System and method for estimating true heats of welding processes

A closed-loop control system for a welder that performs a waveform-controlled electric arc welding process, the control system comprising:

• a sampling circuit that samples instantaneous current and voltage values of the waveform-controlled electric arc welding process during a snip interval;
• a true heat processor that computes a true heat over the snip interval and extrapolates a true heat over the snip interval plus a delay interval;
• a true heat setpoint adjustment that outputs a selected setpoint true heat value;
• and
• a controller that controls a parameter of the waveform-controlled electric arc welding process based on the extrapolated true heat over the snip interval plus the delay interval and the selected setpoint true heat value.

A closed-loop control system for a welder that performs a waveform-controlled electric arc welding process, the control system comprising:

• a sampling circuit that samples current and voltage values of the waveform-controlled power during a snip measurement interval;
• a voltage sample thresholding circuit that selects voltage sample values corresponding to one of a short condition and an arc condition;
• a true heat processor that computes a true heat over the snip measurement interval by integrating a product of voltage sample values selected by the voltage sample thresholding circuit and corresponding current sample values to estimate a true heat in one of the arc and the short;
• and
• a controller that adjusts the waveform-controlled electric arc welding process to maintain the estimated true heat at a desired value.

A method for estimating a true heat of a welding process performed over a welding process interval, the method comprising:

• (a) sampling a voltage and a current applied by the welding process over a snip measurement interval that is smaller than the welding process interval;
• (b) multiplying corresponding sampled voltage and current values to generate sampled power values;
• (c) integrating the sampled power values over the snip measurement interval to compute a sampled true heat produced during the snip measurement interval;
• and
• (d) based on the sampled true heat produced during the snip measurement interval, estimating the true heat of the welding process produced during the welding process interval.

An arc welding apparatus for performing a waveform-controlled arc welding process, the arc welding apparatus comprising:

• an arc welding torch that interacts with an associated weld;
• a power supply that applies a selected waveform-controlled power to the weld via the arc welding torch over a process interval, the power supply including a sampling circuit for sampling instantaneous current and voltage values of the power during a snip portion of the process interval;
• and
• a processor designed to (i) compute a true heat over the snip portion of the process interval, and (ii) extrapolate a true heat over the process interval based thereon.

A method for estimating a true heat of a welding process performed over a welding process interval, the method comprising:

• (a) sampling a voltage and a current applied to the weld over a snip interval that spans at least a portion of the welding process interval;
• (b) multiplying corresponding sampled voltage and current values to generate sampled power values;
• (c) classifying each sampled power value as one of a sampled short power value and a sampled arc power value;
• (d) computing a true heat in the short over the welding process interval based on the sampled short power values;
• and
• (e) computing a true heat in the arc over the welding process interval based on the sampled arc power values.

An open root pipe welding method including:

• performing an open root pipe welding process;
• measuring a snip of current and voltage samples during a measured portion of the open root pipe welding process;
• computing based on the snip a true heat produced during the measured portion of the open root pipe welding process;
• extrapolating the true heat produced during the measured portion over an unmeasured portion of the open root pipe welding process to produce a true heat value;
• and
• adjusting a welding process parameter of the open root pipe welding process based on the true heat value.