US2025301A - Centrifugal molding apparatus - Google Patents

Description

DBC- 24, 1935- l-l. M. NAUGLE ET A1.

CENTRIFUGAL MOLDING APPARATUS giled April 6, 1933 5 Sheets-Sheet l Dec. 24, 1935. H. M. NAUGLE ET AL 2,025,301

CENTRIFUGAL MOLDING APPARATUS Filed April 5, 1933 5 Sheets-Sheet 2 l INVENTORS if H M/Vauyle BY .J Townsend w ATTORNEYS CENTRIFUGAL MOLDING APPARATUS Filed April 6, 1933 5 Sheets-Sheet 5 INVENTORS HMA/mle BY A. J Townsend Patented Dec. `24, 1793.5

UNITED STATES PATENT OFFICE CENTRIFUGAL MOLDING APPARATUS Application April 6, 1933, Serial No. 664,727

12 Claims.

The invention relates to the casting of metal and more particularly to apparatusfor centrifugally molding or casting molten metal on a commercial scale to form preferably steel products`\` such as massive ring blooms, slabs, billets and the like; and this application is a continuation in part of the common subject matter relating toapparatus shown in our copending method and product applications filed, respectively, Septemn ber 18, 1931, Serial No. 563,583, matured in Patent No. 1,908,169, dated May 9, 1933, December 29,

1931, Serial No. 583,658, December 29, 1931, Serial No. 583,659, January 26, 1932, Serial No. 588,945,

matured in Patent No. 1,908,170, dated May 9,

193,3, and May 6, 1933, Serial No. 669,711; and the apparatus shown, described and claimed herein constitutes improvements upon theV apparatus shown in our prior applications filed, respectively,

February 18, 1930, Serial No. 429,359, matured lil in Patent No. 1,903,906, dated April 18, 1933, and

May 17, 1930,- Serial No. 453,311, matured in Patent No. 1,908,168, dated May 9, 1933, and in our prior Patent No- 1,882,516, dated. October 11, 1932.

The centrifugal casting of massive blooms,

f' slabs, billets and the like preferably having cross sectional areas of sixteen square inches and upwards with minimum dimensions of three inches and circumferential lengths of twenty-five feet and upwards directly from molten metal, prefff" erably in accordance with the methods set forth in curcopending applications,` involves the use of centrifugal casting apparatus including an annular mold, a rotor for the mold, a ladle for molten metal, a pouring lbox receiving molten 5 metal from the ladle for pouring into the mold, means for depositing insulation .material upon the inner surface of molten metal poured'into the mold, means for supporting said pouring box and insulating depositing means, and safety means if for the rotor and mold.

It is an object of the present invention to provide apparatus for centrifugally casting massive ring blooms, slabs, billets'and the like, including an annular mold, having separable sections, preferably upper and lower substantially similar sections, and means for attaching and clamping the two separable mold sections together which will not loosen by the action of centrifugal force.

It is likewise an object of the present invention to provide centrifugal casting apparatus with a table or rotor upon which an annular mold, preferably including separable sections, is removably mounted, as by being held in place by its own weight and preferably by engagingl centering means carried by the rotor, to enable easy removal of the mold rfrom the rotor and replacement thereof by other molds; so as to provide for successively placing a series of molds upon the rotor for utilizing one rotor for casting successive quantities of molten metal from one heat. y 5 It is also an object of the present invention to provide centrifugal casting apparatus with an annular mold made of metal in which a substantial mass of metal forms the mold walls and is so located or distributed, with respect to the l0 annular mold cavity formed `by the mold walls, that the cooling of certain regions of' molten metal poured into said mold cavity is accelerated or retarded, as the case maybe, for controlling the rate and progress of cooling and solidication of the molten metal in the mold cavity. Moreover, itiis an object of the present invention to provide centrifugal casting apparatus for carrying out certain of the methods, particularly set forth in our copending application, Serial No. 20

