Machine tools abstract
A work tank for machine tools for receiving the machining fluid
comprising a fixed part and a movable part which retracts to move
the tank away from the work area when it is necessary to remove
a workpiece.
Machine tools claims
We claim:
1. A work tank for machine tools designed to receive a machining
liquid for machining a workpiece, said work tank comprising a fixed
part and a mobile part, said fixed part being a bottom and a rear
wall of said tank and said mobile part being a front wall and at
least part of one of a pair of side walls of said tank, said mobile
part having a first machining position, in which it is sealed against
said fixed part to form said tank, said mobile part further having
a second inoperative position, in which it is raised above said
fixed part.
2. The work tank according to claim 1 further comprising articulated
fittings to raise said mobile part.
3. The work tank according to claim 2 wherein said articulated
fittings raise said mobile part along a plane parallel to said fittings.
4. The work tank as described in claim 2 wherein said articulated
fittings include two pairs of parallel arms, said parallel arms
are coupled to said fixed part at one end, said parallel arms are
coupled to said mobile part at the other end.
5. The work tank according to claim 2 wherein said articulated
fittings are connected to mechanical devices to move said mobile
part.
6. The work tank according to claim 5 wherein said mechanical
devices include an electromechanical power unit with at least one
spring and counterweight.
7. The work tank according to claim 1 wherein said mobile part
includes a device functioning in conjunction with a blocking device
in said second position.
8. The work tank according to claim 5 wherein said mechanical
devices include an electromechanical power unit with a hydraulic
jack.
9. The work tank according to claim 5 wherein said mechanical
devices include an electromechanical power unit with a pneumatic
jack.
Machine tools description
The present invention refers to work tanks for machine tools, designed
to receive the machining fluid and a workpiece and comprising a
fixed and mobile part.
It also refers to these machines, in particular electroerosion
machines equipped with such a tank.
In machine tools of known type, in particular electroerosion machines,
the work tank completely surrounds the machining area during operation.
In order to give free access to this area to facilitate the removal
and re-fitting of workpieces, various solutions have been proposed
in the present state of technology:
a tank with collapsible sides as described for example in CH 551
904 but their dismantling gives rise to real waste of time;
a tank with walls constructed in the form of an accordion as described
for example in CH 400 408 DD 26 53 47 EP 347 716 or made up of
telescopic elements as described for example in the Japanese publication
2-048113 so as to retract at the level of the work table. However,
these systems are relatively expensive and there is a risk that
the metallic waste from the machining will jam the mechanisms that
fold up the walls, and make them less watertight. Finally, the folded
walls form an obstacle around the workpiece clamping table, and
even though the obstacle is not high it hinders the transfer of
the workpiece to and from a pallet placed at the level of the clamping
table;
a tank or an ensemble made up of four walls, which is mobile and
can be pivoted laterally between a machining position and an inoperative
position away from the machining area, has described for example
in DE 32 13 013 FR 2 266 571. This arrangement has at least two
disadvantages: it is necessary to protect the path of pivoting for
safety reasons, and the space occupied by the tank or mobile part
in the inoperative position could better be used for placing devices
involved in workpiece or tool changing, or for other devices;
a tank that retracts into the base of the machine by sliding along
a central column or along pillars, as described in FR 1 235514
DE 1 217 005 and U.S. Pat. No. 3 612 810;
a tank with a fixed rear wall, along which slides the mobile ensemble
formed by the three other walls and the bottom, between the working
position and a withdrawn position in the base, as described for
example in DE 25 14 899;
a tank with a fixed part comprising the bottom and the rear wall,
and a mobile part consisting either of the three other walls and
sliding as above between a working position and a withdrawn position
in the base, as described for example in EP 123 792 or consisting
of the front wall and the adjacent parts of the side walls and sliding
along the fixed parts of the side walls, as described in the Japanese
publication 2-00027.
