GB2138180A - Strip rolling mills - Google Patents
Strip rolling mills Download PDFInfo
- Publication number
- GB2138180A GB2138180A GB08409394A GB8409394A GB2138180A GB 2138180 A GB2138180 A GB 2138180A GB 08409394 A GB08409394 A GB 08409394A GB 8409394 A GB8409394 A GB 8409394A GB 2138180 A GB2138180 A GB 2138180A
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- GB
- United Kingdom
- Prior art keywords
- strip
- rolls
- signal
- lateral
- camber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/68—Camber or steering control for strip, sheets or plates, e.g. preventing meandering
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
- B21B13/06—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with axes of rolls arranged vertically, e.g. edgers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B31/00—Rolling stand structures; Mounting, adjusting, or interchanging rolls, roll mountings, or stand frames
- B21B31/16—Adjusting or positioning rolls
- B21B31/20—Adjusting or positioning rolls by moving rolls perpendicularly to roll axis
- B21B31/32—Adjusting or positioning rolls by moving rolls perpendicularly to roll axis by liquid pressure, e.g. hydromechanical adjusting
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Control Of Metal Rolling (AREA)
Abstract
A rolling mill includes two horizontal rolls 1,2 downstream of which are two vertical rolls 32,33. A sensor 17 produces a signal indicative of the lateral position of the strip upstream of the horizontal rolls and a comparator 20 compares this signal with a signal indicative of the desired lateral position of the strip to produce a difference signal. Hydraulic cylinders 7 and 8 alter the roll gap at one or other end of the horizontal rolls in dependence on the difference signal to correct the lateral position of the strip. A sensor 37 downstream of the vertical rolls produces a signal indicative of the lateral position of the strip and a comparator 38 compares this signal with a signal indicative of the desired lateral position of the strip to produce a difference signal. Hydraulic cylinders 34,35 move the vertical rolls horizontally in dependence on the value of the difference signal to correct the camber of the strip. <IMAGE>
Description
SPECIFICATION
Strip rolling mills
The present invention relates to strip rolling mills and is concerned with a method and apparatus for controlling lateral unstable movement of a strip being rolled which can be applied to all those rolling mills such as hot strip mills, skin path mills, plate mills and cold mills which have the problem that lateral unstable movement of strips being rolled tends to occur. The present invention relates also to a method and apparatus for controlling the camber of a strip being rolled.
Under various rolling conditions, there is a tendency for the strip being rolled not to remain at the centre portions of the working rolls but to be forced towards one end of the working rolls as shown in
Figure 1. This phenomenon is referred to herein as "lateral unstable movement of the strip".
A typical known system for controlling lateral unstable movement of the strip being rolled employs load cells disposed on the work and drive sides of the work rolls (i.e., the sides remote from and close to the drive means for the rolls) respectively and arranged to measure the rolling loads. The lateral displacement of a strip being rolled is indirectly indicated by a difference between the output signals from the load cells. In response to the output signals from the load cells, the roll gaps on the work and drive sides of the rolls are adjusted so as to control the lateral unstable movement.
The system described above for controlling lateral displacement of the strip (hereinafter referred to as an automatic sterring control) is feasible in theory but cannot be realised in practice because the variations in the loads acting on the load cells are too small to be reliably measured; even though the variations to be measured vary from one rolling mill to another, variations of less than one tonne must generally be measured. Furthermore, the automatic steering control is adversely affected by external disturbances caused by the rolling operation itself.
More particularly, the difference in the rolling loads applied at the work and drive sides of the rolling mill is caused by the difference in hardness across the width of the strip being rolled, a difference in the thickness of the strip across its width and the amount by which the centre line of the strip is offset from that of the rolling mill and results in a difference between the roll gaps on the work and drive sides. As a result, the strip drawing velocity is faster on the side on which the roll gap is larger.
Therefore as shown in Figure 1,the strip entering between the working rolls is caused to incline at an angle with respect to the centre line of the rolling mill, that is to say, with rspect to the direction in which the strip is moved. The inclined strip a is advanced at right angles with respect to the axes of the working rolls b and is thus laterally displaced toward the side on which the roll gap is larger, i.e. is subject to lateral unstable movement. As a result the roll gap is increased further and the lateral displacement of the rolled strip is further promoted. The roll gap tends to have the shape shown in Figure 2. Once lateral unstable movement has started as described above, it becomes difficult to roll the strip in a stable manner.
When there is a difference in the roll gaps at the work and drive sides of the rolls (referred to as the right and left sides), a lateral displacement of the strip toward the side with the larger roll gap occurs.
Therefore the roll gap towards which the strip is displaced must be reduced.
A known automatic steering control based upon the principle described above will be described with reference to Figure 3 which is a diagrammatic illustration of a rolling mill with working rolls b and associated backup rolls j. Output signals from cylinder position sensors d and d' which are indicative of the positions of the pistons of hydraulic cylinders c and c' are detected and fed back to operational amplifiers e and e'. Servo valves f and f' are driven in response to the output signals from the operational amplifiers e and e' to adjust the positions of the right and left sides of the working rolls b, j. However, in this system, bending and deformation of the rolls due to lateral displacement of the strip being rolled themselves cause a difference between the roll gaps at the right and left sides of the rolls.This difference in the roll gaps cannot be remedied so that lateral unstable movement of the strip being rolled cannot be prevented. Therefore, the difference between the output signals from the load cells g and g' is obtained by means of an operational amplifier h and the feedback values are adjusted by means of a coeffiecient multiplier i. The output from the coefficient multiplier i is fed back to the operational amplifiers e and e' so that the roll gaps on the sides at which the load is increased and decreased can be reduced and increased, respectively. Thus, the coefficient multiplier i is suitably controlled so that the centre line of the strip being rolled is forced to coincide with the centre line of the rolling mill.
