US2156998A - Apparatus for forming composite metal articles - Google Patents

Description

May 2, 1939. w, E. MccuLLoUGH APPARATUS FOR FORMING COMPOSITE METAL ARTICLES '2 sheets-sheet 1Y Filed oct. 18, 1937 INVENTOR WILLlAM E. MC CULLOUGH ATT ORNE;

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May 2, 1939. wjE. MccuLLoUGH AFPARATUS FOR FORMING COMPOSITE METAL ARTICLES Filed Oct. 18, 1957 2 Sheets-Sheet 2 FIG.2

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INVENTOR ATTORNEY Patented ay 2, i939 MPAR'EUS FR FRMHJG @OMPOSTE METAL ARTICLES Application October i8, 1937, Serial No. 169,733

illaims.` (Ci. 22m-58) This invention relates generally to an improved method and apparatus for casting composite metal articles and refers more particularly to casting linings in bearings or like members.

It is one of the principal objects of this invention to provide a method and apparatus bf the type set forth capable of securing a more uniform product by eliminating, to a large extent, manual control of casting conditions. lo Another advantageous feature of the present invention consists in the provision of a method and apparatus for casting linings in articles wherein the steps of melting the metal, heating the articles, casting the lining, and initially cooling the resulting casting, are all carried out under such closely controlled atmospheric conditions as to prevent oxidation of the metalfromthe time it is converted to its molten state to the time it is initially cooled in the mold.

Another object of this invention is to preheat the article or mold to the casting temperature in a chamber having an atmosphere free from air or oxygen so that there is no danger of the surfaces of the article, or mold, from becoming oxidized and, in turn, elect oxidation of the molten metal subsequently poured into the mold.

Still another object of this invention consists in converting the metal to its molten state in a crucible containing an atmosphere which is also free from air or oxygen so that the oxidation of the metal will not take placeduring theimeltlng operation. l v,

In addition to the foregoing, the present invention contemplates pouring the molten metal into 35 the mold cavity in an atmosphere which is also characterized in that it will not oxidize the metal during the time it is poured into the cavity.

',Ihe foregoing, as well as other objects, will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:-

Figure l is a perspective view of apparatus conn structed in accordance with this invention;

Figure 2 is a plan view of the apparatus shown in Figure 1;

Figure 3 is a sectional view taken substantially on the plane indicated -by the line 3-3 of Figure 2; l

Figure 4 is a cross sectional view taken substantially on the plane indicated by' the line 4-4 of Figure 3; and

Figure 5 is a, sectional ly modied form of construction.

In general, a mold. containing a bearing shell It and a core cooperating with the inner surview illustrating a slightface of the shell to form a cavity are supported on a platform li within a heating chamber l2 and molten metal is permitted to ow by gravity into the cavity from a crucible i3 supported above the heating chamber l2. The heating chamber i2 is sealed and the atmosphere in this chamber, as Well as the atmosphere in the crucible i3, is eiectively controlled so as to be free from air or oxygen. -This is accomplished, in the present instance, by replacing the atmosphere in both the Crucible and heating chamber with agas which will not oxidize the metal at the temperatures used inthe pouring operation. As a result of the above, no air or oxygen is permitted to contact with the metal from the time it is converted to its molten state to the time it is poured into the bearing shell and, as a consequence, the metal forming the lining of the shell will aiord a highly satisfactory bearing surface.

After the proper amount of molten metal has been poured into the shell lil, the discharge opening in the bottom of the crucbleis closed by a valve it and the platform il is lowered to locate the bearing shell in a position below the heating chamber l2 Where it may be conveniently removed from the platform and subjected to a cool.- ing operation (not shown. herein). The core it is then removed from the bearing and the latter is machined to theiproper size.

Referring now more in detail to the apparatus selected herein for the purpose of illustrating the present invention, it will be noted that the same comprises a vertical furnace it supported by a plurality of legs i'i and having a bottom wall it centrally apertured to provide for extending the platform li upwardly therethrough. Supported upon the plate i8 by means of the ring I9 is an element 2li formed of refractory material and having an opening 2l therethrough in registration with the opening through the bottom plate it of the furnace. The element 2t forms the bottom wall of theA pouring chamber it and supports the drum-shaped element 22 which is also composed of refractory material, and forms the vertical side wall of the pouring chamber l2. It will be observed from Figure 3 that the outer surf ace oi the element 22 is spaced inwardly from the annular side wall 23 of the furnace and this space is lled with a suitable insulating material 2li. The inner annular surface of the element 22 is lined with a shell 25 having an electrical heating element 26 associated therewith and designed to4 maintain the temperature in the chamber l2- metal during the pouring operation and to heat the element 20 and having the lower edge portion flared outwardly and adapted to engage the correspondingly tapered wall of the central opening through the bottom wall i8 to provide a seal which prevents the passage of air into the charn-v ber l2 when the platform is in its uppermost position, shown by the full lines` in Figure 3. Supported upon the upper end of the section 21 is a top section 28 recessed, as at 29, to receive a refractory material 30 and adapted to support a table 3l which, in turn, forms a support for the bearing shell l0.

