US1692491A - Hot top for ingot molds - Google Patents

Description

INVENTOR M G DUMAS HOT TOP FOR INGOT MOLDS 0r1g1nalF1led Sept 23 1927 Nov. 20, 1928.

Patented Nov. 20, 1928.

UNITED STATES PATENT OFFICE.

MAXWELL GERSON DUHAS, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO DUMAS ENGINEERING COMPANY, OF YOUNGSTOWN, OHIO, A CORPORATION OF OHIO.

new no? non moor norms.

Continuation of application Serial No. 221,461 filed September 23, 1927. This application filed July 27, A

1928. Serial No. 295,680.

This invention relates to hot tops for ingot molds and is a continuation of application Serial Number 221, 461,'filed September 23, 1927, for hot top for ingot molds.

During the casting of steel and other ferrous alloy ingots, it IS customary to pour the molten metal into a mold. Coolin in the mold takes place from the sides an" bottom of the ingot, resulting in the formation of a cavity or pipe in the upper central portion of the ingot. A large portion of impurities present in theingot are forced into the c'av-.

ity or pipe.

Before the ingot can be subjected to its final finishing operation, it is necessary to cut oil or crop the upper defective portion. of the ingot, with a resulting waste of material. In order to reduce the losses incident to the cropping of ingots, hot'tops or sink heads have been provided to serve as reservoirs of molten metal for filling the cavity formed during the solidification of the ingots. The walls of such hot tops are heat insulated in order to insure that the metal contained therein remains in a liquid state until after the solidification of the metal in the ingot.

Heretofore, such hot tops have had substantially straight side walls. Experience has shown that'in a hot to having a straight side wall, solidification ta es place uniformly inwardly from the side walls, with the result that a shell of solidified metal surrounds the liquid metal preserving it in its liquid state for filling the cavity in the ingot.

The thickness of such a protecting shell depends upon the size of the ingot and the rate of heat dissipation from the hot top. With a straight side hot top, the solidified metal,

40 after the cooling operation of the ingot and metal in the hot top is completed, assumes tially parallel sides. In such a structure the openings for permitting movement of molten metal from the hot top to the ingot proper during the final stages of solidification, has

been materially greater than necessary, resultin in the formation and wastageof a large block of metal as croppage.

I have found that by narrowing the sides of the hot top adjacent to the top of the mold, a material saving in the amount of 'croppage' is obtained. I also propose to narrow the upper portion of the hot top in order to eliminate the upper corners of croppage blocks as heretofore made. By inwardly drawing the portions of the wall of the hot top, I reduce the total radiating surface of the hot top as well as reduce the amount of material frozen therein without sacrificing any efficiency in its operation.

The narrowing'of the side walls of the hot top to form a constricted opening at the top and a constricted neck portion at the bottom for the .purpose stated is madepossible by the increased efiiciency in retaining the heat of the molten metal which is afforded by a structure of this form which serves to materially reduce the radiation losses inherent in straight wall hot top structures.

With a structure embodying my invention Lam able to increase the height of the hot top and thereby the pressure of the molten metal forced into the ingot cavity by sub- 'stantially 14%, and at the same time reduce the volume of the croppage by. 25 to 30%.

In a structure with a straight sided hot top,- the croppage is substantially 15% of the.

total metal poured into the mold. With my structure the croppage is only about 8% of the total metal poured. With a 20 inch mold the amount of croppage with a straight side hot top .is frequently in the neighborhood of twelve hundred (1200) pounds. Accordingly, the mometary value of the croppage, the value of which is several cents a pound, constitutes a considerable item in the cost of the finished ingots.

in the cost of molding ingots.

Iprefer to use a ceramic material for the hot top in order to secure heat insulation. the general shape of a block with substan- By mixing the ceramic material with clay and particles of wood. or other combustible substances before the ceramic material is fired, I am able to produce a porous hot top. The pores resulting from the combustion of the material during the burning 'of the ceramic mass, are filled with air which serves as a good heat insulator. The inner face of the hot top is painted with a refractory sli of clay and water before the hot top is fire Accordingly, by utilizing a hot, top embodying my inven-' The resulting refractory lining for the hot cordance with top prevents the circulation of the air on trapped in the pores and prevents the molten metal from eating into such pores.