Although it would be thought that the system described above with reference to Figure 3 would be feasible it has in fact not been used in practice because the difference between the loads exerted on the right and left sides of the working rolls is too small to be reliably detected and the automatic steering control is adversely affected by external disturbances caused by the rolling operation. In addition, the system described above is not practicable for reasons which will be described below with reference to Figures 4A to 4C.
Figure 4A illustrates the loads or rolling forces PL and PR which are produced due to the lateral displacement of a strip a being rolled. If the loads are controlled such that the rolling force PR iS increased while the rolling force PL is decreased, the roll gap on the right side is reduced and the lateral displacement thus corrected. However, if the difference between the rolling force PR and PL is not sufficiently great, the roll gap is reduced as shown in Figure 4B but the lateral displacement is only partially corrected to some extent. However, the roll gap difference is frequently not sufficient to permit complete correction of the lateral displacement of the strip.On the other hand, if the difference between the rolling forces PR and PL becomes excessive, the roll gap can adopt a configuration which permits the movement of the strip towards the centre as shown in Figure 4C, that is to say, the strip is quickly displaced toward the left. Therefore, if the control system cannot respond quickly, the strip being rolled tends to be displaced too far to the left beyond the centre of the rolling mill. Then the strip is displaced back toward the right. Thus, the strip tends to move in a zig-zag manner. As a consequence, the roll gap must be so adjusted that the strip is prevented from being displaced too quickly to the right or left and thus overshooting the desired central position.
In a control system in which, in response to the difference between the right and left rolling forces, the difference between the right and left roll gaps is controlled and corrected to the desired values, the lateral displacement of the strip being rolled cannot be reliably controlled and if the roll gap difference becomes excessive, the control of the roll gap is adversely affected. Thus, the difference between the roll gaps at the two ends of the working rolls must be controlled in an appropriate manner. However, the most appropiate manner in which the roll gap should be corrected varies with the rolling parameters, such as strip width, strip thickness and strip material and the rolling velocity and there is no method for directly deriving the values of these parameters and altering the roll gap difference control accordingly.As a result, it is extremely difficult or impossible in practice to control the gap appropriately under all conditions.
The control system described above can be used experimentally under predetermined conditions but is not effective in practice.
As mentioned above, the present invention is concerned also with controlling and correcting the camber of a strip being rolled. The term camber is used herein to denote a curvature of the strip in its own plane. Referring again to Figure 1, if the strip moves a little to, say, the right, the roll gap becomes non-uniform, i.e. in this case greater at the right than the left. As referred to above the linear velocity of the periphery of the working roll bisthesameatthe right and left so that the volume of the material of the strip entering the right hand side of the gap between the working rolls b per unit time becomes greater than that entering the left hand side of the gap.When the strip a enters between the work rolls b, its cross section is initially uniform so that the right hand portion of the strip is drawn more rapidly into the gap between the working rolls b than the left hand portion ofthe strip. As shown in Figure 16, which is a diagrammatic plan view of the strip being rolled, the result is that as the strip material enters the gap between the working rolls b, it is forced to move toward the right by a distance Ax so that when the strip material leaves the working rolls, a camber
Ay is produced. As a consequence, the difference between the roll gap at the right and left hand sides is further increased so that the strip a is further forced to move to the right. As a result, a rapid lateral displacement of the strip occurs and the camber increases further.
Lateral unstable movement of the strip a and the resulting camber may be prevented by rolling the strip such that it has a positive crown. However, as a result of recently increasing demands for high quality and yield, it is desired that the positive crown be suppressed and the cross sections in both the lengthwise and widthwise directions be as uniform as possible. However, when a strip is rolled so as to atain these results, lateral unstable movement tends to occur very frequently and it is very difficult to achieve a stable rolling operation. Even if lateral unstable movement of the strip could be prevented, a camber is still produced because of nonsymmetrical variation in thickness of the incoming strip in the widthwise direction and an initial camber.
A camber also tends to be produced as a result of temperature differences across the width of the strip.
No satisfactory solution to these problems has yet been proposed. The only real possibiltyto date is that the strip is rolled with a width greater than that required and thereafter the undesired portions of the rolled strip are cut off so that a rolled strip with the desired plan shape (i.e. shape seen from above) is produced. However, the yield using such a method is considerably decreased.
It is an object of the present invention to provide a method and apparatus for controlling lateral unstable movement of strip being rolled which overcomes the problems encountered in the control system described above with reference to Figure 3, in particular the problem that the control system cannot be used in practice because the difference between the rolling forces cannot be directly correlated with the roll gap. It is thus an object of the invention to prevent lateral unstable movement of the strip being rolled, whereby interruption of the rolling operation can be prevented, damage of the edges of the strip can be avoided, fracture of the strip can be prevented, the yield can be improved, the rolling operation can be stabilised and the productivity of the rolling operation improved. It is a further object to control and correct the camber of the strip.
According to one aspect of the present invention there is provided a method of controlling lateral unstable movement of a strip being rolled in a rolling mill which comprises directly detecting a lateral displacement from a desired position of the strip entering between the working rolls and, in repsonse to the said detected lateral displacement, controlling roll gap control units and thereby changing the roll gaps at the two ends of the working rolls and thus restraining the lateral unstable movement of the strip. The method preferably includes additionally detecting the camber of the strip after it has passed through the work rolls by detecting a lateral displacement of the strip with respect to a desired position downstream oftheworking rolls and, in response to the said detected camber, moving rolls engaging the edges of the strip in a direction lying in the plane of the strip thereby correcting the said camber.
