US1802706A - Car-wheel mold - Google Patents

Description

Apx il 28, 1931. J. c DAVIS 1,802,706

CAR WHEEL MOLD Filed Aug. 20, 1926 Patented Apr. 28, 1931 amp. STATES r Jaime omnrpavrs or cmciaao; rumors? can-warm. Mom);

Application filed August 20, m. Serial no. 'iso,54.

My present invention relates to the art of casting metal, and to improved-means and methods of producing castings which'are not only smooth,'and clean, in that they are free 5 from pits or holes or fromentrained dirt such as sand, dross, slag and the like, but are notably solid and dense vparticularly along" lines of crystallization or solidification of 'iferential character.

Pits, holes, dirt and the like involve rough-' mess, flaking, shelling and a consequent cut- .ting action, since they cannot readily be,

7 machined out, irregularities and otherobvishrinkage of the solidifying metal and where the'portionsare subject to differential co n-i traction, there is'great likelihood of strains, and uneven density, causing consequent unequal strength of the casting and where the casting has a wearing'surface, thereresults uneven wear of the casting.

'Some defects attendantto casting have to pressure headupon the mold at the axial porsome extent been overcome by casting in rotary molds and as regards this general method my prior Patents: 727,103, May 5, 1903; 767,928, Aug. 16, 1904; 1,192,044, July 25 1916; 1,193,670, Aug. '8, 1916; 1,581,790, April 20, 1926; have to a marked degree succeeded in procuring even distribution of the metal in the casting. But these and other processes known to mehave failed in consistently attaining the requisite solidity anddensity in-the castings and insuring a constant run of castings which are both of the solidity and density sought for, but att-he same time free from insuperable peripheral imperfections such as foreignmatter, shelling, irregularities of contour and uneven ness of wear-which are intrinsic and more than merely superficial and so involve actual rejection of the product. j a

In my application Serial Number 46,25 filed July 27, 1925, I have described a new process, apparatus andresultant'product for the manufacture of .wliich vhas so markedly increased the eflicieney of the re-,

sults obtained well nigh perfect.

The invention supplying an ancillar'y'quantity of moulten metal tothecasting, preferably by supply ing sinking heads at the periphery of the castingand I further may'rotate the same casting at the peripheral portions and forcefully feed such ancillary quantity'to the castin While this process is remarkably successful with a melt of certain-degree of purity, ,I found that there is a tendency for an undue minimum amount of compression, due to the.

centrifugal force of rotation or diminished I herein describe, briefly, I involves a new process and apparatus for by the prior practice as to be s at such speeds to forcefully, cohdense the amount of shrinkage at portions having a amount of metal and consequent diminished fluid'pressure head and where the amount of dross, gases or materials of lower specific gravity are -comparativ ely'high in quantity, there is a tendency for the'collection of 'these materials at the axial 'portion'or that portion which forms the hub. of the car wheel; These impurities and gases and this undesirable'low tion,;which is followed by shrinkage in setting, tend to cause a weakness of the metal failure inp'ractice butinvolve an additional; amount of labor in finishing the article to a .-,stage which, in some cases, result intot'al loss 7 for re eetlon thereof, as the article is'fit only and reuse by remelting; V V Where. I-have attempted to overcome this difliculty,'by assisting the rate'of flow ofthe" inetal through the gate by; diminishing any tendency to adhesionto the side walls thereof at the .hub portion due to their collection'at thispoint and consequently not only cause and when pouring the same through the"fit portion of the car wheel, I have found that the centrifugal force of distribution is insufficient to overcomethedefects, particularly at portionsrof the casting where the ready interchange of metal is prevented, due to the shape, of the pouring gateandthe core and also due to the fact that the supply of metal is greater so and remelted at a loss; that I may obtain such from portions of the casting itself rather than from the excess of metal provided at the pouring gate, and also due to the fact thatv .the direct to thebody portions of the casting than paths 'offlow of excess metal are more to the marginal portions andthat upon subsequent setting and shrinkage, the marginal.

more or' less analogous in certain characteristics.

