US2003160A - Method and apparatus for rolling uniform gauge stock - Google Patents

Description

May 1935 I A. J. TOWNSEND ET AL 2,003,160

METHOD AND APPARATUS FOR-ROLLING UNIFORM GAUGE STOCK Filed Nov. 18, 1932 3 Sheets-Sheet 1 Fig: l

INVENTOR 8 Adi'owm'end 1?. SI/Ville! BY ATTORNEYS y 1935- 4 A. J. TOWNSEND ET AL 2,003,160

METHOD AND APPARATUS FOR ROLLING UNIFORM GAUGE STOCK Filed Nov. 18, 1932 3 Sheets-Sheer, 2

INVENTORS I ATTORNEYS A. J fawn/send,

May 28, 1935-. A. J. TOWNSEND ET AL 6 METHOD AND APPARATUS FOR ROLLING UNIFORM GAUGE STOCK Filed Nov. 18, 1932 3 Sheets-eSneet 3 INVENTORS Aglbwnsend EJ/lll'llh BY ATTORNEYS Patented May 28, 1935 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR ROLLING UNIFORM GAUGE STOCK Arthur J. Townsend and Edward S. Miller, Canton, Ohio, assignors, by mesne assignments, to Harry M. N angle and Arthur J. Townsend, both of Canton, Ohio Application November 18, 1932, Serial No. 643,188

16 Claims.

' the like to uniform gauge. i

The usual hot roughing and finishing rolling of hot rolled strips has been accomplished by utilizing a reversing rough rolling-mill in which the rough rolling of a slab is performed by passing a slab alternately back and forth through the reversing mill; after which the rough rolled slab is finish rolled in several stands of mills arranged in tandem to make hot rolled strips.

The output of a reversing rough rolling mill is somewhat restricted but the operation of the same is quite flexible; and due to the fact that alternate ends of the slab being rolled enter the mill alerna'tely, the roughing operation delivers a piece which is accurate to gauge from end to end. 4

Quite recently, in order to substantially increase the output of roughing and finishing hot mills, continuous roughing and finishing mills, comprising in certain cases some nine stands of hot mills arranged in tandem, have been used to make hot rolled strips or stripsheets from slabs.

In such continuous roughing mills, the first four or five stands have been termed the roughing or break-down stands and the succeeding five or four stands have been termed the finishing stands.

The forward end of the material being rolled enters each stand of the continuous train first, in carrying out a continuous hot roughing and finishing operation to make strips or stripsheets, so that the rear end of the material being rolled is delivered to the finishing stands, and particularly. to the last finishing stand, at a substantially greater gauge than the front end of the material.

This variation in gauge from end to end of the material, being rolled occurs because the rear end of the material has cooled to a lower temperature, as it reaches each stand of the continuous train of rolls, than the forward end of the material being rolled as the forward end reaches, each roll stand.

If a variation in gauge of a hot rolled strip or stripsheet which may be from 300 to 800 feet, more or less, in length, is once established, it is diificult, if not impossible to eliminate the gauge variation in subsequent rolling operations.

As a result of this condition of variation in gauge of strips orstripsheets hot rolled in a continuous roughing and finishing mill, it has been found necessary to reduce the finished length of the material being rolled so that variations in gauge from end'to end of the strip or. stripsheet may be maintained within commercially required limits.

The reduction of the finished length of hot rolled strips or stripsheets materially handicaps the subsequent performance of continuous pickling and cold-rolling of the material, so that in many cases it has been necessary to weld short pieces of hot rolled strips or stripsheets together for subsequently performing continuous pickling or cold rolling operations, in order to secure a length of material which will permit greater economy in carrying out such operations.

It has been proposed to automatically compen- Sate for gauge variations of material delivered from a mill by gauging the material as it is delivered from the mill with a gauging device, which is electrically connected with the screw down motors, to open or close the gap between the rolls as gauge variations occur in the material delivered. While it may be possible, to a limited degree, to gauge with a gauging device material delivered on the delivery side of a slowly operating cold mill, it is impractical if not impossible to accurately gauge hot material as it is delivered from the delivery side of 'a continuous hot mill, particularly at the delivery side of the last mill stand,.where the speed of the material may be from 500 to 1000 feet per minute.

