US1688252A - Plate mill and process of rolling hot metal - Google Patents

Description

Oct. 16, 1928. 1,688,252

J. B. TYTUS PLATE MILL AND PROCESS OF ROLLING HOT METAL I Filed April 11, 1925 ATTO/P/VfVS.

Patented Oct. 16,1928.

UNITED STATES PATENT OFFICE.

JOHIV B. TYTUS, OF MIDDLETOWN, OHIO, ASSIGNOR TO THE AMERICAN ROLLING MILL COMPANY, OF MIDDLETOWN, OHIO, A CORPORATION OF OHIO.

PLATE MILL AND PROCESS OF ROLLING HOT METAL.

Application filed April 11, 1925. Serial No 22,272.

My invention relates to processes for roll ing hot metal and particularly to continuous processes, wherein the metal piece is moved from onestand of rolls to another without being given more than one pass in each stand.

It has been proposed in the past in providing for the rolling of hot metal, in order to get a rapid reduction, to utilize a four high stand of rolls in which the two inner rolls were of small diameter thereby giving a maximum reduction in each pass, while the outer rolls by backing up the two inner rolls serve to reinforce them against excessive springing.

I have found, however, that it is not necessary to utilize a four high stand of rolls, and that by the use of an ordinary two high stand, in which means is provided to support a smaller diameter idle roll between the two main rolls, I am enabled to get a quick reduction and at the same time have a mill which is readily convertible to a two high mill, by removing the small diameter roll.

I have also found that where several mills of the three high type, usin a small diameter idle roll for engaging the piece on one side, are arranged in tandem or so as to operate as a continuous mill, that the fit of the piece when rolling plate for example must be provided for in the several stands.

Thus the stands following the first stand must be so arran ed as to have an active pass which properly ts the shape to which it has been forced by the stand preceding it.

In other words, the first stand due to its central spring, will present an openin through which the metal is forced whic gives it a slight convexity. The second stand must be arranged so that its convexity of opening will be such as to fit as closely as possible the shape of the metal from the first stand, and so on through the succeeding stands in a tandem or continuous train.

One solution of this provision for fit of the piece in successive stands of the type noted, which I have discovered, is to form the rolls of the first stand, and particularly the small diameter roll, in such a way that a comparatively large convexity of openin between the rolls will be presented to the piece. The next stand I arrange to present a convexity of opening somewhat less, and the third stand still less, and so on, the number of stands being limited by the length of the piece which it is practical to handle.

It should be understood that in the rolling mill there are a number of features attendant upon the shape of opening of the rolls, and that the designer and operator will have to take these features into consideration in providing for the graduated con.- vexity of active pass.

It is mfy object, as stated, to provide for rolling 0 hot metal, particularly in plate mills, by means of successive reductions on the piece, each reduction to take place in a different stand, and to arrange for rapid reduction of the piece by providing a small diameter for one of the rolls that engages the piece.

This object I provide by that certain process of rolling, and arrangement of rolling mills to be hereinafter more specifically pointed out and claimed.

In the drawing Figure 1 is a partially diagrammatic view of three stands of rolls arranged in tandem. Figure 2 is a diagram of the progressive active passes of several roll stands.

It should'be understood that in a tandem train of rolls, the piece emerges from the active pass of one stand before it enters the active pass of the next, and that in a continuous train, the piece isengaged by more than one stand at the same time. The latter requires a differential speeding of the several stands, and the former a differential spacin so as to accommodate the increasing lengt of the piece as it emerges from each stand. I find it simpler to arrange the mill for my process as a tandem, although I do not wish to exclude continuous trains.

In the drawing, the first stand of rolls shows a lower driven roll 1, and central idle roll 2 of relatively small diameter, and a backin roll 3, like the first roll, although it may fie of different size, if desired. The roll 3 imparts stiifness against bending to the roll 2, and the screw 4 is employed to re ulate the movement of this upper roll, the ower-roll being preferably fixed in its journals, and the rolls 2 and 3 being permitted upward movement away from the roll 1, as controlled by the screw. This form of screw control is accepted practice, in rolling mills, and needs no particular illustration.

The feed tables between the stands of rolls are indicated at 5 and 6, and the second stand of rolls shows bottom roll 1*, central roll 2*, and top roll 3 while the third stand shows bottom roll 1*, central roll 2 and top roll 3. In the illustration all stands are alike to each other, and due to the differential spacing may be used as a tandem train, each being driven at'the same speed.

The convexities referred to as being arranged in the active pass of the stands of rolls, are so slight to the eye that it is not practical to illustrate them on a small scale drawing, but it Will be understood that roll 2 will have a selected concavity, dependent upon roll spring, roll shape, roll temperature, temperature and kind of piece delivered, and shape and thickness of the piece. The second stand will have a lesser convexity of active pass than the first, and the second will have more than the third. The turning of the rolls preliminary to a rolling operation is thus only one of the factors of the resulting active pass of the rolls, and the operator must control the active pass, working with the instrumentalities involved. Thus in Figure 2 are shown three active passes, A, B and C, the series showing progressively less convexity.

The mill shown is used in rapid reduction, of relatively thin plates or packs, in which the pressure factor and resilience of housing result in the ordinary diameter rolls being ineffective in processes of reduction by individual pass through successive stands.

As the piece enters each stand, it passes between the lower roll and the central roll, thus being positive-1y fed by the lower roll,

and grasped between it and the central roll which has a small diameter and thus effects a rapid reduction of the piece.

Were a four high stand to be used with two idler rolls of small diameter, in a continuous or tandem train, not only would the mill be more cumbersome and costly of upkeep, but it would not be convertible to a two high stand to suit special conditions, nor would it result in the piece passing over a roll which is positively driven. Then again the active pass of a stand where two small diameter rolls are used, with the piece passing between the small rolls, as has been proposed in the past, cannot be controlled as readily as in the three high arrangement which I have described.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. A process of rolling hot metal which consists in passing the metal through successive stands of rolls arranged in line, and in selected stands engaging the metal with a roll of a small diameter to give maximum reduction and a large roll opposed to the small one and positively. driving the large roll, and arranging the active pass of'each stand to enforce progressively less convexity on the piece.

2. A plate mill of the character described, comprising a plurality of stands of rolls, each having a driven, lower, large diameter roll, a central, small diameter idler roll, and a top larger diameter, and screw controlled roll, said stands arranged to act successively on the piece, said rolls being so constructed and operated as to present progressively less con vexity of opening, through which the piece must pass, from the first to the last stand.

JOHN B. TYTUS.

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