Spindle Key Phase Detection for Accurate Tool Holder Mounting
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Solution Overview
Problem
Existing machine tools face challenges in accurately determining the phase of a tool holder with respect to the spindle rotation direction due to gaps between the spindle key and tool holder key groove, leading to inconsistent phase determination and reduced rigidity when trying to add elastic members or tapered surfaces, which are not compatible with existing facilities and increase costs.
Innovation Solution
A machine tool system that includes a tool holder with a key groove, a spindle drive unit with a spindle key, a tool exchanger with a grip key, and a numerical controller that controls the spindle drive unit to press the spindle key into the key groove of the tool holder, determining the phase by monitoring load torque and rotation direction, allowing for accurate phase determination without modifying existing facilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an elastic member is added to the key groove or a tapered surface is added to determine the phase, then phase determination accuracy is improved, but device complexity and cost increase, and compatibility with existing machine tools is reduced
Solution Approach 1:
The patent extracts the phase determination function from the mechanical structure (key groove and spindle key interface) and transfers it to the control system through load torque detection. By monitoring the load torque during spindle rotation, the control system identifies the phase position without requiring any modifications to the mechanical coupling structure, thus maintaining simplicity and compatibility while achieving accurate phase determination
Solution Approach 2:
The patent replaces the mechanical phase determination method (using elastic members or tapered surfaces in the key groove) with a sensor-based detection method. The load torque sensor detects the torque variations during spindle rotation to determine the phase position, substituting mechanical structure modifications with a sensing and control system approach that avoids increasing device complexity
2Measurement precision
If an elastic member is added to the key groove or a tapered surface is added to determine the phase, then phase determination accuracy is improved, but tool holder rigidity deteriorates due to structural modifications
Solution Approach 1:
The patent extracts the phase determination function from the tool holder structure (key groove) and relocates it to the control system. By detecting load torque during spindle rotation, the system determines phase position without modifying the tool holder's mechanical structure, thereby preserving its rigidity while achieving accurate phase measurement
Solution Approach 2:
The patent substitutes mechanical modifications to the tool holder (such as adding elastic members to the key groove) with a non-contact sensing method. The load torque sensor detects phase information through torque variations during rotation, eliminating the need to compromise tool holder rigidity for phase determination
3Measurement precision
If the key groove structure is modified to add elastic members or tapered surfaces, then phase determination is improved, but compatibility with existing machine facilities is reduced and incidental facility costs increase
Solution Approach 1:
The patent makes the control system perform multiple functions: it not only controls the spindle rotation but also detects the load torque and determines the phase position. This multi-functionality allows the system to achieve accurate phase determination using existing machine facilities without requiring additional specialized components or modifications to the tool holder structure
Solution Approach 2:
The patent extracts the phase determination capability from the mechanical interface (key groove) and implements it through the control system's load torque detection function. This approach maintains compatibility with existing machine tools and tool holders while achieving accurate phase determination, as no modifications to the mechanical structure are required
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable and simple phase determination of the tool holder with respect to the spindle rotation direction, maintaining tool holder rigidity and compatibility with existing machine tools, thereby enhancing machining accuracy and reducing wear on key grooves.
Implementation Method 1
the spindle is rotated to press the spindle key to the key groove of the tool holder so as to determine the phase
Data Source
AI summary
A machine tool includes: a tool holder which includes a key groove; a spindle drive unit which includes a spindle key that can be fitted into the key groove of the tool holder and a spindle and which removably holds the tool holder; a tool exchanger which includes a grip key and a grip that holds the tool holder at a fixed position with respect to the spindle; and a numerical controller which controls the tool exchanger so as to fit and remove the tool holder with respect to the spindle, and the numerical controller controls the spindle drive unit such that when the tool holder is fitted to the spindle, in a state where the key groove of the tool holder is inserted in the spindle key, the spindle is rotated to press the spindle key to the key groove so as to determine the phase of the tool holder with respect to the spindle.