Abstract:
A tensioning apparatus for operably applying forces to inner surfaces of a hollow body includes a bracing nut having a first receptacle portion and a bracing portion, an axially movable rod that is operably coupled to the bracing nut such that a first portion of the rod is selectively axially movable within the bracing nut, a wedge structure that is operably engaged with the rod for coaxial movement therewith, and a tensioning body that is operably and slidably engaged with the wedge structure. The tension body and the wedge structure have corresponding and facing sloped surfaces such that selectively axial motion of the rod correspondingly and coaxially moves the wedge structure, which coaxial movement of the wedge structure therefore progressively radially displaces the tensioning body to provide tensioning forces against respective inner surfaces of the hollow body.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Provisional Patent Application Ser. No. 60/376,358, filed Apr. 29, 2002, the contents of which are herein incorporated in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to systems for installing underground pipe, generally, and more particularly to devices and methods for installing sectioned pipe into pre-bored underground channels. 
     BACKGROUND OF THE INVENTION 
     The present invention is contemplated for use with underground channel boring systems, the invention being adapted to simplify and expedite the installation of pipes into such underground channels. In typical applications, underground channels are bored between two predetermined points, which points are typically exposed to the surface for access by personnel and/or equipment. A particular such channel boring operation provides for initial boring by a linearly-driven pilot tube, which pilot tube establishes a pathway for which channel boring augers may follow from a starting point to an end point. 
     Preferably, the starting and ending points for channel boring are defined by personnel/equipment shafts which extend upwardly to the ground surface. In such a manner, boring equipment and pipes may be staged, assembled, or disassembled within respective personnel/equipment shafts. Typically, however, the bored channels are too long for a single pipe section to be brought into the respective personnel/equipment shafts and subsequently positioned within the bored underground channel. Therefore, the underground pipes must be assembled from a plurality of pipe sections that are sequentially inserted into the underground channel. Systems available today for installing such pipe sections are relatively time consuming and expensive. In addition, available means for holding adjacent pipe sections together during the pipe insertion process are typically not strong enough to reliably insert such pipe sections into a bore having an inner diameter substantially similar to the outer diameter of the sectioned pipe. Forces exerted on the sectioned pipe, particularly at the respective connection points, can result in undesired separation of the pipe sections. 
     Therefore, it is a primary object of the present invention to provide a means for installing a plurality of mutually secured pipe sections into an underground channel in an expeditious and cost-effective manner. 
     It is a further object of the present invention to provide a means for internally grasping and maintaining adjacent pipe sections in axially connected relationship with one another during insertion thereof into a bored channel. 
     It is a still further object of the present invention to provide an internal tensioning means for selectively and repositionably grasping adjacently connected pipe sections, which tensioning means is configured so as to be manipulated by existing equipment used for boring underground channels. 
     SUMMARY OF THE INVENTION 
     By means of the present invention, a device and system is provided for securably positioning sectioned pipe into bored channels of a diameter similar to that of the pipe. The selectively and remotely positionable device of the present invention expansively provides tension forces to respective pipe sections across seams therebetween, which tension forces are sufficient to maintain the axially connected relationship between such adjacent pipe sections during pipe installation. The present assembly is preferably configured to adapt to mechanized components commonly utilized in underground channel boring operations. As such, the apparatus of the present invention may be easily assimilated into current pipe installation procedures for enhanced stability and reliability of installed sectioned pipe integrity. 
     In a particular embodiment of the present invention, the tensioning apparatus includes a bracing nut having a first receptacle portion and a bracing portion, an axially movable rod that is operably coupled to the bracing nut such that a first portion thereof is selectively axially movable therewithin, and a wedge structure having a first inner surface and a second outer surface, with the second outer surface being sloped with respect to the first inner surface, the first inner surface being operably engaged with an outer surface of the rod for coaxial movement therewith, the wedge structure at least partially concentrically surrounding a second portion of the rod. The tensioning apparatus preferably further includes a tensioning body having a first inner surface and a second outer surface, with the first inner surface being operably and slidably engaged with the second outer surface of the wedge structure. The first inner surface of the tensioning body is preferably sloped with respect to the second outer surface thereof, such that the second outer surface of the tensioning body is operably disposed in a generally parallel relationship with the first inner surface of the wedge structure. The first inner surface of the tensioning body and the second outer surface of the wedge structure are in facing relationship with one another, such that selectively axial motion of the rod correspondingly and coaxially moves the wedge structure, which coaxial movement of the wedge structure progressively radially displaces the tensioning body. 