I have found that I can procure substantially perfect castings, particularly car wheel castings, ofunusually dense character whose integrity. is uninterrupted by flaws such as cracks, holes, insufliciencyof metal, sand, dirt, slag and dross, and free from peripheral and marginal imperfections such as foreign matter, gas holes, shelling, irregularities of contour andshrinkage cracks and that I am able tocut down the losses in manufacture, owing to avoidance of production of useless but expensive castings which haveto be broken up castings at higher centrifugal speeds of rocure greater perfection at the tation of the casting apparatus, and also proortions of the casting which have lower momentum, such as the web or hub portion, if the pouring of the metal, particularly at the hub portion,

is accomplished marginally, peripherally, directly, rectilinearly, ultimately a'nd without disturbing the core'usually provided for the hub lit and also if the radial component of force due to rotation is augmented-by ahigher gravitational component by eliminating the factors due to frictional contact of the'metalwith the sides ofthe mold, particularly with thewalls of the pouring gate. I have further found that I may introduce centrifugal force or otherwise an excess supply of the metal at those portions of the casting where substantially vertical or transverse walls increase the frictional contact of the metal to such an extent as to prevent ready radial movement and also at those axial portions having a minimum amount of fluid pressure head where there is a-tendency for loss of metal due to differential setting thereof, by increasing thereadiness of flow of metal to such portions.

I have still mailer found that I as. obtain, in a very simple manner, a fullness of supply of metal at all portions including the 1' ing mold have sufiicient metal, as well as densify the periphery of the entire. casting at.

high speeds of rotation, if the achub and at the 'same time where I use a rotatcomplished at the marginal portions of the hub as theultimate ouring step, and furthermore may obtain orced feed of the excess metal necessary to maintain a completely filled mold conduciveto best casting results, particularly where I use a rotating mold at higher speeds of rotation, by forming the pouring gate with converging walls tending to augment the distribution of the metal by an added gravitational component in an amo t greater than that encountered b fricti nal contact with the walls of the mol particularly the'pourin'g gate, the supply being at the marginal portion of the hub in a direction substantially rectilinear and without disturbing the core ordinarily provided for forming the fit.

'' vention further has for an object M thergof the provision of a mold for. casting, for example, car wheels, which includes pour ing the metal, particularly the hub portion, marginally, ultimately and rectilinearly; the

provision of a mold for'casting car wheels which includes supplying moulten metal to the hub portion thereofsubstantially parallel to the axial line of the casting so that all portions thereof, particularly the marginal portion of the hub, will have a ready supply of excess metal and during setting of the metal all portions will be free from attenuation, avoiding thereby shrinkage cracks as well as the accumulation of undesirable constituents, such as gases, slag, dross and other 1mpur1t1es tendlng to form non-uniform and unsound castings the provision of a method for casting car wheels which includes pouring moulten metal into a mold directly and rectilinearly so that when rotated to obtain the benefit of densification of the metal due to centrifugal force, the gravitational force due to an excess amount of material will be an additive component to the centrifugal force of rotation; the provision of a method for casting car wheels which includes pouring moulten metal into a mold and directly diverting portions of the stream to marginal portions, at which point attenuation during shrinkage is likely to boom.

The invention still further has for an object thereof the provision of a method for casting car wheels which includes introducmg moulten metal into a mold to impart centrlfugal motion to the metal to force it outwardly to the confines of the mold, including provision to supply excess material at all portions of the mold as the densification occurs and ,to compensate at all portions for shrinkage due to attenuation by providing an additional component of force other than that due to thecentrifugal force, particularly at the axial portions where the 'frictional. con-' tact with the walls of the mold would tend to produce hanging of the metal in the mold and result in an insuflicient supply of metal at these portions.

- portions of the body of the casting, the alloying constituents being positioned only at the desired points without restriction due to the configuration of the. mold.

The invention includes as a further object thereof the provision of casting apparatus particularly suitable for forcefully'feeding moulten metal to the mold and where a mold is used having a configuration whichwould normally cause the moulten metal fed thereto to hang or move away from portions of the casting under conditions used for feeding moulten metal thereto, means being provided to overcome any deficiency of metal by sup plying an excess. of metal at' all portions, particularly at the portionsadjacent to the ub and at marginal portions thereof.

