US1973425A - Rolling mill housing and method of constructing the same - Google Patents

Description

F. c. B|GGERT. JR 1,973,425 ROLLING MID L HOUSING- AND METHOD OF CONSTRUCTING THE SAME Filed Jan. 13 1933 2 Sheets-$heet 1 1934- F. c. BIGGERT, JR 25 ROLLING MILL HOUSING AND METHOD OF CONSTRUCTJING THE SAME 1 Filed Jan. 13, 1935 Z'Sheets-Sheet 2 .14 v "uo WITNESSES INVENTOR Patented Sept. 11, 1934 NITED STA ROLLING MILL HOUSING AND METHOD OF CONSTRUCTING THE SAME Florence C. Biggert,..lr., United Engineering & burgh, Pa.,

Grafton, Pa., assignor to Foundry Company, Piu a corporation of Pennsylvania Application January 13, 1933, Serial No. 651,52

Claims. "(01. 29-448) This invention relates to rolling mills, and more particularly to a roll homing construction and method of constructing the same for such mills,

and especially mills of relatively large sizes.

With the advances which have been made in the art of metal rolling in the past couple of decades, and particularly in the rolling of relatively thin sheets and plates, mills of continually increasing sizes have been developedior rolling sheets and. plates of corresponingly increasing widths. With the development of these larger sized mills, the problems involved-in their construction have become more and more complex. among these problems, one of the most diilicult is that or eliminating what is known as stretching in the rolihousings. This stretching is-produced by the forces exerted upon these housings by the passing of the metal through the mill rolls, and is due tothe elasticty or the metal out of which the housings are cast. The deleterious efiect of this stretching is that it results in the production of sheets of varying thickness or, in other words, in inaccurate rolling, and frequently is the cause of sheets being rolled having insuilicient uniformity of thickness to come within the tolerence normally permitted. In addition, thisstretching frequently dei'orms these housings to such an extent as to cause them to subject the bearing blocks of the rolls, as well as the rolls themelves, to such strains as to cause their failure.

To minimize this stretching of the housings-the usual practice is to increase thearea. or cross seci i i tion of the housings to such an extent that they are capable of maintaining the stretching within tolerable limits. Such practice, however, in mills of exceedinglylarge sizes, for instance, mills capable of rolling sheets in widths of 84 inches and wider, gives rise to an exceedingly difficult problem of construction, as it necessitates these housings having such tremendous sizes that it is almost impossible to cast them in a feasible way. This latter problem will be more fully appreciated when it is considered that the castings for such housings run into weights varying from 250,000 to 400,000 pounds. 1 I

It is an object of this invention to overcome these difiiculties through the provision of a multiple part assembled housing which in addition tominimizing the aforementioned construction diificulties provides for a more eflficient utilization of the metal employed in such a, way that the stretching action produced by the rolling forces is materially reduced for a given size of housing section. H

These and other objects, as well as the various other novel features and advantages of the invention, become apparent when the following detailed description is read in conjunction with the accompanying drawings, of which Fig. 1 is an end view of a rolling mill showing a roll housing embodying the invention, the roll and screw-down assembly thereof being shown in dotted lines; Fig. 2 a. side elevational view of the inner housing section ar -link; Fig. 3 a similar view of the outer housingsection shown in Fig. 1 before the two are assembled, the latter section being shown in full lines as cast when cool, and in dotted lines (slightly exaggerated) as expanded for assembly; Fig. 4 a schematic force diagram of a mill housing comprising a single casting; andFig. 5 a similar illustration of a mill housing constructed accordingtoFig. 1., l I

v Referring indetail to the drawings, the roll housing therein illustrated comprises an oblong link-like section-1, and link section 2, which latter, is rigidly fitted in the opening of the outer section. Ine'ach milltwo of these built-up housings are employed, be-' ing Joined together at their upper ends by upper cross beams not shown and at their lower ends by lower cross beams 4.. For rigidity of construction, these lower cross beams are reinforced by a plurality of spaced tie plates 5. In the latter plates the. base portions of the cross beams 4, which, in the present instance, are made in the form of an inverted'T; are fitted, being seated in grooves 6 cut in the-plates, and held against move- 1 ment therein, as well as against the sides of the housing by wedges 7, which are forced between the outer "edges of the tie plates and a tapered shoulder 8 forming the outer edge of the grooves 6.

For receiving the usual roll assembly, which is designated generallyby the numeral 9, the inner section 2 of the housing is provided with windowforming openings 10, and for adjusting the rolls of this assembly the usual screw-down assembly 11 is mounted on the top of the housing in the customary fashion to operate the adjusting screws 12. Inasmuch as these latter parts constitute no part of the present invention, they are, for clarity, illustrated in the drawings in dotted lines and referred to here only in a general way.

According to this invention, in order to em- .ciently utilize the metal comprising the side walls a somewhat similar inner 75 ties, a housing having substantially twice the size of that which may be produced if the ing were to be cast in a single piece. In casting these parts the outer link is provided with an oblong inner opening 14 which is rounded at its two ends on the radius of a circle andthe sides of this opening, which are parallel, are made tangent to the circumference of the end circles. The inner link, in turn, is provided with an outer contour or peripheral surface which is similar to the opening 14 of. the outer link except that it is slightly longer at normal temperatures.

