US1754745A - Rolling strip metal - Google Patents

Description

April 15, 1930.

c; H. YELLIQTT ROLLING JSTRIP METAL Filed June 13. 1929 3 Sheets-Sheet 1 web a -2 INVENTOR Y April 15, 1930. c. H. ELLIOTT 1,754,745

ROLLING STRIP METAL Fi ed June 15. 1929 3 Sheets-Sheet 2 {J INVENTOR lifiw I CENTER LINE April 15, 1930. c. H, ELLI TT 1,754,745- I ROLLING STRIP IIB'IAL Filed June 13, 1929 3 Sheets-Sheet 3 'CONVEXILFY FLAT CONCAVITY PAss INVENTOR aw REM so-called Patented Apr. 15, 1930 UNrr o STATES PATENT OFFICE CHARLES H. ELLIOTT, OF YOUNGSTOWN, OHIO, A SSIGNOR TO REPUBLIC IRON AND STEEL COMPANY, OF YOUNGSTOWN, OHIO, A CORPORATION OF NEW JERSEY ROLLING STRIP METAL Application med June 13,

This invention relates to the rolling of strip, metal, and is of particular value in the rolling of wide thin material.

In the rolling of wide thin strips, such as strip-sheet, the amount of crown or fullness of the final product is of importance to the consumer and is also of considerable importance to the manufacturer in that the presence of too much fullness in the material, either as delivered from the last pass of the rollingmill or as delivered from the several passes preceding the final pass, may result in riflling of the product at the edges. If too much rifliin occurs, the material is uncommercial an difficulty is encountered in guiding it through the mill. It has heretofore been suggested that in order to satisfactorily roll wide thin material by a continuous process, there should be supplied to the roll train a piece which is convex in cross section, and that the amount of convexity should be progressively reduced in the several stands.

According to the proponents of this system, the factors of roll contour, roll temperature, composition and springiness of the rolls,

spacing of the rolls; and shape, composition,

and temperatureof the piece, must all be taken into account and the successive roll stands so controlled as to provide an active pass in each stand which is less convex than the piece delivered to it from the preceding stand.

According to this system of rolling, it IS necessary for highly skilled workmen to watch the several stands of rolls to the end of controlling the variable elements and thus maintaining the desired progressively decreasing convexity in the several stands. It is also suggested by the proponents of this system that furnaces should be placed be- 7 tween the several stands so as to carefully control the temperature of the ieces.

I have found that by using mill stands having backed working rolls, as for example fourhigh mills, it is possible to eliminate the large amount of skilled labor required in the system above referred to, to eliminate furnaces be tween mill stands and to successfully roll wide thin material at high speed. In order to at- 1929. Serial N0. 370,685.

tain these results it is necessary to maintain the piece sufiiciently fiat in the several stands to permit of controlling its direction by side guides. In other words, instead of depending on the convexity of the piece to cause it to track through the stands, I maintain the piece substantially flat in the several stands and use side guides to control it. The backed mills are inherently so stiff that the large roll spring which is characteristic of two-high sheet mills is substantially reduced and it is, therefore, possible to maintain the desired degree of flatness in the piece at all stages. Instead of supplying a convex piece to the backed mills, I supply a piece which is flat or slightly concave. The concavity may be obtained by crowning one of the earlier sets of rolls. I prefer to have the piece slightly concave rather than flat at the beginning of the run, so that it will never become convex, even though the rolls are considerably worn.

Preferably some of the stands are operated as a continuous mill, that is to say, the piece is in two or more passes at one time. During this part of the operation the substantial fiatness of the material is particularly valuable because if the metal is properly entered into the continuous stands and is sufliciently flat, no difficulty is encountered in getting it through the mill.

Wide strip material has so much surface area, relative to its mass, that .it tends to cool very quickly, particularly in the later stages of the rolling operation. There will, therefor-e, be encountered a slight spring of the rolls in the later passes, despite the stiffness imparted by the backing rolls. On this account, I prefer that the last pass shall be a relatively light one so as to insure the desired flatness in the final product.

