US1792581A - Method of making nonporous articles - Google Patents

Description

Feb. 17, 1931. FIRTH 1,792,581

METHOD OF MAKING NONPOROUS ARTICLES Filed Aug. 12, 1929 A u" 5;" a

Patented Feb. 17, 1931 UNITED STATES LOUIS GERALD FIRTH, O1 PITTSBURGH,

PATENT OFFICE PENNSYLVANIA, ABGIGNOB TO FIRTH- OF PENNBYLVAN IA METHOD OF MAKING NONPOROUS ARTICLES Application fled August 12, 1928. Serial No. 885,256.

This invention relates to a method of making nonporous articles.

Ingotsof steel or other metals or alloys are now usually cast in molds having a substantially square cross-section. The ingot molds are sometimes provided with hot-tops through which the metal is poured into the mold, the hot-tops being used to keep the metal in liquid condition, thereby tending to decrease the amount of shrinks, pipes, an porosity of the cast ingot. Even with the use of hot-tops, however, the ingots are somewhat porous and for certain purposes it is necessary to scrap a large proportion of the ingot and use only that portion of the ingot which is substantially entirel free from orosity, segregation and shrin s. In makmg pistons for pneumatic rock-drills, valve seats and valves which are to be subjected to great pressures, or for airplane work, or other similar usa es, it is necessary that the metal be substantially free from defects such as segregation, shrinks, or porous structure.

My invention is particularly adapted where it is necessary that the ingot be substantially free from the defects above mentioned. The usual process of casting ingots as practiced at the present time is to pour 1n such a wa that the last ortion to cool is at the top 0 the ingot an may be discarded. However, in any given cross section of an ingot at right angles to its longitudinal axis, the last portion to cool is the extreme center. It is probable that the central 5% to 15% of this cross section cools almost similutaneously, i. e., the solidification is progressive from the sides of the mold up to a certain point, at which oint more or less simultaneous freezing ta as place. It is this central 5% to 15% which contains the greater part of the segregated 1mpur1- ties and gases. This central portion also usually cools progressively from the bottom of the ingot to the top and it is customary to discard the upper portion or ipe end which, generall speaking, is the ast portion to cool. l t is impracticable, however, under present ractice to discard the whole of that centrai axis or core which extends from the bottom to the top of the ingot and which contains the steel last to cool in each horizontal plane.

In my invention, I not only discard the top portion of the ingot, according to common practice, but 1 also sever the ingot lon 'tudinally and discard that portion in eac horizontal plane which was the last to cool. It is in this respect that my invention difiers radically from present da practice. The approximate amount of t is last cooled portion to be removed according to my process is from 10% to 30% of the original weight of the ingot, this bein taken maml rom the central portion of tie castmg. en a very high degree of perfect1on 1s required, as much as 50% of the original weight may be removed from the central portion. This can be regulated by cuttin the ingot nearer or further from its centra axis.

In my reference to horizontal planes and longitudinal axis I refer to ingots cast upright according to the usual practice, but my Invention can also be ap lied when the ingot is cast with the longitu inal axis slop-' ing or horizontal. In accordance with my invention, the ingot is cast in a mold having recesses formed therein which form flanges on the ingot extending outwardly from the body portlon of the ingot. Any shrinks, pipes, or porous structure which may be present in the ingot are in the central portion thereof, and the flanges are free from such defects. The flan es are then separated from the relative y porous body portion and are worked by rolling or other shaping methods to form the desired articles.

In the accompanyng drawings, which illustrate several present preferred embodiments of my invention;

Figure 1 is an elevation of an ingot mold;

Figure 2 is a section on the line IIII of Figure 1, showing the ingot in the mold;

Figures 3 and 4 are sections similar to Figure 2, but showing ingots having four and five flanges, respectively;

Figure 5 is a section similar to Figures 2, 3, and 4, but showing another modification;

Figure 6 is a horizontal section of one of the flanges formed on the ingot, after the flange has been separated from the body portion of the ingot; and

Figure 7 is a perspective view of a rockdrill iston.

Re erring more particularly to Figs. 1 and 2 of the drawings, there is shown an ingot mold 2 which is generally triangular in shape. The mold is formed of sections 3, 4, and 5, which are bolted together by bolts 6 and nuts 7. The mold is provided with recesses 8 extending radially from a central recess 9. The recesses 8 taper outwardly from the central portion of the mold, for a purpose hereinafter described.

In casting an in ot in the illustrated mold, the metal is poure in the usual manner, refcrably through a hot-top. The metal ows into the recesses 8 to form an ingot having a central body )ortiou 10 and flanges 11 extending therefrom. Each of the flanges 11 has its three outer sides cooled by the mold. The side of the flange 11, which is connected to the central portion 10 of the ingot, remains hot for a longer time than the other sides of the flan es which contact with the mold sections. he cooling action of the ingot takes place first on the sides exposed to the mold sections so that the flanges 11 are formed without shrinks, porous spots, or segregation. The only porous portion of the ingot is the central ortion 10.

The anges 11 are then separated along the lines 15 from the central portion of the ingot which was the last portion to cool. After separation the flanges, which are entirely solid, are rolled, for ed, or otherwise shaped into the desired articles.

The ingot shown in Figure 3 is similar to the ingot of Fig. 2, except that in Fig. 3 the ingot has four flanges 110: instead of three. An ordinary mold of substantially square cross-section can be converted into a mold embodyin my invention b inserting filler blocks 21 in the corners of t e mold in order to form a mold having recesses 80: which form flanges 11a on the in t. \Vhen the mold shown in Fig. 3 is use for casting the ingot, the flanges 11a are separated along the lines 15a from the central portion of the ingot.

