US1908267A - Method of working metal - Google Patents

Description

May 9, 1933. w. c. M BAIN 5 I METHOD OF WORKING METAL Filed June 13, 1928 Inventor Patented May 9, 1933 OFFICE wmnrm o. mum, on Yoones'roww, OHIO mnon WORKING METAL Application filed June 18,

The present invention relates to the art of metal workin being especially applicable to the rolling 0 stri steel or flat wire of llOIl or steel or their a oys, and the forming of sheets and other strips by the use of rolls or forming dies. It consists essentially in working metal by compression while such metal 1s under a considerable tension transversely of the compressive forces. It further consists of the use of compressive forces considerably less than those used in present practice.

One object of the present invention is to enable a greater elongation in at least one d1- mension to be had without further heat treatment of the metals bein worked and without danger of injury to or ailure of such metals.

A further object of this invention is to make ossible the use of rolls made of harder, and tlihrefore usually more brittle, material than in present practice, by which a superior finish may be given to t e material being worked.

Another ob'ectis to reduce the necessary pressure on t e rolls or revolving dies by which the surface of such rolls or dies is preserved and wear and tear on the bearings is reduced.

Another object of'the invention is the reduction of distortion in strip or flat wire being rolled, such as ruflled ed es, which are due to roll bending. or .over eatingof the rolls nearthe roll necks. Further objects of the present invention are the production of superior products at a less cost than heretofore, the superior polishing produced on the finished product and such other objects as will appear from the disclosure and claims.

In order to enable others to more clearly understand the invention I have illustrated one embodiment thereof in the accompanying drawing which shows certain means by which my invention may be practiced. I do not,-

however, intend to limit my invention to the specific means shown, as many other means may be used by those skilled in thart in the practice of my invention.

Figure 1 is a cross section of a rollin mill in which my invention may be ractice To enable others skille in 'e art to pracit F exceeds e elastic limit 0 the work, while 1928. Serial No. 285,093.

tice this invention I will give a detailedficcount of the several essential parts of the ap aratus illustrated. Y

n the rolling mill in Figure 1, 10 and 11 I are the usual rolls, which may, however, be of smaller cross sectional area and of greater hardness in practicin m invention than is the usual practice. 01 10 is pressed toward roll 11 by a bearing 12 whlch is compressed by screw 13 which bears upon a m breaking block 14 resting upon the bearing 12. 15 is a bar or strip of metal being worked between the rolls. It is fastened at either endv to tension devices which may, as illustrated, comprise flexible members 16 running over pulleys or sheaves 17 and vertically sustaining weights 18 from their depending ends.

In the ractice of the invention as illustrated in igure 1 the weights 18 are sufii- Q cient to put a tensile stress upon the bar or strip 15 being worked, approaching or in some cases even exceeding lts elastic limit.

The block 14,in some cases, is designed to break if the compression screw 13 is trans- 7 mitting a. compressive force through the bearing 12 and rolls 10 and 11 upon the work 15 exceedini per cent of the elastic limit of such wor The work may be advanced between the rolls by positively driving the rolls or by allowin the rolls to idle and placing a greater tensi e stress upon one side of the rolls than the other.

In the former practice it has been customary to place compressive force upon mate- 1 rial being worked which approached or exceeded the elastic limit of the material at the point of contact under ,the conditions at which it was worked. This was deemed necessary in order to obtain the lengthening of such strip desired. Themetal was made to flow by the force of such compression. It has been the practice in certain mills to "place a small tensile stress upon the work to prevent kinking and to assist in a slight lengthening efi'ect of the rolling. In the present invention, however, the reverse relation of forces holds. The tensile stress placed the work ap roaches or even 10 the compressive forces, contrary to all precedent, are less than 90 per cent of the elastic found it possible to obtain such elongation when the compressive force was a very small fraction of the elastic limit of such work. In practice I prefer to have such compressive force from 10 to 50 per cent of the elastic limit of the work and to have the tensile force approach or even exceed the elastic limit of the work.

In order to clearly understand the radical departure of the preseht invention from the usual practice it is only necessary to consider mathematically the relation of forces concerned in the rolling of strips. If the original thickness of a strip is T and the thickness after passing between rolls is T then T T is the total reduction of the pass and (T T is the amount of reduction on either the upper or lower half of the work. Then if the are a of contact of one roll with the work is small compared to the diameterv D of the roll then neglecting negligible errors Therefore Let B be the breadth of the work then the area of contact A of work and roll is If E is the elastic limit of a standard test specimen in compression then according to the former knowledge of those skilled in the art the necessary total roll pressure must approach or exceed B /2 1) (IT 11.

before the rolling is effective.

