Imparting Compressive Stress to Balls via Controlled Pressing

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Solution Overview

Problem

Current methods for imparting compressive stress to spherical balls, such as tumbling and peening, are noisy and difficult to control, leading to uneven stress distribution and potential damage to the surface finish, making it challenging to achieve uniform compressive residual stress without reworking.

Innovation Solution

A method involving placing balls between two bodies with a smooth contact surface, where one body is rotatable, applying a compressive force, and causing relative movement to distribute stress uniformly across the balls' surfaces, allowing for controlled stress profile creation independent of ball mass and reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If tumbling operation is used to impart compressive stress to balls, then compressive stress can be distributed across the ball surface, but the operation produces excessive noise and is difficult to perform uniformly

Engineering Contradiction:

Improvecompressive stress distributionVSAvoidnoise

Core Design Contradiction:

Stress or pressureVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional tumbling mechanical system with a controlled pressing system using opposing bodies. Instead of relying on chaotic tumbling motion to distribute stress, the invention uses controlled compression between two opposing surfaces, one of which moves in a predetermined pattern to ensure uniform stress distribution. This substitution eliminates the noisy impact forces of tumbling while maintaining effective stress imparting.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If peening operation is used to impart compressive stress to balls, then surface hardening can be achieved, but the operation is very noisy and provides limited control over stress profile

Engineering Contradiction:

Improvesurface hardnessVSAvoidcontrol over stress profile

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent introduces dynamic movement of one opposing body during the compression process. The body moves in a predetermined pattern that ensures different portions of the ball surface are subjected to compressive forces, creating a controlled stress profile. This dynamic approach provides precise control over the stress distribution and hardening pattern, eliminating the limitations of static peening operations.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention replaces the uncontrolled impact mechanism of peening with a controlled compression system. Instead of relying on random ball-to-surface or ball-to-ball impacts, the system uses controlled pressing between opposing bodies with predetermined movement patterns, enabling precise control over the stress profile and surface hardening characteristics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stress or pressure

If tumbling operation is used to impart compressive stress to balls, then stress can be distributed across the ball surface, but uniform distribution of stress is difficult to achieve

Engineering Contradiction:

Improvecompressive stress distributionVSAvoiduniformity of stress distribution

Core Design Contradiction:

Stress or pressureVSManufacturing precision

Solution Approach 1:

The patent replaces the chaotic tumbling mechanism with a controlled compression system between opposing bodies. The predetermined movement pattern of one body ensures that compression forces are systematically applied across different portions of the ball surface, guaranteeing uniform stress distribution. This controlled approach eliminates the randomness and non-uniformity inherent in tumbling operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 provides a quieter, more controlled method for achieving uniform compressive residual stress on spherical balls, avoiding the noise and unevenness issues of existing methods while maintaining surface integrity.

Implementation Method 1

imparting a compressive stress along a first diameter of the first plurality of balls by pressing the first body toward the second body or the second body toward the first body or the first and second bodies toward one another with a force

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

imparting compressive residual stress to at least a surface portion of a first plurality of balls

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS10480578B2Method of imparting compressive residual stress to balls

Publication Date: 2019.11.19 AB SKF SKF PATENT DEPARTMENT

AI summary

A method of imparting compressive residual stress to a first plurality of balls includes a) placing the balls between a first body having a first surface and a second body having a second surface, the first surface including a smooth contact portion, the smooth contact portion being substantially flat or convex and having a surface hardness greater than or equal to an initial surface hardness of the balls, b) imparting a compressive stress along a first diameter of the balls by pressing the first body toward the second body or the second body toward the first body or the first and second bodies toward one another with a force, and c) causing relative movement between the first surface and the second surface while maintaining the force at or above a minimum level to impart the compressive stress along other diameters of the balls different than the first diameter.