Abstract:
Tap and die devices are provided to repair internal and external threads, respectively. The tap and die devices are provided with components that coaxially align the tap and die to the nut or fitting being repaired. The tap and die devices are easily portable, compact tools that can be used in tight places.

Description:
BACKGROUND 
     Many piping and plumbing process systems require that pipes, tubing, and fittings be attached by threaded fasteners. Screw threads on nuts or on fittings can be damaged in several ways. If the threads cannot be repaired, usually the nut, pipe, or tubing is discarded or has to be spliced. A problem with attempting to repair threads is the inability to maintain the tap or die coaxially aligned with the nut or fitting being repaired. If the repair is performed with the tap or die at an angle, the screw threads will be misaligned and fittings being joined may not function properly. Compression fittings are commonplace. In a compression system, a nut with a hole in the center through which a tube passes is used to connect the tube to a fitting. A ferrule, also with a hole in the center, is placed on the end of the tube and in front of the nut. When the nut is tightened against a fitting to connect the tube to the fitting, the ferrule can be compressed against tube material, thus deforming the tube and helping to create a seal. During the threading process, the threads on the nut or the fitting may be damaged due to an initial misalignment. A problem arises when repairing a captured nut on a tube because the tube renders the nut inaccessible. 
     Accordingly, it would be useful to provide a tap and die device that can repair external and internal screw threads to avoid having to discard or splice materials. It would further be advantageous to provide a tap and die device that can coaxially align a workpiece needing to be repaired with the tap or die. It would further be advantageous to repair a nut while captured on a tube. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     In a first embodiment, a tap device includes an elongated tap including a shaft having external cutting threads on one end and a body having a bore on one end within which the shaft rotates and a socket on the opposite end of the bore, wherein the center of the socket is coaxially aligned with the longitudinal center of axis of the shaft. 
     The tap device of the first embodiment can be provided wherein the socket has a plurality of sides. 
     The tap device of the first embodiment can be provided wherein the shaft is hollow at least at the end having the cutting threads. This hollow or cavity allows the tap to reach the nut when the nut is captured on a tube because the tube and ferrule can fit within the cavity. 
     The tap device of the first embodiment can be provided wherein the shaft is hollow at least at the end having the cutting threads and the hollow end includes a frustoconical bevel. This allows the tap to reach the nut when the nut is captured on a tube because the tube and a ferrule can fit within the hollow cavity. A hollow end of the tap can be shaped to match any type of tube nut and ferrule. 
     The tap device of the first embodiment can be provided wherein the socket includes slots placed on opposite sides and a clip is placed within the slots. 
     The tap device of the first embodiment can be provided wherein the body has an exterior shape with a plurality of planar sides, such as a hexagonal shape. This allows the body to be held with a typical hand tool, such as a wrench, during the repair process. 
     The tap device of the first embodiment can be provided wherein the tap and body are approximately the same length. This provides a compact device and also allows the tap to reach at least to the slots made in the socket while the head still projects outward of the body to allow turning the tap. 
     In a second embodiment, a method for repairing internal threads includes placing a tap within a bore of a body having a socket located opposite from the bore, wherein the socket and bore are coaxially aligned. The method includes placing a nut within the socket and rotating the tap to engage cutting threads on the tap with threads on the nut to repair the threads. 
     The method of the second embodiment may further include securing the nut in the socket to prevent the nut from exiting the socket. 
     The method of the second embodiment may further include engaging tubing passing through the nut within a cavity provided on the end of the tap. 
     In a third embodiment, a die device includes a die including internal cutting threads on one end and a bore on the inside at an opposite end from the cutting threads, wherein the center of the bore is coaxially aligned with a center of a diameter of the cutting threads and a pilot including a shaft that fits within the bore, wherein the longitudinal center of axis of the pilot is coaxially aligned with the center of the diameter of the cutting threads. 
     The die device of the third embodiment can be provided wherein the die includes means for turning the die. 
