US1730044A - Puddling iron - Google Patents

Description

Patented 0a. 1, 1929 UNITED STATES PATENT-1 OFFICE JOHN B. SCHLOSSBERG,OF TERRE lIAUTE, INDIANA, ASSIGNOR TO AMERICAN CHAIN COMPANY, INC., A- CORPORATION OF NEW YORK PUDDLING IRON No Drawing. Application filed April 26,

This invention relates to the manufacture of high grade puddled wrought iron, which is utilized largely in the production of engine bolts, arch-bars, billets, stay bolts and many other important parts of locomotives; also for passenger car equipment, in which safety of passengers is the prime requisite; -and also for many other articles in which the need for repairs can be obviated by such use of puddled iron instead of steel, owing to the tough, ductile properties of the wrought iron, which insure resistance to vibration, shock and fatigue, and also owing to its ability to resist corrosion.

Steel, when nicked to a depth of 15% of" its cross-section, will break in two when subjected to a blow or strain, while wrought iron when similarly nicked will bend fiat upon itself with very little enlargement of the fracture.

Owing to the high cost of producing puddled iron by manual methods, much time and effort has been expended in the effort to produce the same by a more eificient, uniform,

andat the same time cheaper method than by hand, and an important object of the present invention is to provide a mechanical process adapted to do in a practical manner everything desirable now done by hand; also to do so it more uniformly than by hand, by eliminating the greatfatigue to which a puddler is subjected, so that the quality of his product is much lower in theafternoon than in the morning of any days work.

In prior attempts to provide a mechanical puddling process, various non-essential and undesirable practices characteristic of handpuddling were retained, probably on account of the inability to recognize their deleterious effect, and obviate the same, and also on account of a certain reluctance to omit any practice which might have a part in producing the desirably high-grade quality of the puddled iron manufactured manually.

One such unfavorable practice surviving from the manual process has been the melt- 7 ing of pig iron in the rotary mechanical puddling furnaces which it isd'esirable to employ in any mechanical puddling process. V This practice is objectionable because of the waste 1927. Serial No. 186,833.

of time during which the costly rotary puddling furnace is employed in meltin iron, a step which is not an essential part of the puddling operation itself, but which can be obviated by introducing the charge of iron in molten form. The practice is further objectionable by reason of the relatively high heat requiste for melting the pig iron but which is too high for the puddling operation, so that the puddling furnace must be cooled after melting and before puddling, with great loss of time and inequality of product. It is or the pig further objectionable by reason of the depig iron is refined for the first time in thepuddling furnace, and that the defects resulting from a charge of undesirable analysis are usually not identified until they appear in the product, when it is too late to correct them, nor has any reliable method been provided for curing the defects while the iron is being puddled in the rotary furnace, and were such curing expedients available, they would still be open to the objection that each charge would have to be treated separately, a piecemeal method which is wasteful of time and obviously unsatisfactory and impracticable.

Having recognized these objections in the course of extensive operation of rotary me chanical puddling furnaces, it is an important object of the present invention to provide a molten charge of reliable analysis, so that the puddling operation proper may be carried out in a minimum time, at a desirable temperature, and without the need for attention to. refining operations while puddling, thereby assuringmaximum eficiency in the utilization of the costly rotary furnaces, free done from repairs and the production of uniformly high grade puddled iron, with less than average skill on the part of the operator. v cognate object of the present invention is to provide for utilizing in the molten charge ferrous metals of the nature of the scrap at I present emplo ed in the manufacture of alloy steels, which. ave recently come into active competition with wrought iron, by reason of their low cost, although they do not possess the desirable qualities of toughness and freedom from corrosion which characterize pudd-led iron. Such ferrous metal scrap includes steel scrap, cast iron car wheels, stove plate and broken up machinery casts, a varied supply of which can be obtained readily inthe open market.

The steel scrap so obtainable is high and low in phosphorus, and other variations in analysis occur in the other'metals, so that when such sources of supply are used indiscriminately, to avail of the relatively low cost atwhich they may be obtained, it is necessary to provide a novel method of assuring uniformity of analysis in ,the molten metal charge, in order to produce puddled iron which will possess physical properties conforming to such well-known standards as those of the American Railway Association and the American Society for Testing Materials. For example, a wrought iron having a phosphorous content less than .15, will be lacking in tensilestrength, and improper proportions of silicon and manganese will interfere with proper puddling.

