US3220232A - Hot rolling mill controls - Google Patents

Hot rolling mill controls Download PDF

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Publication number
US3220232A
US3220232A US207455A US20745562A US3220232A US 3220232 A US3220232 A US 3220232A US 207455 A US207455 A US 207455A US 20745562 A US20745562 A US 20745562A US 3220232 A US3220232 A US 3220232A
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United States
Prior art keywords
stations
station
gauge
coupled
measuring
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Expired - Lifetime
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US207455A
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English (en)
Inventor
Tix Arthur
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Bochumer Verein fuer Gussstahlfabrikation AG
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Bochumer Verein fuer Gussstahlfabrikation AG
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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
    • B21B37/16—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

Definitions

  • roller clearances It is also known to correct roller clearances by reference to a detector which measures the gauge and/ or the width of the rolled material as it leaves the mill and in such a way that the trailing end of the stock, which has been subjected to a longer cooling due to its longer wait before entering the mill, will have the Isame finished gauge and/ or finished width as the leading end.
  • An object of the invention is to provide for overcoming the defects of known techniques and, to this end, the invention proposes a continuo-us finishing mill which comprises feedback control means for individually controlling the clearance between the rollers of a plurality of stations and monitoring means for measuring the gauge and/or width of the rolled stock leaving the final station, and which differs from known types of mills in that at least one of the stations-exclusive of the final stationis associated with a regulator for regulating roller clearance at that station, the regulator functioning to reduce the clearance at a rate calculated to decrease the gauge and/ or width of the product leaving the final station progressively, contrary to the natural tendency to increase in gauge and width as rolling proceeds.
  • roller stations may be associateded with regulators of the aforesaid kind.
  • the clearance between the rollers associated with a given regulator is decreased below the basic clearance prescribed by conventional computation.
  • the station associateed with this regulator generates a rolling taper in the gauge or thickness yof the product which is contrary to the natural rolling taper of gauge or thickness, and which is empirically chosen. Even if this opposing taper Ishould not completely compensate the natural rolling taper, it at least has the effect that the required corrections of the roller clearances in the controlled stations will tend to be in one direction only, as will be hereinafter more fully described. This eliminates the undesirable effect of backlash. Moreover, the magnitude of the required corrections will be smaller, as will be likewise discussed in greater detail.
  • a continuous strip mill be operated in conjunction with a primary mill train which rolls down ingots or slabs from thicknesses exceeding mm. without intermediate heating.
  • a primary mill train which rolls down ingots or slabs from thicknesses exceeding mm. without intermediate heating.
  • Such a mill train is of par- -ticular advantage for hot rolling .strip to a final width of say 7 mm. from an unrolled ingot of say l0 tons or from a correspondingly heavy slab.
  • the strip is of considerable length, the difference in temperature between the leading end which first enters the mill and the trailing end which is the last to enter is particularly great.
  • FIGURE 2 is a graph including curves which represent values as measured by two gauge and/ or thickness detectors in a continuous rolling mill according to the invention.
  • FIGURE 3 diagrammatically illustrates the structure of the rolling station.
  • the individual stations are diagrammatically indicated and are each of conventional structure as diagrammatically illustrated in FIG. 3.
  • the reduction of the slab l is shown on an exaggerated scale and as if reduction were continuous.
  • the roll stations III to VI are respectively associated with controls 2(a-d) for maintaining constant separation of the rollers in each station by continuous adjustment which compensates the elastic deformation of the mechanical structure of the station during rolling.
  • Each control 2 comprises a controller 4, a measuring device 5 for measuring the rolling pressure and a clearance adjuster 6 for adjusting roller clearance (distance RC in FIG. 3).
  • the devices 5 for measuring the pressure may each be of a conventional load cell or a conventional device for measuring the elastic elongation of the mechanical structure of the associated station.
  • the roller adjusting means 6 may be conventional screw-type equipment which permits a relatively fine adjustment. Alternatively, special supplementary hydraulic devices may be included in and controlled by the controller.
  • All the controllers 4 are connecte-d in conventional manner to a computer 7 which is of known type and supplies the required input quantity (X) and causes the rollers in all of the stations (III-VI) of the continuous rolling mill to be set to an initial basic clearance before the stock enters.
  • the computer is associated with a conventional mixer 8.
  • This mixer is supplied a correcting feedback quantity (KVH) from a detector 9 located following the final station VII, and with a seco-nd correcting quantity (KH) derived from a detector 1li located between stations II and Ill.
  • the detectors may be conventional gamma ray thickness gauges and, in any event, should be precision instruments capable of measuring thickness variations in terms of hundredths of a millirneter.
  • the mixer 8 contains conventional lmeans for rescaling the correcting input (KH) as next explained.
  • the scaling factor is predetermined by the fluctuation amplitudes at different points of the train. For instance, (KVK) may require evaluation in terms of tenths of a millimeter and (KH) in full millimeters for establishing equivalence. Since the measuring points are fixed, the scaling factor remains constant while stock of given gauge and width is rolled down.
