US1296598A - Metal-mold. - Google Patents

Description

Z. JEFFRIES.

Mam MOLD.

APPLICATION FILED OCT. I8. |916. l

Patented Mar. 4, 1919.

3 SHEETS-SHEET] liu | l l I l l l l l V mln Elftown Z. IEFFRIES.

METAL MOLD.

APPLICATION FILED ocT. I8. Isle.

Patented Miu'. 4, 1919. 3 SHEETS-SHEET 2 I I L znY JEFERIEs, or EAs'r CLEVELAND,

in connection with the accompanying U ings, two of the many possible applications lthermal conductivities,

OHIO' 'ASSIG-NOIR. TO THE ALUMINUM CASTING I ENT otros. I

COMPANY, OF CLEVELAND, OHIO, A CORPORATION 0F OHIO.

To all whom it may concern:

Be it known that I, ZAY zen of the United States, residing at East Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and useful Improvements'in Metal-Molds, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to improvements in permanent metal molds such as are used in making castings of low fusing point metals, such, for example, as aluminum alloys. In this class of work great difculty has been experienced in securing sound castings in cases where the constituent material of the castings is necessarily unevenly distributed, the casting being relatively thick in some parts and thin in others. In the thicker part of the casting the metal remainsv molten after the metal of the thin part' has solidified, and when finally the metal of the thicker part solidiiies its resultant contraction tends JEFFRIES, a citi- `to draw it away from the already solid metal of the thin part and cracking of the casting,

or shrinking, or both, results.

The general object of the present invention is the provision of a permanent mold in which the above noted diIicult-y is overcome; and to this end I make a composite mold having dierent parts of Iits walls formed of different metals having different the metal of higher conductivity being disposed to contact with they thicker part or parts of the casting.

Further objects o the invention relate to the special form and arrangement of the mold partsv in the production of certain types of castings.

In the following description I set forth,

` drawof the invention.

In the drawings-4 Figure 1 is a plan view of arnold constructed in accordance with my invention and adapted for the production of fuse bodies. l

Fig. 2 is a vertical section on the line 2-2 of Fig. 1.

Specication of Letters Patent.

top sections 2 .tions 2 and 3 are Patented Mar. 4, 1919.

Application led October 18,A 1916. Serial No. 126,358.

Fig. 3 is an end elevation of the mold shown in Fig. 1.

Fig. 4 is a vertical of Fig. 1. l Fig. 5 is a side elevation of one of the finished castings produced in the mold.

Fig. 6 is a fragmentary vertical section through a mold embodyingI my invention and adapted for the production of metallic sectionvon the line 4-4 alloy pistons for engines. l

Fig. 7 is'a vertical section taken on theV line 7 7 of Fig. 6.

Fig. 8 is an end view of one of the sections of the mold shown in Fig. 6.

Referring in detail to the construction illustrated in Figs. 1 to 5, inclusive, 1 designates the mold base Iand 2 and 3 top sections thereof mounted on the base. These parts :are preferably iron castings. In the construction shown the mold is formed with a plurality of cavities so that several castings are made at one operation. Since the cavities are alike in all respects, a description of the mold structure with reference to one of the, cavities will suffice. Each of the mold cavities is formed in part in the base section 1 and in'part in the upper sections 2 and 3.

That part of the mold cavity formed in the base has a bottom wall 4 formed .with an upstanding core 5, and a side wall 6, the latter being circular 'in horizontal section. The and 3 have vertical abutting faces 2 and 3a, respectively, lying in a plane through the aXis of the cavity in the base and each of the sections 2 and 3 are formed with alining cavities 7which overlie t e cavity in the base and complete the walls of the mold cavity proper. In the mold secformed alining cavities 8 which extend upward from the cavities 7 to the top of the mold and serve to form a pouring gate.

The top sections 2 and 3 of the mold are slidably mounted on the base section, means being preferably provided to guide the top sections and position them accurately in relation to each other and.l to the base so that the several sections of the mold cavity are brought into proper alinement. purpose each of the top sections are fitted For this .i

j so

with a'tongue 9 which slidably fits in; a groove 10 in the base section. v

The'top section 3 carries at its ends swinging hooks 11, 11, which are adapted to engage pins 12, 12l carried by the section 2 and secure the parts of the mold in operative position in relation to each other.

