Hot isostatic pressing tool and a method of manufacturing an article from powder material by hot isostatic pressing

A hot isostatic pressing tool includes a plurality of canister members and the hot isostatic pressing tool including at least one set of adjacent canister members. The plurality of canister members form a chamber to receive a powder material to be hot isostatically pressed. The at least one set of adjacent canister members have interlocking features forming a U-shaped, or a Z-shaped, leakage flow path between the at least one set of adjacent second canister members. The adjacent canister members are welded together to form a joint and the U-shaped, or Z-shaped, leakage flow path reduces the likelihood of failure of the welded joint during hot isostatic pressing.

The present invention relates to a hot isostatic pressing tool and a method of manufacturing an article from powder material by hot isostatic pressing, e.g. HIP.

Hot isostatic pressing is a processing technique in which high isostatic pressure is applied to a powder material contained in a sealed and evacuated canister at a high temperature to produce a substantially 100% dense article. The industry standard is to manufacture the canisters used in the hot isostatic pressing process from mild steel sheet, approximately 3 mm thick. The canister conventionally used comprises a plurality of separate portions which are joined together by welded joints to form the completed canister. During the hot isostatic pressing cycle, the canister collapses as a result of the high gas pressures and high temperatures applied and results in compaction, or consolidation, of the powder material. The collapsing of the canister is sometimes uneven and this may result in distortion of the canister and uneven compaction, or consolidation, of the powder material and ultimately a distorted article at the end of the hot isostatic pressing cycle.

During the hot isostatic pressing cycle there is a problem in that one or more of the welded joints between portions of the canister may fail. A failure of a welded joint may be due to poor welding or a low packing density of the powder within the canister, which induces an increase in tension in the welded joint and leads to its failure. A failure of a welded joint is difficult to assess immediately after the hot isostatic pressing cycle. This is due to the fact that if the welded joint fails during the early part of the hot isostatic pressing cycle any crack generated is subsequently resealed as the hot isostatic pressing cycle continues, because the crack is resealed by a diffusion bonding process. The result of a failure of a welded joint is that the resulting article is not 100% dense. This is established by non destructive examination, NDE, of one of the tubes used for filling the canister e.g. by analysing the argon content within the filling tube, because if the welded joint fails during the hot isostatic pressing cycle the argon, or other inert gas, used is able to enter the canister.

Accordingly the present invention seeks to provide a hot isostatic pressing tool and a method of manufacturing an article from powder material by hot isostatic pressing which reduces, preferably overcomes, the above mentioned problem.

Accordingly the present invention provides a hot isostatic pressing tool comprising a plurality of canister members, the hot isostatic pressing tool comprising at least one set of adjacent canister members, the plurality of canister members forming a chamber to receive a powder material to be hot isostatically pressed, the at least one set of adjacent canister members having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the at least one set of adjacent canister members.

Each set of adjacent canister members may have interlocking features forming a U-shaped or a Z-shaped leakage flow path between each set of adjacent canister members.

The at least one set of adjacent canister members may have interlocking features forming a series of Z-shaped leakage flow paths between the at least one set of adjacent canister members.

The hot isostatic pressing tool may comprise an inner cylindrical canister member, an outer cylindrical canister member, a first end ring and a second end ring, the outer cylindrical canister member being spaced radially outwardly from the inner cylindrical canister member to form the chamber to receive a powder material to be hot isostatically pressed, the first end ring and a first end of the inner cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end ring and the first end of the inner cylindrical canister member, the second end ring and a second end of the inner cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end ring and the second end of the inner cylindrical canister member, the first end ring and a first end of the outer cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end ring and the first end of the outer cylindrical canister member, the second end ring and a second end of the outer cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end ring and the second end of the outer cylindrical canister member.

The interlocking features of the first end ring and a first end of the inner cylindrical canister member may comprise an annular axially extending projection on the inner cylindrical canister member and an annular groove in the first end ring.

The interlocking features may form a series of Z-shaped leakage flow paths between the first end ring and the first end of the inner cylindrical canister member.

The interlocking features of the second end ring and a second end of the inner cylindrical canister member may comprise an annular axially extending projection on the inner cylindrical canister member and an annular groove in the second end ring.

The interlocking features may form a series of Z-shaped leakage flow paths between the second end ring and the second end of the inner cylindrical canister member.

The interlocking features of the first end ring and the first end of the outer cylindrical canister member may comprise an annular axially extending projection on the first end ring and an annular groove in the first end of the outer cylindrical canister member.

The interlocking features may form a U-shaped leakage flow path between the first end ring and the first end of the outer cylindrical canister member.

The interlocking features of the second end ring and the second end of the outer cylindrical canister member may comprise an annular axially extending projection on the second end ring and an annular groove in the second end of the outer cylindrical canister member.

The interlocking features may form a U-shaped leakage flow path between the second end ring and the second end of the outer cylindrical canister member.

