US1592823A - Casting metal alloys - Google Patents

Description

July 20 1926.

CASTINGMETAL ALLOYS Filed Jan. 2, 1925 Patented July 20, 1926; n

* UNITED STATES PATENT OFFICE.

CASTING METAL ALLOYS.

Application led January 2,- 1925. Serial No. 198.'

Our invention relates tothe production,

alloys or mixtures ofvmetals by castin of which have a tendency to become segregated or disassociated when cooling -in the mold,

' ,5 such, for example, as copper and lead used in the manufacture of bearings,ant1friction bushings, packing rings, and the like, and

one of the primary ob]ects of they invention is to provide a novel method of casting ario ticles of` this sort whereby the character of the same is improved, particularly for anti-friction purposes, by making the alloy more uniform and homogeneous, through prevention of segregation and by more complete freedom from abrasivev impurities and from gas bubbles and other imperfections.

A further object is to provide certain novel apparatuses for carrying out the improved method.

A further object is to provide, as a new article of manufacture, anti-friction metal castings havin the hereinafter described advantageous c aracteristics.

The invention is illustratedin the accompanying drawings, wherein- Fig. 1 is a sectional perspective view` of the metallic mold forming part of a molding apparatus for the manufacture of i eomotive piston rod packing rings. n'

Fig. 2 is a view, in perspective, of the sand cope of this apparatus.

Fig. 3 is a similar view of the metallic` t I. sons which will appear, it is core.

Fig. 4 is a vertical sectional'view of the molding apparatus, the separate lparts of which are shown in Figs. 1, 2 and 3, with said parts in assembled relation and the metal poured.

Fig. 5 is a sectional perspective of. the

acking ring cast in the apparatus shown in igs. l to 4 inclusive before'the `sprues have been removed. Fig. 6 is a view, insectional perspective, of the metallic mold element of another form of apparatus for casting. packing rings or the like. f

Fig. 7 is a vertical sectional view of the assembled apparatus` withthe metal poured.

Fig. 8 is a sectional perspective of the packing ring casting iii the apparatus of Figs. 6 and 7 before the sprue has been removed.

Fig. 9 is a view, in perspective,'of a metallic mold element for apparatus for casting cylindrical bushings.

the pouring gate or `than the .metal iii kthe` mold cavity,

Fig. l0 is la sectional perspective. of the copefor this apparatus.

Fig. 11 is a vertical sectional view 'of the` assembled apparatus.

Fig. l2 is a sectional perspective of the base member of the apparatus, and

Fig. 13 is a plan View of the collapsible metal core forming part of the apparatus of Figs. 9 to 12. y y l Y For packing the piston rods of steam engines operate by superlieated steam, it has een found necessary to provide packing rings which will stand higher tempera-tures than the babbitt'customarily used with engines operated by .saturated steam.

The packing rings should be made of anti friction metal or metals and an alloy of copper and lead has been found suitable for the purpose except that when the rings are cast in sand molds the cooling is so slow that there is a tendency for the metals to become segregated or disassociated, the reason being, probably, that fused copper and lead form a yphysical mixture rather-thaman alloy in the strict sense of the word. Moreover, the sand is likely to be washed into theV casting forming slag, undesirable Vbecause .of its 'abrasive character, and gas holes in the castle have found that while it is not practical (at least in the manufacture of cored castings) to use an all metal mold, for reapossible to efprevent the segregation-of the ingredient metals by using a composite mold comprisingy metal mold and core elements between which the mold cavity is formed, and cope in which the pouring gates-are fectually arranged which is formed of molders sand.

Vlien the'k fused metal mixture reaches the mold cavity it cools so rapidly that disasysociation of the ingredient metals is prevented. At the same time there is considerable shrinkage, but to providel metal to fill the' cavity when this shrinkage takes place,

gates are filled or partially filled during the-pouring operation `and asV this excess met-al in the gates is in contact with sand, it cools much more` slowly and will remain sufficiently fluent so asto flow down into themold cavity to make up for shrinkage. If the `cope were of metal the .pouring gate would be likely to` `freeze so as to make this operati Jn impossible. -Whle the :amount of metal necessary for making 4up for shrinkage may be small the volume in the-gates should be large enough to insure against too rapid cooling. If an all-metal mold is emploved it will be necessary to maintain theiuidity of the metal in the pouring gates by some other means, for -example, by pressure as in die casting. In order to prevent adherence of the casting to the metallic core it is desirable, and in most cases necessary, to remove the core from the Fahrenheit in order that the lead may not 4 sweat out. The casting in either case is allowed to remain in finally set.y

