METHOD AND APPARATUS FOR TRANSFER OF INITIATION SIGNALS

Abstract: A method and apparatus for transferring non-electric blasting initiation signals form detonating cord signal donor lines to signal transmission tube acceptor lines involves disposing the acceptor line in enhanced signal transfer configuration with the donor line. The acceptor line (30) may constitute the input lead (29a) of a detonator (10a). Enhanced signal transfer configuration between the input lead (29a) and the detonating cord (60) can be established by disposing input line (30) in at least partial wrap-around contact with the detonating cord (60) or in multiple abutting contact with the detonating cord (60). Enhanced signal transfer configuration can also be achieved for a detonator having at least two input lines in abutting contact with the detonating cord. A slider (44) is designed to extend contact between a detonator input lead and a detonating cord. The slider (44) provides a detonator retainer (48) for holding a detonator (10a) and a base fixture (74') that includes a pass-through aperture (58a) for a detonating cord (62). Input lead-retaining means (52) on the base fixture (74') disposes the input lead (29a) in position for enhanced signal transfer configuration with a detonating cord that may extend through the pass-through aperture (58a).

Description: METHOD AND APPARATUS FOR TRANSFER OF INITIATION SIGNALS BACKGROUND OF THE INVENTION Field of the Invention This invention relates to the transfer of initiation signals from detonating cord to one or more signal-receiv¬ ing lines and, in particular, to the transfer of initia¬ tion signals from detonating cord to the input lead of a detonator. Related Art Detonating cord is used widely in a variety of blast¬ ing applications to carry a non-electric initiation signal from an initiation device to a signal-receiving device. For example, detonating cord is used to initiate a deto¬ nator within a booster for borehole blasting applications. The detonator not only amplifies the initiation signal from the detonating cord to initiate the booster but usu- ally is a delay detonator which provides a preselected de¬ lay period between transfer of the signal from the deto¬ nating cord to the detonator and initiation of the boost¬ er. Such detonators are disposed within a recess in the booster with the input lead of the detonator in contact with the detonating cord. The input lead of the detonator may comprise low energy detonating cord, shock tube or low velocity signal tube, all of which are well-known in the art. U.S. Patent 4,796,533 to Yunan, dated January 10, 1989, discloses a primer assembly for a cast booster hav¬ ing a percussion cap-actuated detonator seated therein. A length of low energy detonating cord passes through the booster in parallel relation to the detonator. An initia¬ tion signal conveyed by the detonating cord is transferred to the detonator by an explosive coupling element that comprises a shock-sensitive detonating explosive, e.g., lead azide. U.S. Re-issue 30,621 of Patent 4,141,296 to Calder, Jr. et al, reissued May 26, 1981, discloses a booster as¬ sembly in which a carrier device is employed to slidably carry a booster alongside a detonating cord downline. In accordance with the teachings of this invention, the car¬ rier serves to separate the downline from the booster charge, to prevent direct initiation of the booster charge by the downline. As shown in Figures 1 and 4 and de¬ scribed at column 1 , line 33 through column 8, line 4, the assembly comprises a detonator (160) disposed in the booster. An initiation signal is transferred from the downline (10) to the detonator (160) by a transfer line having two ends, one of which is secured in the detonator and the other of which is disposed in external structures (70), (76), (80), (94), (96) et al which hold the line in a circuitous manner around the booster and the carrier and into a partial loop about the downline. The loop is not retained in a fixture to hold it in place where it con¬ tacts the downline, i.e., it is free-standing. Since the booster is mounted alongside the downline, it is subject to canting which can impose excessively firm contact be¬ tween the loop of the input lead line (134) and the down¬ line (10), causing the loop to catch on the downline as shown in Figure 10 of this application, thus preventing proper placement of the booster in the borehole. U.S. Patent 4,295,424 to Smith et al, dated October 20, 1981, discloses a primer assembly for a borehole charge. The assembly comprises a booster charge within which a detonator is disposed. A detonating cord downline passes along the periphery of the booster at a point dia¬ metrically opposite the detonator. An initiation signal is transferred from the downline to the detonator by a detonator input lead comprising intermediary initiating means (36), Figure 5, which contains an explosive charge and which is positioned adjacent to the downline detonat¬ ing cord, and an empty hollow tubular radiator (38) ex¬ tending between the initiating means (36) and the deto¬ nator. SUMMARY OF THE INVENTION One broad aspect of the present invention relates to a slider device for-positioning in a booster a detonator having an input lead with the input lead in enhanced sig- nal transfer configuration with a downline detonating cord. The slider device comprises a base fixture having a pass-through aperture for receiving and retaining such a downline detonating cord therein. An input lead-retaining means is carried on the device for disposing an input lead of such a detonator in position for enhanced signal trans¬ fer configuration with a detonating cord that may extend through the pass-through aperture. In a more specific aspect, the input lead-retaining means may be dimensioned and configured to position such an input lead for at least partial wrap-around contact with a detonating cord that may extend through the pass- through aperture. Alternatively, the input lead-retaining means may be dimensioned and configured to position such input lead for multiple abutting contact with such a deto- nating cord. An optional detonator retainer on the device receives and retains such a detonator therein. According to another aspect of the invention, the base fixture may comprise a base plate, a cover and hinge means for hingedly joining the cover to the base plate. The cover may then be moved between an open position and a closed position. In the open position, the input lead- retaining means is exposed to permit manipulation of an input lead into engagement with the input lead-retaining means. In the closed position, the base plate and cover cooperate to define a base chamber within which the input lead-retaining means is located. Optionally, the input lead-retaining means may comprise a first component car¬ ried on the base plate and a second component carried on the