The first end of the inner cylindrical canister member may have a radially inwardly extending membrane abutting the first end ring.

The second end of the inner cylindrical canister member may have a radially inwardly extending membrane abutting the second end ring.

The first end of the outer cylindrical canister member may have a radially outwardly and axially extending membrane abutting the annular projection on the first end ring.

The second end of the outer cylindrical canister member may have a radially outwardly and axially extending membrane abutting the annular projection on the second end ring.

The first end ring may be hollow and define a sub chamber interconnected with the chamber to receive the powder material to be hot isostatically pressed.

The second end ring may be hollow and define a sub chamber interconnected with the chamber to receive the powder material to be hot isostatically pressed.

The first end ring may have an annular portion extending in a radially inward direction, the radially inner diameter of the annular portion is less than the radially inner diameter of the inner cylindrical canister member.

The second end ring may have an annular portion extending in a radially inward direction, the radially inner diameter of the annular portion is less than the radially inner diameter of the inner cylindrical canister member.

The hot isostatic pressing tool may comprise a cylindrical canister member, a first end member and a second end member, the cylindrical canister member forming the chamber to receive a powder material to be hot isostatically pressed, the first end member and a first end of the cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end member and the first end of the cylindrical canister member, the second end member and a second end of the cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end member and the second end of the cylindrical canister member.

The present invention also provides a method of manufacturing an article from powder material by hot isostatic pressing, the method comprising the steps of: a) forming a plurality of canister members, b) providing interlocking features on an at least one set of adjacent canister members, the interlocking features forming a U-shaped or a Z-shaped leakage flow path between the at least one set of adjacent canister members, c) sealing the canister members together to form a hot isostatic pressing tool, d) supplying powder material into a chamber defined between the plurality of canister members of the hot isostatic pressing tool, e) evacuating gases from the chamber and then sealing the chamber, f) applying heat and pressure to consolidate the powder material within the chamber of the hot isostatic pressing tool to form a consolidated powder material article and g) removing the hot isostatic pressing tool from the consolidated powder material article.

Step a) may comprise forming an inner cylindrical canister member, forming an outer cylindrical canister member, forming a first end ring, forming a second end ring and arranging the outer cylindrical canister member such that it is spaced radially outwardly from the inner cylindrical canister member to form the chamber, step b) comprises providing the first end ring and a first end of the inner cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end ring and the first end of the inner cylindrical canister member, providing the second end ring and a second end of the inner cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end ring and the second end of the inner cylindrical canister member, providing the first end ring and a first end of the outer cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end ring and the first end of the outer cylindrical canister member and providing the second end ring and a second end of the outer cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end ring and the second end of the outer cylindrical canister member, step c) comprises sealing the first end ring to the first end of the inner cylindrical canister member, sealing the second end ring to the second end of the inner cylindrical canister member, sealing the first end ring to the first end of the outer cylindrical canister member and sealing the second end ring to the second end of the outer cylindrical canister member to form a hot isostatic pressing tool, and step d) comprises supplying powder material into the chamber between the inner cylindrical canister member and the outer cylindrical canister member of the hot isostatic pressing tool.

The consolidated powder material article may be a casing.

The casing may be a gas turbine engine casing.

The casing may be a turbine casing, a compressor casing, a fan casing or a combustion casing.

Step a) may comprise forming a cylindrical canister member, forming a first end member and forming a second end member, step b) comprises providing the first end member and a first end of the cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end member and the first end of the cylindrical canister member, providing the second end member and a second end of the cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end member and the second end of the cylindrical canister member, step c) comprise sealing the first end member to the first end of the cylindrical canister member and sealing the second end member to the second end of the cylindrical canister member to form a hot isostatic pressing tool, and step d) comprises supplying powder material into a chamber defined between the cylindrical canister member, the first end member and the second end member of the hot isostatic pressing tool.

The powder material may comprise a powder metal or a powder alloy.

The powder alloy may comprise a nickel base superalloy, a titanium alloy, a steel alloy.

The method may comprise supplying different powder alloys, or different powder metals, into different regions of the chamber.

A turbofan gas turbine engine10, as shown inFIG. 7, comprises in flow series an intake11, a fan12, an intermediate pressure compressor13, a high pressure compressor14, a combustor15, a high pressure turbine16, an intermediate pressure turbine17, a low pressure turbine18and an exhaust19. The high pressure turbine16is arranged to drive the high pressure compressor14via a first shaft26. The intermediate pressure turbine17is arranged to drive the intermediate pressure compressor14via a second shaft28and the low pressure turbine19is arranged to drive the fan12via a third shaft30. In operation air flows into the intake11and is compressed by the fan12. A first portion of the air flows through, and is compressed by, the intermediate pressure compressor13and the high pressure compressor14and is supplied to the combustor15. Fuel is injected into the combustor15and is burnt in the air to produce hot exhaust gases which flow through, and drive, the high pressure turbine16, the intermediate pressure turbine17and the low pressure turbine18. The hot exhaust gases leaving the low pressure turbine18flow through the exhaust19to provide propulsive thrust. A second portion of the air bypasses the main engine to provide propulsive thrust.

