Hydraulic Roll Gap Control With Parallel Valves for Speed and Precision
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Solution Overview
Problem
In strip rolling mills, achieving high rolling speeds and precise adjustment of the roll gap for flexible rolling of strip material with variable thickness profiles is challenging due to the need for large and rapid changes in the roll gap, which existing hydraulic control systems struggle to manage effectively.
Innovation Solution
A hydraulic arrangement featuring a double-acting valve system with two valve arrangements, one with a larger nominal volume flow for fast actuation and another with a smaller volume flow for precise positioning, allowing for high-speed and high-accuracy control of the roll gap by dividing the stroke into sections for efficient and dynamic adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single hydraulic valve arrangement is used for roll gap adjustment, then the system structure is simple, but the system cannot achieve both high-speed actuation and high-precision positioning simultaneously
Solution Approach 1:
The hydraulic control system is segmented into two independent valve arrangements: a first valve arrangement with high flow capacity for rapid roll gap changes, and a second valve arrangement with precise flow control for accurate positioning. This segmentation allows each valve to specialize in one function, resolving the contradiction between speed and precision.
Solution Approach 2:
The system dynamically switches between the two valve arrangements based on the rolling process requirements. During flexible rolling with variable thickness profiles, the first valve arrangement enables quick roll gap changes to follow the thickness profile, while the second valve arrangement provides fine adjustments for precise thickness control.
2Productivity
If a single hydraulic valve arrangement is used, then the device complexity is low, but the productivity for flexible rolling is insufficient
Solution Approach 1:
The hydraulic control system is divided into two specialized valve arrangements, each optimized for specific tasks. The first valve arrangement handles large-volume fluid flow for rapid roll gap adjustment, enabling high rolling speeds. The second valve arrangement handles precise flow control for accurate positioning. This segmentation improves productivity while keeping each component relatively simple.
Solution Approach 2:
The system uses two parallel valve arrangements that can be controlled independently or simultaneously, providing redundant control paths. This allows the system to achieve high productivity through coordinated operation of multiple valves without requiring a completely complex reconfiguration of the hydraulic system.
3Manufacturing precision
If a single hydraulic valve arrangement is used, then the system is easy to operate, but the manufacturing precision of variable thickness profiles is insufficient
Solution Approach 1:
The control system is segmented into two valve arrangements with distinct functions: the first valve arrangement manages overall roll gap positioning for variable thickness profiles, while the second valve arrangement provides fine-tuned flow control for precise thickness accuracy. This segmentation achieves high manufacturing precision while maintaining operational simplicity through clear functional separation.
Solution Approach 2:
The second valve arrangement acts as an intermediary between the hydraulic system and the final roll gap positioning, providing a buffer for fine adjustments. This intermediary valve arrangement enhances manufacturing precision by decoupling the coarse positioning (first valve) from the fine positioning (second valve), making the overall system easier to control.
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 solution enables highly dynamic and precise control of the roll gap, allowing for the production of strip material with variable thickness profiles at high rolling speeds, improving productivity and accuracy by utilizing high pressures and efficient volume flow management.
Implementation Method 1
A hydraulic arrangement for controlling a roll gap of a roll stand includes at least one hydraulic adjusting unit for adjusting the roll gap
Implementation Method 2
a first double-acting valve arrangement for variably controlling the adjusting unit; and a second double-acting valve arrangement for variably controlling the adjusting unit, which is connected in parallel with the first valve arrangement and has a larger nominal volume flow than the first valve arrangement
Data Source
AI summary
A roll stand with at least one working roll for rolling strip material and with a hydraulic arrangement for controlling a roll gap of the roll stand, comprises at least one hydraulic adjustment unit for adjusting the roll gap, the hydraulic adjustment unit comprising a cylinder and an adjusting piston dividing the cylinder into a first chamber and a second chamber; a first double-acting valve arrangement and a second double-acting valve arrangement which are each connected to the first chamber and the second chamber for variable control of the adjusting unit, wherein the second double-acting valve arrangement is connected in parallel with the first valve arrangement and has a larger nominal volume flow than the latter; and wherein the adjusting unit can be pressurized with an working pressure of more than 200 bar.