EP0227870A1 - Automatically controlled machine for rolling metal sheets - Google Patents

Abstract

The machine with automatic control for rolling the sheets comprising at least two central rollers (1, 2) suitably driven, adjustable in height and able to be moved axially to allow the finished object to be released is characterized in that in combination with these rollers central rollers (1, 2) are placed, in a manner known per se, lateral rollers (21, 22) which can be positioned in space using jacks (23, 24), this positioning being permanently recorded by sensors (40 a , 40 b , 41 a , 41 b ) working in connection with a computer (50) and feelers (30 a , 30 b ) constituted by jacks with each rod at its upper part, rollers (33, 34) so as to obtain the position of these probes by means of digital or analog sensors (35 a , 35 b ) giving information compared with the instructions coming from the computer in order to correctly position the lateral rollers (21, 22 ) to roll the sheet to the radius provided in u no tolerance given, to calibrate the defects inherent in the sheet to a given value or to roll cones if necessary.

Description

There are already machines for rolling very thick sheets, in particular for shipbuilding, which are generally equipped with four cylindrical rollers.

Two of the rollers, called central rollers, are located in a vertical plane and pinch the sheet metal to be rolled with an effort that can be metered. One of these rollers is movable relative to the other in the vertical plane by means of two jacks which move it so that the generatrices of the upper and lower rollers are parallel. The hydraulic supply pressure of the cylinders can vary and allows the metering of the clamping force. This arrangement constitutes the equivalent of recessing on the sheet.

In addition, pinching allows the sheet metal to be driven along its length and in the horizontal plane by friction, the two lower and upper central rollers being equipped with a means of rotation, for example an electric, hydraulic or other motor.

Two other rollers, commonly called side rollers, are arranged symmetrically on either side of the central rollers. They are movable in an oblique direction relative to the plane passing through the axes of the two central rollers.

Two groups of hydraulic cylinders are hitched each by means of lateral rollers and make it possible to position them in space separately at altitude relative to the pair of central rollers.

Of course, the above-described assembly of the four rollers is included in a support frame which has all the slides necessary for the movement of the central and lateral rollers.

In addition, the frame is equipped with a lateral tilting bearing articulated around an operating axis by a jack. This set of tilting bearings is located in the axis of a frame and allows the sliding bearing to be released from the upper central roller so as to be able to serve, in all of the above four rollers, a fully closed rolled sheet.

In current practice, the adjustment of the machine and, in particular, the position of the lateral roller ensuring the obtaining of a theoretical radius of the sheet, are controlled manually by an operator who, despite his experience, does not get a job satisfactory only after a long time of work. Consequently, the cost price is extremely high. This is also due to the fact that the non-homogeneities of the metal to be bent, the differences in sheet thickness due to rolling errors, the modification of the characteristics of the metal during bending, the fact that we work beyond of the elastic limit of the material, make, on the one hand, that the radius actually obtained is not that ordered and, on the other hand, that one very often notes a really important evolution, evolution that the we can qualify deviations between a maximum radius and a minimum radius actually connected and that thus it is necessary to make up for these errors by numerous lateral passes carried out at low speed of the machine with, however, a final result which would be tainted by faults not negligible.

This state of the prior art shows an insufficient quality of work of the machine despite the intervention of a highly qualified specialist.

It therefore appeared necessary to remedy these drawbacks major due to the very strict specifications recently appeared for shipbuilding.

The object of the present invention is therefore to make the control of the machine practically automatic so that, from the digital data, one obtains parts machined correctly, whatever the defects of the material and whatever the desired shape can be cylindrical or frustoconical, of the sheet thus worked.

According to the invention, the machine with automatic control for rolling the sheets comprising at least two suitably driven central rollers, adjustable in height and able to be moved axially to allow the finished object to be released is characterized in that in combination with these central rollers are placed, in a manner known per se, lateral rollers which can be positioned in space using cylinders, this positioning being permanently recorded by sensors working in connection with a computer and probes constituted by cylinders each rod of which is provided, at its upper part, with rollers so as to obtain the position of these probes by means of digital or analog sensors giving information compared with the instructions coming from the computer in order to correctly position the lateral rollers for rolling the sheet metal at the radius provided within a given tolerance, to calibrate the defects inherent in the sheet metal at a given value o u roll cones if necessary.

According to another characteristic of the invention, one of the central rollers (lower roller) is mounted in bearings which can slide vertically under the action of jacks to obtain a constant and uniform force from the instructions produced by the computer.