The invention includes as a further object thereof the provision of casting apparatus suitable for rotary casting including a. pouring gate and ancillary, means such as a sink ing head for receiving moulten metal for the formation of a casting therein, the pouring gate and the sinking head being formed toc supply metal'in an amount tending to overcome any deficiency due-to" hanging of the metal in contact with the walls of the mold by forming the same so as to include an additional component of force, preferably gravitational, during rotation, the pouring gate and/or the sinking head being formed with walls divergent towards the body of the mold and preferably supplying a quantity of metal to the marginal portions of the hub from the pouring gate.

The inventionstill further includes as an object thereof the provision of a casting apparatus including a core member so asso-- ciated with moulten metal supply means arranged to facilitate the separation of any excess metal normally retained in the metal supply means, said core member further including means to deflect'moulten metal with out disturbing the configuration of said core member at that portion where the stream of metal directly strikes said core.

portion towards the axial portion and which 5 in setting and from the accumulation of for The invention has for another object thereof the provision. of a casting, for example, a car wheel, obta'inedin a rotary casting apparatus and :of uniform progressive variation in' density from the peripheral hassubstiagtially every portion thereof free from defects 'due to attenuation of the metal N eign and objectionable matter, such as gases,

' slag, dross and the like. v

In the attainment of the objects and advantages above set forth, in the avoidanceof the objections and disadvantages mentioned, and in accomplishing certain ends and gaining certain benefits which-will below be pointd out or clearly appear, I have provided the constructions illustrated in the accompanying drawings which for purposes of convenience, as before suggested, are adapted for the production of a car wheel such as one made of steel which-is solid,

dense, hard and resistant and consequently of excellent wearing qualities, at the peripheral or tread portion and may be relatively softer toward the center and therefore more tough and less apt to fracture. In these drawings, it'will be observed that Figure 1 is a side elevation partly in section of a rotary casting apparatus;

Figure 2 is a plan view of the casting taken in the direction of" the arrows shown on line 2-2 of Figure 1. r 1

Figure .3 is a section taken on a line 33 of Figure 2.

Figure 4 is a plan view taken on a line H of Figure 3.

Figure 5 is a plan view of a core member assembly; v

Figure 6 is a side-elevation of member shown in Figure 5.

Referring to theigdrawing it will be observed that I may employ a mold, suchas for a car wheel, which is preferably mounted upon a support 7 which is rotatable by means of a suitable driving mechanism indicated generally at 8. The mold 6 is provided with a pouring spout or funnel 9 having a refractory lininglO for directing into the mold moulten metal from the ladle 11 or the like.

' the core The pouring spout is connected with a pour- I that of the hub portion of the car wheel so that the angular walls 17 are continuous with the walls defining the hub 18. The pouringgaterof truncated-cone shape forms a passage to the main body of the mold about the core member 16 as at the annular portions indicated at 20. Preferably, however, this passageis. divided so as to render the'excess metal usually found in the pouring lgate after the pour has been completed rea 'ly separable and for this reason the core member is provided with flanged portions 21, 22, leaving metal passages therebetween numbered 23, 24. For forming these portions and for deflecting the metal from the core 16 and to revent any disturbance of the core member y contact therewith of the fiowin .metal, I provide a shield portion 25 prefera ly a met a1 plate, formed of a general shape including the flanged portions 21, 22, which serves to offer resistance to the stream of moulten metal as it enters the cavity intermediate the casting mold, preferably adjacent the rim portion. Where I cast a car wheel, near the tread portion thereof I provide ancillary chambers, sinking headsor risers, 26, in the cope 6', which are preferably substantially truncated-cone shaped, that is, they have divergent walls and a-mouth ortion 27 at the base connected with the main body of the mold'during the pouring operation. In the resultant casting, these sinker heads 26, 26 are duly removed during the finishing operation of the casting and before it is put mto use. ing gate is also removed from the main body of'the casting and where I have provided the core member with flanges 21, 22 the removal of this portion of excess metal will be facilitated as attachment of this excess portion to the main body of the mold is with metal which has flowed in the passages 23, 24.

