US2226500A

US2226500A - Method and apparatus for making sheet metal

Info

Publication number: US2226500A
Application number: US20587A
Authority: US
Inventors: Percy W Matthews
Original assignee: CHARLES W NEILL; EDGAR J GRIFFITHS; JOSEPH F BRANDENBURG
Current assignee: CHARLES W NEILL; EDGAR J GRIFFITHS; JOSEPH F BRANDENBURG
Priority date: 1935-05-09
Filing date: 1935-05-09
Publication date: 1940-12-24
Anticipated expiration: 1957-12-24

Description

Dec. 24, 1940. P. w. MATTHEWS METHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5 Sheets-Sheet 1 ATTOR EY Dec. 24, 1940. p w MATTHEWS 2,226,500

METHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5 Sheets-Sheet 2 INVENTOR ATTORNEY Dec. 24, 1940. P. w. MATTHEWS 2,226,500

METHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5 Sheets-Sheet 3 INVENTOR BYf ' ATTORNE Dec. 24, 1940. P, w. MATTHEWS METHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5 Sheets-Sheet 4 Y E N R O T T A Dec. 24, 1940. P. w. MATTHEWS METHOD AND APPARATUS FOR MAKING SHEET METAL Filed May 9, 1935 5 Sheets-Sheet 5 ATTORNEY U 0 N H 2.

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Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR MAKING SHEET METAL Percy W. Matthews, Pittsburgh, Pa., assignor of thirty-eight one-hundredths to Edgar J. Grifiiths, Pittsburgh, Pa... nineteen one-hundredths to Joseph F. Brandenburg, Larchmont, N. Y., and five one-hundredths to Charles W. Neill, West Englewood, N. J.

Application May 9, 1935, Serial No. 20,587

21 Claims. 80--35) This invention relates to method and apparatus and to provide an improved construction for zonefor making sheet steel in hot and cold strip rolldivided rollers which are employed to maintain ing mills. a uniform temperature across the width of the The invention is applicableto continuous strip strip. mills in which the metal passes in one direction -Other objects, features and advantages of the through successive roll stands, and to cold rolling invention will appear or be pointed out as the mills which pass the strip back and forth through description proceeds.

a single roll stand or tandem roll stands between In the accompanying drawings, forming part reels on which the strip is wound and unwound. hereof:

The term strip is used in this specification in a Fig. 1 is a diagrammatic side elevation of the broad sense to describe the sheet metal operated last three stands of a continuous strip mill, and upon by the rolling mills, but the term is not ina flying shear beyond the last roll stand, with tended to be a limitation on the width of the sheet apparatus between the successive stands and bemetal because some features of the invention are tween the last mill stand and the flying shear for especially adapted for the production of sheet controlling the temperature and tension of the metal of great width. sheet metal in accordance with this invention.

One object of the invention is to provide im- Fig. 2 is a top plan view of the roll stands and proved method and apparatus for producing flat the temperature and tension controlling apparasheet metal which is free from warps and buckles tus of Fig. 1. after it cools. Inability to obtain a fiat product Fig. 3 is a diagrammatic side elevation of a in wide strips has put definite limitations on the single-stand cold rolling mill, with coiling appawidth of the sheet metal rolled in accordance ratus at both ends of the strip which passes with the prior art. According to one feature of through the mill, and temperature and tension this invention the temperature of the strip is concontrol means between the roll stand and each trolled at and between roll stands, or between coiling apparatus. other apparatus which acts on the strip, so as Fig. 4 is a view similar to Fig. 3 with the addito maintain a substantially uniform temperature tion of a tandem roll stand and means between across the entire width of the strip and prevent the two roll stands for controlling the temperauneven rolling and the formation of locked up ture and tension of the strip. stresses which make the strip warp or buckle. Fig. 5 is an enlarged side view, partly in section,

Another object of the invention is to maintain showing a portion of the tension and temperature a constant tension on the strip between the roll control means which is located between two of the stands of a hot rolling mill. Another object is to roll stands of Fig. 1. tension a strip during a hot or cold rolling opera- Fig. 6 is an enlarged view showing the motor of tion and keep the tension uniform regardless of Fig. 5 with means for automatically varying the variations in the amount of slack between roll torque of the motor in response to changes in the stands or changes in the angle of deflection of the slack and deflection of the strip in order to mainstrip. tain a substantially uniform tension in the strip.

