Roll Gap Adjustment Research Articles

Are edger rolls useful to control the plate motion and camber in a reversing rolling mill?

In heavy-plate hot rolling, reversing rolling mills are typically used to reduce the thickness of steel slabs. Some reversing rolling mills are equipped with edger rolls to control the width of the rolled plate. At best, the straight plate centerline coincides with the lateral centerline of the rolling mill and the desired rectangular shape is exactly realized. In reality, lateral asymmetries like temperature gradients and thickness inhomogeneities cause a lateral movement, a camber, and a wedge-shaped cross section of the plate. These effects can reduce the product quality and entail collisions with the mill stand or other equipment along the roller table. To prevent this, active control of the lateral position and contour shape is desirable. In this work, a roughing mill where the roll gap adjustment is self-retaining, meaning that it can only be adjusted between rolling passes, is considered. As a control input during the rolling passes, the lateral position of the edger rolls is exploited. A mathematical model for both the lateral motion and the resulting shape of the plate is derived. The model is validated by measurement data recorded in an industrial plant. Based on the validated model, the question if edger rolls are useful to control the plate motion and shape is discussed. A two-degrees-of-freedom control concept composed of an optimization-based feedforward controller and a proportional feedback controller with Smith predictor is derived for the lateral motion and shape. The performance of the proposed control concept is demonstrated in simulation studies based on the validated model.

A Product-Oriented Synchronization and Effective Information Extraction of Continuous Streaming Data for Relationship Mining in a Hot Rolling Process

Abstract Massive continuous streaming data are generated over time during production in a multistage manufacturing process. This paper aims to develop a product-oriented synchronization and effective information extraction of continuous streaming data and further model the relationships among variables for knowledge discovery. Take the steel rolling process as an example; this paper proposes a three-step data analytics procedure for product-oriented synchronization of continuous streaming data, effective information extraction, and further conducting relationship mining between the roll gap adjustment operations and product shapes based on the product-oriented data. The developed procedure first converts the continuous streaming data generated over time in a production process to product-oriented data set, then extracts the information related to the causes and effects of roll gap adjustments, and finally fits the model describing the relationship among the roll gap adjustments, the change of rolling torques, and the change of product dimensions. This data analytics procedure facilitates the decision-making in the steel rolling process and illustrates an effective application of massive in-situ sensing data towards intelligent decision-making in data-rich manufacturing processes.

Optimal control of plate motion and camber in a reversing rolling mill

In plate rolling, reversing roughing mills are commonly used as a first processing step after casting. They are typically equipped with edger rolls for width reduction. During a rolling pass, lateral asymmetries like temperature gradients or thickness inhomogeneities can cause two major problems. The plate may rotate in the rolling gap and thus move in lateral direction. Another problem is that the plate may leave the mill stand with a cambered shape. In the worst case, these problems entail collisions with the mill stand or other equipment along the roller table. It is an essential control task to avoid such problems. In general, the exit thickness profile and the motion of the plate are controlled by adjusting the roll gap height. The latter has also an influence on the contour shape but, for active control of the plate width and contour shape, the use of edger rolls is more common. This is especially true if the roll gap adjustment is self-retaining, meaning that it cannot be adjusted during a rolling pass. In this work, such a roughing mill and its edger rolls are considered. A mathematical model for the motion and the camber of the plate is derived. Based on this model, a linear quadratic regulator (LQR) for both the plate motion and the resulting camber is developed. It uses the lateral forces of the edgers as control inputs. In a cascaded control structure, these forces are regulated by a subordinate admittance controller. The developed control system is validated in simulation studies.

Designs and Feasibility Assessments of an Integrated Linear Electromagnetic Actuator for Cold Roll Mill Applications

This paper will present the detailed design and feasibility assessments of a linear electromagnetic actuator for providing the required roll-gap adjustment forces directly. A systematic analyzing scheme will be developed to optimize the system structures within specified physical constraints and steady-state operational requirements. The magnetic fluxes and thrusts that can be provided by the proposed system will be analyzed in detail, and the installation comparisons with those rotary electromagnetic counterparts will be discussed. By considering the desired system response times, the corresponding dynamic operational performances are also investigated. From these investigations, the technical feasibilities of adopting such electromagnetic systems for those commonly used hydraulic cylinder/servo valve compositions in the tandem roll mill can then be confirmed.

라면 면대의 균일한 두께를 위한 압연공정 자동화

The basic processing unit for instant ramen noodles includes mixing, rolling, boiling, frying, cooling, and packing processes. For uniform thickness of dough sheets in rolling process, the roll-gap in rolling process needs to keep uniform thickness of flour sheets in spite of different kinds of raw materials. In this paper, we have developed a roll gap adjustment system using a PLC (Programmable Logic Controller) with a touch panel and an AC servo-mechanism to make dough sheets with a good gluten starch-network structure and uniform thickness and to contribute to process standardization by transferring from tacit knowledge of skilled workers to explicit knowledge. The developed system can adjust the roll gap in units of 0.01mm and correspond to various product items which have different thickness specification by recalling the presetting values of the desired thickness from database.

