Abstract:
Apparatus is provided for removing a crimped ring from plastic tubing installed over the nipple of a fitting. A supporting jaw radially supports the crimped ring while a chisel cuts the ring on a tangential path. One embodiment uses pair of levers joined and pivoted intermediate their ends. One lever forms the supporting jaw while the other forms the chisel. When actuated, the cutting jaw cuts the ring on a path tangent to the inside circumference of the ring, thereby avoiding injury to the fitting, the fitting therefore being reusable.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to a tool used to remove compressed rings from tubing joints. More specifically, this tool relates to the removal of crimped rings used to secure plastic plumbing pipe or tubing over a fitting. 
     BACKGROUND OF THE INVENTION 
     The introduction of plastic plumbing to the construction industry has resulted in a significant saving of time. The conduit used in plastic plumbing is referred by a variety of terms such as hose, piping or tubing. Steel piping requires a labor and time intensive fitting and threading process. Rigid copper piping avoids the threading process but replaces it with the need for soldering. Plastic tubing requires less fitting and the resulting joints are easy to complete. Tubing used for household plumbing is placed over a fitting&#39;s barbed or ribbed nipple and secured with a clamp of some sort. 
     It is known to crimp rings, such as annealed copper rings, over plastic plumbing tubing attached to the fitting&#39;s nipples, in order to provide a more secure joint. The tubing is resilient and is caused to deform over the ribs of the rigid nipple, preventing the tubing&#39;s removal therefrom. A number of tools have been developed to crimp the ring over the tubing and the nipple. One such tool is described in U.S. Pat. No. 5,289,712 to Haughian, wherein a lever type tool is used to apply pressure and reduce the diameter of the ring over the tubing, once positioned over a ribbed nipple. The tubing under the ring is permanently deformed. 
     Sometimes it is necessary to change the connection at the joint, to correct an error, alter the configuration, or merely to remove the fitting. Preferably the fitting is salvaged for reuse, due in part to economics but also to avoid the need to change all other joints on the affected fitting. Due to the deformation of the tubing at the old joint, the deformed part is usually cut off. 
     To change the joint, the crimped ring is removed before the tubing can be removed from the ribbed nipple. Currently, removal of these crimped rings presents a challenge, as most plumbers are forced to use a hacksaw to angle cut the ring from the tubing and the nipple. This may result in damage to the nipple as it is difficult to visualize the point at which the ring has been cut and the underlying nipple has not. The tubing offers little resistance to the hacksaw and one can cut through the tubing and into the nipple with little warning. Further, joints of this type are often too closely spaced or are located in areas with little space to maneuver a saw. 
     There are a number of tools used to hold and cut pipe or tubing, such as described in U.S. Pat. No. 287,378 to Herbert and U.S. Pat. No. 198,709 to Thornton. Generally, these pipe-cutting devices cut the pipe circumferentially. U.S. Pat. No. 45,496 describes a device which has a nearly tangential pipe thread cutting tooth. None of these tools could be used to remove a crimp ring from tubing. Further, tools which would apply a force perpendicular to the surface of the ring could result in deformation or damage to the fitting. 
     There is clearly a demonstrated need for a tool that can remove a crimped ring without damaging the underlying nipple and which is simple and easy to operate under a variety of conditions. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment, a device is provided for removing an annular ring from plastic tubing overlying a plumbing fitting. The device has the advantages of simplicity, ease of operation and does not risk injury to the fitting. In an embodiment implementing pivoting jaws and handles, the jaws are placed over the crimped ring and actuation of the handles allows one jaw to support the ring while the other cuts the ring on a path tangent to the inside circumference of the ring which thereby avoids injuring the fitting. 
