CN113714490A

CN113714490A - Directional solidification device and method

Info

Publication number: CN113714490A
Application number: CN202110984340.2A
Authority: CN
Inventors: 束国刚; 任忠鸣; 玄伟东; 段方苗; 王保军; 任兴孚; 白小龙
Original assignee: China United Heavy Gas Turbine Technology Co Ltd; University of Shanghai for Science and Technology
Current assignee: China United Heavy Gas Turbine Technology Co Ltd; University of Shanghai for Science and Technology
Priority date: 2021-08-25
Filing date: 2021-08-25
Publication date: 2021-11-30
Anticipated expiration: 2041-08-25
Also published as: CN113714490B

Abstract

The invention provides a directional solidification device and a method. The mold is capable of reciprocating between a heat-retaining position and a cooling position where a space is provided between the mold and an inner wall surface of the cooling cylinder. The bin is used for containing cooling particles, the bottom of the bin is provided with an outlet opposite to the interval, and the cooling particles can enter the interval through the outlet and gradually wrap the casting mold in the process that the casting mold moves from the heat preservation position to the cooling position, so that a stable temperature gradient in a single direction is formed, and the directional solidification crystal with excellent performance is favorably obtained. The cooled particles also insulate the holding furnace from heat that radiatively heats the solidified crystal portion of the mold, thereby further increasing the temperature gradient.

Description

Directional solidification device and method

Technical Field

The invention relates to the technical field of directional solidification, in particular to a directional solidification device and a directional solidification method.

Background

The directional solidification technology is used as a main method in the preparation process of columnar crystals and single crystals, and has a high position in the field of advanced high-performance material processing and preparation. The temperature gradient is a key factor affecting the crystal growth rate and the texture and performance quality of the crystal. In a Liquid Metal Cooling method (LMC) in the related art, low-melting-point Liquid Metal is used as a Cooling medium to improve Cooling strength, but the Liquid Metal Cooling method is complex in technology, difficult in process control, prone to cause high-temperature alloy pollution, and prone to reduce quality and performance of the blade.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, embodiments of the present invention propose a directional solidification apparatus having a high temperature gradient. The embodiment of the invention also provides a directional solidification method.

The directional solidification device comprises a heat preservation furnace, wherein the heat preservation furnace is provided with a heat preservation cavity; the cooling cylinder is positioned below the holding furnace; a mold that is capable of reciprocating between a soak position in which the mold is located in the soak chamber and a cool-down position in which the mold is located in the cooling cylinder with a space from an inner wall surface of the cooling cylinder; a lifting assembly carrying the casting mold for driving the casting mold to reciprocate between the keep warm position and the cool down position; a bin for containing cooling particles, the bin having an outlet at a bottom thereof opposite the space through which the cooling particles can enter the space and gradually wrap the mold during movement of the mold from the holding position to the cooling position.

According to the directional solidification device provided by the embodiment of the invention, the cooling particles with high heat conductivity are used as a cooling medium, and when the casting mold moves from the heat preservation position to the cooling position, the cooling particles gradually wrap the casting mold to cool the casting mold, so that a stable temperature gradient in a single direction is formed, and the directional solidification crystal with excellent performance is favorably obtained. The cooled particles also insulate the holding furnace from heat that radiatively heats the solidified crystal portion of the mold, thereby further increasing the temperature gradient.

In some embodiments, the directional solidification apparatus further includes a tray located below the molds and carrying the molds, the lifting assembly is connected to the tray so as to move the molds via the tray, and the cooling particles wrapping the molds are located above the tray.

In some embodiments, the directional solidification apparatus further comprises a baffle below and spaced apart from the tray, the baffle for preventing the magnetic cooling particles from falling.

In some embodiments, the lifting assembly includes a support bar, a platform, and a drive device, the platform is located below the tray, the support bar connects the platform and the cooling tray, and the drive device drives and controls raising and lowering of the platform to ultimately move the casting mold.

In some embodiments, the cooling particles are magnetic cooling particles, and the inner wall surface of the cooling cylinder is provided with a magnet, and the magnetic cooling particles entering the space can be attracted by the magnet.

