Patent Document

CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of application Ser. No. 13/567,230 filed Aug. 6, 2012 which is a continuation-in-part of application Ser. No. 12/785,674 filed May 24, 2010, which is a continuation-in-part of application Ser. No. 12/704,706 filed Feb. 12, 2010, now U.S. Pat. No. 8,397,969 issued Mar. 19, 2013, the contents of which are incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates broadly to explosively driven fasteners More particularly, this invention relates to an apparatus for installing explosively driven fasteners and explosive loads for use therewith. 
       BACKGROUND OF THE INVENTION 
       [0003]    Various forms of explosively actuated fastener systems have been developed to drive fasteners into hard structures such as wood, concrete, masonry and steel. A considerable advantage of using such fastener systems has been the reduced time required for installing the fasteners into hard structures. However, a major common disadvantage is that the fasteners cause high stresses when penetrating into the receiving material in the region of the fastening whereby greater spalling occurs. In addition, explosively actuated fastener systems are relatively complex in construction and costly to manufacture and, due to inadequate venting of their combustion chamber, suffer from the disadvantages that they are relatively noisy and tend to jam from a buildup of spent powder. 
         [0004]    Explosively actuated fastener systems have been previously divided into two general groups: the low-velocity fastener system (discharging fasteners at a velocity of less than about 300 ft/sec) and the high-velocity fastener system (discharging fasteners at a velocity of greater than about 500 ft/sec). In the low velocity systems, a drive pin is positioned at the exit end of a cylindrical barrel with a piston located inwardly and spaced from the drive pin and an explosive charge located behind the piston. In the high velocity systems, a drive pin is positioned behind the piston. Some high-velocity fastener systems still have the disadvantages of high noise level, dangerous free fastener velocity and high degree of spall and ricochet when the drive pin strikes the work surface. Some low-velocity fastener systems still have the disadvantage of high noise level, power limitation, severe spall out in concrete and high incidence of drive pin damage. 
         [0005]    With the fastener systems being ballistic in nature and the fasteners attaining free flight, the fastener systems have incurred safety concerns analogous to those of firearms. Designs of power loads have been adjusted to make systems safer, to reduce the number of required parts, and thus decrease the cost of production. 
         [0006]    U.S. Pat. No. 3,172,123 discloses an explosive actuated tool in which a spring-loaded barrel with a bore is forced toward a work surface, thus forcing a fastener into the bore of the barrel. The fastener acts as a firing pin for igniting a power charge disposed at a head end of the fastener. 
         [0007]    U.S. Pat. No. 3,514,025 discloses an electrically operated explosively actuated tool using a caseless cartridge. 
         [0008]    U.S. Pat. No. 3,665,583 describes a suspension clip structure which includes a center portion and a projecting retaining flange for facilitating the holding of the suspension clip structure on a power actuated tool. 
         [0009]    U.S. Pat. No. 3,797,721 describes an explosive actuated tool for driving a fastening stud. The tool includes a barrel with a bore. A muzzle is provided at one end of barrel and an explosion chamber communicates with the bore. A closed gas expansion chamber surrounds the barrel and communicates with the bore solely through a plurality of passageways in the barrel adjacent to the muzzle. 
         [0010]    U.S. Pat. No. 4,830,254 describes a two-stage power driving system for powder actuated tools comprising a barrel, a piston, a first stage power load activation means and a power amplifier. The power amplifier accommodates a stacked arrangement of a fastener and a second stage power load. 
         [0011]    U.S. Pat. No. 4,890,778 describes a hammer-activated fastener tool for driving fastener projectiles comprising a relatively movable barrel and housing components. The barrel carries a power load chamber body and a relatively movable piston member which in muzzleward movement drives the fastener object and on breechward movement achieves ejection of the spent power load cartridge. The housing carries a movable firing pin assembly. 
         [0012]    U.S. Pat. No. 4,899,919 briefly describes a self-energizing fastener which comprises a nail and a charge pellet attached to the head of the nail. A generally cylindrical tool with an “igniting projection” is also shown. 
