US2196600A

US2196600A - Method and apparatus for treating strip

Info

Publication number: US2196600A
Application number: US254862A
Authority: US
Inventors: Raymond J Wean; Donald A Mcarthur
Original assignee: Wean Engineering Co Inc
Current assignee: Wean Engineering Co Inc
Priority date: 1939-02-06
Filing date: 1939-02-06
Publication date: 1940-04-09
Anticipated expiration: 1957-04-09

Description

April 1940- R. J. WEAN Er m. 96,600

. METHOD AND APPARATUS FOR TREATING STRIP Filed Feb. '6, 1939 2 Sheets-SHeet 1 E 3 I N ,3, I INVENTORS I Raymond J. Wean? Dona/d AMcArf/Iurv R- J/WEAN Er AL METHOD AND APPARATUS FOR TREATING STRIP Filed Feb. 6, 1939 1 2 Sheets-Sheet 2 INVENTORS Raymond J. Wean & Donald A. McArf/n/r 1 the method thereof. In the drawings:

Patented Apr. 9, 1940 PATENT OFFICE I 2.196.600 METHOD AND APPARATUS non TREATING s'rmr Raymond J. Wean' and Donald A. McArthur,

Warren, Ohio, assignors to The wean Engineering Company,'lnc Warren, Ohio, a corporation of Ohio v Application February 6, 1939, Serial No. 254,862

8 Claims.

This invention relates toa method and apparatus for the treating of strip material, and particularly to the continuous descaling of steel strip such as is produced on the wellknown continuous strip mills.

It has been proposed heretofore to descale 'strip by passing it through suitable treating apparatus, and securing the trailing end of one ,length' of strip to the leading end of another to 10 avoid the necessity of threading each lengthindividually through the treating apparatus. It has been necessary, however, with the methods and apparatus heretofore usedjto arrest the movement of the strip during the attachment 5 of successive lengths together and their severance after completion of the treatment. This is objectionable because that portion of the material which remains in the treating apparatus during the attachment of severance of successive lengths is subjected to an excessive descaling treatment. Each stop means that the acid in the tank where the concentrated solution is carried will over-pickle the strip and particularly mark the strip at thesurface level of the acid,

- leaving what is called a pickle-etched stain. 7 At both ends of the catenary this will be repeated on the second stop, and when the strip goes to the cold mill for further reduction and elongation, these particular spots or marks across the strip are also elongated and when the material is sheared and inspected, all such sheets have to be thrown out as rejections. Another objection to the methods and apparatus previously employed is that'they did not provide the desired flexibility of operation or control.

We have invented a method andapparatus.

for treating strip which overcomes the aforementioned objections and makes it possible to move the strip continuously through the treatbeing attached or severed. This ensures that all portions of the strip are subjected to precisely the same descaling treatment with the result that a high degree of uniformity in the product is obtained. A further feature of our invention is that a high degree of flexibility in the control and operation thereof is obtained by making the drives for the several parts of the apparatus independent of each other. Other novel features 60. and advantages of. the invention will become apparent as thedescription thereof proceeds. The accompanying drawings illustrate diagrammatically a preferred-form of the-apparatus of the invention which we employ to practice ing apparatus, even while successive lengths are Figures 1A and 13 together constitute a plan view of descaling apparatus in accordance with, the invention; I

Figures 2A and 2B'together constitute a vertical longitudinal sectional view taken along the 6, line IIA-IIB of Figures 1A and 13, together with elemental control circuits for the motors driving the various units; and I Figures 3A and 3B constitute a circuit diagram. 10

For convenience and clarity, the following de- -tailed description of the invention will be divided into three parts, as follows:

(1) The apparatus; '(2) The control;

(3) The method.

.The apparatus of scale thereon, is delivered to the entry end of the apparatus by any convenient means, such as a gravity conveyor Ill. The conveyor is provided with a tilting section'll which, when operated, discharges the coilthereon down a slope 26 I2 onto cradlei rolls l3 of a processing uncoiler M. This device is well known in the steel industry and requires no detailed description. Briefly, it consists of housings I5, pinch rolls l6 and leveling rolls I! which subject the material to a mild cold working as it is drawn therethrough while the ,coil is supported on suitable means for the unwinding operation. The, ma-

- terial is rendered more plastic by passing through the uncoiler and less likely to development of cross breaks. a

A squaring shear I8 is spaced from the discharge end of the coiler ll. A roller conveyor l9 extends between the uncoiler and the shear. The rolls of the conveyor are in two groups and 40 are staggered to prevent the advancing end of a strip .from catching between adjacent rollers. 0n the opposite side of the shear I8 from the conveyor I9 is a tilting conveyor section 20, the alternate position of the conveyor section being 46 shown in dotted lines. The conveyor is shifted to the dotted-line position when the leading end of a coil of strip is passed through the shear.