The fan12, the intermediate pressure compressor13, the high pressure compressor14, the combustor15, the high pressure turbine16, the intermediate pressure turbine17and the low pressure turbine18are each enclosed by a respective casing.

A combustor casing32is shown more clearly inFIG. 8and the combustor casing32comprises an annular radially outwardly extending flange38at an upstream end34of the combustor casing32and an annular radially outwardly extending flange40at a downstream end36of the combustor casing32. The flanges38and40enable the combustor casing32to be secured to a casing of the adjacent high pressure compressor14and a casing of the high pressure turbine16. The combustor casing14also has a plurality of circumferentially spaced apertures42, which have associated bosses and threaded blind holes, to allow fuel injectors44to be inserted into the combustion chamber15.

The combustor casing32is manufactured by hot isostatic pressing of a powder material, e.g. a powder metal or powder alloy. The powder alloy may be a nickel-base superalloy.

The combustor casing32is manufactured using a hot isostatic pressing tool50as shown inFIG. 1. The hot isostatic pressing tool50comprises a plurality of canister members52,54,56and58and the hot isostatic pressing tool50comprises at least one set of adjacent canister members. In this case a first end52A of canister member52is adjacent canister member56and a second end52B of canister member52is adjacent canister member58. Similarly a first end54A of canister member54is adjacent canister member56and a second end54B of canister member54is adjacent canister member58. The plurality of canister members52,54,56and58form, or define, a chamber59to receive a powder material61to be hot isostatically pressed. The at least one set of adjacent canister members52,54,56and58having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the at least one set of adjacent second canister members. In this case each set of adjacent canister members has interlocking features forming a U-shaped or a Z-shaped leakage flow path between each set of adjacent canister members. In this case the first end52A of canister member52and the adjacent canister member56have interlocking features60and62respectively and the second end52B of canister member52and the adjacent canister member58have interlocking features64and66respectively. The first end54A of canister member54and the adjacent canister member56have interlocking features68and70respectively and the second end54B of canister member54and the adjacent canister member58have interlocking features72and74respectively.

The hot isostatic pressing tool50actually comprises an inner cylindrical canister member52, an outer cylindrical canister member54, a first end ring56and a second end ring58. The outer cylindrical canister member54is spaced radially outwardly from the inner cylindrical canister member53to form the chamber59to receive the powder material61to be hot isostatically pressed. The first end ring56and the first end52A of the inner cylindrical canister member have interlocking features60and62forming a U-shaped or a Z-shaped leakage flow path between the first end ring56and the first end52A of the inner cylindrical canister member52. Likewise the second end ring58and the second end52B of the inner cylindrical canister member52have interlocking features64,66forming a U-shaped or a Z-shaped leakage flow path between the second end ring58and the second end52B of the inner cylindrical canister member52. The first end ring56and the first end54A of the outer cylindrical canister member54have interlocking features68and70forming a U-shaped or a Z-shaped leakage flow path between the first end ring56and the first end54A of the outer cylindrical canister member54. Likewise the second end ring58and a second end54B of the outer cylindrical canister member54have interlocking features72and74forming a U-shaped or a Z-shaped leakage flow path between the second end ring58and the second end54B of the outer cylindrical canister member54.

The interlocking features of the first end ring56and the first end52A of the inner cylindrical canister member52comprise an annular axially extending projection60on the inner cylindrical canister member52and an annular groove62in the first end ring56. The interlocking features60and62form a series of Z-shaped leakage flow paths between the first end ring56and the first end52A of the inner cylindrical canister member52. The first end52A of the inner cylindrical canister member52has a radially inwardly extending membrane76abutting the first end ring56.

The interlocking features of the second end ring58and the second end52B of the inner cylindrical canister member52comprise an annular axially extending projection64on the inner cylindrical canister member52and an annular groove66in the second end ring58. The interlocking features64and66form a series of Z-shaped leakage flow paths between the second end ring58and the second end52B of the inner cylindrical canister member52. The second end52B of the inner cylindrical canister member52has a radially inwardly extending membrane78abutting the second end ring58.

The interlocking features of the first end ring56and the first end54A of the outer cylindrical canister member54comprise an annular axially extending projection70on the first end ring56and an annular groove68in the first end54A of the outer cylindrical canister member54. The interlocking features form a U-shaped leakage flow path between the first end ring56and the first end54A of the outer cylindrical canister member54. The first end54A of the outer cylindrical canister member54has a radially outwardly and axially extending membrane80abutting the annular projection70on the first end ring56. The membrane80partially defines the annular groove68.

