Machine tools abstract
A tool-driving device (1), which is particularly provided for machine
tools, has an internal drive (9), which serves to drive a tool.
Also provided is a control device (36), which detects the movement
of the tool-driving device (1) and correspondingly controls its
drive (9). The tool-driving device (1) can thus be controlled independently
of the other tool-machine controls.
Machine tools claims
What is claimed is:
1. A tool-driving device (1) for a machine having at least one
movably-seated machine spindle, having a spindle insert (2), which
includes a coupling device (3) that can be connected to the machine
spindle, a controllable drive (9) for driving a tool that is designed
to convert its drive energy into mechanical energy, and at least
one supply line (8), which serves to transmit the drive energy to
the drive (9), having a coupling element (11), with which an energy-transmitting
connection can be produced and broken between a drive source and
the drive (9), having a detection device (14), which serves to detect
the movement of the machine spindle, and having a control device
(36), which is designed to control the drive (9) as a function of
the movement of the machine spindle.
2. The tool-driving device according to claim 1 characterized
in that the movement of the machine spindle is a rotational movement.
3. The tool-driving device according to claim 1 characterized
in that the control device (36) is controlled exclusively by the
movement of the machine spindle.
4. The tool-driving device according to claim 1 characterized
in that the coupling device (3) is a taper shank that can be clamped
into a machine spindle, and a cylinder segment (5) provided as a
carrier for a marking (6) is connected to an adjoining clip disk
(4) that has a gripping groove for an automatic tool exchange.
5. The tool-driving device according to claim 1 characterized
in that the drive (9) is an electric motor (22) that serves as a
rotational drive.
6. The tool-driving device according to claim 1 characterized
in that the drive (9) is in a driving connection with a receiving
apparatus (18) for a tool.
7. The tool-driving device according to claim 6 characterized
in that the receiving apparatus (18) for the tool projects out of
the housing (2) on a spindle (17) on the side opposite the coupling
device (3).
8. The tool-driving device according to claim 7 characterized
in that the spindle (17) is embodied to rotate symmetrically relative
to an axis of rotation (27) established by the machine spindle.
9. The tool-driving device according to claim 1 characterized
in that the supply line (8) includes one or more slip rings (8),
the ring(s) being mounted to the outside of the housing (2) and
electrically insulated from it.
10. The tool-driving device according to claim 9 characterized
in that the slip ring or rings (8) is or are disposed on a conical
part (7) of the housing (2), with the diameter of the smallest slip
ring (8) being at least as large as the largest diameter of the
tool coupling (3) or an adjoining clip disk (4).
11. The tool-driving device according to claim 1 characterized
in that the coupling element (11) essentially has a contact set
(32), which includes one or more sliding contacts (32a, 32b, 32c).
12. The tool-driving device according to claim 11 characterized
in that the contact set (32) is mounted to move.
13. The tool-driving device according to claim 11 characterized
in that voltage is not applied to the sliding contacts (32a, 32b,
32c) until the detection device (12) detects a rotational movement
of the machine spindle at a minimum rpm.
14. The tool-driving device according to claim 1 further comprising
means for contactless detection of the rotational movement.
15. The tool-driving device according to claim 14 characterized
in that the detection device (12) includes a signal generator (37)
for emitting a signal, and-a signal receiver (38) for detecting
the signal.
16. The tool-driving device according to claim 15 characterized
in that the signal generator (37) is a light source, and the signal
receiver (38) is a light sensor.
17. The tool-driving device according to claim 16 characterized
in that the detection device (12) formed by the signal generator
(37) and the signal receiver (38) and is adjustable in height and
position.
18. The tool-driving device according to claim 17 characterized
in that a reflecting element (6) is mounted to the tool-driving
device (1), and is oriented to reflect the light emitted by the
light source to the sensor.
19. The tool-driving device according to claim 17 characterized
in that an essentially circular clamping body can be mounted to
the tool-driving device (1) with the surface of the clamping body
possessing different reflective properties from the surface on which
it is seated and held.
20. The tool-driving device according to claim 1 characterized
in that it has at least one supply line (21) and an outward-oriented,
nozzle (19), the line and nozzle serving to supply a cooling medium
to the tool.
21. The tool-driving device according to claim 5 characterized
in that the electric motor (22) is one of a DC motor, a single-
or polyphase synchronous motor, and an asynchronous motor.
22. The tool-driving device according to claim 7 characterized
in that the receiving apparatus is an inside cone.
