Patent Publication Number: US-6904660-B2

Title: Compression sleeve puller with double thread engagement and method of manufacture

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
   Division of application Ser. No. 10/119,365 filed Apr. 9, 2002 now U.S Pat. No. 6,637,089. Incorporated herein by reference is the entire text of said application. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to pullers, in particular to compression sleeve pullers having a duality of screw thread engagement and includes method of manufacture. 
   2. Description of Prior Art 
   A pipe which contains pressurized fluid may be connected to a valve which is used to dispense the pressurized fluid in a controlled manner. An example is household plumbing lines bringing water into the premises. The individual branches of the plumbing system are routed inside the walls of the house and terminate inside a room such as a bathroom or kitchen. The plumbing lines protrude through the wall far enough to attach a water valve. A common method of attaching and sealing a water valve to a plumbing line is to employ the use of a compression fitting consisting of a compression nut, a compression sleeve and the valve. To install the valve, (1) the compression nut is placed on the pipe; (2) the closely fitting compression sleeve is slipped onto the pipe; and (3) the valve is pushed on and engaged with the compression nut. The nut is then tightened onto the valve to compress the compression sleeve onto the pipe. The compression sleeve creates both a mechanical grip for the valve and a pressure seal for the fluid. Other methods of attaching the valve include: (a) threading the valve into a threaded pipe fitting and sealing the point of attachment with pipe sealant; or (b) soldering the valve to the pipe. When a valve wears out or fails, it must be removed and replaced. This invention applies only to the removal of valves which are attached using the compression sleeve method of attaching and sealing. 
   When replacing a valve or other device attached to a pressurized pipe by means of a compression sleeve fitting, it is important to remove the old compression sleeve and replace it with a new compression sleeve to ensure proper sealing. Generally, plumbing pipe comprises thin wall copper tubing. This tubing is easily damaged when old compression sleeves are reused because the old sleeve generally must be over-tightened to obtain a seal. 
   The removal of the old compression sleeve requires specially designed tooling to pull the old sleeve off the copper pipe without damage to the pipe. If the pipe is dented, scratched or deformed, it is generally impossible to reseal with a compression sleeve. This results in the need to replace the damaged pipe or otherwise causes extra work and expense. 
   Compression nuts used for this application come in two standard thread designs: coarse thread and fine thread. Although both thread designs possess the same inner diameter, two puller tools are required to couple with the differing thread designs. In lieu of two tools, the prior art discloses a single tool which incorporates a removable adapter to change from the coarse thread to the fine thread or vice versa. This type of puller is shown in U.S. Pat. No. 5,519,929 issued to Bleckman. Bleckman discloses a removable threaded adapter which threads to the end of the body of the tool to provide coupling to the alternate thread design. For example, if the tool is manufactured with the fine thread design at the coupling end, then the adapter is manufactured with a fine inner thread, a stepped down inner portion to match the inner diameter of the tool body, a hexagonal or knurled outer diameter for aid in threading it to the tool body, and a coarse outer thread to mate with the compression nut to be removed. This adapter represents 50% of the utility of the tool and approximately 30% of the total cost of the tool. 
   The required adapter is easily lost or misplaced. Moreover, the adapter is difficult to find in a plumber&#39;s toolbox because of its diminutive size. Also, the use of the adapter increases the length of the tool thereby decreasing its usefulness. Bleckman points out that the longer the tool, the more difficult it is to use in the normal plumbing environment of tight quarters and adjacent obstacles such as pipes, sinks and walls. The disadvantages of the additional removable adapter are significant enough to make the tool as a whole less desirable to both the professional plumber and the handyman. 
   The Bleckman design also discloses an unnecessarily complex and costly bearing device/alignment plug consisting of a larger diameter cylindrical bearing device stepped down to a smaller diameter, tapered, alignment plug used to center the bearing device to the edge of the pipe. Alignment is necessary to prevent the larger diameter bearing device from catching on the compression sleeve as it passes through. The complexity of the bearing device/alignment plug adds unnecessary cost and size to the tool. It has been discovered that if the tapered alignment plug is eliminated and the cylindrical bearing device is replaced by a relatively thin, loose fitting, rotatable disk, the tool operates perfectly well without the additional alignment plug. It was found that the when the disk encounters the compression ring, it self-centers and passes through with no difficulty. The simple disk comprises only about 2% of the cost of the tool whereas the complex bearing device/alignment plug disclosed by Bleckman comprises about 15% of the cost of that tool. Therefore, by eliminating the adapter and replacing the bearing device/alignment plug with a simple disk, the cost of the tool is reduced by about 43%. 
   The Bleckman design suffers from the following disadvantages:
         (a) the separate adapter which is necessary for the tool to be used for both fine and course compression nuts is expensive;   (b) the separate adapter adds undesirable length to the tool;   (c) the separate adapter is easily lost or misplaced;   (d) the bearing device/centering plug is overly complex and expensive.       

