DIFFUSION BONDING METHOD FOR CLOSED IMPELLER

PURPOSE:To manufacture a closed impeller of high strength and high accuracy by combining a core plate having two- or three-dimensional blades and corresponding side plate, filling granular for preventing the blade deformation in the impeller previously and diffusion bonding under this state. CONSTITUTION:A core plate 12 and a side plate 13 are put together as shown in the figure and diffusion bonded. A knock pin 14 is inserted into pin holes of the core plate 12 and side plate 13 to prevent eccentricity due to pressure from above and below and torsion of a blade 11 due to rotation of the core plate 12 and the side plate 13. Next, to prevent buckling and deformation of the blades and to give sufficient pressing force to joint surface, the granular for preventing the blade deformation 16 of ceramics. etc., is filled whole inside of the impeller and diffusion bonded. Small sized spherical particles of the preventive produce satisfactory result. It is necessary to mix a bonding preventive material such as boron nitride to the preventive 16. In the figure, 1 indicates blade, 2 core plate and 3 side plate respectively.