cover. In a particular embodiment, the second compo- nent of the input lead-retaining means may be dimensioned and configured to dispose a first portion of such input lead in transverse relation to a second portion of the in¬ put lead engaged by the first component of the input lead- retaining means. The invention also relates to an initiator unit com¬ prising a slider device as described above in combination with the detonator comprising an input lead. The input lead is disposed in the input lead-retaining means to po¬ sition the input lead for enhanced signal transfer config¬ uration with a detonating cord that may extend through the pass-through aperture of the slider device. In a particular embodiment, the input lead may com- prise at least one strand input line. Alternatively, the input lead may comprise at least one looped input line segment having a middle portion and two end portions each providing an input line for the detonator. (Such an input lead is sometimes referred to herein and in the claims as an "eyelet lead".) The input lead-retaining means may dispose an eyelet lead in position to provide abutting contact with a detonating cord extending through the pass- through aperture. In yet another alternative embodiment, the input lead-retaining means may dispose the eyelet lead about the pass-through aperture so that such detonating cord passes through the eyelet lead. An input lead may comprise at least two strand input lines, and the input lead-retaining means on the base plate may dispose first portions of the input lines in generally parallel relation to each other and in position for abutting contact with a detonating cord extending through the pass-through aperture. Optionally, the input lead-retaining means disposes second portions of the strand input lines in position to provide abutting contact with such detonating cord and in crosswise relation to the first portions. In a specific embodiment of the invention, the input lead-retaining means may be dimensioned and configured to dispose consecutive sections of an input lead in position to attain abutting contact with a detonating cord extend¬ ing through the pass-through aperture as follows. A first section having one end secured in the detonator may be disposed to establish a first point of abutting contact with such detonating cord. A second section may form a first loop and pass transversely over and beyond the first section to establish a second point of abutting contact with such detonating cord. A third section may form a second loop and may pass transversely to and beyond the second section to establish a third point of abutting con¬ tact with such detonating cord. The base fixture may comprise a base plate, a cover and hinge means for hingedly attaching the cover to the base plate. The input lead-retaining means may comprise a base plate component for retaining associated first and third sections of the input lead in abutting contact with a detonating cord extending through the pass-through aper¬ ture and in mutual generally parallel relation. There may also be a cover component for retaining an associated sec¬ ond section of the input lead in crosswise relation to sections associated with the base plate component and in abutting contact with such detonating cord. In a prefer¬ red embodiment, the third section of the input lead may have one end secured in the detonator, i.e., the input lead may comprise an eyelet lead. The invention also has several method aspects, relat¬ ing to methods for disposing a detonator in enhanced sig¬ nal transfer configuration with a detonating cord. One method pertains to an input lead comprising at least one strand input line. The method comprises disposing the in¬ put lead in multiple abutting contact with the detonating cord. There is also a method pertaining to an input lead comprising at least two input lines, the method comprising disposing each of the at least two input lines in abutting contact with the detonating cord. The invention also relates generally to a method for configuring the input lead of a detonator in signal trans¬ fer relation with a detonating cord using a slider unit comprising a base fixture having a pass-through aperture for receiving a detonating cord therein. The method com¬ prises engaging the input lead on the base fixture in a configuration which will establish enhanced signal trans- fer configuration with such a detonating cord extending through the pass-through aperture. According to one aspect of the invention, the method may comprise engaging the input lead on the base fixture in position to provide at least partial wrap-around con¬ tact with such a detonating cord. Alternatively, the method may comprise engaging the input lead on the base fixture in position to provide at least two points of abutting contact with such a detonating cord. If the in- put lead comprises at least two input lines, the method may further comprise disposing at least a portion of each of the input lines in generally parallel relation to each other. The method may be practiced in conjunction with a slider unit in which the base fixture comprises a base plate, a cover and hinge means for hingedly attaching the cover to the base plate, the cover being movable between an open position and a closed position relative to the base plate. The base plate and the cover each define re- spective apertures that cooperate when the cover is in the closed position to define a pass-through aperture for the base fixture. The input lead-retaining means may comprise a first component on the base plate and a second component on the cover. The method may then comprise disposing the cover in an open position, engaging a first portion of the input lead with the first component of the input lead-re¬ taining means and engaging a second portion of the input lead with the second component of the input lead-retaining means. The method then comprises closing the cover onto the base plate to retain the input lead in the base fix¬ ture with the first portion and the second portion in abutting contact with a detonating cord extending through the pass-through aperture. Closing the cover may dispose the second portion of the input lead in crosswise relation to the first portion. The method may be employed with an input lead comprising an eyelet lead having two ends secured in the detonator. The eyelet lead comprises a first portion comprising first and second input lines, each input line comprising a signal-emitting end secured in the detonator, the input lead further comprising a bight portion between the first and second input lines. The method may then comprise engaging the first and second input lines with the first component of the input lead-retaining means to dispose the first and second input lines in position to provide abutting contact with such a detonating cord extending through the pass-through aperture and in