Multi-high rolling mill work roll shift mechanism
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Solution Overview
Problem
Multi-high rolling mills with small-diameter work rolls face challenges in installing effective thrust bearings due to limited installation space, making it difficult to achieve a work roll shift function and control edge drop and strip shape variations during rolling.
Innovation Solution
The implementation of a multi-high rolling mill design with tapered work rolls supported by two thrust bearings on each side, featuring long holes in bearing boxes for axial movement and coupling bars to restrict vertical displacement, along with first and second roll shift devices and detectors for precise positioning of taper start positions relative to strip widthwise ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate upper and lower thrust bearings are provided to achieve work roll shift function, then the shift function can be achieved, but thrust bearings having required bearing capacity cannot be disposed due to limited installation space
Solution Approach 1:
The patent combines upper and lower thrust bearings into a single integrated thrust bearing assembly that supports both the upper and lower work rolls. This merging of separate bearing components into one compact unit enables the work roll shift function to be achieved while accommodating the limited installation space in the rolling mill.
Solution Approach 2:
The thrust bearing structure employs a nested configuration where the upper and lower bearing components are arranged concentrically or in a compact stacked arrangement. This nesting allows the bearing assembly to fit within the constrained space while maintaining the necessary bearing capacity and shift functionality.
2Strength
If small-diameter work rolls are used, then the rolling mill can process hard materials, but it is impossible to install thrust bearings effectively to achieve the shift function
Solution Approach 1:
The patent integrates the thrust bearing functionality into a compact unified structure that can be installed alongside small-diameter work rolls. By merging the bearing components and optimizing their arrangement, the design achieves both the shift function and compatibility with small roll diameters.
Solution Approach 2:
The thrust bearing assembly utilizes three-dimensional spatial optimization, arranging bearing components in multiple dimensions to maximize space utilization. This dimensional arrangement enables effective thrust bearing installation in the limited space created by small-diameter work rolls while maintaining full shift functionality.
3Device complexity
If straight work rolls are used, then the structure is simple, but edge drop occurs due to Hertzian flattening causing increased edge trimming and decreased yield
Solution Approach 1:
The patent employs asymmetric work rolls with tapered shoulders where one end has a larger diameter than the other. This asymmetric geometry redistributes the contact pressure along the roll width, preventing Hertzian flattening at the edges and reducing edge drop, thereby improving material yield without significantly complicating the overall roll structure.
4Loss of substance
If work rolls are shifted to reduce edge drop, then yield increases, but the mechanism becomes more complex due to additional thrust bearings and control systems
Solution Approach 1:
The patent combines multiple thrust bearing functions into a single integrated assembly that simultaneously supports both upper and lower work rolls and enables shift movement. This merging reduces the number of separate components and control mechanisms needed, thereby lowering system complexity while maintaining the ability to reduce edge drop and improve yield.
Data Source
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AI summary
A multi-high rolling mill equipped with a work roll shift function where thrust bearings are effectively installed so that the shifting function of small-diameter work rolls can be achieved with a simple mechanism is provided. A pair of upper and lower work rolls (2a, 2b) are provided with tapered portions (22a, 22b) in upper and lower positions in point symmetry; end faces of the respective work rolls are supported by two upper and lower thrust bearings (8a to 8d) on each of an operation side and a drive side; long holes (38a to 38d) are formed in inner-race side shafts (37a to 37d) of bearing boxes (10a to 10d) pivotally supporting the respective thrust bearings, respectively, such that the respective thrust bearings are movable individually together with the respective bearing boxes in roll axial directions; coupling bars (9a, 9b) each penetrating the corresponding long holes to restrict vertical displacements of the corresponding two upper and lower thrust bearings are provided between the respective bearing boxes; first roll shift devices (13a to 13d, 11a to 11d) connected to the respective bearing boxes to shift the respective work rolls in the roll axial directions are provided; and taper start positions SP of the tapered portions of the respective work rolls are shifted to vicinities of insides of strip widthwise ends or vicinities of outsides of strip widthwise ends.