Rotary Table Brake Lifetime Estimation via Torque and Inertia
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Solution Overview
Problem
Existing machine tools with rotary tables face divergence between estimated and actual brake disc lifetimes due to variations in machining load and workpiece inertia, leading to inaccurate brake replacement timing and potential machining errors.
Innovation Solution
A machine tool with a rotary table that calculates disturbance torque and inertia, using corresponding coefficients to accurately estimate brake disc wear and annunciate replacement needs, thereby determining brake replacement timing based on both operation counts and torque/inertia sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If brake operation count is used to estimate brake disc lifetime, then the estimation method is simple, but divergence occurs between estimated and actual brake lifetime due to variations in machining load and workpiece inertia
Solution Approach 1:
The patent changes the estimation parameters from simple operation count to a comprehensive model including disturbance torque, workpiece inertia, and brake holding force. The disturbance torque calculation unit computes torque based on motor current, and the lifetime estimation unit integrates multiple parameters (torque, inertia, operation count) to dynamically adjust the estimation, thereby resolving the contradiction between simplicity and precision.
Solution Approach 2:
The system implements feedback by continuously monitoring actual brake disc wear through sensors and comparing it with the estimated lifetime. The correction coefficient calculation unit adjusts the estimation based on the difference between actual wear and estimated wear, creating a closed-loop feedback mechanism that improves estimation accuracy while maintaining operational simplicity.
2Device complexity
If brake replacement timing is determined only by operation count, then the control system is simple, but machining errors may occur due to inaccurate brake replacement timing
Solution Approach 1:
The patent transitions from a simple operation-count-based replacement criterion to a multi-parameter decision model. The brake replacement determination unit considers disturbance torque, workpiece inertia, and accumulated wear to dynamically determine optimal replacement timing. This multi-parameter approach ensures reliable machining by accurately predicting when brake performance degrades, while the systematic integration keeps the control architecture manageable.
3Measurement precision
If disturbance torque and inertia are considered in brake lifetime estimation, then brake replacement timing precision is improved, but the calculation and control complexity increases
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing the relationship between disturbance torque and brake wear in a database. The lifetime estimation unit retrieves pre-established correlation data and applies correction coefficients based on pre-analyzed torque-inertia-wear relationships. This preliminary preparation reduces real-time computational complexity while maintaining high estimation precision.
Solution Approach 2:
The patent introduces intermediary elements including a disturbance torque calculation unit that mediates between motor current and brake torque, and a correction coefficient calculation unit that mediates between raw sensor data and final lifetime estimation. These intermediary processing layers simplify the overall calculation by breaking down complex relationships into manageable intermediate steps, reducing computational burden while preserving accuracy.
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 provides more precise brake disc lifetime estimation and timely maintenance, reducing machining errors by considering disturbance torque and inertia, thus aligning estimated and actual brake lifetimes.
Implementation Method 1
frictional wear of a brake disc is caused by disturbance torque by machining load at the brake holding and so on, as brake operation is repeated
Data Source
AI summary
A machine tool includes a rotary table to which a workpiece is mounted, a brake, a displays, a memory configured to store a table in which values of a first coefficient correspond to different sizes of a disturbance torque, and values of a second coefficient correspond to different sizes of inertia of the workpiece. The controller is configured to calculate a size of the disturbance torque, find a first coefficient corresponding to the calculated size of the disturbance torque and the table, find a second coefficient corresponding to the size of the inertia of the workpiece and the table, accumulate the found values of the first and second coefficients, and cause the display to generate an indicator of necessity of a replacement of the brake in response to that the accumulated values of the first and second coefficients reaches a predetermined value.