US2204984A - Method of and apparatus for making sheets - Google Patents

Description

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4l Shets-Sheet I ATTORNEYS- June 18, 1940. R, M, FENTQN l 2,204,984

METHOD 0F AND APPARATUS FUR MARKING SHEETS Filed March 2o, 193e 4 sheets-sneer 2 INVENTOR.

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June 18, 1940. R. M. FENToN METHOD 0F AND APPARATUS FOR MAKING SHEETS Filed March 20, 1936 4 Sheets-Sheet 5 INVENTOR. y. yen dfz y gag,

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June 18, 1940. R. M. FENTON 2,204,984

UETHOD 0F AND APPARATUS FOR MAKING SHEETS Filed March 20, 1936 4 Sheets-Sheet 4 INVENTOR.

BY Kayjewow am@ f ATTO EY5 Patented June 18, 1940 UNITED STATES PATENT OFFICE METHOD OF AND APPARATUS FOR MAKING SHEETS Claims.

'This invention relates as indicated to the method of and apparatus for making sheets and more particularly to a rolling mill system and a mode of operation thereof whereby the produc- 5 tion of a uniform grade of rolled metallic sheets is made possible at a lower cost as based on the amount of capital and labor invested.

It is a further object of my invention to provide a method of and apparatus for the production of individual sheets having all of the desirable characteristics of so-called continuous strip but without requiring the expensive apparatus necessary in the production of such strip.

More specifically, it is a further object of my invention to provide a method of and apparatus for the production of rolled sheets inwhich a plurality of individual sheet bars are successively operated upon to the ultimate production of a continuous strip which is then severed into appropriate lengths for the production of nat sheets having the desirable characteristics as to uniformity in gauge and contour usually associated with continuous strip steel;

It is a further object of my invention to provide a method of and apparatus whereby a plurality of sheet bars in excess of the number usually worked together may be treated as a batch and successively subjected to various rolling operations whereby there is produced a batch of sheets of substantially identical form and with a marked saving in the cost of such production.

It is a further object of my invention to provide a particular apparatus capable of elciently and economically producing the above enumerated results.

To the accomplishment of the foregoing and related ends, said invention, then consists of the means hereinafter fully described-and particularly pointed out in the claims; the annexed drawings and the following description setting forth in detail certain means and one mode illustrating, however, but one of the various ways in which the principle of the invention may be used.

In said annexed drawings:

Fig. 1 is a side elevational view, showing part of the apparatus constructed and arranged in accordance with the principles or my invention and capable of carrying out the process comprising this invention; Fig. la is a schematic side elevational view of the remainder of my said apparatus; Fig. 2 is a plan view of the part of the apparatus shown in Fig. 1; Fig. 3 is a side elevational view ofthe rolling mill and its associated drive shown at the upper righthand end of Fig. 1; Fig.'4 is a side elevational view of an alternative form of construction of the apparatus illustrated in Fig 3; Fig. 5 is a plan view of the mill shown in Fig. i and Fig. 6 isa schematic wiring diagram of the control circuit for the apparatus illustrated in the previous *figures, particularly Figs. 1 and 2.

The methods whereby metallic sheets or strips have been rolled in the past may for' purposes of the present consideration be divided into two general classes: first, the method wherein individual relatively small sheet bars are rolled into individual sheets, in which method the principal manipulation of the work pieces was originally performed manually and in recent years supplemented by mechanical apparatus such as feeders, catchers and conveyors; second, the method whichis generally referred to as the continuous strip process wherein a relatively large billet or bar is successively rolled down to the production of a so-called continuous strip which, due to its great length, as compared to its width, is usually coiled after finishing in order to place the same in the form for convenient shipment.l In this last-named process the apparatus necessary to produce the long strip has been of necessity very expensive to the end that there are but few complete installations of this character in this country at the present time.

My invention, as previously explained, contemplates a process which may be conveniently referred to as a. combination of certain features of the previously described processes retaining the flexibility and low equipment cost of the sheet process with the desirable characteristics, so far as the finished product is concerned, of the so-called strip process.