The interlocking features of the second end ring58and the second end54B of the outer cylindrical canister member54comprise an annular axially extending projection74on the second end ring58and an annular groove72in the second end54B of the outer cylindrical canister member54. The interlocking features form a U-shaped leakage flow path between the second end ring58and the second end54B of the outer cylindrical canister member54. The second end54B of the outer cylindrical canister member54has a radially outwardly and axially extending membrane82abutting the annular projection74on the second end ring58. The membrane82partially defines the annular groove72.

The first end ring56is hollow and defines a sub chamber59A interconnected with the chamber59to receive the powder material61to be hot isostatically pressed. The second end ring58is hollow and defines a sub chamber59B interconnected with the chamber59to receive the powder material61to be hot isostatically pressed.

The combustor casing32is manufactured from powder alloy by hot isostatic pressing, The method comprises the steps of: a) forming a plurality of canister members52,54,56and58, b) providing interlocking features60,62,64,66,68,70and72on an at least one set of adjacent canister members52,54,56and58, the interlocking features forming a U-shaped or a Z-shaped leakage flow path between the at least one set of adjacent canister members52,54,56and58, c) sealing the canister members52,54,56and58together to form the hot isostatic pressing tool50, d) supplying powder alloy61into the chamber59,59A and59B defined between the plurality of canister members52,54,56and58of the hot isostatic pressing tool50, e) evacuating gases from the chamber59,59A and59B and then sealing the chamber59,59A and59B, f) applying heat and pressure to consolidate the powder alloy within the chamber59,59A and59B of the hot isostatic pressing tool50to form a consolidated powder alloy combustor casing32and g) removing the hot isostatic pressing tool50from the consolidated powder alloy combustor casing32.

Step a) comprises forming an inner cylindrical canister member52, forming an outer cylindrical canister member54, forming a first end ring56, forming a second end ring56and arranging the outer cylindrical canister member54such that it is spaced radially outwardly from the inner cylindrical canister member52to form the chamber59. Step b) comprises providing the first end ring56and the first end52A of the inner cylindrical canister member52with interlocking features60and62forming a U-shaped or a Z-shaped leakage flow path between the first end ring56and the first end52A of the inner cylindrical canister member52, providing the second end ring58and the second end52B of the inner cylindrical canister member52with interlocking features64and66forming a U-shaped or a Z-shaped leakage flow path between the second end ring58and the second end52A of the inner cylindrical canister member52, providing the first end ring56and the first end54A of the outer cylindrical canister member54with interlocking features68and70forming a U-shaped or a Z-shaped leakage flow path between the first end ring56and the first end54A of the outer cylindrical canister member54and providing the second end ring58and the second end54B of the outer cylindrical canister member54with interlocking features72and74forming a U-shaped or a Z-shaped leakage flow path between the second end ring58and the second end54B of the outer cylindrical canister member54. Step c) comprises sealing84the first end ring56to the first end52A of the inner cylindrical canister member52, sealing86the second end ring58to the second end52B of the inner cylindrical canister member52, sealing88the first end ring56to the first end54A of the outer cylindrical canister member54and sealing90the second end ring58to the second end54B of the outer cylindrical canister member54to form the hot isostatic pressing tool50. Step d) comprises supplying powder alloy61into the chamber59,59A and59B between the inner cylindrical canister member52and the outer cylindrical canister member54of the hot isostatic pressing tool50.

The sealing84,86,88and90of the canister members52,54,56and58comprises welding, e.g. TIG welding or other suitable welding technique. The seal84between the first end ring56and the first end52A of the inner cylindrical canister member52is at the radially inner end of the radially inwardly extending membrane76at the first end52A of the inner cylindrical canister member52. The seal86between the second end ring58and the second end52B of the inner cylindrical canister member52is at the radially inner end of the radially inwardly extending membrane78at the second end52B of the inner cylindrical canister member52.

The seal88between the first end ring56and the first end54A of the outer cylindrical canister member54is at the radially outer and axially upstream end of the radially outwardly and axially extending membrane80at the first end54A of the outer cylindrical canister member54. The seal90between the second end ring58and the second end54B of the outer cylindrical canister member54is at the radially outer and axially downstream end of the radially outwardly and axially extending membrane82at the second end54B of the outer cylindrical canister member54. Each of the seals, welds,84,86,88and90is an annular weld.

The canister members52,54,56and58are formed by machining forged mild steel rings which are then assembled to form the hot isostatic pressing tool50. Prior to the hot isostatic pressing cycle the canister member52,54,56and58are cleaned, assembled and welded together to form a gas tight seal. The assembled canister members52,54,56and58form a plurality of U-shaped, or a Z-shaped, leakage flow paths which provide a longer and more tortuous route for a gas to enter the hot isostatic pressing tool50. The interlocking features60,62,64,66,68,70,72and74provide extra support between the canister members52,54,56and58of the hot isostatic pressing tool50. In addition the membranes76,78,80and82of the hot isostatic pressing tool50are arranged such that the high pressure within the hot isostatic pressing vessel acts on the membranes76,78,80and82of hot isostatic pressing tool50to press them against the adjacent first end ring56and adjacent second ring54to provide an ability to self seal. The interlocking features60,62,64,66,68,70,72and74and the adjacent flat faces reduce the tensioning effect on the fillet welds84,86,88and90. The fillet welds84,86,88and90can be used in the configuration of the present invention because of the association and support of the interlocking features60,62,64,66,68,70,72and74.

