Bidirectional and directional solidification equipment

Abstract

The invention discloses bidirectional directional solidification equipment, and aims to pull a mold shell containing molten metal downwards or upwards in the same equipment, so that castings are subjected to directional solidification in opposite directions respectively. Therefore, the bidirectional directional solidification equipment comprises a directional solidification furnace, a hearth of the directional solidification furnace is divided into an upper cooling chamber, a middle heating chamber and a lower cooling chamber from top to bottom, and an upper crystallizer and a mold shell lifting mechanism are arranged in the upper cooling chamber; the mold shell lifting mechanism is used for driving an upper mold shell arranged on the upper crystallizer to descend into the middle heating chamber to be heated or to ascend into the upper cooling chamber to be directionally solidified, and a lower crystallizer and a mold shell lifting mechanism are arranged in the lower cooling chamber. The mold shell lifting mechanism is used for driving a lower mold shell arranged on the lower crystallizer to ascend into the middle heating chamber to be heated or descend into the lower cooling chamber to be directionally solidified.

Description

Technical Field

[0001] The invention belongs to the technical field of directional solidification, and in particular relates to a bidirectional directional solidification device. Background Art

[0002] High-temperature alloy single crystal blade castings are generally produced by a downward pull-type directional solidification process. During the production process, the mold shell filled with alloy liquid is lowered from the heating zone through the insulation board into the cooling chamber to achieve sequential solidification of the casting from the bottom to the top. This process is simple and practical and is widely used in production. However, during the solidification process, the density reversal caused by element segregation causes an unstable state in which the upper part is heavy and the lower part is light in the mushy zone, resulting in strong liquid convection and dendrite breakage, forming vertical chain-like freckle grain defects, and causing the single crystal product to be scrapped. The upward pull-type process changes the solidification direction, which can make the liquid in the mushy zone form a stable state in which the upper part is light and the lower part is heavy, avoiding convection and the formation of freckles. However, the existing directional solidification equipment can only achieve directional solidification in the upward direction by pulling the mold shell downward, and it is difficult to avoid freckle defects in the produced high-temperature alloy blade castings. Therefore, it is necessary to develop a dual-function production casting equipment that can perform both upward and downward directional solidification. Through comparison, it is confirmed that under the same manufacturing conditions, the freckle defects in high-temperature alloy single crystal blades can be avoided by changing the solidification direction, providing a new casting process and equipment for the production of high-quality freckle-free high-temperature alloy single crystal blades. Summary of the invention

[0003] The main purpose of the present invention is to provide a bidirectional directional solidification device, which aims to pull the mold shell containing molten metal downward or upward in the same device, so that the casting can be directional solidified in opposite directions. Through comparison, it is confirmed that the freckle defects in single crystal blades can be eliminated only by changing the solidification direction.

[0004] To this end, the bidirectional directional solidification equipment provided by the present invention includes a directional solidification furnace, the furnace of which is divided into an upper cooling chamber, a middle heating chamber and a lower cooling chamber from top to bottom, the upper cooling chamber is provided with an upper crystallizer and a mold shell lifting mechanism, the mold shell lifting mechanism is used to drive the upper mold shell placed on the upper crystallizer to be lowered into the middle heating chamber for heating or raised to the upper cooling chamber for directional solidification; the lower cooling chamber is provided with a lower crystallizer and a mold shell lifting mechanism, the mold shell lifting mechanism is used to drive the lower mold shell placed on the lower crystallizer to be raised to the middle heating chamber for heating or lowered to the lower cooling chamber for directional solidification.

[0005] Specifically, the smelting system of the directional solidification furnace is arranged above the middle heating chamber, the smelting system includes a smelting crucible, an induction coil and a mechanical arm driving the induction coil to move, an alloy plug that can be melted by the alloy liquid is provided at the bottom gate of the smelting crucible, and the top and bottom of the middle heating chamber are respectively provided with an upper insulation baffle and a lower insulation baffle that can be opened and closed, and the upper insulation baffle is provided with a through hole; When the upper mold shell needs to be melted and poured, the lower insulation baffle closes the bottom opening of the middle heating chamber, and the upper insulation baffle remains open. The upper mold shell is installed on the upper crystallizer, and the melting crucible is fixedly installed on the top of the upper mold shell. The mold shell lifting mechanism drives the upper mold shell to descend into the middle heating chamber for heating and heat preservation. The melting crucible on the upper part of the mold shell is located above the heating chamber. The mechanical arm drives the induction coil to move and cover the melting crucible, and heats and melts the alloy in the melting crucible. After the alloy liquid melts the alloy plug, the alloy liquid is injected into the upper mold shell through the pouring gate; When it is necessary to pour the lower mold shell, the upper insulation baffle closes the top opening of the middle heating chamber, and the lower insulation baffle remains open. The lower mold shell is installed on the lower crystallizer, and the smelting crucible is fixedly installed on the top of the lower mold shell. The mold shell lifting mechanism lifts the lower mold shell to the middle heating chamber for heating and insulation. The smelting crucible on the top of the lower mold shell passes through the through hole on the upper insulation baffle and rises out of the heating chamber. The robotic arm drives the induction coil to move and is sleeved on the outside of the smelting crucible to heat and melt the alloy in the smelting crucible. After the alloy liquid melts the alloy plug, the alloy liquid is injected into the lower mold shell through the pouring gate.