- vided with a motor 2| shown.in plan in Figure 1A and diagrammatically in Figure 2A. The shear I8 is driven by a motor 22.

Beyond the tilting conveyor section 29 is located a stitcher 23 which is similar to the shear l8 except that it is provided with punches and the pinch rolls 25. The pit is preferably thirty or forty feet long so as to accommodate a fair length of strip when piled loosely therein, as indicated in Figure 2A.

Pinch rolls 29 driven by a motor 30 are disposed adjacent the end ofthe pit 28 opposite that at or creases which may have been formed in the strip while it lay in the pit, by the weight of the several loops thereof. i

From the pinch rolls 29 the strip passes under a so-called dancer" roll 33 over a guide roll 34 and into descaling apparatus indicated generally The dancer. roll is simply an idle roll mounted on an oscillatable frame, the function of which is to control the slack inthe strip" asit passes through the descaling apparatus 35 by suitably adjusting the speed of the motors driving the pinch rolls which advance the strip.

The descaling apparatus illustrated consists of a plurality of pickling tanks such as that illustrated at.35, and one or more wash tanks 31. The first .tank 35, as shown, is at a level lower than that at which the other pickling tanks are disposed. This permits gravity-flow of nearly spent acid to the first tank from the other tanks, with a considerable economy, as the solution in the first tank does not have to be very strong. With this arrangement, fresh acid is added only to the pickling tanks subsequent to the first. rolls, such as that shown at 34, are provided at each end of each pickling tank, and hold-down rolls 38 are mounted in the wash tanks.

Adjacent the exit end of the last-mentioned tank'islocated an air .drier 39 which dries the strip by subjecting it to jets of warm air as it passes over a conveyor 40.

Pinch rolls 4| driven by a motor 42 are located beyond the drier 39 and are provided with guides 43. The pinch rolls 4| cooperate with the pinch rolls 29 to maintain the desired tension on the strip between them, so that loops of suitable depth to give the proper'lmmersion of the strip in the pickling tanks will be obtained.

.While we have illustrated pickling tanks as the descaling apparatus, any other apparatus capable of removing the scale from the strip may be substituted therefor, for example, centrifugal blasting apparatus.

A second looping pit 44 is disposed adjacent the pinch rolls 4|. It is provided with a dancer roll 45 reciprocable between vertical guides 46 and having a counterweight 41. The dancer roll 45 maintains aloop of variable size in the pit 44.

Pinch rolls 48 driven by a motor 49 cooperate with the pinch rolls 4| to maintain a loop of strip in the pit 44, as illustrated, ander normal running Guide conditions. A shear 50 driven by a motor 5| is similar to that shown at 23 and serves to cut out the stitched Joint between successive lengths of strip when they have passed through the treating zone, e. g., the pickling tanks, wash tanks and drier.

A tilting conveyor section 52 is located beyond the shear 50 for the same purpose as the tilting section "adjacent the shear l8. The conveyor section 52 is carried on a table 53 having skids leading from the section 5| to an oiler 54. The latter includes a pair of polished rolls 55 journaled in suitable housings 56 and provided with means (not shown) for directing oil jets onto the rolls. The latter apply a film of oil to the strip passing therebetween.

A recoiler 51 is disposed adjacent the oiler and is driven by a motor 58. Guides 59 serve to direct strip issuing from the oiler into the recoiler. The latter, of course, recoils the strip for delivery or further processing operations.

The control The uncoiler motor 2| has its armature connected across busses 60 and GI in series with a main switch 62. For simplicity, the latter is illusor other remote control. The motor 21, driving the pinch rolls 25, may similarly be connected to the busses by a switch 63. The motors 2| and 21 and the speed reducers through which they are connected to the uncoiler and the pinch rolls are designed so that the peripheral speed of the uncoiler rolls and the pinch rolls will be approximately the same. In order to permit variations in this speed, we provide a rheostat 64 for controlling the field windings of the motors 2| and 21. The latter are connected in series with the rheostat 64 between the main bus 50 'and an excitation bus 65. I l The

motors

38 and 42 driving the pinch rolls 2 and 4|, which feed strip to the descaling 'means and d'raw it therethrough, respectively, are operated continuously. They are simultaneously connected to the main busses by the closing of a switch 66, and the speed of the motor 42 is equalized with that of the motor 30 by a rheostat 81 connected in the circuit.of the field winding of the motor 42 and actuated by the dancer 'roll 33. A rheostat 68 in the circuit of the field winding of the motor 30 permits the speed of the latter to be controlled as desired.

