US3360974A - Apparatus for treating metal - Google Patents

Description

Jan. 2, 1968 w. T PURVANCE APPARATUS FOR TREATING METAL 2 Sheets-Sheet 1 Filed April '2, 1965 taut [/Vl/E/VfOR W/LL/AM r PURVANCE y W Af/a rney Jan. 2, 1968 w T. PURVANCE APPARATUS FOR TREATING METAL 2 Sheets-Sheet 2 Filed April 7, 1965 lNVE/VTOR W/LL/AM 7T PURVA/VCE United States Patent 3,360,974 APPARATUS FOR TREATING METAL William T. Purvance, Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation of Delaware Filed Apr. 7, 1965, Ser. No. 446,223 2 Claims. (Cl. 72-,224)

ABSTRACT OF THE DISCLOSURE A rolling mill adapted to perform drastic reduction of metal work of 50% or more in a single pass from ingot and billet sizes which includes a nest of four work rolls having axes at right angles to each other and which form a fully confined pass for the Work. Each roll is motordriven and is supported in its oWn housing and an adjacent housing. The mill also contains removable capping means for each roll which maintain the roll shafts in the mill housing and can be removed for roll replacement.

This invention relates to an apparatus for treating metal. More particularly, the invention relates to a rolling mill especially useful for drastically reducing the cross-section of steel shapes. Of particular benefit, is the use of the apparatus in so-called single pass rolling of closely controlled cross-sectional areas. In such rolling processes, the metal is brought to the desired cross-sectional area in a single pass through the rolling mill. The invention is particularly adaptable to processing continuously cast steel, although it is also useful and adaptable to conventional rolling of shapes in vertical or horizontal rolling mills. In addition, the drastic reduction in cross section which is possible with the invention produces a metallurgical structure in the rolled work unlike that which results from conventional rolling practices. That is to say, the product possesses an elongated grain structure more similar to metallurgical structures of extrusions and forgings than of conventionally rolled material.

In continuous casting of steel, the most common technique is to pour molten metal into a water cooled mold at a closely controlled rate. The shape of the water cooled mold controls the size of the cast steel column. The molten steel at the exterior surface is solidified in the cooling area of the mold and the steel column emerges from the mold, usually in a downward direction. From the mold, the steel column enters a pair of pinch rolls which control the rate of descent. Generally, the pinch rolls contact only two sides of the cast bloom and can only reduce the cross-sectional area to the extent that it is necessary to create enough friction to support the weight of the steel above it. Such rolls cannot be used to substantially reduce the cross-sectional area of the steel because of the unprotected and unsupported areas where the steel would bulge and distort on the sides of the steel column not in contact with the rolls.

The present invention avoids the above disadvantages and others by providing a nest of rolls which support and protect the steel column on all sides. Moreover, the design of the novel rolling mill enables it to withstand severe rolling forces and therefore to perform drastic reductions in cross-sectional areas in a single pass. According to the present invention, an apparatus is provided which employs four rolls disposed at substantially right angles to each other and with abutting roll faces. In the preferred embodiment, each of the rolls have tapered edges beveled at 45 and are arranged so that adjacent beveled faces abut each other. Each of the rollers are supported by a shaft extending from each end of the roll which in turn rests in and is supported by individual mill housings in a manner to be hereinafter described. The novel design of the mill also permits the rolls to be quickly and easily changed, as needed, with minimum shut-down time.

The use of the invention in conjunction with continuous casting permits a large cross-sectional area to be cast in the casting mold, e.g., 24 x 24", and due to the rigidity and strength of the rolling mill as well as its novel design, such large cast shapes may be drastically reduced in a single pass of the metal through it to, for example, a 12" x 12" billet. Because of this ability, two mills of my design, one as a following mill located beneath the first mill, can be used to effectively reduce in a single pass a large cast ingot of, for example 24" x 24", to a billet as small as 4 x 4". One of the handicaps of continuous casting process lines has been the limitation on the continuous casting rate brought about by the limited rate of descent of the steel through the casting mold; thus, for example, if only small billets, i.e., 4" x 4", can be cast, a limited production is obtained. This is due of course to the fact that metal cannot be withdrawn from the mold any faster than solidification takes place. However, by use of the invention, billets of the same size, i.e., 4" x 4", could be produced at a rate 36 times faster than the casting rate of the 24 x 24" steel column. Moreover, my rolling mill, besides performing the function of pinch rolls to control the rate of descent and substantial reduction in the size of the cast steel column, also has the effect of equally distributing the heat throughout the cross-sectional area of the bloom and thereby provides a forged or extruded grain type product which is presently obtained only by costly processing.

Other advantages and features of the invention will become apparent in the following description taken in conjunction with the drawings which illustrate various embodiments of the invention.

In the drawings:

FIGURE 1 is a plan view in horizontal section through the bearings showing an assembly of a nest of rolls in accordance with the invention;

FIGURE 2 is a sectional view taken along the line IIII of FIGURE 1 showing the arrangement of mill housings and rolls;

FIGURE 3 is a sectional view taken along lines III- III of FIGURE 1 showing the arrangement of the housing, roll shafts and bearing inserts;

FIGURE 4 is a schematic view of a typical rolling mill in accordance with the invention illustrating how it may be used in continuous casting processes; and

FIGURE 5 is a schematic view showing how the invention can be readily adapted to permit rolling of various shapes.

