Bore Machining Tool Guide Strip Layout for Chatter Reduction

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Solution Overview

Problem

Cutting tools experience vibrations and chattering during machining of long bores, leading to rapid wear of cutting edges and suboptimal surface quality and roundness due to uneven pitch arrangements of cutting edges and insufficient tool stability.

Innovation Solution

A cutting tool design with stationary and resilient guide rails, where the resilient guide rail is radially preloaded to press the tool against fixed guide rails, reducing oscillations by directing cutting forces radially outward and ensuring stable contact with the bore wall, even in long bores.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If cutting edges are arranged with unequal spacing to ensure smooth running, then tool stability is improved, but vibrations and chatter still occur when machining long bores

Engineering Contradiction:
Improvetool stabilityVSAvoidvibrations and chatter
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The guide rails are designed with resilient mounting that allows dynamic adjustment during machining. The resilient guide rails can deflect and adapt to varying cutting forces, maintaining stable contact with the bore wall while absorbing vibrations, thus resolving the contradiction between stability and vibration reduction.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The spacing and arrangement parameters of the guide rails are optimized - with at least three guide rails positioned at different circumferential locations, and the resilient mounting providing variable contact pressure. This parameter optimization enables the tool to maintain stability while reducing vibrations through controlled flexibility.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the cutting tool is made relatively long to machine long bores, then machining capability is improved, but tool stability deteriorates

Engineering Contradiction:
Improvemachining capabilityVSAvoidtool stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The guide rails act as intermediary elements between the cutting tool and the bore wall. They provide intermediate contact points that distribute cutting forces and provide lateral support to the long tool, enabling the tool to maintain stability while achieving the necessary length for machining long bores.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The guide rails are positioned at specific locations along the tool length and circumferentially distributed to provide localized support where needed. This local reinforcement of stability through strategically placed guide rails allows the overall tool to remain long while maintaining adequate stiffness and stability.

Inventive Principle:
Principle #3Local quality

3Power

If cutting forces are transmitted into the tool body, then cutting action is achieved, but rapid wear of cutting edges occurs

Engineering Contradiction:
Improvecutting actionVSAvoidcutting edge durability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The guide rails extract and bear a portion of the cutting forces that would otherwise be transmitted entirely to the tool body and cutting edges. By providing an alternative force transmission path through the guide rails to the bore wall, the cutting edges experience reduced stress and wear, extending their durability while maintaining effective cutting action.

Inventive Principle:
Principle #2Taking out (Extraction)

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

The design significantly reduces tool oscillations and chatter, enhancing surface quality and roundness by maintaining stable contact with the bore wall, thus improving machining performance, especially in long bores.

Implementation Method 1

at least one of the guide rails is resiliently mounted to the tool body, so that it projects more or less far beyond the circumferential surface of the tool body. It is subjected to a preload that pushes the resilient guide rail radially outwards. Due to the spring force of the resiliently mounted guide rail, the cutting tool is elastically pressed against the two fixed guide rails during machining and/or drilling a bore.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3137248B1Machining tool with stationary and spring-mounted guide strips
Publication Date: 2021.10.13 MAPAL DR KRESS SE & CO KG
  • EP3137248B1 patent drawingFigure 1~3
  • EP3137248B1 patent drawingFigure 4~6

AI summary

The invention relates to a machining tool for machining bores, comprising a main part (3) which has a central axis (5) in a circumferential surface (7), at least two geometrically defined cutting edges (9/1 to 9/5) which are unevenly distributed on the circumferential surface (7) of the machining tool (1) when seen in the circumferential direction of the machining tool (1), and a number of guide strips which project from the circumferential surface (7) of the main part (3). The machining tool (1) is characterized in that two guide strips (19/1, 19/2) are designed to be stationary and are arranged with a circumferential spacing of less than 180° relative to one another such that a first circumferential region (21/1) is formed which lies between the stationary guide strips and extends over more than 180°, and a second circumferential region (21/2) is formed which extends over less than 180°; such that one (9/1, 9/2) of the at least two cutting edges (9/1 to 9/5) is arranged in the second circumferential region (21/2) between the stationary guide strips (19/1, 19/2); and such that at least one guide strip (23) is spring-mounted on the main part (3), and the at least one spring-mounted guide strip (23) is arranged in the first circumferential region (21/1) such that the at least one spring-mounted guide strip (23) resiliently presses the machining tool (1) against the stationary guide strips (19/1, 19/2) when machining a bore.