Screw Extruder for High Viscosity Metal Compaction
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Solution Overview
Problem
Screw extrusion of high viscosity metals like aluminum is challenging due to sticking friction, requiring high pressures and excessive energy to overcome frictional forces, making continuous processes impractical.
Innovation Solution
A specially designed screw extruder with a shorter screw length, controlled temperature profile, and a compacting chamber that restricts rotational flow, combined with a progressive reduction in screw core diameter and outer diameter, to reduce torsion forces and facilitate consistent extrusion by promoting sticking and kneading of metal within a short compaction area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If screw extrusion is used for high viscosity metals, then continuous extrusion is achieved, but enormous frictional forces require excessive energy and pressure
Solution Approach 1:
The patent changes the physical parameters of the extrusion system by using a shorter screw length (reducing the extrusion distance) and controlling the temperature profile along the extruder. These parameter changes reduce the total frictional work while maintaining continuous extrusion capability, directly addressing the energy consumption problem.
Solution Approach 2:
The extrusion process is segmented into distinct zones: a feeding zone with longer screw length for material intake, and a compacting zone with shorter screw length for high-pressure compaction. This segmentation allows the material to be gradually processed, reducing energy requirements compared to a single long high-pressure zone.
2Stress or pressure
If screw length is increased to achieve proper compaction, then compaction pressure is improved, but torsion forces become excessive
Solution Approach 1:
The screw design implements local quality by having different effective lengths in different zones. The feeding zone has a longer screw for material intake with lower compaction requirements, while the compacting zone has a shorter screw where high compaction pressure is needed. This localized approach achieves proper compaction without subjecting the entire screw to excessive torsion forces throughout its length.
3Productivity
If extrusion chamber is designed to restrict rotational flow, then compaction efficiency is improved, but device complexity increases
Solution Approach 1:
The extrusion chamber is designed with features that preliminarily restrict rotational flow before the material reaches the die. By pre-restricting rotation in the compacting zone, the material is properly compacted and oriented before extrusion, improving compaction efficiency without requiring complex mechanisms during the actual extrusion process.
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
Enables efficient and continuous extrusion of high viscosity metals by reducing frictional work and energy requirements, achieving the necessary compaction pressure over a shorter distance, resulting in a consistent and practical process for producing products of unlimited length.
Implementation Method 1
an increasing pressure is produced due to the dragging of the material which sticks to the liner and the screw surfaces along the extruder
Implementation Method 2
The liner 2 is provided with cooling channels 3 to control the temperature under the extrusion process
Implementation Method 3
reaching the pressure necessary to force the material through the die at the end of the housing
Data Source
AI summary
A screw extruder for the continuous extrusion of materials with high viscosity, in particular metals such as aluminum and its alloys. The extruder includes an Archimedes screw (1) rotationally provided within a liner (2) of a screw housing (4) having an inlet (11) for the feeding of the material to be extruded, a compacting or extrusion chamber (5) and an extrusion die assembly with a die (6) which forms the shape of the extruded product (7). The required compaction takes place at the down-stream end of the screw towards the extrusion chamber (5) corresponding to up to 540° of the rotation of the screw, or up to 1.5 turns of the screw flight length. The solid plug of metal formed at the end of the screw and extrusion chamber (5) is restricted from rigid rotation to obtain the required compaction and extrusion pressure.