Patent GB-694701-A (GB)
Title: Improved method of and apparatus for forming vane or blade assemblies
IPC: B21D53/78
Filed: 1951-11-15
Abstract: 694,701. Making turbine blade assemblies. GENERAL MOTORS CORPORATION. Nov. 15, 1951 [Dec. 1, 1950], No. 26729/51. Classes 83 (ii) and 83 (iv). In method of making a blade assembly such as that of an axial flow turbine in which radial vanes are mounted between two arcuate strips, a, number of blades having tongues at their ends are rigidly located in the correct relative positions with the tongues extending through holes in the arcuate strips while the tongues are heated and upset in the holes. In a machine for electrically heating and upsetting the tongues, the blades 37, Figs. 2 and 6, are assembled between a semicircular strip 36 and a pair of semi-circular channel-section strips 38, 39 which are clamped in position between a pair of rings 46,47, and the tongues 41,42 are successively upset at each end of the blades between electrodes 72, 84. The rings 46, 47 have recesses 48, 49 which correctly locate the outer strip 36, the ends of the strips being located by blocks 50, Fig. 1. The rings 46, 47 are clamped together by screws 51 with spacers 53 in the region where the assembly is not located and by screws 52 which are set at an angle to pass between the blades 37 in the region of the assembly. The rings are yieldingly-supported on insulating rollers 64 mounted on brackets 13 attached to a spring- loaded plunger 56 which also carries an insulating block 76 supporting the underside of the strip 36. The blades are located relative to the electrodes 72, 84 by a spring-loaded finger 93 engaging notches 94 in the face of the ring 46. Adjusting screws on arms 92 attached to the brackets 13 engage the faces of the rings 46, 47 and locate the work between the electrodes. Die-holdcrs.-The lower die 72, Fig. , 2, is screwed into a tubular member 66 connected to an electric current supply such as that of a spotwelding machine and has tubes 73, 74 connected at the base for the circulation of a coolant. The member 66 is fixed in block 67 supported on the base of the machine and the assembly is insulated from the bed by plates 68, 70 and a sleeve 69. The upper die 84 is mounted on a cross-head 17 which is reciprocable vertically on guides 18 attached to the machine bed. The cross-head is lowered to engage die 84 with the work by a pneumatic ram 21 and is returned to the raised position after each upsetting operation by a counterweight 23. The die 84 is screwed into a plug 83 on a sleeve 81 welded in a horizontal rod 77 which is slidable in the crosshead 17 for adjustment of the die 84 relative to the lower die 72 and clamped in position by a hand-screw 79. The upper end of the sleeve 81 has pipes 88, 89 connected thereto for the supply of a coolant and the lower end carries a pressurepad 90 loaded by a spring 90b to engage the channels 38, 39. In operation, the lowering of the cross-head 17 brings the upper die 84 into engagement with the work as the pad 90 yields and the rollers 62 and pressure-pad 76 are forced downwards as the plunger 56 yields until the work engages the lower die 72, whereupon the tongues on each end of the blades 37 are upset. The dies may upset a part only of the projecting lug 42, Fig. 12, so that two or more operations are required. To prevent local overheating the operations may be performed consecutively on blades which are spaced apart. In a modification adapted for blades of considerable length as in the initial-stage blade-assembly of a compressor, the major portion of each blade is supported during the upsetting operation to prevent distortion. The blades 137, Fig. 10, are clamped in turn between jaws 212, 213 of a clamp 211 which is adjustably mounted in slides 206 on an insulating block 203 attached to the yielding member 56 so that the clamp moves with the work. The face of the ring 146 is cut away to form an arcuate slot 201 permitting access of the clamp to the blades, a pin 226 on the jaw 212 engaging the ring 146 to locate the jaws in position. The jaws 212, 213 are contoured and interchangeable for different blades and normally held apart by a spring (not shown) and operated to grip the blades by a handle 222.