         [0013]    U.S. Pat. No. 5,016,802 describes an explosive actuated extendable driving tool having a housing with a barrel at its front end for receiving a fastening element, with a load chamber in an inner end of the barrel. A manually actuated reciprocating shaft is slidably received in a retainer that is mounted to the back end of the housing. A muzzle with a self-aligning spall guard and splash guard are mounted to the barrel, with a noise suppression element being contained in a chamber formed between the spall guard and the splash guard. Exits for the discharge of combustion gases and carbon into the noise suppression element are defined by discharge ports formed in the barrel and spall guard. 
         [0014]    U.S. Pat. No. 5,135,150 describes a pole-type powder actuated tool that includes a first pin having a flange at the top end, a second pin having a flange at the top end in contact with the flange of the first pin so that the second pin will move in unison with the first pin, a front barrel for receiving a drive pin and cartridge, a rear barrel for accommodating the second pin and part of the first pin and engaged with the front barrel at one end and with a connecting pipe at the other end, two springs enclosing the first pin and second pin for forcing the two pins to the normal position after fired. 
         [0015]    U.S. Pat. No. 5,544,800, U.S. Pat. No. 5,497,929, and U.S. Pat. No. 5,423,469 describe a system for driving a fastener into a work surface. The system includes a fastener having a penetration end, a shaft and a receptacle head end for receiving a power charge and a tool having a reciprocating firing pin. The tool includes a barrel with a bore having a muzzle for receiving the fastener, a spring-biased firing pin and an exhaust chamber connected to the bore for receiving exhaust gases. 
         [0016]    U.S. Pat. No. 5,904,284 describes an explosively actuated fastener system. The explosively actuated fastener system includes a front end; a back end; an open-ended muzzle being positioned adjacent to the front end of the fastener system; an open-ended outer tubular member having a front end and a back end; an open-ended tubular cap being attached to the back end of the outer tubular member and having a front end and a back end and an inward circular protrusion at the back end; an open-ended barrel member including an axial, central bore and extending from within, being an integral continuation of, and thus connecting, the muzzle to the outer tubular member; an open-ended inner tubular member having a front end and a back end, with an outward circular protrusion and an inward circular protrusion being positioned at the front end; a reciprocating ejector comprising a retaining section positioned in the inner tubular member, an outward circular protrusion and a firing rod, that extends forwardly from the retaining section, that comprises a front section, a middle section and a back section and that is separated from the retaining section by the outward circular protrusion; an ejector housing being used for accommodating the reciprocating ejector and including a tube, an outward circular protrusion and a firing pin that extends forwardly from the tube, with the tube including a closed top, an open bottom, a front section that is smaller in diameter than the axial, central bore of the barrel member, a middle section and a back section that is separated from the middle section by the outward circular protrusion and that has a number of perforations; a forward spring being positioned within the inner tubular member; a balancing spring being positioned within the outer tubular member; a handle being attached to and serving as a closure for the back end of the inner tubular member; an open-ended sliding guide including a tubular main body and a front part that at its front edge has an inward circular protrusion and being positioned in front of the outward circular protrusion of the inner tubular member and within the outer tubular member; a reset spring being fitted around the front part of the sliding guide and being positioned between the outward circular protrusion of the ejector housing and the main body of the sliding guide and a pin means being fitted in the number of perforations in the back section of the ejector housing. 
         [0017]    According to the method of the &#39;284 patent, the handle is first pulled backwards to manually reset the fastener system. The backward movement of the inner tubular member results in opening up of the reset spring, causes the sliding guide to move backward and, thus, causes the pin means to lock. Upon pulling the handle to bring the fastener system to a set position, the handle is pushed forward. The forward push on the handle results in compression of the forward spring and build-up of a striking force that forces the inner tubular member to move forward. The forward movement of the inner tubular member causes the sliding guide to move forward and results in compression of the reset spring. The pin means is unlocked, allowing the forward spring to open up, and the firing rod moves forward, pushed by the opening forward spring, in the ejector housing and strikes front of the tube and the firing pin of the ejector housing which initiates deflagration or detonation of a solid propellant pill. 
       Objects of the Invention 
       [0018]    It is therefore an object of the invention to provide an improved tool for installing an explosively driven fastener as well as an improved explosively driven fastener for use therewith. 