As mold-s of this character were construct-y l ed prior to my invention, the bottom wall 4; of the mold cavity was formed of the same material as the other walls, that is to say, of iron; butI with these earlier molds the number of defective castings was exceedtraction caused it to draw away `from the solid metal at B and cracking or shrinking of the casting resulted so that, as stated. above, the losses were exceedingly heavy.

After the trial of many expedients to overcome this dilficulty, I have devised a simple and highly effective means for over.

coming the destructive shrinking and crack ing of the castings. Instead of forming the base of solid iron, I form therein a cylindrical aperture beneath and concentric with each mold cavity, and in this aperture I snugly fit a cylindrical block or plug 13 formed 'of metal of relatively high thermal conductivity, and I preferably employ copper for this purpose. he upper end of this copper insert is formed toprovide the bottom wall 4. with the upstanding core part 5 previously described; The insert may be` secured in the base in any suitable manner. Inthe construction shown I secure a bar'14 to the bottom of the base, arranging the bar to underlie the copper inserts 13, and then secure the latter tothe bar by means of screw bolts 16.

. In the use of my improved mold, the top sections 2 and 3 having been secured in op- :erative position on the' base, the vmolten I netal is introduced into the cavity by pouring through the gate. When the molten metal-.is poured into 'the cavity, heat is abstracted from that part'of the-metal at A 4ductivity of the copper wall at 4 and 5 which more rapidly than from the part at B because of the relatively high thermal concontacts with ,the metalv at A. By providing a. suitable mass of copper the coolmg of theA -metal at' A is effected ,more rapidly than at B thus causing the metal to 'set or solidify at A.while a portion at B is still molten. This molten center at B, furthermore, is cone is progressive toward the gate so that the latter receives the fullcrystallization shrinke. Thus the shrinkage. and cracking reviously referred to is almost entirely o lviated. When the metal of the castings is s0- lidified, the top sections 2 and 3 are drawn back and the castings lifted out.

As previously indicated, the mold shown in Figs. 1 to 4, inclusive, is for the productionjof the bodies 'of'fuses for explosive shells.l These' fuse bodies are commonly made of aluminum alloy. The inished cast-v ing, after removal of 'the -gate metal, is shown in Fig. 5.

In Figs. `6, 7 and 8 I have' shown my invention embodied in a mold designed fory the casting of aluminum alloy pistons. Except for the special means which/I employ foru controlling the cooling of the casting,

the mold shown is not of my invention and itneed not thereforebe described in full detail. Suli'ice it to say that the mold comprises a base section 21 and upper abutting 'sections 22 and 23. The necessary core parts of the mold are not shown and it will be understood that use may be made of any suitable core formed in sections to permit the withdrawal of the core parts around the bosses and ribs of the casting. The top sections 22 and 23 have vertical abutting faces 22a'and 23a, respectively, and these sections,

, it will be understood, are slidable on the base 4 with the mold cavity at 24.

25 is a piston produced inthe mold. Itis of the well known skirted type and is formed with pin bosses 26 and 27 and with f suitable strengthening ribs 28 and 29. The

pin boss 26 is formed with an enlargement or lug 26a which is designed to be drilled out and tapped tofreceive a set screw for securing the piston pin. 30, 30 are'core pins gfor the bosses 26 and27.

It will be observed that the formation of the boss 26, with its enlargement or lug 26a,

concentrates a relatively large or thick mass of metal at -this point in the casting..- Prior to my invention much difficulty was ,encountered in securing sound piston castings of -this character because the thinner parts of nected with the lgatemetal C by an unbroken' columnpf liquid metal ,and the final `freezing the casting "surrounding the 'boss enlargement-solidified befg'e "the greater' mass of the` enlargement an when'the latter later solidified, its shrinkage resulted in cracking of the casting which rendered' it useless.

