Patent Publication Number: US-6212758-B1

Title: Wire termination tool having an improved impact shaft

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to application equipment used for the mass termination of wires, and more particularly to a tool for use in mass termination of wires in a telephone cross-connect system. 
     BACKGROUND OF THE INVENTION 
     Telephone cross-connect systems, e.g., the 110 connector system, are used to manage main cross-connect and horizontal administration fields in private premises telecommunications equipment. Applications of the 110 connector system have included general building, wiring, premises distribution systems, local area networks, and other private area network installations. The main cross-connect is typically located in an equipment room of a building, and provides termination and cross-connection of network interface equipment, switching equipment, processor equipment, and backbone (riser or campus) wiring. Horizontal cross-connect is typically located in the telecommunications closet of a commercial building, and provides termination and cross-connection of horizontal (to the work area) and backbone wiring. Cross-connects allow for easy administration of routing and rerouting common-equipment data circuits to various parts of a building or campus. 
     A prior art 110 cross-connect system includes a field-wired cable termination apparatus that is used to organize and administer cable/wiring installations. A typical 110 cross-connect system of the type known in the art includes a wiring block having a plurality of terminal blocks that are field terminated or pre-terminated during manufacture. Assemblies of such wiring blocks often require as many as nine hundred pairs of wires to be terminated. In order to terminate such a large number of wires cost effectively, various tools have been developed in the art for “mass termination” of wires. 
     For example, a 788H tool includes a five-pair impact tool which is capable of terminating five or more pairs of wires in one insertion stroke of the tool. The 788H mass termination tool has been used for simultaneously seating and trimming five pairs of conductors on an index strip of a wiring block, and for seating a 110C connecting block onto a wiring block for termination. Such prior art tools include a cylindrical handle with a removable head frame, which attaches to the handle with a twist and lock type engagement. The head includes a stuffer and a removable cut-off blade section which allows for replacement of a cutting blade. The stuffer and cut-off blade section are housed in removable the head frame through which the handle is engaged, via a through-bore or the like engagement feature. The removable cut-off blade section is also reversible to allow for seating conductors and for combining an insert/trim function at installation. 
     Some prior art tools that are similar to the 788H, such as the 788E, are powered by 120 volt alternating current based motors, and have an impact function that is activated by a trigger on a handle. These tools are often used in factory production and other large installations where it is not practical to use a manually activated tool, such as the 788H, because of repetitive motion injuries and speed of assembly. There has been a consistent problem in the art with such mass termination tools because of the large number of cycles required of the tool during operation. More particularly, manufacturing facilities that produce the 110 cross-connect system will manufacture approximately 10,000 preassembled 110-rack systems or more, per year. Such a manufacturing output equates to fifty million or more tool cycles for a 788-type tool at the manufacturing site. Components for such systems that are sold to outside assemblers often require in excess of thirty million tool cycles. Unfortunately, tools such as the 788, that are based on electromotive forces, have an average life span of about 1 week in a manufacturing environment. Such short life spans have required the rebuilding or replacement of tools frequently, at several hundred dollars cost per tool. This retooling produces frequent down time and high replacement costs, along with a concomitant increase in the cost of manufacturing. 
     There is a need for a high cycle, low cost mass termination tool adapted for use in connection with a 110 cross-connect system that is capable of extended life. 
     SUMMARY OF THE INVENTION 
     The present invention provides an impact shaft for use in a pneumatic wire termination tool. The preferred tool has a handle, a pneumatically driven piston and a head frame for engaging and terminating a plurality of wires to a corresponding connector at the same time. The impact shaft comprises a plurality of coaxially arranged cylindrical sections positioned end to end, including a dowel pin positioned at a first end and a head frame locator having the dowel pin projecting from a first end and an extension portion projecting from a second end, wherein the dowel pin and the head frame locator are sized to operatively engage the head frame. A spring register portion having a first end from which the extension portion projects, includes a plurality of facets arranged for engagement with a biased portion of the tool so as to maintain the rotational orientation of the impact shaft relative to the handle. An air barrel shaft projecting from a second end of the spring register is operatively engaged by the pneumatically driven piston. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be more fully disclosed in, or rendered obvious by, the following detailed description of the preferred embodiment of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein: 
     FIG. 1 is a perspective view of a mass-termination tool including an impact shaft formed in accordance with the present invention; 
     FIG. 2 is a perspective view of the impact shaft shown in FIG. 1; 
     FIG. 3 is a top plan view of the mass-termination tool, including an impact shaft, as taken along line  3 — 3  in FIG. 1; and 
     FIG. 4 is a side elevational view, partially in section and partially broken-way, of the impact shaft of the present invention assembled to a tool handle, as taken along line  4 — 4  in FIG. 3, and showing a general representation of a head frame used in connection with the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following description of the preferred embodiments of the invention are intended to be read in connection with the foregoing drawings and are to be considered a portion of the entire written description of this invention. As used in the following description, terms such as, “horizonal”, “vertical”, “left”, “right”, “up”, and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.) simply refer to the orientation of the structure of the invention as it is illustrated in the particular drawing figure when that figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate. Also, the terms “connected” and “interconnected,” when used in this disclosure to describe the relationship between two or more structures, mean that such structures are secured or attached to each other either directly or indirectly through intervening structures, and include pivotal connections. The term “operatively connected” means that the foregoing direct or indirect connection between the structures allows such structures to operate as intended by virtue of such connection. 
     Referring to FIGS. 1-5, a 788 type mass termination tool formed in accordance with the present invention comprises an impact shaft  20  and an air tool handle  30 . A termination head used in connection with a prior art 788E tool may be used with impact shaft  20 , and typically includes a head frame (indicated generally by the reference numeral  21  in FIG.  4 ), a stuffer, and a removable cut-off blade section all of which are well known in the art and therefore not shown in the various figures. 
