Vibrating Shot Peening for Internal Coil Spring Stressing
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Solution Overview
Problem
Conventional shot-peening devices face limitations in applying compressive residual stress to the inside of compression coil springs due to restrictions on the mass and velocity of shots, leading to reduced kinetic energy and potential surface roughness, which compromises the fatigue strength of the springs.
Innovation Solution
A shot-peening device with a hollow housing and vibration means that vibrates the housing and workpiece, allowing larger shots to be used at increased velocity, ensuring compressive residual stress is applied effectively to the inside of the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional shot-peening device is used to apply compressive residual stress to the inside of compression coil springs, then the structure is simple and easy to operate, but the kinetic energy of shots is insufficient and surface roughness occurs
Solution Approach 1:
The patent applies mechanical vibration by mounting the workpiece and shots on a vibrating table that oscillates in the vertical direction. This vibration enables shots to achieve higher velocity and kinetic energy while preventing surface roughness, directly resolving the contradiction between insufficient kinetic energy and device complexity.
Solution Approach 2:
The patent introduces dynamic vibration to the otherwise static shot-peening process. The vibrating table transforms the static arrangement of shots and workpiece into a dynamic system where shots are continuously moved and accelerated, enhancing kinetic energy without requiring complex mechanical structures.
2Strength
If larger shots are used to increase kinetic energy, then the fatigue strength improves, but the device complexity increases
Solution Approach 1:
The patent places larger shots inside the hollow housing that contains the workpiece. This nesting arrangement allows larger shots to be used for increasing kinetic energy and fatigue strength while the housing structure provides containment without adding significant complexity.
3Strength
If shots are projected at high velocity to apply compressive residual stress to the inside of workpiece, then the fatigue strength improves, but surface roughness occurs
Solution Approach 1:
The vibrating table oscillates the workpiece and shots vertically, enabling high-velocity shot projection to improve fatigue strength while the vibration-induced randomization of shot trajectories prevents concentrated impact that would cause surface roughness.
Solution Approach 2:
The periodic vibration of the table creates repeated cycles of shot acceleration and impact, distributing the stress application over time and preventing localized surface damage while maintaining overall fatigue strength improvement.
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 device improves the fatigue strength of the workpiece by overcoming mass and velocity limitations, enabling optimal stress peening without surface roughness issues, and can be used to enhance both internal and external stress application.
Implementation Method 1
a vibration means (3) that vibrates the housing (2), wherein a workpiece (W) and shots (SH) are stored within the housing (2), and the vibration means (3) vibrates the housing (2) with the workpiece (W) and the shots (SH) stored therein
Implementation Method 2
the kinetic energy of the shots SH needs to be improved when attempting to apply compressive residual stress to the inside of the compression coil springs
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
Provided is a shot-peening device capable of improving the fatigue strength of a workpiece by applying compressive residual stress to the inside of the workpiece. The shot-peening device comprises: a hollow housing 2; and a vibration means 3 for vibrating the housing 2. The housing 2 stores a workpiece W and shot SH therein. Due to this configuration, the vibration means 3 vibrates the housing 2 with the workpiece W and the shot SH stored therein. Accordingly, the fatigue strength of the workpiece W is improved by applying compressive residual stress to the inside of the workpiece W.