Machine tools abstract
A workpiece holding means for machine tools and more particularly
for milling and/or drilling machines, comprising a pivoting bridge
supported between two bearing walls. The bearing walls respectively
laterally delimit a working area. At least one drive motor serves
for pivoting the pivoting bridge, such motor being arranged outside
the working area on at least one outer side of the bearing walls.
The pivoting bridge is provided with a gear ring adjacent to one
or both of the inner sides of the bearing walls, such gear ring
being drivingly connected with the drive gear wheel driven by at
least one drive motor. The bearing points or bearing pins of the
pivoting bridge accordingly do not have to transmit any drive torque
and are not subjected to any torque load so that more precise running
and more precise positioning is possible.
Machine tools claims
What is claimed is:
1. A workpiece holding means for machine tools, comprising a pivoting
bridge supported between two bearing walls delimiting between them
an inner working area and at least one first drive motor for pivoting
the pivoting bridge, the at least one first drive motor being arranged
clear of the working area on an outer side of one of the bearing
walls, wherein the pivoting bridge is provided with a drive gear
ring on the one of the bearing walls, the drive gear ring being
drivingly connected with a drive gear wheel which is driven by the
at least one first drive motor, wherein the at least one first drive
motor and/or a drive shaft driven by the first drive motor and provided
with the drive gear wheel extends from the outer side of the one
of the bearing walls into the one of the bearing walls, wherein
the drive gear ring is attached to or formed on a region of the
pivoting bridge, and, a sealing ring for sealing the drive gear
ring and/or the drive gear wheel between the region of the pivoting
bridge and an inner side of the one of the bearing walls, an engagement
face between the sealing ring and the region of the pivoting bridge
or the inner side of the one of the bearing walls being in the form
of a plain seal face.
2. The workpiece holding means as set forth in claim 1 wherein
the gear ring and the drive gear wheel are connected together.
3. The workpiece holding means as set forth in claim 1 wherein
the drive gear ring fits at least partly into a recess in one of
the inner sides of the bearing walls.
4. The workpiece holding means as set forth in claim 1 wherein
the pivoting bridge possesses two bearing pins, which are respectively
mounted in bearing sleeves for respectively pivotally supporting
the bearing pins in the two bearing walls.
5. The workpiece holding means as set forth in claim 4 wherein
at least one of the bearing pins possesses a concentric motor-driven
drive shaft therein, which drives at least one workpiece table,
which at least one workpiece table is rotatably supported on the
pivoting bridge by a power transmission train.
6. The workpiece holding means as set forth in claim 5 wherein
a second drive motor for the concentric drive shaft is fixed on
the at least one of the bearing pins.
7. The workpiece holding means as set forth in claim 1 wherein
a diameter of the gear ring is larger than a diameter of the drive
gear wheel.
8. A workpiece holding means for machine tools, comprising a pivoting
bridge pivotally supported via two bearing pins between two bearing
walls delimiting between them an inner working area and at least
one first drive motor driving a first drive shaft for pivoting the
pivoting bridge, the at least one first drive motor being arranged
clear of the working area on an outer side of one of the bearing
walls, wherein the pivoting bridge is provided with a drive gear
ring on the one of the bearing walls, the drive gear ring being
drivingly connected with a drive gear wheel which is driven by the
at least one first drive motor, wherein a second drive motor for
driving a second drive shaft is fixed on one of the bearing pins,
wherein the at least one first drive motor and/or the first drive
shaft driven by the at least one first drive motor, which is provided
with the drive gear wheel, extends from the outer side of the one
of the bearing walls into the one of the bearing walls, wherein
the drive gear ring is attached to or formed on a region of the
pivoting bridge, and a sealing ring for sealing the drive gear ring
and/or the drive gear wheel between the region of the pivoting bridge
and an inner side of the one of the bearing walls, an engagement
face between the sealing ring and the region of the pivoting bridge
or the inner side of the one bearing wall being in the form of a
plain seal face.
9. The workpiece holding means as set forth in claim 8 wherein
the gear ring and the drive gear wheel are connected together.
10. The workpiece holding means as set forth in claim 8 wherein
the gear ring fits at least partly into an annular groove in the
inner side of the one bearing wall.
