US2074873A - Continuously tensioned tandem cold mill train - Google Patents

Description

March 23, 1937. J. B. TYTUS ET AL GONTINUOUSLY TENSIONED TANDEM COLD MILL TRAIN Filed July 21, 1953 2 Sheets-Sheet 2 INVENTORS ATTORNEYS.

Patented Mar. 23, 1937 I UNITED STATES PATENT OFFICE 2,074.81: cosrmnousnr TENSIONED 'mmmu com John a. Tytus' and mini 1;. Hudson, Middleton, Ohio, assignorsltc. The American Bolling ompany,Midd 1etown, Ohio, a corporation of Ohio Application Jnly 21, 1933, sci-n1 No. 681,818

pass, excepting the first. In an exemplary operation, metal strips of sheet. width are welded together to form a continuous supply of metal. This continuous supply is sent serially through a 10 plurality of cold rolling mills arranged in tandem. The continuous supply is tensioned constantlyto predetermined degrees with respect to each passyto which end it is necessary to provide a pulling device of a continuous type at least beyond the ilnal mill in the train, and to provide tension 'controlling devices intermediate the several units in the train. The mills are arranged to exert upon the piece some tractive effort; but the use of tension makes-possible a greater reduction. of the piece per pass than could be made otherwise. It is not sufllcient merely to measure the tension of the piece be-' tween passes and to endeavor to control the speeds of the several dynamic instrumentalities in the train, in accordance with such measurement of tension. It is necessary to provide intermediate the several dynamic instrumentalities means in which the continuous supply of metal may be taken up under a constantlyapplied and constantly predetermined static tension, a sufficient amount of the metal being so taken up to take care of sporadic irregularities in the rolling operation. When this is done, and when the speeds of the several dynamic instrumentalities are controlled in accordance with the length of the strip taken up by such statictension controlling devices, it is possible to maintain on the strip with respect to each pass, predeter mined, constant tensions or differentials oftenslon. Reference is made to several oopending applications which set forth various phases of and instrumentallties useful in carrying on the general process mentioned: An application in the name of Edwin E. Hudson, Ser. No. 002,883,

I flied April 4, 1932; an application oi Edwin B. Hudson, Ser. No. 688,100, filed April 18, 1933; an application of Edwin E. Hudson, Ser. No. 688,101, filed April 18, 1933; and'an application in the names of Tytus and Hudson, Ser. No. 670,930, illed May 13, 1933. herein made to these applications, a description of the general process or of specific processes, or of the several instrumentalities employed will uously rolling an endless supply of material. The

In view of the reference not be made herein, excepting in connection with methods of rolling strip referred to require an automatic electrical control for their most effective operation. In preceding rolling operations, no necessity has arisen for such control because the sporadic irregularities in the rolling operation are not cumulative when rolling separate strips im lengths of 200 to 300 feet. However, when "rolling a continuous supply of material, such sporadic irregularities in the rolling operation are preferably compensated for, as they occur, by means of an automatic speed regulation of the various dynamic instrumentalities of the mill train.

The sporadic irregularities may be caused by Y such conditions as the following:-

(1) Variation in gauge of the strip to be rolled. The gauge may vary throughout the length of the same coil to a slight degree, and the coils of strip which are welded end to end to form the continuous supply may vary somewhat in gauge;

(2) Variation in the'drafts of the mills. It is desirable to provide an automatic control which is effective over a suiiicient. range so that any desired draft may bejhad on any particular mill.

The range of such drafts may vary from zero to or more.

