WO2015187841A1

WO2015187841A1 - Wire with continuous conduction path under elongation

Info

Publication number: WO2015187841A1
Application number: PCT/US2015/034001
Authority: WO
Inventors: Thomas E. Burky; C. Byron TOLBERT
Original assignee: Battelle Memorial Institute
Priority date: 2014-06-04
Filing date: 2015-06-03
Publication date: 2015-12-10

Abstract

A wire for propagating a signal includes a first conductor strand that has a first end and a first breakpoint at a first distance from the first end of the first conductor strand. Further, the wire includes a second conductor strand that has a second end and a second breakpoint at a second distance from the second end of the second conductor strand. The breakpoint of the first conductor strand is at a different distance along the first conductor strand than the breakpoint of the second conductor strand. The two strands are axially surrounded by an insulator such that the first conductor strand is electrically coupled to the second conductor strand.

Description

WIRE WITH CONTINUOUS CONDUCTION PATH

UNDER ELONGATION

TECHNICAL FIELD

Various aspects of the present disclosure relate generally to conductive wire and specifically to wire for propagating a signal, such as an initiation signal or programming signal, from a blast controller to a detonator.

BACKGROUND ART

Blasting systems are used in mining and excavating operations to break down and remove earth material such as rock from a work location. In a typical operation, a miner drills a blast hole into the ground and then lowers a detonator into the blast hole. The detonator is connected to a line that provides a communication path from the detonator to an area outside of the blast hole. The blast hole is then filled with bulk explosive and a layer of stemming material. When the line is connected to a blast controller and an initiation signal is transmitted from the blast controller to the detonator, the detonator initiates the bulk explosive.

DISCLOSURE OF INVENTION

According to aspects of the present disclosure, a wire for propagating a signal is disclosed. The wire has a first conductor strand, a second conductor strand that is electrically coupled to the first conductor strand, and an insulator axially surrounding the first conductor strand and the second conductor strand. The first conductor strand has a first end and a first breakpoint along its length at a first distance from the first end thereof. Similarly, the second conductor strand has a second end and a second breakpoint along its length at a second distance from the second end thereof. The first breakpoint (of the first conductor strand) is at a different distance along the first conductor strand than the second breakpoint (of the second conductor strand).

In an illustrative implementation, the first breakpoint is axially spaced (along the length of the wire) from the second breakpoint. Moreover, the first conductor strand is electrically connected to the second conductor strand via physical contact at least in the areas around the first break point and second breakpoint. For instance, the first conductor strand can physically contact the second conductor strand so as to form an electrical connection along at least a portion of the length of the wire including the areas of the first breakpoint and the second breakpoint. Accordingly, a break at the first break point, the second breakpoint, or both (e.g., due to a tensile load on the wire) will not cause loss of continuity through the wire.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram illustrating a blasting system with a blast controller, a detonator, and a detonation wire according to various aspects of the present disclosure;

FIG. 2 is a block diagram illustrating a wire that can be used in the system of FIG. 1, where the wire is illustrated in a non-stretched state, according to various aspects of the present disclosure;

FIG. 3 is a block diagram illustrating a wire that can be used as the wire in FIG. 1 or FIG. 2 in a stretched state, according to various aspects of the present disclosure;

FIG. 4 is a block diagram of a simplified wire with only three conductor strands to illustrate signal propagation through the wire, according to various embodiments of the present disclosure;

FIG. 5A illustrates a breakpoint of a conductor strand of a wire according to any one or more of FIGS. 1-4, where the breakpoint is a curve-shaped notch cut in the conductor strand, according to various aspects of the present disclosure;

FIG. 5B illustrates a breakpoint of a conductor strand of a wire according to any one or more of FIGS. 1-4, where the breakpoint is a hole cut through the conductor strand, according to various aspects of the present disclosure;

FIG. 5C illustrates a breakpoint of a conductor strand of the a wire according to any one or more of FIGS. 1-4, where the breakpoint is an embrittled portion of the conductor strand, according to various aspects of the present disclosure;

FIG. 5D illustrates a breakpoint of a conductor strand of a wire according to any one or more of FIGS. 1-4, where the breakpoint is pre-severed, where the severed sections can optionally be reattached or left separated, according to various aspects of the present disclosure; and

FIG. 6 is a flow chart illustrating a method for creating a wire capable of elongation while preserving electrical conductivity, according to various aspects of the present disclosure. MODES FOR CARRYING OUT THE INVENTION According to various aspects of the present disclosure, a wire is provided, which is capable of elongation while preserving electrical continuity, as specifically described below with reference to the accompanying drawings.