       SUMMARY OF THE INVENTION 
       [0019]    In accord with these objects, which will be discussed in detail below, the tool according to the invention includes a cylindrical main body having a proximal threaded end, an internal trigger key, an external annular flange, and an internal spring stop distal of the trigger key, the main body defining a diametrical slot which extends a distance between its proximal and distal ends. As used herein the term “proximal” means closest to the tool operator and the term “distal” means distant from the tool operator, i.e. closest to the fastener. 
         [0020]    The proximal threaded end of the main body is coupled to a cylindrical tool base having a distal threaded end (for coupling to the main body), a proximal threaded end (for coupling to a pole), an external annular flange, and an internal spring receiving recess. The distal threaded end of the tool base is threadably coupled to the proximal threaded end of the main body. A cylindrical outer cover extends over a proximal portion of the main body and a distal portion of the tool base, the cover being embraced by the respective external annular flanges of the main body and the tool base. 
         [0021]    A firing pin holder having a proximal end and a distal end with a stepped diameter defining a spring stop therebetween is arranged coaxially within the main body. A main spring is mounted coaxially on the proximal end of the firing pin holder and extends, together with a portion of the proximal end of the firing pin holder, into the spring receiving recess of the tool base. A firing pin is coupled to the distal end of the firing pin holder. The firing pin holder is provided with a diametrical main assembly pin which passes through a diametrical hole in the firing pin holder and engages the diametrical slot of the main body. The assembly pin and slot engagement limit the longitudinal movement of the firing pin holder and the main body relative to each other. The firing pin holder and firing pin together are referred to as the firing pin assembly. 
         [0022]    A firing pin assembly guide is arranged coaxially between the firing pin assembly and the main body. The firing pin assembly guide has a relatively large diameter proximal end, a relatively small diameter distal end, and an external annular flange therebetween. The relatively large diameter proximal end receives the distal end of the firing pin holder and is provided with a diametrical slot which also received the main assembly pin. The small diameter distal end receives the firing pin. In addition, the firing pin assembly guide is provided with a keyway which is arranged to receive the trigger key of the main body as well as a radially biased trigger which extends from the firing pin holder. The keyway is arranged to allow longitudinal movement of the trigger key relative to the firing pin assembly guide and prevent longitudinal movement of the trigger (and thus the firing pin assembly) relative to the firing pin assembly guide when the trigger is radially biased into the keyway. Longitudinal distal movement of the main body causes the trigger key to ride over the radially biased trigger and disengage it from the keyway thereby allowing longitudinal movement of the firing pin assembly relative to the firing pin assembly guide. 
         [0023]    An inner sleeve has a reduced diameter proximal end defining internal and external annular flanges and a threaded distal end. The inner sleeve is coaxially mounted between the firing pin assembly guide and the main body with the internal annular flange of the inner sleeve cooperating with the external annular sleeve of the firing pin assembly guide to limit distal movement of the inner sleeve. A reset spring is mounted over the proximal end of the inner sleeve and is captured between the external annular flange of the inner sleeve and the internal spring stop of the main body. 
         [0024]    A muzzle having proximal threads and distal threads is coupled by its proximal threads to the threaded distal end of the inner sleeve. The muzzle defines a throughbore which receives the distal end of the firing pin assembly guide leaving a distal space to receive the proximal end of an explosively driven fastener. The muzzle has a plurality of exhaust bores extending outward from the throughbore to the outer surface of the muzzle. A debris cup is coaxially mounted over the muzzle and coupled to it via the muzzle&#39;s distal threads. The debris cup catches exhaust debris that exits the muzzle throughbore via the exhaust bores. According to one aspect of the invention, a plurality of interchangeable muzzles are provided. Each muzzle has a different number of exhaust bores. The number of exhaust bores influences the force with which the explosively driven fastener will impact the surface into which it is fired. 
