Method of forming a hollow blade
AssigneeUnited Technologies Corporation
InventorsDavid Porter, James R. Dillner, Peter E. Leibfried, William R. Reimels, J. George Asfalg
Life of this patent
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Abstract
An untwisted hollow blade with internal reinforcing ribs is formed by diffusion bonding two halves. A predominate portion of the blade twist is accomplished by gravity creep deforming against a supporting die, aided by applying twisting moments at the ends. The blade is free to move axially at one end. Simultaneous heat soak for solution heat treatment minimizes overall grain growth. Later, hot forming between heated dies is supplemented with internal blade pressure after die closing. Metal flow is more easily predictable whereby finite element analysis may establish the proper starting form.
Claims35
A method of forming a hollow internally reinforced titanium alloy blade, having a longitudinal axis, with predictable metal flow comprising:
- forming a hollow untwisted blade of lenticular cross section and having axially extending ribs connecting opposite walls of the blade;
- creep deforming said untwisted blade without compressive loading on said untwisted blade other than at the very ends, and without axial restraint of said untwisted blade other than at one end, to a twisted blade by,
- placing said hollow untwisted blade on a shaped die half,
- heating said hollow untwisted blade to a temperature level at which creep takes place with gravity force deforming said untwisted blade into contact with said die, and
- simultaneously applying twisting moments at each end of said hollow untwisted blade;
- final hot forming said twisted blade to a final form blade by:
- placing said twisted blade between a pair of final form dies,
- heating said twisted blade to at least the temperature at which creep takes place, but less than the phase transformation temperature,
- closing said final form dies, and
- applying an internal pressure with said final form dies closed;
- the twisted blade formed in the creep deforming step having at least 80 percent of the twist of the final form blade;
- cooling said final form blade;
- and
- blending the leading and trailing edges of said final form blade.
A method of forming a hollow internally reinforced titanium alloy blade, having a longitudinal axis with predictable metal flow comprising:
- forming a hollow untwisted blade of lenticular cross section and having axially extending ribs of hourglass cross section connecting opposite walls of the untwisted blade;
- machining the leading edge and trailing edge of said untwisted blade;
- creep deforming said untwisted blade without compressive loading other than at the very ends, and without axial restraint other than at one end, to a twisted blade by,
- placing said untwisted blade on a shaped die half,
- heating said untwisted blade to a temperature level at which creep takes place with gravity force deforming said untwisted blade into contact with said die, and
- simultaneously applying twisting moments at each end of said untwisted blade;
- solution heat treating said untwisted blade simultaneously with creep deforming said untwisted blade by holding said untwisted blade at the creep forming temperature for one hour and thereafter quenching said twisted blade;
- final hot forming said twisted blade to a final form blade by,
- placing said twisted blade between a pair of final form dies,
- heating said twisted blade to at least the temperature at which creep takes place, but less than the phase transformation temperature,
- closing said final form dies, and
- applying an internal pressure with said final form dies closed;
- the step of creep deforming said untwisted blade comprising deforming said untwisted blade to a twisted blade having at least 80 percent of the twist of the final form blade;
- cooling said final form blade;
- and
- blending the leading and trailing edges of said final form blade.
A method of twisting a hollow elongated titanium alloy member, having a longitudinal axis, comprising:
- gravity creep deforming said untwisted member without compressive loading of said member other than at the very ends, and without axial restraint of said member other than at one end, to a twisted member by,
- placing said untwisted member on a shaped die half,
- heating said untwisted member to a temperature level at which creep takes place with gravity force deforming said untwisted member into contact with said die half, and
- simultaneously applying twisting moments at each end of said untwisted member.
Dependencies are inferred from the claim text.