By way of an example application, a blasting system includes in general, a blast controller that is wired to a detonator via the wire disclosed more fully herein. More particularly, a detonator is positioned within a blast hole. The wire extends from the detonator and out of the blast hole for connection to the blast controller. The blast controller is typically located on the ground surface near the blast hole. The blast hole is filled with bulk explosive and a layer of stemming material. The process of filling the blast hole can stretch or otherwise elongate the wire extending from the detonator up the hole due to the materials filling the hole exerting force on the wire. However, despite wire elongation, electrical continuity is preserved in the wire. As such, an initiation signal, programming signal, or both may be propagated through the wire between the blast controller and the detonator to set off a detonation event. Thus, even when the wire is stretched within a blast hole, the signal can reach the detonator.

In this manner, aspects of the present disclosure can be carried out in a variety of different modes and should not be limited to the content of description of any particular embodiment. Further, the wire described herein is not limited in purpose to a detonation wire and may be used in any application for which a wire is used that may be subject to elongation.

More particularly, a wire suitable for propagating a signal is disclosed. The wire includes multiple conductor strands that are electrically coupled together so as to define an array of conductive strands. For instance, in an illustrative implementation, the conductor strands are not individually surrounded by insulators. Rather, the conductor strands run generally parallel to each other along the length of the wire and are in electrical contact with each other along their length. The array (i.e., bundle) of conductor strands as a whole is surrounded by an insulator.

The conductor strands of the wire include one or more breakpoints. A breakpoint is a point, region, or other area between two adjacent sections of a conductor strand that is physically weaker than the adjacent sections of the corresponding conductor strand. Alternatively, the breakpoint can be a point where adjacent sections of a conductor strand are physically severed from one another. Thus, if the wire is stretched or otherwise elongated, the conductor strands that make up the wire will also stretch. One or more strands may even physically break (or separate if already severed). However, any breakage(s) will occur at the weakened breakpoint(s). Moreover, the sections of the broken strand are in physical electrical contact with adjacent strands so as to preserve overall electrical continuity through the wire, despite localized open circuits on one or more strands. Thus, as will be described in greater detail herein, the breakpoints are staggered along the length of the conductor strands in such a way that the conductor strands will not all break at the same point along the length of the wire, thus maintaining an electrically conductive path through the wire.

Turning now to the figures, and specifically to FIG. 1, an exemplary blasting system 100 is shown with a blast controller 102 coupled to a wire 104 that leads down a blast hole 106 and terminates at a detonator 108. In an exemplary blast preparation process, the bottom portion of the blast hole 106 is filled with bulk explosive 1 10 that is initiated by the detonator 108 when the detonator 108 receives an initiation signal from the blast controller 102. The top portion of the blast hole 106 is filled with a stemming material 1 12, which is an inert material used for purposes of confining the explosion resulting from the initiated bulk explosive 1 10. Usually, the stemming material 1 12 comprises smaller particles of inert material (e.g., sand, gravel, clay, drilling refuse, etc.) that are packed into the top of the blast hole 106.

In a blast preparation process, the detonator 108 is attached to the wire 104, and both are inserted into the blast hole 106. Bulk explosive 110 is then added to the bottom of the blast hole 106 over the detonator 108. In some cases, some bulk explosive may be in the blast hole before the detonator is inserted. When a desired amount of bulk explosive 110 has been added to the blast hole, the stemming material 1 12 is added to the top of the blast hole 106.

The preparation of a detonation event, including the process of filling the blast hole 106 with bulk explosive 1 10 and stemming material 1 12, can place a tensile load on the wire 104, causing the wire 104 to elongate. For instance, tensile loads on the vertical length of the wire 104 extending through the blast hole 106 can result due to the slumping of explosive product or rock stemming in the blast hole 106 during the blast preparation process set out above. As another example, the weight of rock stemming subsidence can be transferred to the detonator wire 106 causing the detonator wire 106 to stretch. A user initiates the start of an explosion event by causing the blast controller 102 to produce an initiation signal. The initiation signal propagates down the wire 104 and initiates the detonator 108, which initiates the bulk explosive 110. The wire 104 maintains continuity between the blast controller 102 and the detonator 108 for a successful detonation event because the wire 104 maintains conductivity, even when severely elongated. According to certain aspects of the present disclosure, only those wires in the blasting setup that will be exposed to high tensile loads need to consist of the wire 104 described more fully herein. For instance, the wire 104 may be used as the "down hole" or "down line" wires. However, it may be possible to use conventional wire as surface wires (e.g., where such surface wires are not subject to possible elongation).

