Manufacture of a casing with a boss

Patent metadata

Field	Value
Publication number	US-2016369656-A1
Application number	US-201615165743-A
Country	US
Kind code	A1
Filing date	May 26, 2016
Priority date	Jun 19, 2015
Publication date	Dec 22, 2016
Grant date	—

Abstract

The manufacture of a casing which has a boss includes providing two canister portions a first defining an outer wall geometry of a casing including a boss and a second defining an inner wall geometry of the casing. The casing is made using known PHIP methods. The second canister portion includes an array of holes or recesses which, when the canister portions are aligned, face a recess on the first canister portion which defines the boss such that in the nett shape COS an array of pedestals is provided aligned with the boss. The dimension from an exposed end of a pedestal to an exposed surface of the boss is sufficient to receive a bolt thread of the minimum length required to secure a component to the boss.

First claim

1 . A method of manufacture of a casing which has a boss to which one or more components is to be secured by means of a bolt, the method comprising;
determining a minimum length of a bolt required to secure a component to the boss; providing two canister portions a first defining an outer wall geometry of a casing including a boss and a second defining an inner wall geometry of the casing; aligning the first and second canister portions coaxially and introducing the material from which the casing is to be manufactured into a void defined between the canister portions, the material being introduced in a powdered form and under vacuum conditions; sealing the canister and subjecting the canister and powdered material to elevated temperature and pressure sufficient to cause amalgamation of the powdered material into a solid structure; removing the canister portions to provide a nett shape condition of supply (COS) of the casing; and machine finishing one or more elements of the COS including the boss to provide the finished casing; wherein the second canister portion includes an array of holes or recesses which, when the canister portions are aligned, face a recess on the first canister portion which defines the boss such that in the nett shape COS an array of pedestals is provided aligned with the boss and the dimension from an exposed end of a pedestal to an exposed surface of the boss is sufficient to receive a bolt thread of the determined minimum length required to secure a component to the boss.

2 . A method as claimed in claim 1 wherein the canister portions are removed by machining and/or acid etching.

3 . A method as claimed in claim 1 wherein the powder comprises a metal or metal alloy.

4 . A method as claimed in claim 1 wherein the first canister portion defines an annular geometry of the boss.

5 . A method as claimed in claim 4 wherein the first canister further comprises an array of protrusions in the annular geometry defining bolt holes or bolt hole outlines in the boss.

6 . A method as claimed in claim 5 wherein the array of holes or recesses in the second canister portion defines pedestals which are spaced equally around an annulus which mirrors annular geometry of the boss and are arranged in axial alignment with some or all of the protrusions in the annular geometry.

7 . A method as claimed in claim 1 wherein the number of holes or recesses is less than a number of bolt holes provided in the boss.

8 . A method as claimed in claim 1 wherein the second canister portion includes holes and/or recesses of different depths.

9 . A method as claimed in claim 1 wherein the holes or recesses further define a fillet or chamfer from the casing wall.

10 . A method as claimed in claim 1 further comprising drilling and tapping of screw threads through the boss and each pedestal.

11 . A casing made in accordance with the method of claim 1 .

12 . A casing comprising a wall, an annular boss on an outer surface of the wall having an array of bolt holes provided therein and an array of pedestals extending from an inner face of the wall, each pedestal being in axial alignment with a bolt hole.

13 . A casing as claimed in claim 12 manufactured from a high performance metal or alloy suited to use in a gas turbine engine.

14 . A gas turbine engine incorporating the casing of claim 13 .

Assignees

• Rolls Royce Plc

Inventors

• Mulcaire Thomas G
• Garry Ian M

Classifications

• F01D25/24

  Casings (modified for heating or cooling F01D25/14); Casing parts, e.g. diaphragms, casing fastenings (casings for rotary machines or engines in general F16M {; special arrangements in stators dealing with breaking-off of part of rotor F01D21/045}) · CPC title

• F05D2230/22

  by sintering · CPC title

• F05D2300/17

  Alloys · CPC title

• B22F5/10

  of articles with cavities or holes, not otherwise provided for in the preceding subgroups · CPC title

• F05D2220/32

  in gas turbines · CPC title