Patent Publication Number: US-2019178037-A1

Title: Sealing arrangement

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND 
     The present disclosure relates generally, but is not limited, to hole openers for horizontal and vertical drilling through rock. In particular, this disclosure relates to a sealing arrangement that can be employed in a cone arm assembly that is coupled to a bit body of a hole opener or tri-cone bit. 
     Tri-cone bits and hole openers are commonly used to drill and bore through rock. To break apart rock, the tri-cone bits and hole openers typically have one or more cutting elements coupled to a rotating shaft. During operation, the shaft axially loads the cutting elements by forcing the cutting elements against the rock. The rotation of the shaft then causes the hardened surfaces of the cutting elements to break apart the rock. 
     Cone arm assemblies are a commonly used cutting element for this process. The cone arm assemblies have an arm and a cone that rotates relative to a shaft extending outward from the arm. A primary seal is placed between the shaft and the cone to retain lubrication within the cone and to prevent debris and moisture from entering the gaps between the shaft and cone and contacting bearings within the assembly. 
     Due to the abrasive nature of the materials (e.g., rock) being cut and the axial and radial loading and impacts experienced by the cone arm assembly during the cutting process, the primary seal is often subject to failure. The cone arm assembly is often submersed in gritty mud and bentonite mixtures, which suspend sharp rock and abrasive materials that can come into contact with and damage the shaft and seals of the cone arm assembly during cutting. Repeated use of the cone arm assembly can also result in material buildups (e.g., cuttings or debris) forming between the shaft and the cone. The material buildups within the cone arm assembly can cause grinding between the cone and arm during rotation, which produces high temperatures within the cone arm assembly. The high temperatures experienced within the cone arm assembly can damage the primary seal. Once the primary seal has been compromised, contaminants can contact and damage the bearings, which can eventually lead to cone arm assembly failure. 
     Cone arm assemblies are also subject to damage from the weather, as they are often left outside for extended periods of time, where rain, snow, dust, or other debris can contact and damage the primary seal within the cone arm assembly. As more debris and moisture passes beyond the primary seal, the bearings present upon the shaft may be damaged, which can result in cone arm assembly failure. 
     A need exists for an improved cone arm assembly that is able to withstand the harsh conditions experienced during rock drilling and boring processes for prolonged periods of time. 
     BRIEF SUMMARY 
     The present disclosure provides a cone arm assembly having a sealing arrangement that distributes and dissipates the loading experienced by the cone arm assembly during operation to prolong the life of the primary seal. The cone arm assembly restricts moisture and abrasive materials from contacting the primary seal. 
     In one embodiment, the present disclosure provides a cone arm assembly. The cone arm assembly comprises an arm having a shaft extending therefrom. The shaft is angularly surrounded by a shoulder surface on one end of the shaft. A cone has a recess formed therein that receives the shaft in a manner to permit a rotation of the cone relative to the shaft about a rotational axis. The cone has a base surface facing the shoulder surface of the arm. A first seal element is positioned within the recess, and forms a first seal between the shaft of the arm and the cone. A second seal element is positioned within the recess and forms a second seal between the shaft of the arm and the cone. The second seal element is positioned closer to the shoulder surface than the first seal element. A third seal element forms a third seal between the base surface of the cone and the shoulder surface of the arm. 
     In some embodiments, a groove extends inward from the base surface of the cone, which can receive the third seal element. The groove can comprise a first side wall, a second side wall, and a bottom wall. The first side wall, second side wall, and the bottom wall can collectively extend circumferentially about the base surface of the cone. In some embodiments, the recess is formed of a first cylindrical section and a second cylindrical section. The first cylindrical section can be defined by a first radius and can extend inwardly away from the base surface of the cone. The second cylindrical section can be defined by a second radius smaller than the first radius, and can extend inwardly away from the first cylindrical section. A first channel and a second channel can be formed within the first cylindrical section, and the first channel can receive a portion of the first seal element, while the second channel can receive a portion of the second seal element. 
     In some embodiments, at least one bearing is coupled to the shaft. The at least one bearing can be positioned distally away from the first seal element, the second seal element, and the third seal element. In some embodiments, the third seal element is positioned radially outward from the first seal element and the second seal element. The first seal element, second seal element, and third seal element can each be positioned concentric with the rotational axis, but at different axial positions with respect to one another. 
