Variable-Depth Milling Drum for Complex Road Geometry
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Solution Overview
Problem
Existing pavement milling technologies struggle to efficiently remove road material while minimizing additional material removal, especially when dealing with complex geometry defects and uneven surfaces, which leads to increased environmental impact and resource inefficiency.
Innovation Solution
The system employs a digital surface analysis using various sensors to identify road defects and create a minimum material removal map. A control system then selects appropriate milling tools and tool paths to remove only the necessary material, minimizing additional removal and optimizing the milling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional full-width milling is used to prepare sub-base surfaces, then consistent asphalt density can be maintained, but excessive road material is removed and reprocessed
Solution Approach 1:
The system transitions from uniform full-width milling to localized variable-depth milling, where each zone of the road surface receives customized material removal based on its specific condition. The mill drum is divided into multiple independently controllable zones that can be raised or lowered to achieve precise depth control in each location, removing only the necessary amount of material while preserving sound pavement.
Solution Approach 2:
The mill drum incorporates hydraulically actuated segments that can dynamically adjust their vertical position during operation. This dynamic control allows the system to respond to real-time surface variations and defect locations, continuously optimizing the milling depth across different zones to match actual material removal requirements.
2Manufacturing precision
If mill cutting depth is adjusted to maintain smooth flat milled surface, then surface quality is improved, but additional sound material is removed
Solution Approach 1:
The system applies different milling depths to different zones based on their specific surface conditions and defect characteristics. Rather than uniformly lowering the mill to accommodate the deepest defect, each zone is milled to its required depth, preserving sound material in areas that do not require deep removal while maintaining overall surface smoothness through controlled transitions between zones.
Solution Approach 2:
The system performs preliminary scanning and analysis of the road surface to identify defect locations, types, and depths before milling begins. This advance knowledge allows the control system to pre-calculate the optimal milling depth for each zone, ensuring that only the minimum necessary material is removed while still achieving a smooth, continuous milled surface ready for paving.
3Ease of operation
If fixed width milling is used for road repair, then paving width requirements are met, but excessive material is removed when repairing small defects
Solution Approach 1:
The mill drum is divided into multiple independently controllable segments or zones along its width. This segmentation allows different portions of the drum to operate at different depths or even be selectively engaged/disengaged, enabling the system to mill only the specific areas containing defects rather than the entire fixed width path, thus reducing material removal while still meeting paving width requirements.
Solution Approach 2:
The system applies partial milling action by selectively engaging only those portions of the mill drum that correspond to defect locations. Rather than applying full-width milling coverage, the system uses sensor data to identify and treat only the necessary areas, performing partial action that removes material only where needed while leaving surrounding sound pavement intact.
Data Source
AI summary
Disclosed is a method and apparatus for digital control of a milling machine drum to minimize road material milled using complex geometry. A digital representation of a surface and/or subsurface of a road is loaded into a controller. Road defects are identified based on the digital surface, by comparing defect digital characteristics with the digital surface. A minimum removal map can be generated using the defect digital characteristics. A milling tool path can then be generated to minimize material removal, based on the minimum removal map. The mill depth and movement of a mill drum can then be controlled based on the milling tool path.