   Therefore, there is a need for a less complex and costly tool which couples to both fine and coarse threaded compression nuts without the use of an undesirable adapter and operates smoothly without the need for a complicated bearing device/centering plug. 
   3. Summary of the Invention 
   The present invention is a dual thread design compression sleeve puller which fits both coarse and fine threads without the use of an additional adapter. The two threads, coarse and fine, are both cut in the threaded end of the tool so that the tool automatically fits either thread on the compression nut. This overcomes the disadvantages of the thread adapter necessary for prior art and makes the tool more productive and less expensive. It also eliminates the possibility of loss of the adapter. The present invention also elimates the bearing device/centering plug and replaces it with a simple disk which functions for both purposes. 
   4. Objects and Advantages 
   It is therefore an object of the present invention to provide a new and useful compression sleeve puller with a double thread engagement. Further objects and advantages of the present invention are as follows:
         (a) to provide a puller which threadably couples to compression nuts of either fine or coarse thread design without the use of an adapter;   (b) to provide a tool which does not require the use of an alignment plug for centering on the pipe;   (c) to provide a puller of simple design which is easy to use in tight quarters;   (d) to provide a puller which is durable enough for the professional and inexpensive enough for the handyman or homeowner;   (e) to provide a puller which is easy to attach to the compression nut without the use of tools and supports itself when so attached;   (f) to provide a puller which can be operated simply, quickly and in most cases with one hand;   (g) to provide a puller which can be attached and operated by a person with average skill and strength,   (h) to provide a puller which reduces the time and effort for the removal of compression sleeves and increases productivity; and   (i) to provide a method of manufacture which will overcome the limitations and disadvantages of threaded pullers heretofore provided.       

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  depicts the preferred embodiment of the puller. 
       FIG. 2  shows the puller in partial section as typically used engaged with a compression nut, compression sleeve and pipe. 
   

   REFERENCE NUMBERS IN DRAWINGS 
   
       
         10  compression sleeve puller 
         12  torque handle 
         14  screw 
         16  shaft 
         18  groove 
         20  retaining clip 
         22  disk 
         24  body 
         26  internal thread 
         28  internal cavity 
         30  external double thread 
         32  chamfer 
         34  compression nut 
         36  compression sleeve 
         38  pipe 
     
