Abstract:
A hand tool capable of wrapping and unwrapping wires on terminals is provided with a an electrically-insulating drive housing or adaptor and coupling which insulate the bit, and sleeve if present, and driver from the housing and the gear train thereby protecting the user in case of accidental contact between the housing and an active electrical source while the tool is being used. The coupling tightly couples together divided drive shaft portions to maintain the electrical isolation.

Description:
This invention relates to a wire wrapping hand tool, and in particular to a tool adapted for hand-operation for wrapping or unwrapping wires around electrical terminals. 
   BACKGROUND OF THE INVENTION 
   Wire wrapping tools are well known in the art and are commonly used nowadays for the making of connections to terminals on a printed circuit board (PCB). See, for example, U.S. Pat. Nos. 4,177,555, 4,194,700, and 4,620,574, whose contents are herein incorporated by reference, as examples of such tools. The wrapping tool wraps the wire around a sharp-cornered terminal which crushes any oxide layer between the terminal and wire and provides a tightly-held oxide-free metal-to-metal contact of the wire to the terminal. When the tool is reverse driven, with a different active bit, it can be used to unwrap the wire from the terminal. The typical tool is a wire-wrapping gun containing what is known as a removable bit and sleeve. The latter is typically fixed, and the bit rotates, usually clockwise (CW), within the sleeve. Wire from a spool, for example, is fed through the sleeve to the bit face. The bit has a bore for receiving the terminal, and when the bit is rotated around the terminal, structure on the bit face grabs the wire and wraps it around the terminal. The bit and sleeve are replaceably held on the tool by a front-facing collet or chuck at the distal end of the tool (locations on the tool are with respect to the handle end) which when tightened holds the sleeve within the tool. The bit is held in place within the sleeve by a shoulder on the bit. Replacement of the bit and sleeve is accomplished by loosening of the collet to release the bit and sleeve so it can be removed and replaced. Reasons for replacing include wrapping on a different size of terminal. 
   So far as we know, all current tools suffer from the problem of possible electrical shocks to the tool user should the terminal be electrically active and the user contacts any metal screws on the tool, or the metal shaft, or the metal trigger gear. Some manufacturers attempt to solve this problem by surrounding a metal tool housing and handle with a plastic electrically-insulated coating, or constructing the tool frame from plastic. However, this is only a partial solution since the trigger gear is still exposed via the bit and sleeve and electrical shock to the user is still possible if the user contacts any part of the metal trigger while the trigger gear contacts an active terminal. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the invention to provide an improved hand tool capable of wrapping or unwrapping wires on terminals and substantially free of the problem of inadvertent electrical shocks to the user. 
   In accordance with an aspect of the invention, the wrapping/unwrapping tool of the invention incorporates an electrically-insulating drive housing or adaptor and coupling which insulate the bit, and sleeve if present, and driver from the housing and the gear train thereby protecting the user in case of accidental contact between the housing and an active electrical source while the tool is being used. 
   For simplicity, the description hereafter shall mainly refer to the tool of the invention serving as a wrapping tool, but it will be understood that the same tool with the same advantages can also serve as an unwrapping tool as is well-known in the art. Similarly, the description hereafter shall mainly refer to the tool of the invention as a manual hand tool but it will also be understood that the tool can be power-driven, using batteries or electrical motors. 
   The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described the preferred embodiments of the invention, like reference numerals or letters signifying the same or similar components. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a partially sectioned side elevational view of a preferred embodiment of the wire-wrapping tool of the invention; 
       FIG. 2  is a sectional view from the top of the wire-wrapping tool of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Reference will now be made in detail to a presently preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. 
   A preferred embodiment of the improved wire-wrapping tool, which in this embodiment is a manually-operated wire wrapping tool, is represented generally by numeral  10 . As can be seen from the drawings, the manually-operated wire wrapping tool  10  includes a frame  12 , and a hand-actuated lever or trigger  14  movably mounted on the frame  12  at a pivot  16 . The frame  12  is typically made in two complimentary parts  12 A,  12 B, held together by metal screws or pins  18 . Preferably, the frame is made of aluminum metal and the connecting screws or pins likewise of metal. Alternative methods of making the frame and assembling same are within the scope of the present invention. The frame preferably is coated with a good electrically-insulating coating but this does not eliminate the problem of electrical shocks via contact by the bit and sleeve which are typically also of metal with an active terminal. 
   The hand actuated lever  14 , having a gear rack  20  formed at one end, is adapted for comfortable squeezing by hand. Spring members  26  are mounted about the pivot  16  such that force from the springs biases the lever  14  in a direction outwardly from the frame  12 . 
   When squeezed, the lever  14  pivots on the pivot  16  towards the rear of the frame  12 , and the spring members  26  are thereby further tensioned. The squeezing movement provides power for the wire-wrapping tool  10  as will be further described below. The gear rack  20  is formed or mounted near the end of the lever  14  opposite the pivot  16  and includes a plurality of teeth (some not shown) which intermesh with the teeth of a spur gear  28  which is part of a rotatable drive assembly  30 . The specific construction of the drive assembly  30  which incorporate aspects of the present invention will be described in greater detail below. Generally, these assemblies comprise a spur gear, a driven gear and various translational gears that are designed to impart rotary motion to an output shaft or bit. In the presently preferred embodiment, the rotatable drive assembly comprises a spur gear  28  integrally formed and coaxial with a driven gear  32 , a pinion gear  34 , and a bearing  36 . 
