Open coil EMP apparatus

Abstract

An EMP apparatus includes first and second opposed field shaper segments. The field shaper segments include opposed working portions. First and second coil segments respectively support the first and second opposed field shaper segments. The coil segments are electrically operable and in eddy current contact with the field shaper segments. Insulators are disposed between the field shaper segments and the coil segments. A frame moveably supports the coil segments for movement between open and closed positions of the coil segments. Metal stock can be disposed between the shaper segment working portions by opening the shaper and coil segments.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional Application No. 60/926,262 filed Apr. 26, 2007.

TECHNICAL FIELD

This invention relates to compression, crimping, and welding of metal tubes using an electromagnetic pulse.

BACKGROUND OF THE INVENTION

It is known in the art relating to crimping and welding to use conventional electromagnetic force apparatuses. Conventional electromagnetic coils, however, do not accommodate metal tubes having no open end or having a complex geometry.

SUMMARY OF THE INVENTION

The present invention provides for the compression, crimping, and welding of metal tubes using pulses of electromagnetic force, and more particularly to crimping and welding of metal tubes that have no open end or a complex geometry that is not accommodated by conventional electromagnetic coils.

More particularly, an open coil electromagnetic pulse (“EMP”) apparatus in accordance with the invention includes first and second opposed field shaper segments. The field shaper segments include opposed working portions. First and second coil segments respectively support the first and second opposed field shaper segments. The coil segments are electrically operable and in eddy current contact with the field shaper segments, i.e., the coil segments are not in direct electrical contact with the field shaper segments, but “connected” electrically through eddy currents. Insulators are disposed between the field shaper segments and the coil segments. A frame moveably supports the coil segments for movement between open and closed positions of the coil segments. Metal stock can be disposed between the shaper segment working portions by opening the shaper and coil segments.

In one embodiment, the frame may be a clamp and may be hinged. The coil segments may be arranged in a clamshell configuration. The coil segments may have opposed curvilinear recesses and the field shaper segments may have corresponding curvilinear protrusions.

The field shaper segments may be disposed to open and close with movement of the coil segments. The field shaper segments may be disposed in a perpendicular disposition to an open and closing direction of the coil segments. A strap may be mounted on at least one of the coil segments to secure the field shaper segments in the coil segments.

A method of working a metal tube segment includes the steps of providing an EMP apparatus including first and second opposed field shaper segments, the field shaper segments including opposed working portions, first and second coil segments respectively supporting the first and second opposed field shaper segments, the coil segments being electrically operable and in eddy current contact with the field shaper segments, insulators disposed between the shaper segments and the coil segments, and a frame moveably supporting the coil segments for movement between open and closed positions of the coil segments; disposing a metal tube between the shaper segment working portions by opening the shaper and coil segments; moving the frame to move the coil segments into the closed position; applying a pulse of electric current through the coil segments to work the metal tube; and removing the metal tube by opening the shaper and coil segments.

In one embodiment, the method may also include the step of clamping the coil segments to secure the coil segments in the closed position. The frame may include a hinge for moving the coil segments between the open and closed positions. The field shaper segments may open and close with movement of the coil segments.

The method may also include the step of disposing the field shaper segments in a perpendicular disposition to an open and closing direction of the coil segments. The method may further include the step of mounting a strap on at least one of the coil segments to secure the field shaper segments in the coil segments.

These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a side view of an open coil electromagnetic pulse apparatus in accordance with the invention;

FIG. 2A is a cross-sectional view of the open coil electromagnetic pulse apparatus taken along the line 2A-2A in FIG. 1 illustrating a metal tube workpiece prior to an electromagnetic pulse;

FIG. 2B is a schematic, cross-sectional view similar to FIG. 2A illustrating compression and deformation of the metal tube after an electromagnetic pulse;

FIG. 3 is a side view of an alternative embodiment of an open coil electromagnetic pulse apparatus in accordance with the invention;

FIG. 4 is a schematic view of primary and induced currents in coil segments, field shapers, and metal tube of FIG. 1;

FIGS. 5A and 5B are schematic views of electromagnetic crimping or welding using the electromagnetic pulse apparatus of the present invention; and

FIG. 6 is an environmental view of the electromagnetic pulse apparatus working on metal stock.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail, numeral 10 generally indicates an open coil EMP apparatus in accordance with the invention. The open coil EMP apparatus 10 provides for electromagnetic pulse crimping and welding of metal workpieces that have no open end or a complex geometry, for example a tubular ring, a bicycle frame, a motorcycle frame, a automobile frame, or similar.

