Abstract:
A tool capable of wrapping and unwrapping wires on terminals is provided with a quick-release mechanism to allow rapid and simple replacements of bits and sleeves used for the wrapping and unwrapping functions. This feature uses a bit driver comprising a camming surface that cooperates with a collet having a tapered split end for holding the bit and sleeve loosely or a gripping relationship for driving the bit. A novel bit/sleeve combination is capable of wrapping wires on terminals when rotated in one direction and unwrapping wires from terminals when rotated in the opposite direction. The tool also features a motor reversing switch for allowing the tool to be used both for wrapping and for unwrapping wires, with the reversing switch located in a protected region at the rear of the tool to prevent accidental activation. The same tool housing can also be used for fabricating both battery operated as well as AC operated tools.

Description:
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 and 4,194,700, 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 providing a tightly-held oxide-free metal-to-metal contact of the wire to 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 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. 
     Tools also exist for unwrapping a wrapped wire from a terminal. A typical tool has a spiral groove cut into the end of an unwrap bit. When the unwrap bit is rotated counterclockwise (CCW) on the terminal, the bit face grabs the end of the wire and feeds it into the spiral groove allowing it to be unwrapped from the terminal. See U.S. Pat. No. 4,064,581, whose contents are herein incorporated by reference, which describes a hand tool having a wrapping bit at one end and an unwrapping bit at the opposite end. Using a gun-type power tool for wrapping and unwrapping requires that a first bit and sleeve is used for wrapping, and to unwrap the first bit and sleeve must be removed and replaced by an unwrap bit and sleeve that acts as a bushing for the bit, and the power tool must be capable of both CW and CCW operation. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide an improved tool capable of wrapping and unwrapping wires on terminals. 
     Another object of the invention is a tool provided with a quick-release mechanism to allow rapid and simple replacements of bits and sleeves. 
     Still another object of the invention is a novel bit/sleeve combination capable of wrapping wires on terminals when rotated in one direction and unwrapping wires from terminals when rotated in the opposite direction. 
     In accordance with a first aspect of the invention, the tool of the invention features a quick-release for the bit/sleeve. 
     In a preferred embodiment, a bit driver comprises an outwardly facing concave surface that cooperates with a collet having a tapered split end adapted to engage the concave surface and held in loose engagement therewith by a biasable collet housing in a first position. When the collet housing is moved to a second position, it is biased toward the collet and the collet&#39;s tapered split end is cammed by the concave surface into a gripping relationship with a sleeve tightly holding the sleeve on the tool while the bit is driven. To release the bit and sleeve it is merely necessary to move the collet holder from its second to its first position, which preferably is accomplished by rotation of the holder no more than 30°. 
     In accordance with a second aspect of the invention, the tool of the invention features a motor reversing switch for allowing the tool to be used both for wrapping and for unwrapping wires. 
     In a preferred embodiment, the reversible switch is located in a protected region at the rear of the tool to prevent accidental activation. 
     In accordance with a third aspect of the invention, the tool of the invention features a novel bit/sleeve construction that allows the same combination to be used for unwrapping or for wrapping wires without having to replace the bit or sleeve. 
     In a preferred embodiment the combined wrap/unwrap bit/sleeve comprises a bit having a bit face that will wrap around a terminal a wire fed to it through the sleeve and also provided adjacent the bit face with a helical groove capable when exposed of unwrapping a wrapped wire, a sleeve within which the bit rotates, and an adaptor or sleeve extension surrounding the sleeve and cooperating with the sleeve to hold it in either if two positions, a first position when the sleeve projects forward over the bit face and surrounding the helical groove and can provide the usual sleeve function of feeding a wire to the bit face during wrapping, and a second position when the sleeve is moved rearward to expose the helical groove allowing it to carry out its unwrap function. 
     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 partly cross-sectional side view of one form of wrapping/unmwrapping tool according to the invention; 
     FIG. 2 is a partial front view of the tool of FIG. 1; 
     FIG. 3 is a partial view of the tool of FIG. 1 shown with a bit/sleeve loosely mounted for removal within the tool; 
     FIG. 4 is a partial view of the tool of FIG. 1 shown with a bit/sleeve tightly mounted within the tool ready for use; 
     FIG. 5 is exploded perspective view of the quick-release mechanism of the tool illustrated in FIG. 1; 
     FIG. 6 is a front view of the bit face of a combined wrap/unwrap bit/sleeve according to the invention; 
     FIG. 7 is a perspective view and FIG. 8 is a side view of just the bit end of the combined wrap/unwrap bit/sleeve of FIG. 6; 
     FIG. 9 is a cross-sectional side view of the combined wrap/unwrap bit/sleeve assembly of FIG. 6 shown in its wrap position and FIG. 10 is a similar side view showing it in its unwrap position; 
     FIG. 11 is exploded perspective view of the combined wrap/unwrap bit/sleeve assembly of FIG. 6; 
     FIG. 12 is a partial side view showing the quick-release mechanism of the tool illustrated in FIG. 1 in its tightened position, and FIG. 12A shows it in its loosened position; 
     FIG. 13 is an enlarged side partly cross-sectional view of the rear end of the tool of FIG. 1 showing the protected mounting of the reversing switch in a first position and FIG. 14 shows it in its second position; 
     FIG. 15 is a partial circuit schematic showing how reverse motor operation can be achieved; 
     FIG. 16 is a partial side view similar to FIG. 1 showing the housing interior when the tool is manufactured for AC operation instead of battery operation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A wrapping/unwrapping tool  10  according to one form of the invention is shown in FIG.  1 . It includes a gun-type housing  12  comprising a main body  14  supported on a handle  16 . An electric motor  18  drives a bit  20  via a known gear system  22 . The bit end, which has a flat  24  (FIG.  3 ), sits in a drive member  26  mounted for rotation within a fixed collet bushing  28 . The motor and drive gear assembly are conventional and not part of the present invention. The motor  18  is activated by a trigger  30  which when pulled closes a circuit which includes a battery power source  32  and a reversing switch  34  at the rear of the housing  12 . 
