Ceramic core and shell removal device and removal method for high-temperature alloy precision casting

Abstract

The present invention provides a ceramic core and shell removal device and method for high-temperature alloy precision casting, the device comprising: a core removal pool, in which alkali solution is placed; a heating rod, arranged at the bottom of the core removal pool; a temperature measuring component, arranged in the alkali solution; a control system, connected to the temperature measuring component, and the alkali solution is kept warm within a preset temperature range through the temperature measuring component and the control system; a turntable, located above the core removal pool, and the hollow structure precision casting is suspended in the alkali solution through the turntable; the turntable is connected to the control system, and the control system controls the rotation frequency of the turntable to make the hollow structure precision casting inverted head and tail, so as to facilitate the corroded ceramic core to quickly flow out of the inner cavity of the hollow structure precision casting; an ultrasonic generator, located in the core removal pool and connected to the control system, and the control system controls the start and stop of the ultrasonic generator and the working interval. The device of the present invention has a simple structure and high core removal efficiency, and can provide technical support for the development of high-efficiency and low-cost high-temperature alloy precision castings.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature alloy precision casting, and in particular to a ceramic core and shell removal device and a removal method for high-temperature alloy precision casting. Background Art

[0002] With the development of aerospace equipment, the structural design of high-temperature alloy structural parts is becoming more and more complex, and it is often necessary to adopt the core-shell integrated molding technology, which leads to the increasingly complex structure of the core and shell. However, after high-temperature sintering and pouring of high-temperature alloy, the core-shell structure of the ceramic core and shell is dense, the particles are firmly bonded, the shape is complex, and sometimes accompanied by complex and long-range micro-channels, which makes it extremely difficult to remove it later. At the same time, the unclean removal of the core and shell also reduces the surface quality of precision casting, increases the roughness, and causes unqualified fluorescence detection, which seriously restricts the development process of key high-temperature alloy structural parts and becomes one of the links that must be considered in the design of precision casting process.

[0003] A literature search of the prior art revealed that:

[0004] The US patent with application number US5778963 relates to an alkali liquid spraying core removal process. Specifically, a 20%-50% NaOH or KOH solution with a temperature of 93-316°C, a pressure of 340-680atm, and a concentration of 20%-50% is sprayed from a nozzle with an inner diameter of 0.50-1.78mm to the ceramic core at the root of the blade, and then high-pressure water vapor is used to spray out the ceramic core corroded by the alkali liquid. This patent has a good core removal speed when used for core removal of simple-shaped ceramic cores, but its disadvantage is that direct spraying cannot be applied to new hollow blade castings with complex structures and small ceramic cores.

[0005] The Chinese invention patent with application number 201510661986.1 relates to a high-temperature and high-pressure core-removing device and core-removing method for alumina-based ceramic cores. The patent uses a pressure-resistant kettle as a core-removing device, the core-removing temperature is 350-410°C, and the core-removing liquid is a KOH aqueous solution with a concentration of 55-80%. During the core-removing process, a nitrogen alternating pressure of 15-25MPa or a constant nitrogen pressure of 22-25MPa is applied. This method can remove the hollow blade ceramic core after 2-4 cycles. Its shortcomings are that the patented core-removing device includes a complex pressurization and decompression system, the structure is extremely complex, the core-removing pressure is very high, the energy consumption is large, the cost is high, it is difficult to make a large pressure-resistant kettle for core-removing large high-temperature alloy castings, and there are certain safety hazards.

[0006] The Chinese invention patent with application number 201710445566.9 relates to a method and equipment that can improve the efficiency of core removal of ceramic cores. The patent uses alkali solution as the core removal liquid and clean water as the regular cleaning medium. During core removal, the alkali solution is first introduced into the reaction chamber for corrosion for a period of time, and then the alkali solution is sucked back into the alkali solution chamber by a vacuum air pump, and then clean water is introduced into the reaction chamber, and the core removal products are flushed by boiling clean water, and then the clean water is sucked back into the clean water chamber and the alkali solution is introduced into the reaction chamber again, and the above steps are repeated until the core is completely removed. This method quickly improves some core removal efficiencies, but its shortcomings are that the entire core removal equipment is not only complex, but also relies solely on boiling clean water to flush the core removal products, resulting in low flushing efficiency, and complex and fine micropores or core removal products deep in the flow channel are difficult to discharge smoothly. Summary of the invention

[0007] In view of the defects in the prior art, the purpose of the present invention is to provide a ceramic core and shell removal device and removal method for high-temperature alloy precision casting, so as to solve the problems of complex structure and low core removal efficiency of the existing ceramic core de-coring device, and to provide technical support for the development of efficient and low-cost high-temperature alloy precision castings.

