Seal for a joint or juncture – Process of static sealing – Pipe – conduit – or cable
Reexamination Certificate
1999-02-02
2001-09-11
Mah, Chuck Y. (Department: 3626)
Seal for a joint or juncture
Process of static sealing
Pipe, conduit, or cable
C277S616000, C277S622000, C277S626000, C492S046000
Reexamination Certificate
active
06286836
ABSTRACT:
TECHNICAL FIELD
The invention relates to sealing of an entry port for rollers for use in a variety of industrial machines.
DESCRIPTION OF THE BACKGROUND ART
Steam-heated and induction-heated rollers are used in the paper making, printing, paper, film, and foil converting industries. Some examples are: web heating rollers, drying rollers and drums, laminating rollers, embossing rollers, and cast film extrusion rollers.
Steam-heated rollers are actually pressure vessels, especially at higher temperatures. The internal construction of both steam-heated and induction-heated cores can be quite complex and expensive in order to provide the temperature uniformity needed. In addition, a considerable amount of auxiliary equipment is needed to power or heat the roller.
Heat pipe technology has been used to control heat in various kinds of equipment used in space, remote monitoring stations and wherever heat transfer is required. A basic industrial heat pipe roller is disclosed in Noren, U.S. Pat. No. 3,700,028. As reported in Noren, “How Heat Pipes Work,”
Chemical Engineering
, Aug. 19, 1974, acceptance of heat pipes in industry has been slow. Since that time a number of heat pipe constructions have been patented, often for small rollers used in office copiers and printers. Progress has remained slow, however, for industrial and large equipment applications.
International Publication Nr. WO 98/31194, published Jul. 16, 1998, discloses a heat pipe roller having an annular cavity between an inner cylindrical core and an outer cylindrical shell. To allow evacuation of the cavity and injection of an evaporative medium into the cavity, a charging port with a threaded plug is provided in one end of the roller. In the prior art, brazing or solder was used to seal the port after evacuation of air from the cavity and flowing of the medium into the cavity.
Prior art heat pipes are also of the gun-drilled type, in which one or more elongated heat pipe tubes are inserted in longitudinally extending gun-drilled holes in a roller core.
A primary cause of failure in heat pipes is the formation of non-condensable gases. Only one percent air or other gas in the heat pipe reduces heat pipe efficiency approximately fifty percent. Non-condensable gases can form as a result of corrosion, contamination, loss of vacuum, reaction of the medium with wicking materials, or degradation of the medium.
The maintenance of the seal on a charging port is important in preventing non-condensable gases. Such a seal should be easily assembled, and yet withstand internal pressures experienced by the heat pipe. The seal must be compatible with a charging sequence in which the heat pipe cavity is evacuated of air, the medium is flowed into the cavity and the port is sealed.
SUMMARY OF THE INVENTION
The invention is incorporated in a seal assembly and a method of sealing an entry port to a heat pipe.
The port is sealed with a metal-to-metal seal in which a plug is forced into a hole by torquing a screw behind the plug. The plug is made of a softer metal than the metal forming a hole in which the plug is received. The material forming the hole forms a circular, substantially sharp edge, either at 90° or slightly chamfered, without chips, burrs or other irregularities.
The plug is made of a metal that is approximately 30% softer than the metal forming the hole, so that the plug deforms and not the hole. On the other hand, if the plug material is too soft, the seal will relax over time. Brass, copper and nickel plugs are preferred for use with a hole formed in steel.
The screw has one or more longitudinally extending vents to allow a vacuum to be drawn from the heat pipe cavity as the seal is being applied.
The invention can be applied to a roller heated by hot oil, steam, hot water, electricity or to rollers that are cooled by water or other media, and is particularly useful where heat is to be transferred to or from a moving web of material.
The invention allows a heat pipe roller to be charged in the horizontal position. The invention allows reuse of the heat pipe roller. It also allows recharging in the field.
Other objects and advantages, besides those discussed above, will be apparent to those of ordinary skill in the art from the description of the preferred embodiment which follows. In the description, reference is made to the accompanying drawings, which form a part hereof, and which illustrate examples of the invention. Such examples, however, are not exhaustive of the various embodiments of the invention, and, therefore, reference is made to the claims which follow the description for determining the scope of the invention.
REFERENCES:
patent: 2074591 (1937-03-01), Rood
patent: 2154331 (1939-04-01), Hathcock
patent: 2941475 (1960-06-01), Blair
patent: 4807514 (1989-02-01), Gartzmuller
patent: 5145008 (1992-09-01), Yun
patent: 5292298 (1994-03-01), Scannell
patent: 5529313 (1996-06-01), Malks
patent: 5653479 (1997-08-01), Henderson
patent: 5821499 (1998-10-01), Crimmins et al.
patent: 5823091 (1998-10-01), Collingborn
U.S. application No. 08/783,597, Hyllberg et al., filed Jan. 13, 1997.
American Roller Company
Mah Chuck Y.
Patel Vishal
Quarles & Brady LLP
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