     A quick-release mechanism  36  for the bit and sleeve is shown in FIG.  5 . It comprises the collet bushing  28  having an interior concave—preferably tapered—forwardly-facing camming surface  38  (FIG.  3 ); a collet  40  having a tapered split end  42 , serving as collet jaws, configured with a rearwardly-facing taper to engage the camming surface  38  on the bushing  28 , a recessed region  44  for receiving a compression spring  46  and a forward cylindrical part  48 ; and a collet housing  50 . The collet bushing  28  is mounted to the housing main body  14 , the spring  46  mounts in the recessed region  44  of the collet  40 , and the collet housing  50  is mounted on the collet bushing  28  by means of a pin  52  secured to the bushing side  28  via an opening  53  and engaging a right-angle slot  54  in the side of the collet housing  50 . As is evident from FIG. 3, the interior of the collet housing  50  closely surrounds the exterior  56  of the bushing  28 , the collet  40  is seated in the space inside the collet housing  50 , and the spring  46  biases the collet  40  toward bushing  28  by a rim  58  on the collet housing  50 . A sleeve  60  is received by a bore  62  in the collet  40  and a concentric bore  64  in the bushing  28 . As usual, a bit  20  is rotatably mounted within the sleeve  60 , and is held axially by a shoulder  66 . 
     FIG. 3 shows the collet housing  50  in its first bit/sleeve release position, with the collet housing projecting forward by the action of the compression spring  46 . The pin  52  is in a longitudinal portion  68  of its slot  54  (FIG.  12 A), with the slot portion  68  closed off by a wall as a stop position for the pin  52 . In this position, only a small spring pressure is exerted on the collet split end  42  and the slotted collet jaws  42  remain open allowing the bit and sleeve to be removed from the tool. FIGS. 4 and 12 show the collet housing  50  in its second bit/sleeve gripping position, with the collet housing forced into the tool housing against the compression spring  46  pressure. This is achieved by simply pushing and rotating the collet housing  50  CW about 15° relative to the bushing  28  until the pin  52  is moved into a lateral portion  70  of its slot  54  and locks in that position by the closed end of the slot wall. This action forces the collet tapered split end  42  tightly against the concave surface  38  of the bushing  28  closing the collet jaws tightly against the sleeve  60  gripping it tightly and preventing rotation. Now, when a wire is fed into the sleeve in the normal manner until the free end reaches the bit face, the bit pushed onto a terminal, and the motor activated, the wire will be wrapped around the terminal in the normal manner. To remove the bit/sleeve, the collet housing  50  is rotated CCW about 15° relative to the bushing  28  until the pin  52  is moved back into the longitudinal portion  68  of its slot  54  relieving the spring pressure which allows the collet jaws to relax and allows the bit/sleeve to be removed. 
     A conventional wrapping bit and sleeve or unwrapping bit can be used in this aspect of the invention, or the novel combined wrapping/unwrapping bit/sleeve of FIGS. 6-11 according to the invention can be used. 
     As explained earlier, the combined wrapping/unwrapping bit/sleeve of the invention allows both the wrapping and unwrapping functions to occur without removing the bit/sleeve from its mounted position in the tool. The wrap/unwrap bit/sleeve assembly  74  (FIG. 11) comprises a bit  76 , a shortened, axially-movable sleeve  78 , and an adaptor or sleeve extension  80  whose position relative to the sleeve  78  controls whether the combination can wrap or unwrap. The back end of the bit  76  is conventional with the flat  24  and shoulder  66 . The groove  82  is for the wire to be wrapped. The bit working end  84  at the left has an outer helical groove  86  configured when exposed for grabbing the wrapped wire end and unwrapping it. The bit face  88  is configured similarly to existing bit faces in that it has structure  90  for pushing a wire fed along the groove  82  forward and then coiling it around a terminal when the bit is rotated CW. The helical groove end  92  which terminates at the bit face does not interfere with the wrapping action because, during operation, as illustrated in FIG. 9, the sleeve end  94  overlies the bit face  88  and covers the helical groove  92 . Moreover, the bit is rotating CW so that the feeding wire which exits the sleeve  78  via a spout  96  has no opportunity for entering the groove beginning at  92 . The sleeve  78  is maintained in a first position for wire wrapping as shown in FIG. 9 by a first groove  98  engaging an O-ring  100  mounted on the inside of the adaptor  80 . A pin  102  mounted in the side of the adaptor  80  rides in a slot  104  and prevents rotation of the sleeve  78 . 