     The present invention further contemplates and includes a method for retaining a hollow sectioned body in an axially connected disposition through the application of tension forces to inner surfaces thereof. Such a method includes providing a plurality of hollow body sections in axially adjacent and connected relationship with one another, and providing a tensioning apparatus having a bracing nut which has first and second receptacle portions and a bracing portion, with the second receptacle portion being positioned at a side opposite to the first receptacle portion, and the second receptacle portion being specifically configured to operably receive a control rod for axial manipulation of the tensioning apparatus. The bracing portion of the bracing nut is preferably radially disposed about the first receptacle in a plane perpendicular to a central axis of the bracing nut. The tensioning apparatus further includes an axially movable rod that is operably coupled to the bracing nut such that a first portion thereof is threadably received in the bracing nut, a wedge structure having a first inner surface and a second outer surface, with the second outer surface being sloped with respect to the first inner surface, the first inner surface being operably engaged with an outer surface of the rod for coaxial movement therewith, the wedge structure at least partially concentrically surrounding a second portion of the rod, and a tensioning body having a first inner surface and a second outer surface. The first inner surface of the tensioning body is operably and slidably engaged with the wedge structure, and the first inner surface thereof is sloped with respect to the second outer surface such that the second outer surface of the tensioning body is operably disposed in a generally parallel relationship with the first inner surface of the wedge structure. The first inner surface of the tensioning body and the second outer surface of the wedge structure are in facing relationship with one another, such that rotation of the rod results in axial motion along an axis of rotation thereof in a first direction correspondingly and coaxially moves the wedge structure, which coaxial movement of the wedge structure progressively outwardly and radially displaces the tensioning body. The method further includes positioning the tensioning body within the hollow sectioned body at a seam between adjacently connected body sections, and rotating the rod to threadably and axially move the rod in the first direction to thereby radially displace the tensioning body toward respective inner surfaces of the body sections. The method continues by engaging the second outer surface of the tensioning body with respective inner surface of the hollow body sections to thereby obtain a tension force therebetween that is sufficient to maintain the hollow body sections in adjacent axially connected relationship with one another upon insertion into a correspondingly-configured bore. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a tensioning apparatus of the present invention, as disposed within a sectioned pipe while in a contracted state. 
         FIG. 2  is a cross-sectional view of a bracing means component of the tensioning apparatus of the present invention. 
         FIG. 3  is a cross-sectional view of a threaded rod component of the tensioning apparatus of the present invention. 
         FIG. 4  is a cross-sectional view of a wedge means component of the tensioning apparatus of the present invention. 
         FIG. 5  is a cross-sectional view of the apparatus illustrated in  FIG. 1 , with the illustration in  FIG. 5  showing the tensioning apparatus in an expanded state. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The objects and advantages enumerated above together with other objects, features and advances represented by the present invention will now be presented in terms of detailed embodiments described with reference to the attached drawing figures which are intended to be representative of various possible configurations of the invention. Other embodiments and aspects of the invention are recognized as being within the grasp of those having ordinary skill in the art. 
     With attention now to characters of reference to the drawings, and first to  FIG. 1 , a tensioning device  10  of the present invention is illustrated as being disposed within adjoining pipe sections  12 ,  14 . As shown in  FIG. 1 , tensioning device  10  includes a bracing portion  22 , an axially-extending tension portion  34 , a wedge portion  42  and a threaded rod  60 . In operation, threaded rod  60  acts to axially push or pull wedge portion  42 , such that tension portion  34  is selectively circumferentially displaced so as to selectively engage inner surfaces of respective adjacent pipe sections  12 ,  14 . 
     Bracing portion  22  is preferably configured substantially as a threaded nut, with threaded portion  24  disposed oppositely of connector portion  26 . Connector portion  26  is preferably configured to engagably receive a correspondingly configured control rod (not shown) in socket  27 . In a particular embodiment of the present invention, the control rod includes extendable dogs which engage in locking recesses  28  of socket  27 . Locking recesses  28  are preferably specifically configured to receive the extendable dogs on the control rod, and are preferably positioned in substantially opposing surfaces of socket  27 . In other embodiments of the present invention, locking recess  28  is a continuous annular groove disposed in inner surface  29  of socket  27 . In such a manner, an annular ring or other radial extension on the control rod may be fittingly engaged within locking recess  28 . 