[0006] Specifically, the tops of the upper mold shell and the lower mold shell are each provided with a runner connected to the respective casting cavities, and the gate at the bottom of the smelting crucible is matched and inserted and fixed in the runner.

[0007] Specifically, the middle heating chamber includes a CFC heater, an integral graphite hard felt wrapped outside the CFC heater, and a temperature measuring element. The CFC heater is divided into two independent heating zones, an upper zone and a lower zone.

[0008] Specifically, the mold shell chassis at the top of the upper mold shell is fixedly connected to the upper crystallizer through a bolt assembly, and the upper crystallizer is provided with an avoidance gap for the pouring gate of the smelting crucible to be inserted into.

[0009] Specifically, the bolt assembly includes connecting bolts and nuts. The mold shell chassis of the upper mold shell and the upper crystallizer are provided with connecting holes for the connecting nuts to pass through. The connecting bolts pass through the corresponding connecting holes and are connected to the nuts.

[0010] Specifically, an upper cooling ring capable of moving up and down is provided in the upper cooling chamber above the upper heat insulation baffle, the upper cooling ring is arranged around the top opening, a circulating cooling medium is passed through the upper cooling ring, the upper heat insulation baffle is composed of two left and right first sub-plates, a first driving assembly is provided in the upper cooling chamber for driving the two first sub-plates to be respectively withdrawn or inserted from both sides of the bottom of the upper cooling ring, a first compression spring is provided between the upper cooling chamber and the top of the upper cooling ring, a first lifting wedge surface is provided on the opposite side of the two first sub-plates, and first matching wedge surfaces matching with the first lifting wedge surfaces are provided at the bottom of both sides of the upper cooling ring; When the first driving assembly drives the two first sub-plates to be pulled out from both sides of the upper cooling ring respectively, the upper cooling ring remains in contact with the top of the middle heating chamber under the elastic force provided by the first compression spring, and the top opening of the middle heating chamber is opened; when the first driving assembly drives the two first sub-plates to be inserted into the bottom of the upper cooling ring from both sides, the upper cooling ring moves upward under the lifting action of the first lifting wedge surface, the first compression spring is compressed, and the top opening of the middle heating chamber is closed.

[0011] Specifically, a first guide assembly for guiding the upper cooling ring to move up and down is provided in the upper cooling chamber, the first guide assembly includes a first guide column and a first guide sleeve, the first guide sleeve is fixedly installed in the upper cooling chamber, the first guide column and the first guide sleeve are slidably assembled, and the lower end is fixedly connected to the upper cooling ring, and the first compression spring is connected between the first guide sleeve and the first upper cooling ring.

[0012] Specifically, a lower cooling ring capable of moving up and down is provided in the lower cooling chamber below the lower heat insulation baffle, the lower cooling ring is arranged around the bottom opening, a circulating cooling medium is passed through the lower cooling ring, the lower heat insulation baffle is composed of two left and right second sub-plates, a second driving assembly is provided in the lower cooling chamber for driving the two second sub-plates to be respectively withdrawn or inserted from both sides of the bottom of the lower cooling ring, a second compression spring is provided between the lower cooling chamber and the bottom of the lower cooling ring, a second lifting wedge surface is provided on the opposite side of the two second sub-plates, and second mating wedge surfaces mating with the second lifting wedge surfaces are provided on the tops of both sides of the lower cooling ring; When the second driving assembly drives the two second sub-plates to be pulled out from both sides of the lower cooling ring respectively, the lower cooling ring remains in contact with the bottom of the middle heating chamber under the elastic force provided by the second compression spring, and the bottom opening of the middle heating chamber is opened; when the second driving assembly drives the two second sub-plates to be inserted into the top of the lower cooling ring from both sides, the lower cooling ring moves downward under the lifting action of the second lifting wedge surface, the second compression spring is compressed, and the bottom opening of the middle heating chamber is closed.

[0013] Specifically, the lower cooling chamber is provided with a second guide assembly for guiding the upper and lower movement of the lower cooling ring, the guide assembly includes a second guide column and a second guide sleeve, the second guide sleeve is fixedly installed in the lower cooling chamber, the second guide column and the second guide sleeve are slidably assembled, and the upper end is fixedly connected to the lower cooling ring, and the second compression spring is connected between the second guide sleeve and the lower cooling ring.