In Fig. 4 there is shown a mold having five recesses 86, which form an ingot having five flanges 11b extending radially therefrom. My invention contemplates the formation of an in ct having any number of flanges forme thereon.

In Fig. 5 another form of ingot mold is shown. This mold has recesses 80 formed therein, which form the flanges 110 on the ingot. It also has recesses 25 provided in the mold which form flanges 26 on the ingot. When a mold of this sha e is employed, the flan es 8c are separated rom the remainder of t e ingot along the lines 150 and only the two flanges 110 are worked to form the desired articles. The recesses 25 in the mold and the corresponding flanges 26 formed on the ingot are provided in order to cause the shrinks and segregations to take place as indicated at 27, and in order that the flanges 110 will be free from such defects.

The illustrated molds are made in sections which are bolted together in order to free the molds. If desired, solid molds may be employed instead of split molds, and any number of recesses may be provided in the molds to form a corresponding number of flan es on the ingots.

The recesses 8, 8a, 8b, and 80, preferably slope outwardly from the central portion of the mold. In Fig. 6 there is illustrated a flange 11 formed in the mold illustrated in Fig. 2. As above stated, the flanges 11 are substantially free from porosity and segregation. However, there is a small portion 12 of the flange which is not quite as dense as the remaining portion of the flange. This is due to the fact that the ortion 12 is the last to cool. In order to ma e the density of the billet rolled from the flange 11 absolutely uniform, the flanges are cast having a slight taper outwardly from the central portion of the ingot. The inner portion 30 of the flange accordingly is subjected to greater work than the outer portion 31 when the flange is rolled. The greater amount of work to which the portion 30 is subjected ives the rolled billet substantiall uniform ensity throughout.

After rol ing, forging, or otherwise shaping the flange 11, it is formedinto the desired article. a

A piston 35 for a rock-drill is illustrated in Fig. 7. Pistons made according to my invention are free from porosity, shrinks, and other defects and are particularly adapted for the work which they have to perform. If a iston for a rock-drill is slightly porous, it is ikely to crack under the strain imposed by the terrific impact of the piston against the other parts of the rock-drill.

M invention is especially useful in the PlOdXlOtiOll of alloy steel articles which are expensive and in which it is desired to reduce to a minimum the portion of the ingot which it is necessary to discard because of its orous character.

I desired, the ingot may be cast into molds which are rotated in order to force the metal from the central portion of the mold into the recesses which form the flanges on the ingot.

I have illustrated and described several preferred forms of the invention. It is to be understood, however, that the invention may be otherwise embodied within the scope of the following claims.

I claim:

1. The method of makin non-porous metal articles, comprising casting the metal to form an ingot having a body ortion and flanges thereon, separating the anges from the body portion and forming the article from the flanges.

2. The method of making non-porous metal articles, comprising casting a solid ingot having a body portion of relatively porous metal and flanges of relatively nonporous metal, separatin the flanges from the body portion and orming the article from'the flanges.

3. The method of making non-porous steel pistons for pneumatic hammers and drills, comprising castin a steel ingot having a body portion and anges thereon, separating the flanges from the body portion, and formin the flanges into pistons.

i. The method of making non-porous metal articles, comprising casting the metal to form an ingot having a body portion and flanges thereon, longitudinally separating the flanges from the body portion, and forming the article from the flanges.

5. The method of making non-porous metal articles, comprising casting the metal to form an ingot havingra body portion and flanges extending there om, the flanges and body portion being connected throughout the major portion thereof, longitudinally separating the flanges from the body portion, and forming the article from the flanges.

6. The method of making non-porous metal articles, comprising casting the metal to form an in ot havin a body portion and flanges exten mg there rom, the flanges and body portion being connected throughout substantially their entire lengths, longitudinally separating the flanges from the body portion, and forming the article from the anges.

In testimony whereof I have hereunto set my hand.

L. GERALD FIRTH.

pistons for pneumatic hammers comprising castin body portion and anges thereon, separating the flanges from the body portion, and forming the flanges into pistons.

the body portion and forming the article from the flanges.

2. The method of making non-porous metal articles, comprising castm a solid ingot having a body portion 0 porous metal and flanges of relatively nonporous metal, separatin the body portion and from the flanges.

relatively the flanges from orming the article 3. The method of making non-porous steel and drills, a steel ingot having a The method of making non-porous metal articles, comprising casting the metal to form an ingot having a body portion and flanges thereon, longitudinally separating the ing the article from the flan es.

anges from the body portion, and form- 5. The method of makm non-porous om, the flanges and 6. The method of making non-porous metal articles, comprising casting the metal to form an in at havin a body portion and flanges exten mg there?! body portion being connected throu hout substantially their entire lengths, longitudinally separating the flanges from the body om, the flanges and ortion, and forming the article from the anges.

In testimony whereof I have hereunto set my hand.

L. GERALD FIRTH.

CERTIFICATE OF CORRECTION.

Patent No. 1,792,581. Granted February 17, 1931, to

It is hereby certified that the christian name of the patentee in the above numbered patent was erroneously written and printed as "Louis" whereas said name should have been written and printed Lewis; and that the and Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 17th day of March, A. D. 1931.

M. J. Moore,

(Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,792,581. Granted February 17, 193], to

It is hereby certified that the christian name of the patentee in the above numbered patent was erroneously written and printed as "Louis" whereas said M. J. Moore. (Seal) Acting Commissioner of Patents.

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