generally parallel mutual relation to each other. The bight portion of the shock tube segment may then be en¬ gaged with the second component of the input lead-retain¬ ing means, and the cover may then be closed to dispose the bight portion in crosswise relation to the first and sec- ond input lines and in abutting contact with such a deto¬ nating cord. As used herein and in the claims, the term "input line" as used in relation to a detonator refers to a length of signal transmission line that has an end secured in the detonator, for carrying an initiation signal to the detonator. The term "strand" as used in relation to a detonator input line indicates an input line having two ends with only one end secured in the detonator. The terms "looped input line segment" and "eyelet lead" refer to a segment of signal transmission line hav¬ ing two ends, both of which are secured in the detonator. A looped input line segment thus provides two input lines for the detonator. The term "input lead" refers collectively to all the input lines of a detonator. BRIEF DESCRIPTION OF THE DRAWINGS The description of the invention will be understood with reference to the following Figures, in which corre¬ sponding structures are assigned equivalent identifying numerals: Figure 1 is an elevation view of a detonator having an input lead in partial wrap-around contact with a detonating cord in accordance with one embodiment of the present invention; Figure 2A is a view similar to that of Figure 1 of a detonator having an input lead comprising two input lines, each in abutting contact with a detonating cord; Figure 2B is a detailed view of an input line disposed in abutting contact with a detonating cord 60; Figure 2C is an elevation view of a detonator having an input lead comprising an eyelet lead disposed in en¬ hanced signal transfer configuration relation with a de¬ tonating cord; Figure 3A is a perspective view of a slider unit in accordance with one embodiment of the present invention, together with a detonator and detonating cord disposed therein with the input lead of the detonator in enhanced signal transfer configuration with the detonating cord; Figure 3B is a plan view of the assembly of Figure 3A; Figure 4 is a cross-sectional view of a booster equipped with the assembly of Figure 3A; Figure 5 is a perspective view of a slider unit in accordance with another embodiment of the present inven¬ tion; Figure 5A is a plan view of the base plate of the slider unit of Figure 5; Figure 5B is a view similar to Figure 5A showing the input lead of a detonator in the input lead-retaining means on the base plate to dispose the input lead in abut- ting contact with a detonating cord; Figure 5C is a view similar to Figure 5B except that the input lead for the detonator comprises a looped shock tube segment disposed in partial wrap-around contact with the detonating cord; Figure 6A is a plan view of the base fixture of a slider unit in accordance with another embodiment of the present invention, together with a detonator as shown in Figure 1 with the input lead disposed in the input lead- retaining means of the base plate and the cover; Figure 6B is a view of the base fixture of Figure 6A showing how the input lead is configured when the cover is closed, the cover being omitted for clarity; Figure 7 is a view similar to Figure 6A, but with a detonator having an input lead comprising two input lines; Figure 8A is a view similar to Figure 7, but with a detonator having an input lead comprising a looped segment of shock tube disposed in the input lead-retaining means of both the base plate and the cover; Figure 8B is a view similar to Figure 8A showing the configuration of the input lead when the cover is in the closed position, the cover being omitted for clarity; Figure 8C is a view corresponding to Figure 8B showing another embodiment of the input lead; Figure 9 is a perspective view of the slider unit of Figure 5 with the cover closed and with a detonating cord extending through the slider unit and the pass-through aperture thereof; and Figure 10 is a partial elevation view of parts of a prior art device. DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF The present invention relates to a method and appara¬ tus for the transfer of a blasting initiation signal from a detonating cord downline to the input lead of a detona¬ tor for a booster used to initiate borehole blasting agents. The invention relates to configurations for en- hanced signal transfer to the detonator that do not re¬ quire that the input lead be disposed in extended parallel relation to the detonating cord. In accordance with the present invention, one method for obtaining such non-parallel enhanced signal transfer configuration between a detonating cord and a detonator input lead is to dispose the input lead in at least par¬ tial wrap-around contact with the detonating cord. The term "wrap-around contact" indicates that the input lead is constrained to assume a curvate configuration having an internal radius designed to dispose the input lead in con¬ tact with at least a portion of the cross-sectional cir¬ cumference of a detonating cord. Another method for at- taining enhanced signal transfer configuration is to pro¬ vide at least two points of abutting contact between the input lead and the detonating cord, e.g., by looping the input lead around so that at least two portions abut the detonating cord, or by placing each of at least two input lines in abutting contact with the detonating cord at least once. The term "abutting contact" indicates contact that results from tangential juxtaposition of the input lead and the detonating cord, optionally with mild lateral force to assure surface contact between them, as illu- strated in Figure 2B. Equally reliable signal transfer is attained with multiple points of abutting or "casual" con¬ tact as with a single point of firm contact, the latter resulting from pressure applied in pushing the input lead against the detonating cord to cause the two to deform one or both into substantial surface area contact. While firm contact generally enhances signal transfer reliability as compared to casual contact, even a single point of firm contact can inhibit the detonating cord from sliding through the pass-through aperture and can therefore inhib- it proper placement of a booster with which the invention is used. Casual, multiple abutting contact thus provides equally reliable signal transfer and better slidability than firm contact. The method and apparatus of the present invention im- prove the reliability of signal transfer between the de¬ tonating cord and the input lead by increasing the avail¬ able region of signal transfer between a downline and a detonator input lead. The invention also relates to de¬ vices that are useful in establishing enhanced signal transfer configuration between a detonator input lead and a