JP5642461B2 - Combustion chamber of rocket engine and method for manufacturing hollow structure - Google Patents

Description

  The present invention relates to a combustion chamber of a rocket engine and a method for manufacturing a hollow structure.

  A structure having a space inside is known (hereinafter also referred to as “hollow structure”). If the space inside the hollow structure is used as a cooling flow path through which the refrigerant flows, the hollow structure can be cooled. As an application example of such a hollow structure, a combustion chamber of an aerospace rocket engine can be considered. Since the combustion chamber of a rocket engine becomes extremely hot during use, it must be used while being cooled. For this reason, the combustion chamber is provided with a plurality of cooling passages for circulating the refrigerant as a cooling structure.

  1A to 1D are explanatory views showing a method for manufacturing a combustion chamber of a conventional rocket engine. First, as shown to FIG. 1A, the some groove | channel 111 is formed in the copper inner cylinder 110 of a combustion chamber. Next, as shown in FIG. 1B, the groove 111 is filled with wax 120 (core filling). Thereafter, silver powder 121 is applied to the surfaces of the inner cylinder 110 and the wax 120 (conductive treatment). Subsequently, as shown in FIG. 1C, electroforming is performed on the surfaces of the inner cylinder 110 and the wax 120 that have been subjected to the conductive treatment, thereby forming a copper electroformed layer 112. Thereafter, as shown in FIG. 1D, the wax 120 is removed (core removal), and the silver powder 121 is removed. As described above, a copper combustion chamber having a plurality of cooling channels 114 is manufactured.

  As a related technique, Japanese Patent Application Laid-Open No. 2004-137602 discloses a method of applying a coating material to a substrate. The method includes the steps of providing particles of a metal powder having a size in a range from sufficient to 50 microns to avoid being blown away from the substrate by a bow shock layer; Passing the particles of the metal powder through a spray nozzle at a rate sufficient to deform and over at least one surface of the substrate to form a deposited layer on the at least one surface. It is characterized by that. The method has been implemented on a rocket engine manifold.

  Japanese Patent Application Laid-Open No. 3-23352 discloses a combustion chamber of a rocket engine and a manufacturing method thereof. This method for manufacturing a combustion chamber of a rocket engine has an inner cylinder and an outer cylinder having a concentric cross section, and a groove is provided on at least one of the surfaces of the inner cylinder and the outer cylinder in contact with each other to allow refrigerant to pass through. This is a method for manufacturing a combustion chamber of a rocket engine as a cooling passage. After filling the groove with a heat-resistant soluble core and attaching the inner and outer cylinders and vacuum-sealing the inner and outer cylinders, the inner and outer cylinders are diffusion bonded by hot isostatic pressing to remove the heat-resistant soluble core It is characterized by doing. The method is implemented for a rocket engine combustion chamber.

  JP-A-4-45296 discloses a method for producing a hollow body. This method for producing a hollow body includes a step of filling a hollow portion of a base material forming a core with a sublimable substance in a solid state at room temperature in a variable state, and exposing the filled sublimable substance. Applying a powdered conductive material on the surface to form a conductive layer, forming an electroformed layer on the surface of the conductive layer by electroforming, sublimating material filled from the recess of the base material to the outside A sublimation removing step. This method is carried out for a rocket engine combustion chamber or the like.

Japanese Patent Laid-Open No. 2-197591 discloses a copper electroforming method. This electroforming method includes 130 to 160 g / L of copper sulfate pentahydrate, 130 to 160 g / L of sulfuric acid, 0 to 100 ppm of chlorine ions, and the balance is kept at a bath temperature of 24 to 28 ° C. composed of water. the sauce acidic copper sulfate bath, soaked and electroforming product to be a counter electrode, an electrolyte for a cathode product at a current density of 1~7A / dm ^2, a product at a current density of 1~7A / dm ² Electrodeposition with an anode is performed by reversing the polarity of the electrolysis current at a constant cycle so that the time when the product is used as the cathode is longer than the time when the product is used as the anode. And This method is carried out for a rocket engine combustion chamber or the like.

