Liquid purification or separation – Structural installation – Closed circulating system
Reexamination Certificate
1999-04-01
2001-08-14
Drodge, Joseph W. (Department: 1723)
Liquid purification or separation
Structural installation
Closed circulating system
C210S223000, C210S257100, C210S258000, C210S259000
Reexamination Certificate
active
06274037
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a coolant purification system and more particularly to an improved apparatus for removing foreign particles from the cooling and lubricating fluid used in machining operations.
In many types of machine operations, a coolant is supplied to the area being machined for a number of purposes. One of these purposes is to cool and lubricate the machining operation. The other and equally important purpose is to remove the machined particles as well as other foreign matter from the area where machining is occurring so as to improve surface finish.
Although in principle this appears to be simple and obvious, accomplishing these results and being able to operate the equipment over long periods without servicing presents substantial considerations. Environmental concerns also require the reclaiming of the coolant and lubricant and recirculation of it, and this adds greatly to the aforenoted problems.
In some ways, this invention relates to an improvement or an alternative arrangement for providing coolant purification to that shown in my copending United States Letters Patent of the same title, Ser. No. 09/063,017 filed Apr. 20, 1998, now U.S. Pat. No. 6,015,487, and assigned to the assignee hereof.
A prior art type of apparatus is illustrated in FIG.
1
and the effectiveness of various types of prior filtering materials utilized for coolant purification is shown in
FIGS. 2 and 3
. The apparatus shown in
FIG. 1
includes a machining station
21
having a cutting tool
22
that operates to machine the surfaces of a work piece
23
. In the illustrated embodiment, by way of example, the cutting tool
22
is a grinding wheel and the work piece
23
is a gear blank onto which gear teeth are formed by the grinding operation.
This grinding operation takes place over a catch tank
24
with a coolant supply nozzle
25
being provided so as to spray the cooling liquid to the machined area. This liquid is then collected in the catch tank
24
and is returned to a purification apparatus, indicated generally by the reference numeral
26
, where the cutting liquid is collected in a storage tank
27
. A pump
28
draws the coolant from the storage tank
27
and delivers it via the nozzle
28
to the machine area.
In the specific prior art example shown, the purification apparatus
26
comprises a centrifugal separator including an impeller element
29
that is driven by an electric motor
31
and which separates foreign particles from the coolant in a manner known. The purified coolant is returned to the storage tank
27
through a purification return line
32
.
FIG. 2
shows the typical efficiency of this type of centrifugal apparatus by indicating the NAS value. This NAS value is a standard by which the number and size of entrain particles captured by the filter are measured. On the absissa, the size of particles is shown, while on the ordinate, the NAS number is indicated.
It will be seen that the centrifugal type separator is fairly consistent in the NAS number of the particles of varying sizes, but nevertheless does not exclude as many particles as desired, particularly those in the larger sizes, such as 50-100 &mgr;m. Thus its efficiency is not great.
Another type of filter which may be employed for purifying coolant and which has a higher filtration efficiency is the diatomaceous earth type.
FIG. 3
shows the efficiency of this type of filter.
As may be seen in this figure, the efficiency is higher, particularly with larger size particles. However, this type of filter requires frequent servicing and hence is expensive to operate and does not afford long operational cycles between servicing. Also, the smaller size particles are more difficult to capture with this type of filter if reasonable flow velocities and small size of the filter are obtained.
Therefore, it is a principle object of this invention to provide an improved coolant purification system usable with machining operations that will remove with high efficiencies particles of a variety of sizes and which can be operated for long time intervals without necessitating servicing.
It is a principle object, therefore, to provide an improved coolant purification system for a machining apparatus that has high efficiency and long service life while permitting operation at lower cost.
SUMMARY OF THE INVENTION
In accordance with this invention, there is provided a coolant purification system for machining operation that includes a system for supplying coolant to the machined area and collecting the utilized coolant and purifying it. The purification apparatus includes at least a rare earth magnetic separator, bag filters, and a deep level filter that are disposed in a flow path along a coolant circulation arrangement and for returning the coolant to a storage tank for recirculation.
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Beutler Ernest A.
Drodge Joseph W.
Yamaha Hatsudoki Kabushiki Kaisha
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