[0014] Compared with the prior art, the present invention has the following beneficial effects: the present invention can pull the mold shell containing the molten metal downward or upward in the same device, so that the casting can be directional solidified in opposite directions. One advantage of the present invention is that the two processes share a furnace body, a heating chamber and a melting crucible, and one device can be used as two, which greatly saves manufacturing costs and space; the second advantage is to ensure that the directional solidification experiments in two different directions are carried out under exactly the same process conditions (including vacuum degree, heater temperature, mold shell pulling speed and furnace chamber atmosphere, etc.), which is conducive to the comparison of results and confirming the influence of solidification direction on solidification structure such as freckle defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 is a stereoscopic diagram of a bidirectional directional solidification device provided by an embodiment of the present invention; Figure 2 is a schematic diagram of a furnace of a bidirectional directional solidification device provided in an embodiment of the present invention (using a mold shell lifting mechanism); Figure 3 is a schematic diagram of a furnace of a bidirectional directional solidification device provided in an embodiment of the present invention (using a mold shell lifting mechanism); Figure 4 It is a schematic diagram of the process of counter-gravity directional solidification by the downward pulling method provided in an embodiment of the present invention; Figure 5 It is a schematic diagram of the upward pulling operation of the bidirectional directional solidification device provided by an embodiment of the present invention; Figure 6 It is a schematic diagram of a process of directional solidification under gravity using an upward pulling method provided by an embodiment of the present invention; Figure 7 It is a schematic diagram of the connection between the upper mold shell and the upper crystallizer provided in an embodiment of the present invention; Figure 8 This is a photo of the process of preparing single crystal blades using the upper pull solidification method; Among them: 1. directional solidification furnace; 2. furnace; 201. upper cooling chamber; 202. middle heating chamber; 203. lower cooling chamber; 3. upper crystallizer; 4. mold shell lifting mechanism; 5. lower crystallizer; 6. mold shell lifting mechanism; 7. smelting system; 701. smelting crucible; 7011. pouring gate; 702. induction coil; 703. mechanical arm; 704. alloy plug; 8. upper insulation baffle; 801. first sub-plate; 9. lower insulation baffle; 901. second sub-plate; 10. CFC heater; 11. graphite hard felt; 12. bolt assembly ; 13. Avoidance gap; 14. Connecting hole; 15. Upper cooling ring; 16. First drive assembly; 17. First clamping spring; 18. First lifting wedge surface; 19. First matching wedge surface; 20. First guide column; 21. First guide sleeve; 22. Lower cooling ring; 23. Second drive assembly; 24. Second clamping spring; 25. Second lifting wedge surface; 26. Second matching wedge surface; 27. Second guide column; 28. Second guide sleeve; 29. ​​Guardrail; 30. Air pressure control system; 31. Power supply system; 32. Lower mold shell; 33. Upper mold shell. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0020] See also Figure 1 and Figure 2 A bidirectional directional solidification device includes a directional solidification furnace 1, wherein the furnace 2 of the directional solidification furnace 1 is divided into an upper cooling chamber 201, a middle heating chamber 202 and a lower cooling chamber 203 from top to bottom, wherein an upper crystallizer 3 and a mold shell lifting mechanism 4 are arranged in the upper cooling chamber 201, and a lower crystallizer 5 and a mold shell lifting mechanism 6 are arranged in the lower cooling chamber 203, wherein the mold shell lifting mechanism 4 is used to drive an upper mold shell 33 arranged on the upper crystallizer 3 to be lowered into the middle heating chamber 202 for heating or to be raised to the upper cooling chamber 201 for directional solidification, and the mold shell lifting mechanism 6 is used to drive a lower mold shell 32 arranged on the lower crystallizer 5 to be raised to the middle heating chamber 202 for heating or to be lowered to the lower cooling chamber 203 for directional solidification. The cooling medium introduced into the crystallizer may be water, and of course, other cooling media may also be used, which will not be described in detail here.

[0021] This embodiment can pull the mold shell containing molten metal downward or upward in the same device, so that the casting can be directional solidified in opposite directions. The two processes share a furnace body, a heating chamber and a smelting system 7. One device can be used as two devices, which greatly saves manufacturing costs and space. In addition, it can ensure that the directional solidification experiments in two different directions are carried out under exactly the same process conditions (including vacuum degree, furnace temperature, furnace chamber atmosphere, etc.), which is conducive to comparison of results and confirmation of the influence of solidification direction on solidification structure such as freckle defects.

[0022] See also Figure 1-Figure 6 In some embodiments, the melting system 7 of the directional solidification furnace 1 is arranged in the upper cooling chamber 201, and the melting system 7 includes a melting crucible 701 (with the mold shell), an induction coil 702, and a mechanical arm 703 that drives the induction coil 702 to move. The mechanical arm 703 has multiple degrees of freedom and can drive the induction coil 702 to perform complex three-dimensional movements in the upper cooling chamber 201. The induction coil 702 is designed to be spiral-shaped, and the induction coil 702 can be sleeved on the melting crucible 701 under the drive of the mechanical arm 703. As for the specific structure of the mechanical arm 703, they are all existing technical structures and will not be repeated here. An alloy plug 704 that can be melted by the alloy liquid is provided on the pouring port 7011 of the smelting crucible 701, and an upper insulation baffle 8 and a lower insulation baffle 9 that can be opened and closed are respectively provided on the top and bottom of the middle heating chamber 202. A through hole is provided on the upper insulation baffle. By controlling the opening and closing state of the upper insulation baffle 8, the isolation and connection between the upper cooling chamber 201 and the middle heating chamber 202 can be controlled. By controlling the opening and closing state of the lower insulation baffle 9, the isolation and connection between the lower cooling chamber 203 and the middle heating chamber 202 can be controlled.

