FR2521040A1 - Controlling profile of rolled prods. e.g. railway rails - where numerous sensors are used to monitor and adjust positions of profiled work rolls - Google Patents

Abstract

Roll stand contains at least two work rolls forming a gap through which a blank is fed to obtain a prod. with a cross-section which has a specific size and shape. To obtain an exact size and shape, the roll stand is equipped with numerous sensors or chains of sensors which monitor the actual positions of the roll shafts, the roll surfaces, and the progressive wear of the roll surfaces. The data obtd. from the sensors is used to adjust the actual positions of the rolls and their shafts during the rolling operation so that prods. with a cross-section possessing a constant size and shape are obtd. The control process occurs in real time.

Description

Method for regulating the size of a laminated profile, and rolling stand for implementing the method.

 The invention relates to a method for regulating the size of a profile rolled by the active parts of cylinders forming a groove.

 The problem of ensuring that the rolled product has the exact size set by the calibration, not only at the start of the rolling sequence, but throughout it, has so far not received a satisfactory solution.

Admittedly, it has been proposed (for example in French patents Nos. 2,389,837; 2,015,425; 2,130,181) devices for measuring the rolling interval of the mill stands, but these measurements, accounting only for the spacing of the cylinders and thereby integrating the cage deformation deformations do not allow
not achieve the desired gauge regularity.

 The object of the invention is a method of regulation which overcomes the drawbacks of the prior art and which makes it possible to give the wool profile in a groove formed by several cylinders at each determining stage of the rolling sequence the size value as close as possible to that fixed by the calibration and to keep it throughout the rolling period.

 This object is achieved, in accordance with the invention, by measuring the value of at least one displacement of the contour of the active parts in the pressure plane with respect to its predetermined position by the calibration and by modifying according to said value the position of the cylinders in a direction leading to the cancellation of the measured value.

By measuring the real displacement of the contour of the groove, the process integrates all the variables which result from the work of the rolls during rolling, namely
- the operating and stacking clearances of the various elements constituting the complete rolling mill stand
- the elongation, twisting, bending or compression of the cage elements (column, screw and nut, adjustment valves)
- the own bending of the cylinders and
- the wear of the groove and that of the bearings of the cylinders.

 The last two variables in particular were left aside in the regulation methods of the prior art and the laminator tried to ensure the regularity of the rolled product by introducing fictitious values of more or less arbitrary adjustment of the rolls in the rolling program.

 The invention ensuring a correction in real values, taking into account in particular the wear of the grooves, makes it possible to laminate a profile whose gauge deviations are reduced to the minimum.

 Naturally, depending on the shape of the groove, as many displacement measurements are carried out simultaneously as are necessary to account for and cancel the independent displacements of the different parts of the groove contour.

 Advantageously, the part of the table of the cylinder considered delimiting a part of the groove is taken as the source for measuring a displacement, in the portion of the cylinder diametrically opposite to the woolly portion. This way of proceeding makes it possible to assess the exact value of the displacement of the contour of the groove in the pressure plane, apart from the compression effect of the cylinder, an effect which is quite negligible.

Indeed, it is commonly accepted - that the yielding effect of the elements of a cage is measured
in millimeters - 3 to 5 mm; - that the wear effect of the cylinder is measured in 1/100 of
millimeters
0.5 to 0.8 mm - as the compression effect of the cylinder while it remains
in the area of elastic deformation is measured in
microns
0.003 to 0.008 mm
Advantageously, the value of an actual displacement of the contour is measured by measuring at each pass, using a sensor, the distance from the portion of the cylinder table diametrically opposite to the rolling portion, on the one hand to empty and on the other hand in charge
Advantageously, the value of a die is measured
actual placement of the contour by means of a heading chain
position sensors whose sensors are linked to
static or dynamic elements of the cage likely
movement, except the end sensor
upstream which is isolated from such movement, each sensor
recording the relative movement of the sensor which comes
immediately downstream except the downstream end sensor
which measures the relative displacement of the groove outline.

This chain or cascade of sensors includes
as many sensors as necessary to be able to com
moderately move from the mobile benchmark that constitutes in gen-
ral the downstream sensor to the fixed mark which constitutes the
upstream sensor. Naturally, if it is possible to
place the downstream sensor, recording movements
of the contour, in fixed reference, the sensor chain is
reduced to this single downstream sensor, isolated from the movement of
static or dynamic elements of the cage.

Advantageously, the position of the
cylinders as soon as their deviation from the groove contour
with its predetermined position is above a threshold
given, depending on the quality desired for the finished product.

 The position of the cylinders is modified in delayed action or, preferably, in punctual or continuous direct action, using auxiliary members such as jacks, wedges, screws and nuts and the like, and / or main members if these these are quite powerful.