I also prefer'to use edging rolls during the earlier stages of the operation. These reduce the tendency to roll full in the center, thus slightly concave.

rolls in the last two-high stand, it will be stands and of temperature across the piece during rollparture of the piece from .true flatness after the several passes.

The mill shown in Figures 1 and 2 c0mprises heating furnaces 20, from which slabs are supplied to a roll table 21. The slabs pass over a table 22 employing skew rolls to a No. 1 edging pass 23. The edged iece then travels through two two-high stan s 1 and 2, then through a No. 2 edger indicated at 24. The (piece continues through two-high stands 3 an 4 and thence through a No. 3 edger indicated at 25. Beyond this edger there is provided a two-high stand 5, this being followed by four- high stands 6, 7, 8, 9 and 10. The four-high stands employ small work rolls 26 and lar er backing rolls 27 and are preferably of t e type illustrated in the Big ert and Johnson Patent No. 1,654,235. %he stands 6 and 7 are grouped together, as shown in Figures 1 and 2, and the stands 8, 9 and 1 constitute another group. These last tnree stands ordinarily operate as a continuous mill, the piece being in all of them at once during a rtion of the rolling operation.

Roll ta les 28 extend between the several stands and support the piece during its travel. The roll tables are provided with side guides as indicated diagrammatically at 29 and in rolling t ese guides are effective for properly direct' g the material into the substantially flat, the tendency of the rolls to force a sidewise movement of the piece concomitant with its longitudinal travel is eliminated or reduced to the point where such tendency can be easily resisted by the side guides without injuring the strip or causing cobbling. The rolls in the several stands are driven by motors 30, connected through gearm as shown.

11 the mill above described, I employ fiat rolls in stands 1 to 4, inclusive, and use a convex roll in stand 5. The roll is convexed in an amount suflicient to offset the natural roll spring and produce a piece which is flat or While I employ convex understood, of course, that convex rolls might be emplo ed in one of the earlier four-high stands 0 a given mill to supply a substantially flat piece to-the succeeding stands. For that matter, all of the stands might employ backed rolls, but the piece being relatively hotter and thicker in the earlier passes, it will be satisfactory to employ two-high stands for these early passes. However, the later stands should have backed working rolls and Stand No. 1, top workin roll diam eter; bottom working roll 20flt" diameter; both rolls fiat:

Stand No. 2, to working roll 21 diameter; bottom wor ing roll 21 diameter; both rolls flat:

Stand No. 3, top working roll 21% diameter; bottom working roll 21%" diameter; both rolls flat:

Stand No. 4, top working roll 22" diameter; bottom working roll 21%" diameter; both rolls fiat:

Stand No. 5, top working roll 22%" maximum diameter, crown .028'inches in diameter; bottom workin roll 22%" diameter, flat. Totalvwidth o crown on to roll is 15 on each side of the center line 0 the roll, 6" to either side of the center line of the roll being flat:

Stand No. 6, to working roll 15% diameter; bottom wor ing roll 15 diameter; both rolls flat:

Stand No. 7 top working roll 15%" diameter; bottom working roll 155-5" diameter; both rolls flat:

Stand No. 8, to workin roll 16 diameter; bottom woi ring ro 16 diameter; both rolls flat:

Stand No. 9, to working roll 165%" diameter; bottom wor ing roll 16 diameter;

iding it therethrough. By reaboth rolls flat: son of the act that the several passes are all Stand No. 10, to working roll 16% diameter; bottom wor groll 16 diameter; both rolls flat:

The diameter of the backing rolls, in each of the stands 6 to 10, inclusive, was 3 All rolls had bodies 42 long.

The analysis of the steel being rolled was as follows:

ler cent Carbon O8 Manganese 39 Phosphorus 012 Sulphur 029 The slabs used were x 2 x 58 and were successively reduced in stands 1 to 5, inclusive, so that the material when it issued from stand No. 5 had a thickness on the center line of .327", and b reason of the crowning of the top roll in t 's stand showed a concavity at the center of approximately .0Q3"..

