Medical Guide Wire Head Plug Welding Strength
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Solution Overview
Problem
Existing medical guidewires lack effective methods to enhance mechanical strength and minimize the size of the head plug at the welded portion between the core wire and the helical spring body without compromising mechanical properties, making it difficult to navigate through sinuous or meandering blood vessel paths.
Innovation Solution
A method using a highly drawn austenitic stainless steel core wire and a eutectic alloy welding member with a melting temperature of 180°C-495°C to form a weld-hardened portion, which is then partially heat-treated to increase tensile rupture strength and reduce the head plug length and diameter, while maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the core wire is welded to the helical spring body using conventional methods, then the head plug is formed, but the mechanical strength properties of the welded portion are insufficient and the head plug size is large
Solution Approach 1:
The patent applies parameter changes by controlling the heating temperature during welding to be within a specific range (Ac3 transformation point to Ac3+50°C) and using a eutectic alloy with melting point 180-525°C. These parameter optimizations enable strong welding while minimizing heat-affected zone, thus improving mechanical strength while reducing head plug size
Solution Approach 2:
The patent uses composite materials by combining austenitic stainless steel core wire with specific eutectic alloy welding materials. The eutectic alloy composition (containing Sn, In, Zn, and other elements) creates a metallurgically strong bond that improves welded portion strength while allowing smaller head plug dimensions
2Strength
If the core wire is highly drawn to increase tensile rupture strength, then mechanical strength is improved, but the wire becomes more susceptible to thermal influence during welding
Solution Approach 1:
The patent controls the heating temperature parameter to be within Ac3 to Ac3+50°C range during welding. This precise temperature control allows the highly drawn core wire to gain strength from controlled thermal influence without excessive heat damage, optimizing both tensile rupture strength and thermal resistance
Solution Approach 2:
The patent converts the harmful thermal influence into a benefit by intentionally applying controlled heating within the Ac3 transformation point range. This controlled thermal treatment actually strengthens the highly drawn core wire through controlled phase transformation, turning potential damage into strength enhancement
3Ease of operation
If the head plug is reduced in size to navigate sinuous blood vessel paths, then maneuverability is improved, but welding strength may be compromised
Solution Approach 1:
The patent optimizes welding parameters including heating temperature (Ac3 to Ac3+50°C), heating time (1-60 seconds), and eutectic alloy composition. These parameter optimizations create strong welding joints even in miniaturized head plugs, enabling both small size for maneuverability and sufficient welding strength
Solution Approach 2:
The use of eutectic alloy composite materials enables strong welding in reduced-size head plugs. The specific alloy composition creates robust metallurgical bonds that maintain welding strength even when head plug dimensions are minimized for navigating complex vascular paths
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 and welding strength of the core wire, allowing for a reduced and more maneuverable head plug that can be safely inserted into complex vascular paths, enhancing therapeutic treatment capabilities.
Implementation Method 1
a eutectic alloy welding member with a melting temperature of 180°C-495°C to form a weld-hardened portion
Implementation Method 2
welding the core wire to the helical spring body by means of a welding member
Implementation Method 3
a highly drawn austenitic stainless steel core wire
Implementation Method 4
partially heat-treated to increase tensile rupture strength
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
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 tightly drawn with a whole cross sectional reduction ratio as 90%-99%. Upon forming a head plug (41) at a distal end by welding a distal end tip of the core wire (2) to a distal end tip of a helical spring body (3), a eutectic alloy is used as a welding member (4). The eutectic alloy has a predetermined melting temperature point so as to reduce a thermal influence against the core wire (2), thereby improving a mechanical strength property of the core wire (2) so as to lengthwisely reduce and diametrically minimize the head plug (41).