US2853755A

US2853755A - Centrifugal casting method

Info

Publication number: US2853755A
Application number: US481670A
Authority: US
Inventors: Beyer John Henry
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-01-13
Filing date: 1955-01-13
Publication date: 1958-09-30
Anticipated expiration: 1975-09-30
Also published as: DE1143303B

Description

Sept. 30, 1958 'J. H. BEYER CENTRIFUGAL CASTING METHOD 2 Sheets-Sheet 1 Filed Jan. 13, 1955 INVENTOR. JOHN l7. BZXEE Sept. 30, 1958 J. H. BEYER 2,853,755

CENTRIFUGAL. CASTING METHOD Filed Jan. 13, 1955 L g 5/ F1 9. 6

INVEN TOR.

Jaw/v 1/. 56762 2 Sheets-Sheet 2 CENTRIFUGALCASTING METHOD John Henry Beyer, Beverly, N. J. Application January 13, 1955, Serial No. 481,670

5 Claims. (Cl. 22 20.0;5)

The present invention relates to the manufacture of tubular metal castings, and more particularly is concerned with *the manufacture of 'cast iron pipe having bell and spigot 'ends, in permanent metal molds rotated horizontally. I I

It is, wellknown to, cast pipe 'in permanent metal molds, such methods having been practiced extensively -in-this country'for about 30years. Present methods comprise the use of cylindrical metal molds mounted on rollers in a water jacket and adapted to be rotated at suitable speeds. The water jacket ismounted on wheels so that'the entire assembly can be moved by means of a hydraulic cylinder in the direction of the longitudinal of the mold on a fixed bed inclinedslightly from the. horizontal. T he molten ironis fed into the mold through a trough similarly inclined. In casting, a ladle containing-molten iron is tilted at a uniform rate to maintain a constant pouring rate. When the mold is at the extreme upper end of the lixed bed, it is rea dy for casting at which time the trough extends down-thebarrel of the mold for nearly its full length. After the casting ladle has been filled by the transfer ladle, the machine operator brings the mold up to speed and actuates the mechanism controlling the tilting of the ladle. In a few seconds the iron-has filled the bell space at which time the operator starts moving the mold carriage longitudinally down the bed. The stream of iron discharged from thetrough flows onto the surface of the mold, where it is held in place by centrifugal force and 'forms the pipe.

Early in the development of such machines, it was discovered that far better results are obtained if, instead oif-pouring the iron onto the bare mold, a dry unbonded -powdery material, such as 'ferro-silicon, is applied on the inner mold surface just ahead of the iron stream. While constituting a definite improvement, the use of such lin- -ingsnevertheless did not result incompletely acceptable pipe, there always being so-called pinholes or laps or "cold shuts.

"Perhaps the 1 greatest stride in overcoming these disadvantages of casting pipe in permanent metal molds was the invention described and claimed in Schuh et .al. Patent No. 2,399,606. Briefly stated, that invention comprises spraying the inner surface of-theimetal mold with a liquid suspension of a powdered refractory material 'and'a binder to form incrementallyan insulating coating adherent to the mold and having a multiplicity of spaced :protuberances on its inner-face.

ome .of the distinct advantages of using permanent unetal :molds is the speed with'iwhich a great number oft 'pipes can :be cast, :as compared to other methods such as pit casting and centrifugal casting in sand lined molds.

:Maximum castingrspeeds have not-.been attained, however,

due to the necessity of moving:the mold through two two-way strokes for each -pipe cast. Qne' two-"waystroke -:is required for pouring the metal throughout the length of the mold, whilemoving the mold relative to the pour- ;ing trough, and'extractingthe-cast pipe by return-of the mold to casting position. The additional two-way stroke is required in some methods to apply the mold coating,

United States Patent 0 lice has been dispensed with only where additional means have been provided for extracting the pipe-without'longitudinal movement of the mold. The latter method requires fifty percent additional longitudinal'space as 'well as added equipment and so has not been generally adopted. I I

It-is, accordingly, the principal object of the present invention to provide a casting procedure or method for producing pipe in a reciprocating permanent metal mold wherein only one two-waystroke of the mold is required for the production of each pipe.