In pursuance of an important object of the invention, accordingly, I provide for melting the varied ferrous metal components in a suitable furnace, such as an air furnace, in quantities suflicient to furnish at all times an amount of metal preferably adequate to keep several rotary puddling furnaces supplied, and my novel method provides for dosifying the molten metal with quantities of such elements as phosphorus, silicon, manganese and.

carbon as may be necessary to keep the analysis uniform and assure apuddled iron product having predetermined physical properties. A

In carrying this feature of the invention into effect, samples are taken from the molten metal frequently, and suitable dosesof anyone or more elements which may be found lacking, upon analysis, are added to the melt before drawing charges for transfer to the rotary puddling furnace.

As a further step, to provide for uniformity in the molten stock, when a quantity of the same has been withdrawn for transfer to the puddling furnace, a corresponding quantity 1 the total stock of molten metal, it; is easy-to .of scrap is added to the molten stock in the maintain thedesired analysis by sampling and. dosing frequently as already described. 4 Another object of the'invention is to avoid taining the same in anon-oxidizing environment, and for this purpose I provide the molten bath with a cover of oxygen-occluding material, such as limestone, soda ash or common red brick, the first named material being especially suitable by reason of its cleanness and relatively low cost. 7

The charges of molten metal may be trans ferred to the puddling furnaces by ladlesoperated by cranes, or by suitable conduits or otherwise, and prior to charging the rotary puddling furnaces, a suitable quantity of rollscale will preferably be charged into the puddling furnaces, where it lies at first upon the bottom, and then rises gradually through the molten charge after the latter has been intro-' duced, this by reason of the fact that the specific gravity of the scale is considerably lower'than that of the molten iron' and its tendency is, of course to rise to the top.

The temperature in the rotary furnace may average desirably in the neighborhoodof As soon as the charge is introduced into the rotary furnace, the latter is rotated or oscillated in accordance with the-usual practice in'puddling, and the ball produced is Withdrawn in due time and rolled or squeezed.

4. A desirable reductionin the amount of.

magnesite which has beenintroduced heretofore into the iron as a result of the-high temperature to which the magnesite lining. of rotary furnaces has been subjected when-pig iron was melted in the puddling furnace. The higher the temperature of a magnesite lined furnace, the more rapidly-does theilining disintegrate, and the more -.does the mag,- nesite tend to become incorporated with the iron and to come outwith the balls There is a consequent difiiculty in squeezingthe slag out of the ball.

5; Economy in the cost of production by the use of a' central melting furnace sufficiently large to supply a number ofpuddling';diurnaces continuously, so that the several rotairy puddlin'g furnaces-can be used {to their utmost capacity. j

6. Further economy in the cost'ofproduce tion by reason of (a) the saving of 25% of i V the tune required .for the actual puddling 130 operation, when a molten charge of correct and uniform analysis is supplied to the puddling furnace, as compared with the time required for puddling when pig iron is reiined for the first time in the puddling furnace;

(b) The more continuous operation of a rotary furnace which is possible when it is supplied with successive charges of pro-refined molten metal.

(c) The saving of the cost of many repairsv of rotary puddling furnaces, by obviating the use of relatively high, destructive heats.

(d) The production of uniformly high grade puddled iron, of reliable analysis and physical properties, eliminating the need for many costly rejections of inferior product and also obviating the need for much of the expensive testing heretofore required.

I claim: 7

1. In the process of manufacturing puddled iron, the steps which comprise melting a stock of ferrous metal composed of various grades of scrap, including iron scrap and steel scrap, which may have an undetermined content of phosphorus, silicon, manganese, and carbon; said components being melted in quantities sufiicient to constiable for charging one or more puddling furnaces; adding to said molten stock supplies of saidcomponents corresponding substan-' tially in volume and time of introduction to thewithdrawals therefrom, thereby to insure continuity of production of said molten metalwith respect to analysis, heat "and-volume of stock available for puddling; and charging the stock withdrawn into a puddling furnace or furnaces of the oscillating or rotary type and puddling the same;

2.'In the process of manufacturing'puddled iron, the steps which comprise melting in an air furnace a stock of metal composed of various grades of scrap, including steel scrap and iron scrap in quantities sufficient to constitute a plurality of charges of molten metal for one *or more puddling furnaces; withdrawing from said air furnace from time to time portions of molten stock suitable for charging a plurality of puddling,

furnaces; adding to said air furnace 7 sunplies of said components corresponding substantially in volume and time of introduction to the withdrawals therefrom, thereby to insure continuity of operation of said air furnace; transferring the stock withdrawn to a plurality of puddling furnaces; charging said puddling furnaces with roll-scale and with said portions of molten stock; puddling said charges; and withdrawing and squeezing or rolling the balls respectively produced therein. p

In testimony whereof I have signed this specification.

JOHN B. SCI-ILOSSBERG.