With reference to FIGS. 1, 2A, 2B, 4, and 6, in accordance with a first embodiment an open coil EMP apparatus 10 includes two coil segments 12, 14 forming an open coil, and two field shaper segments 16, 18. The coil segments 12, 14 may be in a contact position (a “closed position”) as shown in FIG. 1 or may be separated from each other (an “open position”) to allow for insertion of a workpiece (e.g., metal stock) into the open coil as described in more detail below. The coil segments 12, 14 also may be connected at one end by a hinge 20 to allow for pivotal movement of the coil segments between the closed, contact position and the open, separated position. In the closed position, a contact surface 22 of the coil segment 12 and a contact surface 24 of the coil segment 14 contact each other, allowing for flow of current between the coil segments as described in more detail below. Further, in the closed position, a non-contact surface 23 of coil segment 14 and a non-contact surface 25 of coil segment 16 are spaced from each other. The coil segments 12, 14 also include opposed curvilinear recesses 26, 28, and in the closed position the curvilinear recesses of the coil segments define a cavity within the coil segments.

A frame 30 moveably supports the coil segments 12, 14 for movement between the open and closed positions. The frame 30 may be a clamp that secures the coil segments 12, 14 in the closed position and prevents the coil segments from moving or separating when the coils are actuated as described below.

The field shaper segments 16, 18 are supported by the coil segments 12, 14 and are generally disposed in the cavity defined by the coil segments. The field shaper segments 16, 18 may be disposed so as to open and close with the movement of the coil segments 12, 14. The field shaper segments 16, 18 have curvilinear protrusions 32, 34 that correspond to the curvilinear recesses 22, 24 of the coil segments 12, 14, respectively. An insulator 36 is disposed between the field shaper segments 16, 18 and the coil segments 12, 14. The insulator 36 may be a thin layer of kapton tape, a non-conductive polymer, or similar. Field shaper segment 16 does not contact field shaper segment 18. An insulator 38 such as a thin layer of kapton tape, non-conductive polymer or similar may be disposed between field shaper segment 16 and field shaper segment 18. Similarly, an insulator 39 such as a thin layer of kapton tape, non-conductive polymer or similar may be disposed between the non-contact surfaces 23, 25 of the coil segments 12, 14.

The field shaper segments 16, 18 define an opening 40 that extends through the field shaper segments. The opening 40 may be cylindrical/tubular in shape and is sized in such a way to be adapted to receive a metal workpiece 42 such as a tubular metal workpiece or other metal stock therethrough. To insert the metal tube 42 in the apparatus, the coil segments 12, 14 may be separated from each other, the metal tube may be placed between the field shaper segments 16, 18, and then the coil segments may be returned to the closed position. When the metal tube 42 is placed in the opening 40, it is ready to be crimped or welded by the open coil apparatus 10. Further, in the closed position a strap 43 may be mounted on at least one of the coil segments 12, 14 to secure the field shaper segments 16, 18 in the coil segments.

To crimp or weld the metal tube 42, a brief, high intensity pulse of electrical current is passed through the coil segments 12, 14 via the contact surfaces 22, 24, thereby temporarily generating an electromagnetic field around the coil segments. For example, the current pulse may be in the range of 5-500 kA lasting for a duration of 0.1-100 milliseconds, and may be supplied by a power source such as a charged capacitor bank or similar power source capable of providing a current pulse within the stated ranges.

The generated electromagnetic field induces an eddy current in the field shaper segments 16, 18. In turn, the eddy current in the field shaper segments 16, 18 generates an electromagnetic field that induces an eddy current in the target metal tube 42. The eddy current induced in the metal tube 42 produces an electromagnetic field that opposes the electromagnetic field of the field shaper segments 16, 18. The field shaper segments 16, 18 are positioned relative to the metal tube 42 such that the opposing electromagnetic fields cause the walls of the metal tube to accelerate away from the field shaper segments, thereby compressing the metal tube without physically contacting the tube. The repulsive force generated by the electromagnetic field of the field shaper segments 16, 18 is therefore a non-contact force. The frame 30 prevents the coil segments 12, 14 from opening due to the magnetic force during the electromagnetic pulse, and also prevents arcing between the contact surfaces 22, 24 during the pulse by keeping the contact surfaces from separating.

