US3089365A - Workpiece thickness control apparatus - Google Patents

Workpiece thickness control apparatus Download PDF

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Publication number
US3089365A
US3089365A US30937A US3093760A US3089365A US 3089365 A US3089365 A US 3089365A US 30937 A US30937 A US 30937A US 3093760 A US3093760 A US 3093760A US 3089365 A US3089365 A US 3089365A
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Prior art keywords
signal
strip
thickness
operative
error
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Expired - Lifetime
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US30937A
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English (en)
Inventor
John W Wallace
Paul E Jacobs
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CBS Corp
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Westinghouse Electric Corp
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Priority to US30937A priority Critical patent/US3089365A/en
Priority to JP1584761A priority patent/JPS3711209B1/ja
Priority to FR862560A priority patent/FR1290614A/fr
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Publication of US3089365A publication Critical patent/US3089365A/en
Anticipated expiration legal-status Critical
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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
    • B21B37/18—Automatic gauge control

Definitions

  • the present invention relates in general to workpiece thickness control apparatus and more particularly to control apparatus for a strip rolling mill or the like wherein the rolled actual thickness of the workpiece or strip is compared to a reference desired thickness and the resulting error is provided as a signal and utilized for correcting the rolled thickness of the workpiece.
  • lt is a different object of the present invention to provide improved workpiece thickness control apparatus that is more stable in its operation, and is substantially static to thereby require less maintenance and repair, and is operative only when a thickness error above a predetermined value is present.
  • a rolling mill including an upper roller and a lower roller operative with a strip 12 of metal which passes through the rolling mill 10 from an input reel 14 to a windup reel 16.
  • a strip thickness measuring gauge 18 of the X-ray type for example is operative to provide an youtput lsignal to an amplifier device 2G which output signal corresponds to the difference between the actual measured thickness of the strip 12 and a predetermined reference or desired thickness for the strip 12.
  • the output signal from the amplifier 20 is supplied to an input of a signal gate device 22 which is per se well known in the prior art and is operative to pass the error signal when the gate device is open and to block the passage of the error signal when the gate device is closed.
  • the error signal is supplied to an integrating circuit 24, which could be, for example, a motor operated rheostat or the like, and which provides an output error signal through an amplier 26 to a strip tension control 28 operative with a motor 30 which runs the input or unwind reel 14.
  • the strip tension control 28 may be a well known magnetic amplifier type of variable voltage motor control, for example, with the error signal from the amplifier 26 being supplied to a control winding of a magnetic amplifier for thereby varying the operative speed of the motor 30 in accordance with the value of the control signal supplied by the amplifier 26. In this way the tension of the strip 12 between the unwind reel 14 and the rolling mill 10 is varied for the purpose of nited States Patent raice varying the output thickness of the strip leaving the rolling mill lll.
  • the output signal from the amplifier 20 is also supplied to a signal voltage sensing device 40.
  • the voltage sensing device 40 is operative not to provide an output signal until the error signal received by the amplilier 20 reaches a predetermined value. In other words for values of the error signal below this predetermined minimum value, the voltage sensing device 40 does not provide an output signal. However, for values of the error signal supplied by the amplifier 20 above this predetermined minimum value, such an output signal will be provided.
  • the operation of the gate circuit 40 in this regard is well known in the prior art. For example, a d-iode ⁇ bridge circuit having a back bias voltage across it will not pass an applied input signal of a value less than said bias voltage.
  • the voltage sensing or detecting device 40 may include a liip-flop circuit, such that it provides a binary type of output signal, either a zero value when the error signal supplied by the amplifier 26- is below the desired predetermined value or a unit value output signal when the error signal supplied by the ampliiier 20 is above that predetermined Value.
  • the output signal from the voltage sensing device 48 is operative to open the gate device 22 through the illustrated NOR logic circuitry for a predetermined time interval as determined by the ON timer 46.
  • the operation of the ON timer 46 when it stops its timing operation after a provided ON time period, causes the OFF timer 48 to begin its timing operation and to hold the gate device 22 in its closed state of operation for an OFF time interval dependent -upon the operating speed of the rolling mill 10 as sensed through a pulse source 5t) operative with the mill motor 52.
  • a conventional tachometer may be provided to be operative with the mill mo-tor 52 for providing an analog signal having a value proportional to mill speed. Then the OFF timer 48 would be operative in response to the latter analog signal to provide an OFF time interval inversely proportional to the value of this signal, such that the OFF time interval would be or" shorter duration for a faster operating mill and longer duration for a slower operating rolling mill.
  • the pulse source 56 provides output pulses to the OFF timer 48 at a frequency proportional to the operating speed of the rollingmill 10, such that after a predetermined number of pulses have been received by the OFF timer 48, corresponding to a predetermined length of strip passing through the rolling mill 1t) and thereby compensating for the transport time delay necessitated by the remote physical position of the thickness gauge 18 relative to the rolling mill 10, the OFF timer 48 again allows a thickness correction operation to be made.
  • the output signal from the integrating circuit 24 is effectively the error control signal supplied to the strip tension control 28. If this thickness correction or error signal becomes greater 4than a predetermined magnitude such that there is a likelihood of endangering the breakage of the strip 12, for example, due to an excessive strip tension ⁇ being required to effect the desired error correction, then another voltage sensing device 60 is operative to allow this error signal to p-ass to an input of an ⁇ automatic s-crewdown jogging control circuit 62, to cause the screwdo-wn motor control 68 to operate in the proper direction as ⁇ determined by the signal from the amplifier for causing the serewdown motor 70 to vary the spacing between the upper and lower roller members of the rolling mill 10.