Accordingly, it is an object of the present invention to provide a method of and apparatus for automatically compensating for or eliminating gauge variations existing from end to end in material being rolled in a continuous rolling mill. Y

It is a further object of the present invention to anticipate the variation in gauge, which cumulatively occurs from 'end to end of strips or stripsheets being rolled in acontinuous rolling mill, and to correct in a cumulative manner the gauge variation, toproduce uniform gauge material.

Moreover it is an object of the present invention to automatically adjust the rolls of a rolling mill, by interconnected mechanical and electrical means, preferably synchronized with or operated by the main mill drive motor, -to compensate for gauge variations which may exist from end to end in the material being rolled, while the material is passing through the mill.

The variation in gauge which may occur from end to end of a piece being rolled in a hot mill' progressively'thicker from its forward end to its rear end. v

It is therefore a further object of the present 'invention to compensate for such a gauge variation in continuous hot rolling by' lowering the 1 upper roll at predetermined intervals 8, predetermined amount in coordination with the revolutions made by the rolls, and by adjusting the amount that the upper roll is lowered and/or the intervals of lowering, in accordance with the total gauge correction to be made to produce uniform gauge material.

It is likewise an object of the present invention to provide for the adjustment of the mill screws by automatic and interconnected mechanical and electrical devices to lower the mill screws 3. de-

sired amount progressively at intervals to detion of the mill drive means, or the rolls driven thereby, or with the movement of the material through the rolls, to compensate for variations in the gauge of material being rolled by the mill while the material is passing therethrough.

In certain cases, in carrying out a cold rolling of strip or stripsheet material, gauge variation may occur in the finished material, and it is comprehended within the scope; of the present invention to automatically compensate for or eliminate gauge variations existing from end to end in material being rolled in a continuous mill'whether the operation is a hot rolling operation or a cold pensating for or eliminating gauge variati ns.

existing from end to end in material being ro ed in a rolling mill, and to provide means for adjusting the compensating means to enable the handling of materials of different delivered lengths and of materials having different rates of gauge variations. r

And finally, it is an object of the present invention to avoid the difliculties of gauge variation experienced in prior rolling practice by providing a method of and apparatus for compensating for' gauge variations existing from end to end in material being rolled in a rolling mill, which methods and apparatus may be readily utilized in connection with standard existing equipment.

These and other objects may be obtained by the methods and apparatus, a preferred embodiment of which is shown in the drawings and hereinafter described in detail and claimed, whichmay be stated in general terms as including in a rolling mill having a screw down motor and a drive motor, means for operating the screw down motor automatically to adjust the gap between the mill rolls a predetermined amount at predetermined intervals as the material being rolled passesthe material from the rolls to re-establish the original roll gap setting, and there being means provided for adjusting the interval of and/or amount of roll adjustment.

In the drawings,

Figure 1 is an elevation view of the entering side of a rolling mill stand equipped with thepresent improvements;

Fig. 2 is an enlarged side elevation section of the roll stand shown in Fig. 1, taken on the line 2-2, Fig. l; and

Fig. 3 is a wiring diagram, including diagrammatic illustrations of a mechanical switch operating means, of the interconnected mechanical and electrical means utilized in carrying out the present invention.

Similar numerals refer to similar parts throughout the drawings. 1 A four high roll stand is generally indicated in Figs, 1 and 2 at 4, which may preferably be the last roll stand of a tandem arranged continuous rolling mill and may include the usual mill frame members 5 having mounted therein a lower back .up roll 5, a lower work roll 1, and upper work -ing contained in gear reduction casings. I 5 and I6.

There is preferably a screw down motor and double reduction gearing for each roll adjusting screw II, and the reduction gearing jack shafts I81; and l8b of the screw down motors Ila and "b, respectively, are preferably adapted for being connected together in the usual manner by a magnetic clutch l9. rolling operation, although hot rolling operations For the purposes of description, the speed reduction between each screw down motor Ila or Ill; and its corresponding roll adjusting screw [4 may be considered to be 1000:1; and one revolution of the roll adjusting screw l4 may advance the screw one inch. Of course, it is understood that other screw down motor gear reduction ratios and other roll adjusting screw leads may be utilized, the above relations being taken as usual ones, merely for convenience in describing the present invention.