downline detonating cord. One type of detonator that can be employed in connec¬ tion with the present invention is illustrated in Figure 1. In detonator 10a,- input lead 29a comprises a single signal transmission input line 30 which comprises a strand of shock tube having two ends. One end of the shock tube strand is a signal-emitting end disposed in signal trans- fer relation to a target charge (not shown) within deton¬ ator 10a. The target charge comprises at least an explo¬ sive output charge, and optionally other components such as a receptor charge and a pyrotechnic or digital delay unit, as is well-known in the art, so that detonator 10a may be either a conventional delay or an "instant" (i.e., non-delay) non-electric detonator, the structure and func¬ tion of which are well-known to those of ordinary skill in the art. Input line 30 extends outwardly from the input end 12b of shell 12 of detonator 10a and terminates in distal end 30b which is sealed off by seal 33 so that the hollow interior of the shock tube is not exposed to the environment. Since shock tube is conventionally made from thermoplastic polymeric materials, sonic welding or any other suitable method may be used for sealing distal end 30b. Input line 30 is in enhanced signal transfer config¬ uration with a signal donor line such as detonating cord 60, shown in cross section, by virtue of the partial wrap¬ around contact with detonating cord 60. When detonating cord 60 of Figure 1 initiates, a signal is transferred to the shock tube input line 30. Detonator 10a is thereby initiated. The wrap-around contact illustrated in Figure 1 is only partial wrap-around contact in that the input lead is only in contact with a circumferential arc of about 180 degrees of the center of the detonating cord. It will be appreciated however, that the input lead could be fully wrapped around the detonating cord in accordance with the present invention, if desired, provided that the wrap is sufficiently loose that it does not prevent the input lead from sliding along the detonating cord. Another embodiment of a detonator useful in the prac¬ tice of the present invention is shown in Figure 2A. The detonator 10b comprises an input lead 29b that comprises two strand input lines 30 and 31, each of which has two ends? a signal-emitting end secured in the input end of detonator 10b and a distal sealed end, i.e., ends 33 and 35. Otherwise, detonator 10b is similar in structure and function to detonator 10a, and corresponding structures are numbered identically. Enhanced signal transfer con¬ figuration between detonating cord 60 and input lead 29b is achieved in Figure 2A by disposing both input lines 30 and 31 in abutting contact with detonating cord 60. De¬ tonating cord 60 can transfer an initiation signal to both input lines so that detonator 10a receives two substan¬ tially simultaneous initiation signals to initiate its output charge. If one input line fails to initiate the output charge of detonator 10a, the other input line may succeed. Further, if the detonating cord fails to trans- fer a signal to one input line, there is a chance that the signal will be successfully transferred to the other input line. Thus, the enhanced signal transfer configuration of Figure 2A provides, in two ways, added assurance that a signal in the detonating cord will initiate the detonator, compared to a detonator having a single input line in abutting relation to a detonating cord. In the embodiment shown in Figure 2C, input lead 29c of detonator 10c comprises a segment of shock tube bent into a loop to provide a central bight portion 29c' be- tween two opposite signal-emitting ends that are secured in detonator 10c to provide input lines 30' and 31'. As indicated above, such a lead is referred to herein as an "eyelet lead". The donor line, i.e., detonating cord 60, can be passed through the loop defined by eyelet lead 29c and, as illustrated in Figure 2C, may be disposed in abut¬ ting contact with both input lines 30' and 31' so that it has two points of abutting contact with input lead 29c. So disposed, detonating cord 60 can transfer a signal to detonator 10c through either or both input leads 30' and 31', with the same improved reliability of having redun¬ dant input lines described above for detonator 10b. How¬ ever, the looped input lead 29c of detonator 10c provides an advantage even over the two strand input lead 29b be- cause a signal will travel away from each point on lead 29c at which it is received, towards the signal-emitting ends secured in detonator 10c. Detonator 10c will there¬ fore receive two input signals regardless of whether the signal is transferred at both points of abutting contact or at only one. Finally, an eyelet lead can easily be disposed in partial wrap-around relation to the donor line by passing the donor line through the eyelet loop and in engagement with bight portion 29c', as illustrated by det- onating cord 60''. In such a configuration, the detonator simultaneously derives the benefits of increased surface contact and redundancy of input signals. For these rea¬ sons, the eyelet lead embodiment of Figure 2C is preferred over the multiple strand embodiment of Figure 2A. Another reason for this preference is that, since both ends of an eyelet lead 29c are secured in the detonator 10c, there is no need for the extra step of sealing the distal ends of the shock tube signal transmission lines, as must be done for the embodiment of Figure 2A. The multi-lead detonators of Figures 2A and 2C are described more fully in co-pending patent application Ser¬ ial Number 08/548,815, filed January 11, 1996 in the name of Ernest L. Gladden et al, for "Detonators Having Multi¬ ple-Line Input Leads", (Attorney Docket P-1462). Figure 3A illustrates an initiator unit comprising a slider unit in accordance with the present invention with a detonator disposed therein. The detonator 10a comprises an input lead comprising a single strand input line 30. Slider unit 72 is designed to provide at least partial wrap-around enhanced signal transfer configuration between the single input line 30 of a detonator 10a and a downline detonating cord 60. Slider unit 72 comprises a base fix¬ ture 74 that defines a pass-through aperture (unnumbered) through which detonating cord 60 extends. Slider unit 72 further comprises a detonator retainer that comprises sleeve member 76, which is mounted to base fixture 74. Sleeve member 76 defines an internal bore dimensioned and configured to receive and retain therein the shell 12 of a detonator 10a having an input line 30 projecting therefrom into base fixture 74. Base fixture 74 defines a channel or other input lead-retaining means therein within which at least a portion of the input line may be disposed be- fore a detonating cord 60 is threaded through the pass- through aperture. (As seen in Figures 3A, 3B and 4, an extraneous portion