Machine tools abstract
A device for regenerating the cooling emulsion (3) stagnating in
the tanks (2) of the machine tools, characterized in that the proliferation
of anaerobic bacteria responsible for the evil-smelling deterioration
of said emulsion (3) is suppressed by the use of a plurality of
oxygenation pipes (1) submersed in the cooling liquid and capable
of producing air microbubbles that ensure a sufficient and uniform
oxygenation of the emulsion and avoid the formation of the typical,
continuous lubricating oil layer above the coolant (3). Said oxygenating
microbubbles causes also a continuous displacement of the cooling
emulsion (3) that reduce the risk of dissociation of the emulsion
itself. Pipes (1) submersed in coolant (3) in tank (2) have holes
(5) allowing internal pressurized air to escape regularly and to
oxygenate cooling liquid (3). Said pipes (1) are coated outside
by a sponge rubber layer (4) made of a material resistant to the
oil components of the emulsion so as to ensure a slow, homogeneous
production of air microbubbles which bubble through the sponge rubber.
Said microbubbles are formed by compressed air having a low pressure
barely enough to cause air to escape regularly from pipes (1).
Machine tools claims
What is claimed is:
1. Apparatus for regenerating a cooling emulsion stagnating in
a tank of machine tools by aeration to suppress proliferation of
anaerobic bacteria, the apparatus comprising:
source of comprised air;
a plurality of aeration pipes fluidly connected to the source of
compressed air and having a plurality of holes;
each pipe having an outer surface which is coated with sponge rubber
layer made of a material resistant to oil components of the cooling
each hole having the same diameter and being located along the
lower generatrix of each pipe such that air escaping therefrom crosses
substantially all the sponge rubber coating and establishes a uniform
spreading of microbubbles; and
wherein the pipes which are closer to the source of compressed
air have a lower number of holes than the pipe which are remote
from the source of compressed air such that the quantity of microbubbles
produced by each pipe is substantially the same throughout the tank.
2. The apparatus according to claim 1 wherein each pipe has a
closed first end and a second end fluidly connected to the source
of compressed air.
3. The apparatus according to claim 1 wherein the pipes are located
transversally to the tank in order to ensure a maximum spreading
of the microbubbles and a homogenous oxygenation of the cooling
4. The apparatus according to claim 1 wherein the pipes are made
are made of plastic material.
5. The apparatus according to claim 1 wherein the pipes include
magnets for anchoring the pipes to the tank.
6. The apparatus according to claim 1 wherein the source of compressed
air is structured and arranged to supply air continuously or in
a timed manner in intervals of not longer than two hours, for a
7. The apparatus according to claim 1 wherein compressed air is
drawn directly from a central system.
8. The apparatus according to claim 1 wherein compressed air is
supplied by an independent blower.
9. The apparatus according to claim 1 wherein in use, the pipes
are secured 20-40 cm under the surface of the cooling emulsion.
Machine tools description
CROSS REFERENCE TO RELATED APPLICATION
This is the 35 U.S.C. 371 national stage of international application
PCT/IT99/00206 filed on Jul. 6 1999 which designated the United
States of America.
FIELD OF THE INVENTION
The present invention relates to the mechanical industry and more
particularly the machine tools.
BACKGROUND OF THE INVENTION
It is known that machine tools need cooling liquids to avoid the
overheating of the tools during machining. Such cooling liquids
(thereafter "coolants") are basically water emulsions
comprising emulsifying oil and/or other lubricating means.
Machine tools are usually provided with at least a coolant tank
and at least a recirculating pump that draws the coolant from the
tank for supplying the same to the tool to be cooled.
A common problem in this field is given by the fast deterioration
of such cooling emulsions. This is mainly due to the fact that coolant
has generally a concentration of emulsifying oil ranging between
3 and 5% and is continuously in contact with the lubricating oil
of the guides, the consumption of which in the current machine tools
is about one and half litre a day.
