US2170103A - Method of and means for producing castings - Google Patents

Description

C. E WESTOVER PRODUCING CASTINGS METHOD OF AND MEANS FOR Filed Oct. 10, 1938 2 Sheets-Sheet l wvwvbv INVENTOR.

A TTORNEYS.

Aug. 22, 1939. c. E. WESTOVER METHOD OF AND MEANS FOR PRODUCING CASTINGS Filed Oct. 10, 1938 2 Sheets-Sheet 2 C. L Ws'tolxefl INVENTOR.

ATTORNEYS.

Patented Aug. 22, 1939 UNITED STATES METHOD OF AND MEANS FOR PRODUCING CASTINGS 0. Edward Westover, Chicago, Ill.

Application October 10, 1938, Serial No. 234,234

4 Claims.

This invention relates to a method of and 5 tions.

Unless the cooling rate in the different portions of a casting of different sections is maintained substantially uniform, variousdefects are produced, such as shrink cracks, hot tears, and 10 "piping" or internal shrink cavities. The shrink cracks and hot tears usually are eliminated by the use of surface chills or cracking brackets. The main problem has been to prevent the formation of a cavity or spongy structure at the heart 15 or center of the casting, the same usually being known as piping. This fault is due to the fact that the heart or center of the heavy metal section cools more slowly than the outer portions. As the hot metal cools it shrinks, and the outer portions of the metal solidify first, thereby fixing the volume of the casting. The metal, while cooling, tends tomalntaln uniform density of structure and as continued contraction progresses toward the heart or center, a point is reached liltimately where there is not enough metal to fill the established outer volume with uniform density of structure. Consequently there is produced a center which is either spongy or develops a shrink or "pipe. m The foregoing facts are well known to those skilled in this art and various means have been developed in an effort to eliminate the faults mentioned. Among these the mosteffective have been internal chills. These have been in the form of coils, masses of cold metal, and nails, the chills being placed in the molds where they have been surrounded by and fused to the molten metal. As the chills are of the same kind of metal as that being poured and as they tend to 40 equalize the cooling rate, the method described has in some cases resulted in elimination of the defects heretofore mentioned. In many cases, however, the chills now used produce defects of a different type known as chill kicks or -blows. These defects are formed by trapping gases generated by the sudden envelopment of oxidized or corroded chill surfaces or surfaces containing moisture or other accumulations convertible into gas by heat. They are more objectionable than the "piping" heretofore mentioned and, consequently, internal chills are being used with a degree of uncertainty for accomplishingtheir purpose.

In experimenting with internal chills it has been found that when nails were used as chills with their points up, the "blows were less objectionable than where they were supported with surfaces, and more especially their top sides, in horizontal planes. Further experiments disno closed conclusively that by the use of chills specially shaped and positioned so as to eliminate horizontal surfaces, the "blows or chill kicks were eliminated and, as the rate of cooling is equalized, the produced castings generally have been free from defects.

An object of the present invention is to provide internal chills s0 shaped and positioned that none of them will have flat horizontal surfaces but, on the contrary, the top surfaces will all converge upwardly to points or lines so that no top surface will have all portions enveloped instantly by molten metal.

r A further object is to provide internal chills having upwardly inclined surfaces along which gases are free to flow as quickly as generated following contact of molten metal with the surfaces so that the submergence of each chill is thus gradual and ample time is afforded for the escape of any generated gases before the chill is completely submerged and fused.

With the foregoing and other objects in view the invention consists ofcertain novel details of construction and combinations of parts and certain steps of the method hereinafter more fully described and pointed out in the claims, it being understood that various changes may be made without departing from the spirit of the invention as claimed.

In the accompanying drawings the preferred forms of the invention have been shown.

In said drawings Figure 1 is a vertical section through a mold equipped with chills constructed in accordance with the present invention and positioned to produce the results desired.

Figure 2 is a similar view showing the release of generated gas from the lower chill while the mold is filled to a point where said chill is partly submerged.

Figure 3 is a similar view showing the molten metal at a higher level, the lower chill being completely submerged and the chill at another level being nearly completely submerged.

Figure 4 is a similar view showing the molten metal after it has submerged all but the uppermost chill.

Figure 5 is an enlarged side elevation of one of the chills as shown in Figures 1 to 4 inclusive.

Figure 6 is a section on line 6-6, Figure 5.

Figure '7 is a section on line 11, Figure 5.

Figure 8 is a side elevation of a modified form of chill.

Figure 9 is a section on line 9-9, Figure 8.

Figure 10 is a side elevation of another modified form of internal chill.

Figure 11 is a section on line II-l I, Figure 10.

Figure 12 is an elevation of as old form of internal chill having a horizontal top surface, a blow or chill kick being indicated within the molten metal surrounding the chill.