     Impact shaft  20  of the present invention is formed from a solid blank of tool steel, e.g., S7 tool steel hardened to Rockwell 50-52 C, and generally comprises a plurality of coaxially arranged cylindrical sections positioned end to end so as to form a shaft of varying cross-sectional diameter (FIG.  2 ). In one embodiment, impact shaft  20  includes a dowel or spring pin  45 , a head frame locator  50 , an extension  55 , a spring register  60 , and an air barrel shaft  65 . Dowel or spring pin  45  projects outwardly from a central portion of head frame locator  50  at a first end of impact shaft  20 . Dowel or spring pin  45  may include a central bore  46 , and is sized and shaped to locate and engage a complementary feature on a removable cut-off blade (not shown), via a through-bore in the rear portion of a 788E head frame. 
     Head frame locator  50  projects outwardly from a central portion of extension  55 , and is sized and shaped so as to be accepted within the through-bore in the rear portion of a head frame. Head frame locator  50  has a diameter that is smaller than extension  55 , but larger than dowel or spring pin  45 , and includes a ball detent  66  located on a side surface  52  which is spring loaded so that it will engage a corresponding feature within the through-bore of the head frame. A frustoconical taper  53  forms an intersection transition between head frame locator  50  and dowel or spring pin  45 . Extension  55  projects outwardly from a central portion of spring register  60 , and supports and positions head frame locator  50  and dowel or spring pin  45 . Extension  55  has a diameter that is smaller than spring register  60 , but larger than head frame locator  50 , and is substantially circular in cross-section. 
     Spring register  60  projects outwardly from a central portion of air barrel shaft  65 , and includes a faceted outer surface that defines a plurality of planar surfaces  69  (FIG.  2 ). Planar surfaces  69  form a polygonal cross-sectional profile which may be hexagonal or octagonal. Preferably, spring register  60  is formed having a rectangular or square cross-section, and then the corners are cut down so as to provide additional planar surfaces. Spring register  60  has a width that is larger than the diameter of extension  55  and air barrel shaft  65 . An annular shoulder  80  is positioned at the intersection of spring register  60  and air barrel shaft  65 , and has a diameter that is larger than the width of spring register  60 . A frustoconical section  82  of annular shoulder  80  tapers toward air barrel shaft  65 . Air barrel shaft  65  projects outwardly from the end of frustoconical section  82  of annular shoulder  80  to terminate at a rear end  86  of impact shaft  20 . Air barrel shaft  65  has a substantially circular cross-section that is similar in diameter to extension  55 , and may include a chamfer at rear end  86  to ease assembly to air tool handle  30 . 
     Referring to FIGS.  1  and  3 - 5 , air tool handle  30  is a pneumatically operated impact tool that comprises a pistol-style grip  90  including a trigger  91 . An air input orifice  92  is located at the base of pistol-style grip  90 , and communicates with a shaft engagement barrel  93 , via a conventional pressurized air conduit (not shown) defined within air tool handle  30 . An air valve actuated piston  95  is positioned in operative relation with the conventional pressurized air conduit, and projects outwardly from shaft engagement barrel  93 . Air valve actuated piston  95  includes a first section  97 , a second section  99 , and a shoulder support  101  located at the intersection of first section  97  and second section  99 . First section  97  has a larger diameter than second section  99 , and the outer surface  103  of second section  99  is threaded. Air valve actuated piston  95  is assembled to an operative end of shaft engagement barrel  93 , and includes a central bore  106  that defines a tapered counter-bore  107  that is sized and shaped to accept frustoconical section  82  of impact shaft  20  (FIG.  4 ). 
     A tension spring  110  is positioned in threaded coaxial relation to second section  99  of air valve actuated piston  95 . Spring  110  is typically a helical tension spring having a substantially cylindrical cross-section that is similar in diameter to shoulder support  101  of air valve actuated piston  95 . The coils of spring  110  are sized, shaped, and oriented so as to threadingly engage threaded outer surface  103  of second section  99 . A terminal coil of spring  110  is bent back upon itself so that it extends outwardly from a terminal end of spring  110  to form an impact shaft engagement arm  115 . Arm  115  includes a facet engagement section  117 . 
     With spring  110  threaded onto outer surface  103  of second section  99 , impact shaft  20  is assembled to air tool handle  30  by orienting the shaft so that rear end  86  is in confronting spaced relation to impact shaft engagement arm  115  and coaxially aligned with central bore  106 . Once in this position, impact shaft  20  is moved toward air tool handle  30  so that rear end  86  enters central bore  106 , via spring  110 . Chamfer  89  aids in aligning impact shaft  20  with central bore  106 . Impact shaft  20  continues to move toward air tool handle  30  until frustoconical section  82  of annular shoulder  80  engages the surface of tapered counter-bore  107 . 
     In this position, facet engagement section  117  of impact shaft engagement arm  115  engages a planar surface  69  of faceted outer surface of spring register  60  (FIGS. 1,  3  and  4 ). In this way, the orientation of the head frame may be maintained during a mass termination operation, since impact shaft  20  will be prevented from rotation due to the engagement of facet engagement section  117  with planar surface  69 . Often, the head frame must be reoriented, relative to air tool handle  30 , to accommodate the operator&#39;s position or comfort. In order to alter the orientation of the head frame, impact shaft  20  is rotated so that a different planar surface  69  is engaged by facet engagement section  117 , corresponding to a new orientation of the head frame. As a result of this construction, low duty cycle electric 788E mass termination tools may be replaced with high duty cycle air powered tools. 
     It is to be understood that the present invention is by no means limited only to the particular constructions herein disclosed and shown in the drawings, but also comprises any modifications or equivalents within the scope of the claims.