Elongated Dimpled Workpiece Surface for Stable Oil Film Pressure

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Solution Overview

Problem

The generation of vortex-like turbulence in dimples on workpieces leads to a reduction in oil film pressure when oil is filled between the workpiece and a counterpart material, causing inefficiencies in frictional resistance reduction.

Innovation Solution

The formation of elongated dimples with an aspect ratio of 5.0 or more and 50.0 or less, arranged in a spindle shape, and intersecting longitudinal directions to minimize turbulence and enhance oil film pressure by reducing oil flow disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If circular dimples are formed on the workpiece surface, then the dimples can effectively capture wear debris and generate squeeze effect, but vortex-like turbulence occurs in the oil flow within the dimples, reducing oil film pressure

Engineering Contradiction:
Improvefrictional resistance reductionVSAvoidoil film pressure
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The patent applies asymmetry by changing the dimple shape from circular to elliptical, where the aspect ratio (major axis to minor axis) is controlled within 2.0 to 10.0. This asymmetric geometry suppresses vortex-like turbulence in the oil flow while maintaining the dimple's ability to capture wear debris and generate squeeze effect, thereby resolving the contradiction between frictional resistance reduction and oil film pressure maintenance

Inventive Principle:
Principle #4Asymmetry

2Stress or pressure

If the aspect ratio of dimples is increased to suppress turbulence, then oil film pressure is maintained, but the dimple geometry becomes more complex to manufacture

Engineering Contradiction:
Improveoil film pressureVSAvoiddimple formation complexity
Core Design Contradiction:
Stress or pressureVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by optimizing the aspect ratio of elliptical dimples within a specific range (2.0 to 10.0). This controlled parameter adjustment achieves turbulence suppression and adequate oil film pressure while maintaining manufacturability, as the elliptical shape can be formed using conventional scraping tools with appropriate geometric configuration

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If scraping is used to form dimples on the workpiece surface, then the process is simple and cost-effective, but controlling the precise geometry and aspect ratio of dimples is difficult

Engineering Contradiction:
Improvedimple formation processVSAvoiddimple geometry control
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies self-service by designing the scraping tool geometry such that the tool's own configuration (scraping element angle, depth, and arrangement) automatically produces the desired elliptical dimple geometry with controlled aspect ratio during the scraping process. The tool structure itself ensures consistent dimple formation without requiring complex external control systems, achieving both ease of manufacture and adequate geometric precision

Inventive Principle:
Principle #25Self-service

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 solution effectively suppresses vortex-like turbulence, maintaining higher oil film pressure and reducing frictional resistance by ensuring less turbulent oil flow along the dimples' longitudinal direction, thereby improving the frictional coefficient stability across varying loads.

Implementation Method 1

The oil flow causes vortex-like turbulence (for example, cavitation) in the dimples, for example, when the dimples are circular

Methodology Applied
Scientific EffectVortex-like turbulence: Turbulence

Implementation Method 2

The oil flow causes vortex-like turbulence (for example, cavitation) in the dimples

Methodology Applied
Scientific EffectCavitation: Cavitation

Implementation Method 3

When the counterpart material passes near the dimples, the oil may be squeezed out from the dimples and into the space between the counterpart material and the workpiece (squeeze effect) at high pressure

Methodology Applied
Scientific EffectSqueeze effect:

Implementation Method 4

a cutting edge of a rotary cutting tool may be slightly abutted to the surface of the workpiece while the rotary cutting tool rotates

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP3783239B1Dimpled workpiece and dimpling process
Publication Date: 2023.06.28 KANEFUSA HAMONO KOUGIYOU KK
  • EP3783239B1 patent drawingFigure 1~2
  • EP3783239B1 patent drawingFigure 3~4
  • EP3783239B1 patent drawingFigure 5~6

AI summary

A plurality of dimples (3) are formed on a processing surface (2) of a workpiece. An aspect ratio of the dimples (3) is 5.0 or more and 50.0 or less, the aspect ratio being a ratio of a vertical length (3b) of the dimple in a longitudinal direction to a lateral length (3c) of the dimple in a lateral direction orthogonal to the longitudinal direction.