Patent ID: 6053024
Filing Date: 2000-04-25
Classification: B21D,F16H

Abstract:
A method of forming a turbine shell by bending, comprising the steps of:providing a sheet material with a predetermined uniform thickness;cutting said sheet material in a predetermined configuration such that said sheet material has a circular form with a central hole on a center thereof and a plurality of circumferentially spaced holes located adjacent to said central hole;performing a preliminary pressing operation on said sheet material to provide a preliminary form of said turbine shell by use of a first pair of dies, the first pair of dies shaped to form a preliminary blade-carrying portion, a preliminary flat portion, and a preliminary corner portion, said preliminary pressing operation applying a compressive force to said sheet material to form said preliminary form having a preliminary corner portion with a decreased thickness, a preliminary blade-carrying portion, and a preliminary flat portion; andperforming a finish pressing operation on said sheet material to provide said turbine shell with a finished form by use of a second pair of dies, the second pair of dies shaped to form a finished blade-carrying portion, a finished flat portion, and a finished corner portion, said finish pressing operation generating a compressive force in said preliminary corner portion in a direction substantially transverse to a direction of said decreased thickness of said preliminary corner portion by restricting movement of said preliminary flat portion and said preliminary blade-carrying portion with said preliminary corner portion therebetween to form a finished form having a blade-carrying portion, a finish flat portion and a finished corner portion, said finished blade-carrying portion having the same thickness and shape as said preliminary blade-carrying portion, said finished flat portion having the same thickness and shape as said preliminary flat portion, said preliminary corner portion projecting beyond said finished corner portion, said finished corner portion having a finished thickness that is increased in thickness relative to said decreased thickness of said preliminary corner portion such that the thickness of said finished corner portion is decreased by 10% or less relative to the predetermined thickness of said sheet material.