Workpiece Surface Imprinting for Higher Fatigue Strength
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Solution Overview
Problem
Conventional methods for improving fatigue strength of workpieces, such as shot peening and laser peening, require additional process steps and equipment, increasing manufacturing costs and potentially disrupting production workflows, while also being inefficient in enhancing fatigue life under high stress levels.
Innovation Solution
A method involving a punch and die assembly that imprints surface features through plastic deformation, inducing compressive residual stresses at the sub-surface level of the workpiece, thereby enhancing its fatigue strength without the need for specialized equipment or additional manufacturing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If shot peening or laser peening processes are used to improve fatigue strength, then the fatigue strength of the workpiece increases, but the manufacturing cost increases due to additional process steps and specialized equipment
Solution Approach 1:
The patent combines the fatigue strength improvement process with the existing forming operation by integrating the peening function into the punch and die assembly. This merging eliminates the need for separate peening equipment and process steps, thereby reducing device complexity while maintaining fatigue strength improvement.
Solution Approach 2:
The punch and die assembly is designed to perform multiple functions: both forming the workpiece and inducing compressive residual stresses through surface feature imprinting. This multi-functionality eliminates the need for specialized peening equipment, reducing manufacturing process complexity while achieving fatigue strength improvement.
2Strength
If shot peening or laser peening processes are used to improve fatigue strength, then the fatigue strength of the workpiece increases, but the manufacturing time increases due to additional process steps
Solution Approach 1:
The patent merges the fatigue strength improvement operation with the forming operation into a single integrated process step. The punch and die assembly simultaneously performs forming and surface feature imprinting, eliminating the need for separate peening process steps and thereby improving manufacturing efficiency.
Solution Approach 2:
The compressive residual stresses are induced during the forming operation itself, before the workpiece enters subsequent manufacturing steps. This preliminary action of improving fatigue strength during forming eliminates the need for post-forming peening operations, reducing total manufacturing time.
3Strength
If laser peening is used to improve fatigue strength, then compressive forces are generated to increase fatigue strength, but the workpiece must be moved to a specialized platform which disrupts the manufacturing process
Solution Approach 1:
The punch and die assembly is designed to perform both forming and fatigue strength improvement functions in one location. This eliminates the need to move the workpiece to a specialized peening platform, maintaining manufacturing process continuity and ease of operation while achieving fatigue strength improvement.
Solution Approach 2:
The workpiece receives fatigue strength improvement treatment during its own forming operation without requiring transfer to another system. The forming operation itself serves the dual purpose of shaping and strengthening the workpiece, eliminating process disruptions.
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
The method significantly increases the fatigue life of workpieces by up to 400 times at specific stress levels, providing a cost-effective and time-efficient solution for improving fatigue strength, with surface features showing improved endurance limits and resistance to crack propagation.
Implementation Method 1
the surface features induces compressive residual stresses at a sub-surface level of the workpiece
Implementation Method 2
Operating the punch and die assembly to imprint surface features one or more times on a portion of a surface of the workpiece, wherein the surface features induces compressive residual stresses at a sub-surface level of the workpiece
Data Source
AI summary
The present disclosure discloses a method for improving fatigue strength of a workpiece (100). The method comprises positioning the workpiece (100) in a punch and die assembly (102). Operating the punch and die assembly (102) one or more times to imprint surface features (2) on a portion of a surface of the workpiece (100), wherein the surface features (2) induces compressive residual stresses at a sub-surface level of the workpiece (100), and improves the fatigue strength of the workpiece (100).