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
  • B21B37/16—Control of thickness, width, diameter or other transverse dimensions
  • B21B37/165—Control of thickness, width, diameter or other transverse dimensions responsive mainly to the measured thickness of the product
• • 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
  • B21B37/16—Control of thickness, width, diameter or other transverse dimensions
• • 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
  • B21B37/46—Roll speed or drive motor control
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
  • B21B38/04—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring thickness, width, diameter or other transverse dimensions of the product
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/02—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
  • B21B1/04—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing in a continuous process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
  • B21B1/18—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section in a continuous process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2263/00—Shape of product
  • B21B2263/02—Profile, e.g. of plate, hot strip, sections
• • 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
  • B21B37/48—Tension control; Compression control
• • 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
  • B21B37/58—Roll-force control; Roll-gap control

Definitions

• the present invention concerns a plant and the corresponding method to control the section, and in particular its area, of a rolled product worked in rolling mills.
• the present invention is applied in a rolling line to control and adjust the drawing action or thrust imparted to the rolled product, in order to guarantee that the dimensional values of the final product are respected and to guarantee high quality characteristics of the material.
• an irregular and/or inconstant drawing action over time can lead to dimensional irregularities and/or to unacceptable deteriorations in quality, which can cause losses in production, stoppages of the rolling line, need for frequent adjustments and other problems that influence the efficiency and productivity of the line.
• Document EP-A1 -920.926 also in the name of the present Applicant, discloses a method to control the drawing action applied between a semi- finishing rolling block and a finishing rolling block.
• the method provides to use three section detectors, one at exit from the semi-finishing rolling block, one at entrance to the finishing rolling block and one at exit from the finishing rolling block.
• the values obtained by said detectors are compared with expected values memorized in suitable databases, and in the event of discrepancies a correction is carried out in the drawing parameters of the rolled product.
• this document performs a control of the drawing action by detecting one dimensional parameter at exit from a semi-finishing block and by comparing it with the value at entrance to a finishing block and with the value at exit from the finishing block itself. In the event of divergences from the expected values, a correction is generated which in any case does not prevent the discard of a large quantity of material, which is unacceptable in the case of large diameter profiles.
• an interstand control is known, according to which the drawing action is controlled and consequently adjusted so as to keep it constant, or almost constant, within predetermined limits also as the physical and/or chemical condition of the material passing through varies.
• an imprecise and inconstant control of the drawing action does not allow to perform adjustments on the line such as to allow to keep the process automated and repeatable, irrespective of conditions upstream, maintaining determinate dimensional tolerances, without having recourse to complex and complicated adjustments that would cause stoppages of the rolling line and a reduction in production.
• Purpose of the present invention is therefore to obtain a plant, and the corresponding method, which are able, in every rolling condition, in particular when rolling products with a section diameter from about 70mm and more, to provide a control of the section area in every part of the rolled bar, in order to obtain a final product that is coherent with the expected sizes.
• the Applicant has devised, tested and embodied the present invention to overcome these problems and to obtain a control of the section of the rolled product that is efficient and effective along the whole rolling line.
• a plant according to the present invention which overcomes the limits of the state of the art and eliminates the defects present therein, is used to control the section area of a rolled product passing through a rolling train comprising at least two rolling stands.
• the invention is applied in particular on products with a diameter from 70 mm and more, since in such cases the problems involved are more significant.
• the plant comprises a device to measure the section area, or section measurer, disposed immediately at exit from one of the rolling stands, which can be the last stand in the case of a train with only two stands, or an intermediate stand when the train comprises three or more stands.
• the section measurer will detect the size of the section area of a round profile, or similar to round, so that, in the case of a train with a larger number of stands, the measurer will be disposed at exit from a stand identified by an even number (2 A , 4 A , 6 A etc.), while at exit from the stands identified by an odd number (1 A , 3 A , 5 A ) the section of the bar will be oval.
