FR3144027A1 - SYSTEM AND METHOD FOR GUIDING A ROLLING BELT IN A CONTINUOUS LINE - Google Patents

Abstract

SYSTEM AND METHOD FOR GUIDING A TRAVELING STRIP IN A CONTINUOUS LINE System (1) for guiding a scrolling strip (2) in a line (3) for continuous processing of said strip comprising a plurality of units ( 116, 131, 141, 171, 193, 202) and a plurality of detectors (114, 117, 132, 142, 151, 172, 194, 203) of the position of the strip arranged along the line, characterized in that it comprises a computer-assisted dynamic control model (300) capable of taking into account the position of the strip relative to the center of the line at several points along the line for shared control of the plurality of guidance units. Figure for abstract: Figure 1

Description

SYSTEM AND METHOD FOR GUIDING A ROLLING BELT IN A CONTINUOUS LINE Designation of the technical field concerned

The invention relates to continuous lines for annealing or galvanizing metal strips. It relates more particularly to guiding systems making it possible to maintain the strip in the axis of the line during its movement.

Technical problems addressed by the invention

The continuous metal strip annealing or galvanizing lines are composed in series of different sections, from an inlet section, followed by a treatment furnace composed of hot sections and cold sections, then an outlet section, in which a strip to be treated moves at high speeds, up to several hundred m/min, on strip drive and guide rollers.

In the oven, the strip undergoes a heat treatment which may include heating, temperature maintenance and cooling phases for the annealing and galvanizing lines, to which is added a metal coating stage for the galvanizing lines.

Galvanizing refers to all coatings, whether zinc coatings, aluminum coatings, zinc and aluminum alloys, or any other type of coating.

From entry to exit of the line, the strip is driven on rotating rollers using a traction force. The position of the longitudinal axis of some of these rollers can move in order to exert a guiding action on the strip and prevent it from shifting relative to the center of the line.

Several phenomena can cause lateral movement of the belt. For example, misalignments of transport rollers, a strip with surface defects created upstream of the processing line, for example during rolling, deformation of the strip in the oven during heating or cooling, or a problem with belt traction or roller rotation, can lead to belt guiding faults. This requires a correction in order to limit the strip offsets which could cause it to strike non-moving parts such as the walls of the oven, or even lead to a strip break.

The belt guidance function is dedicated to guidance units installed at several locations on the line. They are made up of a single roller or two rollers whose axes are not fixed. The belt centering effect is obtained by movement of the rollers around the axis of the line.

Depending on the type of line and its production capacity, three to seven guidance units are generally installed to achieve belt path correction and realignment.

State-of-the-art web guiding solutions do not always give satisfactory results, particularly for high-speed lines and those equipped with rapid heating and cooling sections.

The invention provides a solution to these problems by ensuring good guidance of the strip over the entire length of the line, from the unwinders at the entry of the line to the rewinders at the exit of the line, whatever the characteristics of the line. .

Technical background

A strip guide unit comprises a frame consisting of a movable part on which one or two guide rollers are placed and a fixed part linked to the structure of the line, the movable part of the frame being actuated by cylinders electric or hydraulic, a belt position detector and a control system which controls the position of the moving roller(s) according to the need for correction of the belt position. The guidance units are, for example, controlled via PID-type regulation loops.

To simplify the description, we will subsequently consider that the guide units comprise only one roller.

The strip position detector is generally of the capacitive or inductive type and is usually placed downstream of the guided roller, after the correction obtained by moving the roller.

According to the state of the art, each guidance unit operates autonomously, independently of the other guidance units present on the line.

Thus, at the level of a unit, the control system adjusts the positioning of the strip by modifying the position of the guide roller according to the information delivered by its position detector, without taking into account the state of the other guide units present on the line, nor any information other than that delivered by the position detector. Thus, the guidance unit reacts according to a localized band deviation, without taking other parameters into account.

The position of the strip is adjusted by the guiding unit according to the information delivered by its position detector, without anticipation of the evolution of the need for centering of the strip at the entrance to the guiding unit which would result from parameters affecting the position of the strip, for example the state of other guide units, geometric defects of the strip or the consideration of thermal deformation of the strip.

If the web offset noted by the position detector is too significant to be corrected by the guidance unit, an operator must intervene manually. It reduces the speed of the belt to facilitate its recentering and limit the risk of excessive offset which could lead to a collision of the belt with a fixed part of the line or to its breakage. This reduction in running speed leads to a drop in line production.

The effect of a guiding unit being localized to the place where it is positioned, it is necessary to place several guiding units along the line, hence a significant investment and maintenance cost for the web guiding function.

