Free Bending of Recessed Sheet Workpieces Using a Filling Element
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Solution Overview
Problem
Existing methods for shaping large metal sheets used in aircraft outer paneling are limited to full-surface processing, leading to uncontrollable deformation in areas with machined recesses, requiring costly 5-axis portal milling machines for subsequent processing.
Innovation Solution
A method involving a filling element adapted to the mold cavity to equalize material thickness, allowing for step-by-step free bending of pre-machined workpieces, using a three-axis cutting machine, and employing a filling element made of acrylonitrile butadiene plastic (ABS) to ensure precise and repeatable bending, especially in areas with reduced material thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If known forming methods are used on workpieces with machined recesses, then the workpiece can be shaped, but uncontrollable deformation occurs in the area of shaped recesses
Solution Approach 1:
The filling element is placed in the mold cavity before the bending process begins. This preliminary action compensates for the material thickness reduction caused by machining recesses, ensuring that the bending forces are distributed evenly across the entire workpiece surface, including areas with pockets, rivet holes, and window cutouts. This prevents the uncontrollable deformation that would otherwise occur in these weakened areas.
Solution Approach 2:
The filling element acts as an intermediary between the mold cavity and the workpiece. It transfers the bending forces from the mold uniformly to the workpiece surface, compensating for the irregularities caused by machined recesses. This mediator ensures that the bending process proceeds with high precision and reliability, even in areas where the material thickness has been reduced by machining.
2Ease of manufacture
If workpieces are shaped first and then machined, then the desired shaped recess can be produced, but costly 5-axis portal milling machines are required with large space requirements
Solution Approach 1:
The filling element is prepared in advance to match the specific geometry of the mold cavity. This preliminary preparation allows the bending process to be performed with high precision on workpieces that have already been machined, eliminating the need for expensive post-bending machining operations with 5-axis portal milling machines.
Solution Approach 2:
The filling element changes the effective material thickness parameter in the mold cavity area by compensating for the material removal. This parameter change allows the bending process to proceed uniformly across the entire workpiece, including areas with machined recesses, achieving high precision without requiring complex 5-axis machining equipment.
3Adaptability or versatility
If full-surface processing methods are used, then the workpiece can be shaped, but workpieces with machined recesses cannot be processed satisfactorily
Solution Approach 1:
The filling element provides local compensation specifically in the mold cavity area where material thickness has been reduced. Instead of requiring a completely different processing method for workpieces with recesses, the filling element locally adjusts the material thickness in the affected areas, allowing the same bending process to handle both full-surface and machined workpieces with equal precision.
Solution Approach 2:
The filling element serves as a universal intermediary that adapts to different workpiece types. Whether the workpiece has no recesses, single pockets, multiple rivet holes, or window cutouts, the filling element compensates for the material thickness variations, enabling the bending process to achieve high precision across all workpiece configurations.
Data Source
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AI summary
The present invention relates to methods for changing the shape of a plate-like workpiece (10) having a recess formed by reducing the material thickness, comprising arranging the workpiece (10) on at least two spaced-apart support elements (12) of a machine bed (13), forming the workpiece (10) into a final shape by stepwise free bending, in which the steps of bending a partial section of the workpiece (10) by lowering an upper tool (14) between the support elements from a waiting position to a forming position (15), raising the upper tool (14) to the waiting position and moving the position of the workpiece (10) relative to the machine bed (13) in at least one feed direction are carried out repeatedly, and is characterized in thatthat before the workpiece (10) is formed into its final shape, a filling element (18) adapted to the mold recess and designed to compensate for material thickness is created and arranged in the area of the mold recess.