US2287380A - Metal rolling - Google Patents

Description

June 23, 1942. c. JJKLEIN ETAL METAL ROLLING Filed Jan. 30, 1940 IN o Clarenc @in Erb-est ger '5mm M HTTONE YS Patented June 23, 1942 METAL ROLLING Clarence J. Klein, Hollidays Cove, W. Va., and Ernest W. Rieger, Bloomingdale, Ohio Application January 30, 1940, Serial No. 316,314

6 Claims.

Our invention relates broadly to the art of metal rolling, and more particularly to the treatment of wide and thin varieties of metal. The invention is of great value in the treatment of tin plate in coils and will be described in connection therewith, but is also useful in connection with sheared lengths of material. Tin plate is commonly made of mild steel in widths up to 42" and of a thickness of .006" and heavier. A typical tin plate steel has the approximate analysis: carbon 0.04 to 0.12; manganese 0.30 to 0.50; phosphorus up to about 0.04; sulphur up to about 0.05, the balancev being substantially iron.

Cold reduced tin plate is commonly made by hot rolling steel slabs of approximately the aforesaid analysis into coiled strips of desired width, length, and thickness. The hot rolled strip of a thickness `of about 0.08" is pickled, usually in sulphuricacid, to remove the scale, and then cold rolled to a thickness slightly greater than that required in the completed tin plate, which has a thickness of .006" and heavier. Cold rolling increases'the hardness and tensile strength Aof the metaland decreases the ductility. For .exampleLthe' hardness of the cold reduced strip will be of the order of 80 on the Rockwell 30-T scale and the ductility has an Erichsen value of about-2.10 m. m. on 85 pound stock. Strips,

' coi1s,.or sheets in this condition are usually referred to as full hard and have but limited approximately `1650 F., ii open annealed in 'a suitablle atmosphere, for afsuflcient time to make the vsteel soft and ductile. The metal is 'then slowly cooled. The steel will then have a hardness I of approximately. 60 or. even less, as

'measured'lpn the 30-T Rockwell scale and is usually spoken of as dead soft. The dead soft s tockjhasV various uses, but for many purposes, such as the making of tin can bodies, it is necessaryto considerably increase the stiffness of the metal. The added stiffness or temper is commonlyf'imparted to the. soft metal by subjectingit totemper passes. through a mill while the material 'is cold. This final cold rolling also renders``the` vsurfaces Sof the metal very smooth an 'flat. The amount of reduction by such a cold lolling or 1 l11 pe'1,ing`operationmayv for such reduction in the previous rolling operations. T

Diilculty has been encountered in imparting high temper to annealed sheets of low carbon steel. In order to produce the desired high hardness in the finished stock, the use oisteels .f of special analysis, such as so-called high carbonf steel, rephosphorized steel, etc.. has been resorted to. Such steels are dicult toroll and process and consequently,v the costs are high. Awhen expedients of'this kind are resorted to.- We have found that ordinary low carbonti'n plate stock can` berprocessed so as to impart sufiicient temper or hardness thereto to suit the de= ,j f l mand for plate which has a high tempe 1 smooth, and flat. By a high temper, we mean a hardness of from 4 to 6 on a scale where dead soft material has a hardness of 1 and the full A' to produce suilicient reduction of gauge to iin- A part the desired stilness to the sheet in onel pass, arranged in tandem with a mill having relatively large rolls which do not noticeably reduce the thickness of the strip, and whose sole function 'is to hatten and smooththe strip so as to impartthereto such a surface asis now demanded by strip users. In other words, the reductionI and tempering is substantially all done in the 4-high min in one pass. The-siightreduetion and possible slight hardening eiIect which r may be afterwards produced in the materalby the mill having relatively large rolls (e.n g., a l 2-high mill) is omy incidental to the main' function of smoothingl and imparting a high finish to the metal.

