OPPOSED CURRENT FLOW MAGNETIC PULSE FORMING AND JOINING SYSTEM

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was not made as part of a federally sponsored research or development project.

REFERENCETO RELATED DOCUMENTS This application claims the benefit of a previous application filed in the United States

Patent and Trademark Office by HaipSng Shao and Peihul Zhang on February 18, 2005, titled "An Opposed Current Flow Magnetic Poise Forming and Joining System;" and given serial number I VQβUOl-

TECHNICAL FIELD

The present invention relates to the field of magnetic pulse technologies, namely magnetic pulse forming and magnetic pulse joining, including welding, and related systems and methods. The present invention is an opposed current flow magnetic pulse forming and joining system.

BACKGROUND OF THE FNVENTION

The use of magnetic pulse technologies in forming and joining components has been known for years. The widespread use of magnetic pulse forming and joining has been generally limited to use with tubular workpJcces of relatively simple geometries.

Traditionally, magnetic pulse forming and joining b&$ been accomplished through the use of a closed coil configured such that the parts to be formed or joined can be slid into and out of the coil. Such closed coils have not allowed the application of magnetic pulse technologies to workpieces having anything other than simple shapes.

To overcome the limitations inherent in closed coils, numerous split concentrators have been developed to provide additional flexibility to closed coil devices. Such split concentrator designs are found in U.S. Patents 3,486,356, 3,412,590, 3,391,558, and 3,252,313, just to name a few. Still, use of a split concentrator with a closed coil device does not provide the flexibility needed in many situations; after all the formed or welded workpiece must still be able to slide out of the coil.

Others have essentially cut a closed coil device in half so that it can be opened to insert and remove workpieces, yet still create a closed coil when the halves are brought together. Such configurations have been plagued by sparking along the interface between the two sections which leads to premature wear and failure of the coil. Yet another problem plaguing magnetic pulse technology systems has been the lack of control of the current as it passes through the sections. Prior art systems have failed to recognize the importance that the electrical characteristics of the entire system have on the current flow within the sections. A magnetic pulse technology power source may be tens of feet away from the actual forming or joining device. The power transmission systems responsible to transmitting hundreds of thousands of amperes at an electrical potential of thousands of volts are generally the source of several problems. Large power transmission circuits operating at the frequencies used in magnetic pulse forming and joining, generally tens of kHz, produce large inductance loads which negatively impact the operation. Reducing the inductance in magnetic pulse technology systems is very important for two reasons. First, high inductance in a magnetic pulse system has the effect of reducing the magnitude of the current, which consequently reduces the magnitude of the electromagnetic pulse force. Therefore, by reducing the inductance in a magnetic pulse system, the electromagnetic pulse force can be increased without making any changes to the magnetic

pulse power supply, thereby improving the forming or joining of the workpiece(s). Secondly, high inductance in a magnetic pulse system has the effect of reducing the current frequency in the system, which consequently increases the rise time of the magnetic pulse force, which is particularly important in magnetic pulse welding. Therefore, by reducing the inductance in a magnetic pulse system, particularly in the conductors, the rise time of the magnetic pulse force can be reduced, again, without making any changes to the magnetic pulse power supply. Prior magnetic pulse technology systems have not been designed with reduction of inductance of the conductors, and all the associated benefits, in mind. The present system addresses this need. The field of magnetic pulse forming and welding has needed a design in which multiple individual components can be easily configured around a workpiece in such a manner that each component constitutes a separate electrical circuit, yet when properly installed and operated, the individual components work together to produce the same effect as a single closed coil. While some of the prior art devices attempted to improve the state of the art, none has achieved the unique and novel configurations and capabilities of the present invention. With these capabilities taken into consideration, the instant invention addresses many of the shortcomings of the prior art and offers significant benefits heretofore unavailable.

SUMMARY OF INVENTION

In its most general configuration, the present invention advances the state of the art with a variety of new capabilities and overcomes many of the shortcomings of prior methods in new and novel ways. In its most general sense, the present invention overcomes the

shortcomings and limitations of the prior art in any of a number of generally effective configurations.

