Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2000-06-20
2001-06-19
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S268000, C264S270000
Reexamination Certificate
active
06248280
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of this invention lies within the art of respirator filter cartridges. It particularly relates to respirator particulate filters which have a filter media such as filter paper that is pleated and emplaced in a cartridge. The cartridge and paper is then sealed to prevent air passage around the filter media. It particularly relates to the field for the cartridge as well as the method of applying the seal.
2. Description of the Prior Art
A number of filter cartridges have evolved over the years. Many of the filter cartridge designs incorporate a filter cartridge having pleated filter media therein. The reason for the pleated filter media is due to the large surface area which the filter media encompasses thereby allowing for significant inflow of air that is to be filtered through the cartridges.
Such pleated filters generally rely upon pleats of material that are pleated and then bonded together so as to allow for a gap between the pleats of the media. As can be appreciated, if the filter media is at all clogged or filled with such items as sealant or other obstructions, the efficiency of the filter drops significantly.
In the past, there has been a significant problem in sealing filter media to a cartridge. The sealant often times is dripped or disposed onto the filter media. This creates closures or obstructions of the filter media so that it can not function correctly. Various methods have been employed to emplace a sealant with the filter media in the cartridge thereby preventing any migration or channeling of air around the filter media.
The prior art has tried to solve the problem of creating a seal without wetting the filter media with sealant. However, it has failed in great measure to eliminate the adhesive residue on the exterior of the filter and often times on the filter media itself.
Such designs as a plurality of spokes from a central hub extending radially outwardly have been utilized. The thought being that the spokes from the radial hub can disperse liquid sealant to the exterior for sealing. In such a manufacturing process, the adhesive is put on a central hub and allowed to centrifugally move along the spokes to the exterior and then be deposited against the interface of the filter media and the filter cartridge.
With such designs, the sealant is dispensed onto the center hub and after curing and drying remains on the hub. This is not only clearly visible but often times migrates to the filter media itself.
Other designs dispense the sealant onto the top outer surface of the filter body. This design also relates upon a centrifugal force to clear the sealant off the dispensing surface. However, because of the surface tension and the fact that very little energy is imparted into the sealant near the center of rotation a residual amount of sealant remains on the dispensing surface. The remaining sealant is left to cure on the exterior of the filter body.
Other methods have been provided in order to seal filter media to a cartridge. However, when such devices have been tried, they have been costly. For instance, in some cases, the adhesive or sealant is disposed around the edge of the media prior to manufacturing the entire cartridge. Also, dynamic means of maintaining the adhesive or sealant around the media during the manufacturing process have been tried. None have been eminently successful as to maintaining a clean filter media as well as a cartridge.
This particular invention overcomes the deficiencies of the prior art by creating a unique seal in a filter assembly. The seal is created by injecting a pressurized sealant into a rotating assembly. The sealant forms a seal between the inner wall of a two piece molded body and a pleated filter disk.
The result of the process is a respirator filter which is clean and free of adhesive residue. Furthermore, it provides for a clean application and non-clogging of the adhesive on the filter media itself or on the exterior surfaces of the respirator filters. The result is that a substantially un-clogged filter media is provided with a proper seal at the exterior surfaces of where the filter media interfaces the interior of the cartridge. This sealant is a reliable sealant to create the seal while at the same time avoiding the substantial problems of the prior art.
SUMMARY OF THE INVENTION
In summation, this invention provides a filter cartridge and process for sealing filter media to the interior of the cartridge with a sealant that is formed while injecting a sealant into a rotating filter cartridge and then curing the sealant.
More particularly, the process incorporates a seal that is dynamically disposed into a filter cartridge. The sealant is injected by a pressurized process through the movement of a sealing nozzle into an area to allow for the spray of sealant into an interfacing area between a cartridge wall and the filter media.
The injection of the stream of sealant is then curtailed through a snuff back valve which prevents further dripping of the sealant onto the filter media. This is by means of valve spools in the valve which retract to draw the sealant material in the spray nozzle of needle into the interior so that it does not trail off the end of the nozzle.
The cartridges are rotated at approximately 800 revolutions per minute (rpm) while the nozzle or needle is spraying sealant thereinto. This rotation maintains the sealant against the walls of the cartridge as well as allowing for subsequent cure.
The nozzle, once placed in position allows the stream of sealant to travel over the filter media and not touch it, and at the same time strike the inside of a molded cartridge body. Due to gravity and centrifugal forces, the sealant flows downwardly and outwardly to create a uniform seal between the body of the cartridge and the filter media.
The foregoing will be seen to be an effective sealant providing a unique cartridge for respirator purposes as seen in the following specification.
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Kern John J.
Osborne Anthony V.
Bacou USA Safety, Inc.
Bethel George F.
Ortiz Angela
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