NC Lathe Cut-Off Detection Using First Spindle Position Deviation
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Solution Overview
Problem
Conventional machine tools face challenges in precisely determining the success or failure of a cut-off operation due to minute positional deviations and varying frictional loads during the separation movement of the second spindle, leading to potential determination errors.
Innovation Solution
A machine tool with a first spindle capable of moving in an axis direction and a second spindle that performs a cut-off and separation movement, where the machine tool includes a movement controlling unit for stopping the first spindle at a command position during the second spindle's separation movement and a cut-off success or failure determining unit that monitors the positional deviation of the first spindle to assess the cut-off success, rather than relying on the second spindle's deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the machine tool monitors the positional deviation of the second spindle during separation movement to determine cut-off success, then the determination process is simple, but the measurement precision deteriorates due to minute positional deviations and frictional load variations
Solution Approach 1:
Instead of monitoring the positional deviation of the moving second spindle, the invention inverts the approach by monitoring the positional deviation of the stationary first spindle. This inversion eliminates the interference of movement-induced deviations and frictional load variations, enabling precise cut-off determination through a simpler monitoring approach.
2Reliability
If the threshold for determination is set larger to account for positional deviation during separation movement, then the reliability of the determination process improves, but the measurement precision deteriorates due to increased risk of determination error
Solution Approach 1:
The invention resolves this contradiction by inverting the monitoring target from the moving second spindle to the stationary first spindle. This eliminates the need to set larger thresholds to account for movement-related deviations, as the stationary first spindle's positional deviation remains minimal and consistent, enabling both high reliability and precision with a tighter threshold.
3Measurement precision
If the machine tool monitors the positional deviation of the first spindle during separation movement, then the measurement precision of cut-off determination improves, but the device complexity increases due to additional control requirements
Solution Approach 1:
The first spindle serves a dual function: it performs the cutting operation and simultaneously serves as the reference for monitoring cut-off success through its positional deviation. This self-service approach eliminates the need for separate monitoring mechanisms, achieving high measurement precision without significantly increasing device complexity.
4Measurement precision
If the first spindle is stopped at command position during separation movement, then the measurement precision of positional deviation improves, but the productivity deteriorates due to additional stop control
Solution Approach 1:
The first spindle is stopped at the command position in advance before the separation movement begins. This preliminary positioning ensures that the first spindle remains stationary during separation, providing a stable reference for precise positional deviation measurement. The stop duration is minimized to only what is necessary for accurate measurement, thereby limiting the impact on productivity.
Data Source
AI summary
Provided is a machine tool and a method for controlling the machine tool capable of precisely determine a success or a failure of a cut-off. An NC lathe performs a cut-off of a workpiece gripped by a first spindle and a second spindle and then performs a separation movement of the second spindle in a direction separating from the first spindle. The NC lathe includes a movement controlling unit adapted to perform a stop control of the first spindle at a command position of the first spindle during the separation movement of the second spindle and a cut-off success or failure determining unit adapted to monitor a positional deviation of the first spindle during the separation movement of the second spindle to determine a success or a failure of the cut-off, the positional deviation being a difference between the command position and an actual position of the first spindle.