According to a further aspect of the present invention there is provided a method of controlling lateral unstable movement and the camber of a strip being rolled by passing it between two rolls whose axes are substantially horizontal and subsequently between two rolls whose axes are substantially vertical which method comprises deriving a signal indicative of the lateral displacement from a desired position of the strip entering between the horizontal rolls and changing the roll gap between the two ends of the horizontal rolls in response to the said lateral displacement signal, thereby controlling lateral unstable movement of the strip and deriving a signal indicative of the camber of the strip after passing between the horizontal rolls from a signal indicative of the lateral displacement from a desired position of the strip at a point downstream of the horizontal rolls and moving the vertical rolls in response to the signal indicative of the camber to correct the camber of the strip.
According to a still further aspect of the present invention a strip rolling mill includes two working rolls, lateral position sensor means disposed adjacent the working rolls for producing a signal indicative of the lateral position of the strip, set point setting means for producing a signal indicative of a desired lateral position of the strip, comparator means for comparing the signal from the lateral position sensor means with the signal from the set point setting means and for producing a difference signal, signal processing means for processing the difference signal from the comparator means so as to generate roll gap correction signals and means for changing the roll gap between the two ends of the working rolls in dependence on the roll gap correction signals.The rolling mill preferably further includes rolls positioned downstream of the working rolls, sensor means disposed downstream of the working rolls for producing a signal indicative of the lateral position of the strip, set point setting means for producing a signal indicative of a desired lateral position of the strip, comparator means for comparing the signal from the lateral position sensor means and the signal from the set point setting means and for producing a difference signal which is indicative of the camber of the strip, means for processing the signal indicative of the camber and generating a rolling position correction signal and means for moving the positions of the rolls downstream of the working rolls in dependence on the rolling position correction signal to exert a force on the strip in its own plane thereby correcting the camber.
According to yet a further aspect of the present invention a strip rolling mill includes two working rolls whose axes are substantially horizontal downstream of wchih are two rolls whose axes are substantially vertical, sensor means disposed upstream and downstream respectively of the horizontal rolls for detecting the lateral positions of the strip being rolled, means for comparing a signal derived from the sensor means disposed upstream of the horizonral rolls and a signal indicative of the desired lateral position to produce a difference signal, means for generating roll gap correction signals in dependence on the difference signal and means to adjust the roll gap between the two ends of the horizontal rolls in dependence on the roll gap co-rection signals, means for deriving a signal indicative of the camber of the strip by comparing the signal derived from the sensor means disposed downstream of the horizontal rolls with a signal indicative of the desired position, means for generating a rolling position correction signal in dependence on the signal indicative of the camber and means for adjusting the position of the vertical rolls in the direction of the width of the strip in dependence on the roll position correction signal.
In one embodiment of the invention the sensor means adjacent the working rolls comprise sensors for detecting the side edges of the strip in response to the light reflected from the strip. Alternatively the sensor means may comprise light sources disposed below or above the intended path of the strip and sensors disposed above or below the intended path of the strip in optically opposed relationship with the light sources for intercepting the light rays emitted from the light sources and thereby detecting the position of the side edges of the strip. The sensor means may also comprise pressure rolls disposed to contact the side edges of the strip and load sensors for detecting variations in the loads exerted on the pressure rolls when the strip is being rolled.Finally, the sensor means may also comprise pressure rolls movably disposed to contact the side edges of the strip and sensors for detecting variations in the positions of the pressure rolls.
Further features and details of the present inventin will be apparent from the following description of certain specific embodiments which is given by way of example with reference to Figures 5 to 15 of the accompanying drawings, in which;
Figure 5 is a perspective view of a first embodiment of the present invention;
Figure 6 illustrates a mechanism for detecting the lateral position of a strip being rolled;
Figure 7 is a perspective view of a second embodiment of the present invention;
Figure 8shows in detail a sensor used in the embodiment shown in Figure 7;
Figure 9 is a side elevation of a third embodiment of the present invention;
Figure 10 shows in detail a sensor used in the embodiment shown in Figure 9;
Figure 11 is a perspective view of a fourth embodiment of the present invention;
Figure 12 is a perspective view of a fifth embodiment of the present invention; ;
Figure 13 shows means which can be used as an alternative to the holding spiring used in the embodimentshown in Figure 12.
Figure 14 is a perspective view of a sixth embodiment of the present invetnion which also incorporates means for correcting the camber of the strip; and
Figure 75 is a plan view illustrating the principle of camber correction.
The same reference numerals are used to designate similar parts throughout the Figures.
The first embodiment shown in Figure 5 comprises a hydraulic reduction type rolling mill 10 comprising a pair of horizontal upper and lower working rolls 1 and 2, a pair of upper and lower backup rolls 3 and 4, lower backup roll chocks 5 and 6 which support the shaft of the lower backup roll 4 (other roll chocks being not shown) and hydraulic cylinders 7 and 8 for applying the rolling forces to the lower backup roll chocks 5 and 6, respectively. The first embodiment also includes servo valves 11 and 12 for controlling the volumes of working fluid, e.g. oil charged into or discharged from the hydraulic cylinders 7 and 8. The hydraulic cylinders 7 and 8 are provided with piston-displacement sensors 13 and 14, respectively, which detect the position of the pistons of the hydraulic cylinders 7 an 8.The output signals from the piston-displacement sensors 13 and 14 are compared with a reference signal in operational amplifiers 16 and 16. The left and right roll gaps, that is to say the gaps between the two ends of the working rolls, are controlled by controlling the volumes of working oil charged into or discharged from the hydraulic cylinders 7 and 8. Variations in the roll gap are indirectly detected by the pistondisplacement sensors 13 and 14 and the output signals from the displacement sensors 13 and 14 are compared with a reference signal in the operational amplifiers 15 and 16. In response to the difference signals between the output signals from the pistondisplacement sensors 13 and 14 and the reference signal, that is to say, in response to the output signals from the operational amplifiers 15 and 16, the servo valves 11 and 12 are controlled to adjust the roll gap.A strip lateral position sensor 17 is disposed upstream of the rolling mill to detect the lateral position of the strip 9 being rolled. The output signal from the sensor 17 is compared by an operational amplifier 20 with the output signal from a set-point setting circuit comprising a memory 18 and a relay 19 and the output signal 22 from the operational amplifier 20 is processed by a lateral displacement regulator 21. The output signals from the lateral displacement regulator 21 which constitute roll-gap adjustment signals 23 and 24 are applied to the operational amplifiers 15 and 16, respectively.
