Rotary Table Clamp Release Detection Using Drive Load Patterns
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Solution Overview
Problem
Conventional rotary table devices face issues with detecting malfunction in the clamp mechanism due to increased abrasion and prolonged unclamping times, which can lead to shifting or other operational problems, especially in high-speed machine tools.
Innovation Solution
A rotary table device with a load detection system that drives the spindle using a predetermined inspection pattern after the clamp mechanism starts releasing, allowing for determination of clamp mechanism operation based on load changes over time, thereby detecting malfunctions while minimizing abrasion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the spindle is driven by a minute movement amount before clamping is released completely, then the abrasion of the brake disc is suppressed to some extent, but the clamp mechanism malfunction cannot be detected reliably and the spindle may be driven before brake torque decreases sufficiently
Solution Approach 1:
The patent replaces the mechanical proximity switch detection system with an electrical measurement system. A torque sensor detects the brake torque directly, and a measurement value determination unit processes this data to determine when unclamping is complete. This substitution allows for more reliable detection of clamp mechanism status without requiring large piston movements, thereby reducing brake disc abrasion while improving detection reliability.
Solution Approach 2:
The patent implements a feedback mechanism where the torque sensor continuously monitors brake torque during the unclamping process. The measurement value determination unit analyzes the torque change rate and absolute values to determine when unclamping is complete. This feedback loop enables precise control of the spindle driving timing, ensuring the spindle is driven only after sufficient brake torque reduction, thus preventing premature driving while minimizing abrasion.
2Reliability
If a proximity switch is used to detect piston position, then the spindle can be driven after unclamping is confirmed, but the apparatus size increases, cost increases, and reliability decreases
Solution Approach 1:
The patent replaces the mechanical proximity switch system with an electrical torque sensing system. Instead of mechanically detecting piston position, the system uses a torque sensor to measure brake torque and determines unclamping completion through electrical signal processing. This eliminates the need for additional mechanical components, reducing apparatus size and cost while improving reliability through more accurate torque-based detection.
Solution Approach 2:
The patent introduces a measurement value determination unit as an intermediary between the torque sensor and the spindle drive control. This intermediary processes the torque sensor signals, analyzes torque change rates, and determines the optimal timing for spindle driving. This intermediary layer enables sophisticated detection logic without requiring complex mechanical structures, thereby reducing device complexity while maintaining high detection accuracy.
3Reliability
If the piston moves slowly with fluid pressure, then the clamp mechanism operates reliably, but a relatively long period is taken until the piston reaches the separated position after unclamping starts
Solution Approach 1:
The patent implements preliminary detection of unclamping completion using torque sensing before initiating spindle driving. The torque sensor continuously monitors brake torque during piston movement, and the measurement value determination unit identifies when unclamping is complete based on torque characteristics. This preliminary detection allows the system to prepare for spindle driving in advance, reducing the overall time loss without compromising the reliable slow movement of the piston.
Solution Approach 2:
The patent uses real-time torque feedback during the piston movement to determine unclamping completion. The measurement value determination unit analyzes the torque change rate and absolute torque values to identify the moment when the piston has sufficiently separated from the brake disc. This feedback mechanism allows the system to optimize the transition from clamping to driving, reducing idle time while maintaining the reliability of slow, controlled piston movement.
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
This approach enables reliable detection of clamp mechanism malfunctions while reducing abrasion, allowing for timely and accurate spindle rotation initiation, improving operational reliability and reducing apparatus size and cost.
Implementation Method 1
A brake disc provided on a spindle is pressed against a clamping member provided immovably by a piston that is moved in a direction parallel to the spindle with fluid pressure. In this way, rotation of the brake disc and therefore the spindle is prevented by frictional force.
Implementation Method 2
a load detection portion that detects a load of the driving mechanism
Data Source
AI summary
A rotary table device according to the present invention includes: a spindle that supports a table; a driving mechanism that drives the spindle; a load detection portion that detects a load of the driving mechanism; a clamp mechanism that inhibits rotation of the spindle; a rotation control portion that causes the driving mechanism to drive the spindle with a predetermined inspection pattern after the clamp mechanism starts releasing clamping; and a determination portion that determines whether good or not with respect to an operation of the clamp mechanism based on of change over time in the load detected by the load detection portion when the spindle is driven with the inspection pattern.