US1810167A - Art of rolling metal - Google Patents

Description

June 16, 1931.

w *0 MC C J. R. GEORGE 1,810,167

ART OF ROLLING METAL Filed April 10, 1929 involves the production,

Patented June 16, 1931 UNITED STATES PATENT OFFICE JEROME'R. GEORGE, 013 WORCESTER, MASSACHUSETTS, ASSIGNOR TO MORGAN CON- MASSACHUSETTS Application filed April 10,

The present invention relates to improvements in the art of rolling metal, the same being particularly applicable to the rolling of metal strip. Strip rolling, as it is called, u'suallyby wet rolling, of flat elongated pieces of relatively small cross section and thin gauge.

In rolling strip or other metal products continuously, by passage of the stock through a succession of roughing and finishing stands of rolls, it is necessary, at intervals, to shut down the mill, in order to replace those rolls, particularly in the finishing train, whose working surfaces have become badly worn or grooved; otherwise, it is impossible to secure uniformity of gauge in the product of the rolling mill. The worn and grooved rolls so removed have their surfaces restored by turning or grinding them down to a smaller diameter, after which they can be reincorporated in the mill to replace another set or sets of rolls of correspondingdiameter whose wear has become excessive.

The usual practice is to put in new largesize rolls at the end of the finishing train, and to gradually work them back, after successive resurfacings (involving successive reductions of diameter), toward the other end of the mill. As a result of this practice, most strip or similar continuous mills have rolls thatincrease in diameter toward the end of the finishing train and decrease in diameter toward the beginning of the roughing train,a condition that is not conducive to the attainment of the desired relatively heavy reductions in the roughing train, because small-diameter rolls are subect to breaking or excessive springing under the heavy strain of large reductions.

According to m invention, the usual gradation of roll diameters in the strip or other rolling process, as above described,l is

I reversed; I provide and maintain the re as hereinafter set forth, with larger diameters in the roughing operation than in the finishin operation,--thus to secure the benefits of eavy reductions in the roughing operation of the mill, without any sacrifice of accuracy of gauge in the finished product. The above and other objects and advantages ish in diameter from the beginning ART or noLLING METAL 1929. Serial No. 353,970.

of my invention will appear from the following detailed description; thereof, taken in connection, with the accompanying drawings, in which r Fig. 1 is a cross sectional view, showin schematically an arrangement of strip mi 1 rolls adapted to the practice of my invention.

Fig. 2 is a similar view, showing a modification of the arrangement of Fig 1.

Like reference charactersv refer to like parts in the different figures.

Referring first to Fig. 1, the group of rolls designated as 1 illustrate the roughing rolls, and the roup of rolls designated as 2 illustrate the nishing rolls of a strip mill, in which the stock 3, of greatly exaggerated thickness, relative to the roll sizes, passes through the successive'roll stands in the direction of the arrow A. As will be noted, the successive pairs of rolls gradually diminof the roughing train to the end of the nishing train,the first stand of roughing rolls 4, 4

being the largest rolls of the entire mill,

and the successive stands of rolls 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, and 11, 11 being adually reduced in size, so that. the final nishing rolls 12, 12 are the smallest rolls of the entire mill. The relatively large size of the roughing rolls 4, 4, 5, 5, 6, 6, 311(17, 7 gives them a heavy and permits of correspondingly heavy reductions in the thickness of said material by each of said pairs of rolls, say, for example, a fifty per cent reduction in each stand of rolls of the roughing mill.

Hence, as distinguished from the rolling of strip by the usual methods, my invention permits the bulk of the required reduction in thethickness of the stock to be accomplished in the roughing mill 1,leaving only a relatively small proportion of said reduction to be accomplished in the finishing mill 2. For example, assuming, as aforesaid, a fifty per cent reduction in each stand of rolls of the roughing mill 1, the successive stands of rolls 8, 8, 9,9, 10, 10, 11,11 and 12, 12 of the finishing mill, which gradually diminish in size, maybe called upon to acdraft on the material 3' complish, respectively, reductions of forty, thirty, twenty, fifteen and ten per cent,-

these involving draftsthat are relatively b light, and therefore conducive to the production of strip of uniform gauge in the absence of excessive wear, particularly in the last two or three stands of finishing rolls. With this arrangement, the most rapid wear occurs in the roughing rolls 4, 4, 5, 5, 6, 6, and 7, 7, where, obviously, its efiect on the stock is least harmful; that is to say, the amount of wear that would necessitate the replacement of a finishing roll is considerably less than that which would seriously affect the operation of one of the roughing rolls of my improved strip mill. Hence,

with rolls arranged as above described to minimize the work required to be done by the finishing rolls of the mill, there is much less frequent necessity to shut down the mill for the replacement of worn rolls, than in the ordinary strip mill. As excessive wear develops, for example, in the, larger rolls 4, 4 of the roughing train, said rolls may be replaced with new rolls of the same size, and the worn rolls-may be resurfaced by turning or grinding them down to a smaller diameter, so as to serve as replacements for the next smaller rolls 5, 5; and so on, graduall working them forward in the mill, after successive resurfacingsto serve as replacements for the several smaller and smaller pairs of rolls of the roughing and finishing trains.