• the section measurer therefore controls the dimension of the round section of the rolled product exiting from the corresponding rolling pass.
• the plant comprises a control system comprising a control unit, inside which is contained a database of parameters necessary for the correct working, to which the section measurer is connected.
• the database contains a series of working parameters, for example the size of the diameter of the rolled product exiting at least from each rolling stand in which a round section is obtained, correlated to other working parameters, for example the temperature of the rolled product, the type of steel, the rolling speed, the data relating to the wear of the rolling rolls, and other.
• the rolling line can be set, for example in terms of the gap between the rolling rolls, at the start of the cycle as a function of parameters set in advance, or detected instantaneously, for example by temperature probes disposed at entry to the rolling line, by speed detectors or other.
• the value of size detected by the section measurer is compared with the value of the section area, memorized in the above- mentioned database, which the rolled product should have at exit from the stand where the detection is made, possibly based on the set or pre-memorized working parameters.
• the control system acts on the rolling speed, that is, on the speed of rotation of the rolls of at least one of the stands, between the one provided with the measurer and one or more of those upstream thereof, in order to modify the drawing action and return the section size to the expected value.
• the value of the drawing action can be correspondingly increased or decreased.
• sections with a diameter of 70 mm and more, up to 100 mm and more can be subjected in the segment between the two stands, both to a greater drawing action and to a greater thrust, in order to return the value of drawing action to the value corresponding to the desired section, within the admissible limits of the peak load for the segment of rolled product in the interstand.
• control system and its database can be equipped with self-learning systems which, based on the adjustments made during one rolling cycle, memorize the values of speed and possibly the gap between the rolls, so that when a new cycle is started, if the starting conditions are the same (starting diameter of the bar, type of material, temperature, etc.) the rolling line, and in particular all the stands, is already in a substantially optimum situation for the rolling passes.
• the invention provides a first option in which the correction of the drawing action is distributed over several stands, if present, or over several pairs of stands between those upstream of the stand where the section measurer is disposed at the exit.
• the invention provides to intervene by widening or reducing the gap of one or more of the stands involved in detecting the size.
• a maximum threshold is provided of the drawing action admissible between two or more stands, so that, when the tail end of the bar leaves the first stand, the consequent annulment of the drawing action cannot cause the size of the section to go outside acceptable and controllable values, which would thus oblige a considerable part of the terminal segment of the rolled bar to be discarded.
• the section measurer in the case of four rolling stands, can be located either downstream of the second stand or downstream of the fourth stand. In this case, it is possible to proceed with a rough adjustment between the first and second stand and with a fine adjustment between the third and fourth stand, always within the maximum admissible threshold of drawing action or thrust on the rolled product being worked.
• a control is carried out on the characteristics (for example temperature, section size, type of material, etc.) of the rolled product arriving in the upstream stand, so as to proceed, before the corresponding rolling pass, with the necessary settings of the work parameters of the stand, so as to obtain the desired drawing action and such to take the rolled product to a section size that corresponds to the expected and pre-memorized value.
• characteristics for example temperature, section size, type of material, etc.
• - fig. 1 shows schematically a rolling train consisting of four rolling stands, in which the method according to the invention is applied between the third and fourth stand;
• - fig. 2 shows a variant of fig. 1 ;
• - fig. 3 shows another variant of fig. 1 ;
• - fig. 4 is a schematization of the functioning of the invention.
• Figs. 1, 2 and 3 show by way of example a rolling train 30 consisting of four rolling stands 1 1, considering an oval-round-oval-round rolling cycle, in which a rolled product 12 is deformed through each stand 11, assuming an oval and round cross section in alternate sequence. In this way better quality characteristics of the final product are obtained.
• the invention also concerns the case where there are two, six or more stands 1 1.
• the four stands 1 1, respectively 11a, l ib, 11c and l id in this case are identified for a final round rolling, so they are characterized by the acronyms 01 and O2 to indicate oval rolling and by Tl and T2 to indicate round rolling.