In some embodiments, the cooling cylinder includes a sleeve, the magnet is cylindrical, the sleeve is sleeved on the magnet, and a cavity is formed between the sleeve and the magnet and used for circulating cooling water.

In some embodiments, the directional solidification apparatus further comprises a container located below the cooling drum, the container opening upward for receiving the magnetic cooling particles.

In some embodiments, a cooling channel is provided in a wall of the silo.

In some embodiments, the directional solidification device further comprises an annular heat insulation plate, the annular heat insulation plate is connected below the holding furnace, the annular heat insulation plate is sleeved on the casting mold, and the annular heat insulation plate isolates the holding cavity from the cooling particles.

According to another aspect of the present invention, there is provided a directional solidification method, including the steps of:

step 1: the lifting assembly enables the casting mould to be in the heat preservation position, and the casting mould is preheated in the heat preservation cavity;

step 2: injecting a molten superalloy into the casting mold;

and step 3: moving the casting mold to the cooling position by using the lifting assembly, wherein the cooling particles enter the interval through the outlet and wrap the casting mold, and the casting mold and the cooling particles exchange heat to enable the high-temperature alloy in the casting mold to be gradually cooled, solidified and formed from bottom to top;

and 4, step 4: the casting mold stays for a preset time after reaching the cooling position until the alloy in the casting mold is completely solidified and formed;

and 5: and after the alloy is completely solidified and formed, taking out the casting mold and the solidified alloy and demolding.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 is a schematic view of a directional solidification apparatus according to an embodiment of the present invention.

Reference numerals:

a directional solidification apparatus 100;

a holding furnace 110; a heat preservation chamber 111; a heat generating member 112; an upper cover 113; a cooling cylinder 120; a magnet 121; a sleeve 122; a cavity 123; a mold 130; a space 131; a support rod 141; a platform 142; a tray 150; a storage bin 160; an outlet 161; a baffle 170; a container 180; an annular heat shield 190; the pellets 200 are cooled.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The basic structure of the directional solidification apparatus 100 provided by the present invention is described below with reference to fig. 1.

As shown in fig. 1, the directional solidification apparatus 100 includes a holding furnace 110, a cooling cylinder 120, a casting mold 130, a lifting assembly, and a bin 160. Wherein the holding furnace 110 defines a holding chamber 111. The cooling cylinder 120 is located below the holding furnace 110.

The mold 130 is capable of reciprocating between a soak position and a cool down position. Wherein, in the heat preservation position, the casting mold 130 is accommodated in the heat preservation cavity 111 for heat preservation, and in the cooling position, the casting mold 130 is located in the cooling cylinder 120 for cooling. When the mold 130 is located at the cooling position, a space 131 is provided between the mold 130 and the inner wall surface of the cooling cylinder 120.

It can be understood that in the directional solidification apparatus 100 provided by the present invention, the holding chamber 111 in the holding furnace 110 serves as a hot end for directional solidification, and the cooling cylinder 120 serves as a cold end for directional solidification, when the mold 130 moves from the holding position to the cooling position, that is, when a portion of the lower end of the mold 130 is drawn out from the holding chamber 111 and extends into the cooling cylinder 120, since the upper half of the mold 130 is located in the holding chamber 111, a stable directional temperature gradient is formed in the mold 130 by the hot end and the cold end, and thus the alloy in the mold 130 can be gradually solidified and formed along the direction of the temperature gradient.

The lifting assembly comprises a tray 150, the tray 150 is located below the casting mold 130 and carries the casting mold 130, and the lifting assembly drives the casting mold 130 to move through the tray 150. That is, the tray 150 is used to carry the molds 130 to drive the molds 130 to reciprocate between the keeping-warm position and the cooling position, i.e., the molds 130 can be raised or lowered by the lifting assembly to reciprocate between the keeping-warm position and the cooling position. As the mold 130 is lowered by the lifting assembly, the mold 130 is gradually pulled out of the soak chamber 111 and into the cooling cylinder 120. When the mold 130 is raised by the elevating assembly, the mold 130 in the cooling cylinder 120 is gradually pulled out and inserted into the soak chamber 111.

