Patent Publication Number: US-10760354-B2

Title: Collar with stepped retaining ring groove

Description:
SUMMARY 
     An assembly is formed from a tubular collar, a pipe member, and a retaining ring. The tubular collar has opposed first and second ends and an endless internal groove positioned adjacent the first end. Formed in the groove is a step-like base that defines adjacent shallow and deep sections. The pipe member has an end positioned within the collar and an endless external groove positioned adjacent the end. The external groove of the pipe member is situated in concentric relationship with the internal groove of the collar. Situated within both grooves is the retaining ring. 
     A kit includes a tubular collar, a pipe member, and a retaining ring. The tubular collar has an endless internal groove. Formed in the groove is a step-like base defining adjacent shallow and deep sections. The pipe member has an end and an endless external groove positioned adjacent the end. The external groove is configured to be concentric with the internal groove when the end of the pipe member is received within the collar. Sized to be retained within the internal groove, the retaining ring has a maximum cross-sectional dimension that exceeds the depth of the shallow section. 
     A tubular collar having opposed first and second ends is formed from an outer surface, an inner surface, and an endless groove formed in the inner surface. The outer surface is symmetric about a collar axis and has a circular cross-sectional profile. The inner surface has the cross-sectional profile of a polygon that has a centroid situated on the collar axis. Concentric with the collar axis and positioned adjacent the collar&#39;s first end, the groove has axially offset shallow and deep sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a collar having an internal groove in which a retaining ring is positioned. 
         FIG. 2  is a cross-sectional view of the collar of  FIG. 1 , taken along a plane that contains its longitudinal axis. 
         FIG. 3  is an enlarged view of an end of the collar of  FIG. 2 . 
         FIG. 4  is a perspective view of the retaining ring of  FIG. 1 . 
         FIG. 5  is a perspective view of a first end of an inner pipe member. 
         FIG. 6  is a cross-sectional view of a partial dual-member drill string showing the collar and the retaining ring of  FIG. 1  being slid onto the first end of the inner pipe member of  FIG. 5 . 
         FIG. 7  is a cross-sectional view of the partial dual-member drill string of  FIG. 6  showing a later stage of sliding the collar and retaining ring onto the first end of the inner pipe member. 
         FIG. 8  is an enlarged view of a portion of the partial dual-member drill string of  FIG. 7 . 
         FIG. 9  is a cross-sectional view of the partial dual-member drill string of  FIG. 6  showing the collar and retaining ring fully installed on the first end of the inner pipe member. 
         FIG. 10  is a cross-sectional view of the partial dual-member drill string of 
         FIG. 6  showing the retaining ring wedged between the collar and the inner pipe member such that axial movement of the collar relative to the inner pipe member is restricted. 
         FIG. 11  is a cross-sectional view of the dual-member drill string of  FIG. 10  taken along line  11 - 11 . 
         FIG. 12  is a side elevation view of a horizontal directional drilling operation in which a dual-member drill string is used to drill a borehole. 
         FIG. 13  is a cross-sectional view of a portion of the dual-member drill string of  FIG. 12 . 
         FIG. 14  is a cutaway perspective exploded view of an alternative pipe end for use with a collar and retaining ring. 
         FIG. 15  is an exploded side view the alternative pipe end of  FIG. 14 , with the collar and retaining ring shown. 
         FIG. 16  is a sectional view of the pipe end, collar, and retaining ring of  FIGS. 14-15 , showing the retaining ring wedged between the collar and the inner pipe member such that axial movement of the collar relative to the inner pipe member is restricted. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 12 and 13  illustrate a horizontal directional drilling system  10  comprising a drilling rig  12 , a dual-member drill string  14 , a beacon  16 , a tracker  18 , and a borehole  20 . The dual-member drill string  14  comprises an outer drill string  22  formed from a plurality of adjacent outer pipe members  24  and an inner drill string  26  formed from a plurality of adjacent inner pipe members  28 . Adjacent outer pipe members  24  are joined together by a threaded connection. Adjacent inner pipe members  28  are joined together by a torque-transmitting connection that includes a collar  30  and a retaining ring  32 . 
     Dual-member drill strings, such as drill string  14 , are configured to allow relative rotation between the inner drill string  26  and outer drill string  22 , such that rotation of each component drill string  22 ,  26  may perform a separate function. For example, the outer drill string  22  may provide for steering of the drill string  14  while the inner drill string  26  may rotate a drill bit (not shown) at the terminal end of the drill string  14 . 