The present invention includes several systems and methods for performing magnetic pulse forming and joining with improved quality, reliability, and dramatically less losses due to inductance in the conductors. In one of the many preferable configurations, the opposed current flow magnetic pulse forming and joining system of the present invention is in electrical communication with a magnetic pulse power supply having a positive connection and a negative connection. The system may be used in forming an individual workpiece or joining multiple workpieces. The system generally comprises a first section, a second section, an insulator, and a. first and a second pair of conductors. During operation, the first and second sections cooperate to enclose the workpiece, or workpieces, that is to be formed or joined by an electromagnetic force generated by current flowing through the sections. The system is configured so that the first pair of conductors and the second pair of conductors complete a first electrical circuit between the first section and the magnetic pulse power supply and a second electrical circuit between the second section and the magnetic pulse power supply.

The system is configured to achieve desirable current flow throughout the system by minimizing the inductance in the conductors. The desired current flow is through the first section in a direction opposite the current flowing through the second section, while the current flows in opposite directions in each conductor of each pair of conductors. This current flow permits the first and second sections to function as if a single magnetic pulse coil, and the opposed current in the individual conductor pairs greatly reduces inductance in the conductors, affording several benefits not previously found in magnetic pulse systems.

Numerous variations, modifications, alternatives, and alterations of the various preferred embodiments, processes, and methods may be used alone or in combination with one another as will become more readily apparent to those with skill in the art with reference to the following detailed description of the preferred embodiments and the accompanying figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Without limiting the scope of the present invention as claimed below and referring now to the drawings and figures: FIG. 1 shows a schematic of one embodiment of the system of the present invention, not to scale;

FIG. 2 shows a front elevation view of one embodiment of a portion of the system of the present invention in the operational position, not to scale;

FIG. 3 shows a front elevation view of one embodiment of a portion of the system of the present invention in an open position, not to scale;

FIG. 4 shows a front elevation view of one embodiment of a portion of the system of the present invention in the operational position, not to scale;

FIG. 5 shows a front elevation view of one embodiment of a portion of the system of the present invention in the operational position, not to scale; FIG. 6 shows a front elevation view of one embodiment of a portion of the system of the present invention in the operational position, not to scale;

FIG. 7 shows a schematic of one embodiment of the system of the present invention, not to scale;

FIG. 8 shows a schematic of one embodiment of the system of the present invention, not to scale;

FIG. 9 shows a schematic of one embodiment of the system of the present invention, not to scale; FIG. 10 shows a schematic of one embodiment of the system of the present invention, not to scale;

FIG. 11 shows a schematic of one embodiment of the system of the present invention, not to scale;

FIG. 12 shows a schematic of one embodiment of the system of the present invention, not to scale;

FIG. 13 shows a schematic of one embodiment of the system of the present invention, not to scale;

FIG. 14 shows a schematic of one embodiment of the system of the present invention, not to scale; FIG. 15 shows a front elevation view of one embodiment of a portion of the system of the present invention in an open position, not to scale; and

FIG. 16 shows a schematic of one embodiment of the system of the present invention, not to scale.

DETAILED DESCRIPTION OF THE INVENTION

The opposed current flow magnetic pulse forming and joining system (10) of the present invention enables a significant advance in the state of the art. The preferred embodiments of the method and system accomplish this by new and novel methods that are configured in unique and novel ways and which demonstrate previously unavailable but

preferred and desirable capabilities. The description set forth below in connection with the drawings is intended merely as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention.

The present invention includes several systems and methods for performing magnetic pulse forming and joining with improved quality, reliability, and dramatically less losses due to inductance in the conductors. The opposed current flow magnetic pulse forming and joining system (10) is in electrical communication with a magnetic pulse power supply (20) having a positive connection (22) and a negative connection (24), as would be understood by those with skill in the art. The system (10) may be used in forming an individual workpiece or joiaing multiple workpieces.

