Dynamic Extrusion Screw Control for 3D Printing
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Solution Overview
Problem
Existing extrusion-based 3D printing technologies face challenges in maintaining a constant material output, leading to geometry deviations and defects such as porosities in printed components.
Innovation Solution
The development of a procedure to create local and dynamic output characteristics for extrusion devices, which involves continuously capturing the rotating angle and output volume of the extrusion screw, and using this data to adjust the rotation speed and ensure a constant material discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the extrusion screw rotates at a constant speed to maintain steady material discharge, then the global average material flow remains relatively constant, but significant pulsations occur on a shorter time scale leading to geometric deviations
Solution Approach 1:
The patent applies dynamics by transitioning from constant rotational speed to dynamically adjusted rotational speed. The extrusion screw's rotational speed is continuously varied based on real-time material discharge measurements, allowing the system to compensate for pulsations and maintain consistent material flow despite the inherent periodic variations in screw rotation
Solution Approach 2:
The patent implements feedback control by measuring the actual material discharge rate and using this information to adjust the extrusion screw's rotational speed. A sensor detects the material discharge, and this measurement feeds back to the control system, which then modifies the motor speed to maintain the desired discharge rate, eliminating geometric deviations caused by pulsations
2Manufacturing precision
If the extrusion rate is not precisely controlled, then the printing process is simpler and faster, but the extruded strands exhibit geometric deviations resulting in defects such as porosity or contour deviations
Solution Approach 1:
The patent uses feedback control to precisely control the extrusion rate. A sensor measures the actual material discharge, and this information is fed back to adjust the extrusion screw speed in real-time, ensuring consistent strand geometry and eliminating defects like porosity and contour deviations
Solution Approach 2:
The patent replaces simple mechanical constant-speed rotation with an electronically controlled variable-speed system. The motor driving the extrusion screw is controlled by an electronic system that adjusts speed based on feedback, substituting a sophisticated control mechanism for simple mechanical operation to achieve precise extrusion rate control
Data Source
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AI summary
A method for creating a local discharge characteristic of an extrusion device, wherein the extrusion device discharges a printable material at a discharge nozzle by means of a motor-driven extrusion screw to form a three-dimensional structure from the printable material, and wherein the local discharge characteristic defines a discharge volume of the printable material from the discharge nozzle as a function of a rotation angle of the extrusion screw and/or a multiple thereof, comprising the steps of: - discharging the printable material by controlling the motor such that the extrusion screw has a substantially constant rotational speed; - continuously acquiring rotation angle information of the extrusion screw and storing the rotation angle information in a digital data memory;- Continuous detection of the strand-extruded material using a sensor system comprising at least one sensor and determination of the discharge volume of the strand-extruded material for a certain strand section; - Continuous assignment of the determined discharge volume to a stored rotation angle information of the extrusion screw, and - Creation of a local discharge characteristic based on a multitude of stored rotation angle information and their respective assigned discharge volumes.;