The invention includes novel apparatus for Fig. 7 is a top plan view of a portion of the maintaining a constant uniform tension on the apparatus shown in Fig. 5 with the motor control run of strip between two roll stands by means of means of Fig. 6 also shown but on a reduced scale. a variable-torque motor equipped with means for Figs. 8 and 9 are enlarged sectional views on the varying the torque in accordance with changes lines 8-8 and 9 -9 of Figs. 6 and 5, respectively. in the deflection of the strip. In another form Fig. 10 is a, side elevation of an embodiment of of the invention a constant-torque device is comthe invention for maintaining a substantially unibined with apparatus for changing the mechanform tension in the strip by means of a constantical advantage with which the device tensions the torque motor instead of the variable-torque mechstrip as the angle of deflection of the strip varies anism shown in Figs. 6 and 7. with the slack between the roll stands. Fig. 11 is a sectional view on the line I l-l l of Another object of the invention is to provide Fig. 10. an improved method and apparatus for removing Fig. 12 is a view, partly in section and partly scale from the strip during the rolling'operation. schematic, showing the full-width finding device Other objects are to provide improved control and the electric control circuits for the apparatus. mechanism responsive to the passage of the full Fig. 13 is an enlarged plan view taken on the width of material at the forward end of the strip, line |3l3 of Fig. 12.

Fig. 14 is a sectional view on the line l4=l4 of Fig. 13.

Fig. 15 is a view, on a reduced scale, showing typical irregular front and rear ends of the metal strip.

Fig. 16 is a sectional view on the line Iii-l6 of Fig. 12.

Fig. 17 is a top plan view of the limit switches shown in Fig. 12.

Fig. 18 is an enlarged fragmentary detail view, mostly in section, showing the construction of one of the zone-divided rollers.

Figs. 19 and 20 are sectional views on the lines I 9-H and 20-20, respectively, of Fig. 18.

Fig. 1 shows the three last roll stands H, l2 and I 3 of a continuous hot strip mill. The 4- high roll stands shown are representative of roll stands in general, since other types can be used with this invention. A looper unit Il is located between each of the roll stands H, l2 and I3 and has rollers l5 and IS in contact with the metal strip between 'these roll stands. Similar looper units may be located between all of the stands of a continuous strip mill, but if looper units are not between all of the roll stands, they should be between the last stands where they are most effective.

A fullwidth finding device I1 is associated with each of the looper units i l to control the operation of the looper units I4 to control the operation of the looper unit so that no tension is applied to the strip until the full width of the metal at the front end of the strip has entered the next roll stand beyond the looper unit.

The metal strip I8 travels from right to left in Fig. 1 and the front end of the strip is guided into the looper units and roll stands by a chute I 9. This chute is made up of a number of sections located between the roll stands and looper units, and any other places where the forward end of the strip needs support at the beginning of a rolling operation.

After leaving the last rolling pass l3, the strip 18 is guided by the chute I9 to a looper unit 20 and then into the pinch-rolls 2| of a flying shear 22. The looper unit 20 differs from the units M in that it has only one roller. All of the looper units may be similar to the looper units Id of the unit 20. The construction will be described fully in the explanation of Figs. 5 and 7.

Referring again to Fig. 1, the strip l8 passes from the pinch-rolls 2| into feed rolls 26, which move the strip between the knife drums 25 of the flying shear. Rollers 26 of the flying shear delivery table are shown to the left of the knife drum.

Pipes 28 deliver sprays of steam, water or other fluid against the upper and lower sides of the strip l8 to remove scale. There is a break in the chute I9 to permit fluid sprayed from the lower pipe 28 to reach the strip l8, and there is another break to prevent the chute from covering a luminous tube 29 of the full-width finding device l1.

Fig. 2 shows motors 3| with reduction gearing 32 connected with mill pinions 33 which drive the rolls of the roll stands I l-'|3. .Fig. 2 shows the relation of the looper units and roll stands. The chute l9, full-width finding devices ill and the spray pipes 28 are omitted from Fig. 2.

The rollers I 5 and 16 of the looper units are preferably zone-divided rollers for controlling the temperature of the hot strip IS in a manner which tends to equalize the temperature across the entire width of the strip. The construction and' operation of. these zone-divided rollers will be described in detail in the explanation of Fig. 18. For the present it is sufiicient to understand that these rollers are divided into several cooling zones, each of which extends axially for a portion of the length of the roller and each of which is substantially independent of the others in its cooling effect. Hot sections of the strip near the center can be cooled more. than sections which are nearer the edges and at a lower temperature so that the temperature of the strip becomes substantially constant across its entire width. The rolls of the roll stands H-I3 are also preferably zone divided.

Unless the temperature is substantially uniform across the entire width of the strip, the gauge of the metal is not absolutely uniform and there are locked-up stresses which make the strip warp or form into waves and buckles. The looper units I 4 and 20 tension the hot strip to any desired limit. When the looper rollers and those of the roll stands are zone divided, and the strip is rolled to a uniform gauge, substantially free from warps and buckles, the tension imparted to the strip may be light and intended primarily to take up slack between the roll stands. When some or all of the rollers in contact with the strip are not zone divided, and the cooling is not sufficiently uniform, or for some other reason the strip is objectionably wavy or warped, the tension imparted by the looper units can be increased to stretch the metal and substantially remove the waves and warp. Even when the temperature control effected by the zone-divided rollers is sufficient to obtain a substantially flat strip, the looper units can be used to put the strip under any tension wanted for the rolling operation; or to stretch the metal between roll stands if such a working of the metal between the roll stands is desired. The looper units maintain a uniform tension in the strip regardless of changes in the deflection.