The system (10) generally comprises a first section (100), a second section (200), an insulator (300), and a first and a second pair of conductors (400, 500), as seen in FIG. 1 in an operational position (600). The system (10) is configured so that the first pair of conductors (400) and the second pair of conductors (500) complete a first electrical circuit between the first section (100) and the magnetic pulse power supply (20) and a second electrical circuit between the second section (200) and the magnetic pulse power supply (20). Further, the system (10) is configured to achieve desirable current flow throughout the system (10) by rrώώmzing the inductance in the conductors. Such desirable current flow is characterized by current flowing through the first section (100) in a direction opposite the current flowing at

the second section (200), and the current flowing in opposite directions in each conductor of the first pair of conductors (400), and similarly, current flowing in opposite directions in each conductor of the second pair of conductors (500), as will be described in detail later herein. The desirable current flow permits the first and second sections (100, 200) to function as if a single magnetic pulse coil. The opposed current in the individual conductor pairs (400, 500) greatly reduces inductance in the conductors, affording several benefits not previously found in magnetic pulse systems. Additionally, the use of multiple sections increases the life of the system.

Now, a detailed description of each of the elements will begin with the first and second sections (100, 200). As seen in FIGS. 2 and 3, the first section (100) has a first section working face (110) with a first workpiece recess section (112), a positive first section connector (120), and a negative first section connector (130). Similarly, the second section (200) has a second section working face (210) with a second workpiece recess section (212), a positive second section connector (220), and a negative second section connector (230). The first and second section working faces (110, 210) are referred to as the working faces because these are the surfaces to which it is desirable to direct current passing through each section to achieve a predetermined electromagnetic force. The first working face (110) has a first workpiece recess section (112) and the second working face (210) has a second workpiece recess section (212). When the sections (100, 200) are brought into the operational position (600) the first workpiece recess section (112) is generally adjacent to the second workpiece recess section (212) so as to create a void where the workpiece, or workpieces, labeled (WP) in FIG. 15, to be formed or joined reside. The recess sections (112, 212) may be shaped to generally conform to the shape of the workpiece, or workpieces, to be formed or joined, or they may be shaped to create a common shape such as a circular recess so that

various magnetic pulse field shapers, or concentrators, may be used. The sections (100, 200) are held together during forming and joining by a force system, often a clamping system, capable of withstanding the reaction of the electromagnetic force.

As one with skill in the art will appreciate, the positive first section connector (120), negative first section connection (130), positive second section connector (220), and negative second section connector (230) may be either formed as an integral part of the respective sections (100, 200), as seen in FIG. 2, or may be individual parts attached to the respective sections (100, 200), as seen in FIG. 15. Further, the connectors (120, 130, 220, 230) may be little more than a solder joint between the conductors (430, 440, 530, 540) and the sections (100, 200), as schematically illustrated in FIGS. 1 and 7, or may be as simple as lugs to facilitate connecting the conductors (430, 440, 530, 540) to the sections (100, 200), as schematically illustrated in FIGS. 2-6. In one particular embodiment the positive first section connector (120) and the negative first section connector (130) are in contact with a portion of the first section working face (i 10) and the positive second section connector (220) and the negative second section connector (230) are in contact with a portion of the second section working face (210). Such positioning of the section connectors (120, 130, 220, 230) in contact with the working faces (110, 210) ensures that the current enters each section (100, 200) at the working face (110, 210) and leaves each section (100, 200) at the working face (110, 210). The location of the ingress and egress of the current from the sections (100, 200), as well as the strategic direction of current travel and position of the conductors, is largely determinative of the current path through the sections (100, 200) which affects the magnitude of the electromagnetic force.

The present invention is unique in that it recognizes and takes advantage of electrical principles to maximize the amount of current traveling through the sections (100, 200) either

at or near the working faces (110, 210). One with skill in the art will recognize that current always flows along a path of minimum impedance and that the impedance of the present system (10), with the exception of the power supply (20), may be represented by the following equation:

Z = R + jωL -j ωC

In the above equation, Z is impedance, R is resistance, coL is the inductive reactance, and l/(ωC) is the capacitive reactance. Conventional magnetic pulse joining systems have only looked to optimize the coil, or the elements that make up a split coil, rather than look at the magnetic pulse joining system as a whole. Given this narrow view, the inductive reactance and the capacitive reactance have been ignored and the impedance is simply

i represented by the resistance. This narrow view leads one to falsely believe that the current will automatically travel through the sections (100, 200) at or near the working faces (110, 210), rather than along the opposite perimeter of the sections (100, 200), because it is the path of least resistance. The present inventors discovered that such a narrow view is inappropriate because the current does not naturally travel along the working faces (110, 210) in. conventional systems, thereby dramatically reducing the effectiveness of the system.

