Wire Feed Control in CMT Welding for Uniform Deposition
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Solution Overview
Problem
In deposition welding and additive manufacturing, achieving consistent deposition rates is challenging due to variations in welding current and wire feed, leading to inconsistent layer thickness, especially when the free wire length or torch distance changes.
Innovation Solution
The method involves continuously monitoring the wire feed and adjusting welding parameters such as current, wire length, torch distance, and angle to maintain a constant average wire feed, using an integrating or proportional-integrating controller to regulate the wire feed and shift working points or interpolate between them to achieve consistent deposition rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding current is kept constant, then welding process stability is improved, but deposition rate consistency deteriorates when wire length or torch distance changes
Solution Approach 1:
The patent changes the controlled parameter from welding current to wire feed rate. By controlling the wire feed rate directly instead of maintaining constant current, the system achieves consistent deposition rates even when geometric parameters like wire length or torch distance vary. This parameter substitution resolves the contradiction between process stability and deposition consistency.
Solution Approach 2:
The patent implements a feedback control system that continuously monitors the wire feed rate and adjusts welding parameters accordingly. The controller compares the actual wire feed rate with the desired rate and dynamically adjusts the welding current and other parameters to maintain consistent deposition, resolving the contradiction through closed-loop control.
2Productivity
If wire feed rate is increased to maintain deposition rate, then productivity is improved, but manufacturing precision deteriorates due to inconsistent layer thickness
Solution Approach 1:
The patent employs dynamic adjustment of welding parameters during the welding process. The system continuously adapts the wire feed rate, welding current, and other parameters in real-time based on actual process conditions, enabling both high productivity and consistent layer thickness through dynamic optimization rather than static parameter settings.
Solution Approach 2:
The system dynamically changes multiple welding parameters including wire feed rate, welding current, and potentially torch position or angle. By coordinating changes across multiple parameters rather than adjusting only one, the system maintains both high deposition rates and uniform layer thickness.
3Manufacturing precision
If multiple welding parameters are adjusted to maintain constant deposition rate, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical adjustment mechanisms with electronic control and software-based parameter management. Instead of physical mechanisms for adjusting wire feed rate, welding current, and other parameters, the system uses electronic sensors, controllers, and algorithms to achieve precise control, reducing mechanical complexity while maintaining or improving precision.
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 approach ensures a uniform thickness of the weld seam or applied material layer, maintaining consistent deposition rates by dynamically adjusting welding parameters in response to deviations in wire feed, thereby improving process reliability and efficiency.
Implementation Method 1
a welding process is formed by cyclical alternation of an arc phase and a short-circuit phase
Implementation Method 2
the welding wire is moved towards the workpiece during the arc phase until it touches a workpiece and then, after a short circuit is formed during the short-circuit phase
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The invention relates to a welding process with a consumable welding wire (5), in particular a cold metal-transfer welding process for build-up welding, and also to a welding apparatus (1) for carrying out such a welding process. According to the invention, during the welding process a preset melt-off efficiency (Ab) of the welding wire (5) is kept substantially constant, in that the average wire feed (vmean) of the welding wire (5) is controlled, wherein the current wire feed (v(t)) is measured, the average measured wire feed (vmean) is compared with a specified average wire feed (vsoll_mean) corresponding to the desired melt-off efficiency (Ab), and, in accordance with the deviation (Δv) of the average measured wire feed (vmean) from the specified average wire feed (vsoll_mean) as the system deviation, the welding current (I), the free length of the welding wire (5), the distance of the contact tube of the welding torch from the workpiece (CTWD Contact Tip to Work Distance) and/or the inclination angle of the welding torch (4) are changed as welding parameters (Pi).