Manufacturing gas flow units

Abstract: Metal is deposited on a passage-forming core (10) by electrocasting to provide a primary metal layer (13). A plurality of longitudinally extending grooves (14) is formed in the primary metal layer and is then filled with a low melting point filler (15). Metal is deposited onto the primary metal layer (13) by electrocasting to form a secondary metal layer (16). Circumferential openings (17,18) are formed in the secondary metal layer adjacent to its ends which communicate with the grooves. The filler in the grooves is then melted and discharged to provide a plurality of coolant passages (19). The openings (17,18) are filled with manifold-forming cores (20,21) made of a filler with a low melting point. Metal is deposited onto the manifold-forming cores by electrocasting to provide tertiary metal layers (22,23). Through-holes (26,27) are formed in the tertiary metal layers. The passage-forming core (10) is dissolved to provide a gas passage (30) and the manifold-forming cores (20,21) are melted and discharged to provide coolant manifolds (28,29).

Description: The present invention relates to a process for manufacturing a gas flow unit. Hollow gas flow units such as rocket nozzles, through which high-temperature gas flows, generally include, means for cooling the unit itself. A known hollow gas flow unit comprising a heat exchanger or rocket nozzle as disclosed in Japanese Utility Model 1st Publication No.61-78263 will be described below with reference to Figure 1 of the accompanying drawings which is a longitudinal sectional view. An inner cylinder 1 defining a gas passage 2 comprises two concentrically laminated, substantially cylindrical electrocast copper layers 3 and 4 with coolant passages 6 being defined by the layer 4 and grooves 5 in the layer 3. A two-part outer cylinder 7 made of a heat-resistant alloy is fitted over the inner cylinder 1 and connected to it by welding or the like. The outer cylinder 7 has, at its opposite ends, manifolds 8 and 9 which are in communication with the passages 6. When high-temperature gas flows through the passage 2 in the heat exchanger, coolant is introduced through one manifold 8 into the passages 6 to cool the inner cylinder 1. The coolant 1 is discharged out of the passages 6 through the other manifold 9 at an increased temperature due to cooling of the cylinder 1 so that excessive temperature rise of the cylinder 1 is prevented. The cylinders 1 and 7 are joined together by welding or the like only at their opposite ends so that the outer cylinder 7 must have a sufficiently thick wall to be able to withstand the pressure of the coolant flowing through the passages 6 as well as most of the pressure of the gas flowing through the passage 2. This results in an increase in the weight of the heat exchanger as a whole. Due to the fact that the cylinders 1 and 7 are joined together by welding or the like, the layers 3 and 4 may separate from each other due to local heating, thereby resulting in leakage of the coolant. The present invention was made in the light of the problems referred to above and has as its object the provision of a process for manufacturing a gas flow unit which contributes to a reduction in weight of the gas flow unit, prevents separation of the electrocast layers and prevents leakage of the coolant. According to the present invention a process for manufacturing a gas flow unit, such as a rocket nozzle or combustion vessel, comprises the steps of providing a metallic passage-forming core, depositing a metal on the passage-forming core by electrocasting to provide a primary metal layer, forming a plurality of longitudinally extending grooves in the primary metal layer, filling the grooves with low-melting-point filler, depositing a metal on the primarly metal layer by electrocasting to provide a secondary metal layer, circumferentially machining the secondary metal layer adjacent to its ends to provide openings communicating with the grooves, heating the filler to melt it, discharging the melted filler through the openings to provide a plurality of coolant passages constituted by the grooves, filling each of the openings with a manifold-forming core made of low-melting-point filler, depositing a metal on the manifold-forming cores and on the secondary metal layer adjacent to the manifold-forming cores by electrocasting to provide tertiary metal layers, forming a hole in each of the tertiary metal layers which leads from the exterior to the associated manifold-forming core, removing the passage-forming core to provide a gas passage inside the primary metal layer, heating the manifold-forming cores to melt them, and discharging the melted manifold-forming cores through the holes to provide coolant manifolds. In the preferred embodiment the passage forming core is removed from within the primary metal layer by dissolving it. In the process of the present invention a gas flow unit comprising a gas passage, coolant passages, manifolds and flanges is manufactured integrally by electrocasting primary, secondary and tertiary metal layers whereby the resulting unit has a lightweight construction. Due to the integral construction