Plasma Penetration Welding Arc Control
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Solution Overview
Problem
Conventional penetration welding methods risk forming unintended holes in back components due to a sudden increase in plasma arc voltage during the formation of through holes in layered steel sheets, which can lead to insufficient hole size and quality.
Innovation Solution
A penetration welding method that maintains a constant plasma arc column width by controlling the plasma gas flow-rate and using a laser displacement gauge to determine the threshold for arc voltage and distance, ensuring the plasma arc column is eliminated before reaching the back components, thus preventing unwanted hole formation and ensuring a sufficient hole size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the arc voltage increase rate is maximized by using a high open circuit voltage source, then the penetration detection accuracy is improved, but the plasma arc column reaches back components and forms unintended holes
Solution Approach 1:
The plasma gas flow rate is dynamically adjusted during the hole digging process. The flow rate is set to a first value during initial drilling and then changed to a second value (different from the first) when the hole depth reaches a predetermined threshold, allowing controlled plasma arc column behavior to prevent back component damage while maintaining detection accuracy
Solution Approach 2:
The invention changes the plasma gas flow rate parameter at a critical moment in the process. By switching the flow rate when the hole depth reaches a predetermined value, the plasma arc column characteristics are modified to prevent it from reaching back components, thus resolving the contradiction between detection accuracy and harmful effects
2Manufacturing precision
If the plasma arc column is allowed to extend freely to detect penetration, then the through hole formation is achieved, but the arc voltage increases too rapidly causing harm to back components
Solution Approach 1:
The plasma gas flow rate is applied in distinct phases: a first flow rate during the initial hole digging phase, and a second flow rate when the hole reaches a predetermined depth. This periodic adjustment of the flow rate parameter controls the plasma arc column extension and prevents excessive voltage increase that would harm back components
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
This method allows for the formation of through holes with a sufficient size from the top surface to the back surface without forming holes in back components, simplifying the process and eliminating the need for detecting penetration, while maintaining a consistent arc voltage increase until the desired hole diameter is achieved.
Implementation Method 1
generating a plasma arc column from a plasma torch to a work that is layered steel sheets
Implementation Method 2
by causing a plasma arc column to be generated by a plasma torch
Implementation Method 3
forming a through hole in layered steel sheets by causing a plasma arc column to be generated
Data Source
AI summary
A penetration welding method includes a plasma welding step for forming a through hole in a work, which is a laminated steel plate, from a front surface to rear surface thereof without forming a hole in a component at the rear, by generating a plasma arc column from a plasma torch to the work. After the plasma arc column is generated, the plasma arc column is extinguished when an arc voltage or the length of the arc estimated from the arc voltage exceeds an end-determining threshold which is determined according to the thickness of the work. Further, plasma gas is discharged from the plasma torch at a flow rate at which the width of the plasma arc column is maintained approximately constant from the plasma torch side to the work side so that the arc voltage is increased at an approximately constant rate before and after penetration.