(3) Variation in the adjustment of individual mills. In the operation of a mill train such as that referred'to, it may be desirable to adjust the mill screw of some of the mills in order to redistribute the draits, and to distribute work more eflectlvely between the various mills. It is therefore highly desirable to provide an automatic electrical control which will readjust the speeds of the various'units as such mill screw adjustments are made. i

(4) Variation in actual or relative speed of in dividual units due to a change in the desired finished gauge. It is highly desirable to provide an automatic control system which will take care of these variations also to permit the flexible .use

of the mill train in the rolling of metal to differ-' -vide a suitable electrical control having a wide range of overall speed control, s'uch'as a ratio of 1'to 100. The provision of means for a slow speed is highly desirable for the threading operation, whereas obviously relatively high overall speeds are highly desirable in production.

electrical control in the nature of protection for each of the several motors ofthe mill train, so that all motors are stopped by an electrical overload. Still another object of our invention is the provision of means to'stop motors in the train in the event of a breakage in the continuous sup- Another object of our invention is to provide ply of metal. Where the several automatic speed control devices are arranged to vary the speeds of preceding devices, one of our objects is to provide for the stoppage of all motors behind a break 6 in the strip, while permitting all motors ahead of the breakage to continue running to discharge meading portion of the broken strip from the These and other objects of our invention which automatic speed control hereinabove mentioned.

Fig. 3 is a side elevation of a rheostat. Fig. 4 is a detailed showing of a portion of the mechanical connectionbetween a tension control 25 device and the rheostatof a mill motor.

Pig. dshows aportion of a chain equipped with a controlling pin and employed in connection with the mechanism of Fig. 4.

various controls employed in the practice of our invention.

The particular embodiment chosen by us for the purpose of an exemplary showing herein is a I train of four tandem cold rolling mills indicated generally at A, B, D, and E in Fig. 1. These mills v are of the four-high type having small driven working rolls. .A pulling machine F is shown at the end of the train. 'This pulling machine is of the continuous type. We have indicated at C tension controlling devices located between each of the mills in the train, and between the last mill and the pulling machine I". These static tension controlling devices are capable of taking up and paying out the strip under a constant, predetermined static tension; and they are also so arranged as to control the speed either of the mill or pulling machine located immediately ahead of each tension device, or the mill located immediately preceding such device.

In order that the train may have a continuous upply of material for rolling, we provide ahead of the mill a welding device, indicated generally at l, a flash cutter 2, and a looping device 3 to permit continuous feeding of the welded strip in spite of the discontinuous process of welding. Preferably also we provide a brake 4 ahead of the mill A to lay the strip before it enters this mill.

Beyond the pulling machine I", we may locate a shear I, so that the finished band of metal may be cut apart, either into sheets or into useful lengths for coiling as at i.

The instrumentalities thus far referred to do not require more detailed description, since they are set forth in one or more of the copending applications hereinabove referred to.

For the sake of an exemplary showing, we have indicated the static tensioning device C as being of the'hydraulic type, in which the pull roll 3! is actuated by a piston I in a hydraulic cylinder.

70 We have shown the several static tension devices,

each provided with an accumulator having a piston I working in a cylinder 8, which is connected to the pressure cylinder of the static tension takeup device 0 by a pipe Ill. The accumulators may be loaded by means of tanks ll, mice with liquid 6 is an electrical wiring diagram of the aovaavs to predeterminedlevels. As shown by gauges I! the hydraulic systems may be filled bymeans of a supply line H, supplying fluid under pressure from a hydraulic pump not shown, through valves i2. The drainage of thehydraulic system may be accomplished by means of valves I3. Valves II and II may be manipulated so as to placethe pistons I ofthe various accumulators in correct positions with reference to the pistons 9 of the static tension devices when these devices are functioning properly. It will be understood that this arrangement of the static tension controlling mechanisms is exemplary only, and is set forth here as forming part of but one operative embodi ment of our invention.