     When the user desires to exercise the unwrap function, the sleeve  78  is simply pushed rearward in a linear motion until a second groove  106  is engaged by the O-ring  100  retaining the sleeve in its second position as shown in FIG.  10 . The right end of the adaptor  80  is against the bit shoulder  66  preventing movement of the adaptor. This action exposes the helical groove  86 . Now, when the bit is rotated CCW, the exposed end  92  of the spiral groove is capable of grabbing the wire end and unwrapping it from its terminal. The slot  108  at the rear of the adaptor  80  allows entrance of the feeding wire into the longitudal groove  82  of the bit during the wrapping function. The spiral groove behaves during its unwrapping function similar to the manner in which the known unwrap tool operates. Similarly, the bit face when rotated CW behaves during its wrapping function similar to the manner in which the known wrap tool operates. 
     As is clear from the foregoing, for use with the combined wrap/unwrap bit/sleeve, it is desirable for the tool  10  to be capable of both CW and CCW rotation. A DC motor  18  can be incorporated with that capability provided that a circuit and switch are provided that will, in effect, reverse the polarity of the operating voltage applied to the motor terminals. A further feature of the present invention is to provide the circuit and the operating reversing switch in a protected position so that it cannot be accidentally activated when the tool accidentally hits a hard surface or is placed down on a hard surface so as to activate the switch. In a preferred embodiment, the circuit is provided on a small circuit board  110  mounted at the rear behind the motor  18 , and the reversing switch  112  which cooperates with the circuit to control the rotation direction of the motor is mounted on the tool housing  14  at its rear, behind the circuit board  110  and in a recessed region  116  molded into the housing  14 . Reference  34  refers to the switch activator button which can be moved from an upper position as shown in FIG. 13 for CW rotation, to a lower position as shown in FIG. 14 for CCW rotation. The switch body  112  is preferably mounted on the circuit board  110 . The recessed region  116 , as shown, is provided by an annular ridge  118  whose height parallel to the tool axis and in a direction away from the tool exceeds that of the switch button  34 , preventing the latter from being accidentally activated. The location of the switch  34  at the rear makes it very convenient for the user to change motor rotation by using the thumb on the hand holding the gun to operate the switch. FIG. 15 is a circuit schematic of one form of circuit that can be used to reverse motor rotation with a simple double pole/double throw switch  120 . 
     FIG. 16 illustrates another feature of the invention, namely, configuring the gun handle  16  so that it is relatively simple to manufacture a tool for either battery operation or AC operation via a power line cord. FIG. 1 shows the tool interior made for battery operation. The positive terminal of the battery  32  is connected via wire  122  to the circuit board at  124  and also to a contact  126  at the trigger  30 . The other half  128  of the contact is connected to one of the motor terminals at  129 . The other of the motor terns is connected to the circuit board at  130 . The negative side of the battery is connected to the circuit board at  134  via wire  132 . As shown in the circuit schematic of FIG. 15, with reversing switch in position A, positive battery power is supplied to the motor&#39;s upper terminal, and with reversing switch in position B, negative battery power is supplied to the motor&#39;s upper terminal, reversing its rotation. When it is desired to manufacture the same tool but powered by AC power, the same housing  14  can be used. The terminals  126 ,  128  and the battery contacts are replaced by a second circuit board  136  connected to the part  138  which is now a simple on/off toggle switch, and a support structure  140  for a conventional AC line cord  142  is plugged into what previously was the support  144  for the battery. The second circuit board  136  in a conventional manner rectifies the AC line input. Several of the wire connections change (cf: FIGS.  1  and  16 ), but the changeover is remarkably simple and very inexpensive since the same mold can be used for both tool housings. Typically, the tool housings are of molded plastic. Most known hand tools are differently configured when manufactured for battery or AC operation. 
     It is understood that the circuit details are not critical and other arrangements can be chosen to achieve the function of allowing reversible motor rotation. 
     Among the advantages of the invention described herein are ease of operation as a wrap or unwrap tool which merely requires axially-repositioning of the movable sleeve  78  and operation of the reversing switch  34 , protection against inadvertent activation of the reversing switch  34  by its mounting inside of a protecting ridge  118 , quick-release and mounting of a bit/sleeve assembly by a small movement of a collet housing  50 , and use of the same gun housing for fabrication of either a battery operated or an AC powered tool. 
     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.