US2123037A - Centrifugal casting machine - Google Patents

Description

July 5, 193., F. G. CARRINGTON 2,123,037

CENTRIFUGAL CASTING MACHINE Filed June 7, 1937 sheets-sheet 1 a U u 5S i f S w1 i 1 I 1 .1 l j L Q 1 Q i I b--Q v 14 S l r L l w+ g Q @NI K n fune/4%?.- Fran/z; 6 czmvzgm July 5, 1938. F. G. cARRlNGToN 2,123,037

CEIlTl'IFUGALy CASTING MACHINE Filed June 7, 1957 2 Sheets-Sheet 2 Patented July- 5, 1938 UNITED STATES PATENT OFFICE CENTRIFUGAL CASTING MACHINE l Frank G. Carrington, Anniston, Ala.

Application June 7, 1937, Serial No. 146,864 1o claims. (ci. zz-ss) The present invention relates to improved cenf trifugal casting equipment of the type having an exteriorly cooled mold rotatably mounted in a carriage which is telescopically Vmovable with 5 respect to an end pouring trough. Equipment of this type is widely used inthe production of cast iron pipe and the like.

A principal object of the invention is the provision of centrifugal casting apparatus of the l type described in which the rotatable mold is provided with a cooling jacket having improved intermediate mold-supporting means positioned to allow passage of cooling water about the mold Vand a centrifugally actuated cooling system for l circulating water about the mold and supporting means suliiciently rapid to provide a relatively small difference in temperature at the ends of the mold. 4

An additional object is to provide a centrifugal casting device having a mold and an outer jacket carrying intermediate mold-supporting means which will allow for thermal expansion of the mold without permitting the mold to sag.

' Another object of the invention is to provide improved mold-supporting means including spaced anchor memberscarrying therebetween .spring bars provided with radial mold-supporting bars, the 'spring bars being tensioned to'allow for thermal expansion ofthe mold without per` mittlng the mold to sag.

Still another object of the invention is the provision of an improved cooling system for centrifugal casting machines.

A further object ls to provide a cooling system for a centrifugal casting machine, in which i water is circulated through a rotating mold-cooling chamber 'and non-'rotating end jackets by centrifugal force and at a rate sulcientl to provide a relatively low difference in temperature at the opposite ends of the mold. v

These and other objects will be evident upon a consideration of the following specicationand by reference to the accompanying drawings, in

which Fig. 1 is a longitudinal sectional view of a centrifugal casting' machine constructed in accordance with my invention;

Fig. 2 is a bottom view of the machine shown in Fig. 1; l Fig. 3 is a view of the machine shown in Fig.

2 taken from the bell end thereof;

Fig. 4 is a sectional view taken along line 4-ll of Fig. 1;

Fig. 5 is a sectional view taken along line 5--5 Fig. 6 is a sectional view taken along line 6-6 of Fig. l; and v y Fig. '7 is a sectional View taken along line 1.-1 of Fig. l1. l

In centrifugal casting machines for producing 5 pipe, molten metal is poured from the end of an extended trough into a rotating mold which is progressively moved from telescopic relation with respect to the pouring trough; A mold of this type is indicated at I0 in the drawings. 10

At one end the mold IB is of bell shape to form the enlarged overftting end of the pipe to be cast, and an end core II is removably fitted into -the bell end of the mold during the casting operation. After the pipe has been cast and with- 15 drawn this core is removed in the usual manner.

The bell nd of the mold has a flange I2 on its outside and the opposite end of the mold is provided with an enlarged cylindrical flange `I3. The pouring spout (not shown) extends through 20 ange I3 intothe interior of lthe mold and the latter is reciprocally movable with respect to the pouring spout, as will be described.

To the flange I2 is'flxed bymeans of screws one end of a mold jacket I4. This jacket ex- 25' contact with the exterior of the mold. Two series of supporting members are shown in the drawings. As shown in Figs. l and 5,.each of the 40 supporting structures consists of spaced screwthreaded anchor members I5.` A steel spring bar I6 is secured to anchor members I5 by suitable nuts Il and I8. Depending from the inner side of spring bar I6 is a radial mold-supporting 45 standard I9 which passes through the mold jacket I 4 and bears against the outer surface of the mold. As shown in Fig. 5, there are a number of these mold-supporting units positioned about the mold in each of the two series of units, 5o thereby affording support at relatively closely' spaced sections about the circumference of the mold. As the mold-supporting standards are radially positioned and as theouter jacket Ill is of larger diameter than the mold, there are pro- 55 vided ample openings between the standards through which cooling water may circulate without overcoming an objectionable resistance.