The apparatus thus far described is exemplary of a tandem cold mill system in which it is possible to roll strip material indicated at IS in the form of a continuous supply without interruption, and undercontrolled and continuous tension with respect to each pass, whereby it is possible to secure a greater reduction in gauge for each mill than is possible without tension control, or with a tandem mill rolling separate strips. This is predicated on an automatic control of the several dynamic instrumentalities in the train exerted by the static tension take-up devices; and we will now describe an exemplary way in which this may be done. Figure 2 shows at It one of the mill motor rheostats used in this instance to control the speed of the mill motor immediately preceding one of the static tension devices C. The rheostat comprises the usual case containing resistances brought out to contact buttons 24, a shaft 20 bearing the contact arm 23, and a. hand-' wheel indicated at 2!. It will be understood that a rotation of the shaft 20 in one direction decreases resistance in the mill motor circuit so as to increase the speed of the motor, while a rotation of the shaft 20 in the opposite direction acts to cut down the speed of the mill motor. For the automatic operation, a sprocket 22 is rotatably mounted upon the shaft 21-, and is arranged to be driven by means hereinafter to be described, in. accordance with the length of strip taken up in thestatic tension device C'. The hand-wheel 2| and this sprocket are provided, respectively, with clutch members indicated at 220,. The hand-wheel 2i is slidably but nonrotatably mounted on the shaft 20. When the clutch parts are engaged as shownv in Fig. 3, a rotation of the sprocket 22 will produce a rotation of the shaft 20. The hand-wheel may, however, be pulled outwardly to the position shown in dotted lines at 2 i when this is done, the sprocket 22 is disconnected from the shaft 20, and the 'rheostat'may be manipulated or'adjusted by the hand-wheel 2|.

The sprocket 22 is connected by means of a chain 28 to a sprocket 25, non-'-rotatably mounted upon a shaft 21 shown in Fig. 4. A sprocket 29 is rotatably mounted on this shaft and carries a chain III, to one end of which a weight ii is attached. The other end of the chain is connected by means of a cable 32 passing over a sheave 33 to an arm 34 mounted for movement in connection with the movable roll I! of the static tension take-up device; It will be clear that the movements of the movable roll of this device indicate the amount of strip taken up by the movable roll under static tension. Since the movable roll is driven upwardly in the embodiment shown, if it risestoo far, this indicates that too much strip is being taken up by the device and necessitates either a diminution in the speed of the foregoing mill, or an increase in the speed of the succeeding mill, depending upon. which mill is to be controlled thereby. Consequently if movements of the chain 30 are made to control move- 5 ments of the mill motor rheostat I3, such speed control may be eifected. It is advisable, however. to provide for some lost motion in this drive, so that there can be an intermediate zone in which sporadic movement of the tension take-up roller 35 will not directly afiect a speed control. We accomplish this by mounting segmental members 23 non-rotatably upon the shaft 21, and'by providing pins 36 extending beyond the edges of the chain 30, and adapted tocontact these segmental members. When one of the pins strikes the segmental members, then the shaft 21 will be turned upon further movement of the chain; but until this happens there will be no movement of the shaft 21 because the sprocket 23 is rotatably mounted thereon. Two speed ranges are. indicated in Fig. 2 at 31 to 38 for the decrease speed range, and 38, 39 for the increase speed range.

By the construction shown in these several figures, the position of the roll 35 of the tension take-up device will act to increase or decrease the speed of the motor of the mill immediately preceding or immediately following the .tension take-up.

device. so The instrumentalities so far described do not scribed in the copending applications to which reference has been made: but; they have been described here in order that the operation of our invention may be thoroughly understood.

Briefly, in the carrying out of our invention, we provide means for effecting an overall speed control of all of the dynamic instrumentalltles in our mill train, irrespective of and without ailecting the automatic speed control referred to. This enables us either to slow down our train for threading, or to speedit up after threading in order to bring it to the proper production speed.

Essentially we do this by providing separate motors for each of the dynamic. instrumentalities in the train, controlling these motors automatically as aforesaid, but also controlling them manually by varying concurrently the power supplied to each. A convenient method of doing this is V I by providing a generator driven by a motor connected to the power lineQor by any other suitable prime mover, and then controlling the power output of the said generator by suitable means. We have shown in Fig. 6 the motor at G connected to a generator marked H. This generator sup- 5 plies power to. the several mill motors indicated at A B D and E in Fig. 6, and to the motor *of the pulling device indicated-at F We have shown an excitor K for the field windings of the generator H, the said excitor being controlled by a suitable rheostat, or the like, IO0I located in I a position of convenient access to the operator. The operators position is shown at 40 in Figure 6. Standing in this position the operator can control the speed of the motor F of the puller F by means of the hand-wheel 2I of the rheostat 343 of such motor. This rheostat is indicated'diagrammatically in this figure at 343. A control of the speed of the motor F will, in turn, control the speed of all of the other motors in the train, automatically through the action of the tension take-up devices 0. Suitable trip breakers are provided for each of the motors'indicated respectively at 502, 602-, 102, 802, and 902. controlling circuits for these breakers derive their power from power leads 300, as will be clear from differ from certain of the instrumentalities de-.