Turning now to FIG. 2, a longitudinal cross section of a wire 204 is illustrated. The different shading designs are used to help delineate the individual conductor strands, not to indicate type of material. The wire 204 can be utilized as the wire 104 in the exemplary blasting system of FIG. 1, or the wire 204 can be used in other applications where resistance to tensile load is required or desirable. The wire 204 includes several conductor strands 222, 224, 226, 228, 230, 232, 234 running the length of the wire 204. The exemplary wire 204 has seven conductor strands shown in the longitudinal cross section, but the wire 104 may have any number (greater than one) of conductor strands. Further, while the wire 204 is shown running horizontally with conductor strands 222-234 stacked vertically for purposes of clarify of discussion herein, in practice, the conductor strands 222-234 can be stacked in the depth direction as well as twisted, braided, packed in a generally circular cross section or otherwise configured. Moreover, although terminating connectors are not shown, in practice, any suitable connector may be utilized. The particular termination will depend upon the application (e.g., upon the specific connection to the corresponding detonator and blasting controller in the example of FIG.

1).

In the illustrative implementation, the individual conductor strands 222-234 do not each include an individual outer insulator. Rather, where the individual conductor strands 222-234 touch, they are electrically coupled such that a signal propagating through one conductor strand is also propagated through adjacent conductor strands. In this regard, adjacent conductors are directly electrically connected through physical contact. Moreover, two conductors can be electrically connected through coupling between one or more intermediate conductors. Also, because the individual conductor strands 222-234 can be packed into various configurations, it is possible that one strand will physically contact, and thus be directly electrically coupled, to multiple adjacent strands.

The conductor strands 222-234 include at least one breakpoint 236-248. The breakpoints create weak points along the individual conductor strands. As such, the individual conductor strands may progressively break as more tension is applied to the wire 204 as will be described in greater detail herein.

In FIG. 2, the breakpoints 236-248 are illustrated as notches shaped as wedges cut into the conductor strands 222-234 themselves for purposes of illustration. The amount of weakness built into the breakpoint (e.g., the depths of the notches as schematically represented) affects the breaking strength of the breakpoint: for instance, the deeper the notch, the weaker the breakpoint will be. Also, the notch can extend entirely through, thus severing the adjacent sections of a given conductor strand.

Other breakpoint configurations may be implemented. For instance, in certain implementations, breakpoints are implemented as curved (e.g., round) or other shaped notches cut into the conductor strands or holes cut through the conductor strands. In yet further alternative implementations, breakpoints are implemented as portions (e.g., regions) of the conductor strands made brittle through a process (e.g., chemical treatments, crimping or bending etc.). In yet further alternative configurations, breakpoints are implemented by physically cutting the conductor strand into two portions and reconnecting the two portions with a weak connection (e.g., adhesive, solder, crimped sleeve, etc.).

Still further yet, the strands may be made up of individual segments that are coaxially positioned such that a space is defined between two segments of the strand. That space is also a breakpoint implementation. In an illustrative exemplary implementation using severed sections, strands are laid inside the insulator roughly end to end, such that at least one strand does not form a complete individual strand, but is rather laid out in strand sections that are physically separate from each other. Here, the breakpoints already exist and are implemented by the physical separation between the severed strand sections. The strand sections do not break per se. Rather, since the sections are already broken, the sections slide past each other in response to the insulator stretching.

Further, the breakpoints 236-248 are staggered relative to breakpoints 236-248 on adjacent conductor strands 222-234. For example, breakpoint 242 on conductor strand 228 is staggered both from breakpoint 240 on conductor strand 226 and from breakpoint 244 on conductor strand 230. Thus, the staggered breakpoints 236-248 on adjacent conductor strands 222-234 are a different distance from an end of the conductor strands 222-234. That is, the breakpoints 236-248 are staggered along the axial length of the wire 204. However, breakpoints 236-248 on non-adjacent conductor strands 222-234 may be in the same distance from the ends of the conductor strands 222-234. For example, see breakpoint 244 on conductor strand 230 and breakpoint 236 on conductor strand 222.