Referring now more specifically to the drawings and more especially to Figs. 1 and 2, the apparatus herein illustrated so arranged as to be capable of performing the method comprising my invention consists of a plurality of bar heating furnaces generally indicated at i ofr which three in number have been illustrated.' Any convenient number of furnaces such as l may be employed; however, it has been found that when three such furnaces of the usual capacity are used, they are ample to supply the heated bars necessary for a continuous opera` tion of the apparatus associated therewith and in accordance with, the method presently to be explained.

Each of the furnaces l is provided with a conveyor 2 extending preferably therethrough and' arranged to carry the work bars on edge through 5'5 the furnace in the marmer generally indicated in my prior Patent No. 2,023,318, dated December 3, 1935. The furnaces I or more particularly the work conveyors associated therewith are provided with drive motors 3, d and 5 which are energized and controlled in the manner hereinafter more fully explained.

Positioned adjacent the discharge ends of the conveyors 2 and extending transversely thereof is a roller conveyor generally indicated at 6 which is driven by means of a suitable motor such as 1.

Adjacent the right hand or discharge end of the conveyor 6 there is positioned a straightening or aligning table, generally indicated at 1, which is provided with a plurality or driven rollers 8 arranged at an angle to the longitudinal axis of the conveyor 6 so that when a sheet bar is delivered endwise fashion from the conveyor 6 to the table 8, the bar will be rotated in a counter-clockwise direction as viewed in Fig. 2 until the same moves against the matching stop 9 with its-long axis arranged at right angles to the longitudinal axis of the conveyor 6, i. e., the bar is arranged in position to be presented to the mills.

'I'he straightening table 8, or more particularly the rollers thereof are preferably continuously driven by some suitable means such as a motor I which may also be employed for the purpose of continuously driving the conveyor Il gjhlilgh extends from the matching stop 9 to the In the preferred form of my invention I provide two Z-high roughing mills generally indicated at I 2 and I3 which mills are arranged in tandem with each other and with a 3-high roughing mill generally indicated at I4. The employment of the 3high roughing mill for the last roughing pass is preferred since it results in the production of a breakdown having a more uniform cross section than when the last roughing pass is through a. 2-high mill. The motor shown at I5 may be employed for the purpose of continuously driving the conveyor I5a. The motor I6 may be employed for the purpose of continuously driving the conveyor Ilia and the motor I1 may be employed for the purpose of driving the conveyor I 1a in the particular manner hereinafter more fully explained.

Positioned in alignment with the conveyor I1a is a holding furnace I8 of conventional construction and design and arranged to receive a plurality of work units issuing from the mills I2, I3 and I4 and to maintain such work pieces at a predetermined temperature or to heat the same to such te`mperaturepreliminary to their being subjected to a further rolling operation.

Leading from the discharge end of the furnace I8 is a conveyor I9 which is in reality a combined feeding and catching device associated with the mill generally indicated at 20, the construction and mode or operation of which will likewise be explained in detail.

'I'he mill 20 also has a catcher-feeder table generally indicated at 2I associated therewith. The tables I9 and 2l are employed as hereinafter more fully explained for the purpose of passing and re-passing a plurality of Work pieces arranged and treated as a batch through rthe mill until they have been reduced and accordingly elongated to the desired extent.

'I'he conveyor chains on tables I9 and 2I are respectively driven by means of spindles I9a and 2|a through magnetic clutches I9b and 2lb and are coupled for a source of power by means of aeoaaea sprocket chains I9c and 2Ic to one of the driving pinions for the mill 26.