It is preferable that the strip lateral position sensor 17 be disposed as near as possible to the rolling mill 10 and atthe upstream side thereof because the lateral position detected by the sensor 17 disposed upstream of the rolling mill 10 would be different to that detected by a sensor disposed downstream of the rolling mill 10. As shown in Figure 6, when the strip 9 leaves the rolling mill 10, its lateral displacement uses a nonuniformity of the right and left roll gaps, resulting in a camber i.e. a curvature of the strip in its own plane, which can be defined by a hyberbolic curve B and which changes very rapidly.
The position sensor may be downstream of the rolling mill but in this event should be disposed as close as possible to the rolling mill and there is no improvement in the response. In addition, the time required for the strip to travel from the working rolls to the downstream lateral position is waste or dead time.
If there is no force exerted on the strip 9 to restrain it (for instance, if there is no guide which exerts a force on the strip or if there is no tension for pulling the strip upstream), the strip is displaced to the right or left due to the difference in elongation between the right and left sides of the strip (which results in lateral unstable movement thereof). Under these conditions then strip 9 is drawn between the upper and lower work rolls 1 and 2 and leaves them so that the lateral unstable movement occurs as described above. When the lateral position sensor 17 is disposed upstream of the rolling mill 10, not only the lateral position, but also the displacement ofthe strip due to the inclination thereof can be detected.
Referring now to Figure 6, the strip 9 is inclined at an angle 6 relative to the direction A in which it is moving due to the deflection thereof. On the upstream side of the rolling mill a displacement 3 of the strip immediately occurs due to the inclination 6 at a point spaced a distance f away from the roll axis. On the downstream side, the inclination is integrated in time and a camber or lateral displacement results.
As a result, as time elapses, the displacement is considerably decreased. Thus, on the downstream side of the rolling mill 10,thedeviation due to the inclination of the strip 9 cannot be detected and only the lateral movement due to the displacement of the strip on the upstream side of the rolling mill 10 can be detected.
The deviation due to the initial lateral displacement of the strip 9 on the upstream side of the rolling mill 10 has a tendency to increase with distance from the working rolls 1 and 2. It follows therefore that if the lateral position sensor 17 is disposed upstream ofthe rolling mill 10, lateral displacement which is succeeded by lateral movement of the strip 9 can be easily and immediately detected. As a consequence, the output signal from the lateral movement detector 17 can be used as a feedback signal which can be used to control the movement wih a better response.
In Figure 6, 3 designates an initial lateral displacement of the strip 9.
The output signal from the sensor 17 is compared by the operational amplifier 20 with the output from the set-point setting circuit 18, 19, as described above, and the output from the operational amplifier 20 is processed by the lateral displacement regulator 21. The output signals or roll-gap correction signals 23 and 24 from the lateral displacement-regulator 21 are applied to the operational amplifiers 15 and 16, respectively, of the roll-gap control system.
When the rolling operation is started, the relay 19 is turned off at a suitable time. The instantaneous value of the position of the strip is stored in the memory 18 and the output from the memory 18 is applied as a set point to the operational amplifier 20.
When lateral movement of the strip 9 starts, its lateral position is detected by the sensor 17 and the output from this sensor is compared with the set point value by the operational ampifier 20 as described above. The output signal 22 from the operational amplifier 20, which is indicative of the lateral displacement of the strip 9 is processed by the lateral displacement regulator 21. The lateral displacement regulator 21 may comprise an amplifier ora proportional gain circuitora proportional and differentiating circuit or a proportional, differentiating and integrating circuit. Thus the lateral displacement regulator 21 comprises a circuit whose type is selected depending upon the position ofthesensor 17, external disturbances and the like.The output signals from the lateral displacement regulator 21 are applied as the roll-gap correction signals 23 and 24 to the operational amplifiers 15 and 16 of the roll-gap control system. For instance, when the strip 9 is displaced toward the work side, the roll gap on the work side is reduced while the roll gap on the drive side is ncreased. On the other hand, when the strip 9 is displaced to the drive side, the signals are so applied that the roll gap on the work side is increased while the roll gap on the drive side is reduced.
In the operational amplifiers 15 and 16, the signals representative of the displacements of the pistons of the hydraulic cylinders 7 and 8 are compared with the roll-gap correction signals. The servo valves 11 and 12 control the volumes of oil charged into or discharged from the hydraulic cylinders 7 and 8 in response to the difference signals derived from the operational amplifiers 15 and 15. The size of the right and left roll gaps are thus corrected so that further lateral displacement of the strip is prevented and the strip is returned to the set point piston stored in the memory 18.
In the second embodiment shown in Figures 7 and 8 sensors 25 are disposed upstream of a hot rolling mill 10 and detect the light radiated by the hot strip 9 and thus detect the positions of the side edges of the strip 9. The difference between the outputs from the sensors 25, which represent the postion of both side edges of the strip 9, is derived in an operational amplifier 26 and compared in a comparator 28 with a set-point signal derived from a set-point signal setting unit 27.
As described above, the set point setting unit 27 generates a set-point signal which represents the initial lateral position of the strip 9 prior to passing between the upper and lower working rolls 1 and 2.
Alternatively the set-point setting unit 27 may be so constructed that the set point may be arbitrarily varied so that the strip 9 passes at any desired position in the widthwise direction of the rolling mill 10.