of the unit, there is no need to connect manifolds and flanges by welding. Consequently, no separation of metal layers occurs to the thermal effects and there is also no risk of leakage of coolant. Further features and details of the invention will be apparent from the following description of one specific embodiment which is given by way of example with reference to Figures 2 to 13 of the accompanying drawings, in which:- Figure 2 is a sectional view of a passage-forming dissoluble core which is used in the manufacture of a combustion vessel having a gas passage of rectangular cross-section according to the present invention; Figure 3 is a sectional view showing the primary metal layer formed by electrocasting on the passage-forming dissoluble core of Figure 2; Figure 4 is a sectional view similar to Figure 3 showing grooves formed in the surface of the primary metal layer; Figure 5 is a sectional view showing the secondary metal layer formed by electrocasting on the primary metal layer seen in Figure 4; Figure 6 is a sectional view similar to Figure 5 showing the secondary metal layer formed with openings and coolant passages; Figure 7 is a sectional view similar to Figure 6 showing manifold-forming fusible cores fitted into the openings of Figure 6 and tertiary metal layers formed by electrocasting onto the manifold-forming fusible cores and on the secondary metal layer; Figure 8 is a sectional view showing holes formed in the tertiary metal layers leading from the exterior to the manifold-forming fusible cores; Figure 9 is a sectional view similar to Figure 8 after the ends of the primary metal layer and passage-forming dissoluble core have been cut off; Figure 10 is a sectional view showing coolant manifolds inside the tertiary metal layers and a gas passage inside the primary metal layer; Figure 11 is a sectional view along the line XI-XI in Figure 4; Figure 12 is a sectional view on the line XII-XII in Figure 6; and Figure 13 is a sectional view on the line XIII-XIII in Figure 10. Figures 2 to 13 represent sequential steps in manufacturing a combustion vessel having a gas passage of rectangular cross-section which constitutes a gas flow unit in accordance with the present invention. A passage-forming dissoluble core 10 having a longitudinal through hole or holes 11 for promoting metal fusion is fabricated from a metal having a low melting point, such as an aluminium alloy. The core 10 of rectangular cross-section is necked or constricted at the central portion along its length (See Fig. 2). Pre-treatment, such as grinding, polishing and/or degreasing, is carried out on the core 10. Masks 12 are fitted over the opposite ends of the core 10. Then, the core 10 is placed in an electrocasting vessel and a layer of metal, such as copper, is attached to the core 10 by electrocasting to provide a primary metal layer 13 (See Figure 3). After the primary metal layer 13 has been formed, the core 10 is taken out of the electrocasting vessel, the masks 12 are removed and the layer 13 is washed and heat treated. After the surface of the layer 13 is smoothed by machining or the like, a plurality of longitudinally extending grooves 14 are formed in the layer 13 by electric discharge machining or the like (See Figures 4 and 11). The layer 13 is then pre-treated, e.g. by grinding, polishing and/or degreasing, and masks 12 are fitted over the opposite ends of the core 10. Each of the grooves 14 is filled with low-melting-point filler 15, such as wax, with a melting point lower than the boiling point of water. After the surface of the filler is treated to improve its electrical conductivity, the core 10 is placed in the electrocasting vessel and metal, such as copper, is deposited on the layer 13 and filler 15 to provide a secondary metal layer 16 (See Figure 5). After the layer 16 has been formed, the core 10 is taken out of the electrocasting vessel and after removal of the masks 12 it is washed and heat treated. The surface of the layer 16 is then smoothed by machining or the like. The layer 16 is also circumferentially machined at positions adjacent to its ends to provide openings 17 and 18 which communicate with the grooves 14. The layer 16 is heated to melt the filler 15 and the melted filler 15 is discharged through the openings 17 and 18 to provide a plurality of coolant passages 19 defined by the grooves 14 and the layer 16 (See Figures 6 and 12). The layers 13 and 16 are pre-treated, e.g. by grinding, polishing and/or degreasing. The openings 17 and 18 are filled with manifold-forming cores 20 and 21 made of low melting point filler, such as wax with a melting point less than the boiling point of water, and masks 12 are fitted over the ends of the core 10 and layer 13 and also over the layer 16 except for those regions around the cores 20 and 21. The core 10 is then placed in the electrocasting vessel and a metal, such as copper, is deposited by electrocasting on the cores 20 and 21 and on the surface of the layers 13 and 16 adjacent to the cores 20 and 21, thereby providing tertiary metal layers 22 and 23 (See Figure 7). After the layers 22 and 23 have been formed, the core 10 is taken out of the electrocasting