The extended length of the mold and its weight creates a tendency for the mold to sag, particularly at hig'h temperatures. bars i8 have suillcient resiliency to allow for `thermal expansion of the mold and at the same time are rigid enough to prevent the mold' from sagging. That is, less force is required to prevent sagging than to prevent thermal expansion, and the force exerted by the spring bars is between these limits. By adjusting nutsv i1 and I8 the tension exerted by-bars i6 may -be changed to the desired extent.

When the mold turnsat a high rate oi' revolution there is a tendency for the machine to vibrate unless the mold is supported properly, the vibration being caused by a loss of dynamic bal` ancing. The turbulence` caused when the inflowing stream of molten metal strikes a vibrating mold often will produce defects in the casting. In the case of slender molds such as those used for casting pipe l inches in diameter and Il feet long the eilort exerted by the intermediate supporting units in preventing the sagging and warping of the mold may be of the order of i0 per cent of the effort required to prevent thermal expansion.

The casting mechanism is provided with a cooling system in which water is circulated through the cuter jacket i4 in a direction to- When the mold and jacket are rotating, the

ward the bell end of the mold. A baille 2li at the bell end of the jacket insures passage of the water to the end oi' the mold. After passing around the baille 20 the water reverses its direction and then passes outwardly through ori- Surrounding the bearing surface 22 at the bell end of the machine is a non-rotating circular end casing or shell 23 which is sealed with respect to the surface 22 by means of packing 24 and rings 2B. The casing 22 forms a collection chamber for cooling water passing from the bell or outlet end of the cooling chamber formed by jacket I4.

At its bottom the casing 28 communicates with a return water jacket 24 which`extends longitudinally of the machine and terminates adiacent the other end oi' the mold. lI-'he terminal end of return jacket 24 communicates with a non-rotating circular end shell or casingv 2l. Casing 2l surrounds the end of the mold jacket I4 and the latter is mounted to rotate within this casing by means of packing 2B and rings 21. Thus, casing 2l forms a bearing for the rotatable mold `jacket which will prevent loss of cool-E ing water. Casing 2i also constitutes a supply chamber from which cooling water enters jacket I4 through a sexies of openings 28 located at spaced internals in the jacket.

Itwillbenotedfromllg. landfromaco'mparlson of Figs. il and .'l that the outlet casing 22 is larger in diameter than inlet casing 25.

amount of centrifugal force set up-in the water of 'the cooling system will depend upon the distance of the water from'the center of rotation. As the water at the bell end ot the jacket i4 is farther from the center of rotation than at any other point, the rotation of the mold causes a now of water from jacket I4 into the outlet casing 2I '1hewatortheniiows from the outlet The spring,

casing through return jacket 24, inlet casing 26,v

l and back intoI the jacket I4 by way of openings 28. To prevent backflow, the return jacket 24 is provided with acheck valve, asshown in Fig. 1.

In, traversing the jacket I4 the water comes in intimate contact with the mold and"main, tains the latter at the desired temperature. The temperature of the water entering the jacket it from inlet casing 26 is lower than the ten/iperature of the water leaving the cooling jacket at the bell end of the machine. This temperature gradient results in diierent cooling conditions at the two ends of the mold;V The rapid circulation obtained by my cooling system maintains a relatively low temperature gradient and as a consequence adesirable uniformity of results is obtained. y

The rate of circulation of water depends upon the difference in radial distances from the center of rotation of the water at the inlet and outlet ends of the` cooling jacket and upon the rate of rotation of the mold. These factors co-operate to produce a rapid rate of circulation.

The circulation system described is provided with a fresh Water inlet line 3i which extends between the chamber provided by casing 24 and temperature regulation valve 32. Valve 32 also communicates with a longitudinally extending supply line 23, which connects through a gland 34' with a telescoping section 2l. 0n the oppoline 38.

site side of the casing 24 an outlet line 36 communicates through valve $1 with a discharge This discharge line connects through a gland 39 with a telescoping section to. The supply and discharge lines for the cooling water travel with the carriage as the latter reciprocates away from and toward the pouring spout.