563,583, matured in Patent No. 1,908,169; as by providing a mold having Walls forming an annular mold cavity, and by providing certain portions of said Walls with facings or insets of refractory or insulating material for retarding and 25 controlling the rate and progress of cooling and solidication of molten Vmetal poured into and contained within the mold cavity, to bring the final place of solidication of the molten metal substantially at the inner surface of the ring formed thereby, substantially midway between the upper and lower faces thereof so as to pro'- duce a sound, homogeneous, centrifugally cast ring, bloom, slab, billet and the like free from blow holes, shrinkage cavities, and other similar imperfections. ,Y

Likewise, it is an object of the present invention to provide centrifugal casting apparatus for carrying out certain other methods, particularly set forth in our copending application, Serial No. 563,583, matured in Patent No. 1,908,169; as'byl providing a mold having walls forming an annular mold cavity, and by providing at least that portion of the upper and lower mold walls which extend from the inner .edges of said mold walls to approximatelythe inner surface of the centrifugally -molded ring to be formed in the mold cavity with facings or insets of refractory or insulating material for retarding or delaying the cooling and solidification of molten metal adjacent thereto, to eliminate the formation of objectionable ns and the like at and adjacent to the upper and lower inner annular corners of the cast ring, which ns if formed, would have to be removed prior to rolling, thus incurring extra operations and decreasing yield.

Similarly, it is an object of the present invention to provide centrifugal casting apparatus for carrying out certain other methods, particularly set forth in our copending application, Serial No. 563,583, matured in Patent No. 1,908,169; as by providing a mold having upper, outer and lower walls forming an annular mold cavity, by extending said lower mold wall inward from the mold cavity a substantial distance for receiving molten metal poured thereon to be introduced into the mold cavity, and by providing said lower mold wall and its inwardly extending portion with facings or insets of refractory or insulating material for preventing the cooling and solidification of the molten metal as it is being poured upon the inwardly extending portion of the lower mold wall.

It is a further object of the present invention to provide the rotor or table of centrifugal casting apparatus with a central vertical spindle which is journaled in anti-friction bearings for obtaining a smoothness of operation of the rotor to prevent agitation of the molten metal within a mold .mounted on the rotor during solidif'lcation of the same; and to preferably provide a housing for the bearings in which the spindle is journaled, which also houses rotor driving connections.

Moreover, it is an object of the present invention to provide means for preferably automati- ,cally regulating the retardation of rotation of the rotor of centrifugal casting apparatus after metal introduced into a mold mounted on the rotor has `cooled to a self-sustaining plastic condition, to prevent disintegration of the metal due to inertia. 1

It is a further object of the present invention to provide centrifugal casting apparatus with a pouring ,box which receives molten metal from a ladle and discharges the same to a rotating mold, with a spout or discharge nozzle arranged or located to limit or prevent splashing and dripping.

It is also an object of the present invention-to provide means for depositing or applying a blanket or coating of heat insulating or refractory material, and/or pressure producing material to the inner face of molten metal within a rotating annular mold of centrifugal casting apparatus,

immediately after the molten metal has been` poured therein, forrretarding the cooling and solidification ofthe molten metal throughout theA entire area of the inner face portion ofthe ring until the cooling and solidication of the molten metal has progressed from the outer peripheral portion of the ring inward to the inner face thereof. i.

Similarly, it is a further object of the present invention to provide apparatus for depositing heat insulating or refractory, preferably lcomminuted, material upon the inner face of molten metal poured into a rotating annular mold of centrifugal casting apparatus, immediately after the pouring operation has been completed.

Furthermore, it is an object of the present invention to provide centrifugal castingapparatus with means for mounting the pouring box and i insulating material depositing means in proper and accurate position with respect to the rotating mold; said mounting means being arranged for quick removal of the pouring boxand insulating material depositing means immediately after the pouring operation has been completed, without the possibility of any of the parts striking rotating parts, so as to enable prompt remounted on the ,is journaled at vent cooling strains. 5

Y Moreover, it is an object of the present invention to provide centrifugal casting apparatus with safety means and devices for protecting the operators thereof from injury as by locating moying parts thereof within a compartment substan- 10 tially enclosed byv guards.