of input lead, which may comprise sealed end 33, may project out from the base fixture.) Base fixture 74 may comprise a base plate defining at least a first component of the input lead-retaining means for disposing the input line in partial wrap-around rela¬ tion to the pass-through aperture. A cover may then be fitted onto the base plate to secure the input line in base fixture 74. Optionally, the cover may be hingedly attached to the base plate. After a detonator is secured in sleeve member 76 with its input lead in base fixture 74, a detonating cord can be disposed in the pass-through aperture. Then, as best seen in Figure 3B, input line 30 will be disposed in base fixture 74 in approximately a one-half turn wrap-around contact with the detonating cord 60. Preferably, the input lines comprise lengths of shock tube having an outside diameter (OD) not greater than about 2.380 mm (0.0937 inch), for example, a tube outside diameter (OD) of from about 0.397 to 2.380 mm (about 0.0156 to 0.00937 inch), and the ratio of the inside di¬ ameter of the tube to the radial thickness of the tube wall is from about 0.18 to 2.5. The inside diameter of the tube may be from about 0.198 to 1.321 mm (about 0.0078 to 0.0520 inch). The powder surface density of the reac¬ tive material contained within the bore of the tube may, but need not, be significantly less than that which the prior art considers to be a minimum acceptable powder sur¬ face density. Such shock tube is described in co-pending patent application Serial Number 08/380,839, filed January 30, 1995, in the name of Ernest L. Gladden et al for "Im¬ proved Signal Transmission Fuse" (Attorney Docket P-1385). Figure 4 shows the environment of use of slider unit 72, detonator 10a and -detonating cord 60. Booster 36 is a cast booster that generally comprises a secondary explo¬ sive and is cast so-that it defines an initiator well within which slider unit 72 and detonator 10a may be re- ceived and secured. Booster 36 also defines a central bore within which a hollow shielding sleeve 46 is secured. Shielding sleeve 46 also has a hollow bore dimensioned and configured to receive a detonating cord. Slider unit 72 is dimensioned and configured so that when it is received in the initiator well, the pass-through aperture is align¬ ed with the central bore of the booster. Then, after ini¬ tiator unit 72 is inserted into the initiator well of booster 36, detonating cord 60 may be threaded through shielding sleeve 46 and the pass-through aperture of base fixture 74. Booster 36 is then slid along detonating cord 62 to the desired position for blasting. Typically, booster 36 is disposed in the borehole filled with a blasting agent such as ammonium nitrate and fuel oil ("ANFO") or the like (not shown). Detonating cord 60 is initiated but it does not initiate booster 36 because of the protective function of shielding sleeve 46. However, detonating cord 60 can transfer an initiation signal to input line 30 and, thus, to detonator 10a. Detonator 10a has sufficient strength to initiate booster 36, which in turn initiates the borehole explosive. Slider unit 72 provides improved reliability in the transfer of an initi¬ ation signal from detonating cord 60 to detonator 10c by virtue of the input lead-retaining means in the base fix¬ ture that establishes enhanced signal transfer configura- tion between the two without the need for any apparatus to extend the input lead around the booster. By providing a base fixture that has a pass-through aperture for the downline and input lead-retaining means as described here¬ in, such contact is attained with a shorter input lead than is necessary for use with, e.g., the devices shown in U.S. Re-issue 30,621 (discussed above). Such a configura¬ tion also allows for the more economical manufacture of the slider unit since there is no need for external struc- tures needed to join the detonator input lead with a down¬ line that is separated from the booster with which the de¬ tonator is used. Another slider unit in accordance with the present invention is shown in Figure 5 which provides an upward- looking perspective view of the bottom of a slider unit 44. Slider unit 44 is useful for holding a detonator in place within a booster in the type of arrangement illus¬ trated in Figure 4, Figure 5 being enlarged relative to Figure 4. Slider unit 44 is adapted for use with a boost¬ er of the type which is encased within an outer shell which has means thereon such as recesses located at the bottom of the booster which are engaged by protrusions 64 to mount slider unit 44 and a detonator carried thereon within a booster, as more fully disclosed in commonly own¬ ed co-pending patent application Serial Number 08/575,244, filed on January 16, 1996, in the name of Daniel P. Sutula, Jr. et al, for "Slider Member For Booster Explo¬ sive Charges" (Attorney docket P-1480-2). Slider unit 44 comprises a shielding tube 46 having an internal bore through which the downhole detonating cord passes. Shielding tube 46 not only allows the boost¬ er to slide along the detonating cord, but also serves to protect the booster from being damaged or initiated di- rectly from the downline detonating cord, which preferably is a low energy detonating cord. A detonator retainer 48 is carried on shielding tube 46, to hold a detonator such as any one of the detonators illustrated and/or described herein. Slider unit 44 also includes a base fixture 74' that is connected to tube 46. Base fixture 74' comprises a base plate 50, base plate component 52a of the input lead-retaining means, and a cover 54 attached to base plate 50 by a hinge 54a. The base plate component 52a of the input lead-retaining means comprises flanges 66a, 66b that define saddle recesses 78, the function of which will be described below. Cover 54 optionally carries a cover component 52b of the input lead-retaining means which com¬ prises, in the illustrated embodiment, flange 57 and the grommet or raised annular boss 59 that encircles aperture 58b. Figure 5 shows hinged cover 54 in the open position; the cover may be closed as shown in Figure 9 by swinging cover 54 about hinge 54a whereby cover 54 and base plate 50 cooperate to define an enclosed base chamber 51 (indi¬ cated in Figure 5) within which the signal-receiving por¬ tion of the input lead of the detonator is disposed. Base plate 50 and cover 54 define base plate aperture 58a and cover aperture 58b respectively. These apertures align with one another when cover 54 is closed over base plate 50 so that they cooperate to provide a pass-through aper¬ ture 58 (Figures 8B, 8C and 9) that allows a detonating cord 62 to pass through the base fixture. Base plate 50 (Figure 5) comprises cover-engaging detents, only one of which, detent 53, is seen in Figure 5. Cover 54 comprises detent-receiving slots 56 that engage corresponding de¬ tents 53 when cover 54 is closed