     These and still other advantages of the invention will be apparent from the detailed description and the drawings. What follows is merely a description of some preferred embodiments of the present invention. To assess the full scope of the invention, the claims should be looked to, as these preferred embodiments are not intended to be the only embodiments within the scope of the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be better understood and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such detailed description makes reference to the following drawings. 
         FIG. 1  is a perspective view of a cone arm assembly according to one exemplary embodiment. 
         FIG. 2A  is a cross-sectional view of the cone arm assembly of  FIG. 1  taken along line  2 A- 2 A. 
         FIG. 2B  is a detail view of the cone arm assembly taken along arc  2 B- 2 B of  FIG. 2A . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the embodiments of the present disclosure. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a cone arm assembly  10  for drilling and boring through earth and rock. The cone arm assembly  10  includes an arm  12  and a cone  14  that can rotate about the arm  12 . A plurality of teeth  16  can be positioned about the cone. The teeth  16  can be formed of a hardened material, like tungsten carbide. In some embodiments, the teeth  16  are tungsten carbide inserts removably coupled to the cone  14 . 
     With further reference now to  FIGS. 2A and 2B , the internal structure of the cone arm assembly  10  is shown. The arm  12  has a mounting surface  18  that can be coupled to a bit body (not shown) of a hole cutter or a tri-cone bit. In some embodiments, the mounting surface  18  of the arm  12  can be coupled to a pocket (not shown) formed in the bit body using a key and slot interface, as shown and described in U.S. Pat. No. 7,845,437 B2, which is hereby incorporated by reference in its entirety. A plurality of threaded holes  20  can extend through the mounting surface  18  to receive fasteners or pins that can be used to couple the arm  12  to the bit body. 
     A shoulder surface  22  extends away from the mounting surface  18 . In some embodiments, the shoulder surface  22  extends away from the mounting surface  18  to form a substantially flat surface. The shoulder surface  22  can be angularly offset from the mounting surface  18 . In some embodiments, the offset between the mounting surface  18  and the shoulder surface  22  forms an obtuse angle (i.e., greater than 90 degrees) between the mounting surface  18  and the shoulder surface  22 . A shaft  24  extends outwardly away from the shoulder surface  22  to define a rotational axis X-X. The shaft  24  can be generally cylindrical in shape. 
     The cone  14  is rotatably coupled to the shaft  24 . The shaft  24  is received within a recess  26  formed in the cone  14 . One or more bearings  28 ,  30 ,  32  can be positioned between the shaft  24  and the recess  26  formed in the cone  14  to enable precise rotation of the cone  14  on the shaft  24  and to reduce friction between the recess  26  and the shaft  24  as the cone  14  rotates. Seal elements  34 ,  36 ,  38  are positioned between the arm  12  and cone  14  to restrict abrasive materials, moisture, and other unwanted contaminants from entering into the recess  26  and contacting or damaging the bearings  28 ,  30 ,  32 . In some embodiments, the first seal element  34 , the second seal element  36 , and the third seal element  38  can each be positioned concentric with the rotational axis X-X, but at different axial positions with respect to one another. 
     The first seal element  34  can be positioned within the recess  26  and can form a first seal between the shaft  24  and the cone  14 . In some embodiments, the first seal element  34  is positioned axially between the bearing  32  and a base surface  40  of the cone  14 . The first seal element  34  can act as a primary seal between the bearings  28 ,  30 ,  32  and rock, earth, or moisture that is present outside the cone arm assembly  10 . The first seal created by the first seal element  34  can also retain lubrication present within the bearings  28 ,  30 ,  32  to extend bearing life. The first seal element  34  can be an o-ring, and can be formed of a resilient elastomeric material. For example, the first seal element  34  can be formed of a hydrogenated nitrile butadiene rubber (HNBR). 
