Independent Screw Conveyors for Asphalt Temperature Homogenization
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Solution Overview
Problem
Existing material handling systems for road construction fail to maintain uniform temperature distribution in asphalt mixes during transport and storage, leading to uneven paving quality due to temperature-dependent bitumen viscosity, affecting density and layer thickness.
Innovation Solution
A material conveying system with independently operable screw conveyors and a control system that allows for delayed startup and adjustable ratio of transverse to main flow, enabling precise temperature homogenization by delaying or shutting off screw conveyors based on temperature measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If screw conveyors are continuously operated to mix cold edge material with hot core material, then temperature homogeneity is improved, but the first surge of cold material from the truck is unnecessarily mixed with the hot mix
Solution Approach 1:
The control system delays the startup of screw conveyors until after the first surge of material has passed through the main conveyor. This preliminary action ensures that cold edge material is not mixed with hot core material at the beginning of the conveying process, while still allowing temperature homogenization to occur later when the mix is ready for discharge.
2Ease of operation
If screw conveyors are coupled to the main conveyor drive, then operational simplicity is maintained, but the ratio of transverse flow to main flow cannot be adjusted to control mixing
Solution Approach 1:
The control system enables dynamic adjustment of the screw conveyor startup and shutdown timing relative to the main conveyor operation. The screw conveyors can be started delayed and shut off early, allowing the operator to control the ratio of transverse flow to main flow and optimize the mixing temperature after leaving the bunker.
3Productivity
If screw conveyors are started immediately, then mixing begins early, but cold edge material is mixed with hot core material unnecessarily
Solution Approach 1:
The control system implements periodic operation of the screw conveyors, starting them delayed after the first surge of material and shutting them off early before the end of the conveying process. This periodic action allows the screw conveyors to operate only when needed for temperature homogenization, avoiding unnecessary mixing of cold edge material with hot core material while still achieving effective mixing when required.
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
Achieves improved temperature homogeneity in asphalt mixes, ensuring consistent paving quality by preventing early mixing of cold edge material with hot core material and optimizing the ratio of cross-flow to main flow, thus enhancing the load-bearing capacity and evenness of the road surface.
Implementation Method 1
screw conveyors (6, 7), which define a transverse conveying flow and are arranged in the bunker halves
Implementation Method 2
main conveying device (5), which defines a main conveying flow and runs between the first and second bunker halves
Implementation Method 3
temperature measuring system, which records the temperature of the main conveying flow after leaving the material bunker
Data Source
Figure 1
Figure 2~3
AI summary
The invention describes a material conveying system (1) for road pavers and feeders. The material conveying system (1) comprises a material hopper (2) which includes a first and a second hopper half (3, 4), a main conveying unit (5) which defines a main conveying flow and runs between the first and second hopper half (3, 4), and screw conveyors (6, 7) which define a transverse conveying flow and are arranged in the hopper half (3, 4). A characteristic feature of the material conveying system (1) is that the screw conveyors (6, 7) can be operated independently of the main conveying unit. The independent operation of the screw conveyors (6, 7) and the main conveying unit (5) allows for improved homogenization of the mixing temperature of the paving material.