Arc Welding Start Control Using Wire Retraction After Contact
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Solution Overview
Problem
Conventional arc initiation techniques in welding result in high energy consumption, spatter, and potential spot welding of the wire to the workpiece, leading to reduced contact tip life and disrupted welding operations.
Innovation Solution
A welding power supply system that detects contact between the wire electrode and the workpiece using a low-current power source, enabling arc initiation by retracting the wire electrode after contact detection, thereby reducing the likelihood of spot welding and minimizing spatter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional arc initiation techniques are used with high current levels, then the arc can be ignited reliably, but spatter increases and contact tip life is reduced
Solution Approach 1:
The system performs preliminary wire retraction before applying high current arc ignition. The wire is retracted a predetermined distance (e.g., 0.25-2 inches) before the arc start current is applied, which prevents the wire from being molten during contact and reduces spatter generation while maintaining reliable arc ignition
Solution Approach 2:
The arc initiation process uses periodic action by first retracting the wire, then applying arc start current for a predetermined time period, and finally advancing the wire to establish the arc. This time-based periodic control sequence ensures reliable ignition while minimizing harmful spatter effects
2Reliability
If conventional arc initiation techniques are used with high current levels, then the arc can be ignited reliably, but contact tip life is reduced due to spot welding
Solution Approach 1:
The system performs preliminary wire retraction before applying high current arc ignition. By retracting the wire a predetermined distance before the arc start current is applied, the wire is positioned away from the contact tip during the high current pulse, preventing spot welding and extending contact tip life while maintaining reliable arc ignition
Solution Approach 2:
The invention extracts the wire from its normal contact position with the contact tip before applying the arc start current. This separation removes the wire from the harmful high current path during initiation, preventing damage to the contact tip while still enabling reliable arc ignition when the wire is subsequently advanced
3Object-generated harmful factors
If wire retraction is used to initiate the arc, then spatter is reduced, but the system complexity increases
Solution Approach 1:
The system uses the existing wire feed motor to perform both wire advancement and wire retraction functions. By controlling the motor to reverse direction for retraction and then resume normal operation for advancement, the system achieves arc initiation with reduced spatter without adding separate retraction mechanisms, thus minimizing control system complexity
Solution Approach 2:
The wire feed motor is made multi-functional by using it for both normal wire feeding and arc initiation retraction. This universal use of the existing motor eliminates the need for additional dedicated retraction actuators, reducing device complexity while achieving the spatter reduction benefit
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
The system effectively initiates the arc with lower current levels, minimizing spatter and extending contact tip life while ensuring secure welding operations.
Implementation Method 1
A welding power supply system that detects contact between the wire electrode and the workpiece using a low-current power source
Implementation Method 2
Conventional short circuit gas metal arc welding (GMAW), also referred to as metal inert gas (MIG) welding, is a welding process in which an electric arc forms between an electrode and pieces of metal that are to be welded. The electric arc generates heat that causes the pieces of metal to melt.
Data Source
AI summary
Systems and methods to start arc welding are disclosed. An example welding-type power supply includes: power conversion circuitry configured to convert input power to welding-type power; and control circuitry configured to: prior to a welding operation, control the power conversion circuitry to stop outputting the welding-type power to a wire electrode; and in response to identifying contact between the wire electrode and a workpiece: control the power conversion circuitry to output an arc starting current to the wire electrode; control a feed motor of a welding torch to retract the wire electrode; control the feed motor to advance the wire electrode based on a first parameter of the welding operation; and control the power conversion circuitry to output the welding-type power to the wire electrode based on the first parameter or a second parameter of the welding operation.