Turning – Radially moving rotating tool inside bore – Tool simultaneously moving axially
Patent
1997-08-29
1999-10-19
Pitts, Andrea L.
Turning
Radially moving rotating tool inside bore
Tool simultaneously moving axially
82 12, 82 86, 82158, 82172, B23B 4100
Patent
active
059670070
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a position drive, in particular for use in machine tools, comprising at least one transmission element which is movable with respect to a base body, the transmission element being provided especially for the displacement of a cutting tool or of a cutting tip carrier, an electric motor arrangement which is positioned on the base body and can be coupled to the transmission element, and a power supply device for the motor arrangement.
BACKGROUND OF THE INVENTION
A tool head for use in machine tools is known (U.S. Pat. No. 3,710,659), the position drive of which has a centrally positioned electric drive motor with an axially aligned drive shaft for driving sliders which are movable perpendicular to the axis of rotation of the tool head. A transfer of the drive principle to other applications is not easily possible. Moreover, the efficiency of the known drive principle with its centrally positioned drive motor is not sufficient for many applications.
Based on this, it is the object of the invention, to develop a position drive of the type described above, which has a broad field of applications and which is suited to be used in machine tools for machining centers.
SUMMARY OF THE INVENTION
The solution according to the invention is based on the use of a hollow shaft which is borne rotatably in the base body and drivable by means of the motor arrangement. There is a drive unit available which is compactly built yet efficient, which can be used for different applications with different objects, and which is especially well suited to be used in machine tools for machining centers.
A first variant of the invention provides that the transmission element is formed to be a thrust member which is movable with respect to the base body, while the hollow shaft is borne rotatable about an axis of the base body, which is concentric with respect to a displacement axis of the thrust member, and that the hollow shaft has an internal thread which engages in an external thread of the thrust member.
In an advantageous or alternative embodiment of the invention, the hollow shaft has a toothed ring which is positioned concentric with respect to the external thread, for the engagement of at least one gear which is positioned on a driven shaft of the motor arrangement. In order to increase the efficiency of the motor, the motor arrangement has a plurality of electric motors which are distributed over the circumference of the hollow shaft, and the drive shafts of which each carry a gear which meshes with a toothed ring of the hollow shaft, and which are drivable in unision by the control electronics. The electric motors are positioned at equal circumferential distances in a base-body-fixed motor block with their driven shafts in parallel with respect to the axis of the hollow shaft. They are formed to be e.g. stepper motors or servo motors which are driveable by means of a common NC-control.
Between the hollow shaft and a base-body-fixed part, for instance the motor block, there is advantageously positioned a sensor for monitoring the speed and direction of rotation of the hollow shaft, which is preferably formed to be an incremental transmitter. Instead of the sensor, an encoder which is positioned on one of the electric motors may be provided for monitoring the speed and direction of rotation of the hollow shaft.
In order to ensure an optimal force transfer between the electric motors and the hollow shaft, the toothed ring is formed to be an internal gear ring, the diameter of which is larger than that of the internal thread.
In a preferred application of the position drive according to the invention, an exchangeable cutting head is positioned removably on the base body, which has a central opening and/or a guide bushing at its front side for the insertion of a reaming or drilling tool which is connectable to the thrust member. To this end, the thrust member carries a coupling element, which is positioned at the front side of and within the base body, for the insertion of a reami
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Komet Praezisionswerkzeuge Robert Breuning GmbH
Pitts Andrea L.
Tsai Henry W. H.
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