US1648471A - Casting - Google Patents

Description

N. M. Aus-rmy CASTING Original Filed March 5, 1923 Nov. 8, 192 7.

Patented Nov. 8, 1927.

UNITED STATES- NED II.- AUSTIN, 0E CANTON, onIo, AssIeNon To UNITED ENGINEERING a EoUNncaY 1,648,471 PATENT OFFICE.

COMPANY, PITTSBURGH, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA.

onsTINca Original application led MarchJ 5, 1923,

The present invention relates to theart 0f molding, and more'particularly to castings; the present application being a division of my copending application, Serial No.`

622,841, filed March 5, 1923 and issued as Patent No. 1,544,544 dated July 7, 1925.

In making certain types of castings, particularly cast rolls it has heretofore been the ractice, in order to obtain the desired dept of chill, to employ a com osition of metal having the roperty o freezing quickly. The quick reezing, however, does not allow suiiicient time for the graphite to separate out enough to give a solid .gray interior to the casting. -The quick' freezing also has a tendency to set up casting strains which, when a casting is broken, show in the form of radial streaks from the surface toward the center.

By the present invention, 'I propose to overcome the above mentioned and other disadvantages of the-prior practice, b et'1 ecting a change in the chemical and p ysical interior structure of a casting after the molten metal has been poured into the mold,

' and preferably, after the superficial .por-

tion of the molten metal has cooled and solidiiied to -formI an outer shell. change is` produced .by causing the diffusion into the interior of the molten metal of a diii'erent metal or material. The invention is of particular importance in connection with the casting of rolls, it being desirable,

v od; and

for example, to lower the meltin point of the metal of which the interior'o the casting is composed in order that this portion of the casting will not cool too quickly.

` Two slightly different methods for prac.- ticing my invention are illustrated in the accompanying drawings, in which:

Fi res 1 and 2 are similar vertical sectiona views of a mold illustrating one lnethod of carrying my invention' into efect;

Figure 3 is a view similarto Figures 1 and 2, illustrating a slightly modified meth- Figure 4 is a sectional view of a roll castin made in accordance with my invention. eferring tothe drawings, A represents an. ordinary sand mold, which may have one or more mold cavities, for casting rolls.

AThis mold has the usual pouring basin 1,

strainer c ore 2, and the vertical and horiviicia'l portion of the metal surroundin This Serial No. 622,841. Divided'and this application led January 10, 1925. Serial No. 1,528.

zontal passages 3 and l4, constituting the 55 gate, for introducing the molten material lnto the mold, and the riser vents 5. While l have shown a mold for casting rolls, it will be understood that m -invention is not hmited to rolls, but is app icable to castings generally, irrespective ofshape or intended use.

In'a'ccordance with the method illustrated In Figures 1 and 2, a pipe 6 is introduced 1nto the mold through a riser vent'5, prior 05 to the pouring ofthe molten metal into the mold. The lower end of the ipe is closed by ay wall of the mold, and t e pi e is of some material which will not me t when subjected to the heat of the molten metal lo surroundin the. pi The molten metal is now pour into t e mold and the supet e pipe may be allowed to cool and solidi to form an outer shell. Then the pipe 6 is filled with molten material, which may be another metal, for instance, and the pipe gradually withdrawn from the mold. to allow the 'molten material contained within it to diii'use into themolten metal in the interior of the shell, thereby changing the cplnliposit-ion of the casting up to the frozen s e In Figure 3, I have illustrated a slight modification of the above described method, According. to this method, a bar. 7 of different chemical analysis 1s inserted down through a molten mass, of metal in a mold, said barmelting and dilusing into the surrounding metal as in the first method.

It will be understood, of course, that in the case of rolls, the .object is to obtain eX- treme hardness in the-outer portion 'of the roll for a considerable depth while giving to the interior of the roll great tensile strength. e By the introduction of various metals, in the manner above described, and containing varying proportions of silicon, manganese, carbon, chromium, molybdenum, nickel, copper, cobalt, tungsten, titanium, alumi- 100 Anum and the like, I am enabled to change the internal structure of a roll casting so as to reatly increase the strength ofthe roll, am? I am .at the same time enabled to chill to the. desired depth. In fact, the present invention enables chilling to greater de ths than vformerly without weakening the rol.

In Figure 4, I have illustrated a roll casting made in accordance with either of the methods above described..

I claim:

1. A casting having its outer and interior portions of different compositions7 the interior portion consisting of the same mate-7 rial as the outer portion plus additional material diiused thereinto 2. A casting having a relatively hard chilled outer portion and an interior portion of relatively high tensile strength, the interior portion consisting of the same material as the outer portion, plus additional materiai dused thereinto.

3. A. casting having a chilled outer portion and a solid gray interior portion of a different composition from said outer por-- ytion but formed in part of the Same material as the outer portion of the casting.

4. A. casting roll for rolling mills having a chilled outer vportion and a solid gray interior portion of a different composition from said outer portion and formed of the same material as the outer portion but hav-- ing alloying material diffused therethrough.

In testimony whereof I have hereunto set my handc NED M. AUSTIN.

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