     The second seal element  36  can also be positioned within the recess  26  and can form a second seal between the shaft  24  and the cone  14 . The second seal element  36  can be positioned axially between the first seal element  34  and the base surface  40  of the cone  14 . The second seal element  36  can form a secondary seal between the bearings  28 ,  30 ,  32  and abrasive materials or moisture external to the cone arm assembly  10 . In some embodiments, the second seal element  36  acts as a radial dampener between the cone  14  and the arm  12 . The second seal element  36  can dissipate energy within the cone arm assembly  10  that is created by cyclic loading during cutting or drilling processes. The second seal element  36  can also provide shock absorption to counter intermittent shock loads that may be experienced by the cone arm assembly  10 . The second seal element  36  can also be formed of an elastomeric material, and can be an o-ring, quad-ring, or other type of dynamic rotary seal. In some embodiments, the second seal element  36  can be a PolyPak® seal having an o-ring used to energize a conventional lip-type seal. 
     The third seal element  38  can be positioned between the base surface  40  of the cone  14  and the shoulder surface  22  of the arm  12 . The third seal element  38  can form a third seal between the shoulder surface  22  and the base surface  40  of the cone  14  that further restricts abrasive materials or unwanted moisture from contacting the bearings  28 ,  30 ,  32 . Due to its placement between the shoulder surface  22  and the base surface  40  of the cone  14 , the third seal element  38  can restrict unwanted contaminants from entering into the recess  26  of the cone  14  altogether. The third seal element  38  can be formed of a resilient elastomeric material, such as urethane, for example. In some embodiments, the third seal element  38  has a Shore A hardness exceeding 60. In some embodiments, the third seal element  38  can have a composite seal design incorporating an elastic static energizer element and a wear-resistant material on the dynamic sealing surfaces. A PolyPak® seal, for example, can also be used as the third seal element  38 . 
     The third seal element  38  restricts the amount of contaminants and abrasive material that can enter into the recess  26 , which can improve the life of the second seal element  36  and first seal element  34  respectively. The third seal element  38  also protects the second seal element  36  and the first seal element  34  when the cone arm assembly  10  is not performing a cutting or drilling process. In many scenarios, hole openers or tri-cone bits having cone arm assemblies  10  are stored outside and are exposed to the outdoor elements for extended periods of time. Rain, dust, dirt, and other unwanted contaminants may contact the cone arm assembly  10  before, during, and after use. The third seal element  38  can protect the recess  26  from these contaminants, which could otherwise cause recess  26  wall corrosion, shaft  24  corrosion, or bearing  28 ,  30 ,  32  corrosion if left in contact with the internal components of the cone arm assembly  10 . By maintaining a seal between the shoulder surface  22  and the base surface  40  of the cone  14 , rust or other corrosion that may prevent or restrict rotation of the cone  14  relative to the arm  12  is reduced. Correspondingly, the bearing  28 ,  30 ,  32  life, first seal element  34  life, second seal element  36  life, and overall cone arm assembly  10  life is improved. 
     The third seal element  38  also serves as a dampener that counteracts axial loading experienced by the cone arm assembly  10  during cutting or drilling processes. The resilient nature of the third seal element  38  provides additional protection to internal components (e.g., bearings  28 ,  30 ,  32 ) present within the recess  26  of the cone  14  that may otherwise be affected by sudden impacts or shock loading imparted on the cone  14 . The third seal element  38  can also help restrict sudden contact that may occur between the base surface  40  and the shoulder surface  22 . In some embodiments, the shoulder surface  22  and the base surface  40  are approximately parallel to one another, and the distance between the shoulder surface  22  and the base surface  40  is between about 0.038 cm (0.015 in) and about 0.064 cm (0.025 in). The cone  14  may deflect relative to the shaft  24  when it is axially loaded during cutting or drilling, and the base surface  40  may be biased toward the shoulder surface  22 . The dampening properties of the third seal element  38  can dissipate the energy from the axial loading, reducing the impact (if any) that occurs between the base surface  40  and the shoulder surface  22 . The third seal element  38  can extend upwardly from the base surface  40  of the cone  14  as well, so that contact occurs between the shoulder surface  22  and the third seal element  38  before contact can occur between the shoulder surface  22  and the base surface  40 . 
