Axial Feed Control Using Feed-Rate-Based Position Rounding

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Solution Overview

Problem

In continuous axial feed methods for machine tools, variations in the stopping position and movement of objects occur due to operator timing errors, especially at higher axial feed rates, leading to inaccuracies in reaching the desired position.

Innovation Solution

A control device and method that includes an input unit for specifying axial feed rates, a motor driving control unit, an amount-of-movement detecting unit, a coordinate position detecting unit, and a rounding processing unit to round the coordinate position or amount of movement to a predetermined place corresponding to the axial feed rate, ensuring accurate stopping even when the operator releases the feed operation at varying times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the axial feed rate is increased to improve productivity, then the feed speed increases, but the stopping position accuracy deteriorates due to operator timing errors

Engineering Contradiction:
Improveaxial feed rateVSAvoidstopping position accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The system continuously monitors the actual axial feed position through the amount-of-movement detecting unit and coordinate position detecting unit, comparing it with the target position. When the axial feed operation is stopped, the system provides feedback by calculating the difference between the target position and actual position, then automatically feeds the moved object by this difference amount to achieve accurate stopping regardless of operator timing errors.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the manual mechanical control system with an automated control system that uses detection units and control units to manage the axial feed process. Instead of relying on operator skill and timing, the system uses automatic detection of movement amount and coordinate position, followed by automated compensation feeding, thereby substituting human operation with a controlled mechanical-electrical system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If manual axial feed operation is used to maintain simple device structure, then the control system remains simple, but stopping position variation increases due to operator timing errors

Engineering Contradiction:
Improvecontrol system structureVSAvoidstopping position consistency
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The system performs self-correction by automatically detecting the stopping position error and compensating for it without requiring external intervention. When the axial feed operation is stopped, the control unit automatically calculates the position difference and commands the motor to feed the moved object by the exact difference amount, enabling the system to self-correct operator timing errors and achieve consistent stopping positions.

Inventive Principle:
Principle #25Self-service

3Loss of time

If the axial feed operation is stopped early to improve response time, then the operation time decreases, but the stopping position deviates more from the target position

Engineering Contradiction:
Improveaxial feed operation timeVSAvoidposition accuracy
Core Design Contradiction:
Loss of timeVSManufacturing precision

Solution Approach 1:

The system performs preliminary detection of the movement amount and coordinate position during the axial feed operation. When the operation is stopped, the control unit has already prepared the position data and can immediately calculate the difference and command compensation feeding, thereby eliminating the need for extended operation time while ensuring accurate stopping position through pre-prepared data and rapid automated correction.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3620874B1Control device and axial feed control method
Publication Date: 2021.03.24 FANUC LTD
  • EP3620874B1 patent drawingFigure 1
  • EP3620874B1 patent drawingFigure 2
  • EP3620874B1 patent drawingFigure 3

AI summary

A control device (14) includes: an input unit (52); a motor driving control unit (64); an amount-of-movement detecting unit (66); a coordinate position detecting unit (68); a display unit (56); and a rounding processing unit (70) configured to perform rounding processing to round the coordinate position and the amount of movement of an object (16) to be moved, to a rounding place corresponding to an axial feed rate. The motor driving control unit (64) drives motors (50X, 50Y) such that at least one of the coordinate position and the amount of movement of the moved object (16) is rounded.