Another object of the invention is the provision-of a casting method whereby pipe can be made in a horizontally rotating permanent metal mold without themecessity of a separate two-way traverse of the mold forinsertion of a bell core or for applying a moldcoating.

Still a further object is to lprovidea methodfor casting metal pipe in a horizontally rotating permanent mold in which the mold is moved in one direction along its horizontal axis to extract thepipe and ismoved in the opposite direction to receive a refractory mold coating and/or to be positioned forreception of molten metal.

Still another object is the provision of a method :for casting metal pipe in a horizontally rotating permanent metal mold in a shorter time than heretofore considered possible. I

This invention has other objects that willbe apparent from a consideration of the method described'herein and of the specific embodiment shown in the drawings saccompanying and forming part of the present specification.

Such form will now be described in detail to illustrate the general principles of .the invention, but it is :to be understood thatsuch detailed description "is not to be taken in a limiting sense, since the scope of the invention is defined by the claims appended hereto. In the drawings:

Figure 1 is a side elevation of a pipe casting machine suitable for practicing the process of thisrinventiomand with parts thereof broken away.

Figure 2 is an enlarged sectional view taken substantially on the line 'IIII of Figure '1, with parts being broken away.

Figure 3 is an .enlargedsectional view taken along line I'II'III oflFigure 2, showing in greater detail the pushout bar and .spray nozzles for applying a refractory coating to'the mold interior.

Figures 4 through 8 are diagrammatic sketches, omitting details, illustrating the various steps in the novel icasting cycle comprising'the present invention.

The'machine generally comprises a Supporting platform :10 of conventional design, provided with a pair ofhori- Carriage 12 is adapted for .13 attachedto the carriage through axle 14. Carriage 12 carries-cylindrical mold .15 which defines the exterior surfaceof the pipe produced therein. 'Mold 15.is supported by .a plurality of rollers 16 rotatably mounted on drive gear .22 drivingly attached "to mold 15 through ring 26.

Cooling of the mold 15 is effected by spraying a cooling fluid, preferably water, upon its exterior by means of 3 a plurality of spray jets 28 of the mold and supported by fluid conduits 29 which supply the cooling fluid to the jets. In the apparatus illustrated in Figure 1 there are three conduits provided, one directly beneath the center of the mold and one each spaced 120 therefrom on both sides of the mold. The conduits are connected with fluid supply means (not shown) which include controls for turning the supply .of cooling fluid 'on or ofi as required during casting operations. Cooling fluid is removed from themachine, after contact with the mold exterior, by gravity through outlet conduits 30, spaced along the bottom of carriage 12and leading into telescoping pipes or outlet troughs 31 and thence through drains 32. Alternatively, the mold can be cooled by immersion in a water jacket in accordance with well known means.

A spigot end closing device33 is provided for prevention of metal runout at the spigot end of the mold during casting. In accordance with the structure shown in Figure 2, there is provided a longitudinal shaft 34 supported by bearings (not shown). To one end of the shaft 35 there is secured a lever 36 supporting a cage 37 in which is mounted, through the medium of a bearing spaced adjacent the length' (not shown), a ring the external diameter of which will 1 end of the mold by means of air cylinder 38. Shaft passes through a bracket 39 mounted on carriage 12, and provided with a helical slot 40 adapted to receive a pin 41 protruding therethrough and rigidly attached to shaft 34. Thus when the piston in air cylinder 38 is forced toward the bell end of the mold, shaft 34 and.

pin 41 are also forced in that direction. In order to move, however, pin 41 must follow the helical path of slot 40, causing rotation of shaft 34 and consequent movement of lever 36 and the attached closing device to the position shown in Figure 2. Conversely, when pressure on the piston in cylinder 38 is reversed, shaft 34 is forced to move away from the mold and to rotate in the opposite direction, thus moving the end closing ring out of alignment with the mold.