Various other characteristics of the invention will also emerge from the detailed description which follows.

• La fig. 1 est une élévation, partie en coupe schématique, des passes de la machine.
• La fig. 2 est une coupe suivant la ligne II-II de la fig. 1.
• La fig. 3 est un schéma de la commande automatique de la machine.

An embodiment of the object of the invention is shown, by way of nonlimiting example, in the accompanying drawing.

• Fig. 1 is an elevation, partly in schematic section, of the machine passes.
• Fig. 2 is a section along line II-II of FIG. 1.
• Fig. 3 is a diagram of the automatic control of the machine.

In fig. 1, which is a very schematic partial section along the line I-I of FIG. 2, there is shown the two central rollers 1, 2, the roller 1 said upper and the roller 2 said lower. The upper roller 1 is mounted in bearings 3, 4 which are integral with the frame, not shown, of the machine and calculated so as to withstand the forces to which the upper roller is subjected voluntarily.

As can be seen in fig. 2, it is possible, using the double-acting cylinder 5, to adjust the position of the bearing 4 for operations which will be described below.

The upper roller is mounted on a drive shaft 6, the ends of which rest in the bearings 3 and 4.

In addition, one of the ends of the drive shaft 6 carries a member 7 for connecting the shaft 6 to a motor element. The lower roller 2 rests, via the shaft 8, in bearings 9, 10 which are supported by the rods 11, 12 of the double-acting cylinders 13, 14 secured to the frame of the machine. Thus, it is possible to use, vertically by means of the bearings 9, 10 and of the shaft 8, the lower roller 2.

As in the present case, it is sometimes possible to drive the lower roller 2 using the jack 14.

In addition, a double-acting cylinder 15, placed on the lateral side of the machine frame and articulated on it, has an axis 16 which allows, by its cylinder rod 15 a , to move, using an axis 17, the bearing 3 so as to release the upper roller 1 and bring it into a position allowing extraction when the work passes are finished in the ring produced using the sheet 20.

The above description indicates that the central rollers 1 and 2, located in the same vertical plane, pinch the sheet 20 to roll with an effort that can be measured since this effort is a function of the pressure of the rods cylinder 11, 12 which move the lower central roller 2 so that the generators of these rollers are always parallel. The hydraulic supply pressure of the double-acting cylinders 13, 14 can vary easily and therefore allows the metering of the clamping force of the sheet 20 to be metered. In addition, the clamping thus obtained allows the drive of the sheet 20 according to its length and in a horizontal plane by friction between the two lower central rollers 2 and upper 1 because these, as has already been indicated, are equipped with rotation means, such as electric, hydraulic or other motors.

The machine also has and as shown in fig. 1 two side rollers 21, 22 which are arranged symmetrically on either side of the central rollers 1, 2. the side rollers 21, 22 are movable in an oblique direction relative to the plane presented by the axes of the two central rollers like this is perfectly visible in fig. 1.

Two pairs of hydraulic cylinders 23, 24 (only one of the cylinders of each pair is shown in fig. 1) each coupled to the bearing of one of the lateral rollers 21, 22 allow these rollers to be positioned in parallel with respect to the torque of the central rollers 1, 2. The set of four rollers 1, 2, 21, 22 is, as already indicated, inscribed in an upper frame, part 25 of which is shown in FIG. 2, this support frame being equipped with the slides necessary for the movement of the rollers 1, 2, 21, 22 under the effect of the jacks 13, 14, 23, 24.

As already indicated, this frame is, moreover, equipped with a tilting bearing 3 (see fig. 1) articulated around an axis 25 and maneuvered by the double-acting cylinder 15. This set of tilting bearings is located in the axis of the frame, it allows to release the sliding bearing 6 is accommodated in the pivot bearing 3 of the upper roll 1 in order to go out of all the central rollers 1, 2, a rolled sheet metal, completely closed. The double-acting cylinder 5 of the bearing 4 fixed to the one end 5a to the frame of the machine, allows to tilt the entire upper central roller 1 about an axis 26 shown schematically in fig. 2, in order to facilitate the release operation of a closed rolled sheet, after the bearing 3 has been tilted by the jack 15. The end bearings of each of the central rollers 1, 2 are sliding and fitted with ball joints, this which optionally allows them to tilt relative to the horizontal.