  • the automatic jogging control ⁇ 612 can be operative to effect periodic and timed changes in the spacing of the roller members of the rolling mill lll -for correcting any d strip thickness error.
  • the time period of the changes can be controlled by the operating speed of the rolling mill 10, such as taught in copending patent application Serial No. 17,983, filed March 28, 1960. and entitled Motor Control Apparatus, by the same inventor and assigned to the same assignee.
  • the error signal ⁇ from the amplifier 2t) causes the screwdown motor 70 to correct the thickness error, whenever the error signal has a predetermined value large enough to be sensed by the voltage sensing device 60.
  • the output signal from the voltage sensing device 60 can be utilized, for example, to energize a relay for controlling the passage of ⁇ the error signal from the amplier 20 to the screwdown motor control 68.
  • the present control apparatus is operative to provide a relatively fast tension gauge control that is applicable to particularly slow speed mills that operate with a strip speed in the order of 2000 t./min. or below.
  • the workpiece thickness or gauge error signal is obtained from the thickness gauge 18 and is supplied to a preamplifier 20;
  • the output of the preamplifier 20 feeds the gate device 22 which is operative to either supply the preamplifier output signal to the integrator circuit 24 or block the passage of the preamplifier output signal.
  • the integrator circuit 24 is operative to provide an error correction signal into the strip tension control 23 for the unwind reel 14 and its motor 30 through the power or output amplifier 26 to cause a change in the strip tension between the unwind reel 14 and the rolling mill 10 in a proper direction that will reduce the workpiece thickness or gauge error.
  • the integrating circuit 24 is allowed to receive the output signal from the preamplifier 20 only if a predetermined and minimum thickness error exists as determined by the voltage level sensing device 40 connected between the output of the preamplifier device 20 and the provided NOR logic control circuitry.
  • the device 40 in this regard is operative as a voltage level detector and includes a binary signal providing circuit such as a iiip-iiop or the like.
  • the output signal from the voltage sensing device 40 has a one value in a binary sense until the error signal from the out-put of the preamplifier 20 exceeds the predetermined voltage sensing or ⁇ operating signal level of the device 40. If the error signal received from the preamplifier 20 is greater than the latter voltage sensing level, there is provided a zero value output signal to the NOR logic device 70 and the NOR device 72 within the timing circuit 7'3.
  • a NOR logic device provides a unit value output signal until at least one of its inputs receives a unit value input signal, in which case the NOR logic device provides a zero value output signal.
  • the NOR device 70 provides a unit value output signal.
  • the zero value output signal from the NOR device 74 causes the NOR device 72 of the dip-flop circuit 75 to have a unit value output signal.
  • the zero value signal of the NOR device 74 causes the NOR device 76 to have a unit value output signal since its second input as energized by the output of the ON timer is now also energized by a zero value input signal.
  • the unit value output signal from the NOR device 76 causes the gate device to open and thereby allows the passage of the error signal from the output of the preampliier 20 to the integrating circuit 24.
  • the zero value output signal from the NOR device starts the operation of the ON timer 46. After a predetermined ON time interval as initially set on for the ON timer 46, the ON timer provides a unit value output signal which is supplied to an input of the NOR device 76 to thereby terminate its unit value output signal and thusly close the gate device 22.
  • the ON timer 46 also causes the NOR device 72 to have a zero value output signal which starts the' OFF timer 48 to provide a zero value output signal and begin counting pulses received from the pulse source 5).
  • the OFF timer 48 provides a unit value output signal until its input is energized by the NOR device 72 providing a unit value output signal. After a predetermined number of pulses have been received from the pulse source 5G and counted by the OFF timer 48, it again provides a unit value output signal to an input of the NOR device 78.
  • the zero value control signal from the OFF timer 48 causes the NOR device 78 to have a unit value output signal to in turn cause the NOR device 70 to have a zero value output signal and the NOR device 74 to have a unit value output signal to further block the NOR device 76.
  • the unit value output signal from the ON timer 46 causes the NOR device 76 to have a zero value output signal which is operative to block or close the gate device 22.
  • the gate device 22 was in this manner opened for a time period determined by the ON timer 46 providing a zero value output signal and further the gate device 22 is held closed for a time period determined by the OFF timer 48.
  • the OFF timer 48 is responsive to the pulses received from the pulse source for holding the gate device 22 closed through the operation of the NOR devices 78, 70, 74 and 76 for a time period in accordance with the operating speed of the rolling mill 10 and thereby the movement of the strip 12. ln this manner any correction made in the thickness or gauge of the strip 12 by varying the tension between the unwind reel 14 and the rolling mill 10 would have enough time to physically move from the rolling mill 10 to the subsequent positioned thickness gauge 18 for measurement before an additional error correction is made.
  • the unit signal from the OFF timer 48 causes the NOR device 78 to have a zero output signal, and this in turn unblocks and allows the NOR device 70 to respond to any zero signal supplied by the voltage sensing device 40.
  • the ON timer 46 and the OFF timer 48 are per se well known devices readily available to persons skilled in this art.
  • a unit value signal that is operative to block the timer circuit 73 is supplied to an input of each of the NOR devices 70 and 72. This causes the NOR device 70 to provide a zero output signal and the NOR device 74 a unit output signal, since the NOR device 72 is now supplying a zero signal to the second input of the NOR device 74.
  • the unit signal from the NOR device 74 blocks the gate device 22 through the NOR device 76 and further resets the ON timer 46.
  • the NOR device 72 now provides a zero signal to reset the OFF ⁇ timer 48.
  • the control apparatus as shown in the figure provides a correction proportional to the actual thickness error and which allows a maximum rate of correction to be used.
  • the rate of correction of a given error is determined by the integration constant of the integrating circuit 24 and the ON time of the ON timer 46.
  • the ON time is set to be one preselected transport time period as determined by the known practical rate of movement of the strip 12 between the rolling mill 10 and the thickness gauge 18 or less.
