US1177957A - Method and apparatus for the production of cast-steel blanks. - Google Patents

Description

W. MCCONWAY. METHOD AND APPARATUS ToR THE PRonucTToN oT cAsT sTEEL LANKs. APPLICATION FILED JUNE 5,1915. 1 ,177,957, Patented Apr. 4, 1916.

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W. McCONWAY. METHOD AND APPARATUS FOR THE PRODUCTION OE GAST STEEL BLANKS.

APPLICATION FlLED )UNE 5,1915.

Patented Apr. 4, 1916.

2 SHEETS-SHEET 2.

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. To all whom it may concern:

UNITED s'rArEs PATENT. oFFIoE.

WILLIAM MccoNWAY, oF PITTsBuRGH, PENNSYLVANIA.

METHOD AND APPARATUS FOR THE PRODIICTION OF CAST-STEEL BLAN'KS.

Specification of Letters Patent.

Patented Apr. 4, 1916.

Application led June 5, 1915. Serial No. 32,379:

Be it known that I, WILLIAM MCCoNWAY,

la citizen of the United States, residing at- Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful 'improvements in Methods and Apparatus for the Production of Cast-Steel Blanks; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the artto which it appertains to make and use `Vthe same.

My invention relates to the production of steel blanks from the molten metal, and has for its object the prevention of cracks l in and on the periphery of the casting.

Heretofore, when practising the ordinary methods of vertical casting in stationary molds, attempts have been made to prevent the formation of cracks .in and on the exterior surface of the casting by applying pressure to the casting in the mold afterthe casting has sufficiently cooled to form a solid shell around the inclosed molten metal, and in the practice of such method the use of expansible molds has also been suggested. .v

. In the practice of what is termed centrifu- "hereinafter shown.

gal castingit has been proposed, inthe production of hollow cylindrical castings, to employ a mandrel or roller, within the hollow cylindrical casting and extending longitudinally thereof, with intent to solidify and compact the metal and smooth the interior of the casting; but such a method results in a.- violent disturbance of the molecules of the steel at a critical period in cooling and so'degrades the quality of the metal.

My present invention relates more particularly to what is termed centrifugal casting wherein the molten metal is delivered, when in a high state of fiuidity, directly to a rotating mold, the axis of rotation being horizontal, whereby.. the molten metal is instantly distributed to theperipheral lines and there remains in situ until solidified as y As the -centrifugal method of casting is at present practised the tendency of the metal in the matrix to contract is opposed to the centrifugal force incident to the rotation of the mold, with the result that there is a tendency of the casting to withdraw from the face of the mold or matrix in a directionopposed t0 the cracks inthe casting. `Tomeet these conditions in the centrifugal casting of steel, I have devised a method which involves the application of continuous pressure to the revolving molten metal in a direction normal tothe centrifugal force during the casting operation, and the maintenance of said pres sure continuously until the casting has sufliciently solidified to retain its Iform when -in a quiescent state, after which the centrifto the direction of operation of the centrifugal force during the granulating period of the casting; and a centrifugal casting apparatus thus constructed to be capable of being operated to produce such an effect, involves a secondary feature of my invention.

` In the drawings chosen for the purpose of illustrating an apparatus adapted to be utilized in carrying out my improved method of centrifugal casting,vFigure 1 is a side elevation of centrifugal casting apparatus embodying my invention. Fig.V 2 is an elevation of the charging end of said apparatus. Fig. 3 is a longitudinal vertical section of the apparatus shown in Fig. 1; and Fig. Llis a longitudinal vertical section of a modified form ofthe apparatus.

`ALike symbolsrefer to like parts wherever they occur.

I will now proceed to describe my invention more fully so that others skilled in the art towhich it appertains may lapply the same; and as an understanding of the character of the devices necessary to the carrying out of the method will, it is believed, tend to a better comprehension of .the method itself, and serve to more clearly differentiate my method from the prior art, I will first describe the apparatus employed by me.

In the drawings, l indicates a cylindrical mold adapted for the production of hollow cylindrical castings or ingots C, This mold 30 which is provided o hollow shaft 3a,

is horizontally disposed and is secured by bolts 1b, or otherwise, to a revolving disk or head 2 having a centrally disposed, hollow trunnion or shaft 3, the opposite end of 5 which shaft or trunnion 3 is also provided with a disk or head f1 constituting one head of a cylinder 5. The hollow'shaft or trunnion 3 is journaled in bearings on a pedestal 6. The opposite head 7 of the cylinder 5 is 10 also provided with a hollow trunnion 8 that is in axial alinement with the hollow shaft or trunnion 3, and said trunnion 8 is jourf naled in bearings on a pedestal 9.

The outer end of hollow shaft or trunnion 8 is closed by a head or disk l10 secured thereto by bolts l1, or in other suitable mauner, and said head has a central opening and gland 12 through which passes a pipe 13 that is connected toa pumpor other |source of hydrostatic pressure. The inlet Ipipe 13 for hydrostatic pressure is axially disposed with relation to the hollow shaft or trunnion 8 and is held in stationary posi' tion -in its axial relation to the shaft by mleans of an arm or bracket 9b on the pedesta 9.