Such lubricating oil is not recycled and is collected in the coolant
tank with the result that a layer of lubricating oil is formed on
the surface of the coolant in a few days, thus preventing the latter
from being oxygenated and helping the fast proliferation of anaerobic
bacteria that are the main cause of bad smells and fast deterioration
of the emulsion itself.
Problems due to the removal of the lubricating oil from the surface
of the cooling emulsion in the tank have been not solved effectively
until today. An approach uses a suitable electric apparatus so-called
A drawback of such oil separator is that not all the oil is recovered
but a portion thereof sticks at the metal wall of the tank. If it
is true that the service life of the emulsion is prolonged in this
way, it is also true that the tank needs a careful maintenance after
the replacement of the emulsion to avoid that the mould produced
by the bacteria pollutes quickly the new cooling emulsion.
SUMMARY OF THE INVENTION
This invention seeks to overcome such drawbacks by providing a
device to be installed in the tanks of the cooling liquid in the
machine tools capable of preventing anaerobic bacteria from being
formed and avoiding both the fast deterioration of the cooling emulsion
and bad smell emission.
This is accomplished according to the invention by providing a
device able to generate air microbubbles that guarantee the constant,
uniform oxygenation of the cooling emulsion, particularly when the
machine is still and the coolant is prone to become stagnant.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the invention will result from the following
detailed description with reference to the accompanying drawings
that show some preferred embodiments thereof only by way of a not
In the drawings:
FIG. 1 is a top plan view of the device according to the invention
installed in the tank of a machine tool, with partial sections of
the oxygenation pipes;
FIGS. 2 and 3 are a longitudinal section and a cross section of
FIG. 1 respectively;
FIG. 4 is a cross section of an oxygenation pipe according to the
DETAILED DESCRIPTION OF THE INVENTION
The device according to the invention operates essentially as an
oxygenation device that increases the life time of the cooling emulsion
in addition to the avoidance of the proliferation of anaerobic bacteria,
and ensures a slight, continuous displacement which makes the oxygenation
With reference to the drawings listed above the device of the invention
includes a plurality of pipes 1 submersed in coolant 3 of tank 2
and perforated so as to allow the internal pressurized air to escape
regularly and to oxygenate liquid cooling medium 3. In the embodiment
shown each such pipe has a closed end while the other end is connected
to the compressed-air source.
According to a peculiar feature of the invention, such pipes are
coated outside by a layer 4 made of sponge rubber withstanding the
oil components of the emulsion which guarantees a slow, homogeneous
production of air microbubbles. Such microbubbles consist of compressed
air having a low pressure barely enough to cause air to escape regularly
from pipes 1 that have holes 5 which are spread out therealong so
that a suitable pressure is guaranteed from the nearest to the remote
portions from the air source. In fact, it should be appreciated
that the air escaping from pipes 1 as microbubbles does not perform
any mechanical function or remove any deposit of any kind. It just
bubbles through the emulsion to oxygenate it.
More specifically pipes 1 which are near the compressed-air source
have a lower number of holes 5 than the number of holes 5 of remote
pipes 1 so that the quantity of microbubbles produced by each pipe
is the same throughout tank 3.
With particular reference to FIG. 3 such holes 5 all having the
same diameter, are located along the lower generatrix of each pipe
1 so that air escaping therefrom crosses almost all the sponge rubber
coating 4 and establishes an uniform spreading of microbubbles all
over the surface of the coating.
According to the invention such pipes 1 are preferably disposed
transversally to tank 3 in order to ensure the maximum spreading
of the microbubbles and a homogeneous oxygenation of the emulsion.
In the mechanical industry the machine down time to replace the
emulsion and to clean the tank settles the cost. Therefore, an immediate
advantage of the present invention is that the machine should be
stopped only for the installation of the device mentioned above.
The described oxygenation device is specifically conceived to be
adapted to the typical shapes of the different tanks of the machine
tools without any modification of the tanks. Pipes 1 are preferably
made of plastic material and then can be easily cut to fit them
to the size of the tanks.