  • the roller clearance adjusting device 6 of station II is connected with a regulator 11 which may be ⁇ a computer. This regulator is a conventional computer which stores a program for all anticipated lengths of rolled stock. The stored program has been fed into regulator 1l.
  • the particular program for a specific length is preselected on the basis of such specific length.
  • rollers in all of the stations have been adjusted to the basic roller clearance prescribed by computers 7 and corresponding to the curvilinear clearance taper of the rolling mill train.
  • the rollers of stations I and VII remain in this basic position of adjustment during the entire rolling operation of the stock.
  • Computer 7 may be part of the computer 7, but is not modified by the output from mixer 8.
  • the control of the roller clearance in roller stations III-VI by the associated control devices Za-d is modified by correcting inputs received by the measuring devices Sa--d to increase the rolling pressure by further reduction of the roller clearance, when the pressure has already been raised by the passage of a harder section of stock.
  • the roller clearance is slightly increased when a softer length of stock has already caused the rolling pressure of its own accord to fall.
  • the stations therefore operate to maintain a rigidly constant product and thereby substantially compensate non-uniformities in working conditions.
  • the rollers of this station are controlled to produce a rolling taper contrary to the natural rolling taper of the product.
  • the regulator reduces the separation of the rollers at a rate which may be constant or otherwise prescribed by the programsay from l2 mm. to a final l0 mm.
  • the length L of the abscissa of the graph of FIG. 2 represents the length of the rolled stock leaving roller station VII.
  • the values of (KVH) measured by detector 9, which represent the gauge of the outgoing strip are on a line parallel with the abscissa. This is so because the desired finished gauge is independent of stock length. Deviations from the controlled gauge appear as oscillations about the straight dot-dash line. Detector 1t) measures a (KVK) which diminishes linearly towards the abscissa, but which is likewise subject to oscillating deviations. (KVH) diminishes because it is a function of both stock length and desired finished gauge.
  • the fourth station is likewise controlled by a programmed regulator 11, then the generation of the compensating rolling taper will be distributed between two points along the train. This has advantages in permitting better compensation in the controlled roller stations. It is desirable that a controlled station, namely station III, should intervene between the stations regulated by predicted programming. The controlled stations will then be the stations III, V and VI.
  • Apparatus comprising a sequence of rolling stations each comprising rollers having an adjustable clearance therebetween and being aligned to roll a metal body into a strip of determinable gauge, clearance adjusting means coupled to the rollers of each station, irst control means coupled to the clearance adjusting means of the first and last stations to provide constant roller clearances therein according to a predetermined program, first measuring means in selected of the stations between the first and last stations to measure rolling pressure in said selected stations, second control means in said selected stations and coupled to said first measuring means, second and third measuring means respectively positioned following the said last station and at a station between the first and last stations, said second and third measuring means measuring strip thickness variations at their respective positions, mixing means coupled to said second and third measuring means to combine the measurements received therefrom, and computer means coupled to said mixing means and to said second control means and controlling the latter according to a combination of the said predetermined program and the combined measurements, the second control means being also controlled by said first measuring means, said second control means being coupled to and controlling said clearance adjusting means whereby to compensate
  • Apparatus as claimed in claim 2 comprising a programmed regulator coupled to and controlling the clearance adjuster of the said second station.
  • Apparatus for hot rolling a metal strip comprising a multiple stand continuous finishing mill including a plurality of stands arranged in succession and including a first stand, a last stand and a plurality of stands between the first and last stand, each stand including a [pair of rolls through which the strip passes and is rolled, said strips being reduced in thickness as the strip is passed from the first stand to the last stand, said last stand having rolls with fixed adjustment to provide constant spacing between the rolls for the particular strip, means ,for measuring the thickness of the strip at the last stand and at one of the stands between the first and last -stands and proximate the rst stand, and means responsive to the thicknesses of the strip as measured by the last mentioned means for continuously varying the spacing between the rolls of at least one stand located between those stands at which the thicknesses of the strip are measured to produce a strip of substantially uniform thickness at the last stand despite the constant spacing of the rolls thereat and despite the increasing resistance to deformation of the trailing end of the strip as a result of cooling of the strip,
  • Alpparatus as claimed in claim 4 comprising a program control device coupled to the rolls of the stand proximate the iirst stand at which the thickness of the strip is measured.
  • the means for measuring thickness comprise thickness gages located at the outlet of the second stand and at the outlet of the seventh stand, said means for varying the spacing of the rolls comprising mixer means for receiving the thickness measurements from the thickness gages for correcting the spacing of the rolls in accordance therewith.
  • Apparatus as claimed in claim 4 wherein the apparatus further comprises rolls at each stand for controlling the width of the strip, the latter rolls corresponding to the rolls controlling the thickness of the strip but being operated in accordance with width measurements to produce strips of substantially uniform width.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Metal Rolling (AREA)
US207455A 1961-07-01 1962-06-29 Hot rolling mill controls Expired - Lifetime US3220232A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEB0063115 1961-07-01