23. The tool-driving device according to claim 11 characterized
in that the one or more sliding contacts correspond to the number
of slip rings.
24. The tool-driving device according to claim 11 characterized
in that the one or more contacts are carbon brushes or rollers and
are connected to at least one of a power source and a control device
by way of a supply line.
25. The tool-driving device according to claim 12 characterized
in that the contact set is mounted to the machine tool.
26. The tool-driving device according to claim 12 characterized
in that the contact set is mounted on a spindle head that supports
the machine spindle.
27. The tool-driving device according to claim 13 characterized
in that the minimum rpm is 30 rpm.
28. The tool-driving device according to claim 14 wherein the
means for contactless detection detects the rotational movement
at least one of optically and magnetically.
29. The tool-driving device according to claim 17 characterized
in that the detection device is mounted to the machine tool.
30. The tool-driving device according to claim 17 characterized
in that the detection device is mounted to the spindle head that
guides the machine spindle.
31. The tool-driving device according to claim 18 characterized
in that the reflecting element is one of a wafer and a film.
32. The tool-driving device according to claim 19 characterized
in that the clamping body is provided with at least one of a gap
and a recess.
33. The tool-driving device according to claim 19 characterized
in that the clamping body is mounted to a cylindrical segment of
the tool-driving device.
34. The tool-driving device according to claim 20 characterized
in that the least one supply line is disposed inside the housing
and extends essentially parallel to its axis of rotation.
35. The tool-driving device according to claim 20 characterized
in that the nozzle is pivotable.
36. The tool-driving device according to claim 20 characterized
in that the nozzle includes plastic.
37. The tool-driving device according to claim 20 characterized
in that the cooling medium is at least one of a cooling fluid and
a compressed air.
Machine tools description
The invention relates to a tool-driving device that is particularly
designed for use in machine tools or in machining units of machining
centers, and has at least one machine spindle that is seated to
move.
Machine tools are used especially for material-removal processes,
such as boring, milling, turning on a lathe, etc.
The tool is inserted into a corresponding tool receptacle that
is secured in the work spindle of the relevant machine tool. Various
tool receptacles are available.
During the machining process, the work spindles are driven by associated
drive apparatuses. Control devices, which can include expanded electronic
circuits or execution programs, are provided for controlling the
spindle movement, notably its rotation and/or adjustment.
The control device establishes the rpm of the spindle within an
rpm range. This range is inherently limited. It may be that, particularly
for very small tool diameters or for other reasons, rpms outside
of the rpm range of the spindle are required.
It is the object of the invention to provide a tool-driving device
that expands the application range of a machine tool or machining
unit, preferably with as little intrusion as possible into the existing
machine control.
This object is accomplished with a tool-driving device having the
features of claim 1.
The tool-driving device of the invention has a spindle insert,
which can preferably be clamped, fixed against relative rotation,
in a machine spindle and can support a tool for machining workpieces.
A coupling device serves to secure the spindle insert in the machine
spindle. A drive that is supplied by a drive source located outside
of the spindle insert, and can be controlled by a control device,
is provided for driving the tool. The drive is effected by way of
a coupling element that can be connected to the supply lines of
the drive. The drive is controlled as a function of the movement
of the machine spindle; the tool-driving device is provided with
a detection device for detecting this movement.
From the spindle movement, the detection device obtains a signal
that characterizes, for example, the rpm, and is used as an input
signal for the control device for controlling the drive, and therefore
the movement, of the tool. The detection of the rpm requires no
access to the machine control, especially if no control signals
originating from the machine control are necessary. The control
device is separate from the other machine control, and is therefore
independent and self-sufficient.
If desired, the power supply can be effected by the tapping of
the machine control or the drive source of the machine tool. A dedicated
drive source can, however, also be provided for the power supply.
The tool-driving device permits the increase of the rpm of the
machine spindles above and beyond the capabilities of the machine
spindle. Unlike in a passive accessory gear, in this instance the
additional supply of power in the drive of the tool permits the
conversion of an output that exceeds the output of the machine spindle.
The maximum torque can be completely retained while the rpm is increased.
The spindle insert has a coupling device, e.g., a 7/24 taper shank,
which permits a secure, detachable connection--fixed against relative
rotation--with the machine spindle. It also has an essentially cylindrical,
one- or multiple-part housing, inside which the drive is disposed.