An embodiment of the invention in a singlestand cold rolling mill is shown in Fig. 3. Coiling apparatus, comprising

reels

35 and 36, is located on both sides of a roll stand 31, and passes the cold strip 38 back and forth through the roll stand 31 until the metal is rolled to the desired gauge. A looper unit 20 is located between the roll stands 31 and each of the

reels

35 and 36. During the cold rolling of the strip 38 it is subject to a constant and uniform tension as it passes from the uncoiling reel to the coiling reel. Rollers 39, which are preferably zone divided, are located on fixed axes in positions to prevent the diameter of the coils on the reels from affecting the angle of deflection across the looper roller. In addition to taking up slack, the looper units can be employed to give the strip any amount of tension desired and to provide any desired envelopment of the strip material around the rollers with which the strip is in contact. great enough to put the strip under a predetermined tension for rolling, or to stretch out any waves or other unevenness of the strip, or to stretch the entire strip to work the metal.

Considerable heat is generated in the metal when it passes through the roll stand 31 and un even cooling of the strip is likely to give it different temperatures across its width so that in its next pass through the roll stand it will be rolled with stresses tending to warp and buckle the strip. The rollers l6 are preferably zone divided, for the purpose of equalizing the temperature across the width of the strip similarly to This tension may be made the rolls of Fig. 1. The rolls of the roll stand 31 are preferably of zone-divided construction also.

The apparatus shown in Fig. 4 is a cold strip mill similar to that of Fig. 3, with the addition of another roll stand 46 in tandem with the roll stand 31, and a chute I9, looper unit I4, and full-width finding device II between the roll stands as in Fig. 1.

Figs. 5 and 7 show the construction of one of the looper units. When the front end of the strip l8 comes from the working rolls of the roll stand 12, it is supported by the chute I9 and passes under the roller I5, over the top of the roller l6, under the other roller I5, through the full-width finding device I1, and then between the upper and lower spray pipes 28, and into the working rolls of the next roll stand I3.

An inclined .portion 42 of the chute I9 is con nected to the horizontal portion of the chute by a hinge 44 and has its free end supported by a rod 45. This inclined portion of the chute raises the front end of the strip so that it contacts with the upper part of the roller I6 and passes over this roller, as shown in Fig. 5. The roller I6 and the inclined portion of the chute comprise means for giving the strip an initial deflection so that during the operationof the rolling mill the run of strip between the roll stands I2 and I3 will not approach a straight line where the control of tension becomes very critical.

The ends of the roller I 6 are journaled in blocks 4! which slide vertically in guides 48 of a frame 49. Both of the blocks 41 are connected to a horizontal support 5I, and this support is raised and lowered by a rack bar 52. The upper end of the rack bar is connected to, or integral with, the support 5 I, and the lower end of the rack bar bears against a roller 53 with flanges 54 (Fig. 9) for preventing displacement of the rack bar 52 out of its vertical position. A pinion 56 meshes with teeth on the rack bar 52. Flanges 58 extending along both sides of the teeth of the rack bar 52 contact with the hub of the pinion 56 and hold the rack bar against the roller 53.

The roller 53 turns on a shaft journaled in downwardly extending lugs of the frame 49. The pinion 56 is secured to a drive shaft 66, which is also journaled in lugs of the frame 49. There are limit switches 6I on the drive shaft. The purpose of these switches will be explained in the description of the control mechanism. The drive shaft 66 connects with a torque motor 62, shown in Figs. 5 and '7.

When there is no power supplied to the motor 62, the rr .ler I6 occupies the position shown in Fig. 5, with the blocks 41 resting on springs 63. During operation of the rolling mill it is possible for the roller I6 to be moved lower than the initial position shown in Fig. 5 by compressing the springs 63, but in normal operation of the rolling mill the slack in the strip is always greater than that produced by the initial deflection imparted to the strip and the roller I6 never moves as low as the position shown in Fig. 5. The inclined portion of the chute is hinged so that it can move down to permit the strip to move lower than its posiion of initial deflection and avoid breaking in case of some abnormal operation which causes almost all of the slack to be taken up before an attendant or automatic control means can correct the trouble.

' The rollers I5 turn on axles connected to the upper ends of links 64. The lower ends of the links 64 have pivot connections with the frame 49. Links 65 connect the axles of the rollers I5 with the blocks 41. These link connections provide strong and simple supporting means for the rollers I5, but the link movement is not an essential feature of the invention and the links 64 can be made integral parts of the frame 49 and sufficiently strong so that the links 65 are not necessary. In Fig. 5 the rod 45 is connected to the links 65 to rise and fall with the blocks 41.

