US530094A - Method of and apparatus for rolling sheet metal - Google Patents

Description

(No Model.) I

-S. A. DAVIS. METHOD OF AND APPARATUS FOR RGLLING SHEET METAL- Patented Dec. 4, 1894.

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STEWART DAVIS, OF APOLLO, ASSIGNOR TO THE APOLLO IRON AND STEEL COMPANY, OF PITTSBURG, PENNSYLVANIA.

METHOD OF AND APPARATUS FOR ROLLING SHEET METAL.

SPECIFICATION forming part of Letters Patent No. 530,094, dated December 4, 1894.

1 Application filed May 1, 1894. Serial No. 509,660. (No model.)

To all whom it may concern:

Be it known that I, STEWART A. DAVIS, a citizenof the United States, residing atApollo, in the county of Armstrong and State of Pennsylvania, have invented or discovered certain new and useful Improvements in Rolling Sheet Metal, of which improvements the following is a specification.

The invention described herein relates to certain improvements in the manufacture of sheet metal.

In order to prevent the chilling of the sheets in rolling small gages, by contact with the rolls, it is necessary that the latter should be heated to such a temperature as will avoid material chilling. After the rolls have become properly heated, contact with the sheets will maintain them at the desired temperature. It has been ascertained that if both rolls be made true cylinders, so that when cold they will be in contact throughout their entire length, when heated the rolls will become convexlongitudinally. Thisconvexityarises from the different temperatures of the rolls at different points, and consequent differences of expansion. The hottest portions of the rolls are about midway of their lengths, and as the rolls will expand more at that place, it results that when the rolls have been sufi'iciently heated to prevent material chilling of the sheets, they will be in contact only about midway of their lengths. To overcome this difficulty, one or both of the rolls are made concave longitudinally, the concavity being proportioned to the expansion of the rolls when heated, so that when properly heated, the rolls willbe in contact throughout their entire lengths.

It has heretofore been the practice in order to bring the rolls to a proper heat and shape, to roll small gagesor thin sheets, tobegin by rolling starting iron or what might be termed seconds. The operation is begun with sheets say about twenty inches wide, or of such a width as compared with the rela tive concavity and length of the rolls, that when the sheets have been passed between them, the variation in thickness at the edges and middle portions of the sheet will not be detrimental to that class or kind of sheets. After the portions of the rolls in contact with such sheets have become heated and expandecl, wider sheets, say, twenty-two inches in width, are rolled for a time, thereby effecting the heating and consequent expansion along greater portions of the rolls. The roller continues to roll wider and wider sheets, un-

til the rolls have become properly heated and expanded so as to be in contact throughout their entire lengths, when the rolling of the smaller gages of sheets may be commenced.

It frequently happens that all or nearly all the orders in a mill, .call for firsts or thin gage sheets, but a large quantity of seconds or starting iron must be rolled before the production of firsts can be commenced. At the beginning of a week after the rolls have become cold, it requires about six hours continuous rolling of seconds to properly heat and expand the rolls, and at the beginning of each turn, 2'. 6., two or three times in twentyfour hours, or whenever the rolls have been idle for some time, the rolls must be operated on seconds for about an hour before they can be employed in rolling firsts. It will be readily understood that under such circumstances, which are by no means exceptional, the cost and labor of rolling firsts is greatly increased, as the seconds must be stored up as stock, and frequently sold at a loss.

The object of the present invention is to provide for the preparation of the rolls for the production of any.width or gage of sheets, without their preliminary operation on inferior classes orv kinds of material.

In the accompanying drawings forming a part of this specification, Figure 1 is a front elevation of a mill having-my improvement applied thereto, and showing the heated rolls in working contact. Fig. 2 is a sectional elevation of the mill. Figs. 3 and 4 are elevations of rolls, illustrating different constructions of rolls, and Fig. 5 is a diagrammatic view.

,In the practice of my invention,the rolls 1 are constructed as regards their necks or journals, and mounted in their housings 2, in the usual or any suitable manner. As shown in Figs. 3 and 4, the rolls are made one straight and one concave longitudinally, or both concave longitudinally, so that if placed together when cold they will be in contact with each other only at or near their ends.