The pressure on the inlet side of the fresh.

water supply line 3i is suillciently greater than -the pressure inside the circulation system to peropposite side of the casing 24 and this vwater tudinally of the axis of the mold toward and.

away from the pouring spout along the supporting track, the water inlet and outlet pipes 2l and Il telescoping respectively into and out ot thepipes 3i and 4I. y f

During the pouring operation the mold and mold casing are rotated at the desirable, rapid rate by the drive gear 48. Gear 4 6 surrounds the jacket I4 at the approximate center thereof and is driven by a suitable motor v(not shown) mounted on the carriage. The gear likewise is connected with an outstanding flange ring 41 which rotates in the slot 4l of a block 49 which is rigidly secured to the carriage 30, as shown in Fil. Thil block proventi longitudinal move- 1| l5 piston rod 42.

amasar 3 ment of the mold during Withdrawal of pipe therefrom'.

The mold jacket is supported on a number of f rollers M, as shown in Fig. 6, these rollers being 5 mounted on opposite sides of the mold center and supported on stanchions 5i positioned on the bottom of the mold carriage. f

In operation'of the machine the mold carriage is moved into telescopic relation with respect to l the pouring spout and the mold is set'into a state of rapid rotation. The molten metalflrst is poured into the bell end'of the mold and the carriage then is moved away from the pouring spout at a' very uniform rate by the hydraulic The rapid rotation of the mold setsy up a centrifugal 'pressure in the bell end of the circulating system lwhich causes water to pass from the shell 23 through the casing 2d and into the inlet shell 25. Fromthe inlet shell the '20 water circulates through openings it in the mold ,jacket and passes in contact `with the mold throughout its length back to the casing til.

n 'I'he valve 32 permits the entrance oi the desired amount of i cooling water into the casing 2l 25 4whereit mingles with the circulated Water bypassed about the mold. The check valve 2d is `raised by the flow of water. When the rotation ofthe mold isstopped the check valve @il permits a continuance of the flow of water from the inlet 30 to the outlet lines, the inlet being on the downstream side of the check valve.

The casting cycle for the commercial sizes of 4 inch, 6 inch, and inch diameter pipe, i3 feet long, is of the order oi one to two minutes. As 35 soon as the metal has solidified and cooled sufflciently to allow it to be handled the casting is withdrawn and the mold is prepared for the next casting.l The structure and qualities of the casting are affected by the temperature of the i (Tmold, it being desirable that the mold be brought back to the same temperature at the beginning of each pouring operation. Practically all the heat removed from the mold passes into the water of the cooling system. This transfer of 45 heat from the moidis dependent upon such factors as the temperature dierence between the mold and the water and the velocity'at which the water passes over the mold surface. By properly adjusting the diameters of the two end cas- 50 ings of the machine and the use of a by-pass iiow, the centrifugal pressure developed during the casting `operation by the rotating mold provides for a rapid circulation of water and optimum cooling conditions. The by-pass chamber pro- 55 vided by casing 24 is large enough to act as a reservoir for circulated water and prevents theincoming` fresh water from having a sudden chilling eiectfon the mold. Various changes may be made in the details 60 of construction described herein without departing from the scope of the invention as defined inthe appended claims.

I claim: 1. In a centrifugal casting machine of the type 5 telescopically movable with respect to .an end through said water compartment and between' said mold supports.

2. il. centrifugal lcasting machine, comprising a metallic mold, a cooling jacket surrounding said mold and being spaced therefrom except at its ends, and a' series of intermediate mold-supporting units between said jacket and mold, said units including mold-.supporting members having their` inner ends bearing against said mold lu 'and extending outwardly therefrom, and spring bars supported' by said jacket for engagement. with the outer, endsof said supporting members with'sumcient pressure to resist sagging of said mold but insufficient to resist thermal expansion thereof.

3. A centrifugal casting machine, comprising a metallic mold, a cooling jacket surrounding said mold and being spaced therefrom to form a water compartment, and `intermediate moldsupporting units between said jacket and mold, each of said units including a mold-supporting member having its inner end bearing` against said mold and extending radially therefrom through said jacket,V spring bar securing means on opposite sides of said supporting member and a spring bar secured by said means and bearing against said supporting member with a pressure sufficient tov resist sagging of said mold but insufficient to prevent thermal expansion thereof.

