Rotating Piston Flow Control for Extrusion Pausing
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Solution Overview
Problem
Extrusion-based processes in generative manufacturing lack the ability to pause and restart briefly, leading to issues like component inaccuracies, material overcharging, and structural damage due to continuous operation, limiting the production of high-quality components with complex inner structures.
Innovation Solution
A device with a rotating piston and flange system is placed between the extrusion unit and outlet die, featuring a borehole and groove that allow for controlled volume flow management, enabling start-stop functionality and volume regulation by redirecting material through a bypass channel, allowing for temporary storage or reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extrusion-based processes operate continuously without pausing, then productivity is maintained, but manufacturing precision deteriorates due to component inaccuracies and structural damage
Solution Approach 1:
The system dynamically switches between continuous extrusion mode and paused mode using a rotatable piston with angularly positioned grooves. The piston can be rotated to different angular positions to control material flow, enabling the system to adapt between continuous operation and brief pausing, thus resolving the contradiction between maintaining productivity and ensuring manufacturing precision.
Solution Approach 2:
The invention changes the flow parameter by rotating the piston to different angular positions. When the groove is aligned with the outlet die, material flows continuously; when rotated away, material flow is paused or redirected through the bypass channel. This parameter change enables precise control over extrusion timing, allowing pausing without compromising component accuracy while maintaining overall productivity.
2Ease of operation
If material flow is interrupted by stopping the screw rotation, then pausing is achieved, but manufacturing precision worsens due to overcharging and dimensional deviations
Solution Approach 1:
The piston with its groove and bypass channel acts as an intermediary device between the extrusion unit and outlet die. Instead of directly stopping the screw rotation, the system uses the piston to control material flow. The groove can be rotated away from the outlet die opening, redirecting material through the bypass channel, which provides a smooth transition and prevents overcharging and dimensional deviations that would occur with direct screw stopping.
Solution Approach 2:
The material flow path is segmented into two separate channels: the main channel through the groove leading to the outlet die, and the bypass channel through the bypass die. This segmentation allows independent control of material flow to the die versus bypass flow, enabling precise pausing capability without disrupting the extrusion process or causing dimensional inconsistencies.
3Adaptability or versatility
If a piston with groove and bypass channel is introduced, then volume flow control is achieved, but device complexity increases
Solution Approach 1:
The piston serves multiple functions: it acts as a flow control valve by rotating the groove to different positions, it redirects material through the bypass channel, and it enables both continuous and paused extrusion modes. This multi-functionality justifies the added device complexity, as a single component performs what would otherwise require multiple separate control mechanisms, achieving volume flow control while maintaining operational simplicity.
4Ease of manufacture
If extrusion is performed without volume flow control, then process simplicity is maintained, but manufacturing precision deteriorates due to material overcharging and lag
Solution Approach 1:
The system introduces dynamic control of volume flow through the rotatable piston mechanism. The groove can be positioned at different angular angles relative to the outlet die, dynamically adjusting the amount of material that reaches the die versus being redirected through the bypass channel. This dynamic volume flow control prevents material overcharging and lag, ensuring uniform material distribution while maintaining relatively simple extrusion processes.
Data Source
AI summary
A device for influencing the volume flow of extruded plastically deformable material conveyed to an outlet nozzle. A flange arranged between an extrusion unit and an outlet nozzle and is connected to the extrusion unit and the outlet nozzle. A duct from the extrusion unit and the outlet nozzle is incorporated in the flange. A piston is mounted in the flange to be rotatable perpendicular to the longitudinal axis of the duct and is located through the duct. In the piston there is a hole which opens into a bypass duct routed to a bypass nozzle. On the outer lateral surface of the piston there is at least one groove in the region of the duct so that, depending on the angular positions of the piston, material can be conveyed through the at least one groove to the outlet nozzle or through the hole to the bypass nozzle.