After the compression, crimping, or welding has been performed on the metal tube 42, the frame 20 may be opened, separating the coil segments 12, 14 to allow the metal tube to be removed from the apparatus.

In an alternative arrangement of the apparatus 110, as shown in FIG. 3 the orientation of the slot between field shaper segment 116 and field shaper segment 118 may be disposed in any direction, and not necessarily in the orientation shown in FIG. 1. For example, in FIG. 1 the slot between the field shaper segments 16, 18 is generally parallel (i.e., aligned) with a separation line between the coil segments 12, 14. In contrast, in FIG. 3 the slot between the field shaper segments 116, 118 is generally perpendicular to a separation line between the coil segments 112, 114. The field shape segments 116, 118 are also disposed in a perpendicular disposition to an open and closing direction of the coil segments 112, 114. In this orientation, the force along the slot between the field shaper segments 116, 118 is reduced because the repulsive forces that arise during an electromagnetic pulse act on the field shaper segments in a different direction than the coil segments 112, 114. Therefore, it is easier to keep the coil segments 112, 114 in the closed position during an electromagnetic pulse. It should be understood that the slot between the field shaper segments may be disposed at any angle relative to the separation line between the coil segments.

FIGS. 5A and 5B illustrate electromagnetic pulse crimping or welding using the open coil apparatus 10. As shown schematically, the metal tube 42 may be deformed by the electromagnetic forces and moves towards an inner metal piece 44. The deformed area of the metal tube 42 collides with the metal piece 44, and is crimped or welded together with metal piece depending on the collision velocity. The metal piece 44 may be a rod, tube, or similar. FIG. 5A illustrates center joining of the metal tube 42 to the metal piece 44, while FIG. 5B illustrates end joining of a metal tube 42′ and metal piece 44′.

Although the invention has been described by reference to specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims.

Claims

1. An EMP apparatus comprising:

first and second opposed field shaper segments;

said field shaper segments including opposed working portions;

first and second coil segments respectively supporting said first and second opposed field shaper segments;

said coil segments being electrically operable and in eddy current contact with said field shaper segments;

insulators disposed between said field shaper segments and said coil segments; and

a frame moveably supporting said coil segments for movement between open and closed positions of said coil segments;

whereby metal stock can be disposed between said shaper segment working portions by opening said shaper and coil segments.

2. The EMP apparatus of claim 1, wherein said frame is a clamp.

3. The EMP apparatus of claim 1, wherein said frame is hinged.

4. The EMP apparatus of claim 3, wherein said coil segments are arranged in a clamshell configuration.

5. The EMP apparatus of claim 1, wherein coil segments have opposed curvilinear recesses and said field shaper segments have corresponding curvilinear protrusions.

6. The EMP apparatus of claim 1, wherein said field shaper segments are disposed to open and close with movement of said coil segments.

7. The EMP apparatus of claim 1, wherein said field shaper segments are disposed in a perpendicular disposition to an open and closing direction of said coil segments.

8. The EMP apparatus of claim 1, including a strap mounted on at least one of said coil segments to secure said field shaper segments in said coil segments.

9. A method of working a metal tube segment comprising the steps of:

providing an EMP apparatus including: first and second opposed field shaper segments; said shaper segments including opposed working portions; first and second coil segments respectively supporting said first and second opposed field shaper segments; said coil segments being electrically operable and in eddy current contact with said field shaper segments; insulators disposed between said shaper segments and said coil segments; and a frame moveably supporting said coil segments for movement between open and closed positions of said coil segments;

disposing a metal tube between said shaper segment working portions by opening said shaper and coil segments;

moving said frame to move said coil segments into said closed position;

applying a pulse of electric current through said coil segments to work said metal tube; and

removing said metal tube by opening said shaper and coil segments.

10. The method of claim 9, including the step of:

clamping said coil segments to secure said coil segments in said closed position.

11. The method of claim 9, wherein said frame includes a hinge for moving said coil segments between said open and closed positions.

12. The method of claim 9, wherein said field shaper segments open and close with movement of said coil segments.

13. The method of claim 9, including the step of:

disposing said field shaper segments in a perpendicular disposition to an open and closing direction of said coil segments.

14. The method of claim 9, including the step of:

mounting a strap on at least one of said coil segments to secure said field shaper segments in said coil segments.