And finally, it is an object of the present invention to provide centrifugal casting apparatus in which all of the above desiderata are obtained in an expedient manner which enables the rapid 15 and economic casting of massive ring blooms', slabs, billets and the like which are homogeneous and free from defects throughout.

These and other objects may be obtained bythe apparatus, parts, combinations, devices, ele- 20 ments, arrangements, and means hereinafter described in detail and claimed, preferred embodiments of which are shown in the accompanying drawings, in which:-

Figure l is'an axial section of a preferred form 25 of the improved centrifugal casting apparatus taken as on the line 1-1, Fig. 2;

Fig. 2 is a plan view of the same; and

Fig. 3 is an enlargedv fragmentary section of a portion of the mold and rotor. 30

Similar numerals refer to similar pa throughout the drawings.

The improved centrifugal casting apparatus is preferably mounted upon a primary concrete foundation 4 in which a pit 5 is formed. A 35 flanged annular rotor supporting base 6 is foundation 4 and anchored thereto preferably by anchor means 1; and the base 6 preferably supports a drive and bearing housing generally indicated at 9, preferably com- 40 posed of an upper housing member 9 andv a lower housing member I0.

A combined thrust and radial anti-friction preferably tapered'roller bearing II is preferably mounted at I2 in the upper housing member 45 9, and a combined thrust and radial anti-friction preferably tapered roller bearing I3 is preferably mounted at I4 in the lower `housing member I0.

A vertical spindle I5, provided with ra flange I5,

I1 and I9, respectively, in the 50 bearings II and I3, and a bearing retaining disk I 9 is preferably mounted on the end of the spindle I5 engaging the cone o f the bearing I3. A bearing lubricant retaining plate 2l is preferably bolted to the lower housing member III at '2| to 55 enclose the bearing I3 and the lower end of the spindle I5; and lubricant seals 22 and 23 are preferably provided for the bearing Il between the upper housingmember 9 and the spindlel l5.

A bevel gear 24 is mounted on the spindle I5 6o within the housing 9, and the gear 24 is driven by a bevel pinion 25, which is located within the housing 8 through an opening 23 provided in a wall of the lower housing member I0. The pinion 25 is mounted on one end of a shaft 21 which 65 is journaled in bearings 29 and 29, and a gear 30 is mounted on the other end of the shaft 21 within a gear housing 3l. A pinion 32, mounted on the motor shaft of the rotor drive motor 33, which is supported at 34 on the primary founda- 70 tion 4, drives the gear 33.

flanger I6. The table 35 is preferably provided with a fiat annular surface 38, and a removable guard plate 39 preferably extends inward from the fiat annular table top surface 38 to the hub portion 36 thereof for enclosing the bolts 31. A cover plate 48 bolted to the spindle is also preferably provided for the upper end of the spindle I5.

Centering means, which may either be blocks or an annular ring 4|, is preferably provided by welding the s'ame at 42'to the rotorI or table 35 for mounting and centering the annular mold, generally indicated at 43 (Fig. 3) on' the rotor. The improved mold 43 preferably includes sepf arable halves or sections 44 and 45 having therebetween a substantially horizontal joint 46 with an offset 41 therein, substantiallyin the median plane of the mold; and abutting flanges 48 and 49 are provided on the mold sections 44 and 45, which are detachably clamped, joined, or secured together by means such as pins 58, which engage the lower mold section 44 and pass through the abutting fianges 48 and 49. and by wedge pins which engage the pins 59 and the upper mold section 45. l

The mold sections 44 and 45 comprise the upper metal mold wall 52, the outer metal mold wall 53 and the lower metal mold wall 54, which form an annular inwardly opening trapezoidal mold cavity 55 suitably shaped to give the desired section to a massive ring, preferably with the upper and lower wall mold cavity surfaces slightlyl tapered outward toward each other, and with rounded corners between the upper, lower and side wall mold cavity surfaces, as shown.