The bin 160 is used for containing the cooling particles 200, the bottom of the bin 160 is provided with an outlet 161 opposite to the interval 131, and the cooling particles 200 can enter the interval 131 through the outlet 161 and be positioned among the tray 150, the cooling cylinder 120 and the casting mold 130 so as to wrap the casting mold 130 in the process that the casting mold 130 moves from the heat preservation position to the cooling position. It should be noted that the cooling particles 200 are solid particles with high thermal conductivity, which wrap the mold 130 and perform efficient heat exchange with the mold 130 to cool the mold 130 with a high temperature, and have excellent cooling capability.

The invention also provides a method for directional solidification by using the directional solidification device 100, which comprises the following steps:

step 1: the lifting assembly enables the casting mould 130 to be at a heat preservation position, and the casting mould 130 is preheated in the heat preservation cavity 111;

step 2: injecting the molten superalloy into the mold 130;

and step 3: moving the casting mold 130 to a cooling position by using the lifting assembly, wherein the cooling particles 200 enter the space 131 through the outlet 161 and wrap the casting mold 130, and the casting mold 130 exchanges heat with the cooling particles 200 to gradually cool, solidify and form the high-temperature alloy of the casting mold 130 from bottom to top;

and 4, step 4: the casting mold 130 stays for a preset time after reaching the cooling position until the alloy in the casting mold 130 is completely solidified and formed;

and 5: after the alloy is completely solidified and formed, the mold 130 and the solidified alloy are taken out and demolded.

A specific embodiment of the present invention will be described below with reference to fig. 1.

As shown in fig. 1, the directional solidification apparatus 100 of the present embodiment includes a holding furnace 110, a cooling cylinder 120, a casting mold 130, a lifting assembly, and a bin 160. The cooling cylinder 120 is located below the holding furnace 110. The mold 130 is moved up and down by the elevating assembly between a soaking position in the soaking chamber 111 of the soaking furnace 110 and a cooling position in the cooling drum 120. Optionally, the cooling cylinder 120 is made of steel.

In the embodiment shown in fig. 1, in order to better keep the temperature of the casting mold 130, a heat generating member 112 for heating and keeping the temperature is further provided in the holding furnace 110. Specifically, the heat generating member 112 is disposed around the sidewall of the holding furnace 110, and the temperature of the heat generating member 112 is increased after being energized, and the heat is radiated to the mold 130 to be increased and maintained at a predetermined temperature. The upper end of the holding furnace 110 is provided with an upper cover 113, and the upper cover 113 can prevent the heat in the protection cavity 111 from dissipating. The holding furnace 110 is open at the lower end, and the mold 130 can extend into or out of the holding chamber 111 through the lower end opening of the holding furnace 110.

In the present embodiment, the cooling particles 200 are magnetic cooling particles, that is, the cooling particles 200 have magnetism, the magnet 121 is provided on the inner wall surface of the cooling cylinder 120, and the cooling particles 200 entering the gap can be attracted by the magnet 121. That is, during the movement of the mold 130 from the temperature-keeping position to the cooling position, the magnetic cooling particles 200 entering the space 131 through the outlet 161 can be attracted by the magnet 121 to form a stable barrier, which acts as a heat-insulating plate to better prevent the heat in the temperature-keeping chamber 111 from being excessively radiated downward to the cooling cylinder 120. The cooling particles 200 can enhance heat transfer, increase the cooling rate of the mold 130, and increase the temperature gradient of the solid-liquid interface.

Alternatively, the magnet 121 may be a permanent magnet or an electromagnet.

Optionally, the cooling particles 200 are solid metal particles or solid non-metal particles with high thermal conductivity. Such as iron powder particles, cobalt powder particles, nickel powder particles, and the like.

As shown in fig. 1, the cooling cylinder 120 includes a sleeve 122, the magnet 121 is cylindrical, the sleeve 122 is disposed on the magnet 121, a cavity 123 is formed between the sleeve 122 and the magnet 121, and the cavity 123 is used for flowing cooling water. Therefore, the cooling particles 200 can be cooled after being adsorbed by the magnets 121, and heat exchanged from the mold 130 is continuously conducted out, so that the cooling speed of the mold 130 is increased, and the directional solidification process is facilitated.