The work rolls 1 and 8 are driven in the usual manner through couplings 20 connected with the usual -pinions in the pinion case 2|, by the main mill drive motor fllthrough the usual gear reduction unit 23.

In the above detailed description, a usual arrangement of a roll stand and driving and screw down means therefor has been described, the same being shown as a four high roll stand and may be the last stand of a tandem arranged continuous either hot ,or cold rolling mill through which the material M being rolled passes from the entering out of the mill stand at the delivery side B travelling in the direction of the arrow shown in Fig. 2,

all of which is standard practice.

While our invention is described in connection with the particular type of mill shown, it will be understood by anyone skilled in the artzthat the invention may be carried out in connection with other usual types of mills.

Proceeding now to the detailed the interconnected mechanical and electrical devices utilized for rolling uniform gauge material, .a cam 24 is preferably mounted on the screw description of at 25 is connected preferably by a coupling 25a to the drive shaft of the main mill motor,22, and

a cam 26 is preferably mountedon the drive shaft 21 of the screw down motor Ho.

The hydraulic variable speed transmission generally indicated at 25 may preferably include what is generally termed a hydraulic pump 28, which is directly connected to and operates at the speed of.

the main mill drive motor 22, and also includes a hydraulic motor 29 driven by pump 28 through a hydraulic connection '38. .The speed 'of the shaft 3| of the hydraulic motor 29 is variable and may be controlled by the hydraulic variable speed transmission controller 32. A cam 33 is mounted on the shaft 3| of the hydraulic pump 29. ,L,

Referring to the wiring diagram shown in Fig. 3, the mill drive motor is diagrammatically indicated at 22, the mill screw down motors are diagrammatically indicated at He and I1!) and the shafts I8a, 21 and 3|, together with their respective cams 24, 26 and 33 are diagrammatically shown.

For convenience in description, the various circuitsshown in the wiring diagram of Fig. 3 may be generally referred to as the mill drive motor circuit, the screw down actuating circuit (down), the screw down holding circuit (down), the screw down contactor circuit (down), the screw down actuating circuit (up), thescrew down contactorcircuit (up) and the screw down'motor circuits cludes wire 4I, leading from line wire 58 to the armature 42 of the double acting series relay 0011-, trolled by the coil 39, the armature, 42 being preferablylpivoted at 43, contact 44- on armature 42, contact 45, wire46, contact 41, switch blade 48, contact 49, wire 50,,wire 5|, shunt relay coil 52, wire 53, and wire 54 leading to line wire 55.

. The switch blade 48 of the screw down actuating contact making switch, is preferably provided-on a lever '51, pivoted at 58, and carrying a roller""59, which rides on the cam. 33 mounted on the shaft 3| of the'hydraulic pump 2% When the roller 59 rides in the recess 33a of the cam 33,

as shownin Fig. 3, switchblade 48 closes the circuit between the contact points 41 and 49; and

when the roller 59 rides on the outer peripheryu 33b f the cam 33,- switch blade 48\ope'ns thecircuit between contact points 41 and 49. r v

The screw down holding circuit (down) includes wire 68 leading from line wire 56 to contact 6|, switch blade62, contact 63, wire 64, contact 65, switch blade 66, contact 61, wire 68, wire 5|, shunt relay coil 52, wire 53', and wire 54 leading to line wire 55.-

switch (down), is preferably provided on a lever 69, pivoted at, 18, and carrying a roller 1|, which rides on thecam 26 mounted on the, shaft 21 of the screw down motor I'1a. When the roller 1| rides on the periphery. 26a, of the cam 26, as shown in Fig. 3, the switch blade 62- closes the circuit between the contact points- 6| and 63;

to line wire 55.

and when the roller 1| rides on the projection 26b of the cam 26, switch blade 62 opens the cir-,

cuit between contact points 6| and 63.

