US3430681A

US3430681A - Method of and apparatus for making centrifugal castings with integral heads

Info

Publication number: US3430681A
Application number: US620562A
Authority: US
Inventors: Walter W Smith; Kenneth E Longacher; Herbert H Zollar
Original assignee: Shenango Furnace Co
Current assignee: Shenango Furnace Co
Priority date: 1967-03-03
Filing date: 1967-03-03
Publication date: 1969-03-04
Anticipated expiration: 1986-03-04

Description

March 4, 1969 W, W SM|T|-| ET AL 3,430,681

METHOD oF AND APPARATUS Non MAKING CENTRIFUGAD CASTINGS wITH INTEGRAL, HEADS I 'Filed March s, 1967 sheet of 28 32 u8 x4 la e8 le /N VE NTORS.

Wa/er W. Smith Kenner/1 E. Longacher H erber H. Zo//ar BY M@ f// THE/R ArmR/VEYS March 4, 1969 Filed March 5, 1967 W. W. SMITH ET METHOD OF AND APPARATUS FOR MAKING CENTRIFUGAL CASTINGS WITH INTEGRAL HEADS Sheet 2, of 2 INVENTORS.

Wa/er W. Sm/f Kennet/7 E. Longacher Herberf H Zo//ar www f/ THE /R ATTORNEYS United States Patent O 3.430,681 METHOD F AND APPARATUS FOR MAKING CENTRIFUGAL CASTINGS WITH INTEGRAL HEADS Walter W. Smith, Kenneth E. Longacher, and Herbert H.

Zollar, Dover, Ohio, assignors to The Sheuango Furnace Company, Pittsburgh, Pa., a corporation 0f Pennsylvania Filed Mar. 3, 1967, Ser. No. 620,562 ILS. Ci. 164--111 Int. Cl. B22d 13/00 6 Claims ABSTRACT 0F THE DISCLGSURE The manufacture of castings having a hollow cylindrical body and integral heads by centrifugally casting the cylindrical body portion in a hollow refractory lined mold in which the heads are resiliently mounted, the heads having an outer diameter less than the inner diameter of the mold and being provided with intersecting longitudinal slots and circumferential grooves on the outer periphery to promote a strong bond between the heads and the cylindrical body.

- the finished cast cylindrical body can rotate, it is necessary to secure heads to each end of the cylindrical body.

Heads have been secured in the ends of cylindrical castings in `a variety of ways; by bolting, welding, shrinking the cylinders on the heads, or expanding the heads within the cylinders. Each of these methods is time consuming and, therefore, expensive.

We have invented a method for securing heads to cylinders in which the heads are secured to the cylinder while the cylinder is being cast and by which a bond is obtained between the heads and the cylinders.

In the accompanying drawings, we have illustrated a presently preferred embodiment of our invention in which:

FIGURE 1 is a cross-sectional view of a rotatable casting mold used in our invention and showing the heads in place prior to the pouring and casting of the molten metal;

FIGURE 2 is an enlarged elevation view of a head to be used in practicing our invention;

FIGURE 3 is a section along the lines III-III of FIG- URE 2;

FIGURE 4 is a cross-sectional view of the mold similar to FIGURE 1 and including the centrifugally cast body formed by our invention;

FIGURE 5 is a cross-sectional view of the completed cast product of our invention;

FIGURE 6 is an enlarged detail view of the bonded joint formed between the cast body and a head; and

FIGURE 7 is a side view of the joint of FIGURE 6.

In FIGURE l, we have shown a rotatable sand mold assembly suitable for centrifugally casting a cylindrical body integrally with a head at each of its ends according to our invention. The assembly comprises a hollow elongated cylindrical mold 10. Flanges 12 extend from the outer 3,430,681 Patented Mar. 4, 1969 Fice surface of the mold at each end thereof.

Roller tracks

14 and 16 are positioned on the outer surface of the mold adjacent each end. Pairs of drive rollers (not shown) engage the

roller tracks

14 and 16 to support and rotate the mold about its longitudinal axis. Guides 18, formed along the edges of the track 14, prevent longitudinal shifting of the mold, and thus keep the

tracks

14 and 16 on the drive rollers.

A circular face plate 20, having a central aperture 22, is mounted on one end of the mold 10. A base portion 24 of the plate extends radially from the aperture and terminates in a disk portion 26 having a thickness less than that of the base portion 24. A collar 28 is secured to the plate 20 along the disk portion, such as by bolts 30. A flange 32 of the collar 28 tits inside the mold 10. A disk 34 of refractory material, having a central hole 36, is pressed against the plate between the flange 32 and the wall forming the aperture 22. When the plate 20 is secured to the flange 12 at the end of the mold 10, the inner edge of the ange 32, the wall forming the aperture 22, and the inner face of the refractory disk 34 lall lie in the same plane perpendicular to the longitudinal axis of the mold.

