Machine Tool Dynamic Error Compensation Without Force Sensors
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Solution Overview
Problem
Existing numerical control systems for machine tools face challenges in accurately compensating dynamic errors caused by forces and velocities during cutting operations without using additional sensors, leading to increased costs and complexity in calculating compensation amounts.
Innovation Solution
A numerical control device that measures the shape of a test workpiece and calculates dynamic compensation parameters based on the comparison between the command shape and measured data, allowing for dynamic error compensation without the need for pressure sensors, by using a measurement unit, dynamic compensation parameter calculation unit, and dynamic compensation unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pressure sensors are attached to the machine tool to detect cutting point load and compensate tool deflection, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The machine tool uses its own measurement capabilities to detect and compensate for dynamic errors. The measurement unit measures the shape of the workpiece, and the control unit calculates compensation amounts based on this measurement data, eliminating the need for external sensors.
Solution Approach 2:
The patent replaces the mechanical sensor-based detection system with a measurement-based system. Instead of using pressure sensors to directly detect cutting forces, the system measures the actual workpiece shape and infers dynamic errors from the deviation between measured and commanded shapes.
2Manufacturing precision
If additional sensors are used to detect cutting point load for dynamic error compensation, then manufacturing precision is improved, but cost increases
Solution Approach 1:
The measurement unit serves multiple functions: it measures both static geometric errors and dynamic errors during cutting. By using the same measurement system for both purposes, the patent eliminates the need for separate sensors and reduces overall system cost.
Solution Approach 2:
The machine tool system compensates for its own dynamic errors using its built-in measurement capabilities. The control unit processes measurement data to calculate compensation amounts, making the system self-sufficient without requiring additional sensing equipment.
3Manufacturing precision
If static compensation methods are used to correct machining errors, then manufacturing precision is improved for static errors, but dynamic errors generated during cutting cannot be compensated
Solution Approach 1:
The patent transitions from static compensation to dynamic compensation by continuously measuring the workpiece shape during or after cutting and calculating compensation amounts based on actual cutting conditions. The control unit adjusts compensation in real-time based on the measured dynamic errors.
Solution Approach 2:
The system implements a feedback mechanism where the measurement unit measures the actual workpiece shape, the control unit compares it with the commanded shape to detect dynamic errors, and then calculates and applies compensation amounts to correct these errors in subsequent operations.
Data Source
AI summary
A numerical control device causes a machine tool to perform cutting with a command coordinate value indicated by a cutting command received from a command analysis unit. The numerical control device includes a dynamic compensation parameter calculation unit that calculates a dynamic compensation parameter for compensating for a dynamic error generated by a force acting on the machine tool and a velocity upon cutting, based on a command shape, and a dynamic compensation unit that compensates for the dynamic error with respect to the command coordinate value, based on the dynamic compensation parameter calculated, in which the dynamic compensation parameter calculation unit acquires only the dynamic error from a comparison of the command shape and the measurement data, and calculates the dynamic compensation parameter from the dynamic error acquired.