Direct-Drive Grinding Spindle Layout for Compact Internal Gear Machining
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Solution Overview
Problem
Existing grinding arrangements face challenges in achieving a compact design suitable for gear grinding, particularly for internal gears, while maintaining precise tool movement control and high motor power, and suffer from mechanical transmission distances that complicate load assessment and vibration measurement.
Innovation Solution
A compact grinding arrangement with a direct-drive external rotor design, featuring bearings with inner and outer rings on the stator and rotor, a position encoder on the rotor, and seals to create a stable, sealed unit, allowing direct tool mounting and precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the tool spindle is located in the axial end region of a tubular grinding arm with the drive motor positioned in the other axial end region and torque transmitted via a belt drive, then the design can accommodate the tool spindle in a confined space, but the mechanical transmission distance increases causing static and dynamic compliance
Solution Approach 1:
The invention merges the drive motor and tool spindle into a single integrated unit where the motor rotor directly forms the tool spindle. This eliminates the belt drive and intermediate transmission components, reducing mechanical transmission distance and compliance while maintaining compact installation space suitable for confined grinding arm regions.
2Manufacturing precision
If the tool spindle is directly driven by the motor rotor, then the mechanical transmission distance is minimized improving control precision, but the design requires sufficient space for motor windings and complex bearing arrangements
Solution Approach 1:
The invention transitions from conventional radial bearing arrangements to an axial bearing configuration where bearings are arranged at different axial positions along the motor rotor. This dimensional reorganization allows sufficient winding space in the radial direction while maintaining precise rotational support through axially distributed bearings, resolving the space-complexity contradiction.
3Reliability
If conventional bearing arrangements with counter bearings are used, then machining loads and imbalance forces are supported, but the bearing arrangement becomes more complex and the stator length increases
Solution Approach 1:
The invention extracts and eliminates the counter bearing arrangement from the conventional design. By strategically positioning the primary bearings at different axial locations on the motor rotor, the design achieves adequate support for machining loads and imbalance forces without requiring additional counter bearings, thereby reducing overall stator length and simplifying the bearing arrangement.
4Stability of the object's composition
If the stator is supported by two widely spaced bearings, then the long stator is stabilized, but the mechanical transmission path becomes longer increasing compliance
Solution Approach 1:
Instead of supporting the long stator with widely spaced bearings, the invention inverts the approach by supporting the rotating rotor with axially distributed bearings. This reversal maintains structural stability while minimizing the mechanical transmission path between the drive source and tool, thereby reducing compliance without sacrificing support stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise and dynamic control of tool movements, improved vibration assessment, and cost-effective manufacturing with minimal components, while providing high mechanical power and resistance to grinding media, facilitating efficient machining of internal gears.
Implementation Method 1
a drive motor with a stator and a rotor is arranged to rotate the second part relative to the first part, wherein the first part of the tool spindle is formed by the stator of the drive motor, wherein the second part is formed by the rotor of the drive motor
Implementation Method 2
both bearings rotatably mount the rotor relative to the stator
Data Source
AI summary
The invention relates to a tool arrangement (1) comprising a tool spindle (2) with a stationary first part (3) and a second part (4) rotatably mounted relative to the first part (3), wherein the second part (4) carries a tool (5), wherein a drive motor with a stator and a rotor is arranged to rotate the second part (4) relative to the first part (3), wherein the first part (3) of the tool spindle (2) is formed by the stator of the drive motor, wherein the second part (4) is formed by the rotor of the drive motor, wherein the stator (3) has a first bearing (9) for mounting the rotor at a first axial position (P1) and a second bearing (10) at a second axial position (P2).In order to further develop such a grinding arrangement in such a way as to create a unit that is as compact as possible, the invention provides that the first bearing (9) has at least one inner ring (11) which is arranged on the outer circumference of the stator (3), and has at least one outer ring (12) which is arranged on an inner cylindrical surface (13) of the rotor (4), wherein the second bearing (10) has at least one outer ring (14) which is arranged on an inner cylindrical surface (15) of the stator (5), and has at least one inner ring (16) which is arranged on an outer cylindrical surface (17) of a cover (18) which is connected to the rotor (4).