A circular head 38, of the type shown in FIGURES 2 and 3, is resiliently secured to the face plate 20. The head comprises a wheel-shaped body having a hub 40 and a disk portion 42 extending from the hub and terminating in a rim 44 which is thicker than the disk portion 42, but narrower than the axial length of the hub. Webs 46 extend radially from the hub 40 to the rim 44 to strengthen the head.

Four blind tapped holes 50 are located in the disk portion 42 radially equidistant from the axis of the aperture 22 and equally spaced circumferentially about the aperture. Longitudinally extending slots 52 are circumferentially spaced equidistant from one another about the rim 44.

A plurality of circumferential grooves 54 having a depth no greater than and preferably less than the depth of the slots S2 which they intersect are provided along the rim 44 of the head 38. The disk portion 42 of the head also has a central indented portion 56.

Referring to FIGURE 1, we have shown the head 38 positioned in the mold prior to pouring the molten casting metal. Studs 58, threadably anchored in the tapped holes 50 in the head 38, extend through corresponding holes in the refractory disk and face plate and protrude outwardly therefrom. Coil springs 60 are placed over the protruding studs 58 and the head 38 is drawn securely against the refractory disk 34 by nuts 62 threaded onto the studs. Thus, the head is resiliently mounted on the face plate preparatory to casting.

A lining 64 of molding sand, which is also refractory is then compacted on the inner wall of the mold 10 in accordance with standard practice. The length of the sand lining is substantially equal to the length of the cylindrical casting to be made, and the internal diameter of the lining is greater than the diameter of the head member secured to the face plate.

The end of the mold opposite the face plate is closed with a circular stop or set plate 66 whichvis adapted to be positioned within the inner wall of the mold 10 perpendicular to the longitudinal axis of the mold. The set plate can be adjustably secured in any position along the inner wall of the mold to vary the length of the casting as required.

Flanges

68 and 70, integral with the periphery of the set plate 66, extend outwardly from inner and outer surfaces, 72 and 74 respectively, of the set plate for cooperation with the inner wall of the mold. Aperture 76 of the set plate has its center on the longitudinal axis of the mold 10 when the mold is completed.

A second disk 78 of refractory material is ypressed against the inner surface of the set plate. Hole 80 in the disk 78 is axially aligned and communicates with aperture 76 to provide an opening, upon assembly, into the mold from the outside of the mold.

A head 82, substantially identical to the head 3S, is resiliently secured to the set plate 66 in a manner similar to the mounting of head 38 to face plate 20.

The assembly of the head 82, disk 78 and set plate 66 is placed into the open end of the mold 10, such that the plate 66 is perpendicular to the longitudinal axis of the case. When the assembly is complete, the sand lining 64 contacts both the

refractory disks

34 and 78 around their peripheries.

The completed mold assembly may then be set in rotation about its longitudinal axis by the drive rollers to evenly distribute, by centrifugal force, the molten metal poured into the prepared sand mold. The molten metal is poured into the mold by any well known means. We prefer to insert a pouring spout (not shown) through an aperture in either the face plate or the set plate, using a spout which is long enough to discharge the molten metal at a point aproximately midway between the heads, and on the axis of the mold, to obtain a more even distribution of the molten metal along the sand lining in the mold. Centrifugal force, generated by rotating the mold, causes uniform distribution of the molten metal along the iner wall of the mold forming the cylindrical cast portion, and, more important, the metal lls the slots and grooves on the rim of the head and extends to the sand lining.

We have also found it advantageous to superheat the molten metal, preferably to a temperature at least 200 F. greater than the melting point of the metal used in casting. This prevents premature soliditication of the casting, i.e., al1 of the metal is poured and distributed before any of it solidics.

FIGURE 4 shows the completed casting in the mold and FIGURE 5 shows the casting after removal from the mold. A cast cylindrical body 86 extends between the

heads

38 and 82 to which it is bonded. The bonded joint between the head 38 and the body 86 is shown in FIG- URES 6 and 7. The bonding of the heads to the cast body is enhanced by the slots 52 and grooves 54 machined in the rims 44. The circumferential grooves 54 in the heads provide an increased area of contact between the molten metal and the heads so that it is believed that portions of the heads between the grooves are at least partially melted upon first contact by the molten metal. In any event, we have found that a bond is formed between the heads and the cylindrical body. Since the depth of the slots 52 is greater than the depth of the grooves 54, an opening 88 is provided which enables air which might otherwise be trapped in the grooves during casting to escape in the direction of arrow A, thus minimizing blow holes or air pockets in the bonded joint which would adversely aect the integrity of the joint.

