U.S. patent application number 10/017291 was filed with the patent office on 2002-06-27 for device for the purification of machining liquids for electroerosion machines.
This patent application is currently assigned to CHARMILLES TECHNOLOGIES SA. Invention is credited to Demellayer, Rene.
Application Number | 20020079213 10/017291 |
Document ID | / |
Family ID | 8170783 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020079213 |
Kind Code |
A1 |
Demellayer, Rene |
June 27, 2002 |
Device for the purification of machining liquids for electroerosion
machines
Abstract
The device for purifying machining liquids for electroerosion
machines, comprises a first ultrasonic decantation device (11) to
separate by decantation the metallic contamination particles (38)
from the machining electrode and the machined piece, a second
ultrasonic decantation device (45) of a lower power to separate the
particles (39) of said machining additive, and filtration elements
(46) to separate carbonaceous particles (41) from the decomposition
of the dielectric liquid. After filtration, this latter is remixed
with the additive particles in a mixing receptacle (47) to obtain
purified machining liquid.
Inventors: |
Demellayer, Rene; (Vernier,
CH) |
Correspondence
Address: |
YOUNG & THOMPSON
745 SOUTH 23RD STREET 2ND FLOOR
ARLINGTON
VA
22202
|
Assignee: |
CHARMILLES TECHNOLOGIES SA
|
Family ID: |
8170783 |
Appl. No.: |
10/017291 |
Filed: |
December 18, 2001 |
Current U.S.
Class: |
204/238 ;
204/273; 204/276 |
Current CPC
Class: |
B23H 1/10 20130101 |
Class at
Publication: |
204/238 ;
204/273; 204/276 |
International
Class: |
C25B 015/00; C25B
009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2000 |
EP |
00128317.5 |
Claims
1. Device for purifying machining liquids for electroerosion
machines (10) provided with an electrode (17) adapted to machine a
piece (15), the machining liquid (14) being constituted by a
dielectric liquid containing at least first particles (39) of an
additive adapted to facilitate electroerosion and second particles
(38) of contamination arising from the electrode (17) and/or from
the piece (15) and having a higher density than the first particles
(39), characterized by the fact that the device comprises at least
one ultrasonic decantation device (11) comprising a first
decantation receptacle (30) for the machining liquid (14) in which
is disposed a first ultrasonic emission member (31) connected to a
first ultrasonic generator (33) whose power can be adjusted such
that the second particles (38) decant, whilst the first particles
(39) remain in suspension in the dielectric liquid.
2. Device according to claim 1, characterized by the fact that it
comprises supply means (34, 35) for supplying contaminated
machining liquid into the first decantation receptacle (30) and at
least one opening (36) provided in this latter for discharging
purified machining liquid containing the first particles (39).
3. Device according to claim 2, characterized by the fact that it
comprises supplemental means (40) to separate third particles (41)
of contamination constituted by colloidal carbon from the
decomposition of the machining liquid, these supplemental means
(40) comprising a second ultrasonic decantation device (45) with a
second decantation receptacle (50) in which is disposed a second
ultrasonic emission member (51) connected to a second ultrasonic
generator (53), the power of this latter being adjusted such that
the first particles (39) decant, whilst the third particles (41)
remain in suspension in the machining liquid, this second
decantation receptacle (50) comprising an inlet connected to said
opening (36).
4. Device according to claim 3, characterized by the fact that the
supplemental means (40) comprise a mixing receptacle (47) with
mixing members (60), filtering elements (46) for the machining
liquid obtained by decantation at the outlet of the second
decantation receptacle (50) and arranged to retain by filtration
the third particles (41), a supply conduit (59) for the filtered
dielectric liquid from the filtration elements (46) to said mixing
receptacle (47) and extraction transport means (55) arranged to
transport the first particles (39) decanted from the second
decantation receptacle (50) into the mixing receptacle (47).
5. Device according to claim 4, characterized by the fact that said
extraction and transport means are constituted by a conveyor belt
(55) arranged in the bottom of the second decantation receptacle
(50) and extending just above the mixing receptacle (47) to
discharge the first particles (39) into this latter.
6. Device according to claim 3, characterized by the fact that the
first ultrasonic generator (33) is adjusted to a power comprised
between 10 and 50 watts, preferably between 40 and 100 watts, and
by the fact that the second ultrasonic generator (53) is adjusted
to a lower power, comprised between 1 and 30 watts, preferably
between 5 and 20 watts.
Description
[0001] The present invention relates to a device for the
purification of machining liquids for electroerosion machines
provided with an electrode adapted to machine a piece, the
machining liquid being constituted by a dielectric liquid
containing at least first particles of an additive adapted to
facilitate electroerosion and second particles of contamination
from the electrode and/or the piece and having a higher density
than the first particles.