The switch blade 66 of the shunt relay controlled by the coil 52 is preferably mounted on an insulating block 12 ,carried by one arm 13 of the bell crank armature 14 of the shuntrelay, pivoted at 15.

The screw down contactor-circuit (down) includes wire 16 leadingfrom linewire 56, wire 11, armature 14, contact 18 carried by armature 14, contact 19, wire 88, wire 8|, screw down motor shunt relay down contactor coils 82, wire 83, and wire 84 leading to-line wire 55.

The screw down actuating circuit (up) includes wire 4 I, leading from line wire 56 to armature 42 of the double acting series relay controlled by the coil 39, contact 85 on armature 42, contactv 86, wire 81, contact 88, switch blade 89, contact 98, wire 9|, shunt relay coil 92, wire 93, and wire 54 leading to line wire 55. I

The switch blade 89' of the screw down limit switch (up) is preferably provided on a lever 94, pivoted at 95, and carrying a roller 96, which rides on the cam 24 mounted on the jack shaft I8a of the screw down motor I1a. When the roller 96 rides on the outer periphery 24a'of the cam 24, as shown in Fig. 3, the switch" blade 89 closes the" circuit between contact points 88 and 98; and when the roller 96 rideson the projection 242) of the cam 24, switch blade 89 opens the circuit between contact points :88 and -98.

The screw down contactor circuit (up) includes Wire 16 leading from line wire 56, wire 91, armature 98 pivote'd at 99 controlled by shunt-relay coil 92, contact I80 carried by armature 98, contact I8I, wire I02, wire I83, screw down motor shunt relay up contactor coils I04, wire 83, and wire 84 leading to lineiwire 55. The up and ,down screw down contactor circuit wires 8| and I03 may also preferably be connected to usual screw down motor control switches indicated dia-' grammatically at I85, which may also be connected by wire I86 to line wire 56. The screw down motor circuit for each screw down motor I1a and I1b,'when the motors are to be operated to run the screws I4 down, each includes wire I81 leading from line wire 56, wire I88; contact I89, contact 8 carried byarmature III controlled by one of the shunt relay down= contactor coils 82, wire II 2, wire II3, screw down motor I1a or I1b, wire II4, wire II5,armature II6 controlled by the other shunt 'relay down contactor coil 82, contact I I1 carried by armature I I6, contact II 8, wire I I9, and wire I20 leading The screw down motor circuit for each screw down motor I11: and I112, when the motors are to be operatedto run the screws I4 up, each includes ,wire I81le,ading from line wire 56, wire I2I'; contact I22, contact I28 carried by armature I24 controlled by one of the shunt relay up contactor coils I04, wire I25, wire II I4, screw down motors I1a or'I1b, wire II3, wire' I26, armature I21, controlled by the other shunt relayup contactor coil I84, contact I28 carried by armature I21, contact I29, wire I38, and wire leading to line The switch blade 62 of the screw downlimit wire 55..

When the mill drive motor is operating under load, when material M being rolled enters. between work rolls 1 and 8, and during, the entire time of passage of material M through the mill, the coil 39 is energized so as to hold the armature 42 of the double acting series relay in the position shown in Fig. 3 of the drawings, so that the contact points 44 and 45 are closed and the contact points 85 and 86 are open. When the mill drive motor is operating at no load, as when the rear end of the material M being rolled is delivered from the work rolls 1 and 8, the coil 38 becomes deenergized and the armature 42 moves to a position opening contacts 44 and 45 and closing contacts 85 and 86.

The contacts 44 and 45 are in the screw'down actuating circuit (down) and the contacts and 88 are in the screw down actuating circuit (up), so that the mill drive motor circuit, or the load on the mill drive motor, or the passage of material between the work rolls 1 and 8 controls the screw down actuating circuit (down) and screw down actuating circuit (up). I

In order for the screw down actuating circuit (down), and therefore the shunt relay coil 52 to beinitially energized, to move the armature 14 to the position shown in Fig. 3, the switch blade 48 must close the circuit between contacts 41 and 48, and this condition only occurs when the roller 58 rides in the recess 33a of the cam 33, so that the screw down actuating contact making switch secondarily controlsthe screw down actuating circuit (down).