The present inventors realized that while capacitive reactance may be ignored, inductive reactance may not be ignored. For instance, if the sections (100, 200) of FIG. 2 were simply connected to the magnetic pulse power supply (20) with individual conductors paying no attention to the current flow in the conductors nor the position of the conductors with respect to one another, then the current flow through the sections (100, 200) would not be near the working faces (110, 210), but rather along the outer perimeter. For example, FIG. 16 represents one half of a conventional split component magnetic pulse joining system. In such configurations the inductive reactance in the electrical loop designated by nodes g-a-b-c-

d-h is higher than the inductive reactance of the electrical loop designated by nodes g-a-f-e-d- h, while the resistance of the g-a-b-c-d-h loop is lower than the resistance of the g-a-f-e-d-h loop. The higher inductive reactance more than offsets the lower resistance resulting in the total impedance (Z) of the g-a-b-c-d-h loop being higher than the impedance of the g-a-f-e-d- h loop. Therefore the current travels along the g-a-f-e-d-h loop, which is not the desired path. The present inventors have numerically modeled this system and the model confirms the g-a- f-e-d-h current path.

, The present invention introduces a unique relationship between the direction of current travel in the conductors and the proximity of certain conductors with respect to one another such that the current travels along the working faces of the sections, represented by nodes a-b-c-d in FIG. 16, rather along the opposite perimeter of the sections, represented by nodes a-f-e-d in FIG. 16. Such realization of the importance of the inductive reactance in magnetic pulse joining systems allows capabilities that were previously unobtainable. The selective configuration of the conductors as well as the direction of current travel in the conductors claimed in the present invention reduces the inductance, and therefore the inductive reactance, in the system such that the path of minimum impedance is along the working faces (110, 210).

While the very nature of the present invention ensures that majority of the current passing through the sections is at, or near, the working faces (110, 210), additional embodiments seen in FIGS. 4-6 may further direct stray current within the individual sections (100, 200). The first section (100) may include at least one first section current path control device (140) and the second section (200) may include at least one second section current patib. control device (240) to direct stray current in a manner preferential to forming and joining, as seen in FIG. 4. The preferential current path may be different in different

applications, but generally it is preferential to direct the current as close to the working faces (110, 210) as possible. The current path control devices (140, 240) may take any number of forms but may be an insulating barrier. Such insulating barriers (142, 242) are illustrated in FIG. 5 and generally extend toward the working faces (110, 210), but stop just short of the face (110, 210) so that the stray current must pass between the insulating barriers (142, 242) and working faces (110, 210). In a preferred embodiment shown in FIG. 6, the first insulating barrier (142) comprises a first ingress barrier (144) and a first egress barrier (146) wherein the first ingress barrier (144) directs current to the portion of the first section working face (110) between the positive first section connector (120) and the first workpiece recess section (112) and the first egress barrier (146) directs current to the portion of the first section working face (110) between the first workpiece recess section (112) and the negative first section connector (130). Similarly, in this embodiment, the second insulating barrier (242) comprises a second ingress barrier (244) and a second egress barrier (246) wherein the second ingress barrier (244) directs stray current to the portion of the second section working face (210) between the positive second section connector (220) and the second workpiece recess section (212) and the second egress barrier (246) directs current to the portion of the second section working face (210) between the second workpiece recess section (212) and the negative second section connector (230).

The selection of the materials of construction of the sections (100, 200), connectors (120, 130, 220, 230), and current path control devices (140, 240) is within the capability of one with skill in the art. Obviously, the sections (100, 200) and the connectors (120, 130, 220, 230) must be electrically conductive and strong enough to withstand the reaction forces associated with creating the desired electromagnetic force. Alternatively, the current path

control devices (140, 240) must not be electrically conductive in order to direct the stray current path within the sections (100, 200).