 The invention makes it possible to ensure the product rolled at the final pass a regularity close to that determined by the calibration, roughing, roughing and intermediate, so that the finishing pass is the ideal size of the nominal profile, this ensuring so continues a correction of the settings of the rolls subjected to the rolling force in the different cages of the train.

 The application of the corrections takes place after pass up to and including the finishing pass, this no longer has to undergo the excess or iron deficiencies of random variations given to the profile during passes not in accordance with the calibration .

 The invention also relates to a rolling mill stand for implementing the aforementioned method comprising cylinders defining a groove, and means for modifying the position of said cylinders, equipped with at least one position sensor measuring a displacement of the contour of the groove. and functionally connected to the control of the means for modifying the position of the cylinders.

The invention therefore exercises both
a) An action to preserve the geometry of the stand to maintain the practical rolling axis on the theoretical axis.

 b) An action to correct the calibration values aberrated by wear, or by the variation in resistance of the product itself due to temperature differences along the blank (head, middle, foot) originating from both reheating , of the end effect, that of the drift by heating of the various elements constituting the train of rolling mills during rolling.

The invention will be better understood from the description which follows, given with reference to the accompanying drawings in which
- Figure 1 shows the arrangement of sensors according to the invention in the case of universal rolling of a rail;
- Figures 2, 3 and 4 show three alternative arrangements of a chain of sensors mounted in series to control the position of a vertical roller;
- Figure 5 shows the different parameters measured and calculated for the control of the position of a horizontal cylinder;
- Figures 6 and 7 show two variants of a circuit for correcting the position of a horizontal cylinder.

 Figure 1 shows the arrangement of the sensors in the case of the rail. All the sensors shown are fixed individual sensors, for simplicity, but it is understood that they may, in whole or in part, be replaced by chains of sensors.

These sensors are of known type (presence, proximity, contact, potentiometric, etc.).

 The rail 1 is laminated by the upper 2 and lower 3 horizontal cylinders, and the vertical skate 4 and mushroom 5 rollers.

 The lateral (or axial) positioning of the horizontal rolls 2 and 3 is controlled respectively by the sensors 6 and 7 measuring the distance B variable according to the axial displacements of the axes 8 and 9 of the rolls 2 and 3. The geometry of the vertical rolling plane ( trace 19) is ensured by the action of sensors 6 and 7 on the lateral positioning of the cylinders.

 The positioning of the vertical rollers 4 and 5 is controlled respectively by the sensors 10 and 11 which measure the distance B + b taking account of the play at the start B and the wear b (represented in hatched parts on the rollers and rollers).

In addition, sensors 12 and 13 control the distance B + b from the jointing surfaces, respectively upper and lower on the shoe side, while sensors
14 and 15 check the distance of the jointing surfaces
upper and lower respectively, mushroom side.

 The sensors 10, 12 and 13 act on the positioning of the shoe roller 4 to maintain a correct shoe thickness.

 Similarly, the sensors 11, 14 and 15 act on the positioning of the mushroom roller 5 to keep the correct thickness of the mushroom.

 The vertical positioning of the horizontal cylinders 2 and 3 is controlled by the sensors 16 and 17 respectively, the action of said sensors on the vertical positioning of the cylinders ensures the geometry of the horizontal rolling plane (of trace 18).

 The combined action of sensors 6,7 and 16,17 therefore allows the control of the theoretical rolling axis.

 Furthermore, the respective action of the sensors 16 and 17 on the vertical positioning of the horizontal cylinders makes it possible to maintain a correct core thickness.

 Naturally, the lateral positioning of the horizontal cylinders, in response to the indications of the sensors 6 and 7, takes priority to give its fair value to the positioning of the vertical rollers, in response to the indications of the sensors 10 and 11, and then give perfect positioning accuracy vertical of the horizontal cylinders, in response to the indications of sensors 16 and 17.

I1 will be observed that the sensors shown observe the displacement of the cylinder (or roller) contour which they control, on the portion diametrically opposite to the rolling portion (that is to say on the portion axially symmetrical to the rolling portion)
In the practice of rolling the rail, one can be content to place the sensors on the parts of cylinders (or rollers) which wear out the most: this is how one can omit the sensors 14 and 15 while neglecting the wear of the laminating portion of the joint parts on the mushroom side.

 The displacements of the cylinders and rollers can be carried out as follows.

 With regard to the correction of the horizontal cylinders 2, 3, the vertical clamping movement is ensured on at least one cylinder by a system of screws and nuts (cf. also 36, fig. 6) therefore the action is controlled by a motor-reducer assembly (35, fig. 6) programmed.

i1 just enter the measured values
B + b in the program (see below) to have the necessary correction specific to a given pass, by action on the main motor (35, fig. 6) or on the auxiliary motor (38, fig. 7).