Alternative forms of interlocking features may be used such as mortise and tenon, dovetail, dowels, studs, however it is considered that fully annular interlocking features are preferred because these provide maximum support and interlock capability.

The hot isostatic pressing cycle uses temperature of up to 1200° C. and a pressure of up to 150 MPa.

The combustor casing32may be manufactured using a hot isostatic pressing tool150as shown inFIG. 2. The hot isostatic pressing tool150is substantially the same as that shown inFIG. 1and like parts are denoted by like numerals. The hot isostatic pressing tool150differs from that inFIG. 1in that the interlocking features of the first end ring56and the first end54A of the outer cylindrical canister member54comprise an annular groove170in the first end ring56and an axially extending projection168on the first end54A of the outer cylindrical canister member54. The interlocking features form a series of Z-shaped leakage flow paths between the first end ring56and the first end54A of the outer cylindrical canister member54. The first end54A of the outer cylindrical canister member54has a radially outwardly extending membrane180abutting the first end ring56. The interlocking features of the second end ring58and the second end54B of the outer cylindrical canister member54comprise an annular groove174in the second end ring58and an axially extending projection172on the second end54B of the outer cylindrical canister member54. The interlocking features form a series of Z-shaped leakage flow paths between the second end ring58and the second end54B of the outer cylindrical canister member54. The second end54B of the outer cylindrical canister member54has a radially outwardly extending membrane182abutting the second end ring56.

The combustor casing32may be manufactured using a hot isostatic pressing tool250as shown inFIG. 3. The hot isostatic pressing tool250is substantially the same as that shown inFIG. 1and like parts are denoted by like numerals. The hot isostatic pressing tool250differs from that inFIG. 1in that the interlocking features of the first end ring56and the first end52A of the inner cylindrical canister member52comprise an annular groove260on the inner cylindrical canister member52and an annular axially extending projection262on the first end ring56. The interlocking features260and262form a U-shaped leakage flow paths between the first end ring56and the first end52A of the inner cylindrical canister member52. The first end52A of the inner cylindrical canister member52has a radially inwardly and axially extending membrane276abutting the annular projection262on the first second end ring56. The interlocking features of the second end ring58and the second end52B of the inner cylindrical canister member52comprise an annular groove264on the inner cylindrical canister member52and an annular axially extending projection266on the second end ring58. The interlocking features264and266form a U-shaped leakage flow paths between the first end ring56and the second end52B of the inner cylindrical canister member52. The second end52B of the inner cylindrical canister member52has a radially inwardly and axially extending membrane278abutting the annular projection266on the second end ring58.

The combustor casing32may be manufactured using a hot isostatic pressing tool350as shown inFIG. 4. The hot isostatic pressing tool350is substantially the same as that shown inFIG. 1and like parts are denoted by like numerals. The hot isostatic pressing tool350differs from that inFIG. 1in that the interlocking features of the first end ring56and the first end52A of the inner cylindrical canister member52comprise an annular ledge360on the radially inner surface of the inner cylindrical canister member52and an annular axially extending projection362on the first end ring56. The annular axially extending projection362rests on the annular ledge360. The interlocking features360and362form a Z-shaped leakage flow paths between the first end ring56and the first end52A of the inner cylindrical canister member52. The first end52A of the inner cylindrical canister member52has a radially inwardly and axially extending membrane376abutting the annular projection72on the first end ring56. The interlocking features of the second end ring58and the second end52B of the inner cylindrical canister member52comprise an annular ledge364on the radially inner surface of the inner cylindrical canister member52and an annular axially extending projection366on the second end ring58. The annular axially extending projection366rests on the annular ledge364. The interlocking features364and366form a Z-shaped leakage flow paths between the second end ring58and the second end52B of the inner cylindrical canister member52. The second end52B of the inner cylindrical canister member52has a radially inwardly and axially extending membrane378abutting the annular projection366on the second end ring58.