The pinched sheet 20 between the central rollers 1, 2 is folded by means of any of the side rollers 21, 22 which are pushed by the pairs of jacks 23, 24. The pushing force F1 (see fig. 1) lateral rollers used, in this case the roller 21, generated by means of these actuating cylinders creates a bending moment whose value is Fxd and therefore folds the sheet 20 to the embedding of the central rollers 1,2. The opposite rotation of the two central rollers 1,2 which pinch the sheet 20 drives the sheet in a determined direction.

After folding, keeping the side roller used in position (roller 21) associated with the rotation of the two central rollers 1, 2 makes it possible to obtain a theoretical rolling radius R, a function of the position x of the side roller 21.

As already indicated, the lateral position of the roller 21 ensuring that the theoretical radius is obtained is currently controlled by the operator.

However, the non-homogeneities of the metal to be bent, the differences in sheet thickness due to rolling errors, the modification of the characteristics of the metal during bending, the fact that one works beyond the elastic limit of the material make, on the one hand, that the radius actually obtained is not that ordered and, on the other hand, that one notes a relatively important ovalization (difference between maximum radius and minimum radius actually rolled) that it is necessary to catch up with numerous local "passes", carried out at low speed.

The final result, however, remains marred by significant flaws.

The originality of the proposed automatically controlled rolling system consists in using probes 30 a , 30 b fixed on the frame not shown and located on either side of the lower central roller 2 for example between this central roller 2 and the rollers side 21, 22. It is of course possible to use several probes 30 a and 30 b arranged along the width of the sheet to be rolled.

To simplify, the description will be made with a single probe 30 a and a single 30 b located at half the width of the sheet. These feelers are constituted for example by jacks 31, 32 with hydraulic control equipped with a roller 33, 34 at the end of the rod. The cylinders can be moved up or down, either to put their end caster mite in contact with the outside of the sheet, either to be erased.

Their altitude position is recorded by means of sensors (digital or analog) 35 a , 35 b .

when the rollers 33, 34 are in contact with the sheet 20 the oil pressure is maintained in the "fitting" direction so that the roller 33 or 34 remains in contact with the sheet 20 at all times whatever the irregularities (bumps, hollow, runout) of the sheet 20.

The contact force of the rollers 33, 34 on the sheet 20 is calculated so that the resulting deformation of the sheet is negligible (a few kilos).

The first rolling pass is carried out with a position X₁ of fixed side roller 21 corresponding to a given radius R₁, this radius being larger than the final radius R _r to be obtained. the probes 30 a , 30 b are then deleted.

Once this pass has been made, the lateral roller used is released so as to release the curved sheet metal, the latter however remaining pinched between the central rollers 1, 2. The two feelers 30 a and 30 b are then brought into contact with the outer face of the sheet, and it is scrolled by means of drive motors 7, 14. Just as at any position X of the lateral roller corresponds to a theoretical radius R _t , to any dimension z of the probe corresponds to a radius R _r real (since the sheet 20 is no longer subjected to stress). Under these conditions, the value of the instantaneous bending radius R _i is recorded over the entire length of the sheet.

The deviations of R _i from the controlled bending radius are calculated from their measurement and stored and will be used in the future pass to control the position x₂ of the (or) side rollers 21 and 22 so as to reduce or eliminate the geometry deviations recorded.

For the next pass, a new position x₂ of the lateral roller considered is therefore determined to obtain a new theoretical radius R₂, <R₁. The deviations corresponding to the values memorized during the first pass by means of the sensors, weighted by a certain coefficient, are added at any time while the sheet is running, at the value of x₂ thus established. The second pass is performed by controlling the position of the lateral roller and a new reading of the real profile is made by the sensors. The instantaneous deviations are again recorded which will serve to correct the position of the roller during the third pass and so on until the final radius is obtained.

