Medical Guide Wire Tensile Strength via Low-Temperature Heat Treatment
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Solution Overview
Problem
Existing medical guide wires do not effectively achieve the most preferable tensile strength characteristic during manufacturing, particularly when austenitic stainless steel wires are deeply drawn, leading to instability and potential disconnection during twisting procedures.
Innovation Solution
A method involving deep drawing of austenitic stainless steel wires with a whole cross-sectional reduction ratio of 90%-97.6%, followed by low-temperature heat treatments at 380°C-495°C to increase tensile strength, and using a gold-tin or silver-tin based alloy welding member to prevent disconnection and enhance straightness, while also applying a synthetic layer for additional strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If austenitic stainless steel wire is deeply drawn with high cross-sectional reduction ratio, then tensile strength is improved, but the wire becomes prone to disconnection during twisting procedure
Solution Approach 1:
The patent applies low-temperature heat treatment (200-400°C) to change the physical parameters of the stainless steel wire, specifically treating it after deep drawing to restore ductility while maintaining the strength gains from the drawing process. This parameter change resolves the contradiction by allowing the wire to achieve high tensile strength through deep drawing while preventing disconnection during twisting through subsequent heat treatment that restores material flexibility.
Solution Approach 2:
The patent performs heat treatment as a preliminary action before the twisting procedure to ensure the wire has appropriate mechanical properties for the subsequent twisting operation. By pre-treating the wire at low temperature after deep drawing, the patent prepares the material to withstand the twisting process without disconnection, thus resolving the reliability issue while maintaining the strength benefits.
2Strength
If austenitic stainless steel wire is subjected to multiple mechanical procedures, then tensile strength is increased, but thermal influence deteriorates the tensile strength characteristic
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature heat treatment to low-temperature heat treatment (200-400°C). This parameter change allows the wire to benefit from mechanical procedures that increase tensile strength while minimizing thermal influence that would otherwise deteriorate the tensile strength characteristic. The low temperature is sufficient to restore ductility and stabilize the wire structure without causing thermal degradation.
3Shape
If core wire is twisted to improve straightness, then linearity is improved, but disconnection occurs during twisting procedure
Solution Approach 1:
The patent performs low-temperature heat treatment as a preliminary action before twisting to ensure the core wire has the appropriate mechanical properties for the twisting operation. This pre-treatment prevents disconnection during twisting by restoring ductility, while still allowing the twisting procedure to achieve the desired straightness improvement.
Solution Approach 2:
The patent applies low-temperature heat treatment (200-400°C) to change the physical state of the core wire, making it more ductile and suitable for twisting. This parameter change enables the wire to be twisted effectively to improve straightness without risking disconnection, thus resolving the contradiction between shape improvement and quality stability.
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 method significantly increases the tensile rupture strength of the medical guide wire, maintaining product quality and preventing disconnection, making it suitable for minimally invasive surgeries by achieving high tensile strength and straightness.
Implementation Method 1
the core wire is heat treated at low temperature within a predetermined temperature range in order to improve a mechanical strength characteristic of the core wire
Implementation Method 2
such that the core wire is heat treated at low temperature of 380°C-495°C
Implementation Method 3
it is possible to increase the straightness or linearity of the core wire even when the core wire is drawn with the whole cross sectional reduction ratio as 90%-97.6%, while at the same time, preventing the disconnection of the core wire in the twisting procedure
Data Source
Figure 1~3
Figure 4~6
Figure 7
AI summary
In a medical guide wire (1), a flexible core wire (2) is made of austenitic stainless steel wire treated with a solid solution procedure, and drawn with a whole cross sectional reduction ratio as 90%-97.6%. Each time when the core wire (2) is subjected to a series of mechanical procedures, the core wire (2) is heat treated repetitively at low temperature subsequent to the mechanical procedures to improve a tensile strength characteristic of the core wire (2). The core wire (2) is twisted under the low heat treatment. Effectively used is a heat generated from a synthetic layer (6) when coating the layer (6) on the helical spring body (3). This makes it possible to increase the characteristic of the tensile strength of the core wire (2) with its thermal conductivity taken into consideration. Upon improving the tensile strength of the core wire (2), optimal conditions are achieved by considering a relationshp between the tensile strength and the temperature which the core wire (2) exhibits when tightly drawn as a wrought-out procedure.