Curved Press Forming With Variable Die Shoulder Radius
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Solution Overview
Problem
Existing press forming methods for high-strength metal sheets face challenges in controlling fractures and wrinkles in curved parts, particularly due to mismatched material movement directions and increased tool size and cost requirements, as well as limitations in applying these methods to parts with specific shapes.
Innovation Solution
A press forming method that increases the bending radius of the die shoulder from the end to the middle of a curved portion, forms a shape to restrain rotational motion on the top portion, and enlarges the flange width in the middle portion, using a metal sheet with tensile strength between 440 MPa and 1600 MPa, to manage material movement and reduce strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-strength metal sheet is used for press forming, then the collision safety and weight reduction are improved, but the ductility decreases causing fracture and the yield strength increases causing wrinkles
Solution Approach 1:
The invention changes the geometric parameters of the die shoulder (bending radius and position) to control material flow and strain distribution during press forming of high-strength metal sheets, preventing fracture and wrinkles while maintaining formability
Solution Approach 2:
The invention applies different bending radii at different locations of the die shoulder (larger at the curved portion, smaller at the straight portion) to locally control material flow and strain distribution, preventing defects in critical areas
2Ease of manufacture
If existing press forming methods are used for parts with curved portions, then the material can be formed, but the material movement direction does not coincide with the pull direction causing ineffective fracture control
Solution Approach 1:
The invention creates an asymmetric die shoulder configuration with different bending radii for curved and straight portions, aligning material flow direction with the pull direction in curved portions to effectively control fracture
3Manufacturing precision
If a pad is used to pressurize the top portion to control wrinkles, then the wrinkle formation is reduced, but the tool size and cost increase
Solution Approach 1:
The invention designs the die shoulder geometry to automatically control material flow and prevent wrinkle formation during press forming, eliminating the need for additional pads or complex wrinkle control mechanisms
Solution Approach 2:
The invention changes the die shoulder bending radius parameter to control strain distribution and prevent wrinkles without requiring additional pressurization equipment
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 effectively controls fractures and wrinkles in the flange and top portions of curved parts, reducing tool size and cost while enabling the formation of complex shapes without significant wrinkles or fractures.
Implementation Method 1
press forming is a manufacturing method capable of manufacturing metal parts at a low cost in a short time... generation of a fracture due to a decrease in ductility and generation of wrinkles due to an increase in yield strength
Data Source
AI summary
A press forming method of press forming a press forming part that includes a top portion, a side wall portion continuous from the top portion via a punch shoulder, and a flange portion continuous from the side wall portion via a die shoulder, the press forming part having a curved portion curved in a recessed manner in a top view, the press forming method includes: making a bending radius of the die shoulder in the curved portion increased from an end side toward a middle portion of the curve.