[0008] According to one aspect of the present invention, a ceramic core and shell removal device for high-temperature alloy precision casting is provided, the device comprising:

[0009] a decoring tank, in which alkali solution is placed;

[0010] A heating rod, disposed at the bottom of the core removal tank, and used to heat the alkali solution;

[0011] A temperature measuring element, disposed in the alkali solution, for measuring the temperature of the alkali solution;

[0012] A control system connected to the temperature measuring element, and maintaining the alkali solution within a preset temperature range through the temperature measuring element and the control system;

[0013] A turntable is located above the core removal pool, the plane of the turntable is perpendicular to the horizontal plane of the alkali solution, and the two ends of the hollow structure precision casting are suspended and connected below the turntable, and the hollow structure precision casting is suspended in the alkali solution through the turntable; the turntable is connected to the control system, and the control system controls the rotation frequency of the turntable to make the hollow structure precision casting inverted head and tail, so as to facilitate the corroded ceramic core to quickly flow out of the inner cavity of the hollow structure precision casting;

[0014] The ultrasonic generator is located in the core removal tank and is connected to the control system. The control system controls the start and stop and working interval of the ultrasonic generator.

[0015] Furthermore, two binding ropes are connected to the turntable, and the two binding ropes are respectively connected to two ends of the hollow structure precision casting, and the head and tail ends of the hollow structure precision casting are fixed by the two binding ropes.

[0016] Furthermore, the device also includes a vibration generator, which is located in the alkali solution and is used to quickly vibrate the ceramic core corroded by the alkali solution layer by layer; the vibration generator is connected to the control system, and the control system controls the opening and closing of the vibration generator and the working interval.

[0017] According to another aspect of the present invention, a method for removing a ceramic core and shell for high-temperature alloy precision casting is provided, which is implemented by using the above-mentioned ceramic core and shell removal device for high-temperature alloy precision casting. The method comprises:

[0018] preparing alkali solution, and pouring the alkali solution into the core removal tank;

[0019] The alkali solution is heated by a heating rod, the temperature of the alkali solution is monitored in real time by a temperature measuring element, and the alkali solution is kept warm within a preset temperature range by a control system;

[0020] The head and tail of the hollow structure precision casting are suspended on a turntable and suspended in the alkali solution, and the rotation frequency of the turntable is controlled by the control system to continuously change the placement position of the hollow structure precision casting in the alkali solution;

[0021] The ultrasonic generator is used to accelerate the rapid separation of the corroded ceramic core, and the control system is used to control the working interval of the ultrasonic generator to achieve rapid core removal of the hollow precision casting with a ceramic core.

[0022] Furthermore, the alkali solution is prepared, wherein: the alkali solution is a mixed alkali solution, the mixed alkali solution is made by mixing KOH and NaOH according to a volume percentage of 1:1, and diluting with water to a concentration of 70%-90%.

[0023] Furthermore, the alkali solution is kept warm within a preset temperature range through a control system, wherein the preset temperature range is 160°C-240°C.

[0024] Furthermore, the rotation frequency of the turntable is controlled by the control system, wherein the rotation frequency is one rotation every 10-40 minutes.

[0025] Furthermore, the control system controls the working interval of the ultrasonic generator, wherein the working interval is to stop working for 1-5 minutes every half an hour to prevent the ultrasonic generator from being damaged by overload.

[0026] Furthermore, after accelerating the rapid separation of the corroded ceramic core by the ultrasonic generator and controlling the working interval of the ultrasonic generator by the control system, it also includes: accelerating the rapid separation of the corroded ceramic core by the vibration generator and controlling the working interval of the vibration generator by the control system.