  • the integration constant is set to correct as precisely as is practical the total error in one ON time period, and the OFF timer 48 holds the circuit from resetting the ON timer until one transport time period is over. At that time the ON timer is reset and ready for another correction cycle if necessary.
  • the integrator circuit 24 will probably reach an excessive error correction limit now and then in the course of its operation.
  • the voltage detector device 60 provides an output signal to permit the screwdown gauge control to be energized and to function normally as though no strip tension control were also being applied.
  • the screwdown motor 70 can employed for effecting the desired thickness corrections when needed.
  • the advantage of varying the strip tension is that this is in eiect a static control system in that the unwind reel motor 30 is already operating and the strip tension control 28 may be a static device in the form of a variable voltage magnetic amplier control.
  • the screwdown motor 70 when it operates to vary the spacing between the upper roller member and the lower roller member operates the mechanical screwdown and if this is done too often excessive maintenance results and repairs become necessary.
  • the present control apparatus provides the desired maximum speed of response and accuracy of strip thickness error correction while reducing the number of screwdown changes to au absolute minimum.
  • ⁇ In strip thickness control apparatus for a rolling mill including a strip thickness error correction device, the combination of an error signal source operative with the strip for providing an error signal having a value in accordance with the strip thickness error, a signal gate device operative with said error signal source, signal integration means connected between said signal gate device and the error correction device for controlling the passage of the error signal to the error correction device for the purpose of varying the thickness of the strip rolled by said rolling mill in accordance with the integral of said error signal, a timing device operative with said gate device for opening the gate device for a predetermined time duration period, and a signal magnitude sensing device operative with said signal source and connected to said timing device for controlling the operation of said timing device in accordance with the magnitude of said error signal and thereby the thickness error of said strip.
  • strip thickness control apparatus for a rolling mill including a strip tension control device, the combination of an error signal source operative with the strip for providing a strip thickness error signal, a signal gate device operative with said error signal source, signal integration means connected between said signal gate device and the strip tension control device for controlling the passage of a predetermined integral of the error signal to the tension control device for the purpose of varying the tension of the strip relative to said rolling mill and thereby the thickness of the strip rolled by said rolling mill, a timing device operative with said gate device for opening the gate device for a predetermined time duration period, and a signal magnitude sensing device operative with said signal source and connected to said timing device for controlling the operation of said timing device in accordance with the magnitude of said error signal and thereby the thickness error of said strip.
  • strip thickness control apparatus for a rolling mill including a strip tension control device, the combination of an error signal source operative with the strip -for providing a strip thickness error signal, a signal gate device operative with said signal source, signal integration means connected between said signal gate device and the strip tension control device for controlling the supply of the integrated error signal to the tension control device for the purpose of varying the tension of the strip and thereby the thickness of the strip rolled by said rolling mill, a timing device responsive to the movement ot the strip and operative with said gate device for opening the gate device for a time duration period dependent upon tlie rate of movement of the strip, and a signal magnitude sensing device operative with said signal source and connected to said timing device for controlling the operation of said timing device in accordance with the magnitude of said error signal and thereby the thickness error of said strip.
  • strip thickness control apparatus for a rolling mill including a strip tension control device, the com bination of an error signal source operative with the strip for providing a strip thickness error signal, a signal gate device and signal integration means connected between said signal source and the strip tension control device for controlling the passage of an error correction signal to the tension control device from said signal integration means for the purpose of varying the tension of the strip and thereby the thickness of the strip rolled by said rolling mill, a control signal source operative with said strip for providing a control signal having a predetermined characteristic proportional to the movement speed of the strip, a timing device responsive to said characteristic of said control signal and operative with said gate device for opening the gate device for a controlled time duration period, and a signal magnitude sensing device operative with said signal source and connected to said timing device for controlling the operation of said timing device in accordance with the magnitude of said error signal and thereby the thickness error of said strip.
  • strip thickness control apparatus for a strip rolling mill including a strip tension control device and a screwdown control device
  • an error signal source operative with the strip for providing a strip thickness error signal having a value in accordance with the dilerence between the actual strip thickness and a predetermined reference strip thickness
  • a signal gate device and a signal integration circuit connected between said signal source and the strip tension control device -for controlling the passage of the integrated error signal to the tension control device for the purpose of varying the l tension of the strip by an amount in accordance with the magnitude of said error signal
  • a timing device operative with said gate device for opening the gate device for a predetermined time duration period
  • a lirst signal magnitude sensing device operative with said signal source and connected to said timing device for controlling the operation of said timing device in accordance with a first magnitude of said error signal and thereby the thickness error of said strip
  • a second signal magnitude sensing device operative with said signal source and connected to control said screwdown control device for controlling the operation of said screwdown control device in accordance with
US30937A 1960-05-23 1960-05-23 Workpiece thickness control apparatus Expired - Lifetime US3089365A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US30937A US3089365A (en) 1960-05-23 1960-05-23 Workpiece thickness control apparatus
JP1584761A JPS3711209B1 (xx) 1960-05-23 1961-05-10
FR862560A FR1290614A (fr) 1960-05-23 1961-05-23 Appareil de contrôle d'épaisseur d'une pièce à travailler