[0023] See also Figure 3 and Figure 4When the above-mentioned bidirectional directional solidification equipment is used for reverse gravity solidification, the upper heat insulation baffle 8 closes the top opening of the middle heating chamber 202, and the lower heat insulation baffle 9 remains open. The lower mold shell is placed on the lower crystallization plate of the mold shell lifting mechanism 6, and the melting crucible 701 is fixedly installed on the top of the lower mold shell. The mold shell lifting mechanism 6 drives the crystallization plate to move upward to push the lower mold shell into the middle heating chamber 202, and is heated to a preset insulation temperature together with the furnace. The melting crucible 701 on the top of the lower mold shell 1 is lifted into the upper cooling chamber 201 through the through hole on the upper heat-insulating partition board. The mechanical arm 703 drives the induction coil 702 to move and cover the melting crucible 701. When the heating chamber is powered on and heated, the movable coil starts to increase the power to bake and preheat the alloy material in the crucible. After the upper mold shell in the heating chamber reaches the preset temperature and is kept warm for a period of time, the alloy material begins to melt. After the alloy liquid melts the alloy plug 704 through heat transfer, the alloy liquid is injected into the lower mold shell through the pouring port 7011. The upper mold shell is left to stand for a certain period of time. After the alloy liquid in the upper mold shell is stable, the mold shell lifting mechanism 6 starts to pull downward and pull the upper mold shell out of the middle heating chamber 202 (insulation bag) at a preset pulling rate. In the process of pulling the upper mold shell downward, the lower part of the mold shell is cold and the upper part is hot, forming a temperature gradient from bottom to top, thereby realizing directional solidification from bottom to top, that is, solidification against gravity. The alloy plug 704 is made of a material similar to the alloy material, and may also be a pure nickel alloy plug 704 or the like.

[0024] See also Figure 4 and Figure 5 When the above-mentioned bidirectional directional solidification equipment is used for gravity solidification, the lower heat insulation baffle 9 closes the bottom opening of the middle heating chamber 202, and the upper heat insulation baffle 8 remains open. The upper mold shell is installed on the upper crystallizer 3, and the melting crucible 701 is fixedly installed on the top of the upper mold shell. The mold shell lifting mechanism 4 drives the upper mold shell to descend to the middle heating chamber 202, and is heated to a preset insulation temperature together with the furnace. The melting crucible 701 is located in the upper cooling chamber 201, and the robot arm 703 drives the induction coil 702 to move The induction coil 702 is movable and sleeved outside the melting crucible 701. During the process of the mold shell heating up, the induction coil 702 starts to increase the power to bake and preheat the alloy material. After the alloy is melted, it will stand in the crucible for a certain period of time. After the alloy liquid melts the alloy plug 704 pre-placed at the bottom of the crucible through heat transfer, the alloy liquid is injected into the upper mold shell through the pouring port 7011 at the bottom of the melting crucible. After the upper mold shell stands for a certain period of time to stabilize the alloy liquid, the mold shell pulling mechanism 4 starts to pull upward and pull the upper mold shell out from the top of the heating chamber at a preset pulling rate. During the process of the upper mold shell being pulled upward, the upper mold shell forms a temperature gradient from top to bottom, thereby realizing directional solidification from top to bottom, that is, solidification along gravity. Among them, the mold shell pulling mechanism 4 and the mold shell lifting mechanism 6 can both adopt a screw mechanism driven by a motor, and of course other commonly used linear drive mechanisms can also be adopted.

[0025] It can be understood that, in order to facilitate the assembly of the melting crucible 701 and the mold shell, runners connected to the respective casting cavities are provided on the top of the upper mold shell and the lower mold shell, and the shape of the gate 7011 at the bottom of the melting crucible 701 is designed to be a cone with a larger upper part and a smaller lower part. The shape of the upper inner cavity of the gate is adapted to the shape of the gate 7011. When the melting crucible 701 needs to be assembled with the mold shell, the gate 7011 needs to be inserted into the gate, and the melting crucible 701 can be firmly installed on the mold shell. With the above assembly method, after the mold shell is cast, the melting crucible 701 can be pulled out and reused.