     In a broad aspect then, apparatus is provided for cutting a crimped ring from an underlying cylindrical object, such as plastic tubing overlying a nipple, the apparatus comprising an annular recess for radially supporting at least a portion of the ring along its circumference and a ring-cutting chisel. Means are provided for actuating the chisel between resting and ring-cutting positions, preferably being a pair of pivoting levers, which form the recess and chisel portions. The chisel, when actuated from a resting position to a cutting position, engages and cuts through the ring across its width and along a path substantially tangent to the ring&#39;s inner circumference so as to leave the underlying circular object intact, the ring being supported by the annular recess. 
     Preferably, the actuating means are a pair of levers or a screw actuated chisel integrated into a unitary body. More preferably, serrations can be provided in the annular recess to prevent rotation of the ring while cutting. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is a partial side, cross-sectional view of a conventional plumbing fitting, plastic tubing and crimped ring; 
     FIG. 1 b  is a cross-sectional view of the fitting, tubing and ring along line I—I of FIG. 1 a;    
     FIG. 2 is a perspective view of a hacksaw example for removal of a crimped ring, according to the prior art; 
     FIG. 3 a  is a side view of one embodiment of the invention illustrating the resting position prior to cutting of the ring; 
     FIG. 3 b  is a side view according to FIG. 3 a , illustrating cutting position wherein the ring is severed; 
     FIG. 4 a  is a partial perspective view of the embodiment according to FIG. 3 a  illustrating a partial fitting, tubing and crimped ring prior to cutting; 
     FIG. 4 b  is a perspective view of a crimped ring after it has been cut using an embodiment of the invention; and 
     FIG. 5 is a side cross-sectional view of a screw-type embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Having reference to FIGS. 1 a  and  1   b , in conventional plumbing, fittings  1  are used at joints in resilient, tubular plastic tubing  2 . A contemporary example of such tubing is cross-linked polyethylene, most commonly used in configurations having ½″ and ¾″ inside diameters. The inside diameter or bore of the tubing  2  is placed over a cylindrical member  3 . The member  3  could be a rigid cylindrical plug or a nipple  3  extending from the fitting  1 . The member  3  has several barbs, serrations or circumferential ribs  4  spaced axially therealong. Hereinafter, the cylindrical member referred to herein is implemented as a nipple  3  having a bore for passing fluids coextensive with the tubing  2 . Together, the nipple  3  and overlying tubing  2  form a cylindrical object  5 . 
     The tubing  2  is secured to the nipple  3  with an annular ring  6 . The ring  6  is placed concentrically over the cylindrical object  5  and compressed or crimped with a conventional crimping tool (not shown). The crimped ring  6  radially compresses the tubing  2  onto the nipple  3  and deforms it over the nipple&#39;s ribs  4 . The crimped ring  6  is used only once and must be removed if the tubing  2  is to be separated from the nipple  3 . 
     As stated above, a known prior art means of ring removal, as seen in FIG. 2, is to use a hacksaw  7  to cut across the width w of the crimped ring  6  at an angle. There is a risk that in attempting to cut the ring  6 , both the tubing  2  and the nipple  3  may be cut requiring replacement of the fitting  1  and all three joints shown. 
     Having reference to FIGS. 3 a - 5 , the present invention provides a device  11 , which incorporates radial support means  8  for the ring  6  and a ring-cutting means  10 . A portion of the outer circumference of the ring  6  rests against the support means  8  for radially supporting the ring  6 . Actuating means  9  operate cutting means  10  between a resting position (FIG. 3 a ) and a ring-cutting position (FIG. 3 b ). 
     As shown in FIGS. 4 a  and  5 , when actuated, the cutting means  10  are driven into the ring  6 , across its width w, and along a path P substantially tangent to the inside circumference of the annular ring  6 . Cutting reaction forces (including torque), imposed upon the ring  6 , tubing  2  and fitting  1 , are radially resisted by the support means  8 . 
     The arrangement of the support and cutting means  8 , 10  are described in detail as follows. 