11. The workpiece holding means as set forth in claim 8 wherein
the two bearing pins are respectively mounted in bearing sleeves
for respectively pivotally supporting the bearing pins in the two
bearing walls.
12. The workpiece holding means as set forth in claim 11 wherein
at least one of the bearing pins possesses a the second drive shaft,
which is a concentric motor-driven drive shaft, which drives at
least one workpiece table, which at least one workpiece table is
rotatably supported on the pivoting bridge by a power transmission
train.
13. The workpiece holding means as set forth in claim 8 wherein
a diameter of the gear ring is larger than a diameter of the drive
gear wheel.
14. A workpiece holding means for machine tools, comprising a pivoting
bridge supported between two bearing walls delimiting between them
an inner working area and furthermore at least one first drive motor
for pivoting the pivoting bridge, the at least one first drive motor
being arranged clear of the working area on at least one outer side
of the bearing walls, wherein the pivoting bridge is provided with
a drive gear ring on the at least one of the bearing walls, the
drive gear ring being drivingly connected with a drive gear wheel
which is driven by the at least one first drive motor, wherein at
least a portion of the at least one first drive motor and a drive
shaft driven by the at least one first drive motor and provided
with the drive gear wheel extend from an outer side of a corresponding
bearing wall into a holding recess in the corresponding bearing
wall, the holding recess also containing the drive gear wheel, said
at least one first drive motor, the drive shaft, and the drive gear
wheel being locked in place by a holding flange.
15. The workpiece holding means as set forth in claim 14 wherein
the gear ring and the drive gear wheel are connected together.
16. The workpiece holding means as set forth in claim 15 wherein
the drive gear ring fits at least partly into a recess in one of
the inner sides of the bearing walls.
17. The workpiece holding means as set forth in claim 15 wherein
the pivoting bridge possesses two bearing pins, which are respectively
mounted in bearing sleeves, for respectively pivotally supporting
the bearing pins in the two bearing walls.
18. The workpiece holding means as set forth in claim 17 wherein
at least one of the bearing pins possesses a concentric motor-driven
drive shaft therein, which drives at least one workpiece table,
which at least one workpiece table is rotatably supported on the
pivoting bridge by a power transmission train.
19. The workpiece holding means as set forth in claim 18 wherein
a second drive motor for the concentric drive shaft is fixed on
the at least one of the bearing pins.
20. The workpiece holding means as set forth in claim 15 wherein
a diameter of the gear ring is larger than a diameter of the drive
gear wheel.
Machine tools description
BACKGROUND OF THE INVENTION
The invention relates to a workpiece holding means for machine
tools and more particularly for milling and/or drilling machines,
comprising a pivoting bridge more particularly possessing two bearing
pins for the pivotal support between two bearing walls respectively
laterally delimiting a working area, and furthermore at least one
drive motor for pivoting the pivoting bridge, such motor being arranged
outside the said working area on at least one outer side of the
bearing walls.
THE PRIOR ART
The use of such pivoting bridges as workpiece holding means for
machine tools is for example disclosed in the European patent publication
0712682 or in the German patent publication 3624284 C2. The drive
motor is in each case arranged externally on one of the two bearing
walls, i.e. clear of the working area in order to protect same from
shavings produced in the course of machining and from lubricating
substances and coolants. This externally mounted drive motor drive
drives, at this position, one of the bearing pins so that same must
transmit the entire driving torque from the bearing pin to the pivoting
bridge. More particularly in the case of high precision machining
the torque on the bearing pin has turned out to be disadvantageous,
since effects are produced on the accuracy of positioning and the
running behavior.
SHORT SUMMARY OF THE INVENTION
One object of the invention is to so improve a workpiece holding
means of the type initially mentioned that if the drive motor is
externally mounted torque forces on the bearing pins may be prevented.
In order to achieve these and/or other objects appearing from the
present specification, claims and drawings, in the present invention
the pivoting bridge is provided with a gear ring at one or both
of the two inner sides of the bearing walls, such gear ring being
drivingly connected with a drive gear wheel itself driven by the
at least one drive motor.
There is the advantage that not only a bearing pin but also the
pivoting bridge is driven directly by way of its gear ring so that
there is a short power transmission path and no torque load on the
bearing pins. This leads to improved running properties and to a
greater accuracy of positioning. As regards precise bearing means
the bearing pins may be optimized without paying heed to the drive
means.