• 1) à chacun des rouleaux 21 et 22 sont respectivement asso­ciés deux capteurs 40a, 40b et 41a, 41b qui représentent la position x de chacun des rouleaux 21, 22. Cette disposition permet d'obtenir de façon précise l'horizontalité des rouleaux;
• 2) en fonction des données géométriques de la machine et du numéro n de la passe à réaliser, un calculateur numérique 50 (fig. 3) calcule le rayon théorique R_n à obtenir. Ce calcul est effectué selon une loi dite "de convergence" de forme exponentielle décroissante, qui permet de se rappro­cher du rayon final R_f à rouler en fonction du numéro de la passe.
  On peut fixer le nombre de passes n par l'intermédiaire de la loi de convergence.
  Les caractéristiques de la tôle, le nombre de passes, le rayon final et les tolérances sont introduits dans le cal­culateur 50 par l'entrée 60 (voir fig. 3) ;
• 3) selon une loi mathématique fixée par la géométrie de la machine et de ses accessoires, le calculateur établit ensuite, pour chaque rayon théorique R_n à obtenir la consigne théorique fixé X_n de position du rouleau correspondante :
• 4) pendant le roulage de la passe n, à la consigne principale X_n est superposée une consigne variable de correction α E(n-1)i, qui représente, pour chaque point du profil de la tôle 20, une partie de la valeur E(n-1)i mémorisée, correspondant à l'écart enregistré à la passe (n-1) précédente par les palpeurs entre le rayon théorique R(n-1) et le rayon réel R(n-1)i. Cet écart est fonction de la position i de la tôle 20 par rapport à l'endroit où elle est pincée ;
• 5) les valeurs de E (n-1)i correspondent en tout point au profil roulé, à la moyenne arithmétique des écarts entre le rayon théorique R(n-1) et le rayon réel instantané R(n-1)i. Ces écarts sont calculés par le calculateur 50 à partir des valeurs R(n-1)i₁ et R(n-1)i₂, mesurées simultané­ment par les deux palpeurs 30a, 30b tout au long de la tôle. Cette disposition permet de limiter toute erreur de mesure due aux mouvements irréguliers de la tôle pendant la trans­lation "à vide", et/ou à l'effet du poids propre de la tôle dont le centre de gravité se déplace pendant la translation.
  Ces écarts sont ensuite mémorisés. Ainsi que dit ci-dessus, les valeurs enregistrées de E(n-1) sont transformées en consignes de correction αE(n-1)i pour tenir compte de la loi de convergence, du numéro de la passe et de la géométrie de la machine ;
• 6) de même les mesures effectuées par les deux palpeurs 30a, 30b à la passe n permettent de calculer par des relations géométriques simples, le rayon instantané en tout point et le rayon moyen réel correspondant R(n)i.
• 7) la comparaison entre le rayon final R_f entré comme donnée dans le calculateur 50 et le rayon R(n)i arrête le cycle de convergence lorsque l'écart est inférieur à une valeur fixée à l'avance (tolérance admise sur le rayon) ;
• 8) de même, le cycle d'asservissement des rouleaux est stoppé lorsque la valeur E(n), représentant la moyenne arithmétique des valeurs E(n)i le long de la tôle, est inférieure à une valeur référence fixée à l'avance (tolérance d'ovalisation). E(n) représente l'écart entre R(n) et R(n)i à la passe n.

The side rollers are controlled as follows:

• 1) each of the rollers 21 and 22 is respectively associated with two sensors 40 a , 40 b and 41 a , 41 b which represent the position x of each of the rollers 21, 22. This arrangement makes it possible to obtain precisely the horizontality rollers;
• 2) as a function of the geometric data of the machine and of the number n of the pass to be produced, a digital computer 50 (fig. 3) calculates the theoretical radius R _n to be obtained. This calculation is carried out according to a law known as "of convergence" of decreasing exponential form, which makes it possible to approach the final radius R _f to roll according to the number of the pass.
  One can fix the number of passes n via the law of convergence.
  The characteristics of the sheet, the number of passes, the final radius and the tolerances are introduced into the computer 50 via input 60 (see fig. 3);
• 3) according to a mathematical law fixed by the geometry of the machine and its accessories, the computer then establishes, for each theoretical radius R _n to obtain the fixed theoretical setpoint X _n of position of the corresponding roller:
• 4) during the running of the pass n , on the main setpoint X _n is superimposed a variable correction setpoint α E (n-1) i, which represents, for each point of the profile of the sheet 20, a part of the value E (n-1) i stored, corresponding to the difference recorded on the previous pass (n-1) by the probes between the theoretical radius R (n-1) and the real radius R (n-1) i. This difference is a function of the position i of the sheet 20 relative to the place where it is pinched;
• 5) the values of E (n-1) i correspond at all points to the rolled profile, to the arithmetic mean of the differences between the theoretical radius R (n-1) and the instantaneous real radius R (n-1) i. These differences are calculated by the computer 50 from the values R (n-1) i₁ and R (n-1) i₂, measured simultaneously by the two feelers 30 a , 30 b throughout the sheet. This arrangement makes it possible to limit any measurement error due to the irregular movements of the sheet during the "unladen" translation, and / or to the effect of the self-weight of the sheet whose center of gravity moves during translation.
  These differences are then memorized. As said above, the recorded values of E (n-1) are transformed into correction instructions αE (n-1) i to take account of the law of convergence, the number of the pass and the geometry of the machine;
• 6) in the same way the measurements carried out by the two probes 30 a , 30 b with the pass n make it possible to calculate by relations simple geometric, the instantaneous radius at any point and the corresponding real mean radius R (n) i.
• 7) the comparison between the final radius R _f entered as given in the computer 50 and the radius R (n) i stops the convergence cycle when the difference is less than a value fixed in advance (tolerance allowed on the radius );
• 8) likewise, the control cycle of the rollers is stopped when the value E (n), representing the arithmetic mean of the values E (n) i along the sheet, is less than a reference value fixed in advance (ovalization tolerance). E (n) represents the difference between R (n) and R (n) i at pass n .