Also, in some cases, adjacent conductor strands 222-234 may have breakpoints at the same point along the conductor strand, if at least one conductor strand has a breakpoint staggered from a breakpoint on an adjacent conductor strand.

The array of conductor strands 222-234 is surrounded by an insulator 250 (e.g., a plastic jacket) running lengthwise (i.e., axially) to the conductor strands 222-234. The insulator 250 ensures that the conductor strands 222-234 physically touch adjacent conductor strands, allowing for an electrically conductive coupling between adjacent conductor strands.

Referring to FIG. 3, a wire 304 is illustrated under tension and so as to be elongated, according to aspects of the present disclosure. As with FIG. 2, the different shading designs are used to help delineate the individual conductor strands, not to indicate type of material. The wire 304 in FIG. 3 is analogous in many regards to the wire 204 of FIG. 2. As such, like elements are illustrated with a reference numeral 100 higher in FIG. 3 than in FIG. 2. That is, the wire 304 includes a plurality of conductor strands, e.g., conductor strands 322, 324, 226, 328, 330, 232 and 234, as illustrated. The conductor strands 322-334 include at least one breakpoint 236, 238, 240, 242, 244, 246, and 248 in a manner analogous to that described with reference to FIG. 2. Breakpoints 236-248 are represented by triangular notches in the conductor strands.

In the example of FIG. 3, tension is applied in the horizontal direction with enough force that breakpoints in three conductor strands 322, 328, 334 break. More particularly, breakpoint 336 in conductor strand 322, breakpoint 342 in conductor 328, and breakpoint 346 in conductor 334, have broken. The individual conductor-strand portions then slide past adjacent conductor strands allowing the wire 304 to increase in length without a complete break in a conduction path of the wire 304. Any or all of the conductor strands 322-34 may also be broken at other points not shown in the limited section shown. As illustrated, after the wire 304 has been elongated due to outside tension, the conduction path of conductor 322 is broken into two sections, 322A and 322B, which are separated by a break 352. However, since conductor strand 322A is electrically coupled to conductor strand 324, the conduction path of strand 322A can continue in strand 324 and then back to conductor strand 322B after the break 352. Similarly, the conduction path of conductor 334 is broken into two sections, 334A and 334B, which are separated by a break 354. However, the conduction path of conductor strand 334A can continue past break 354 on conductor strand 332 and back to conductor strand 334B. Likewise, the conduction path of conductor 328 is broken into two sections, 328A and 328B, which are separated by a break 356. The conduction path of conductor strand 328A can continue past break 356 on conductor strand 326, conductor strand 330, or both and back to conductor strand 328B.

As such, continuity across the length of the wire is preserved, despite three breaks in individual conductor strands. In practice, as more breaks occur in different sections of the wire 304, as long as at least one portion of a conductor strand straddles an individual break, then the conduction path is continuous. Also, as the insulator 350 (e.g., a plastic insulator jacket) is elongated along with the elongation of the wire, the insulator 350 will squeeze the conductor strands 322-334 helping to ensure a good electrical contact between adjacent conductor strands.

In an illustrative example, the breakage strength of individual strands is designed to occur at approximately the same force as the yield strength of the insulator 350. In an alternative exemplary implementation, the strength of the breakpoints may be varied, so the breakpoints break with different amounts of tension applied to the wire 304. Moreover, at least some of the breakpoints may have a breaking strength based on a ratio with the yield strength of the insulator 350. As such, the breaking strength of the breakpoints may be approximately equal to the yield strength of the insulator 350, greater than the yield strength of the insulator 350, less than the yield strength of the insulator 350, or a combination thereof.

As an illustrative example, a demolitionist may require a wire with an elongation to break percentage (i.e., yield strength) of 200% with a tensile strength of 150- 750 N (Newton). Under such conditions, a conventional wire would have its insulation stripped off under less than 200% elongation. However, in certain illustrative implementations, a shock tube material is used as wire insulation. The shock tube material is designed to withstand such extreme elongation and still remain functional as insulation. As such, in this exemplary implementation, both the wire and insulator can undergo extreme elongation and still function.

