Cylinder Bore Roughening with Dual Cutting Heads and Chip Flushing

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Solution Overview

Problem

Existing methods for roughening the inner surface of cylindrical bores are limited by chip accumulation and jamming issues, especially on horizontal spindles, leading to surface quality deterioration and inadequate thermal coating adhesion, particularly with light metals like aluminum.

Innovation Solution

A tool with two radial cutting heads for finishing and roughening, where one cutting head is positioned ahead of the other, and a flushing medium is used to direct chips away from the surface, allowing for efficient chip removal and preventing jamming, even on horizontal spindles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single radial cutting head is used for roughening the inner surface of a cylindrical bore, then the machining time is short and coating adhesion is excellent, but chips accumulate and jam the tool especially on horizontal spindles, deteriorating surface quality and impairing coating adhesion

Engineering Contradiction:
Improvemachining timeVSAvoidchip removal reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The single cutting head is divided into two separate cutting heads: a first radial cutting head for finishing and a second radial cutting head for roughening. This segmentation allows each cutting head to perform its specific function optimally while enabling independent chip removal paths, preventing chip accumulation and jamming that occurs with a single cutting head.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If the tool and bore are aligned axially in the vertical direction, then chips fall downwards and machining is simple, but the application is limited and cannot be used on horizontal spindles

Engineering Contradiction:
Improvechip removal simplicityVSAvoidmachine tool orientation adaptability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The invention transitions from relying solely on vertical gravity-based chip removal to a multi-dimensional chip removal system. By introducing flushing media delivery systems that can operate in various orientations, the process becomes adaptable to both vertical and horizontal spindle configurations, expanding machine tool orientation adaptability while maintaining effective chip removal.

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

3Manufacturing precision

If chips are flushed away during finishing, then surface quality is maintained, but the flushing media must be precisely directed to avoid interfering with subsequent roughening

Engineering Contradiction:
Improvesurface qualityVSAvoidflushing media delivery system
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention introduces flushing media as an intermediary substance to facilitate chip removal during the finishing operation. The flushing media delivers chips away from the finishing area without requiring complex mechanical chip evacuation systems, maintaining surface quality while avoiding interference with the subsequent roughening operation through proper timing and positioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This approach enables efficient, reliable, and cost-effective surface roughening, ensuring good adhesion of thermal coatings on cylindrical bores, particularly for non-ferrous metals, by preventing chip accumulation and improving surface quality.

Implementation Method 1

a flushing medium for rinsing and/or cooling is supplied to the area of the radial cutting head for roughening the inner surface with a directional component opposite to the feed direction

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP2879825B1Method and tool for roughening an inner surface of a cylindrical bore
Publication Date: 2023.09.13 MERCEDES BENZ GROUP AG
  • EP2879825B1 patent drawingFigure 1~2
  • EP2879825B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for roughening an inner surface (8) of a cylindrical bore (9), in particular a running surface in a cylindrical bore or cylinder liner of an internal combustion engine, wherein, by means of a rotating tool (1), which is moved in a translatory manner in the axial direction of the cylindrical bore (9) and has a radial cutting head (7), a chip (12) is lifted off by at least one cutting edge of the radial cutting head (7) and is broken away by means of a further edge or face of the radial cutting head (7), in order to produce the roughened surface. The invention is characterized in that the tool (1) is introduced into the cylindrical bore (9) or is passed through it, after which a positioning of the tool (1) in the radial direction takes place, and after which the removal of the material takes place by means of the rotating tool (1) when the tool is moved in its advancing direction (V) out of the cylindrical bore. A tool (1) is also claimed.