[0027] Furthermore, the control system is used to control the working interval of the vibration generator, wherein: the working interval is to stop working for 1-5 minutes every half an hour.

[0028] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0029] The present invention provides a device and method for removing ceramic cores and shells for high-temperature alloy precision casting, which utilize ultrasound to quickly shake off the ceramic cores corroded by alkali solution layer by layer, and through the method of continuously rotating the hollow structure precision casting, the detached ceramic cores are quickly discharged from the hollow structure precision casting; at the same time, the hollow structure precision casting and the ceramic core have different response frequencies under the action of ultrasound, which also accelerates the penetration of the alkali solution in the ceramic core; under the above-mentioned joint action, the removal effect of the ceramic core and shell can be greatly improved, and the device has a simple structure, low energy consumption, easy operation and high safety and reliability, which shortens the cleaning time of the core and shell in the later stage of precision casting while also reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 It is a structural schematic diagram of a ceramic core and shell removal device for high-temperature alloy precision casting according to an embodiment of the present invention;

[0032] In the figure: 1 is a core removal tank, 2 is alkali solution, 3 is a heating rod, 4 is a temperature measuring component, 5 is a turntable, 6 is a binding rope, 7 is a hollow structure precision casting, 8 is an ultrasonic generator, 9 is a control system, and 10 is a vibration generator. DETAILED DESCRIPTION

[0033] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0034] The embodiment of the present invention provides a ceramic core and shell removal device for high temperature alloy precision casting, referring to Figure 1The device comprises a core removal pool 1, a heating rod 3, a temperature measuring element 4, a control system 9, a turntable 5 and an ultrasonic generator 8, wherein: the core removal pool 1 can be a stainless steel core removal pool, in which a corrosive alkali solution 2 is placed; the heating rod 3 is arranged at the bottom of the core removal pool 1, and the heating rod 3 is used to heat the alkali solution 2, preferably, the heating rod 3 is an electric heating rod; the temperature measuring element 4 is arranged in the alkali solution 2, and is used to measure the temperature of the alkali solution 2, preferably, the temperature measuring element 4 is a thermocouple; the control system 9 is connected to the temperature measuring element 4, and the alkali solution 2 is kept warm within a preset temperature range through the temperature measuring element 4 and the control system 9; the turntable 5 is located at the core removal pool 1, the plane of the turntable 5 is perpendicular to the horizontal plane of the alkali solution 2, and the two ends of the hollow structure precision casting 7 are suspended and connected below the turntable 5, and the hollow structure precision casting 7 is suspended in the alkali solution 2 through the turntable 5; preferably, the turntable 5 is a circular turntable; the turntable 5 is connected to the control system 9, and the control system 9 controls the rotation frequency of the turntable 5 to make the hollow structure precision casting 7 inverted head and tail, so as to facilitate the corroded ceramic core to quickly flow out of the inner cavity of the hollow structure precision casting 7; the ultrasonic generator 8 is located in the core removal pool 1 and is connected to the control system 9, and the control system 9 controls the start and stop of the ultrasonic generator 8 and the working interval.

[0035] In the above embodiment, ultrasound is used to quickly shake off the ceramic core corroded by the alkali solution 2 layer by layer, and the detached ceramic core is quickly discharged from the hollow structure precision casting 7 by continuously rotating the hollow structure precision casting 7; at the same time, the hollow structure precision casting 7 and the ceramic core have different response frequencies under the action of ultrasound, which also accelerates the penetration of the alkali solution 2 in the ceramic core; under the above-mentioned joint action, the removal effect of the ceramic core and shell can be greatly improved, and the device has a simple structure, low energy consumption, easy operation and high safety and reliability, which shortens the cleaning time of the core and shell in the later stage of precision casting while also reducing costs.

[0036] In some embodiments, the alkali solution 2 is a mixed alkali solution, which is a mixture of KOH and NaOH in a volume percentage of 1:1, and is diluted with water to a concentration of 70%-90% to achieve a good corrosion effect.