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In order to roll small or thin gages, these rolls must be proportionallyheated, thereby eitecting a proportional expansion, to bring them to a true cylindrical shape, or in contact throughout their entire lengths. As the middle portions of the rolls have the smallest di ameter such portions must be heated more highly to eitect a greater expansion. To effect this higher heating and also to avoid the production of sheets diltering greatly as regards the thickness at their edges and middle portions, the preliminary heating is commenced with comparatively narrow sheets, say, about twenty inches wide. By reference to Fig. 5, where the width of the sheets as compared with the lengths of the rolls is indicated by the lines a, a, it will be seen that while there will be such a difference in thickness between the middle and edge portions of the sheets after passing between the rolls as to prevent their classification as firsts, it will not be great enough to render the sheets useless. By the continued rolling of the twenty inch sheets the middle portions of the rolls become heated and expanded, so that wider sheets, e. g., twenty-two or twenty-four inch sheets, as indicated by the lines I), b, and c, 0, may be rolled without producing too great inequalities of thickness. The passage of these wider sheets between the rolls not only increases the heat at the middle portions ofthe rolls, but also extends the heat at the middle portions of the'rolls, and also extends the heating and consequent expansion toward the ends. As the heating and expansion extend, wider and wider sheets are rolled until the rolls have been heated and expanded into contact with each other throughout their entire lengths, as shown in Fig. 1. Until the rolls are thus in contact the smaller gages of sheets cannot be rolled, on account of the gap or space between the middle portions of the rolls. To avoid this laborious and expensive manner of heating, I arrange a heating device in such relation to the rolls that the heat produced thereby will operate on the rolls at or near their line of contact with each other and in order that all portions of the rolls may be brought in contact with the heat to avoid undue heating of certain portions, the rolls are rotated. At the beginning of the heating operation, the rolls are slowly rotated, but as they become heated the speed of rotation is gradually increased. The heat thus applied is regulated in accordance with the degree of expansion required at dilferent points of the rolls, the greatest heat being applied to the portions of the rolls having the smallest diameter. A convenient means of thus heating the rolls consists in a gas burner 3, connected by a pipe at to a suitable source of supply and arranged in such relation to the rolls that the jet or jets therefrom will impinge upon the rolls at or near their line of contact and about midway of their length or at the points of greatest concavity.

In using my improvement, the gas is ignited distributed between the rolls, thus avoiding any inequalities in heating and consequent expansion. As the rolls become heated their speed of rotation is gradually increased.

By the use of my improvement the rolling of the smallest gages and any desired widths of sheets may be commenced as soon as the turn comes on at the beginning of a week. In case one turn finishes rolling its quota of sheets before another comes on, or any other delay in the continuous operation of the mill the gas can be ignited and the rolls kept in proper condition for immediate operation by the next turn.

As shown in Figs. 3 and 4, one of the rolls may be made concave and the other a true cylinder or both concave. \Vith either construction, the concavity is so proportioned that when proportionallyheated the rolls have their faces parallel or approximately parallel throughout the entire length of their working portions.

It will be observed that heat is applied to the rolls at the points of greatest concavity, as such portions must be expanded more than other parts, in order to bring the rolls to cylindrical form. The heat thus applied is conducted by the metal toward the ends of the roll or points of lesser concavity, and will gradually decrease in intensity correspondingly to the decrease in concavity.

I claim herein as my invention 1. The method herein described of bringing the ordinary mounted metal rolls of a sheet rolling mill from the concave condition in which they normally are when cold, to or approximately to, the cylindrical condition required in first class sheet rolling, by applying a high heat to the surface of such rolls proportional to the concavity thereof while being driven and while rotating in contact with each other, for a considerable length of time, Wherebyto remove, so far as practicable or desirable, the concavity normally existing in the rolls when cold, and to bring them into condition for use in the rollingot first class stock, substantially as set forth.

2. The combination of a pair of rolls for rolling sheet metal one of which is concave longitudinally, and means for applying a regulated heat to the rolls at the point of greatest concavity, whereby said rolls are brought into substantial parallelism with each other, substantially as set forth.

In testimony whereof I have hereunto set my hand.

STEIVART A. DAVIS.

Witnesses:

DARWIN S. WoLoo'rT, F. E. GAITHER.

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