JP 2004-137602 A Japanese Patent Laid-Open No. 3-23352 JP-A-4-45296 Japanese Patent Laid-Open No. 2-197591

  The hollow structure such as the combustion chamber of the rocket engine shown in the examples of FIGS. 1A to 1D is formed by electroforming. However, the electroforming method has the following problems. (1) Core filling (FIG. 1B), conductive treatment (FIG. 1B), and core removal (FIG. 1D) each require a period of one day or more. (2) The growth rate of the film by electroforming (example: copper) is extremely slow, and it takes several months to reach the target film thickness. (3) When a film (eg, copper) is grown by electroforming, it is difficult to grow the film uniformly, and a non-uniform layer is formed as the film thickness increases. Therefore, a series of processes of stopping the film growth in the middle, cutting and removing the non-uniform layer, and growing the film again by electroforming after predetermined cleaning is required a plurality of times. This increases the number of days for manufacturing.

  Due to the problems described above, the manufacturing flow time of the combustion chamber of the rocket engine, which is a hollow structure, is as long as several months. Here, it is possible to use the electroforming method to shorten the manufacturing flow time and continue the manufacturing while leaving the non-uniform layer, but maintain the high quality required for the film (example: copper). Cannot be applied. A technique capable of forming a hollow structure in as short a time as possible without degrading quality is desired. In particular, in the case of a combustion chamber of a rocket engine, the occurrence of a leak due to an impact such as heat or pressure has a very serious influence on the operation of the rocket. There is a need for a technique that is stronger and more reliable with impact.

  Accordingly, an object of the present invention is to provide a method for manufacturing a hollow structure capable of forming a hollow structure in as short a period as possible without degrading quality.

  Another object of the present invention is to provide a hollow structure or a combustion chamber of a rocket engine that is strong against impact and has higher reliability.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the embodiments for carrying out the invention. These numbers and symbols are added with parentheses in order to clarify the correspondence between the description of the claims and the mode for carrying out the invention. However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

  The method for producing a hollow structure of the present invention comprises a step of forming a groove (11) in a member (10), a step of filling a filler (20) into the groove (11), a filler (20) and a member ( 10) forming the conductive layer (21) on the exposed surface, forming the first layer (12) on the conductive layer (21) by electroforming, and cold spraying the first layer ( 12) forming a second layer (13) on the surface and removing the filler (20) from the groove (11).

  In the present invention, the layer formed so as to cover the member (10) and the filling layer (20) is divided into a first layer (12) and a second layer (13). Manufacture. By using the cold spray method, which has a high film formation speed and is easy to handle, the film formation period can be shortened and the time and cost of film formation can be reduced compared to the case of forming only by electroforming. .

The method for manufacturing a hollow structure further includes a step of heat-treating the second layer (13) in a non-oxidizing atmosphere.
In the present invention, by applying heat treatment as a post-process, the residual stress of the second layer (13) formed mainly by the cold spray method is released, and the mechanical characteristics of the second layer (13) are improved. Can do.

In the method for manufacturing a hollow structure, the step of forming the second layer (13) includes a step of temporarily stopping the formation of the second layer (13) and heat-treating the second layer (13).
In the present invention, by applying heat treatment as an intermediate step, the residual stress of the second layer (13) formed mainly by the cold spray method is released, and the mechanical properties of the second layer (13) are improved. Can do. Further, since the residual stress is released during film formation and film growth continues favorably, it becomes possible to form a relatively thick film.

In the method for manufacturing the hollow structure, the second layer (13) is thicker than the first layer (12).
In the present invention, by using a larger number of cold spray methods that are faster in film formation and easy to handle, the film formation period can be further shortened, and the time and cost of film formation can be further reduced.

In the method for manufacturing a hollow structure, the first layer (12) includes a needle crystal as a main component. The second layer (13) contains granular crystals as a main component.
In the present invention, since two layers having anisotropic crystallinity are laminated, there is an effect that resistance to impact is enhanced.