Inthe production of a wheel of uniform composition, I preferably employ moulten steel having a specification of 0.25 to 0.50 per.

cent carbon and 1.25150 2.0 per cent manganese, which may be introduced in the fur nace, though it will be understood my present improvements are available for the pro.- duction of wheels havin varyin composi: tion by graduating the addition 0 the modifying material as can be accomplished readilyby introducing itbetween the ladle and the mold in a manner such as outlined in my aforementioned patents or my application above mentioned. i

The moulten metal is pouredjnto the mold 15 through the pouring gate and as such mold .fills, the ancillary mold cavities 26, 26 are alsofilled. The metal filling in throughout the mold cavity 15 enters the same throu h the passages concentric with the to of t e core'member 16 and where I have divlded this concentric portion the metal enters through the passages 23, 24. m

It will be observed that the metal flows to the casting in a direction substantially parallel to the axial line of the mold and that the metal 'fiowsthereto rectilinearly and directly in an unrestricted manner, the hub portion.

being filled .at its marginal portion, which is the ultimate or final pouring step During the pouring operation, the mold may be rotated but I prefer to rotate the mold after the pouring is completed, the rotation being efiected untilthe casting is solidified. Preferably I include an amount of moulten metal Similarly any excessmetal in the pourneoagoe in the pouring gate in excess of the amount necessary to fill the mold. This excess of metal, particularly where I use hi h speeds of rotation, serves as an additional uid pressure head upon the metal in the mold. This additional component varies as the walls become more divergent with higher speedsof rotation. Where I position the mold as shown this excess metal increases the pressure of the metal on the mold, due to the gravitational component.

From experience I have ascertained that if the mold 15 remains stationary I cannot infallibly attain a degree of solidity and density in the casting desired b me but that by utilizing a rate of rotation 0 say 25 to 100 revolutions per minute, centrifugal motion is imparted to the moulten metal to such an extent that the metal filling the sinker heads 26, 26 serves to completely fill the outermostparts of the mold and the excess metal in the pouring gate additionally serves to densify the metal at the hub portion as it acts upon the marginal portion of the hub at the passages 23, 24.

For certain purposes to further densify the moulten metal in the casting I may impart rotation above the speeds of revolution above mentioned to obtain a highly densified metal wherein the casting is completely filled and I am enabled not only to prevent'the formation of holes and secure a solid and clean casting, free from entrapped gases, loose sand, slag, dross and the like but am also enabled to attain, in addition, complete solidity and marked degree of density at all portions of the casting, particularly at the hub portion, at which point the metal solidifies, free from attenuation or shrinkage 'found that the metal accumulating in the pouring gate 10 will by reason of the sides or wall thereof being angular, characteristic of the sides of a truncated cone, that the component of the centrifu al force and that due v to gravity willforce t e meta], downwardly towards the main body of metal in the mold and thence-outwardl radially. In this way, whatever metal or inarilyb would have a tendency to hang on or rise away from the metal in the main body of the mold, will be forced-into the mold and disengaged from the transverse portions of the mold or those portions offering the greatest amount of frictional contact. I

I have also found that by forming the pouring gate as aforementioned, during retation the metal will not hang or rise away.

from the main body of the metal in the mold and give the deceptive appearance of the .mold being completely full. For this reason.v

I may operate my process at centrifugal speeds not previously available, and obtain densification of the casting in a manner not heretofore attainable, while at the speeds ordinarily used the excess metal in the pouring gate will serve as additional pressure to the main body of moulten metal and act as an additive force during rotation.