     The shape of the shaft  24  can help locate the seal elements  34 ,  36 ,  38  and the bearings  28 ,  30 ,  32  within the cone arm assembly  10 . In some embodiments, the shaft  24  has a tiered structure, and includes a first section  42  proximate to the shoulder surface  22  and a second section  44  extending outwardly away from the first section  42 . The first section  42  can be defined by a radius R 1  larger than a radius R 2  defining the second section  44 . A first annular surface  46  can be formed at the meeting of the first section  42  and the second section  44 . A third section  48  can extend outwardly from the second section  44 , and a second annular surface  50  can be formed at the meeting of the second section  44  and the third section  48 . The third section  48  can be defined by a radius R 3  smaller than the radius R 2 . In some embodiments, a distal section  52  extends outwardly from the third section  48 . The distal section  52  can be defined by a radius R 4  that is larger than the radius R 3 . A third annular surface  54  opposing the second annular surface  50  can be formed at the junction of the third section  48  and the distal section  52 . In some embodiments, the radius R 4  is smaller than the radius R 2 . A distal end  55  of the shaft  24  can be defined by the distal section  52 . 
     In some embodiments, a plurality of grooves  56 ,  58  are formed in the shaft  24  to receive bearings  28 ,  30 ,  32 . For example, a first bearing groove  56  can be formed in the first section  42 . In some embodiments, the first bearing groove  56  has a semicircular cross-section and extends circumferentially around the shaft  24 . In some embodiments, the first bearing groove  56  acts as a race for one or more ball bearings  30 . A second bearing groove  58  can also be formed in the shaft  24 . The second bearing groove  58  can be defined by a portion of the second annular surface  50 , the outer surface of the third section  48 , and the third annular surface  54 . The second bearing groove  58  can also extend circumferentially around the shaft  24 , and can support one or more roller bearings  28 . 
     The shaft  24  is received within the recess  26  formed within the cone  14 . The recess  26  extends inward from the base surface  40  of the cone  14  that faces the shoulder surface  22  of the arm  12 . The recess  26  can form a clearance fit with the shaft  24 , permitting the rotation of the cone  14  about the shaft  24 . In some embodiments, the recess  26  is formed of a first cylindrical section  60  and a second cylindrical section  62 . The first cylindrical section  60  can extend inwardly away from the base surface  40  and can be defined by a radius R 5 . The radius R 5  can be larger than the radius R 1 , so that the first section  42  of the shaft  24  can form a clearance fit with the first cylindrical section  60  of the recess  26 . A second cylindrical section  62  can extend inwardly away from the first cylindrical section  60 , and can be defined by a radius R 6  smaller than the radius R 5 . A step  64  can be formed at the junction between the first cylindrical section  60  and the second cylindrical section  62 . The radius R 6  can be larger than the radii R 2 , R 3 , and R 4 , so that the second section  44 , the third section  48 , and the distal section  52  can form a clearance fit with the second cylindrical section  62  of the recess  26 . When the cone  14  is coupled to the arm  12 , the first annular surface  46  can engage the step  64 . A thrust washer  66  can be positioned between the first annular surface  46  and the step  64 . In some embodiments, a lubrication reservoir  68  extends inwardly away from the second cylindrical section  62 . 
     The recess  26  within the cone  14  can also be defined by one or more bearing grooves  70 ,  72  extending circumferentially around the recess  26 . In some embodiments, a first bearing groove  70  is formed in the first cylindrical section  60 . The first bearing groove  70  can have a semicircular cross-section that extends inwardly from the first cylindrical section  60 . When the cone  14  is coupled to the shaft  24 , the first bearing groove  70  can serve as the outer race for one or more ball bearings  30 , and can be axially aligned with the first bearing groove  56  formed in the shaft  24 . A second bearing groove  72  can be formed in the first cylindrical section  60  of the recess  26  as well. In some embodiments, the second bearing groove  72  has a rectangular cross-section, and can support one or more roller bearings  32 . The second bearing groove  72  can be positioned axially between the base surface  40  and the first bearing groove  70 . 
