Improvements in or relating to blades for use in axial-flow rotary bladed machines such as gas turbines

摘要

801,468. Copy-milling turbine blades. ESCHER WYSS A.G. April 3, 1956 [March 31, 1955], No. 10222/56. Class 83 (3). [Also in Group XXVI] A blade for use in an axial-flow turbine or compressor comprises a profile portion 1 and a thickened root portion 2, the profile form of the profile portion and of the root portion being the same, at least on one side of the blade. The blade may be formed by using profile cutters which are moved outwardly as they approach the root portion. The surfaces of the blade at both sides may be produced simultaneously and the blade may be rotated during machining of the profile portion so as to produce the desired blade twist. The blade may be formed by a series of cutting operations, each forming only a part of the profile; for example the leading and trailing edge portions may be cut simultaneously and finally the centre portion of the profile. A tracer roller corresponding to portions of the profile already cut may be used during machining of subsequent portions of the profile, and to prevent damage by swarf penetrating between the roller and the finished portion of the profile, a rubber covering may be disposed between the cutter and the roller. If only one blade surface is machined at a time, the blade twist may be provided either by movement of the cutter or by turning the blade support. A complementary member 14 is disposed on at least one side of the blade root 13. The engaging faces of the root 13 and member 14 may be of corrugated form as shown in Fig. 7, the corrugated face of the root being produced by undulatory transverse movement of the profile cutter. The flat-faced blank from which the concave surface 10, Fig. 6, is cut may have a width terminating at 11 so that as the cutter 10SP1/SP is withdrawn to produce the thickened root, it leaves the flat surface 11 to engage a flat complementary member 14.