Eyeless Sewing Needle Localized Heat Treatment for Crimping
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Solution Overview
Problem
Existing eyeless sewing needles made of austenitic stainless steel face issues with bending when gripped near the hole due to a granular crystalline structure extending towards the needlepoint, making them difficult to handle and increasing the risk of bending during surgical procedures.
Innovation Solution
A sewing needle with a curved axial body made of austenitic stainless steel featuring a fibrous structure along its length, where the periphery of the axial hole is heated to create a granular structure without directionality, and a heat-affected zone is formed between the fibrous and granular structures, limiting the granular structure's length to prevent bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the entire needle is made with a fibrous crystalline structure to maintain hardness, then the needle becomes too hard for crimping operations, but if the entire needle is made with a granular structure to enable crimping, then the needle becomes too flexible and may bend during use
Solution Approach 1:
The needle is designed with different crystalline structures in different regions: the base end portion (within 3 times the needle diameter from the hole base) has a granular structure for flexibility and ease of crimping, while the remaining portions maintain a fibrous structure for hardness and strength. This local differentiation resolves the contradiction by providing each region with the specific structure it needs for its function.
2Ease of operation
If the granular structure extends towards the needlepoint to provide flexibility for crimping, then the needle becomes flexible in the gripping area, but this causes the needle to bend when gripped near the hole during suturing
Solution Approach 1:
The granular structure is localized to only the base end portion within 3 times the needle diameter from the hole base, while the rest of the needle maintains the fibrous structure. This ensures flexibility and ease of crimping only where needed at the base, while maintaining needle stability and preventing bending in the gripping area and along the needle length.
Solution Approach 2:
The heating process is applied preliminarily to create the granular structure in the base end portion before the crimping operation. This preliminary structural modification enables easy crimping without compromising the needle's overall stability during subsequent handling and suturing operations.
3Reliability
If austenitic stainless steel is used to improve corrosion resistance and eliminate quenching, then cracking and chipping are prevented, but the material requires work hardening which makes the entire needle too hard for crimping
Solution Approach 1:
The needle maintains austenitic stainless steel throughout for uniform corrosion resistance, but applies localized heating to create a granular structure in the base end portion. This localized structural modification provides the necessary flexibility for crimping operations while preserving the superior corrosion resistance of the austenitic material throughout the entire needle.
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 needle remains flexible near the hole for easy crimping while maintaining hardness towards the needlepoint, preventing bending when gripped near the hole and ensuring secure suturing.
Implementation Method 1
a periphery of the axial hole at the base end is heated to make the fibrous structure be a granular structure without directionality
Implementation Method 2
at least a part of a heat-affected zone made between the fibrous structure and the granular structure through the heating
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
In an eyeless sewing needle (10), a periphery of an axial hole at the base end (lla) is heated to make a fibrous structure be a granular structure without directionality, and at least a part of a heat-affected zone made between the fibrous structure and the granular structure due to the heating is within a range that is three times the diameter of the sewing needle and that extends from an effective base (12c) of the axial hole (12) towards the needlepoint (14). This allows provision of a flexible sewing needle so that the hole periphery can be processed while keeping a hard state at the position of the needlepoint slightly away from the axial hole.