Referring to Figs. l to 5 inclusive, 25

designates an annular cast iron mold elethe mold. until it' has ment forme'd, preferably, with a taperedv opening 26 and recessed at 27 to provide, with the cast iron core 28, a cavity to receive vthe molten metali This cavity, in the form `of theapparatus shown in Figs. 1 to 4 the conical surface, however, not extending quite to 'the inner edge of the mold element core 28 is tapered to fit the tapered openso that this edge of the packing ring, indicated at 30, is blunt as shown at 31. The

ing 26 in member 25- and in assembling the parts .the upper edge' of the core is flush with the upper edge of element 25; The

mold cavity is covered by a green sand cope 32 formed withapouring opening and a riser designated 33 and 34. The metal oured into the mold cavity through one. o these openings will, of course, rise in the other to the extent of excess of metal over that necessary to ll the cavity. The metal in the cavity chills rapidly and shrinks. The metal in openings33, 34 cools 'much more slowly so that it will remain fluent and will flow into the cavity to'make u for the shrinkage of the metal therein.- s soon as the metal has hardened but before it has taken its final set, the cope is removed and the metal core is knocked out. When the casting has set it is removed. from the mold element 25, after which the sprucs 35 36 are cut off and the surfacesgof the ring finished as may be necessary. We have found that there is little or no Washing ofthe sand o f lmingling of sand with metal took place, with rom the cope' into the casting. The interthe old' method of sand. molding, largely when the hot metal struck the sand bottom of the mold cavity, The sand cope-permits the ready escape of gases from the mold cavity. If desired the castingmay be gated to direct impingement of the molten metal against the wall of the mold.

The preferred-ingredients for a packing ring to be used as indicated, are as follows: 35%l to 40% copper, 3% to 5% nickel,the balancelead. The nickel gives a more intimate amalgamation of the other metals. Preferably we use a flux consisting of phosphor copper v(85% copper and 15% -phosphorous). This ux is used in quantities of from 1 to 4 ounces per 100 pounds of metal.

It acts as a dioxidizer so. that the metal flows more freely.

The same method may be used for casting any unstabley mixture of metals, such, forexample, as a mixture of 68% copper, 25% lead and 7% tin.

In Figs. 6, 7 and 8 wehave illustratedla modified, and in some respects more desirable method of casting' the .same sort of packing ring or other like article. In this apparatus the cast iron mold element 37 is arranged, in a position inverted with respectvl to that of .element 25, upon an iron base plate 38. The metallic core 39 is annular in form but externally tapered as is core 28. Within the metal core 39 is a dry sand a core 40-which is formed with a pouring gate converges downwardly as lndicated at 29,.

41 and projects up through :the green sand cope 42. An orifice 43 through the sand and metal cores leads to the mold cavity 44. The mold element 37 is formed with a plurality of gas orifices 45 to allow escape of gas from the mold cavity into the green sand of the cope. This lform of casting ap aratus has the. advantage that the wide end 45`of the packing ring 47 (Fig. 8) has a relatively smooth surface requiring but little finishing. Vvrhatever slag there may be in the metal collects in the tapered end of the ring from which it may be removed by a simplified machining operation. When the castin' has sufficiently set the cope 42 is remove and the mold 37, core 39 and the casting are inverted and the core knocked out of the mold element 37 from which the casting may then be removed and its sprue 48 cut pif.

In Figs. 1 0 to 12, I have shown apparatus for casting the1 cylindrical bushing designated 49. A suitable alloy for an anti- Irietion bushing of this sort consists of copper, 5% tin and 25% lead. These metals tend to segregate when cast in sand. The molding apparatus comprises separable metallic mold members 51, 52 adapted to be secured together by bolts 53, a metal base .and l'adapted to alignv with the mold cav ity between mold elements 51, 52 and the core. The core is madel preferably'in three parts 56, 57, 58, as shown in Fi 18,' part 58 being a Wedge which can be readily knocked out when the corel is to be removed. For this purpose the core sections V are formed with recesses 62 for a chisel. The core is removed while the casting is hot. After the casting is set it may be removed from the mold. The embodiment of the invention disclosed in Figs. 10 to 12 is not claimed in its specic details in this application as it forms part of the subject matter of any application by us, Serial No. 111,993, filed May 27, 1926 as a continuation in part of this` application. p

It will be understood that the apparatuses and methods described are, so far as details are concerned,.merely illustrative of the principles of our invention Which4 We propose to claim as broadly as the state of the art will Warrant.

We claim:

1. Molding apparatus for casting metal through,

' ing alloys of the character described, comprising, in combination, a metallic mold element having a tapered opening therein, a tapered metallic core to fit into said opening, and a sand element formed with a pouring gate leading to the cavity between said mold element and core.

2. Molding apparatus for casting metal alloys of the character described, comprising, in combination, an annular metallic mold element, the opening through which is tapered, a tapered metallic core to fit into said opening, and a sand cope provided with a pouring gate leading to the mold cavity.

3. Molding apparatus :for casting metal alloys of the character described, comprising, in combination, an annular metallic mold element having an opening therea metallic core to fit into said openand '1 sand cope provided with a pourgate leading to the mold cavity.

WiLiiniivi H. onori?. ROBERT JTSHOEMAKER.

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