| 摘要 |
The blank comprises two differing composite materials, in coaxial layers of the same basic material, especially PTFE, with various fillers. The radially innermost layer is followed by successive outer layers produced by powder pressing, all layers being sintered together. An Independent claim is included for a bush or profiled ring, especially a ring seal, made as above. Preferred Features: A cylindrical former is surrounded by a casing, leaving an annular gap of the desired, optionally single-layer thickness. The gap is filled with powder followed by pressing. The casing is removed and the diameter is made uniform. To develop the axial form, in a similar process, collinear sections are produced in succession from individual quantities of powder, pressed onto the existing sections. Successive layers are added to a coaxial core. Alternatively, rings, especially ring-seals, are produced. These may be formed and parted in succession from the blank.
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