Spindle Deterioration Detection via Inertial Rotation Time
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing machine tools lack a method to inspect the deteriorated state of their spindles without disassembling the spindle head, which can lead to unexpected production disruptions when bearing seizures or other failures occur.
Innovation Solution
A machine tool system that includes a spindle, a motor, an encoder, and software for calculating rotating speed, inertial rotation time, and acceleration, allowing for the detection of spindle deterioration by comparing measured values against predetermined thresholds, and outputting alarms when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated bearing-friction measuring apparatus is used to measure bearing friction, then measurement precision is improved, but device complexity increases and the method cannot be applied to inspect spindles in usable machine tools without disassembly
Solution Approach 1:
The machine tool control device performs multiple functions: it controls the spindle motor, measures rotation speed via encoder, calculates inertial rotation characteristics, and detects bearing abnormalities. This multi-functional approach eliminates the need for a dedicated bearing-friction measuring apparatus while maintaining inspection capability.
Solution Approach 2:
The machine tool inspects its own spindle bearing condition using its existing components (motor, encoder, control device). The control device utilizes the spindle's own inertial rotation characteristics to detect bearing abnormalities, enabling self-diagnosis without external specialized equipment.
2Measurement precision
If the spindle is inspected by disassembling the spindle head, then measurement precision is improved, but productivity decreases due to production interruption
Solution Approach 1:
The system performs preliminary inspection of the spindle bearing condition while the machine tool is still in operation or during brief idle periods. By detecting bearing abnormalities early through inertial rotation analysis, the system enables proactive maintenance scheduling that minimizes production interruption.
Solution Approach 2:
The inspection function operates continuously or periodically without requiring spindle disassembly or machine tool shutdown. The control device can measure inertial rotation characteristics during normal operation or brief pauses, maintaining continuous productivity while monitoring spindle health.
3Measurement precision
If bearing friction is measured using traditional methods, then measurement precision is improved, but ease of operation deteriorates due to the need for specialized equipment and procedures
Solution Approach 1:
The machine tool performs self-inspection using its existing control device and encoder. The control device automatically calculates inertial rotation time and detects bearing abnormalities without requiring operators to use specialized measurement equipment or perform complex friction torque measurements.
Solution Approach 2:
The patent replaces traditional mechanical friction torque measurement methods with an electrical/control-based approach. The control device uses encoder signals to measure rotation speed and calculate inertial rotation characteristics, substituting complex mechanical measurement systems with simpler electronic control and computation.
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 the detection of spindle deterioration before it causes production disruptions, allowing for proactive replacement and maintaining factory production capacity.
Implementation Method 1
an encoder configured to measure a rotation angle position of the spindle or the motor
Implementation Method 2
interrupting power of the motor to rotate the spindle with inertia
Data Source
AI summary
In order to make it possible to inspect a deteriorated state of a spindle incorporated in a machine tool without disassembling the machine tool, a command for speed V0 is output to the spindle and, when the rotating speed of the spindle reaches V0, power of a spindle motor is interrupted and a timer is started. The spindle continues to rotate with inertia while decelerating. Time T clocked by the timer when the spindle speed decreases to zero is read. When time T is outside a range between the upper and lower limits, the spindle is in the deteriorated state, and an alarm is output. When time T is not greater than the lower limit, the spindle and a bearing of the spindle are deteriorated and friction resistance increases. When time T is larger than the upper limit, oil holding force of grease of the bearing is deteriorated.