Numerical Control Unit Stepwise Override for Smooth Speed Change

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Solution Overview

Problem

Conventional technologies face challenges in achieving rapid and smooth speed changes using overrides, leading to increased machine shock, machining errors, and high load in creating high-speed cycle machining data, especially when gradual acceleration/deceleration is required.

Innovation Solution

A numerical control unit that includes a command program analysis unit, an override input unit, a stepwise override change unit, and a speed operation unit, which analyzes commanded speeds, inputs overrides as a multiplying factor, and stepwise changes the override within specified times or amounts per interpolation cycle to calculate the feed speed, enabling gradual acceleration/deceleration in a short time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the override is changed directly as the actual override, then the speed change response is fast, but the machine shock and machining errors increase

Engineering Contradiction:

Improvespeed change responseVSAvoidmachine shock and machining errors

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies preliminary action by calculating and storing acceleration/deceleration data in advance during the command program analysis phase. This pre-calculated data is then referenced during execution to achieve smooth speed changes without real-time complex calculations, resolving the contradiction between fast response and reduced machine shock.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by making the actual override change stepwise through multiple interpolation cycles rather than instantly. The override is adjusted gradually over a specified number of cycles, enabling smooth acceleration/deceleration that reduces machine shock while maintaining responsive speed control.

Inventive Principle:

Principle #15Dynamics

2Reliability

If high speed cycle machining data is created in consideration of acceleration/deceleration, then the smooth speed change is achieved, but the data capacity and creation load increase

Engineering Contradiction:

Improvesmooth speed changeVSAvoiddata capacity and creation load

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the acceleration/deceleration consideration from the high-speed cycle machining data itself and handles it separately through override adjustment. This separation allows the high-speed cycle data to remain simple and compact while smooth speed changes are achieved through the override mechanism, reducing both data capacity and creation load.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent makes the override mechanism multi-functional by using it for both speed control and acceleration/deceleration management. This universal approach eliminates the need for separate acceleration/deceleration data structures, reducing overall system complexity and data requirements while maintaining smooth speed transitions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the override is updated by a tiny amount each time using a ladder program, then the machine shock is reduced, but the load of creating the ladder program increases

Engineering Contradiction:

Improvemachine shock reductionVSAvoidprogram creation load

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies self-service by enabling the numerical control unit to automatically perform the gradual override adjustment without requiring external ladder programming. The system autonomously calculates and applies stepwise override changes based on the specified interpolation cycles, eliminating the need for complex ladder programs while achieving smooth acceleration/deceleration.

Inventive Principle:

Principle #25Self-service

4Productivity

If the feed speed is changed rapidly, then the productivity is improved, but the machining errors and machine shock increase

Engineering Contradiction:

Improvefeed speedVSAvoidmachining errors

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent uses preliminary action by pre-calculating acceleration/deceleration data during command program analysis. This allows rapid feed speed changes to be implemented while maintaining machining precision, as the system is already prepared with the appropriate acceleration profiles before execution begins.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by adjusting the override stepwise through multiple interpolation cycles rather than instantly. This dynamic approach allows the feed speed to change rapidly in terms of overall timing while smoothly transitioning through intermediate values, reducing machine shock and machining errors while maintaining high productivity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9256213B2Numerical control unit having function to smoothly change feed speed when override is changed

Publication Date: 2016.02.09 FANUC LTD

AI summary

A commanded speed is acquired by a command program analysis unit, an override is acquired by an override input unit, and the override before input is changed in steps by a stepwise override change unit to the override that is input, in a predesignated time or by a predesignated change amount, and outputs the override changed as an actual override. The actual override is acquired by a speed operation unit in an interpolation cycle from the stepwise override change unit and the commanded speed is multiplied by the actual override to calculate a feed speed.