[0037] In some embodiments, two binding ropes 6 are connected to the turntable 5, and the two binding ropes 6 are respectively connected to two ends of the hollow structure precision casting 7, that is, one end of one of the binding ropes 6 is connected to the turntable 5, and the other end is connected to one end of the hollow structure precision casting 7; one end of the other binding rope 6 is connected to the turntable 5, and the position on the turntable 5 is different from that of the other binding ropes 6, and the other end is connected to the other end of the hollow structure precision casting 7; the head and tail ends of the hollow structure precision casting 7 are fixed by the two binding ropes 6. Preferably, the binding ropes 6 are made of binding steel wire, and the connection is firm and reliable.

[0038] In some embodiments, the device further includes a vibration generator 10, which is located in the alkali solution 2 and is used to quickly shake off the ceramic cores corroded by the alkali solution 2 layer by layer. Preferably, the vibration generator 10 is arranged close to the surface of the hollow structure precision casting 7 to better transmit the vibration energy to the casting; the vibration generator 10 is connected to the control system 9, and the control system 9 controls the opening and closing and working intervals of the vibration generator 10. The strong output of the vibration generator 10 can make up for the shortcomings of insufficient single ultrasonic vibration energy, thereby overcoming the disadvantage of low removal efficiency inside the complex structure, and further improving the removal effect of the ceramic core and shell.

[0039] Another embodiment of the present invention further provides a method for removing a ceramic core and shell for high temperature alloy precision casting, which is implemented by using the above-mentioned ceramic core and shell removal device for high temperature alloy precision casting. Figure 1 , the method comprising:

[0040] S1, prepare alkali solution 2, and pour the alkali solution 2 into the core removal tank 1;

[0041] S2, heating the alkali solution 2 by the heating rod 3, using the temperature measuring element 4 to monitor the temperature of the alkali solution 2 in real time, and keeping the alkali solution 2 within a preset temperature range by the control system 9;

[0042] S3, suspending the hollow structure precision casting 7 on the turntable 5 by its head and tail, and suspending it in the alkali solution 2, controlling the rotation frequency of the turntable 5 by the control system 9, and constantly changing the placement position of the hollow structure precision casting 7 in the alkali solution 2;

[0043] S4, the corroded ceramic core is accelerated to be quickly separated by the ultrasonic generator 8, and the working interval of the ultrasonic generator 8 is controlled by the control system 9 to achieve the rapid core removal of the hollow precision casting with ceramic core.

[0044] Because the shell and core materials are ceramic, the main component is SiO 2 , alkali solution 2 can react with SiO 2 In some embodiments, to increase the speed at which the alkali solution 2 corrodes the ceramic shell and core, in step S1: the alkali solution 2 is a mixed alkali solution, which is a mixture of KOH and NaOH in a volume percentage of 1:1, and is diluted with water to a concentration of 70%-90%. Under this composition, the alkali solution 2 corrodes the ceramic shell and core at the fastest speed.

[0045] In some embodiments, in step S2, according to the temperature resistance of the decoring pool 1 and the boiling point of the alkali solution 2, the preset temperature range is 160°C-240°C to accelerate the corrosion.

[0046] In step S3, the rotation frequency of the turntable 5 is determined according to factors such as the complexity and size of the casting structure. The more complex the casting structure, the more cavities, and the larger the size, the smaller the rotation frequency. The rotation frequency is one rotation every 10-40 minutes, preferably, one rotation every half hour, so that the detached ceramic core can be quickly and promptly discharged from the hollow structure precision casting 7.

[0047] In step S4, the intermittent setting of the ultrasonic generator 8 is to prevent the ultrasonic generator 8 from being damaged by long-term continuous operation. The shorter the intermittent time, the better the core stripping effect. Because after the ultrasound stops, the corrosion rate decreases sharply. In some embodiments, the working interval is to stop working for 1-5 minutes every half an hour. Preferably, the work is stopped for three minutes every half an hour to prevent the ultrasonic generator 8 from being damaged by overload work, while also achieving a better core stripping effect.