     Geometric collars, such as collar  30 , allow for easier make-up of adjacent inner pipe members  28 . Further description of dual-member drill strings  14  and pipe joints between adjacent sections is found in U.S. Pat. No. RE 38,418, issued to Deken, the contents of which are fully incorporated herein by reference. 
     With reference to  FIGS. 1-3 , the collar  30  is a tubular member formed from a strong and durable material such as steel. The collar  30  has an inner surface  34 , an outer surface  36 , and a passage  38 . Formed on the inner surface  34  are a plurality of raised longitudinal ridges  40 . Preferably, the inner surface  34  has six raised longitudinal ridges  40 . 
     Situated on a longitudinal collar axis  42 , the collar  30  has opposed first and second ends  44 ,  46 . Adjacent the second end  46 , the collar  30  may have an area of gradually reducing outer circumference  48 . Adjacent the first end  44 , a shoulder  50  and an endless internal groove  52  are formed in the inner surface  34  of the collar  30 . The groove  52  comprises a shallow section  54  and a deep section  56 . The shallow section  54  is situated between the deep section  56  and the first end of the collar  44 , and the shallow section  54  has a depth D. The deep section  56 , the shallow section  54 , and a section of the inner surface adjacent the shoulder  58  have maximum cross-sectional dimensions A, B, and C, respectively. Depth D should be understood to be substantially one-half of the difference between dimensions B and C. 
     Shown in  FIGS. 1 and 4 , the retaining ring  32  is formed from a strong and durable material such as steel. The retaining ring  32  has an arched body  60  having a pair of opposed retaining ring ends  62 . The ends  62  may be pressed together or sprung apart to change the effective outer circumference measured around the retaining ring  32 . Measurement of effective outer circumference should include any space between the ends  62 . The retaining ring  32  is characterized by a maximum cross-sectional dimension E, which exceeds the depth D of the shallow section  54 . In a relaxed position, the retaining ring  32  is sized to be retained within the internal groove  52  of the collar  30 . 
     As shown in  FIG. 4 , the retaining ring ends  62  are separated by a gap and situated in face-to-face relationship. However, in other embodiments, the retaining ring  32  may have a spiral form in which the ends  62  overlap the arched body  60 . 
     As best shown in  FIG. 1 , the retaining ring  32  is installed in the collar  30  by pressing the retaining ring ends  62  together to reduce the effective outer circumference of the retaining ring  32 . Under compression, the retaining ring  32  is inserted into the passage  38  at the first end  44  of the collar  30 . Then the retaining ring  32  is allowed to expand circumferentially within the groove  52 . Once situated in the groove  52 , the axial movement of the retaining ring  32  is limited to the area bounded by the groove  52 . 
     Shown in  FIGS. 5-11 and 13 , the inner pipe member  28  is formed from a strong and durable material such as steel. The inner pipe member  28  has an inner surface  64 , an outer surface  66 , and opposed first and second ends  68 ,  70 . The inner pipe member  28  has a first end section  72  sized to be received within the collar  30 . As shown in  FIG. 11 , the first end section  72  has a hexagonal cross-sectional profile. In other embodiments, the first end section  72  may have the cross-sectional profile of a triangle, a square, a pentagon, a heptagon, an octagon, or any other suitable polygonal shape. The first end section  72  may have a beveled portion  74 . 
     Formed in the outer surface  66  of the inner pipe member  28 , an external shoulder  76  and an endless external groove  78  are positioned adjacent the first end  68 . With reference to  FIG. 8 , the external groove  78  has a bottom  80  and a ramp  82 . An internal angle θ between the bottom  80  and the ramp  82  may be between 120 and 165 degrees. Preferably, the internal angle θ is 135 degrees. 
     Shown in  FIGS. 6-13 , the collar  30  and the inner pipe member  28  are assembled. In this embodiment, the retaining ring  32  is installed in the collar  30  before the inner pipe member  28  and the collar  30  are assembled. The collar  30  and the retaining ring  32  are installed on the inner pipe member  28  by bringing the inner pipe member  28  and the collar  30  together while they are coaxially aligned. This movement results in the first end section  72  of the inner pipe member  28  being received in the passage  38  of the first end  44  of the collar  30 . During assembly, the collar  30  moves axially relative to the first inner pipe member  28  in a first direction  84 . The retaining ring  32  expands circumferentially when it slides over the beveled portion  74  of the first end section  72 . With reference to  FIGS. 7 and 8 , movement of the expanded retaining ring  32  relative to inner pipe member  28  continues in first direction  84 . When the collar  30  and retaining ring  32  pass over the external groove  78  of the inner pipe member  28 , the retaining ring  32  contracts circumferentially and relaxes into the external groove  78 . 