In accordance with the present invention metal is poured through the bell end core 43 into the rotating mold 15 from a pouring ladle 42 and is guided by a pouring spout 44, the small end 45 of which extends, into the mold about equal distance with the innermost part of the core 43. Pouring ladle 42 is preferably of metal construction with a refractory lining, and should be of such size as to hold sufiicient molten metal to produce one pipe of the size determined by the mold and of predetermined wall thickness. The ladle is pivoted on the front by a fixed support 46. Metal is poured from the ladle by raising the rear thereof by means of hydraulic lift comprising a cylinder 47 and piston 48. An arm 49 is pivotally connected to the upper extension of piston 48 and the other end of arm 49 is rigidly attached to shaft 73. This shaft is rotatable in bearings seated in,

support 46 and the other end of the shaft is rigidly attached to one side of ladle 42. A similar shaft arrangement supports the opposite side of the ladle. In operation shaft 73 rotates to tilt the ladle when piston 48 is forced upward. Spout 44 is attached to and supported by fixed support 46 through supports 50. Alternatively, and particularly when the cast pipe is to be removed by means holding it in fixed position rather than by push outmeans as shown, the ladle and pouring spout may be movable by hydraulic cylinders out of alignment with the mold and away from the mold. Suitable apparatus for this alternative is shown,. for example, in Patent No. 1,942,919.

At the end of supporting platform 10, opposite the pouring end, there is provided a fixed support51 for one end of a combination push-out lance and spray coating equipment, shown generally at 52. This portion of the machine illustrated comprises essentially a lance tube portion 55 rigidly attached to the support 51 by bracket 53 secured by bolts 54. The outer tube 55, which acts as a support for the spray equipment, is of such length that when carriage 12 is retracted to contact with support 51, the end 56 extends to a position adjacent to or past the outer portion of hell cavity 24 of the mold. The free end of tube 55 is provided with pushout ring or head 57, rigidly secured as by brazing or welding, which is adapted to contact the spigot end of the pipe formed in mold 15. Pushout ring 57, has an outside diameter smaller than the insidediameter of mold 15 but at least slightly greater than the inside diameter of the pipe to be cast.

A smaller tube 60 is mounted within outer tube 55 and is maintained coaxially therewith by means of a cylinder 61 slidably mounted within tube 55 and rigidly attached to tube 60. One end of tube 60 is attached to an arm 74 said arm'being also connected to extension 62 of a piston, parallel to tube 60. The piston is operated reciprocally within a cylinder 63 by fluid pressure introduced through fittings 64 or 65, depending on the direction it is desired to move the piston and connections thereto. At the other end of tube 60 is a threaded closure cap 66,and adjacent thereto are spray nozzles 67 for spraying refractory'mold coating compositions. In operation, spray nozzles 67 are retracted into tube 55 as shown in Figure 3 while the lance is being used to push a cast pipe from the mold. When end 56 of the lance is protruding past the'bell cavity, after having pushed the pipe out, fluid pressure is applied through fitting 65'to force the piston in cylinder 63 toward the casting machine, thus causing inner tube 60 to move in that direction until spray nozzles 67 are moved to an exposed position past end 56. The mold coating material is then introduced into pipe 60 and is forced by pressure out of nozzles 67.

In the specific embodiment shown, lance 52 is in fixed position so that the free end may transpierce the mold 15 as the mold carriage 12 is moved back and forth on rails 11. A piston 68 operating in a cylinder 69 secured to the base 10 has its outer end connected to the under side of carriage 12 by a coupling member 70 for moving the carriage to and fro on the rails 11 during operation.

The series of steps comprising the casting process of the present invention will now be described with particular reference to Figures 48, inclusive, which show diagrammatically the operations performed and the positions of parts of the apparatus during each step. In the first step, Figure 4, rotation -of the mold about its horizontal axis is commenced by activation of motor 18. The spray nozzles 67 are advanced so as to protrude past the end of tube 55 to an exposed position. In the meantime, pouring ladle 42 has been charged with the proper amount of molten metal for making one pipe of predetermined wall thickness and of .an outside diameter determined by the inside diameter of mold 15. A bell core 43 is placed in position around the spout end 45 of pouring spout 44.