onto base plate 50 and that keep cover 54 in the closed position. Within the base chamber 51, the base plate component 52a and the cov- er component 52b of the input lead-retaining means cooper¬ ate to keep the input lead of a detonator in enhanced sig¬ nal transfer configuration relation with the pass-through aperture, e.g., in position to assume casual, abutting contact with a detonating cord in the pass-through aper- ture, as will be described more fully below. As seen in Figure 5A, the base plate component 52a of the input lead-retaining means comprises flanges 66a, 66b, 66c and 66d which are dimensioned and configured to define retaining channels to position a first portion of an input lead from a detonator in abutting contact relation with aperture 58a. On opposite sides of aperture 58a, flanges 66a and 66b define "pinch" regions 68 where a pair of in¬ put lines are disposed too close to one another to allow a typical detonating cord to pass between them. Between the pinch regions 68, flanges 66a and 66b diverge slightly around aperture 58a to permit input lines therein to bend around a detonating cord or other downline passed through aperture 58a, as discussed more fully below. Flanges 66a, 66b, 66c and 66d are dimensioned and configured to receive and retain an input lead therein so that a user can easily but securely engage the input lead with the input lead- retaining means. As seen in Figure 5B, when the detonator 10b is dis¬ posed in place in the slider unit to provide an initiator unit, input lines 30 and 31 are disposed in the base plate component 52a of the input lead-retaining means. Pinch regions 68 and the flared region therebetween constrain lines 30 and 31 to closely bend around a detonating cord 62 that extends through aperture 58a (Figure 5A) , i.e., input lines 30 and 31 are each disposed in casual, abut¬ ting contact with detonating cord 62, at points even with gussets 70. As a result, there are two points of abutting contact between the detonating cord 62 and the input lead 29a, and each of these can serve as points where an initi¬ ation signal is transmitted from detonating cord 62 to the detonator. This redundancy in signal transfer capability increases the reliability with which a signal can be transferred from cord 62 to the detonator. Preferably, flanges 66a, 66b do not bear on lines 30, 31 in the deflection region even when lines 30, 31 are de¬ flected about a detonating cord, i.e., they are disposed at a slight stand-off from the input lines in the deflec- tion region to avoid imposing firm contact between the in¬ put lines and the detonating cord due to foreseeable vari¬ ations in the diameters of the input lines and the deton¬ ating cord. The inherent resilience of the input lines and the slight stand-off of flanges 66a, 66b allows them to engage in casual abutting contact with the detonating cord in the deflection region. However, flanges 66a, 66b are configured to constrain lines 30, 31 from deflecting away from the detonating cord to a significant degree when the detonating cord initiates, since this could result in a failure to transfer the initiation signal to the input line. Gussetts 70 reinforce flanges 66a, 66b against the lateral force of initiation of the detonating cord and thus enhance the reliability of signal transfer to the in- put lead. Figure 5C shows detonator 10c of Figure 2C mounted within slider unit 44 with input lines 30' and 31' both in abutting contact with detonating cord 62. As illustrated in Figures 6A and 6B, a slider unit as generally described in connection with Figures 5 and 5A can be used in the practice of the present invention with a detonator whose input lead comprises a single input line. Slider unit 44' is substantially the same in con- struction as slider unit 44, except that flanges 66a and 66b of base plate component 52a' of the input lead-retain¬ ing means have optional curved ends and that the cover component 52b' of the input lead-retaining means comprises optional stays 61. Detonator 10a is mounted in slider unit 44' and, as seen in Figure 6A, a first portion 166 of the single strand input line 30 is positioned in the base plate component 52a' of the input lead-retaining means to secure line 30 in abutting contact relation to aperture 58a at a point near gusset 70a. In other words, a first portion of input line 30 is associated with the base plate component 52a of the input lead-retaining means. A second portion 161 of line 30 is disposed in the cover component 52b' of the input lead-retaining means, i.e., between flange 57 on one side of line 30 and boss 59 and stays 61 on the other side. Together, flange 57, boss 59, and stays 61 cooperate to retain the second portion of line 30 in abutting contact relation with cover aperture 58b. Thus, a second portion of line 30 is associated with the cover component of the input lead-retaining means. The input lead-retaining means is dimensioned and configured so that when cover 54 is moved into the closed position onto base plate 50, input line 30 is folded over into a configuration in which the second portion 161 of input line 30 is disposed in saddle recess 78. So dis- posed, second portion 161 is both in abutting contact re¬ lation with aperture 58a and in crosswise relation to the first portion 166 of line 30 as shown in Figure 6B. When a detonating cord extends through pass-through aperture 58 and therefore through base plate aperture 58a, it will come into abutting contact with line 30 at two points, one point being on first portion 166 near gusset 70a and the other points being on second portion 161 at flange 66c. Having two points of abutting contact provides added as¬ surance that the initiation signal from the detonating cord will be transferred to the input lead. As shown in Figure 7, a detonator 10b', having two strand input lines 30 and 31 can be disposed in slider unit 44' with each strand mirroring the other in its con¬ figuration on base plate 50 and cover 54, which are shown with cover 54 in the open position. When cover 54 is closed onto base plate 50, the respective second portions of the two strands assume the configuration indicated in dotted outline. A slider unit in accordance with the present invention can also be used in connection with a detonator 10c' having an eyelet lead 29c'', as shown in Figure 8A. A first portion 266 of eyelet lead 29c'' comprises input lines 30' and 31' for detonator 10c'. The first portion 266 of eyelet lead 29c'' is disposed on base fixture 74' between flanges 66a and 66b of base component 52a' of the line-retaining means, in abutting contact relation with aperture 58a at points near gussets 70a and 70b. A second portion (also referred to as the bight portion) 29c' dis- tally connects input lines 30' and 31' to form the closed loop opposite the detonator. Second portion 29c' is dis¬ posed in the cover component 52b' of the line-retaining