The platform il is movable between the two positions shown in Figure 3 by means of a fluid pressure actuated device 32' comprising a vertical cylinder 83 and a piston 36 reciprocably mounted in the cylinder. A rod 35 operatively connects the piston 3Q in the cylinder 33 to a central hub 35 formed integral with the cupshaped section21 of the platform Ii.. In accordance with conventional practice. uid pressure is alternately admitted to the cylinder 33 on opposite sides of the piston i in a manner (not shown herein) for eecting reciprocation of the piston.

`The top end of the annular pouring chamber I2 is closed by means of a plate it of refractory material having a central opening is therethrough and having the outer edge portion resting upon a ring t2 which, in turn, is secured to the side wall of the furnace. A sleeve 63 of heat resisting material is sleeved in the opening lli and is provided with an enlargement above the plate for supporting the crucible i3.- As shown in Figure 3, the enlargement is recessed, as at d4, to receive the lower end of the crucible i3 and for holding the latter in an upright position in the furnace. Seated upon the plate 40 is a ring 45 of refractory material having the inner annular wall 46 surrounding the lower end portion of the crucible and cooperating with a stop plate d1 of refractory material to form a burner chamber 48. 'Ihe plate 41 is supported upon thetop surface of the ring i5`and is formed with an enlarged opening 49 through the center thereof to provide for receiving the crucible i3. A cover 50 of refractory material is seated upon the plate 41 and cooperates with the upper portion of the crucible I3 to close the heating chamber v48.

i Upon reference to Figure 4, it will be noted that heat is generated in the chamber 13 by means of two burners 5l and 52. The two burners are predeterminedly arranged with respect to the furnace through a discharge opening 54 lo cated adjacent-the burner 5I. A

The -crucible i3 is formed of a heat resisting material and has a threaded opening through the center of the bottom wall 55 thereof for detach.v

ably receiving a valve or cap member 5S. The

member 53 is formed with a restricted discharge v opening 51 therethrough havingl an outwardly ared .portion at the upper end thereof forming a tapered valve seat 58 for engagement with the correspondingly tapered lower end of thevalve plunger M. The valve plunger lli extends upvwardly through the cover 59 for the crucible and is-slidably mountedin a bushing 60 rotatably supported in a hub ti on the cover E9. The upper end of the valve plunger is operatively con nected to a cable S2 which extends over a suitable pulley B3 and terminates in a position where it may be conveniently manipulated by the operator. It will, of course, be understood from the above that the valve plunger is operated by the action of gravity to close-the discharge port 51 in the bottom of the crucible and is manually lifted to open this port by the cable 62.

In Figure 3 of the drawings, the lower end of the bushing 50 lsshown as extending into the crucible and as having an eccentric portion t5 into which a stirring bar 65 is secured. The stirring bar is formed of a heat resisting material and extends to a position adjacent the bottom of the crucible. The bar is oscillated to agitate the molten metal in the crucible by means of a spider 61 having a hub et secured to the upper end of the bushing 50.

It has previously been stated that the atmosphere in the crucible is controlled to such an extent that the latter is free from air or oxygen and this-is accomplished herein by replacing the atmosphere in the crucible with a gas of the type which will not oxidize the metal at-the temperatures enmloyed. In the present instance, the gas is admitted through a fitting 59 in the cover 58 of the crucible and is conducted to a point immediately adacent the bottom of the crucible through a tube 1@ of a heat resisting material, such as graphite. It may be pointed out at this time that in cases where the tube assumes a position in the path of travel of the stirring bar 66, a suitable stop 1l is formed on the inner surface of the cover 59 adjacent the tube for engaging the eccentric 65 to prevent either the latter or stirring bar from contacting with the tube'10. The provision of the stop 1I is of particular importance in cases where the tube 10 is formed of graphite, or some other fragile material, since vit prevents breakage of the tube by the stirring bar.

The bearing shell i0 is supported on the platform I I and is positioned by a core 15 so that the shell is located directly below the discharge passage 51 through the bottom wall of the crucible. One type of core that may be used is shown in Figure 3 as having a base 16 recessed, as at 11, to receive the lower end of the bearing shell and having a vertical portion 18 extending axially through the bearing shell I0. 'The diameter of the vertical portion 18 is such as to provide an annular space 19 at the inner side of the bearing shell slightly greater than the thickness of the lining desired, and it is within this space that the molten metal from the crucible is discharged. The upper end of the bearing shell is protected by a cap 80 preferably of the same material as' the core, and the latter is formed with an opening 8| Y therethrough communicating with the annular space 19 to permit the molten metal to flow by gravity from the discharge port 51 into the space 19.

