Patent Application
20050167356
The present invention relates to a filter manufacturing process using an RF receptive filter adhesive. This invention also relates to a filter assembly that uses RF receptive adhesive and which is suitable for oil filter and other applications.
Fluid filters incorporate a filter assembly for filtering debris from fluid flowing through the filter. One typical arrangement for oil filter applications includes a filter assembly having a paper pleated filter media captured between a pair of opposing end discs. A center tube may be arranged between the end discs and the filter media to provide further structural rigidity to the filter assembly.
A roll of filter media is fed into a pleating machine to create folds in the media. The filter media contains a material that provides stiffness to the filter media when exposed to heat. The pleated filter media enters an oven where it is preheated to partially cure the material and the filter media. The partially pleated filter media enters a station where it is cut to length and the ends are secured to form a cylindrical shape. A center tube may be inserted at this time.
An adhesive that provides desirable chemical and temperature resistance, such as plastisol, is dispensed onto end discs, which is installed onto the ends of the filter media to form an assembly. The filter media and end disc enter an oven where the adhesive is heated and cured or partially cured. The material in the filter media also finishes curing at this time. The oven where the assembly is finally cured may be of a considerable length, and the assembly may require exposure of several minutes in the oven.
The prior art process described above requires a long assembly line to incorporate the various heating steps in the process. Moreover, the filter media and end discs must be handled several times to partially cure the end disc to the filter media one at a time. Finally, the long exposure of the filter assembly to high temperatures in the oven eliminates the ability to use non-metallic end discs, which could be destroyed at high temperatures typically experienced in the final curing oven. Therefore, what is needed is a filter manufacturing process that reduces the cost and space associated with the long assembly line and numerous ovens while enabling use of non-metallic end disc materials.
The inventive filter manufacturing process includes the steps of dispensing an adhesive including an RF receptive material, and arranging the adhesive between an end disc and a filter media. The adhesive is exposed to RF waves to excite the RF receptive material, which generates heat to cure the adhesive. The adhesive need only be exposed to the RF waves for several seconds to generate sufficient heat to fully cure the adhesive.
The RF receptive material and the adhesive generates heat of a desired level only in a localized area. As a result, the filter media may be fully cured during the early processing stages without becoming damaged by subsequent heating. In one example, the adhesive is a vinyl adhesive plastisol. The end discs may be arranged into the filter media and cured one at a time or simultaneously. The filter assembly is passed through a curing tunnel in which an RF transmitter is arranged proximate to the adhesive. The strength of the RF waves diminishes in proportion to the square of the distance from the RF transmitter to the RF receptive material. As a result, the RF waves do not generate a significant amount of heat in portions of the filter media away from the adhesive.
Accordingly, the above invention provides a filter manufacturing process that reduces the cost and space associated with the long assembly line and numerous ovens while enabling use of non-metallic end disc materials.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
A flow chart depicting the inventive filter manufacturing process 10 is shown in
The filter media is unrolled and pleated, as indicated at 12. The filter media is heated, as indicated at 14. The filter media may be heated to the extent that the material in the filter media is fully cured. The filter media is cut to size and the free ends are joined together to form a cylindrical shaped filter, as indicated at 16. A center tube may be installed into the filter media, if desired, as indicated at 18. An adhesive having an RF receptive material is dispensed, for securing end discs to the filter media as indicated at 20. End discs are installed onto the filter media, as indicated at 22. The adhesive is cured, as indicated at 24, by briefly exposing the adhesive to RF waves. The filter assembly comprising the filter media and end discs is ready for final filter processing, as indicated at 26, immediately following the curing of the adhesive.
Referring to
The cured filter media is fed through a machine 34 that cuts the filter media into desired lengths and forms the filter media into a cylindrical-shaped filter element 35. The free ends of the filter element 35 are joined together, for example, by clips 36, which forms a central opening 38. A center tube 44 may be inserted into the central opening 38 at station 42 to provide additional structural support for the filter element 38 during filter operation, however, a center tube 44 need not be used.
A dispenser 50 deposits an adhesive 52 onto first 56 and second 58 end discs at a station 46. While metal end discs are typically used, paper or other non-metallic end discs may now be used with the inventive manufacturing process due to the reduced temperatures and exposure as compared to the prior art process. Referring to
One end disc 56 and 58 may arranged onto the filter element 35 and cured one at a time. Alternatively, both of the end discs 56 and 58 may be arranged onto the filter element 35 and the adhesive on the end discs 56 and 58 simultaneously cured. An adhesive 52 having a greater viscosity enables the end discs 56 and 58 to be installed onto the filter element 35 and cured simultaneously since the adhesive will run more slowly. A lower viscosity adhesive may also be used, however, the end disc 56 and 58 may have to be cured and installed onto the filter element 35 one at a time to avoid the adhesive 52 from running or wicking into the filter media.
Separate end discs may be eliminated and instead provided by the adhesive. For example, adhesive plastisol may be inserted into a mold and an end of the filter element 35 inserted into the adhesive. The adhesive end disc then may be cured upon exposure to RF waves.
The filter element 35, discs 56 and 58, and adhesive 52 together comprise the filter assembly 59. The filter assembly 59 is fed through a curing tunnel 60 to heat and cure the adhesive 52. The curing tunnel 60 of the inventive filter manufacturing process 10 is shown in more detail in
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