It is to be understood that the, internal chills forming a part of the present invention can be of various shapes and sizes. It is merely essential that they be so shaped that, when properly placed in a mold, they will be formed with upwardly inclined surfaces and will be free from horizontal surfaces, especially at the tops of the chills. In the form illustrated in Figures 1 to 7 inclusive, the chill is formed with a head I in the form of a double pyramid, the apex portion of One of the pyramids merging into an elongated tapered stem 2 having flat surfaces which converge to a point 3. If preferred, however, the head of the chill, as shown in Figure 8, can be made of a double cone shape, one apex of this modified head 4 merging into a tapered stem 5 having flat surfaces as shown in Figure 5.

In Figure 10 the chill is of another shape and includes an elongated rectangular portion 6 having pyramidal ends I one of which merges into an elongated tapered stem 8 having flat sides which converge to a point 9.

It will be noted that when any one of the internal chills which has been shown is placed with its longitudinal center in a horizontal or in a vertical position, the said chill can be so located that all of its surfaces will incline upwardly 'so that there will be no horizontal top surface on any one of the chills.

In practice the chills are placed in the cavity C of a mold M, the heads thereof being so located as to insure equalization of the cooling rate of all portions of the casting. Some of the chills, if desired, can be arranged vertically with their heads uppermost or lowermost while others can be arranged horizontally. In every case, however, the chill has all of its surfaces inclined upwardly, the lower surfaces in the form shown diverging upwardly from a low point or line while the upper surfaces converge upwardly toward a high point or line.

With the chills located as explained and as shown, for example, in Figure 1, the molten metal X can be poured into the mold and as the level thereof rises gradually within the mold, the lowermost chill or chills will be gradually enveloped but at no time will an entire surface be completely enveloped instantaneously, as would occur should one of the top surfaces be horizontal. Consequently if the chills have surface accumulations of any substances which would be converted into gas when contacted by the molten metal X, the gases thus generated would be released upwardly in advance ofthe rising surface of the molten liquid as fast as the level of said liquid contacts with the chill and causes the gas generation. Thus the gas will not be trapped along any portion of the chill but will escape along the inclined surfaces thereof until the uppermost .point or line of the chill is reached, as shown for example in Figure 3. Therefore there will be no formation of a blow or chill kick and as the chill also serves to equalize the cooling rate, the resultant casting generally will be found free from all of the defects heretofore resulting from the use of internal chills.

Attention is directed to Figure 12 which shows a nail positioned with a horizontal top surface. This figure shows a blow B within the metal of the casting directly above the horizontal surface 8 of the nail N. Obviously accumulations wise would be produced.

become trapped and cannot rise through the.

metal thereover, thus producing the defects indicated. As has already been pointed"out,-by the elimination of fiat horizontal surfaces and, preferably, all horizontal surfaces, and the utilization of surfaces which are inclined or rounded upwardly, gases are free to flow upwardly along said surfaces as fast as generated and before they can become enveloped, so that the resultant casting will be free of the defects which other- What is claimed:

.1. The method of producing a casting without a blow and with separate internal chills forming a permanent part of the structure of the casting, which includes the step of positioning each chill with one end engaged and supported by the mold and its other end contained wholly within the mold cavity, said chills being extended along different lines from points adjacent to the center of the cavity, each chill being constructed and positioned to present no horizontal top surface, and subsequently pouring molten metal into the mold to gradually envelope the top portions of the chills.

2. The method of producing a casting without a blow and with an internal chill angular in cross-section and forming a permanent part of the structure of the casting, which includes the step of positioning the chill withone end engaged and supported by the mold and its other end contained wholly within the mold cavity, said chill being so constructed and arranged that all of its surfaces are inclined upwardly along straight lines and no horizontal surface is presented, and thereafter pouring molten metal into the mold to gradually submerge and fuse the chill, to reduce to gas at the level of the molten metal any accumulations on the chill convertible by the hot metal into gas, and to allow free flow of the generated gas upwardly along the surfaces of the chill in advance of the rising level of the metal.

3. The combination with a mold having a cavity for receiving molten metal, of separate chills each supported at one end by the mold and having its other end portion extended into the mold cavity, said chills being extended in opposite directions from points adjacent to the center of the cavity and each chill having all of its surfaces extending upwardly within the cavity, all of the chills being positioned for gradual submergence by the rising level of molten metal while being poured into the cavity.

4. The combination with a mold having a cavity for receiving molten metal, of separate chills each supported at one end by the mold and having its other end portion extended into the mold cavity, said chills being extended in opposite directions from points adjacent to the center of the cavity and each chill having all of its surfaces extending upwardly within the cavo. EDWARD WESTOVER.

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