Spindle-Mounted Optical Measurement for Machine Tool Motion Errors

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Solution Overview

Problem

Existing machine tools face challenges in accurately calculating movement errors during translational and rotational movements of components, which affect the precision of workpiece processing.

Innovation Solution

An optical apparatus is attached to the main spindle of a machine tool, capable of changing the direction of measurement light and receiving returning light from fiducial members to calculate the position and distance of the optical apparatus, using a computing unit to determine positional and distance information for precise movement control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an optical apparatus is attached to the main spindle to measure movement errors, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvemovement error calculation precisionVSAvoidoptical apparatus structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The optical apparatus is integrated into the main spindle structure, with the direction change member and light receiving unit nested within the existing spindle components. This allows the measurement system to be housed within the main spindle without requiring separate external measurement devices, thereby improving measurement precision while minimizing the increase in overall device complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The main spindle is designed to serve dual functions: both tool holding/processing and optical measurement. The optical apparatus attached to the main spindle enables movement error measurement while the spindle continues its primary function of holding and rotating tools for workpiece processing. This multi-functionality resolves the contradiction by eliminating the need for completely separate measurement systems.

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

2Measurement precision

If multiple fiducial members are used for optical reception, then measurement precision is improved, but the time required for measurement increases

Engineering Contradiction:
Improveposition and distance calculation precisionVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The optical apparatus performs periodic scanning of multiple fiducial members in sequence rather than simultaneously measuring all of them. The direction change member directs measurement light to different fiducial members at different time intervals, allowing the system to collect data from multiple reference points while maintaining a continuous measurement cycle that minimizes total measurement time.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The positions of multiple fiducial members are predetermined and pre-configured on the workpiece or measurement table. This preliminary arrangement allows the optical apparatus to efficiently navigate to and measure each fiducial member in a predetermined sequence, reducing the time required for real-time positioning and measurement calculations.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If the optical apparatus measures both position and distance, then manufacturing precision is improved, but the complexity of the measurement system increases

Engineering Contradiction:
Improveworkpiece processing precisionVSAvoidoptical measurement system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The optical apparatus combines position measurement and distance measurement functions into a single integrated system. The direction change member and light receiving unit work together to simultaneously determine both the angular position and radial distance to fiducial members, eliminating the need for separate position sensors and distance sensors that would otherwise be required.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system replaces complex mechanical measurement mechanisms with optical measurement. Instead of using mechanical probes or contact-based measurement devices that would require complex positioning mechanisms, the patent uses optical fields to measure both position and distance non-contactfully, thereby improving manufacturing precision while managing system complexity through the use of light-based sensing.

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

Enhances the precision of machine tool operations by accurately calculating movement errors, allowing for improved processing of workpieces through enhanced positional and distance measurements.

Implementation Method 1

a light receiving unit that optically receives returning light, which is generated by irradiating each of a plurality of fiducial members with the measurement light whose propagating direction has been changed by the direction change member, from each of the plurality of fiducial members

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP4616996A1Measurement system, machine tool, optical device, measurement method, computer program, and recording medium
Publication Date: 2025.09.17 NIKON CORP
  • EP4616996A1 patent drawingFigure 1
  • EP4616996A1 patent drawingFigure 2
  • EP4616996A1 patent drawingFigure 3~4

AI summary

An optical apparatus is attached to a main spindle instead of a tool in a machine tool, the machine tool processes a workpiece by the tool attached to the main spindle of a processing head while moving at least one of a stage, on which the workpiece is placed, and the processing head, the optical apparatus includes: a direction change member for changing a propagating direction of measurement light; and a light receiving unit for optically receiving returning light, which is generated by irradiating each of fiducial members with the measurement light whose propagating direction has been changed by the direction change member, from each of the fiducial members, the light receiving unit optically receives the returning light that is generated by irradiating each of at least one fiducial member, which is positioned on the workpiece that is placed on the stage, and at least another one fiducial member, which is positioned on the stage or on the workpiece that is placed on the stage, of the fiducial members with the measurement light.