Ground Milling Roller Tumbling Control for Motor Load Reduction
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Solution Overview
Problem
Ground milling machines with height-adjustable milling rollers face issues during rapid lowering, leading to excessive load on the drive motor and potential damage, as well as chisel damage due to abrupt braking torque increases.
Innovation Solution
Implementing a controlled tumbling movement of the milling roller, either two-dimensional or three-dimensional, via open-loop and/or closed-loop control to reduce the braking torque and protect the chisels, along with adaptive control of the lowering speed based on the drive motor's power and rotational speed to prevent motor overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the milling roller is lowered rapidly to increase penetration speed, then productivity is improved, but the drive motor is subjected to excessive loads exceeding its power limit
Solution Approach 1:
The milling roller is given a tumbling movement instead of rigid straight lowering, making the lowering dynamic rather than static. This tumbling motion allows the roller to penetrate ground material more efficiently while distributing the load over time, preventing sudden power spikes that would exceed motor limits
Solution Approach 2:
The tumbling movement creates a periodic action where the milling roller alternates between engagement and slight disengagement with the ground material. This periodic engagement pattern reduces continuous braking torque, allowing faster overall penetration while keeping instantaneous motor loads within safe limits
2Productivity
If the milling roller is lowered rapidly to increase milling depth, then productivity is improved, but the chisels are damaged due to excessive braking torque
Solution Approach 1:
The tumbling movement transforms the static rigid lowering into a dynamic motion where chisels engage and disengage periodically. This reduces impact forces and braking torque on individual chisels, preventing damage while achieving rapid depth adjustment
Solution Approach 2:
The tumbling movement acts as a cushioning mechanism by preventing direct rigid impact of the milling roller onto the ground material. The oscillating motion absorbs and distributes impact forces, protecting chisels from sudden excessive braking torque before damage can occur
3Device complexity
If open-loop control is used for tumbling movement, then device complexity is reduced, but control precision and adaptability are limited
Solution Approach 1:
A sensor detects the actual tumbling movement of the milling roller and feeds this information back to the control unit. The control unit compares the detected movement with the desired tumbling pattern and adjusts actuator commands accordingly, enabling adaptive control that responds to actual machine conditions while maintaining reasonable system complexity
Data Source
AI summary
The present invention relates to a method for operating a ground milling machine which comprises at least one height-adjustable milling roller, wherein the milling roller performs a tumbling movement (T′) which is controlled by way of open-loop and/or closed-loop control during lowering in operation. The present invention further relates to a control device for the closed-loop and/or open-loop control of this method, and also to a ground milling machine with such a control device.