Patent ID: 11454236

Abstract:
The present invention comprises: a blank forming step in which a casing blank (70) is formed by die-casting, the casing blank (70) having a first cylindrical section (41), a second cylindrical section (42), and an annular section (44) which includes a recess (71) recessed toward one side in an axial direction (O) from a first surface (44a) facing the other side in the axial direction (O); and a cutting step in which the inner peripheral surface (42a) of the second cylindrical section (42) and a second surface (44b) of the annular section (44), the second surface (44b) facing the one side in the axial direction (O), are cut to connect the recess (71) to a compression section containing space (42A) within the second cylindrical section (42), thereby forming a flow passage. In the blank forming step, the casing blank (70) is formed such that a part of a side surface (71a) of the recess (71) is disposed radially outside the inner peripheral surface (42a) of the second cylindrical section (42).