H-shaped Steel Flange Widening via Split Bending
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Solution Overview
Problem
Current methods for producing H-shaped steel with widened flanges face limitations in flange width expansion, leading to shape defects due to rapid changes in material shape during the rolling process, and are constrained by equipment scale and reduction amounts in rough rolling mills.
Innovation Solution
A method involving a rough rolling step with multiple calibers, where deep splits are created on the material's end surfaces using projections with acute-angle tip shapes, followed by sequential bending of flange portions in subsequent calibers, to efficiently produce H-shaped steel with wider flanges while minimizing shape defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If splits are created on slab end surfaces and edging rolling is performed to widen flanges, then flange width increases, but the rate of spread decreases significantly (from 0.8 to 0.5) and shape defects occur due to rapid shape changes
Solution Approach 1:
The flange widening process is divided into multiple sequential steps across different calibers. The first caliber creates initial splits, the second caliber deepens splits, and subsequent calibers gradually expand and bend the flange portions. This segmentation prevents rapid shape changes that cause defects while achieving the desired flange width.
Solution Approach 2:
The first and second calibers perform preliminary actions by creating and deepening splits before the main flange expansion. This preliminary preparation of the material structure enables controlled subsequent bending and expansion without causing shape defects.
2Length of moving object
If the size of the material (slab) is increased to increase the edging amount, then more material is available for spreading, but device limits in equipment scale and amount of reduction of rough rolling mills prevent sufficient flange widening
Solution Approach 1:
Instead of relying solely on increasing slab size or reduction amount in the longitudinal direction, the invention utilizes the width direction by creating splits and bending flange portions laterally. This dimensional approach to flange widening bypasses the limits of rough rolling mill reduction capacity.
3Length of moving object
If conventional rough rolling methods use wedge designing, reduction adjustment, and lubrication adjustment to improve spread, then some flange widening is achieved, but the rate of spread is limited to approximately 0.8 and cannot greatly contribute to flange width
Solution Approach 1:
The invention fundamentally changes the forming mechanism from conventional spread-based widening to split creation and flange bending. By changing the formation method parameter rather than adjusting conventional parameters like wedge angle or reduction amount, the process achieves much higher flange widening efficiency.
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 approach allows for the stable and efficient production of H-shaped steel with flanges wider than conventional sizes, reducing shape defects and overcoming equipment limitations by carefully controlling the tip angles and contact points in each caliber to achieve uniform flange thickness and width.
Implementation Method 1
projections with acute-angle tip shapes... create deep splits on the material's end surfaces
Implementation Method 2
sequential bending of flange portions in subsequent calibers
Data Source
AI summary
[Object] To suppress occurrence of shape defects in a material to be rolled and enable efficient and stable production of an H-shaped steel product with a flange width larger than a conventional flange width by creating deep splits on end surfaces of a material (e.g., slab) using projections with acute-angle tip shapes, and sequentially bending formed flange portions.[Solution] Provided is a method for producing H-shaped steel, the method including: a rough rolling step; an intermediate rolling step; and a finish rolling step. In a rolling mill that performs the rough rolling step, a plurality of calibers to shape a material to be rolled are engraved, the number of the plurality of calibers being four or more. Shaping of one or a plurality of passes is performed on the material to be rolled in the plurality of calibers. In a first caliber and a second caliber among the plurality of calibers, projections to create splits vertically with respect to a width direction of the material to be rolled are formed. In a second caliber and subsequent calibers among the plurality of calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with caliber peripheral surfaces in shaping of at least one pass. In a third caliber and subsequent calibers among the plurality of calibers, a step of sequentially bending divided parts formed by the splits is performed.