' Figure 3 shows lines 5 to inclusive, illustrating the contour of the piece after leaving each of the passes 5 to 10, inclusive. The curves of Fi re 3 were obtained by measuring the thic ess of the piece at substantially half inch intervals across its entire width and plotting the readings thus obtained. It will be understood that in this view the vertical scale has been greatly exaggerated so as to show the variations in thickness of contour.

-The following is a tabulation of the thickness at the center line:

there is produced in different stands a ar suflicient flatness to permit of contro g. it

preferred .embodiment of the invention. It a will be understood, however, that it is not .limited to the form shown, but may be otherwise embodied and practiced within the scope of the following claims.

I claim: 1. In the method of rolling strip metal in backed mills, the steps consisting in passing material through successive roll stands, en-

After leaving gaging its edges between stands to guide it Aft leaving 6 pass; and m m lmng 1t suflio1ently flat 1n the sev- After leaving 7 eraldpasses to permit of controll ng it by side gu1 es.

32:; 13:33; j 352:: 2.111 the method of rolling strip metal in Afterleaving'lqo 10 pass "I backed m1lls, the steps consistingX 1n supplyg a concave piece, passing it t rough suc- It will be noted that the material is substantially flat after each of the passes, there being a slight thinning at the edges but the body portion of the sheet being very flat.

Figure 4 illustrates in chart form the departure from true flatness after the several passes. In this chart the line D 'illustrates the convexity or concavity of the piece after each pass from stand No. 5 on. It will be noted that at stand 5 there is .003"concavity and that from stands 6 to 8, inclusive, there is .004" convexity. At stand!) the convexity has increased to .0065" and then drops off again to .005" in the last pass.

Considering the convexity of the body portion of the sheet, that is to say, disregarding the slight thinning of the edges, and considering only that portion of the sheet lying bea tween the lines L and L of Figure 3 (the lines L and L lying three inches inwardly fromthe edges), the departure of the material from true flatness is illustrated in Figure 4 by the line D. This line shows thatover the main body portion of the sheet the .e is a' I concavity of .002" when the material enters the first four-high stand and that thereafter there isa convexity ranging from .0005" to .0015 This remarkable flatness of the matecessive roll stands, engaging its edges between stands to guide it and maintaimng it sulfic'iently flat in the several passes to permit of controlling its direction by side guides.

3. In the method of rolling strip metal in backed mills, the steps consisting in passing material through successive roll stands, ongaging its edges between stands to guide it,

maintaining it sufficiently flat in the several passes to permit. of controlli guides, and taking a relatively li the final ass.

it by side ght draft in e methodof rolling strip metal in backed mills, the steps consisting m supplying a piece substantially without convexity in cross section, passing t through successive roll stands, engaging its edges between stands to guideit-and maintaining it sufiiciently flat in the several passes to permit of controlling it by side guides.

. 5. 'In the method of rolling strip metal in backed mills, the steps consisting in passing material through successive roll stands, engaging its edges between stands to guide it, maintaining itsufliciently flat in the several passes to engaging it during aportion of the rolling operation in a plurality of stands rial is highly desirable in the finished produc at one time.

and makes 1t possible to control the material by side guides during its passage through the mill.

So far as I am aware my invention is applicable to the rolling 0 thin material of any 1 width. It eliminates necessity for heating furnaces between the stands and beyond the usual amount'of supervision does not reunderstood; that the we ma quire highly skilled employees. Neither does it require the'close calculation of roll contour r uired in other s stems, since the inherent ssiliness of the'bac ed mill makes it possible to use flat rolls in man L passes. It is to be be turned to other than flat profile, depending on the particular conditions encountered, so long as my hand. 1

6. In the method of rolling strip metal, the steps consisting in subjecting a heated piece to reducing and edging passes so as to produce a piece substantially free of convexity in cross section, and rollin it in backed mills.

7. In the method of rolling strip metal, the steps consisting in subjecting a heated piece to reducing and edgingpasses so as to produce a piece substantially freeof convexity in cross (permit of controlling it by side guides an section, rollin it in backed mills; and maintaining the piece sufliciently flat in the several backed mill passes to permit of controllin' it by side guides.

testimony whereof I have hereunto set CHARLES H. ELLIOTT.

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