Classifications

• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D1/00—Straightening, restoring form or removing local distortions of sheet metal or specific articles made therefrom; Stretching sheet metal combined with rolling
  • B21D1/02—Straightening, restoring form or removing local distortions of sheet metal or specific articles made therefrom; Stretching sheet metal combined with rolling by rollers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D1/00—Straightening, restoring form or removing local distortions of sheet metal or specific articles made therefrom; Stretching sheet metal combined with rolling
  • B21D1/05—Stretching combined with rolling

Definitions

• the present invention relates to a device and a method for calibrating a multi-roller leveler.
• Multi-roller levelers are used as finishing tools for flattening steel sheets.
• the general principle of leveling by multi-roller levelers in particular leveling under tension, consists in passing the sheet or strip to be leveled between two series of parallel rollers arranged so as to be nested one inside the other, the nesting being decreasing in the direction of travel of the sheet.
• the sheet is flexibly deformed alternately in one direction then in the other.
• the amplitude of flexion decreases from the entry of the leveler towards the exit, so that the steel strip is subjected to a succession of alternating stresses capable of eliminating or at least greatly reducing the internal stresses which cause flatness defects.
• the strip is driven through the leveler between a supply reel and a take-up reel by “S” drive blocks which cause it to run, while also ensuring traction on the strip.
• FIG. 1 there is shown schematically such a leveler, comprising a set of lower rollers 11, and a set of upper rollers 12, carried respectively by a lower base 13 and an upper base 14.
• the metal strip 10 runs in the leveler between two motorized blocks 31, 32 of drive and traction drums arranged in "S", in the direction of arrow F.
• the rollers are all parallel and offset in the direction of travel of the strip between the top and the bottom, so that they can be more or less nested within each other.
• the strip in the entry area of the leveler, the strip is relatively strongly deformed by alternating bending between the entry rollers 11a, 12a, 11b, etc. which are strongly nested, while in the exit zone, the deformations are very small due to the fact that the exit rollers 11m, 12m, linen are little or not at all nested.
• FIG. 2 there is also shown schematically an example of adjustment means of the leveler, to adjust the nesting of the rollers.
• the upper box spring 14 is supported on an upper frame 15 by sets of adjustments 16a, 16b, 16c, 16d, for example of the screw-nut type with angle gear, arranged respectively in two sets 16a, 16b towards the entry of the leveler and the other two 16c, 16d towards the exit, and on each side in the longitudinal direction.
• the two input adjustment sets 16a, 16b are connected by a drive shaft 17a and a coupling 18a, and driven together by an input motor 19a.
• the two output adjustment assemblies 16c, 16d are connected by a drive shaft 17b and a coupling 18b, and driven together by an output motor 19b.
• the couplings 18a, 18b make it possible to temporarily uncouple the sets of adjustments which they connect, in order to be able to adjust the transverse parallelism, or "wobbling", between the lower and upper rollers, and this at the entry as at the exit from the leveler. Then, the adjustment of the overlaps of the rollers of the leveler is carried out by means of the motors which simultaneously and identically drive the adjustment assemblies, either at the entry of the leveler or at the exit.
• the parallelism or swaying adjustment is only carried out in the event of major interventions on the leveler.
• Calibration of the leveler is carried out more commonly, to readjust the nestings of the rollers, or modify them according to the characteristics of the planed strips.
• FIG 3 there is also schematically shown the leveler, in front view, to show the means for adjusting the bending or bending of the rollers.
• the bending forces exerted on the strip lead in reaction to causing deformations of the leveling rollers.
• the leveling rollers are in fact supported by support rollers, themselves supported by support rollers.
• This assembly is mounted in a chassis called cassette placed on a set of bias wedges or actuators or against independent supports, adjustable in height, distributed over the width of the leveler.
• the vertical position of the support rollers can be adjusted by means of adjustable bias wedges 22, each acting under all of the support rollers located on the same line parallel to the travel of the strip and over the entire length of the leveler.
• the shape of the leveling rollers therefore depends on the vertical position of the support rollers.
• FIG. 5 An example of an adjustable counter-support system is shown in FIG. 5.
• the height of the counter-supports is adjustable by means of bias wedges 23 interposed between the support rollers and a rigid lower frame 15 ′ and sliding l 'one over the other.
• the relative displacement of the bias wedges is effected by a jack 24, and can be measured for example by a position sensor 25.
• the calibration of multi-roller levelers is conventionally carried out empty using rectified steel shims, or loaded using metal shims and lead bars, which are slid between the bases of the leveler, then the bed bases are clamped in parallel to a precise spacing between the two sets of lower and upper rollers, spacing defined by a rectified steel shim, for example 8 mm thick, placed between the two sets of rollers.
• the leveler is thus placed under conditions of effort capable of making up for the inevitable mechanical play and in a state of stress determined by the crushing of the lead wedges.
• the position of the clamping screws of the leveler is then identified, position then considered as a reference, and with respect to which the subsequent working position is adjusted, by bringing the said adjusting screws into the position corresponding to the position of desired work of the rollers, based on the relationship between the displacement of said screws and the corresponding displacement rollers.