     Once a secure engagement is obtained between the control rod and bracing portion  22 , the control rod may be manipulated to axially move bracing portion  22 , as well as all other attached components of tensioning device  10 , within the respective underground pipe. The present invention contemplates a variety of configurations for the securing engagement between bracing portion  22  and the control rod. Preferably, however, a removable “snap-fit” engagement therebetween is most preferred. Therefore, any protrusions such as extendable dogs on the control rod are preferably selectively retractable when disengagement of the control rod from bracing portion  22  is desired. 
     In preferred embodiments of the invention, threaded portion  24  is substantially oppositely disposed from socket  27  in bracing portion  22 , and most preferably disposed along a central axis of bracing portion  22 . Thus, rotational threading engagement at threaded portion  24  is about a central axis defined thereby. Threaded portion  24  of bracing portion  22  further defines an opening to threaded rod receiving port  31 . Receiving port  31  provides excess space into which first bearing portion  62  of threaded rod  60  may axially move. As shown in  FIG. 1 , receiving port  31  is sized and configured to accommodate first bearing portion  62  of threaded rod  60 . In operation, first bearing portion  62  of threaded rod  60  is retained within inner surface  32  of receiving port  31  to thereby maintain engagement between threaded rod  60  and bracing portion  22 . 
     Threaded rod  60  is shown in an isolation view of FIG.  3 . Threaded rod  60  includes threaded portion  64  which is preferably sized and configured to threadably mate with threaded portion  24  of bracing portion  22 . In addition to first bearing portion  62 , threaded rod  60  preferably includes second bearing portion  66  and third bearing portion  68  disposed at specific intervals along the length of threaded rod  60 . Respective bearing portions  62 ,  66 ,  68  extend substantially transversely to a longitudinal axis  71  of threaded rod  60 . 
     As shown in  FIG. 3 , third bearing portion  68  preferably includes a cut-out portion  70  radially disposed therein. In preferred embodiments, cut-out portion  70  is a radius sized and configured to receive a ring bearing  72  therein. Ring bearing  72  provides for efficient rotational movement of threaded rod  60  as bearing surface  69  is placed in close proximity to a respective surface of wedge portion  42 . In operation, ring bearing  72  is in contact with an exterior surface  44  of wedge portion  42 , such that bearing surface  69  is not frictionally engaged with surface  44  during rotation of threaded rod  60 . 
     Threaded rod  60  further includes a coupling portion  76  that is sized and configured to receive a rotatable device thereto. In preferred embodiments of the present invention, the rotating spindle which drives the soil boring device is adapted to operably couple to coupling portion  76  of threaded rod  60 . In such a manner, rotational movement may be employed upon threaded rod  60  from the soil boring device in selectively clockwise or counter-clockwise direction. Direct coupling of such rotation means provides selective axially movement of threaded rod  60  within tensioning device  10  via respective threaded portions  64  and  24 . 
     Wedge portion  42  is shown in isolation view in FIG.  4 . In preferred embodiments, wedge portion  42  includes an inclined bearing surface  46  upon which radially extending tension portion  34  operably bears. When assembled in tensioning device  10 , first bearing surface  44  of wedge portion  42  is selectively pressed against by third bearing portion  68  through threaded rotation of threaded rod  60  during the engagement sequence of tensioning device  10  expanding radially outwardly toward inner surfaces of respective pipe sections  12 ,  14 . Second bearing surface  48  of wedge portion  42  is primarily preferably placed into contact with second bearing portion  66  of threaded rod  60  during threaded retraction of threaded rod  60  from bracing portion  22 . During such a sequence, second bearing portion  66  progressively bears against second bearing surface  48  of wedge portion  42  to thereby retract radially expanding tensioning means  34  inwardly. In such a manner, wedge portion  42  is operably utilized to selectively radially expand and contract tensioning device  10  via inclined bearing surface  46 . 
