Abstract A composite heavy-duty bushing, such as a bearing bushing or bearing race (FIG. 4) consists of a high load-bearing or working portion consisting of a sleeve composed of sintered powdered high-performance alloy and a supporting or mounting sleeve subjected to less concentrated or intense loads made of an inexpensive base metal, such as sintered powdered iron. These two sleeves are separately briquetted, and then assembled telescopically. This assembly is then sintered while the sleeves are thus united, and finally hot-forged in an axial direction. This forging operation densifies the composite assembly from the sintered briquette density of about 75 percent to a final density of about 98 percent and at the same time upsets the ends of the base metal sleeve into an adjacent end bevel in the high performance alloy sleeve, hereby clinching the two sleeves inseparably to one another. Photomicrographs of longitudinal sections of these composite bushings spanning the joint between the two sleeves (FIG. 6) after subsequent carburizing and hardening heat treatment show a superior interlock therebetween resulting from a migration of the metals into one another across the interface therebetween into an intermediate zone of the intermingled metals which encircles the interphase. Torsion tests performed on such sections show adequate strengths without failure along the junction surfaces which compare favorably with the strength of similar single solid metal bushings. These photomicrographs also show that such a complete bond has been achieved along the central or axial portion of the joint, that the beveling of the ends is not essential in order to form a joint of adequate strength. Such beveling at the ends is therefore optional and is provided as an additional means of retention of the inner sleeve inside the outer sleeve.
A composite heavy-duty bushing comprising - an inner sleeve composed of substantially solidified sintered powdered metallic material and having generally-cylindrical outer and inner surfaces, - an outer sleeve composed of a different substantially solidified sintered powdered metallic material and also having a generally-cylindrical outer surface and having a generallycylindrical inner surface telescopingly engaging said outer surface of said inner sleeve and hot-forgedly joined thereto along a generally-cylindrical interface therebetween, - one of said sleeves being composed of a high-strength metallic material and the other sleeve being composed of a lower-strength base metallic material, - minute portions of one of said metallic materials extending irregularly past minute portions of the other of said metallic materials across said interface in interlocking engagement with one another and forming an approximately hollow cylindrical intermediate zone of the interflowed metallic materials encircling said interface, - said base metallic material being iron and said high-strength metallic material being a manganese-molybdenum iron alloy.
Claim 2
Dependent Claim
156 words
A composite heavy-duty bushing comprising - an inner sleeve composed of substantially solidified sintered powdered metallic material and having generally-cylindrical outer and inner surfaces, - an outer sleeve composed of a different substantially solidified sintered powdered metallic material and also having a generally-cylindrical outer surface and having a generallycylindrical inner surface telescopingly engaging said outer surface of said inner sleeve and hot-forgedly joined thereto along a generally-cylindrical interface therebetween, - one of said sleeves being composed of a high-strength metallic material and the other sleeve being composed of a lower-strength base metallic material, - minute portions of one of said metallic materials extending irregularly past minute portions of the other of said metallic materials across said interface in interlocking engagement with one another and forming an approximately hollow cylindrical intermediate zone of the interflowed metallic materials encircling said interface, - said base metallic material being iron and said high-strength metallic material being a manganese-molybdenum iron alloy.
Claim 3
Dependent Claim
19 words
A composite heavy-duty bushing, according to claim 1, wherein said high-strength metallic material is a nickel-content manganese-molybdenum iron alloy.
Claim 4
Dependent Claim
18 words
A composite heavy-duty bushing, according to claim 1, wherein said high-strength material is a nickel-free manganese-molybdenum iron alloy.
Claim 5
Dependent Claim
54 words
A composite heavy-duty bushing, according to claim 1, wherein one of said sleeves has bevels extending toward the ends of said sleeves at the opposite ends of said generally-cylindrical interface and wherein the metallic material at both ends of the other sleeve extends transversely across said interface into abutting interflowed engagement with said bevels.