We provide means at the entering side of the 4-high mill for feeding the strip material thereto and means at the exit end of the 2-high mill for receiving the material. It is also within our contemplation to provide suitable tensioning apparatus between the material-feeding means and the -rst mill and between the second mill and vary from about 13% to aboutfl0% and does not seriously aect the 'gauge of the material. However, in very'accurate rolling, allowance is made 55 stances, it may also be desirable to provide devices for; producing constant tension in the strip at various points; for example, between the i aforesaid tensioning apparatus and the entering side of the 4-high mill, between the 4high mill and the second mill, and between the second mill another object is to provide a method and inexpensive apparatus which will accomplish these purposes at relatively low cost.

The details of our invention are more fully set forth in the following description referring to the accompanying' drawing, forming part of this speciiication, in which we have shown for purposes of illustration only. certain preferred embodiments of our`invention.

In the drawing: y l

Figure 1 is a diagrammatic representation of apparatus suitable for carrying out this invention; and l Figure 2 is a diagrammatic illustration of a modification of the apparatus shown 'in Figure 1.

In Figure 1 of the drawing we havevshown diagrammatically a simple form of apparatus suitable for the practice of our invention. As there illustrated, the apparatus for treating strip metal of a width up to about 36" comprises a 4-high mill 2 and a Z-high mill 3, arranged in tandem; a pay-oil reel or entry reel 4, disposed adjacent the entering side of the -high mill 2; a billy roll or guide roller 5 between the reel 4 and the mill 2; and a take-up reel or delivery reel 6 disposedon the exit side of the 2-high mill 3.

The 4high mill comprises a pair of metal work rolls 1 which are' held against initial deilection by a pair of cooperating backing-up rolls 8, all oi. which are suitably journaled in housingsfnot shown. The work rolls range in diameter from about 6" to about 8". The back# ing-up rolls are many times larger in diameter than the work rolls 1; for example, we have used backing-up rolls having diameters ranging from about 32" to about 38" when used in connection with work rolls of from about 6"` to about 8" in diameter and about 42 wide. But considerably larger rolls could also be satisfactorily used if desired. The work rollsare driven by any conventional means, suchas van electric motor, which may be connected by suitable means to the work rolls 1 or backing rolls 8*; or one alone of the backing rolls 8 may be driven.

The 2-high mill 3 comprises a pair of rolls 9 of any suitable diameter, such as fromy about 24" to about 36, journaled in suitable housings (not shown). 'I'he sole purpose of these rolls is to smooth and flatten the strip so the diameter of the rolls is not important, so long as the rolls have sufficient strength and are suiliciently large in diameter to perform their function. We have found that rolls of from about 235" to about 36" in diameter are quite suitable for a 42" mill, although rolls of larger diameter can be satisfactorily employed. We prefer to use iron rolls rather than steel rolls, as .we have found that iron rolls impart a smoother and more satisfactory nish -to the strip metal than do steel rolls. The rolls 9 are driven in unison in any conventional manner, such as by -an electric motor connected to the rolls by conventional means. rolls may be driven. `'I'he peripheral speed of the rolls-9 is slightly greater than the peripheral speed of the work rolls 1, so that a desired amount of tension is exerted on the strip I0 Either or both ,v

p is shown diagrammatically in'Figure 2.

between the rolls 1 and the rolls 9. The strip I0 is preferably delivered to the reel 6 under very little tension.

It is to be understood that a 4-high mill having work rolls of about '167 or upin diameter may1 be used instead oi' the 2high mill 3. Where a 4-high mill is used as the last or finishing stand, the work rolls must be relatively large in diameter, of the order of about 16" or up, to properly atten and impart a smooth finish to the strip.

'Ihc pay-off reel 4 is of the well known cone type which has a suitable retarding device associated therewith, such as the conventional motor generator set, to impose. a controlled drag or tension on the strip. The take-up reel 6 is preferably of the collapsible type and is driven in the conventional manner by a suitable electric motor.

