Extrusion Screw Control for 3D Printing Discharge Pulsations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing extrusion devices for 3D printing face challenges in maintaining precise control over material output, leading to geometry deviations and defects such as porosities in printed components.
Innovation Solution
The extrusion device incorporates a control unit that utilizes local, global, and dynamic output characteristics to adjust the rotation of the extrusion snail, ensuring a constant material discharge by varying the rotation speed and angle within a revolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If screw speed is regulated to control volumetric discharge, then average material discharge remains relatively constant, but significant pulsations occur over shorter timescales
Solution Approach 1:
The patent applies dynamics by making the screw rotation speed variable rather than constant. The control unit dynamically adjusts the rotation speed of the extrusion screw based on detected strand dimensions, using time-dependent or position-dependent speed profiles to compensate for pulsations and maintain consistent material discharge throughout the printing process.
Solution Approach 2:
The patent implements feedback control by using an optical measurement system to continuously detect the dimensions of the extruded strand and feeding this information back to the control unit. The control unit then adjusts the screw rotation speed in response to these measurements, creating a closed-loop control system that maintains manufacturing precision.
2Device complexity
If single-screw extruders are used for material extrusion, then device complexity is reduced, but precise control over material discharge becomes challenging
Solution Approach 1:
The patent introduces a measurement system with optical sensors that detect strand dimensions and provide feedback to the control unit. This feedback mechanism enables precise control of material discharge from the relatively simple single-screw extruder structure, resolving the contradiction between device simplicity and control precision.
Solution Approach 2:
The patent controls the rotation speed of the extrusion screw as a variable parameter rather than a fixed value. By dynamically adjusting this parameter based on process conditions and desired output, the system achieves precise material discharge control while maintaining the simplicity of the single-screw extruder design.
3Ease of operation
If constant rotational speed is maintained for the extrusion screw, then operation is simplified, but geometric deviations and defects such as porosity occur
Solution Approach 1:
The patent transitions from constant to variable rotational speed operation. The control unit implements time-dependent or position-dependent speed profiles that dynamically adjust the screw rotation speed to compensate for discharge variations, maintaining component geometry precision while keeping operation relatively simple through automated control.
Solution Approach 2:
The patent uses preliminary action by pre-calculating or pre-programming the desired speed profile based on the printing path and material characteristics. The control unit executes this predetermined speed variation pattern to prevent geometric deviations before they occur, rather than reacting to defects after they form.
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 significantly reduces pulsations in material discharge, allowing for the production of high-quality 3D components with reduced defects, by compensating for fluctuations in material output and maintaining consistent geometry.
Implementation Method 1
an extrusion screw for conveying the at least one printable material from a material feed to a discharge nozzle
Implementation Method 2
a motor for rotatably driving the extrusion screw
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An extrusion device for producing three-dimensional structures from at least one printable material, comprising an extrusion screw for conveying the at least one printable material from a material feed to a discharge die for dispensing the at least one printable material, a motor for rotatably driving the extrusion screw, and a control unit configured to control the rotation of the extrusion screw by controlling the motor, wherein the control unit includes a local discharge characteristic that defines a discharge volume of the printable material from the discharge die as a function of a rotation angle of the extrusion screw and/or a multiple thereof, wherein the extrusion device has a rotary encoder for detecting rotation angle information of the extrusion screw, and the control unit is further configuredto adjust the desired material discharge from the discharge nozzle by controlling the motor to regulate the rotation of the extrusion screw, depending on the discharge volume defined from the local discharge characteristics for the detected rotation angle information.