Referring to FIG. 4, a wire 404 is illustrated. As with FIGS. 2-3, the different shading designs are used to help delineate the individual conductor strands, not to indicate type of material. The wire 404 of FIG. 4 is analogous in many regards to the wire 304 of FIG. 3, the wire 204 of FIG. 2 or combinations thereof. As such, in FIG. 4, like elements are illustrated with a reference numeral 100 higher than in FIG. 3 and 200 higher than in FIG. 2. For the sake of simplicity and clarity of discussion herein, the wire 404 of FIG. 4 has three conductor strands 422, 424, 426. Each conductor strand is broken in two places, resulting in three portions for each strand: conductor strand 422 has portions 422A, 422B, and 422C; conductor strand 424 has portions 424A, 424B, and 424C; and conductor strand 426 has portions 426A, 426B, and 426C.

The breaks in conductor strand 422 are labeled 462A and 462B. Similarly, the breaks in conductor strand 424 are labeled 464A and 464B, and the breaks in conductor strand 426 are labeled 466A and 466B. Thus, none of the conductor strands 422-426 are unbroken from the blast controller to the detonator after the wire 406 has been elongated. However, in practice, one or more of the conductive strands of the wire 404 may have remained unbroken. Moreover, one or more of the conductor strands need not include a breakpoint. Likewise, not all conductor strands of the wire 404 need to have the same number of breakpoints.

Starting at the left, a signal 470 is on all three conductor strands 422A-426A. However, at break 462A, the signal 470 propagates through 424A and 426A only. At break 466A, the signal 470 only propagates on conductor strand portion 424A. However, after break 462A ends, the signal 470 returns to conductor strand 422 on portion 422B. After break 466A ends, the signal 470 is once again on all three conductor strands 422A- 426A.

At break 464A, the signal propagates on two conductor strand portions 422B and 426B, and when break 464A ends, the signal 470 is once again on all three conductor strands 422B-426B. At breaks 462B and 464B, the signal 470 is down to one conductor portion 466B until after the breaks 462B, 464B end. Then at break 466B, the signal 460 is on conductor strand portions 422C and 424C. After the break 466B ends, the signal 470 is once again on all three conductor strands 422C-426C. As such, while all of the conductor strands 422-426 have breaks, the signal 470 is still able to propagate from one end of the wire 404 to the other end. In other words, even though the individual conductor strands are not continuous, the conduction path through the wire 404 is continuous. In illustrative implementations, the more conductor strands in the wire, the more the wire may be stretched (i.e., elongated).

Therefore, if outside tension is placed on the wire, even to the point of extreme elongation, a continuous conduction path remains. For example, referring back to FIG. 1, if the stemming material 1 12 slumps (e.g., slides, settles, shifts, etc.) and places tension on the wire 104, then the conduction path is not broken in the wire 104 and the signal from the blast controller 102 may still reach the detonator 108.

FIGS. 5A-5D illustrate several embodiments of breakpoints in a conductive strand other than a wedge-shaped notch. In this regard, the illustrative embodiments of FIG. 5A-5D can be implemented with any of the wire configurations 104, 204, 304, 404 of FIGS. 1-4, respectively. FIG. 5A illustrates a conductor strand 510 with a breakpoint 516 that is a curve-shaped (i.e., rounded) notch cut into the conductor strand 510. As with the wedge-shaped notches, the depths of the curved notches affect the strength of the curved- shaped breakpoint 516.

FIG. 5B illustrates a conductor strand 520 with a breakpoint 526 that is a hole cut into the strand 520. The hole 526 can be cut entirely through the conductor strand 520 or only partway through the conductor strand 520. The diameter and depth of the hole 526 affects the strength of the breakpoint 526.

FIG. 5C illustrates a conductor strand 530 with a breakpoint 536 that is an embrittled portion of the conductor strand 530. The portion 536 may be embrittled by any means (e.g., heat, chemicals, etc.), and the process used to embrittle the portion affects the strength of the breakpoint 536.