However, these three latter solutions have the disadvantage of
making use of sliding devices that during machining are in contact
with the liquid containing metallic fragments, causing a lack of
reliability due to the risk of jamming, furthermore, is necessary
to wait for the end of the with drawal movement for the level of
the work table to be freed. Also, there tracted walls clutter up
either the rear of the working plane,or the base, whereas these
spaces are very useful for placing, for example, workpiece or tool
changer robots or magazines, machining liquid injection or filtration
devices, containers for used liquid, or for used wire in the case
of wire cutting machines.
The present invention proposes to overcome these disadvantages
by creating a tank with a fixed part and a mobile part, in which
the mobile part retracts so that the work area is freed as soon
as the retraction operation begins and neither the areas around
the machining plane nor the base are obstructed.
This objective is attained by a machining tank that has a fixed
part and a mobile part. According to the invention, the fixed part
comprises the bottom and the rear wall and in certain cases an adjacent
part of the side walls of the tank, and the mobile part comprising
the front wall and at least a part of the adjacent side walls. This
tank is designed to be able to occupy a low position, called working
position, in which it is fitted in a tight manner to the fixed part
to form the said tank, and a high position, called inoperative position,
in which it is raised above the fixed part.
To allow this movement, the tank advantageously includes articulated
fittings to raise the said mobile part. By means of a particularly
advantageous structure, the said articulated fittings are designed
to raise the mobile part parallel to itself. They preferably include
a pair of parallel arms, coupled to the fixed part on the one hand
and to the mobile part on the other hand.
To facilitate the maneuvering of the mobile part, the said articulated
fittings can be associated with mechanical devices to move the said
mobile part. These mechanical devices can include at least one spring
and/or at least one counter weight and/or at least one hydraulic
or pneumatic jack. They can also include an electromechanical power
unit.
Advantageously includes a part working in conjunction with a device
for blocking or stopping the mobile part of the tank in the high
position to ensure the safety of operators when said mobile part
is raised.
In a particularly advantageous variant of the present invention,
the mobile part in the high position rests against the element of
the machine's base structure into which the tool holder is fitted,
i.e. the machining head. The blocking device mentioned above can
then be mounted on this element and include a component actuated
by a spring or by any other mechanical, pneumatic, hydraulic, magnetic
or electric system of known type, so as to fit into a housing provided
in the mobile part of the tank and to hold the latter in the high
position. When the movement raising the mobile part is carried out,
it is preferable for the machining head and the work table carrying
the tank to occupy a predetermined relative position.
By means of a particularly advantageous form of construction, the
machining head can have an overhang equipped for example with a
rim, or profiled so as to hold the mobile part; this element is
actuated for example by the numerical control of the machine, in
such a way as to fit the rim under the mobile part.
To prevent the machining liquid that is still wetting the mobile
part from dripping off when the mobile part is raised, the latter
is equipped along its lower edge with a sloping gutter which constitutes
a drainage channel for the liquid and leads it to a container.
The electroerosion machine according to the invention is characterized
in that it includes a machining tank of this type.
The present invention will be better understood with reference
to a preferred form of construction carried out on a die sinking
electroerosion machine as in the annexed drawings, in which:
FIG. 1 represents a front view of the first form of construction
of an electroerosion machine according to the invention, in which
the tank is in the low position;
FIG. 2 represents this machine in the same position but seen from
the side;
FIG. 3 represents a front view of this electroerosion machine in
which the tank is in the high position;
FIG. 4 represents this machine in the same position, but seen from
the side;
FIG. 5 represents a front view of a second form of construction
of an electroerosion machine according to the invention, is in the
low position;
FIG. 6 represents this machine in the same position, seen from
the side;
FIG. 7 represents a front view of this machine with the tank in
the high position;
FIG. 8 represents this machine in the same position, seen from
the side.
With reference to the figures, the electroerosion machine represented
comprises a base 10 which supports a column 11 carrying a machining
head 12. Mounted on the base 10 is a table with crossed XY movements
that is mobile along two orthogonal axes X and Y thanks to slides
13a and 13b associated with axial displacement mechanisms that are
of known type. These mechanisms include for example two stepping
motors and two ball screws driven by these motors.