     In one embodiment of the invention, shown in FIGS. 3 a  through  4   a , a crimped-ring removal device  11  is shown. Support means  8  are shown to comprise a first lever  12 , on one end of which a ring support in the form of a supporting jaw  13  having a ring supporting surface  13   a  thereon is formed, and on the other end a handle  14  is disclosed. A second lever  15  has a blade or chisel  16  formed on a chisel support  15   a  at one end as the cutting means  10 , and on the other end is formed a handle  17 . 
     The two levers  12 , 15  are joined with a pivot  18  intermediate along their length which allows the device  11  to be actuated to drive the chisel  16  into the ring  6 . Slot  19  aids in placing the jaws over the ring  6 . The slot is inoperative during cutting. The ring  6 , the underlying tubing  2 , and the nipple  3  rest in an annular recess  20  in the supporting jaw  13  which acts as the support means  8 . The annular recess  20  and supporting jaw  13  provide support against the radial force resulting when the chisel  16  bears down on the ring  6  in the cutting position (FIG. 3 b ). 
     While the resulting frictional forces are significant and usually sufficient to prevent rotation of the ring  6 , the supporting jaw  13  optionally includes serrated teeth  21  to further prevent reactive rotation of the ring  6  during cutting (see FIGS. 4 a  and  5 ). 
     Best shown in FIGS. 4 a  and  4   b , the chisel  16  has a linear cutting edge  22  for making a single cut  23  through the annulus of and across the width w of the ring  6 . The resulting cut is substantially parallel to the axis of the ring  6 . Adding angle to the edge may assist in the cutting, but a greater stroke would be required between resting and cutting positions. 
     In operation, FIG. 3 a  shows the device  11  in a non-actuated, or resting position. When the handles  14 , 17  of levers  12 , 15  are actuated by squeezing them together, the device is actuated to the cutting position. 
     Then, as shown in FIGS. 4 a  and  3   b , the chisel  16  and pivot  18  are arranged so that when operated between the resting and cutting positions, the chisel  16  is pivoted to strike the ring  6  and proceed therethrough on a path P substantially tangent to the ring&#39;s inner diameter or circumference  23 . The cutting path P enables cutting of the ring  6  without cutting the underlying nipple  3 . The chisel  16  could encroach on the already deformed resilient tubing  2 . 
     In another embodiment of the invention, best seen in FIG. 5, the support means  8 , a supporting jaw  13 , and the chisel  16  are provided in a unitary C-shaped body  25 . Note that the same reference numerals are used when the elements have the same function as in the earlier embodiment. 
     The supporting jaw  13  is formed in the body&#39;s lower end  26  of the body  25  and the actuating means  9  is formed at the body&#39;s upper end  27 . The actuating means  9  comprises a linear screw actuator  28 , housed in a threaded bore  29  in the body&#39;s upper end  27 . As in the first embodiment, the cutting means  10  is a chisel  16  formed on a bit  30 . The bit  30  moves axially, but does not rotate, within bore  29  so as to ensure the chisel&#39;s cutting edge  22  cuts across the ring&#39;s width w. The bit  30  is prevented from rotating by guide means  31  formed in the body&#39;s upper end  27 , aligning the chisel&#39;s edge  22  substantially parallel to the ring&#39;s axis. 
     Means  34  connect the linear screw actuator  28  and the bit  30  so that the bit  30  both advances and retracts with the actuator. Connecting means  34  permits relative rotation of the rotating screw actuator and non-rotating bit. 
     One form of connection means  34  is shown as an annular groove  32  at the end of the bit  30  opposite the chisel  16  and having a transverse locking pin  33  installed through the screw actuator  28  to engage the annular groove  32  in the bit  30 . 
     Although several preferred embodiments of the present invention have been disclosed above, it is clear to those of ordinary skill in the art that other embodiments are possible which do not vary from the spirit and scope of the present invention. For example, other forms of actuating means are possible which support a ring and actuate the chisel along the described path; the chisel can be skewed slightly to increase the point load, yet still cut across the ring&#39;s width; or a spring return can be added to the chisel of the embodiment depicted in FIG. 5 rather than the connection means  34 .