Rotating Elastic Grindstone Superfinishing Eliminates Crossing-Angle Patterns

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Solution Overview

Problem

Conventional superfinishing techniques struggle to produce smooth surfaces on machine components like rolling elements and bearing rings without leaving machined markings, such as crossing-angle patterns, and are inefficient in handling complex shapes, leading to reduced machining efficiency and increased setup complexity.

Innovation Solution

The use of a rotating elastic grindstone with a sectional shape corresponding to the workpiece's shape, allowing it to follow the surface contours and eliminate crossing-angle patterns, while maintaining the precise shape of complex features like crowning or logarithmic shapes, thereby improving surface roughness and reducing initial setup steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a non-rotatable grindstone is used for superfinishing, then the surface roughness can be improved, but crossing-angle patterns are formed on the work surface

Engineering Contradiction:
Improvesurface roughnessVSAvoidcrossing-angle patterns
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The grindstone is made rotatable in addition to its traditional oscillating motion, creating a dynamic two-degree-of-freedom motion system. This rotational movement continuously changes the contact point between the grindstone and workpiece, preventing the formation of fixed crossing-angle patterns while maintaining the surface finishing quality.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The grindstone performs periodic oscillating motion combined with rotational motion. The oscillating motion provides the primary finishing action while the superimposed rotational motion periodically varies the contact geometry, eliminating repetitive crossing-angle patterns and producing a more uniform surface.

Inventive Principle:
Principle #19Periodic action

2Device complexity

If a fixed-angle grindstone movement is used, then the machining process is simple, but complex shapes like crowning or logarithmic shapes cannot be followed

Engineering Contradiction:
Improvemachining process simplicityVSAvoidcomplex shape following capability
Core Design Contradiction:
Device complexityVSShape

Solution Approach 1:

The addition of rotational motion to the grindstone creates a dynamic system that can adapt to complex workpiece geometries. The rotation allows the grindstone to follow crowning, logarithmic, and other complex shapes while maintaining a relatively simple oscillating feed mechanism.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The grindstone's motion parameters are changed by superimposing rotational motion on the oscillating motion. This parameter change enables the grindstone to conform to complex surface geometries without fundamentally changing the machining process structure.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the turning radius of the workpiece changes for each model, then the machining can be adapted to different specifications, but the initial set-up steps and components increase

Engineering Contradiction:
Improvemodel adaptation capabilityVSAvoidinitial set-up time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The rotatable grindstone system serves multiple functions: it can machine various workpiece types (cylindrical, spherical, tapered) and follow different geometries (crowning, logarithmic shapes) using the same basic mechanism. This universality reduces the need for model-specific setup components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system adapts to different workpiece specifications by changing operational parameters (rotation speed, oscillation amplitude, feed rate) rather than requiring physical reconfiguration of the machining setup, thereby reducing initial set-up time.

Inventive Principle:
Principle #35Parameter changes

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 method achieves smooth surfaces free from machined markings, enhances surface roughness, extends the lifespan of machine components, and simplifies the machining process by reducing the number of initial setup steps and allowing the use of general machine tools, thereby improving production efficiency and quality.

Implementation Method 1

The machining surface of the elastic grindstone, the sectional shape of which corresponds to the sectional shape of the to-be-machined surface, is moved to follow the to-be-machined surface of the work, thereby superfinishing the to-be-machined surface of the work

Methodology Applied
Scientific EffectAbrasion: Abrasion

Implementation Method 2

a machining surface of a rotating elastic grindstone, the sectional shape of which corresponds to the sectional shape of the to-be-machined surface

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2378147B1Machine component and super-finishing method therefor
Publication Date: 2018.09.19 NTN CORP
  • EP2378147B1 patent drawingFigure 1
  • EP2378147B1 patent drawingFigure 2
  • EP2378147B1 patent drawingFigure 3

AI summary

A surface shape of a machining surface (4b) of a rotating elastic grindstone (4) is rendered to be a shape appropriate to a to-be-machined surface (8a) of a work (8). With the work (8) being rotated, the rotating elastic grindstone (4) is held in engagement to an end of the to-be-machined surface (8a) of the work (8). The elastic grindstone (4) is moved along a machining trajectory effective to allow the machining surface (4b) of the elastic grindstone (4), which is so formed as to suit to the to-be-machined surface (8a), to follow the to-be-machined surface (8a) of the work (8). The to-be-machined surface (8a) of the work (8) so superfinished represents a smooth surface free from any machining trace such as a crossing-angle pattern.