Hollow Fan Blade Superplastic Forming Defect Prevention
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Solution Overview
Problem
Current methods for manufacturing hollow fan blades for gas turbine engines face issues with 'sticking' of preforms during superplastic forming, leading to misalignment and defects due to inadequate penetration of argon between core and skin preforms, particularly in the collector zone, which compromises the strength and quality of the blade.
Innovation Solution
The method involves positioning the collector zone on the peripheral edge of the blade and using a tube to supply argon, with the groove and slot located at a distance from the outer boundary of the entrance or exit edge, less than L/3, to facilitate 'unsticking' of the core and skin preforms, thereby ensuring proper alignment and reducing the risk of defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If argon is supplied between core and skin preforms during superplastic forming, then the preforms should separate properly, but argon penetration is inadequate leading to sticking and misalignment
Solution Approach 1:
The groove and slot are pre-positioned at specific locations (distance less than L/3 from the outer boundary) before superplastic forming begins. This preliminary configuration ensures that argon can penetrate effectively at the critical stage when preforms need to separate, preventing sticking and misalignment defects.
Solution Approach 2:
The groove in the skin preform and the slot in the core preform act as intermediaries that facilitate argon penetration between the preforms. These structural features serve as channels that mediate the separation process, allowing gas to reach the interface between core and skin preforms effectively.
2Ease of manufacture
If the tube is positioned closer to the entrance or exit edge, then argon penetration is improved, but the structural integrity may be compromised
Solution Approach 1:
The groove and slot are positioned at a specific location (distance less than L/3 from the outer boundary) rather than uniformly distributed. This local positioning provides concentrated argon penetration effectiveness at the critical region while maintaining overall structural integrity of the blade.
3Reliability
If the groove and slot are positioned at distance less than L/3 from the outer boundary, then preform separation is facilitated, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a quantitative parameter (distance less than L/3 from the outer boundary) for positioning the groove and slot. This parameter change provides a clear manufacturing criterion that balances the need for effective preform separation with achievable manufacturing precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents 'sticking' and misalignment of the core preform, ensuring the formation of stiffening ribs without defects, thus enhancing the structural integrity and manufacturing quality of the hollow fan blade.
Implementation Method 1
carrying out superplastic forming by supplying working fluid into cavities between the skin and core preforms using also at least one tube
Implementation Method 2
diffusion welding the preforms in predetermined areas, also along an entrance edge, an exit edge and a peripheral edge, to produce an integral structural preform
Data Source
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AI summary
The invention relates to metal forming using diffusion welding and superplastic forming. Stop-off material is preliminarily applied in a predetermined screen pattern to areas where surfaces of skin and core preforms come into contact. Skin preforms are provided with a groove, and core preform is provided with a slot for mounting at least one tube. A stack is sealed along edges with the exception of where at least one tube is to be mounted. A tube is mounted to be connected to a collector zone, and oxygen and binder of the stop-off material are removed from cavities in the stack. The stack is fully sealed, heated, and the preforms are diffusion-welded in predetermined areas, also along an entrance edge, an exit edge and a peripheral edge. An integral structural preform is given an airfoil shape and subjected to superplastic forming by supplying working fluid into cavities between the skin and core preforms through also at least one tube. The collector zone is disposed on the side of the stack, which corresponds to the peripheral edge of the blade. For mounting one or more tubes for supplying working fluid at superplastic forming, the groove in the skin preforms and the slot in the core preform are provided at a distance from the outer boundary of the entrance edge or exit edge less than L/3, where L is the length of the blade chord along the peripheral edge. It is thus possible to eliminate risk of defects during blade forming without compromising performance characteristics of the blade and increase in labor intensity of producing same.