Moreover, there is a substantial mass of metal in the outer `metal mold wall 53, the upper metal mold wall 52, and the lower metal mcldwall 54; and there is a substantially greater mass of metal in the outer metal mold. wall 53 than ineither the upper metal mold wall 52 or the lower metal -mold wall 54; and the total mass of metal in the said mold walls 52, 53 and 54 is preferably greater than the mass of metal in the ring to be formed in the mold cavity 55, for a purpose which will be hereinafter described.

The lower mold wall 54 is preferably extended radially inward a substantial distance by an annular plate section 56 rabbeted at the joint 51 to and supported on the lower mold section 44, and the inner annular surface of the plate 56 may preferably be tapered as at 58 for wedge engagement with the centering ring 4|.

The mold 43 which is removably mounted on the rotor 35, may be quickly raised, together With the annular plate 56 and removed from the rotor table 35 by any suitable crane tackle (not shown), which may engage the flange 59 so that successive molds may be successively placed on the rotor; and upon release of the pins 58 and 5|, the upper mold section 45 may be removed from the lower mold section 44 by suitable crane tackle (not shown), which may engage the flange 59.

The upper and lower mold walls 52 and 54 are preferably provided withdovetailed annular channels or recesses 60, and annular insets or 52 and 54; and the-plate 56 is also preferably provided with a dovetailed annular channel or recess 62 in which is dovetailed an annular inset, facing or ring of heat insulating refractory material 63. The refractory material rings 6| and 63 may be made of a series of arcuate nre bricks dovetailed into the channels and secured therein by fire clay cement 64, and the upper surface of the ring 63 is preferably slightly tapered to be substantially parallel with the mold cavity surface of the upper mold wall 52.

A secondary concrete foundation 65 preferably substantially encloses the rotor and mounting therefor, together with the mold carried thereby, by forming a compartment 66 in which the rotor is located; and a plurality of overhanging arcuate guard plate brackets 61 are preferably anchored to the foundation 65, at 68, to form a circular working floor above the rotor with a central opening 69 therethrough slightly larger than the outside dimensionsV of the mold 43.

The motor 33 and gear housing 3| are preferably located in a compartment 69 formed' by walls provided with a cover plate 1| and the compartment 69 is preferably separated from the compartment 66 by a guard vplate 12 extending between the walls 18. Likewise, the compartmentl 66 is separated from the pit 5 by a guard plate 13, which protects the shat 21 and bearings 28 and 29 therefor.

Saddle boxes 14 are preferably mounted at 15 on the overhanging brackets 61'at fdiametrically spaced portions of the opening 69 formed thereby; and each saddle box 14 preferably includes an end wall 16 and side walls 11.

I-beams 18, secured together in spaced relation by spacers 19, form a bridge generally indicated at 80, which may be removably supported or suspended at its end portions in the saddle boxes 14; and the bridge 88 is provided with a suitable I- frame 8| with which suitable crane tackle may be engaged for hoisting the bridge 80 to remove the same from its location above the rotor.

A refractory lined pouring box 82, provided with a flared mouth 83, a well 84 and a spout having an orifice 85 therein, is mounted on the bridge 80 above the mold 43 with the spout located adjacent to the mold 43; and a cartridge chute 86, prodischarge end 88 cut away at 88a adjacent to the mold 43 is also suspended or mounted on the bridge 88 above the mold 43 for holding a prefer'- ably cartridge charge 89 of preferably comminuted refractory material.. The refractory material 'charge 89 is preferably confined in measured amounts within a paper or fabric container and held within the cartridge chute by a bell crank stop 98 pivoted at 9| to the chute 86, and maintained in position by a trigger 92 which may be operated to discharge the material by releasing the cartridge 89 by a pull line 93 leading to the operators station.

In utilizing the improved centrifugal casting apparatus. for centrifuga-Hy casting molten metal to form massive ring blooms, slabs, billets and the like, raw materials, consisting preferably of scrap metal and other necessary or desired refining and/or alloying materials are melted and refined preferably in an eectric furnace. When the molten metal has the desired chemical characteristics and has a temperature materially above 2600 F., the same is tapped intol the ladle 94 wherein it is carried to a position over the centrifugal casting appartus, as shown in Fig. 1, and is there tapped into the pouring box v82, whence it flows into the annular mold cavity 55 of the rotating mold 43 wherein upon solidication, a massive ring bloom A is formed as shown particularly in Fig. 3.