         [0025]    An explosively driven fastener according to the invention includes a nail having a pointed distal end and a proximal nail head. The nail head is mounted inside a plastic cap containing a buffer and a nitrocellulose load. Preferably, a spacer is arranged between the buffer and the load creating an air space between the buffer and the load. The nail is advantageously mounted in an angle bracket which will be affixed to a surface by the nail after the nail is driven. In addition, a rubber seal is preferably arranged on the nail between the bracket and the plastic cap. The plastic cap is preferably provided with outwardly extending flutes or wings. Because of the provision of different muzzles, it is possible to provide fasteners with a uniform standard load rather than different loads for different surfaces. 
         [0026]    In operation, an explosively driven fastener is inserted into the distal end of the muzzle throughbore. More particularly, the plastic cap is inserted into the throughbore until the bracket abuts the distal end of the muzzle. The fastener bracket is aligned with a surface to be penetrated by the nail and the tool base is pushed distally towards the surface. Distal movement of the tool base moves the main body, the main spring and the firing pin assembly, all distally. Distal movement of the firing pin assembly causes distal movement of the firing pin assembly guide since they are locked together by the radially biased trigger. The distal end of the firing pin assembly guide abuts the proximal end of the fastener (the plastic cap containing the load) which prevents further distal movement of the firing pin assembly guide. In addition, distal movement of the main body causes compression of the reset spring as it is biased against the inner sleeve which is prevented from distal movement by the muzzle which abuts the fastener bracket which abuts the surface to be penetrated. Further distal movement of the tool base therefore compresses the main spring against the firing pin holder and continues to move the main body distally relative to the firing pin assembly and guide, also further compressing the reset spring. Continued distal movement causes the key of the main body to enter the keyway of the firing pin assembly guide and ride over the radially biased trigger depressing the trigger radially inward. Radial depression of the trigger disengages the firing pin assembly from the firing pin assembly guide allowing it to move freely longitudinally distally. The compressed main spring then forces the firing pin assembly in the distal direction with the firing pin traveling through the distal end of the firing pin assembly guide (which is held against distal movement by the fastener) until the firing pin exits the firing pin assembly guide and impacts the proximal end of the fastener striking the explosive load. The load explodes forcing the nail out of the muzzle and into the surface to be penetrated. 
         [0027]    When the tool is moved away from the fastener, the actions of the springs automatically resets the tool. Sometimes the spent load container remains lodged inside the tool. Movement of the muzzle in the proximal direction brings the proximal end of the spent load container into engagement with the distal end of the firing pin assembly guide and causes the spent load container to be ejected. 
         [0028]    The apparatus according to the invention obviates the need to purchase separate loads for the tool and there is no need to place fasteners and loads into the tool separately. The tool is easily assembled and disassembled for cleaning and is preferably made entirely of stainless steel. Since the nail is directly propelled by the explosive rather than by a driver propelled by explosive, better nail penetration is achieved. In addition, there is no need to replace drivers which wear after repeated impact against nail heads. Further, the absence of a driver results in the absence of vibration when the tool is in use. This results in greater accuracy and less noise. The nail penetrates much faster and thus results in a lower failure rate. The slim profile of the tool allows it to fit into tight spaces such as between ductwork, pipes, etc. The tool automatically triggers and is automatically reset after use. 
         [0029]    The construction of the tool renders it lighter. The tool in combination with the provided fastener is quieter than powder actuated tools. This is important when working in an occupied building. The plastic cap on the nail contains the energy that would otherwise escape and cause noise. 
         [0030]    Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  is a side elevation view of a tool according to the invention; 
           [0032]      FIG. 2  is a side elevation view of a fastener according to the invention; 
           [0033]      FIG. 3  is a side elevation view of a tool and fastener according to the invention; 
           [0034]      FIG. 4  is a longitudinal cross section taken along line  4 - 4  in  FIG. 1 ; 
           [0035]      FIG. 5  is an exploded perspective view of a tool according to the invention; 
           [0036]      FIG. 5 a    is a broken perspective view of a first muzzle configuration; 
           [0037]      FIG. 5 b    is a broken perspective view of a second muzzle configuration; 
           [0038]      FIG. 5 c    is a perspective view of an alternate embodiment of a firing pin assembly guide; 