In accordance with the method comprising my invention the work pieces after the conclusion of the rolling operation in the mill 20 are discharged into a pickling tank generally indicated at 22 from which they pass into a wash tank generally indicated at 23 in order to remove therefrom all foreign material such as dirt, scale and the like. The cleaning tank 23, it should be noted. may be constructed in accordance with the principles disclosed in my co-pending application Serial No. 62,304, filed February 4, 1936, so that a continuous line of individual sheets is discharged from the cleaning tank whereupon they pass through an end shears generally indicated at 24 which crops forward and rear ends of the sheet along the lines normal to their longitudinal axes. The end-sheared sheets then pass through a resistance Welder generally indicated at 25 which momentarily arrests the sheets and by means of the resistance ash welding process welds the forward end of a rearward sheet to the rearward end of a forward sheet to the production of a continuous strip generally indicated at 26. The strip thus formed passes through a grinder of any conventional design generally indicated at 21 which is employed for the purpose of grinding off the flash formed on the sheets by the welder. After the grinding operation has been completed the strip passes through a pair of opposed brushes 28 which finally clean the sheet of all adhering foreign material and after which the sheet or strip passes over the rollers such as 29. 30 and 3| between which the sheet is permitted to loop so that it may be drawn at a continuous rate as at 32 through one or more stands of i-high finishing mills generally indicated at 33.

After the strip thus rolled in a continuous fashion and comprising a plurality of individual components joined together by weld areas is discharged as at 34 from the finishing mills 33, the same will preferably be severed into individual units along the lines at which the sheets were originally welded to the production of a plurality of fiat sheets in which substantially the entire body thereof is uniform both as to structure and cross section.

'I'he mill 20 illustrated as being of usual 4-high design so far as the rolls thereof are concerned. is, however, novel with respect to the means which have been provided for driving the same and the manner in which the same is driven and controlled. The upper and lower work rolls are respectively driven through spindles 35 and 36 by means of independent reversable electric motors 31 and 38 and the backing up rolls are connected by means of spindles 39 and 40 to small electric motors 4I and 42 respectively. The primary or work motors 31 and 38 are as previously indicated of the reversible type and while forming no part of this invention are so constructed as to be capable of being brought up to speed in a relatively short time such as approxivmately one second and brought to a stop from full speed in an approximately equivalent length of time. 'I'he motors 4I and 42 are employed primarily for the purpose 4of overcoming the inertia of the large backing up rolls. That is, when the power is cut off of the motors 31 and 38 for the purpose of bringing the mill to a standstill preliminary to its reversal, the motors 4I and 42 are energized so as to act as a magnetic brake for the rotating backing up rolls and thereafter to assist in bringing the backing up rolls to full speed in the opposite direction. If the small diameter work rolls were relied upon entirely for this purpose undesirable relative movement between such work rolls and the backing up rolls might occur. It is believed novel to provide this type of drive for a reversing 4-high mill, l. e., where reversing motors are employed for the purpose of driving the work rolls in opposite directions and individual motors are employed for the purpose of driving the backing up rolls in opposite direction during the reversal stage so as to overcome the inertia of the large mass rolls. It will be understood that the degree of energization which the motors 4l and 42 are subjected to, i. e., the amount of driving which such motors exert upon the backing up rolls with which the same are associated. is not materially relied upon during the rolling operation to assist in driving the mill but are primarily relied upon to reverse the backing up rolls in the manner explained.

Instead of employing a 4-high mill at 28 as above explained, I may prefer to employ a reversing 2-high mill generally indicated at 88 in Figs. 4 and 5. The upper and lower rolls it and i5 respectively of the 2-high mill are connected by means of spindles 156 and 8l respectively through a gear housing generally indicated at i8 to a single prime mover such as the electric motor L39. The spindle i6 has interposed therein between the roll 815 and the driving gear on the spindle a slip clutch generally indicated at 58 which is employed for substantially the same purpose as are the motors li and @l2 in the 4-high mill. In other words, the slip clutch 58 will be so adjusted that the amount of torque capable of transmittal thereby to the upper roll 88 is suflicient to overcome the momentum and inertia of the roll during a stopping and starting in reverse direction of the mill but insumcient to drive the roll t8 at a speed different from that at which the lower work roll Q5 is driven. The provision of the slip clutch 58 makes possible, therefore, the driving of both upper and lower rolls of the 2-high mills from' a single source of power which is essential during the reversal of the mill without, however, in any way interfering with the normal operation of the 2-high mill which requires that only one roll be driven since if both rolls were driven at a constant speed,

Fig. 6 wherein the controls for the various units are shown.