Referring again to FIG. 2, in the operational position (600) the insulator (300) is in contact with a portion of the first section working face (110) and the second section working face (210). The insulator (300) blocks current flow between the first section (100) and the second section (200). The insulator (300) is not permanently attached to either section (100, 200), but may be attached in one of the embodiments to reduce the number of loose elements during the ingress and egress of the workpiece(s). Additionally, the insulator (300) may be a single element or it may be composed of multiple sections, as illustrated in FIG. 15. The system (10) includes two pairs of conductors (400, 500), each pair having a conductor A (430, 530) and a conductor B (440, 540), as seen in FIG. 7. As will be explained herein, the individual A conductors (430, 530) are be placed in close proximity to their associated individual B conductor (440, 540), which may include the conductors being a twisted pair, or braided, or coaxial. The first pair of conductors (400) has a first distal end (410) and a first proximal end (420) and has its first conductor A (430) in close proximity to the first conductor B (440). The first distal end (410) is in electrical communication with the magnetic pulse power supply (20) and the first proximal end (420) is in electrical communication with the first section (100) and the second section (200). Similarly, the second pair of conductors (500) has a second distal end (510) and a second proximal end (520) and has its second conductor A (530) in close proximity to the second conductor B (540). The second distal end (510) is in electrical communication with the magnetic pulse power supply (20) and the second proximal end (520) in electrical communication with the first section (100) and the second section (200).

The close proximity of the first conductor A (430) to the first conductor B (440), as well as the close proximity of the second conductor A (530) to the second conductor B (540), combined with the opposed current flow relationship between the A conductors (430, 530) and the B conductors (440, 540) reduces the inductance in the conductors, and therefore the inductive reactance and impedance as previously described. In addition to the reasons set forth above, reducing the inductance in magnetic pulse technology systems is very important for two reasons. First, high inductance in the conductors of a magnetic pulse system has the effect of reducing the magnitude of the current, which consequently reduces the magnitude of the magnetic pulse force. Therefore, by reducing the inductance in the conductors, the electromagnetic pulse force can be increased without making any changes to the magnetic pulse power supply (20), thereby improving the forming or joining of the workpiece(s). Secondly, high inductance in the conductors has the effect of reducing the current frequency in the system which consequently increases the rise time of the electromagnetic force. Therefore, by reducing the inductance in a magnetic pulse system, particularly in the conductors, the magnitude of the current is increased and the rise time of the electromagnetic force can be reduced without making any changes to the magnetic pulse power supply (20), ' thereby improving the forming or joining of the workpiece(s).

With reference now to FIG. 7, when the system (10) is in a operational position (600) with the first section working face (110) substantially parallel with the second section working face (210) and a portion of each working face (110, 210) is in contact with the insulator (300), the first pair of conductors (400) and the second pair of conductors (500) are configured to complete a first electrical circuit between the first section (100) and the magnetic pulse power supply (20) and a second electrical circuit between the second section (200) and the magnetic pulse power supply (20). This configuration ensures that the current

flowing at the first section working face (110) is in a direction opposite the current flowing at the second section working face (210), and the current flowing in the first conductor A (430) is in a direction opposite the current flowing in the first conductor B (440) and the current flowing in the second conductor A (530) is in a direction opposite the current flowing in the second conductor B (540), as shown by the flow arrows in the figures indicating the direction of the current travel.

Four illustrative embodiments of the above configuration are found in FIGS. 7-11. In the first illustrative embodiment, seen in FIG. 7, (a) the first conductor A (430) is in electrical communication with the positive first section connector (120) and the magnetic pulse power supply positive connection (22), (b) the first conductor B (440) is in electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24), (c) the second conductor A (530) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22), and (d) the second conductor B (540) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24). In all of these four illustrative embodiments of FIGS. 7-10 the operational position the positive first section connector (120) is adjacent to the negative second section connector (230) and is separated therefrom by a portion of the insulator (300) and the positive second section connector (220) is adjacent to the negative first section connector (130) and is separated therefrom by a portion of the insulator (300). In this first illustrative embodiment of FIG. 7 ₅ the current traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the first conductor A (430), passes through the first section (100), and returns to the magnetic pulse power (20) supply through the second conductor B (540) and current traverses from the magnetic pulse power supply (20) to the positive second