In the method for manufacturing a hollow structure, the member (10) is an inner cylinder of a combustion chamber of a rocket engine. The first layer (12) and the second layer (13) are outer cylinders of the combustion chamber. The groove (11) is a refrigerant flow path of the combustion chamber.
In the present invention, by using the method for manufacturing the hollow structure in the method for manufacturing the combustion chamber (25) of the rocket engine, the film formation period can be shortened compared with the case of forming only by the electroforming method, and the film formation is performed. Can be saved.

The combustion chamber of the rocket engine of the present invention comprises an inner cylinder (10a) having a concentric cross section and an outer cylinder (15a) having a concentric cross section outside the inner cylinder (10a). To do. The inner cylinder (10a) or the outer cylinder (15a) has a plurality of refrigerant channels (14a) through which refrigerant can flow. The outer cylinder (15a) includes a first layer (12a) provided on the inner cylinder (10a) side and a second layer (13a) provided on the outer side of the first layer (12a). The first layer (12a) and the second layer (13a) have different crystal structures.
In the present invention, since two layers having anisotropic crystallinity having different crystal structures are laminated, there is an effect that resistance to impact is enhanced. It is particularly preferable that a rocket engine combustion chamber (25) used in a severe usage environment in which a high-temperature and high-pressure fluid burns and circulates has such characteristics.

In the combustion chamber of the rocket engine, the first layer (12a) contains needle-like crystals as a main component. The second layer (13a) contains granular crystals as a main component.
In the present invention, since the first layer (12a) is mainly composed of acicular crystals and the second layer (13a) is laminated with two layers having anisotropic crystallinity, it is resistant to impact. It has the effect of being strengthened.

In the combustion chamber of the rocket engine, the second layer (13a) is thicker than the first layer (12a).
In the present invention, when the second layer (13a) is formed by a cold spray method and the first layer (12a) is formed by an electroforming method, the second layer (13a) is made relatively thick and cold. By using more spraying methods, the film formation period can be further shortened, and the time and cost of film formation can be further reduced.

  According to the present invention, it is possible to form a hollow structure in as short a period as possible without degrading quality. In addition, according to the present invention, it is possible to obtain a hollow structure or a rocket engine combustion chamber that is strong against impact and has higher reliability.

FIG. 1A is an explanatory view showing a method of manufacturing a combustion chamber of a conventional rocket engine. FIG. 1B is an explanatory view showing a method of manufacturing a combustion chamber of a conventional rocket engine. FIG. 1C is an explanatory view showing a method of manufacturing a combustion chamber of a conventional rocket engine. FIG. 1D is an explanatory view showing a method for manufacturing a combustion chamber of a conventional rocket engine. FIG. 2A is a perspective view showing the configuration of the hollow structure according to the embodiment of the present invention. 2B is a cross-sectional view schematically showing crystal states of the first layer and the second layer in the hollow structure of FIG. 2A. FIG. 3A is a perspective view showing a combustion chamber of a rocket engine to which a hollow structure according to an embodiment of the present invention is applied. FIG. 3B is an xy plan view showing a combustion chamber of the rocket engine to which the hollow structure according to the embodiment of the present invention is applied. FIG. 3C is a zx sectional view (AA ′ sectional view in FIG. 3B) showing a combustion chamber of a rocket engine to which the hollow structure according to the embodiment of the present invention is applied. FIG. 4A is a flowchart showing a method for manufacturing a hollow structure according to an embodiment of the present invention. FIG. 4B is a flowchart showing a method for manufacturing the hollow structure according to the embodiment of the present invention. FIG. 4C is a flowchart showing a method for manufacturing the hollow structure according to the embodiment of the present invention. FIG. 4D is a flowchart showing a method for manufacturing the hollow structure according to the embodiment of the present invention. FIG. 4E is a flowchart showing a method for manufacturing the hollow structure according to the embodiment of the present invention.

