Press-Hardened Auto Components With Pre-Punched Hole Blanks
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Solution Overview
Problem
The existing methods for producing molded motor vehicle components with holes and partial hardening are inefficient, requiring high effort for shear-cutting and machining, and often result in suboptimal hole edge quality and mechanical properties.
Innovation Solution
A method involving laser cutting of steel strips into blanks, followed by punching holes in a mechanical punching device, heating above the austenitization temperature, and forming in a mold with controlled cooling to achieve high-strength components with uniform hole edge quality and reduced tearing risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If holes are introduced in the starting blanks before hot forming and press hardening using traditional shear-cutting and machining methods, then the component can be produced with hole features, but the production effort and time are excessively high
Solution Approach 1:
The patent replaces traditional mechanical shear-cutting and machining methods with laser technology for producing blanks with holes. The laser beam melts and vaporizes material to create holes directly during the blank cutting process, eliminating the need for separate punching or drilling operations after forming. This substitution of mechanical systems with optical/thermal energy systems resolves the contradiction by dramatically reducing production steps and time while maintaining manufacturing capability.
Solution Approach 2:
The patent performs the hole creation action in advance during the blank cutting stage, before the hot forming process. By integrating hole production into the initial blank preparation phase using laser technology, the component receives both its final shape and hole features simultaneously. This preliminary action eliminates subsequent machining steps and reduces overall production time while ensuring holes are properly positioned and formed.
2Productivity
If holes are produced by laser cutting in the blank, then production time is reduced, but the hole edge quality and mechanical properties deteriorate due to melting and vaporization effects
Solution Approach 1:
The patent optimizes laser processing parameters including power, pulse duration, frequency, and focus position to control the melting and vaporization process. By carefully adjusting these parameters, the laser creates clean hole edges with minimal recast layer and heat-affected zone. The use of pulsed laser modes with specific duty cycles allows precise control over material removal, maintaining hole edge quality while preserving the mechanical properties of the surrounding steel alloy.
Solution Approach 2:
The patent employs pulsed laser operation instead of continuous beam delivery. The periodic pulsing allows brief intervals for heat dissipation and material ejection between pulses, preventing excessive heat accumulation and melting. This periodic action creates clean hole edges with minimal thermal damage to the surrounding material, maintaining manufacturing precision while enabling efficient hole production through the blank.
3Manufacturing precision
If mechanical punching is used to produce holes in the blank, then hole edge quality improves, but the process complexity and device complexity increase
Solution Approach 1:
The patent combines the blank cutting operation and hole creation operation into a single integrated laser processing step. Instead of using separate mechanical punching equipment after blank formation, the laser beam simultaneously cuts the blank to shape and creates all required holes in one pass. This merging of operations eliminates the need for additional punching devices, tooling, and setup procedures, reducing device complexity while maintaining hole edge quality through optimized laser parameters.
4Productivity
If hot punching is performed in the mold during forming, then the process steps are reduced, but the risk of tearing and hole edge defects increases
Solution Approach 1:
The patent performs hole creation in the cold blank state before heating and forming, rather than attempting hot punching during the forming process. By creating holes in the cold, more ductile steel alloy before thermal processing, the material has better toughness and resistance to tearing. The holes are formed when the material is most forgiving of stress concentrations, and subsequent heating and forming then proceeds without risk of hole edge tearing or defects.
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
This method significantly reduces production time and effort, enhances hole edge quality, and achieves tensile strengths of ≥1,250 MPa and elongation at break of ≥4.5%, allowing for flexible hole patterns and reduced material complexity, while minimizing the need for additional reinforcement.
Implementation Method 1
divided into blanks in a laser cutting station by means of laser cutting
Implementation Method 2
transferring the perforated blank to a heating device and heating the blank to a temperature above the specific austenitization temperature of the steel alloy
Implementation Method 3
forming the blank to form the molded component and at least partially hardening the molded component in the mold
Data Source
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AI summary
The invention relates to a method for producing an at least partially hardened automotive component from a blank made of a hardenable steel alloy, wherein the automotive component has several holes. A steel strip made of a hardenable steel alloy, supplied in strip form on a coil, is pulled from the coil and laser-cut into blanks in a laser cutting station, where the edges are trimmed. Holes are then produced in the blanks by punching in a punching device. The blanks are then transferred to a heating device and heated to a temperature above the specific austenitizing temperature of the steel alloy, whereupon the blanks are formed into the component in a mold and the components are at least partially hardened.