Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-10-26
2001-05-22
Popovics, Robert (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S791000, C210S805000, C210S167050, C210S167150, C210S391000, C210S398000, C210S402000, C210S409000
Reexamination Certificate
active
06235209
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns filters and more particularly filters used to remove contaminating particles from cutting fluids used in metal working machining.
Large volumes of contaminated cutting liquids are generated in the machining of metal in large scale metal cutting operations such as in the manufacture of engine components in the automotive industry. These liquids are filtered to remove solid particles such as grit, metal chips, etc. in a recirculating system, which returns the filtered liquid for reuse with the machine. The volumes of liquids required for large machining installations has led to the use of indexing belt filters circulated through large tanks.
See U.S. Pat. No. 5,601,729 for an example of such filtering apparatus.
These filters allow great volumes of liquid to be filtered, but do not totally eliminate the presence of stray particles which can get around the edges of the belts, pass through tears in the belt, or otherwise get into the filtered liquid.
Even one metal chip can cause plugging of a coolant nozzle for a machine tool, creating rapid tool failure and possible shut down of the entire installation.
There is thus a need for a failsafe auxiliary filter for removing residual particles from the filtered liquid.
A particular problem associated with cutting fluids in particular is the build up of gelatinous material which has a great tendency to rapidly plug up fine filter openings, such that it is not practical to use fine screen filters to eliminate these stray particles. Also, such apparatus is often operated continuously with automatic controls, and any auxiliary filters used desirably should not require constant maintenance.
It is the object of the present invention to provide a filter and process for filtering out residual particles from filtered cutting fluids recirculated from a machining operation.
SUMMARY OF THE INVENTION
The above object and others which will be understood upon a reading of the following specification and claims are achieved by an auxiliary filter comprised of a hollow wheel member carrying a filter screen on its perimeter, the wheel continuously rotated in a sealed tank receiving under pressure the filtered liquid. The hollow wheel member has an outer cylindrical perimeter covered with a fine screen supported by wedge wire windings and a circumferential array of bars welded to the outer portion of oppositely dished hub pieces. The hub pieces are axially spaced apart to define a flow path for liquid received under pressure from the main filter apparatus and flowing through the fine screen, which is thereafter directed back to the machining center.
The screen is backwashed by a series of high pressure jets directed at the screen as it rotates past the jets. An open side of a collection trough faces the screen at the location of the spray jets, to collect dislodged material and draw the same out of the tank.
The combination of the rotation of the wheel and the cleaning effect of the backwash jets keeps the fine screen clear of both gelatinous material and any captured residual particles so as to allow continuous operation of the auxiliary filter.
REFERENCES:
patent: 785531 (1905-03-01), Weller
patent: 1712258 (1929-05-01), Compain
patent: 4772402 (1988-09-01), Love
patent: 4895647 (1990-01-01), Uchiyama
patent: 4992167 (1991-02-01), Uchiyama
patent: 5328611 (1994-07-01), Lenhart
Benefiel John R.
Popovics Robert
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