US2330469A - Method of cold-rolling steel strip or sheet - Google Patents

Description

Sept. 28, 1943. v. BYUS ET AL METHOD OF COLD-ROLLING STEEL STRIP OR SHEET Filed May 2 1940 lfiveidarsx a 4 M i r. 50% EL E w Patented Sept. 28, 1943 I UNITED ROLLING STEEL STRIP R SHEET Vere Byus and Earl D. Spangler, Gary, Ind. Application May 2, 1940, Serial No. 333,030

METHOD or c01 1)- 4 Claims. This invention relates to cold-rolling steel strip or sheets, and more particularly to that form of rolling which is known in the art as temper-rolling."

At the present time it is widely conventional to obtain 16mg lengths of steel strip or sheets by hot-rolling and subsequent cold-rolling operations. That form of cold-rolling which is employed in the art to obtain the desired :gage or thickness of the steel strip or sheet'is more properly referred to as cold-reducing." There has recently been developed a method which or gage, is known as tempering" or temperrolling-and is used to superficially harden, or increase the surface hardness of, the steel strip or sheet whereby it is sufllciently stiffened to eliminate buckling, fluting, creasing, and other objectionable features which result during subsequent forming operations to which the strip steel is subjected. It naturally follows that, the superficial hardening, or surface hardening, of the In cold-reduction, as distinguished from temper-rolling, the magnitude of the coldworking phenomena is such as to render the steel strip or sheet extremely stiff and brittle; and it is the usual practice to resort to intermediate annealing steps in order to render the material more ductile.

After the conventional cold-reducing operationsrthe steelstrip or sheet delivered to the "temper-mill" in an annealed condition and with an average hardness of 35 to 55 Rockwell B; and in order to increase this to approximately may broadly be termed cold-rolling, although steel strip or sheet results in a flatter or smooth-- 7 er surface: and it may be stated that itnecessarily follows that a surface which is flatter and smoother accrues from a reduction in gage, although. this reduction be extremely minute. It is therefore generally understood in the art that "tempering or temper-rolling does not truly effect a reduction in gage, although it is realized that an imperceptible, or extremely minute, reduction 'is necessarily had. As distinguished from tempering or temper-rolling, cold-rolling of such magnitude as to constitute cold-reduction effects reductions in gage which are of considerable magnitude, such as well over 50 per cent, in most cases.

It is true that both forms of cold-rolling (temper-rolling and cold-reducing) usually employ 4-high mills comprising backing-up rolls and considerably smaller intermediately disposed metal-working rolls through which the steel strip or sheet is directed. Here, however, the similarity ceases as mills employed for cold-reduction" purposes are of extremely rugged construction and capable of very high screw-down" pressures; whereas the minute or practically imperceptible reduction effected by temper-rolling" mills does not require a unit of such rugged construction. Therefore temper-rolling" is usually performed on much lighter mills.

-metals, such as by tinning.

'70 Rockwell B by subjecting it to a conventional temper-rolling" process, it has been necessary to resort to a number of passages of the workpiece through the mill such as materially raise the cost of production. In order to reduce the cost of production and lessen the number of passes required, several 4-high mills of the type referred to hereinbefore have been disposed in tandem relationship and each operated in the manner referred to hereinbefore as constituting conventional temper-rolling." This has resulted in the reduction of the number of passes to a certain extent, but not to such a degree as to justify the expenditure involved-or increase the efliciency of the process to the extent desired.

In conventional temper-rolling the strip or sheet is elongated anywhere from approximately 1 per cent to approximately 10 per cent, depending upon the number of passesrequired to obtain the desired hardness. Temper-rolling" may be accomplished in a decreasing number of passes by increasing the screw-down pressure or by using lubricating oils on the strip, but these expedients have the following disadvantages:

a. Increasing screw-down pressure involves greater current consumption in the driving of such mills; and deflects the shape of the working rolls, thus leading to distorted shape of the pass and irregular or uneven working of both surfaces of the annealed strip being rolled. The distortion or deflection of the rolls by excessive screw- -down pressure results in spalling and cracking of the working surfaces of the rolls and leads to their early destruction.

b. The use of lubricating oils on the strip. necessitates its complete removal in a subsequent or separate operation to prevent dimculties in' coating the surface of the thus treated It is among, the objects of the present invention to provide a novel method of cold-rolling steel strip or sheets in the manner specifically designated in the art as temper-rolling," which accomplishes in a single pass through a conventional "temper-mill" any desired degree of superficial hardening or surface hardening of the annealed material.