[0048] In some embodiments, after the ultrasonic generator 8 is used to accelerate the rapid separation of the corroded ceramic core, and the control system 9 is used to control the working interval of the ultrasonic generator 8, the method further includes: accelerating the rapid separation of the corroded ceramic core by the vibration generator 10, and controlling the working interval of the vibration generator 10 by the control system 9. The intermittent setting is to prevent the vibration generator 10 from being damaged by long-term continuous operation. The shorter the intermittent time, the better the core removal effect, because after the vibration stops, the corrosion rate decreases sharply. The working interval of the vibration generator 10 is in step with that of the ultrasonic generator 8, that is, the working interval is 1-5 minutes. Preferably, the working interval is to stop working for three minutes every half an hour to prevent the vibration generator 10 from being damaged by overload work, and at the same time, it can also achieve a better core removal effect.

[0049] The technical solution of the present application is described in more detail below with more specific embodiments.

[0050] Example 1

[0051] A complex structural casting of aerospace rare earth high-temperature alloy, about 1000mm long and 60mm high, with a complex lattice rod system inside. The core and shell are integrated to prepare the ceramic shell, and the interior is filled with core material. After the precision casting is completed, it needs to be shelled and cored.

[0052] KOH and NaOH were mixed in a volume percentage of 1:1. Due to the relatively complex structure of the ceramic core, the mixed alkali solution was diluted with water to a concentration of 70%. The core removal temperature was 170°C, the rotation frequency of the turntable was one revolution every 30 minutes, the ultrasonic generator stopped working for 3 minutes every half an hour, and the vibration generator stopped working for 3 minutes every half an hour. Alkali boiling was continuously performed for 25 hours in a ceramic core and shell removal device for high-temperature alloy precision casting to complete shelling and core removal, proving that this method can also achieve rapid removal of integrated core and shell with complex structure.

[0053] Example 2

[0054] An aerospace K447A high-temperature alloy integrated casting with a diameter of 300mm and a height of 50mm has 32 complex hollow inner cavity blades distributed around the circumference. The ceramic core used is a silicon oxide-based ceramic core, and core removal is required after precision casting.

[0055] KOH and NaOH were mixed in a volume percentage of 1:1, and water was added to dilute the mixture to prepare a mixed alkali solution with a concentration of 75%. The core removal temperature was 190°C, the rotation frequency of the turntable was one revolution every 10 minutes, the ultrasonic generator was stopped for 1 minute every half hour, and the vibration generator was stopped for 1 minute every half hour. The core was continuously removed for 117 hours in a ceramic core and shell removal device for high-temperature alloy precision casting, proving that this method can achieve rapid core removal of hollow precision castings with silicon oxide-based ceramic cores.

[0056] Example 3

[0057] A large and complex thin-walled casing casting made of aviation K4169 high-temperature alloy has a diameter of 1760mm and a height of about 450mm. There are 12 hollow inclined support plate structures between the inner and outer rings. The ceramic core used is an alumina-based ceramic core. After the precision casting is completed, core removal is required.

[0058] KOH and NaOH were mixed in a volume percentage of 1:1. Since the structure of the ceramic core is relatively simple, the mixed alkali solution was diluted with water to a concentration of 60%. The core removal temperature was 160°C, the rotation frequency of the turntable was one rotation every 40 minutes, the ultrasonic generator stopped working for 5 minutes every half an hour, and the vibration generator stopped working for 5 minutes every half an hour. The core was continuously removed for 19 hours in a ceramic core and shell removal device for high-temperature alloy precision casting, proving that this method can achieve rapid core removal of hollow precision castings with alumina-based ceramic cores.

[0059] In the above embodiment, ultrasound is used to quickly shake off the ceramic cores corroded by alkali solution layer by layer, and the detached ceramic cores are quickly discharged from the hollow structure precision casting by continuously rotating the hollow structure precision casting; at the same time, the hollow structure precision casting and the ceramic core have different response frequencies under ultrasound, which also accelerates the penetration of alkali solution in the ceramic core; the strong output of the vibration generator also makes up for the shortcomings of insufficient single ultrasonic vibration energy, and can overcome the disadvantage of low removal efficiency inside complex structures. Under the above joint action, the removal effect of ceramic core shells such as aluminum oxide or silicon oxide ceramics can be greatly improved.

