Vehicle Pillar Press Forming With Segmented Edge Clamping
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Solution Overview
Problem
High tensile strength steels used in vehicle pillars face challenges in press forming due to low ductility, leading to poor yield and the need for extensive trimming of clamped portions, particularly affecting the upper and lower pillar portions.
Innovation Solution
A press forming method and die configuration that clamps both ends of the workpiece in the longer side direction using pressing pads and a punch, while maintaining clamping by blank holders and a die, allowing for the center portion to be formed without clamping by blank holders, thereby reducing unnecessary material removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the whole periphery of the material is clamped using a blank holder in conventional press forming, then the deep drawing process can be performed, but many clamped portions must be trimmed and removed in the post-process, deteriorating the yield
Solution Approach 1:
The clamping function is segmented into two distinct systems: blank holders that clamp the shorter side ends and a die with pressing pads that clamp the longer side ends. This segmentation allows different regions of the workpiece to be clamped by different mechanisms, enabling the longer side ends to be clamped without requiring subsequent trimming operations, thus improving material yield while maintaining manufacturability
Solution Approach 2:
Pressing pads are introduced as an intermediary component between the die and the workpiece to provide localized clamping at the longer side ends. These pressing pads transmit the clamping force selectively to the ends that would otherwise require trimming, allowing the main body of the material to be formed without excessive clamping that would necessitate post-process removal
2Strength
If high tensile strength steel is used to achieve high strength and fracture strength, then deformation strength and fracture strength are improved, but ductility deteriorates, making deep drawing difficult
Solution Approach 1:
The clamping force is applied locally at specific regions (ends of the workpiece) rather than uniformly across the entire periphery. This localized clamping approach, implemented through pressing pads at the longer side ends and blank holders at the shorter side ends, reduces restraint in the central deformation zone, thereby improving the formability of high tensile strength steel while maintaining the necessary strength properties
Data Source
AI summary
A method of manufacturing a vehicle pillar includes: a blanking for obtaining a work piece by cutting a material; a drawing for obtaining an intermediate product by forming the work piece, using an upper die and a lower die; and a trimming for removing an unnecessary portion of the intermediate product. In the drawing, both ends of the work piece in a longer side direction are clamped between pressing pads and a punch. Then, in the drawing, both ends of the work piece in a shorter side direction are clamped between blank holders and a die. In the drawing, a center portion of the work piece is clamped between the die and the punch to form the work piece, while the clamping performed by the pressing pads and the punch, and the clamping performed by the blank holders and the die are maintained.