The

the diagram. By opening a switch 345, the trip breaker 302 for the motor F can be tripped by power derived from the power lines 300, through leads 3 so as to stop the puller motor F The trip breakers of the other motors in the train are .arranged .for actuation by means of switches hereinafter to be described, which switches are arranged to throw oil the strip breakers. These switches are indicated at SSI, SS2, and etc. and are switches adapted to be maintained closed by the strip and to open automatically upon strip breakage. They may conveniently be in the form of switches having'arms bearing against the strip itself, although they may likewise be arranged to be actuated by the static tension controlling devices, or by theacc'umulators connected therewith. fIhe switch SSI, for example, makes or breaks the circuit represented by leads 304, which is the tripping circuit for the trip breaker 502 of the mill motor A By following the leads 304. however, it will be seen that these leads so through switch mechanisms in connection with the devices SS2, SS3 and SS4. Should a breakage of the strip occur, say. at the switch 833, this would not only trip the breaker 502 connected with the mill'motor A, but also the breaker 602 (through a circuit represented by leads 3| 4) connected with the mill motor B and also the breaker 102 connected with mill motor D through a circuit represented by the leads .324. In this way a breakage of the strip occurring at any particular point in the train is made immediately to stop all preceding motors; but it does not stop suceeding motors, because the circuits to such motors are not connected through preceding strip breakers. The switch mecha nisms SSI and etc. are, however, 'connectedfor magnetic operation through leads II M to a switch II00 located at the operators position 40. By closing this switch, all of the strip switches SSI, and etc. can be held by the operator in the closed position, while the mill train is being threaded. When the mill train has been threaded and placed in operation, then the strip I8 itself will act to maintain the switches SSI and etc.

closed until a breakage in such strip occurs.

' As explained, a rheostat IO0I located in the operators position controls, through leads I000 and I002, the excitor, from the excitor K to the enerator H. When the mill train has been .323 and 333 (which will be understood as rheastats similar to the rheostat I9 in Fig. 2) by the several static tension devices C diagrammatically indicated in Fig. 6. The rheostat 343 of the pull. er motor F will be controlled by the operator through the hand-wheel 2i thereof. Such control will be usually eflective throughout. the normal operating speed rangeof the mill train when it is running in production. A variation of the field strength of the generator H, whereby the overall speeds of all of the instrumentalities is controlled, may be used to vary speed in producticn, but is of particular value when lower speeds are required during the operation of threading the mills.

For the electrical protection of the various cult breakers, each-oi the ordinary type, have overload protection; but they are also provided with additional contacts connected into a circuit represented by the leads III to trip a main cirs cult breaker I, connected to the power leads from the generator H, should any of the circuit breakers 5", I, etc. open, due to electrical overload.

In the event that a strip breaks in the mill, all mills or other dynamic devices behind the break I are stopped, while all of the motors ahead of the break continue to run. removing the unbroken portion of the strip from the mills.

Preferably all of the trip breakers I", I, 16 etc. are provided with additional contacts controlling indicator lines'lll, 8, etc. located near the individual motors. There is also preferably an indicator light 403, connected to the main trip breaker I, by circuit 2.

Thus by our invention we have provided a means for varying the overall speed of all of the dynamic instrumentalities in the mill train without afiecting the automatic speed cmtrol. We have provided for the stoppage of the motors of all dynamic instrumentalities when an electrical overload trips the circuit breaker connected to any one of them. 2 We have also provided means whereby a breakage of the strip will act to stop mills or other dynamic instrumentalities located ahead of the break in the train. It will be understoodthatthemechanismwehavedisclosedis exemplary only of our invention, and may be modified without departing from the spirit thereof. It will also be understoodwthat instead of employing a series of mills and a final puller, pulling devices may be located between of the mills in the train, and may be provided with motors as are the mill motors in the train.