The construction of a sensor 25 is shown in Figure 8. The light radiated from the strip 9 is focussed through a lens 30 mounted in a lens barrel 29 on a sensor element group 31 consisting of a plurality of equispaced sensor elements to detect the position of one side edge of the strip 9.
N denotes the total number of sensor elements; L, the length of the field of view; and N', the number of sensor elements which receive the reflected light.
Then X = N' x h. The value of X varies with lateral movement of the strip so the position of the side edge of the strip 9 can be obtained by measuring the value of X.
The operational amplifiers 15 and 16 compare the signals indicative of the positions of the pistons of the hydraulic cylinders 7 and 8 with the roll-gap corrections signals 23, 24, respectively. The servo valves 11 and 12 control the volumes of oil charged into or discharged from the hydraulic cylinders 7 and 8 in response to the difference signals produced by the amplfiers 15 and 16. The right and left roll gaps are thus varied and further lateral movement of the strip is prevented in a manner similar to that described above. The strip 9 is also returned to the set determined by the set-point setting unit 27 as described above.
In the third embodiment ofthe present invention shown in Figures 9 and 10, reference numeral 32 designates the housing of the rolling mill 10; 33, a load cell for detecting a rolling load; and 34, a position sensor for detecting the position of the piston of the hydraulic cylinder 7 and thus, indirectly, variations in roll gap.
A light source 35 is disposed below the path of the strip 9 on the upstream side of the rolling mill 10 and two light sensors 36 are disposed above the path of the strip 9 so as to intercept the light emitted from the light source 35 at the work and drive sides, respectively, thereby detecting the position of the side edges of the strip 9. The output signal from the light sensors 36 are applied to a lateral movement operator 37 and the output signal representative of the lateral displacement Ax from the lateral movement operator 37 is applied to a lateral displacement controller 38. The output signal AG, which is a correction signal, from the lateral displacement controller 38 is applied as a right or left gap change signal to a hydraulic roll-gap control system 39.
The light sensors 36 intercept the light which is emitted from the light source 35 and which is not interurupted by the strip 9. Therefore signals indicative of the quantity of light received by each light sensor 36 are applied to the lateral movement operator 37 whose output signal, which is a function ofthe lateral diisplacement Ax, is applied as a lateral displacement signal to the lateral displacement controller 38.
The lateral controller 38 computes the roll gap change signal AG, which is a function of the displacement Ax by means of a proportional, differentiating of integrating circuit. The roll gap change signal thus obtained is applied to the hydraulic roll-gap control system 39.
In response to the roll gap change signal AG, the hydraulic roll-gap control system 39 controls the volumes of working fluid charged into or discharged from the hydraulic cylinders 7 and 8 and consequently the right and left roll gaps are changed. As a result, further lateral movement of the strip 9 can be prevented and the strip 9 returned to the set point position, as described above.
As described above, the roll gaps are changed in accordance with the lateral displacement of the strip.
For instance, if one assumes that the strip 9 is displaced to the left when viewed from the upstream side, then the left hydraulic cylinder 8 is so actuated that the roll gap is reduced while the right hydraulic cylinder 7 is so actuated that the roll gap is increased in response to the roll gap change signal. When the strip 9 has been displaced back to the right, when viewed from the upstream side, the left hydraulic cylinder 8 is so actuated that the roll gap is increased while the right hydraulic cylinder 7 is so actuated that the roll gap is reduced in response to the roll gap change signal.
In the fourth embodiment of the present invention shown in Figure 11, reference numerals 40 and 41 designate roll-gap control units; 42 and 43, holding or pressure rolls disposed at right and left sides of the strip 9 upstream of the rolling mill 10; 44 and 45, load cells for detecting the loads exerted on the pressure rolls 42 and 43; and 46, a lateral displacement controller which receives a difference signal 47 representative of the difference between the output signals from the load cells 44 and 45 and which applies control signals with opposite polarities to the roll-gap control units 40 and 41.
If one assumes that the strip 9 is displaced to the right with respect to the direction (indicated by the arrow) in which the strip 9 is moving, the loads FL and FR exerted on the pressure rolls 42 and 43 vary and the load FR exerted on the right pressure roll 43 increases. As described above, in response to the direcrion of the lateral movement of the strip, there exists a difference between the loads exerted on the right and left holding or pressure rolls 42 and 43. The operational amplifier 26 generates a signal representative of the difference between the loads FL and FR.
The difference signal 47 is applied to the controller 46 which in turn applies the control signals with opposite polarities to the roll gap control units 40 and 41, respectively. As a result, the right hydraulic cylinder 7 is so actuated that the right roll gap is reduced while the left hydraulic cylinder is so actuated that the left roll gap is increased. As a result, the lateral displacement of the strip 9 is corrected.
In the fifth embodiment of the present invention shown in Figure 12, reference numerals 48 and 49 denote sensors for detecting the displacement of holding or pressure rolls 42 and 43, respectively; and 50 and 51, holding springs disposed between the sensors and the pressure rolls. A difference signal 47 which represents the difference between the output signals from the sensors 48 and 49 is generated by the amplifier 26 and is applied to the controller 46, as in the case of the embodiment shown in Figure 11, and the controller 46 applies control signals with opposite polarities to the roll gap control units 40 and 41.
If one assumes that the strip 9 is displaced to the right with respect to the direction in which the strip 9 moves through the rolling mill 10, then the positions ofthe pressure rolls 42 and 43 are changed with respect to their normal desired position, i.e. the right pressure roll 43 is pushed backward by the strip 9 while the left pressure roll 42 is pushed forward underthe action of the holding or bias spring 50. The displacements of the pressure rolls 42 and 43 are detected by the sensors 48 and 49 and the difference between the output signals from the sensors 48 and 49 represents the lateral position of the strip 9, i.e.
whether the strip 9 is displaced to the right or left.
