US1073735A - Method of making sound castings. - Google Patents

Description

I. D. OARNBY 6: L. B. LINDBMUTH.

METHOD OF MAKING SOUND OASTIHGB.

APPLIOATIOH FILED JD!!! 12, 1913.

Patented Sept. 23, 1913.

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FBAHK D. CABNEY AND LEWIS B. I'IINDEM'UTH, OF STEELTON, ZPENNSYLVANIA.

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Specification of Letters Patent.

Application filed June 12; 1918. Serial No. 778,291.

To all whom it may-concern Be it known that we, FRANK D. CARNEY and Lswrs B. LINDEMUTH, both citizens of the United States of America, and residents of Steelton, Dauphin county, Pennsylvania, have invented certain new and usefullmprovements in Methods of Making Sound Gastings; and we do hereby declare the following to bea full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference beinghad to the accompanying drawings, and to letters or, figures of reference marked thereon, which form a part of this specification.

Thisinven'tion relates to the method of making sound castings, and more-especially to the making of sound castings containing large volumes of metal, such as ingots and the like, theobject beingto reduce or eliminate the pipe, and reducethe quantity of metal in. the crop ends, thereby saving much valuable metal from being scrapped.

Hereinafter w'eshall refer to the ingot, as a type of casting containing a large volume of metal, but wish it understood that the operations hereinafter described are equally applicable to other shapes and types of large castings.

In casting an ingot, for example, the metal is poured or teemed in the usual manner into the ingot mold. After the desired quantity of metal has been placed in the mold the top surface is blanketed with an insulating layer of any suitable material, such as a slag, preferably a low fusing slag having good insulating properties; or it may be blanketed byadding materials'capable of formin such a slag when said materials are heated y the molten metal in the mold without injuriously chilling the metal, or by adding a fuel, as charcoal or coke, as the insulating material. An open-ended form is then placed or floated on the molten metal, preferably a frustum whose major diameter 1s considerably less than the diameter of the top of the ingot mold. This form may be floated on the metal either before or after placing the blanket thereon. The most practical form'is the frustum of a cone or of a square pyramid. The base of the frustum is preferably formed with a large bearing surface, either by thickening the lower end, or by forming an external flange on said end. Any material fusing at a high temperature may be used, fire-clay having been found quite suitable. Care should be taken that the frustums are thoroughly dry, to prevent explosions and injury to the workmen, and if desired, they may be heated to any desired temperature before being placed on the molten metal in the mold. As the metal sets the frustum becomes fastened in the metal, or, as it were, frozen in place. It is necessary for the subsequent operations, that the form be held, as otherwise it would rise when additional. molten metal is added. When the metal has set, or even before this has taken place, it is referable, but not necessary to place additional insulating material on top of the blanket in the annular space between the frustum and the inner walls of the mold to a depth approximately the height to which the frus tum projects above the metal surface in the mold, that is to say, about on a level with the top of the frustum. After about onethird to one-half the total volume of the ingot has set or solidified, a depression forms in the molten center of the ingot, which is about one-half the volume of the pipe, were such allowed to be formed. Molten metal is then poured through the frustum into the depression until the frustum is filled or about filled with this added metal.

It is well understood in present practice that molten iron or steel when in condition for castin is of a much lower temperature than the hlghest temperature of the furnace, the aim being to have the metal at as low a temperature as possible and still sufficiently limpid or fluid to fulfil all the conditions for casting, and also with the aim to produce a casting with as little pipe as possible.

It is also well known that segregation takes place at the center of the ingot to a greater or less extent, according to the'composition of the metal and its rate of cooling. Now,

mold, segregation is broken up and distributed over a large volume by the stirring action of the molten stream of metal striking that fluid portion of theingot in which the segregation had already commenced. By thus distributing the segregation over a large volume the degree of segregation in erably purer, addition of high temperature,

that-is to say, the temperature of the molten" metal added is higher than that of the greater volume of metal first placed in the mold. When this additional molten metal is poured or teemed into the form, it sinks through the blanket of sla'g or other material that is inside the form, and first fills the depression above mentioned, and then rises in the form, at the same time raising the blanket on its surface. This raised portion of the blanket on'the hot molten metal addition in the form now prevents the added metal from cooling too rapidly. The segregated area Within the ingot, which was still molten at the time the hot metal was added, now receives heat from the hotter molten addition. The segregated volume contains a greater percentage ofmetalloids than the molten addition, and, being lighter, it rises and mixes with and diffuses in the purer metal (of the same, or different composition, as the body of metal first poured) as above described.

The center then cools down, (segregation and tendency to pipe still continuing, the segregated area being lifted wholly or partially into the body of metal added,) and this added metal sinks, to follow up the shrinkage due to cooling, and effectually prevents the formation of a pipe in the ingot proper.

It will be noted that no mechanical means are used to hold the form in place, this being done by the molten metal itself, and that the form need not be of undue Weight to hold it down, it being only sufficiently strong to withstand the hydrostatic .pressure due to the height of the added metal above the level of the upper surface of the ingot proper.

.The form being of much less diameter than the upper surface of the ingot enables it to be quickly inserted in the mold at the proper time, and also reduces the volume of metal to be scrapped.

Another, most important, advantage results from the use of this method of making sound castings, in that the ingot mold may befilled to any depth desired, thereby avoiding the necessity of providing difi'erentsized molds for ingots of different weight, as it is immaterial to what depth the mold'is filled fixing or freezing the form in place.

