Self-Centering Roller Guide for Metal Strip Stability
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Solution Overview
Problem
The high-speed rolling of ultra-thin metal strips leads to instability, head folding, and cobbles due to aerodynamic and mechanical-aerodynamic phenomena, limiting feeding speed and causing damage during the winding process in hot rolling mills.
Innovation Solution
A self-centering roller guiding system with a curvilinear profile and a fluid blowing system to deform the strip, reducing lift forces and aerodynamic effects, combined with guiding tables and appropriately shaped rollers to maintain strip stability and prevent take-off and cobbles at high feeding speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the strip feeding speed is increased to improve productivity, then the production efficiency increases, but the aerodynamic lift force increases quadratically causing strip instability, head folding, and cobbles
Solution Approach 1:
The patent applies counterweight by using guiding tables positioned to support the strip head from below, counterbalancing the aerodynamic lift force that increases quadratically with feeding speed. This mechanical support prevents the strip head from rising and becoming unstable at high speeds while maintaining productivity.
Solution Approach 2:
The patent introduces guiding tables as an intermediary element between the strip head and the roller table. These tables provide intermediate support to the strip head, preventing direct interaction between the high-speed moving strip and the rollers, thereby eliminating head folding and cobbles while allowing high feeding speeds.
2Ease of operation
If the strip head impacts the roller at a high angle to maintain feeding direction, then the strip is guided towards the pass line, but the collision causes rebound and amplifies the take-off phenomenon
Solution Approach 1:
The patent applies preliminary action by positioning guiding tables upstream before the strip head reaches the rollers. The tables pre-align the strip head with the pass line and provide support in advance, preventing the need for high-angle impact collisions and eliminating the rebound phenomenon that causes folding.
Solution Approach 2:
The patent replaces the mechanical collision-based guiding system with a support-based system using guiding tables. Instead of relying on the strip head to impact rollers at an angle for guidance, the tables provide continuous support and gentle guidance, substituting the harmful mechanical impact with a non-contact or minimal-contact support mechanism.
3Strength
If corrugation rollers are used to stiffen the strip, then the strip rigidity increases, but permanent deformation occurs requiring rejection of the deformed portion
Solution Approach 1:
The patent replaces the mechanical corrugation system with a fluid dynamic system using air or water jets. The jets create aerodynamic or hydrodynamic forces that stiffen the strip temporarily during transport without causing permanent deformation. This substitution eliminates material rejection while maintaining sufficient rigidity for stable handling at high speeds.
Solution Approach 2:
The patent applies pneumatics and hydraulics by using jets of air or water to stiffen the strip. The fluid jets create pressure and flow patterns that increase the effective rigidity of the thin strip during transport on the roller table, eliminating the need for mechanical corrugation rollers that cause permanent deformation and material waste.
4Shape
If the distance between rollers is reduced to minimize bending, then the strip head remains closer to the pass line, but the number of rollers and system complexity increases
Solution Approach 1:
The patent extracts the guiding and support function from the roller system and places it on separate guiding tables. This allows the rollers to be spaced farther apart without compromising strip head position, as the tables provide the necessary support and alignment. The extraction of this function reduces the number of rollers needed and simplifies the overall system.
Solution Approach 2:
The patent introduces guiding tables as an additional dimensional element in the strip handling system. By adding this vertical support dimension, the system can maintain proper strip head position with fewer rollers, as the tables provide support in a different spatial dimension rather than relying solely on closely-spaced rollers.
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
The system effectively stabilizes the strip, preventing damage and ensuring smooth feeding and winding by increasing the strip's moment of inertia, reducing lift forces, and minimizing aerodynamic lift, thus enhancing winding quality and safety.
Implementation Method 1
there are provided at least one lead-in and containment means of the strip, arranged on said at least one roller table and provided with a blowing system of a fluid which is suitable to issue jets of fluid onto the moving strip in order to deform the strip on said feeding rollers
Implementation Method 2
The present invention, therefore, proposes to achieve the above-discussed purposes and aforesaid objects by making a guiding system for a metal strip exiting from a rolling mill, defining a longitudinal feeding direction, which in accordance with claim 1 comprises at least one roller table, comprising a plurality of feeding rollers having at least in the central part thereof, in cross section to the feeding direction, a substantially curvilinear profile
Implementation Method 3
there are provided guiding tables, arranged between the feeding rollers of at least one roller table, in order to support the head of the strip and minimize the possible instabilities when the head passes on said feeding rollers
Data Source
AI summary
A roller guiding system for thin strips (20) at a rolling system outlet which allows a safe guiding without take-off and consequent tipping/folding of the head of the strip and without cobbles even at high feeding speeds. The system of the invention prevents the strip from impacting or sliding on the upper containment devices (8) or on the rollers (4′) by its upwards or downwards movement, thus avoiding possible damages to the surface, such as scratches or lines. Furthermore, such a guiding system acts on the mechanical-aerodynamic phenomenon which causes instability in the head moving by making a self-centering guiding system which is thus suitable for improving the winding quality of the coil itself.