US2085394A - Centrifugal casting - Google Patents

Description

June 29, 1937. f w. D. SARGENT 2,085,394

' GENTRIFUGAL CASTING Filed sept. 9, 1955 2 sheets-sheet' 1 June 29, 1937- w. D. SARGENT CENTRIFUGAL CASTING Filed Sept. 9, 1933 2 Sheets-Sheet 2 31u/enten Patented June 29, 1937 UNITED STATES PATENT QFFICIE'.-

CENTRIFUGAL CASTING William D. Sargent, Newark, N. J., assignmto Dur-afer Incorporated, Newark, N. J., a corporation oi' Delaware Application September 9, 1933, Serial No. 688,831

11 Claims.

ing about a vertical axis.

Cast iron has long been recognized4 as an excellent friction brake material, but due to its inherent weaknesses, lack of strength. vinternal stresses, brittleness, etc., its use for brake drums o has not usually been found practical apart from some form of metallic supporting structure. Ihese composite structures due to severe temperature changes and conditions arising in brake drums, producing unequal expansion and contraction, are not free fro'm dimculties. This-invention is, therefore, particularly directed to an improved composite and the method and apparatus adapted to produce the same.

Accordingly an object of this inventionv is to provide an improved brake drum. having a shell and a centrlfugally cast liner so arranged that separation between the welded liner and shell is mechanically substantially impossible.

Another object of the invention is to provide a 5 brake drum having a shell and cast liner, the shell being deformed along an edge and irremovably nterlocked with the cast liner.

A further object of the invention is to provide in a brake drum, a shell having a bell mouthed edge portion and a cast lining provided with a ange encompassing the bell mouth so as to be rigidly secured to the shell.

A still further object of the invention is to provide a brake drum structure which may be of 5 sucha design as to properly conduct and distribute the heat incident to casting a liner therein.

Yet another object of the invention is to provide a centrifugal lcasting machine adapted to produce the novel drum structure and employ the same in'establishing aJsubstantially permanent mold casting machine.

Still another object of the invention is to pro- 4vide ai annular trough means for receiving molten metal, the trough being so supported and constituted as to be free from overheating from the adjacent molds.

A Vstill further object of the invention is to pro-V vide in a centrifugal casting machine a rotatable annular trough adapted to measure quantities of molten metal when stationary and discharge molten metal therefrom only after a predetermined substantially full speed is attained.

. Another object oi the invention is to provid novel means for supporting a diaphragm member within the centrifugal casting apparatus s0 that quick securing and release is obtained to the end that the casting may be quickly removed from themachine and cooled-in atmosphere or other suitable means.V

so A further object of the invention is to make a (cl. zz-ts) casting welded to a. shell without the necessity of preheating the shell.

lA still further object of the invention is to cast molten iron into a diaphragm 'shell at room temperatures without distortion of the diaphragm of the shell. f

Further objects of the in vention andother novel features will appear more'fully hereinafter from the following detailed Vdescription when taken in conjunction with the accompanying drawings. It

is expressly understood, however, that the drawings are employed for purposes of illustration only.

and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings wherein similar reference characters refer to similar parts throughout the several views:

Fig. 1 is a front elevation of the casting machine with the 'mold and associated elements shown in section;

Fig. 2 is an enlarged section of a portion of Fig. l diagrammatically illustrating the flow of molten metal;

Fig. 3 is a section through a portion of a modiiied mold and finished brake drum; Fig. 4 is a front elevation similar to Fig. l illustrative of the manner of preparing the machine for operation, and

Fig.' 5 is a section through the upper part of the machine of Fig. 4 ,and illustrative of an improved form of holding means for the brake drum diaphragm.

Referring to the drawings and more particularly to Fig. 1 therein, the casting machine comprises a foundation Ill, frame I2 for supporting the upper half of the casting machine and a motor It for supporting the lower part thereof. v

The motor is provided with a shaft I6 carrying thereon a mold supporting spider I8 havinganl annular -rim portion 20 flanged or shouldered as.' at 22 to receive and center a mold section 24.

Pins 26 extending parallel to the axis and adapted to extend into the mold cavity are retained by springs 28 and shoulders 30 so that their inner ends 32v are flush ordinarily with the mold cavity. A nished casting may be ejected by force exerted or applid to the underside of the pins at 34 should such action be desired or necessary. A l

The frame I2 at its-upper end centrally carries a pneumatic lift cylinder 40 having a piston therein swivelly connected to the spider 44 which supports and carries the upper mold section. Details of the piston and cylinder and swivel connector are immaterial in this modification, but may, if desired, be constructed similar to Fig. 5, hereinafter to .be described.

The spider Il is provided with -an annular rim the mold section 60 which is secured in any suitable manner as by bolts 52 to the rim. In order to steady the -shafts supporting the upper and lower mold sections, and guide them into accurate concentric engagement, the lower shaft i6 may y be provided on its end with a socket member 54 i which is adapted to receive the depending end 56 of the upper shaft 42. An annular shoulder 66 on the socket member may be provided to support and center a flanged diaphragm member such as 60 into which a lining is to be centrifugally cast, the shoulder being so arranged :as to secure the diaphragmsnugly between the upper inner face 62 of the upper mold and the shoul.

der 58.