       FIG. 9  shows the collar  30  in fully installed position on the inner pipe member  28 . After assembly, the retaining ring  32  is situated within the grooves  52 ,  78  of both the collar  30  and the inner pipe member  28 . Axial movement of the collar  30  relative to the inner pipe member  28  in the first direction  84  is limited when the internal shoulder  50  of the collar  30  contacts the external shoulder  76  of the inner pipe member  28 . 
     As shown in  FIGS. 6-9 , the installation of the collar  30  on the inner pipe member  28  occurs within the outer drill string  22 , though the outer drill string is not strictly necessary to installation. Use of the collar  30  to connect inner pipe members  28  in a dual-member drill string  14  is advantageous for saving time in making up and breaking the inner drill string connections without threading. The collar  30  may be pinned or welded to one pipe member  28  and the ring  32  used for connection to a received adjacent end section  72 . The “pin end” of an inner pipe member may be on the “downhole” side of the pipe member while the collar  30  is attached to the “uphole” side, though the reverse configuration may be used. Likewise, in a dual-member drill string system, the connection between adjacent inner members  28  may take place before or after outer pipe members  24  are threaded or otherwise connected. 
     In  FIG. 10 , the retaining ring  32  is shown resisting the axial movement of the collar  30  relative to the inner pipe member  28  in a second direction  86  opposite to first direction  84 . When the collar  30  moves in the second direction  86 , the retaining ring  32  expands circumferentially as it slides over the ramp  82  of the inner pipe member  28 . Before cresting the top of the ramp  82 , the retaining ring  32  contacts the bottom  88  of the shallow section  54  of the internal groove  52 . With reference to  FIGS. 3, 4, and 10 , because the maximum cross-sectional dimension E of the retaining ring  32  exceeds the depth D of the shallow section  54 , the retaining ring  32  becomes wedged between the collar  30  and the inner pipe member  28 . By resisting axial movement in the second direction  86 , the connection between the collar  30  and the inner pipe member  28  is maintained. In order to remove the collar  30  from the inner pipe member  28 , force sufficient to deform the retaining ring  32  is applied in the second direction  86 . 
     In the embodiment described above, the retaining ring  32  is installed in the internal groove  52  of the collar  30  prior to connecting the collar  30  to the inner pipe member  28 . However, in another embodiment, the retaining ring  32  may first be installed in the external groove  78  of the inner pipe member  28 . The relaxed retaining ring  32  is sized to be retained within the external groove  78  of the inner pipe member  28 . After inserting the retaining ring  32  into the external groove  78 , the collar  30  and the inner pipe member  28  are coaxially aligned and brought together to form the connection. 
       FIG. 11  shows the outer pipe member  24 , the collar  30 , and the first end section  72  of the inner pipe member  28  centered on the collar axis  42  to form a torque-transmitting relationship between the collar  30  and the inner pipe member  28 . The first end section  72  of the inner pipe member  28  has a plurality of sides  90  in which each pair of adjacent sides  90  is joined together at a vertex  92 . Opposing vertices  92  are separated by a distance F. 
     To facilitate joining the inner pipe member  28  to the collar  30 , the first end section  72  may slide into the collar  30  in any rotational orientation where each vertex  92  is positioned between a pair of adjacent longitudinal ridges  40 . Contact between the longitudinal ridges  40  and the first end section  72  transfers torque between the collar  30  and the inner pipe member  28 . Although  FIG. 11  only shows the first end section  72  of the inner pipe member  28 , the second end  70  of the inner pipe member  28  also has a section having a plurality of sides  90  formed in a polygonal shape to engage the longitudinal ridges  40  of the collar  30 . 
     With reference to  FIGS. 3, 4, and 11 , in an embodiment, the distance between opposite vertices (F) is 1.615 inches, and the maximum cross-sectional dimension of the retaining ring (E) is 0.125 inches. The maximum cross-sectional dimension of the deep section (A) is between 1.865 and 1.875 inches. That dimension equals the sum of the distance between opposite vertices (F) plus twice the maximum cross-sectional dimension of the retaining ring (E) plus a manufacturing tolerance of between 0 and 0.010 inches. The maximum cross-sectional dimension of the shallow section (B) is 1.825 inches which equals the sum of the distance between opposite vertices (F) plus twice the maximum cross-sectional dimension of the retaining ring (E) minus 0.040 inches. 