Immediately after the molten metal has been vided with a ared receiving end 81 and an open v heat insulating refractory preferably comminuted material is preferably deposited on the inner face of the molten metal contained within the mold cavity 55 by releasing the cartridge charge of the Same indicated at 89 which is held in the cartridge chute 86, so that the comminuted material will l spread to form a blanket or coating indicated by dotted lines at B in Fig. 3, upon the inner face of the molten metal. As soon as the molten metal has cooled to a selfsustaining plastic condition to form a ring A,

the ring A may be removed from the mold. This may be accomplished by promptly removing the ladle 94 with a crane, after the pouring operation has been completed, and then picking up the bridge by engaging the I-frame 8l with a crane hook to remove the bridge, and the pouring box 82 and depositing means 86 carried thereby, from above the rotating mold.

Meanwhile, when the molten metal within the mold cavity 55 cools to a self-sustaining plastic condition, the speed of rotation of the rotor 35 is preferably automatically retarded by suitable control means, indicated diagrammatically at 91, which may preferably include accelerating switches, dynamic braking contactors, and positively driven contact making means for automatically regulating the sequence and periods of the operation of the same; for retarding the speed of the motor 33 and the rotor 35, so as to permit the ring A to shrink without disintegration or rupture due to inertia and for bringing the rotor 35 to rest at the proper time. Thereafter, crane means are engaged under the moldflange 59 to remove the mold 43 from the rotor 35, whereupon an empty mold may be placed upon the rotor and another casting operation may be performed.

'I'he mold 43 is preferably removed to a stripping table where the pins 50 and'5l are released followed by a removal of the upper mold section 45. The massive ring bloom A may then be stripped from the lower mold section 54 and transferred preferably to a circular roller table where the same may be severed by a hot saw or shear to form one or more arcuate blooms which may be subsequently straightened and rolled to form semi-finished or finished rolled steel products in accordance with the method set forth in our copending application, Serial No. 603,764, matured in Patent No. 1,908,171, dated May 9, 1933.

The use of the pins 50 and wedge pins 5| provide means for clamping the mold sections 44 and 45 together, which clamping means cannot loosen by the action of centrifugal force during rotation of the rotor to permit the mold sections to spread during a pouring operation; and the'said clamping means is readily releasable and removable for stripping a molded ring A from the mold 43.

The loose mounting of mold 43 on the rotor 35, by its being held in place by its own Weight, by having its sections joined together independently of the rotor, and by engaging the centering means 4| provided on the rotor 43, provides for ease of removal and replacement of molds 43, thus making possible the casting of succeeding parts of a heat on vthe same rotor equipment.

The location of a substantial mass of metal in the outer metal mold wall 53, and the upper and lower metal mold walls 52 and 54, and the location of a substantially greater mass of metal in the outer mold wall 53 than in either the upper orA the lower mold walls 52 and 54 because of the recesses 60 in said walls 52 and 54 provides for great heat absorptionand dissipation particwalls 52 and 54, to accelerate the cooling and solidiiication of molten metal from which the outer peripheral portions of the ring A is formed, so that the solidif'ication of the molten metal forming the ring A initiates at the outer portions of the ring and progresses from the outer portions thereof to the inner portions thereof.

The use of the annular insets of refractory material 6l in the upper and lower metal mold walls 52 and 54 retards the rate and progress of cooling and solidiiieation ofthe molten metal at and adjacent to the upper and lower inner annular corners of the ring A, which aids in bringing the final placev of solidication of the molten metal substantially at the inner surface of the ring A and substantially midway vbetween the upper and lower 'faces thereof.

