Z-Section Sheet Pile Rolling with Variable Roll Diameter
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Solution Overview
Problem
The existing methods for hot rolling Z-section sheet piles result in grooved rolls with a short lifetime due to the absence of mirror symmetry, leading to rapid wear and increased risk of roll fracture, as they require deep grooves and extreme roll gap contours.
Innovation Solution
A method involving rolling a curved preform of the web in successive roll gaps with varying diameters, allowing for less vertical space and shallower grooves, which reduces mechanical wear and the risk of roll fracture, enabling the rolls to be reworked more frequently and extending their lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If deep grooves and extreme roll gap contours are used to roll Z-section sheet piles without mirror symmetry, then the Z-section shape can be formed, but the roll lifetime decreases rapidly due to wear and fracture risk
Solution Approach 1:
The rolling process is divided into multiple passes with different roll gap contours. The first pass forms the basic Z-section shape with moderate groove depth, while subsequent passes refine the shape with shallower grooves. This segmentation allows the rolls to form the complex Z-section geometry without requiring extremely deep grooves that would wear out quickly.
Solution Approach 2:
The web curvature is pre-formed in the first rolling pass before the final corner shaping. By preliminarily forming the curved web with moderate roll gaps, the subsequent passes only need to form the corners with shallower grooves, reducing the overall groove depth required and extending roll lifetime.
2Shape
If deep grooves are used in rolls to form Z-section corners, then the corner shape is achieved, but mechanical wear increases and roll fracture risk increases
Solution Approach 1:
The roll gap contour is made variable through multiple passes rather than using a single static deep groove. The first pass uses a deeper contour to establish basic geometry, while subsequent passes use progressively shallower contours to refine the corner shapes. This dynamic approach distributes the deformation demand across multiple operations, reducing peak stresses and wear in any single roll.
Solution Approach 2:
The rolling parameters (roll gap depth, roll speed, temperature) are changed between passes. The first pass operates with higher temperature and larger gap to form the basic shape, while subsequent passes use lower temperature and smaller gaps for precision corner forming. This parameter variation allows corner formation without requiring excessively deep grooves that would compromise roll reliability.
3Volume of moving object
If successive roll gaps with varying diameters are used, then less vertical space is required and shallower grooves are possible, but the rolling process becomes more complex
Solution Approach 1:
The rolling process is segmented into multiple passes, each with a specific roll gap configuration. The first pass uses rolls with larger diameter variation to form the basic curved web, while subsequent passes use rolls with smaller diameter variation for corner formation. This segmentation reduces the maximum vertical space needed compared to a single-pass deep groove method, while the complexity is managed through standardized roll designs.
Solution Approach 2:
Instead of solving the shape formation problem primarily in the vertical dimension (deep grooves), the invention uses the longitudinal dimension (multiple passes along the rolling direction) to progressively form the Z-section shape. The varying roll diameters create a three-dimensional roll gap volume that accommodates the curved web formation, distributing the complexity across space and time rather than concentrating it in a single deep groove.
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
The proposed method increases the lifetime of rolls by reducing mechanical wear and the risk of fracture, allowing for more frequent reworking and enabling the use of a thinner slab as a starting product, while maintaining the quality of Z-section sheet piles.
Implementation Method 1
rolling a curved preform of the web in successive roll gaps defined by at least one roll pair comprising a grooved upper roll and a grooved lower roll
Implementation Method 2
subsequently straightening the curved preform of the web between an upper straightening roll and a lower straightening roll
Data Source
AI summary
A method for rolling a Z-section sheet pile comprises rolling a curved preform of a web (16) in successive roll gaps defined by at least one roll pair comprising a grooved upper roll (26) and a grooved lower roll (28), wherein: a first corner (18) and an adjoining first part of the curved preform of the web (16) are formed in a first groove (42) of an upper roll (26); and a second corner (20) and an adjoining second part of the curved preform of the web (16) are formed in a first groove (46) of a lower roll (28). In the last roll gaps forming the curved preform of the web (16), the diameter of the lower roll (28) decreases in a discontinuous manner in the interval between the first groove (42) in the upper roll (26) and the first groove (46) in the lower roll (26), and the diameter of the upper roll (26) increases in this interval in a complementary manner.