The axial (or lateral) positioning movement can be ensured by the movement of the locking system itself relative to the amounts of the cage (screw-nut, jack, conical double wedges, driven by mechanical, electromechanical or hydraulic action )
With regard to the correction of the vertical rollers 4, 5, the horizontal tightening movement of the rollers is effected by an action of the control motor acting on the roller holders by means of screws and nuts (cf. fig. 2 to 4) or cylinder.

 The correction is made by modifying the action of the main motor or, if an auxiliary movement has been placed in series (for example conical corners, hydraulic cylinders, etc.) on the control of this auxiliary movement.

 Figures 2, 3, 4 schematically represent three embodiments of sensor chains, in the case of the detection of the displacement of a vertical roller, such as the roller 4 for example.

 In FIG. 2, the sensor 20 fixed on the roller holder 21 measures the relative movement B1 of the roller 4 relative to the roller holder. The roller holder 21 is moved by a screw 22 rotating in the nut 23, retained by the nut holder 24 secured to the cage 25. Upstream of the sensor chain, a sensor 27 independent of the cage measures the displacement B4 of the nut holder 24. A measuring square 26 whose foot is linked to the end of the screw 22 makes it possible to know, thanks to a sensor 28, (in the case of potentiometric sensors, a plurality of plunger cores 28, crossing the coil not referenced, can be provided if the magnitude of the displacements of the screw 22 l requires) the displacement B3 of the screw 22 relative to the nut holder 24. A sensor 29 linked to the roller carrier 21 measures the displacement B2 of the carrier relative to the end of the screw 22. The sum of the indications of the sensors 20 , 29, 28, 27 allows to know the value of the absolute displacement of the roller 4.

 According to the assembly of FIG. 3, the screw 22 ′ turns in a nut 23 ’which is fixed to the roller carrier 21.

The foot of the bracket 26 'is directly integral with the roller carrier 21; the sensors 28 ′ of the bracket 26 ′ pick up its position relative to the support 30 of screws secured to the cage. The sensor chain 20, 28 ′ ends upstream by the sensor 31 measuring the absolute displacement B3 of the support 30.

 mounting of fig. 4, even simpler, provides that the measuring bracket 26 'is integral with the roller carrier 21, and that the displacement B2 of the bracket (therefore of the roller carrier) is measured in an absolute manner by the sensor 28' ( the coil through which the square crosses is therefore in fixed reference).

 The principle of the measurements and the corrections will now be explained in detail by taking for example a horizontal cylinder 2 whose vertical displacement is controlled by a sensor 16. On the same i eme figure 5, are represented, during the n pass on the left , on the one hand the cylinder 2 'empty and, on the right, the same cylinder 2 "under load. The doubly hatched parts represent the wear b of the cylinder, in the ith pass-n th pass.

If xn represents the programmed position of the tightening screws of the axis 8 ', 8 "of the cylinder 2', 2" at the pass n (see also figures 6, 7), P the distance
n programmed from the cylinder axis to the rolling plane,
E the programmed spacing of the contour of the vacuum cylinder
n in the rolling plan, we have, for each pass, the relations
X 5 E - E and P = P - X
where E and P are the reference values established at dice
oo purpose of rolling.

 In principle, the theoretical calibration program makes it possible to establish the rolling sequence.

 This results in the reference of the values originally measured by the vacuum sensor and in the setting position.

A values (reference values)
n (fig. 5) are stored and cannot change once the position of the cylinders, defined by their controlled movement, is set to the original reference.

All the corrections, which will take place, are added to the order of the theoretical program taken at the output of the memory
10) To establish the operational program.

 20) To correct the values at the nth pass of the nth sequence in the case of direct control or that of the nth pass of the (m +1) th sequence in the case of the deferred or delayed command.

 The measurements recorded by the sensor each phase of the no-load sequence (A'n) as under load (A "n) are compared with the values referenced in the theoretical or operational memory as the case may be.

We notice that the value b which symbolizes
n 1 wear of the cylinder groove is known by comparing the no-load values A n and A '
not
bt A '- A
nnn
A 'values are measured by the heading
vacuum in the rolling intervals.

The wear value b for a donation pass
born from a given sequence, does not change, whether the cylinders are empty or loaded.

The values A "n are measured by the heading
loaded while the bar is engaged in the cylinders.

th
Measure A "n at pass n of the same sequence will be compared to measure A of reference.

not
By principle of construction of the sensor system on the cage, we have
- for reference values
(1) An + D + At C, where D is the diameter of the unworn cylinder
- for empty values
(2) A'n + D '+ E' = C
nn where D is the diameter of the worn cylinder
- for loaded values
(3) A "n + D '+ E" n = C, where C is the same constant for the three relations.