As shown in fig. 1, the tray 150 has a certain gap from the magnet 121, which is for fixing and mounting the mold 130. Further, the directional solidification apparatus 100 further includes a baffle 170, the baffle 170 being located below the tray 150 with a space therebetween, the baffle 170 serving to prevent the cooling particles 200 from falling.

After the alloy is completely solidified and formed, the cooling cylinder 120 and the holding furnace 110 are removed, and most of the cooling particles 200 fall off. The directional solidification device 100 further includes a container 180, the container 180 is located below the cooling cylinder 120, and the container 180 is opened upwards for receiving the falling cooling particles 200, so that the cooling particles 200 can be cooled and screened, and then loaded into the bin 160 for recycling.

Optionally, a cooling channel is provided in the wall of the bin 160, that is, the bin 160 can cool the cooling particles 200 located therein, so that the cooling particles 200 can contact the mold 130 and cool the mold 130 better after entering the space 131, thereby further improving the cooling strength and the temperature gradient.

Further, the directional solidification apparatus 100 further includes an annular heat insulation plate 190, the annular heat insulation plate 190 is connected below the holding furnace 110, the annular heat insulation plate 190 is sleeved on the casting mold 130, and the annular heat insulation plate 190 is used for isolating the high-temperature holding cavity 111 from the low-temperature cooling particles 200, so as to prevent excessive heat in the holding cavity 111 from being radiated downwards to the cooling drum 120. Optionally, the annular insulating plate 190 is made of a carbon anvil or an insulating ceramic material.

In this embodiment, the mold 130 is a cylindrical mold with an open top and a closed bottom, the mold 130 is placed on the tray 150, the upper surface of the tray 150 seals the lower opening of the mold 130 to prevent the molten superalloy from leaking, and the upper opening of the mold 130 is used for pouring the molten superalloy into the mold 130. The tray 150 is used to further cool the lower end of the mold 130 and to improve the temperature gradient during directional solidification.

Further, the tray 150 is a water-cooled tray, a cooling water flow channel (not shown in the figure) is arranged in the tray 150, the directional solidification device 100 further comprises a water inlet pipe (not shown in the figure) and a water outlet pipe (not shown in the figure), the water inlet pipe and the water outlet pipe are both connected with the cold area tray 150, the water inlet end of the water inlet pipe is communicated with the water inlet end of the cooling water flow channel so as to introduce cooling water into the cooling water flow channel, the water outlet pipe is communicated with the water outlet end of the cooling water flow channel so as to discharge the cooling water in the cooling water flow channel, and the cooling water flowing in the cooling water flow channel continuously takes away heat so as to keep the tray 150 at a lower temperature, so that the casting mold 130 is continuously and effectively cooled, the temperature gradient in the directional solidification process is ensured, the directional growth of crystals is facilitated, and the preparation of single crystal blades with excellent performance is facilitated.

In this embodiment, as shown in fig. 1, the lifting assembly specifically includes a supporting rod 141, a platform 142 and a driving device (not shown in the figure), wherein the platform 142 is located below the tray 150, the upper end of the supporting rod 141 is connected to the lower surface of the tray 150, and the lower end of the supporting rod 141 is connected to the platform 142. The driving device is used for driving and controlling the platform 142 to ascend and descend, so as to drive the tray 150 to ascend and descend and finally drive the casting mold 130 to reciprocate between the heat preservation position and the cooling position.

As shown in fig. 1, the platform 142 is located below the cooling cylinder 120, and the baffle 170 and the tray 150 move up and down within the ring-shaped magnet 121 by the support rod 141.