The term "static tension devices' as used hereinafterinthe claimsshouldbeconstruedtomean devices operating to maintain a substantially invariable tension in the strip or rolling piece irrespective of the variations in the elongation thereof or variations in the length thereof be- 45 tween dynamic instrumentalitiea.

Having thus described our invention, what w claim as new and desire to secure by Letters Pat ent, is: I

1. In a rolling mechanism the combination of so interspaoed driven mills, a pulling device located between said mills, and. static tension maintaining devices located between each .mill and said pulling device, each said static tension device adapted to control the speed of. an adjacent mill, 55 or pulling device respectively and spective of said automatic eaitrol for varying the overall speed of each of said mills andflid puller ooncurrentlv. 2.1a a rolling mechanism the combination 0! so interspaoed driven mills forming a tandem train,

at least one pulling device located at the endv oi said train, static tension devices located between each mill and each adjacent mill or puller,

. each of said static tension devices adapted to con-.

as trol the speed of an adjacent mill or pulling device, and means irrespective of said'control for varying the overall speeds of each oi said mills and pulling devices concurrently.

3. In a rolling mechanism the combination of 7o interspaoed driven mills forming a tandem train,

at least one 'pulling device located at the end of said train, static tension devices located between each mill and each adjacent mill or puller, each of said static tension devices adapted to control rs the speed of an adjacent mill or pulling device,

smears and means irrespective of said control for varying the overall speeds of each of said mills and pulling devices concurrently, said means comprising a generator connected to supply power to said several mills and pulling devices, and means for controlling the voltage of the power so apand means irrespective of said control for vary ing the overall speeds of each of said mills and pulling devices concurrently, said means comprising a generator connected to supply power to said several mills and pulling devices, and means for controlling the voltage of the power so applied, said means comprising means for controlling the field strength of said generator.

5. In a rolling mechanism the combination of interspaoed driven mills forming a tandem train, at least one pulling device located at the end of said train, static tension devices located between each mill and each adjacent mill or puller, each of said static tension devices adapted to control the speed of. an adjacent mill or pulling device, and means irrespective of said control for varyingtheoverallspeedsofeachorfsaidmillsand pulling devices concurrently, said means comprising a generator connected to supply power to said several mills and pulling devices, means for controlling the voltage of the power so applied,

and means for stopping all of said mills and pullers upon an electrical overload of any one of 6.. In a metal rolling device includln8 dynamic instrumentalities. a train of tandem cold mills, a pulling machine located at the end of said train, static tension devices located between each of said mills and between the final mill and said pulling device, said static tension devices arranged to take up, under a predetermined force, a portion of a continuous strip fed through said train, means for causing said static tension takeup devices to control the speed of an adjacent dynamic instrumentality in said train, means for simultaneously controlling the overall'speed of each of said dynamic instrumentalities in said train, irrespective of said automatic speed control, said means comprising a generator connected to supply power to said several dynamic instrumentalities, means for controlling the-voltage of the power so supplied, and means for stopping all of said dynamic instrumentalities behind a breakage in the strip in the direction of travel of the sheet upon the occurrence of such breakage.

7. In a metal rolling device including dynamic instrumentalities, a train of tandem cold mills, a pulling machine located at the end of said train, static tension devices located between each of said mills and between the final mill and said pulling device, said static tension devices arranged to take up, under a predetermined force, a portion of a continuous strip fed through said train,

means for causing said static tension take-up the sheet upon the occurrence of such breakage,

said means comprising switching means for each of said instrumentalities arranged to be actuated by the tension in said strip, said switches so con- L nected together that the tripping of any one thereof will trip all switches in the train ahead of said one.

