Pellet Extruder with Variable Volume Chamber for 3D Printing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
3D printing using pellet extrusion faces challenges with stringing issues due to the lack of a retraction mechanism, limiting the ability to move the nozzle unit to different locations without leaving behind unwanted plastic strings.
Innovation Solution
An extruder-based print head with an internal volume enlargement unit and an actuator connected to an extrusion screw, which allows for the retraction of liquefied material into an expansion volume, creating a larger internal volume to manage pressure and prevent dripping or stringing, enabling the print head to move to new positions without material loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pellet extrusion is used for 3D printing, then material feeding efficiency is improved, but stringing occurs due to lack of retraction mechanism
Solution Approach 1:
The patent applies the dynamics principle by making the internal volume of the extrusion unit variable through a movable piston. The piston can dynamically adjust the chamber volume between printing and retraction phases, enabling the system to adapt its configuration based on operational requirements. This dynamic volume adjustment allows the extrusion unit to function both as a high-efficiency pellet feeder and as a system capable of material retraction to prevent stringing.
Solution Approach 2:
The patent implements parameter changes by varying the internal volume parameter of the extrusion unit. By changing the volume parameter through piston movement, the system creates negative pressure during retraction to pull material back, and positive pressure during extrusion to push material forward. This parameter variation resolves the contradiction between maintaining feeding efficiency and preventing stringing.
2Adaptability or versatility
If nozzle unit moves to different locations, then printing versatility is improved, but material dripping occurs without retraction
Solution Approach 1:
The dynamic piston mechanism enables the extrusion unit to adjust its internal volume in real-time based on the operational phase. During movement between print locations, the piston retracts to increase chamber volume, creating negative pressure that prevents material dripping. This dynamic adaptation allows versatile positioning while maintaining material control.
Solution Approach 2:
The system applies preliminary anti-action by creating negative pressure in the extrusion chamber before and during nozzle movement. This preliminary pressure adjustment counteracts the gravitational force that would cause material to drip from the nozzle, enabling the print head to move to different locations without material loss.
3Object-generated harmful factors
If internal volume is enlarged for retraction, then stringing is prevented, but device complexity increases
Solution Approach 1:
The patent merges the retraction mechanism with the existing extrusion screw and chamber structure. The piston is integrated into the extrusion unit, and the retraction function is combined with the material feeding function. This merging approach enables stringing prevention without adding a completely separate, complex retraction system.
Solution Approach 2:
The extrusion unit is designed with multi-functionality, serving both as a material feeding mechanism and as a retraction system. The same chamber and piston structure that enables high-efficiency pellet extrusion also provides the variable volume needed for material retraction and stringing prevention, eliminating the need for separate dedicated components.
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 stringing and allows for the print head to be moved to different locations without material loss, enhancing the versatility and quality of 3D printing using pellet extrusion techniques.
Implementation Method 1
By creating an enlargement of the internal volume present in the printing head, any pressure in the liquefied material is taken away instantly
Implementation Method 2
transform the material into liquefied material (i.e. molten by temperature and/or pressure) in print form
Implementation Method 3
transform the material into liquefied material (i.e. molten by temperature and/or pressure) in print form
Data Source
AI summary
Extruder based print head (1) for 3D printing with a material feed unit (2) for providing material in granular and/or liquid feed form, a material extrusion unit (3) arranged to receive the material in granular and/or liquid feed form and transform the material into liquefied material in print form, and a nozzle unit (4) in fluid communication with the material extrusion unit (3), the nozzle unit (3) comprising an output channel (5) and a nozzle (6) arranged to output the liquefied material. Furthermore, an internal volume enlargement unit (7) is provided in fluid communication with the output channel (5) of the nozzle unit (4), wherein the internal volume enlargement unit (7) has a first internal volume in a first operational status and a second internal volume in a second operational status, wherein the second internal volume is larger than the first internal volume.