Rolling Method for Plate Thickness Uniformity
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Solution Overview
Problem
Older screwdown mills, which use mechanical screws that cannot be moved under load, face challenges in producing high-quality thick plates from ingots or thick slabs due to limitations in removing thickness and width variations, leading to significant yield loss and inefficiencies in processing.
Innovation Solution
A method involving multiple rolling passes with incremental roll gap reductions and broadsiding to convert tapered ingots or slabs into rectangular plates, utilizing mechanical screws to adjust the roll gap and count revolutions to calculate the length for each pass, allowing for a stepped thickness profile and subsequent width increase without the need for hydraulic control systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If traditional full-length rolling passes are used on screwdown mills, then the mechanical screw can set the roll gap, but significant yield loss occurs due to inability to remove thickness and width variations
Solution Approach 1:
The rolling process is divided into multiple sequential passes, each handling a specific section of the ingot. The ingot is rolled in stages where different portions are processed in different passes, allowing the mechanical screw to effectively remove thickness and width variations in each segment without excessive yield loss.
Solution Approach 2:
The method performs preliminary rolling passes to prepare the ingot by removing surface variations and taper before final rolling. This preliminary action creates a more uniform workpiece that can be processed more efficiently in subsequent passes, reducing overall yield loss.
2Manufacturing precision
If hydraulic gap control systems are used, then thickness and width variations can be removed effectively, but older screwdown mills cannot be converted making the process inapplicable
Solution Approach 1:
The method is designed to work with the existing mechanical screw system of older mills, making the system serve its original function while achieving improved results. The mechanical screw's inherent capabilities are utilized through optimized rolling passes rather than requiring replacement with hydraulic systems.
Solution Approach 2:
The rolling process is segmented into multiple passes that accomplish what a single hydraulic-controlled pass would achieve. By dividing the deformation into stages with intermediate unloading and repositioning, the mechanical screw system achieves comparable thickness and width uniformity.
3Loss of substance
If multiple rolling passes with partial passes are used, then yield loss is reduced and quality improved, but processing time increases
Solution Approach 1:
The method uses partial passes where only portions of the ingot are rolled in each pass rather than rolling the entire length. This partial action allows the mechanical screw to be repositioned and optimized for different sections, reducing yield loss while managing processing time through efficient sequencing.
4Manufacturing precision
If the mechanical screw adjusts roll gap in multiple steps, then thickness uniformity improves, but the number of rolling passes increases
Solution Approach 1:
The thickness reduction is segmented into multiple controlled passes, each with a specific roll gap setting. The mechanical screw is used to precisely set each gap in sequence, achieving superior thickness uniformity by systematically removing material in controlled increments rather than attempting single-pass reduction.
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 enables older screwdown mills to produce high-quality plates with reduced yield loss and improved uniformity, allowing for the use of existing technology to achieve results similar to those with hydraulic control systems, albeit with longer processing times and more steps.
Implementation Method 1
rolling the ingot or slab through a first pass extending over the full length of the ingot or slab to produce a rolled product
Implementation Method 2
using the mechanical screw to set a reduced roll gap
Data Source
Figure 1~3
Figure 4A~4D
Figure 5A~5B
AI summary
A method of rolling a metal plate from an ingot or thick slab (1,2) comprises setting a work roll gap with a mechanical screw (24) and rolling the ingot or slab through a first pass to produce a rolled product (21). The rolled product (21) is removed from the roll gap and the mechanical screw (24) is used to set a reduced roll gap (34a). The rolled product (21) is rolled through the reduced roll gap (34a) over a partial pass, the partial pass extending over less than the full length of the rolled product (21), to form a further rolled product (22, 21); and the further rolled product is removed from the roll gap. The method further comprises turning the rolled plate and carrying out a further roll pass in a width direction of the plate.