  Hereinafter, a method for manufacturing a combustion chamber and a hollow structure of a rocket engine according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 2A is a perspective view showing the configuration of the hollow structure according to the embodiment of the present invention. The hollow structure 1 has a plurality of cooling channels 14 (a plurality of spaces) through which a fluid (eg, a refrigerant) can pass. If a refrigerant is used as the fluid, the hollow structure 1 can be used as a member that can be cooled. The shape of the hollow structure 1 is not limited to the plate shape as shown in FIG. 2A, and may have other desired shapes (eg, columnar shape, cylindrical shape, planar shape, or a shape in which they are curved). Moreover, the shape of the cooling flow path 14 is not limited to a rectangular cross section as shown in FIG. 2A, and may have another desired shape (eg, a circle, an ellipse, or a polygon). The hollow structure 1 includes a base material portion 10 and a laminated portion 15.

  The base material part 10 is a part which becomes a base material at the time of manufacture. There is no particular limitation on the shape, and FIG. 2A shows a plate-like example. The base material part 10 is provided with at least one cooling channel 14 through which a refrigerant can pass. However, the cooling flow path 14 may be provided in the laminated portion 15. Examples of the material include metal from the viewpoint of cooling efficiency, strength, and elongation. In the case of a combustion chamber of a rocket engine, copper or an alloy containing copper as a main component, which has excellent cooling efficiency, strength, and elongation, is preferable.

  The laminated portion 15 is a portion that is formed on the base material during manufacturing. Although there is no limitation in shape, it becomes an upper layer structure from the manufacturing method mentioned later. FIG. 2A shows a plate-like example. A part of the stacked portion 15 constitutes one side surface of the cooling channel 14. As the material, since the hollow structure 1 is formed integrally with the base material portion 10, the same material as the base material portion 10 is preferable. That is, metal is exemplified from the viewpoint of cooling efficiency, strength, and elongation. In the case of a combustion chamber of a rocket engine, copper or an alloy containing copper as a main component, which has excellent cooling efficiency, strength, and elongation, is preferable.

  The stacked unit 15 includes a first layer 12 and a second layer 13. The first layer 12 is provided in a layered manner on the surface of the base material portion 10. A part thereof constitutes one side surface of the cooling water channel 14. The second layer 13 is provided in layers on the surface of the first layer 12. The first layer 12 and the second layer 13 integrally form the laminated portion 15 but have different crystal structures. Hereinafter, the first layer 12 and the second layer 13 will be further described.

  2B is a cross-sectional view schematically showing crystal states of the first layer and the second layer in the hollow structure of FIG. 2A. The first layer 12 contains acicular crystals as a main component. The acicular crystal extends in the direction from the base material part 10 toward the second layer 13. On the other hand, the second layer 13 contains granular crystals as a main component. The granular crystals are formed so as to be stacked on the first layer 12. However, the main component means the most abundant component. That is, the laminated portion 15 is composed of two layers having different crystal structures. Two layers having different crystal structures can be realized by different manufacturing methods as described later. For example, the above crystal structure can be realized by forming the first layer 12 by electroforming and the second layer 13 by cold spray.

  As described above, since the crystal structures of the first layer 12 and the second layer 13 are different, that is, two layers having anisotropic crystallinity are laminated, there is an effect that resistance to impact is enhanced. That is, even if an impact is fatal to one crystal structure, there may be no problem with the other crystal structure. In such a case, the resistance to impact can be enhanced as compared with the case where the stacked portion 15 is configured by only one of the crystal structures. As a result, for example, the fluid leakage resistance from the base material portion 10 to the laminated portion 15 can be increased. As will be described later, when the first layer 12 is formed by an electroforming method and the second layer 13 is formed by a cold spray method, the manufacturing period can be shortened and the cost and labor can be reduced.

