Rotating Plasma Torch Control for Consistent Kerf Quality

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Solution Overview

Problem

Automated plasma cutting systems using CNC technology face challenges in achieving consistent and repeatable cut characteristics, such as dross, kerf width, and bevel, due to asymmetrical plasma jets and changing cut directions, leading to irregular edges and sizing issues.

Innovation Solution

A plasma cutting system with a gantry and torch carriage that allows the plasma cutting torch to rotate 360 degrees around its axis, maintaining a constant angular orientation with respect to the kerf and cut edge, while moving in perpendicular directions, using a motor with a hollow shaft rotor and controlled by a CNC system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the plasma torch is moved in different directions to cut various shapes, then the versatility of the cutting system is improved, but the consistency of cut characteristics (dross, kerf width, bevel) deteriorates

Engineering Contradiction:
Improvecutting direction flexibilityVSAvoidcut edge consistency
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The plasma torch is made rotatable about its longitudinal axis through 360 degrees, allowing the torch orientation to dynamically adjust during cutting operations. This enables the torch to maintain optimal angular orientation relative to the cut direction while cutting shapes of any complexity, thereby preserving cut edge consistency across all cutting directions.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If the plasma torch is rotated to maintain constant angular orientation, then the manufacturing precision of cut edges is improved, but the device complexity increases

Engineering Contradiction:
Improvecut edge consistencyVSAvoidtorch rotation mechanism
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The motor with hollow shaft rotor serves multiple functions: it provides rotational motion to the plasma torch for orientation control, and the hollow shaft design allows passage of plasma gases and electrical connections through the rotor. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If trial and error approach is used to obtain acceptable parts, then the adaptability to achieve desired cut quality is improved, but the productivity and time efficiency deteriorate

Engineering Contradiction:
Improvecut quality adjustment capabilityVSAvoidproduction time
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The system incorporates feedback control where the CNC controller monitors the torch orientation and cutting direction, automatically adjusting the torch rotation angle to maintain optimal cutting conditions. This closed-loop control eliminates the need for trial and error by continuously adapting to maintain cut quality, thereby significantly improving productivity.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3799996B1System for and method of cutting with a plasma torch
Publication Date: 2023.06.07 LINCOLN GLOBAL INC
  • EP3799996B1 patent drawingFigure 1
  • EP3799996B1 patent drawingFigure 2
  • EP3799996B1 patent drawingFigure 3

AI summary

A plasma cutting system Includes a plasma cutting table. A gantry (106) is movable along the plasma cutting table in a first direction. A torch carriage (104) is movable along the gantry (106) in a second direction that is perpendicular to the first direction. A torch holder (126) is attached to the torch carriage (104) and includes a motor (128) having a hollow shaft rotor (132). A plasma cutting torch (103) is attached to the hollow shaft rotor (132) for 360 degree rotation by the hollow shaft rotor (132) around an axis (124) of the plasma cutting torch (103). The invention also provides a plasma cutting method with such plasma cutting system (100).