[0060] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A ceramic core and shell removal device for high-temperature alloy precision casting, characterized in that: include: a de-coring tank, in which alkali solution is placed; A heating rod, disposed at the bottom of the core removal tank, and used to heat the alkali solution; A temperature measuring element, disposed in the alkali solution, for measuring the temperature of the alkali solution; A control system connected to the temperature measuring element, and maintaining the alkali solution within a preset temperature range through the temperature measuring element and the control system; A turntable is located above the core removal pool, the plane of the turntable is perpendicular to the horizontal plane of the alkali solution, and two ends of the hollow structure precision casting are suspended and connected below the turntable, so that the hollow structure precision casting is suspended in the alkali solution through the turntable; The turntable is connected to the control system, and the control system controls the rotation frequency of the turntable to make the hollow structure precision casting inverted head to tail, so as to facilitate the corroded ceramic core to quickly flow out of the inner cavity of the hollow structure precision casting; An ultrasonic generator is located in the core removal tank and connected to the control system, and the control system controls the start and stop and working interval of the ultrasonic generator; The turntable is a circular turntable, and two binding ropes are connected to the turntable, and the two binding ropes are respectively connected to the two ends of the hollow structure precision casting, and the head and tail ends of the hollow structure precision casting are fixed by the two binding ropes; The device also includes a vibration generator, which is located in the alkali solution and is used to quickly vibrate the ceramic core corroded by the alkali solution layer by layer; the vibration generator is arranged close to the surface of the hollow structure precision casting; the vibration generator is connected to the control system, and the control system controls the opening and closing of the vibration generator and the working interval.

2. A method for removing a ceramic core and shell for high-temperature alloy precision casting, which is implemented by using the ceramic core and shell removal device for high-temperature alloy precision casting according to claim 1, characterized in that: include: preparing alkali solution, and pouring the alkali solution into the core removal tank; The alkali solution is heated by a heating rod, the temperature of the alkali solution is monitored in real time by a temperature measuring element, and the alkali solution is kept warm within a preset temperature range by a control system; The head and tail of the hollow structure precision casting are suspended on a turntable and suspended in the alkali solution, and the rotation frequency of the turntable is controlled by the control system to continuously change the placement position of the hollow structure precision casting in the alkali solution; The ultrasonic generator is used to accelerate the rapid separation of the corroded ceramic core, and the control system is used to control the working interval of the ultrasonic generator to achieve the rapid core removal of the hollow precision casting with the ceramic core; After accelerating the rapid separation of the corroded ceramic core by the ultrasonic generator and controlling the working interval of the ultrasonic generator by the control system, the method further includes: accelerating the rapid separation of the corroded ceramic core by the vibration generator and controlling the working interval of the vibration generator by the control system.

3. The method for removing ceramic core and shell for high temperature alloy precision casting according to claim 2, characterized in that: The prepared alkali solution is a mixed alkali solution, which is made by mixing KOH and NaOH in a volume percentage of 1:1, and diluting with water to a concentration of 70%-90%.

4. The method for removing ceramic core and shell for high temperature alloy precision casting according to claim 2, characterized in that: The alkali solution is kept warm within a preset temperature range by a control system, wherein the preset temperature range is 160°C-240°C.

5. The method for removing ceramic core and shell for high temperature alloy precision casting according to claim 2, characterized in that: The rotation frequency of the turntable is controlled by the control system, wherein the rotation frequency is one rotation every 10-40 minutes.

6. The method for removing ceramic core and shell for high temperature alloy precision casting according to claim 2, characterized in that: The control system is used to control the working interval of the ultrasonic generator, wherein the working interval is to stop working for 1-5 minutes every half an hour to prevent the ultrasonic generator from being damaged by overload.

7. The method for removing ceramic core and shell for high temperature alloy precision casting according to claim 2, characterized in that: The control system is used to control the working interval of the vibration generator, wherein the working interval is to stop working for 1-5 minutes every half an hour.

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