The resilient mounting of the heads against the refractory disks and plates permits the heads to contract longitudinally in the mold. This strengthens the bonded joint and minimizes adverse stresses between the heads and the cast body.

A structure substantially similar to that shown in FIG- URE 5 has been cast and was examined physically and metallurgically; the ram length of the specimen tested was 75% inches, and had a 33 inch internal and a 361/2 inch external diameter. The width of the head of the specimen tested, at the periphery, was 51/2 inches. The specimen was tested at 8O pounds per square inch water pressure (approximately equal to 40 p.s.i. steam). An end of the roll was machined back 4 inches from the base of the head above the periphery of the head. Metallurgical examination of the machined surface showed a sound bond at a diameter of 33% inches or 1/16 of an inch below the top of the grooves measured from the outside diameter of the periphery of the head.

Using our invention, complete assemblies of cylindrical, circular, and symmetrical cast shapes can be bonded to the heads. The product of the invention is a satisfactory integral shape having virtually none of the adverse mechanical stresses usually characteristic of cast-in assemblies, and which has good physical and mechanical characteristics.

We have described our invention in terms of bonding a head to a cylindrical body; however, this invention may be used to bond any type of plate, flange, disk, head, etc., to a cylindrical or other symmetrical body which can be formed by centrifugal casting. For example, it can be used to bond an internal ange, disk, plate, or head to a cylindrical roll body in cases where it is then desired to mechanically mount a cover on the part which in turn has been bonded to the cylindrical roll.

As used in this specification the term symmetrical body means a body or shape which when formed is symmetrical about the axis of rotation of the casting machine and therefore includes bodies having cross-sections which are circular, square, triangular, octagonal, etc.

Both ferrous and nonferrous materials can be utilized in this invention. Thus the head or end plate may be either a ferrous or nonferrous material and the cast body portion may be either ferrous or nonferrous.

While we have shown and described a preferred embodiment of our invention, it will be understood that it may be otherwise embodied within the scope of the appended claims.

We claim:

1. The manufacture of castings having a hollow cylindrical body portion and integral heads at each end which comprises:

(a) Mounting a hollow refractory lined cylindrical mold for rotation about its longitudinal axis, said mold being closed at each end by a circular plate extending transversely of said longitudinal axis;

(b) Mounting on the inside surface of each plate one of said heads, said heads being resiliently mounted for movement inwardly of the cylinder and away from the plates, said heads also being positioned within the refractory lining of the cylinder and having an outer diameter less than the inner diameter of the lining thus forming an annular space between the periphery of each head and the refractory lining; and

(c) Rotating said mold about its longitudinal axis and pouring molten metal into said cylindrical mold, centrifugal force distributing the metal uniformly over the lined interior of the cylindrical mold and forcing the metal into the annular spaces between the heads and said lining.

2. The manufacture of castings set forth in claim 1 in which the molten metal is superheated prior to being poured into the mold.

3. The manufacture of castings set forth in claim 1 in which the heads are provided with a plurality of circumferential lgrooves prior to mounting on the plates.

4. The manufacture of castings set forth in claim 3 in which the heads are provided with a. plurality of longitudinally extending slots which intersect the grooves, the slots having a depth at least as great as the depth of the grooves.

5. Apparatus for manufacturing castings having a hollow cylindrical body portion and integral heads at each comprising:

(a) A refractory lined hollow cylindrical mold mounted for rotation about its longitudinal axis;

(b)` `Circular plates at each end of the mold for closing the refractory lined portion of the mold, at least one of said plates having a circular aperture through which molten metal can be poured into said mold; and

5 6 (c) Means on each plate for mounting one of said whereby the head is biased to permit movement of heads, said heads having an exterior diameter less the head inwardly longitudinally of the cylinder and than the interior diameter of the refractory lining and away from its plate during casting of a. roll. being positioned lwithin the lining adjacent its ends, References Cited said mounting means being reslllent to permlt move- 5 met of the heads inwardly of the cylinder and away UNITED STATES PATENTS fromthe plates- 2.030.105 2/1936 VEnrich et a1. 164-286 6. Apparatus for manufacturing castings as set forth in claim 5 wherein said resilient mounting means com- FOREIGN PATENTS @mesi i0 785,319 10/1957 Great Britain.

(a) At least a pair of studs extending through one of said plates, each stud having an end secured to a 1 SPENCER OVERHOLSER Primary Examinen head; (b) The other end of each of said studs protruding R D' BALDmNAsslsmmExammer through said plate and outside said mold; 15 Us C1 XR (c) Biasing means engageable iwith a protruding end of each stud for drawing a stud and a head secured 164-112, 288 thereto against the plate on which it is mounted,