• the known method has in particular the consequence observed experimentally of causing over-tightening during the planing of thin strips.
• the present invention aims to solve the problems mentioned above. It aims in particular to make it possible to determine with better precision the characteristics of a multi-roller leveler, by performing a load calibration, reproducible and under known forces. It also aims to determine the overall yield of the leveler, under different loads, so as to be able to integrate these values into the adjustment models. It also aims to determine more precisely the influences of the counter-support settings, so as to refine the settings of the latter and to be able to correct the transverse yielding of the leveling rollers, in order finally to obtain a better flatness of the planed strips.
• the invention relates to a device for calibrating a multi-roller leveler for leveling a metal strip, comprising a set of lower rollers and a set of upper rollers, arranged substantially parallel, perpendicular to the direction. leveling along which the strip to be leveled travels.
• the device is characterized in that it comprises a metal measuring plate, in particular with a high elastic limit, of a size suitable for being placed in position between the set of upper rollers and the set of lower rollers. extending substantially over the entire length of said rollers, said plate comprising positioning means for ensuring its positioning relative to the rollers in the leveling direction, and strain gauges for measuring elastic deformations of the plate, the said strain gauges being fixed on the plate so as to form several transverse rows of gauges each located directly above one of said rollers, on the face of the plate opposite to said roller.
• the invention also relates to a method for calibrating a multi-roller leveler, using the device according to the invention, characterized in that the measuring plate is placed in the leveler, positioned by means of the positioning means so that each row of gauges is located directly above a roller, and the two sets of rollers are brought together so as to exert a clamping force on the measuring plate, and the measurement is made by means said gauges the deformations undergone by the plate at the right of each roller located below the gauges, to deduce the clamping force applied by the rollers at the right of each gauge, as well as the actual tightening between rollers.
• the strain gauges placed directly above the rollers it is possible to measure the surface bending deformations of the plate, caused by the pressing of the rollers on the plate, and to deduce therefrom, knowing the mechanical characteristics of the plate, l intensity of the pressing force at each gauge. From these measurements, one can therefore have a precise knowledge of the characteristics of the leveler, from the point of view of the geometry of the leveling path defined between the rollers.
• the plate comprises at least one row of gauges situated so as to be placed directly above one of the rollers situated towards the entry of the leveler, and a row of gauges situated so as to be placed plumb with one of the output rollers. It is thus possible to determine the clamping forces at the input and output of the leveler, and for example consequently initialize the motors controlling the position of the upper bed base, in a position corresponding to an identical clamping at the input and at the output, in order to then assess the actual tightening gap between inlet and outlet, and therefore the difference in nesting between the inlet rollers and the outlet rollers. Note that the gauges will not be placed in line with the first roller, upper or lower, or in line with the last roller, upper or lower, so that the measurements will only be made in line with rollers loaded only substantially vertically.
• a row of gauges has at least one gauge located in the center line and one gauge on each side towards the edges of the leveler, which makes it possible to determine, and therefore correct if necessary, differences in tightening between the sides of the leveler. In combination with the measures mentioned above, it becomes possible to detect, and therefore also correct, swaying of the leveler.
• a row of gauges comprises a central gauge and several lateral gauges, arranged so as to be each located directly above each counter-support of the leveler. It is then possible to further improve the precise knowledge of the characteristics of the leveler, from the point of view of the geometry of the leveling path defined between the rollers, in particular of the transverse profile of this path, which is defined by the shape of the generators of the contacting rollers. the measurement plate.
• the invention also makes it possible to grasp the behavior of the leveler when loaded, by determining the overall tightening force in different measured positions of the tightening control means, and by deducing therefrom a yield curve of the leveler, which can then be taken into account to carry out the presets for the work, according to the dimensional and mechanical characteristics of the bands to be leveled, and according to the importance of the nesting of the rollers necessary to correct known defects of said bands, for example.
• the overall tightening force determined from all the measurements made by all the gauges we could also appreciate more localized variations in tightening, to distinguish for example the proper ceding of each column of the leveler, or to independently monitor the behavior of the counter-supports during load variations.
• instrumented plate according to the invention is typically a steel plate with high elastic limit, for example of 1000 MPa, and of thickness for example of the order of 0.7 mm, in any case very thick. significantly greater than that of the strips to be leveled, which typically have a thickness of 0.1 to 0.2 mm for example.
• the measuring plate must not be subjected to plastic deformations, which could in particular occur following too strong nesting of the rollers. Too much nesting of the rollers can risk excessively distorting the measurement gauges.
• the thickness of the plate is determined so as to apply by elastic bending the leveling forces usually supported by the leveler. - in addition, a maximum thickness of the plate is determined to avoid reducing the sensitivity of the measurements.
• the elastic limit of the plate is determined according to the thickness and so as to avoid plasticization when the plate has to apply the usual maximum leveling forces.