The combustor casing32may be manufactured using a hot isostatic pressing tool450as shown inFIG. 5. The hot isostatic pressing tool450is substantially the same as that shown inFIG. 1and like parts are denoted by like numerals. The interlocking features of the first end ring56and the first end52A of the inner cylindrical canister member52comprise an annular axially extending projection60on the inner cylindrical canister member52and an annular groove62in the first end ring56. The interlocking features60and62form a series of Z-shaped leakage flow paths between the first end ring56and the first end52A of the inner cylindrical canister member52. The first end52A of the inner cylindrical canister member52has a radially inwardly extending membrane76abutting the first end ring56. The interlocking features of the first end ring56and the first end54A of the outer cylindrical canister member54comprise an annular axially extending projection70on the first end ring56and an annular groove68in the first end54A of the outer cylindrical canister member54. The interlocking features form a U-shaped leakage flow path between the first end ring56and the first end54A of the outer cylindrical canister member54. The first end54A of the outer cylindrical canister member54has a radially outwardly and axially extending membrane80abutting the annular projection70on the first end ring56. The membrane80partially defines the annular groove68. The interlocking features of the second end ring58and the second end52B of the inner cylindrical canister member52comprise an annular axially extending projection64on the inner cylindrical canister member52and an annular groove66in the second end ring58. The interlocking features64and66form a series of Z-shaped leakage flow paths between the second end ring58and the second end52B of the inner cylindrical canister member52. The second end52B of the inner cylindrical canister member52has a radially inwardly extending membrane78abutting the second end ring58. The interlocking features of the second end ring58and the second end54B of the outer cylindrical canister member54comprise an annular axially extending projection74on the second end ring58and an annular groove72in the second end54B of the outer cylindrical canister member54. The interlocking features form a U-shaped leakage flow path between the second end ring58and the second end54B of the outer cylindrical canister member54. The second end54B of the outer cylindrical canister member54has a radially outwardly and axially extending membrane82abutting the annular projection72on the second end ring58. The hot isostatic pressing tool450differs from that inFIG. 1in that the first end ring56has an annular portion56A which extends in a radially inward direction to a radially inner diameter much less than the radially inner diameter of the inner cylindrical canister member54and the second end ring58has an annular portion58A which extends in a radially inward direction to a radially inner diameter much less than the radially inner diameter of the inner cylindrical canister member54. The annular portion56A of the first end ring56and the annular portion58A of the second ring58provide a large mass to the end rings56and58to resist radially outward or radially inward movement of the end rings56and58as the powder metal61in the chambers59A and59B is compacted and hence control the radially inner diameter of the hot isostatic pressing tool450.

The combustor casing32may be manufactured using a hot isostatic pressing tool550as shown inFIG. 6. The hot isostatic pressing tool550is substantially the same as that shown inFIG. 5and like parts are denoted by like numerals. The hot isostatic pressing tool550is similar to that inFIG. 5in that the first end ring56has an annular portion56A which extends in a radially inward direction to a radially inner diameter much less than the radially inner diameter of the inner cylindrical canister member54and the second end ring58has an annular portion58A which extends in a radially inward direction to a radially inner diameter much less than the radially inner diameter of the inner cylindrical canister member54. The annular portion56A of the first end ring56and the annular portion58A of the second ring58provide a large mass to the end rings56and58to resist radially outward or radially inward movement of the end rings56and58as the powder metal61in the chamber59A and59B is compacted and hence control the radially inner diameter of the hot isostatic pressing tool450. The hot isostatic pressing tool550differs to that inFIG. 5in that the interlocking features of the first end ring56and the first end52A of the inner cylindrical canister member52comprise an annular ledge560on the radially inner surface of the inner cylindrical canister member52and an annular axially extending projection562on the first end ring56. The annular axially extending projection562rests on the annular ledge560. The interlocking features560and562form a Z-shaped leakage flow paths between the first end ring56and the first end52A of the inner cylindrical canister member52. The first end52A of the inner cylindrical canister member52has a radially inwardly and axially extending membrane576abutting the annular projection562on the first second end ring56. The interlocking features of the second end ring58and the second end52B of the inner cylindrical canister member52comprise an annular ledge564on the radially inner surface of the inner cylindrical canister member52and an annular axially extending projection566on the second end ring58. The annular axially extending projection566rests on the annular ledge564. The interlocking features564and566form a Z-shaped leakage flow paths between the second end ring58and the first end52A of the inner cylindrical canister member52. The second end ring52B of the inner cylindrical canister member52has a radially inwardly and axially extending membrane578abutting the annular projection566on the second end ring58.

