Roller Centering Tool for Inscribed-Circle Workpiece Alignment

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Solution Overview

Problem

Existing centering methods for circular workpieces fail to accurately align the center of the maximum inscribed circle, which is necessary for high-precision machining, and lack a simple and precise method for determining centering success or failure.

Innovation Solution

A centering tool with a pair of rollers and a displacement sensor that follows the workpiece's shape, allowing for centering based on the inscribed circle, and a control unit that determines the feed target position and confirms contact, ensuring precise alignment and reducing misalignment to an allowable range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If one-point contact is used to push the cylindrical workpiece, then the centering process is simple, but the centering precision is insufficient for high-precision machining

Engineering Contradiction:
Improvecentering tool structureVSAvoidcentering precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The single contact point is segmented into a pair of contacts (rollers) that are disposed apart from each other. This segmentation allows the tool to follow the workpiece shape more accurately and achieve inscribed circle centering, which is essential for high-precision machining while maintaining operational simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces direct pushing contact with rolling contact using rollers. This mechanical substitution reduces friction and allows the contacts to follow the workpiece contour more accurately, enabling precise detection of the inscribed circle center without damaging the workpiece surface.

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

2Manufacturing precision

If continuous pushing is performed to settle the runout, then the centering is achieved, but the process complexity increases and requires additional pass or fail determination

Engineering Contradiction:
Improvecentering accuracyVSAvoidcentering process steps
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The displacement sensor provides real-time feedback on the workpiece position and runout during rotation. This feedback mechanism allows the control system to automatically determine when centering is complete and whether the pass/fail criteria are met, eliminating the need for complex manual determination processes.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The centering tool with a pair of rollers automatically follows the workpiece shape and performs self-adjustment during rotation. The system self-determines the inscribed circle center and runout conditions without requiring additional complex control steps or manual intervention.

Inventive Principle:
Principle #25Self-service

3Device complexity

If the displacement sensor is positioned away from the contacts, then the measurement is simpler, but the measurement accuracy for inscribed circle centering is reduced

Engineering Contradiction:
Improvesensor positioningVSAvoiddisplacement detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The displacement sensor is merged with the shank portion and positioned at the same height as the pair of contacts. This merging ensures that the sensor measures the actual displacement at the contact point, providing accurate inscribed circle centering data while maintaining a simple integrated structure.

Inventive Principle:
Principle #5Merging (Combining)

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 high-precision centering of circular workpieces by aligning the inscribed circle with the rotary table's center, ensuring machining allowance and allowing for accurate determination of centering success, thereby facilitating high-precision machining and manufacturing.

Implementation Method 1

a displacement sensor provided integrally with the shank portion and detecting displacement in the direction orthogonal to the axis at an intermediate position between the pair of contacts

Methodology Applied
Scientific EffectDisplacement detection: Displacement

Implementation Method 2

the pair of contacts are rollers rotating around axes parallel to the axis

Methodology Applied
Scientific EffectRolling contact: Roller

Data Source

PatentEP4015141B1Centering tool, centering device, machine tool, method of centering circular workpiece, circular workpiece manufacturing method, ring member manufacturing method, bearing manufacturing method, machine manufacturing method, vehicle manufacturing method, and program
Publication Date: 2026.04.22 NSK LTD
  • EP4015141B1 patent drawingFigure 1
  • EP4015141B1 patent drawingFigure 2A~2B
  • EP4015141B1 patent drawingFigure 3

AI summary

A centering tool includes: a shank portion having a shaft portion for attachment; a rotating member rotatably supported by the shank portion and having a pair of contacts disposed apart from each other in a direction orthogonal to an axis of the shank portion; and a displacement sensor provided integrally with the shank portion and detecting displacement in the direction orthogonal to the axis of the shank portion at an intermediate position between the pair of contacts, in which a circular workpiece is centered by being pushed toward a rotation center of a rotary table while each of the pair of contacts is caused to abut against a peripheral surface of the circular workpiece disposed on the rotary table.