from the above-mentioned products or semi-products which are ordinary ferrous metals or non-ferrous metals;

(3) The shape of the product of the present invention is a complex turbine blade, which is a product without machining allowance, which is different from the above-mentioned products or semi-finished products which are generally simple in shape and have an equal cross-sectional structure;

(4) The cooling action part of the present invention is on the outer surface of the ceramic mold shell, which is different from the above-mentioned water spray cooling directly acting on the metal surface of the product or semi-product;

(5) The processing environment of the present invention is very precise and strict, and the working conditions must be in a vacuum furnace, which is different from the above-mentioned water spray cooling environment, which has lower requirements and can directly act on the air.

Description of drawings

What Fig. 1 shows is the use status schematic diagram of the cooling device of prior art;

Figure 2 is a schematic view of the cooling device of the present invention in use.

The symbols in the figure indicate: 1. Heater, 2. Insulation layer, 3. Ceramic formwork, 4. High temperature alloy melt, 5. High temperature alloy casting, 6. Heat insulating ceramic ball, 7. Lifting table, 8. Chassis , 9, liquid metal for cooling, 10, stirring device, 11 heating oil, 12, heat shield, 13, nozzle, 14, jet pump, 15, shroud, 16, cooling liquid collection plate, 17, return pipe, 18 , coolant container, 19, coolant, 20, water-cooled furnace bottom, A, heating chamber, B, mold cold chamber. the

Detailed ways

As shown in Figure 2, the present invention is a directional solidification device for superalloys, comprising a heating chamber A and a mold cold chamber B, the heating chamber A and the mold cold chamber B are vacuum chambers that communicate up and down and are insulated from each other. Lifting table 7 is provided. The mold shell is placed on the lifting table 7, and the superalloy melt 4 is poured into the mold shell in the heating chamber A, and enters the mold cold chamber B as the lifting table 7 descends to solidify directionally. In this specific embodiment, the mold shell is a ceramic mold shell 3 , and a liquid superalloy melt 4 is housed in the ceramic mold shell 3 . The inside of the heating chamber A is provided with a heater 1 , and the outside is provided with an insulating layer 2 , and a heat insulation board 12 is provided between the heating chamber A and the mold cold chamber B. the

The innovation of the present invention lies in that a set of jet cooling device and cooling liquid circulation device are arranged in the mold cold room B of the directional solidification furnace. specific:

The spray cooling device includes a nozzle 13 , a coolant conduit and a coolant container 18 connected in sequence. A circle of nozzles 13 is evenly arranged at the furnace outlet at the bottom of the heating chamber A, and the ejection end of the nozzles 13 corresponds to the outer peripheral surface of the ceramic mold shell 3, and a jet pump 14 is arranged on the cooling liquid conduit. The nozzle 13 is an atomizing nozzle, and the number of the nozzle 13 is determined according to the size of the outer contour of the ceramic mold shell 3. The selection of the inner diameter and pressure of the nozzle 13 is based on the principle that the nozzle 13 can spray the cooling liquid mist in the shape of fine mist. In this specific embodiment, the coolant container 18 is a copper cup placed on the water-cooled furnace bottom 12, the jet pump 14 is an electric pump, and the coolant 19 is a liquid gallium-indium-tin alloy with a low melting point.

The coolant circulation device includes a coolant collection pan 16 , a shroud 15 and a return pipe 17 . The cooling liquid collecting pan 16 is arranged on the top periphery of the lift table 7 , and the bottom of the cooling liquid collecting pan 16 is provided with a cooling liquid return hole, and is connected to the cooling liquid container 18 through the return pipe 17 . A shroud 15 is arranged on the inner side of the bottom of the nozzle 13 . The shroud 15 is in the shape of an inverted umbrella, and the bottom opening of the shroud 15 corresponds to the inner side of the cooling liquid collecting pan 16 . the