       FIGS. 12 and 13  show the dual-member drill string  14  in which the collar  30  forms a torque-transmitting connection between identical, adjacent inner pipe members  28 . The first end  44  of the collar  30  surrounds the first end section  72  of one of the inner pipe members  28  so that the internal and external grooves  52 ,  78  are in concentric relationship. The retaining ring  32  is situated within the internal and external grooves  52 ,  78 . The second end  46  of the collar  30  surrounds the second end  70  of an adjacent inner pipe member  28 . During a drilling operation, torque is transmitted between adjacent inner pipe members  28  as the sides go of each inner pipe member  28  contact the longitudinal ridges  40  in the surrounding collar  30  as shown in  FIG. 11 . Disconnection of the collar  30  from the first end section  72  of each inner pipe member  28  is inhibited by the wedged position of the retaining ring  32  between the collar  30  and the ramp  82  of the inner pipe member  28  as shown in  FIG. 10 . 
     With reference to  FIGS. 14-16 , an alternative embodiment of the inner pipe member  128  is shown. The inner pipe member  128  shown has a hexagonal profile for its entire length, though other cross-sectional shapes may be utilized as with pipe member  28 . This pipe member  128  has a similar first end section  72  as pipe member  28  ( FIG. 5 ), but the remainder of the pipe member may also be hexagonal. 
     The inner pipe member  128  has a grooved region  178  consisting of a set of radially-aligned depressions  177  formed in the vertices of the hexagonal profile of the inner pipe member  128 . The grooved region  178  extends from a shoulder  184  to a ramp  182 . 
     The grooved region  178  may be formed on the inner pipe member  128  through rotationally machining the grooved region, thus causing the grooved region to be substantially circular in shape. However, it should be appreciated that being “substantially circular” may allow for certain flat regions where, for example, the sides of the hexagonal pipe member  128  are closer to a center axis of the pipe member than io the radius of the circular grooved region  178  being machined. Likewise, the term “concentric” may be used to describe the grooved region  178  and the internal groove  52  of the collar  30 , despite the fact that the grooved region  178  may only be substantially circular, rather than perfectly circular in cross-section. 
     The grooved region  178  may therefore consist essentially of machined arcuate depressions  177  interconnected by the flat sides of the hexagonal profile. Alternatively, a curved, planar, or angled depression  177  may be formed through the vertices of the pipe member  128  to form each depression  177 , so long as the retaining ring may be situated within the grooved region  178  to restrict the separation of the collar from the end of the pipe section  128 , as shown in  FIG. 16 . 
     Functionally, the design of  FIGS. 14-16  is similar. The retaining ring  32  is preferably installed in the collar  30  before the inner pipe member  128  and the collar  30  are assembled. The collar  30  and the retaining ring  32  are installed on the inner pipe member  128  by bringing the inner pipe member  128  and the collar  30  together while they are coaxially aligned. This movement results in the first end section  72  of the inner pipe member  128  being received in the passage  38  of the first end  44  of the collar  30 . 
     During assembly, the collar  30  moves axially relative to the inner pipe member  128 . The retaining ring  32  expands circumferentially when it slides over the beveled portion  74  of the first end section  72 . 
     When the collar  30  and retaining ring  32  pass over the grooved region  178  of the inner pipe member  28 , the retaining ring  32  contracts circumferentially and relaxes into the grooved region  178 . At this point, the functionality of the grooved region  178  to maintain the collar  30  on the first end section  72  of the inner pipe  128  is the same as in  FIGS. 9 and 10 . 
     As shown in  FIG. 16 , a radial ridge  55  is formed between the shallow portion  54  and the deep section  56  of the internal groove  52 . The ridge  55  has a smaller cross-sectional dimension than either the dimension A of the deep section  56  or dimension B of the shallow section  54 , but greater than dimension C, as shown in  FIG. 3 . Axial movement of the collar  30  relative to the inner pipe member  128  in the first direction  84  is limited when the external shoulder  184  of the inner pipe member  128  causes the ring  32  to contact the radial ridge  55 . 
     Axial movement of the collar  30  relative to the inner pipe member  128  in the second direction  86  is limited as well. As the retaining ring  32  expands circumferentially as it slides over the ramp  182  of the inner pipe member  128 . Before cresting the top of the ramp  182 , the retaining ring  32  contacts the bottom of the shallow section  54  of the internal groove  52 . The combined depth of the depressions  177  of the grooved section  178  and the shallow section  54  of the internal groove  52  are such that the retaining ring  32  acts as a shoulder to prevent further movement of the collar in second direction  86 . 
     Changes may be made in the construction, operation and arrangement of the various parts, elements, steps and procedures described herein without departing from the spirit and scope of the invention as described in the following claims