CNC Surface Speed Switching for Energy-Efficient Turning

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Solution Overview

Problem

In turning cutting processes, maintaining constant surface speed is challenging, leading to reduced accuracy and shortened tool life due to varying spindle speeds, and existing constant surface speed control techniques increase electric power consumption and risk spindle motor overheating.

Innovation Solution

A numerical control device with a surface speed calculating unit, cutting speed setting unit, comparison unit, and operation control unit that dynamically turns ON/OFF constant surface speed control based on designated spindle rotation speed and distance from the rotation center, ensuring surface speed remains within recommended cutting speed ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If constant surface speed control is continuously activated, then cutting accuracy is improved and tool life is extended, but electric power consumption increases and spindle motor may overheat

Engineering Contradiction:

Improvecutting accuracyVSAvoidelectric power consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by making the constant surface speed control function dynamically adjustable rather than continuously active. The control function is activated or deactivated based on real-time comparison of calculated surface speed against predetermined minimum and maximum cutting speeds, allowing the system to adapt its control intensity to actual machining conditions and reduce unnecessary energy consumption.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter state by comparing surface speed against minimum and maximum cutting speed thresholds. When the calculated surface speed falls within the acceptable range, constant surface speed control is deactivated; when it exceeds the range, control is activated. This parameter-based switching optimizes energy usage while maintaining cutting accuracy when needed.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If constant surface speed control is activated, then tool life is extended, but spindle acceleration/deceleration frequency increases leading to higher power consumption

Engineering Contradiction:

Improvetool lifeVSAvoidelectric power consumption

Core Design Contradiction:

Duration of action of stationary objectVSUse of energy by moving object

Solution Approach 1:

The patent monitors the surface speed parameter and compares it against minimum and maximum cutting speed thresholds. The constant surface speed control function is selectively activated only when the calculated surface speed exceeds these thresholds, rather than being continuously active. This parameter-based conditional activation extends tool life by maintaining appropriate cutting speeds while avoiding unnecessary spindle acceleration/deceleration that would increase power consumption.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If constant surface speed control is selectively activated/deactivated, then power consumption is reduced, but control complexity increases

Engineering Contradiction:

Improveelectric power consumptionVSAvoidcontrol complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent performs preliminary calculation of the surface speed based on the machining program and spindle rotation speed before executing the constant surface speed control function. By pre-calculating whether the surface speed exceeds the minimum or maximum cutting speeds, the system can deterministically activate or deactivate control without requiring complex real-time decision-making, thus reducing control complexity while still achieving power savings.

Inventive Principle:

Principle #10Preliminary action

4Manufacturing precision

If frequent spindle acceleration/deceleration is performed, then surface speed is maintained within recommended range, but spindle motor overheating risk increases

Engineering Contradiction:

Improvesurface speed control accuracyVSAvoidspindle motor temperature

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The patent compares the calculated surface speed against minimum and maximum cutting speed thresholds and only activates constant surface speed control when the surface speed exceeds these thresholds. This conditional activation based on parameter comparison ensures surface speed remains within the recommended range for cutting accuracy while minimizing unnecessary spindle acceleration/deceleration that would generate heat and cause motor overheating.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11669074B2Numerical control device

Publication Date: 2023.06.06 FANUC LTD

AI summary

To enable turning-on/off of constant surface speed control during machining. A numerical control device has a constant surface speed control function for controlling a spindle rotation rate to make a surface speed constant, and includes: a surface speed calculating unit for calculating a surface speed based on a spindle rotation speed having been designated and a distance from a rotation center; a cutting speed setting unit for setting a minimum cutting speed and a maximum cutting speed; a comparison unit for comparing the surface speed with the minimum cutting speed and the maximum cutting speed; and an operation control unit for controlling whether to activate the constant surface speed control function based on a result of the comparison made by the comparison unit.