Chuck Holding Force Detection Using Sensor Time Difference
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Solution Overview
Problem
The holding force of a chuck in a machine tool is difficult to measure directly, and the relationship between control amounts and holding force is inconsistent due to factors like chuck wear and lubrication changes.
Innovation Solution
A method for detecting and controlling the holding force of a chuck using sensors to measure the time difference between sensor states during closing and opening operations, correlating this with the tightening amount to set the desired holding force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the holding force is determined from control amount of the chuck mechanism, then the control is simple, but the measurement precision deteriorates due to inconsistency from wear and lubrication changes
Solution Approach 1:
The patent introduces sensors (first sensor and second sensor) as intermediary devices to detect the actual holding force of the chuck. These sensors act as mediators between the chuck mechanism and the control system, providing direct feedback on holding force rather than relying on indirect control amount measurements. This resolves the contradiction by maintaining simple control operation while achieving precise holding force measurement through the intermediary sensing mechanism.
Solution Approach 2:
The patent implements a feedback mechanism where sensor data about the chuck's holding force is fed back to the control system. The control unit uses this feedback information to adjust and maintain the desired holding force. This feedback loop enables precise measurement and control of holding force while keeping the control system simple and adaptive to wear and lubrication changes.
2Measurement precision
If sensors are added to detect chuck state, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent designs the sensor system to serve multiple functions: the first sensor detects when the chuck is in the open state, the second sensor detects when the chuck is in the closed state, and together they provide comprehensive holding force measurement. This multi-functionality reduces the need for separate specialized sensors for each detection task, thereby improving measurement precision while limiting the increase in device complexity.
Solution Approach 2:
The sensor system is integrated into the existing chuck mechanism in a way that the sensors utilize the mechanical movements and states already present in the system. The sensors detect natural states (open/closed positions) without requiring additional actuation or complex mounting structures, allowing precise measurement while minimizing added complexity.
Data Source
AI summary
Provided is technology which enables suitable control of a chuck holding force. In this machine tool comprising a main shaft provided with a chuck for holding a workpiece, when an open/close mechanism has performed a closing operation on the chuck such that the chuck enters a closed state from an open state, a holding force of the chuck on the workpiece in the closed state is acquired on the basis of the magnitude of a difference between a first time taken from when a control unit emits a control signal for the closing operation to the open/close mechanism to when a first sensor detects that the chuck is no longer in the open state, and a second time taken from when the control unit emits a control signal in an open/close mechanism to when a second sensor detects that the chuck has entered the closed state.