According to a first aspect of the invention, there is proposed a system for guiding a moving strip in a continuous processing line for said strip comprising a plurality of guide units and a plurality of detectors of the position of the strip. strip arranged along the line, characterized in that it comprises a computer-assisted dynamic control model capable of taking into account the position of the strip relative to the center of the line at several points along the line for a shared control of the plurality of guidance units.

The position of the strip at a location on the line is determined from a position detector. This position detector can be that of a guidance unit. It can also be an autonomous detector, unrelated to a guidance unit and remote from the guidance units.

The position of the strip at a point on the line can also be determined by calculation, by extrapolation from the information delivered by one or more position detectors arranged upstream and/or downstream of this point.

The number of strip position detectors and their position on the line is determined according to the configuration of the line, in particular the length of the pass line between the unwinder at the line entry and the rewinder at the line exit, the length of the strip strands, the diameter of the deflector rollers, the nature of the heating and cooling sections, according to the strip formats, in particular the maximum width and the minimum thickness, the thermal cycles carried out and in particular the maximum temperatures reached and the speeds of heating and cooling, and according to the maximum line speed and belt tension in the different sections.

There may be the same number of position detectors on the line as guidance units, or a different number, in particular a higher number.

Advantageously, position detectors are placed at strategic points along the line where significant strip off-centering can occur. It can also be positioned in places where an offset of the strip with respect to the axis of the line can occur in order to anticipate it as early as possible and make corrections to prevent the off-centering from taking too long. the extent. Knowledge of possible off-centering of the belt at these points, and the importance of this, is useful to improve the guidance of the belt along the line. These strategic points can be different depending on the nature of the line and its characteristics. For example, they can be located at the outlet of a rapid induction heating section or at the outlet of a rapid cooling section, for example by spraying a liquid onto the strip.

Taking into account the position of the strip at several points on the line, and therefore the importance of the possible off-centering of the strip at these points, allows the implementation of an overall strategy for centering the strip. It is thus possible to make a correction at the level of a guiding unit by anticipating the repercussion of this correction on all the points of the line, then to check it where detection of the position of the strip is carried out.

Thus, advantageously according to the invention, the guiding units are shared so as to control a guiding unit by taking into account the correction carried out by other guiding units arranged upstream and/or downstream in the direction of travel of the the band. This pooling makes it possible to generally improve the band centering by reducing the total correction that must be made.

According to an exemplary embodiment of the invention, the computer-assisted dynamic control model comprises a predictive model making it possible to anticipate a deviation of the strip along the line. The predictive model takes into account a database fed by the history of the behavior of the belts on the line, in particular according to the initial state of the belt at the entrance to the line, the operating conditions of the line, the thermal cycles carried out in the oven and the geometric characteristics of the strip. The database is also enriched with data collected on other continuous lines and the predictive model takes into account the resulting lessons.

From the acquired experience available in the database, the predictive model anticipates the behavior of the belt according to its characteristics and the operating conditions of the line to improve the control of the guidance system according to the invention.

Advantageously according to the invention, the predictive model comprises artificial intelligence. This takes advantage of “deep learning” based on information present in the database of the history of strip behavior on the line and data collected on other lines to anticipate and predict behavior. of the band and propose the best possible strategy for controlling the guidance system according to the invention.

The predictive model can request a shift of the strip at a point to anticipate, and thus avoid or mitigate, a shift which would occur downstream of this point without this shift.

Likewise, to prevent a guidance unit from reaching the maximum correction position, the predictive model can act on the other guidance units to further pool the corrections with other guidance units.

The predictive model can request an adjustment of the belt traction per section of the line based on an expected belt offset in order to improve the alignment of the belt.

The predictive model may also request an adjustment of the web speed based on an expected web offset in order to improve the alignment of the web.

The guidance system according to the invention may comprise at least one device for measuring spatial inhomogeneities in the band. It includes, for example, a laser profilometer coupled to a camera. The device for measuring spatial inhomogeneities in the strip also plays the role of strip position detectors.

This can be placed before the strip enters the oven so that, knowing the geometry of the strip before it enters the oven, the model anticipates the behavior of the strip as it moves through the line.

Knowing the spatial inhomogeneities in the strip at the entrance to the line, it is possible to determine the mechanical and thermal deformations of the strip which will result during its passage through the different sections of the oven, heating and cooling, by means thermomechanical and metallurgical models. So, for example, if the strip has thicker edges, if it has a long center or long edges, if it has buckles or undulations, these initial characteristics, and the anticipation of the evolution of these along the line, are taken into account by the computer-assisted dynamic control model to predict a strip offset and optimize its centering.