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US30937A US3089365A (en) 1960-05-23 1960-05-23 Workpiece thickness control apparatus

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3196646A (en) * 1961-10-30 1965-07-27 Armco Steel Corp Method and apparatus for maintaining substantially constant strip gauge in a tandem mill
US3312091A (en) * 1963-05-20 1967-04-04 Hitachi Ltd Control system for material reducing apparatus
US4016735A (en) * 1975-09-23 1977-04-12 Westinghouse Electric Corporation Range control for an automatic gauge control system of a rolling mill

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2264096A (en) * 1938-08-11 1941-11-25 Gen Electric Control system
US2767604A (en) * 1953-01-19 1956-10-23 Jr Mark E Whalen Apparatus for monitoring the operation of rolling mills
US2909717A (en) * 1957-07-19 1959-10-20 Westinghouse Canada Ltd Analogue to digital converter apparatus
US2933626A (en) * 1958-10-22 1960-04-19 Westinghouse Electric Corp Sample data control apparatus
US3015974A (en) * 1958-09-18 1962-01-09 Gen Electric Automatic control system for rolling mills and adjustable dies

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2264096A (en) * 1938-08-11 1941-11-25 Gen Electric Control system
US2767604A (en) * 1953-01-19 1956-10-23 Jr Mark E Whalen Apparatus for monitoring the operation of rolling mills
US2909717A (en) * 1957-07-19 1959-10-20 Westinghouse Canada Ltd Analogue to digital converter apparatus
US3015974A (en) * 1958-09-18 1962-01-09 Gen Electric Automatic control system for rolling mills and adjustable dies
US2933626A (en) * 1958-10-22 1960-04-19 Westinghouse Electric Corp Sample data control apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3196646A (en) * 1961-10-30 1965-07-27 Armco Steel Corp Method and apparatus for maintaining substantially constant strip gauge in a tandem mill
US3312091A (en) * 1963-05-20 1967-04-04 Hitachi Ltd Control system for material reducing apparatus
US4016735A (en) * 1975-09-23 1977-04-12 Westinghouse Electric Corporation Range control for an automatic gauge control system of a rolling mill

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Publication number Publication date
FR1290614A (fr) 1962-04-13
JPS3711209B1 (xx) 1962-08-16

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