The method for performing directional solidification by using the directional solidification device in the embodiment is described below according to the directional solidification device provided in the above-mentioned embodiment, and specifically includes the following steps:

step 1: the lifting assembly enables the casting mold 130 to be at a heat preservation position, and the casting mold 130 is preheated in the heat preservation cavity 111 to reach a preset temperature value;

step 2: injecting the molten superalloy from the upper opening of the holding furnace 110 into the upper opening of the mold 130 in the holding chamber 111, so that the molten superalloy fills the mold 130;

and step 3: the lifting group lowers the driving device driving platform 142 of the driving device 140 to drive the casting mold 130 to move to the cooling position, in the process, the casting mold 130 is gradually wrapped by the cooling particles 200 entering the gap 131, so that the casting mold 130 is cooled, and high-temperature alloy in the casting mold 130 is gradually cooled, solidified and formed from bottom to top due to continuous heat exchange with the cooling particles 200;

and 4, step 4: the casting mold 130 stays for a preset time after reaching the cooling position until the alloy in the casting mold 130 is completely solidified and formed, and the stay time can be selected according to experience;

and 5: after the alloy in the casting mold 130 is completely solidified and formed, taking out the casting mold 130 and the solidified alloy, and demolding to finish one-time directional solidification;

in step 2, the superalloy on the bottom of the mold 130 is cooled and solidified by contacting the pallet 150, and the superalloy on the top of the mold 130 is far from the pallet 150 and is not greatly affected by the cooling, so that a directional temperature gradient is formed inside the mold 130, and the directional solidification process starts.

In summary, the directional solidification apparatus and method provided according to the present embodiment have the following beneficial effects:

the high-heat-conductivity magnetic solid particles are used as a cooling medium, a magnetic field is used for absorbing the magnetic cooling particles to form a barrier, the barrier plays a role of a heat insulation plate and isolates the radiation of heat of a heating section to a cooling section, so that the problems of deformation and damage of a formwork, volatilization of alloy elements, reaction bonding of alloy and the formwork and the like which are easily caused when the temperature is not controlled are solved.

The magnetic cooling particles continuously flow into and wrap the casting mold along with the descending of the casting mold, the heat transfer is enhanced, and the cooling speed is increased, so that the temperature gradient in front of a solid-liquid interface is increased, and the problem of unstable temperature gradient in the directional solidification process is solved.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A directional solidification apparatus, comprising:

the heat preservation furnace is provided with a heat preservation cavity;

the cooling cylinder is positioned below the holding furnace;

a mold that is capable of reciprocating between a soak position in which the mold is located in the soak chamber and a cool-down position in which the mold is located in the cooling cylinder with a space from an inner wall surface of the cooling cylinder;

a lifting assembly carrying the casting mold for driving the casting mold to reciprocate between the keep warm position and the cool down position; a bin for containing cooling particles, the bin having an outlet at a bottom thereof opposite the space through which the cooling particles can enter the space and gradually wrap the mold during movement of the mold from the holding position to the cooling position.

2. The directional solidification device of claim 1 further comprising a tray positioned below the molds and carrying the molds, the elevator assembly being connected to the tray for moving the molds via the tray, the cooled particles surrounding the molds being positioned above the tray.

3. The directional solidification device of claim 2 further comprising a baffle spaced below the tray for preventing the magnetic cooling particles from falling.

4. A directional solidification apparatus according to claim 2 wherein the lifting assembly includes a support bar, a platform, and a drive device, the platform being located below the tray, the support bar connecting the platform and the cooling tray, the drive device driving and controlling raising and lowering of the platform to ultimately move the mold.

5. The directional solidification device according to claim 1, wherein the cooling particles are magnetic cooling particles, and an inner wall surface of the cooling cylinder is provided with a magnet, and the magnetic cooling particles entering the space can be attracted by the magnet.

6. The directional solidification device according to claim 5 wherein the cooling cylinder comprises a sleeve, the magnet is cylindrical and the sleeve is sleeved on the magnet, and a cavity is formed between the sleeve and the magnet and used for circulating cooling water.

7. The directional solidification device of claim 1 further comprising a container positioned below the cooling drum, the container opening upward for receiving the magnetic cooling particles.

8. The directional solidification device of claim 1 wherein a cooling channel is provided in a wall of the storage bin.

9. The directional solidification device according to claim 1, further comprising an annular heat insulating plate connected below the holding furnace, wherein the casting mold is sleeved with the annular heat insulating plate, and the annular heat insulating plate isolates the holding cavity from the cooling particles.

10. A directional solidification method, characterized in that directional solidification is performed using the directional solidification apparatus according to any one of claims 1 to 9, comprising the steps of:

step 2: injecting a molten superalloy into the casting mold;