• Each of the stands 1 in a known manner, has a motor 14 to move the parts needed for rolling, in particular to rotate rolling rolls 18, and adjustment means 15 to adjust the calibration gap between the rolling rolls 18.
• a section measurer 10 is provided at exit from the last stand 1 Id, that is, the fourth.
• the invention is applied only between stands 1 lc and 1 Id of the O2 and T2 type.
• the adjustment of the drawing action, based on the measurements of the section area performed by the section measurer 10, is applied only between the third stand 11c and the fourth stand 1 Id.
• the invention is applied between all four stands 1 la, 1 lb, l ie and l id, distributing the adjustment of the drawing action so that a dissimilarity between the expected value of the section area and the value measured by the section measurer 10 is corrected by adjusting the drawing action between all said stands 1 1a, l ib, 1 1c and 1 Id.
• a section measurer 1 10 is provided at exit from the second stand 1 lb and a section measurer 10 at exit from the fourth stand 1 Id.
• this solution allows to intervene by adjusting the drawing action between the stands 1 1a and l ib, and then possibly intervening also with an adjustment of the drawing action between stands 1 lc and 1 id.
• the invention provides that, according to the circumstances, it is possible or necessary to intervene on the calibration gap between the rolling rolls 18, acting on each occasion on the motor 14 or on the adjustment means 15 of one or more stands 11.
• control system can provide an adjustment of the gap between the rolling rolls 18, for example of the last stand 1 Id or the last two stands 1 lc and l id, together with an adjustment of the drawing action between said two stands, until the section measurer 10 detects that the value of the section area corresponds to the expected value memorized in the control system.
• a maximum threshold of drawing action or thrust is also provided, acceptable between two stands, so that said value is not excessive when the tail end of the rolled product 12 leaves the first stand 11a, something which in this case could lead to an unacceptable deformation, both in the sense of stretching (excess drawing action), and also in the sense of deformation and compression (excess thrust), of the last segment of the rolled product 12 which would thus have to be discarded.
• Fig. 4 shows the invention schematically with a block diagram, describing the functioning thereof, as described hereafter.
• the section measurer 10 (or section measurers 10 and 1 10) detects the section area of the rolled product 12 and transmits the data detected to a control unit 20, which can be the programmable type.
• the control unit 20 contains a database 21, in which the parameters necessary for controlling the rolling are memorized, and in particular at least the values relating to the value of the section area of the rolled product 12 at exit from each of the stands 1 1a, l ib, 1 1c, l id. With the aid of the database 21, the control unit 20 controls whether a possible variation in the section area, detected by the section measurer 10, 1 10, differs or not from the expected value.
• the adjustments performed at the end of the rolling cycle can be memorized in the database 21, so as to allow to set the settings of all the stands 1 la-1 Id to start the following cycle if the product to be rolled has the same characteristics as the product already rolled, thus also obtaining an optimum setting already on the first segment of the rolled product 12.
• rolling cards can be present in the database 21, in which the setting value of the speed of rotation of the rolls and/or the gap between the rolls is correlated to data relating to the wear of the rolls and to specific characteristics of the rolled product 12 being worked, for example its temperature at entry into the rolling line, the type of steel, the starting diameter of the rolled product 12 and other.
• a control device 23 is provided of the characteristics of the rolled product 12 being worked (temperature at entry to the rolling line, type of steel, starting diameter of the rolled product 12), on arrival in the upstream stand 11, so as to proceed with the settings of the stand itself that are necessary to obtain a constant or almost constant section area.
• a confirmation block 24 allows the rolling to proceed without the control unit 20 intervening.
• control unit 20 If the control unit 20 detects an incorrect value, the control unit 20 intervenes by means of an adjustment block 25, adjusting the speed of the motor 14 that feeds the rolling rolls 18 by an action performed on a motor adjustment block 26, or by adjusting the gap, that is, the distance between the rolling rolls, by means of the adjustment means 15 and following a gap adjustment block 27, with actions of an entity coherent with the information relating to the product being rolled and contained in the database 21.

Applications Claiming Priority (2)

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• 2012
  • 2012-02-17 IT IT000026A patent/ITUD20120026A1/it unknown
• 2013
  • 2013-02-15 US US14/379,411 patent/US20150027186A1/en not_active Abandoned
  • 2013-02-15 EP EP13713491.2A patent/EP2814626A1/en not_active Withdrawn
  • 2013-02-15 KR KR20147025957A patent/KR20140140036A/ko not_active Application Discontinuation
  • 2013-02-15 CN CN201380020719.5A patent/CN104703719A/zh active Pending
  • 2013-02-15 WO PCT/IB2013/000204 patent/WO2013121277A1/en active Application Filing

Non-Patent Citations (1)

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