Rounded Ophthalmic Knife Tip for Bend-Resistant Sharpness
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Solution Overview
Problem
Austenitic stainless steel medical knives used in ophthalmic surgery are prone to bending during use, leading to deformation and loss of sharpness, as they cannot be quenched to achieve the necessary hardness and sharpness like martensitic stainless steel.
Innovation Solution
The medical knife is manufactured using austenitic stainless steel with a fibrous structure, where the blade tip is rounded through electrolytic or chemical polishing to increase strength and prevent bending, while maintaining sharpness by removing burrs and forming a convex curved surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If austenitic stainless steel is used for the medical knife, then corrosion resistance is improved, but hardness and sharpness deteriorate because the material cannot be quenched
Solution Approach 1:
The invention changes the crystalline structure parameters of austenitic stainless steel through cold working (stretching) to create a fibrous structure, transforming the material properties to achieve both corrosion resistance and improved hardness without quenching
Solution Approach 2:
The invention creates a composite crystalline structure within the austenitic stainless steel by inducing a fibrous structure through cold working, combining the corrosion resistance of austenitic steel with enhanced hardness characteristics
2Strength
If austenitic stainless steel wire is stretched and work hardened to attain predetermined hardness, then hardness is improved, but the crystalline structure becomes fibrous which may affect sharpness
Solution Approach 1:
The invention applies different surface treatments to different regions of the blade, with electrolytic or chemical polishing applied specifically to the cutting edge area to remove fibrous structure effects and create a sharp, smooth cutting surface while maintaining the fibrous structure in the body for hardness
3Manufacturing precision
If the blade tip is made thin and sharp for effective cutting, then cutting performance is improved, but the blade tip becomes prone to bending during use
Solution Approach 1:
The invention optimizes the geometric parameters of the blade tip by forming a convex curved surface with specific radius of curvature, creating a shape that maintains sharpness while increasing structural rigidity to prevent bending during surgical use
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 rounded blade tip is resistant to bending and maintains sharpness, ensuring easy usability and effective cutting without compromising the knife's ability to penetrate tissues during ophthalmic procedures.
Implementation Method 1
the blade tip is rounded through electrolytic or chemical polishing to increase strength and prevent bending
Implementation Method 2
the blade tip is rounded through electrolytic or chemical polishing to increase strength and prevent bending
Data Source
Figure 1(a)~1(h)
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
There is a problem with a medical knife such as a straight knife made of austenitic stainless steel due to a thin and pointed blade tip portion that when forming an incision in a cornea, a sclera, or the like during ophthalmic surgery, blade tip portion is easily bent. The present invention provides a medical knife capable of improving strength of the thin pointed blade tip portion, and preventing decrease in sharpness. The medical knife of the present invention includes a planar cutting portion and a slanted surface formed along the periphery of at least a part of the cutting portion. The slanted surface is electrolytically polished or chemically polished so as to form a cutting blade constituted by a convex rounded surface on at least an edge of the slanted surface of the knife, and a blade tip is rounded. Since the blade tip is rounded, the blade tip is thick, thereby increasing strength and making it difficult to bend.