Patent GB-802476-A (GB)
Title: Improvements in or relating to rotors of axial-flow fluid machines for example compressors and turbines
Inventor: HAWORTH LIONEL
IPC: F01D5/30
Filed: 1955-09-29
Abstract: 802,476. Turbine and compressor bladed rotors. ROLLS-ROYCE, Ltd. Sept. 4, 1956 [Sept. 29, 1955], No. 27796/55. Class 110 (3). In an axial-flow turbine or compressor, rotor blades 12 are mounted by their roots 14 in axial slots formed in the rim 11 of the rotor disc 10 and means are provided to retain the root portions against displacement in the slots. The blades shown are formed with blade platforms 13, with fir-tree root portions 14 and with narrow stem portions 16 between the platform and root portions. Each blade platform is provided with an inwardly-facing groove 20, the grooves of the blade assembly together forming a continuous annular groove. The face of the rotor disc corresponding to that on which the grooves 20 are disposed is formed with an inwardly-facing circumferential groove 21, also with an interrupted circumferential land 11a and with spaced projections 22, 23. A flat annular plate 25 is provided to prevent displacement of the blades to the right (as seen in Fig. 4), the plate 25 having a gap 26 at one point so that it may be contracted in diameter, and when so contracted it is placed adjacent the side of the rotor disc and blade root portions. When allowed to expand, the rim portion 28 of the plate 25 engages the circumferential groove 20 formed on the under-surfaces of the blade platforms 13 and the flange 30 at the inner periphery of the plate 25 engages the circumferential groove 21 in the rotor disc. The plate 25 is also formed with inwardly-extending lugs 31, 32 which correspond to the projections 22, 23 on the rotor disc, and upon assembly the plate is so positioned that the lugs 31, 32 are in the positions shown at 31a, 32a in Fig. 2. After the plate 25 has been allowed to expand to engage the grooves 20, 21, it is rotated so that the lugs 31, 32 are radially aligned with the projections 22, 23. A block 34 is then entered between the projections 32 and lugs 23, the block having a flange to engage in the groove 21. A pin 35 is engaged in holes in the block 34 and lugs 32, the ends of the pin being bent over to prevent its disengagement. The gap 26 in the plate 25 is arranged to be disposed adjacent one of the blade stems 16 so as to prevent leakage between adjacent blade stems. The land 11a is provided so that the edge of the plate 25 and the flange 30 are sprung into good sealing contact with the grooves 20 on the blade platforms and with the side of the groove 21 respectively. In a second embodiment, Fig. 7, the plate 25 does not have to be displaced circumferentially upon assembly, the lugs 131 on the plate 25 being cut back as indicated at 131a so that the lugs 131 may be passed over the projections 22 when the plate is contracted. Filler pieces 134 are inserted into the spaces between the projections 22 and the lugs 131 after the plate has been allowed to expand, and tabs 134a on the filler pieces are bent up so as to lie on either side of each lug 131. A lug is disposed on the plate 25 opposite the gap 26, the lug being positioned between a pair of projections formed on the rotor disc so as to prevent rotation of the plate 25 in operation.