section connector (220) through the second conductor A (530), passes through the second section (200), and returns to the magnetic pulse power supply (20) through the first conductor B (440). Therefore, the current flowing at the first section working face (110) is in a direction opposite the current flowing at the second section working face (210), the current flowing through the first conductor A (430) is in the opposite direction of the current flowing through the first conductor B (440), and the current flowing through the second conductor A (530) is in the opposite direction of the current flowing through the second conductor B (540) to minimize the inductance in the conductors, as is also true in the embodiments of FIGS. 8-10. In the second illustrative embodiment, seen in FIG. 8, (a) the first conductor A (430) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24), (b) the first conductor B (440) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22), (c) the second conductor A (530) is in electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24), and (d) the second conductor B (540) is in electrical communication with the positive first section connector (120) and the magnetic pulse power supply positive connection (22). In this second illustrative embodiment, current traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the second conductor B (540), passes through the first section (100), and returns to the magnetic pulse power supply (20) through the first conductor A (430) and current traverses from the magnetic pulse power supply (20) to the positive second section connector (220) through the first conductor B (530), passes through the second section (200), and returns to the magnetic pulse power supply (20) through the second conductor A (530).

In the third illustrative embodiment, seen in FIG. 9, (a) the first conductor A (430) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22), (b) the first conductor B (440) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24), (c) the second conductor A (530) is in electrical communication with the positive first section connector (120) and the magnetic pulse power supply positive connection (22), and (d) the second conductor B (540) is in electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24). In this third illustrative embodiment, current traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the second conductor A (530), passes through the first section (100), and returns to the magnetic pulse power supply (20) through the first conductor B (440) and current traverses from the magnetic pulse power supply (20) to the positive second section connector (220) through the first conductor A (430), passes through the second section (200), and returns to the magnetic pulse power supply (20) through the second conductor B (540).

In the fourth and final illustrative embodiment, as seen in FIG. 10, (a) the first conductor A (430) is in electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24), (b) the first conductor B (440) is in electrical communication with the positive first section connector (120) and the magnetic pulse power supply positive connection (22), (c) the second conductor A (530) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24), and (d) the second conductor B (540) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22). In this fourth illustrative embodiment, current

traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the first conductor B (440), passes through the first section (100), and returns to the magnetic pulse power supply (20) through the second conductor A (530) and current traverses from the magnetic pulse power supply (20) to the positive second section connector (220) through the second conductor B (540), passes through the second section (200), and returns to the magnetic pulse power supply (20) through the first conductor A (430).

The inductance associated with the conductors (430, 440, 530, 540) is reduced the closer the opposed current flow inductors (430 & 440, 530 & 540) are to one another. Therefore, in one particular embodiment the first conductor A (430) is within approximately one inch of the first conductor B (440) throughout substantially the length from the first distal end (410) to the first proximal end (420), and the second conductor A (530) is within approximately one inch of the second conductor B (540) throughout substantially the length from the second distal end (510) to the second proximal end (520). hi a further embodiment the first conductor A (430) is substantially in contact with the first conductor B (440) throughout substantially the length from the first distal end (410) to the first proximal end (420), and the second conductor A (530) is substantially in contact with the second conductor B (540) throughout substantially the length from the second distal end (510) to the second proximal end (520). In this particular embodiment the A conductors (430, 530) may not be in contact with the B conductors (440, 540) near the distal (410, 510) and proximal ends (420, 520) to allow for connection to the sections (100, 200) and the power supply (20). As one with skill in the art will recognize, the first (400) and second (500) pair of conductors may be what are commonly referred to as braided conductors, or cables. Further, one skilled in the art will recognize that the figures are schematic in nature and that distances from the distal ends (410, 510) to the proximal ends (420, 520) may be many tens of feet, while the distance that

the conductors (430, 440, 530, 540) separate to facilitate connection to the magnetic pulse power supply positive and negative connections (22, 24), or to the respective sections (100, 200), will be the absolute minimum necessary to make the connections, generally less than two feet. Additionally, one skilled in the art will understand that the conductors may include an exterior protection sheath, and therefore reference to the conductors being in contact may mean that the exterior protective sheathes are in contact.