If material-removal operations are to be executed with a rotating
tool, the drive is embodied as a rotary drive. A motor, e.g., an
electric motor, serves to drive the tool. DC motors, synchronous
motors or asynchronous motors can be used for a single- or polyphase
alternating current. Hydraulic or pneumatic drives, with which rotational
or axial movements of the tool can be attained, can also be used.
The motors can be connected to the tool directly, or via a gear
in a driving arrangement.
In a preferred embodiment of the invention, a receiving apparatus
is provided for receiving the tool; the apparatus has a tool spindle,
into which the tool is clamped, fixed against relative rotation.
The tool spindle preferably has a conical inside shape. The tool
spindle is then formed by a rotatably-seated shaft, and projects
out of the housing. The shaft is connected to a rotating part of
the motor (internal or external rotor) so as to be fixed against
relative rotation. The shaft and the tool spindle are preferably
embodied to rotate symmetrically relative to an axis of rotation
established by the machine spindle. The tool spindle can, however,
also support a quick-clamping element, a jaw chuck or the like.
At least one slip ring, which is mounted to the outside of the
housing and is electrically insulated from it, and can be brought
into engagement with an associated sliding contact of the coupling
element, is provided for supplying power to the electric motor.
When the machine spindle rotates, the sliding contacts slide along
the slip rings, thereby assuring the power supply to the drive.
Rollers can also be used instead of sliding contacts. The supply
can also be effected contactless, e.g., with transformers.
The slip rings are preferably disposed on a conical part of the
housing whose diameter increases starting from the machine spindle.
The slip rings therefore have different diameters. The smallest
diameter is larger than that of an arbitrary part of the coupling
device. Thus, the spindle insert can be inserted into the machine
spindle without altering the position of the contact set. The contact
set can then be rigidly secured to the machine tool, in which case
it is disposed at a slight incline, corresponding to the incline
of the conical housing part. The insertion of the spindle insert
produces the contact between the slip rings and the sliding contacts.
The contact set can also be seated to be adjusted, and/or can be
separate.
The safety of the tool-driving device is increased when voltage
is only applied to the sliding contacts during the machining process.
If the detection device detects rpms that are at least as high as
a defined threshold value, preferably 30 rpm, the current supply
to the sliding contacts is enabled, for example, by the automatic
closure of a switch. The circuit is opened at rpms below the threshold
value.
Contactless, magnetic or optical methods are preferred for rpm
detection. For example, a metal part connected to rotate with the
spindle insert or the machine spindle can serve to induce a short
voltage pulse in a stationary coil with each rotation.
In an advantageous embodiment, the detection device has a signal
generator, particularly a light source, and a signal receiver, particularly
a light sensor. The detection device is preferably adjustably mounted
to the machine tool, for example to the spindle head that guides
the machine spindle. A marking, such as a narrow metal plate, that
reflects the light emitted by the light source is secured to the
tool coupling or the machine spindle. A signal that is thereby generated,
and characterizes the rpm of the machine spindle, e.g., a pulse
signal that is proportional thereto, is then transmitted to the
control device.
A circular clamping body having different visual properties from
the location where it is to be secured can serve as a marking. The
clamping body can have a gap or a recess.
The passage of the gap or recess in front of the sensor generates
the signal.
Markings that effect the generation of a plurality of signals with
each rotation can also be provided. In the simplest case, the markings
can be equidistantly spaced and provided on, for example, an adhesive
strip.
The control device utilizes the signals arriving from the detection
device to generate a corresponding drive signal for the drive. Hence,
the rpm range of the tool can be expanded with the device of the
invention. Existing machine tools can therefore be rendered more
versatile without its mechanical or electronic components being
disturbed.
The control device can be integrated into the spindle insert, or
accommodated separately. It can also be controlled by programs running
on a computer. A console can be provided for the user.
At least one supply line for a cooling fluid or compressed air
is preferably provided in the tool-driving device for cooling the
tool, as is an outward-oriented nozzle, which is preferably pivotable
and comprises plastic, for example. At the same time, the nozzle
can conduct heat out of the tool-driving device.
Further advantageous details about embodiments of the invention
ensue from the dependent claims, the drawing and/or the associated
description.
The drawing illustrates an embodiment of the subject of the invention.