Carried upon the lower shaft I6v is an annular trough 'I0 constructed preferably of refractory material which, asshown, is independently supported from the shaft in a vertically adjustable manner, free from the mold supports, thereby preventing the trough 'from overheating Vdue to heat ow from the mold sections. As shown in Figs. 1 and 2, the annular trough'is carried upon a spider 12, and is provided' with an inner wall 'the corner ifd necessary. y

To provide a vmechanical interlock between the will take place. The curvature of the corner 84 in `the mold is also made of short radius, prefer ably shorter than the radius ,of curvature between the flange and disc4 portion of the dia-` phragm, so that expansion may take place into cast metal and shell or diaphragm which will safeguard the composite construction against contractiony of the liner awayv fromthe shell should the elements be not adequately welded together although such has not been found to occur, the edge of the flange 80 may be bell mouthed as at 8| or otherwise suitably formed' and -extend into the ange forming annular groove 88, whereby cast' metal may completely encircle the flange edge. This construction also aids in the more uniform cooling of the` heavy isection ofthe casting sin'ce the 'ange extends substantially into lthe center thereof.

A particular advantage inherent in the machine is derived from the particular form of the article f manufactured thereby. The use of a flange diaproduction.

` phragm tends to protect the upper mold section.

thereby -permitting the use of a permanent mold material such. as steel or a suitable refractory. The lower mold section while not so well protected may be more or less permanent 'and constructed of steel or any suitable refractory ma-A terial capableof withstanding the stresses of lcentrifugal casting. The extreme simplicity of .the lower mold section and its simple mounting,

it being held lin place by the annular shoulder 22 and by the.,.weigvht of the` upper mold section permits of quickand cheap replacement as often .as necessary without coolingor delaying rapid As shown in Fig. 3, the upper moldv d lsection '60 may be extended by an annular lip r Il having an inner tapered surface Il against which a refractory insert may seat. In this particular modification the refractory insert may b e `of `the sand core vtype because ofthe support rendered to it by the surrounding mold 50 and lip 5| and rim portion 2li. Y

In Fig. 4, the method of preparing the machine when cold is illustrated.' Blocks preferably of refractory` material are placed between the. upper and'lower mold sections and asbestos protection shields are provided at various other points whilev a heating'torch is applied to the mold cavities. As shown, a central block 90,

which may be in segmental' form for easy place-` ment and removal, guards the` inner shaft and Support spiders from the torch. A screen 92 suitably hung upon the annular trough is adapted to protect the lower mold spider and adjacent parts, while a cylindrical shie1d'84 is placed around the mold to prevent loss of heat. The

shield 94 may be vremovably supported on brackets 96 in the manner shown. An aperture 98 therein offers access to theinterior o-f the mold and a suitable torch |00 may be inserted therethrough.

A novel diaphragm holding and ejecting means for use in connection with the machine is illustrated in Figs. 4 and 5 wherein channels lili are shown as terminating in ports ||2 in the upper mold face 62. The inumber of ports may be varied to suit but are preferably arranged at short intervals and all connected to the channel ll'il.-

Referring to Fig. 5, the channels H0 enter into an axial bore |I'3 passing through the shaft IIS, which shaft is rotatably carried in the piston i i4 and piston rod H6. Raising or lowering of the upper mold section is accomplished by admitting compressed air to the lower part of the cylinder from the supply pipe Ill, or exhausting the cylinder into they exhaust connection H9 -of the three-way valve ||8`. Referring again to the ports ||2 and connecting channels H0, the upper end of the cylinder may be provided with a threeway valve |28 adapted to connect the upper'end of the cylinder'either to a source of vacuum |221 or pressure I'I. It will thus readily appear that by application of vacuum, a'diaphragm such as may be securely held Iagainst the under face 62 of the upper mold section by reason of the ports H2, and ejection of the diaphragm may be quickly accomplished by reversing the suction to pressure. Since movement of the-piston in'and out .of the upper portion lof the cylinder may seriously affect the vacuum operation, it- ,may be. Y

desirable to provide a flexible and swivel 'hose connection between the upper'end of shaft l 'i 6 and the valve1|20 in which case the packing |24 maybe dispensed with'. However, in practice it has been found that when the piston rises, vac'- uum used to hold the diaphragm in place is re 'duced tending to initiateejection'whichds de-g sirable at this time.