In. yet a further variation of the conductors (400, 500), the first pair of conductors (400) is a first coaxial conductor (450) and the second pair of conductors (500) is a second coaxial conductor (550), as seen in FIGS. 11-14. In the first coaxial conductor (450) the first conductor A (430) is a first interior conductor (452) and the first conductor B (440) is a first exterior conductor (454). Similarly, in the second coaxial conductor (550) the second conductor A (530) is a second interior conductor (552) and the second conductor B (540) is a second exterior conductor (554). Consistent with previous embodiments, the current flowing in the first interior conductor (452) is in a direction opposite the current flowing in the first exterior conductor (454) and the current flowing in the second interior conductor (552) is in a direction opposite the current flowing in the second exterior conductor (554) to minimize the inductance in the conductors. Therefore, in this embodiment, not only are the opposed current flow conductors (452 & 454, 552 & 554) in close proximity to one another throughout most of the length from the distal end (410, 510) to the proximal end (420, 520), the exterior conductor (454, 554) surrounds the interior conductor (452, 552), thereby further reducing the inductance in the conductors and eliminating the tendency of separate individual conductors to "jump" or repel one another due to their creation of electromagnetic fields. In essence, the coaxial conductors (450, 550) are self-constrained. Further, as previously explained, the opposed current flow in the first section working face (110) and the second

section working face (210) serves to produce an electromagnetic force similar to that of a single closed coil and the opposed current flow in the individual conductors (452, 454, 552, 554) of the first and second coaxial conductors (450, 550) reduces the inductance in the system (10) attributable to the conductors (450, 550). Four illustrative coaxial embodiments are found in FIGS. 11-14, similar to the four illustrative embodiments previously described regarding non-coaxial embodiments. In the first illustrative embodiment, seen in FIG. 11, (a) the first interior conductor (452) is in electrical communication with the positive first section connector (120) and the magnetic pulse power supply positive connection (22), (b) the first exterior conductor (454) is in electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24), (c) the second interior conductor (552) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22), and (d) the second exterior conductor (454) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24). In each of the embodiments illustrated in FIGS. 11-14 the positive first section connector (120) is adjacent to the negative second section connector (230) and is separated therefrom by a portion of the insulator (300), and the positive second section connector (220) is adjacent to the negative first section connector (130) and is separated therefrom by a portion of the insulator (300). In this embodiment current traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the first interior conductor (452), passes through the first section (100), and returns to the magnetic pulse power supply (20) through the second exterior conductor (554), and current traverses from the magnetic pulse power supply (20) to the positive second section connector (220) through the second interior conductor (552), passes

through the second section (200), and returns to the magnetic pulse power supply (20) through the first exterior conductor (454). Therefore, in this embodiment, and all of those of FIGS. 11-14, the current flowing at the first section working face (110) is in a direction opposite the current flowing at the second section working face (220), the current flowing through the first interior conductor (452) is in the opposite direction of the current flowing through the first exterior conductor (454), and the current flowing through the second interior conductor (552) is in the opposite direction of the current flowing through the second exterior conductor (554) to minimize the inductance in the conductors.

In the second illustrative embodiment, seen in FIG. 12, (a) the first interior conductor (452) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24), (b) the first exterior conductor (454) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22), (c) the second interior conductor (552) is in. electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24), and (d) the second exterior conductor (554) is in electrical communication with the positive first section connector (120) and the magnetic pulse power supply positive connection (22). In this embodiment current traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the second exterior conductor (554), passes through the first section (100), and returns to the magnetic pulse power supply (20) through the first interior conductor (452), and current traverses from the magnetic pulse power supply (20) to the positive second section connector (220) through the first exterior conductor (454), passes through the second section (200), and returns to the magnetic pulse power supply (20) through the second interior conductor (552).