The measures recited in the claims represent advantageous further
developments and improvements of the invention.
The drive motor and/or a drive shaft driven by it and provided
with a drive gear wheel extend at least partially from the outside
through the bearing wall. This means that simple dismounting of
the drive for the pivoting bridge is possible, for example by detaching
the drive motor from the bearing wall and drawing it outward together
with the drive gear wheel.
The gear ring and the drive gear wheel are preferably in mesh with
each other or connected together by way of a drive train such as
a sprocket chain or a toothed belt.
In an advantageous form of the invention the drive gear ring extends
into an annular or disk-like recess in the inner side of the bearing
wall at least partially so that it is substantially protected against
matter produced in the course of machining such as shavings or the
like.
In accordance with an advantageous design of the invention the
drive gear ring is attached to of formed on a disk-like area of
the pivoting bridge and more particularly on a flat side thereof
facing the bearing wall. The disk-like area accordingly serves not
only as a holding socket for the gear ring but also additionally
for screening off from the working area, more especially in the
case of an arrangement of the gear ring let into the bearing wall.
In order to achieve an even better sealing effect for the gear
wheel drive to shut it off from the working area it is an advantage
to arrange a seal ring for sealing the drive gear ring and/or the
drive gear wheel between the disk-like area of the pivoting bridge
and the inner side of the corresponding bearing wall, the face of
engagement between the sealing ring and the disk-like area or the
inner side of the bearing wall preferably being in the form of a
plain bearing means and/or a labyrinth seal face. Accordingly it
is possible for the gear ring or, respectively, the drive gear wheel
to be reliably protected or sealed from liquids and lubricants required
for machining.
In accordance with an advantageous development of the invention
at least one of the bearing pins, which are more especially supported
in bearing sleeves, contains a concentric, motor-driven drive shaft,
which drives, by way of an power transmission train, running in
or on the pivoting bridge, at least one workpiece table supported
in a rotatable manner on the pivoting bridge. Such a drive, which
in principle is disclosed in the initially mentioned prior art,
for a workpiece table through the bearing pin can be designed for
substantially more simply, if in accordance with the invention the
bearing pin is not required from the pivotal drive of the pivoting
bridge.
The drive motor for the drive shaft in the bearing pin is secured
to the latter in a manner preventing relative rotation so that the
pivotal motion of the pivoting bridge is decoupled for the rotary
movement of the workpiece table.
The torsion force acting on the pivoting bridge may be further
reduced if the pivoting bridge has two gear rings at the inner sides
of the two bearing walls and if two drive motors are provided for
a synchronous drive of such two gear rings.
The diameter of the gear ring is preferably substantially larger
than the diameter of the drive gear wheel, something which contributes
to increasing precision of positioning of the pivoting bridge. Furthermore,
for the drive motor a transmission with an extremely low step-down
transmission ratio may be selected, or it is even possible to completely
do without such a step-down transmission.
Further advantageous developments and convenient forms of the invention
will be understood from the following detailed descriptive disclosure
of one embodiment thereof in conjunction with the accompanying drawings.
LIST OF THE SEVERAL VIEWS OF THE FIGURES
FIG. 1 shows a diagrammatic overall elevation of a pivoting bridge
pivotally supported between two bearing walls as an embodiment of
the invention.
FIG. 2 shows a more detailed representation of the drive placed
on the left hand bearing wall.
DETAILED ACCOUNT OF WORKING EMBODIMENT OF THE INVENTION
The workpiece holding means illustrated in FIGS. 1 and 2 for machine
tools such as milling machines, or drilling machines, essentially
comprises a pivoting bridge 10 which at its two opposite terminal
regions possesses two bearing pins 11 and 12 turned in opposite
directions. The pivoting bridge 10 is supported in a pivotal manner
by means of such bearing pins 11 and 12 on two spaced apart bearing
walls 13 and 14. In the case of such bearing walls 13 and 14 it
may be a question of side walls of the machine tool or of side walls
of a customized holding means for the pivoting bridge 10.