Moreover, so long as the annular insets of refractory material 6I extend at least from the inner edges 95 of the upper and lower mold walls 52 and 54 to approximately the inner surface 96 of the centrifugally molded ring to be formed in the mold cavity, objectionable fins do not form at and adjacent to the upper andy lower inner annular corners of the ring A, which fins -if formed, must be removed prior to rolling, thus incurring extra operations and decreasing yield.

terial 63 as a facing for the annular plate 56 prevents a. chilling, cooling or solidication of the molten metaly as it is being poured from the pouring box into the mold cavity 55, when the molten metal being poured is received upon the upper surface of the refractory ring 63; and this control of the cooling of the molten metal prevents solidication of molten metal outside of the mold cavity before it is thrown by `centrifugal force into the mold cavity, which would be objectionable.

Likewise, the use of the cartridge chute 86 as a means for distributing a blanket or coating of heat insulating or refractory material B and/or pressure producing material, upon the inner face of molten metal contained within the mold cavity 55 immediately after the molten metal has been poured therein, enables the cooling and solidication of the molten metal throughout the entire area of the inner face portion of the ring to be retarded until the cooling and solidification of the molten metal has progressed from the outer peripheral portion of the ring AI inward to the inner face 96 thereof.

These various means for controlling the cooling and solidification of the molten metal so as to bring the final point of solidiiication substantially at the inner surface 96 of the ring A, substantially midway between the upper and lower vertical spindle journaled in anti-friction bearings prevents agitation of the molten metal within the rotating mold as the same ls'being subjected to the action of centrifugal force, so that the beneficial effects of pressure acting upon the molten Ametal during rapid cooling and solidification produces sound, homogeneous castings fren from blow holes, shrinkage cavities, dendritic segregation, and the like.

'I'he provision of means for regulating the retardation of rotation of the rotor after the ring A has cooled to a self-sustaining plastic condiltion, enables the speed of the rotor to be controlled so as to prevent disintegration or rupture of the metal due to inertia and to permit certain methods set forth in our Patent No. 1,882,516 to be carried out.

Thel use of the pouring box 82, having a well 84, and an oriflce 85 in the discharge nozzle thereof, together with the location of the discharge nozzle substantially as shown in the drawings, enables a pouring operation to be carried out without a dripping or splashing of the molten metal.

The use of the saddle boxes "M, and the bridge upon which the pouring box 82 and cartridge chute 86 are mounted, enables the pouringbox spout and the discharge mouth of the cartridge (.hute to be accurately located with reference to the mold. Moreover, the end wall 16 and side walls 11 of the saddle boxes engage the ends o-f the bridge 80 in such a way that in placing the bridge over or withdrawing the bridgefrom the rotor, the pouring box spout and cartridge chute discharge end are guided clear of the mold, thus eliminating any possibility of the same striking the mold. Such an arrangement makes it possible to remove the bridge 8f) from above the rotating mold before the mold has been brought to rest, which therefore facilitates the ultimate vstripping of the ring A from the mold 43.

The location of the rotating parts within the compartments 5, 66, and 69, all of which are substantially enclosed by guards, protects the operators of the centrifugal casting apparatus from injury.

Accordingly, the improved centrifugal casting apparatus may be used for making the improved product set forth in our copending application, Serial No. 669,711, preferably in accordance with the method set forth in our copending application, Serial No. 453,311, matured in Patent No. 1,908,168.

We claimz- 1., In centrifugal casting apparatus, an annular mold comprising upper, outer and lower metal mold walls having mold cavity surfaces forming an annular inwardly opening mold cavity, said upper and lower mold walls being provided with annular recesses, and there being annular insets of refractory material in said annular recesses having surfaces coextensive with the mold cavity surfaces of said upper and lower metal moldwalls.

2. In centrifugal casting apparatus, an annular mold comprising upper, outer and lower metal mold walls having mold cavity surfaces forming an annular inwardly opening mold cavity, rsaid upper and lower mold walls being provided with dovetailed annular recesses, and there being annular insets of refractory material in said dovetailed recesses having surfaces lcoextensive with the mold cavity surfaces of said upper and lower metal mold walls.

