Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Making composite or hollow article
Patent
1983-12-27
1986-12-09
Lechert, Jr., Stephen J.
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Making composite or hollow article
291567R, 291571R, 29DIG31, 251366, 251367, 251368, 419 48, 419 49, 427181, 427239, B22F 700
Patent
active
046279580
ABSTRACT:
A valve cladding method and associated system for implementation including the steps of preforming solid insert-members (22,24) of a vitreous material (having a rheological state that varys with temperature), to generally conform in shape to the cavity walls (12, 14) that are to be clad. The insert-member is fixtured (32) within the cavity to provide a generally concentric, annular space (28) of predetermined thickness and length between the insert-member and the adjacent walls to be clad, thereby defining an activation volume. This volume (28) is filled with loose metal powder (48) and vibrated to achieve tap density for a given powder blend. The activation volume is degassed, evacuated and sealed. The valve body (10') a thus loaded, is heated to a temperature at which the insert members becomes pliable, in the range from one-half to full melting temperature of the powder. Pressurization of the heated article is achieved by the use of a suitable press (50, 62) mechanical or hydraulic, with adequate configured, mated dies (52, 58). The heated valve body is placed within dies appropriate for applying a pressure-ramp-cycle to the pliable insert-members, sufficient for the insert to hydrodynamically transmit the applied pressure-pulse to the activation volume, whereby the metal powder is isodynamically compacted and metallurgically bonded to the adjacent cavity walls. After cooling in normalized fashion, the insert-member material reverts to its brittle, glass-like behavioral patterns that exist at room temperature and this reversion from pliable-to-brittle properties allows easy extraction of the insert-members.
REFERENCES:
patent: 1896939 (1933-02-01), Calkins et al.
patent: 2331584 (1943-10-01), Underwood
patent: 4065302 (1977-12-01), Turillon
patent: 4477955 (1984-10-01), Becker et al.
patent: 4562090 (1985-12-01), Dickson
Kelsey-Hayes Powder Technology Center, dated 1982 "Rapid Omnidirectional Compaction (ROC).
Gray Tool Company
Lechert Jr. Stephen J.
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