Hopper Recesses for Uniform Extrusion in Compact Additive Manufacturing
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Solution Overview
Problem
Screw extruders used in additive manufacturing are limited by their weight and size, which restricts their application due to the need for either a traversable design or an oversized 3D printing device, and existing solutions do not adequately address the uniform extrusion of granular materials.
Innovation Solution
A charging system with a specially designed hopper featuring axially and radially tapering recesses that extend along the hopper axis parallel to the extruder screw, allowing for improved material conveyance and retention, ensuring uniform extrusion patterns by adjusting the width and depth of recesses to match the dimensions of granules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional hopper with large cross-section is used to prevent bridging, then material flow is improved, but the extruder size and weight increase
Solution Approach 1:
The hopper wall is equipped with axially extending recesses at specific locations where material bridging occurs. These recesses create localized expansion spaces that facilitate material flow only where needed, rather than requiring a uniformly large cross-section throughout the entire hopper. This allows the hopper to maintain a compact overall size while still preventing bridging at critical points.
Solution Approach 2:
The hopper cross-section is effectively segmented into multiple flow paths by the recesses. Instead of relying on a single large open space, the recesses divide the material flow into several channels, improving flow reliability without increasing the overall hopper volume or weight.
2Reliability
If a conventional hopper with large cross-section is used to prevent bridging, then material flow is improved, but the device size increases
Solution Approach 1:
The recesses create localized three-dimensional expansion spaces within the hopper wall structure. These local expansions provide the necessary volume for material to redistribute and flow smoothly without requiring a uniformly large cross-section across the entire hopper, thus maintaining a compact device footprint.
Solution Approach 2:
Instead of increasing the cross-sectional area in the horizontal plane, the invention utilizes the axial dimension by extending recesses along the hopper axis. This creates vertical expansion spaces that facilitate material flow without increasing the horizontal footprint of the device.
3Area of stationary object
If the hopper cross-section is reduced to decrease device size, then device compactness is improved, but material bridging occurs
Solution Approach 1:
The recesses create localized three-dimensional expansion spaces within the hopper wall structure. These local expansions provide the necessary volume for material to redistribute and flow smoothly without requiring a uniformly large cross-section across the entire hopper, thus maintaining a compact device footprint.
4Length of moving object
If a shorter extruder design is used to maintain compactness, then device size is reduced, but uniform extrusion of granular materials becomes difficult
Solution Approach 1:
The recesses perform preliminary action by facilitating material redistribution and preventing bridging before the material enters the extruder screw. This pre-processing of the material flow ensures that granular materials are properly positioned and distributed, enabling uniform extrusion even in a compact extruder with reduced length.
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 proposed charging system enhances the extrusion of granular materials by achieving more uniform patterns, particularly with tough thermoplastics, and allows for a shorter extruder design, maintaining a compact extruder apparatus with a favorable length-to-diameter ratio.
Implementation Method 1
the material falls onto the screw driven by gravity
Data Source
AI summary
It is provided a charging system for feeding processing material, in particular granular processing material to at least one extruder screw, comprising a hopper that is adapted to guide the processing material along a feed direction to the extruder screw and extends along a hopper axis, which in the properly mounted state of the charging system extends parallel to a longitudinal axis of the extruder screw.In the proposed charging system, the hopper includes a plurality of recesses each extending axially with respect to the hopper axis on a hopper wall extending around the hopper axis.