Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for other than internal combustion engine – or...
Reexamination Certificate
1998-07-23
2001-06-05
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for other than internal combustion engine, or...
C277S631000, C277S652000, C277S938000, C072S307000, C029S460000, C029S888300, C228S173500
Reexamination Certificate
active
06241256
ABSTRACT:
TECHNICAL FIELD
The present invention relates to large-diameter gaskets. More particularly, the present invention relates to large-diameter gaskets for heat exchangers and to apparatus and methods for the manufacture of large-diameter gaskets.
BACKGROUND OF THE INVENTION
Heat exchanger are large pieces of mechanical air and fluid handling equipment having large cross-sectional dimensions. Adjacent components of heat exchanger connect together at flanges with bolts. Gaskets seal the connection of the adjacent components to prevent leakage from the heat exchanger.
Periodically, or as necessary, the gaskets that seal the connections in heat exchanger are replaced. It has been the practice in the industry for the new gaskets to be custom manufactured, typically by a gasket distribution company local to the facility requiring the new gaskets. There are several reasons for this practice. Generally, no major company manufacturing small-diameter gaskets provides large-diameter gaskets for heat exchanger. Small diameter gaskets are generally available in a wide range of inner and outer diameters, generally having overall diameters of up to about twelve inches. For large-diameter applications, generally of twelve inches and greater, there are a number of different gasket patterns, and replacement typically is an infrequent occurrence. It is impractical to inventory replacement gaskets for large diameter applications.
In contrast, the smaller gaskets for fluid flow control devices are used more frequently, and manufacturers of gaskets maintain dies in a wide range of inner and outer diameters to manufacture small-diameter gaskets up to approximately twelve inches. Such smaller gaskets are easier to store in warehouses and ship to distributors or end-users for installation. The large-diameter gaskets however are more difficult to handle and store due to their size, the flexibility of the gasket, and the brittle nature of the sealing material of the gasket.
Presently, replacement large-diameter gaskets are generally made by gasket distributors which are local to the site requiring replacement gaskets. The replacement gaskets are made with a metal ring overlaid with sealing materials. The ring is cut using a gasket template laid over a large plate of sheet metal. The sealing material is typically cut from a sheet of calendared graphite having a layer of adhesive. Such product is available commercially in a number of thicknesses and densities. The sheet is laid on a table and the ring is placed on the adhesive layer. The gasket is then cut from the sheet. The ring is turned over and placed on a second sheet to coat the opposing side of the ring. The remaining materials are generally scrapped as waste, which comprises an additional cost. The gasket is then moved carefully to the heat exchanger and installed.
While these locally-manufactured gaskets have provided replacement gaskets for large-diameter sealing applications, there are drawbacks to their usage. These drawbacks include the inability to incorporate into the large diameter gaskets the improvements found in modern small diameter gaskets. The uniformity of the custom-made gasket varies one to another, and the overall quality depends upon the experience of the technician manufacturing the gasket.
Accordingly, there is a need in the art for an improved heat exchanger gasket, together with an apparatus and method of manufacturing improved heat exchanger gaskets. It is to such that the present invention is directed.
SUMMARY OF THE INVENTION
The present invention meets the needs in the art by providing an apparatus and method for manufacturing a large diameter heat exchanger gasket. The apparatus comprises a holding press and a bending press which are disposed coaxially and spaced-apart for receiving an elongate band therethrough. Each press is selectively positionable in a first position for allowing the elongate gasket band to move longitudinally through the holding press and the bending press and a second position holding the band rigidly from movement relative to the respective press. A drive press is disposed coaxially with and spaced-apart from the holding press and operative in opposite mode to the holding press and the bending press, whereby the elongate gasket band is held tightly when the holding press and the bending press is in the first position. The drive press is also movable longitudinally from a first position to a second position for moving a portion of the elongate gasket band through the bending press. The bending press is pivotable from a first position to a second position at an oblique angle relative to a longitudinal axis of the elongate band for bending the band at an oblique angle relative to the longitudinal axis. Pneumatic cylinders move the respective presses. The holding press and the bending press operate in unison to move to the second position to hold the elongate band during a bending step when the bending press pivots from the first position to the second position. The drive press operates in a holding mode for gripping the elongate gasket band while the holding press and the bending press are in the first position in order for the drive press to move a portion of the elongate band longitudinally through the bending press.
The apparatus of the present invention provides a preferred embodiment of a large diameter gasket, comprising an elongate, narrow band having distal ends joined together to define a closed loop with a diameter exceeding twelve inches. A jacket of a sealing material enwrapps substantially the entire band. A patch of the sealing material enwrapps a portion of the loop where the distal ends join together.
The present invention provides a method of manufacturing a large diameter gasket, in which an elongate band moves a predetermined distance to advance a portion of the elongate band into a bending press. An adjacent holding press and the bending press hold the elongate band firmly. The bending press pivots adjacent the holding press from a first position to a second position to bend the portion of the band at an oblique angle laterally. The elongate band is released from being secured in the holding press and the bending press. The steps are repeated until a loop of a predetermined diameter is formed. The loop is separated from the band, and opposing distal ends joined together to form a large-diameter gasket.
Objects, advantages and features of the present invention will become apparent from a reading of the following detailed description of the invention and claims in view of the appended drawings.
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Grafoil Engineering Design Manual; Union Carbide Corp., 1987; vol. I; “Sheet and Laminate Products”, pp. 3, 4, 7, 9, 10, 14.
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Flexitallic Catalog 278, Single and Double-Jacketed Gaskets/Metallic and Non-Metallic Gaskets, Flexitallic Gasket Company, Inc., Deer Park, Texas, pp. 1-8, undated.
Flexitallic, Special Heat Exchanger Gaskets, Flextallic Gasket Company, Inc., Deer Park, Texas, pp. 38-39, undated.
Metallic Jacketed Gaskets, Technical Data Sheets, Leader Gasket, Inc., Houston, Texas, pp. 3-1, 3-2, 3-3, 3-4, 4-1, and 4-2, undated.
Tighten Up With M&P Graphonic™ Gaskets—An Innovative Aolution For Controlling Fugitive Emissions, Marine and Petroleum Mfg., Inc., Houston, Texas, undated.
Meyer Reid M.
Suggs Steven M.
Acadia Elastomers Corporation
Baker, Donelson Bearman & Caldwell
Knight Anthony
Pickard Alison K.
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