The difference signal 47 is applied to the controller 46 so that the lateral movement of the strip 9 is prevented or corrected in the manner described above with reference to Figure 11.
The sixth embodiment illustrated in Figure 14 includes means for controlling lateral unstable movement of the strip which is identical to that shown in Figure 5 (except that the set point setting circuit 18, 19 is also generally designated 25) and this will therefore not be described again. This embodiment also includes means for correcting the camber of the strip, which will now be described. Disposed on the downstream side ofthe horizontal rolling mill 10 is a vertical rolling mill which is generally indicated by reference numeral 36 and comprises vertical rolls 32 and 33 supported by vertical roll chocks 30 and 31, respectively, and hydraulic cylinders 34 and 35 and which enables the strip 9 to be rolled in the widthwise direction.A sensor 37 for detecting the lateral position of the strip (referred to herein as a camber sensor) is disposed on the downstream side of the vertical rolling mill 36 and the output from the sensor 37 is compared in an operational amplifier 38 with the output signal from the set-point determination circuit 25. The output signal 39 from the amplifier 38 is processed by a camber regulator 40 which derives an output signal 41 for correcting the positions of the left and right vertical rolls 32 and 33 which signal is applied to operational amplifiers 42 and 43 which control cylinders 34 and 35 acting on the rolls 32 and 33. The camber control system described above is substantially similar to the horizontal rolling mill control system and thus no detail is shown in Figure 14.
In use, the embodiment of Figure 14 controls lateral unstable movement as described with reference to the embodiment of Figure 5. With regard to the camber control the amplifier 38 calculates the difference between the output signal from the set point circuit 25 and the output from the camber sensor 37 (which detects the position of the strip 9 leaving the vertical rolling mill 36) and the output from the amplifier 38 is applied to the camber regulator 40.
The output from the camber regulator 40 is applied as a set point signal 41 for a vertical roll position control system (not shown) to the amplifiers 42 and 43 which in turn compare the pistondisplacement signals (not shown) from the cylinders 34 and 35 with the set-point signal 41 to produce a difference signal. In response to the difference signal, servo valves (not shown) are moved to vary the positions of the vertical rolls 32 and 33. Thus, the vertical rolls 32 and 33 are shifted by the same amount in the direction of the strip camber. In other words, the path which the strip follows is moved so that a bending moment M is exerted on the strip 9. In
Figure 15, the chain lines show the intitial situation; reference letter A denotes the direction of shift; C, the distance between the load points of the right and left vertical rolls; and P, the load force. The bending moment M is given by the equation
M
In the embodiment of Figure 14, the camber sensor is disposed downstream of the vertical rolling mill, but it will be understood that it may be interposed between the horizontal and vertical rolling mills 10 and 36. In addition, a plurality of camber sensors may be used. The camber sensor may also be of any of the alternative types referred to above and indeed may be of any appropriate contact or non-contact type.
The present invention has been described with reference to four-high rolling mills but it is to be understood that the present invention may equally be applied to any type of rolling mill which suffers from the problem of lateral unstable movement of the strip being rolled. It will also be understood that various modifications may be effected to the specific embodiments. For instance, the control circuit may be hardwired but may also be an appropriately programmed computer. The strip lateral position sensors may be disposed on both the upstream and downstream sides of the rolling mill. In the embodiment shown in Figure 9, a light source and associated light sensors may be disposed both at the upstream and downstream sides of the rolling mill and the light source may be disposed below the path of the strip.The lateral displacement regulator may comprise an amplifier or a proportional gain circuit, a proportional and differentiation circuit or a proportional, differentiation and integrating circuit depending upon the kinds of external disturbances which are expected. In the embodiment shown in Figures 11 and 12, the holding or pressure rolls 42 and 42 are described as disposed upstream of the rolling mill, but they may be disposed both upstream and downstream of the rolling mill. In the last embodiment shown in Figure 12, instead of the holding or bias springs 50 and 51 loaded between the holding or pressure rolls 42 and 43 and the sensors 48 and 49, an air cylinder 52 as shown in Figure 13 or a hydraulic cylinder or the combination of an air cylinder or a hydraulic cylinder with a spring may be used.It will be understood that, in practice, in addition to the position control systems, a mill modulus control circuit for measuring the rolling load by means of a load cell and computing the stretching of the mill, thereby compensating for or correcting the stretching may be provided. However, the mill modulus control circuit and the like are not shown in the accompanying drawings because they do not constitute part of the present invention.
Thus in the present invention, the lateral displacement of a strip adjacent the working roll, e.g. on the upstream side thereof, of a rolling mill is directly detected so that the difference between the right and left roll gaps is corrected for. As a result, lateral movement of the strip can be prevented so that the rolling operation can be carried out in a stable manner. As a consequence, the camber of the rolled strip can be reduced so that the yield of the rolling operation strips can be improved, accidents due to lateral, unstable movement of the strip being rolled can be prevented and consequently operational efficiency can be improved. It also becomes possible to roll a strip with less crown and consequently the yield can be improved and in one embodiment additional positive steps are taken to further reduce or eliminate the camber altogether.
Claims (15)
1. A method of controlling lateral unstable movement of a strip being rolled in a rolling mill which comprises directly detecting a lateral displacement from a desired position of the strip entering between the working rolls and, in response to the said detected lateral displacement, controlling roll gap control units and thereby changing the roll gaps at the two ends of the working rolls and thus restraining the lateral unstable movement of the strip.
2. A method as claimed in Claim 1 which includes additionally detecting the camber of the strip after it has passed through the work rolls by detecting a lateral displacement of the strip with respect to a desired position downstream of the working rolls and, in response to the said detected camber, moving rolls engaging the edges of the strip in a direction lying in the plane of the strip thereby correcting the said camber.