Spray of coating material is then begun as the mold carriage is moved in the direction of the arrow (Figure 5), and is continued until'the carriage reaches the position shown in Figure 6. The'sprayInozzles will have then passed through the complete length of the mold while spraying the mold coating. The spray is then stopped and spray nozzles 67 retracted to the position withinthe tube 55. V

Rotation of the mold is then stopped in order that the bell core 43 may be seated and secured in the bell cavity of the mold; The piston 34 in' cylinder 38 is forced to ward the spigot end of the mold, thus causing the spigot end closing device 33 to close the spigot end of the mold. In the step illustrated injFigure 7, the mold is again rotated, cooling water sprayedonto 'the'ou'tside surface bf the mold through nozzles 28, and the pouring ladle42 is tilted, molten metal being poured therefrom through pouring spout 44, the' small end 45 of whichextends into the mold through the bell core 43, terminating at the inner extremity of said core. The molten metal is carried throughout the length of the mold'by centrifugal force.

Rotation of thernold is continued until the metal has solidified to a point where it is self-supporting, at which time rotation is stopped, water spray onto the mold .is stopped, and spigot end closure ring v33 is moved out of position'in-line with the mold; Mold carriage 12 is then moved in the direction of the arrow in-Figure 8. Pushout ring 57 enters the spigot end of the mold and engages the spigot end 71 of the pipe 72 which has been formed in "thenrol'd. Continuation ofmovem'ent of the carriage to the position shown in Figure 4 causes the pipe to be pushed completely out of the mold where it is received and removed by any suitable means (not shown).

While in the preferred embodiment, illustrated and described, the mold coating lance is adapted to operate also as a pipe pushout device, the feature is not essential to the process comprising the present invention. The process does, however, require that the pipe be removed by means holding it in fixed position, as shown in Figure 8, while the mold is traversed until free of the pipe. This result can be accomplished by alternative means which clamp and hold the bell end of the pipe while the mold is traversed. Suitable grasping means are well known in the art.

After extraction of the pipe the mold is again in position to be rotated, moved toward the pouring equipment, and supplied with a new mold coating. The heat remaining from the previous casting is sufiicient for drying or curing the mold coating material, when required. The mold must be heated by other suitable means prior to spray coating at the beginning of casting operations.

The foregoing process makes it possible, for the first time, to produce a casting with a single two-way stroke of the mold, where as conventional casting cycles require two two-way strokes of the mold for each casting or one two-way stroke of the mold with additional means for extraction of the pipe requiring additional space. The elimination of a complete stroke without adding a separate extraction unit is made possible only by the combi,

nation of features described in this specification for the first time. In addition, the process makes it possible to apply a mold coating of a type requiring drying or curing without the necessity for an added stroke of the mold.

Essentially, the coating must be supplied by a lance entering the mold from the spigot end, which lance can serve the additional purpose of ejecting the cast pipe by applying force thereto toward the bell end when the mold is moved to cause the lance to enter the mold. It is likewise essential, in this operation, that non-retractive pouring of metal be utilized; specifically, the metal must be poured through the bell end of the mold, while the mold is rotating horizontally about its axis, but while the mold is maintained stationarylongitudinally.

In order to realize the full benefits of the casting method of this invention, it is necessary that the entire charge of molten metal be distributed throughout the length of the mold as rapidly as possible, and particularly before any portions thereof are solidified. To accomplish this result requires a proper balance between pouring temperature, time of pouring and rate of mold rotation during pouring. While exact limits for all possible combinations cannot be defined exactly, the limits for any combination, taken with other variables such as metal composition, mold coating composition and thickness, mold wall thickness and length and diameter of the pipe to be cast, can easily be determined by experimentation as is necessary in conventional casting methods. In fact, the determinations are simplified by the method of this invention 'due largely to elimination of the human error "factorinherent in'prior methods which require judgment in the rate of pouring metal along the length of the-mold.