     In some embodiments, the cone  14  is coupled to the shaft  24  using the ball bearings  30 . The ball bearings  30  can be introduced between the first bearing groove  56  formed in the shaft and first bearing groove  70  formed in the cone  14  using a bearing insertion hole  73 , which extends through a portion of the arm  12  and the shaft  24 . Once the ball bearings  30  are placed within the first bearing grooves  56 ,  70 , the ball bearings  30  restrict relative axial motion between the shaft  24  and the cone  14 , coupling the shaft  24  to the cone  14 . The ball bearings  30  also promote rotational motion of the cone  14  about the shaft  24 . 
     The recess is further defined by channels  74 ,  76  that receive seal elements  34 ,  36 . A first channel  74  can be formed in the first cylindrical section  60 . The first channel  74  can have a rectangular cross-section and can be positioned axially between the base surface  40  and the second bearing groove  72 . The first channel  74  can be defined by an upper wall  78 , a lower wall  80 , and a radial wall  82  extending between the upper wall  78  and lower wall  80 . The radial wall  82  can extend circumferentially about the cone  14 . The radial wall  82  can be defined by a radius R 7  that is larger than the radius R 5  that defines the first cylindrical section  60 . The first seal element  34  can be received within the first channel  74 , where it forms a seal between the shaft  24  and the cone  14 . In some embodiments, an adhesive can be used to couple the first seal element  34  to at least one of the upper wall  78 , the lower wall  80 , and the radial wall  82 . In other embodiments, the upper wall  78 , the lower wall  80 , and the radial wall  82  compress the first seal element  34  to secure the first seal element  34  in place. 
     The second channel  76  can be positioned axially between the base surface  40  and the first channel  74 . Like the first channel  74 , the second channel  76  can also be defined by an upper wall  84 , a lower wall  86 , and a radial wall  88  extending between the upper wall  84  and the lower wall  86 . The radial wall  88  can be defined by a radius R 8  that is also larger than the radius R 5 , and can extend circumferentially about the cone  14 . In some embodiments, the radius R 8  is smaller than the radius R 7 . The second seal element  36  is received within the second channel  76 , and forms a seal between the shaft  24  and the cone  14 . The second seal element  36  can be coupled to the second channel  76 . In some embodiments, the second seal element  36  is compressed by the upper wall  84  and lower wall  86  to maintain the second seal element  36  within the second channel  76 . Adhesive can also be used to secure the second seal element  36  within the second channel  76 . 
     A groove  90  can be formed in the base surface  40  of the cone  14  to receive the third seal element  38 . The groove  90  can be defined by a first side wall  92 , a second side wall  94 , and a bottom wall  96 . The first side wall  92 , the second side wall  94 , and the bottom wall  96  can extend circumferentially about the base surface  40 . The third seal element  38  can be received within the groove  90 , where it can then form the third seal between the base surface  40  and the shoulder surface  22 . In some embodiments, the groove  90  can instead be formed in the shoulder surface  22  of the arm  12 . 
     In some embodiments, the bottom wall  96  of the groove  90 , the upper wall  78  of the first channel  74 , and the upper wall  84  of the second channel  76  each lie in approximately parallel planes. For example, each of the bottom wall  96  of the groove  90 , the upper wall  78  of the first channel  74 , and the upper wall  84  of the second channel  76  form flat surfaces approximately perpendicular to the rotational axis X-X. In some embodiments, the bottom wall  96  of the groove  90  is formed at a first depth D 1  from the base surface  40 . The upper wall  84  of the second channel  76  can be formed at a second depth D 2  from the base surface  40  that is greater than the first depth D 1 . In some embodiments, the first side wall  92  and the second side wall  94  are positioned radially outward from the radial wall  88  of the second channel  76 . The third seal element  38  can then be positioned radially outward from the first seal element  34  and the second seal element  36 . 
     Using the seal element  34 ,  36 ,  38  configurations described in detail above, the life of the cone arm assembly  10  can be extended. The three seal element configuration present in the cone arm assembly  10  protects the internal components of the cone arm assembly  10  from corrosion and contamination during both operation and idle periods. The sealing and dampening provided by the sealing arrangement better counteracts impact loading experienced during cutting and drilling processes that could otherwise cause cone arm assembly  10  failure. 
     It should be appreciated that various other modifications and variations to the preferred embodiments can be made within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiments. To ascertain the full scope of the invention, the following claims should be referenced.