Seamless Medical Hollow Needle for Low-Resistance Blood Flow
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Solution Overview
Problem
Conventional medical hollow needles face issues with surface roughness on the inner circumferential surface due to joint portions or wrinkles, leading to resistance in liquid flow, especially when used for blood or fluid transfer, and existing manufacturing methods fail to ensure smooth flow.
Innovation Solution
A medical hollow needle with a tapered inner circumferential surface formed by deep drawing, having an arithmetic mean roughness of Ra≤1.0 μm, and a structure without circumferential joints, ensuring a smooth and stable liquid flow by reducing surface irregularities and pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the hollow needle is manufactured by rounding a sheet of medical metal into a cylindrical shape and performing multi-step extraction, then the manufacturing process is established, but the inner circumferential surface becomes wrinkled and rough when the diameter is small, hindering smooth liquid flow
Solution Approach 1:
The patent changes the manufacturing method from multi-step extraction to deep drawing process, which fundamentally alters the forming parameters and mechanism. This parameter change enables the inner circumferential surface to be formed smoothly without wrinkles, achieving Ra≤1.0 μm while maintaining manufacturing feasibility
Solution Approach 2:
The patent replaces the traditional extraction mechanism with a deep drawing mechanism. Instead of removing material through extraction, the needle tube is formed by deep drawing a blank, which substitutes the mechanical action and eliminates the wrinkle formation issue on the inner surface
2Device complexity
If the sheet is rounded into cylindrical shape with edges joined, then the hollow needle structure is formed, but the joint portion creates surface roughness and resistance to liquid flow
Solution Approach 1:
The patent extracts or eliminates the joint portion from the needle structure by using a deep drawing process that forms a seamless needle tube from a blank. This removes the source of surface roughness and liquid flow resistance at the joint area
Solution Approach 2:
The deep drawing process creates a homogeneous inner circumferential surface throughout the entire needle tube, eliminating the non-uniformity caused by joint portions. The surface roughness is uniformly controlled at Ra≤1.0 μm across all areas, ensuring consistent liquid flow characteristics
3Reliability
If the inner circumferential surface is welded to ensure liquid tightness at the joint portion, then liquid tightness is improved, but the inner circumferential surface becomes difficult to keep smooth
Solution Approach 1:
The patent eliminates the need for welding by removing the joint portion through the deep drawing process. The needle tube is formed as a seamless structure from a blank, so no welding is required to achieve liquid tightness, and the inner surface remains smooth throughout
Solution Approach 2:
The patent avoids segmenting the needle tube by joining separate pieces. Instead, the entire needle tube is formed as a single integrated piece through deep drawing, eliminating the joint portion that would require welding and compromise surface smoothness
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 achieves efficient liquid flow with reduced turbulence and damage to blood cells, minimizing pain during puncture and enhancing the stability of fluid flow rates.
Implementation Method 1
an inner circumferential surface of the needle tube has a tapered surface with a diameter becoming smaller toward a needle tip formed by deep drawing
Data Source
AI summary
Provided is a medical hollow needle with a novel structure that allows the efficient passage of blood or other liquids. A medical hollow needle has an inner lumen penetrating it in a direction of a needle axis. An inner circumferential surface of a needle tube constituting a circumferential wall of the inner lumen has a tapered surface with a diameter becoming smaller toward a needle tip formed by deep drawing. An arithmetic mean roughness Ra of the inner circumferential surface in the direction of the needle axis is set as Ra≤1.0 μm.