     The die device of the third embodiment can be provided wherein the pilot includes a boss placed a predetermined distance from one end of the shaft. The boss shape can be made to match any specific fitting such that the boss is placed against the fitting to help with aligning the pilot to the fitting. 
     The die device of the third embodiment can be provided wherein the pilot includes a spindle in front of the boss. The spindle outer diameter can be made to match any specific fitting such that the spindle is placed inside of the fitting to help with aligning the pilot to the fitting. 
     The die device of the third embodiment can be provided wherein the outer diameter of the boss is smaller than a minor diameter of the cutting threads to allow the boss to fit within the die in the area of the cutting threads. 
     The die device of the third embodiment can be provided wherein the pilot includes a frustoconical boss on the shaft wherein, when placed within the die, a base of the frustoconical boss faces in the direction of the bore in the die. 
     The die device of the third embodiment can be provided wherein the axial length of the die is smaller than the length of the pilot. 
     In a fourth embodiment, a method for repairing external threads includes placing a pilot on the inside of a fitting with external threads wherein a portion of the pilot extends outward of the fitting, and the longitudinal center of the pilot is coaxially aligned with a center of a diameter of the external threads of the fitting. The method includes engaging a die with the outward extending portion of the pilot, wherein the longitudinal center of axis of the pilot is coaxially aligned with a center of a bore of the die. In this way, the longitudinal center of axis of the die is coaxially aligned with the center of a diameter of the external threads of the fitting. The method includes turning the die to advance the die on the threads of the fitting to repair the threads. 
     The method of the fourth embodiment may further include placing a boss on the pilot against a corresponding structure on the fitting to facilitate coaxial alignment of the pilot to the fitting. 
     Disclosed herein is a tap and die device having a component that assists with maintaining a workpiece, such as a nut or fitting, coaxially aligned with the tap and die device. In the tap device, the component is a body configured with a socket and bore to hold the workpiece and the tap both coaxially aligned with each other. The tap can be hollow at least at one end to accept a tube and ferrule in the situation when the nut is captured on a tube. In the die device, the component is a pilot that is configured to maintain the die coaxially aligned with the workpiece. The pilot fits within a fitting to maintain the alignment. 
     The tap and die devices can be provided together as a set or a kit. Furthermore, the tap and die devices can be sized to match any standard or nonstandard screw thread size for compression type tube and piping connections. A plurality of different sized tap and die devices can be combined into a kit. 
     The tap and die devices can repair internal and external threads, respectively. The tap and die devices are provided with a component that coaxially aligns the tap and die to the nut or fitting being repaired. The tap and die devices are easily portable, compact tools that can be used in tight places. The tap and die devices are manually operated and do not require the use of pneumatic nor electrically powered tools. Common manual tools can be used to operate the tap and die devices. 
     The tap and die devices can be used to repair pre-existing threads on nuts and other fittings that have been damaged. The tap and die devices can be used on materials used in threaded systems, including metal, iron, steel, copper, brass, plastic, and the like. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a diagrammatical illustration of a tap device in accordance with one embodiment of the invention; 
         FIG. 2  is an exploded view diagrammatical illustration of the tap device of  FIG. 1 ; 
         FIG. 3  is a cross-sectional illustration of a body of a tap device in accordance with one embodiment of the invention; 
         FIG. 4  is a diagrammatical illustration of a body of a tap device in accordance with one embodiment of the invention; 
         FIG. 5  is a diagrammatical cross-sectional illustration of a tap in accordance with one embodiment of the invention; 
         FIG. 6  is a diagrammatical illustration of a die device in accordance with one embodiment of the invention; 
         FIG. 7  is an exploded view diagrammatical illustration of the die device of  FIG. 6 ; and 
         FIG. 8  is a diagrammatical illustration of a die in accordance with one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a tap device  100  is illustrated. The tap device  100  may be used to repair internal screw threads, such as are present in a nut  106 . The nut  106  can be assembled on the tube  108  and captured by a ferrule (not shown). However, the tap device  100  is not limited to using only on captured nuts. The tap device  100  can be used on loose nuts. However, the repair of threads on never used, loose nuts is less common. The tap device  100  includes a tap  102  and a body  104 . The body  104  can be a structure with a hollow interior within which the tap  102  is located. One end of the body  104  is provided with a bore within which one end of the tap  102  rotates. The bore diameter can be closely matched to the diameter of the tap  102  to provide little or no side-to-side movement to maintain coaxial alignment between the tap  102  and the body  104 . The tap  102  includes a shaft. At least the part of the shaft that fits within the bore is cylindrical to allow rotation therein. Because the bore within which the tap  102  fits is only slightly larger than the diameter of the cylindrical portion of the tap  102 , the tap  102  has insignificant lateral movement. On the end of the body  104  opposite to the bore is a socket  134 . Both the bore and socket have the same center of axis and are coaxially aligned with one another. The socket  134  and the bore are rigidly connected to each other. In one embodiment, the body  104  can be a unitary piece of material and the bore and socket are formed from the single piece of material. In other embodiments, the bore and socket can be separate but connected rigidly to one another such that the center axis of the bore and the center axis of the socket are coaxially aligned. 
