3D Printer Hot End Reverse Flow Prevention
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Solution Overview
Problem
Conventional 3D printer hot ends often experience clogging due to reverse flow of melted filament into the barrel, caused by the difference between the nozzle discharge diameter and filament diameter, leading to inhibited material flow and fabrication issues.
Innovation Solution
A ring-shaped reverse flow preventing member is integrated into the hot end's flow path to minimize the gap between the filament and the inner wall, preventing melted material from flowing back upstream and reducing clogging by maintaining the filament in a solid state, with a metal member and case member enhancing heat dissipation and temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner diameter of the flow path is reduced to be close to the wire diameter of the filament to minimize clearance, then reverse flow of melted filament is prevented, but manufacturing precision deteriorates due to filament diameter tolerance variations
Solution Approach 1:
The patent changes the physical state parameter of the filament by introducing a melting portion that heats and melts the filament before it reaches the nozzle. This transformation from solid to molten state allows the material to flow smoothly through the nozzle without reverse flow issues, while the solid filament in the feeding portion maintains precise dimensional tolerance for consistent feeding.
2Temperature
If cooling measures such as heat dissipating fins or water cooling are applied to the barrel to prevent filament melting, then filament melting is prevented, but clogging occurs due to reverse flow of melted filament from the nozzle to the barrel
Solution Approach 1:
The patent divides the barrel into functionally distinct segments: a cooling portion with heat dissipating fins for preventing filament melting during storage and feeding, and a melting portion with a heater for melting the filament before nozzle discharge. This segmentation allows each portion to perform its specific function without interfering with the other, preventing both melting during feeding and reverse flow clogging.
Solution Approach 2:
Different thermal properties are applied to different portions of the barrel. The cooling portion has high heat dissipation capability through fins to maintain low temperature and prevent melting, while the melting portion has localized heating capability to melt filament only where needed for discharge. This local differentiation of thermal characteristics resolves the contradiction between preventing melting and enabling controlled melting for discharge.
3Reliability
If the gap between the flow path inner wall and filament is reduced to prevent reverse flow, then melted filament cannot invade the barrel side, but the system becomes sensitive to filament diameter tolerance variations
Solution Approach 1:
The patent introduces a temperature parameter change that transforms the filament from solid to molten state in the discharge portion. This allows the system to accommodate filament diameter variations because the molten material becomes fluid and can adapt to slight dimensional variations, eliminating the sensitivity to tolerance that would exist with a fixed clearance design for solid filament.
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 solution effectively prevents clogging, ensuring continuous fabrication by maintaining the filament in a solid state and optimizing temperature distribution, thereby allowing reliable deposition material flow.
Implementation Method 1
forcibly cooling the barrel 102 by a fan
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3(A)~3(B)
AI summary
A hot end for a 3D fabrication apparatus, the hot end comprising: a printhead 100 having a supplying opening 11 to supply a filament-shaped deposition material, a discharging opening 41 to discharge the deposition material being melted, and a flow path 12 to communicatively couple linearly the supplying opening 11 and the discharging opening 41; and a heating means 60 to melt the deposition material in the flow path 12, wherein a ring-shaped reverse flow preventing member 50 to prevent the deposition material melted by the heating means 60 from reversely flowing through the flow path 12 toward the supplying opening 11 side is arranged in the flow path 12 between the heating means 60 and the supplying opening 11, through which ring-shaped reverse flow preventing member 50 the deposition material is inserted.