Spindle Shaft Electrical Discharge via Tangential Rod Elements

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Solution Overview

Problem

Highly sensitive measuring devices in machine tools, such as structure-borne noise or vibration sensors, experience significant deviations and fluctuations due to electrical charging of the spindle shaft, affecting precision and reproducibility.

Innovation Solution

A spindle device with an electrically grounded section featuring rod elements made of conductive material, arranged tangentially on the spindle shaft, ensures effective discharge of electrical charges, reducing interference with sensitive measuring devices and allowing for precise control of the machine tool.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If grinding brushes are used to derive potential from the spindle shaft, then electrical discharge is achieved, but device complexity and wear increase

Engineering Contradiction:

Improveelectrical discharge capabilityVSAvoidcomplexity of derivation device

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs rod-shaped derivation elements that are simpler and more durable than grinding brushes. These elements can be easily replaced when worn and provide a more reliable electrical discharge path without the complexity of brush mechanisms, aligning with the principle of using simple, replaceable components

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent replaces the mechanical grinding brush system with a simpler rod element system that relies on elastic pressing forces rather than friction-based grinding. This substitution reduces mechanical complexity and wear while maintaining effective electrical discharge capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution enhances the accuracy and reduces scatter of measured values, enabling more precise control of the machine tool by preventing electrical potential from influencing sensitive measuring devices.

Implementation Method 1

at least one element having an electrically conductive material, wherein the at least one rod element is arranged in such a way that it touches the spindle shaft in a tangential manner

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

the spindle device has at least one resilient element for each rod element, which attaches the respective rod element to the Outer circumference of the spindle shaft presses

Methodology Applied

Scientific EffectElastic force: Elasticity

Data Source

PatentEP3447858B1Spindle device for use on a numerically controlled machine tool

Publication Date: 2020.05.13 DECKEL MAHO PFRONTEN GMBH

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AI summary

The present invention relates to a spindle device 100 for use on a numerically controlled machine tool, comprising: a spindle housing 1, and a spindle shaft 15 mounted in the spindle housing, wherein the spindle device 100 further comprises an electrically grounded section 4 which holds at least one rod element 20 having an electrically conductive material, and wherein the at least one rod element 20 is arranged such that it tangentially contacts the spindle shaft 15 at an outer circumference of the spindle shaft 15.