STALS WHILE THE CRYSTALS ARE BEING PULLED FROM A MELT METHOD AND APPARATUS FOR REDUCING RESIDUAL STRESSES IN CRY

摘要

For holding while machining the end enlargement or enlargements of an elongated otherwise thin deformable workpiece, such as a jet engine blade, the lower block of a two-part hinged fixture has mechanically-adjustable stops which predetermine the location of the front edge and front end of the thin portion of the workpiece and has three upwardly-inclined support pins upon which the lower surface of the thin portion rests. An upper block hinged to the lower block contains three downwardly-inclined correspondingly located clamping pins which bear upon the upper surface of the thin portion immediately above the lower support pins. Each block contains horizontally-movable forward and rearward hold-fast pins for the workpiece end enlargements. A multiplicity of pairs of aligned hydraulically-actuated upper and lower deformation-preventing plungers in both the lower and upper blocks are then set in motion to press simultaneously against the upper and lower surfaces of the thin portion of the workpiece while forward and rearward lower and upper plungers are urged outward against its opposite ends by spring pressure and locked hydraulic pressure fluid created by rotating a screw-threaded piston against hydraulic fluid already present in the upper and lower blocks of the fixture and communicating with the hydraulically-actuated deformation-preventing plungers through upper and lower networks of passageways. The clamping plungers are hydraulically-actuated (FIGS. 1 to 5), or spring-actuated (FIGS. 6 and 7), or screw actuated (FIG. 8).