Machine tools abstract
An operating head for automatic machine tools of the type mounted
on a structure for moving along a set of three Cartesian axes having
a first support, fitted to the structure for rotation around a first
axis, and a chuck unit fitted to the first support, wherein the
chuck unit is interchangeable and projects from the first support,
and is designed to allow angular positioning around a second axis
orthogonal to the first axis. The first support includes a power
transmission system for the chuck unit. The connection of the chuck
unit to the first support permits changing from rough to finish
work by simply replacing the chuck unit, rather than replacing the
entire operating head.
Machine tools claims
What is claimed is:
1. An operating head for automatic machine tools comprising: a
first support adapted for rotation about a first axis and mounted
on a structure movable in a set of three Cartesian axes; a second
support rotatably mounted to the first support for rotation about
a second axis orthogonal to the first axis; an interchangeable chuck
unit, mounted to project from the second support; a power transmission
system having a coupling connected to a drive connected to a chuck
of said chuck unit; first means for controlling rotation of the
second support about the second axis; and locking means for selectively
locking the second support against rotation about the second axis;
wherein said second support has a coupling means for detachably
connecting to the chuck unit; said chuck unit being connectable
to said power transmission system via a detachable coupling comprising
parts brought into contact with each other and clamped with a straight
2. An operating head according to claim 1 wherein the locking
means comprises a chamber having walls made of a deformable material
and fluid means for introducing a pressurized fluid into the chamber
to deform the walls and frictionally lock the second support.
3. An operating head for automatic machine tools, comprising: a
first support rotatably fitted on a structure, the first support
rotatable around a first axis, the structure movable along a set
of three Cartesian axes; a second support fitted to the first support,
the second support being rotatable around a second axis; an interchangeable
chuck unit projecting from the second support; first means for controlling
the rotation of the second support around the second axis; and locking
means for locking the second support in a rotated position, the
locking means including a chamber having walls made of a deformable
material fitted around the second support, the chamber connected
to a fluid means for introducing a pressurized fluid into the chamber
for deforming the chamber walls and locking the second support in
the rotated position; wherein said second support has a detachable
coupling means for connection to the chuck unit; said chuck unit
being connectable to said power transmission system via a coupling
comprising detachably cooperating parts.
4. An operating head according to claim 3 wherein the interchangeable
chuck unit is one of a motorized chuck and a power chuck.
5. An operating head for an automatic machine tool having a structure
movable along a set of three Cartesian axes, the operating head
comprising: a first support rotatably fitted to the structure for
rotation about a first axis; a chuck unit fitted to the first support,
the chuck unit projecting from the first support and being rotatable
to different angular positions around a second axis, the chuck unit
being removable from the first support and having a chuck for holding
a tool; the first support includes a power transmission system and
means for connecting the power transmission system to the chuck
unit; and a rotating support fitted to the first support, the chuck
unit being mounted on the rotating support by means for detachably
coupling, the rotating support including means for detachably coupling
the power transmission system to the chuck unit, and the rotating
support controllable by means for controlling rotation of the rotating
support around the second axis.
6. An operating head according to claim 5 wherein the power transmission
system comprises a drive having shafts and bevel gear pairs, connected
on one side to a motor system of the structure, and having a coupling
on the other side for connection to kinematic devices provided on
the chuck unit.
7. An operating head according to claim 6 further comprising a
ring-shaped chamber connected at one side to exhaust devices and
on an opposite side to a duct terminating adjacent a coupling of
a tool, the ring-shaped chamber fitted to the structure.
8. An operating head according to claim 7 wherein the duct is
connected to the ring-shaped chamber by a coupling, the duct being
integral with and rotatably connected to the chuck unit.
9. An operating head according to claim 5 further comprising a
chamber having walls made of a deformable material fitted around
the rotating support, the chamber being connected to fluid means
for introducing a pressurized fluid into the chamber.
Machine tools description
This invention relates to an operating head for automatic machine
tools with a projecting interchangeable chuck unit.
In particular, the head in accordance with the invention comprises
a support that rotates around a first axis, which said support incorporates
a power transmission system, and a kinematic mechanism for angular
positioning of the chuck unit around a second axis, usually orthogonal
to the axis of rotation of the support.
A plate integral with the chuck assembly is fitted with couplings
designed for the connection of the said support.
The chuck assembly incorporates a power unit or motorised chuck
suitable to perform high-speed finishing tasks.
This characteristic allows the operator to change over from roughing
to finishing tasks without replacing the entire head (as is necessary
with known equipment in which the chuck assembly is mounted on a
fork support), merely by replacing the chuck unit, a much quicker
and cheaper operation.
The automatic machine tools used to perform chip-forming tasks
such as milling, contouring, etc., comprise a support that moves
along three orthogonal axes on which an operating head with two
degrees of freedom is mounted; the said operating head carries a
tool unit consisting, for example, of a chuck or motorised chuck,
on which the tool required for each task is mounted.
The structure and characteristics of these operating heads vary
considerably, depending on whether the job in hand is a high-power
task, performed with a roughing tool which rotates at a relatively
low speed (max. 3000-5000 rpm) and removes large amounts of material,
consequently discharging considerable reactive forces onto the structure,
or a finishing/milling task, performed with a tool which rotates
at high speed (up to 15000-30000 rpm).
The stresses to which the tool is subjected during these various
types of work, which are discharged onto the structure and the upstream
devices, require the use of chucks with different characteristics
and dimensions, which means that different operating heads have
to be manufactured.