, I claim: V

1. In the method of making tubular metal castings in a horizontal, cylindrical, externally cooled metal mold "having'bell' and spigotends, the methodi'steps whichcomprise retracting the said mold from afixed lance extending fromthe spigot end through the mold-along the longitudinal axis thereof, said lance applying a mold coating throughout the inner surface of the moldduring such retraction, stopping longitudinal movement of the mold when fully retracted from said lance, placing a bell .core and'a spigot end closure in the respectiverhold ends, arorating the mold and pouring molten metal therein-through said bell core, whereby said molten metal is uniformly distributed throughout the inner surface -of'the zmold .by centrifugal force, stopping mold rotation when the said molten metal has solidified to form a pipe, and ejecting said pipe from said mold by moving the mold longitudinally against said lance, whereby the end of the lance engages the end of the pipe and holds the pipe stationary relative to mold movement until fully ejected from the bell end of said mold.

2. In a method of casting pipe from molten metal in externally cooled centrifugal metal mold-s having bell and spigot ends, the method steps which comprise setting the mold in rotation and pouring molten metal therein through the bell end, continuing rotation of the mold until the poured metal is uniformly distributed throughout the mold by centrifugal force and is solidified to form a pipe, then stopping mold rotation and moving the mold along its longitudinal axis in the direction of its spigot end whereby the spigot end of said cast pipe engages a fixed pushout lance to hold said pipe stationary against longitudinal movement with the mold, continuing and longitudinal movement of the mold until the bell end of the mold has passed the spigot end of the pipe whereby the pipe extracted, then setting the mold in rotation and retracting the mold to its original position while simultaneously applying a coating to said mold from an applicator mounted on said lance.

3. The method of casting metal pipe in a horizontal permanent metal cylindrical mold'having bell and spigot forming ends, rotatable about its horizontal axis and reciprocatable along its longitudinal axis which comprises, rotating the said mold, pouring molten metal into the rotating mold through the bell end thereof while maintaining the mold longitudinally stationary and while spraying Water onto the exterior surface of the mold, stopping mold rotation and water spray when the poured metal has solidified to form a pipe, moving said mold along its longitudinal axis in the direction of its spigot end whereby the spigot end of said cast pipe engages a fixed pushout lance which holds said pipe stationary against movement of said mold, rotating said mold after the bell end thereof has cleared the spigot end of the stationary cast pipe, retracting said rotating mold to its original position while applying an interior refractory coating thereto.

4. The method of casting metal pipe in a horizontally rotatable, reciprocatable, permanent metal cylindrical mold having a bell and a spigot end which comprises, securing a bell core in the bell end and closure means in the spigot end of the mold, thereafter rotating the mold and applying cooling means to the exterior surface thereof,

continuing said longitudinal movement of the mold until said pipe is completely extracted and removed, rotating said mold and. retracting it to its original position while applying a mold coating thereto by means 7 carriedby said pushout lance.

1 5. In the method of making tubular metal castings in a horizontal, cylindrical, externally cooled metal mold having bell and spigot ends, the method steps which comprise retracting the said mold from a fixed lance extending from the spigot end through the mold along the longitudinal axis thereof, said lance applying a mold coating throughout the inner surface of the mold during such retraction, stopping longitudinal movement of the mold when fully retracted from said lance, placing a bell core and a spigot end closure in the respective mold ends, rotating the mold and pouring molten metal therein through said bell core, whereby said molten metal is uniformly distributed throughout the inner surface of the mold by centrifugal force, stopping mold rotation when the molten rnetal has solidifiedto form a pipe, and ejecting said pipefrom said mold by moving the mold longitudinally in the direction of the spigot end while maintaining the pipe stationary until fully ejected from the bell lend said mold. g 7

References Cited in the file of this patent,-

UNITED STATES PATENTS 1 1,199,353 DB Lavaud et al. Sept, 26, 1916 1,550,126 Tompkins "Aug. 18, 1925 1,615,877 Knocke- Feb. 1, 1927 1,942,919 Enrich et a1. Jan. 9, 1934 2,399,606 Schuh et a1. 2 Apr. 30, 1946 2,631,342 Romine Mar. 17, 1953 FOREIGN PATENTS 378,558 1923 Germany 1. 1 July 17,