The combustor casing32may be manufactured using a hot isostatic pressing tool650as shown inFIG. 9. The hot isostatic pressing tool650is substantially the same as that shown inFIG. 5and like parts are denoted by like numerals. The hot isostatic pressing tool650is similar to that inFIG. 5in that the first end ring56has an annular portion56A which extends in a radially inward direction to a radially inner diameter much less than the radially inner diameter of the inner cylindrical canister member54and the second end ring58has an annular portion58A which extends in a radially inward direction to a radially inner diameter much less than the radially inner diameter of the inner cylindrical canister member54. The annular portion56A of the first end ring56and the annular portion58A of the second ring58provide a large mass to the end rings56and58to resist radially outward or radially inward movement of the end rings56and58as the powder metal61in the chamber59A and59B is compacted and hence control the radially inner diameter of the hot isostatic pressing tool450. The hot isostatic pressing tool550differs to that inFIG. 5in that the interlocking features of the first end ring56and the first end52A of the inner cylindrical canister member52comprise an annular axially extending projection662on the first end ring56and an annular groove660in the inner cylindrical canister member52. The interlocking features660and662form a series of Z-shaped leakage flow paths between the first end ring56and the first end52A of the inner cylindrical canister member52. The first end52A of the inner cylindrical canister member52has a radially inwardly extending membrane76abutting the first end ring56. The interlocking features of the second end ring58and the second end52B of the inner cylindrical canister member52comprise an annular axially extending projection666on the second end ring58and an annular groove664in the inner cylindrical canister member52. The interlocking features664and666form a series of Z-shaped leakage flow paths between the second end ring58and the second end52B of the inner cylindrical canister member52. The second end52B of the inner cylindrical canister member52has a radially inwardly extending membrane78abutting the second end ring58. The interlocking features of the second end ring58and the second end54B of outer cylindrical canister member54comprise an annular axially extending projection674on the second end ring58and an annular groove672in the outer cylindrical canister member54. The end of the membrane82abuts the second end ring58. The interlocking features672and674form a Z-shaped leakage flow path between the second end ring58and the second end54B of the outer cylindrical canister member54.

The combustor casing32may be manufactured using a hot isostatic pressing tool750as shown inFIG. 10. The hot isostatic pressing tool750is similar to that shown inFIG. 5and like parts are denoted by like numerals. The hot isostatic pressing tool750comprises a plurality of canister members752and754and the hot isostatic pressing tool750comprises at least one set of adjacent canister members. In this case a first end752A of canister member752is adjacent a first end754A of canister member754and a second end752B of canister member752is adjacent a second end754B of the canister member754. The plurality of canister members752and754form, or define, a chamber59to receive a powder material61to be hot isostatically pressed. The at least one set of adjacent canister members752and754having interlocking features forming a U-shaped leakage flow path or a Z-shaped leakage flow path between the at least one set of adjacent second canister members. In this case the first end752A of canister member752and the first end754A of the adjacent canister member754have interlocking features760and762respectively and the second end752B of canister member752and the second end754B of the adjacent canister member754have interlocking features764and766respectively. The hot isostatic pressing tool750actually comprises an inner cylindrical canister member752and an outer cylindrical canister member754and the outer cylindrical canister member754is spaced radially outwardly from the inner cylindrical canister member752to form the chamber59to receive the powder material61to be hot isostatically pressed. The interlocking features760and762of the first end752A of the inner cylindrical canister member752and the first end754A of the outer cylindrical canister member754comprise an annular axially extending projection760on the first end752A of the inner cylindrical canister member752and an annular groove762in the first end754A of the outer cylindrical canister member754. The interlocking features760and762form a series of Z-shaped leakage flow paths between the first end752A of the inner cylindrical canister member752and the first end754A of the outer cylindrical canister member754. The interlocking features of the second end752B of the inner cylindrical canister member752and the second end754B of the outer cylindrical canister member754comprise an annular groove764in the second end752B of the inner cylindrical canister member752and an annular axially extending projection766on the second end754B of the outer cylindrical canister member754. The interlocking features764and766form a series of Z-shaped leakage flow paths between the second end752B of the inner cylindrical canister member752and the second end754B of the outer cylindrical canister member754. The interlocking features at the first ends752A and754A of the inner and outer cylindrical canister members752and754respectively may equally well form a simple Z-shaped leakage flow path or a U-shaped leakage flow path and the interlocking features at the second ends752B and754B of the inner and outer cylindrical canister members752and754respectively may equally well form a simple Z-shaped leakage flow path or a U-shaped leakage flow path.

The hot isostatic pressing tool750also comprises a support structure92. The support structure92comprises a first annular support member94, a second annular support member96and an axially extending support member98or a plurality of axially extending support members98. The first annular support member94is located radially within the first annular sub portion59A of the annular chamber59to support the first end752A of the inner cylindrical canister member752. The radially outer surface of the first annular support member94is radially within the radially inner surface of the first end752A of the inner cylindrical canister member752. The second annular support member96is located radially within the second annular sub portion59B of the annular chamber59to support the second end752B of the inner cylindrical canister member752. The radially outer surface of the second annular support member96is radially within the radially inner surface of the second end752B of the inner cylindrical canister member752. The fit between the first and second annular support members94and96and the corresponding first and second end ends752A and752B of the inner cylindrical canister member752is such that at room temperature the support structure92is easily placed coaxially within the first and second ends752A and752B of the inner cylindrical canister member752but at the hot isostatic pressing temperature the relative thermal expansion of the first annular support member94and the first end752A and the relative expansion of the second annular support member96and the second end752B is such that the radially outer surface of the first annular support member94abuts the radially inner surface of the first end752A and the radially outer surface of the second annular support member96abuts the radially inner surface of the second end752B to control the radial positions of the first and second ends752A and752B and hence control the final positions and shape of the flanges38and40in the finished combustor casing32. The first and second annular support members94and96extend in a radially inward direction to a radially inner diameter much less than the radially inner diameter of the inner cylindrical canister member752.