It will thus be observed that by this process there will be no attenuation during sobe obtained in accordance with uses to which" the wheel is to be submitted, I may modify my process by including during the pouring step the addition of a modifying element such as manganese of other ingredient havingdesirable properties when alloyed with steel. This modifying element may be added directly to the ladle 11 or,- between the ladle 11 and the mold 15 but for the purpose of introducing and incorporating most perfectly and commingling and distributing most thoroughly the modifying element into the stream of flowing metal, I make use of an ejector 29 and nozzle 30 so that the modifying element may be drawn or otherwise forced into'the flowing stream of moulten metal. 7

By the process as above practiced, added modifying ingredientswill be. positioned at predetermined portionsof the casting in an unrestricted stream and will be fully as effective at the desired points withoutadhering to intermediate portions of the wallsof the mold, in that the passages to themold are rectilinearly disposed and continuous with the walls of the pouring gate. 1

It will thus be observed that-by the combined effects of the pouring gate and the ancillary chamber, a forceful feeding of the metal to the casting will be assured and more forcible as the speeds, of rotation are in-' z'reased. While this process is adaptable for ise with chills in the rim of the mold for orocuring densification with a high degree of iuccess and which I consider within the scope if my invention, the preferred form of my nvention contemplates the omission of chills rials of varying density, that is the entrapped ases, sand dirt, slag, dross and the like may (1' their way to the central portion of the mold, whereas the purified metal will be forced to the confines or periphery of themold. And while I contemplate rotating my mold during the pouring operation, I prefer particularly in the casting of car wheels to first fill .themold and then rotate, having found that in this manner there will be no scouring or displacement of the mold, particularly where a sand mold is used, and in this manner also I obtain the benefits derived by using a mold that is completely filled.

Inasmuch as I preferebaly make use of centrifugal force, the extent to which the benefit thereof is attained obviousy depends.

in part upon the rate of revolution imparted to the mold 15 and in part to the. time interval through which such movement is continued.

It is believed that the operation of my presentinvention and various applications of its use will be understood by those skilled in "the art without further detailed description.

For certain purposes and in certain of its soas to permit the free movement of matephases, it may be employed in connection withstationary molds, in intermittently rotated molds, in continuously rotated molds, and in molds rotated at predetermined times, and equally the modifying material may be introduced at various points or under various conditions, or both, all according to the.

prospective uses of the castings produced.

In theclaims, where I have used the expressions pouring the hub portion marginy, marginal portions of'the hub or marginal portions of the wheel I mean to include by the term marginal the extreme lateral dimensions taken at any point of reference in a horizontal plane and where I make reference to pouring marginally, "it is contemplated that the molten metal flows preferably'from such reference point from the source in a direction towards the extreme peripheral dimensions from the axial line rather than vice versa 7 7 Having thus described my invention and illustrated its use, what-I claim as new and desire to secure by Letters Patent, is

. 1. In a rotary casting apparatus for car wheel castings, a mold provided with a pouring gate, the walls thereof being divergent and continuous with the hub forming portlon of the mold, to supply the metal directly to the marginal portion of the hub'along the walls thereof, whereby when the mold is rotated at or above rotating speeds which would normally cause the metal to hang to the walls of the pouring gate or move away from portions of the casting, the hubforming portion of the mold will be completely supplied with the molten metalto and in-.

cluding the full marginal portions of the I hub.

2. In arotary casting apparatus, at car wheel mold formed with a, pouring gate adapted to supply said casting with excess meta-l at rotating speeds which would normallycause the metal to hangtto the walls or move away from portions of the casting adthe hub forming portion of the mold and having passages continuous therewith to keep said portions completely supplied adj acent the marginal'portions of the hub during rotation at the said rotating speeds.

4. In a rotary casting apparatus, a mold provided witha pouring gate, an ancillary for the formation of the casting-therein, said sinking head and pouring gate being formed with walls divergent towards the main body'of the mold, the pouring gate be.- ing adapted to supply metal gravitationally to all portions of the hub during rotation.

5. In a rotary casting apparatus, a mold provided with a, pouring gate, an ancillary sinking head for receiving moulten metal for the formation of the casting therein, said sinking head and pouring gate being, formed with walls divergent towards the main body of the mold, the pouring gate being arran ed to completely fill all portions of the hub ur i g rotation. f

("In a rotary casting apparatus,'a mold provided with a pouring gate, an ancillary sinking head for receiving moulten metal for theformation of the casting therein, said a sinking head and pouring gate being formed withwalls divergent towards the main body of the mold, the pouring gatebeing arranged to directly and gravitationally supply metal to the hub at the marginal portions thereof durin rotation." I