4. A centrifugal casting machine of the type telescopically movablewith respect to anend pouring trough, comprising an externally cooled metallic mold, a cooling jacketsurrounding said mold and being spaced therefrom for substantially the full length' of the mold, oneend of said mold being longitudinally expansible with respect to said jacket and the other end of said mold being rigidly attached to said jacket, means for rotating said mold and jacket as a unit, a non- 40 rotating casing adjacent each end of said iacket, 1 said jacket having openings communicating with said casings, and one of said casingshaving a greater diameter than the other of said casings y to provide a' centrifugal pressure differential 4 therebetween, a return conduit between said casings, and inlet and outletI conduits communicating with said return conduit.

5. A centrifugal casting machine of the type telescopically movable with respect to an` end pouring trough, comprising an externally cooled rotatable metallic mold having an enlarged bell end, a cooling jacket surrounding said mold for `substantially its entire length and `forming a.

water compartment, a non-rotating casing surrounding said jacket adjacent each end thereof,

said jacket having spaced openings communicating with said casings and the casing adjacent the bell end of the mold being oflarger diameter than the other of said casings to establish a e0 centrifugal pressure differential therebetween upon rotation of said mold. and a return condui connecting said casings.

`(i. A centrifugal casting machine of the type telescopically movable with respect to an end '35 pouring trough, comprising an externally cooled, rotatable metallic mold, a cooling jacket surrounding said mold and forming a one way conduit for cooling water, a. non-rotating collection casing communicating with said conduit adjacent 7o one end of said jacket and ay non-rotating supply casing communicating with said conduit adjacent the lother end of said jacket, a return conduit i pouring trough, comprising an externally cooled rotatable metallic mold, a cooling jacket surrounding said mold and forming a one way conduit for cooling water, a non-rotating collection casing communicating with said conduit adjacent one end of said jacket, a non-rotating supply casing communicating with said conduit adjacent the other end of said jacket, a return conduit connecting said casings, a check valve in said return conduit, an inlet conduit communicating with said return conduit onthe downstream side of saidl check valve and an outletv conduit communicating with said return conduit on the upstream side of said check valve.

8. A centrifugal casting machine of the type telescopically movable with respect to an end pouring trough, comprising an externally cooled rotatable metallic mold having an enlarged bell end, a cooling jacket surrounding said mold and forming a one way conduit for cooling water, a relatively large non-rotating casing surrounding said jacket-adjacent the bell end of said mold and communicating with said one way conduit, a relatively small non-rotating casing surrounding said jacket adjacent the other end of said mold and communicating with said one way conduit, a return conduit between said casings a check valve in said return conduit a cool water supply line communicating with said return conduit on the downstream side of said check valve, and an outlet conduit communicating with said return conduit on the upstream side of said check valve.

9. A centrifugal casting machine of the type telescopically movable with respect to an end pouring trough, comprising a longitudinally extending rotatable jacket having an enlarged bell end and spaced openings adjacent each end, a metallic mold carried in said jacket, said mold having an enlarged bell end fixed to the bell end of said jacket and being slidably mounted at its other end in said jacket, intermediate springpressed mold supports carried by said jacket and bearing against said mold, said supports being spaced apart sulciently to permit free flow of cooling water between said jacket and 'said mold, non-rotating caslngs enclosing said jacket about the openings adjacent each end, a return conduit between said casings, a check valve in said conduit, a telescoping cool water supply line communicating with the return conduit on the down? stream side of said check valve, a telescoping outlet line communicating with the return conduit on the upstream side of the check valve, and means for reciprocating the aforesaid elements longitudinally of the axis of the mold.

10. A centrifugal casting machine of the type telescopically movable with respect to an end pouring trough, comprising a metallic externally cooled mold, a cooling jacket mounted about said mold in spaced relation thereto, said jacket being ilxed to said mold at one end and supporting said mold at its other end in slidable relation, central drive means for rotating said jacket, `and spring-pressed mold supports carried by said jacket on opposite sides of said drive means and bearing against the exterior of said molds with a pressure suilicient to resist sagging but insufticient to resist radial thermal expansion.

FRANK G. CARRINGTON.

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