Next, an example in which the hollow structure 1 is applied to a combustion chamber of a rocket engine will be described.
3A is a perspective view showing a combustion chamber of a rocket engine to which a hollow structure according to an embodiment of the present invention is applied, FIG. 3B is an xy plan view thereof, and FIG. 3C is a zx sectional view thereof (cross section AA ′ in FIG. 3B). Figure). The combustion chamber 25 is used for a rocket engine, and a high-temperature and high-pressure fluid burns and circulates during use. There are a plurality of cooling passages 14a (a plurality of spaces) through which the refrigerant passes, and the temperature of the combustion chamber 25 is suppressed to a desired temperature or less by cooling with the refrigerant. The combustion chamber 25 has a cylindrical shape extending in the z direction and constricted near the center. The combustion chamber 25 includes an inner cylinder 10a as a base material portion and an outer cylinder 15a as a laminated portion.

  The inner cylinder 10a is an inner portion of the constricted cylinder. The xy cross section is provided so that the inner surface and the outer surface of the inner cylinder 10a are substantially concentric. The inner cylinder 10a is provided so as to penetrate from the top to the bottom in the z direction along the outer surface thereof, and has a plurality of cooling channels 14a through which the refrigerant flows. The xy cross section of the cooling flow path 14a has a rectangular shape. However, the cooling flow path 14 may be provided in the outer cylinder 15a. The material is preferably copper or an alloy containing copper as a main component in terms of cooling efficiency, strength, and elongation. Note that “substantially” means to allow a difference in the manufacturing error range (the same applies hereinafter).

  The outer cylinder 15a is an outer portion of the constricted cylinder, and is coupled to the outer surface of the inner cylinder 10a. The xy cross section is provided so that the inner surface and the outer surface of the outer cylinder 15a are concentric. The axis of the concentric circle of the outer cylinder 15a substantially coincides with the axis of the concentric circle of the Naito 10a. A part of the outer cylinder 15 a constitutes one side surface of the cooling channel 14. The material is preferably the same material as the inner cylinder 10a because the combustion chamber 25 is formed integrally with the inner cylinder 10a. That is, copper or an alloy containing copper as a main component is preferable in terms of cooling efficiency, strength, and elongation.

  The outer cylinder 15a includes a first layer 12a and a second layer 13a. The first layer 12a is provided in a layered manner on the inner cylinder 10a on the inner cylinder 10a side, and is the same as the first layer 12 in FIG. 2B. That is, the main component is acicular crystals extending in the direction from the inner cylinder 10a toward the second layer 13a. The second layer 13a is provided in a layered manner on the outer surface of the first layer 12a, and is the same as the second layer 13 in FIG. 2B. That is, it includes granular crystals formed so as to be stacked on the first layer 12a as a main component. Thus, the outer cylinder 15a is composed of two layers having different crystal structures. Such a crystal structure is realized, for example, by forming the first layer 12a by an electroforming method and the second layer 13a by a cold spray method, as will be described later.

  Also in this case, since the crystal structures of the first layer 12a and the second layer 13a are different, there is an effect that resistance to impact is enhanced. That is, in the combustion chamber 25, various impacts such as a cryogenic temperature of the supplied liquid fuel, a high temperature and a high pressure due to an explosion are applied. At this time, even if a certain impact is fatal to one crystal structure, there may be no problem with the other crystal structure. In such a case, the resistance to impact can be enhanced as compared with the case where the outer cylinder 15a is constituted by only one of the crystal structures. As a result, for example, even if there is a possibility that the inner cylinder 10a is partially cracked and partly enters the outer cylinder 15a, either the first layer 12a or the second layer 13a can more reliably enter the inner cylinder 10a. Can be blocked. As a result, liquid fuel and combustion gas leaks can be prevented more reliably than ever.

  Further, when the first layer 12a is formed by an electroforming method and the second layer 13a is formed by a cold spray method, it is preferable that the first layer 12a is relatively thin and the second layer 13a is relatively thick. . Thereby, as will be described later, the manufacturing period can be shortened, the manufacturing cost, and the manufacturing effort can be reduced.

Next, the manufacturing method of the hollow structure (FIG. 2A-FIG. 2B) which concerns on embodiment of this invention is demonstrated.
4A to 4E are flowcharts showing a method for manufacturing a hollow structure according to an embodiment of the present invention.

