Pneumatic Probe Head for Precision Small Object Measurement

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Solution Overview

Problem

Conventional coordinate measuring machines face challenges in achieving high repeatability and precision when measuring small objects due to the limitations of probing force and the tendency of probe bodies to bend, leading to poor repeat accuracy.

Innovation Solution

The device employs a pneumatic measuring principle with a probe head that can be mounted at variable inclination, using pneumatic measuring nozzles to detect changes in position and deformation, allowing for lower contact forces and reduced probe body deformation, enabling precise measurement of small objects with improved stability and repeatability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional probing systems with switching systems are used, then the device is easy and inexpensive to manufacture, but a point can only be touched once in one direction and the probe body has to be returned to its original position resulting in time delay

Engineering Contradiction:
Improveease of manufactureVSAvoidmeasurement speed
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces the mechanical switching system with a pneumatic measurement system. Instead of using electrical contacts that open/close to detect probe position, the invention uses pneumatic nozzles that detect changes in air pressure or air flow when the probe body moves. This substitution eliminates the need for mechanical return movements while maintaining manufacturing simplicity, as pneumatic components are also relatively simple to manufacture.

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

Solution Approach 2:

The patent introduces pneumatic nozzles as an intermediary detection mechanism. Rather than directly detecting probe contact through electrical switches, the system uses air flow through nozzles as an intermediate physical quantity that changes when the probe body moves. This intermediary measurement method enables continuous position detection without requiring the probe to return to its original position, thus improving measurement speed.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Force

If small probe bodies with diameter less than 0.5 mm are used, then the probing force can be reduced, but bending of the probe body results in undesirably poor repeat accuracy

Engineering Contradiction:
Improveprobing forceVSAvoidrepeat accuracy
Core Design Contradiction:
ForceVSMeasurement precision

Solution Approach 1:

The patent replaces direct mechanical contact measurement with pneumatic field measurement. Instead of relying on the mechanical stiffness of thin probe bodies to maintain accuracy under low probing forces, the system uses pneumatic nozzles to detect probe position changes. This substitution allows the use of very thin probe bodies (less than 0.3 mm) with minimal probing force while maintaining high repeat accuracy through non-contact or near-contact pneumatic detection.

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

3Length of moving object

If probe bodies thinner than 0.3 mm are used, then smaller objects can be measured, but bending of the probe body results in undesirably poor repeat accuracy

Engineering Contradiction:
Improveprobe body thicknessVSAvoidrepeat accuracy
Core Design Contradiction:
Length of moving objectVSMeasurement precision

Solution Approach 1:

The patent substitutes mechanical position detection with pneumatic field detection. By using pneumatic nozzles that detect air pressure or flow changes, the system can accurately measure the position of extremely thin probe bodies (less than 0.3 mm) without being affected by their bending. The pneumatic detection method is sensitive enough to detect subtle position changes even when the probe body is very flexible, thereby maintaining repeat accuracy despite the use of ultra-thin probe structures.

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

This solution enables precise and repeatable measurements of small objects with reduced probing forces, maintaining high stability and minimizing deformation, thus enhancing the accuracy and reliability of coordinate measurements.

Implementation Method 1

the means for detecting a change in the inclination of the probe or vice versa include at least one pneumatic measuring nozzle, which opens into a recess in the probe

Methodology Applied
Scientific EffectPneumatic measurement: Pressure Drop

Data Source

PatentEP2378240B1Device for measuring objects
Publication Date: 2017.05.10 STOTZ FEINMESSTECHN
  • EP2378240B1 patent drawingFigure 1
  • EP2378240B1 patent drawingFigure 2
  • EP2378240B1 patent drawingFigure 3

AI summary

The device has a probe head (13) moved relative to an object (11) to be measured by an actuator to touch an upper surface of the object. A probe body (15) is angle-variably supported with freedom of movement along a direction at the probe head. Pneumatic measuring nozzles (31, 32, 35, 36, 39) detect movement of the probe body relative to the probe head by measuring a test parameter, where the test parameter is provided as a distance of the probe body from a reference point. The probe body is supported in a retainer (17) of the probe head.