Spring Steel Wire Oxide Film for Low-Decarburization Coiling
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Solution Overview
Problem
During the manufacture of steel wires for springs, heat treatment causes decarburization, leading to reduced quality and workability due to lubricant residue, which can cause clogging and inaccurate measurements.
Innovation Solution
A steel wire for springs with Ca or Na adhered in an amount of 0.2 g/m2 or less, along with a surface roughness of 10 μm or less and an oxide film thickness of 1.0 μm to 20 μm, to reduce decarburization and improve coilability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lubricant is applied during steel wire manufacturing, then workability and formability are improved, but decarburization occurs and quality is reduced
Solution Approach 1:
The invention changes the chemical composition parameters of the lubricant by strictly limiting Ca to 0.003 wt% or less and Na to 0.003 wt% or less, while maintaining lubrication functionality through alternative lubricant compositions that do not cause decarburization
Solution Approach 2:
The invention converts the harmful effect of lubricant residue into a beneficial outcome by selecting specific lubricant compositions that provide necessary lubrication during manufacturing while preventing decarburization, thus eliminating the trade-off between workability and quality
2Strength
If heat treatment is performed on steel wire, then spring characteristics are improved, but decarburization occurs leading to reduced fatigue resistance
Solution Approach 1:
The invention performs preliminary action by controlling the lubricant composition before heat treatment to prevent decarburization during the subsequent heat treatment process, thereby preserving fatigue resistance while achieving desired spring characteristics
Solution Approach 2:
The invention changes the chemical environment parameters during heat treatment by using lubricants with controlled Ca and Na content, which prevents decarburization while allowing the heat treatment to improve spring characteristics
3Ease of operation
If lubricant residue remains on steel wire surface, then friction is reduced during coiling, but clogging occurs and measurements become inaccurate
Solution Approach 1:
The invention changes the physical and chemical parameters of the lubricant by limiting Ca and Na content, which reduces lubricant residue deposition while maintaining sufficient lubrication for smooth coiling and accurate sensor measurements
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 reduces decarburization, improves spring characteristics such as fatigue resistance and settling resistance, and enhances workability and formability during coiling by minimizing lubricant residue and frictional resistance.
Implementation Method 1
the steel wire has an oxide film on a surface of the steel wire
Implementation Method 2
heat treatment causes decarburization, leading to reduced quality and workability due to lubricant residue
Data Source
AI summary
A steel wire for a spring includes a steel wire that has Ca or Na adhered thereto in an amount of 0.2 g/m2 or less. The steel wire has an oxide film on a surface thereof, and the oxide film has a thickness of, for example, from 2.0 μm to 20 μm.