When the looper unit is in operation and the roller I6 rises into an elevated position as indicated in dotted lines in Fig. 5, the strip I8 flexes at the rollers I5. There are two important advantages in having these looper rollers in the relation illustrated. The strip is given reverse bends, which are very effective in loosening scale for subsequent removal by the spray pipes 28, and the amount of slack which can be taken up with a given displacement of the roller I6 is greater with the three-roller combination than if the roller I6 alone deflected the strip in an angle extending all the way to each of the roll stands I2 and I3.

The break in the chute I9 at the spray pipes 28 has sloping edges so that the front edge ofv the strip cannot catch in this break. A different provision for preventing the front edge of the strip from catching in the break at the luminous tube 29 will be described in the explanation of Figs. 12-14. Such a provision may also be used at the slots for the spray pipes. The chute I9 has a sloping cover just ahead of the roll stand I3 for guiding the front edge of the strip into the bite of the rolls.

As the deflection of the strip increases, a constant upward force on the roller I6 produces progressively less tension in the strip. In order to maintain a constant uniform strip tension, therefore, it is necessary to increase in a definite relation the force with which the roller I6 is urged upward as the deflection of the strip increases. This can be accomplished by increasing the torque of the motor 62. The mechanism which varies the motor torque is shown in detail in Figs. 6 and 8.

The supply of electricity to the motor 62 is controlled by a rheostat 61, which has two rows of taps 68, with the taps of the respective rows staggered so that a contactor 69 of an arm I8 is always in contact with at least one of the taps 68. The contactor bears against a strip I2 to complete the circuit through the rheostat 61. With the arm I in the position shown in Fig. 6, the power of the motor is at a minimum, or that necessary to give the strip the desired tension when the deflection is at its smallest value.

There is a cam I4 on the shaft of the motor 62, and a cam-follower at the lower end of a lever I5. The lever I has a pivot connection I6 with the motor frame or some other convenient stationary structure. The follower at the lower end of the lever is held against the cam I4 by a spring 11 connected at its opposite ends to the lever and the motor frame. A link I9 connects the lever I5 with the arm In. As the shaft of the motor 62 turns, the cam I4 shifts the lever 15 and moves the arm I0 to vary the torque of the motor 62. The angular movement of the cam I4 is proport onal to the displacement of the roller I6. The contour of the cam I4 is designed to move the arm I9 and change the motor torque in such a manner that the tension imparted to the strip I8 remains constant regardless of changes in the deflection of the strip.

The correct outline for the cam I4 is most easily determined by computing the upward force on the roller I6 necessary to produce the desired uniform tension in the strip with certain chosen deflections. The closer together these deflections are taken, the more accurate the cam outline will be. These necessary forces are first obtained with reference to roller displacement, but this is easily converted to angular displacement of the motor shaft. Adding to this knowledge the motor torque corresponding to each tap 88 of the rheostat, the necessary radius of the cam for all of the chosen displacements can then be accurately determined.

Figs. 10 and 11 show another form of looper unit which is similar in construction to the unit illustrated in Fig. 5 except that it has different kind of mechanism for raising the roller IE to tension the strip. Cables 8| are attached to the upper ends of the blocks 41. These cables wrap around drums 82 on a shaft 83 journaled in brackets 84 which extend upward from the frame 49. A large drum 86 is secured to the shaft 83 near one end and a cable 81 wraps around the drum 86 at one end and around a grooved drum 88 at the other. The grooved drum 88 is fastened to the shaft of a constant-torque motor 90. The radius of the grooved drum 88 varies to change the mechanical advantage of the motion-transmitting connections between the motor 90 and the blocks 41 in accordance with changes in the deflection of the strip and variations in the angularity of the connecting cables so that the constant uniform torque of the motor 90 is transmitted to the roller I6 as a force which so varies with the position of the roller I6 that a uniform, constant tension is maintained in the strip.

The angular movement of the drum 86 is limited because it is on the same shaft with the limit switches 8|, but the large diameter of the drum 86 with respect to the grooved drum 88 makes it possible to have the motor 90 make a number of complete revolutions in moving the roller I8 from its position of minimum strip deflection to its maximum deflection position.

Fig. 12 shows the full-width finding device and the control circuits through which this device controls the operation of the looper unit motor and the supply of fluid to the spray pipes 28.

A swinging finder 92 comprises a photoelectric relay 93 enclosed in an opaque housing and responsive to light which enters through a long sleeve 94. This sleeve is the only light-entrance into the photoelectric relay housing so that only light in line with the sleeve can control the photoelectric relay. The finder 92 is supported from a frame 95 for angular movement transversely of the strip I8. The finder swings through an angle which causes the sleeve 94 to travel from a position in line with the edge of the strip to a position in line with the center of the strip. A similar finder 91 containing a photoelectric relay 98 swings across the other half of the strip I8. Unless the strip completely covers the luminous tube 29, light from this tube will reach the finders at some point during their swinging movement. For a narrow strip, one finder swinging across the full width of the strip would be sufficient, but more than one finder reduces the time required to detect the full width of the strip and reduces the amount of full-width material which may pass through the device before it operates the control apparatus. Gear motors IOI and I02 on the frame 95 are connected with the swinging finders 92 and 91 by links I03 and I04.

