Touch Probe Calibration on Gear Tooth Flanks Without Measuring Blocks

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Solution Overview

Problem

Gear cutting machines face imprecision in probe calibration due to external influences like temperature fluctuations, leading to position errors that existing methods struggle to accurately compensate for, especially when using external measuring blocks is impractical or impossible.

Innovation Solution

A method that calibrates the probe directly on a workpiece by moving it relative to the workpiece holder over two axes, rotating the workpiece to maintain contact with the tooth flank, and determining deflection deviations to calculate correction values, eliminating the need for external reference objects and allowing comprehensive calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a measuring block is used for calibration, then the probe position can be determined, but the process requires manual intervention and additional setup time

Engineering Contradiction:
Improveprobe position determinationVSAvoidcalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The gear wheel itself serves as the measurement object for calibration, eliminating the need for separate measuring blocks. The system automatically determines probe position by measuring tooth flanks directly on the workpiece, making the calibration process self-contained and eliminating manual setup steps.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The workpiece serves dual purposes: it is both the object to be manufactured and the reference object for calibration. By using the gear wheel's own tooth flanks as the measurement surface, the system eliminates the need for separate calibration artifacts, making the process universally applicable to any gear wheel production.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If a measuring block is used for calibration, then probe position can be checked, but the method cannot be applied when traverse paths are insufficient to reach the measuring block

Engineering Contradiction:
Improveprobe position determinationVSAvoidapplicability to different machine configurations
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The gear wheel serves as its own calibration reference, eliminating the need for external measuring blocks that require sufficient traverse paths. By measuring features that are inherently part of the workpiece (tooth flanks), the system becomes adaptable to machines with limited traverse capabilities.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The tooth flanks of the gear wheel act as an intermediary measurement surface that is always accessible within the machine's working envelope. This intermediary reference allows probe position determination without requiring the probe to reach external measuring blocks that may be out of reach.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If the probe is moved tangentially to the base circle for calibration, then profile angles can be measured, but the method is complex and requires precise tangential positioning

Engineering Contradiction:
Improveprofile angle measurementVSAvoidcalibration method complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of moving the probe tangentially to the base circle as in conventional methods, the patent rotates the gear wheel and moves the probe in non-tangential directions (radially and axially). This inverted approach simplifies the measurement geometry and eliminates the need for precise tangential positioning while still enabling accurate probe calibration.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces axial movement of the probe in addition to radial movement, adding a third dimension to the calibration process. By measuring tooth flanks at different axial positions and combining this with radial measurements, the system achieves accurate probe positioning without requiring complex tangential motion control.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 method provides a simpler, fully automatic calibration process that effectively corrects position errors in both directions, ensuring precise probe alignment without external measuring blocks, suitable for various types of tooth profiles and gear cutting machines.

Implementation Method 1

the deflection of the probe tip relative to the probe base and/or the achievement of a deflection of the probe tip relative to the probe base can be determined via at least one sensor of the probe

Methodology Applied
Scientific EffectDeflection detection via sensor:

Data Source

PatentEP3712552B1Method for calibrating a touch probe in a gear cutting machine
Publication Date: 2021.03.10 LIEBHER VERZAHNTECHNIK GMBH
  • EP3712552B1 patent drawingFigure 1
  • EP3712552B1 patent drawingFigure 2~3
  • EP3712552B1 patent drawingFigure 4

AI summary

The present application discloses a method for calibrating a measuring probe in a gear cutting machine using a workpiece held in a workpiece fixture of the gear cutting machine. The measuring probe has a probe tip that is movably arranged on a probe base. The deflection of the probe tip relative to the probe base can be determined via at least one sensor of the probe, and the measuring probe is movable relative to the workpiece fixture via at least two axes of motion of the gear cutting machine. The method comprises rotating the workpiece about a rotational axis of the workpiece fixture and moving the measuring probe about the at least two axes of motion of the gear cutting machine such that the point of contact of the probe tip on the tooth flank would remain unchanged with perfect calibration.