During rolling, the production of a non-left cylinder requires having a constant and uniform pinching force on the sheet over the length of the sheet.

In the event that this force is not uniform or is poorly determined, a cone or a barrel is rolled, or the sheet is rolled.

The pinching force depends on the thickness of the sheet to be rolled, its width and the quality of the steel.

The adjustment of this effort is currently, as already indicated, carried out by means of safety valves controlled by the operator, generally separately for each side.

This arrangement can in many cases lead to errors (different settings between the two valves, incorrect setting in relation to the characteristics of the sheet, etc.) which result in the faults mentioned above.

The proposed machine therefore includes a servo of the pinching force carried out in the following manner.

The movable lower central roller 2 is equipped with two jacks 13 and 14. Each section of jacks subjected to the pressure is equipped with a pressure sensor 61 a , 61 b (see fig. 2).

Depending on the characteristics of the sheet metal entered as data in the computer 50, the latter establishes from simple relations a pressure set point P _o , image of the pinching force. This setpoint is compared to the actual pressure P _r measured by the sensor 61 a or 61 b.

The difference between P _o and P _r makes it possible to control a servo-valve 62 or 63 which feeds the actuator 13 or 14 or discharges the oil under pressure to keep the pressure constant.

One of the jacks can also receive an additional external instruction 70 which allows for example to straighten a sheet which would have been rolled in a cone or left. This additional setpoint makes it possible to modify the pressure of the circuit in question more or less than the calculated pressure.

This machine can also roll cones by tilting the lateral bending roller with respect to the horizontal. For this, the position setpoints x _n imposed on each cylinder of the same roller are different, and result from a simple mathematical calculation established according to the geometric data of the machine and solved by the computer.

A manual control modifying one of the two set points x _n of position of the two control cylinders of the same roller also makes it possible to produce cones by the operator independently of the computer (arrows F₁₀ and F₁₁ - Fig. 3).

Claims (5)

1 - Machine with automatic control for rolling the sheets comprising at least two central rollers (1, 2) suitably driven, adjustable in height and able to be moved axially to allow the finished object to be released, characterized in that in combination with these central rollers (1, 2) are placed, in a manner known per se, lateral rollers (21, 22) which can be positioned in space using jacks (23, 24), this positioning being permanently recorded by sensors (40 a , 40 b , 41 a , 41 b ) working in connection with a computer (50) and probes (30 a , 30 b ) constituted by jacks with each rod at its upper part , rollers (33, 34) so as to obtain the position of these probes by means of digital or analog sensors (35 a , 35 b ) giving information compared to the instructions coming from the computer (50) in order to correctly position the side rollers (21, 22) for rolling the sheet to the radius foreseen in s a given tolerance, to calibrate the faults inherent in the sheet to a given value or to roll cones if necessary. 2 - Machine according to claim 1, characterized in that one of the central rollers (2) (lower roller) is mounted on bearings which can slide vertically under the action of jacks (13, 14) to obtain a constant force and uniform from the setpoints developed by the computer (50). 3 - Machine according to one of claims 1 and 2, characterized in that the computer contains, at least, a memory for recording the tolerances of the radii and roundnesses of the sheet to be worked. 4 - Machine according to one of claims 1 to 3, characterized in that the number of work passes is programmed in advance in the memory of the computer (50). 5 - Machine according to one of claims 1 to 4, characterized in that rolling is carried out continuously, each successive radius being calculated according to a decreasing exponential convergence law, the roundness correction being carried out during rolling.

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