In the operation of this mill, the strip I0 is fed from the pay-off reel 4 and over the billy roll 5, which is commonly 4made of brass to avoid scratching the strip, through the 4high mill 2, thence between the rolls 9 of the 2-high mill 3, and thence to the take-up reel 6. The pay-off reel 4 is operated so as to exert tension on the strip I0 between the reel and the work rolls 1. The work rolls 1 are adjusted to the draft necessary to impart in one pass the degree of hardness required, such as a hardness of 6 where the dead soft material has'ahardness of l, and the full hard material has a hardness of 7. A material which is 6 hard is very stiff. The draft of the mill 2, combined with'the tension imparted by the pay-olf reel 4 and the'r'olls 9 of the 2-high mill, must be sufficient to reduce the strip in an amount suilicient to impart thereto the necessary hardness and bring it-to the thickness desired in the finished strip in one pass.

We have found that in manyinstances it is advantageous to provide means auxiliary to the mills and reels for causing tension to be imparted to the strip. Apparatus with such auxiliary tensioning means and without a billy roll Inasmuch as the only difference between the apparatus illustrated in Figure l and that illustrated in Figure 2, outside of the omission of a billy roll in Figure 2, resides in the auxiliary tensioning rmeans provided in Figure- 2, the same numerals with a prime atllxed thereto will be used lto designateparts in Figure 2 similar to those already described.

Between thefpayj-oif reel 4 and the work rolls 1 of the 4-high mill 2', there is provided a plurality of spaced apart cooperating tension rolls "II and I2, the longitudinal axes of which are in substantially the same vertical plane and are parallel to the longitudinal axes of the work rolls 1'. The top of the roll I2 is preferably in substantially the same horizontal plane as'the pass line between the work rolls 1'.' The tension rolls II and I2` are of the same diameter and are mounted in any convenient supports such as brackets |3, secured to the housings I4 of the 4-high mill 2. They are connected by any convenient means to apparatus for imposing a resistance to rotation of the rolls, such as a motor generator set (not shown) The rolls II and I2 are made of metal and are so constructed and arranged that thestrip I0 may be led around them, as shown, and frictionally engage the surfaces of the rolls over arcs which aresubtended by angles of notv substantially less than hydraulic unit 2l.

. may be provided adjacent theA bottom of rolls II The rolls II and I2 are made of a diameter large enough to present sumcient strip-engaging areas to maintain the desired amount of tension `in the strip and to prevent slippage of the strip relative to their surfaces. rolls having a diameter of the order of 19" are satisfactory for use with a 42" mill.

We may also provide spaced apart cooperating tension rolls I5 and I6 between the exit side of the 2-high mill 3' and the wind-up reel 5 with the top surface of the roll I5 in substantially the same `horizontal plane as the pass line ofthe rolls 9' of the mill 3'. The longitudinal axes of the rolls 4I5 and `Iii are in substantially the same vertical plane and are parallel to the longitudinal axes of the work rolls 9'." Thev rolls I5'ar`1dv I6 are of the Asame diameter, are mounted any: convenient housings such as brackets I1', secured to'the housings I6 of the Z-high mill 3' and are driven at the same speed by any convenient means, such as by an electric'motor and Vc0ning areas to maintainthe desired amount of tenf sion in the strip and'to prevent slippage of the strip relative to their surfaces. By this arrangement, tension is imparted to the strip I as it emerges from the rolls 9,' and the strip, after it leaves roll I5, can be wound on thewind-upreel 6' with only sufllcient tension to make a snug coll.,

Adjacent the top of the roll I2, there maybe provided an idle roller or contact roller I9, which We havefound that tension relationship to a rheostat 32,'by means of which the current to the motors driving the rolls 9 may be adjusted. The tensiometer is located so that Y the roller 28 will be in contact with the bottom of the -strip I0 `and by means of the uid admitted tothe hydraulic unit, the pressure of the rollerv 28 against the strip may be controlled land consequently, the tension on the strip. The

tensiometer 25 in like manner controls the current through the motor driving the mill 2 and thus the tension of the strip between the roll I2 and the rolls 'I'. The tensiometer 2'I controls the current to the motorr driving the tension. rollers I and I6 and the tension of the strip between the rolls 9 and the roll I6.

The current control feature'is not necessary to the successful operation of the tensiometers as visual scales may be provided to indicate to the operator the tension in various parts of the strip,

and he may vvthen adjust the current to the various motors to keep the strip at the desired tension.