As soon asthe' coil 52 has been energized by the screw down actuating'circuit (down). to move the armature 14 to the position shown in Fig. of the drawings, the switch blade 86 connects contact points 65 and 81 to close the screw down hold- .ing circuit (down) provided that the switch blade 82 connects contacts 6| and 63 by the roller II riding on the periphery 26a bf the cam 28, to

maintain the coil 52 energized so as to hold the armature 14 in the position shown in Fig. 3 ofthe drawings after thescrew down actuating circuit (down) may be deenergized when the roller 58 rides on the periphery 33b of cam 33 to open the circuit between contacts4l and 48. Since the armature "I4 is in the screw down contactor circuit (down), the screw down'actuating circuit (down) followed by the screw down holding circuit (down) controls thescrew down contactor circuit (down).

As long as the armature I4 is in the position shown in Fig. 3 of the drawings, the screw down contactor circuit is energized and the screw down shunt relay down contactor coils 82 hold the down relay armatures I II and I I8 in the position shown in Fig. 3 to complete the screw down motor circuits (down) so that the screw down motors I10. and I'll; will run the screws I4 down.

When the switch blade 62 disconnects-contact points BI and 83, by the roller 'II riding on cam 26b, the screw down holdingcircuit (down) is de-".

energized so that the coils 82' are deenergized,- which results in contact being broken between contact points I08 and III), and III and ,8; so

that the screw down motor circuits (down) are deenergized and-the screw down motors "a and Ill) cease to move the screws I4 down. Thus, the

screw down contactor circuit (down) controls the screw down motor circuits (down).

When the mill drive motor is operating at no :load, the mill drive motor circuit is deenergized and the armature 42- moves to 'a position closing the contacts 85 and 86 in the screw down actuating circuit (up). When the switch blade 88 connects contacts 88 and 80, during the time when-the roller 88 isriding on the peripheral surface 24:; of

the cam 24, the screw down actuating circuit (up is energized to energize the coil 82 and draw the armature 288 to a position closing contacts I88 and l0I so that the'screw down-contactor'circuitiup) is energized. The screw down actuating circuit -until the roller 88 rides on the cam projection 24b when the switch blade 88 disconnects conactuating circuit (up): At thistime, armature 88 is released, deenergizing the screw down contactor circuit (up) and the shunt relay coils I04 are deenergized to break the screw down motor circuits (up).

Assume that the material M to be rolled finishes approximately three hundred feet in length, and that a gauge variation from forward to rear ,end of such a finished piece is .010 inch. Assume, further, that the diameter of. the work rolls I and 8 is approximately 18 inches so that the periphery of the same is approximately, 5 feet. Thus, each revolution of the rolls I and 8 advances 5 feet of material through-the rolls.

tacts 88 and 80, deenergizing theiscrew down- 8 advances feet of material M through the rolls. -With the assumed screw down motor gear reduction ratio of l000:1 and the assumed roll adjusting screw lead of 1 inch, for every revolution down of the screw down motors the roll ad- J'usting screws I4 move down .001 inch and defor the .010 inch gauge variation which would otherwise occur, with the result that the delivered material has a uniform gauge from end to end.

In order to secure the periodic or intermittent operation of the screw down motors (down) at intervals of 30 foot passage of material through work rolls 1 and 8, the screw down actuating circuit (down) must'be energized once every 6 revolutions of the work rolls 1 and 8, and this is accomplished by adjusting the hydraulic speed transmission controller 32 so that the cam 33 makes one revolution for every 6 revolutions of the work rolls-1 and 8.,

Of course it will be understood to those skilled in the art that the hydraulic variable speed transmission 25 may be connected to the gear reduction unit 23 rather than to the main mill- .drive motor 22, or at any other desirable place, so that the speed of the cam 33 may be coordinated with the speed of the rolls 1 and 8 and therefore with the passage of the material 'through the mill.

and therefore to the passage of material through the It is for this purpose thata hydraulic variable speed transmission is preferably utilized so that variable speeds for the cam 33 maybe readily obtained when desired; but it will be readily understood by those skilled in the art that other means may be provided for obtaining variable speed adjustments for the cam 33 coordinated with the rotation of the work rolls 1 and 8.