The motor "driving the pinch rolls 48 may be connected across the main bus by a switch 59. The speed of this motor is normally controlled by a rheostat .10 in the field circuit thereof.

The motor 58 may be connected across the main busses by moving a switch 12 to the left. It may also be connected across the bus 6|! and an auxiliary bus 13 by moving the switch 12 to the right. The bus 13 is connected to a current source having a voltage higher than that of the bus 5|, whereby high speed operationof'the motor 58 is obtained for purposes which will be explained shortly. A manual field rheostat 1 la provides for adjustment of the speed of the motor 58.

The method I2, and thence onto the cradle rolls of the uncoiler. The motor 2| is then energized by closing the switch 62 to feed the end of the coil between the pinch rolls I6 and the leveling rolls l1 across the conveyor section l9 and through the shear l8. When the end of the coil has passed through the shear, the motor 2| is stopped and the shear operated to crop the leading end of the strip and provide a square end. During this time, the trailing end of the previous strip length is disposed between the jaws of the stitcher 2-3.

- The squared end of the new coil is again fed forward by energizing the motor 2|. The leading end of the new coil is then laid on top of the trailing end of the preceding coil, overlapping it by approximately one foot, the overlap being between the dies and punches of the stitcher. Operation of the stitcher motor 26 causes the punches and dies to form interengaging lugs and slots in the two strip ends. To look the stitch, it is subjected to tension. The hold-down 24 is advanced so that it grips the end of the new coil. The motor 2'! driving the pinch rolls 25 is then energized to exert a pull on the trailing end of the preceding strip length. As a result, there is a slight relative movement between the two strips and the stitch is locked. The hold-down 24 is then raised and the motors 2| and 21 simultaneously energized to pass the strip through the pinch rolls 25' forthe purpose of flattening it. After the strip has passed through the pinch rolls 25, one of the pinch rolls is retractedrelative to the other whereby to release the grip previously exerted on the strip thereby.

While the operations just described are being effected, the pinch rolls 29 and 4|, continue to operate to feed through the descaling-zone the-excess strip accumulated in the looping pit 28. This excess strip is provided by operating the uncoiler at a speed which will deliver strip to the pit faster than it is drawn therefrom by the pinch rolls 29. As shown in the circuit diagram, the motors driving the pinch rolls 29 and 4| are independent of all the other motors so that they are not affected by the operations necessary to attach one length to another or, as will be described presently, to sever successive lengthsafter they have been descaled. It will also be apparent thatthe control system provided for the motors 2| and. 21 permits theuncoiler I4 and the pinch rolls 25 to be operated independently or together and, if the latter, their speeds can be jointly varied. This independence between the speeds of operation of different portions of the apparatus is one ofthe important advantages of the invention.

The dancer roll 33 operating the rheostat 61, as already indicated, causes the speed of the motor 42 to be so adjusted relative to that of the motor 30 as to maintain the proper amount of material between the pinch rolls to provide the desired depth of immersion of the material in the several pickling and wash tanks.

Under normal running conditions, the recoiler '51 is operated at a speed suflicient to coil the material substantially as fast as it is delivered from the descaling zone. The upper roll of the pinch rolls 48 is retracted and the motor 58 is controlled by the rheostat 1|a to maintain the desired loop in the pit 44. This loop is preferably a minimum as the end of a length approaches and a, maxi-' mum after cutting out the stitch and. starting a new coil, but no piling up of material in the pit 44 should be permitted as scratches would result.

75 When the stitch comes alonz, the operator low-'- ers the top roll-of pinch rolls 48 and stops the pinch roll motor 49 and the coiler motor 58. The

shear 50 is then operated to make a cutjust ahead .of the stitch. As soon as this has been done, the

coiler motor 58 is driven at maximum speed by moving the switch 12 to the right. The free end of the preceding strip length-is thus ,wound up quickly on the'recoiler. As soon asit has been completely coiled, .the motor 58 is stopped, the coil is removed from the coiler spindle by any convenient means, and preparations made to at tach the leading end of the succeeding strip thereto. In the meantime, the pinch rolls 48- are driven by energizing the motor 49 to pass the stitch through shear 50. After stopping the motor 49, a second cut is then made to sever the stitched joint. The motor 49 is again started and the pinch rolls 48 feed the leading end of the succeeding strip length across 'the conveyor 52 and the table 53 between the rolls of the oiler 54 and the guides 59 to the recoiler spindle to which it is secured.

During the severing of the stitched joint, strip continues to issue from the pinch rolls 4|, in-.

creasing the size of the loop in the pit 44. The operation of cutting out the stitch and starting the succeeding length of strip onto the coiler is usually completed before the loop reaches the bottom of the pit 44. To prevent further piling up of strip the

motors

30 and 42 can be slowed down by rheostat 68. Slowing down the strip in the. pickling tanks is not objectionable as it does not mark the strip as a complete stop does.