     In one embodiment, the socket  134  can be hexagonal on the inside and outside. However, while a hexagonal socket is illustrated, it can be appreciated that the socket can be any size or shape and possess any number of sides. The socket  134  may be provided in the shape or size to match any standard nut size and shape as well as any custom or irregular shape. Furthermore, the socket may include curved shapes or a combination of curved and straight sides to match irregular, custom, or specialized nuts. The outside of the socket  134  may be shaped as a hexagon or otherwise to provide a way of holding the body  104  while repairing the threads. The body  104  may be held with a wrench, vise or other tool. 
     The body  104  has a centerline defined as a line passing longitudinally through the center of the body  104  as well as through the bore and socket. The tap  102  includes a centerline passing longitudinally through the center of the tap  102 . The purpose of the bore is to keep the centerline of the tap  102  aligned as closely as possible to the centerline of the body  104 . As a consequence, the centerline of the tap  102  is also coaxially aligned and passes through the centerline of the socket  134 . The purpose for this will become apparent as further described below. 
     One application of the tap device  100  illustrated in  FIG. 1  is for repairing threads that have been damaged or are otherwise in need of repair. The nut  106  includes internal or female threads, while a fitting may include external or male threads. The threads of the nut  106  are defined by a diameter and are centered with respect to the center bore of the nut  106 . In one particular embodiment, the tap device  100  may be used to repair threads on a nut  106  as part of a tubing section  108 . For example, nut  106  and tubing  108  can comprise parts of a compression fitting system, wherein the nut  106  is captured on tubing  108  by a ferrule (not shown). As is well known, compression fittings work by compressing a frustoconically shaped ferrule (not shown) on the tubing  108  against a fitting having a similar frustoconical shape on the inside of the fitting. Once the ferrule is placed on the frustoconically shaped fitting, the nut  106  is threaded onto the fitting (not shown) and tightened. The nut  106  can not be removed after tightening to a sealing condition because the ferrule is tightly pressed to the tubing  108  and usually deforms the tubing. 
     As discussed above, the socket  134  of the body  104  is configured to accept any standard or irregular nut, such as nut  106 . The tolerances between the interior socket dimensions and the exterior nut dimensions are preferably kept as small as possible so that when placed in the socket  134 , the nut  106  center is coaxially aligned as closely as possible with the center of the socket  134 , which has the consequence that the nut  106  is also coaxially aligned with the tap  102  in the body  104 . The body  104  maintains the tap  102  coaxially aligned on the center of the nut  106  to produce accurate, straight threads during repairs. 