means, e.g., between flange 57 and stays 61 and annular boss 59. When cover 54 is moved about hinge 54a into the closed position, eyelet lead 29c'' is folded so that it assumes the pretzel-shaped configuration shown in Figure 8B, in which both input lines 30' and 31' of first portion 266 are disposed in abutting contact relation with pass- through aperture 58 and the second portion, i.e., bight portion, 29c', is positioned to attain abutting contact with a detonating cord extending through base plate aper¬ ture 58a at a point on bight portion 29c' at flange 66c. Bight portion 29c' is also in crosswise relation to input lines 30' and 31' of the first portion 266. So configur¬ ed, eyelet lead 29c L ' can be described as having a first section (which comprises input lead 30' of first portion 266) having one end secured in the detonator and being disposed in position for abutting contact with a detonat¬ ing cord extending through the pass-through aperture. A second section of input lead 29c'' comprising bight por¬ tion 29c' forms a first loop and passes transversely over and beyond the first section to provide a second point of abutting contact with a detonating cord that extends through the pass-through aperture. Finally, a third sec¬ tion comprising input lead 31' forms a second loop and which passes transversely to and beyond the second section to a third point of abutting contact with such a detonat¬ ing cord. In an optional alternate embodiment, a single input line 30'' can be disposed in a pretzel-like config¬ uration similar to that shown in Figure 8B, except that the end of the third section 131 is sealed at 33 rather than being secured in the detonator cap, as shown in Fig¬ ure 8C. When cover 54 is swung into the closed position to enclose the input lead of a detonator disposed therein, a downline detonating cord 62 can be received in and will extend through the pass-through aperture 58, as shown in Figure 9. The detonating cord so disposed will be in en¬ hanced signal transfer configuration with the input lead of the detonator secured on the detonator retainer. By disposing the input lead in a base fixture through which the downline passes, the sliders of the present invention provide assurance that an input lead therein cannot catch on a downline sliding therethrough. Preferably, a detonating cord extending through the booster charge has, in cross section, a major flattened peripheral arc from which the signal output from the cord is more effectively transferred than at other peripheral regions. For example, the detonating cord may have an oval cross-sectional configuration having a major cross- sectional axis and a minor cross-sectional axis, and the major flattened peripheral arc extends along the major cross-sectional axis. Preferably, the input lead of the detonator is disposed in contact with the major flattened peripheral arc of the detonating cord. Optionally, the input lead may comprise an input line having, in cross section, a major flattened peripheral arc for increased sensitivity to the detonating cord signal, and the major flattened peripheral arc of the detonating cord is in con- tact with the major flattened peripheral arc of the input lead. The slider member may be configured to facilitate such contact. For example, the pass-through aperture 58 of the base fixture 74 may be oval to conform to the deto¬ nating cord and bias the detonating cord into a particular orientation, and the lead-retaining means may be configur¬ ed to dispose the input lead so that it contacts the major flattened peripheral arc of the detonating cord, prefer¬ ably with its own major flattened peripheral arc. While the invention has been described in detail with reference to particular embodiments thereof, it will be apparent that upon a reading and understanding of the foregoing, numerous alterations to the described embodi¬ ments will occur to those skilled in the art and it is intended to include such alterations within the scope of the appended claims.

Claims: THE CLAIMS What is claimed is: ' 1. A slider device for positioning in a booster a detonator having an input lead and for disposing the de¬ tonator in signal transfer relation with a downline de¬ tonating cord, the slider device comprising: a base fixture having a pass-through aperture for receiving and retaining the downline detonating cord therein; and input lead-retaining means carried on the device for disposing such input lead of such detonator in posi¬ tion for enhanced signal transfer configuration with such detonating cord extending through the pass-through aper¬ ture. 2. The slider device of claim 1 wherein the input lead-retaining means is dimensioned and configured to po¬ sition such input lead for at least partial wrap-around contact with such detonating cord. 3. The slider device of claim 1 wherein the input lead-retaining means is dimensioned and configured to po¬ sition such input lead for multiple abutting contact with such detonating cord. 4. The slider device of claim 1, claim 2 or claim 3 further comprising a detonator retaining means on the de¬ vice for receiving and retaining such detonator therein. 5. The slider device of claim 1, claim 2 or claim 3 wherein the base fixture comprises a base plate, a cover and hinge means for hingedly joining the cover to the base plate for movement of the cover from an open position in which the input lead-retaining means is exposed to permit manipulation of such input lead into engagement with the input lead-retaining means to a closed position, the base plate and cover cooperating when the cover is in its closed position to define a base chamber within which the input lead-retaining means is located. 6. The slider device of claim 5 wherein the input lead-retaining means comprises a first component carried on the base plate and a second component carried on the cover. 7. The slider device of claim 6 wherein the second component of the input lead-retaining means is dimensioned and configured to dispose a first portion of such input lead in transverse relation to a second portion of the in¬ put lead engaged by the first component of the input lead- retaining means. 8. An initiator unit comprising the slider device of claim 1, claim 2 or claim 3 in combination with a detona¬ tor comprising an input lead, the input lead being dis¬ posed in the input lead-retaining means to position the input lead for enhanced signal transfer configuration with a detonating cord that may extend through the pass-through aperture of the slider device. 