TETE DE COUPE DE FRAISEUSE A DEUX ELEMENTS DE ROTATION CONTINUE ET A ENTRAINEMENT DIRECT

MILLER CUTTERHEAD WITH TWO CONTINUOUS ROTATIONS AND DIRECT DRIVE

Abrégé anglais

Miller cutterhead with two continuous rotations and direct drive, of the kind
that is comprised of slide, cutterhead and main spindle, where: a)-. the
cutterhead is a modular element and has a first and second supplementary
rotation spindle, to convert a three-spindle grinding centre or milling
machine into a five spindle one; b)-. it has a first motor coupled directly
onto the first supplementary rotation spindle with the stator fixed on the
slide and with its motor fixed on the cutterhead; and c)-. it has a second
motor coupled directly onto the second rotation spindle. The first and second
motors are high torque flat motors with a low speed range; in particular
direct servomotors, without any intermediate transmission or reduction.
Application in machine-tool.

Revendications

5
CLAIMS
1.- Miller cutterhead with two continuous rotations and direct
drive, comprised of a slide, cutterhead and main spindle, characterised
because
the cutterhead is a modular element and has a first and second supplementary
rotation spindle, to convert a three-spindle grinding centre or milling
machine
into a five-spindle one; because it has a first motor coupled directly onto
the
first supplementary rotation spindle with its stator fixed on the slide and
with
its rotor fixed on the cutterhead; and because it has a second motor coupled
directly onto the second rotation spindle.
2.- Miller cutterhead with two continuous rotations and direct
drive, according to above claim, characterised because the first and second
motors are high torque flat motors with a low speed range; in particular
direct
servomotors, without any intermediate transmission or reduction.

Description

CA 02268202 1999-04-07
"MILLER CUTTERHEAD WITH TWO CONTINUOUS
ROTATIONS AND DIRECT DRIVE".
The object of this invention is a cutterhead that provides the
tool with two continuous additional rotations in order to convert a three-
spindle grinding centre or milling machine into a five-spindle one. With this
solution a traditional vertical milling machine can be transformed into a five-
spindle one, all of them in the tool.
Of the two additional rotations that the cutterhead of the
invention provides, one of them is parallel to the table and the other
perpendicular to the table.
Traditionally, these rotations of the tool have been generated
by motors, located on the upper part of the ram, accompanied by some
transmissions that provide the rotation at the tip of the tool.
The solution adopted by this cutterhead is to use high torque
direct motors with relatively low speed ranges, which permits the location or
coupling of the motors directly on the rotation spindle, providing a more
compact solution.
This cutterhead is a modular element that can be considered as
an accessory for the machine.
In this invention high torque flat motors have been used with
low speed ranges; in particular direct servomotors, without any intermediate
transmission or reduction, which produce rotary movements, providing the
assembly with a good control and high dynamics.
The advantages or dynamic features achieved with the
invention both in accelerations and limit speeds represent an increase of up
to
100% respect to the currently known cutterheads.
This invention advocates a miller cutterhead with two
rotations and direct drive, comprised of a slide, cutterhead and main spindle,
and it is characterised because the cutterhead is a modular element and has a

CA 02268202 1999-04-07
2
first and second supplementary rotation spindle, to make a three-spindle
grinding centre or milling machine into a five-spindle one; because it has a
first motor coupled directly on the first supplementary rotation spindle with
its
stator fixed in the slide and with its rotor fixed in the cutterhead; and
because
it has a second motor coupled directly in the second rotation spindle.
It is also characterised because the first and second motors are
high torque flat motors with a low speed range; in particular direct
servomotors, without any intermediate transmission or reduction.
This cutterhead is designed to be applied in medium-sized or
large grinding centres and milling machines, where it is necessary to work
with five spindles. These machines must include numerical controls with high
features and with capacity to interpolate five spindles at the same time.
It will preferably be applied on vertical grinding centres, but it
can be implanted additionally on horizontal centres.
The advantages provided by the proposed solution of the
miller cutterhead with two continuous rotations and direct drive, targeted by
this invention are:
. Simplification of the design on eliminating mechanical
transmissions.
. More compact solution, minimising volume and weight.
. Great rigidity of the cutterhead opposed to traditional
solution.
. Greater reliability inherent to the reduction of the number of
components.
. Elimination of the transmission chains
. Elimination of the mechanical hysteresis.
. High angular acceleration because this corresponds directly
with that of the motor.
. Reduction of the inertia.

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3
To reach a better understanding of the object of this invention,
a preferential form of practical execution is represented on the drawings,
susceptible to accessory changes that will not change the basic design.
Figure 1 is a schematic representation of a practical execution
of the cutterhead targeted by this invention.
Below an example of a practical execution of this invention is
described, but it is not limiting.
In figure 1 the slide (1), cutterhead (2) and main spindle (3)
have been represented in a coaxial mode.
Milling machines with a slide ( 1 ) equipped with movement on
three spindles and a cutterhead (2) with movement on another two
supplementary spindles (B) (C) are already known.
For the movement of the supplementary spindle (B)
traditionally there is a first motor (M'2) (not represented) placed on the
slide
( 1 ) and a second motor (M'2) (not represented) placed on the cutterhead (2),
requiring a transmission complex between them both and the relative rotation
spindles for the tool (4) to achieve the desired movements.
Figure 1 shows that, in accordance with the invention, the first
motor (Ml) to achieve the supplementary rotation (B) has its stator (5) fixed
to
the slide (1) and the rotor (6) fixed to the cutterhead (2) and on the spindle
(B)
of the supplementary rotation.
The second motor (M2) is placed on the cutterhead (2) in a
coaxial fashion and on the spindle itself ( C) of the supplementary rotation
to
be achieved.
It can be seen that with this arrangement the transmissions
disappear so the dynamic features of the machine are substantially improved.
The first and second motors (M 1 ), (M2) are high torque flat
motors with a low speed range which, as already mentioned, are coupled

CA 02268202 1999-04-07
4
directly onto the relative rotation spindle (B), (C) providing a more compact
solution.
In particular, the first and second motors (M1), (M2) are
direct servomotors and the speed ranges used are relatively low, up to 120
r.p.m.
Of the two supplementary rotations or spindles (B) ( C), one
of them is parallel to the work table (not represented) and the other is
perpendicular to it. As a result, the servomotors (M 1 ), (M2) are located
coaxially and radially with the electric boring bar.
It has also been arranged for the main motor (M3) or electric
boring bar to be placed coaxially to the main spindle (3).

Dessin représentatif