One revolution of the screw down motor lla, keeping the above assumptions in mind, makes a .001 inch adjustment of the roll adjusting screw l4, and the cam 26in being directly connected to the shaft 21 of the .screw down motor I'Ia causes the screw down holding circuit (down) to be deenergized with each revolution of the screw down motor Ha, so' as to stop the screw down motor. If it is desired to change ,the

amount of the intermittent adjustment of the gap between .the work rolls 1 and 8, to something other than .001 inch per,adjustment, the ratio of revolutions of the cam 26 with respect to the screw down motor I'Ia may be changed in any suitable manner.

In the case assumed above, ten down adjustments of the screw are performed by the screw down, motor l1; and ten revolutions of the screw down motor and of the cam 26 occur in performing the adjustments. Meanwhile, the screw down jack shaft l8a does not make a com- Dlete revolution, so that the roller 96 rides on the periphery 24a of the cam 24 during the entire time of intermittent down movement of\the screws l4, Q

In Fig. 3, the cam 26 is indicated by an arrow as rotating in a clockwise direction during down setting upon delivery of the rear end of the ma- 'terial from the rolls, tordeenergize the screw down'actuatin'g circuit (111)), and therefore the screw down contactor circuit (up), and finally the screw down motor circuits (up).

The operation of our improved method and apparatus-for rolling uniform gauge strips and the like may be briefly summarized as follows:-

The mill starts with no load on it and the ing a selected gauge. The front end of material to be rolled enters between the 'work rolls 1 and 8 and upon engagement of the rolls with the ma"- terial, suflicient current passes through the mill drive motor circuit to energize the coil 39 to draw the armature 42 to the position shown in Fig. 3 of the drawings.

After the rolls 1 and 8 have made not over sixrevolutions, the cam 33 causes the switch blade 48 to make contact between contact points 41 and 49, thus energizing the screw down actuating circuit (down), which in turn,energizes the screw down contactor circuit (down) to close the screw down motor circuits (down), and the screw down motors start running the screws l4 down.

Meanwhile, upon rotation of the screw down motor "a, the cam 26 operates the screw down limit switch (down) to make contact between contact points El and 63 to energize the screw down holding circuit (down) and maintain the coil 52 energized after the screw down actuating circuit (down) has been vdeenergized by 'c on-' The distance that the screws travel down is limited by operation of the cam26, and the screws l4 come to rest when the cam 26 makes one revpredetermined intervals as long as material is passing through the mill and a load remains on the mill drive motor 22, so that the screw down motors operate in synchronism with the rotation of the work rolls to adjust the gap between the work rolls during passageof material through the rolls.

When the rear end of the material is delivered from the mill, the load on the driving motor is removed and the coil 39 is deenergized, releasing. the armature 42 and energizing the screw down actuating circuit (up). Thereupon, the screw down contactor circuit (up) and consequently the screw down motor circuits (up) are energized and the screw down motors return the screws I4 to their original up position, when the cam 24b operates the screw down limit switch (up) to open the screw down actuating circuit. (up); and the mill is ready for rolling another piece.

There are only two variables which exist and these are the variable lengths of material to .be rolled and the difi'erent gauge variations existing from end to end of pieces. When the improved method and apparatus for rolling uniform gauge strips and the like is originally installed, it will probably be necessary to roll one or two pieces.

and determine the value of the gauge variation, whereupon the various adjustments may be made to accomplish gauge compensation.

- In certain cases, it may be convenient or nec* essary' to compensate for gauge variations, in

continuously rolling material on a continuous rolling mill, at a roll stand other than the last finishing stand of a continuous train, or at a plurality of roll stands of the continuous train. It is therefore comprehended within the scope of the present invention to compensate for gauge variation of material being rolled in a continuous rolling mill at one or more of any of the stands of a continuous train of tandem arranged mills.