Within the cylinder 5 isa piston 14: whose stem 15 extends through the hollow shaft or trunnion 3 and into the mold 1, and within the mold with a h ead or piston 16, of a diameter'substantially equal to the interior diameter of mold 1. These devices form a convenient means for applying continuous pressure tothe cast- 1ng in the mold during the rotation of said mold. The periphery of the cylinder 5 constitutes and is in effect a pulley 5a mounted on the shaft 3, whereby the moldl 1 may be rotated frrm a suitable source of power 40 through the medium of a belt passing around 4such pulley. f The outer end of the rotatable mold llis formed as a disk or head 17 which is secured onthe mold and to the revolving head 2 by bolts 18, and said disk or head 17. is provided with a centrally disposed opening or ,throat 19 through which extends the lower end of a funnel or spout 2O by means of which the molten metal is introducedvinto 50 the rotatable mold 1 at the time of casting.

In. the modified form of the apparatus shown in Fig. 4 of the drawingso the cylindrical mold la, the revolving head 2a, the the pedestals 6a and 9a'in `which the hollow shaft 3a is journaled, the

head or piston 16a within the mold and the stem or piston rod 15a, which extends ,l .through the hollow shaft 3a, each and all have their counterparts in similar relations 0 in the preferred form of the apparatus shown in Figs. 1 and 3 of the drawing. But

in lieu of applying the continuous pressure.

to the' casting by hydrostatic pressure., which requires a cylinder and piston, there has been substituted for these last named elements a pointed pressure screw 21 which is4 supported in axial alinement with the stem 158L of the pistomhead 16a by means ofa bracket or arm 9 on the pedestal 9a'. The

hollow shaft 3a is provided with a pulley 3P for rotating the shaft and mold.

In carrying out my method ofv centrifugal maintain the molten metal in contact with the walls of the mold which a peripheral speed of approximately sixty-five feet. per second or upward will suffice to accomplish, the molten steel in a high state of fluidity is introduced intothemold and as soon as the congelation of the metal sets-in a progressive pressure is applied longitudinally of the casting or, in other words, normal to the direction or operation of the centrifugal The application of this progressive force, which maybe effected by a continulng ap- .force induced by the rotation of the mold.' I

plication of power to the-follower or piston 16 (or 16a) that traverses the mold, is continued until the casting has reachedthe point of solidilication where it will maintain its form in a quiescent state, when the rotation of the mold is arrested and the pressure on the piston (16 or 16B) is released, thus relieving the casting of -the pressure of both the'centrifugal force and the force normal thereto. The casting is then permitted to cool in the usual manner, being then subject only to the force of contraction incident to cooling. The progressive pressure thus applied to the casting 1na direction normal to the Vcentrifugal force during the formative orvgranulating period when the contractionin the casting due to cooling is opposed by the centrifugal force causes the casting to be compressed longitudinally and to expand diametrically so as Cto maintain the contact of the periphery of the casting with the walls of the matrix and prevent the formation of peripheral cracks in the casting. -It is to be noted that when the pressure is in excess of that required to maintain steady peripherall contact with the matrix the excess of pre'ssmre becomes circumferential and prohibits molecular separation. v

Having thus described my invention,

k"what I claim and desire to secure by Letters Patent is 1. The method of producing steel blanks from'molten steel which involves the simul- Y taneouspsubjection of the molten steel to the .operation of centrifugal force and to a force applied in a direction `normal to said cen'- trifugal force.

2. The method of producing steel blanks from molten steel which involves the simultaneous subjection of the molten steel to the operation of centrifugal force and to uniform pressure normal thereto.

3. The method of producing steel blanks from molten steel involving the simultaneous subjection of the molten steel to the operation of centrifugal force and to a force acting normal thereto during the formative perird of the blank and discontinuing the application of said forces when the molten metal has solidified to a point where the blank will retain its shape when quiescent.

4. In apparatus for casting blanks from molten steel, the combination With a rotatable mold.- of means progressively movable in the axial line of the mold for exerting positive pressure on the molten metal in the mold.

5. A method of producing cast steel blanks which involves the subjectionof the molten mass during its granulation to the action of forces the directions of which are normal to each other.

6. The method of forming a cast steel annulus which involves subjecting a mass of molten steel to centrifugal force and applying a compressive force to the mass of metal in direction of length of the annulus during granulation of the steel.

7 ln apparatus for casting blanks from molten steel, the combination with a rotatable mold, of means for rotating the mold to exert centrifugal vforce on the molten metal during the casting thereof, and means Within the mold and movable axially of the mold to eXert on the molten metal a force normal to the centrifugal force created by the rotation of the moldvduring the casting operation.

In testimony whereof I affix mysignature.

WILLIAM MccoN'WAY.

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