3. A method of controlling lateral unstable movement and the camber of a strip being rolled by passing it between two rolls whose axes are substantially horizontal and subsequently between two rolls whose axes are substantially vertical which method comprises deriving a signal indicative of the lateral displacement from a desired position of the strip entering between the horizontal rolls and changing the roll gap between the two ends of the horizontal rolls in response to the said lateral displacement signal, thereby controlling lateral unstable movement of the strip and deriving a signal indicative of the camber of the strip after passing between the horizontal rolls from a signal indicative of the lateral displacement from a desired position of the strip at a point downstream of the horizontal rolls and moving the vertical rolls in response to the signal indicative of the camber to correct the camber of the strip.
4. A method as claimed in any one of the preceding claims in which the lateral displacement of the strip entering between the rolls is detected upstream of the working rolls.
5. A strip rolling mill including two working rolls, lateral position sensor means disposed adjacent the working rolls for producing a signal indicative of the lateral position of the strip, set point setting means for producing a signal indicative of a desired lateral position of the strip, comparator means for comparing the signal from the lateral position sensor means with the signal from the set point setting means and for producing a difference signal, signal processing means for processing the difference signal from the comparator means so as to generate roll gap correction signals and means for changing the roll gap between the two ends of the working rolls in dependence on the roll gap correction signals.
6. A rolling mill as claimed in Claim 5 further including rolls positioned downstream ofthe working rolls, sensor means disposed downstream of the working rolls for producing a signal indicative of the lateral position of the strip, set point setting means for producing a signal indicative of a desired lateral position of the strip, comparator means for comparing the signal from the lateral position sensor means and the signal from the set point setting means and for producing a difference signal which is indicative of the camber of the strip, means for processing the signal indicative of the camber and generating a rolling position correction signal and means for moving the positions of the rolls downstream of the working rolls in dependence on the rolling position correction signal to exert a force on the strip in its own plane thereby correcting the camber.
7. A rolling mill as claimed in Claim 5 or Claim 6 in which the sensor means adjacent the working rolls are situated upstream of the working rolls.
8. A strip rolling mill incuding two working rolls whose axes are substantially horizontal downstream of which are two rolls whose axes are substantially vertical, sensor means disposed upstream and downstream respectively of the horizontal rolls for detecting the lateral positions of the strip being rolled, means for comparing a signal derived from the sensor means disposed upstream of the horizontal rolls and a signal indicative of the desired lateral position to produce a difference signal, means for generating roll gap correction signals in dependence on the difference signal and means to adjust the roll gap between the two ends of the horizontal rolls in dependence on the roll gap correction signals, means for deriving a signal indicative of the camber of the strip by comparing the signal derived from the sensor means disposed downstream of the horizontal rolls with a signal indicative of the desired position, means for generating a rolling position correction signal in dependence on the signal indicative of the camber and means for adjusting the position of the vertical rolls in the direction of the width of the strip in dependence on the roll position correction signal.
9. A rolling mill as claimed in Claim 8 in which the sensor means disposed upstream of the horizontal rolls are adjacent to the horizontal rolls.
10. A rolling mill as claimed in any one of Claims 5 to 7 and 9 in which the sensor means adjacent the working rolls comprises sensors for detecting the side edges of the strip in response to radiation radiated from the strip.
11. A rolling mill as claimed in any one of Claims 5 to 7 and 9 in which the sensor means adjacent the working rolls comprises light sources disposed below or above the intended path of the strip and sensors disposed above or below the intended path of the strip in optically opposed relationship with the light sources for intercepting the light rays emitted from the light sources and thereby detecting the position of the side edges of the strip.
12. A rolling mill as claimed in any one of Claims 5 to 7 and 9 in which the sensor means adjacent the working rolls comrpises pressure rolls disposed to contact the side edges of the strip and load sensors for detecting variations in the loads exerted on the pressure rolls when the strip is being rolled.
13. A rolling mill as claimed in any one of Claims 5 to 7 and 9 in which the sensor means adjacent the working rolls comprises pressure rolls movably disposed to contact the side edges of the strip and sensors for detecting variations in the positions of the pressure rolls.
14. A method of controlling lateral unstable movement of strip being rolled substantially as specifically herein described with reference to Figure 5 or Figures 7 and 8 or Figures 9 and 10 or Figure 11 or Figure 12 or Figure 14 of the accompanying drawings.
