Hydraulic Dancer Roller Control for Stable Strip Tension
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Solution Overview
Problem
Existing methods for controlling strip tension during flexible rolling of metal strips at high speeds and varying thicknesses struggle to maintain constant tension due to rapid changes in strip speed, leading to inconsistencies in strip thickness tolerances and limitations in coil weight and rolling speed.
Innovation Solution
A device with a dancer roller arrangement, hydraulic drive, hydraulic tank, controllable valve, and hydraulic pressure accumulator, which allows for rapid and precise adjustment of strip tension by inferring hydraulic pressure and controlling the valve arrangement to provide a high volume of hydraulic fluid for quick tension adjustments, while minimizing line losses and preventing cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the coiler speeds are adjusted to compensate for strip speed variations, then strip tension can be maintained at low rolling speeds, but the coil weight is limited and rolling speed must be reduced due to mass inertia
Solution Approach 1:
The patent employs a dancer roller mechanism driven by a hydraulic cylinder to control strip tension. The hydraulic system responds rapidly to strip speed variations by adjusting the dancer roller position, which in turn regulates the strip tension. This hydraulic actuation system enables fast response times that are not limited by coil mass inertia, allowing constant strip tension maintenance even at high rolling speeds where coiler speed adjustment alone would be insufficient
2Adaptability or versatility
If the roll gap is changed to achieve different strip thicknesses, then flexible rolling with up to 50% thickness variation is achieved, but strip speed and strip tension change rapidly causing thickness tolerance issues
Solution Approach 1:
The patent implements a feedback control system where strip tension is continuously monitored (directly or indirectly via dancer roller position) and used to regulate the dancer roller's position through the hydraulic drive. This closed-loop feedback mechanism compensates for the rapid strip tension changes caused by roll gap adjustments, maintaining constant strip tension throughout the rolling process even when producing strips with widely varying thicknesses, thereby ensuring consistent thickness tolerances
Solution Approach 2:
The dancer roller mechanism provides dynamic adjustment of strip tension in real-time during the rolling process. By allowing the dancer roller to move dynamically in response to strip speed and tension variations, the system adapts continuously to changing rolling conditions, maintaining optimal strip tension despite rapid changes in strip thickness caused by roll gap modifications
3Productivity
If high rolling speeds are used to increase productivity, then output is improved, but strip tension cannot be maintained constant due to rapid speed changes
Solution Approach 1:
The hydraulic drive system for the dancer roller provides rapid response capability that matches high rolling speeds. The hydraulic actuation can quickly adjust the dancer roller position to compensate for fast-changing strip tension conditions, enabling constant strip tension maintenance even at high productivity levels where traditional coiler speed adjustment would be too slow to respond
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
Enables rapid and precise regulation of strip tension, achieving small fluctuations below 35% even at high rolling speeds, ensuring consistent strip thickness and reducing non-productive times by maintaining constant strip tension.
Implementation Method 1
at least one hydraulic pressure accumulator for temporarily storing hydraulic fluid previously delivered by the hydraulic pump, the hydraulic pressure accumulator being arranged between the hydraulic pump and the valve arrangement
Implementation Method 2
The hydraulic drive is supplied with hydraulic fluid from the hydraulic tank by means of a hydraulic pump
Implementation Method 3
A controllable valve arrangement is arranged between the hydraulic tank and the hydraulic drive for controlling the hydraulic drive
Implementation Method 4
A pressure sensor for determining the hydraulic pressure is arranged in the hydraulic drive, the device being set up to infer the strip tension in the metal strip from the hydraulic pressure and to control the valve arrangement as a function of the determined strip tension
Data Source
AI summary
Device for controlling strip tension during flexible rolling of metal strip, the device comprising: a roller arrangement (11, 17) with at least one dancer roller (12, 18) whose position is adjustable for controlling the strip tension of the metal strip (8), at least one hydraulic drive (22) coupled to the dancer roller (12, 18) for adjusting it, a hydraulic tank (27) for hydraulic fluid, which is fluidly connected to the hydraulic drive via a hydraulic supply line (38), a controllable valve arrangement (29) between the hydraulic tank (27) and the hydraulic drive (22) for controlling the hydraulic drive (22), a hydraulic pump (28) with which the hydraulic drive (22) is supplied with hydraulic fluid from the hydraulic tank (27), and at least one hydraulic pressure accumulator (33) for temporarily storing hydraulic fluid previously delivered by the hydraulic pump (28).wherein the hydraulic pressure accumulator (33) is arranged between the hydraulic pump (28) and the valve assembly (29).