7. a rotary casting apparatus, a car wheel mold provided with a pouring gate, an interiorly disposed ancillary sinking head closed to the atmosphere for receiving moulten metal for the formation of a casting therein sed near the periphery of the wheel, said sinking head and pouring gate being formed with walls divergent -towards the main body of the mold and formed'of a size relative to eachother and to the main body excess of metal at the marginal sinking head for receiving moulten metal ofthe casting to maintain the mold completelly filled during rotation. H 8.. n a rotary casting apparatus, a car wheel mold provided with a pouring gate, an

interiorly disposed ancillary sinking head closed to the atmosphere for receiving molten metal for the formation of a casting therein disposed near the periphery of the wheel,

said sinking. head and pouring gate being formed with walls divergent towards the main body of. the mold and formed of a size relative to each other and to the main body of the casting to-maintain the mold completely filled during rotation and to maintain an excess at a marginal portion of the hub.'

9. In a, rotary casting apparatus, a car wheel mold provided with a centrally disposed pouring gate, said gate being formed with walls divergent towards the main body of the mold and substantially continuous with the outlines of the Hub forming portion thereof at the maximum divergence and arranged to be of a size relative to the main body of the casting to include a quantit of molten metal to maintain the mold comp etely filled during rotation' and maintain an ortions of the hub free from attenuation o the metal retained in the hub and intermediate tions between the pouring gate, at centri ging speeds.

- 10. For use 111 a rotary casting. apparatus, a car wheel mold including a pouring gate and a hub core member associated therewith,

the pouring gate being divergent towards the hub forming portion of the mold and having substantially continuous outline and direct gravitational connection with said hub forming portion for the flow of metal from thepouring gate .to the hub forming portion, said .hub core member being arranged to facilitate the separation from the body of the casting of the excess metal normally retained in the pouring gate after complete pouring of the casting and comprising'a deflectin plate im mediately above the hub core mem er at that portion where the molten metal directly strikes said core member in flowing from the pouring'gate.

11. Ina rotary casting a pparatusar- 2 ranged to cast car wheels varyin in density and composition between the axlal'portions and the peripheral wearing surface, the comb nation which includes a'rotatable car wheel casting mold, molten metal supply means I therefor including means to intermittently feed alloying ingredients for selectively forming in said casting an alloy steel of predetermined characteristics at predetermmed portions, varying from the composition of the T main body of the casting,a gate associated with said car wheel casting mold formed with walls divergent substantially continuously from the inlet to the hub forming portion of the mold whereby-the metal and the alloying ingredientswill-flow in an unrestricted stream to the predetermined portions of the a casting, free from adherence to the walls of the mold and the gate.

12. For use in a rotary casting apparatus, of a car wheel mold, a tpouring gate and hub core member associate therewith, said hub. core memberbeing arranged to divert molten metal poured through said. gate,through a plurality of passages to the hub 'jorming por? tion' of the mold, the 'centerline'of said passages of the gate being at right angles to p the angle" of repose assumed by. the molten metal inthe main'bodyofthe mold at-cen-Q trifugal speeds of rotation of the casting a'pparatu's. U r

13. A device of the character described comprisingin combination, a car wheel cast-V ingmold mounted for rotation on a vertical axis, and having a metal receiving cavity at the'hub thereofisaid cavity-being. formed to provide the hub of said wheel and extending thereabove with continuous walls" with said hub forming portion, to provide a combined sinking-head and pouring gate said sinkin'ghead and pouring gate having wall portions diverging-fiom top to bottom. 14. A device of the character described comprising in combination, a carwheel cast-'- mold mounted for rotation on a vertical BXIS, and having a metalreceiving cavity at the hub thereoi; saidcavity being formed to provide the hubof said wheel andextendin thereabove with "continuous walls with sai .A hub formin portion; to provide a combined. sinking-hes. and pouring gate said sinking head and pouring gate having w. portions diverging from top to bottom, an .a core'in said hub forming portion of said cavity to form a center opening in said wheel hub.

In testimony whereof, I a have hereunto my 13th day of. August,

" fJA EsloannYl

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