Classification gage for turbine vanes

Claim 1

Gage means for observing class in a turbine vane which comprises an airfoil blade having a span extending longitudinally between fixed outer and inner buttresses, said blade having a convex surface referenced to an airfoil gage line extending between said buttresses and having a concave surface referenced at its trailing edge to a trailing-edge gage line, one of said buttresses including a wall extending generally transverely of said blade at juncture thereto and having opposed substantially flat elongated abutment surfaces for nested abutment with corresponding adjacent surfaces of the next adjacent vane when in shrouded assembly about a turbine axis; said gage means comprising a rigid frame, trailing-edge support means carried by said frame at longitudinally spaced locations for stabilized support of the trailing edge of the vane, said support means at each of said locations comprising first and second elongated abutments that are generally transversely oriented with respect to each other and with respect to the axis of longitudinal spacing, the first abutments at said locations being substantially parallel to each other and the second abutments at said locations being substantially parallel to each other, whereby said trailing-edge support means affords an applied blade a limited region of angularly rockable displacement of the blade about a rocking axis substantially coincident with the trailingedge gage line; a fixed stop longitudinally offset in a first direction from said support means and projecting from a part of said frame to intercept part of the inner wall of one buttress and thus determine a lateral location for rockable trailing-edge support; second stop means including blade-contacting means movably carried by said frame and offset from the rocking axis for contact with the convex blade surface, said second stop means also including a buttress contact movably mounted on said frame for engaging the inner wall of the other buttress, said bladecontacting means and said movable buttress contact being mechanically coupled for cooperative displacement so that the displaced position of one determines the displaced position of the other, and said offset being such as to position said bladecontacting means for localized contact with the convex blade surface substantially at the airfoil gage line thereof; and means for measuring with respect to a predetermined reference on said frame the angular orientation of one of the abutment surfaces of one of the buttresses, when the blade is limited in said rocking displacement, upon contact by the movable buttress contact with the inner wall of the other buttress; whereby the measured angle may be substantially indicative of class of vanes successively observed by aid gage means.