In the third illustrative embodiment, seen in FIG. 13, (a) the first interior conductor (452) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22), (b) the first exterior conductor (454) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24), (c) the second interior conductor (552) is in electrical communication with the positive first section connector (120) and the magnetic pulse power supply positive connection (22), and (d) the second exterior conductor (554) is in electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24). In this embodiment the current traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the second interior conductor (552), passes through the first section (100), and returns to the magnetic pulse power supply (20) through the first exterior conductor (454), and current traverses from the magnetic pulse power supply (20) to the positive second section connector (220) through the first interior conductor (452), passes through the second section (200), and returns to the magnetic pulse power supply (20) through the second exterior conductor (554). In the fourth illustrative embodiment, seen in FIG. 14, (a) the first interior conductor (452) is in electrical communication with the negative second section connector (230) and the magnetic pulse power supply negative connection (24), (b) the first exterior conductor (454) is in electrical communication with the positive first section connector (130) and the magnetic pulse power supply positive connection (22), (c) the second interior conductor (552) is in electrical communication with the negative first section connector (130) and the magnetic pulse power supply negative connection (24), and (d) the second exterior conductor (554) is in electrical communication with the positive second section connector (220) and the magnetic pulse power supply positive connection (22). In this embodiment the current

traverses from the magnetic pulse power supply (20) to the positive first section connector (120) through the first exterior conductor (454), passes through the first section (100), and returns to the magnetic pulse power supply (20) through the second interior conductor (552), and the current traverses from the magnetic pulse power supply (20) to the positive second section connector (220) through the second exterior conductor (554), passes through the second section (200), and returns to the magnetic pulse power supply (20) through the first interior conductor (452).

The magnetic pulse power supply (20) of the present invention is well known to those with skill in the art. Magnetic pulse power supplies generally include a plurality of high- capacity capacitors and the requisite charging and control circuitry to generate and control the discharge of large quantities of current at high electrical potential for a very short duration. While the description herein refers to a single magnetic pulse power supply (20), one with skill in the art will recognize that each section (100, 200) may have its own magnetic pulse power supply provided they are simultaneously controlled. One with skill in the art will recognize that in yet a further embodiment the first section (100) and the second section (200) may incorporate, or be constructed of, actual electromagnetic coils. The sections (100, 200) may be multiple-turn or single-turn coils.

Numerous alterations, modifications, and variations of the preferred embodiments disclosed herein will be apparent to those skilled in the art and they are all anticipated and contemplated to be within the spirit and scope of the instant invention. For instance, while the disclosure herein always refers to two sections, one with skill in the art will appreciate that this invention may be constructed with more than two sections and the same principles regarding reduction in inductance due to the conductors apply. Additionally, given the large quantity of current required to perform magnetic pulse forming and joining, one with skill in

the art will recognize that the present invention anticipates using more than just two pairs of conductors. In fact the present inventors' experimentation has included as many as six coaxial conductors. Generally, the inductance and resistance attributable to the conductors tends to decrease as the number of conductors increases. Additionally, while magnetic pulse forming and joining are referred to herein, one with skill in the art will recognize that the present invention may also be used in magnetic pulse cutting and all types of magnetic pulse metal working. Further, although specific embodiments have been described in detail, those with skill in the art will understand that the preceding embodiments and variations can be modified to incorporate various types of substitute and or additional or alternative materials, relative arrangement of elements, and dimensional configurations. Accordingly, even though only few variations of the present invention are described herein, it is to be understood that the practice of such additional modifications and variations and the equivalents thereof, are within the spirit and scope of the invention as defined in the following claims. The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or acts for performing the functions in combination with other claimed elements as specifically claimed.

INDUSTMAL APPLICABILITY

The opposed current flow low-inductance magnetic pulse forming and welding system answers a long felt need for pulse forming and joining with improved quality, reliability, and dramatically less losses due to inductance in the conductors. The system, may be used in forming individual workpieces or joining multiple workpieces, including joining by magnetic pulse welding. The system includes a first section, a second section, an insulator, and a first and second pair of conductors. The system is configured to achieve desirable current flow by minimizing inductance, inductive reactance, and impedance in the conductors.