9. The initiator unit of claim 8 wherein the input lead comprises at least one strand of input line. 10. The initiator unit of claim 8 wherein the input lead comprises at least one eyelet lead having a middle portion and two end portions, each end portion providing an input line for the detonator, wherein the input lead- retaining means positions the eyelet lead to provide abut¬ ting contact with such detonating cord. 11. The initiator unit of claim 8 wherein the input lead comprises at least one eyelet lead having a middle portion and two end portions, each end portion providing an input line for the detonator, wherein the input lead- retaining means disposes the eyelet lead so that such de¬ tonating cord will pass through the eyelet lead. 12. The initiator unit of claim 8 wherein the input lead comprises at least two input lines, wherein the input lead-retaining means on the base plate disposes first por¬ tions of the input lines in generally parallel relation to each other to provide abutting contact with such detonat¬ ing cord. 13. The initiator unit of claim 12 wherein the input lead-retaining means disposes second portions of the input lines in abutting contact with such detonating cord and in crosswise relation to the first portions. 14. The initiator unit of claim 8 wherein the input lead-retaining means is dimensioned and configured to dis¬ pose consecutive sections of an input lead as follows: (i) a first section having one end secured in the detonator is disposed to provide a first point of abutting contact with such detonating cord, (ii) a second section which forms a first loop and which passes transversely over and beyond the first section to provide a second point of abutting contact with such detonating cord, and (iii) a third sec¬ tion which forms a second loop and which passes trans¬ versely to and beyond the second section to provide a third point of abutting contact with such detonating cord. 15. The initiator unit of claim 14 wherein the base fixture comprises a base plate, a cover and hinge means for hingedly joining the cover to the base plate, and wherein the input lead-retaining means comprises a base plate component for retaining associated first and third sections of the input lead in abutting contact with such detonating cord and in mutual generally parallel relation, and a cover component for retaining an associated second section of the input lead in crosswise relation to por¬ tions associated with the base plate component and in po- sition to provide abutting contact with such detonating cord. 16. The initiator unit of claim 15 wherein the input lead comprises an eyelet lead wherein the third section of the input lead has one end secured in the detonator. 17. A method for disposing a detonator having an in¬ put lead comprising at least one input line in signal transfer relation to a detonating cord, the method com¬ prising disposing the input lead in multiple abutting con¬ tact with the detonating cord. 18. A method for disposing a detonator having an in¬ put lead comprising at least two input lines in signal transfer relation to a detonating cord, the method com¬ prising disposing each of the at least two input leads in abutting contact with the detonating cord. 19. The method of claim 18 wherein the input lead comprises at least two strand input leads. 20. The method of claim 18 wherein the input lead comprises an eyelet lead. 21. A method for configuring the input lead of a de¬ tonator in signal transfer relation to a detonating cord for transferring an initiation signal to the detonator, the detonator being retained within a slider unit compris¬ ing a base fixture having a pass-through aperture for re¬ ceiving a detonating cord therein, the method comprising engaging the input lead on the base fixture in a configur¬ ation which can provide enhanced signal transfer configur¬ ation with such detonating cord. 22. The method of claim 21 comprising engaging the input lead on the base fixture in position to provide at least partial wrap-around contact between the input lead and such detonating cord. 23. The method -of claim 21 comprising engaging the input lead on the base fixture in position to provide at least two points of abutting contact between the input lead and such detonating cord. 24. The method of claim 23 wherein the input lead comprises at least two input lines and wherein the method comprises engaging the input lead on the base fixture in position to dispose at least a portion of each of at least two input leads in position to provide abutting contact with such detonating cord and in generally parallel rela¬ tion to each other. 25. The method of claim 21 wherein the base fixture comprises a base plate, a cover and hinge means for hing¬ edly joining the cover to the base plate, the cover being movable between an open position and a closed position re¬ lative to the base plate, wherein the input lead-retaining means comprises a first component on the base plate and a second component on the cover, the base plate and the cov¬ er each defining respective apertures that cooperate when the cover is in the closed position to define a pass- through aperture for the base fixture; and wherein the method comprises disposing the cover in an open position, engaging a first portion of the input lead with the first component of the input lead-retaining means and engaging a second portion of the input lead with the second component of the input lead-retaining means, and then closing the cover onto the base plate to retain the input lead in the base fixture with the first portion and the second portion in abutting contact with such detonat¬ ing cord. 26. The method of claim 25 wherein closing the cover comprises disposing the second portion of the input lead in crosswise relation to the first portion. 27. The method of claim 25 wherein the input lead comprises an eyelet lead having two ends secured in the detonator, the input lead comprising a first portion com¬ prising a first and a second input line, each input line comprising a signal-emitting end secured in the detonator, the input lead further comprising a second portion com¬ prising a bight section joining the first input line and the second input line, wherein the method comprises engag¬ ing the input lines with the first component of the input lead-retaining means to dispose the first and second input lines in position to provide abutting contact with such detonating cord and in generally parallel mutual relation to each other, and engaging the bight portion of the shock tube segment with the second component of the input lead- retaining means, and wherein closing the cover disposes the bight portion in crosswise relation to the first and second input lines and in position to provide abutting contact with such detonating cord.

Inventors: BURTON JEFFREY H, DUFRANE RONALD M, GLADDEN ERNEST L, LILLEY THOMAS C, RENFRO STEVEN L, SUTULA DANIEL P JR, TORO DANIEL A, TSEKA THOMAS C, BURTON, JEFFREY, H., DUFRANE, RONALD, M., GLADDEN, ERNEST, L., LILLEY, THOMAS, C., RENFRO, STEVEN, L., SUTULA, DANIEL, P., JR., TORO, DANIEL, A., TSEKA, THOMAS, C.
Applicants: ENSIGN BICKFORD CO, THE ENSIGN-BICKFORD COMPANY
Application year: 1996
Main classification: C06C5
IPC codes: C06C5, F42B3, F42D1