GB770787A - Process for fabricating hollow blades and blades produced thereby - Google Patents

Abstract

770,787. Making turbine blades; angular bonding; stamping. CLARKE, D. J., and STALKER, E. A. Nov. 8, 1954, No. 32256/54. Classes 83 (2) and 83 (4). A hollow sheet metal blade, e.g. for turbines, compressors and the like is fabricated from a flat metal sheet 15 which is fed by rolls 21, 22 over a table 20 and under cutters 28, 30, 31 on a shaft 26 mounted in a framework 24 and driven by pulley 25. The central cutter forms a groove 32 extending part way through the thickness of the sheet; the side cutters 30, 31 form bevels 33 on the edges of the sheet. Following such operation the sheet is fed forwardly into a press 35 and against a stop member 36. The press embodies a plunger 37 operated by ram 38 under the action of hydraulic or other power, the head 39 also carrying a knife 40 which cuts the sheet to the proper length. The lower die 42 is formed with a face 43 on one portion which corresponds to the contour of the surface 11 of the blade and with a face 44 on a second portion corresponding to the contour of the surface 12 of the blade. An apex 45 centrally of the die is immediately beneath the groove 32. The upper die 46 has a face 47 for engagement with the surface 11, a face 48 for engagement with the surface 12 and a projection 49 to enter the groove 32. The dies may be shaped to form any airfoil contour as desired varying throughout its length and with whatever twist is wanted. The blank is then removed from the press and placed in a folding machine which has a base 50, the upper surface of which is contoured to receive the blade portion 11. An anvil 52 is then swung into position about its pivot 53 and a roller or wrapping bar 55 is swung by handle 57 about its pivot 56 so as to fold the portion 12 about the nose 58 of the anvil, the groove 32 facilitating such folding and avoiding the buckling of the sheet, particularly where a short radius bend is produced. When the fold has been completed, the blade is withdrawn from the folding machine. To complete the fabrication, the two trailing edges are brought together and secured as by spot-welding, silver solder, copper brazing or the like; for this operation, the blade may be mounted in a fixture 60 and a length of solder 61 with suitable flux laid in the groove formed between the bevelled edges 33 which may be flared outwardly slightly to receive the solder. The groove 32 at the leading edge may be similarly brazed or soldered, as by applying a length of solder 64 with flux. Final operations include grinding, deburring and polishing of the trailing edge of the blade to a sharp edge.