Roll Stand Hydraulic Cylinder Control for Stable Piston Locking
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Solution Overview
Problem
Hydraulic control circuits for adjusting cylinders in roll stands face instability and reliability issues during sudden load changes, leading to thickness errors and cavitation due to the compressibility of hydraulic fluid and variable pressures.
Innovation Solution
A hydraulic control circuit with adjustable pressures in both chambers, controlled by a device that generates position-dependent signals for the valves, ensuring stable locking of the piston and preventing pressure drops, using a control device that adapts to wear and switches between position and pressure control states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If 4-edge control is used to compensate for flexibility changes during piercing, then piston stability improves, but pressure control complexity increases and cavitation risk arises
Solution Approach 1:
The control device continuously monitors the actual piston position and compares it with the target position, dynamically adjusting the control signals to both hydraulic valves based on position feedback. This closed-loop control maintains piston stability during piercing while adapting to changing load conditions, preventing the pressure control complexity and cavitation risks associated with open-loop 4-edge control
Solution Approach 2:
The control system transitions from static pressure control to dynamic position-based control, where control parameters are continuously adapted based on real-time piston position and load conditions. The control device adjusts valve signals dynamically during piercing operations, enabling the system to maintain stability without requiring complex predetermined pressure combinations
2Length of moving object
If hydraulic fluid column is increased to accommodate long stroke actuating cylinders, then adjusting range improves, but compressibility effects increase leading to thickness errors
Solution Approach 1:
The system replaces traditional mechanical position maintenance with active hydraulic control. Instead of relying on rigid mechanical linkages that would eliminate compressibility effects, the control device continuously adjusts hydraulic valve signals based on position feedback, compensating for fluid compressibility and maintaining thickness precision despite long hydraulic fluid columns
Solution Approach 2:
The control system dynamically adjusts pressure and flow parameters in response to position feedback, adapting hydraulic conditions to maintain precision during long-stroke operations. By varying control parameters rather than maintaining fixed conditions, the system compensates for compressibility effects throughout the extended stroke range
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 provides stable and reliable hydraulic locking, preventing piston yielding during sudden loads and reducing cavitation risks, allowing for longer hydraulic fluid columns without compromising rolling stability or quality.
Implementation Method 1
A hydraulic control circuit with adjustable pressures in both chambers, controlled by a device that generates position-dependent signals for the valves
Implementation Method 2
The problem increases due to the compressibility of the hydraulic fluid as the column of hydraulic fluid increases on the side of the cylinder that is compressed by the tapping
Implementation Method 3
the hydraulic pressure of the first hydraulic chamber being adjustable, i.e. variable, by actuating the first hydraulic valve
Data Source
Figure 1a~1b
Figure 2a~2d
AI summary
The invention relates to a hydraulic feedback control loop (1) and method for controlling a hydraulic actuating cylinder (3), in particular an adjustment cylinder for a working roll in a roll stand, which cylinder comprises a cylindrical housing (31) and a piston (32) slidably arranged therein which divides the housing interior into a first hydraulic chamber (34) and a second hydraulic chamber (35). The feedback control loop (1) comprises: at least one first hydraulic valve (10) which is designed to apply a hydraulic fluid to the first hydraulic chamber (34), wherein the hydraulic pressure of the first hydraulic chamber (34) can be adjusted by actuating the first hydraulic valve (10); at least one second hydraulic valve (11) which is designed to apply a hydraulic fluid to the second hydraulic chamber (35), wherein the hydraulic pressure of the second hydraulic chamber (35) can be adjusted by actuating the second hydraulic valve (11); a feedback control device (12-20) which is provided and designed for actuating the two hydraulic valves (10, 11) in order to actuate, in a position control state, the second hydraulic valve (11) by means of a position control signal dependent on the working position of the piston (32) and to actuate, in said position control state, the first hydraulic valve (10) by means of an adapted position control signal, which is a signal generated on the basis of the position control signal.