When the metal, in casting condition, is found to be sufliciently hot when first poured or teemed into the mold to give plenty of time for the various manipulations, the, form may at once he floated on its surface and ,l'frozen into place by causing a skin to form the annular surface between the outer walls of the bottom of the frustum and the inner walls of the ingot mold; and this may be done by packing this annular space with molders sand, or the equivalent, the aim being to maintain the surface portion of the metal inside the form in such a condition that the molten addition may combine with the segregated area and follow up the shrinkage, and form a solid ingot as homogeneous throughoutas possible.

'We are aware that it has heretofore been proposed to blanket an ingot top With the idea'of reducing the volume of the pipes, but practice demonstrates that the volume remains substantially the same, though the shape is considerably altered.

Our purpose in using a blanket is, primarily to prevent too rapid cooling, and preserve the top molten only for a suflicient length of time to permit the insertion of the form, and to maintain the surface of the casting Within the form in proper condition until metal can be conveniently added to produce the result we attain.

. Referring to the accompanying drawings, in which like parts are similarly designated, Figures 1, 2 mil 3 are vertical sections of an ingot mold intended to illustrate our process at different stages; Fig. 4 is a similar view of the ingot. Figs. 5, 6 and 7 are views similar to Figs. 1, 2 and 3, but-where the mold is not cast full. Figs. 8, 9 and 10 are modified forms of fire-clay forms.

The ingot mold 1 in Fig. 1, is indicated as containingmolten metal at 2, with a molten slag covering 3 and a cylindrical form 4. floated thereon, the space between the mold 1 and form 4 being filled with molders sand 5. v

In Fig. 2 the metal is supposed to have partially solidified. as indicated at 2 adjacent the sides of the mold 1, leaving a central molten portion 6, intended to indicate the area of segregation. It will be noted that the slag layer within the form 4 is thicker, indicating that additional slag or slag forming material has been placed in the form With carbonaceous material 7 on shown as raised and smaller, extending into which comprises filling a mold to the the form with the slag layer 3 on top.

In Fig. 4 we have shown the in ot removed from the mold and the form roken away, and showing a few recesses or holes 9 in the neck below the slag layer 3".

Figs. 5, 6 "and 7 are identical with Figs. 1, 2. and 3, except that there is less metal -shown in the molds 1.

Figs. 8, 9 and 10 show different forms of' frust-a. In Fig. 8 the walls of the frustum 10 are of uniform thickness, while in Fig. 9 they are ta red, being thicker at the bottom of the i'i ustum 11. In Fig. 12 the frustum 11 is shown as having an external base flange 12.

We claim-- 1. The method of making sound castings, which comprises pouring molten metal into a mold to any deslred depth, placing a form on the metal therein and allowing it to freeze in place, and then ouring into the form, while the center of tlie casting is still molten, an additional (Eantity of metal.

2. The method of ma 'n'g sound castings,

which comprises pouring molten metal into a mold to any desired depth, placing a form on' the metal therein and allowing it to freeze in place, and then curing into the form, while the center of t e casting'is still molten, an additional quantity of metal of a composition calculated to mix with the molten metal to arm a composition sub stantially the same as that of the body of the casting.

3. The method of making sound cast-in s,

esired depth, freezin an open-ended form on, the; surface of t e metal in the mold While maintaining the center of the castin molten and its surface metal within sai form in condition for the reception of a subsequent quantity of molten metal, then placing in the form such molten metal, said added metal being of a temperature higher than the temperature of the molten center of the castin r 4. The metiod of making sound. castings,

which comprises filling a mold to the depth desired, freezing an open-ended form in the top of the metal,-while the center of the casting is still molten, then filling said form with molten metal having a temperature higher than that of the metal first placed in the mold.

5. The method of making sound castings, which comprises filling a mold to the depth desired, freezing an open-ended form in the top of the casting and pouring into said form hot molten metal, after one-third to one-half of the volume of the casting has solidified. v

6. The method of making sound castings, which comprises pouring molten metal into a mold to any desired depth, blanketin the metal, floating a form on the blan eted metal and permitting said form to freeze in place, and pouring hotter molten metal into and through said form.

7. The method of making sound castings,-

which comprises filling a mold to the depth desired, placing an open-ended-form in the top of the metal, blanketin the surface of the metal within the'form, reezing the form in position and placing hot metal in the form. a

8. The method of making sound castings, which com rises fillin a mold-to the'depth desired, b anketing t e top of the metal with slag, floating an o en-ended form on the surface of the meta, said form being frozen in place, packing the annular s ace between the exterior surface of the orm and the interior surface of the mold with refractory packing material and fillin the form with. an a ditional quantity 0 hot metal poured or teemed through the slag layer within the hollow form.

- 9..The method of making sound castings, which comprises pouring molten metal into a mold to any deslred depth, placing a form on the metal therein and allowing it to freeze in place, and then pouring into the form, while the center of t e casting is still molten, an additional quantity of metal, and controlling the degree of mixing of the added metal drops efore entering the form. In testimony that we claim the foregoing as our invention, we have signed our names in presence of two subscribing witnesses.

FRANK D CARNEY. LEWIS B.

Witnesses:

Geo. PARSONS, CHAS. R. HoL'roN.

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