15. Astrip rolling mill including means for controlling lateral unstable movement of a strip being rolled substantially as specifically herein described with reference to Figure 5 or Figures 7 and 8 or
Figures 9 and 10 or Figure 11 or Figure 12 or Figure 14 of the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58064369A JPS59189011A (en) | 1983-04-12 | 1983-04-12 | Method and device for controlling meandering and lateral deviation of rolling material |
| JP58065109A JPS59191510A (en) | 1983-04-13 | 1983-04-13 | Method and device for controlling meander of rolling material |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8409394D0 GB8409394D0 (en) | 1984-05-23 |
| GB2138180A true GB2138180A (en) | 1984-10-17 |
| GB2138180B GB2138180B (en) | 1986-09-24 |
Family
ID=26405483
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08409394A Expired GB2138180B (en) | 1983-04-12 | 1984-04-11 | Strip rolling mills |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2138180B (en) |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0192982A2 (en) * | 1985-03-01 | 1986-09-03 | Sms Schloemann-Siemag Aktiengesellschaft | Apparatus for advancing rolled strip |
| EP0206453A1 (en) * | 1985-05-23 | 1986-12-30 | Ishikawajima-Harima Jukogyo Kabushiki Kaisha | Method of multi-pass rolling and rolling mill stand for carrying out the method |
| WO1990009249A1 (en) * | 1989-02-07 | 1990-08-23 | Davy Mckee (Poole) Limited | The measurement of shape of metal strip |
| WO1990010508A1 (en) * | 1989-03-14 | 1990-09-20 | Lothar Kehne | Roller, in particular for rolling mills and metallurgical plants |
| DE3933260A1 (en) * | 1989-02-04 | 1990-10-11 | Lothar Kehne | Roller, especially for rolling mills and steel works |
| WO1999012670A1 (en) * | 1997-09-11 | 1999-03-18 | Kvaerner Technology & Research Limited | Hot flat rolling mill stand and control method and apparatus therefor |
| EP0916417A2 (en) * | 1997-11-11 | 1999-05-19 | Mitsubishi Heavy Industries, Ltd. | Housingless rolling mill |
| EP1125658A1 (en) * | 2000-02-15 | 2001-08-22 | Danieli & C. Officine Meccaniche SpA | Method to control the axial position of slabs emerging from continuous casting and relative device |
| WO2007137649A1 (en) * | 2006-05-27 | 2007-12-06 | Sms Demag Ag | Device for measuring the width and/or the position of a metal strip or slab |
| CN102470412A (en) * | 2009-07-30 | 2012-05-23 | 西门子公司 | Method for controlling and/or regulating a location of a metal strip passing through a rolling mill, control and/or regulating device, and rolling mill |
| RU2769552C1 (en) * | 2018-07-25 | 2022-04-04 | Прайметалз Текнолоджиз Аустриа ГмбХ | Method and device for determining the lateral contour of the strip or the position of the edges of a moving metal strip |
| CN114453426A (en) * | 2022-01-06 | 2022-05-10 | 首钢京唐钢铁联合有限责任公司 | Method for adjusting rough rolling center line |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115159225A (en) * | 2022-06-30 | 2022-10-11 | 广西广盛新材料科技有限公司 | Roll gap deviation control method, roll gap deviation control device, computer and readable storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB992101A (en) * | 1963-11-12 | 1965-05-19 | Blaw Knox Co | Automatic strip threading device for a tandem mill assembly |
| GB2100475A (en) * | 1981-04-24 | 1982-12-22 | Betr Forsch Inst Angew Forsch | Apparatus to control the position of rolled strip during rolling |
-
1984
- 1984-04-11 GB GB08409394A patent/GB2138180B/en not_active Expired
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB992101A (en) * | 1963-11-12 | 1965-05-19 | Blaw Knox Co | Automatic strip threading device for a tandem mill assembly |
| GB2100475A (en) * | 1981-04-24 | 1982-12-22 | Betr Forsch Inst Angew Forsch | Apparatus to control the position of rolled strip during rolling |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0192982A2 (en) * | 1985-03-01 | 1986-09-03 | Sms Schloemann-Siemag Aktiengesellschaft | Apparatus for advancing rolled strip |
| EP0192982A3 (en) * | 1985-03-01 | 1989-03-29 | Sms Schloemann-Siemag Aktiengesellschaft | Apparatus for advancing rolled strip |
| EP0206453A1 (en) * | 1985-05-23 | 1986-12-30 | Ishikawajima-Harima Jukogyo Kabushiki Kaisha | Method of multi-pass rolling and rolling mill stand for carrying out the method |
| DE3933260A1 (en) * | 1989-02-04 | 1990-10-11 | Lothar Kehne | Roller, especially for rolling mills and steel works |
| WO1990009249A1 (en) * | 1989-02-07 | 1990-08-23 | Davy Mckee (Poole) Limited | The measurement of shape of metal strip |
| WO1990010508A1 (en) * | 1989-03-14 | 1990-09-20 | Lothar Kehne | Roller, in particular for rolling mills and metallurgical plants |
| WO1999012670A1 (en) * | 1997-09-11 | 1999-03-18 | Kvaerner Technology & Research Limited | Hot flat rolling mill stand and control method and apparatus therefor |
| EP0916417A3 (en) * | 1997-11-11 | 2001-05-02 | Mitsubishi Heavy Industries, Ltd. | Housingless rolling mill |
| EP0916417A2 (en) * | 1997-11-11 | 1999-05-19 | Mitsubishi Heavy Industries, Ltd. | Housingless rolling mill |
| EP1125658A1 (en) * | 2000-02-15 | 2001-08-22 | Danieli & C. Officine Meccaniche SpA | Method to control the axial position of slabs emerging from continuous casting and relative device |
| WO2007137649A1 (en) * | 2006-05-27 | 2007-12-06 | Sms Demag Ag | Device for measuring the width and/or the position of a metal strip or slab |
| JP2009539074A (en) * | 2006-05-27 | 2009-11-12 | エス・エム・エス・ジーマーク・アクチエンゲゼルシャフト | Device for measuring the width and / or position of a strip or slab |
| US8217377B2 (en) | 2006-05-27 | 2012-07-10 | Sms Siemag Aktiengesellschaft | Device with movable sensor for measuring the width and/or the position of a metal strip or slab |
| CN102470412A (en) * | 2009-07-30 | 2012-05-23 | 西门子公司 | Method for controlling and/or regulating a location of a metal strip passing through a rolling mill, control and/or regulating device, and rolling mill |
| RU2769552C1 (en) * | 2018-07-25 | 2022-04-04 | Прайметалз Текнолоджиз Аустриа ГмбХ | Method and device for determining the lateral contour of the strip or the position of the edges of a moving metal strip |
| US11975372B2 (en) | 2018-07-25 | 2024-05-07 | Primetals Technologies Austria GmbH | Method and device for ascertaining the lateral strip contour or the position of the strip edges of a running metal strip |
| CN114453426A (en) * | 2022-01-06 | 2022-05-10 | 首钢京唐钢铁联合有限责任公司 | Method for adjusting rough rolling center line |
| CN114453426B (en) * | 2022-01-06 | 2024-05-10 | 首钢京唐钢铁联合有限责任公司 | Method for adjusting rough rolling center line |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8409394D0 (en) | 1984-05-23 |
| GB2138180B (en) | 1986-09-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Effective date: 20040410 |