• the positioning means comprise at least two sets of positioning gauge respectively disposed towards each lateral edge of the plate, as far apart as possible from each other, perpendicular to the same roller, to allow to precisely determine the positioning of the plate relative to this roller in the leveling direction, and therefore the relative position of all the rows of measurement gauges with respect to their respective rollers.
• the positioning gauges are preferably gauges of the type known under the name of "chains", conventionally constituted under the form of a set of five strain gauges associated in line over an overall length of the order of a centimeter. Each chain is precisely glued to the face of the plate opposite a working roller, so that the axis of the central gauge of the chain is perfectly in line with the axis of said roller.
• the positioning of the plate is done by observing the signals from each gauge of the chain, until a symmetry is obtained on the gauges located on each side of the central gauge on the one hand and until detection a maximum by the central gauge on the other hand, significant of the location thereof just below the axis of the roller, where the curvature of the plate is most pronounced.
• FIGS. 1 to 5 which illustrate the principle and the production of a multi-roller leveler have already been commented on
• FIG. 6 is a partial view of a measuring plate according to the invention
• Figure 7 illustrates the positioning of the plate in the leveler, according to the invention.
• FIG. 8 is a graph showing by way of example a yield curve determined using the measuring plate
• FIG. 9 is a graph illustrating the loaded profile of the rollers at the entry of the leveler, showing in particular the influence of the adjustment of the counter-supports on the profile.
• the instrumented plate 5 given by way of example and produced for a particular type of multi-roller leveler, shown in FIG. 6, is typically a sheet steel plate with high elastic limit, 0.7 mm thick and 500 mm in the direction of leveling and 1 m in the transverse direction. It carries several rows of deformation gauges 50 bonded to the surface of the sheet, as follows:
• a first row 51 of gauges is located on the upper face, so as to be positioned directly above the second lower roller 11b, as can be seen in FIG. 7.
• a second row 52 of gauges is placed similarly to the perpendicular of the '' penultimate lower roller.
• a third row 53 is preferably placed at the level of a median roller of the roller series.
• Each of these rows has seven gauges, such as the gauges 51a, 51b, 51c, 51f, 51i, 51j, 51k, of the first row, placed respectively over the counter-supports 22a, 22b, 22c, 22f, 22i , 22d, 22k.
• Other rows of gauges are placed on the underside of the plate 5, such as a row of gauges 54 placed in line with the second upper roller 12b, a row 55 placed in line with the penultimate upper roller, and a row 56 placed vertically above a middle roller of the series of upper rollers.
• Each of these rows comprises for example three gauges, placed respectively plumb with the counter-supports 22b, 22f, and 22j.
• positioning gauges 61, 62 consisting of chains of five gauges aligned in the leveling direction, of a type known per se, and whose central gauge is located precisely on line 54.
• the plate 5 also includes two adjustable stops 60, each comprising a fixed part 63 secured to the plate 5 and a movable part 64 adjustable relative to the fixed part, for example by a micrometric screw, and the end of which is positioned so as to abut against the first lower roller, as shown in FIG. 7.
• adjustable stops 60 each comprising a fixed part 63 secured to the plate 5 and a movable part 64 adjustable relative to the fixed part, for example by a micrometric screw, and the end of which is positioned so as to abut against the first lower roller, as shown in FIG. 7.
• the indications given by the positioning gauges 61, 62 allow the correct positioning of the row of gauges 54 to be plumb with the roller 12b, and to correct it if necessary using adjustable stops 60, with precision. of the order of 0.1 mm.
• This first measurement step is decisive in ensuring perfect parallelism between the rows of gauges and the rollers, and the precise positioning of each alignment of gauges in the vertical plane passing through the axis of the
• the tightening measurements can then be made using the various gauges.
• Such a yield curve can then be integrated into the adjustment parameters of the leveler.
• the graph in Figure 9 shows, by example, the profile of the rollers entering a leveler.
• Trace 71 corresponds to a setting of the counter-supports at 0; trace 72 at a setting at -0.05 mm; plot 73 at a setting of -0.1 mm.
• Each point of the plots corresponds to a measurement gauge, and the values indicated on the ordinate represent the tightening of the rollers on the plate, determined from the measurements carried out.
• the invention is not limited to the embodiment of the instrumented plate described above only by way of example.
• the number and arrangement of the rows of gauges and the number of gauges per row may be modified, depending on the number of rollers of the leveler, the number of counter supports and the desired measurements.
• the positioning gauges as well as the adjustable stops can be replaced by equivalent means capable of ensuring the most precise positioning possible of the rows of measuring gauges perpendicular to the rollers.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Straightening Metal Sheet-Like Bodies (AREA)
• Rollers For Roller Conveyors For Transfer (AREA)
• A Measuring Device Byusing Mechanical Method (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Coating With Molten Metal (AREA)
• Length Measuring Devices With Unspecified Measuring Means (AREA)
• Cultivation Receptacles Or Flower-Pots, Or Pots For Seedlings (AREA)
• Sowing (AREA)

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• 2000
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