Conical Hollow Needle Electropolishing for Circular Tapered Surfaces
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Solution Overview
Problem
Conventional electrochemical polishing of conical hollow needles often results in a distorted outer circumferential surface, leading to increased patient pain and reduced strength characteristics due to uneven electrolysis efficiency.
Innovation Solution
A method involving the use of a pair or multiple cathodes arranged at different positions around the hollow needle during electropolishing, with controlled energization and movement to ensure uniform electrolysis, resulting in a conical part with an outer circumferential surface shape closer to a perfect circle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional electropolishing with one electrode plate is used, then the manufacturing process is simple, but the outer circumferential surface becomes distorted and deviates from a perfect circle
Solution Approach 1:
The single electrode plate is divided into multiple electrode plates (at least three) arranged around the hollow needle. Each electrode plate processes a specific angular region, and their combined action ensures uniform material removal around the entire circumference, maintaining circularity while achieving the conical shape.
Solution Approach 2:
The electrode arrangement transitions from a single-plane configuration to a three-dimensional circumferential arrangement. By positioning electrode plates at different angular positions around the needle axis, the system achieves uniform electrolysis in all radial directions, preventing surface distortion.
2Device complexity
If the hollow needle is not rotated during electropolishing, then the process is simpler to control, but electrolysis efficiency varies and surface distortion occurs
Solution Approach 1:
The hollow needle is rotated during electropolishing to dynamically change its orientation relative to the fixed electrode plates. This rotation ensures that all regions of the needle surface receive equivalent electrolytic treatment over time, achieving uniform material removal and circular cross-sections without requiring complex moving electrodes.
3Manufacturing precision
If multiple cathodes are arranged around the hollow needle, then the outer circumferential surface circularity is improved, but the device complexity increases
Solution Approach 1:
The multiple electrode plates serve dual functions: they collectively create the conical tapered shape through controlled material removal, and simultaneously maintain the circular cross-sectional geometry by distributing electrolysis uniformly around the circumference. This multi-functionality justifies the increased device complexity.
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
This approach effectively reduces pain during puncture and enhances the strength characteristics of the conical hollow needle by achieving a consistent, circular cross-sectional shape.
Implementation Method 1
immersing a hollow needle having a straight shape in an electrolytic solution and performing electropolishing to make an outer circumferential surface of the hollow needle into a conical shape
Implementation Method 2
performing electropolishing by placing an electrode plate in the bath and passing an electric current between the electrode plate and the hollow needle
Data Source
AI summary
Provided is a novel manufacturing method for a conical hollow needle that makes it possible to efficiently form a conical part that has a nearly perfectly circular outer circumferential surface shape. The present invention is a method of manufacturing a conical hollow needle that has a conical part that has a tapered outer circumferential surface. The manufacturing method involves immersing a hollow needle having a straight shape in an electrolyte solution to conically electropolish an outer circumferential surface. From a start to an end of the electropolishing, the hollow needle, which serves as an anode, is sandwiched between a pair of cathodes at a prescribed distance therefrom in a radial direction, and the hollow needle is rotated around a needle axis thereof to change which faces of the hollow needle are opposite to the cathodes.