In this way, the cooling liquid 19 (liquid gallium indium tin alloy) is driven by the jet pump 14 (electric pump), sprayed to the ceramic mold case 3 through the cooling liquid conduit through the nozzle 13, and the cooling of the shroud 15 and the outer peripheral surface of the ceramic mold case 3 The liquid 19 flows back to the cooling liquid container 18 (copper cup) through the cooling liquid collection plate 16 and the return pipe 17, so that the superalloy melt 4 in the ceramic mold shell 3 is fully cooled and directional solidified, and the cooling liquid 19 is recycled, Energy conservation. the

The method for using the directional solidification device of the above-mentioned superalloy, the specific steps are:

Installation work:

1) In the mold cold chamber B of the existing directional solidification furnace, a circle of nozzles 13 is evenly arranged around the furnace outlet at the bottom of the heating chamber A, and the nozzles 13 are passed through the coolant conduit and the coolant container 18 (copper cup) Connected, the jet pump 14 (electric pump) is set on the coolant conduit; specifically: the nozzle 13 is set at the bottom of the heat shield 12 between the heating chamber A and the mold cold chamber B, and the nozzle 13 is set horizontally so that it sprays The mist droplets effectively act on the outer peripheral surface of the ceramic formwork 3 .

2) Place the ceramic formwork 3 on the lifting table 7, and install a cooling liquid collection plate 16 on the outer periphery of the top of the lifting table 7, and use the return pipe 17 to connect the cooling liquid return hole at the bottom of the cooling liquid collecting plate 16 with the cooling liquid The container 18 is connected; specifically: the ceramic formwork 3 is fixedly installed on the upper surface of the lifting table 7 through the chassis 8, and the cooling liquid collecting plate 16 is installed on the bottom of the chassis 8 and the top periphery of the lifting table 7, Also link to each other with the cooling liquid container 18 (copper cup) with return pipe 17 (the flexible pipe that has certain allowance and ductility). the

3) A circle of shroud 15 is arranged on the inner side of the bottom of the nozzle 13, the shroud 15 is in the shape of an inverted umbrella, and its bottom opening corresponds to the inner side of the cooling liquid collection tray 16;

4) Use the indium tin liquid alloy as the cooling liquid 19, and pour it into the cooling liquid container 18 (copper cup);

Inspection before use:

5) Lift the ceramic formwork 3 into the heating chamber A through the lifting workbench 7 and then descend to the mold cold chamber B, turn on the injection pump 14 (electric pump) to compress the cooling liquid 19 to spray the outer peripheral surface of the ceramic formwork 3 in mist form, After the test is successful, close the device; if necessary, adjust the number, position and direction of the nozzles 13, and optimize the injection flow to achieve the best effect.

The use of directional solidification device:

6) Lift the ceramic formwork 3 into the heating chamber A through the lifting table 7, close the furnace door of the directional solidification furnace, and evacuate the inner cavity of the heating chamber A and the mold cold chamber B;

7) Turn on the heater 1 in the heating chamber A, preheat the ceramic formwork 3, and then pour the melted superalloy melt 4 into the ceramic formwork 3;

8) Lower the ceramic mold shell 3 to the mold cold chamber B at a set speed through the lifting table 7;

9) After the ceramic formwork 3 enters the mold cold chamber B, turn on the injection pump 14 at an appropriate moment, so that the cooling liquid 19 is sprayed to the ceramic formwork 3 in the form of droplets, and the superalloy melt 4 inside the ceramic formwork 3 is cooled. forced cooling;

10) The shroud 15 inside the bottom of the nozzle 3 prevents the cooling liquid 19 from splashing out, and the heat-exchanged cooling liquid 19 flows down the ceramic formwork 3, and the cooling liquid 19 on the shroud 15 and the ceramic formwork 3 passes through the cooling liquid collection plate 16 and the return pipe 17 are collected to the cooling liquid container 18, thus completing the circulating work of the cooling liquid 19;

11) When the superalloy directional solidification process is about to end, close the jet pump 14, and open the mold cold chamber B after vacuuming, take out the ceramic mold shell 3, and take out the superalloy casting 5 after directional solidification therefrom.

