Motor Spindle Floating Bearing for Precise Rotor Replacement

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Solution Overview

Problem

Existing motor spindles face challenges in achieving high-precision and reproducible replacement of the rotor, with potential damage to bearings due to contact and unintentional removal during operation, especially under thermal expansion differences between the stator and rotor.

Innovation Solution

The design incorporates a second rotary bearing with an axial floating bearing that compensates for thermal expansions, maintaining a consistent air gap along the adjustment path to prevent contact and includes a locking mechanism with adjustable bolts for secure attachment, ensuring reliable radial and axial locking of the rotor to the stator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the second pivot bearing is designed as an axial loose bearing to compensate for thermal expansion, then thermal expansion compensation is improved, but the risk of bearing damage due to contact or unintentional removal increases

Engineering Contradiction:
Improvethermal expansion compensationVSAvoidbearing damage prevention
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by pre-defining a limited adjustment path for the second coupling part that prevents it from moving into positions where contact with the inner ring would occur. The bearing gap is designed with predetermined boundaries that stop the floating bearing from displacing too far, thereby preventing bearing damage before it can happen during thermal expansion cycles

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent implements dynamics by allowing the second coupling part to move axially within a defined adjustment path to accommodate thermal expansion differences between stator and rotor. The floating bearing design enables dynamic adaptation to temperature changes while the limited adjustment path ensures this movement remains within safe boundaries that prevent bearing damage

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the second coupling part is made axially movable to compensate for thermal expansion, then thermal adaptation is improved, but the risk of accidental bearing removal during rotor replacement increases

Engineering Contradiction:
Improvethermal adaptationVSAvoidbearing retention during rotor replacement
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent prevents accidental bearing removal by pre-establishing a limited adjustment path that restricts the axial movement of the second coupling part. The bearing gap is designed with predetermined boundaries that prevent the floating bearing from displacing far enough to be accidentally removed during rotor replacement operations, while still allowing sufficient movement for thermal expansion compensation

Inventive Principle:
Principle #9Preliminary anti-action

3Manufacturing precision

If the bearing gap is reduced to improve precision, then manufacturing precision is improved, but the risk of contact between bearing components increases

Engineering Contradiction:
Improverotor replacement precisionVSAvoidcontact damage risk
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent resolves the precision-contact contradiction by implementing a dynamic floating bearing design where the second coupling part can move axially within a limited adjustment path. This dynamic capability allows the bearing to maintain optimal gaps under normal operating conditions for high precision, while automatically adjusting during thermal expansion to prevent contact damage

Inventive Principle:
Principle #15Dynamics

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

This solution ensures high-precision and reproducible rotor replacement, prevents damage to bearings, and compensates for thermal expansions, maintaining operational stability and reliability.

Implementation Method 1

heat influences occurring during operation of the motor spindle, which can lead to different expansions of the stator and the rotor, can be compensated for by a displacement in the second pivot bearing

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3998134B1Motor spindle
Publication Date: 2024.02.28 MASCHFAB BERTHOLD HERMLE AG
  • EP3998134B1 patent drawingFigure 1
  • EP3998134B1 patent drawingFigure 2~3
  • EP3998134B1 patent drawingFigure 4

AI summary

Motor spindle (1) with a sleeve-shaped stator (2) having a first coupling receptacle (11) and a second coupling receptacle (12), with a rotor (4) having a first coupling part (41) with axial fixed bearing and a second coupling part (42) with axial floating bearing, which are designed for fixing to the respective coupling receptacle (12), wherein the axial floating bearing comprises an inner ring (62) fixed on the rotor shaft (5) and an outer ring (63) arranged coaxially to the inner ring (62) and fixed to the second coupling part (42),wherein the second coupling part (42) is axially movable on the rotor shaft (5) parallel to the rotor axis (6) between a first functional position and a second functional position along an adjustment path (14) and wherein a first distance (58) exists between a first axial surface (66) of the inner ring (62) and the second coupling part (42) for the entire adjustment path (14) and a second distance (59) exists between a second axial surface (67) of the inner ring (62) and the second coupling part (42).