           [0039]      FIG. 5 d    is a sectional view taken along line  5   d - 5   d  in  FIG. 5   c;    
           [0040]      FIG. 6  is a cut away view of the main body component of  FIG. 5 ; 
           [0041]      FIG. 7  is a section taken along line  7 - 7  in  FIG. 6 ; 
           [0042]      FIG. 8  is a perspective view of a fastener according to the invention; 
           [0043]      FIG. 9  is a section taken along line  9 - 9  in  FIG. 8 ; 
           [0044]      FIG. 10  is an exploded partially broken perspective view of the fastener; 
           [0045]      FIG. 11  is a side elevation view of a fastener arranged next to a concrete surface; 
           [0046]      FIGS. 12-18  are views similar to  FIG. 4  showing the tool and fastener is stages of operation; 
           [0047]      FIG. 19  is a longitudinal section and partial perspective view illustrating the tool ejecting a spent load container; 
           [0048]      FIG. 20  is an exploded view including a broken longitudinal section of the end of a tool according to the invention, and side elevation views of an explosive load according to the invention and a prior art fastener; 
           [0049]      FIGS. 21 and 22  are views similar to  FIG. 20  with different prior art fasteners; and 
           [0050]      FIGS. 23-25  are views similar to  FIGS. 20-22  but show the tool, load and fastener assembled and ready to fire. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0051]    Turning now to  FIGS. 1-3 , the invention includes an apparatus  10  for installing an explosively driven fastener  12 . The fastener  12  (described in more detail below with reference to  FIGS. 8-11 ) typically includes a nail  14 , an explosive load  16 , and an angle bracket  18  which is coupled to a suspension wire  20 . 
         [0052]    Turning now to  FIGS. 4-7 , the tool  10  according to the invention includes a cylindrical main body  22  having a proximal threaded end  24 , an internal trigger key  26 , an external annular flange  28 , an internal spring stop  30  distal of the trigger key  26 , and a distal end  32 . The main body  22  defines a diametrical slot  34  which extends a distance between the main body proximal end  24  and distal end  32 . As used herein the term “proximal” means closest to the tool operator and the term “distal” means distant from the tool operator, i.e. closest to the fastener. 
         [0053]    The proximal threaded end  24  of the main body  22  is coupled to a cylindrical tool base  36  having a distal threaded end  38  (for coupling to the threaded end  24  of the main body  22 ), a proximal threaded end  40  (for coupling to a pole, not shown), an external annular flange  42 , and an internal spring receiving recess  44 . The distal threaded end  38  of the tool base is threadably coupled to the proximal threaded end  24  of the main body  22 . A cylindrical outer cover  46  extends over a proximal portion of the main body  22  and a distal portion of the tool base  36 , the cover  46  being embraced by the external annular flange  28  of the main body  22  and the external annular flange  42  of the tool base  36 . As used herein, the main body  22  coupled to the tool base  36  are said to comprise the “trigger body”. 
         [0054]    A firing pin holder  48  having a proximal end  50  and a distal end  52  with a stepped diameter defining a spring stop  54  therebetween is arranged coaxially within the main body  22 . A main spring (firing spring)  56  is mounted coaxially on the proximal end  50  of the firing pin holder  48  and extends from the spring stop  54 , together with a portion of the proximal end  50  of the firing pin holder  48 , into the spring receiving recess  44  of the tool base  36 . A firing pin  58  is coupled to the distal end  52  of the firing pin holder  48 . According to the presently preferred embodiment, a steel disk  57  and a frustroconical rubber buffer  59  are located behind the main spring  56  as shown best in  FIG. 4 . These parts act as shock absorbers. 
         [0055]    The firing pin holder  48  is provided with a diametrical main assembly pin  60  which passes through a diametrical hole  62  in the firing pin holder  48  and engages the diametrical slot  34  of the main body  22 . The assembly pin  60  and slot  34  engagement limit the longitudinal movement of the firing pin holder and the main body relative to each other. The firing pin  58  is coupled to the firing pin holder  48  by a pin  64  which engages a diametrical hole  66  in the firing pin and a diametrical hole  68  in the firing pin holder. More specifically, the firing pin  58  has a proximal head  70  which defines the diametrical hole  66  and a pointed distal end  72 . The head  70  is received in a recess  74  at the distal end of the firing pin holder  48 . The coupled firing pin holder  48  and firing pin  58  together are referred to as the firing pin assembly. 
