Twin-Screw Extruder for Homogeneous Bitumen Application
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Solution Overview
Problem
Existing devices for producing joint-shaped seams on asphalt surfaces suffer from pulsating and irregular bitumen application due to gas inclusions and uneven material distribution, leading to defects in the seam formation.
Innovation Solution
A mobile device equipped with a twin-screw extruder featuring intermeshing helices that compress and degas bituminous material, ensuring a homogeneous and consistent output, reducing gas inclusions and pulsation, and applying a band-shaped bitumen material along the seam flank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single kneading screw is used to convey bituminous material, then the device structure is simple, but the material flow becomes pulsating and contains trapped gas
Solution Approach 1:
The single kneading screw is divided into two intermeshing screws that rotate in opposite directions. This segmentation allows the material to be conveyed through multiple channels simultaneously, eliminating pulsating flow and trapping gas bubbles that occur with a single screw design.
Solution Approach 2:
Two separate screw conveyors are merged into a single integrated twin-screw extruder system where the screws intermesh. This combining of two material flow paths into one unified discharge system maintains continuous, pulsation-free flow while eliminating gas inclusions through the intermeshing action.
2Device complexity
If the channel width and height remain constant throughout the extruder, then the device structure is simple, but the bituminous material cannot be adequately compressed and homogenized
Solution Approach 1:
The channel cross-sectional dimensions are progressively reduced from the feed zone through the compression zone to the discharge zone. This gradual change in geometric parameters (width and height) creates increasing compression on the bituminous material, ensuring thorough mixing and homogenization while maintaining a relatively simple single-pass channel design.
3Productivity
If bituminous material is applied without prior degassing, then the application process is fast, but gas inclusions cause defects in the seam
Solution Approach 1:
The twin-screw extruder performs degassing action before the material reaches the discharge point. The intermeshing screws create shear forces and pressure variations that force trapped gas bubbles to rise and escape from the material stream, ensuring gas-free application without reducing processing speed.
Solution Approach 2:
The natural tendency of gas to become trapped during material conveyance is converted into a beneficial separation process. The pulsating shear forces generated by intermeshing screws create conditions that promote gas bubble coalescence and rise to the surface, where they can be eliminated before application.
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 solution achieves a homogeneous bitumen application with reduced gas inclusions and pulsation, resulting in a more consistent and defect-free joint-shaped seam on asphalt surfaces.
Implementation Method 1
the first screw extruder and the second screw extruder each have a channel forming a space between the respective turns of the first and second helix
Implementation Method 2
the channels have a channel width that decreases in width from an intake zone, through a compression zone to an discharge zone
Data Source
Figure 1
Figure 2~3
Figure 4.1~4.2
AI summary
To solve the problem of plasticizing and homogenizing a bituminous material with a mobile device, thereby at least reducing gas inclusions in the material and pulsation in the mass flow of the material, such a mobile device is proposed, comprising at least a feed unit, an extruder housing, and a discharge unit downstream of the extruder housing, wherein a twin-screw extruder is arranged in the extruder housing, comprising a first screw extruder and a second screw extruder with extruder axes running approximately parallel to each other, a first shaft and a second shaft, wherein the first screw extruder has a first helix on the first shaft and the second screw extruder has a second helix on the second shaft, and the first helix and the second helix are designed to intermeshing.and wherein the first screw extruder and the second screw extruder each have a channel forming a space between the respective turns of the first and second helix, the channels having a channel width that decreases in width from an intake zone, through a compression zone to an discharge zone of the twin-screw extruder, and the respective channels decreasing in channel height from the intake zone, through the compression zone to the discharge zone.