Another device for measuring spatial inhomogeneities in the strip can also be placed at another location on the line, for example at the outlet of a cooling section due to strip deformations which may occur there due to slopes. rapid cooling and the difficulty of obtaining uniform cooling across the width of the strip.

A device for measuring spatial inhomogeneities in the strip can also be placed at the outlet of the oven in order to loop back and improve the thermomechanical and metallurgical models for predicting mechanical and thermal deformations of the strip during its passage through the oven.

The guidance system according to the invention may comprise at least one device for measuring the temperature profile over the width of the strip. This includes, for example, a scanner or a set of pyrometers. The temperature profile measuring device can also act as belt position detectors when the measured temperature profile extends beyond the width of the belt, the position of the latter being determined by a variation sudden temperature surge beyond the edges of the strip.

The transverse temperature profile of the strip can modify its geometric profile, for example with long edges if they are hotter than the center of the strip. This information can be taken into account by the predictive model to improve the alignment of the band.

Belt traction varies along the line, particularly due to belt expansion in heating sections and contraction in cooling sections. Transport rollers are, for example, equipped with strain gauges to measure the tension of the belt along the line. The computer-assisted dynamic control model according to the invention takes into account the tension measurements of the belt to adjust the centering of the belt. The predictive model makes it possible to anticipate belt offsets that could occur due to variations in belt traction and thus improve guidance.

The number, nature (one or two rollers) and position of guide units on the line can be determined by modeling when designing a new line or during a study prior to modification of an existing line. Likewise, the number and position of the position detectors can be determined by modeling. This makes it possible to optimize the position of the equipment for maximum belt guiding efficiency. It also makes it possible to limit the number of equipment to that which is necessary in order to limit investment and operating costs.

The profiles of the transport rollers can also be determined by modeling when designing a new line or during a study prior to the modification of an existing line.

Advantageously, the modeling tools can include a digital twin of the line. This makes it possible to simulate the quality of the alignment of the strip along the line, and therefore to optimize, in particular the number, nature and location of the guiding units, position detectors, spatial inhomogeneities of the strip, devices for measuring the temperature profile over the width of the strip and the profile of the rollers, according to the operating parameters of the line, the thermal cycles carried out and the strip formats.

The improvement brought by the invention to the guidance of the strip along the line can make it possible to place a single roller guide unit where a two roller unit would be necessary according to the state of the art. In addition to the lower cost of a single roll unit, this above all allows for two additional strands of tape. This results in a shorter oven, therefore with a smaller footprint, and a lower investment cost.

According to a second aspect of the invention, a method is proposed for controlling a system for guiding a strip running in a continuous line, characterized in that it ensures dynamic control of a guiding system according to the invention by taking into account the position of the strip at a plurality of points along the line for controlling a guide unit.

Advantageously according to the invention, the strip can be deliberately decentered by a guiding unit in order to improve the overall guidance of the strip along the line. Causing a shift in the strip can in fact prevent a larger shift from occurring at another point along the line, without a deliberate shift.

According to an exemplary embodiment, the method according to the invention controls a guidance unit by taking into account spatial inhomogeneities in the band. It is thus possible to anticipate and avoid band deviations which would result from these spatial inhomogeneities.

According to an exemplary embodiment, the method according to the invention controls a guiding unit by taking into account the temperature profile over the width of the strip. It is thus possible to anticipate and avoid band deviations which would result from a significant temperature gradient over the bandwidth.

The invention thus allows:

. To optimize the total guidance capacity of the guidance units present on the line;

. To optimize the design of the line and in particular the oven;

. To reduce the cost, footprint and environmental impact of the line;

. To anticipate a deviation of the band;

. A gain in line productivity through an increase in line speed authorized by better guidance;

. A gain in productivity and line operating costs by reducing line stoppages resulting from belt breakage following a guiding problem;

. To limit the intervention of operators for the control and maintenance of the line, resulting in a reduction in the risk of accident during interventions following a belt break.

For example, the implementation of the invention on a galvanizing line with a capacity of 300,000 tonnes/year can allow an annual gain in productivity equivalent to a gain of one million euros per year. increase in line speed and 1.7 million euros due to a limited number of days of downtime due to belt breakage.

Brief description of the figures

Other characteristics and advantages of the invention will appear during reading of the detailed description which follows, for the understanding of which we will refer to the appended drawing in which:

is a schematic and partially represented view of a galvanizing line according to an exemplary embodiment of the invention.