   In the known constructions, the pinion gear  34  is integral with a drive shaft all supported by a metal drive housing  40 . More on this later. The gear rack  20  drives the spur gear  28  and the driven gear  32  in a counter-clockwise direction ( FIG. 1 ) thereby driving the pinion gear which drivingly engages the drive shaft, such as by means of a key. The drive shaft is rotatably mounted in the drive housing  40  which is held fixedly in place in the frame  12  by any suitable means. An adjustable collet nut  44  is adapted to engage a threaded end  38  of the drive housing  40  to secure a terminal wire connecting bit/sleeve assembly  45  when inserted into the drive housing  40  to engage the drive shaft. 
   Mounting of the gearing and drive assembly within the frame can be by conventional means except for the changes that will be described in detail below as part of the invention. 
   In operation, which is the same for the known tools, when the lever  14  is squeezed toward the rear of the frame  12 , the gear rack  20  drives the spur gear  28  and driven gear  32  and the rotatable drive assembly. A backstop  46 , comprised of a tensioned bar or leaf spring positioned within the frame  12 , is contacted by the gear rack  20  as it is squeezed toward frame  12 . The backstop  46  aids in avoiding impact of the gear rack  20  against the frame  12 . The backstop  46  exerts force against the gear rack  20  and is mounted to permit travel a short distance with increasing resistance against the gear rack  20 , thus encouraging the gear rack  20  to slow down as it approaches the frame  12 . When pressure on the lever  14  is released, the spring members  26  cause the lever  14  to return to its normal rest position. The lever  14  comes to rest when the gear rack  20  abuts against a gear rack stop  48  mounted in the frame  12 . Preferably, a shock absorbing piece of resilient material, such as rubber, can be included on one side of the stop  48  to help absorb impact or to act as a spacer. 
   As indicated above, an electric motor, activated by batteries or line voltage can be substituted to drive the bit via a known gear system. The bit end, which has a flat  22 , sits in and rotates within the outer sleeve  23 . 
   As indicated earlier, to avoid the electrical shock problem, in accordance with an aspect of the invention, the drive shaft is physically spit into two axially-aligned portions  30 A,  30 B. The proximal part  30 A is integral with the pinion  34  and will be hereafter from time to time referred to as the first shaft portion or pinion shaft. The distal part  30  B likewise has a flat to engage and couple to the flat  22  on the bit and thus drives the latter, and will be hereafter from time to time referred to as the second shaft portion or drive shaft. Each shaft portion  30 A,  30 B is supported by a bearing  50 A, respectively  50 B, journaled for rotation within the drive housing  40 . Both shaft parts  30 A,  30 B are tightly coupled together by a surrounding coupling  52 . The latter is secured at its right proximate end ( FIG. 1 ) to and rotates with the pinion shaft  30 A and at its left distal end ( FIG. 1 ) to and rotates with the drive shaft  30 B. The connection can be by way of key or pin, but it is preferred to use a press-fit connection, which it is surprisingly found to be sufficiently strong to withstand any normal pulling or twisting forces during use. Preferably, this is obtained by knurling a portion of the drive shaft (indicated by the thicker line  25  in  FIG. 2 ) and forcing it into the complementary bore of the hollow coupling  52 . The pinion shaft fits on the other end and uses the same knurl and press fit arrangement. The coupling  52  is constituted of an electrically-insulated plastic such as ABS and thus the two shaft portions  30 A,  30 B are electrically-insulated from one another. 
   As a further feature of the invention, the drive housing  40  is also constituted of an electrically-insulated plastic such as ABS and thus the entire frame metal parts are electrically-insulated from the bearing  50 B, the bit/sleeve combination  45 , the split drive shafts  30 A,  30 B, and the gear train  20 ,  28 ,  32 ,  34 . This combination of the electrically-insulated split shaft coupling  52  and the drive housing  40  accomplishes the goal of ensuring that no inadvertent contacting of the bit/sleeve to an electrically active terminal will cause an electrical shock to the tool operator. As additional protection, the collet nut  44  is also made out of plastic and this helps to avoid electrical shorts between terminals. 
   As still a further feature of the invention, the assembled rotating components within the drive housing  40  are retained within the frame by frame tabs  60  ( FIG. 2 ) and pins  62 , one of which is shown in  FIG. 2 . During the assembly process, after the pin  62  has been fixed to the drive housing  40 , the gears are disengaged and the pinion shaft  30 A and drive shaft  30 B are together rotated until the bit-engaging flat on the distal drive shaft  30  B has acquired a preset (rotary) orientation. This preset orientation ensures that when the rotating components within the drive housing  40  stop rotating during use of the gun, the preset flat orientation will always have the same orientation to receive and couple to the flat  22  on the bit. Then, the assembly is completed and the gears reengaged. The tabs  60  at the proximal end keep the bearing  50 A from moving out of the drive housing  40  and maintain the gears assembly in its final engaged relationship, once set. This feature reduces assembly time and also makes disassembly very easy when required. 
   The plastic material of the drive housing  40  is tough enough so that screw threads  38  provided at its distal end will resist damage due to frequent tightening and loosening of the sleeve-holding collet  44 . The latter, preferably electrically-insulated, can also be electrically-conductive if desired, with only a small loss in protection as it does not affect the electrically-insulating effect of the electrically-insulated drive housing  40  and shaft coupling  52 . 
   Conventional wrapping bits and sleeve or unwrapping bit can be used with the tool of the invention. 
   While the invention has been described in connection with preferred embodiments, it will be understood that modifications thereof within the principles outlined above will be evident to those skilled in the art and thus the invention is not limited to the preferred embodiments but is intended to encompass such modifications.