Rolling Mill Balance Force Control for Inter-Roll Slide Suppression
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Solution Overview
Problem
Existing technologies fail to effectively suppress inter-roll slide during rolling processes, particularly when kiss roll occurs, leading to potential damage to components like bearings, especially when using work rolls with smaller radii for thinner strip thicknesses.
Innovation Solution
A method for setting work roll balance force that includes determining the mill longitudinal rigidity coefficient, kiss roll load, rolling load, and traction coefficient, and adjusting the work roll balance force to prevent excessive inter-roll slide by maintaining the traction coefficient within a safe limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If work rolls with smaller radius are used to roll thinner strip thickness, then strip thickness reduction is achieved, but load capacity of drive spindle declines
Solution Approach 1:
The patent introduces intermediate rolls as a mediator between the drive spindle and work rolls. The intermediate rolls have larger radius and are directly driven by the drive spindle, while the work rolls with smaller radius are driven by the intermediate rolls. This intermediary mechanism allows the drive spindle to drive larger-radius intermediate rolls (higher load capacity) which in turn drive the smaller-radius work rolls, thus achieving both thin strip thickness and sufficient load capacity.
2Reliability
If roll balance force is increased to prevent biting failure, then biting reliability is improved, but inter-roll slide increases causing component damage
Solution Approach 1:
The patent dynamically adjusts the roll balance force parameter based on the biting angle θx during the rolling process. Instead of using a fixed high roll balance force, the control device calculates and applies an optimal roll balance force that varies with the biting angle, ensuring sufficient biting reliability while preventing excessive inter-roll slide and component damage.
Solution Approach 2:
The patent implements a feedback control mechanism where the control device continuously monitors the biting angle θx and adjusts the roll balance force accordingly. The control device calculates the optimal roll balance force based on the current biting angle and applies it through the roll balance force applying device, creating a closed-loop control system that prevents both biting failure and excessive inter-roll slide.
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 approach effectively suppresses inter-roll slide without damaging components, ensuring stable rolling operations even when kiss roll occurs, by optimizing the work roll balance force based on mill conditions and traction coefficient limits.
Implementation Method 1
by using work rolls that draw in a hot-rolled strip material to be rolled by friction
Implementation Method 2
by holding down the strip material by using hold-down rolls that can be lifted and lowered so as to prevent the strip material from floating, the strip material gets to have pressing force which is larger than the reaction force received from the work rolls
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3
AI summary
In a work roll balance force setting method of a rolling mill, a kiss roll load Pk, a rolling load Pr, and rolling torque Tr of work rolls 610 and 611 in relation to a work roll angle θx of the tip position of a rolled material 5 between the start of biting of the rolled material 5 and completion of the biting are determined by using a mill longitudinal rigidity coefficient K and a rolling condition. Thereafter, the traction coefficient μrt between the work rolls 610 and 611 and intermediate rolls 620 and 621, and a maximum value μrtmax of μrt in relation to θx in a state in which hypothetical work roll balance force Pb is applied are determined from a sum P of Pk, Pr, and Pb, and Tr between the start of biting of the rolled material 5 and completion of the biting. Thereafter, a tolerated value μrtcr of μrt is compared with μrtmax, and work roll balance force at the start of biting of the rolled material 5 is reset to a value which is equal to or larger than a value that is required when μrt assumes the maximum value μrtmax, and equal to or smaller than a value that is a limit based on a constraint in terms of strength of the rolling mill, in a case where μrtcr is equal to or larger than μrtmax.