Liquid Level Reference for Coordinate Measuring Machine Guide Alignment

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Solution Overview

Problem

Coordinate measuring machines face challenges in correcting guidance errors caused by foundation settlement, workpiece mass, and temperature changes, which are time-dependent and not stable in the long term, leading to precision issues and high costs for creating stable foundations and recalibrating guide errors.

Innovation Solution

A coordinate measuring machine utilizing a liquid-filled device made of communicating tubes, where liquid surfaces of equal height establish a reference system, allowing measuring devices to determine height differences and correct guidance errors by evaluating changes in liquid levels to adjust the position of guides relative to a fixed point, thereby accounting for dynamic guidance errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If inherently rigid foundations are used to minimize guidance changes, then measurement precision is improved, but the effort and cost for creating and maintaining these foundations increases

Engineering Contradiction:
Improveguidance error stabilityVSAvoidfoundation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism by continuously monitoring the position of guides using sensors and comparing them against reference values. When deviations are detected, the system automatically generates correction signals to adjust the guide positions, thereby maintaining measurement precision without requiring inherently rigid foundations

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical approach of creating rigid foundations with a sensor-based detection and correction system. Instead of relying on physical rigidity to prevent guidance errors, the system uses electronic sensors, signal processing, and automated correction mechanisms to compensate for foundation deformations and guide position changes

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If highly rigid foundations are used to prevent torsional guide errors, then guidance stability is improved, but the cost and effort for foundation creation and transport increases

Engineering Contradiction:
Improveguide parallelism stabilityVSAvoidfoundation manufacturing effort
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The system uses sensors to continuously monitor the relative positions and parallelism of multiple guides. When torsional errors or skewing are detected, the feedback mechanism automatically adjusts the guide positions to restore proper parallelism, eliminating the need for highly rigid foundations that would otherwise be required to prevent such errors

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The correction system operates autonomously by continuously detecting guide position deviations and automatically implementing corrections without human intervention. This self-service capability allows the system to maintain guide stability dynamically, replacing the need for statically rigid foundations

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If foundation shrinkage is allowed to occur naturally, then manufacturing simplicity is improved, but guidance errors increase requiring recalibration

Engineering Contradiction:
Improvefoundation manufacturing simplicityVSAvoidguidance error accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic correction system that adapts to changing foundation conditions over time. As the foundation shrinks or deforms, the sensors continuously detect resulting guide position changes, and the system dynamically adjusts correction values to maintain measurement precision throughout the foundation's service life

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system performs preliminary detection of guide position deviations caused by foundation shrinkage and applies corrections in advance before these deviations significantly impact measurement accuracy. This proactive approach maintains precision without requiring the foundation to be manufactured with excessive rigidity

Inventive Principle:
Principle #10Preliminary action

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 improves the long-term accuracy and reduces the effort required for foundation stability and recalibration, maintaining measurement precision while minimizing the need for highly rigid foundations and extensive air conditioning.

Implementation Method 1

a liquid-filled device made of communicating tubes in which liquid surfaces of the same height are established in relation to the gravitational field of the earth

Methodology Applied
Scientific EffectCommunicating tubes principle: Pascal's Law

Data Source

PatentEP2734807B1Coordinate measuring apparatus having a device consisting of communicating tubes
Publication Date: 2015.05.06 CARL ZEISS INDUSTRIELLE MESSTECHNIKE GMBH
  • EP2734807B1 patent drawingFigure 1~2
  • EP2734807B1 patent drawingFigure 3
  • EP2734807B1 patent drawingFigure 4

AI summary

The invention relates to a coordinate measuring assembly (1), comprising a base (2), a guide (7, 8; 29, 30) which is fixed relative to the base (2) and by means of which a movement of a movable part is guided, characterised by a liquid-filled device (16) consisting of communicating tubes (17, 8, 19, 20; 36, 37, 38) in which liquid surfaces of the same height relative to the gravitational field of the earth are established, measuring units (22, 23; 33, 34, 35) that are assigned to the tubes and determine the respective liquid level in the tube and/or the difference in height between the liquid surface and a fixed point (24, 25), which is immovable relative to the guide (7, 8). The invention further relates to a method for determining the position of a part of a coordinate measuring apparatus, in particular a guide for guiding the movement of a movable further part of the coordinate measuring apparatus.