If continuous pouring is required, a new ceramic formwork 3 can be installed on the lifting table 7, and steps 5) to 11) can be repeated for the next working cycle. the

Claims (7)

1. A directional solidification device for high-temperature alloys, comprising a heating chamber and a mold cold chamber, the heating chamber and the mold cold chamber are vacuum chambers that communicate up and down and are insulated from each other, and a lifting workbench is provided in the chamber, and the lifting workbench The mold shell is placed on top, and the superalloy melt is poured into the mold shell in the heating chamber, and enters the mold cold room with the lifting table to be directional solidified; it is characterized in that: the mold cold room is equipped with a spray cooling device, including sequentially connected nozzles , a cooling liquid conduit and a cooling liquid container, a circle of nozzles is uniformly arranged at the furnace outlet at the bottom of the heating chamber, the spray end of the nozzle corresponds to the outer peripheral surface of the mold shell, and a jet pump is arranged on the cooling liquid conduit. 2. The directional solidification device for superalloys according to claim 1, characterized in that: a cooling liquid circulation device is arranged in the cooling chamber of the mold, including a cooling liquid collecting pan and a return pipe, and the cooling liquid collecting pan is arranged on a lift On the outer periphery of the top of the workbench, the bottom of the cooling liquid collection plate is provided with a cooling liquid return hole, and the cooling liquid container is connected through the return pipe. 3. The directional solidification device for superalloys according to claim 2, characterized in that: there is a shroud around the inner side of the bottom of the nozzle, the shroud is in the shape of an inverted umbrella, and the bottom opening of the shroud corresponds to the inner side of the cooling liquid collection plate. 4. The device for directional solidification of superalloy according to claim 1, characterized in that: the nozzle is an atomizing nozzle. 5 . The directional solidification device for superalloys according to claim 1 , wherein the cooling liquid is liquid gallium indium tin alloy. 6. The directional solidification device for superalloys according to claim 1, characterized in that: the mold shell is a ceramic mold shell. 7. The method for using the directional solidification device of superalloy according to claim 1, characterized in that: the specific steps are: Installation work: 1) In the mold cooling chamber of the existing directional solidification furnace, a circle of nozzles is evenly arranged around the furnace outlet at the bottom of the heating chamber, and the nozzles are connected to the cooling liquid container through the cooling liquid conduit, and the jet pump is arranged on the cooling liquid conduit ; 2) Place the ceramic formwork on the lifting table, install a cooling liquid collection plate on the outer periphery of the top of the lifting table, and use a return pipe to connect the cooling liquid return hole at the bottom of the cooling liquid collecting plate to the cooling liquid container; 3) A circle of shrouds is arranged on the inner side of the bottom of the nozzle, the shrouds are in the shape of an inverted umbrella, and the opening at the bottom corresponds to the inner side of the cooling liquid collection plate; 4) Pour the indium tin liquid alloy into the cooling liquid container as the cooling liquid; Use of directional solidification device: 5) Lift the ceramic mold shell into the heating chamber through the lifting workbench; close the furnace door of the directional solidification furnace, and vacuumize the cavity of the heating chamber and the mold cooling chamber; 6) Turn on the heater in the heating chamber, preheat the ceramic formwork, and then pour the melted superalloy melt into the ceramic formwork; 7) Slowly lower the ceramic mold shell to the mold cold room at a set speed through the lifting table; 8) When the ceramic formwork enters the cold chamber of the casting mold, the jet pump is turned on, so that the cooling liquid is sprayed to the ceramic formwork in the form of droplets, and the superalloy melt inside the ceramic formwork is forcibly cooled; 9) The shroud inside the bottom of the nozzle prevents the coolant from splashing out, and the coolant after heat exchange flows down the ceramic mold shell. The coolant on the shroud and the ceramic mold shell is collected to the coolant container through the coolant collection plate and the return pipe , thus completing the circulation of the coolant; 10) When the directional solidification process of the superalloy is about to end, turn off the jet pump, and open the cold chamber of the casting mold after evacuating, take out the ceramic mold shell, and take out the superalloy casting after directional solidification therefrom.

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