Press-Formed Steel Sheet Edge Heating for Stretch Flange Cracks
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Solution Overview
Problem
Existing methods for manufacturing press formed products using high tensile strength steel sheets face challenges such as stretch flange cracks, which are difficult to suppress without complicating die shapes or applying unnecessary heat treatments, especially for automobile components like lower arms.
Innovation Solution
A method involving shearing, localized heating, and cooling of the end surfaces of metal sheets to identify and mitigate stretch flange crack regions, using laser or induction heating to minimize heat application to the metal sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high tensile strength steel sheets are used to achieve weight reduction and collision safety improvement, then strength and safety are improved, but stretch flange cracks occur during press forming
Solution Approach 1:
The patent applies preliminary heating to the metal sheet before press forming to increase its temperature to 400-1000°C. This preliminary thermal treatment modifies the material properties in advance, enabling the high tensile strength steel sheet to undergo press forming without developing stretch flange cracks, thus resolving the contradiction between using high-strength material and maintaining forming quality
Solution Approach 2:
The patent changes the temperature parameter of the metal sheet from ambient temperature to 400-1000°C through heating. This parameter change transforms the material's mechanical properties, reducing its susceptibility to stretch flange cracks during press forming while maintaining its high tensile strength characteristics
2Reliability
If the steel sheet is heated to 400°C or more to suppress stretch flange cracks, then forming quality is improved, but the die is easily damaged and mass-production cost increases
Solution Approach 1:
The patent applies heating locally to the metal sheet rather than heating the entire press forming system. By targeting only the metal sheet for heating to 400-1000°C, the treatment suppresses stretch flange cracks while avoiding the need to heat the die, thereby preventing die damage and reducing additional manufacturing costs
3Reliability
If the steel sheet is heated to suppress stretch flange cracks, then forming quality is improved, but a heating device must be incorporated in the die which complicates the die shape
Solution Approach 1:
The patent extracts the heating function from the die structure and applies it separately to the metal sheet. By using an independent heating method on the sheet rather than incorporating heating devices into the die, the patent suppresses stretch flange cracks while maintaining simple die structure and avoiding increased device complexity
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
Reduces the risk of stretch flange cracks and improves formability without unnecessary heating, leading to improved yield and component strength.
Implementation Method 1
using laser or induction heating to minimize heat application to the metal sheet
Implementation Method 2
using laser or induction heating to minimize heat application to the metal sheet
Implementation Method 3
the steel sheet temperature during the forming is increased to 400°C or more and 1000°C or less, whereby dynamic recovery of the dislocation occurs during processing
Implementation Method 4
localized heating, and cooling of the end surfaces of metal sheets
Data Source
Figure 1~2B
Figure 3~4
AI summary
To provide a press formed product in which a stretch flange crack can be suppressed and which is free from forming defects without complicating the die shape and without applying heat treatment more than necessary. A method for manufacturing the press formed product is a method for manufacturing the press formed product including applying press processing (press processing process (4)) including stretch flange forming to a single metal sheet of one sheet material after performing shearing processing (shearing process (1)) of the metal sheet to manufacture the press formed product. When a region where a stretch flange crack is estimated to be likely to occur when the single metal sheet is press formed by the press processing is set as a stretch flange crack region, the press processing (press processing process (4)) is applied after heating and cooling the end surface of the metal sheet positioned in the stretch flange crack region and at least the end surface in the end surface and the vicinity thereof in the single metal sheet after the shearing processing (heating process (2) and cooling process 3 (3)).