Patent GB-916546-A (GB)
Title: Means and method of manufacturing hollow turbine blades
IPC: B21D53/78
Filed: 1961-11-14
Abstract: 916,546. Making turbine blades; stamping. B.C. JET ENGINES Ltd. Nov. 14, 1961, No. 40627/61. Classes 83 (2) and 83 (4). A method of forming a hollow turbine blade from a length of tubular material consists of supporting the length at each end thereof, providing a gas-tight seal between one end of the length and its supporting means, heating the length to a malleable temperature, clamping the heated length between dies having the required blade shape, simultaneously crimping the length adjacent its unsealed end and applying gas pressure to the interior of the length to expand it into intimate contact with the clamping faces of the die. The blade forming press comprises a base 1 on which a C-shaped frame 2 is mounted which supports a die 4 and a transverse clamping jaw 5. A double-acting hydraulic cylinder 7 supported on the upper part of the frame 2 carries a horizontal plate 9 fitted with an upper die 12 and a clamping jaw 14. Arms 16 extending from the plate 9 are each provided with an adjustable pressure foot 17. Also mounted on the base is a spring- loaded work-holder 20 carrying a slide 28 actuated by a handle 34. The slide carries a circular bearer 40 having a tapered bore 41 for accommodating an outer sleeve 42 provided with a piston 47 and a stop 48 working in a spring-loaded fluid pressure cylinder 50. A tapered face provided at the end of the cylinder 50 accommodates a chuck 54. A tubular fitting 63 is inserted on the sleeve 42 for supplying gas under pressure to the interior of the tubular workpiece. The work-holder is electrically insulated from other parts of the holder and press and electric current is supplied to the holder for heating the workpiece by means of a terminal band 67 attached to the fitting 63. A second work-holder 70 having similar parts to the holder 20 is mounted on the other side of the press. In a modification, the upper and lower dies 95 and 101 are coupled together by a double linkage for unitary movement. Figs. 5 and 6. The work-holder 126 is similar to the holder 20 but the platform 28 is adjustably mounted on a standard 128. The platform 137 of the other work-holder 136 is similarly mounted. Clamping members 142 operated from an hydraulic cylinder 147 are mounted on the platform 137. In operation, a length of tube L is aligned between the holders 20 and 70 using tongs and the handles 34 are operated to move each slide so that one end of the tube is gripped between the tubular fitting 63 and the chuck 54 and the other end of the tube by the chuck 81 of the holder 70. With the workpiece supported in the holders, electric current is supplied to the terminal band 67 to heat the workpiece. The upper die is now lowered and the presser feet 17 engage bearers 40 on the holders 20 and 70 so that when the upper die initially engages the workpiece the latter is not deflected out of alignment with the holders. No deformation takes place until the workpiece is fully supported by the lower die, whereupon the die halves close in unison. The clamping members 5 and 14 form a pressure-tight seal in the workpiece and air or nitrogen under pressure is supplied to the interior of the workpiece to expand it into close conformity with the dies. Surplus metal is removed from the formed workpiece by a cutting operation. An openended aerofoil section so formed is shown in Fig. 7.