This diliiculty I have overcome' by applying the expedient hereinbefoa'e described. lIn the case of the piston mold I bore out the wall ofthe top section 23 to receive a cylindrical plug 31 of copper.` As, shown, t hi's plug -is formed with an'extension or neck 31", thel of which'constitutes a part of the innerl ment 26a more rapidly than the remaining,

iron, parts of the mold wal withdraw heat from the other parts of the casting and, with a copper insert properly proportioned, the rate of cooling of the metal of the thick boss parts of the iston is increased to such an extent that t e freezing of said. thick parts occurs sooner than the freezing of the thinner metal parts between the bosses and the pouring gate and consequently the local shrinking and cracking which marked the earlier practice is avoided.

Itwill be observed, both in the case of the fuse body mold and in the case of the piston mold, that the casting to be made is of such a form that the mold cavity has a greater volume at certain points than at other points intermediate the first-named points and thel gate through which, the

molten metal enters the cavity and which,

in the casting operation, maintains a body ofmolten metal in communication with said cavity. Often, as in the two typical cases herein presented, it is difficult, if not practically impossible, to arrange the gate in such a way as to obviate conditions such as last referred to; and it will be seen that where4 such conditions exist there is a tendencyand in fact a practical certainty of the metal in the thinner part or parts of the cavity freezing before that in the parts of larger volume so that the molten metal y in the last named parts is separated from the molten metal supply in the gate by the freezing of `'the intermediate metal and, when the more remote metal finally solidifes, the shrinking and cracking which is hereinbefore referred to results. results are practically entirely obviated by means of my invention, in accordance with j which the mold walls are made of materials possessing different thermal conductivities, the material of higher conductivity being ldisposed to contact with the molten metal in the parts of the cavity of greater volume, while the wall material of lower conductivity is arranged to contact with the metal nearer the. gate which is' thus prevented from freezing until after the freezingl of the more remote metal. In other words, by means of my invention, a progressive freez- .ing of, the metal is secured, beginning at oints .more remote from the gate.

It will be understood, in connection with But these the molds. herein disclosed, that various changes in the form and proportion of the parts may be made and it w1ll also be understood that my invention mav be applied in a great variety of ways such. as will suggest themselves to those skilled inthe art. The constructions herein set forth are for purposes of illustration andv explanation only and are not intended in any way as a limitation of my invention. What I claimais:

l. A permanent mold for casting bodies having an irregular distribution of their y constituent material, the said mold having walls of ferrous metal with a metallic insert of relatively high thermal conductivity arranged to be engaged by the thick` part of the casting.

2. A composite metal mold "for casting bodies having an irregular distribution of their constituent material, the said mold having its walls made up of different metals having different thermal -conductivities with the metal of higher conductivity arranged toy be engaged by the thicker parts of the casting.

3. A permanent mold for casting bodies of4 low fusing point metal having van irregular distribution of their constituent material, the said mold having walls of ferrous metal with an insert of copper arranged to be engaged by the thick part of the casting.

4. A composite permanent mold having its cavity forming walls formed in partof -ferrous -m'etal and in part of copper.

5. A composite mold for casting bodies having constituent material, the said mold having its walls made up of different -materials having different thermal conductivities with the material of higher conductivityarran ed to be engaged by the thicker parts of t e casting.

6. A mold for casting bodies having an irregular distribution of their constituent material, the said mold having walls formed with a cavity for the casting and with a gate adapted to afford a supply of molten metal in communication with the cavity, the said cavity having a lesser volume at points points more remote from the gate opening than at saidy last named points, and the walls of the mold adjacent the latter-points being formed of material having a higher an irregular distribution of their intermediate thegate opening and other l thermal conductivity than the material forming the walls at the said other points nearer the gate. i l v 7. A composite metal mold for casting bodies having an irregular distributionl of theirl `constituent material, the said mold having walls formed with a cavity for the casting and with a gate adapted to afford a supply of molten metal in communication metal having a higher thermal conductivity with the cavity, the said cavity having a than the metal forming the walls at the lesser volume at points l'ltermediatev the other points Vnearer the gate. 10

gate opening and other points more remote In testimony whereof I have hereunto 5 from the gate opening than^ at Asaid last Vaffixed. my signature.

named points, and the Walls of the mold adjacent the latter points being formed of ZAY JEFF RIES.

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