Referring to the diagram of the , we can see schematically and partially represented, in longitudinal view, a vertical furnace galvanizing line 3 according to an exemplary embodiment of the invention. It comprises, successively and in the direction of travel of the strip 2, an input section comprising an unwinder 111, a welder 112, a tensioning block 113 with two rollers, a device 114 for measuring spatial inhomogeneities in the strip, an accumulator 115, a single-roller strip guiding unit 116, a strip position detector 117 and a second two-roller tensioner block 118, a direct-fire preheating section 120, a heating section 130 comprising a two-roller tape guide unit 131 and a tape position detection detector 132, a holding section 140 comprising a one-roller tape guide unit 141 and a tape position detection detector 142 , a slow cooling section 150, a rapid cooling section 160, an aging section 170 comprising a two-roller strip guiding unit 171 and a detector 172 for detecting the position of the strip, an exit section 180 and coating comprising a tensioner block 181 with 3 rollers and a dip coating tank 182, a final cooling section 190 after coating comprising a tensioner block 191 with two rollers, a water tank 192, a strip guiding unit 193 with two rollers and a strip position detector 194 and an output section 200 comprising an accumulator 201, a single roller guide unit 202, a strip position detector 203, a two-roller tensioner block 204, a shearer 205 and a winder 206.

In the example of realization of the , a strip position detector 132 is positioned upstream of the guide unit 131 located in the heating section 130. It is positioned on the strip strand located just upstream of the guide unit. For another line configuration or other operating characteristics thereof, it could for example be placed on a strip strand closer to the entrance to the heating section or, conversely, be placed in a strip strand located downstream of the guide unit 131.

Likewise, a strip position detector 142 is positioned downstream of the guide unit 141 located in the holding section 140. It is here placed three strands downstream of the guide unit but it could be placed on another strand or upstream of the guide unit for another line configuration or other operating characteristics thereof. .

Still for this example of realization of the , a strip position detector 172 is positioned downstream of the guide unit 171 located in the aging section 170. It is here placed five strands downstream of the guide unit but it could be placed on another strand or upstream of the guide unit for another line configuration or other operating characteristics thereof. .

A belt position detector 194 is also positioned downstream of the guide unit 193 located in the final cooling section 190. It is here placed just downstream of the guidance unit which corresponds to the usual position of position detectors according to the state of the art.

A guide unit 116, 202 and a strip position detector 117, 203 are also placed in each accumulator.

In this embodiment shown in , a pyrometer 151 is placed at the outlet of the slow cooling section 150. The temperature profile across the width of the strip measured by this pyrometer can be taken into account for controlling the guidance of the strip.

The line monitoring and control system includes a computer-assisted dynamic control model 300 making it possible to control the guiding units according to the positions of the strip detected along the line by the position detectors, taking into account the information operating process of the line. The Model 300 also takes into account transients, for example when changing tape formats, to adjust the control of the guiding units and maintain good tape centering.

The model 300 includes a predictive model 301 making it possible to anticipate a deviation of the strip along the line, the latter comprising artificial intelligence 302.

Claims (10)

System (1) for guiding a strip (2) moving in a line (3) for continuous processing of said strip comprising a plurality of units (116, 131, 141, 171, 193, 202) for guiding and a plurality of detectors (114, 117, 132, 142, 151, 172, 194, 203) of the position of the strip arranged along the line, characterized in that it comprises a model (300) of assisted dynamic control by computer capable of taking into account the position of the strip relative to the center of the line at several points along the line for shared control of the plurality of guidance units. System according to claim 1, characterized in that the dynamic control model (300) comprises a predictive model (301) making it possible to anticipate a deviation of the strip at a point along the line. System according to claim 2, characterized in that the predictive model (301) comprises artificial intelligence (302). System according to claim 1, characterized in that it comprises a device (114) for measuring spatial inhomogeneities in the band. System according to claim 1, characterized in that it comprises a device (151) for measuring the temperature profile over the width of the strip. Line (3) for continuous processing of a metal strip (2), characterized in that it comprises a system (1) for guiding the strip according to one of claims 1 to 5. Method for controlling a system (1) for guiding a strip (2) running in a continuous line (3), characterized in that it ensures dynamic control of the guiding system according to one of claims 1 to 5 taking into account the position of the strip at a plurality of points along the line for controlling a guiding unit (116, 131, 141, 171, 193, 202). Method according to claim 7, characterized in that it controls a guiding unit (116, 131, 141, 171, 193, 202) taking into account spatial inhomogeneities in the band. Method according to claim 7, characterized in that it controls a guiding unit (116, 131, 141, 171, 193, 202) taking into account the temperature profile over the width of the strip. Method according to claim 7, characterized in that the alignment of the strip is deliberately decentered by a guiding unit (116, 131, 141, 171, 193, 202) in order to improve the overall guidance of the strip along line.