While I have described the use of pores in the hot top, it is to be understood that the hot top may be made without such pores.

A suitable cap is provided for closing the upper end of the hot top. The cap is made more porous than the body of the hot top, and is not provided with a refractory lining in order to permit the escape of gases.

The accompanying drawings illustrate the present preferred embodiment of the invention, in which:

Figure 1 is an elevational view of a mold and hot top.

Figure 2 is a plan view thereof.

Figure 3 is a sectional view of a hot top embodying my invention, and

Fig. 4 is a perspective view of a cap.

Referring to Figure 1,' an ingot mold 1, of any desired cross vided with a hot top 2 having a mid-section 4 of greater diameter than its upper and lower sections 5 and 6 respectively, whereby the chamber defined within it approaches a sphere in shape. The outer walls of the hot top may be straight or tapered as the case may be, although it is preferably formed as illustrated for economy in the use of material.

The hot top is provided with an upper o pening 7 and a lower opening 8. The

opening 8 is, in part, defined by a flange 9 that extends downwardly into the body of the mold 1. The horizontal cross sectional shape of the flange 9 may be varied in acthe shape of the mold 1 with which it is associated. A variety of shapes such as rectangular or other polygonal shapes are on-the market. A shoulder 10 is provided above the flange 9 for engaging the upper surface of the mold 1 and supporting the hot top. A cap 11 is provided for closing the opening 7 The material of the'hot top 2 is preferably ceramic material made porous by inserting small particles of combustible material in the ceramic material before it is fired. A suitable ceramic material is refractorgy clay, which when fired produces a ho y of refractory material .havmga melting or excess of the temperature of molten steel. If desired the combustible material may be omitted from the ceramic material berore the firing operation, in which case pores 14 will not be formed in the refractory mawith a slip of clay,

s. and prevents the terial.

, The inner surface of the hot top 2 is provided with a refractory lining 12 produced painting the inner surface of the hot top which when fired producesa smooth surface that closes the pores sectional shape is p r0 preferred is to be understood that varlous changes inwardly in slagging temperature considerably in circulation of air between of the cap 11 is. preferably of very porous M ceramic material and is not lined in order to permit the escape of gases confined above the top of the molten metal. v

I have found that by making the ratio of the diameters of the opening 8 at least onefourth of that of the portion 4 of the hot top, satisfactory results may be obtained. At the same time, the saving of wasted metal by reducing the diameters of the sections 5 and 6 of the hot top is considerable as has been previously described.

By ta ering the walls of the hot top inwardly rom the mid-section 4, I reduce the radiating by secure a greater conservation of heat. The heightof the hot top constructed'with tapering up 6, respective y, may be increased by approximately 15% over a straight sided hot top and at the same time produce a saving of; 25% in the metal in the hot top. By

increasing the height of the hot top, the

embodiment of the invention, it

may be made therein without departing from the spirit of the invention or the scope of the appended claims.

vI claim:

er and lower sections 5 and.

.1. A hot topor sink head having its interior mid portion of greater diameter than the upper and lower portions.

2. In a hot top or sink head, a hollow body having a predetermined inner dimension at its intermediate section, the body tapering both directions from the intermediate section, and terminating in openings at the upper and lower ends thereof.

3. Ina hot top, a hollow body having a lower opening and an intermediate portion of greater dimension than said opening, the

- diameter of the lower opening being at least one-fourth of that of the intermediate portion.

4. In a hot top structure a hollow body portion the interior of'which is of substantially spherical form and'having openings in vertical alinement.

5. In a hot top a hollow body having its interior mid portion of greater diameter than its upper and lower portions and having a restricted portion intermediate the mid portion and the lower portion.

In testimony whereof I have hereunto set my hand this 24 day'of July, 1928, at Pitts burgh, Pa.

MAXWELL GERSON DUMAS.

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