US3538729A

US3538729A - Control system for strip coiling apparatus

Info

Publication number: US3538729A
Application number: US652454A
Authority: US
Inventors: John D Sterrett Jr
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1967-07-11
Filing date: 1967-07-11
Publication date: 1970-11-10
Anticipated expiration: 1987-11-10
Also published as: FR1576668A; GB1233057A

Description

Nov. 10, 1970 AG NETIC MPLIFIER J. D. STERRETT, JR

CONTROL SYSTEM FOR STRIP GOILING APPARATUS Filed July 11, 1967 PINCH ROLL COUNTER RESET 1 MANDREL UP COUNTER WITNESSES- GATE MANDREL DOWN COUNTER RESET J Yrs DIG TAL TO ANALOG CONVERTER GENERATOR CONTROL INVENTOR ohn D. Sterrett,Jr.

ATTORNEY United States Patent 3,538,729 CONTROL SYSTEM FOR STRIP COILING APPARATUS John D. Sterrett, Jr., Williamsville, N.Y., assiguor to Westinghouse Electric Corporation, Pittsburgh, Pa., a

corporation of Pennsylvania Filed July 11, 1967, Ser. No. 652,454 Int. Cl. B30b 15/00 US. CI. 7230 1 Claim ABSTRACT OF THE DISCLOSURE Described is apparatus for controlling strip coiling apparatus whereby the trailing end of the strip will come to rest at a preselected angular position about the mandrel on which it is coiled. The invention finds utility, for example, in controlling a downcoiler for a hot strip rolling mill where it is desired to position the end of the strip beneath the coil prior to its removal from the mandrel.

BACKGROUND OF THE INVENTION Although not limited thereto, the present invention is particularly adapted for use with continuous hot strip rolling mills. In such mills the strip, as it proceeds from the last tandem finishing stand, is carried over a long table, called the runout table, and thence through pinch rolls to a downcoiler where it is wound into coils for shipment or further processing. When the hot strip has been coiled on such a downcoiler mandrel, it is necessary to position the trailing end of the strip under the coil before the coil is stripped from the mandrel. That is, when the coil is stripped from the mandrel, it is deposited onto rollers or guideways where it is conveyed, along a path extending parallel to the coil axis, to some remote location. If the trailing end of the strip is not beneath the coil such that the weight of the coil will restrain it on the aforesaid guideways, the end will possibly unwind or flop around, an obviously undesirable condition.

SUMMARY OF THE INVENTION As an overall object, the present invention provides a control system for strip coiling apparatus which insures that the trailing end ofthe strip will come to rest at a preselected angular position about the mandrel on which it is coiled.

More specifically, an object of the invention is to provide a control system for a hot mill downcoiler which positions the trailing end of the strip beneath the coil such that when the coil is stripped from the mandrel and deposited on guideways, the trailing end will be constrained from unwinding.

In accordance with the invention, means are provided for sensing passage of the trailing end of the strip past a detecting device, together with means operative essentially just before passage of the trailing end of the strip past the detecting means for producing a first electrical signal indicative of the number of revolutions of the coiler mandrel required to wind on the coil the length of the strip between the detecting means and the coil. Further means are provided for producing a second electrical signal when the end of the strip passes the detecting means. When the trailing end of the strip passes the sensing means, the aforesaid first and second electrical signals are applied to apparatus which causes the mandrel to first rotate through a number of revolutions necessary to wind the remaining length of strip onto the coil, plus a predetermined arcuate distance, and then stop.

Preferably, the strip end detecting means comprises a current or the like sensing means on a drive motor for Patented Nov. 10,1970

pinch rolls ahead of the coiler. The strip usually makes approximately a tangential contact with the coil on which it is being wound at the top thereof, while the aforesaid predetermined arcuate distance is sutlicient to rotate the trailing end of the strip from the point of tangential contact at the top of the coil to a position beneath the coil. As will be understood, the number of revolutions of the coiler mandrel required to wind the length of the strip between the coiler and the pinch rolls is dependent upon the diameter of the coil; and this diameter will gradually increase as the strip is being wound. Accordingly, the diameter of the coil is continually monitored. This is accomplished by means of first and second counters, the first of which counts pulses proportional to the number of revolutions of the coiler mandrel and the other of which counts pulses proportional to the number of revolutions of the pinch rolls.

The pinch roll counter is preset to count a fixed number of pulses indicative of the length of the strip between the pinch rolls and the coiler. Each time the predetermined count of the pinch roll counter is reached, it resets itself and also resets the aforesaid first counter which is counting the number of revolutions of the man drel coiler. The count of the first counter, upon passage of the trailing end of the strip through the pinch rolls, is then preset into a mandrel downcounter which counts down in an amount equal to the distance between the pinch rolls and the coiler plus the predetermined angular distance required to position the trailing end of the strip beneath the coil. After the mandrel down-counter has counted down, therefore, the trailing end of the strip will be at the bottom of the coil and the drive motor for the mandrel down-counter will be stopped.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIG. 1 is a schematic illustration of a downcoiler showing the guideways on which the coil is transported at the completion of a coiling operation; and

FIG. 2 is a schematic circuit diagram illustrating the control system of the present invention for positioning the trailing end of strip material beneath the coil as shown in FIG. 1.