Publications (1)

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US3220232A true US3220232A (en) 1965-11-30

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US207455A Expired - Lifetime US3220232A (en) 1961-07-01 1962-06-29 Hot rolling mill controls

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US (1) US3220232A (enrdf_load_stackoverflow)
AT (1) AT249614B (enrdf_load_stackoverflow)
GB (1) GB1009035A (enrdf_load_stackoverflow)
LU (1) LU41929A1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841124A (en) * 1971-10-11 1974-10-15 Hitachi Ltd Width controlling apparatus and method for rolled strips

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931917A (en) * 1957-01-07 1960-04-05 Beelitz Guenter Apparatus for determining the width of a metal strip
US2972268A (en) * 1957-04-08 1961-02-21 Westinghouse Electric Corp Automatic strip thickness control apparatus
US2985043A (en) * 1959-04-24 1961-05-23 United States Steel Corp System for controlling the screw settings of a reversing mill
US3081653A (en) * 1957-11-22 1963-03-19 Westinghouse Electric Corp Strip thickness control apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2931917A (en) * 1957-01-07 1960-04-05 Beelitz Guenter Apparatus for determining the width of a metal strip
US2972268A (en) * 1957-04-08 1961-02-21 Westinghouse Electric Corp Automatic strip thickness control apparatus
US3081653A (en) * 1957-11-22 1963-03-19 Westinghouse Electric Corp Strip thickness control apparatus
US2985043A (en) * 1959-04-24 1961-05-23 United States Steel Corp System for controlling the screw settings of a reversing mill

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3841124A (en) * 1971-10-11 1974-10-15 Hitachi Ltd Width controlling apparatus and method for rolled strips

Also Published As

Publication number Publication date
AT249614B (de) 1966-09-26
LU41929A1 (enrdf_load_stackoverflow) 1962-08-22
GB1009035A (en) 1965-11-03

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