FIG. 5D illustrates a conductor strand 540 that has been severed (e.g., cut into a first portion 542 and a second portion 544). In optional exemplary implementations, the two portions 542, 544 may be reconnected using a process such as soldering, adhesion, crimping, etc. The process used to reconnect the two portions 542, 544 affects the strength of the breakpoint 546. However, the severed sections can be utilized in their severed state. The point 546, where the two portions have been reconnected or is otherwise left severed, is considered the breakpoint 546 of conductor strand 540, as described in greater detail herein. FIG. 6 illustrates a process 600 for creating a wire that maintains a conduction path under elongation. At 610, a user creates breakpoints in a first conductor strand. Then at 612, the user creates breakpoints in a second conductor strand; however those breakpoints in the second conductor strand are staggered from the breakpoints in the first conductor strand (e.g., along the length of the wire). Then at 614, the two conductor strands are encapsulated in an insulator such that the first conductor strand is electrically coupled to the second conductor strand and breakpoints in the second conductor strand remain staggered from the breakpoints in the first conductor strand.

Some of the variables that affect the breaking of the wire include: the breaking strength of the breakpoints; the type of breakpoint; the distance between the breakpoints on the individual conductor strands; the placement of the breakpoints on a particular conductor strand relative to breakpoints on adjacent conductor strands (i.e., staggering the breakpoints); the number of strands in the wire; and the insulator material.

The breakpoints can be created using any method. For example, in certain implementations, for wedge-notch shaped breakpoints, a mechanical roll mill process or a laser cutting process is used as the wire is being transferred from a bulk wire spool onto a small spool for a wire winding process and extrusion coating process. The breakage strength of each individual strand is thus repeatable and predictable by controlling the amount of notch cut into the strand and by applying known analysis processes for crack propagation in the conductor metal.

The positioning of the breakpoints can be predetermined or programmed such that the distance between breakpoints occurs in random increments. In certain implementations, the degree of randomness is controlled so as to limit the maximum distance, minimum distance, or both between consecutive breakpoints. Further, the force required to cause a break may be varied across multiple breakpoints. Still further, in certain implementations, the conductor strands are arranged into one or more sets, where the positioning and break force of various breakpoints within the set can be controlled to be the same, different, random, according, or a combination thereof to a predetermined pattern.

Some collateral effects may occur in the wire from the notching process, such as work hardening (mechanical method) or heat treating (laser method). Combined together with the properties of the insulator (e.g., plastic insulation jacket), the particular technique used to create the breakpoint provides insight into the force required to stretch the overall wire. The breakage strength of individual strands can be designed to occur at approximately the same force as the yield strength of the plastic jacket if desired. Alternatively, the breakage strength of individual strands may be considerably more or less than the yield strength of the insulator.

The various described wire implementations herein are useful where resilience to breakage due to wire elongation is desirable. For instance, the wire described herein may be used in mining applications or other applications where elongation of the wire may result due to tensile load on the wire because the multi-strand, segmented conductor strands allow the overall wire to stretch and break individual strands but maintains high conductivity for extreme elongation performance. The illustrated configurations avoid the breakage and conductive open circuit situations that occur in conventional wire (e.g., typically solid core, single strand, etc.) when subjected to tensile loads in downhole mining operations. Thus, for example, the wire described herein, increases the survivability of the wire during a slump or subsidence in stemming or explosive material.

More particularly, the selection of breakpoints allows a wire placed under tensile load, to undergo a controlled, progressive breaking process (or designed random breaking process) that does not immediately lose conductivity. Moreover, the selection of breakpoints results in a controlled stretching without a single point of failure (open circuit). That is, the breakpoints in conductive strands define controlled positions of weakness for individual conductor strands so that the conductor strands progressively break as more tension is applied to the wire, without creating an open circuit between the ends of the overall wire, as described more fully herein. Alternatively, breakpoints can cause breakage to occur in a random pattern throughout the area of the wire that is being stretched. The breakpoints break and allow individual strands to slide past adjacent strands thus allowing the overall wire to increase in length without a complete break in the wire.