Referring to Fig. 3 wherein the nished brake drum structure is shown. it will appearY that the castmetal liner |80 is mechanically interlocked over the bell mouth edge 8| in addition to being substantially'welded to the flange Il yof the diaphragm. After casting and cooling, the drum is removed, and the inner skin which includesV the'` v impurities may be machined away so as to produce a high grade internal friction braking surface.' Y

In voperation of the machine, the same is ilrst heated to the operating temperature, preferably while rotating slowly, in the manner described in connection with Fig. 4, this being done to' prevent chilling of the rst castings made. .After heating, the liners 90,' 92 and 94 are removed and an amount of molten metal suiilcient to i'lll the annular trough 1|! to the overflow point is poured thereinto, any excess overflowing into the catch troughs 13. A flanged diaphragm is inserted in the topv mold section and the sections are thereafter brought together by exhausting cylinder 40. Rotation and rapid acceleration is immediately commenced, and after a predetermined speed is attained the metal will flow up over the lip (see Fig. 2) and be discharged with high velocity against the flange 80 heating it to the Vtemperature of the iron and thereafter flow as indicated in Fig. 2 to ll the cavities. The diaphragm when subjected to the heat and impingement expands so as to take up the clearance, and soon after the metalis discharged from `the trough, the molds are rapidly decelerated as byv reversing the current ow in the motor .and supplying a resistance, separated, and the brake drum with its shell and liner both welded and locked removed for uniform normal cooling in atmosphere or in any other'desirable medium.' Acceleration, the running time, and deceleration, infall may take a fraction of a minute. Also the time during which the molten metal must lie in the trough is extremely short, since the acceleration period is short due to the annular construction of the trough whereby the molten metal is rapidly accelerated therewith. This annular shape thereby greatly prolongs the life of the trough. l

There is .thus provided an improved article of manufacture and machine adapted to cooperate therewith .during the process of manufacture whereby rapid manufacture of brake drums and the like at low cost is possible.

Though only one embodiment or modification of the invention has been illustrated and described, it is to be understood that the invention is not limited thereto but may be embodied in various mechanical forms. For example, the size and proportions may be varied at will to suit various conditions, or the mechanical elements thereof may be varied or equivalent substitutions made therefor. As such'and many other changes in construction and arrangement of parts may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art, reference will be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. An insert shell for use in casting a brake drum comprising a drum shaped member having an inturned head portion along one edge,

A and a bell-mouthed portion along the other edge.

2. Arotatable annular trough having an outer annular high lip sloping slightly radially outward toward the top, andan inner lip provided with an overow discharge means for regulating liquid capacity.

3. A centrifugal casting machine, a two-part rotatable mold, means for rotating one of the parts. means for rotatably supporting and raising and lowering the other of the parts into and out of engagement with the first part. and vacuum and pressure ports leading into said mold cavity for securing or releasing a metallic insert in said cavity by 'suction or pressure thereon.

4. In a centrifugal casting machine, a twopart rotatable mold, means for raising or lowering one of the parts and for rotatably supporting the same, ports on the inner surface of said mold, and means including a controlling valve for connecting said ports to a source of fluid vacuum or pressure at will to hold or release a metallic insert adapted to seat over said ports.

5. In a centrifugal casting machine a two-part annular mold, means for rotatingand supporting one of the parts upon a vertical axis, and an annular pouring trough within said mold independently supported and spaced therefrom and adapted for rotation witha part of the rotatable mold.

6. In a centrifugal casting machine, a two-part annular mold, means for rotating and supporting one of the parts upon a vertical axis, a flanged diaphragm adapted to seat in said mold, means adapted to hold said flanged diaphragm in the other of saidparts, and an annular trough within said mold removably 'supported for rotation with and spaced from the rotatable part, said annular trough being adapted to discharge metal upon the flange of said flanged diaphragm during rotation.

'7. A rotatable vertical axis annular trough, an annular mold around said trough, spaced supporting means for rthe mold underneath said trough and discharge means in said trough for regulating the liquid level, said discharge means being located so as tor discharge between the spaced supporting means.

8. In a .vertical axis centrifugal casting machine, an upper' mold section, a lower mold section, said upper mold section having an annular groove facing and partially bounded by the lower mold member, and a removable refractory insert arranged in said groove. f

' 9. In a vertical axis centrifugal casting machine, an upper mold section having an annular groove in the-inner lower edge thereof, a refractory insert removably arranged in said groove,

a lower mold member adapted to engage theA lower edge of said upper mold section and refractory insert andretain the refractory insert in place, and a anged diaphragm member covering the inner exposedv surface ofsaid upper mold section and extending over and adjacent to a portion of the exposed surface of said refractory insert.

10. A centrifugal casting machine, a two-part rotatable mold, means for rotating one of the parts, means for rotatably supporting and raisl ing and lowering the other of the parts into and out of engagement with the rst part, and vacuum ports leading into said mold cavity in a. directionsubstantially parallel with the rotational axis for securing a metallic insert having an inturned head portion in said'cavity by suction on the insert head portion.

11. A centrifugal casting machine, a two-part rotatable mold, means for rotating one part of said mold, means for rotatably supporting and raising and lowering the other part of said mold into and out of engagement with the iirst part, and means movable with one of said parts for centering and securing a metallic insert in the mold, and means on the other of said parts for securing the metallic insert in the mold, independent of said movable means.

WILLIAM nl sARGENT.'

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