Dynamic Contact Force Control in Machine Tool Finishing
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Solution Overview
Problem
Single-axis, force-controlled automated surface finishing tools struggle to maintain consistent contact pressure due to dynamic variables such as tool orientation, workpiece curvature, and abrasive media wear, leading to inconsistent material removal and surface finishing quality.
Innovation Solution
A control system that utilizes sensors to measure contact force and additional parameters like overturning moment, torque, and motor current to dynamically adjust the contact force, ensuring consistent pressure across the contact area, even as the tool orientation changes or abrasive media wears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-axis force control is used to maintain constant contact force, then the control system is simple, but contact pressure varies due to tool orientation and surface curvature
Solution Approach 1:
The control system measures additional parameters (overturning moment, torque, motor current) and uses this feedback to dynamically adjust the contact force, closing the control loop to compensate for variations in contact pressure caused by tool orientation and surface curvature
Solution Approach 2:
The system transitions from static force control to dynamic control by continuously adjusting the contact force based on real-time measurements of tool orientation, surface curvature, and abrasive wear, allowing the system to adapt to changing conditions
2Force
If contact force is held constant, then control is simple, but contact pressure increases when contact area is reduced due to orientation or curvature
Solution Approach 1:
The system changes the contact force parameter dynamically based on measured conditions (orientation angle, surface curvature radius, abrasive wear) rather than maintaining a constant value, optimizing contact pressure across varying operational conditions
3Duration of action of moving object
If abrasive media wears over time, then material removal continues, but more contact force is required to maintain the same material removal rate
Solution Approach 1:
The control system monitors motor current and torque as indicators of abrasive wear and uses this feedback to automatically increase contact force when wear is detected, maintaining consistent material removal performance throughout the abrasive media's service life
4Manufacturing precision
If manual control is used, then dynamic factors can be compensated, but automation is lost
Solution Approach 1:
The system enables the machine tool to automatically compensate for dynamic factors and abrasive wear through sensor measurements and closed-loop control, eliminating the need for manual intervention while maintaining the quality of process control that a skilled worker would provide
Data Source
AI summary
Techniques are provided for controlling the contact force in a single-axis, force-controlled tool responsive to dynamic process variables such as tool orientation relative to the workpiece, curvature of the workpiece wear of the abrasive media and other dynamic process variables that are not otherwise controlled by a single-axis, force-controlled actuator. A control system includes sensors for determining a contact force between the tool and the workpiece along a single-axis of compliance, and one or more additional process parameters, such as an overturning moment on the tool due to the orientation of the workpiece and surface curvature, torque about an axis of rotation of the tool, etc. The control circuit uses the measurement of these additional parameters are used to determine the control force between the tool and the workpiece.