Mixed-flow fan and method of making

Claim 1

A METHOD FOR MAKING A MIXED-FLOW FAN COMPRISING THE STEPS OF: PROVIDING FIRST AND SECOND GROUPS OF SHEET METAL PARTS WHEREIN THE PARTS OF AT LEAST ONE GROUP ARE FORMED FROM COMPOSITE SHEETS EACH COMPRISING A PARENT METAL AND COATINGS THEREON OF A READILY FUSIBLE FILLER MATERIAL, PROVIDING FROM THE PARTS OF ONE OF SAID GROUPS OF PARTS A SHALLOW CONVEX ANNULAR INTAKE SHROUD WITH A PLURALITY OF CIRCUMAXIALLY SPACED ROWS OF SLOTS THEREIN, PROVIDING FROM THE PARTS OF THE OTHER OF SAID GROUPS OF PARTS A PLURALITY OF BLADE BLANKS EACH HAVING OPPOSITE CONCAVE AND CONVEX EDGES EACH OF WHICH EDGES IS PROVIDED WITH ROWS OF TABS, THE TABS ON THE CONCAVE EDGE OF EACH BLADE CONFORMING IN SIZE AND SPACING TO THE SLOTS OF ONE ROW IN THE SHROUD AND THE TABS ON THE CONVEX EDGE OF EACH BLADE HAVING CENTER LINES WHICH EXTEND PARALLEL TO THE SHROUD AXIS, POSITIONING THE SEVERAL BLADE BLANKS ADJACENT THE SHROUD AND INSERTING THE TABS AT SAID CONCAVE EDGES INTO THE CORRESPONDING SHROUD SLOTS, BENDING THE PROJECTING END PORTIONS OF THE INSERTED TABS TO LOCK THE BLADE BLANKS TO THE SHROUD, PROVIDING FROM THE PARTS OF SAID ONE GROUP OF PARTS AN ANNULAR BACKPLATE HAVING A SHALLOW OUTER PORTION WITH A PLURALITY OF CIRCUMAXIALLY SPACED ROWS OF SLOTS THEREIN, THE SAID SLOTS CONFORMING IN SIZE AND SPACING TO THE TABS AT THE CONVEX EDGES OF THE ASSEMBLED BLADE BLANKS, POSITIONING THE BACKPLATE WITH ITS CONCAVE PORTION ADJACENT SAID ASSEMBLED BLADE BLANKS AND EFFECTING RELATIVE AXIAL MOVEMENT BETWEEN SAID BACKPLATE AND THE ASSEMBLED BLADE BLANKS AND SHROUD TO INSERT THE TABS AT THE CONVEX EDGES OF SAID BLANKS INTO CORRESPONDING SLOTS IN THE BACKPLATE, BENDING THE PROJECTING END PORTIONS OF THE LAST SAID INSERTED TABS TO LOCK THE BACKPLATE TO THE BLADE BLANKS, AND HEATING THE ENTIRE ASSEMBLY TO CAUSE SOME OF THE FILLER METAL TO BECOME MOLTEN AND FLOW BY CAPILLARY ACTION SO AS TO CONSITUTE FILLETS AT ALL REENTRANT ANGLES BETWEEN THE FAN PARTS AND SO AS TO FILL ALL CREVICES BETWEEN THE EDGES OF THE BLADES AND THE SHROUD AND BACKPLATE AND ALL CREVICES WITHIN SAID SLOTS AND BETWEEN THE END PORTIONS OF SAID TABS AND THE RESPECTIVELY ADJACENT FACES OF THE SHROUD AND BACKPLATE.