Multistage Superplastic Forming Apparatus Reducing Cycle Time
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Solution Overview
Problem
Conventional superplastic forming processes require long cycle times, leading to necking and splitting when forming complex components with small radii, and often necessitate additional costly equipment and pre-forming steps to address these issues.
Innovation Solution
A multistage superplastic forming apparatus and method using a single-action forming tool with non-planar upper and lower dies that combines mechanical and gas forming processes, eliminating the need for a blank holder by pre-forming the metal sheet in multiple axes before the final superplastic forming step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional superplastic forming process is used to form complex components with small radii, then the component geometry can be achieved, but the forming cycle time becomes excessively long (up to 30 minutes)
Solution Approach 1:
The forming process is divided into multiple stages: an initial mechanical pre-forming stage followed by a superplastic forming stage. This segmentation allows the most time-critical material redistribution to occur mechanically at high speed, while the slower superplastic process only needs to complete the final complex geometry, thereby reducing total cycle time while maintaining formability.
Solution Approach 2:
The mechanical pre-forming process performs preliminary material redistribution and thinning operations before the superplastic forming stage. By preparing the blank in advance with appropriate material flow patterns, the subsequent superplastic forming requires less time to achieve the final complex geometry, thus reducing overall cycle time.
2Productivity
If the forming cycle time is reduced to increase productivity, then productivity improves, but necking and splitting occur when forming over small radii
Solution Approach 1:
The process separates material redistribution (handled mechanically to prevent necking) from final forming (handled by superplastic process). This allows faster overall cycling while maintaining material integrity during the critical thinning zones through controlled mechanical pre-forming.
Solution Approach 2:
The mechanical pre-forming process performs preliminary material flow control to prevent necking and splitting before the superplastic forming begins. By establishing appropriate material distribution patterns in advance, the subsequent rapid superplastic forming can proceed without causing material failure.
3Reliability
If additional pre-forming steps are added to prevent necking and excessive thinning, then material integrity is maintained, but equipment complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the mechanical pre-forming and superplastic forming operations into a single integrated tool and process sequence. The same tooling performs both functions in sequence, eliminating the need for separate pre-forming equipment and reducing overall system complexity while maintaining material integrity.
Solution Approach 2:
The forming tool is designed to perform multiple functions: mechanical pre-forming and superplastic forming. This multi-functional tooling eliminates the need for dedicated separate equipment for each operation, reducing manufacturing cost and equipment complexity while ensuring material integrity through controlled pre-forming.
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 reduces cycle times, minimizes necking and excessive thinning, simplifies equipment, and decreases overall forming time while maintaining material thickness, thereby improving the efficiency and cost-effectiveness of forming complex geometries.
Implementation Method 1
Superplastic forming (SPF) is a process that takes advantage of a material's superplasticity or ability to undergo large strains under certain elevated temperature conditions
Implementation Method 2
a predefined gas pressure profile is applied to one side of the sheet. The gas pressure forces the sheet into a die cavity
Implementation Method 3
The die and sheet of material, or as sometimes referred to the blank, are heated to a superplastic temperature
Data Source
AI summary
A superplastic forming apparatus and method for forming a sheet of material at an elevated temperatures into a workpiece having a complex geometry. The process takes advantage of a mechanical forming step, which draws material along a major axis to form a first preform. Upon completion of the first mechanical forming step, a second, initial superplastic forming step acts on the first preform to create a second preform having a plurality of channels or grooves located thereon. The grooves or channels function to draw additional material prior to the second or final gas forming step, which completes the forming process by driving the material against a forming surface. Accordingly, the method and apparatus function to reduce forming time and eliminate thinning and wrinkling of the sheet material during the forming process.