3. In centrifugal casting apparatus, an annular mold comprising upper, outer and lower metal mold walls having mold cavity surfaces forming an annular inwardly opening mold cavity, there being annular recesses provided in said upper and lower metal mold walls extending from the inner edges of said mold walls to approximately the inner surface of the centrifugally molded ring to be formed in the mold cavity, and there being annular insets of refractory material in said anvrotating the rotor,and a cartridge chute adjametal mold walls.

4. In centrifugal casting apparatus, an annular mold comprising upper, outer'and lower metal 5 mold walls forming an annular inwardly opening mold cavity, said lower mold wall being extended inward a substantial distance from said mold cavity for receiving molten metal to be introduced into the mold cavity, and said inwardly extending 10 portion of said lower mold wall being provided with a facing of refractory material.

5. In centrifugal casting apparatus, an annular mold comprising upper, outer and lower annular metal mold walls having mold cavity surfaces 15 forming an annular inwardly opening mold cavity, an annular plate extending inward a substantial distance from said mold cavity for receiving molten metal to be introduced into the mold cavity, said upper and lower mold walls 20 and said annular plate each being provided with vided with annular recesses, there being annular insets of refractory material in said annular re- 30 cesses having surfaces coextensive with the mold cavity surfaces of said upper and'lower metal mold walls, said upper and lower mold cavity surfaces and the refractory material surfaces c0- extensive therewith being tapered outward to'- 35 ward each other, an annular plate extending inward from said lower mold wall asubstan'tial distance from said mold cavity for receiving molten metal to be introduced into the mold cavity, said annular plate being provided with an annular 40 recess, and an annular inset of refractorymaterial in said annular recess having a surface substantially parallel with the upper mold cavity surface.

7. In centrifugal casting apparatus, a rotor 45 minuted refractory material adjacent to the mold,

and means for discharging said comminuted material into the mold cavity. 60 9. In centrifugal casting apparatus, a rotor, an annular mold comprising walls formingan annular inwardly opening mold cavity, means for cent to the mold provided wana receiving end, 65 an open discharge end and means for holding a cartridge charge of comminuted material in said chute and for discharging the same into the mold cavity. v 70 10. In centrifugal casting apparatus, a rotor mounted for rotation on a vertical axis, an annular mold mountedon the rotor, means for rotating the rotor, a pouring box located above the mold for discharging molten metal into the mold, r insulation material depositing means located o above the mold, for discharging refractory material into the mold, and mounting means for said pouring .box and insulating material depositing means removably suspended above the mold.

11. In centrifugal casting apparatus, a rotor, an annular mold mounted on the rotor, means for rotating the rotor, a bridge, means for removably supporting the bridge above the mold, a pouring box mounted on the bridge having a discharge nozzle normally located adjacent to said mold for discharging molten metal into the mold, and means mounted on said bridge having a discharge end normally located adjacent to said mold for supporting andA discharging refractory material into the mold.

12. Centrifugal casting apparatus, including a rotor, a central vertical spindle for said rotor, a rotor supporting base, anti-friction bearings mounted on said base, said spindle being journaled in said bearings, means for rotating said spindle, means for regulating retardation of rotation of the rotor, centering means on the rotor, an annular mold comprising separable sections forming an annular inwardly opening mold cavity, means for clamping themold sections together including pins engaging one of the mold sections and wedge pins engaging said other mold section and said pins, a third section inwardly extending from and rabbeted to one of said sections, a surface of said third section engaging said centering means, said st two mentioned sections forming upper, outer and lower metal mold walls, said outer, upper and lower mold walls comprising a substantial mass of metal, said mold sections and said third section each being provided l with annular recesses, there being annular insets of refractory material in said annular recesses, a

bridge, means for removably supporting the bridge above the mold, a pouring vbox mounted on the bridge above the mold, means mounted on the bridge above the mold for discharging heat insulating material into the mold cavity, and guard means forming a compartment substantially enzo closing said rotor and mold.

HARRY M. NAUGLE. ARTHUR J. TOWNSEND.

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