Abstract Actual sealing is done by a metal-filled Teflon polytetrafluoroethylene ring which in practice comprises about 40 per cent virgin Teflon mineral filled with about 60 per cent by weight powdered bronze or glass fiber. The Teflon in sheet form is bonded to a sheet of an elastomer such as synthetic rubber previously patterned on its compression surface to accommodate distortion occurring when the ring is installed. Along opposite margins of the composite sheet, double-coated tapes are applied, these being covered with liners. From the composite sheet, strips are slit or punched in dimensions to fit a grooved piston or the like. Preferably these strips are provided with step-joints cut at the ends of the strips which extend toward the margins to which the double-coated tape and liners have been applied. The rings thus formed are handled flat until applied in their respective grooves. At the time of application, the liner and/or tape is pulled from each ring end, leaving a thin coating of adhesive adhering to the ends of the ring adjacent the stepjoint. When the ring is pushed into its groove, this adhesive engages the bottom of the groove and maintains the split ring in assembly with the grooved piston.
A packing ring comprising a flat strip of generally rectangular cross-section having an outer lamination of polytetrafluoroethylene and an elastomeric inner lamination, said ring having complementary end portions each half as wide as said strip and having parallel edges in said end portions, whereby when said packing ring is installed and radially compressed in a packing groove with said inner lamination wholly within said groove and said outer lamination in contact with a part other than the part which contains the groove, with said ends in laterally lapping relationship, the compression of said inner lamination and the lapping relationship of said complementary end portions causes said ring to compensate for extrusion of said outer lamination and for wear of said outer lamination by movement of said complementary end portions with respect to each other in the direction along said strip to maintain the radial dimension of said installed ring unchanged, without failure of the seal at said ends.
Claim 2
Dependent Claim
158 words
A packing ring comprising a flat strip of generally rectangular cross-section having an outer lamination of polytetrafluoroethylene and an elastomeric inner lamination, said ring having complementary end portions each half as wide as said strip and having parallel edges in said end portions, whereby when said packing ring is installed and radially compressed in a packing groove with said inner lamination wholly within said groove and said outer lamination in contact with a part other than the part which contains the groove, with said ends in laterally lapping relationship, the compression of said inner lamination and the lapping relationship of said complementary end portions causes said ring to compensate for extrusion of said outer lamination and for wear of said outer lamination by movement of said complementary end portions with respect to each other in the direction along said strip to maintain the radial dimension of said installed ring unchanged, without failure of the seal at said ends.
Claim 3
Dependent Claim
16 words
A packing ring in accordance with claim 1 in which the outer lamination is mineral filled.
Claim 4
Dependent Claim
26 words
A packing ring according to claim 1 in which the synthetic elastomeric lamination has a grooved interior compression face on which said adhesive coating is disposed.
Claim 5
Dependent Claim
32 words
A packing ring in accordance with claim 1 in which the inner surface of said inner lamination is provided with an adhesive coating at least in proximity to said complementary end portions.