Shown are in:
FIG. 1 a tool-driving device according to the invention, in a partly
schematic front view;
FIG. 2 a front view of the tool-driving device from FIG. 1 in
a partly cutaway and partly schematic representation;
FIG. 3 a side view of the coupling element used in the device of
the invention according to FIGS. 1 and 2 in a partly schematic
representation;
FIG. 4 a plan view of the coupling element from FIGS. 1 through
3 in a partly schematic representation; and
FIG. 5 a schematic representation of the operating principle of
the device according to the invention.
As shown in a schematic, general view in FIG. 1 a tool-driving
device 1 has a housing 2 which has an essentially cylindrical shape.
At one end of the housing 2 is a 7/24 taper shank 3 which is received
in a corresponding chuck, not shown in detail, of a machine spindle.
A clip disk 4 adjoins the 7/24 taper shank 3. A short, cylindrical
segment 5 which directly adjoins the clip disk 4 but has a smaller
diameter than the disk, serves as a carrier for marks 6 the constitution
and significance of which will be discussed later.
Adjoining the cylindrical segment 5 is a conical connecting segment
7 whose smallest diameter adjoins the cylindrical segment 5. The
diameter here is, however, already larger than that of the clip
disk. The conical connecting segment 7 has one or more--in the present
embodiment, three--slip ring(s) 8 (8a, 8b, 8c) for supplying current
to a drive 9 disposed in the housing 2 as can be seen in FIG. 2.
A connecting head 11 which supports a contact carrier 12 and a
sensor unit 14 is associated with the slip rings 8 and the marking
6. The connecting head 11 is preferably permanently mounted to the
machine tool for which the tool-driving device 1 is to be used.
As an alternative, the connecting head 11 can be mounted to a carrier
that permits a radial movement of the connecting head 11 and only
brings it into the connecting position when the tool-driving unit
1 is to be secured to the machine spindle. If other tools are to
be used, the connecting head 11 can be moved out of the way. This
is not necessary in most cases, however.
Adjoining the conical connecting segment 7 in the tool-driving
unit 1 is a cylindrical housing part 15 whose end remote from the
7/24 taper shaft 3 is closed with a lid 16. The lid has a central
opening, through which a rotatably-seated spindle 17 projects. The
spindle is provided for receiving tools, and, as can be seen from
FIG. 2 has an inside cone 18. Adjacent to the spindle 17 is a nozzle
19 which is preferably seated to move, and is connected to a conduit
21 which can serve in conveying cooling lubricants.
As can be seen from FIG. 2 the drive 9 in the form of an electric
motor 22 is disposed inside the housing 2 preferably essentially
in a space surrounded by the housing part 15. The spindle 17 forms
the motor shaft, and is rotatably seated at both ends of the electric
motor 22 by ball bearings 23 24. The electric motor 22 can be a
servomotor, a stepping motor, a three-phase asynchronous motor,
a synchronous motor or another suitable electric motor. It can be
embodied as a pancake motor or a drag-cup motor if small moments
of inertia are necessary. In addition, a gear, such as a planetary
gear, can be provided between the electric motor 22 and the coupling
formed by the inside cone 18 for coupling a tool, for the purpose
of altering the rpm, particularly increasing it, or for generating
additional movements, for example axial movements. If needed, this
can also be effected with further drives.
Lines 26 lead from the stator 25 of the electric motor 22 to the
slip rings 8 which are disposed in an uninterrupted, concentric
arrangement relative to an axis of rotation 27. The 7/24 taper shank
3 the housing 2 and the spindle 17 are likewise arranged concentrically
with respect to this axis of rotation 27.
The connecting head 11 is shown separately in FIGS. 3 and 4. Disposed
on its side 31 facing the tool-driving device 1 are sliding contacts
32 (32a, 32b, 32c); springs 33 prestress these contacts radially,
with respect to the axis of rotation 27 in the direction of an
arrow 34 indicated in FIG. 4. The sliding contacts 32 are connected
to an actuation unit 36 via lines 35. The actuation unit 36 generates
actuation signals for the drive 9 which is shown as a block in
FIG. 5.