In addition to the luminous tube 29, the swinging finder 92 receives light also from a lamp I06 carried by a block I01 at the edge of the strip I8. The block I! is supported from a rod I09 which extends through the frame 95 and has a threaded end passing through a hand-wheel I I0. The block IN is urged against a head H2 on the rod.l09

by a spring H3, and the rod is shifted trans-' versely of the strip by turning the hand-wheels I I0.

The lamp I06 receives electricity through a conductor I I 0 from a contact I I on the top of the block I0'I. A contact II! on a rod H8 is held against the contact II5 by a spring H9, which is compressed between the frame 95 and a collar on the rod II8. There is a dash-pot I2I at the end of the rod II8.

The contact H1 is connected with a lighting circuit I22 through a normally closed push-button switch I23, which can be operated at any time to extinguish the lamp I06.

A lamp I24 at the edge of the strip under the swinging finder 91 is supported by structure similar to that described for the lamp I06 and receives its electricity through similar contacts. A description of the operation of the structure on one side of the strip is, therefore, sufiicient.

As long as the swinging finder 92 receives light from the lamp I06, the photoelectric relay 93 is open and the swinging finder 92 remains stationary. The block I 01 has a sloping face I25 (Fig. 16) and its position is adjusted by means of the hand-wheel IIO (Fig. 12) so that as the strip enters the full-width finding device, the edge of the strip strikes the sloping face of the block and pushes the block outward against the pressure of the spring II3. This movement of the block I0I moves the contact II5 away from the contact I I I and breaks the circuit to the lamp I08. When the swinging finder no longer receives light from the lamp I06, the photoelectric relay 93 closes and supplies power to close a normally open contactor I 21. The closing of this contactor completes a circuit from a power line I28 through a speed control panel I29 to the gear motor IOI. When this motor starts it swings the finder 92 counterclockwise in Fig. 12.

The lamp I06 must remain extinguished until the swinging finder moves out of the range of this lamp or into the shadow of the strip I8. This time delay is obtained with the dash-pot I2I, which makes the movement of the contact II 1 under influence of the spring II9 slow enough to allow the swinging finder to move beyond the influence of the lamp I08 before the contacts I I5 and II'I'again touch and relight the lamp.

A normally open push-button switch I3I is connected in parallel with the photoelectric relay 93 and can be operated to close a circuit from a control power line I32 to the contactor I21 for manual operation of the mechanism regardless of the light supplied to the photoelectric relay.

The control circuits of the photoelectric relay 98 and motor I02 are similar to those already described for the swinging finder 92. If either of the swinging finders 92 and 91 picks up light from the luminous tube 29, the photoelectric relay in that finder opens and causes the swinging movement of that finder to stop until the strip covers the tube 29. Fig. shows a typical front end of the strip I8 and it is evident that the length of the luminous tube between the block I01 and the corresponding block on the other side will not be shielded from the swinging finders until the ragged edge has passed beyond' the tube 29 and the portion of the strip in which the metal extends across the full width is under the swinging finders.

Contacts I34 and I35 near the center of the frame 95 are connected with the control power line I32. Other contacts I36 and I31 are connected with normally open, adjustable time-delay opening relays I38 and I39. A contact I46 carried by the swinging finder 92 bridges the contacts I34 and I36 when the swinging finder reaches the limit of its inward movement. The closing of the ciricuit between these contacts I34 and I36 supplies power to the relay I38 and causes it to close. A contact I4I carried by the swinging finder 91 bridges the contacts I35 and I31 to close the relay I39.

The contacts closed by the relays I38 and I39 are connected in series, and when both of these relays are closed at the same time they complete a circuit from the control power line I32, through a conductor I43 to one contact I44 of the limit switch 6I. A commutator bar I46 on the drum of the limit switch completes the circuit from the contact I44 to another contact I41 which connects with an adjustable, normally open, time-delay closing, differential contactor ME). A normally open, push-button switch I56 isconnected in parallel with the relays I38 and I39 for closing the circuit to the contactor I69 regardless of the position of the relays.

When power is supplied to the difierential contactor I49 from the contact I44 of limit switch 6i,

this contactor I49 closes the circuit from a power line I5I, through a torque control panel I53, to the motor 62. This torque control panel I53 includes the rheostat 61 when the control circuit is designed for the embodiment of the invention shown in Figs. 5-8.

Referring again to Fig. 12, the closing of the contactor I49 supplies power through a normally closed, push-button switch I54 and conductor I55 to open a solenoid-operated valve I56 which controls the supply of fluid to the spray pipes 28. The push-button switch I54 can be opened at any time to cut oil the current which holds the valve I56 open, so that the valve will close and the sprays stop. A normally open, push-button switch I51 can be closed to supply power to the valve I 56 at any time.

