Coil Spring Jig Structure for Stable Stress Shot Peening

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Solution Overview

Problem

Coil springs with long free lengths relative to their center diameter tend to radially twist or bend during stress shot peening, making it difficult to apply residual stress effectively to their inner peripheral surfaces, which is crucial for enhancing fatigue strength, especially in suspension devices for vehicles.

Innovation Solution

A coil spring jig is designed with a spring support portion, displacement regulating portions, and a rotatable lid portion that abuts the outer peripheral surface of the coil spring, maintaining it in a compressed state and preventing radial displacement, allowing for even shot peening on both inner and outer surfaces while preventing body bending.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If stress shot peening is performed on a coil spring with long free length and small outer diameter, then residual stress can be applied to enhance fatigue strength, but the coil spring body bends due to radial twisting

Engineering Contradiction:

Improvefatigue strengthVSAvoidbody bending

Core Design Contradiction:

StrengthVSStability of the object's composition

Solution Approach 1:

The patent introduces displacement regulating portions as intermediary components between the shot peening device and the coil spring. These portions include guide members that extend along the axial direction and regulate radial displacement of the coil spring during stress shot peening, preventing body bending while allowing effective residual stress application

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements preliminary positioning and constraint of the coil spring before shot peening begins. The guide members and displacement regulating portions are pre-installed to establish proper alignment and restrict radial movement, ensuring the coil spring maintains its positional stability throughout the shot peening process

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If the coil spring is kept in a compressed state for shot peening, then residual stress can be applied to the inner peripheral surface, but radial displacement occurs causing body bending

Engineering Contradiction:

Improveresidual stress applicationVSAvoidradial displacement

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent divides the displacement regulation function into multiple independent guide members arranged circumferentially around the coil spring. Each guide member independently regulates radial displacement at different angular positions, providing comprehensive constraint while maintaining ease of operation and setup

Inventive Principle:

Principle #1Segmentation

3Reliability

If displacement regulating portions are added to prevent body bending, then shot peening effectiveness is maintained, but device complexity increases

Engineering Contradiction:

Improveshot peening effectivenessVSAvoidjig structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The guide members serve multiple functions simultaneously: they guide the shot peening process, regulate radial displacement, prevent body bending, and maintain coil spring positioning. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while ensuring shot peening effectiveness

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 jig effectively applies compressive residual stress to the inner and outer surfaces of the coil spring, enhancing its fatigue strength and preventing body bending, thus improving the reliability and durability of the coil spring.

Implementation Method 1

a plurality of displacement regulating portions extending along an axis of the coil spring from the spring support portion with the coil spring supported by the spring support portion as a reference, capable of abutting against an outer peripheral surface of the coil spring, and regulating displacement of the coil spring in a radial direction of the coil spring

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

a lid portion supported by the displacement regulating portions and capable of keeping the coil spring in a compressed state by sandwiching the coil spring together with the spring support portion

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

Stress shot peening, in which shot peening is performed on a coil spring which is kept in a compressed state, is known. Residual stress can be applied to the coil spring by performing the stress shot peening

Methodology Applied

Scientific EffectShot Peening: Shot Peening

Data Source

PatentUS12173767B2Coil spring jig, coil spring manufacturing method, and coil spring testing method

Publication Date: 2024.12.24 ASTEMO LTD

AI summary

A coil spring jig includes a spring support portion where one end of a coil spring is capable of being placed, a plurality of displacement regulating portions extending along an axis of the coil spring from the spring support portion with the coil spring supported by the spring support portion as a reference, capable of abutting against an outer peripheral surface of the coil spring, and regulating displacement of the coil spring in a radial direction of the coil spring, and a lid portion supported by the displacement regulating portions and capable of keeping the coil spring in a compressed state by sandwiching the coil spring together with the spring support portion.