Liquid purification or separation – With alarm – indicator – register – recorder – signal or...
Reexamination Certificate
2001-03-01
2003-02-25
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
With alarm, indicator, register, recorder, signal or...
C210S108000, C210S139000, C210S143000, C210S171000, C210S427000
Reexamination Certificate
active
06524471
ABSTRACT:
BACKGROUND OF THE INVENTION
Many machine tools, such as cutting or drilling tools, or the like, require a supply of machining fluid to the work area during a machining operation. This fluid often must pass through small openings and must be maintained as clean as possible to ensure proper flow rates as well as proper machining operations.
To this end, a filter unit is often included in many machining fluid flow circuits associated with machine tools. The filter unit conditions the machining fluid prior to that fluid being used in a machining operation.
However, if the filter unit does not effectively filter the machining fluid, such as because the filter unit is dirty or clogged or the like, the filtering process is impaired, if not vitiated. In some cases, a malfunctioning filter unit may actually require complete shutdown of the machining operation.
Therefore there is a need to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation as efficient as possible.
The filter art has several examples of systems for maintaining filter units in efficient operating condition. Some of these examples simply periodically replace the filter unit. While effective, this can be costly in time as well as in equipment.
Therefore there is a need to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation as efficient as possible without requiring replacement of the filter unit.
Another example monitors flow characteristics of fluid flowing through the filter unit and uses changes in these flow characteristics as indicators of filter unit degradation. Some of the flow characteristics commonly used include pressure drop across the filter unit, flow rates through the filter unit, viscosity of fluid flowing through the filter unit, and the like.
While monitoring flow characteristics is effective, it has several disadvantages that prevent it from being fully effective in maintaining a filter unit in the most efficient flow condition in the most effective and efficient manner.
For instance, flow characteristics may vary with the flow state conditions (such as temperature or the like) and a change of such indicia may mean that the fluid itself has changed or that the state of the fluid has changed and not the condition of the filter unit. This will, thus, provide an erroneous signal for a filter unit change or maintenance. Such an erroneous signal may result in an unnecessary filter unit change or maintenance cycle which may be inefficient, or worse, mask conditions in the filter unit itself thereby creating a situation in which a filter unit is not services when it should be.
Still further, using fluid flow characteristics as an indicia of filter unit operation or condition may require guesswork in determining when to initiate a filter unit maintenance cycle. For example, there may be a delay time between the pressure drop across a filter unit reaching a particular level and the filter unit actually being clogged beyond an acceptable level. The pressure drop signal may either lead or lag this unacceptable filter unit condition. The fluid flow circuit operator must rely on his or her experience when using fluid flow characteristics as an indicia for monitoring filter unit operation. Again, while this is somewhat efficient, it is not the most effective way to ensure proper filter unit operation. Furthermore, a control means that is energized in response to an activator stimulated by a condition sensor is subject to further inaccuracies associated with the condition sensor itself.
Some modern machining operations can be so precise and delicate that any contamination in the machining fluid beyond a very narrow range can be extremely detrimental. Accordingly, filter unit operation must be very accurate and precise and should not rely on human interpretation of data that may only be inferentially related to the actual condition of the filter unit to determine when a filter unit is operating at maximum efficiency.
Due to problems that may be associated with contaminated machining fluid in some modern machining operations, there is a need a need to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation as efficient as possible and which can carry out filter unit maintenance in a manner that can err on the side of initiating a maintenance cycle too often rather than not often enough, yet without being unduly wasteful of time and/or resources.
Still further, using inferential type data may require taking a filter unit off line during a machining operation or servicing the filter unit before it is absolutely necessary. Servicing a filter unit before it is necessary to do so may be ineffecient. Taking a filter unit off line during a machining operation would require replacing the filter unit and perhaps stopping a machining operation while the filter unit is removed and replaced, or using an alternative filter unit while the maintenance cycle on the subject filter unit is completed. In the first case, machining time may be lost; and in the second case, extra filter units must be available. In either case, the process is not as efficient as it could be and thus could be considered as being wasteful of time and/or resources.
Accordingly, there is a need to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation as efficient as possible and that does not require a filter unit to be taken off line during the maintenance operation.
SUMMARY OF THE INVENTION
The above-discussed disadvantages and drawbacks are overcome by initiating a backwash cycle of a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation based on the number of times the machine tool is used. That is, after a preset number of machine tool uses, the filter backwash cycle is automatically initiated before the next use of the machine tool.
As a result of this filter unit maintenance procedure, there is no need to take a filter unit off line for the maintenance since the filter unit is maintained during a machine tool regularly scheduled downtime. Hence, there is no need for a backup filter unit. Further, there is no need to interpret flow characteristic data to determine if the filter unit is in need of maintenance.
The number of machine tool uses can be set to any suitable value so an efficient filter unit can be ensured. Since the filter unit does not need to be removed from operation, the preset value of machine tool uses can be set to a very conservative value without unduly effecting machine tool overall use efficiency.
TECHNICAL FIELD OF THE INVENTION
The present invention relates to the general art of machine tools, and to the particular field of machine tools that include application of a fluent medium to the work or product.
OBJECTS AND ADVANTAGES OF THE INVENTION
It is a main object of the present invention to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation as efficient as possible.
It is another object of the present invention to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation as efficient as possible without requiring replacement of the filter unit.
It is another object of the present invention to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machining operation as efficient as possible and which can carry out filter unit maintenance in a manner that can err on the side of initiating a maintenance cycle too often rather than not often enough, yet without being unduly wasteful of time and/or resources.
It is another object of the present invention to maintain a filter unit in a flow circuit associated with supplying machining fluid to a machine tool during a machin
Brown Mark E.
Cecil Terry K.
Crain Mitchell L.
Drodge Joseph W.
Shughart Thomson & Kilroy P.C.
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