[0002] It has been demonstrated that, during machining with an
electroerosion machine, the use of an additive in the form of a
powder having particles of the order of several microns, greatly
improves the machining performance, see for example Swiss patent
670,785.
[0003] During machining by electroerosion with powder and particles
as additives, the principal element not solved is the filtration
and purification of the used and contaminated machining liquid.
[0004] There are encountered in this latter, particles of the
additive, particles in the form of metallic spherules of the
material of the piece and of the electrode, as well as particles of
colloidal carbon in the form of submicron size in the case of
carbonated dielectric liquids.
[0005] An ideal filtration should retain only the dielectric liquid
and the particles of additive. Conventional filtrations however do
not permit obtaining the desired filtration, because a coarse
filtration (>20 .mu.m) lets pass many fine metallic spherules.
On the contrary, a fine filtration eliminates, in addition to the
metallic spherules, the additive powders. A magnetic separation
works only for magnetic metallic spherules, but not for all the
other spherules.
[0006] The present invention has for its object to overcome these
drawbacks and to provide a purification device permitting obtaining
a high degree of purification and this with means that are simple
to use and at a moderate cost. The invention is characterized to
this end by the fact that the device comprises at least one
ultrasonic decantation device comprising a first decantation
receptacle for the machining liquid in which is disposed a first
ultrasonic emission member connected to a first ultrasonic
generator whose power can be adjusted such that the second
particles decant whilst the first particles remain in suspension in
the dielectric liquid.
[0007] These characteristics permit obtaining a good purification
of machining liquids and a device of moderate cost which is simple
to use and rapid and reliable in operation.
[0008] The device moreover can comprise preferably means for
supplying contaminated machining liquid to the first decantation
receptacle and at least one opening provided in this latter for the
discharge of purified machining liquid containing the first
particles.
[0009] According to a preferred embodiment, the device comprises
supplemental means to separate third contamination particles
constituted by colloidal carbon from the decomposition of the
machining liquid, these supplemental means comprising a second
ultrasonic decantation device with a second decantation receptacle
in which is disposed a second ultrasonic emission member connected
to a second ultrasonic generator, the power of this latter being
adjusted such that the first particles decant, whilst the third
particles remain in suspension in the machining liquid, this second
decantation receptacle comprising an inlet connected to said
opening.
[0010] This embodiment is particularly well adapted for the
processing of carbonated dielectric machining liquids, such as oil,
which permit purifying to a high degree of purity.
[0011] Preferably, the supplemental means comprise a mixing
receptacle having mixing members, filtration elements for the
machining liquid obtained by decantation at the outlet of the
second decantation receptacle and arranged to retain by filtration
the third particles, a filtered dielectric liquid supply conduit
from the filtration elements to said mixing receptacle, and
extraction and transport means arranged to transport the first
decanted particles from the second decantation receptacle to the
mixing receptacle.
[0012] By these characteristics, the carbonated dielectric liquids
can be purified effectively and reconstitution of the complete
machining liquid can be carried out in a reliable and inexpensive
manner.
[0013] Other advantages will become apparent from the
characteristics set forth in the dependent claims and from the
description given hereafter of the invention, in greater detail,
with the help of the drawings which show schematically and by way
of example two embodiments.
[0014] FIGS. 1 and 2 are schematic views of a first and second
embodiment.
[0015] With reference to FIG. 1, electroerosion machine 10 is
provided with a first embodiment of the decantation device 11.
[0016] This electroerosion machine comprises a working receptacle
12 in which is contained a machining liquid 14 and a piece 15 to be
machined mounted on a work table 16. The electroerosion machine
moreover has an electrode 17 serving as a machining tool, mounted
on a spindle 18.
[0017] The machining liquid 14 is circulated and temperature
controlled in the working receptacle 12 thanks to a mixing
installation 20 comprising a pumping circuit 21 with a suction pump
22 and a heat exchanger 23 connected to a cooling water
circuit.
[0018] The machining liquid 14 is constituted by a dielectric
liquid in which are suspended first particles of an additive
adapted to facilitate electroerosion and second particles of
contamination from the electrode and/or the piece 15 to be
machined. The first particles could for example be graphite
particles of a density of 2 to 2.2 g/cm and a granulometry between
1 and 100 .mu.m, preferably between 1 and 10 .mu.m. The second
particles are generally present in the form of metallic spherules
torn off and ejected from the piece to be machined and from the
electrode during erosive discharges. Their density, greater than
that of the first particles, is comprised between 4 and 20
g/cm.sup.3.
[0019] The granulometry of these spherules is generally comprised
between 1 and 40 .mu.m.