The accumulated excess of strip in the pit 44 is gradually removed after the leading end of the following length of strip has been started on the coiler by reconnecting the motor 58 to the bus 6 retracting the top roll of pinch rolls 48, and controlling the speed of the motor by the manual rheostat Ila.

Normal operations continue until the trailing end of the length being uncoiled approaches the shear I8. At that time, the uncoiler motor2l and the pinch rollmotor 21 are stopped. The shear 8 takes a croppingcut from the end of the strip. The pinch roll motor 21 is again energized to ad- Vance the squared end of thestrip to the stitcher 23 where it awaits the squared leading end of the succeeding strip length.

It will'be apparent from the foregoing description that the invention is characterized'by nu? merous features of advantage. In the first place, the strip is fed continuously through the descaling zoneso that all portionsthereof are subjected to precisely the same treatment. The speed of the motors driving the pinch rolls which forward the strip through the zone is such that the desired descaling treatment will be effected. The control of these motor's is entirely independent of all the otherdevices, and the provision of the looping pits makes it possible to attach successive lengths together and shear them apart without stopping the travel of the material through the descaling zone.

The uncoiler not only prevents fluting and cross breaks but also loosens the scale on the strip to a certain extent, facilitating final scale. removal. It also'permits the material to pile in the looping pit 28 without injury;

The conveyor section l9 permits the free end 'of a coil to be fed forward without catching or The stitcher pinch rolls and the shear pinch rolls grip the strip only when. stitching or shearing so that accurate matching of the speed of these rolls withthat of the other parts is not necessary. p

The arrangement of the drier is such as to ,blow the moisture oh the strip so that it dries very quickly.

Although we have illustrated and described but;

one preferred embodiment and practice of the invention, it will be understood that changes in the construction or procedure may be made without departing from the spirit of. the invention or the scope of the appended claims.

We claim:

v 1. In a method of treating coiled strip having an adherent but removable surface layer thereon,

the steps including unwinding a coil of strip, ad

vancing the end thereof longitudinally along a predetermined path, maintaining the strip continuously in motion while traversing one portion of said path, removing said layer progressively while the strip traverses said portion of its path,

accumulating an excess of strip at a point in said path ahead of said portion, unwinding a second taching the leading end of a second length to the trailing end of the first, arresting the junction between the lengths, shearing the trailing end of the first length from the leading end of the second after the latter has traversed said zone, while maintaining continuous movement of the second length through said zone, and accumulating an excess of strip between said zone and the point of shearing.

3. In a method of treating coiled strip, the steps including uncoiling a length of strip, ad-

vancing the leading end thereof; and passing,

the strip continuously through a descaling zone, attaching the leading end of a second length to the trailing end of the first, shearing the trailing end of the that length fromthe leading end of the second after the latter has traversed said zone, while maintaining continuous movement of the second length through said zone, and accumulating an excess of strip between said zone and the point of shearing.

4. In a strip descaling line, the combination with an uncoiler, a stitcher adapted to join the adjacent ends of successive coils of strip, a looping pit adapted to receive surplus strip, descaling means, means for continuously feeding strip through said means, a shear for severing adjacent coils, a recoiler adapted to receive and coil descaled strip, anda looping pit between the desealing means and the recoiler.

5. In a strip handling apparatus, the combination with an uncoiler adapted to unwind strip from a coil, and pinch rolls cooperating therewith to feed the strip forward, of a motor for driving the uncoiler and a motor for driving the pinch rolls, separate means for starting and stopping said motors, and common means for varying the speed of said motors.

6. In a strip handling apparatus, the combination with descaling'means, a stand of pinch "rolls at each end of said means forpassing strip therethrough, of a motor driving each stand of pinch rolls, common means for starting and stopping said motors, and independent speed control means for each of said motors.

'7. Strip-handling apparatus comprising an uncoiler, feed-in pinch rolls, entering and exit descaler pinch rolls, feed-out pinch rolls and a coiler, separate motors for driving said elements, and common means forcontrolling the motors driving said descaler pinch rolls independently of the motors driving the other elements.

8. In a method of treating strip, the steps ineluding passing strip continuously through a descaling zone, normally coiling it at a point beyond said zone substantially at the same rate at which it is passed through said zone, severing the strip into two pieces at intervals, arresting the leading end of the trailing piece while continuing to pass the body of the trailing piece through said zone and accumulating excess strip between said zone and the point of severance,. coiling the trailing end of the leading piece, then coiling the leading end of the trailing piece at a rate greater than that at which it is passed through said zone.

- RAYMOND J. WEAN. I

'DONALD A. McARTI-IUR.