In order to form a highly satisfactory bearing aisance surface, it is important to guard against oxidation of the metal as it flows from the valve port El into the space 19, and this is accomplished in thepresent instance by replacing the atmosphere` in the chamber l2 with a gas characterized in that it will not oxidize the metal at the prevailing temperatures. This gas is introduced into the chamber l2 through the medium of a conduit 83 extending through the side wall of the chamber l2. As a matter of fact, with the present invention, the lining cast on the inner surface of the bearing shell is not submitted to the air until the platform ll is lowered to the dotted line position shown in Figure 3 and, at this time, the metal is sufficiently set that exposing the same to the air does not aect the quality of the casting.

Operation Assuming that the parts are in the position thereof shown in Figure 3, a metal of the type required to form the desired lining in the bearing shell is placed in the crucible i3. The atmosphere or air within the crucible is replaced by a gas which is introduced into the Crucible through the tube lli and which will not oxidize the metal at the prevailing melting temperatures. At the same'time, this gas is introduced into the pouring chamber l2 and replaces the atmosphere in this provided in the side of the pouring chamber i2 so that the operator may determine when suflicient metal has been poured to completely iill the bearing shell and to take care of the shrinkage that`exists when the metal solidifies. When the required amount of metal has been poured, the cable 62 is released and the valve plunger returns to its closed position under the action of gravity.

' The platform Il is lowered to the dotted line position thereof shownin Figure 3 and the bearing shell, with its lining land core, is introduced to -a cooling `operation (not shown herein). The

core is then're'moved from the bearing and the lining is machined to the proper dimension.

In Figure 5, I have shown a slightly modified form of core construction. In this figure, a metal tube 9B is concentrically located Within the bearing shell l0 and-is welded to the latter at the lower end thereof in the manner designated by the reference character 9 l. The external diameter of the tube 99 is sufficiently less than the internal diameter of the bearing shell to provide a space 92 slightly greater than the thickness oi the lining desired. The top of the shell is closed by means of a cover 93 having a centrally arranged opening 94 therethrough providing for the passage of molten metal into the space 92. Also, the

upper end of the tube is closed by means of' a disc 95 welded in place. With this construction, it is necessary to remove the metal tube 9i by a boring operation, but the metal core contributes materially in securing a highly eiective containing the metal adapted to be poured and top wall closed by the bottom wall of the Crucible,`

said chamber also havingA an opening in the bottom wall thereof, and a platform for supporting the mold movable from a position beneath the chamber to a position within said opening.

2. In apparatus for casting metals, a crucible `adapted to contain the molten metal and having a discharge port in the bottom wall thereof, a removable cover for the upper end of the Crucible and having a hub portion, a sleeve rotatably mounted in the hub portion and having the lower end extending into the crucible, a stirring bar secured to the lower end of the sleeve at a point ofiset from the axis of rocking movement of the sleeve, and a rod slidably mounted in the sleeve having a portion at thelower end controlling the discharge port in the bottom Wall of the Crucible.

3. In apparatus for` casting a lining in bearing shells or the like,` a chamber having openings in the top and bottom walls thereof, a platform movable from a position below the chamber into the opening of the bottom Wall of the chamber to close said opening, means for positioning the bearing shell on the platform with its axis extending vertically of the chamber, means closing the lower end of the bearing shell and cooperating with the inner annular surface of the shell to form a space having a width approximating the thickness of the lining desired, means for introducing a gas into the chamber to provide an atmosphere which is substantially free from air, and means located above the chamberfor; melting metal in the presence of an atmosphere similar to the one existing in the chamber and for discharging the molten metal through the opening in the top wall of the chamber into the annular space in the bearing shell.

4. In apparatus for casting a lining in a bearing shell or the like, a heating chamber containing a non-oxidizing gas and having an opening through the top wall thereof, means for supporting a bearing shell in said chamber with the axis of the shell extending vertically and substantially in alignment with said opening, means extending into said bearing shell and cooperating with the inner annular surface of the shell to form a space having a width approximating the thickness of the liningdesired, and a crucible also containing a non-oxidizing gas and supported above the cham- 'ber with the bottom wall forming a closure for the opening in the top wall of the chamber, said the chamber whereby the molten metal flows by gravity in the presence of a non-oxidizing atmosphere to the space within said bearing shell.

5. In apparatus for casting a lining in a bearing shell or the like, a heating chamber containing a non-oxidizing vgas and 'having an opening through the top Wall, means for supporting said bearing shell in said chamber with the axis of the shell extending vertically and substantially Vin alignment with said opening, means extending into said bearing shell andcooperating with the inner annular surface of said shell to forma space having a width approximating the thickness of the lining desired, a crucible also containing a non-oxidizing gas and supported above the chamber with the bottom wall forming a closure for the opening in the top wall of the chamber, said crucible ada'pted to contain molten metal and having a valve controlled opening in the bottom wall registering with the opening in the topwall of the chamber for discharging molten 5 metal into the space in said bearing shell, e heeting chamber surrounding the lower portion of the crucible, and e plurality of heating units arranged to discharge heating medium into the chamber surrounding the crucible substantially tangentially to the inner side wall oi' the latter chamber.

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