Variable polarity power supply for welding
AssigneeVenable Industries, Inc.
InventorWayne H. Tuttle
Life of this patent
Estimating the term…
Abstract
Disclosed is a variable polarity power supply for arc welding that quickly switches between polarities in order to more easily re-establish the arc. The variable polarity power supply includes a current-limited boost circuit for providing increased open circuit voltage to re-establish the arc, while limiting the re-establishment current. The variable polarity power supply is particularly suitable for computer-controlled welding applications because it periodically restarts the arc in either direction without using high frequency radiation, and provides quick switching times along with a low reverse current to reduce the heat in the torch, thereby increasing the longevity of the torch.
Claims27
A variable polarity power supply for welding, said power supply having a first output applied to a workpiece, and having a second output applied to a torch, said power supply having a current source for providing current in the forward direction and in the reverse direction said power supply comprising:
- a control circuit for controlling the polarity of the first and the second outputs of the power supply;
- a plurality of drivers connected to the control circuit;
- a switching circuit for switching polarity of the power supply so that the polarity of the first output is switched with the polarity of the second output, said polarity switching circuit being responsive to the drivers;
- a boost circuit for significantly increasing the open circuit voltage and the power applied between said workpiece and said torch by the power supply in response to an increase in the voltage on said current source output.
A method for variable polarity arc welding by applying a variable, reversible voltage between a torch and a workpiece for providing current for a current source, said method comprising the steps of:
- first, applying a voltage between the torch and workpiece so that current flows between the torch and the workpiece;
- second, reversing the polarity of said voltage;
- third, substantially simultaneously with the second step, monitoring the absolute value of the voltage on said current source output;
- and
- fourth, if the absolute value of said voltage rises above a selected level, significantly increasing the open circuit voltage and the power applied between the torch and the workpiece.
A variable polarity power supply, said power supply having a first output and a second output, said power supply having a current source for providing current in the forward direction and in the reverse direction said power supply comprising:
- a switching circuit for switching polarity of the power supply so that the polarity of the first output is switched with the polarity of the second output;
- a circuit for controlling the switching circuit;
- a current limited boost circuit for significantly increasing the open circuit voltage and the power applied between said workpiece and said torch by the power supply in response to an increase in the voltage of said current source output.
A variable polarity power supply for welding, said power supply having a first output applied to a workpiece, and having a second output applied to a torch, said power supply having a current source for providing current for establishing and re-establishing an arc in forward and reverse directions, said power supply comprising:
- a control circuit for controlling the polarity of the first and the second outputs of the power supply;
- a plurality of drivers connected to the control circuit;
- a switching circuit for switching polarity of the power supply so that the polarity of the first output is switched with the polarity of the second output, said polarity switching circuit being responsive to the drivers;
- a boost circuit for significantly increasing the open circuit voltage and the power applied between said workpiece and said torch by the power supply in response to sensing a loss of said arc.
A variable polarity power supply for welding, said power supply having a first output applied to a workpiece, and having a second output applied to a torch, said power supply comprising:
- a current source for providing current in the forward direction for establishing an arc for a first predetermined length of time, and said current source providing current in the reverse direction for re-establishing said arc for a second predetermined length of time;
- a boost circuit for significantly increasing the open circuit voltage and the power applied between said workpiece and said torch by the power supply in response to a loss of said arc.
A variable polarity power supply, said power supply having a first output and a second output, said power supply having a current source for providing current in a first direction during a first predetermined period of time, and said current source of said power supply providing current in a second direction during a second period of time, said power supply comprising:
- a control circuit for controlling the polarity of the first and the second outputs of the power supply;
- a plurality of drivers connected to the control circuit;
- a switching circuit for switching polarity of the power supply so that the polarity of the first output is switched with the polarity of the second output, said polarity switching circuit being responsive to the drivers;
- a boost circuit for significantly increasing the open circuit voltage and the power applied between said first and second outputs by the power supply for a third period of time less than said second period of time in response to an increase in the voltage on said current source output.
A method for variable polarity arc welding by applying a variable, reversible voltage between a torch and a workpiece for providing current for a current source, said method comprising the steps of:
- first, applying a voltage between the torch and workpiece so that current flows between the torch and the workpiece;
- second, reversing the polarity of said voltage;
- third, substantially simultaneously with the second step, monitoring the absolute value of the voltage on said current source output;
- fourth, if the absolute value of said voltage rises above a selected level, increasing the open circuit voltage;
- and
- fifth, substantially simultaneously with increasing said open circuit voltage in said fourth step, limiting the current that can flow at that open circuit voltage so that the average reverse current is less than the average forward current, and the magnitude of the reverse current at any time will not be greater than the magnitude of the forward current at any time.
A variable polarity power supply, said power supply having a first output and a second output, said power supply having a current source for providing current in the forward direction and in the reverse direction, said power supply comprising:
- a switching circuit for switching polarity of the power supply so that the polarity of the first output is switched with the polarity of the second output;
- a circuit for controlling the switching circuit;
- a current limited boost circuit for significantly increasing the open circuit voltage of the power supply, said boost circuit being responsive to the voltage of said current source output;
- and
- means for limiting the current from said current limited boost circuit that can flow at the open circuit voltage so that the average reverse current is less than the average forward current, and the magnitude of the reverse current at any time will not be greater than the magnitude of the forward current at any time.
A method for variable polarity arc welding by applying a variable, reversible voltage between a torch and a workpiece for providing current for a current source, said method comprising the steps of:
- first, applying a voltage between the torch and workpiece so that current flows between the torch and the workpiece;
- second, reversing the polarity of said voltage;
- third, substantially simultaneously with the second step, monitoring the absolute value of the voltage on said current source output;
- and
- fourth, if the absolute value of said voltage rises above a selected level, significantly increasing the power applied between the torch and the workpiece by applying a DC voltage.
A variable polarity power supply for welding, said power supply having a first output applied to a workpiece, and having a second output applied to a torch, said power supply comprising:
- a current source for providing current in the forward direction for establishing an arc for a first predetermined length of time, and said current source providing current in the reverse direction for re-establishing said arc for a second predetermined length of time;
- a boost circuit for significantly increasing the power applied between said workpiece and said torch by applying a DC voltage in response to a loss of said arc.
Dependencies are inferred from the claim text.