Syringe Kit Screwed Surfaces Prevent Stick Slip
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Solution Overview
Problem
Syringe kits for mixing medicinal chemicals often experience stick and slip phenomena due to smooth surfaces, leading to disturbed smooth and steady operations when the barrels are screwed together.
Innovation Solution
The syringe kit features a connecting tube with a male screw and an inner tapered surface, paired with a screw tube and nozzle portion having a female screw, where either or both surfaces are roughened to a specific range (Ra1.0 to Ra2.0) to prevent stick and slip, and the taper angle is set between 6% and 12% for smooth engagement and disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If smooth mirror surfaces are used on the barrels, then manufacturing precision and appearance are improved, but stick and slip phenomena occur during screwing operations
Solution Approach 1:
The patent applies different surface qualities to different functional areas: the barrel bodies maintain smooth mirror surfaces for manufacturing precision and appearance, while only the screwing contact surfaces (male and female threads) are roughened to Ra1.6-Ra3.2 to prevent stick and slip phenomena. This localized differentiation resolves the contradiction by providing smooth surfaces where needed while adding roughness only where friction control is required for operational smoothness.
2Ease of operation
If rough surfaces are used on the screwing surfaces, then stick and slip phenomena are prevented, but manufacturing complexity increases
Solution Approach 1:
The patent controls the surface roughness parameter within a specific range (Ra1.6-Ra3.2) on the screwing surfaces to prevent stick and slip phenomena while avoiding excessive roughness that would complicate manufacturing. This parameter optimization resolves the contradiction by finding the optimal roughness level that provides operational smoothness without unnecessarily increasing manufacturing complexity.
3Stability of the object's composition
If the taper angle is too small, then connection stability is improved, but engagement and disengagement become difficult
Solution Approach 1:
The patent optimizes the taper angle parameter within the range of 6-12 degrees to balance connection stability with ease of engagement and disengagement. This angular parameter optimization resolves the contradiction by providing sufficient taper for smooth operation while maintaining adequate connection stability through the complementary male-female screw structure.
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 configuration ensures smooth and steady operations by preventing stick and slip phenomena and allowing for sufficient mixing of medicinal chemicals, with the added benefit of using cyclic polyolefin for high transparency and steam sterilization properties.
Implementation Method 1
either the outer periphery of the connecting tube portion of the first barrel and the surface of the male screw or the inner periphery of the screw tube portion of the second barrel and the surface of the female screw is roughened, or both of them are roughened, so as to have a surface roughness in a range between Ra1.0 and Ra2.0, and therefore it is possible to prevent stick and slip phenomena between the two members
Implementation Method 2
a stick and slip phenomenon (a friction vibration phenomenon where the friction surfaces stick and slip repeatedly) tends to occur on the screwed surfaces when the tip portion of one barrel and the tip portion of the other barrel are screwed together
Data Source
AI summary
A syringe kit for mixing two medicinal fluids includes first and second barrels containing medicinal fluids therein. The first barrel includes a connecting tube portion at a tip portion having a male screw on an outer periphery, and a non-roughened inner tapered surface on an inner periphery. The second barrel includes a second plunger, a screw tube portion with a female screw on an inner periphery thereof freely engageable with the male screw of the connecting tube portion, and a nozzle portion situated inside the screw tube portion with a non-roughened outer tapered surface fitting to the non-roughened inner tapered surface. A surface of the male screw and the outer periphery of the connecting tube portion, or a surface of the female screw and the inner periphery of the screw tube portion are roughened to a surface roughness in a range between Ra 1.0 and Ra 2.0 micrometer.