The difference in lengths between the exterior of the inner link and the interior of the outer link is such that the outer link may, when expanded 1 by heating it sufficiently, be placed on the inner tion as mentioned hereinbefore are link and shrunk tightly thereover, which is done when the two sections are'essembled. When so assembled, which may be accomplished with relative ease, the two'parts are firmly bound together and provide a strong and rigid structure. To improve the union between the two their contacting surfaces are machined as accurately as is possible before the two are assembled.

Like the outer link, the inner link is provided with an opening 10 which constitutes the window within which the roll assembly is mounted. This opening, however, is dissimilar from the opening 14 in that it is made substantially rectangular in shape so that its end portions are provided with semicircular arches which increase the strength.

of the houslngs'and adapt them to rigidly withstand the forces exerted upon them when a piece of'metal is passed between the rolls, or in other words, minimize the amount of bending which such forces tend to produce.

The chief advantages flowing from this'inventhat it makes 1 it possible to produce with equal casting difllculbetter castings, for, as is well known,

ties a roll housing having substantially twice the size of an integrally cast housing. In addition to this, by reason of the more enlclent utilization of the metal in the castings, smaller castings may be used for a given sized mill which makes for the gas pockets, blowholes, internal strains and such other imperfections which are encountered in the making of castings, are of less consequence the smaller the cross section of the castings, and these in tremendously large castings become of real importance.

In addition to the above-mentioned manufacturing advantages of the invention, a roll housing constructed in accordance herewith has the further advantage that it is capable of withstanding greater stretching forces with a lesser amount of stretching at the housing window and deflection of the housing side walls, than is produced in housings which are made in a single solid piece. This is attributed principally to two factors, first, the fact that the planes of contact between the housing sections at the sides of the housing are such that they permit a slip to occur between the inner and outer links when subjected to endwise stresses, which, in view of such stress in a mill being applied at the center of the mill, adapts the outer link to carry a greater portion of the stretchresisting load than is the case of a unitary structure. The other factor which contributes to the above result is the fact that the outer link is shrunk upon the inner link, thereby causing the inner one to be initially subjected to compression and the outer link to tension, which aids in effecting the above-mentioned distribution of stresses.

By way of illustrating this point, reference will whole housthough in different degree, but the initial compression of the inner-housing compensates for this inequality so as to more nearly approach the conditions of a member in pure tension.. In this latter form of housing the stretching will be actually in substantially the ratio shown by the lines 21a and 22ainFig.'5.

In accordance with the invention, as illustrated diagrammatically in Fig. 5, due to the housing being in two parts and having sliding vertical surfaces therebetween, the force distributions resulting from the rolling forcesimposed on the housing do not follow the same distribution as in a housing which is cast in a single section, as indicated in Fig. 4. As shown, by reason of the links 1 and 2 having circular contacting surfaces at their two ends, the rolling forces are transradial lines substantially perpendicular to the periphery of such end surfaces, and by reason of the vertical contacting surfaces of the two links lying in vertical planes, relativev movement between them is permitted, causing the outer link to be subjected to a substantially uniform tenslonal strain over its length inasmuch as when stretched it slides with respect to the inner link. Consequently, the outer link is more effectively utilized to withstand the stretching stresses exerted upon the housing than is that portion of a unitary housing. Hence, while the total amount of stretching taking place in the housing may be the same as that which takes place in a housing of similar size cast in one section for a given stress, the average amount of stretching, and particularly the amount of stretching at the window opening in the housing, is materially reduced as well as the deflection of the side portion of the housing. The chief advantages of this feature are that the stretching which interferes with the rolling operation of the mill is minimized, and accordingly for a given size of housing a lesser amount of material may be used in making a casting to comply with a given stretching tolerance.

According to the provisions of the patent statutes, I have explained the principle and mode of operation of my invention, and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. The method of making a roll housing for a metal rolling mill comprising forming an outer housing section having an opening in the center thereof, forming an inner housing section having a peripheral contour of the same shape but diagnosis of the conditions obtaining in a roll housing when rolling is taking been illustratedin various produced in integrally cast in-the proportions Edi initial compression in the inner section.

3. The method of making a roll housing for a metal rolling mill comprising forming an outer housing section with an opening in the center thereof, the ends of which have the curvature of a. circle and the sides of which are paralled to each other and extend tangential to the curvature of the ends, forming an inner housing section with an outer peripheral contour similar to but slightly larger than the opening in the outer section, and heating and shrinking said outer section upon the inner section.

1,978,425 slightly larger than the opening in the outer see- 4. A roll housing for a metal rolling mill'coim prising an outer'section having an oblong opening in its center, and an inner section provided with a bearing window in its interior and a peripheral contour corresrionding to the openingin said outer section with said outer section shrunk upon the inner section in a manner to form a substantially unitary structure.

5. A roll housing for a metal rolling mill comprising a pair 01' link-like cast sections mounted with one shrunk upon the other, the inner of said sections having a roll window inits center and an exterior surface which is parallel at the sides and round at the ends, and the outer section having an opening in its center which is similar in shape but slightly shorter under normal'conditions than the exterior of the inner link whereby the inner link is subjected to compression and the outer link to tension when assembled.

FLORENCE C. BIQGERT, Jr.

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