When power is supplied to the motor 62 it is also supplied to a brake I58 on the motor to release this brake. The brake is connected in the circuit ahead of the torque control panel I53 because it is never desirable to reduce the power supplied to hold the brake released while the motor is running.

The limit switch 6I has a commutator bar I66 which moves into position to bridge contacts IGI and I62 when the motor 62 turns beyond a predetermined limit. When'the circuit between the contacts I6I and I62 is closed, current flows from the control power line I32 to an opening solenoid I64 of the differential contactor I49. This solenoid I64 can be supplied with current to open the differential contactor I49 at any time by closing a normally open, push-button switch I66 which is connected in parallel with the contacts I6I and I62 of the limit switch. Another normally open, push-button switch I66 is connected in parallel with the contacts I44 and I41 01 the limit switch and can be operated at any time to close the differential contactor I49.

when the rearward end of a strip passes through one roll stand, the roller of the looper unit between thatvroll stand and the next is free to rise without restraint from the strip tension, and the motor 62 rotates until the limit switch 6I closes the circuit to the solenoid I64 and opens the differential contactor I49 and the circuit to the motor 62.

The limit switch 6I includes two drums, as shown in Fig. 17. The inner drum I12 is secured to the motor shaft, and carries the commutator bar I66. The outer drum I13 is secured to the inner drum by screws I15 (Fig. 12) extending through arcuate slots to permit angular adjustment of the drums with respect to one another. The commutator bar I46 is carried by the outer drum I13.

Figs. 13 and 14 show ribs I11 over the tube 29 to prevent the front end of the strip from catching in the break in the chute I9. These ribs are sufliciently thin and are set on a diagonal so that their shadows do not afiect the operation of the swinging finders.

stands are preferably zone-divided by a similar construction. The roller comprises an outer shell I18 into which end fittings I19 are secured. The

end fittings run in ball bearings I86 in the roller supporting frame or blocks 41. A nut I82 threads over the outer end of the end fitting I19 and holds the ball bearing I86 in assembled relation with the end fitting. Seals I83 protect the ball bearing from water and dirt and retain lubricant in the bearing.

The fluid inlet conduit is made up of a series of short tubes I85 extending in a line through the center of the roller. The ends of each tube I85 are spaced a short distance from those of the next adjoining tubes, and there is a conduit section I86 connecting each tube with the next tube. The conduit sections I86 have two walls with a conduit I88 between them. The inner and outer walls of the conduit sections I86 are joined at spaced points by pillars I89.

The ends of both the inner and outer walls of each conduit section fit over the adjacent ends of the corresponding walls of the next conduit section to form sliding joints I9I and I92 between the ends of the .conduit sections to allow for expansion with change of temperature. The ends of the conduit sections remote from their threaded connections with the tubes I85 are free to slide on the tubes as the conduit sections change in length with temperature variation. The inner face of each conduit section is spaced, for the greater part of its length, from the tube I85, which it surrounds, to form a heat insulating chamber I94.

A sleeve I96 surrounds each of the conduit sections I86 and throughout most of its length is spaced from the outside wall of the conduit section to form a heat insulating chamber I91.

A chamber I98, between the sleeve I96 and the outer shell I18, communicates through openings 266 with the fluid inlet conduit formed by the tubes I85. These openings 266 extend through roller is cold. Plungers 201 extend through openings in one end of the ring 205 into an annular mercury chamber 208 enclosed in the ring. The outer ends of these plungers 20'! contact with an abutment comprising a nut 209 threaded over the end of the sleeve I96 and held in set position by a lock nut 2I0. respect to the openings 204 can be adjusted by changing the positions of the nuts 209 and 2I0 on the sleeve I96.

The ring 205 is urged toward the nuts 209 and 2I0 by a spring 2I2 which is compressed between the ring and a collar on the sleeve I96. When the temperature of the liquid in the chamber I90 rises, heat is transmitted through the ring 205 to the mercury in the chamber 208 and the expansion of this mercury displaces the plungers 201 and causes the ring 205 to move away from the nut 209, against the force of the spring 2I2, to partially uncover the openings 20 5. A further rise in the temperature of the liquid in chamber I98 causes the ring 205 to uncover more of the openings 2% and increases the rate of flow of cooling liquid through the chamber I98 to counteract the temperature rise.

The zones of the roller are divided by packing 2I5 which is held in place by nuts 2I6 threaded as may be necessary to maintain a substantially uniform temperature across the width of the strip. By reducing the length of the zones, the number of zones is increased, and the accuracy of the temperature control improved. Although the zone-divided rollers of this invention are employed to cool the strip, it will be understood that the roller construction illustrated can be employed when rolling material which must be heated by the roller. For such operation the; openings 2| t are located at the other end of the rings 205 so that the ring uncovers these openings as the temperature falls and hot fluid is supplied through the inlet conduit.

The preferred embodiments at this invention have been described, but changes and modifications can be made, and some features can be used without others, without departing from the invention as defined in the claims.