The power lines from which the primary power from the mill, as well as the power for the control circuits are derived, are shown at 5l, 52 and 53.

' rI 'he motor 'F which is employed to drive the conveyor 8 has a magnetically actuated starting switch, generally indicated at 54 associated there-` with, the armature 55 of which carries a pull-in coil 56 and a holding coil 5l. The pull-in coil 56 may be connected across lines 5i and 53 either by means of the flag switch 5B or the manually operable switch 59. Connected parallel with the pull-in coil 56 and simultaneously connected across the power lines by the flag switch 58 is the actuating coil 60 of the matching stop 9 on the straightening or aligning table 1. 'I'he holding coil is connected across the power lines by means of the back contactor 6|, the circuit through which is ccmpletedthrough the iiag switch 62. The flag switches 62 and 58 are arranged adjacent the opposite ends of the matching stop 9 at its forward face with the flag switch 62 arranged to be engaged by the forward end of the bar being handled and the rear end of the bar being handled engaging the iiag switch 58.

Each of the motors 3, fi and 5 is provided with a magnetic starting switch 3a, ia and 5a respectively, the armatures of which are provided with pull-in coils 63, 64 and 65 and also holding coils 66, 61 and 68. The pull-in coils 63, B4 and 65 may be connected across the power lines 5i and 53, either independently by means of the individual start buttons 63a, 84a and 65a or simultaneously by means of the common starting switch 69. The circuit for the holding coils from the main power lines is completed through the back contactors 66a, B'ia and 68a, the individual stop buttons l0, ll and l2 and the common stop button 53. Stop switches lli, l5 and 'i6 are also included in the lines to the holding coils 66, 6l and 68 and are adapted to be energized by cams ll, 'i8 and i8 respectively, which cams are connected in any suitable manner to the respective conveyors 2 or the motors driving the same so that when the conveyor, after energization, has advanced a predetermined distance suiiicient to discharge one bar from its furnace, the cam such as 'll will engage the stop switch iii deenergizing the holding coil 56, opening the switch 3a and deenergizing the motor 3 and stopping the conveyor. The holding furnace i 8, as previously indicated, has a conveyor ila associated therewith and also as illustrated in Figs. 2 and 6, flag switches 8U and 8l. Motor il which is employed to drive the conveyor ila in the holding furnace is energized by means of a magnetic starting switch 82 which is actuated on energization of the coil 83. 'Ihe circuit across the power line to the coil 83 may be completed either by means of the manually operated switch 86 or the ag switch 88a. vThe iiag switch 8i and a time delay relay generally indicated at 8d, the energization coil 85 of which is connected across the power line through the iiag switch 88, control the energization of the holding coil 83a.

The motors 3l and 38 which are employed to drive the work rolls of the mill 2l) in opposite directions are connected in any suitable manner such as is illustrated in Fig. 6 across the power lines so as to becapable of energization for rotation in opposite directions. For example, a double throw armature 8l adapted to selectively close one or the other of two switches controlled thereby may be employed with separate coils on each such armature, one each of which may be selectively connected across the power lines by a central control switch such as 88. Depending upon the position oi the switch 88, the motors 8l and 38 will be driven in either one direction or the other.

Since the conveyors i9 and 2l are. connected by means of spindles l9a and Zia and magnetic clutches l9b and 2lb respectively with one or the other of the spindles of the motors 3l and 38, the direction of movement when energized of such tables will always be in the direction of the work movement through the mill. Some meansmust be provided, however, for insuring atl that the tables I9 or 20 will not, upon elongation f1 of the work pieces carried thereby during the rolling operation, cause such work pieces to terminally overlap. To this end ag switches 88 and 90 positioned on opposite sides of the mill are provided and interconnected with the magnetic clutches I 9b and 2lb respectively in the manner illustrated in Fig. 6.