The actuation unit 36 is also connected to the sensor head 14
and receives signals from it that correspond to the rpm of the machine
spindle. For this purpose, the markings 6 that cooperate with the
sensor head 14 (FIGS. 1 and 2) are provided. The markings can be,
for example, recesses or projections on the segment 5 of the tool-driving
unit 1. The sensor head 14 includes a corresponding detection device
for these recesses or projections, such as a magnetic detection
device. In the present case, however, the sensor head 14 is based
on an optical principle. A light source 37 illuminates the segment
5 and a sensor 38 registers the reflected light. The reflective
behavior of the marking 6 differs from that of the remainder of
the segment 5. For example, the marking 6 can be formed by a slotted
plastic ring that partly extends around the segment 5 and leaves
open a smaller segment between its two free, oppositely-located
ends; the sensor head detects the passage of this segment. Thus,
with each rotation of the machine spindle, and therefore each rotation
of the tool-driving device 1 a signal is generated at the sensor
14. Alternatively, a plurality of marks can be provided, which then
generate a plurality of signals. If need be, other devices, such
as a monochromatic or marked adhesive strip, can be used as markings
6 in place of the plastic ring.
At its output 41 the actuation unit 36 generates signals that
correspond to the frequency of the signals received at its input
42. An operator terminal 43 can be used to determine the matchup,
and, for example, which input rpm (input 42) generates which output
rpm (output 41). As an alternative, the matchup can be fixedly set,
or a data interface with a computer can be used to set the matchup.
The described tool-driving device 1 operates as follows:
The tool-driving device 1 can be stored in the magazine of a machine
tool, or in a separate storage device. It can be equipped in advance
with, for example, a tool whose shaft is received in the inside
cone 8 of the spindle 17. To set up the tool-driving device 1 for
operation, the connecting head 11 is mounted to the machine tool,
at a suitable location near the spindle. The connecting head 11
remains in or on the machine tool. The connecting head 11 is disposed
at a large enough distance from the work spindle to permit the free
passage of a clip disk 4 so the connecting head does not impede
the exchange of a conventional tool.
Moreover, the control device of the tool-driving device 1 is mounted
in or on the machine tool. The control device includes the actuation
unit 36 and an optional operator unit 43. When the tool-driving
unit 1 is to be operated, it is inserted into the machine spindle,
i.e., coupled to it, like a conventional tool. This process is effected
essentially by an axial movement in the direction of the axis of
rotation 27. The clip disk 4 passes the contact head 12 without
touching it. While the 7/24 taper shank 3 is located in a corresponding
receptacle, the contacts 32 of the contact head 12 come into contact
with the slip rings 8. The marking 6 also comes into the viewing
field of the sensor head 14.
The operator unit 43 is used now or in advance to determine how
the drive 9 is to be actuated with actuation pulses originating
from the sensor head 14. For example, a fixed rpm can be set. If
the rpm ratio is set at a factor of 5 for example, a rotation of
the machine spindle at 100 rpm causes the control unit 36 to emit
pulses for 500 rpm, correspondingly actuating the drive 9. The rpms
are added, so the spindle 17 rotates at 600 rpm. If the rpm of the
machine spindle is increased to, for example, 5000 the drive 9
is actuated at five times the rpm, i.e., 25000. These rpms are
added to the spindle rpm, so the spindle 17 ultimately rotates at
30000 rpm.
In this way, the machine spindle can attain rpms that it otherwise
could not. In addition, the operator unit 43 can be used, if needed,
to effect a stepless variation in the rpm of the spindle 17.
Unlike in the described embodiment, but within the scope of the
invention, the actuation unit 36 and the operator unit 43 can be
integrated into the tool-driving device 1. The marking 6 is then
permanently applied outside of the tool-driving device 1. Instead
of the marking 6 a corresponding reading head can be provided on
the tool-driving device 1. If the tool-driving device 1 is separate
from the machine tool, the actuation unit 36 is set through, for
example, pre-programming. Operator elements can be provided on the
tool-driving unit, or an interface to a computer or other operator
unit can be provided. In this embodiment, the power supply can be
effected externally, as is apparent in FIGS. 1 and 2.
An advantage of the above-described embodiments is that non-whole-number
rpm ratios can also be set through the corresponding programming
of the actuation unit 36. If needed, however, this programming option
can be omitted. In a simplified embodiment, it is also possible,
for example, to change the rpm merely by changing the number of
marks 6 present on the segment 5. To this end, a suitable adhesive
strip provided with marks can be used. The marks themselves can
also be represented by an adhesive strip. In all cases, the tool-driving
device 1 is controlled without disturbing the machine control of
the machine tool.
A tool-driving device 1 that is particularly provided for machine
tools has an internal drive 9 which serves to drive a tool. Furthermore,
a control device 36 is provided, which detects the movement of the
tool-driving device 1 and correspondingly controls its drive 9.
The tool-driving device 1 can therefore be controlled independently
of the other machine-tool controls. |