As shown in FIGURE 1, four rolls 13a, 13b, 13c and 13d are arranged to form a nest of rolls with the axes of the rolls at substantially right angles to each other and with abutting roll surfaces forming a fully closed pass for the Work 11. Each of the rolls has a primary shaft 15a, 15b, 15c and 15d and a secondary shaft 17a, 17b. 17c and 17d extending from opposite sides of the rolls 13a, 13b, 13c and 13d respectively. Associated with each roll is a mill housing 19a, 19b, 19c and 19d which supports the primary shaft of that roll. Thus, mill housing 19a supports the primary shaft 15a of roll 13a; similarly. mill housing 1% supports the primary shaft 15b of roll 1317, etc. Within each mill housing is a recess 21a, 21b, 21c and 21d which receives the secondary shaft of an ad jacent roll. Thus, for example, mill housing 19a receives in the reccess 21:: the secondary shaft 17d of roll 13a while mill housing 19b receives at 21b the secondary shaft 17a of roll 13a. The secondary shaft 17b is fitted into the recess 210 of mill housing 190 associated with roll 130. Secondary shaft is received by the recess 21d of mill housing 1%. The primary shafts 15a, 15b, 15c and 15d of each of the rolls are preferably independently driven and are equipped with independent but synchronized motor drives.

Suitable capping means 25 (best shown in FIGURES 2 and 3) maintain the roll shafts in the mill housings. The capping means 25 may be a single large cast section; however, in the preferred embodiment comprises a top 27 and inserts 29 which extend into the mill housings to hold the roll shafts in position. The use of separate capping means in this manner permits the rolls to be changed easily by use of an overhead crane which removes the cap and inserts from the mill housing after which the rolls can be removed from the housings and new rolls positioned to replace them. The mill housings 19a, 19b, 19c and 19d may be mounted on conventional housing shoes 18 to which they are attached, as by cap screws 16. In this way, the mill housings are held rigidly in place at the bottom. It will be observed that with the above described design the mill housings are not subjected to any cross strains since all rolling forces are directed in the same manner against housings.

Upon metallurgical examination of a drastically reduced product produced from this rolling mill, the prodnot will be found to have a greatly elongated grain structure. Moreover, the product will have a greater hardness than conventionally rolled material.

The configuration of the working surface of the rolls 13a, 13b, 13c and 13d is made to conform to the desired cross-sectional area of the final product. In the embodiment shown in FIGURE 1, the faces of the rolls are machined to provide a square product. This is accomplished as shown by using rolls with beveled edges 20 having a 45 taper at the edges of the rolls. When the rolls are arranged as shown with adjacent edges abutting, a fully closed pass for the work is provided. Furthermore, lateral movement of each roll is precluded by the support provided by adjacent rolls. The roll shafts a, 15b, 15c and 15d, which are supported on bearings 23a, 23b, 23c and 23d, are individually connected with conventional motor drives and couplings to provide the force necessary for the drastic reduction of steel shapes. The bearings, which may be of the friction or anti-friction type allow free rolling of the rolls. However, because of the friction that results from the closely machined tapered faces of each of the rolls and the force of the crosssectional area during rolling, it is possible to drive the mill with a single drive. The nest of rolls which are arranged to provide a fully closed pass for the work form a funnel into which hot steel can be inserted and which emerges at the exit side of the mill with the exact circumference and configuration of the work roll faces.

It should be noted that the rolling mill of the invention can be easily adapted to a continuous casting line. As an example, two nests of rolls, 30 and 40, which are of the design described in FIGURES 1, 2 and 3, may be positioned as shown in FIGURE 4 to receive a hot poured ingot from mold 35. The primary mill reduces the cross-sectional area of the cast steel column 37. The steel of reduced section 39 leaving primary mill 30 can be passed into a following mill 40 where it emerges with a still smaller cross-sectional area. Obviously, additional mills can be provided to accomplish further reduction as desired or a single mill may be used if less reduction is needed.

In addition to use in a continuous casting line, the invention may be employed as horizontal rolling mills for blooms, bars, billets or other shapes. This is accomplished in the same manner as heretofore described except that the mill is built for a vertical pass. By altering the working face of the rolls, as shown in FIGURE 5, squares, rounds, hexagons or other shapes can be produced. Through the use of successive mills of this design, i.e., following mills, very great reductions of the original work may be performed. By using work rolls with closely machined edges beveled at and driving the four rolls so they rotate to the center at the same speed, friction is minimized. All four rolls may be synchronized in speed through mechanical linkages or electrical circuitry.

I claim:

1. A rolling mill adapted to perform drastic reduction of metal work of or more in a single pass from ingot and billet sizes such as to produce an elongated grain structure characteristic of extrusions, said mill comprising a nest of four work rolls arranged with their axes at substantially right angles to each other and with abutting roll surfaces forming a fully confined pass for the work, a motor and drive for each work roll, a primary and a secondary shaft extending from opposite sides of each of said work rolls, a mill housing for each work roll supporting the primary shaft of that roll, means within each mill housing a support secondary shaft of an adjacent work roll, and removable capping means associated with each roll for maintaining the roll shafts in the mill housings and which when removed permit replacement of the rolls in the housings.

2. A rolling mill according to claim 1 in which the edges of the rolls are beveled at 45 and the rolls are positioned with abutting beveled surfaces such that together the rolls form a fully confined pass for the work.

References Cited UNITED STATES PATENTS 281,978 7/1883 Crandell 72224 1,788,693 1/1931 Stiiting 72224 1,994,187 3/1935 Bennington 72-224 CHARLES W. LANHAM, Primary Examiner.

H. D. HOINKES, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,360,974 January 2, 1968 William T. Purvance that error appears in the above numbered pat- It is hereby certified d that the said Letters Patent should read as ent requiring correction an corrected below.

Column 1, line 69, for "rollers" read rolls column 2, line 66, for "13a" read 13d Signed and sealed this 4th day of February 1969.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, 11'.

Attesting Officer

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