Retractable Punch Inserts for Deep Drawing Sheet Metal
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Solution Overview
Problem
Producing complex formed sheet metal parts with great drawing depth under serial production conditions is challenging due to limitations in feasibility and cost, especially when achieving complex shapes with small radii and high quality.
Innovation Solution
A method and tooling system where a metal sheet is formed using a pressing tool with a punch, downholder, and die, where punch inserts are actively retracted to create local material reserves, allowing for deep drawing with minimal additional shaping, enabling complex designs with small radii and high quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pressing tools are used to produce complex formed sheet metal parts with great drawing depth, then the production cost increases and feasibility is limited, but the drawing depth and quality requirements cannot be met
Solution Approach 1:
The pressing tool is segmented into multiple functional components: a punch with retractable punch inserts, a downholder, and a die with die ring. The punch inserts can be independently retracted to create local material reserves, allowing different regions of the metal sheet to be formed with different material flow characteristics. This segmentation enables complex shapes with great drawing depth while maintaining production feasibility.
Solution Approach 2:
The punch inserts are designed to be dynamically retractable during the pressing operation. As the upper tool part moves downward, the punch inserts actively retract to release local material reserves, enabling the metal sheet to flow into deep drawing regions. This dynamic adjustment allows the tool to adapt to complex geometries and achieve drawing depths of at least 200 mm while maintaining serial production conditions.
2Manufacturing precision
If multiple forming operations are used to achieve great drawing depth, then the production time increases and productivity decreases, but the drawing depth requirement cannot be satisfied
Solution Approach 1:
The punch inserts are positioned in an extended initial state before the pressing operation begins. During the pressing process, they actively retract to pre-create local material reserves in the metal sheet. This preliminary action enables the metal sheet to flow into deep drawing regions during the single pressing operation, achieving great drawing depth without requiring multiple sequential forming operations, thus maintaining high productivity.
3Ease of manufacture
If the metal sheet material flows freely during forming, then the forming process is simpler, but the quality of the formed part deteriorates with material defects
Solution Approach 1:
The pressing tool creates different local conditions for material flow: the retractable punch inserts generate local material reserves in specific regions, while the die ring and downholder control the border region. During forming of the other region, the peripheral metal sheet is clamped between the die ring and downholder, preventing material flow from the border region and ensuring only local material reserves are used. This local control prevents material defects while maintaining process simplicity.
4Device complexity
If punch inserts remain in extended position during pressing, then the tool structure is simpler, but the drawing depth is limited
Solution Approach 1:
The punch inserts are designed with active retraction capability during the pressing operation. As the upper tool part moves downward to form the metal sheet, the punch inserts retract to release local material reserves, enabling the metal sheet to flow into deep drawing regions. This dynamic retraction mechanism achieves drawing depths of at least 200 mm while maintaining a relatively simple tool structure through mechanical coupling with the downholder.
Data Source
AI summary
A method for producing a complex sheet metal part includes clamping a border region of the metal sheet between a die ring of an upper tool part of a pressing tool and a downholder of a lower tool part of the pressing tool; moving the upper tool part further downwards thereby pulling the metal sheet over extended punch inserts of a punch of the lower tool part, thereby generating local material reserves of the metal sheet; moving the upper tool part further downwards while actively retracting the punch inserts, thereby releasing the local material reserves; and forming the metal sheet between the die and the punch using only the local material reserves.