It should be noted that the life time of a well concentrated emulsion
varies as a function of the kind of water used: for example, if
water is very hard, the emulsion is prone to dissociate very quickly
to the order of two weeks. Upon dissociation the emulsion gives
out a typical, bad smell of sulphur dioxide, and its lubricating
action for cooling the cutting tool fails.
A further drawback deriving from the deterioration of the emulsion
is that the emulsion after dissociation becomes highly oxidative
and corrosive for the guides of the machine tools, above all for
framed guides not visible from the outside.
Moreover, as the disposal of the emulsion should take place according
to precise anti-pollution regulations having large cost, the extension
of the operating life of such cooling, lubricating liquids is particularly
useful and advantageous.
The optimum oxygenation provided by the device according to the
invention is independent of the thickness of the oil layer floating
on the emulsion. Therefore, any disposal of oil can also be made
with still standing machine by using cheaper means than the oil
separator mentioned above.
It should be appreciated that the oxygenation of the cooling emulsion
by the movement imparted thereto by pumps is a solution that does
not overcome the problem of the separation of water and emulsifying
oil. In fact, with such a solution the oxygenation is not sufficient
in any case in view of the volume of the displaced emulsion. The
approach of increasing the oxygenation by a faster, turbulent displacement
of the emulsion does not improve the oxygenation process because
the lubricating oil for the guides and the emulsion could mix together
with the risk of a chemical contamination..
To sum up, it is necessary to avoid that sulphur-containing oil
from the guides keeps in contact with the same portion of emulsion
all the time. To this end, the device of the invention breaks the
oil film and displaces the underlying portion of the emulsion so
as to oxygenate it.
It is important that the installation of the oxygenation pipes
1 is well dimensioned for a correct use of the device according
to the invention. To this end the pipe-lining requires that pipes
1 are anchored to the bottom of the tank, for example by magnets
secured to the pipes. Moreover, the supply of compressed air may
be continuous or timed, e.g. by intervals not longer than two hours,
for a sufficient oxygenation.
As the air consumption corresponds approximately to a small air
loss from a normal blowing gun, still another advantage of the invention
is given by that the compressed air can be provided directly by
the central system (if any) or by an independent blower for each
machine tool which is driven during the machine down time, for example
overnight, during holidays, etc.
For example, the blower may be derived by a ducted fan, an oxygenator
for aquarium, a compressor for hobby, a compressor for refrigerator,
The use of the device according to the invention makes the emulsion
unalterable in time because moulds consisting of dead anaerobic
bacteria having the density of the gelatine and attacking the emulsion
to make it useless in 3-5 days since the formation of the first
colonies are suppressed.
The tanks are kept clean and degreased by the device of the invention,
and the emulsion still keeps the distinctive smell of the fresh
composition after many months in spite of the machine down times.
A further advantage of the invention is that the emulsion is not
deteriorated quickly and is not attacked by bacteria even if it
is prepared at a wrong concentration, and when further emulsion
is then added at a different concentration, the two compositions
are blended and take an intermediate concentration.
Baffle or gate means are often applied at different heights to
concentrate oil in a limited area of the tank. Such means made usually
of metal sheet limits the movement of the emulsion, and then it
is advisable to remove it (very easily) to achieve the best result.
Finally, in case of very deep tanks, it is not necessary to anchor
pipes 1 to the bottom of the tanks according to the invention but
it is sufficient to secure them 20-40 cm under the surface of coolant
3 to have good oxygenation and displacement. This is particularly
advantageous also in view of the fact that the air pressure of the
oxygenator should be barely enough to cause the microbubbles to
escape. Therefore, the greater the depth, the higher the air pressure.
The present invention has been described and illustrated according
to a preferred embodiment thereof, however, it should be understood
that those skilled in the art can make equivalent modifications
and/or replacements without departing from the scope of the present