High-Speed Punching of Hot-Formed Metal Sheets
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Solution Overview
Problem
Shear cutting of high-strength metal sheets (>1300 MPa) results in microcracks, burrs, and strain hardening, requiring a die and complex setup, which complicates the manufacturing process.
Innovation Solution
High-speed punching at speeds over 6 m/s without a counter holder, using magnetic or pyrotechnical means to eliminate the need for a die, minimizing strain hardening and microcracks, and allowing for a simpler, more efficient process with robotic assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shear cutting is used to produce openings in high-strength metal sheets, then the opening can be created, but microcracks and burrs are formed around the hole perimeter
Solution Approach 1:
The patent changes the cutting speed parameter from conventional low speeds to high speeds (greater than 6 m/s). This parameter change transforms the cutting mechanism from a gradual shear process to a rapid impact process that prevents microcrack formation and burr generation by completing the cut before strain hardening can occur
Solution Approach 2:
The patent replaces the conventional mechanical shear cutting system with a high-speed punching system that uses kinetic energy and impact forces. This substitution eliminates the need for a die counter holder and changes the fundamental mechanism from shear deformation to impact-driven separation, resulting in cleaner cuts without microcracks
2Manufacturing precision
If shear cutting is used to produce openings in high-strength metal sheets, then the opening can be created, but strain hardening increases by more than 15% in the cutting region
Solution Approach 1:
The patent changes the cutting speed parameter to high speeds (greater than 6 m/s), which reduces the duration of the cutting process. This parameter change prevents strain hardening by completing the cut so rapidly that plastic deformation and associated hardening do not have time to develop in the material
3Manufacturing precision
If a die with contour matching the punch is used in shear cutting, then the opening can be produced with correct geometry, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the die counter holder from the cutting system. By using high-speed punching, the process no longer requires a die to support the workpiece or define the cut geometry, as the rapid impact creates the opening without needing formative contact on both sides of the material
Solution Approach 2:
The punch serves multiple functions: it defines the opening geometry through its own contour, provides the cutting action through high-speed impact, and eliminates the need for a separate die. This multi-functionality simplifies the overall device while maintaining geometric precision
4Manufacturing precision
If shear cutting is used to produce openings in high-strength metal sheets, then the opening can be created, but the widening of the opening in the breakage region exceeds 10% of wall thickness
Solution Approach 1:
The patent changes the cutting speed to high values (greater than 6 m/s), which alters the deformation mechanism from gradual shear with significant plastic flow to rapid impact separation. This parameter change minimizes material displacement and prevents the opening widening that occurs in conventional slow-speed shear cutting
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
Achieves smooth cuts with reduced strain hardening and microcrack risk, enabling efficient production of openings in high-strength metal sheets without the need for a die, and allowing for faster cycle times and lighter equipment.
Implementation Method 1
The high speed of the punch may be realized, e.g. with the aid of magnetic pulse, or pyrotechnical means, or electromagnetic pulse technique
Implementation Method 2
The high speed of the punch may be realized, e.g. with the aid of magnetic pulse, or pyrotechnical means, or electromagnetic pulse technique
Implementation Method 3
The high speed of the punch at more than 6 m/s causes in the workpiece a momentary temperature rise which, however, is limited to a very narrow workpiece zone
Data Source
AI summary
A hot-formed metal sheet has a tensile strength Rm>1300 megapascal (MPa) and includes an opening which is produced by high-speed punching at a speed of a punch of more than 6 m/s in the absence of a counter holder of a contour matching a contour of the punch, with a smooth cut proportion of the cutting surface of the opening amounting to more than 50%.