Electric heating – Metal heating – By arc
Reexamination Certificate
2002-09-24
2004-04-06
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
By arc
C219S130510
Reexamination Certificate
active
06717108
ABSTRACT:
The present invention relates to the art of electric arc welding with a welder having a power supply of the switching type and more particularly to an electric arc welder of this type combined with a novel and unique method to design the waveforms used by the welder.
BACKGROUND OF INVENTION AND INCORPORATION BY REFERENCE
Electric arc welding involves the movement of an electrode toward a workpiece while current is passed through the electrode and across an arc between the electrode and workpiece. Although some electric arc welders utilize a non-consumable electrode, most of the mass production arc welding involves an electrode which is consumed during the welding process whereby the electrode is melted by the arc and deposited on the workpiece. Thus, an arc welding process includes variable process characteristics, such as wire speed or electrode speed, gas composition, electrode diameter and workpiece metal. The actual electrical arc welding process at the production site takes into consideration these characteristics and involves a non-linear complex control system which determines the applicable metal transfer mode and the electrical parameters of the power supply performing the welding process. In order to achieve desirable results, a waveform is selected having several control parameters, which waveform is customized for the exact condition of each welding application. Thus, controlling arc welding has become an art which demands substantial knowledge and experience to select a waveform having several control parameters to produce an optimum welding process. A large number of controllers have been developed for use with electric arc welders that have real time current waveforms developed by welding engineers to optimize the welding process performed in the field. To accomplish this objective, a microprocessor based controller has been developed and is now used that allows an operator in the field to select one of many welding waveforms by merely using one of several overlays. This successful microprocessor based controller is illustrated in Blankenship U.S. Pat. No. 5,278,390 that is incorporated by reference herein. By using a known template for the controller, an operator selects a welding waveform having the desired control parameters especially developed for the selected weld process by a skilled welding engineer. This successful controller had a certain amount of adjustability in the field; however, such on-site adjustments were limited. Mass production use of arc welders has created a demand for the ability to conveniently adjust certain control parameters of the welding waveform in the field, especially when the welding process conditions are different than what is used in designing standard waveforms shipped with the welders (such as cable length, shielding gas and welding wire). Thus, there was a need for a controller to be used with an electric arc welder, where the controller can process a desired waveform that is adjusted interactively at the manufacturing site so the waveform is optimized for welding conditions and welding requirements for the job.
To fill this need, an electric arc welder was developed with a microprocessor based controller for the specific arc welder. This welder is shown in Hsu U.S. Pat. No. 6,002,104 incorporated by reference herein. The welder has a switching type power supply for creating a welding cycle, with a real time current waveform constituting several control parameters by rapidly switching a D.C. current in a controlled fashion by a pulse width modulator and it will be described with respect to such switching type power supply. This prior patented controller was used with various switching type power supplies normally used in electric arc welders; however, the Hsu patent shows a down chopper power supply for simplicity. In practice, an inverter type power supply having a waveform controlled by a pulse width modulator was controlled in accordance with the present invention. The microprocessor based controller included means for displaying a waveform generated on an electrically operated waveform screen, such as a CRT. In this manner, the operator at the production site viewed the actual waveform to be processed by the electric arc welder under the direction of the patented controller. Interactive means were employed for manually adjusting at least a portion of the waveform displayed on the waveform screen to generate a new waveform operating on the waveform screen and having the desired control parameters. Consequently, a prebuilt waveform was first displayed on the CRT, normally in a graph exhibiting current versus time. To change one of the control parameters, such as background current, peak current, current ramp, etc., a manual adjustment of the prebuilt waveform was performed manually and interactively on the waveform screen. In this manner, a new current waveform was exhibited on the waveform CRT screen. In accordance with somewhat standard practice, before the patented arc welder the pulse width modulator of the power supply was controlled in accordance with the newly created current waveform to cause the power supply itself to generate a welding cycle with the real time waveform corresponding to the new waveform on the waveform screen. The welder power supply executed the new control parameters exhibited as control parameters in the new waveform. In this manner, a desired waveform was exhibited and used by the electric arc welder. If there was a need to change a control parameter of the exhibited waveform, the waveform itself was modified visually by the operator on site and then employed for control of the electric arc welder. This interactive changing of the waveform, as it was visually displayed on a waveform screen, was novel to the welding field and was implemented by including a JAVA virtual machine with a welder control application program or an applet running within a browser in JAVA language. The JAVA control program was dedicated to the specific electric arc welder combined with the controller. Thus, the consumer product was an electric arc welder having a power supply with a microprocessor based controller that was driven by a program in JAVA language. This concept was accomplished by using a JAVA virtual machine as part of the on site controller. This new electric arc welding was interactively manipulated to create a waveform for controlling the actual real time waveform of the welding process. The controller performed its functions through real time adjustment of the pulse width modulator used in the switching power supply driving the welder.
In a welder using the patented technology of Hsu U.S. Pat. No. 6,002,104 the welder has a microprocessor with a JAVA virtual machine and controlled by at least one control application program in JAVA language. The program was dedicated to the particular welder being controlled. The microprocessor system included hardware with a first interface for an interactive display screen and a second interface for a manual data entry device, such as mouse or keyboard, that was used interactively to change the waveform on the display screen preparatory to the waveform being implemented on a digital communication link (such as ethernet or infrared) for outputting control parameters to the welder. The same communication channel was used to input operating parameters from the welder. In this manner, the electric welder was controlled by manual manipulation of the actual waveform to be used in the welding process preparatory to implementation of the welding process. As changes are required, certain control parameters were adjusted on the display screen to merely change the shape of the waveform being displayed. When the operating parameters from the welder were inputted to the microprocessor of the controller, a separate “scope” application program in JAVA language was selected and implemented by the controller. In this manner, the CRT of the controller was converted from a waveform editor to an oscilloscope display for reading parameters from the welder and for displaying these param
Fay Sharpe Fagan Minnich & McKee LLP
Lincoln Global Inc.
Shaw Clifford C.
LandOfFree
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