[0026] See also Figure 2 and Figure 3 Specifically, the middle heating chamber 202 includes a CFC heater 10, an integral graphite hard felt 11 wrapped outside the CFC heater 10, and a temperature measuring element (not shown in the figure). The CFC heater 10 is divided into two independent upper and lower heating zones. The middle heating chamber 202 uses domestic CFC as the heater material, which is made of carbon fiber materials through weaving, vapor deposition and other processes, with high structural strength and uniform resistance. The long-term working temperature under vacuum can reach 1800°C, and it has the characteristics of uniform heating, fast heating speed, high strength, thin wall and long service life. The comprehensive performance is much higher than that of traditional graphite heating bodies. Due to the thin wall thickness (3~5 mm), the CFC heater 10 itself has a small heat capacity, so it is easy to heat and cool quickly, and has high efficiency. The external insulation material of the heater adopts an integral graphite hard felt 11, which has a high degree of integration, good thermal insulation effect and convenient disassembly and assembly. In view of the difficulty of fast heat dissipation rate and great heat preservation difficulty of the solidification interface, CFC heater 10 adopts upper and lower dual-zone heating. The maximum heating temperature of the upper and lower zones is 1650℃. It can perform dual-zone temperature control and accurately control the temperature gradient in the hot zone. At the same time, heating can be freely switched between manual and automatic. It is equipped with a high-power thyristor voltage regulator power supply, and the power supply adopts air-cooled heat dissipation mode.

[0027] See also Figure 2 and Figure 7 In some embodiments, the mold chassis at the top of the upper mold shell is fixedly connected to the upper crystallizer 3 through a bolt assembly 12, and the upper crystallizer 3 is provided with an avoidance gap 13 for the pouring port 7011 of the melting crucible 701 to be inserted. The bolt assembly 12 includes a connecting bolt and a nut. The mold chassis of the upper mold shell and the upper crystallizer 3 are provided with a connecting hole 14 for the connecting nut to pass through. The connecting bolt passes through the corresponding connecting hole 14 and is connected with the nut to fix the upper mold shell on the upper crystallizer 3. In order to form the connecting hole 14 on the mold chassis, when preparing the wax mold, it is necessary to install a wax column on the wax mold chassis, and clean the top after each slurry and sanding, and form the bolt connection hole 14 of the mold shell bottom plate after dewaxing, and then connect the mold shell and the crystallizer with carbon fiber bolts.

[0028] In some embodiments, in order to further improve the effect of the upper cooling chamber 201, an upper cooling ring 15 capable of moving up and down is provided above the upper insulation baffle 8 in the upper cooling chamber 201. The upper cooling ring 15 is arranged around the top opening of the heating chamber. A circulating cooling medium is passed through the upper cooling ring 15. The upper insulation baffle 8 is composed of two left and right first sub-plates 801. The upper cooling chamber 201 is provided with a first driving component 16 for driving the two first sub-plates 801 to be respectively extracted or inserted from the bottom sides of the upper cooling ring 15. The upper cooling chamber 201 and the upper cooling ring 15 are connected. A first compression spring 17 is provided between the tops, a first lifting wedge surface 18 is provided on the opposite side of the two first sub-plates 801, and first matching wedge surfaces 19 matching with the first lifting wedge surfaces 18 are provided at the bottoms on both sides of the upper cooling ring 15. The first lifting wedge surface 18 and the first matching wedge surface 19 cooperate to form a wedge-shaped lifting mechanism. When the two first sub-plates 801 are respectively inserted from both sides of the upper insulation baffle 8, the upper insulation baffle 8 moves upward under the lifting action of the wedge-shaped lifting mechanism, so that the first sub-plate 801 can be smoothly inserted under the upper insulation baffle 8, and the top is opened and closed.

[0029] When the first driving assembly 16 drives the two first sub-plates 801 to be pulled out from both sides of the upper cooling ring 15 respectively, the upper cooling ring 15 remains in contact with the top of the middle heating chamber 202 under the elastic force provided by the first compression spring 17. At this time, the top of the middle heating chamber 202 is opened, and when the mold shell lifting mechanism 4 starts to lift the upper mold shell upward, water flows through the upper cooling ring 15. When the upper mold shell is lifted and passes through the upper cooling ring 15, the outer surface of the upper mold shell radiates heat to the inner wall of the upper cooling ring 15, thereby improving the cooling efficiency and promoting the heat dissipation of the casting.

[0030] When the first driving assembly 16 drives the two first sub-plates 801 to be inserted into the bottom of the upper cooling ring 15 from both sides, the upper cooling ring 15 moves upward under the lifting action of the first lifting wedge surface 18, and the first compression spring 17 is compressed. When the upper insulation baffle 8 is fully inserted into the bottom of the upper cooling ring 15, the top opening of the middle heating chamber 202 is closed, thereby ensuring the stability of the temperature field in the middle heating chamber 202 when it is pulled downward for solidification.