The magnetic clutches are arranged to be connected across the power lines by means of switches such as 9| and 92 which are respectively connected with time delay switches 93 and 94, the energization coils 95 and 96 of the time delay switches being in series with the flag switches 89 and 90 respectively.

Let it be assumed that there is no work in the mill and the operator thereof desires to initiate the passage of work bars from the furnaces I through the mill. The operator will first close the common start switch 69 for the three motors 3, 4 and 5 which respectively drive the conveyors of the three furnaces. Immediately such switch is closed, it may be reopened by the operator since the holding coils 66, 61 and 68 will maintain the switches 3a, 4a and 5a in closed position until the conveyors have advanced sufficiently to discharge one bar from each of the furnaces, whereupon cams 11, 18 and 19 byadeenergization of the holding coils 86, 81 and 88 will cause the motors 3, 4 and 5 to be deenergized. Three bars have thus been discharged onto conveyor 6, whereupon the operator by a closing of switch 59 causes the motor 1 to be energized to advance the bar farthest on the right as viewed in Fig. 1 to move onto the straightening table 1. 'Ihe forward end of such bar will strike the ag switch 62, deenergizing the holding coil 51, opening the switch 2 and deenergizing the motor 1, thus stopping conveyor 8. As the bar is rotated in a counterclockwise direction until its forward edge engages flag switch 58 closing the latter, the coil 60 of the matching stop will be energized, lowering the matching stop out of the path of the bar and simultaneously reenergizing the motor 1 through the pull-in coil 56, thus restarting the conveyor 8 which will continue until the bar which was discharged from the center furnace strikes the flag switch 62, whereupon the above outlined procedure will be repeated.

As soon as the matching stop 9 has been depressed, i. e., moved out of the pathof the rst bar, it will proceed on the conveyor II successively through the mills I2, I3 and I4 onto conveyor I 1a. Immediately upon its being dis-1 charged from the mill, the bar will strike the flag switch 88a which will energize the pull-lin coil 83, closing the switch 82, energizing motor I1, causing conveyor I 1a to carry the bar towards the holding furnace. As the bar approaches the holding furnace it engages the ag switch 80 which is in series with the time delay switch 84, which controls the energization of the holding coil 83a. The effect of the time delay switch 84 is to maintain the circuit through the holding coil 83a closed for a predetermined length of time after the bar trips the flag switch 80. 'This length of time is just sumcient for the bar to move into the heating zone of the furnace whereupon the rela'y 84 will drop out, deenergizing the holding coil 83a and opening the switch 82. The next bar that issues out of the mill I4 will by energization deenergized so that no more bars can be fed into the furnace.

With the holding furnace filled or containing a sufficient number of bars to comprise a batch for rolling on the mill 20, the operator will, by closing switch Ia and manually maintaining the same closed, cause a predetermined number of bars to be discharged from the holding furnace onto the table I9. With the mill 20 being driven in the proper direction, the table I9 will progressively move such predetermined number of bars through the mill 28. After all of the bars have moved through the mill 20, the operator will reverse the switch 88, causing the motors 31 and 38 and the tables I9 and 2l to be driven in the opposite direction to effect a re-rolling of the batch of bars through the mill 20.

'I'he magnetic clutches I 9b and 2Ib are pro- Avided, as previously indicated, for the purpose of preventing the bars due to elongation from terminally overlapping on the tables I9 and 2I and the operation of such magnetic clutches is briefly as follows:

A flag switch 89 at the forward side of the mill is connected with the power lines, so that when closed, it will maintain energized the winding 95 of the time delay switch 93 by means of which latter switch, the winding |917 of the magnetic clutch is energized. Assuming that the work is progressing from left to right, as viewed in Fig. 2, the forward end of the first bar strikes the flag switch 89, causing the same to be opened. The switch 9,3 will maintain the magnetic clutch :9b energized for a length of time sumcient for the first bar to enter the bite of the mill, at the expiration of which time the magnetic clutch I9b will be deenergized and the conveyor I9 stopped until the rear end of the first bar has passed over the flag switch 89, whereupon the magnetic clutch I9b will be re-energized to start the conveyor I9 and feed the next bar into the mill. Thus, the successive bars passing through the mill are at all times spaced approximately the distance between the ag switch 89 and the bite of the mill. In a similar manner the flag switch 90 operates as the work is moving from right to left as viewed in Fig. 2 to maintain the same spacing between the work pieces during such directional movement. At this point, it should be noted that the ag switches 89 and 9U are so constructed that the switch 89 will open the line to the magnetic clutch I9b only when the work moves such switch from left to right and the flag switch 98 is constructed to open the line to the magnetic clutch 2lb only when the work moves such switch from right to left.

No provision need be'made to insure spacing of the work pieces on the conveyor at the discharge side of the mill since the speed of such conveyor is always substantially the same as the rate at which the mill is driven and the work is discharged from the mill.

The previously described method of manipulation of the apparatus, it will be noted, results in the simultaneous working of a single mill through a plurality of Work pieces which is essential if such work pieces are to be joined together in the production of a continuous strip for the rolling in a continuous fashion through a plurality of finishing mills. In other words, it is essential, when joining together a plurality of individual sheets to roll the same thereafter in strip fashion, that the contour of all of such individual components be substantially identical in order that the contour of the rolls of the finishing mill may betted in a. measure at least to the contour of the work being operated upon. In other words, it is essential that there be some relationship between the contour of the rolls of the mill 20 and the contour of the rolls of the mills 33, so that when the strip is finished in the last-named mills, the metal of the strip will flow in a uniform fashion throughout the Width of the strip which is essential in the production of a rst class sheet.

Other forms may be employed embodying the features of my invention instead of the one herein explained, change being made as regards the means and the steps herein disclosed, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed, whether produced by my preferred method or by others embodying steps equivalent to those stated in the following claims.

I therefore particularly point out and distinctly claim as my invention:

1. In a method of producing steel sheets, unlform as to gauge and having similar characteristics, the steps of hot rolling sheet bars by single passes through a plurality of breakdown mills in tandem; semi-iinishing the batch of sheets so produced by passing and repassing as a batch through a reversing mill; buttwelding the several pieces of such batch in end to end relation into a single work-piece; f ull 1inishing such work-piece on a continuous iinishing mill; and separating the several sheets along the lines of the several welds.

2. A method of producing cold-rolled sheet steel, comprising the steps of hot rolling a plurality of sheet bars by single passes through successive stands of roughing rolls in tandem; seminishing by repeated passes in batches on a reversing mill whereby a plurality of semi-iinished sheets are produced having similar cross-sections; joining the semi-iinished sheets by butt- Welding the ends, whereby a work-piece is produced; and finishing the work-piece by cold rolling on a continuous mill.

3. A method of producing cold-rolled steel sheets, comprising the steps of hot rolling a plurality of sheet bars by single passes through a plurality of roll stands, whereby work units of similar cross-section are secured; semi-finishing a batch of such work units of substantially uniform temperature by passing and repassing as a batch through a reversing mill; uniting the work units of such batch into a single work-piece by butt-welding the ends, whereby a work-piece is produced; and nishing the work-piece by cold rolling on a continuous mill; and separating the sheet along the lines of the welds.

4. A method of producing a work-piece for cold nishing on a continuous mill, comprising the steps of hot rolling a plurality of sheet bars by single passes on successive stands of rolls; semifinishing a batch of sheet bars so rolled by repeated reductions of same as a batch on a reversing mill, whereby a plurality of semi-finished sheets of similar cross-section are produced; and joining the semi-iinished sheets by butt-welding the adjoining ends thereof.

5. In the formation of a work-piece suitable for full-finishing on a continuous cold roll mill, the steps of forming breakdowns by rolling a plurality of Work-pieces on a tandem mill comprising a plurality of two-high stands; semi-lnishing said breakdowns by reversing passes on a finishing mill; and uniting the`semi-finished sheets by butt-welding into a single work-piece.

RAY M. FENTON.

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