vessel and after removal of the masks 12 it is washed and heat treated. The tertiary metal layers 22 and 23 are machined or the like to form flanges 24 and 25. Through holes 26 and 27 are formed in the layers 22 and 23 which lead from the exterior to the cores 20 and 21 (See Figure 8). There may be only a single hole 26 and a single hole 27 but it is preferred that there are two or even three of each type of hole to make the coolant flow more uniform. The end portions of the layer 13 beyond the flanges 24 and 25 are cut off by machining or the like (See Figure 9). The core 10 is then dissolved by, for example, an aqueous solution of sodium hydroxide. The dissolved core 10 is discharged out of the layer 13 to leave a gas passage 30 inside the layer 13. The layers 22 and 23 are heated to melt the cores 20 and 21. The melted cores 20 and 21 are discharged through the holes 26 and 27 to leave coolant manifolds 28 and 29 constituted by the openings 17 and 18 (See Figures 10 and 13). When high temperature gas is to pass through the passage 30 in the combustion vessl manufactured as described above, coolant is introduced through the hole 26 into the manifold 28 and thence into the passages 19 so that excessive temperature increase of the layers 13 and 16 is prevented. The coolant passes at an increased temperature into the manifold 29 and is discharged through the hole 27 to the exterior. The combustion unit of Figure 10 is integrally manufactured by the formation of the primary, secondary and tertiary metal layers 13, 16, 22 and 23 by electrocasting so that it is lightweight in comparison with conventional combustion vessels. Because the whole combustion vessel including the manifolds 28 and 29 and the flanges 24 and 25 are integrally manufactured by electrocasting, there is no need to join the manifolds 28 and 29 and the flanges 24 and 25 by welding. As a result, no separation of the metal layers 13 and 16 due to thermal effects as well as no leakage of the coolant will occur. The shape of the gas passage 30 may be freely varied by changing the shape of the core 10 when manufacturing a combustion vessel by the above process. It will be understood that the process for manufacturing a gas flow unit according to the present invention is not limited to the embodiment described above and that various changes and modifications may be made with departing from the scope of the present invention. For example, the primary, secondary and tertiary metal layers may be formed by electrocasting a metal other than copper or different metals may be used for each of the metal layers. Furthermore, the low-melting point filler used in the grooves 14 and for the cores 20 and 21 may be made of metal and the passage forming core 10 may be removed by melting rather than dissolving it.

Claims: A process for manufacturing a gas flow unit, such as a rocket nozzle or combustion vessel, comprising the steps of providing a metallic passage-forming core (10), depositing a metal on the passage-forming core (10) by electrocasting to provide a primary metal layer (13), forming a plurality of longitudinally extending grooves (14) in the primary metal layer (13), filling the grooves (14) with low-melting-point filler (15), depositing a metal on the primary metal layer (13) by electrocasting to provide a secondary metal layer (16), circumferentially machining the secondary metal layer (16) adjacent to its ends to provide openings (17,18) communicating with the grooves (14), heating the filler (15) to melt it, discharging the melted filler (15) through the openings (17,18) to provide a plurality of coolant passages (19) constituted by the grooves (14), filling each of the openings (17,18) with a manifold-forming core (20,21) made of low-melting-point filler, depositing a metal on the manifold-forming cores (20,21) and on the secondary metal layer (16) adjacent to the manifold-forming cores (20,21) by electrocasting to provide tertiary metal layers (22,23), forming a hole (26,27) in each of the tertiary metal layers (22,23) which leads from the exterior to the associated manifold-forming core (20,21), removing the passage-forming core (10) to provide a gas passage (30) inside the primary metal layer (13), heating the manifold-forming cores (20,21) to melt them, and discharging the melted manifold-forming cores through the holes (26,27) to provide coolant manifolds (28,29). A process as claimed in claim 1 in which the passage forming core (10) is removed by dissolving it. A process as claimed in claim 1 in which the passage forming core (10) is formed of metal having a low melting point, e.g. of about 200°C and is removed by melting it.

Inventors: HIGASHINO KAZUYUKI, IMAI KIWAMU, MATSUSHIMA YUKINORI, OMORI YASUNORI, SANO KAZUO, SAYAMA MASAMI, TANI HOSHIRO, HIGASHINO, KAZUYUKI, IMAI, KIWAMU, MATSUSHIMA, YUKINORI, OMORI, YASUNORI, SANO, KAZUO, SAYAMA, MASAMI, TANI, HOSHIRO, IMAI, KIWAMU, (102) MAISON SHIBAKUBO, NO. 14-35, SAYAMA, MASAMI, (107-4-402) TSUBAKIMINE NEW TOWN
Applicants: ISHIKAWAJIMA HARIMA HEAVY IND, MISHIMA KOSAN KABUSHIKI KAISHA, ISHIKAWAJIMA-HARIMA JUKOGYO KABUSHIKI KAISHA
Application year: 1992
Main classification: C25D1
IPC codes: C25D1