Another object is the provision of a method of the class described which results in the even elongation of the strip or sheet.

Still another object is the uniform working of both surfaces of the material.

A further object is the elimination of "pinching" of the material during the rolling operation.

The foregoing and other objects will beapparent after referring to the drawing, in which:

Figure 1 is an end elevation, partly in section, of'apparatus which may be used to practice the method of the present invention;

Figure 2 is a side elevation of part of the apparatus of Figure 1; and

Figure3 is an enlarged sectional view of that part of the apparatus which is shown in Figure 2 Referring more particularly to the drawing, the numeral 2 designates the housing of a conventional 4-high cold-rolling temper-rolling mill employing the usual large-diameter backing-up rolls 3 which bear against a series of intermediately disposed smaller diameter metal-working rolls 6. On one side of the housing 2 there is disposed a conventional uncoiling device, generally designated at 6, while on the other side of the said housing there is disposed a conventional coiling. device,.generally designated 'at 7. Accordingly, the strip to be temper-rolled, and designated hereinafter at 3, is led away from the uncoiling device, generally designated at 6, threaded between the metal-working rolls 5 and connected to, and coiled upon, the conventional coiling device, generally designated at I. The screw-down pressure applied to the backing-up rolls 3,and accordingly thatwhich is transmitted to the maller intermediately disposed metal-working rolls 4, is of a smaller magnitude and one which would ordinarily require several passages of the strip S through the mill in order to obtain the desired superficial or surface hardening.

According to the teachings of the present invention there is disposed adjacent to, and on the entry side of, the metal-working rolls 4 a cylindrical header 9 which extends above the line of pass and in parallelism with the upper metalworking roll. This cylindrical header 9 is equipped with a series of vertically depending pipes ii, each of which terminates in a T-connection l3. To each opening of each of the T-connections i3 there is connected a short horizontally extending tube l5 which terminates in a downwardly directed fiat spray l6.

Connected to the cylindrical header 9 is a feed pipe i8 through which a liquid medium is supplied for. a purpose which will-be later described.

Immediately below the strip 8 and occupying a position opposite the header 9 is a corresponding device and associated instrumentalities which are designated by corresponding numerals to which there is affixed the character (prime).

According to the teachings of the invention, steam is introduced through the feed pipes i8 and I8 through the series of flat spray nozzles i6 onto the upper and lower surfaces of the strip S ismmediately prior to its entrance between the metal-working rolls 4. It is essential that the steam be supplied in the form of a continuous bath or film across the entire width, and on both sides, of the strip S.

According to a modification, a super-saturated mixture of steam and condensate at temperatures corresponding closely to the temperature of the steam may be fed through the flat spray nozzles IS in the form of a continuous bath or film across the entire width, and on both sides, of the strip S.

According to another modification, hot, or even warm, water may be supplied through the feed pipes i8 and i8 and accordingly through the nozzles IS, in lieu of the steam, or super-saturated mixture of team and condensate referred to hereinbefore.

While we have shown and described several specific embodiments of the present invention it will be seen that we do not wish to be limited exactly thereto, since various modifications may be made without departing fromthe scope of the invention, as defined by the following claims.

We claim:

1'. The method of temper rolling a fiat metal workpiece in a cold rolling mill, which comprises flowing a continuous bath of liquid water at elevated temperatures across the full width of the said workpiece immediately prior to its entry into the metal working temper rolls.

2. The method of temper-rolling'a fiat metal workpiece in a cold-rolling mill which includes flowing a continuous bath of water at elevated temperatures across the full width of said workpiece immediately prior to its entry into the metal-working temper rolls.

3. The method of temper-rolling a flat metal workpiece in a cold-rolling mill which includes fiowing a continuous bath of steam across the full width of said workpiece immediately prior to its entry into the metal-working temper rolls.

4. The method of temper-rolling a fiat metal workpiece in a cold-rolling mill which includes flowing a continuous bath of super-saturated mixture of steam and condensate across the full width of said workpiece immediately prior to its entry into the metal-working temper rolls.

EARL D. SPANGLER. VERE BYUS.

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