With reference now to the drawings, and particularly to FIG. 1, a hot strip downcoiler is schematically illustrated and includes a mandrel 10 driven by means of a suitable motor, not shown, and around which steel strip material 12 is wound. During the coiling process, the strip is normally constrained by means of rollers 14 which are movable radially inwardly or outwardly. The rollers 14 are normally held in engagement with the coil during a coiling operation in order to constrain the strip, but are permitted to move radially outwardly as the coil expands.

After the coil is wound, it is normally deposited onto skids or guideways 16 and 18 and then pushed along the guideways 16 and 18 to some remote location for further processing. However, before the coil is positioned on the guideways 16 and 18, it is necessary to position the trailing end of the strip, indicated at 20, beneath the coil in order that it will rest on the guideways 16 and 18. Otherwise, if the trailing end 20 is at the top of the coil, for example, it will flop around and the coil will begin tounwind. In the past, the trailing end of the coil 20 was normally positioned at the bottom of the coil by manual control on the part of the operator. Needless to say, this is a somewhat cumbersome and time-consuming operation.

The apparatus of the present invention for automatically positioning the trailing end 20 beneath the coil at the completion of a coiling operation is shown in FIG. 2. It will be noted that the strip 12 passes between a pair of

pinch rolls

22 and 24 before it is wound about the mandrel 10. The pinch roll 24, for example, is driven by means of motor 26. Similarly, the mandrel 10 is driven by means of a drive motor 28 provided with an external control winding 30. The motor 28, in turn, is driven by a direct current generator 32 connected, in the usual case, to a three-phase alternating current motor 34. The generator 32 is provided with a control winding 36 which is, in turn, connected to a generator control circuit 38. Control of the generator 32 via winding 36 and circuit 38, therefore, will also control the motor 28 in accordance with usual practice.

When the mandrel 10 comes to rest at the completion of a coiling operation, the trailing end of the strip should preferably be midway between points A and B shown in FIG. 2. Furthermore, if the trailing end of the strip rotates beyond point A, as when the mandrel is rotating too fast to stop at the desired position, it will be necessary to rotate the mandrel through an additional almost 360".

Note that when the trailing end of the strip 12 passes through the

pinch rolls

22 and 24, the maximum distance through which the circumference of the coil should rtate is:

where 0 is the distance, D, expressed as an angle, between the bite of the pinch rolls 40 and the point 42 of essentially tangential contact of the strip 12 with the coil, and

is the arcuate distance between the point of tangential contact 42 and point A. Notice that 0 may be several revolutions.

The value of (94- is determined by means including a tachometer pulse generator 44 connected to the mandrel 10. The output pulses from the generator 44 are, in turn, applied as input pulses to a mandrel up-counter 62. It will be appreciated that the number of revolutions of the mandrel required to coil a given length of strip will be dependent upon the diameter of the coil, the greater the diameter, the fewer the number of required revolutions. Therefore, in order to rotate the mandrel 10 through an arcuate distance equal to (0+), it is necessary to continuously monitor the diameter of the coil. This is accomplished by means including a second tachometer pulse generator 47 connected to the pinch roll 24. The output of the tachometer generator 47 will be a series of pulses, the number of which is proportional to the length of the strip passing between the pinch rolls. These pulses are applied to a pinch roll counter 50 which will produce an output on lead 52 after it has counted a number of pulses corresponding to the distance D, or 0, between

points

40 and 42. When the pinch roll counter 50 thus reaches the count corresponding to the distance D, it resets itself via lead 54 and again begins counting until it reaches a count corresponding to the distance D. At the same time, the output pulse on lead 52 resets the mandrel up-counter 62 and enables a gate 58 to transfer the count from counter 62 to a mandrel down-counter 48.

Let us assume, for example, that at the beginning of a coiling operation with the diameter of the coil relatively small, the pulse generator 44 produces 1000 pulses during the time required to wind a length of strip equal to the distance D. The mandrel up-counter 62, therefore, will count 1000 pulses until it is reset by a pulse on lead 52, whereupon it will transfer the count to the mandrel downcounter 48 which is preset to the count of the mandrel up-counter 62 plus a number of pulses necessary for the mandrel to rotate through the distance or arc This latter number, of course, will be fixed regardless of the diameter of the coil. For purposes of illustration, it will be assumed that the number of pulses produced during rotation through the angle as is 50. Consequently, under the circumstances described, the count stored in counter 48 is 1050.

