Asymmetric Turning Tools Suppress Chatter Vibration

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Solution Overview

Problem

Existing turning methods face challenges in suppressing chatter vibrations, particularly when dealing with long workpieces, leading to decreased accuracy and stability, especially when the workpiece has low rigidity.

Innovation Solution

The method involves shifting the arrangement of cutting tool edges around the rotation center axis by a specific offset angle and pitch difference, allowing for unequal pitch turning or swing turning to balance turning forces and reduce chatter vibrations, using a machine tool with detection and calculation means to optimize these angles based on chatter frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the edges of two cutting tools are placed opposite to each other at an angle of 180°, then the turning efficiency is doubled and static deflection is suppressed, but the stability with respect to chatter vibration is low

Engineering Contradiction:
Improveturning efficiencyVSAvoidchatter vibration stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies asymmetry by intentionally offsetting the arrangement of cutting tool edges from the symmetric 180° opposition. The first edge of the first cutting tool and the second edge of the second cutting tool are positioned at unequal angles relative to the rotation center axis, creating an asymmetric configuration that disrupts the regenerative chatter vibration mechanism while maintaining balanced turning forces for stable processing.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If a tail means or side guide mechanism is used to support the workpiece, then chatter vibration is suppressed, but it is difficult to turn the workpiece to have the desired shape or special mechanisms are required

Engineering Contradiction:
Improvechatter vibration suppressionVSAvoidsupport mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the need for complex external support mechanisms (tail means, roller guides) by addressing the root cause of chatter vibration through the asymmetric edge arrangement of the cutting tools. This approach suppresses chatter vibration inherently through the cutting process configuration rather than relying on additional support devices, thereby simplifying the overall system.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If the edge arrangement is offset by a given angle, then regenerative chatter vibration is canceled and turning stability is enhanced, but the clearance angle may become lower than a given angle causing abnormal tool abrasion

Engineering Contradiction:
Improveturning stabilityVSAvoidtool edge strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies parameter changes by optimizing the offset angle within specific ranges that simultaneously achieve chatter vibration suppression and maintain adequate clearance angles. By carefully selecting and adjusting the angular parameters of the asymmetric edge arrangement, the patent finds the optimal balance between stability enhancement and tool edge integrity, preventing both chatter vibration and abnormal tool abrasion.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3196721B1Turning method for suppressing chatter vibration and machine tool
Publication Date: 2019.07.31 NAKAMURATOME SEIMITSU IND
  • EP3196721B1 patent drawingFigure 1
  • EP3196721B1 patent drawingFigure 2A~2C
  • EP3196721B1 patent drawingFigure 3

AI summary

A turning method and a machine tool for reducing or suppressing the occurrence of a chatter vibration during turning, e.g. with a lathe,, using a rotatable main spindle (10) to hold a workpiece (W) and machining the workpiece (W) with a first (11) and a second (12) tool, which are situated opposite to each other at an angle of 180° around the rotation center axis (P), and swinging the first tool (11) within an angle range (Δφ) or offsetting the first tool (11) by an offset angle (φ1), based on the frequency of the detected chatter vibration.