     The socket  134  may have a first and second slot  110  and  112  on opposite sides of the socket  134 . In use, the nut  106 , with or without the tubing  108 , may be placed inside the body  104  until the nut  106  extends deeper than the slots  110  and  112 . At that point, a clip  114  may be inserted in slots  110  and  112  to retain the nut  106  from being pushed out of the socket  134 . The tap  102  includes means to rotate the tap  102 . Once the nut  106  is inside the socket  134 , the tap  102  may be turned and advanced in the body  104  by using a rod  116  acting as a lever, or the tap  102  can be fitted with a hexagonal head  118  that may be turned with a standard wrench. The body  104  may be held with a wrench, vise, or other tool. 
     Referring to  FIG. 2 , the tap device  100  comprising the tap  102  and body  104  is illustrated. As can be seen clearly in  FIG. 2 , the body  104  has a cylindrical bore  120  for the bore  120 . The bore  120  diameter is slightly larger than a diameter of the tap  102  to allow rotation therein with minimal lateral play. The centerline of the tap  102  is coaxially aligned with the centerline of the body  104  and, as a consequence, with the centerline of the socket  134 . The tap  102  includes external cutting threads  122  on one end thereof. Cutting threads  122  may be of any design known in the art. For example, cutting threads  122  may be of a common type and include any number of flutes. As is well known, cutting threads  122  can be defined by a major, minor, and pitch diameter, and any numbers of flutes and lead angle. In one embodiment, the outside of the body  104  may have a hexagonal shape, providing six sides along the length of the body. However, the body  104  can be other shapes. For example, the outside of the body  104  may be cylindrical. However, the interior of the body  104  may have a hexagon shape (or any other shape) for the socket  134  and a cylindrical shape for the bore  120 . In one embodiment, elongated openings  124  as seen in  FIGS. 3 and 4  may be provided on the body  104  on one or two sides thereof. However, the openings  124  are optional. The openings  124  may be provided on opposite sides of the body  104  to allow viewing the process of chasing the threads. A hexagonally shaped body  104  provides the ability to hold the body  104  with a standard wrench, vise, or other tool at both ends of the body  104 . However, the body  104  can have other shapes to assist with holding the body  104  when repairing threads. 
     Referring to  FIG. 5 , a cross-sectional view of the tap  102  is shown. In one embodiment, the tap  102  is hollow at the end containing the cutting threads  122 , thereby forming a cavity  126  at the end. The cavity  126  may have a shape and diameter to match a shape and diameter of any standard (or nonstandard) tubing size to allow the front end of the tubing to fit within the cavity  126 . Since the nut is also centered on the tubing, the tubing may further provide additional support to maintain the nut coaxially aligned with the tap  102  as the tap  102  is advanced on the nut. The forward end of the cavity  126  includes a beveled or frustoconical shape  128 , wherein the base of the frustoconical shape  128  is the forwardmost part. The frustoconical shape  128  can correspond to the shape of a ferrule, such as, for example, the ferrules that are used in well known compression fittings. Providing the cavity  126  and the frustoconical shape  128  at the end of the tap  102  allows the tap  102  to advance without hindrance to the bottom of the nut  106  when the nut  106  being repaired is connected to tubing. It should be appreciated that the shape of the cavity can be made to match any fitting, compression or otherwise. The frustoconical shape mentioned is to illustrate one embodiment of the tap  102 . 
     The tap device  100  can be provided wherein the tap  102  and body  104  are approximately the same length. This provides a compact device and also allows the tap  102  to reach at least to the slots  110  and  112  made in the socket  134 , while the head  118  still projects outward of the body  104  to allow turning. 
     On the end opposite to the cutting threads  122 , the tap  102  includes a head  118 . The head  118  projects outside of the body  104 , as seen in  FIG. 1 , even when the tap  102  is advanced to the bottom of the socket  134 . The head  118  may be shaped as a hexagon to allow the use of standard wrenches to rotate the tap  102 . Alternatively, or additionally, the head  118  may also include a hole  132  to allow a rod  116  to be used as a lever to turn the tap  102 . The tap  102  is manually driven by hand and does not require the use of powered tools. 
     Referring now to  FIG. 6 , a die device is illustrated for repairing external or male threads. The die device includes a die  200  and a pilot  202 . 
