Stock material or miscellaneous articles – All metal or with adjacent metals – Having metal particles
Patent
1996-07-10
1998-07-14
Jenkins, Daniel J.
Stock material or miscellaneous articles
All metal or with adjacent metals
Having metal particles
428548, B22F 702
Patent
active
057801703
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a sintered friction material for the production of friction-linked components, in particular synchronizing rings, as well as a friction-linked component, especially a synchronizing ring, with a friction coating of this sintered friction material. In the following, reference is made primarily to a synchronizing ring, without this constituting a limitation.
2. Description of the Related Art
Synchronizing rings, e.g. for motor vehicle gear boxes, are subject to high stresses and have to meet a multitude of requirement. For sufficiently short shifting times, it is necessary that the friction coating of the synchronizing ring has a good frictional behavior. In addition, the synchronizing ring must have a sufficient mechanical and thermal stability. It is also practical if the friction coating is easy to process mechanically since the friction surface must be produced to fit exactly. For obvious reasons, these requirements generally cannot be met by one single type of material. Thus, it is common knowledge to manufacture synchronizing rings in two layers, so that the friction coating layer is designed for favorable friction conditions while the material serving as a carrier, has a high mechanical and/or thermal stability.
From DD-PS 89 727, we are familiar with a friction component for oil flow, for example a synchronizing ring, which is produced with the powder-metallurgy method from an iron powder to which powdered nickel, copper, lead as well as graphite are added. The use of lead can result in considerable danger to the health during production as well as when the friction component is in use. In addition, because of the comparatively low graphite content, it has turned out that this material has a tendency to show strong signs of adherence, particularly under high stresses, which manifest themselves in the form of an uneven moment build-up and scoring.
From DE-GM 73 42 680, a synchronizing ring of sintered steel is known, which has a thin injection-molded coating of molybdenum as friction surface. On the one hand, molybdenum as injection-molding material is an expensive material and, on the other, the synchronizing ring generally must be ground to fit the required surface dimensions. As a result of the high degree of hardness of the molybdenum coating, this generally results in high tool wear.
From DE-OS 42 03 321, a sintered friction material for friction-linked components, in particular synchronizing rings, is known, which has a graphite share of 15-30 percent by volume and which contains, among other things, ceramic components. To be sure, a synchronizing ring with such a friction coating does exhibit the desired friction behavior. However, it cannot be ruled out that strong signs of abrasion will occur on the clutch as a result of the share of ceramic components. If applicable, this can also lead to an uneven momentum build-up.
It is the object of the invention to create a sintered friction material for friction-linked components, a material showing good friction behavior without the herewith connected disadvantages of the initially described kind.
SUMMARY OF THE INVENTION
The solution according to the invention is a sintered friction material with an iron-based matrix and a solid lubricant, which contains 0.5 to 10 percent in weight molybdenum in relation to the matrix, and 20-50 percent in volume graphite as solid lubricant. In one embodiment according to the invention, the molybdenum content can be 1 to 5 percent in weight preferably 1 to 2 percent in weight. It can be useful if the graphite content is 25 to 45 percent in volume. The component parts here can contain production-related and/or unavoidable impurities.
Surprisingly, it has turned out on the one hand that mixing a sintered metal material, generally used as a construction material, with a high share of solid lubricant has the desired friction qualities. On the other hand, signs of adhesion and abrasive wear of the friction surface of the clutch are avoided for
REFERENCES:
patent: 3853572 (1974-12-01), Herron et al.
patent: 4654381 (1987-03-01), Kang et al.
patent: 5370725 (1994-12-01), Kawamura et al.
Romero, O.: "Clutch technology moves into gear boxes". In: Metal Powder Report, vol. 48, No. 6, Jun. 1993, UK, pp. 30-33.
Eckhardt Marion
Gonia Detlev
Schneider Lothar
Jenkins Daniel J.
Sintermetallwerk Krebsoge GmbH
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