I have found, however, that by the use of a tension upon the work, approaching or exceeding the elastic limit of the work, the necessary roll pressures may be reduced to from 90 per cent of the above almost to zero. I

refer to use 15 per cent to 50 per cent of what lies been considered the lower limit of edective pressures.

In the diagram it will be noted that the wei hts are adjustable. A suitable number of t em may be removed after each pass so as to suit the tension to the strength of the strip. In some cases, it is more desirable to have a stronger pull on the strip on one side a endas? v the Weights on the entering side may be all removed and thusthe tension be reduced tozero or else regulated to 'ust enough tohold the strip in position. 1%, however, the tension in the strip on the leaving side of the mill be held up to the neighborhood of the elastic limit, the method still falls within the scope of my claims since there is a zone in the strip between the last points of contact with the rolls, in which the strip is in tension up to the neighborhood of the elastic limit and at the same time is under a very low compression. The back tension in this case is caused by large reductions in which the shoulder of the strip as it is being reduced in the mill, presses against the rolls so as to cause a very appreciable horizontal force component.

It is to be understood that this rolling may be done at any temperature and is not specifically limited to iron-containing metals. It has awide application in the making of highly polished watch springs, sheet metal, iron and steel alloy strips, razor blades, etc. In practice oil may or may not, as desired, be placed upon the rolls, but if used will be of peculiar advantage, due to the fact that the compressive force is so small thatthe oil will lower the frictional resistances and it will be possible to maintain a high polish upon the rolls and the strip or sheet worked. The rolls may be constructed of material which may be much harder than is possible at present, as the smaller pressures obviate the danger of breaking the more brittle hard rolls; or on the other extreme, the rolls may be of mate rial softer than thestrip being worked, as the pressures used are considerably under the elastic limits of the materials worked. This latter is of very peculiar importance in the rolling of strips and sheets of a very hard material.

I do not wish to be limited to the form illustrated. and to the method described except as defined by the appended claims.

I claim:

1. In a method of rolling metal, the steps consisting in drawing it between rolls and applied to the trailing end thereof a tension approaching the elastic limit, said rolls being driven solely by the tension in the strip.

2. In a method of working metal, the steps lll stepsincluding pulling a strip between rolls driven by a tension in the strip, applying a forward tension to the strip leaving the rolls 4 approaching the elastic limit, subjectin the rolls to a pressure less than the elastic llmit, and subjecting the strip entering the rolls to a restraining tension.

4. In a method of working metal, the steps including drawing a strip between rolls V driven solely by the tension in the strip, and applying tensions approaching the elastic limit to the strip entering the rolls and the strip leaving the rolls.

5. In a method of working metal strip, the

steps-including drawing the strip between rolls driven solely by the tension in the strip, applying tensions approaching the elastic limit to the strip, and exerting a comparatively low pressure on the rolls.

6. In a method of rolling metal strip, the steps including pulling the strip between rolls driven solely by the tension in the strip, continuously advancing the strip while maintaining the trailing end thereof under a tensile force approaching the elastic limit to reduce the compressive force exerted by the rolls.

including drawing the strip between rolls driven by the tension in the strip, applying a tensile force in the neighborhood of the elastic limit to the strip, and applying a compressive force at right angles to the tensile force intermediate the ends of the strip, said compressive force being materially below the elastic limit.

8. In the art of rollin metal, the steps includin 'pulling a strip etween rolls driven solely y the tension of the strip, subjecting the strip longitudinally to tension in the neighborhood of the elastic limit, and laterally to a slight compression only.

9. In a method of rolling ferrous metal strip, the steps including drawing it between rolls driven solely by the tension of the' strip, tensioning the stri substantially to the elastic limit, and light y compressing it between the rolls.

10. In a method of cold rolling ferrous strip, the steps including drawing it between rolls driven solel by the tension in the strip and applying a igh restraining tension to the trailing end of the strip.

In testimony whereof I atfix m signature.

WILLIAM C. OBAIN.

7. In amethod of working metal, the steps

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