[0031] Specifically, in order to effectively ensure the movement accuracy of the upper cooling ring 15, a first guide assembly for guiding the upper cooling ring 15 to move up and down is provided in the upper cooling chamber 201. The first guide assembly includes a first guide column 20 and a first guide sleeve 21. The first guide sleeve 21 is fixedly installed in the upper cooling chamber 201. The first guide column 20 and the first guide sleeve 21 are slidably assembled, and the lower end is fixedly connected to the upper cooling ring 15. The first compression spring is connected between the first guide sleeve 21 and the first upper cooling ring 15.

[0032] In some embodiments, similar to the upper cooling chamber 201, a lower cooling ring 22 that can move up and down can also be set in the lower cooling chamber 203 below the lower insulation baffle 9. The lower cooling ring 22 is set around the bottom opening, and a circulating cooling medium is passed through the lower cooling ring 22. The lower insulation baffle 9 is composed of two left and right second sub-plates 901. The lower cooling chamber 203 is provided with a second driving component 23 for driving the two second sub-plates 901 to be respectively pulled out or inserted from the two sides of the bottom of the lower cooling ring 22. A second clamping spring 24 is provided between the lower cooling chamber 203 and the bottom of the lower cooling ring 22. A second lifting wedge surface 25 is provided on the opposite side of the two second sub-plates 901, and second mating wedge surfaces 26 mating with the second lifting wedge surfaces 25 are provided on the tops of both sides of the lower cooling ring 22 to form a wedge-shaped lifting mechanism.

[0033] In this embodiment, when the second drive assembly 23 drives the two second sub-plates 901 to be drawn out from both sides of the lower cooling ring 22, the lower cooling ring 22 is kept in contact with the bottom of the middle heating chamber 202 under the elastic force provided by the second compression spring 24, and the bottom opening of the middle heating chamber 202 is opened. At this time, the lower mold shell can be pulled downward for solidification. When the second drive assembly 23 drives the two second sub-plates 901 to be inserted into the top of the lower cooling ring 22 from both sides, the lower cooling ring 22 moves downward under the lifting action of the second lifting wedge surface 25, and the second compression spring 24 is compressed. When the lower heat insulation baffle 9 is fully inserted between the lower cooling ring 22 and the middle heating chamber 202, the bottom opening of the middle heating chamber 202 is closed, thereby ensuring the stability of the temperature field in the middle heating chamber 202 when it is lifted upward for solidification. As for the specific structures of the first drive assembly 16 and the second drive assembly 23, both adopt the existing linear drive mechanism, which will not be described here.

[0034] Similarly, a second guide assembly for guiding the lower cooling ring 22 to move up and down can also be provided in the lower cooling chamber 203. The guide assembly includes a second guide column 27 and a second guide sleeve 28. The second guide sleeve 28 is fixedly installed in the lower cooling chamber 203. The second guide column 27 is slidably assembled with the second guide sleeve 28, and the upper end is fixedly connected to the lower cooling ring 22. The second compression spring is connected between the second guide sleeve 28 and the lower cooling ring 22. In addition, to ensure safety, a guardrail 29 is provided on the periphery of the directional solidification furnace 1, and also includes an air pressure control system 30 for vacuuming the furnace chamber of the directional solidification furnace and a power supply system 31 for powering the furnace body. In this embodiment, the directional solidification furnace is a vacuum furnace. Of course, for those skilled in the art, an atmosphere protection furnace can also be used.

[0035] This case mainly tests the function of the upward pull solidification method of this equipment, including the following steps: (1) According to the requirements of the upper pull solidification process, the pressed leaf wax mold is formed into a corresponding wax tree structure ( Figure 8a). The upper part of the wax tree is the chassis wax mold, which is connected to 8 seed crystal tube wax molds, each of which is connected to two layers of blade wax molds. The lowest part is the cross-runner wax mold that combines circular and radial shapes. Each module can be used to prepare 16 single crystal blades.

[0036] (2) The ceramic mold shell is prepared by the lost wax method. After multiple slurry dipping and sanding to reach a certain shell thickness, it is fully dried and then dewaxed and fired to obtain a mold shell for casting single crystal blades, such as Figure 8 As shown in b.

[0037] (3) The prepared mold shell is subjected to a methylene blue leak test to confirm that the mold shell is dense and leak-free. A seed crystal rod of the same alloy material (CMSX-4) is placed in the seed crystal tube of the mold shell, and then the mold shell is fixed to the crystallization plate with carbon fiber bolts. The cut CMSX-4 alloy material is placed in the melting crucible on the top of the mold shell, and the mold shell is lowered into the heating chamber, with the crucible on the top of the mold shell remaining on the top of the heating chamber.

[0038] (4) Rotate the induction coil from the outside to the position of the melting crucible, and lower it to put the crucible in the center of the coil.

[0039] The furnace is evacuated, the heater is powered on, the temperature of the heating chamber is raised to 1550°C and kept warm to preheat the mold shell.

[0040] (5) The induction coil is energized to heat and melt the alloy material in the crucible. The alloy plug in the through hole at the bottom of the crucible is also melted by the superheated alloy liquid. The alloy liquid flows downward into the sprue in the center column tube to fill the mold. The scum on the upper surface of the alloy liquid floats on the residual liquid and remains in the crucible. It will not enter the mold cavity, reducing the inclusion defects of the casting.

