Ceramic Coupling for Length Measuring Device Wear Reduction

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Solution Overview

Problem

Existing length measuring devices face challenges in achieving high resolution and accuracy while maintaining stability and cost-effectiveness, as they are prone to wear and misalignment due to environmental influences and design limitations.

Innovation Solution

A length measuring device with a coupling system that rigidly connects the scanning carriage to the driver only in the measuring direction, using ceramic coupling parts with a spherical contact surface to maintain precise guidance and reduce wear, allowing for flexible movement in other directions and minimizing the impact of guide inaccuracies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a very small diameter pin is used to bring the contact point close to the neutral plane of the ruler, then measurement accuracy is improved, but stability deteriorates

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidstability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent changes the material parameter from steel to ceramic for the coupling part, which fundamentally alters the properties. Ceramic material provides both the rigidity needed for stability and the ability to maintain precise contact geometry, resolving the contradiction between small diameter requirements for accuracy and the stability needed for reliable operation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs ceramic material as a composite solution that combines advantages of both steel (strength) and other materials (wear resistance, dimensional stability). This composite approach allows the coupling part to maintain its geometric precision while providing the stability required for reliable measurement over extended periods.

Inventive Principle:
Principle #40Composite materials

2Reliability

If a sliding layer is provided to reduce wear between contacting clutch parts, then wear resistance is improved, but device complexity increases

Engineering Contradiction:
Improvewear resistanceVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a thin sliding film layer that can be easily applied and replaced if needed. This thin layer approach provides wear resistance without requiring complex mechanical structures, maintaining simplicity while improving reliability through the use of a straightforward protective coating.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the surface property of the coupling part by applying a sliding film coating. This parameter change in surface friction and wear characteristics provides protection without adding structural complexity, as the film is applied directly to the existing coupling surface rather than requiring separate mechanical components.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If the coupling is designed to be rigid in the measuring direction and flexible in other directions, then measurement accuracy is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmanufacturing precision
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent applies local quality by designing the coupling to have different mechanical properties in different directions. The coupling is rigid in the measuring direction (X-axis) to maintain measurement accuracy, while remaining flexible in transverse directions to accommodate guide inaccuracies. This anisotropic design is achieved through the ceramic material's inherent properties and the coupling's geometric configuration.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the mechanical parameters of the coupling by selecting ceramic material, which naturally provides high rigidity in compression along the measuring direction while allowing controlled flexibility in other directions. This material parameter selection enables the coupling to meet the directional requirement without excessively high manufacturing precision.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2037230B1Length measuring device
Publication Date: 2012.08.22 DR JOHANNES HEIDENHAIN GMBH
  • EP2037230B1 patent drawingFigure 1
  • EP2037230B1 patent drawingFigure 2

AI summary

The device has a sampling carriage (10) for sampling a measuring partition of a measuring rod (20), and longitudinally guided at guiding surfaces in a measuring direction, where the rod is made from glass. A coupling (14) is provided for coupling the carriage to a carrier (13) that is fastened to an object, where the carriage is movable with respect to the rod. The coupling has coupling parts (141, 142) arranged at the carrier, where one of the coupling parts contains ceramic material e.g. zirconium oxide, in contacting area.