Feed Shaft Worm Gear Diagnosis Using Drive Torque Deviation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current abnormality determination systems for NC machine tools are labor-intensive and time-consuming, as they require manual measurement of indexing errors in rotary tables, and cannot accurately detect abnormal positions within the reducing gear.
Innovation Solution
An abnormality determination system that uses a gear mechanism or direct-acting motor to drive the feed shaft or spindle, with an encoder to detect speed or position, and calculates the drive torque command deviation to determine if the indexing is normal or abnormal, allowing for self-diagnosis and quick identification of indexing errors without additional measuring devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual measurement of indexing errors is performed using a rotary encoder, then measurement precision is improved, but loss of time and labor increases
Solution Approach 1:
The system uses the machine tool's own servo motor and encoder to perform self-diagnosis of indexing errors. The servo motor drives the rotary table through the worm gear mechanism, and the encoder detects position feedback. By comparing the commanded position with the actual position feedback, the system automatically determines indexing errors without requiring external measuring devices or manual measurement, thus resolving the contradiction between measurement precision and time consumption.
Solution Approach 2:
The patent replaces manual mechanical measurement methods with an automated electronic diagnosis system. Instead of using external rotary encoders and manual data collection, the system utilizes the existing servo control system's electronic feedback mechanisms to automatically detect and diagnose indexing errors, substituting mechanical measurement processes with electronic automation.
2Measurement precision
If external measuring devices are used to detect indexing errors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system utilizes the machine tool's own built-in servo motor and encoder for self-diagnosis, eliminating the need for external measuring devices. The encoder already present in the servo motor provides position feedback that is used to detect indexing errors, turning the machine's own components into diagnostic tools and avoiding additional measurement equipment.
Solution Approach 2:
The servo motor and encoder, originally designed for positioning control, are made multi-functional by also serving as diagnostic tools for detecting indexing errors. This universal use of existing components eliminates the need for separate measuring devices, reducing device complexity while maintaining diagnostic capability.
3Manufacturing precision
If comprehensive error measurement is performed across the full rotation range, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The system performs automated self-diagnosis using the servo control system, enabling rapid assessment of indexing accuracy across the full rotation range. The automation eliminates manual measurement time while maintaining comprehensive coverage, thus improving productivity without sacrificing manufacturing precision.
Solution Approach 2:
The system can perform diagnosis during idle time such as when the machine tool is started or when a workpiece is not chucked. This preliminary diagnosis action allows indexing accuracy to be verified before actual machining operations, ensuring manufacturing precision while minimizing impact on productivity through efficient timing.
4Measurement precision
If detailed diagnosis of reducing gear abnormality is performed, then measurement precision is improved, but ease of operation worsens
Solution Approach 1:
The system automatically analyzes the relationship between drive torque commands and position feedback to identify abnormal positions in the reducing gear. This automated analysis eliminates the need for operators to manually interpret complex measurement data, maintaining high detection precision while significantly improving ease of operation.
Solution Approach 2:
The system uses feedback from the encoder's position detection combined with drive torque command information to automatically identify abnormal positions. The feedback mechanism provides real-time data that the control system processes to pinpoint gear abnormalities, achieving both precision and operational simplicity through automated feedback-based diagnosis.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A system determining whether the feed shafts are normal or abnormal, the system including: a command generation unit that moves the feed shafts in a forward direction at a predetermined speed from a lower limit value to an upper limit value of a range of feeding movement by the numerical controller (18); and a feed shaft abnormality determination unit (19) that monitors a drive torque command during the movement of the feed shafts in the forward direction by the command generation unit, compares a monitoring result during the movement in the forward direction with a normal value of the drive torque command, determines that abnormality occurs when the drive torque command deviates from the normal value, and outputs the determination result.