[0041] (6) The alloy liquid enters the casting cavity from the mold shell sprue through the bottom runner. The alloy liquid level rises and melts the protruding part of the seed crystal.

[0042] (7) After the alloy material is melted and filled into the mold, the coil rises, separates from the crucible and moves outward without affecting the rising and pulling of the mold shell.

[0043] (8) The mold shell filled with alloy liquid is pulled upward at a speed of 3 mm / min, so that the alloy liquid starts from the interface of the remelted seed crystal and solidifies from top to bottom in a gravity-directed manner ( Figure 8 c).

[0044] (9) After directional solidification is completed, the casting with the mold shell continues to rise to the upper cooling chamber of the furnace, the casting is removed and taken out, and the outer mold shell is removed to obtain a complete casting string ( Figure 8 d). The upper part of the blade casting in the photo is the seed crystal rod.

[0045] (10) Cut off the gating system of the casting string to obtain a single blade casting ( Figure 8e), and then conduct detection and analysis work.

[0046] from Figure 8 As can be seen in Figure e, all small blade samples have smooth surfaces, good shape integrity, and no obvious casting defects. All small blades were macro-chemically etched, and the grains of the small blade samples were inspected by visual + stereoscopic methods. The single crystal of the blade basin and blade back of all blade samples is intact, and the entire blade is composed of one grain. No freckles or other grain defects were found, which are good single crystal blade castings.

[0047] Unless otherwise stated, any technical solution disclosed in the present invention disclosed above, if it discloses a numerical range, then the disclosed numerical range is a preferred numerical range, and any technician in the field should understand that the preferred numerical range is only a numerical value with a more obvious technical effect or representative value among many implementable numerical values. Since there are too many numerical values ​​to be exhaustive, the present invention discloses some numerical values ​​to illustrate the technical solution of the present invention, and the numerical values ​​listed above should not constitute a limitation on the scope of protection of the present invention.

[0048] At the same time, if the above-mentioned invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connected by bolts or screws), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by one-piece molding using a casting process) (except when it is obviously impossible to use an one-piece molding process).

[0049] In addition, the terms used in any technical solution disclosed in the present invention to indicate positional relationships or shapes include states or shapes that are similar, similar or close to them unless otherwise stated. Any component provided by the present invention may be assembled from multiple separate components or may be a separate component manufactured by an integrated molding process.

[0050] The above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A bidirectional directional solidification device, comprising a directional solidification furnace, characterized in that: The furnace of the directional solidification furnace is divided into an upper cooling chamber, a middle heating chamber and a lower cooling chamber from top to bottom. An upper crystallizer and a mold shell lifting mechanism are arranged in the upper cooling chamber, and a lower crystallizer and a mold shell lifting mechanism are arranged in the lower cooling chamber. The mold shell lifting mechanism is used to drive the upper mold shell placed on the upper crystallizer to be lowered into the middle heating chamber for heating or to be raised to the upper cooling chamber for directional solidification. The mold shell lifting mechanism is used to drive the lower mold shell placed on the lower crystallizer to be raised to the middle heating chamber for heating or to be lowered to the lower cooling chamber for directional solidification.

2. The bidirectional directional solidification equipment according to claim 1, characterized in that: The smelting system of the directional solidification furnace is arranged on the middle heating chamber, and the smelting system includes a smelting crucible, an induction coil and a mechanical arm driving the induction coil to move. The bottom gate of the smelting crucible is provided with an alloy plug that can be melted by the alloy liquid. The top and bottom of the middle heating chamber are respectively provided with an upper insulation baffle and a lower insulation baffle that can be opened and closed, and the upper insulation baffle is provided with a through hole; When it is necessary to pour the upper mold shell, the lower insulation baffle closes the bottom opening of the middle heating chamber, and the upper insulation baffle remains open. The upper mold shell is installed on the upper crystallizer, and the smelting crucible is fixedly installed on the top of the upper mold shell. The mold shell lifting mechanism drives the upper mold shell to descend to the middle heating chamber for heating and heat preservation. The smelting crucible on the upper part of the mold shell is located at the top of the heating chamber. The mechanical arm drives the induction coil to move and cover the smelting crucible, heats and melts the alloy in the smelting crucible, and after the alloy liquid melts the alloy plug, the alloy liquid is injected into the upper mold shell through the pouring gate; When it is necessary to pour the lower mold shell, the upper insulation baffle closes the top opening of the middle heating chamber, and the lower insulation baffle remains open. The lower mold shell is installed on the lower crystallizer, and the smelting crucible is fixedly installed on the top of the lower mold shell. The mold shell lifting mechanism lifts the lower mold shell to the middle heating chamber for heating and insulation. The smelting crucible on the top of the lower mold shell passes through the through hole of the upper insulation baffle and rises above the heating chamber. The robotic arm drives the induction coil to move and is sleeved on the outside of the smelting crucible to heat and melt the alloy in the smelting crucible. After the alloy liquid melts the alloy plug, the alloy liquid is injected into the lower mold shell through the pouring gate.