8. In a metal rolling device including dynamic instrumentalities, a train of tandem cold mills, a pulling machine located at the end 01' said train.

static tension devices located between each of said mills and between the final mill and said. pulling device, said static tension devices arranged to take up, under a predetermined force, a portion of a continuous strip fed through said train, means for causing said static tension take up devices to control the speed of an adjacent dynamic instrumentality in said train, means for simultaneously controlling the overall speed of each of said dynamic instrumentalities in said train, irrespective of said automatic speed control, said means comprising a generator connected to supply power to said several dynamic instrumentalities, means for controlling the voltage of the power so supplied, and means for stopping all of said dynamic, instrumentalitiesahead of a breakage in the strip, upon the occurrence of such breakage, said means comprising switching means tor each 01 said instrumentalitics arranged to be actuated by the tension in said strip. said switches so connected together that the tripping of any one thereof will trip all switches in the train ahead of said one, and means-tor setting all of said instrumentalities during the threading operation.

40 9. In arolling apparatus including dynamic instrumentalities, the combination of a train of tandem mills, means located at least beyond the,

final millifor exerting continuous tension upon a continuous strip passing through said mills, means located between all of the dynamic instrumentalities in said train for taking up said strip under a constant, predetermined static tension, means for-automatically controlling the speeds of said several instrumentalities in accordance with 5 the length of strip so taken up, means for stopping said instrumentalities upon a release of said tension, and means for rendering said last mentioned means inoperative during thethreading 01' said train." 10. In a rolling apparatus including dynamic .instrumentalities, a train of tandem cold mills, means forexerting a pull continuously on a continuous strip passing through said train and located at least beyond the final mill therein,

w each of said dynamic instrumentalities being provided with'a separate-electric motor, circuit ,breakers attached to each of said motors, a main circuit breaker, contacts connected to each. or

the other circuit breakers for tripping said main 5 circuit breaker, supplementary circuit breakers attached to each of said motors, and means for selectively tripping said last mentioned circuit breakers uponthe occurrence of a break in said strip. I V "M" Q 70 11.'-In a rolling apparatus including dynamic instrumentaiities, a train of tandem cold ,mills,

means for exerting a pull continuously on a condynamic instrumentalities.

tinuous strip passing through said train and located at least beyond the iinal mill therein. each of said dynamic lnstrumentalities being provided with a separate electric motor, mutually interconnected,circuit breakers ior tripping said main circuit breaker, supplementary circuit breakers attached to each of said motors, means for selectively tripping said last mentioned cirs cult breakers upon the occurrence of a break in said strip, said last mentioned means comprising strip actuated switches, means for causing each or said switches to break the circuit of each preceding switch, means for rendering said switches inoperative, and means for simultaneously varying the voltage of current applied to each of said motors. q

12. In a rolling apparatus including dynamic instrumentalities,-a train of tandem cold mills, means for exerting a pull continuously on a continuous strip passing through said train and located at least beyond the final mill therein, each 01 said dynamic instrumentalities being provided with a separate electric motor, mutually interconnected, circuit breakers for tripping said main circuit breaker; supplementary circuit breakers attached to each of said motors, means for selectively tripping said last mentioned circuit breakers upon the occurrence of a break in said strip, said last mentioned means comprising stripactuated switches, means for causing each of said switches to break the circuit or each preceding switch; means for rendering said. switches inoperative. means for simultaneously varying the voltage of current applied to each of said motors, said last mentioned means mm prising a generator, means for driving said generator, and means for varying the field strength of said generator,

13. In a rolling apparatusincluding dynamic instrumentalities, a train of tandem cold mills, means for exerting a pull continuously on a continuous strip passing through said train and located at least beyond the final mill therein, each or'said dynamic instrumentalities being provided with a separate electric motor, mutuallyv interconnected, circuit breakers i'or tripping said main circuit breaker, supplementary circuit breakers attached to each of said motors, means for selectively tripping said last mentioned circuit breakers upon the occurrence of a break in said strip, said last mentioned" means com-'- prising strip actuated,switches, means for causing each oi said switches to break the circuit of generator, means for taking up said strip under- .a predetermined static tension between each of said dynamic instrumentalities, and means for causing said last mentioned means to eii'ect automatically, a control of the speed 01 an adjacent dynamic instrumentality, and means forimanually controlling the speed of one of said instrumentalities which, through said automatic speed control, will control the speed of all or said other com: 3, runs. nnwm a. HUDSON.

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