Thepresent improvements accordingly provide for the hot or cold rolling of uniform gauge material such as strips, sheets, stripsheets and the like, in' a rolling mill regardless of the length of material rolled or of the value of the gauge variation from end to end of the material, which 4 is to be compensated for. Moreover, the present improvements may be readily applied to existing rolling mill equipment for correcting the gauge variation difficulties experienced in continuous rolling.

We claim: 1. In a rolling mill including work rolls and screw down means, means for operating the screw down' means intermittently to adjust the gap between the rolls a predetermined amount during movement of material through the rolls, and means operated by the entry of material between the rolls for actuating the said operating means.

to roll a selected gauge material and screw down means, means for operating the screw down 2. In a rolling mill including work rolls set amount at predetermined intervals during movement of material through the rolls, and means for varying the said intervals.

4. In a rolling mill including work rolls and .screw down means for the work rolls, means for operating the screw down means at equal time intervals for equal time periods to progressively adjust the gap between the rolls during move- 20 ment of material through the rolls.

5. In a rolling mill including work rolls and H screwwdown means for the work rolls, means periodically operating the screw down means every time the rolls'make a predetermined num- 5 her of revolutions to adjust the gap between the rolls during. movement of material through the rolls.

6. In a strip rolling mill including work rolls and screw down means for the work rolls, means periodically operating the screw down means to cumulatively adjust the gap between the rolls every time a predetermined length of strip and successive equal lengths of strippass through the rolls from the entry of the strip between the rolls until delivery of the strip from the rolls.

'7. In a strip rolling mill including work rolls and screw down means for the work rolls, means periodically operating the screw down 'means to cumulatively adjustrthe gap between the rolls an equal amount every time each of successive equal fractional lengths of strip pass through the rolls from the entry of a strip between the work rolls, screw down means for the work rolls,

and means automatically operating upon the entry of material between the rolls until delivery 50 of the' material from the rolls for actuating the screw down means at intervals to progressively (decrease the gap between the rolls.

9. In a rolling mill including work rolls, a mill drive motor for the work rolls, screw down means, driving means for the screw down means, means for periodically operating the driving means at intervals to periodically adjust the gap between the rolls, and means automatically actu-' ating said operating means when the mill drive.

60' 'motor is running under load. I

10. In a rolling mill for maintaining the gauge of the material rolled substantially constant, work rolls, screw down means for the work rolls, and means periodically operating the screw down means a predetermined amount to cumulatively adjust the gap between the work rolls during movement of the material through the rolls.

11. In a rolling mill for substantially eliminating gauge variations in the material rolled resulting from the gradual cooling of the material while being rolled, work rolls. a mill drive motor for the work rolls, screw down means for the work rolls, and means actuated by the mill drive motor for operating the screw down means periodically a predetermined. amount to cumulatively adjust the gap between the work rolls during I movement of the material through the work rolls.

12. The method of rolling metal in a rolling mill to maintain the gauge of the rolled metal substantially constant, which includes periodically and cumulatively adjusting the gap between the mill rolls every time the rolls make a predetermined number of revolutions automatically when metal is moving forward through the rolls.

ing gauge progressively heavier from front to I rear end, which includes automatically adjusting the gap between the mill rolls a predetermined amount every time each of successive i'ractional lengths of strip pass through the rolls from the entry of the strip to the rolls to the delivery of the strip from the rolls, and controlling the actuation of the automatic adjustment by the load on the mill drive motor. I

15. The method-of rolling metalin a rolling mill to maintain the gauge of the rolled metal substantially constant, which includes progressively adjusting the gap between the mill rolls at equal time intervals for equal time periods automatically when metal is moving forward through the rollsgland automatically returning the roll gap adjustment to the original setting upon delivery of the metal from the rolls.

'16, The method of rolling metal in a rolling mill to maintain the gauge of the rolled metal substantially constant, which includes periodically adjusting the gap between the mill rolls at equal time intervals for equal time periods automatically when metal is moving forward through the rolls, automatically returning the roll gap adjustment to the. original setting upon delivery of the metal from the rolls, and controlling the actuation of said automatic adjustments by the load on the mill drive motor.

ARTHUR J. TOWNSEND. EDWARD S. MILLER.

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