Plasma Torch Piercing Control Using Arc Voltage Feedback

Solution Overview

Problem

In plasma cutting machines, the plasma arc often extinguishes during the piercing step due to increased arc voltage, leading to reduced cutting performance and wastefulness in power supply capacity, as the plasma torch is retracted to avoid molten metal damage and the power source's reserve capacity is not utilized efficiently.

Innovation Solution

A plasma cutting machine equipped with a controller, voltage sensor, and actuator that determines the completion of the piercing step based on arc voltage, holding the plasma torch at a specific height to prevent arc extinction and efficiently manage power supply capacity by moving the torch horizontally after piercing, thereby reducing power wastage and enhancing cutting performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the plasma torch is retracted to a high position during the piercing step to avoid molten metal damage, then the plasma torch is protected from damage, but the arc voltage increases and may cause arc extinction

Engineering Contradiction:

Improveplasma torch protectionVSAvoidarc voltage

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The controller determines piercing completion based on arc voltage changes before the torch needs to be retracted. By detecting when the piercing step is complete through voltage monitoring, the system can prepare for the position change in advance, ensuring the torch is only moved when necessary and minimizing the duration of high voltage conditions that could cause extinction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors arc voltage during the piercing step and uses this feedback to determine when piercing is complete. This closed-loop control allows the system to adapt to real-time conditions, adjusting the retraction timing based on actual voltage changes rather than following a fixed schedule, thereby preventing both premature and delayed position changes that could lead to arc extinction.

Inventive Principle:

Principle #23Feedback

2Reliability

If the plasma power source has an output capacity with reserve power to prevent arc extinction, then arc continuity is maintained, but the power supply capacity becomes wasteful

Engineering Contradiction:

Improvearc continuityVSAvoidpower supply capacity wastefulness

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The controller determines piercing completion based on arc voltage changes before the torch needs to be retracted. By detecting when the piercing step is complete through voltage monitoring, the system can prepare for the position change in advance, ensuring the torch is only moved when necessary and minimizing the duration of high voltage conditions that could cause extinction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors arc voltage during the piercing step and uses this feedback to determine when piercing is complete. This closed-loop control allows the system to adapt to real-time conditions, adjusting the retraction timing based on actual voltage changes rather than following a fixed schedule, thereby preventing both premature and delayed position changes that could lead to arc extinction.

Inventive Principle:

Principle #23Feedback

3Power

If the plasma torch is held at a specific height during the piercing step, then the arc voltage remains stable, but the piercing step duration increases

Engineering Contradiction:

Improvearc voltage stabilityVSAvoidpiercing step duration

Core Design Contradiction:

PowerVSLoss of time

Solution Approach 1:

The controller determines piercing completion based on arc voltage changes before the torch needs to be retracted. By detecting when the piercing step is complete through voltage monitoring, the system can prepare for the position change in advance, ensuring the torch is only moved when necessary and minimizing the duration of high voltage conditions that could cause extinction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors arc voltage during the piercing step and uses this feedback to determine when piercing is complete. This closed-loop control allows the system to adapt to real-time conditions, adjusting the retraction timing based on actual voltage changes rather than following a fixed schedule, thereby preventing both premature and delayed position changes that could lead to arc extinction.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Accurate determination of piercing step completion based on arc voltage reduces power supply capacity requirements, preventing arc extinction and improving cutting performance by minimizing power wastage and maintaining efficient plasma arc maintenance.

Implementation Method 1

The plasma arc is generated by an arc discharge between the electrode of the plasma torch and the material

Methodology Applied

Scientific EffectArc discharge: Electric Arc

Implementation Method 2

The voltage sensor detects an arc voltage applied to the plasma torch from the plasma power source

Methodology Applied

Scientific EffectVoltage detection:

Data Source

PatentUS11772183B2Plasma cutting machine and method for controlling plasma cutting machine

Publication Date: 2023.10.03 KOMATSU SANKI

AI summary

A plasma torch moves to a piercing position. The plasma torch generates a plasma arc and starts a piercing step at the piercing position. Whether the piercing step is completed is determined based on the arc voltage. The plasma torch is held at the piercing position in the horizontal direction from the start of the piercing step until the completion of the piercing step. The plasma torch is moved in a predetermined direction including at least the horizontal direction after the piercing step is completed.