Synchronous Spindle Recovery During Interrupted Tool Exchange

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Solution Overview

Problem

Machine tools face challenges in safely and efficiently managing tool exchanges during stoppages, particularly when using synchronous motors, where unrecognized rotor positions can lead to accidental rotation and potential damage.

Innovation Solution

Incorporating a controller with motor information storage to use specific commands for synchronous motors during recovery processes, ensuring safe positioning and operation by maintaining direct current supply states and utilizing position detection sensors to prevent rotor rotation issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a synchronous motor is used to rotate the spindle during tool exchange, then productivity and precision are improved, but the risk of accidental rotation and damage increases when rotor position is unrecognized

Engineering Contradiction:

Improvetool exchange efficiencyVSAvoidaccidental rotation damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The controller determines the motor type in advance and stores this information. When a stoppage occurs during tool exchange, the controller retrieves this stored information and executes appropriate recovery commands before attempting to rotate the spindle, preventing accidental rotation damage while maintaining efficient operation with synchronous motors

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes operational parameters based on motor type detection. For synchronous motors, the controller uses specific recovery commands that account for the motor's characteristics, while for other motor types, different commands are used. This parameter adaptation allows safe and efficient operation across different motor types

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If generic recovery commands are used during stoppage recovery, then device complexity is reduced, but manufacturing precision and operational safety deteriorate

Engineering Contradiction:

Improvecontrol system simplicityVSAvoidspindle positioning accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The controller is designed with multi-functionality to handle both synchronous and non-synchronous motors. By storing motor type information and selecting appropriate recovery commands based on this information, the single controller can safely manage different motor types without requiring separate control systems, thus maintaining precision while avoiding excessive complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11161209B2Machine tool

Publication Date: 2021.11.02 FANUC LTD

AI summary

A machine tool includes a motor configured to rotate a spindle, a tool magazine holding a plurality of tools, and a controller. The controller has a storage unit storing motor information indicating that the motor is a synchronous motor. When the machine tool stops, while a tool exchange process is carried out, due to electric power outage, operation of a stop button, a value of a drive current of the motor, or a value output from the sensor, the controller uses a command for the synchronous motor, based on the motor information, as a part of a series of commands for recovery of the machine tool, where the tool exchange process is a process in which a tool attached to the spindle is changed with one of the plurality of tools of the tool magazine.