In accordance with the present state of the art, when the operator
wishes to change over from a high-power task to a finishing task,
the entire operating head must be replaced, involving very high
These factors lead to an increase in overall costs, due not only
to the longer production times but also to the need to have two
or more operating heads complete with the corresponding kinematic
mechanisms, if not two or more separate machines used for roughing,
finishing or other complementary tasks.
This problem is solved by the present invention, which relates
to an operating head for automatic machine tools that includes an
interchangeable chuck unit fitted to project from a support, which
said unit can be replaced quickly and easily with a chuck of different
For example, as the power transmission system and angular positioning
devices of the chuck are built into the support to which the chuck
unit is fitted, the operator can switch from a power chuck to a
medium- or high-speed motorised finishing chuck very quickly, with
no need to replace the entire head.
This invention will now be described in detail, by way of example
but not of limitation, by reference to the annexed figures in which:
FIG. 1 shows a cross-section of the operating head in accordance
with the invention
FIG. 2 is a side view in partial cross-section of the operating
head illustrated in FIG. 1 showing the arrangement of the couplings
which lock the various chuck assemblies and the corresponding hydraulic
and electrical power supplies which drive the automatic operating
FIG. 3 schematically illustrates the interchangeable chuck unit,
on which a motorised chuck is fitted
FIG. 4 shows the plate fitted to the chuck unit for connection
to the corresponding support.
In FIG. 1 no. 1 indicates an operating head in accordance with
the invention, fitted to a sleeve 2 in such a way that it can rotate
around a first axis identified as "C".
The head comprises a support 3 fitted to the sleeve via bearings
4 a chuck unit 5 being mounted on the said sleeve. Interchangeable
chuck unit 5 may be a chuck, as illustrated in FIG. 1 or a motorised
chuck, as illustrated in FIG. 3.
A shaft 6 connected to motor systems not illustrated in the figure,
transmits motion via a bevel gear pair 7 to a second, inclined shaft
8 which, via another bevel gear pair 9 rotates a shaft 10.
A coupling of known type is fitted at the end of shaft 10 to transmit
motion to shaft 11 of another bevel gear pair 12 fitted to the
chuck unit and connected to power chuck 5.
The invention is not limited to the configuration illustrated,
but also covers all equivalent solutions.
For example, in the case of power transmission systems, the invention
will not be limited to the solution with an inclined shaft, but
also extends to heads with other types of transmission, such as
those with parallel and/or orthogonal shafts and the like.
The chuck unit is shaped in such a way as to form a coupling for
connection to a body or support 16 with a set of pins or shanks
14 which are gripped by gripper elements 15 of known type fitted
to support 16 to lock chuck 5.
Support 16 is fitted with toothing 17 which is engaged by corresponding
toothing 17' present on the body of the chuck, and acts as a location
plate for the correct positioning of the chuck.
Alternatively, in order to position the chuck unit precisely in
relation to support 16 different devices can be fitted instead
of the reference toothing, such as pins inserted into corresponding
seatings in the adjacent piece or other systems.
A set of rapid couplings of known type 25 and 26 is fitted to the
plate which constitutes the interface between the chuck unit and
its support; the said couplings 25 and 26 are designed to connect
the unit to electrical power supply devices and fluid supply devices,
such as lubricants or coolants, respectively (FIG. 2).
A motor 18 schematically illustrated in FIG. 2 causes corresponding
toothing 20 on support 16 to rotate via a cogwheel drive 19 with
take-up system of known type.
Motor 18 controlled by a transducer, controls the angular positioning
of the chuck unit around an axis identified as "A".
As will clearly appear from the description and the annexed drawings,
chuck unit 5 can easily be removed, as it is only connected to the
transmission devices via a coupling which requires the two parts
to be brought into contact with one another and clamped with a simple,
straight approach movement; it can therefore be detached with no
need to remove any part of the head, merely by activating grippers
15 to release shanks or pins 14 and disconnect the electric and
Chuck 5 can therefore be quickly and easily replaced with a different
chuck unit which has the same coupling, such as a motorised chuck
designed to perform high-speed finishing or milling tasks.
Subsequently, during operation, motor 18 will cause support 16
to rotate in order to position the chuck around axis "A",
whereupon, in the case of machining performed with three machine
axes (3+2 mode), support 16 will lock in the position reached.
For this purpose, a ring-shaped chamber shown as no. 30 in FIG.
1 with walls made of a deformable material, is fitted around support
Chamber 30 is connected to means designed to convey pressurised
fluid into the chamber so as to deform the walls, dilating them
outwards in order to lock support 16 by friction.
Machining can be commenced by rotating the chuck tool via the transmission
system constituted by shafts 6 8 10 and 11.
In the case of machining with 5 simultaneous axes, motor 18 will
continuously vary the angle of the chuck unit under numerical control.
Chip-exhausting devices are also fitted, comprising a ring-shaped
chamber 21 which surrounds the base of the head and contains one
or more slits fitted with a rapid coupling 22 of known type for
connection of an arm 23; another arm 24 which terminates close
to the tool, is connected to the end of the said arm 23.
During machining, chips and/or dust are exhausted through ducts
24 23 and 21 by devices of known type; if the chuck needs to be
replaced, it is sufficient to disconnect ducts 23 and 24 which
are removed together with the chuck and replaced by new ducts associated
with the chuck to be fitted to the head, the said new ducts being
connected via rapid coupling 22.