Machine Tool Diameter Measurement With Single-Point Referencing

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Solution Overview

Problem

Existing methods for measuring workpiece diameter in machine tools require multiple probes, leading to complex operations and increased measurement time, limited accuracy, and restricted applicability due to stroke length limitations.

Innovation Solution

A method involving a contact or non-contact sensor to measure coordinates of a single point on the workpiece circumference, using a reference point to calculate diameter, minimizing movement distance and stroke requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If three-point measurement method is used to ensure measurement accuracy, then measurement precision is improved, but measurement time increases and productivity decreases

Engineering Contradiction:
Improveworkpiece diameter measurement accuracyVSAvoidmeasurement speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The invention extracts only the essential measurement information by measuring just two points on the workpiece circumference instead of three points. By utilizing the relationship between the two measured points and the known workpiece center position, the diameter can be calculated without requiring a third measurement point, thus reducing measurement time while maintaining accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The workpiece center position is predetermined or pre-calculated before the actual diameter measurement. This preliminary determination of the center position allows the measurement system to calculate diameter from just two points rather than requiring three points, thereby speeding up the measurement process without sacrificing precision.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If three-point measurement method is used to ensure measurement accuracy, then measurement precision is improved, but operational complexity increases

Engineering Contradiction:
Improveworkpiece diameter measurement accuracyVSAvoidmeasurement operation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention simplifies the measurement operation by extracting only the necessary two points for diameter measurement, eliminating the need to position and measure a third point. This reduction from three-point to two-point measurement directly decreases operational complexity while the calculation method based on predetermined center position maintains measurement accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

3Adaptability or versatility

If tool post moves long distance to measure three points, then measurement coverage is improved, but measurement time increases and productivity decreases

Engineering Contradiction:
Improvemeasurement coverageVSAvoidmeasurement efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The invention reduces the measurement coverage requirement by extracting only two essential measurement points instead of three. This allows the tool post to move a shorter distance along the workpiece circumference, thereby improving measurement efficiency and productivity while still obtaining sufficient data to calculate the diameter accurately using the predetermined center position.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If stroke length of tool post is limited, then device complexity is reduced, but adaptability to different workpiece sizes decreases

Engineering Contradiction:
Improvetool post structure simplicityVSAvoidworkpiece size range
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The invention transitions from requiring extensive linear movement along the workpiece circumference to utilizing the radial dimension by measuring from predetermined center position to two points on the circumference. This dimensional approach allows measurement of various workpiece sizes with a limited stroke tool post, thereby improving adaptability without increasing device complexity.

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

Solution Approach 2:

The workpiece center position is predetermined or pre-calculated, enabling the measurement system to adapt to different workpiece sizes without requiring the tool post to traverse the entire circumference. This preliminary knowledge of the center position allows accurate diameter measurement of various sized workpieces within the limited stroke capability of the tool post.

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

Enables rapid and accurate measurement of workpiece diameter with reduced operational complexity and increased applicability to various workpieces.

Implementation Method 1

measuring the coordinates of three points along the outer circumference of the workpiece by using a contact type position detection sensor

Methodology Applied
Scientific EffectContact detection:

Data Source

PatentEP4283247B1Workpiece diameter measurement method and machine tool
Publication Date: 2025.12.31 DMG MORI CO LTD
  • EP4283247B1 patent drawingFigure 1
  • EP4283247B1 patent drawingFigure 2
  • EP4283247B1 patent drawingFigure 3

AI summary

Disclosed is a workpiece diameter measurement method including the steps of: measuring coordinates of a point P that is on an outer circumferential surface of a cylindrical workpiece that is supported such that a rotary axis of a main spindle of a machine tool and a central axis of the cylindrical workpiece coincide with each other, the coordinates having a maximum or minimum coordinate in a first direction that is orthogonal to the rotary axis; calculating a distance D2 in the first direction between the point P and a reference point Q that is a point at which a distance D1 in the first direction from the rotary axis is known; and calculating a workpiece diameter of the cylindrical workpiece based on the distance D1 and the distance D2.