3. The bidirectional directional solidification equipment according to claim 2, characterized in that: The tops of the upper mold shell and the lower mold shell are both provided with runners connected to their respective casting cavities, and the gate at the bottom of the smelting crucible is matched and inserted and fixed in the runners.

4. The bidirectional directional solidification equipment according to claim 2, characterized in that: The middle heating chamber comprises a CFC heater, an integral graphite hard felt wrapped outside the CFC heater, and a temperature measuring element. The CFC heater is divided into two independent heating zones, an upper zone and a lower zone.

5. The bidirectional directional solidification equipment according to claim 2, characterized in that: The mold shell chassis at the top of the upper mold shell is fixedly connected to the upper crystallizer through a bolt assembly, and the upper crystallizer is provided with an avoidance notch for the pouring gate of the smelting crucible to be inserted.

6. The bidirectional directional solidification equipment according to claim 5, characterized in that: The bolt assembly includes connecting bolts and nuts. The mold shell chassis of the upper mold shell and the upper crystallizer are provided with connecting holes for the connecting nuts to pass through. The connecting bolts are connected to the nuts after passing through the corresponding connecting holes.

7. The bidirectional directional solidification equipment according to any one of claims 2 to 6, characterized in that: An upper cooling ring capable of moving up and down is provided in the upper cooling chamber above the upper heat insulation baffle, the upper cooling ring is arranged around the top opening, a circulating cooling medium is passed through the upper cooling ring, the upper heat insulation baffle is composed of two left and right first sub-plates, a first driving assembly is provided in the upper cooling chamber for driving the two first sub-plates to be respectively withdrawn or inserted from both sides of the bottom of the upper cooling ring, a first compression spring is provided between the upper cooling chamber and the top of the upper cooling ring, a first lifting wedge surface is provided on one side opposite to the two first sub-plates, and first matching wedge surfaces matching with the first lifting wedge surfaces are provided at the bottoms of both sides of the upper cooling ring; When the first driving assembly drives the two first sub-plates to be pulled out from both sides of the upper cooling ring respectively, the upper cooling ring remains in contact with the top of the middle heating chamber under the elastic force provided by the first compression spring, and the top opening of the middle heating chamber is opened; when the first driving assembly drives the two first sub-plates to be inserted into the bottom of the upper cooling ring from both sides, the upper cooling ring moves upward under the lifting action of the first lifting wedge surface, the first compression spring is compressed, and the top opening of the middle heating chamber is closed.

8. The bidirectional directional solidification equipment according to claim 7, characterized in that: A first guide assembly is provided in the upper cooling chamber to guide the upper cooling ring to move up and down. The first guide assembly includes a first guide column and a first guide sleeve. The first guide sleeve is fixedly installed in the upper cooling chamber. The first guide column is slidably assembled with the first guide sleeve, and the lower end is fixedly connected to the upper cooling ring. The first compression spring is connected between the first guide sleeve and the first upper cooling ring.

9. The bidirectional directional solidification equipment according to claim 7, characterized in that: A lower cooling ring capable of moving up and down is provided in the lower cooling chamber below the lower heat insulation baffle, the lower cooling ring is arranged around the bottom opening, a circulating cooling medium is passed through the lower cooling ring, the lower heat insulation baffle is composed of two left and right second sub-plates, a second driving assembly is provided in the lower cooling chamber for driving the two second sub-plates to be respectively withdrawn or inserted from both sides of the bottom of the lower cooling ring, a second compression spring is provided between the lower cooling chamber and the bottom of the lower cooling ring, a second lifting wedge surface is provided on the opposite side of the two second sub-plates, and second matching wedge surfaces matching with the second lifting wedge surfaces are provided on the tops of both sides of the lower cooling ring; When the second driving assembly drives the two second sub-plates to be pulled out from both sides of the lower cooling ring respectively, the lower cooling ring remains in contact with the bottom of the middle heating chamber under the elastic force provided by the second compression spring, and the bottom opening of the middle heating chamber is opened; when the second driving assembly drives the two second sub-plates to be inserted into the top of the lower cooling ring from both sides, the lower cooling ring moves downward under the lifting action of the second lifting wedge surface, the second compression spring is compressed, and the bottom opening of the middle heating chamber is closed.

10. The bidirectional directional solidification equipment according to claim 9, characterized in that: A second guide assembly is provided in the lower cooling chamber to guide the upper and lower movement of the lower cooling ring. The guide assembly includes a second guide column and a second guide sleeve. The second guide sleeve is fixedly installed in the lower cooling chamber. The second guide column is slidably assembled with the second guide sleeve, and the upper end is fixedly connected to the lower cooling ring. The second compression spring is connected between the second guide sleeve and the lower cooling ring.

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