Sheet-like gasket with overlapped peripheral portions

Details Sheet-like gasket with overlapped peripheral portions Sheet-like gasket with overlapped peripheral portions

1995-07-18

1997-06-03

Cummings, Scott

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

277198, F16J 1510

Patent

active

056346450

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Technical Field
The present invention relates to a sheet-like gasket which is useful for sealing a flange connection portion of a pipe joint, a passage connection portion of a fluid apparatus, or the like, and more particularly to a sheet-like gasket formed of a material having a layered internal structure such as expanded graphite or porous polytetrafluoroethylene (PTFE).
2. Prior Art
Sheet-like gaskets of such types which are conventionally known include those having the following structures: having a layered internal structure such as expanded graphite superior in heat resistance, airtightness and stress relaxation property, or porous PTFE superior in contamination preventing property for fluid, into a sheet-like shape by pressurization, and then stamping the sheet-like material into an annular shape, so as to form a sheet-like base member 10 having a predetermined shape. protrusions 11 are formed on both front and back faces 10a and 10a, i.e., on tightening faces of a sheet-like base member 10 having a predetermined shape made of expanded graphite, porous PTFE, or the like, so that a high face pressure is locally applied to the contact surface. a sheet-like base member 10 having a predetermined shape made of expanded graphite, porous PTFE, or the like are compressed from both front and back faces for forming recesses, so that a high-density layer 13 is formed between the recess portions 12 and 12 on the front and back faces. portion of a sheet-like base member 10 having a predetermined shape made of expanded graphite, porous PTFE, or the like is compressed by using a mold, etc., so as to form a high-density layer 13. In FIG. 27, the high-density layer 13 is formed only on the inner circumferential face portion of the sheet-like base member 10. Alternatively, the high-density layer 13 may be formed only on an outer circumferential face portion, or on both inner and outer circumferential face portions. portion of a sheet-like base member 10 having a predetermined shape made of expanded graphite, porous PTFE, or the like, a local sheet base member 14 made of the same material as that of the sheet-like base member 10 is overlapped, and then pressurized so that the thickness of the whole structure is uniform. In FIG. 28, the local sheet base member 14 is overlapped only on the outer end portion of the sheet-like base member 10. Alternatively, the local sheet base member 14 may be overlapped only on the inner end portion. faces of a sheet-like base member 10 having a predetermined shape made of expanded graphite, porous PTFE, or the like with coating members 15 and 15 made of PTFE or the like, or by, as shown in FIG. 30, coating the entire face of the sheet-like base member 10 with a coating member 15 made of PTFE or the like. portion and an inner circumferential face portion of a sheet-like base member 10 having a predetermined shape made of expanded graphite, porous PTFE, or the like with a covering member 16 made of a metal, PTFE (which is not porous), or the like.
In general, in a sheet-like gasket in which a sheet-like base member 10 is formed of a material having a layered internal structure such as expanded graphite or porous PTFE, as is apparent from an enlarged cross-sectional structure shown in FIG. 32, both front and back face portions 10a and 10a of the sheet-like base member 10 are in a high-density and high-alignment (high alignment: a state in which alignment in one direction is attained, so that, for example for expanded graphite, flaky expanded graphite particles are tidily arranged in a stacked manner) state. Accordingly, as indicated by b in the figure, leakage from the inside to the front and back face portions 10a and 10a hardly occurs, but, as indicated by a in the figure, penetration leakage via the internal layer to the outside tends to easily occur.
With the aforementioned view points, the above-listed conventional sheet-like gaskets will be individually studied. In the structures of (A) and (B), leakage from the contact surface, i.e., contact-surface

REFERENCES:
patent: 456243 (1891-07-01), Fromm
patent: 595867 (1897-12-01), Watson et al.
patent: 3231289 (1966-01-01), Carrell
patent: 3580765 (1971-05-01), Grove
patent: 4293135 (1981-10-01), Wallace
patent: 4535996 (1985-08-01), Cardis et al.
patent: 4572522 (1986-02-01), Smagatz
patent: 5222744 (1993-06-01), Dennys
patent: 5236203 (1993-08-01), Uchida et al.
patent: 5413359 (1995-05-01), Latty
Machine Design: "Seals", 3rd. ed.; pp. 74-81.

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