         [0056]    A firing pin assembly guide  76  is arranged coaxially between the firing pin assembly  48 ,  58  and the main body  22 . The firing pin assembly guide  76  has a relatively large diameter proximal end  78 , a relatively small diameter distal end  80 , and an external annular flange  82  therebetween. The relatively large diameter proximal end  78  receives the distal end  52  of the firing pin holder  48  and is provided with a diametrical slot  84  which also receives the main assembly pin  60 . The small diameter distal end  80  receives the firing pin  58 . In addition, the firing pin assembly guide  76  is provided with a keyway which is arranged to receive the trigger key  26  of the main body  22  as well as a radially biased trigger  88  which extends from the firing pin holder  48 . The keyway  86  is arranged to allow longitudinal movement of the trigger key  26  relative to the firing pin assembly guide  76  and prevent longitudinal movement of the trigger (and thus the firing pin assembly) relative to the firing pin assembly guide when the trigger  88  is radially biased into the keyway  86 . More particularly, the keyway  86  has a circular stop  90  which intersects the keyway  86  and receives the trigger  88  which is biased into the stop by a spring  92 . Longitudinal distal movement of the main body  22  relative to the firing pin assembly guide  76  causes the trigger key  26  (which has a smooth distal edge) to ride over the radially biased trigger  88  and disengage the trigger  88  from the keyway  86  thereby allowing longitudinal movement of the firing pin assembly  48 ,  58  relative to the firing pin assembly guide  76 . 
         [0057]    An inner sleeve  94  has a reduced diameter proximal end  96  defining an internal annular flange  98 , an external annular flange  100  and a threaded distal end  102 . The inner sleeve  94  is coaxially mounted between the firing pin assembly guide  76  and the main body  22  with the internal annular flange  98  of the inner sleeve  94  cooperating with the external annular flange  82  of the firing pin assembly guide  76  to limit distal movement of the inner sleeve  94  (see  FIG. 12 , e.g.). A reset spring  104  is mounted over the proximal end  96  of the inner (reset) sleeve  94  and is captured between the external annular flange  100  of the inner sleeve  94  and the internal spring stop  30  of the main body  22 . According to the presently preferred embodiment, a TEFLON ring  77  is located on the proximal side of the annular flange  82 . The ring  77  reduces the shock when the firing pin guide is propelled backward and the flange  82  is moved toward the flange  98 . 
         [0058]    A muzzle  106  having proximal threads  108  and distal threads  110  is coupled by its proximal threads  108  to the threaded distal end  102  of the inner sleeve  94 . The muzzle  106  defines a throughbore  107  which receives the distal end  80  of the firing pin assembly guide  76  leaving a distal space to receive the proximal end of an explosively driven fastener (described below with reference to  FIGS. 9-19 ). The muzzle  106  has a plurality of exhaust bores  112  extending outward from the throughbore  107  to the outer surface of the muzzle. The number, location and configuration of the exhaust bores  112  maybe varied to affect the operation of the explosive load. For example,  FIGS. 5 and 5   a  illustrate a muzzle having six exhaust bores  112  which are staggered longitudinally in two groups of three bores arranged approximately one hundred twenty degrees apart. The bores are not perfectly radial but are angled proximally, i.e. in the direction taken by exhaust from the explosive load.  FIG. 5 b    illustrates an alternative muzzle  106 ′ having the same threads  108 ′,  110 ′ as the threads  108 ,  110  in the muzzle  106 . Thus, the muzzles  106  and  106 ′ are interchangeable in the tool  10 . The exhaust bores  112 ′ in the muzzle  106 ′ are fewer in number, thus allowing less exhaust from the exploding load. From the foregoing, those skilled in the art will appreciate that the fewer the exhaust bores, the greater the explosive force will be on the fastener. 
         [0059]    According to an alternate embodiment, shown in  FIGS. 5 c  and 5 d   , a slightly different firing pin assembly guide  276  is provided. The firing pin assembly guide  276  is similar to the firing pin assembly guide  76  ( FIG. 5 ) with similar numerals (increased by 200) referring to similar features. There is a relatively large diameter proximal end  278 , a relatively small diameter distal end  280 , and an external annular flange  282  therebetween. The relatively large diameter proximal end  278  receives the distal end  52  of the firing pin holder  48  ( FIG. 5 ) and is provided with a diametrical slot (not shown) which also receives the main assembly pin  60 . The small diameter distal end  280  receives the firing pin  58 . In addition, the firing pin assembly guide  276  is provided with a keyway  286  which is arranged to receive the trigger key  26  of the main body  22  as well as the radially biased trigger  88  which extends from the firing pin holder  48 . The keyway  286  is arranged to allow longitudinal movement of the trigger key  26  relative to the firing pin assembly guide  276  and prevent longitudinal movement of the trigger (and thus the firing pin assembly) relative to the firing pin assembly guide when the trigger  88  is radially biased into the keyway  286 . More particularly, the keyway  286  has a circular stop  290  which intersects the keyway  286  and receives the trigger  88  which is biased into the stop by the spring  92 . Longitudinal distal movement of the main body  22  relative to the firing pin assembly guide  276  causes the trigger key  26  (which has a smooth distal edge) to ride over the radially biased trigger  88  and disengage the trigger  88  from the keyway  286  thereby allowing longitudinal movement of the firing pin assembly  48 ,  58  relative to the firing pin assembly guide  276 . 