     As shown in  FIG. 7 , the majority of the length of the pilot  202  can be cylindrical in shape. The pilot  202  includes a boss  204  that is rigidly affixed to a position along the length of the pilot  202 . The boss  204  may be shaped to correspond to standard or irregular tubing and/or piping components. For example, the boss  204  can have a frustoconical shape similar to the ferrules used in compression fittings. In the illustrated embodiment, the frustoconical shaped boss  204  has a base that faces the die  200 . In compression fittings, such as the one illustrated in  FIG. 7 , the end of fitting  208  is provided with a bore having a beveled edge  210  that is frustoconical in shape. The fitting  208  has external threads that can be repaired using the disclosed die device. The threads on the fitting  208  are defined by a diameter and are centered with respect to a bore within the fitting  208 . The bore can terminate at the beveled frustoconical edge  210 . The pilot  202  may include a spindle  212  in front of the boss  204 . The spindle  212  may be sized to fit within the bore in fitting  208 , and the boss  204  is sized to fit against the beveled edge  210  of the fitting  208 . The outer dimension of the spindle  212  is matched closely to the inner diameter of the fitting  208 . When the spindle  212  is inserted in the fitting  208  and the boss  204  is placed against the beveled edge  210 , this will provide for coaxially aligning the center of the fitting  208  threads to the longitudinal centerline of the pilot  202 . Fitting  208  may include components such as valves, for example. 
     The die  200  fits over the pilot  202  as seen in  FIG. 6 . The die  200  includes interior cutting threads  222  and an interior bore that is closely dimensioned to a diameter of the pilot  202 . The purpose of the bore is to allow the centerline of the die  200  to remain coaxially aligned to the centerline of the pilot  202  with high precision as the die advances forward. Consequently, because the centerline of the pilot  202  is aligned with the centerline of the fitting  208 , the centerline of the die  200  will also be aligned with the centerline of the fitting  208 . Thus, the die  200  becomes coaxially aligned with the fitting  208  threads. Furthermore, as the die  200  is turned and advances, the pilot  202  assists in maintaining the die  200  straight to avoid cutting threads at an angle. The interior cutting threads  222  can be of a conventional or well-known design to repair exterior threads. The fitting  208  can be held with a standard wrench, in a vise, or is otherwise rigidly held during the repair of the fitting. 
     At the end opposite to the spindle  212 , the pilot  202  is provided with a head  216 . Optionally, the head  216  may be a hexagon shape and/or the head  216  may include a hole therein. 
     Referring to  FIG. 8 , an illustration of the die  200  is shown. The die  200  is a hollow structure that may be formed from a single piece of material. The end  212  includes cutting threads  222  on the interior. As is well known, cutting threads  222  can be defined by a major, minor, and pitch diameter, and any number of flutes and lead angle. The end  214  includes a bore  210  on the interior and the exterior can be provided with means used to apply torque to turn the die  200 . The center of the bore  210  is coaxially aligned with the center of the pitch diameter that defines the cutting threads  222 . The die  200  fits over the pilot  202  such that the pilot  202  fits within the bore  210 . The die  200  can advance on the pilot  202  up to the point when the base of boss  204  contacts the bore  210 . A lip cap be formed where the diameter of the bore  210  expands to the diameter of the cutting threads  222 . The diameter of the boss  204  is smaller than the diameter of the minor diameter of the cutting threads  222  to allow the boss  204  to fit within the area of the cutting threads  222 . Furthermore, the length of the area of the cutting threads  222  is long enough so that the die will advance far enough to repair the length of the threads needing repair. 
     In one embodiment, the end  214  used to turn the die  200  may have a hexagon shape that fits standard wrench sizes. However, the end  214  can also be square or a polygon with any number of sides. The die  200  can be turned with a standard wrench, for example, by hand without powered tools. When turning the die  200 , the fitting  208  can be held with a wrench, vise, or otherwise held rigidly. 
     While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.