     With reference now to  FIGS. 1 and 5 , tensioning device  10  is illustrated in both an expanded and a contracted state. Tensioning device  10  is illustrated in a contracted configuration in  FIG. 1 , with threaded rod  60  disposed in a relatively extended position, minimally threaded within bracing portion  22 . The control rod manipulates bracing portion  22 , as well as the remainder of tensioning device  10 , into a position adjacent a seam between respective pipe sections  12 ,  14 . Once tensioning device  10  has been properly positioned, rotation of threaded rod  60  is initiated by the rotation means of the boring device (not shown). A predefined rotational direction, i.e. clockwise, causes the threaded engagement between threaded portion  64  of threaded rod  60  and threaded portion  24  of bracing portion  22  to axially move threaded rod  60  into receiving port  31  of bracing portion  22 . Axial movement of threaded rod  60  dictated by the aforementioned threaded engagement results in pressure imparted upon first bearing surface  34  of wedge portion  42  from third bearing portion  68  of threaded rod  60 . In preferred embodiments, bearing  72  transfers the pressure from bearing portion  68  of threaded rod  60  to first bearing portion  44  of wedge portion  42 , thereby minimizing frictional forces developed at the interface between third bearing portion  68  and wedge portion  42  due to rotational movement of threaded rod  60 . 
     Continued rotation of threaded rod  60 , and the resultant force upon first bearing surface  44 , moves wedge portion  42  axially toward bracing portion  22 . During such axial movement of wedge portion  42 , inclined bearing surface  46  progressively displaces tensioning portion  34  radially outwardly. Such radial displacement is obtained due to the respective corresponding inclined surfaces of wedge portion  42  and tensioning portion  34 . In addition, bracing surface  33  of bracing portion  22  prevents axial displacement of tensioning portion  34  as a result of axial movement of wedge portion  42  and the associated frictional forces therebetween. 
     Rotation of threaded rod  60  is preferably continued until desired engagement is obtained between tension surface  36  of tensioning portion  34  and respective inner surfaces of pipe sections  12 ,  14 . In a preferred embodiment of the present invention, one or more roller bearings  37  are provided in bearing surface  36  of tensioning means  34 , such that frictional forces developed between the rotating tension device  10  and respective pipe sections  12 ,  14  is minimized. Such roller bearing  37  may be of any desired configuration, so long as frictional forces between tensioning means  34  and respective pipe sections  12 ,  14  are dissipated thereby. 
     In some embodiments of the present invention, wedge portion  42  and tensioning portion  34  are removably or permanently engaged with one another through various engagement means. An example of such an engagement means includes a tongue and groove configuration, whereby wedge portion  42  and tensioning portion  34  are slidably and engagably received in one another. Such engagement between wedge portion  42  and tensioning portion  34  promotes reliable radial expansion and contraction, and minimizes risk of undesired disassembly of tensioning device  10 . 
     In some embodiments of the present invention, tensioning portion  34  is removably and slidably engaged with bracing surface  33  of bracing portion  22 . Such engagement further promotes reliable and accurate expansion and contraction of tensioning device  10 . 
     Preferably, wedge portion  42  is removably or permanently engaged with rod  60  through various engagement means. An example of such an engagement means includes a tongue and groove configuration whereby wedge portion  42  is slidably and engagably secured to rod  60 . 
     Tensioning device  10  is illustrated in  FIG. 5  in an expanded configuration, whereby tensioning portion  34  is in physical abutment with respective inner surfaces of pipe sections  12 ,  14 . Such an abutment creates a tensioning engagement therebetween, and acts to assist in holding respective pipe sections  12 ,  14  together. As illustrated in  FIGS. 1 and 5 , respective pipe sections  12 ,  14  are preferably threadably engaged with one another. In other embodiments, however, respective pipe sections  12 ,  14  may be engaged through other means, such as fasteners, adhesives, or the like. As the engaged pipe sections  12 ,  14  are inserted into the bored underground channel, resistive forces such as impediments or friction alone create an environment and potential of disengagement between respective pipe sections  12 ,  14 . Tensioning device  10  of the present invention is specifically designed to assist in preventing such disengagement between respective pipe sections  12 ,  14 . By providing sufficient expansion force on the inner surfaces of respective pipe sections  12 ,  14 , a tension force is created therebetween due to the high levels of friction between tensioning surface  36  and respective pipe sections  12 ,  14 . To enhance the frictional force developed between tensioning surface  36  and respective inner surfaces of pipe sections  12 ,  14 , tensioning surface  36  may be uneven, or “jagged”. Such an uneven surface acts to partially bite into the respective inner surfaces of pipe sections  12 ,  14 , thereby enhancing the frictional force obtained. Such frictional force inhibits relative axial motion between respective pipe sections  12 ,  14 . 