With D = D '+ 2 b and E' = E + b
nnnn the correction to be made is
= = E "- E
nnn
Operation (1) - (2) gives
b = A '- A
nnn
and (1) - (3) gives a = A - A "+ 2 b
nnnn therefore A = 2 A '- A "- A
nnnn
In the case of instantaneous An correction
n continuous or punctual in the passes of the same sequence, as in the case of correction #n deferred to the
n (m + l) th sequence has an interest in keeping the value cor
i th rigée of the n pass of the (ml) sequence in the operational program to the engagement of the bar to the n th pass to the m th sequence to avoid too sudden transitions of the rolling conditions from one sequence to another . This procedure allows a gradual tightening of the gaps while preventing adjustment drift.

The complex phenomenon of the variation in position of the contour of the groove of the cylinder moving relative to the theoretical rolling axis
on the one hand, under the instantaneous effect due to the load on the cylinder at 11 engagement and during the pass to that of the possible variations of this load,
- and on the other hand, under the slow and progressive effect of cylinder wear during rolling, can therefore be measured with the same sensor
10) by an empty measurement (rest time of the cylinders between passes) which allows to take into account the phenomenon of wear
2 ") and by measuring the displacement under the load, which is carried out with the bar engaged.

For each sensor or measurement chain, there are therefore three types of measurement
10) The measurements at the cage adjustment stage and search for the reference. The rolls are placed geometrically at a known reference value chosen with respect to the rolling axis.

This adjustment being made, the sensors are "calibrated" and give the measurement of the A values (origin)
not
20) The empty measurements during rolling for each pass and applying the "theoretical" or "operational"program; the sensors measure during the free time of the cylinders the values A 'represented
wear and tear (only).

30) The measurements under load during rolling for each pass and at each sequence the sensors measure under load during the working time of the cylinders the values A "n representative of the yielding and
n of wear.

 FIG. 6 represents the diagram of a correction circuit on the main control members.

The sensor 16 allows 11 recording in 32 of the different distances A (reference), A '(empty), A "(in
nnn charge) of cylinder 2. From these values, a computer 33 calculates the correction #n to be added at the operational programming level 34 to the displacement displacement value Xn 36 given by theoretical programming 37. The screws 36 are driven by the motor 35 controlled by the operational program 34.

 According to FIG. 7> auxiliary organs have been provided (auxiliary motor 38 and auxiliary jack 39 at the end of the screw 36) to carry out the correction displacement An ordered by the operational program 34.

Claims (11)

1. Method for regulating the size of a profile laminated by the active parts of cylinders forming a groove, characterized in that the value of at least one real displacement (An) of the contour of the active parts in the pressure plane with respect to its predetermined position by calibration and the position of the cylinders is changed as a function of said value in a direction leading to the cancellation of the measured value. 2. Method according to claim 1, characterized in that the value of an actual displacement (an) of the contour is measured on the portion of the table of each cylinder diametrically opposite to the rolling portion. 3. Method according to claim 2, characterized in that the value of a real displacement tAn) of the contour is measured by measuring with each pass using a sensor the distance from the portion of the cylinder table diametrically opposite the rolling portion, on the one hand empty (A'n) and, on the other hand, loaded (A ") 4. Method according to any one of claims 1 to 3, characterized in that the value of an actual displacement (An) of the contour is measured by means of a  n position sensor chain (20,29,28,27), the sensors of which are linked to static or dynamic elements of the cage capable of movement, with the exception of the upstream end sensor (27) which is isolated from such a movement, each sensor recording the relative movement of the sensor which comes immediately downstream, except the downstream end sensor (20) which measures the relative movement of the groove contour. 5. Method according to claim 4, characterized in that the sensor chain is reduced to a sensor isolated from the movement of static or dynamic elements of the cage. 6. Method according to any one of claims 1 to 5, characterized in that the position of the cylinders is changed as soon as their deviation from the groove contour with its predetermined position is greater than a given threshold. 7. Method according to any one of claims 1 to 6, characterized in that the position of the cylinders is modified in instantaneous punctual or continuous action. 8. Method according to claim 7, characterized in that the position of the cylinders is modified by means of auxiliary members (38, 39), such as jacks, wedges, screws and nuts and the like. 9. Method according to claim 7, characterized in that the position of the cylinders is modified using main members (35, 36). 10. Method according to any one of claims 1 to 6, characterized in that the position of the cylinders in delayed action is modified. 11. Rolling stand comprising rolls (2) defining a groove and means (35, 36, 38, 39) for modifying the position of said rolls, characterized in that it is equipped with at least one sensor (16) position measuring a displacement of the groove contour and functionally connected to the control (34) of the means for modifying the position of the cylinders.