Now, as the diameter of the coil increases, the number of revolutions required to wind a length of strip equal to D decreases. Let us assume, for example, that the number of pulses produced at a larger diameter by the pulse generator 44 during winding of a length of strip equal to D is 500. Under these circumstances, the mandrel up-counter 62 will count up to 500, whereupon a pulse on lead 52 will reset it and open gate 56 to transfer the count to the mandrel down-counter 48.

The count stored by counter 48 will now be 550 rather than 1050. In this manner, it can be seen that as the coil diameter increases during a coiling operation, the count stored in the mandrel down-counter 48 will be periodically decreased. This action will continue with the count of

counters

62 and 48 being changed periodically (i.e., each time the counter counts up to the distance D and produces an output pulse) until a gate circuit 58 is opened or enabled to apply pulses from generator 44 to the mandrel down-counter 48.

The gate 58 is opened by means of a current sensing magnetic amplifier connected across one of the input leads to the drive motor 26. In this manner, when the trailing end of the strip passes between the pinch rolls 22 and 24 and the current input to the motor 26 drops, the magnetic amplifier 60 will produce an output on lead 46 to open the gate 58. It should be understood, however, that the magnetic amplifier 60 is only one type of device for sensing the passage of the trailing end of the strip beyond the point at which the distance D begins. That is, photocells, magnetic detecting devices or the like can be used with equal effectiveness to produce a signal which opens the gate 58.

After the gate 58 opens, the pulses from pulse generator 44 are applied to the mandrel down-counter 48 which proceeds to count down from the value (t9+). The output of the mandrel down-counter 48, in turn, is applied to a digital-to-analog converter and function generator 64 which will apply a control signal to the gen erator control circuit 38 via lead 66 to stop the generator 32 and motor 28 when the count of counter 48 indicates that the count has been decreased almost to Zero. In the operation of the digital-to-analog converter 64, its output will gradually decrease as the counter 48 counts down whereby the rotational speed of the motor 28 and mandrel 10 also gradually decreases to the point where the mandrel stops with the trailing end of the strip ahead of point A. At this time (i.e., with the mandrel stopped), the count of counter 48 will not be exactly zero. If, however, the count of counter 48 should reach zero, indicating that the trailing end of the strip has passed point A, the counter 48 will be reset via lead 68 to rotate the mandrel 10 through something less than 360 whereby the coil will come to rest with the trailing end of the strip preferably midway between points A and B.

Thus, essentially just before the trailing end of the strip passes through the pinch rolls 22 and 24, the last sample of the distance D is taken and the mandrel upcounter '62 produces a first output signal (which can be on a plurality of leads) indicative of the number of revolutions of the mandrel required to wind a length of strip equal to the distance D. When the trailing end of the strip passes through the

rolls

22 and 24, a second electrical signal is produced by circuit 60; and these two signals activate the down-counter 48, converter 64 and circuit 38 to rotate the mandrel through a number of revolutions equal to or slightly less than (H+), whereupon it stops.

Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit re quirements without departing from the spirit and scope of the invention. In this respect, it will be apparent that the two

counters

46 and 48 could be combined into a single counter which initially counts up and thereafter counts down with the same overall effect. Furthermore,

the digital components utilized herein could be readily replaced with analog components with the same overall effect.

I claim as my invention:

1. In apparatus of the type in which strip material passes strip presence detecting means and thence to a rotating mandrel about which it is Wound into a coil, having the improvement for stopping the rotation of said mandrel and the coil wound thereon, with the trailing end of the strip coming to rest at a predetermined arcuate distance beyond the point at which the entering strip makes tangential contact with the coil, said improvement comprising first means operative in relation to the passage of the trailing end of the strip past said strip presence detecting means for determining the number of revolutions of the mandrel required to wind the length of the strip between the strip presence detecting means and said tangential contact point, said first means comprising first pulse generating means connected to said strip presence detecting means, second pulse generating means connected to said mandrel, first counting means for counting a predetermined number of pulses from said first pulse generating means, second counting means for counting pulses from said second pulse generating means, resetting means for resetting said first and second counters after said first counting means has counted said predetermined number of pulses, second means for indicating when the end ofv i the strip passes said strip presence detecting means, third counter means preset to count a number of pulses from the second pulse generator means proportional to said predetermined arcuate distance, gating means responsive to said second means for applying pulses from said second pulse generator means to said third counting means to cause said third counting means to count down from the count stored therein, and means for decelerating said mandrel from operating rotational velocity to zero velocity, comprising digital-to-analog converter means connected to the output of the third counting means, the converter producing an analog output signal of decreasing magnitude as the third counting means counts down, drive motor means for said mandrel, control circuitry for energizing said drive motor means, and coupling means for applying said analog output to said control circuitry to cause said drive motor to slow down and then stop when the third counting means approaches substantially zero count reading.

References Cited UNITED STATES PATENTS 1,882,219 10/1932 Harwood et al 72-25 3,028,114 4/1962 Asbeck 72148 3,208,683 9/1965 Thompson 242-57 RICHARD I HERBST, Primary Examiner