Analogue Probe Temperature Control for CMM Accuracy

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Solution Overview

Problem

Temperature changes in the operating environment significantly degrade the accuracy of analogue probes used in coordinate positioning machines due to thermal expansion effects, leading to erroneous measurements.

Innovation Solution

A method involving a temperature actuator and sensor to maintain the analogue probe at a predetermined temperature, compensating for environmental and machine temperature changes, ensuring stability and accuracy by modulating the temperature actuator to keep the probe within a specified tolerance range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the analogue probe is used in varying temperature environments, then the measurement process can continue without interruption, but the measurement accuracy significantly degrades due to thermal expansion effects

Engineering Contradiction:
Improvemeasurement continuityVSAvoidmeasurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by actively controlling the temperature of the analogue probe to maintain it at a constant predetermined temperature despite environmental temperature variations. The temperature actuator dynamically adjusts the probe's temperature parameter to compensate for thermal expansion effects, thereby maintaining measurement accuracy while allowing continuous operation in varying temperature environments.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If a temperature actuator is added to control probe temperature, then measurement accuracy is maintained under temperature variations, but device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidprobe structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements self-service by integrating a temperature actuator and temperature sensor directly into the probe body, enabling the probe to autonomously regulate its own temperature. The temperature sensor monitors the probe's temperature and provides feedback to the temperature actuator, which automatically adjusts heating or cooling to maintain the predetermined temperature, eliminating the need for external temperature control systems.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If the probe temperature is actively controlled to a predetermined temperature, then thermal expansion effects are compensated, but additional energy is consumed by the temperature actuator

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies feedback control by using a temperature sensor to continuously monitor the probe's temperature and providing this information to the temperature actuator. The actuator adjusts its heating or cooling output based on the temperature feedback to maintain the probe at the predetermined temperature, thereby compensating for thermal expansion effects while optimizing energy consumption by only activating when temperature deviations occur.

Inventive Principle:
Principle #23Feedback

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 approach effectively reduces the impact of temperature variations on measurement accuracy, ensuring consistent and reliable results by maintaining the probe's temperature, thus preventing warm-up/cool-down delays and variations in measuring accuracy.

Implementation Method 1

due to thermal expansion effects, changes in the temperature of the operating environment in which the analogue probe is used can significantly degrade the accuracy of the analogue probe

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2142878B1Analogue probe with temperature control and method of operation
Publication Date: 2018.09.26 RENISHAW PLC
  • EP2142878B1 patent drawingFigure 1~2
  • EP2142878B1 patent drawingFigure 3a~5

AI summary

An analogue probe for use with a coordinate positioning machine. The analogue probe comprises a temperature actuator which can be modulated so as maintain the temperature of at least a part of the analogue probe at a substantially constant predetermined temperature.