[0020] When the dielectric liquid is of a carbonated nature, the
machining liquid can moreover comprise third particles in the form
of particles of colloidal carbon caused by the decomposition of the
dielectric liquid under the influence of the erosive discharges,
which have the tendency to flocculate in submicron particles. The
density of these third particles is less than 2 g/cm.sup.3 and
their diameter is generally less than 0.5 .mu.m. Of course these
third particles do not exist in the case of water as the dielectric
liquid.
[0021] The first embodiment of the decantation device 11 has a
decantation receptacle 30 for the machining liquid in which is
disposed an ultrasonic emission member 30 in the form of a
sonotrode. This latter is connected by a connection 32 to an
ultrasonic generator 33 of a frequency of 40 kHz and whose power
can be adjusted, for example from 10 to 200 watts. A conduit 34
provided with a suction pump 35 serves as supply means for the
contaminated machining liquid into the decantation receptacle 30.
At least one opening 36 connected to an outlet conduit 37 permits
returning the machining liquid purified from the second
contamination particles, to the electroerosion machine, either into
an attached reservoir, or directly into the working receptacle.
[0022] Ultrasound is a very effective way to place in suspension
particles of the size of the first particles of the additive
powders. The ultrasonic energy for suspending the particles must be
higher the greater is the density of the particles and the greater
is their size. It is to be noted that below a critical size, the
density has less importance than the size for suspending by
diffusion. Decantation is moreover slowed when the viscosity of the
machining liquid increases. It is thus possible to provide a
selective decantation device operated by moderate ultrasonic
energy. The power of the ultrasonic generator 30 is adjusted for
each density and viscosity of the machining liquid and each density
and size of the particles to be separated. The optimum adjustment
permits decantation and accumulation on the bottom of the
decantation receptacle, of the second contamination particles 38,
namely the metallic spherules, whilst keeping in suspension the
first particles 39 that are lighter, of the additive, such as
graphite.
[0023] The power of this generator 33 is thus generally adjusted
between 10 and 150 watts, preferably between 4 and 100 watts.
[0024] Such a decantation device suffices for the case of water as
the dielectric liquid, it can also be used in this form if it is
acceptable to let the first particles subsist with the third
particles of carbon from the decomposition of a carbonated
dielectric liquid, such as oil.
[0025] The separation and elimination of the third particles
requires a more complete purification device, of which one
embodiment is described with reference to FIG. 2.
[0026] This second embodiment comprises a first decantation device
11 identical or similar to that described with reference to FIG. 1.
It is moreover provided with supplemental means 40 adapted to
separate the third contamination particles 41 of the machining
liquid from which has already been decanted the second particles
38. These supplemental means comprise a second decantation device
45, filtration elements 46 and a mixing receptable 47.
[0027] The second decantation device 45 comprises for this purpose
a second decantation receptacle 50 in which is disposed a second
ultrasonic emitting member 51, in the form of a second sonotrode
connected by a connection 52 to a second ultrasonic generator
53.
[0028] The outlet conduit 37 of the first decantation device 11
serves as a supply conduit for the machining liquid containing the
first and third particles.
[0029] The second ultrasonic generator 53 has a frequency of 40 kHz
and its power can be adjusted for example between 1 and 30 watts,
preferably between 5 and 20 watts. Its power is thus adjusted to be
lower than that of the first generator 33. It is adjusted to
maintain in suspension the third particles 41, whilst the first
particles decant and accumulate on a conveyor belt 55 serving as an
extraction and transport means to bring these first particles 39
above the mixing receptacle 47, where they are discharged.
[0030] An outlet conduit 56 provided with a pump 57 supplies
machining liquid with third particles 41 to the filtration elements
46. These latter are arranged to retain all the third particles 41
and comprise to this effect at least one fine filter, for example a
paper cartridge filter. The dielectric liquid 58 thus purified is
conveyed by a conduit 59 into the mixing receptacle 47, where it is
mixed with the first particles by mixing members 60, such as
paddles or air circulation, etc. The purified and thus constituted
machining liquid is then returned by a pipe 61 and a pump 62 to the
electroerosion machine.
[0031] These purification devices are particularly important for
rough machining and for semi-finishing and permit eliminating the
largest metallic particles which would otherwise be very
troublesome during subsequent finish machining.
[0032] Of course, the embodiments described above are in no way
limiting and can be the subject of any modification desirable
within the scope defined by claim 1. In particular, other devices
could be added, such as washing or any other treatment of the first
additive particles leaving the second decantation receptacle 50, a
measured supplier for the first particles permitting obtaining an
exact concentration of the first particles in the machining liquid
contained in the mixer 47, an extraction device, for example a
conveyor, for the second metallic particles of contamination into
the first decantation receptacle 30. All of the purification device
could be integrated into the electroerosion machine or constitute a
unit separate from this latter.
* * * * *