- I claim:

1. The method of making sheet metal which comprises simultaneously and progressively roll-' ing different portions of a metal strip to reduce the thickness while the metal is at a high temperature, and deflecting the hot strip out of its normal run between successive points at which the metal is rolled by applying to the hot strip between said points a force of sufficient magnitude to impart a consequential tension to the hot metal as it passes from one point of rolling to the next.

2. The method of rolling metal in a continuous strip mill, which method comprises passing a strip which is at least red hot through successive roll stands, applying force to the hot strip between roll stands to produce a deflection of the strip and maintain a tension in the metal, maintaining said force at a magnitude sufi'icient to stretch the hot metal, and changing the magnitude of said force in accordance with variations in the angle of deflection and at a rate which The position of the ring 205 with causes the tension of the hot strip to remain substantially uniform when variation in the slack between roll stands causes changes in the angle of deflection.

3. The method of making sheet metal in a hot rolling strip mill in which the metal strip passes successively through roll stands which operate simultaneously on different portions of the strip, which method comprises applying a force and deflecting the hot strip between successive roll stands, maintaining the deflecting force against the strip to cause a tension in the metal between the roll stands during the rolling of the metal, and controlling the temperature of the tensioned metal to obtain a substantially uniform temperature across its width as it enters the next roll stand.

4. The method of making sheet metal in a hot rolling mill having successive roll stands through which the metal strip passes, which method comprises passing the forward end of the strip through the successive roll stands with the metal at a high temperature, imparting a substantial initial deflection to the strip after it has passed through one roll stand and before the forward end of the strip has entered the next roll stand, and taking up the slack between the successive stands by imparting a further deflection to the strip in the same direction as the initial deflection after the forward end of the strip has passed through said second roll stand.

5. The method of rolling thin flat metal sheets in a rolling mill having successive roll stands through which a metal strip is passed to reduce the thickness to the gauge desired, which method comprises deflecting the metal strip between successive roll stands to produce sufficient tension in the metal to stretch said metal and remove warps and buckles in the strip, increasing and decreasing the tensioning force in accordance with changes in the slack between the roll stands at a rate which causes the tension in thestrip to re-- main substantially uniform regardless of changes which the slack variation causes in the angle of deflection, and equalizing the temperature of the strip by selective cooling at various zones across its width to prevent the formation of stresses tending to warp or buckle the strip.

6. In apparatus for rolling a metal strip to reduce its thickness, a roll stand through which the metal strip passes at one point in its travel, other means operating upon the strip at a point spaced from the roll stand lengthwise of the strip, and a temperature-controlling roller in contact with the run of the strip between the spaced points, said roller being divided internally into a plurality of axially extending zones and having means 'for producing different temperature-control efiect from the respective zones to equalize the temperature of the strip across its width.

'7. Apparatus for rolling sheet metal including in combination a continuous hot strip; rolling mill with a plurality of roll stands, roller means between successive rollstands for deflecting the run of strip passing between said successive roll stands, said roller means including one or more hollow rollers divided into several axially extending zones, means for controlling the temperature of the respective zones independently to equalize passes, of a device which bears against the strip between the roll stands and deflects the strip at acute angles to a straight run between the roll stands, power mechanism for moving said deflecting device to hold it against the strip during changes in the amount of slack between the roll stands, and automatic means included in said power mechanism for changing the mechanical advantage of said mechanism in accordance with the sine of the angle of deflection of the strip, as the angle of the deflection changes, so that the resulting tension forces in the strip remain subthe strip in accordance with changes in the slack and at a rate which obtains a substantially uniform tension in the metal of the strip during said changes in the slack.

10. The combination with the successive roll stands of a rolling mill, of means imparting an initial deflection to the metal strip while the forward end of the strip is passing from one roll stand to the next roll stand, and other means for deflecting the strip further in the same direction and taking up the slack in the strip after the forward end has passed through said next roll stand.

11. In a cold rolling strip mill, the combination of a roll stand through which'a. metal strip is passed to reduce the thickness of said strip, reels beyond both ends of the roll stand for winding and unwinding the strip as it is passed back and forth through the roll stand, means tensioning the run of strip between the roll stand and at least one of the reels, said means comprising a roller which contacts with and deflects the strip, said roller being divided internally into a plurality of axially extending zones and having means for producing different temperature-control effect from the respective zones to equalize the temperature of the strip across its width, mechanism urging the deflecting roller against the strip, said mechanism including automatic means for changing the force exerted by the deflecting roller at a rate substantially proportional to the sine of the angle of deflection to compensag for changes in said angle of deflection and maintain the tension of the strip substantially uniform, and means for preventing change in diameter of the reeled strip from affecting the tension imparted by said mechanism.

12. The combination of apparatus for progressively rolling a metal strip to reduce its thickness, means at spaced points along the length of the metal for causing the progressive movement of the strip, means between said spaced points deflecting the run of the strip at acute angles to a straight line between said points, a torque motor, and mechanism operated by said motor for applying force to the deflecting means to produce a tension in the strip, said mechanism including means constructed and arranged to change the mechanical advantage of the mechanism in accordance with the sine of the angle of deflection so that the opposing component forces which tension the strip remain substantially unchanged at difierent angles of deflection.

