Electric heating – Metal heating – By arc
Reexamination Certificate
1999-12-20
2003-01-28
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
By arc
C219S132000
Reexamination Certificate
active
06512199
ABSTRACT:
BACKGROUND—FIELD OF INVENTION
This invention relates to a compact, modular, constant current DC arc welding apparatus of the consumable electrode type (DC Stick and/or MIG) which is also capable of providing welding current for a non-consumable welding process (TIG) which is designed to be attached to, and to be directly or indirectly driven by, any suitable drive motor. Suitable drive motors include, but are not limited to, internal combustion engines, hydraulic motors, pneumatic motors, and electric motors. The modular welding apparatus of this invention generates welding current by means of a specially constructed high-current alternator, hereinafter referred to as a welding power generator, an electronic power control apparatus, and a remote operator control apparatus.
This invention produces a DC welding current with a pulsating high-frequency ripple component, hereafter referred to as high frequency DC welding current, which provides a number of improved technical welding characteristics. For example, this high frequency DC welding current can be transmitted over relatively long distances when compared to a pure DC current, with much less power loss due to the resistive and inductive effects of transmission cables, reducing the usual need to increase welding cable cross sectional size when using longer welding cables. This high frequency DC welding current also enables a weldor to produce very high quality welds, which show greater penetration into the workpiece for a given power setting when compared with prior art. The high frequency DC welding current also produces an exceptionally easy to start and easy to maintain welding arc which can be used successfully, without weld degradation, over a very wide range of arc to weld puddle lengths, including use with the electrode placed in direct contact with, or within, the weld puddle itself. Because of its ability to maintain a suitable welding arc with the electrode placed within a weld puddle, completely isolated from atmospheric and other external impurities, the high frequency DC welding current generated by the invention produces weld joints with less internal defects.
This invention's electronic power control apparatus works in conjunction with the invention's power generating apparatus to generate a very precisely controlled welding current output without the need for either precise control of drive motor speed, or a complicated electrical or mechanical power control system which relies on output power sensing or any sort of electrical or mechanical feedback. The invention's electronic power control apparatus also provides a means to control the electrical and operational characteristics of the aforementioned high frequency DC welding current.
The invention also incorporates a complete set of welder operation controls (i.e., power on/off, output amperage, arc starting, momentary power boost) which are integrated ergonomically into the invention's electrode holder, eliminating the need for a weldor/operator to leave a work location to make any adjustments to the welding power generating apparatus. A safety interlock is also included in the invention's control apparatus to provide additional weldor/operator safety.
The modular design of the invention's power generating apparatus and its electronic power control apparatus allow a plurality of individually operated, and independently controlled, compact, modular, constant current DC arc welding apparatuses to be attached to, and powered by, a single drive motor without any undesirable interaction between the individual components.
Further, the invention's compact, modular, welding power generator and its electronic power control apparatus also make it possible for a plurality of separate welding power generators to be attached to, and driven by, a single drive motor, with their welding current outputs connected in parallel, and with all of the interconnected welding power generators controlled by a single electronic power control apparatus without any undesirable interaction between the individual components. Thereby providing a means to generate, and to precisely control, very high welding currents (i.e., from 300 to over 800 amps.) with a very high degree of efficiency, and at a very low manufacturing cost, when compared with any prior art. For example, conventional motor-driven high-amperage welders must be very massively constructed to operate reliably and to provide a means to dissipate high internal heat generated while producing large welding currents. It is easy to see, therefore, the great advantage provided by the modular aspects of this invention, when compared to prior art.
This invention, because of its compact size and modular construction, is also universally retrofittable into any motor driven vehicle (i.e., tractors, automobiles, trucks, construction equipment, mowing equipment, nursery equipment, mining equipment, logging equipment, military equipment, all-terrain vehicles, amphibious vehicles, and water-craft), thereby creating a new class of welding equipment.
BACKGROUND—DESCRIPTION OF PRIOR ART
Electric arc welding requires a relatively high power current source. In the case of mobile and/or portable welders, this power source typically consists of a motor driving a DC generator or an alternator. Given the high weight, and expense of DC generators, most modern motor driven welding devices utilize an alternator as the power source. This power source must generate sufficient AC or DC current to melt welding electrodes that range from {fraction (1/16)} to {fraction (5/16)} inch in diameter and are 9 to 18 inches in length. The power source must also be able to provide sufficient voltage to start, and to maintain, an electrical welding arc. Normally the arc welding power source has two terminals. One terminal is connected via a flexible cable to the work piece to be welded, and the other is connected via a second flexible cable to an electrode holder. The electrode holder is an insulated metal clamp supported by an insulated handle which is gripped by the equipment operator.
Particularly with DC welders, the size and length of the flexible electrical cable used to connect the arc welding source to the workpiece and to the electrode holder is of critical importance, requiring larger and larger cable sizes as the distance from the welder to the workpiece increases. As cable size and/or length increases, equipment cost increases, utility of the equipment decreases, and workload placed on weldors operating the equipment increases.
Consumable electrodes are typically used with electric arc welding equipment.
Approximately one inch at one end of the welding electrode is bare metal to insure good electrical contact when it is gripped by an electrode holder clamp. The remainder of the electrode is coated with various chemical formulations (fluxing agents, arc stabilizers, metal powders, and other substances). These coatings exhibit little insulating effect and when a weldor grips an electrode and places it into the jaws of the electrode holder, the weldor is at considerable risk of electrical shock. Since a welding electrode is consumed in about three minutes, many electrode changes may be required to complete a job. Each change of electrode provides a risk of electrical shock. As time passes, a weldor's gloves to grow damp with perspiration, greatly decreasing any insulating effect that these gloves may provide. Weldors are, therefore, frequently shocked. On most occasions this shock is simply painful, but under the right circumstances, this shock may be fatal or disabling.
There have been a number of systems designed to better control a welding power source (as described, for example, in U.S. Pat. No. 4,216,368, and U.S. Pat. No. 5,864,117), but their technical deficiencies, and/or their high expense, have prevented their general acceptance and widespread use, particularly in lower-cost general purpose welding equipment. Further, none of these control systems have been particularly applicable to motor-driven welders desi
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