Patent GB-786727-A (GB)
Title: Method and apparatus for making hollow blades for compressors and gas turbines
IPC: B21D53/78
Filed: 1954-05-11
Abstract: 786,727. Making turbine and compressor blades. STALKER, E. A., and CLARKE, D. J. May 11, 1954, No. 13725/54. Classes 83 (2) and 83 (4). Stamping; bending.-A method of fabricating from a metal sheet a fluid deflecting blade includes the steps of bending the sheet simultaneously and in opposite directions about male and female dies to form the blade contours while causing a controlled stretch of the sheet in a chordwise direction between the dies which reduce the incidence of internal strains likely to disturb the formed contours during subsequent heat bonding of the blade parts. Cutting out and shaping.-Sheet metal strip 20 is intermittently fed by profiled coacting rollers 21, 22 over a table 24 into a press having a recess 26 formed by dies 27, 28 contoured to form the rearward lower and upper portions of the blade respectively. A stop 29 positions the sheet in the press. A forming die 30 shaped to form the nose of the blade is carried by an hydraulically-operated plunger 31 and has cutting edges 70, 71 which co-operate with grooves 72, 73 on opposite sides of the recess for shearing the partially formed blank from the strip. The blank and scrap are ejected by an air blast supplied through pipe-lines 74 and 741. The strip is gripped on its forward side by a clamp 35 which has a recess 36 for co-operating with a rib 37 on the die 28, said clamp being operated by an hydraulic plunger 38. A similar second clamp 40 grips the rearward side of the strip and this clamp is arranged on a pivot 44 and is actuated by an arm 45 attached to an hydraulic plunger 46. The pressure exerted by each clamp may be adjusted to allow for localized slipping to prevent distortion or uneven stretching during the forming operation. Hydraulic pressure is supplied by a pump 50 from a reservoir 52. In operation, a reversing valve 60 is operated by the feed roller 21 as the strip abuts the stop 29 and supplies pressure fluid to operate the forming die and forward clamp 35. When the forming die reaches the position shown in Fig. 4, an arm 66 on the die actuates a valve 67 for supplying fluid pressure to actuate the rear clamp 40, thus the strip is clamped on both sides during the remainder of the stroke of the die 30. Finally, the partially formed blank is sheared from the strip by the cutting edges 70, 71. Bending.-The partially-formed blank is provided with a groove milled along the inside of the bend of the leading edge and the blank is then placed in a bender 85 (Figs. 9 and 10) comprising a lower die 86 and a pivoted mandrel 87 hydraulically operated to clamp the blank between the mandrel and the die. The leading edge of the blank is brought to the desired radius by operating a pivoted bender 95 and this brings the trailing edges 75, 76 of the blade together. Finally, the milled groove is filled with solder or brazing material and the blade is placed in a fixture 100 (Fig. 13) to facilitate soldering or brazing the trailing edges 75, 76 together. The trailing edge is now ground to a sharp section and the formed hollow blade mounted on a base.