  
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The preferred embodiment of the compression sleeve puller is illustrated in  FIGS. 1 and 2 .  FIG. 1  shows puller  10  composed of a generally cylindrical body  24  with internal thread  26  at one end for threaded engagement with screw  14  and external thread  30  at the opposite end for threaded engagement with compression nut  34  (FIG.  2 ). Body  24  may be hexagonal or knurled for a better grip. Body  24  has an internal cavity  28  to receive circular disk  22  and an inner chamfer  32  on the open end of cavity  28  to provide a close fit with compression sleeve  36  (FIG.  2 ). Screw  14  has a torque handle  12  fitted on one end and a smaller diameter shaft  16  on the opposite end onto which disk  22  is retained by retaining clip  20  in groove  18 . Disk  22  contains a center hole to rotatably mount onto said shaft  16  and has an outside diameter to closely fit into cavity  28  and yet slide easily therein. 
     FIG. 2  shows puller  10  in partial sectional view attached to pipe  38  by nut  34  which contains a sleeve  36  compressed onto pipe  38  and is to be removed therefrom. Nut  34  is threaded on to thread  30  thereby holding pipe  38  tightly against disk  22 . The rotatable mounting of disk  22  allows for reduced effort when handle  12  is turned forcing disk  22  against the end of pipe  38 . Disk  22  does not rotate against the end of pipe  38  where the contact diameter is relatively large but instead rotates against screw  14  where the contact diameter is small thus reducing the effort needed to turn handle  12 . Cavity  28  is slightly more than ⅝ inch deep which is enough to contain the thickness of disk  22  and to receive pipe  38  engaged fully up to the position of sleeve  36 . The inner diameter of cavity  28  is just over ⅝ inch and is closely dimensioned to the outside diameter of pipe  38  for a slidable fit. Screw  14  is approximately two inches in length and is long enough to contain handle  12  and shaft  16  and capable of advancing far enough to push disk  22  at least ⅜ inch beyond the end of cavity  28  so that it passes completely through sleeve  36 . As screw  14  is turned using handle  12 , disk  22  advances against the end of pipe  38  and urges it out of cavity  28 . Screw  14  is further turned urging pipe  38  through sleeve  36  freeing sleeve  36  from pipe  38 . The various components of puller  10  are made of stainless steel to resist corrosion and for easy cleaning and long life. 
   To illustrate one important aspect of this invention, attention is given to the particular case of copper plumbing commonly used for distributing and dispensing water throughout a standard residence or business. Copper plumbing is comprised of copper tubing with an inner diameter of ½ inch and an outer diameter of ⅝ inch. Water control valves and compression nuts used with compression fittings on this size pipe come in two thread designs: fine pitch and coarse pitch. The fine pitch thread is a {fraction (13/16)}-18 NF thread hereinafter referred to as fine thread, and the coarse pitch thread is a straight pipe thread, ½-14 NPS hereinafter referred to as coarse thread. These two threads are of substantially identical diameters. A threadably engaging puller may be manufactured with either a coarse thread or a fine thread in which case two tools, or at least a tool with a relatively expensive adapter, are required to fit all possible jobs of this pipe size. It is an object of the invention to have a single tool which fits both thread designs and is simple and inexpensive. In an effort to do this, two discoveries were made. First, it was discovered that a fine thread may be cut over a coarse thread (or alternatively a coarse thread over a fine thread) resulting in a “single entry, double pitch thread” which will fit both fine thread and coarse thread compression nuts. The discovery of the double thread enhances the utility of puller  10  and eliminates the need for a separate adapter. It was also found that a simple disk  22  may be used in place of the more complicated and costly bearing device/alignment plug used in the prior art. 
   In the preferred embodiment, thread  30  is a single entry, double pitch thread which engages with compression nut  34  whether it has a coarse thread or a fine thread. This double thread  30  may be manufactured by first cutting a fine thread ({fraction (13/16)}-18NF) on body  24  and carefully noting the entry point of the thread. Then, using the same entry point, a coarse thread (½-14NPS) is cut on body  24  directly over said fine thread resulting in double thread  30 . The second thread will clear a path for itself through the pattern of the first cut thread. Since both threads start at the same entry point, a fine thread compression nut or alternatively a coarse thread compression nut each start threading on at the same entry point and automatically find their own path on double thread  30 . Since the fine and coarse threads have different pitches, they will intersect every few turns and result in areas where the major diameter of one thread is cut away to provide for the minor diameter of the other. The appearance of the resulting double thread is a bifurcated look but operates perfectly well for both compression nuts, fine or coarse. Some material is removed from the thread in the process of double threading so the ultimate strength of each of the two threads is reduced. However, each thread is of sufficient strength for removing even the tightest compression sleeves. In addition, the first two or three turns of said double thread are substantially whole, so its strength for use on this tool is more than adequate. Because of the geometry of nut  34  and sleeve  36 , puller  10  will engage nut  34  by fewer than three turns before bottoming out against sleeve  36 . The strength of the engaged threads is only slightly reduced from that of a standard coarse thread or fine thread. In the preferred embodiment, the thread  30  of puller  10  is steel while the thread of nut  34  is generally brass so that even the reduced strength of thread  30  is substantially greater than the strength of the thread of nut  34 . Testing shows that even corroded and overly compressed sleeves  36  are easily removed with puller  10 . 
   Although an illustration herein cites the use and design of puller  10  specifically for ½ inch copper pipe, it is in no way intended to limit the use of said puller to that particular use. It is to be noted here that puller  10  may be scaled to larger or smaller pipe applications without changing the spirit or intent of the invention. 
   OPERATION 
   Puller  10  is used after a water valve is removed from pipe  38  and the compression nut  34  remaining on the pipe is retained by a compression sleeve  36 . Puller  10  is operated as follows: (a) prepare puller  10  by turning handle  12  counter clockwise until disk  22  is drawn as deeply as possible into cavity  28  (b) hand tighten external double thread  30  to nut  34  on pipe  38  (c) turn handle  12  clockwise until disk  22  pushes pipe  38  completely through sleeve  36  freeing nut  34  and sleeve  36  from pipe  38  (d) discard compression nut  34  and compression sleeve  36 . 
   CONCLUSIONS, RAMIFICATIONS AND SCOPE 
   From the foregoing description it is seen that the invention provides an extremely simple, efficient, low cost and reliable manner for removing compression sleeves from pipes. 
   While in the foregoing there have been set forth the preferred embodiment of the invention, it will be appreciated that the details herein given may be varied by those skilled in the art without departing from the true spirit and scope of the appended claims. 
   Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.