13. The combination of apparatus for progressively rolling a metal strip to reduce its thickness, means at spaced points along the length of the metal for causing the progressive movement of the strip, and a temperature-controlling roller in contact with the run of the strip between the spaced points, said roller being divided internally into a plurality of axially extending zones and having means for producing different temperature-control effect from the respective zones to equalize the temperature of the strip across its width.

14. Apparatus for rolling sheet metal including in combination spaced roll stands through which a metal strip moves while working rolls in said stands operate simultaneously on different portions of the strip, a hollow temperature-controlling roller in contact with the run of the strip between the roll stands, said roller including partitions dividing the interior of the roller into several axially extending zones, and means for supplying difierent amounts of temperature-controlling fluid to the respective zones to obtain a constant temperature across the width of the strip, and mechanism urging the roller against the strip including means for moving the roller with variations in the slack in the run of strip between the roll stands.

15. The combination with a rolling mill having successive roll stands which operate on difierent portions of the same strip as said strip travels progressively through the mill, of a roller between the roll stands, mechanism for moving the roller against the run of strip between the roll stands and for holding said roller against the strip during variations in the slack in said strip, and control means for starting the operation of said mechanism including means for detecting the passage of the full width of material behind the forward edge of the strip.

16. Apparatus for detecting the passage of the full width of metal behind the forward end of a rolled strip including in combination a photoelectric relay in a swinging finder, means for swinging the finder transversely of the strip so that the photoelectric relay is successively in position to be affected by light from a point just beyond the edge of the strip and then from points at the edge and progressively in from the edge, a source of light extending under the strip in position to supply light to the swinging finder when said source of light is not covered by the strip, a source of light adjacent the edge of the strip for illuminating the finder, and means displaced by the edge of the strip for extinguishing the light from the source adjacent the edge of the strip.

17. The combination with successive roll stands through which a metal strip passes, of means for tensioning the run of strip between said roll stands including a roller which contacts with the strip and deflects it out of a straight run between the stands, and mechanism urging the roller against the strip including a rotary member through which the force is applied to the roller, said rotary member being of different diameter at different points to change the mechanical advantage of the mechanism as said member rotates, the rate of change of diameter being so correlated with the deflection caused by the rotation of said member that the force with which. the roller is thrust against the strip varies as a function of the angle of deflection of the strip and keeps the tension in the strip substantially uniform.

18. The combination with successive roll stands through which a metal strip passes, of strip tensioning means comprising a roller which contacts with the strip and deflects it out of a straight run between the roll stands, and mechanism for thrusting the roller against the strip including a cam which turns in response to changes in the angle of deflection to vary the force of the roller against the strip, said cam having a peripheral contour correlated to the displacement of the roller so as to vary said force in a manner that keeps the strip tension constant during changes in the angle of deflection.

19. The combination with successive roll stands through which a metal strip passes, of strip tensioning means comprising a roller which contacts with the strip and deflects it out of a straight run between the roll stands, and mechanism for thrusting the roller against the strip including a cable through which force is transmitted to the roller, and a drum on which the cable winds, the drum being of different diameter at angularly spaced points with the diameter at each point so related to the roller position which corresponds to that position of the drum that the force transmitted to the roller varies as a function of the angle of displacement of the strip and maintains a substantially constant tension in the strip.

20. The method of making sheet metal in a rolling mill in which the metal strip passes successively through roll stands which operate simultaneously on different portions of the strip, which method comprises controlling the shape of the rolls and the temperature of the strip at the roll stands by controlling the temperature of the rolls, applying a force and deflecting the strip between successive roll stands by a deflecting means, maintaining a substantial deflecting force against the strip to cause the strip to partially envelop and tightly embrace the deflecting means to control the temperature of the strip material between the roll stands during the rolling of the metal, and controlling the temperature of said deflecting means so as to obtain a substantially uniform temperature across the width of the strip material to prevent warping and buckling of the strip material.

21. The method of making sheet metal in a rolling mill in which the metal strip passes successively through roll stands which operate simultaneously on difierent portions of the strip, which method comprises controlling the shape of the rolls and the temperature of the strip at the roll stands by controlling the temperature of the rolls, applying a force and deflecting the strip between successive roll stands by a deflecting means, maintaining a substantial deflecting force against the strip to cause the strip to partially envelope and tightly embrace the deflecting means to control the temperature of the strip material between the roll stands during the rolling of the metal, controlling the temperature of said deflecting means so as to obtain a substantially uniform temperature across the width of the strip material to prevent warping and buckling of the strip material, and equalizing the temperature of the strip at one or more of the temperature control regions by selective temperature control at various zones across its width to prevent the formation of stresses tending to warp or buckle the strip.

PERCY W. MATTHEWS.