  First, as shown in FIG. 4A, a plurality of grooves 11 are formed on the surface of the base material portion 10. The groove 11 finally becomes the fluid flow path 14. Therefore, the number and shape are determined by the characteristics required for the hollow structure to be manufactured. In the example of this figure, a groove 11 having a rectangular cross section perpendicular to the flow path direction is formed.

  Next, as shown in FIG. 4B, a plurality of grooves 11 is filled with a filler 20 such as wax. The filler 20 is filled so that the exposed surface and the surface (exposed surface) of the base material portion form substantially the same plane. Thereby, the planarity of the 1st layer 12 manufactured on this can be improved. Further, the bonding between the first layer 12 and the base material portion 10 can be strengthened. In addition, the extension and strength of the first layer 12 and the second layer 13 formed thereon can be increased.

  Subsequently, as shown in FIG. 4C, a conductive layer 21 such as silver powder is formed on the exposed surfaces of the filler 20 and the base material portion 10. That is, in the electroforming method, a conductive process is performed on a region where an electroformed film is formed. Then, the first layer 12 is formed as an electroformed film on the surface of the filler 20 and the base material part 10 (on the conductive layer 21) subjected to the conductive treatment by electroforming. At this time, the film thickness of the electroformed film may be a level necessary for stably forming the second layer 13 formed on the first layer 12, and is preferably not increased. This is because forming a thick film by electroforming requires time, labor, and costs as described in the background art section. The film thickness necessary for stably forming the second layer 13 varies depending on the manufacturing conditions of the second layer 13 and is determined by experiments, simulations, and the like. For example, when the copper second layer 13 is formed by a cold spray method under the conditions described later, a copper electroformed film is laminated by 0.1 mm or more as the first layer 12.

Next, as shown to FIG. 4D, the 2nd layer 13 is formed as a cold spray film | membrane on the 1st layer 12 which is an electroforming film | membrane by the cold spray method. For example, a cold spray film of copper is laminated about 10 mm.
As a condition of copper cold spray, for example,
Working gas of cold spray: helium, nitrogen Copper powder supply amount: 50 g / min-200 g / min
Gas pressure: 2MPa-10MPa
Powder and gas temperature in heating furnace before film formation: 200 ° C.-950 ° C.
It is. In addition, when implementing a cold spray method, you may remove the filler 20 previously.
The total thickness of the first layer 12 and the second layer 13 is set to a desired thickness for the stacked portion 15.

  Thereafter, as shown in FIG. 4E, the filler 20 is removed from the plurality of grooves 11 by a method such as melting. Thereby, the hollow structure 1 which has the some cooling flow path 14 enclosed by the laminated part 15 and the base material part 10 can be manufactured.

  As described above, the hollow structure 1 has the laminated portion 15 formed by combining the electroforming method and the cold spray method. Here, the film formation rate of the cold spray method is extremely high as compared with the film formation rate of the electroforming method. Therefore, it is much shorter in the case where the laminated part 15 (example: copper film) is formed by combining the electroforming method and the cold spray method than in the case where the laminated part 15 is formed only by the electroforming method. In the meantime, the film formation can be completed. Thereby, the manufacturing period of the hollow structure 1 can be shortened while maintaining mechanical properties such as strength and elongation of the membrane.

  As a method for shortening the film formation time, it is conceivable to form the film only by the cold spray method without using the electroforming method. However, in the cold spray method, the gas pressure during film formation is very strong. Therefore, there is a problem in that the filler 20 is adversely affected, the cooling water channel 14 cannot be formed so as to cover the groove 11 appropriately, and the shape of the laminated portion 15 is also undulated. However, in this embodiment, since the electroforming method is used as the first layer 12 and the cold spray method is used after the cooling water channel 14 is formed so as to cover the grooves 11 appropriately, the above problem can be solved.

  At this time, as shown in FIG. 2B, the first layer 12 contains acicular crystals as a main component, and the second layer 13 contains granular crystals as a main component. That is, the laminated portion 15 is composed of two layers having different crystal structures. Since the two layers having anisotropic crystallinity are laminated in this manner, there is an effect that resistance to impact is enhanced. As a result, for example, the fluid leakage resistance from the base material portion 10 to the laminated portion 15 can be increased.