Mounted on the machining head 12 is an electrode holder 14 that
can move vertically along a Z axis and can rotate around this axis
in two opposite directions represented by the double arrow R. The
mechanisms allowing displacements of the machining head are also
of known type. They include for example a first stepping motor coupled
to a ball screw to generate the displacement along the Z axis and
a second stepping motor coupled to a ball screw which meshes with
a toothed wheel with an axis parallel to the Z axis to generate
a rotation of the machining head in either of the two directions
as shown by the arrow R.
The workpiece clamping table 13 called the work table, is fixed
to the cross table XY and is embedded in the bottom 16 of a work
or machining tank 15. The machining tank is consists of a fixed
part and a mobile part. These two parts are fit together in a tight
manner in order to contain a dielectric liquid during the operating
phase. According to a variant not shown, the work table 13 can constitute
this bottom 16. The fixed part comprises the bottom 16 and the rear
wall 17 of the tank 15 such as the part 9 of the side walls which
is adjacent to the rear wall 17. These parts 9 are advantageously
provided with an oblique profile, fitted particularly for facilitating
the tight fitted connection of the mobile and fixed parts of the
tank. Moreover, according to the preferred embodiment illustrated
in that example, they extend under the bottom of the tank, such
as to screen the upper slide of the XY table, and slide X is the
variant represented in the drawings. The mobile part consists of
the front wall 18 and the parts 19 and 20 of the two side walls.
Two pairs of articulated arms 21 and 22 parallel with each other
to form a parallelogram, and make it possible to displace the mobile
part of the tank 15 from a low position, called the machining position,
shown in FIGS. 1 and 2 to the high position, called the operative
position, shown in FIGS. 3 and 4. The arms 21 and 22 are coupled
on the one hand to the lateral extremities integral with the fixed
part and on the other hand to the mobile parts 19 and 20 of the
side walls. In the construction represented by way of example in
FIGS. 1 to 4 the displacement f the mobile part from its low position
to its high position is done by means of a hydraulic or pneumatic
jack 23 whose body is fixed to the bottom 16 or to the rear wall
17 of the tank and whose piston rod is fixed to one of the articulated
arms, in that example, to the arm 22. It is of course understood
that this mechanism could be replaced by any other mechanism having
an equivalent function. The mobile part of the tank can also be
raised manually. For this purpose, the front wall 18 is equipped
with two handles 24. It would also be possible to provide a winch
with a crank handle, a counter weight, etc. To prevent the remaining
dielectric from flowing and dripping into the work area when the
mobile part is raised, the latter is equipped along its loweredge
with a sloping gutter which constitutes a drainage channel for the
liquid and leads it to a collecting tank that is not shown. In its
raised position, the mobile part of the tank 15 is held by a blocking
device 25 which is, in that example, made up of a curved leaf spring
which is supported by or fits into an appropriate depression of
the front wall 18 (see FIG. 4).
FIGS. 5 to 8 represent a form of construction of the electroerosion
machine defined above which differs from the construction illustrated
by FIGS. 1 to 4 in so far as the tank raising mechanism has two
pairs of arms close together and masked by hoods 40 and 41 and also
an electric motor 42 which actuates the arms. The other components
of the machine are identical and will not be described in detail
They have the same references as those attributed to the corresponding
components of the machine represented by FIGS. 1 to 4.
The present invention is not limited to the forms of construction
described, but can be subject to various modifications and take
the form of different variants that are evident to an expert in
the art.
Hence, the fixed part of the work tank can be constituted only
by its bottom and rear wall and the mobile part can be compressed
of the front wall and all of side walls.
The device of the present invention can be mounted on a diesinking
machine whose electrode is not rotary. The work table 13 can be
separated from the cross table XY by the bottom of the machining
tank and fixed or embedded in the latter, or it can even actually
constitute the latter. This work table can be fixed, while the machining
head is actuated for example along crossed X and Y axes perpendicular
to the Z axis.
According to other variants, the device of the present invention
can be mounted on a wire-electrode electroerosion machine and in
the high position can rest against the carriage carrying the upper
head.
The device according to the present invention can also be mounted
on a machine that has no column, but a gantry, or having any other
known type of construction. |