     In some embodiments of the present invention, pipe sections  12 ,  14  may not be engaged in an overlapping relationship, as is illustrated in the figure. In such embodiments, respective pipe sections  12 ,  14  may be placed in substantially abutting configuration. To assist in engaging the respective pipe sections to one another in such an embodiment, adhesives or separate fastening devices, or both are preferably utilized. Such a fastening device may include, for example, an external ring binder which extends circumferentially about respective pipe sections  12 ,  14  at the seam between respective abutted sections. In such embodiments, the tensioning device  10  of the present invention is highly desirable to obtain a tension force between respective pipe sections  12 ,  14 . 
     In preferred embodiments of the present invention, tensioning device  10  is able to develop at least about 25,000 pounds of expansion force, and up to about 70,000 pounds of expansion force. Such an expansion force creates a more than necessary amount of tension force (as a result of friction between tensioning portion  34  and respective pipe sections  12 ,  14 ) to maintain engagement between respective pipe sections  12 ,  14  during pipe insertion into the underground bored tunnel. 
     In operation, tensioning device  10  is utilized to enhance engagement between respective adjacent pipe sections during insertion into the underground channel. The selective expansion/contraction capability of tensioning device  10  allows the tensioning device  10  to be selectively utilized at multiple locations along the constructed pipe. To contract tensioning device  10 , rotation in a direction opposite of that needed to expand tensioning device  10  is provided to threaded rod  60  via the boring apparatus. Such opposite rotation of threaded rod  60  results in second bearing portion  66  of threaded rod  60  operably bearing against second bearing surface  48  of wedge portion  42 . Therefore, second bearing portion  66  pushes against second bearing surface  48  of wedge portion  42  to thereby axially move wedge portion  42  away from bracing portion  22 . In such a manner, tensioning portion  34  is moved radially inwardly due to the corresponding engaged inclined surfaces between tensioning means  34  and wedge portion  42 . 
     When in a contracted configuration, tensioning device  10  may be moved axially within the constructed pipe by the control rod. Therefore, tensioning device  10  may be selectively moved to the next pipe section seam to assist in holding the respective pipe sections to one another during insertion through the underground channel. 
     A torque of up to 50 ft-lbs. may be required of the rotation generation system to enable tensioning device  10  to develop up to 70,000 pounds of expansion force. In addition, forces up to 200 pounds may be required to insert the assembled pipe into and through the underground channel. A substantial portion of this needed force may impinge upon the seams between respective pipe sections  12 ,  14 , as a result of friction or impediments in the pipe insertion path. To prevent separation of respective adjacent pipe sections, tensioning device  10  may preferably be utilized. 
     Though a wide variety of pipe sizes and tensioning device dimensions are contemplated by the present invention, it is particularly preferred for use in pipe applications having inside diameters of greater than 4 inches. Though the present invention may be used in applications of smaller dimensions, it is particularly useful for larger applications, where forces resistant to pipe insertion into the underground channel are substantially increased. A particular application contemplated for the present invention is in the insertion of 15 inch ID sewer pipe in 10 foot long sections. Such pipe is preferably polymeric in nature, and most preferably polyvinyl chloride (PVC). PVC pipe material is preferred for its strong and durable physical characteristics, whereby cracking or breakage or the pipe due to expansion forces generated by tensioning device  10  of the present invention are minimized. Any typically used underground pipe material may also be used in conjunction with the tensioning device of the present invention. It is contemplated that tensioning device  10  is widely applicable, and can be used wherever expansion within a pipe is desired. 
     Preferably, the components comprising the present invention are fabricated from relatively strong and durable materials such as steel or the like. Though metal materials are particularly preferred for the applications described herein, a variety of other materials may be utilized instead. 
     The invention has been described herein in considerable detail in order to comply with the Patent Statutes, and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the invention as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.