The present invention may also comprise forming a cylindrical canister member, forming a first end member and forming a second end member, step b) comprises providing the first end member and a first end of the cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end member and the first end of the cylindrical canister member, providing the second end member and a second end of the cylindrical canister member with interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end member and the second end of the cylindrical canister member, step c) comprise sealing the first end member to the first end of the cylindrical canister member and sealing the second end member to the second end of the cylindrical canister member to form a hot isostatic pressing tool, and step d) comprises supplying powder material into a chamber defined between the cylindrical canister member, the first end member and the second end member of the hot isostatic pressing tool.

The powder material may comprise a powder metal or a powder alloy. The powder alloy may comprise a nickel base superalloy, a titanium alloy, a steel alloy. The method may comprise supplying different powder alloys, or different powder metals, into different regions of the chamber.

The consolidated powder material article may be a casing. The casing may be a gas turbine engine casing. The casing may be a turbine casing, a compressor casing, a fan casing or a combustion casing.

The hot isostatic pressing tool may alternatively comprise a cylindrical canister member, a first end member and a second end member, the cylindrical canister member forming a chamber to receive a powder material to be hot isostatically pressed, the first end member and a first end of the cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the first end member and the first end of the cylindrical canister member, the second end member and a second end of the cylindrical canister member having interlocking features forming a U-shaped or a Z-shaped leakage flow path between the second end member and the second end of the cylindrical canister member.

The canister members of the hot isostatic pressing tool of the present invention may be formed by machining forged mild steel rings which are then assembled to form the hot isostatic pressing tool. Alternatively the canister members of the hot isostatic pressing tool of the present invention may be formed by casting or may be produced by hot isostatic pressing of powder metal. The canister members may comprise mild steel, preferably mild steel comprising 2 wt % carbon. All the internal surfaces of the canister members which contact powder material, metal or alloy, are machined accurately to enable the production of a precise nett shape article and the interlocking features forming the U-shaped or Z-shaped leakage flow path are machined accurately to ensure integrity during the hot isostatic pressing process. The internal surfaces of the canister members which contact powder material, metal or alloy, may be provided with a barrier layer to inhibit the diffusion of carbides and ferrites from the mild steel canister members into the powder material, metal or alloy e.g. nickel base superalloy, during the hot isostatic pressing procedure. The barrier layer may comprise a nickel alloy, boron nitride or yttria.

In all of the embodiments of the present invention the interlocking features of the adjacent canister members form a U-shaped, a Z-shaped or a series of Z-shaped leakage flow paths. In the case ofFIGS. 1 and 5there are two U-shaped leakage flow paths and two leakage flow paths comprising a series of Z-shaped leakage flow paths. In the case ofFIG. 2there are four leakage flow paths comprising a series of Z-shaped leakage flow paths. In the case ofFIG. 3there are three U-shaped leakage flow paths and one leakage flow path comprising a U-shaped leakage flow path and an additional perpendicular portion. In the case ofFIGS. 4 and 6there are two U-shaped leakage flow paths and two Z-shaped flow paths. In the case ofFIG. 9there is one U-shaped leakage flow path, two leakage flow paths comprising a series of Z-shaped leakage flow paths and one leakage flow path comprising a U-shaped leakage flow path and an additional perpendicular portion. In the case ofFIG. 10there are two leakage flow paths comprising a series of Z-shaped leakage flow paths. The interlocking features of the adjacent canister members can be considered to form a leakage flow path comprising three straight lines interconnected by two right angle bends in the case of a U-shaped leakage flow path and a Z-shaped leakage flow path. The interlocking features of the adjacent canister members can be considered to form a leakage flow path comprising five straight lines interconnected by four right angle bends in the case of a leakage flow path comprising a series of Z-shaped leakage flow paths. The interlocking features of the adjacent canister members can be considered to form a leakage flow path comprising four straight lines and three right angle bends in the case of a leakage flow path comprising a U-shaped leakage flow path and an additional perpendicular portion.

Although the present invention has been specifically described with respect to canisters comprising two, three or four canister members it is equally applicable to a canister comprising two or more canister members.

Although the present invention has been described with reference to an annular chamber having cylindrical, conical or frustoconical inner and outer surfaces, e.g. which are circular in cross-section, the present invention may also be applicable to other annular chambers which have polygonal inner and outer surfaces, e.g. square, pentagonal, hexagonal, octagonal etc in cross-section.

Although the present invention has been described with reference to a hot isostatic pressing tool for producing a gas turbine engine casing it may be suitable for a hot isostatic pressing tool for producing casings for other engines, or for producing other articles or apparatus.