The two bearing pins 10 and 11 are arranged at two disk-like terminal
regions 15 and 16 of the pivoting bridge 10 which are respectively
positioned directly adjacent to and parallel to the bearing walls
13 and 14. As shown in the more detailed representation of FIG.
2 the bearing pins 11 and 12 are supported in anti-friction bearings
17 in bearing sleeves 18 and 19 which are respectively inserted
in corresponding recesses in the bearing walls 13 and 14. The bearing
pins 11 and 12 respectively fit into the disk-like terminal regions
15 and 16 and are held in same by means of flanges 20.
A gear ring 21 is mounted on the outer side, facing the bearing
wall 13 of the left hand disk-like terminal region 15 the ring
being screwed or pinned in place in some manner not illustrated
in detail. These gear ring 21 fits in a corresponding annular recess
22 in the left hand bearing wall 13. A first drive motor 23 for
pivoting the pivoting bridge 10 is inserted from the outside in
a corresponding holding recess 24 in the left hand bearing wall
13 and locked in place by means of a holding flange 25. A drive
gear wheel 27 driven by a drive shaft 26 of the drive motor 23 is
in mesh with the radially outwardly directed teeth 28 of the gear
ring 21. The drive gear wheel 27 is located in the extension of
the holding recess 24 into which the first drive motor 23 is partly
fitted. After detachment of the holding flange 25 the first drive
motor 23 may be drawn out together with the drive gear wheel 27
outward from the left bearing wall 13.
Instead of toothed engagement between the drive gear wheel 27 and
the gear ring 21 it is possible for the transmission of power to
be by way of a drive chain, a toothed belt or the like.
For the protection of the drive device essentially comprising the
gear ring 21 and the drive gear wheel 27 against shavings and against
lubricants and coolants and the like during machining, which are
present in the working area 29 between the two bearing walls 13
and 14 a sealing ring 30 is provided, which is fixed on the left
hand bearing wall 13 and is so fitted about the disk-like terminal
region 15 of the pivoting bridge 10 that the drive gear wheel 27
is enclosed. This sealing ring 30 is in contact by way of plain
sealing face 31 or, respectively, a labyrinth seal face with the
radially outwardly turned peripheral face of the terminal region
15. As an alternative to this the sealing ring 30 could also be
fixed on the terminal region 15 the plain sealing face 31 being
formed between the sealing ring 30 and the inner face, facing the
working area 29 of the left hand bearing wall 13.
A workpiece table 32 is rotatably mounted on the pivoting bridge
10 and onto it workpieces may be clamped, the axis of rotation extending
perpendicularly to the pivot axis of the pivoting bridge 10. The
drive of such workpiece table 32 is in a known manner by way of
a second drive motor 33 which is flange-mounted by means of a flanged
cup 34 on the free terminal side of the bearing pin 11. In the interior
of such bearing pin 11 a drive shaft 35 is rotatably mounted by
means of anti-friction bearings 36 and at one end is connected by
way of a connection member 37 with the drive shaft 38 of the second
drive motor 33. The other end of the direction shaft 35 bears a
gear wheel 39 driving the workpiece table 32 by way of a power transmission
train 40 not illustrated in detail. Such transmission train can
include drive sprocket chains, toothed belts, drive shafts or the
like in a known manner.
Instead of a workpiece table 32 the pivoting bridge 10 may also
possess several such workpiece tables, which are either driven by
way of the same drive or by way of separate drives. For instance,
for this purpose the second bearing pin 12 may be provided with
a further corresponding drive device. The simplest possible design
would have one pivoting bridge 10 without rotary workpiece tables
32.
The diameter of the gear ring 21 is substantially larger than that
of the drive gear wheel 27 so that for this reason the speed of
rotation of the first drive motor 23 would be stepped down. In case
of need the first drive motor 23 may further possess a step-down
transmission. This also applies from the second drive motor 33.
As a modification of the illustrated working example the drive
of the pivoting bridge 10 may also be from both sides in order to
reduce the torque acting of the pivoting bridge owing to the drive
forces as far as possible. For this purpose the right disk-like
terminal region 16 is provided with a gear ring corresponding to
the gear ring 21 and in the right hand bearing wall 14 a drive motor
corresponding to the first drive motor 23 is provided. The two drive
motors are operated synchronously. |