In addition, in the electroforming method, the growth may stop due to the relationship between the apparatus and the bath, or the growth may become inappropriate. When the growth becomes inappropriate, the film characteristics are remarkably deteriorated, so it is necessary to stop the growth. In such a case, in order to perform the electroforming again, first, the member is taken out from the bathtub, the member is washed, the surface of the member is thinned, the member is washed, the member is immersed in the bathtub, and finally The procedure is to carry out the electroforming method again. Therefore, it takes much time, cost and time.
However, as shown in the present embodiment, by laminating the first layer by the electroforming method and the second layer by the cold spray method, the labor, cost, and time associated with the growth stoppage that has been required by the electroforming method are greatly increased. Can be reduced. In particular, the effect can be further enhanced by relatively reducing the thickness of the first layer by electroforming, while relatively increasing the thickness of the second layer by the cold spray method. It can be said.
Further, in the case of the cold spray method, even if the film is scratched, the film formation can be resumed immediately after the surface has been thinned, so that there is an effect that the repair can be easily performed.

  Next, the case where the hollow structure 1 is applied to the combustion chamber 25 (FIGS. 3A to 3C) of the rocket engine will be described. The manufacturing method is basically the same as that described with reference to FIGS. 4A to 4E. That is, it is as follows.

  First, the inner cylinder 10a for the rocket engine combustion chamber 25 is prepared. Then, similarly to the case of FIG. 4A, a plurality of grooves are formed on the surface of the inner cylinder 10a. The groove finally becomes the fluid flow path 14a. Therefore, the number and shape are determined by the characteristics required for the combustion chamber 25 to be manufactured.

  Next, as in the case of FIG. 4B, a plurality of grooves are filled with a filler such as wax. The filler is filled so that the exposed surface and the surface (exposed surface) of the inner cylinder 10a are substantially the same plane. Thereby, the planarity of the 1st layer 12a manufactured on this can be improved. Further, the bonding between the first layer 12a and the inner cylinder 10a can be strengthened. In addition, the extension and strength of the first layer 12a and the second layer 13a formed thereon can be increased.

  Subsequently, as in the case of FIG. 4C, a conductive layer such as silver powder is formed on the exposed surface of the filler and the inner cylinder 10a. That is, in the electroforming method, a conductive process is performed on a region where an electroformed film is formed. Then, the first layer 12a is formed as a copper electroformed film on the surface of the filler and the inner cylinder 10a (on the conductive layer) subjected to the conductive treatment by electroforming. For example, a copper electroformed film is laminated by 0.1 mm or more. The reason why the thickness is 0.1 mm or more is to stably form the second layer 13a formed on the first layer 12a.

Next, as in the case of FIG. 4D, the second layer 13a is formed as a cold spray film on the first layer 12a, which is an electroformed film, by a cold spray method. For example, a cold spray film of copper is laminated about 10 mm.
As a condition of copper cold spray, for example,
Working gas of cold spray: helium, nitrogen Copper powder supply amount: 50 g / min-200 g / min
Gas pressure: 2MPa-10MPa
Powder and gas temperature in heating furnace before film formation: 200 ° C.-950 ° C.
It is. In addition, when implementing a cold spray method, you may remove a filler previously.
The total thickness of the first layer 12a and the second layer 13a is set to a desired thickness for the outer cylinder 15a.

  Thereafter, as in the case of FIG. 4E, the filler is removed from the plurality of grooves by a method such as melting. Thereby, the hollow structure 1 which has the some cooling channel 14a enclosed by the outer cylinder 15a and the inner cylinder 10a can be manufactured.