         [0060]    The firing pin assembly guide  276  is also provided with a plurality of circumferential grooves  281 ,  283 ,  285 ,  287  extending along at least part of the relatively small diameter distal end  280  of the firing pin assembly guide  276 . The firing pin assembly guide  276  may be preferable to the firing pin assembly guide  76  where the tool is made with relatively large dimensions. The grooves  281 ,  283 ,  285 ,  287  supplement the exhaust bores  112  of the muzzle  106  ( FIGS. 5, 5   a , and  5   b ) by allowing some exhaust to vent through the main body of the tool. This makes the larger tools much quieter. 
         [0061]    A debris cup  114  is coaxially mounted over the muzzle  106  and coupled to it via the muzzle&#39;s distal threads  110 . The debris cup  114  catches exhaust debris that exits the muzzle throughbore via the exhaust bores  112 . A flange  118  on the muzzle separates the distal end  102  of the inner sleeve  94  from the proximal end of the cup  114 . Distal inner threads  116  on the debris cup anchor it to the distal outer threads  110  of the muzzle  106 . 
         [0062]    Referring now to  FIGS. 8-11 , an explosively driven fastener  12  according to the invention includes a nail  14  having a pointed distal end  120  and a proximal nail head  122 . The nail head  122  is mounted inside a plastic cap  16  containing a buffer  124  and a nitrocellulose load  126 . Preferably, a spacer  128  is arranged between the buffer  124  and the load  126  creating an air space  130  between the buffer and the load. The nail  14  is advantageously mounted in an angle bracket  18  which will be affixed to the surface of material  1  (which may be concrete, wood, masonry, steel, etc.) by the nail  14  after the nail is driven. In addition, as shown in  FIG. 11 , a rubber seal  132  is preferably arranged on the nail  14  between the bracket  18  and the plastic cap  16 . The seal  132  and the buffer  124  both act to silence the explosion of the load  126  without significantly diminishing the impact on the nail. The plastic cap  16  also tends to guide the nail during penetration allowing the nail to penetrate more deeply into hard surfaces. The plastic cap is preferably provided with outwardly extending flutes or wings  134 . The wings help hold the fastener in the tool until the fastener is fired. 
         [0063]    Operation of the tool and fastener is illustrated in the sequence of  FIGS. 12-19 . In operation, an explosively driven fastener  12  is inserted into the distal end of the muzzle  106  throughbore  107 . More particularly, the plastic cap is inserted into the throughbore until the bracket  18  abuts the distal end of the muzzle  106 . The fastener bracket  18  is aligned with a surface to be penetrated by the nail  14  ( FIG. 12 ) and the tool base  36  is pushed distally ( FIG. 13 ) towards the surface (from right to left as shown in the Figs.). This is typically accomplished by an operator pushing a pole (not shown) which is attached to the threads  40  of the tool base  36 . Also, this movement is typically upward into a ceiling structure. Distal movement of the tool base  36  moves the main body  22 , the main spring  56  and the firing pin assembly  48 ,  58  all distally. Distal movement of the firing pin assembly causes distal movement of the firing pin assembly guide  76  ( FIGS. 13 and 14 ) since they are locked together by the radially biased trigger  88 . The distal end  80  of the firing pin assembly guide  76  abuts the proximal end of the fastener (the plastic cap  16  containing the load  126 ,  FIG. 13  et seq.) which prevents further distal movement of the firing pin assembly guide  76 . In addition, distal movement of the main body  22  causes compression of the reset spring  104  ( FIG. 14 ) as it is biased against the inner sleeve  94  which is prevented from distal movement by the muzzle  106  which abuts the fastener bracket  18  which abuts the surface to be penetrated. Further distal movement of the tool base  36  therefore compresses the main spring  56  against the firing pin holder  48  ( FIG. 14 ) and continues to move the main body  22  distally relative to the firing pin assembly  48 ,  58  and guide  76 , also further compressing the reset spring  104 . Continued distal movement causes the internal trigger key  26  of the main body  22  to enter the keyway  86  of the firing pin assembly guide  76  and ride over the