US 4,414,028 A · Method of and apparatus for sintering a mass of particles with a powdery mold

Abstract

A particulate mass to be sintered is imbedded in a mold which comprises a porous mass of particulate refractory material enclosed within a flexible membrane. Six press units are provided for applying compressive pressures externally to the mold, together or in sequence, whereby to subject the sinterable mass to pressures in the respective directions, under the control of a preprogrammed control unit which receives clock pulses from a source and stimulates the respective press units. A flexible heating coil imbedded in the mold is supplied with alternating current from a source to inductively heat up the sinterable mass and the adjacent mold material, to enable sintering to occur. The sinterable mass may have been precompacted into a self-supporting so-called "green compact", or it may be supported in a self-supporting shell carried within and forming part of the mold. The mold preferably comprises three layers having characteristics chosen so as to assist in heating up the sinterable mass uniformly.

Claims13

Dependent claims

A method of sintering a sinterable mass of particles, comprising the steps of:

(a) imbedding the sinterable mass in a porous mass of particulate heat-resistant material, said porous mass constituting a force-transmitting medium for transferring pressures uniformly to said sinterable mass,
(b) disposing said porous mass in pressure-reception relationship in a multi-axial compression system capable of applying plural independent axial pressures externally to said porous mass along a plurality of axes intersecting generally at a point in said sinterable mass, each axis lying generally orthogonal to the adjacent axes,
(c) applying thermal energy sufficient for sintering said sinterable mass;
(d) in a first stage of sintering, applying said independent pressures, set at a first magnitude, simultaneously along said axes to multi-directionally compress said sinterable mass through the medium of said porous mass,
(e) in a second stage of sintering, applying said independent pressures set at a second magnitude, which is greater than said first magnitude, successively and cyclically along said axes, and
(f) in a third and final stage of sintering, applying said independent pressures set at a third magnitude, which is greater than said second magnitude, simultaneously along said axes.

3 more elements

Dependencies are inferred from the claim text.

Method of and apparatus for sintering a mass of particles with a powdery mold

Life of this patent

Method of and apparatus for sintering a mass of particles with a powdery mold

Life of this patent

Abstract

Claims13