Design of a New Type Casting Rolling Mill Screw down System

Considering the advantages and disadvantages of the mill screw down system now, a new type screw down system of caster is designed in this paper. Electro-hydraulic double-precision device is adopted in the synchronized screw down system.Bilateral synchronous motor is adopted first for coarse adjustment, and then use hydraulic servo cylinder to realize synchronization precision adjustment. It can adjust roll gap with double-precision, which can both achieve the purpose of rapid screw down and meet the accuracy requirements of the roll gap adjustment. Rotate both sides of screw down nuts using one hydraulic cylinder to achieve simultaneous fine-tuning of the roll gap. While coarse and fine adjustment, the actions are coordinate and non-interference. The screw down nut designed is compound nut, which can effectively compensate for the loosening and improve the accuracy of the roll gap adjustment. By analyzing and comparing, the new type screw down system of caster has some advantages such as double-precision adjustment, well synchronization, easy to operate and low cost, which have practical significance to improve the performance of the twin-roll casting machine.

Design of the Pinch Machine for Battery Grid Continuous Casting Machine Based on Link and Floating Gear Mechanism

In order to realize pinch during the production of the continuous casting battery grid, using the link and floating mechanism a pinch machine is designed which can automatically adjust the roll gap and pinch tension. First the structure of the grid pinch machine is introduced ,in which adopts the dual drive roller to achieve the upper and lower pinch roll and pinch roll to rotate in accordance with the same speed, but in the opposite direction. The pinch force generates by the fiction force between the grid plate and the upper and lower pinch roller. By means of the shifting bearing and spring the position of the upper pinch roller is controlled and the roll gap adjustment mechanism adopts the link and floating gear mechanism which results in structure simplification , high reliability, Low cost, stable, long life and low noise. Finally, according to the design principle of the pinch machine, using the theoretical mechanics and the Euler formula the pinch roller tension, tension roller tension and pinch pressure are calculated. The pinch machine has made it possible to achieve the manufacturing system of continuous casting battery grid.

Effect of roll gap adjustment on exit cross sectional shape in groove rolling—Experimental and FE analysis

We machined work roll with groove worn down as well as groove with no wear. We then performed a pilot hot rod rolling test at temperature of 1000 °C using plain carbon steel (0.1% C) as the roll gap decreases from reference roll gap (6.5 mm) to 3.5 mm. To understand better the effect of roll gap (i.e., section height) adjustment on the exit cross sectional area (ECSA) variation of workpiece in a two-stand groove rolling process with wear is considered, we carried out a series of three dimensional finite element analysis. Results reveal that variation of ECSA is almost linearly proportional to roll gap change while the roll gap decreases from reference roll gap (6.5 mm) to 3.5 mm. In oval groove rolling, the exit cross sectional shape and area predicted by FEA is in a good agreement with those measured. In round groove rolling, however, some deviations between FEA and experiment are observed because of roll groove geometry coupled with cross sectional shape of incoming workpiece. In the two-stand groove rolling, the effect of roll gap adjustment at each stand on the exit cross section of workpiece is somewhat different, in comparison with single-stand groove rolling. The roll gap adjustment at the previous stand has a more influence on the ECSA of workpiece than that of the next stand.

A study of roll gap adjustment due to roll wear in groove rolling: Experiment and modelling

In the tandem groove rolling process, when a certain amount of wear on the work roll exists and the roll speed is not changed, the roll gap, i.e. the section height, should be adjusted to keep a mass balance between stands, i.e. multiply the exit cross-sectional area by the roll speed between stands. To investigate the actual relationship between the amount of wear on the work roll and the subsequent exit cross-sectional area variation, the authors designed wear contours and machined them on the original roll groove, i.e. on the roll groove with no wear. They then performed a pilot hot rolling test using a work roll with a worn-down groove and one with a groove with no wear, and measured the exit cross-sectional area of the workpiece while the roll gap changed. To predict the amount of roll gap adjustment that compensates wear, a model for roll gap adjustment is proposed. In the proposed model, the authors introduced the concept of equivalent roll gap adjustment, which reduces the increased exit cross-sectional area owing to wear up to a base exit cross-sectional area of the workpiece. Results reveal that the exit cross-sectional area calculated by the roll gap adjustment model is in good agreement with the exit cross-sectional area measured. It has been found from the pilot hot rolling test that variation in exit cross-sectional area is almost linearly proportional to roll gap change while the roll gap decreases from a datum roll gap to about half of the datum one.

Experimental study for roll gap adjustment due to roll wear in single-stand rolling and multi-stand rolling test

To investigate a correlation between the amount of wear and roll gap (pass height) adjustment, we performed a single-stand reversible pilot groove rolling test as well as rolling test in an actual rod mill. In case of the pilot rolling test, we designed wear contour (profile) and machined it on the original roll groove (i.e., roll groove with no wear) to make the roll groove worn down. For the actual rod mill test, we developed a measuring device which can detect the actual wear profile.