| 摘要 |
627,295. Milling turbine blades. LOMBARD, A. A., and DAZELEY, W. E. April 10, 1946, No. 11069. [Classes 83 (ii) and 83 (iii)] Guide vanes for axialflow turbines or com. pressors are manufactured by a repetition method comprising the steps of first shaping the vane proper to its final configuration, support. ing the vane in a jig which engages it at points or lines defining, in the final assembly of vanes, the theoretical throat area measured between adjacent vanes and machining the locating means on the vane while it is so supported. The points or lines which' define the throat area are the trailing edge 14, Fig. 3, and the nearest point 15 to the trailing edge on the convex side of the adjacent vane. The jig comprises a block 17, Fig. 4, with an opening 18 to accommodate the vane, the trailing edge of which is received in a groove 19 while a pin 20 forms an abutment against which the convex face of the blade is held by a screw 21. The axes of the pin 20 and the screw 21 are relatively displaced in a manner which causes the trailing edge to bear against one side of the groove 19 when the screw is tightened. A pair of jaws 24 adjusted by nuts 25 clamp the vane in position. Lengthwise location of the vane is effected by two adjustable stops 23 engaging the inner faces of the tablets 11 and 12, Fig. 2. The edges 11a and 11b are parallel to one another and to the edges 12a and 12b so that when a vane is mounted in the jig the surfaces 26 and 27 of the latter are parallel with the upper and lower edges of the tablets while the side edges of tablet 11 are parallel with the jig surfaces 28. A base 29 mounted on the table of a horizontal milling-machine carries the jig which is traversed past rotary cutters to machine the edges 11a and 12a and, by inversion of the jig, the edges 11b and 12b. The side edges of tablet 11 are machined by mounting the jig with its side surfaces alternately accommodated in a base of configuration different from that shown. A similarly-constructed jig with its side surfaces 28 parallel with the side edges of the tablet 12 is employed to machine these edges. Two jigs may simultaneously be accommodated in the base. Specification 611,326, [Group XXVI], is referred to.
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