GB770120A - Improvements in the manufacture of axial compressor rotors - Google Patents

Abstract

770,120. Making blade discs for axial compressors; turning. GENERAL MOTORS CORPORATION. May 9, 1955, No. 13328/55. Classes 83 (2), 83 (3) and 83 (4). [Also in Group XXVI] Forging. A blade-wheel of an axial compressor is made by forming an over-size wheel rim 16, Fig. 5, having an internal annular groove 24, locating a disc 14 within the rim with the periphery of the disc aligned with the groove and mechanically contracting the rim on to the disc so that the periphery of the latter is gripped within said groove, Fig. 6 (not shown). The disc 14 is made of a low-alloy steel, preferably from cross-rolled stock, and its side walls are machined to conical form. The disc is then heat-treated and finish-ground. The rim 16 is made of stainless steel rolled into a hoop and welded. The groove 24 is machined therein and the rim is heat-treated and ground. The rim 16 is then located in the conical bore of a die 26 and the disc 14 is positioned therein. A collapsible pressure-block 30 is located on the rim and the latter is then forced through the die to contract the rim by a ram 28. The contraction of the rim will produce a predetermined buckling of the disc 14, Fig. 6 (not shown); this buckling will disappear when the rim and disc are removed from the die. The wheel-assembly is then pressed between a pair of dies 36, 38, Fig. 7, whereby the walls of the groove 24 are swaged round the bead 22 at the periphery of the disc. The wheel is then placed on a rotatable indexing-plate and a series of notches 42, Fig. 10, are stamped into the side of the rim by a punch 44, Fig. 8 (not shown). The contracting, swaging and notching operations are preferably performed cold. Spacers 12 rolled from strip-stock and welded into hoops have their edges notched by broaching or shearing to correspond to the notches 42 in wheel rims 16. Dove-tail slots 46, Fig. 11 (not shown), are formed in the periphery of the rim 16 for receiving the blades, subsequent to the notching operation. A compressor rotor assembly, Fig. 1, comprises a series of wheels 14, 16 with their blades 18 mounted on a tiebolt 8 with intermediate spacers 12 between the wheels. The spacers 12 having notched edges engaging in the notches 42 in the wheel rims, enable the drive to be transmitted directly between the rims of adjacent wheels. The blades 18 are retained in their slots in the rims 16 by pins 20. Turning. The conical side-walls of the disc 14, Fig. 5, are formed by flexing a flat disc against a concave block which is then rotated whilst a cutting tool traverses the disc radially of its axis of rotation. Upon the disc being released from the block it will spring back to its original plane, thus revealing a conical surface, and the operation is repeated on the other side.