US1774687A - Process of metal casting - Google Patents

Description

Patented Sept. `2, 1930 f UNITED 'STATES DONALD n. WILLA'RD, or DnnvILLn ILLINOIS rnoonss'or iunrnr.. CASTING AvApplication. led November A employed on trucks, in which the hub has a steel insert therein in which the keyway by which the hub is secured to the axle is formed.

- Heretofore it has been difficult or impossible to secure satisfactory castings with 1o inserts, particularly where the inserts are oil substantial size, because of the chilling eiiect of the inserts on lthe molten metal when the latter is poured into the molds, tlie'tendency lof the two' metals to separate during'the cooling Vof the cast metal and the severestrain fupon-the structure set up during the cooling and 'shrinking of the casting, which often `results"in1m0re or less serious cracking of the cast article. Often tliercracks so formed can- 2o not be `detected until after` heat treatment and sometimes until after the casting has been put in service. By the process of my invention which forms the subject of this application, I am able to producel castings with inserts, and more particularly cast iron wheels with steel hub linings in which there is a iirm union between the insert and the cast metal.

character mentioned, I prepare a steel insert of suitable length to i'orm the lining member for the hub and of a substantially less external diameter than the hub of the wheel cavity or well communicating with the latter and adapted to contain a relatively large amount of metal. The insert is properly centered andmounted in the mold with its axis vertical and the molten castiron, which *l is commonly malleable metal, is poured into f the mold through the hollow ot the insert.

In the Vdrawings Fig. ",vertical section through ainold with a inisliedfcastingtherein and also showing the -1 lines; o -iiow-ot'the'moltenrmetalj. A

7,1927. serial No.231,s15. y

The fluid, metal flowing Vthrough the insert rapidlyheats, the latter. `During ltheyearly stages the inflowingmetal loses al# considerableportionoi' its heat to the insert, -but this portion of the mold chargemainly finds its `way into the, well,J prepared for it yas previously mentioned. fAfter the well is .substantially full, as the iow continues-the cast metal fills the bore of the insert and iiows `through the lateral or transverse passages to the exterior of the insert and `into the mold cavity proper where it sets.` `In the meantime the inserthas been heated to approximately `the temperature of the .cast metall and' has been Ywell watched by the latter so that a firm union ofthe metal of the insert andthe cast metal is secured and the two'metals are at substantially the same ytemperature during metal .oi the sprue and thev bob formed, in the well areirenioved and the cast metal( drilled flIn the accompanying drawing and innthe f following specilication I have shown and v desCr-"ilbed amold and vpreferred method for; car- In carrying out my improved process; as $30 applied to the manufacture of wheels oi' the ry nglout'myinvention andin thej following i 'l'msi ha@ deined the invention with Vthe y purposelot" claiming itas broadly `as the prior far'vvillvperrmit f, v

lL is a ragmentary f Fig; 'fis atragmentaryl view 'of a Vwheel,

ing tof-my invention; and A, Y

*Figa Seis afperspective ofthe insertiindiametric section andon an enlarged scale.

g l Inipractici'ng-myf inventionfor the produc- 'itiQn-o'f anialleablecast iron wheelawith a 1 `/sfteell insert lining, I! form the moldv andv the "cavityth'ereof-fin thelusual manner. The

"nfioldingcavity proper maybe forme'dlf'by means of a pattern designed to producethe requiredfsliape oilwheel', 'the sandofxthemold 'beingillustrated at :5, 6. l The `central bottom portionaoflthe walll of the 'mold' cavity, howpartlyin tr-ansverseas'ection;:formed accordever, is formed by a gate or core 18 supported in the sand of the cope and the upper surface of which conforms to the desired shape of the wheel. The gate or core 13 is, moreover, formed with spaced openings or passages 14 and the sand 5, of the cope with a well 15 with which said passages communicate. Suitable sand cores 11 are supported in the mold to form the hollows of the spokes 12 of the wheel.

The insert 7 which may be of soft steel, is shown as cylindrical in shape and ot dia1neter less than that of the hub of the finished wheel but suliicient to provide for a bore 8 to receive the axle shaft and a suliicient wall thickness to permit a keyway 2O (see dotted line Figs. 1 and 2) for the spline to secure the wheel to the axle, to be formed therein. The insert is also formed with transverse perforations or holes 9, the outer ends of which are countersunk as at 10. The insert is or may be supported on the gate or core 13 and centered with respect to the mold cavity before the cast metal is teemed.

The mold is centrally gated and the molten cast iron of which the body of the wheel, including the spokes, is to be formed, is poured through the bore or the insert. The insert is rapidly heated by the hot fluid metal and the latter is more or less cooled during the initial heating.

The first part of the metal entering the mold, however, and a considerable proportion of the entire charge passes through the opening 14 in the gate. or core 13 and into the well or sump 15 beneath the mold cavity proper, so that it is immaterial that this metal is partially cooled. After the well is filled, the insert in the meantime having been highly heated as above explained, the pouring is continued and the freshly poured metal 'lls the lower portion of the bore of the insert and then overflows through the opening 9 into the mold cavity proper about the insert and forms the spokes and the main portion of the hub of the wheel. Since the insert is heated to approximately the temperature of the fluid metal it no longer chills the latter and thus defective castings are largely avoided. Pouring is continued until the mold and gate 16 are substantially full. The casting is now permitted to cool and the insert cools with the cast metal. Cooling is relatively slow, however, because of the body of hot metal contained in the sump. By reason of the act that the insert is highly heated before the metal with which it is to be surrounded is in contact therewith and then cools along with the cast metal, it forms a firm union with the latter and separation of the metal and cracking during or after cooling are largely avoided. y

After the casting has sufficiently cooled it is withdrawn from the mold, the bob or mass of metal formed in the well and the sprue separated therefrom. The insert is then bored out and reamed to receive the axle and the keyway machined therein. If the original bore of the insert is of proper diameter it is suflicient to remove the cast metal therefrom. Odinarily, however, the bore S as originally formed is too small and in drilling and reaming a portion of the metal of the insert is removed as indicated in dotted lines at 18, Fig. l. In the completed wheel the insert and casting are held together not merely bythe adhesion of the metals as previously explained, but also by reason of the cast metal cores extending into the openings 9 in the insert.

I claim:

1. A wheel for trucks andthe like comprising a cast metal hub and spokes and a steel insert liner having an axial bore therein to receive an axle and transverse openings into which the metal of the casting extends.

2. A method of casting an iron article having a tubular insert therein which consists in forming a mold having a molding cavity proper and a well beneath and connected thereto, forming an insert with a central bore and transverse bores, supporting the insert substantially centrally of the mold cavity and with its central bore in communication with the well in the mold and teeming molten cast metal through the bore of the insert into the well and through said bore and the transverse bores of the insert into the mold cavity about the insert.

DONALD E. WILLARD.

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