In exemplary implementations, the wire described herein can be elongated more than 10% of its normal length, and depending upon the number of conductor strands and corresponding breakpoints, the wire can be elongated substantially longer than 10% of its length. As noted in greater detail herein, performance of the wire, such as amount of elongation achievable, can be established by controlling parameters associated with the manufacture of the multi-strand, breakpoint wire, such as by controlling the breakpoint. Breakpoints can be controlled by setting for example, the depth of the notch into each strand; the shape of the notch (e.g., rounded versus wedge shaped or other shape); or by adjusting any other parameter that determines the weakness of the strand at the breakpoint. Moreover, parameters such as the distance between breakpoints in individual strands; the placement of the breakpoints with respect to breakpoints in adjacent strands; the number of strands used in each bundle defining a wire; the jacket material thickness/strength surrounding the multi-strand bundle, etc., can be used to affect performance of the wire.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

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 act for performing the function in combination with other claimed elements as specifically claimed. The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Aspects of the invention were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

CLAIMS What is claimed is:

1. A wire comprising:

a first conductor strand comprising:

a first end;

a first breakpoint at a first distance from the first end of the first conductor strand;

a second conductor strand comprising:

a second end;

a second breakpoint at a second distance from the second end of the second conductor strand, wherein the second distance is different than the first distance; and

an insulator axially surrounding the first conductor strand and the second conductor strand;

wherein:

the first conductor strand is electrically coupled to the second conductor strand.

2. The wire of claim 1, wherein the first breakpoint is a first notch with a first depth.

3. The wire of claim 2, wherein the second breakpoint is a second notch with a second depth, and the second depth is different than the first depth.

4. The wire of claim 2, wherein the first notch comprises a wedge shape.

5. The wire of claim 2, wherein the first notch comprises a curved shape.

6. The wire of claim 1, wherein the first breakpoint comprises a hole extending at least partway through the first conductor strand.

7. The wire of claim 1, wherein the first breakpoint comprises an embrittled portion of the first conductor strand.

8. The wire of claim 1, wherein the first breakpoint comprises:

a first portion;

a second portion physically separate from the first portion; and

a soldered portion coupling the first portion to the second portion.

9. The wire of claim 1, wherein:

the insulator comprises a yield strength; and

the first breakpoint comprises a breakage strength approximately equal to the yield strength of the insulator.

10. The wire of claim 1, wherein:

the insulator comprises a yield strength; and

the first breakpoint comprises a breakage strength less than the yield strength of the insulator.

1 1. The wire of claim 1, wherein the first conductor strand further comprises at least one additional breakpoint along a length thereof.

12. The wire of claim 1 further comprising a plurality of conductor strands with a plurality of breakpoints, wherein:

the breakpoints are staggered from each other; and

the conductor strands of the plurality of conductor strands are electrically coupled to each other and to the first conductor strand and the second conductor strand.

13. A method of creating a wire that maintains a conduction path under elongation, the method comprising:

creating breakpoints in a first conductor strand;

creating breakpoints in a second conductor strand, wherein the breakpoints in the second conductor strand are staggered from the breakpoints in the first conductor strand; electrically coupling the first conductor strand to the second conductor strand; and

encapsulating, axially, the first conductor strand and the second conductor strand in an insulator.

14. The method of claim 13, wherein creating breakpoints in the first conductor strand comprises cutting a notch into the first conductor strand.

15. The method of claim 14, wherein creating breakpoints in the second conductor strand comprises cutting a notch into the second conductor strand, wherein the notch of the second strand is a different depth than a depth of the notch cut into the first strand..

16. The method of claim 13, wherein creating breakpoints in the first conductor strand comprises select one of:

cutting a hole at least partway through the first conductor strand; and

severing adjacent sections of the first conductor strand.

17. The method of claim 13, wherein creating breakpoints in the first conductor strand comprises chemically treating the first conductor strand to reduce the tensile strength of at least a portion of the first conductor strand.

18. The method of claim 13, wherein creating breakpoints in the first conductor strand comprises:

cutting the first conductor strand into a first portion and a second portion; and reattaching the second portion to the first portion to define a point of weakness along the length of the first conductor strand.

19. The method of claim 13, wherein encapsulating, axially, the first conductor strand and the second conductor strand in an insulator comprises encapsulating, axially, the first conductor strand and the second conductor strand in an insulator such that there is a predetermined ratio between the strength of the insulator and the strength of the conductor strands.

20. A system comprising:

a detonator;

a blast controller configured to emit an ignition signal to the detonator; and a detonation wire coupled between the blast controller and the detonator, the detonation wire configured to transmit the ignition signal, wherein the detonation wire comprises:

a first conductor strand including:

a first end;

a second conductor strand including:

a second end;

a second breakpoint at a second distance from the second end of the second conductor strand, wherein the second distance is different than the first distance; and an insulator axially surrounding the first conductor strand and the second conductor strand;

wherein the first conductor strand is electrically coupled to the second conductor strand.