Wire EDM Controller Path Correction for Corner Precision

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Solution Overview

Problem

Conventional wire electrical discharge machining techniques face challenges in maintaining shape precision at corner and arc portions due to wire electrode deflection, leading to increased machining time and inefficiencies in path correction, especially when relying on manual adjustments and rule-based corrections.

Innovation Solution

A machine learning device integrated into a controller for wire electrical discharge machines uses reinforcement learning algorithms, such as Q-learning, to automatically calculate an optimal machining path that prevents shear drop at corner portions without significantly increasing machining time, by learning from data on machining conditions, path geometry, and environmental factors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional machining condition control modifies machining conditions when the wire electrode approaches corner portions, then deflection of the wire electrode is alleviated, but machining speed decreases and machining time increases

Engineering Contradiction:
Improveshape precision at corner portionsVSAvoidmachining speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system performs preliminary action by pre-calculating the optimal machining path that proactively compensates for wire electrode deflection before machining begins. The correction amount calculation unit computes the necessary path adjustment in advance based on workpiece shape data, corner position information, and wire deflection characteristics, allowing the wire to maintain precision without real-time speed modifications.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention replaces the mechanical approach of slowing down the wire electrode to maintain precision with an informational/computational approach. By substituting the physical mechanism (speed control) with a computational mechanism (path correction calculation), the system achieves the same precision goal without the penalty of reduced machining speed.

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

2Manufacturing precision

If conventional technique corrects the machining path based on rule of thumb, then it may work for simple shapes, but it cannot effectively correct the machining path for every type of corner

Engineering Contradiction:
Improvemachining path accuracyVSAvoidapplicability to different corner types
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts the correction amount based on varying parameters including corner position coordinates, workpiece shape characteristics, and wire deflection amounts. The correction amount calculation unit processes these multiple parameters to generate customized path corrections for each specific corner configuration, enabling effective handling of diverse corner types rather than applying a fixed rule of thumb.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system implements feedback by using actual machining data and wire deflection measurements to refine and update the correction amount calculations. The correction amount calculation unit continuously optimizes the machining path based on feedback from machining results, ensuring high accuracy across different corner types and workpiece geometries.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3486845B1Controller and machine learning device
Publication Date: 2023.06.21 FANUC LTD
  • EP3486845B1 patent drawingFigure 1
  • EP3486845B1 patent drawingFigure 2
  • EP3486845B1 patent drawingFigure 3

AI summary

A machine learning device provided in a controller for controlling a wire electrical discharge machine uses state variables (including data relating to a correction amount, a machining path, machining conditions, and a machining environment) observed by a state observation unit and determination data acquired by a determination data acquisition unit to machine-learn a correction for a machining path. Using the learning result, the machining path can be corrected automatically and accurately on the basis of a partial machining path, the machining conditions and the machining environment of the machining performed by the wire electrical discharge machine.