Substantially the same advantages of operatlon, as those above described, are possessed by the strip mill of slightly modified form shown schematicall in Fig. 2, where a roughing train of rolls 1s designated at 13, an intermediate train at 14, and a finishing train at 15. The several roll stands of roughing train 13 are provided by large rolls 16, 16 of preferably uniform size, say, for example, eighteen inch rolls; in like manner, the smaller rolls 17, 17 of the intermediate tram 14 may be sixteen inch rolls, and the still smaller rolls 18, 18 of the finishing train 15 may be, for example, twelve inch rolls. The use of relatively large roughing and intermediate rolls 16, 16 and 17, 17 permits, as before, the heaviest drafts on the stock in advanceof the latters passage through the finishing rolls 18, thus effecting the bulk of said stocks reduction in the roughing and intermediate ortions of the mill, and leavin onl a relatively small reduction to be effected y the rolls of the finishing train 15.

In both forms of the invention here shown, the arrangement by which the roughing rolls are enabled to effect the bulk of the required reduction in the thickness of the stock before the finishing rolls are reached, has the effect of heating up the stock sufliciently so as to counteract the drop in temperature that almost invariably occurs in wet rolling, by the time the stock reaches the finishing rolls. In other words, y my invention, the initial reductions can be made heavy enough to maintain the temperature of the stock substantially uniform from one end of the mill to the other, in

spite of the tendency of the stock to cool' off, toward the finishing rolls', from its exposure to the water used in wet rolling.

The arrangement of Fig. 2 permits, if desired, a variation of the method of roll replacement which applies to Fig. 1. For instance, the final roughing rolls 16,16,.when worn, may be replaced by new rolls, the worn rolls, after dressing to a smaller diameter, may be worked backward in the roughing train 13, as illustrated by the broken lines in Fig. 2. The same procedure may be adopted for replacements in the intermediate train 14 and in the finishing train 15. When successive reductions of one of the larger rolls 16 has made it too small to use any longer in the roughing train 13, it

becomes available for the intermediate train 14, and similarly, a correspondingly reduced roll 17 of the intermediate train becomes available for the finishing train 15.

I claim,

1. In the continuous rolling of hot metal, the improvement which consists in passing the'stock through successive stands of rolls that decrease in diameter from the roughing to the finishing end of the mill, and causing the larger rolls to procure the bulk of the required reduction in thickness of said stock, thereby to heat up said stock sufiiciently so that its temperature is substantially maintained during the finish rolling thereof.

2. The herein described method of wet continuous rolling in the production of g sists in procuring in effect a reduction by each of said stands of rolls that is substantially in proportion to the thickness of the stock as it enters said stand.

4. A two-high continuous wet rolling mill for the production of metal strip, or other rolled product, comprising a train'of roughing rolls having larger diameters than the other rolls of said mill, whereb the reductions made in said roughing rol s can be of suflicient' magnitude to maintain the temerature of the stock substantially uniform rom one end of the mill to the other. 1

' 5..A mill for rolling strip and the like,

having roughing rolls of large diameter and 5 finishing rolls of smaller diameter, for

vheavy'and lightdrafts, respectively.

6. A mill for rolling stripand the like, having successive stands of rolls-that decrease in diameter toward the finishing end 7. A mill for rolling strip and the like, having its initial standsof rolls of larger diameter than its final stands of rolls, for heavy initial reductions. J

8. A mill for rolling strip and the like,v

having roughing rolls of large diameter, intermediate rolls of smaller diameter, and finishing rolls of still smaller diameter than said intermediate rolls, for reductions in proportions to siid diameters.

' 9. In the art of rolling metal by passa through successive stands of rolls, all su ject to replacement as wear develops, the improvement which consists in working the replaced rolls',after each resurfacing thereof by reduction of diameter, through succes-' sive positions in the mill, from the roughing to the finishing end. I

JEROME R. GEORGE.

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