  In the rocket engine combustion chamber 25, as described above, the outer cylinder 15a is formed by combining the electroforming method and the cold spray method. Here, the film formation rate of the cold spray method is extremely high compared to the film formation rate of the electroforming method. Therefore, the case where the outer cylinder 15a (copper film) is formed by combining the electroforming method and the cold spray method is formed in a much shorter time than the case where the outer cylinder is formed only by the electroforming method. The membrane can be terminated. For example, when the outer cylinder is formed only by the electroforming method, a construction period of about two months is required. However, the outer cylinder is formed by combining the electroforming method and the cold spray method. As a result, the construction period can be significantly reduced to about two weeks. That is, the manufacturing period of the combustion chamber 25 of the rocket engine can be shortened while maintaining the mechanical characteristics such as the strength and elongation of the film. In addition, it is possible to reduce manufacturing effort and manufacturing costs.

The modification of the manufacturing method of the hollow structure which concerns on embodiment of this invention mentioned above is demonstrated.
In the present modification, when the second layer 13 (second layer 13a) is formed as a cold spray film on the first layer 12 (first layer 12a) by the cold spray method (FIG. 4D), the film formation is in progress. A heat treatment is performed later. For example, when a copper cold spray film having a thickness of 10 mm ^t is manufactured, when the film thickness is 5 mm ^t , the cold spray method is temporarily stopped and heat treatment is performed. Then, after the film thickness becomes 10 mm ^t and the cold spray method is completed, heat treatment is further performed. In addition, when implementing heat processing, you may remove the filler 20 previously (illustration: just before a cold spray or just before heat processing).

The heat treatment conditions are as follows, for example.
Heat treatment temperature: 200 ° C-950 ° C
Heat treatment time: 1 hour to 10 hours Heat treatment atmosphere: Ar gas atmosphere, vacuum (non-oxidizing atmosphere)
The number of heat treatments during film formation and the above heat treatment conditions are not limited to the above number and conditions, and are set according to the film to be formed, the film formation conditions of the film, and the desired film quality.

  Depending on the film to be formed, the film formation conditions of the film, the desired film quality heat treatment conditions, etc., the heat treatment during film formation can be omitted and only the heat treatment after film formation can be performed. Further, the film may be formed while heating the substrate under appropriate conditions immediately before and during the cold spray.

  By performing the heat treatment, a film having good crystallinity can be stably formed by the effect that the residual stress of the second layer 13 (second layer 13a) generated during the film formation is relaxed during and after the film formation. It can be formed into a film. This makes it possible to form a relatively thick film with improved mechanical properties such as film strength and elongation. In particular, in the case of manufacturing the combustion chamber 25 of the rocket engine, it is possible to obtain performance equivalent to or higher than that manufactured by only the electroforming method.

  The present invention is not limited to the above-described embodiments and modifications, and it is apparent that each embodiment can be appropriately modified or changed within the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Hollow structure 10 Base material part 10a Inner cylinder 11 Groove 12, 12a 1st layer 13, 13a 2nd layer 14, 14a Cooling flow path 15 Lamination | stacking part 15a Outer cylinder 20 Filler 21 Conductive layer 25 Combustion chamber

Claims (4)

Forming a groove in the member;
Filling the groove with a filler;
Forming a conductive layer on the filler and the exposed surface of the member;
Forming a first layer on the conductive layer by electroforming;
Forming a second layer on the first layer by a cold spray method;
Removing the filler from the groove , and
The step of forming the second layer includes
A method for manufacturing a hollow structure , comprising the step of temporarily stopping the formation of the second layer and heat-treating the second layer . In the manufacturing method of the hollow structure of Claim 1,
The step of the heat treatment method for manufacturing a hollow structural member comprising the step of annealing the second layer in a non-oxidizing atmosphere. In the manufacturing method of the hollow structure of Claim 1 or 2 ,
The method for producing a hollow structure, wherein the second layer is thicker than the first layer. In the manufacturing method of the hollow structure according to any one of claims 1 to 3 ,
The member is an inner cylinder of a combustion chamber of a rocket engine,
The first layer and the second layer are outer cylinders of the combustion chamber,
The groove is a refrigerant flow path of the combustion chamber. A method for manufacturing a hollow structure.

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