| 摘要 |
A method of manufacturing a metal housing (14) includes providing a first passage (10) through the metal housing (14) and providing a second passage (12) through the metal housing (14), wherein the second passage (12) includes a region of intersection (20) which intersects the first passage (10) to define an opening (22, 122, 222) into the first passage (10). The method further includes subjecting the metal housing (14) to a heat treatment process to carburise an internal surface of the first and/or second passage (10, 12) and, subsequent to the carburisation process, applying a hard stage electrochemical machining process to the carburised internal surface of the first and/or second passage (10, 12) to improve surface finish. Another aspect of the invention includes providing a second passage (12) through the metal housing (14) by means of a tool (46), such as an electrochemical machining electrode, having an active region without rotational symmetry about its axis (Y-Y). The active region is shaped to provide the region of intersection (20) with a generally conical taper (29, 31) to the opening (22; 122; 222).
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