radially biased trigger  88  depressing the trigger radially inward ( FIG. 14 ). Radial depression of the trigger  88  disengages the firing pin assembly  48 ,  58  from the firing pin assembly guide  76  allowing it to move freely longitudinally distally ( FIG. 15 ). The compressed main spring  56  then forces the firing pin assembly  48 ,  58  in the distal direction with the firing pin  58  traveling through the distal end  80  of the firing pin assembly guide  76  (which is held stationary against distal movement by the fastener, plastic cap  16 ) until the firing pin  58  exits the firing pin assembly guide  76  and impacts the proximal end of the fastener striking the explosive load  126  ( FIG. 16 ). The load  126  explodes forcing the nail  14  out of the muzzle  106  and into the surface to be penetrated. 
         [0064]    When the tool is moved away from the fastener, the springs  56  and  104  move the parts back to their original positions ( FIG. 17 ) with the trigger  88  engaging the circular stop  90 . In some cases, the plastic cap  18 , or a portion of it will remain attached to the nail head as shown in  FIG. 17 . In some cases, the plastic cap or a portion of it will remain in the bore  107  of the muzzle  106  as shown in  FIG. 18 . These remnants of the fastener are easily ejected from the tool by moving the muzzle  106  and inner sleeve  94  proximally toward the main body  22  against the action of reset spring  104 . This brings the end of the muzzle closer to the end of the firing pin assembly guide as shown in  FIG. 19 , thereby ejecting any remnants of the plastic cap. 
         [0065]    The apparatus according to the invention obviates the need to purchase separate loads for the tool and there is no need to place fasteners and loads into the tool separately. The tool is easily assembled and disassembled for cleaning and is preferably made entirely of stainless steel. Since the nail is directly propelled by the explosive rather than by a driver propelled by explosive, better nail penetration is achieved. In addition, there is no need to replace drivers which wear after repeated impact against nail heads. Further, the absence of a driver results in the absence of vibration when the tool is in use. This results in greater accuracy and less noise. The nail penetrates much faster and thus results in a lower failure rate. The slim profile of the tool allows it to fit into tight spaces such as between ductwork, pipes, etc. The tool automatically triggers and is automatically reset after use. Interchangeable muzzles obviates the need for different loads. The force of a standard load can be regulated by the choice of muzzle. 
         [0066]    The construction of the tool renders it lighter. The tool in combination with the provided fastener is quieter than powder actuated tools. This is important when working in an occupied building. The plastic cap on the nail contains the energy that would otherwise escape and cause noise. 
         [0067]    The tool  10  according to the invention can be used with prior art fasteners as shown in  FIGS. 20-25 . Prior art fasteners  1 ,  2 , and  3  can be used in the tool  10  with an explosive load  212 . The load  212  is substantially the same as the load described above but not connected to a nail. The load  212  is loaded into the apparatus  10  first and then the fastened is inserted on to of it. 
         [0068]    According to the presently preferred embodiment, the explosive load  212  (as well as the plastic cap  16 ) is made of an ABS plastic container having the following properties: 
         [0000]    
       
         
               
               
               
               
             
           
               
                 TABLE 
               
               
                   
               
               
                 Property 
                 Test Method 
                 Units 
                 Number 
               
               
                   
               
             
             
               
                 Tensile Strength 
                 ASTM D-638 
                 kg/cm 2   
                 350-500 
               
               
                 Flexural Strength 
                 ASTM D-790 
                 kg/cm 2   
                 550-650 
               
               
                 IZOD Impact Strength 
                 ASTM D-256 
                 kg-cm/cm 
                 25-35 
               
               
                   
               
             
          
         
       
     
         [0069]    This construction of the container helps optimize the impact of the explosion while minimizing noise. 
         [0070]    The contents of the plastic container (i.e. nitrocellulose load  126 ) preferably has the following formulation: 94% Nitrocellulose, 5% Methocel and color agent, 1% Diphenylamine. 
         [0071]    There have been described and illustrated herein several embodiments of an apparatus for installing explosively driven fasteners and fasteners for use therewith. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed.

Technology Category: 7