It is to be understood that the apparatus will operate satisfactorily without the contact rolls or idle rollers I 9, 22, 23, and 24 or without the ,tensiometers 25, 26, and 2'I, and without both the rollers and the tensiometers or with various rollers or tensiometers omitted, and that various arrangements of tensiometers and idle rollers may be satisfactory. It is also to be understood that our invention is not limited to the herein is moved into engagement with the surface of roll I2 adjacent the last point of contact of the strip Ill and roll I2, by areciprocable plunger 20 of a Similar idle rollers 22 and 23 and I5 at the point of rst contact of the strip IU andthe roll II and at the point of last contact of the strip I0' and roll I5, respectively. Likewise, an idle roller 24 may be provided at the point of first contact of the strip I0 and` roll I6. In order to prevent marking of the strip,v

.the portion of the strip adjacent the mills 2 and 3', we may provide constant tension devices 25,

` 26, and 21, located between the tension roll I2 and the rolls l', between the rolls 1' and 9', and between the rolls 9' and I6, respectively. devices are the known electric tensiometers and since the devices 25, 26, and 21 are all similar, only 26 will be described. The tensiometery 26 comprises a roller 28, rotatably mounted in one end of a bell crank lever 29, which is pivoted at 3x0. To the other end of the lever, a plunger reciprocably mounted in a hydraulic unit 3I is secured, and the end of the arm is in operative of parts may be resorted to and the invention otherwise embodied and practiced within the scope of the following claims.

` We claim:

Y l. A two-stand, skin-pass mill for imparting stiffness to strip metalwhile slightly reducing they thickness comprising a 4-.high mill having work rolls having a diameter not greater than about one-fourth of the diameter .of the backing-up rolls, a second mill in tandem with the first mill, the diameter of the working rolls of the second mill being at least twice the diameter of the working rolls in the first mill, means for introducing the strip into the first mill under' back tension, and means beyond the exit side of the second mill for exerting forward tension on the strip as it leaves the rolls of the second mill.

2. A two-stand skin-passmill for finishing strip metal comprising a first mill having small Work rolls and backing rolls with a diameter several times-that of the work rolls adapted to effect an appreciable reduction in the thickness of the strip to temper it, a second mill in tandem with the first mill, the second mill having 'large work rolls relative to the work rolls of the first mill adapted to flatten the strip without reducing its thickness materially, Aand means for'tensionlng the strip leaving the second mill.

3. A two-stand skin-pass mill for iinishing strip metal comprising a rst mill having small work rolls and backing rolls with a diameter several These 4 times that of the work rolls adapted to effect an appreciable reduction in the thickness of the strip to temper it, a second mill in tandem with the first mill, the second mill having large work rolls relative to the work rolls of the iirst mill adapted to flatten the strip without reducing its thickness materially, means for tensioning the strip between the mills, and means for tensioning the strip leaving the second mill.

4. A two-stand skin-pass mill for finishing strip metal comprising a first mill having small work rolls and backing rolls with a diameter s everal times that of the work rolls adapted to eilect an appreciable reduction in the thickness of thestrip to temper it. means for tensioning the strip entering the rst mill, a second mill in tandem with the iirst mill, the second mill having large work\ rolls relative tothe work rolls of the rst mill f' mill adapted to flatten the strip without reducing 2@ its aucxness materially, means for tensioning/me strip between the mills, and means for tensioning the strip leaving the second mill. l

6. A two-stand skin-pass mill for iinishing stripr metal comprising a first mill having small work Y rollsand backing rolls with a diameter several times that of the work rolls adapted tn eiTect an appreciable reduction in the thickness of the strip to temper it, a second mill in tandem with the first mill, the second mill having large work rolls relative to the work rolls of the ilrst mill adapted to atten the strip without reducing the thickness materially, means for tensioning the strip leaving the second mill, a coiling device for the tempered strip, and operating means for the ooiling device to coil the strip under just sumcient tension to make a snug coil. l f

CLARENCE J. KLEIN. ERNEST W. RIEGER.

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