Inverse-Contour Machining for Residual Stress Distortion
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Solution Overview
Problem
Machining operations often result in residual stress-induced distortion of parts, leading to costly rework and scrapping due to bowing, warping, and twisting, as existing methods to mitigate this issue are either ineffective or add significant costs.
Innovation Solution
A method that involves determining the variation in a distorted part caused by residual stress, inverting a contour to offset this variation, and using the inverted contour to configure a tool path for machining a second part, which compensates for residual stress distortion within tolerance of the nominal part, thereby eliminating the need for in-process adjustments or post-machining rework.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional machining operations are performed on parts, then manufacturing productivity is maintained, but residual stress distortion occurs causing parts to be out of tolerance
Solution Approach 1:
The invention applies preliminary action by pre-distorting the digital model of the part in the opposite direction of the expected residual stress distortion. This allows the part to compensate for distortion automatically when residual stresses are released during machining, eliminating the need for post-machining rework and maintaining both productivity and precision.
Solution Approach 2:
The invention applies preliminary anti-action by introducing a counter-distortion to the digital model that opposes the anticipated residual stress distortion. This counter-distortion ensures that when the actual distortion occurs during machining, the part ends up within tolerance without requiring additional corrective operations.
2Manufacturing precision
If successive roughing operations with time intervals are performed to mitigate residual stress distortion, then part tolerance is improved, but manufacturing cycle time increases
Solution Approach 1:
The invention eliminates the need for multiple roughing passes with time intervals by applying a preliminary counter-distortion to the digital model. This allows the part to be machined in a single continuous operation while still achieving the required tolerance, thereby reducing manufacturing cycle time significantly.
3Manufacturing precision
If mechanical straightening or material property alteration is performed to solve residual stress distortion, then part tolerance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention replaces complex mechanical straightening processes or material property alterations with a simple digital model modification. By pre-distorting the digital model, the compensation is achieved through software rather than additional mechanical equipment or complex processing steps, reducing device complexity and manufacturing cost.
4Manufacturing precision
If extensive rework is performed on distorted parts to make them acceptable, then part tolerance is improved, but productivity decreases and cost increases
Solution Approach 1:
The invention eliminates the need for extensive rework by applying preliminary counter-distortion to the digital model. This ensures that parts are produced within tolerance from the first machining operation, eliminating scrap and rework, thereby maintaining high productivity while ensuring part tolerance compliance.
Data Source
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AI summary
A method for manufacturing a part to compensate for residual stress distortion is disclosed. The method can include obtaining a first part based on a nominal part. The first part can be distorted from the nominal part by residual stress. The method can also include determining a variation of the first part from the nominal part. The method can further include determining an offset of the variation relative to the nominal part to compensate for the variation. Additionally, the method can include making a second part using the offset of the variation, wherein residual stress distorts the second part within tolerance of the nominal part.