Wire EDM Tension Control for Annealing Straightness
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Solution Overview
Problem
Existing wire electric discharge machining apparatuses face challenges in achieving stable straightness of wire electrodes regardless of diameter or material, due to inadequate tension control during annealing, which affects the success rate of automatic wire threading and machining efficiency.
Innovation Solution
The apparatus includes a tension device that applies a set tension value of 80 g or less during anneal current supply, and then lowers the tension by 10 g or more before returning to the original value, ensuring stable heating and re-crystallization of the wire electrode without adverse crystal structure effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a particular anneal current is supplied to heat the wire electrode, then the wire electrode is annealed and straightened, but the temperature increases rapidly causing elongation that makes adequate straightness difficult to achieve
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the tension applied to the wire electrode during the annealing process. Specifically, the tension is increased during the initial rapid heating phase to compensate for thermal elongation, then reduced after the current is stopped to prevent over-constraint during cooling. This dynamic parameter adjustment resolves the contradiction between achieving sufficient heating and maintaining straightness.
2Manufacturing precision
If a tension of around a few hundred g is applied during annealing, then the wire electrode maintains adequate straightness, but the wire electrode may break during heating due to excessive tension
Solution Approach 1:
The patent implements dynamics by making the tension applied to the wire electrode variable rather than constant. The tension device dynamically adjusts the tension based on the heating phase: applying higher tension (around a few hundred g) during the annealing process to maintain straightness, then reducing the tension after the current is stopped to prevent wire breakage. This dynamic adjustment resolves the contradiction between maintaining straightness and preventing breakage.
3Temperature
If the tension is reduced after annealing current is stopped, then the wire electrode can cool without excessive constraint, but the wire electrode may become slack and lose straightness
Solution Approach 1:
The patent applies preliminary action by maintaining adequate tension during the critical cooling phase immediately after the anneal current is stopped. This preliminary tension maintenance prevents the wire from becoming slack and losing straightness as it cools and contracts. The tension is held at an appropriate level until the cooling process is complete, ensuring straightness is preserved throughout the temperature change.
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 enhances the stability of wire electrode straightness, increases the success rate of automatic wire threading, and reduces operator burden by eliminating the need for resetting anneal conditions and using a control device for the anneal current and current detector.
Implementation Method 1
supplies a current adapted for annealing the wire electrode ('anneal current') to heat the wire electrode
Implementation Method 2
the wire electrode is annealed when a particular amount of time has passed after the anneal current is supplied to the wire electrode
Implementation Method 3
the tension will become smaller relative to the expanding elongation rate of the wire electrode caused by the rapid increase in temperature
Data Source
AI summary
A control device 8 controls a tension device 10 to apply a tension to a wire electrode WE such that a set tension value is as small as possible within a range of 80 g or less during a particular anneal period when a particular anneal current is supplied from a current supply device 5.