Abstract:
A method for constructing a power tong jaw, including the steps of: (1) providing a substantially flat upper plate and a substantially flat lower plate; (2) providing at least two separately formed substantially elongated column members, at least one of the column members having a die insert groove formed therein; and (3) connecting the upper plate to the lower plate using the column members.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   None. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   None. 
   REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON COMPACT DISC 
   None. 
   BACKGROUND OF THE INVENTION 
   A. Field of Invention 
   The present invention relates to pipe tongs or power tongs used in the oil and gas industry to make-up and break-out sections of drill pipe and other tubular members having threaded connections. More particularly, the present invention relates to a jaw for use in such tongs and a method for constructing the jaw. 
   B. Description of Related Art 
   Power tongs are often employed in the oil and gas industry to break-out or make-up threaded connections on tubular members (such as drill pipe, tubing, or casing). It is generally required that one tong grip and rotate one section of a tubular string and a second tong grip and hold stationary the other section of the tubular string. The first tong rotating the first tubular member is typically referred to as the power tong, while the second tong holding the second tubular member stationary is typically referred to as the back-up tong. Examples of conventional power tongs can be seen in references such as U.S. Pat. Nos. 5,671,961, 5,702,139, and 5,819,604 to Buck, which are incorporated herein by reference. 
   Power tongs ordinarily have two or more jaws which are actuated to grip and release the tubular member. The actual contact with the tubular is typically accomplished through the use of die inserts which are removably positioned in the power tong jaws. Die inserts are commonly held in place through a dovetail key arrangement or other groove and spline configurations as seen in U.S. Pat. No. 4,576,067 to Buck, which is incorporated herein by reference, and the patents cited therein. 
   Power tong jaws are commonly machined from solid pieces of metal bar stock, or semi-finished casting or from ring forgings which are rolled to near final dimensions and then machined to final dimensions. An example of jaws  1  constructed in this manner is seen in  FIG. 1 . It can be seen that the jaw  1  includes a jaw body  4  with dovetail slots  3  formed therein. The rear portion of the jaw body  4  includes a jaw roller  5  secured to the jaw body  4  by a roller pin  6 . A number of machine hours on lathes, mills, and saws are required to construct these jaws  1  from the preliminary material. A portion of these hours are spent forming the complex dovetail slot  3  in the jaw  1 , which dovetail slot  3  receives the die insert  2 . The process of forming jaws from solid material in this manner is costly and time consuming. 
   Jaws are often formed from multiple pieces for applications where the weight of a completely solid jaw might be excessive. An example of such jaws  106  is seen in  FIG. 2 . Lower and upper plates  100  and  102  are cut, e.g., using a laser, waterjet, or torch. Afterward, the plates  100  and  102  must be machined or milled before they are connected to a jaw mid-section  101  using bolts  105 . Like the solid jaws  1  discussed above, the jaw mid-section  101  is cut from metal bar stock or ring forging and machined. Although the jaw mid-section  101  is smaller in diameter than the solid jaw  1  (and, therefore, involves less material), like the solid jaw  1 , the jaw mid-section  101  contains dovetail slots  104  for receiving die inserts  103 . As noted above, substantial machine work is required to form these dovetail slots  104 . Thus, the process of constructing jaws in this manner is less expensive than constructing jaws out of solid material, but this manner of constructing jaws is still costly—primarily because of the machine work that must be done on the jaw mid-section  101 , especially the complex machine work required to form the dovetail slots  104 . What is needed in the art is a power tong jaw design which may be manufactured less expensively, from less preliminary material, and requires less machine work. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides a jaw for use in power tongs and a method for constructing the jaw. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is an exploded view of a prior art power tong jaw constructed from solid metal.  FIG. 1(   a ) shows a right jaw, and  FIG. 1(   b ) shows a left jaw. 
       FIG. 2  is an exploded view of a prior art power tong jaw constructed from multiple pieces  FIG. 2(   a ) shows a right jaw, and  FIG. 2(   b ) shows a left jaw. 
       FIG. 3  is an exploded view of a power tong jaw constructed using the method of the present invention. 
       FIG. 4  is a close-up view of a column member having a die insert groove formed therein. 
       FIG. 5  is an assembled view of a power tong jaw constructed using the method of the present invention. 
       FIG. 6  is an exploded view of a power tong jaw member constructed using the method of the present invention. 
       FIG. 7  is an assembled view of a power tong jaw member constructed using the method of the present invention. 
       FIG. 8  is a perspective view of a back-up power tong incorporating a jaw member of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The following detailed description refers to the accompanying figures. 
   The term “power tong” as used herein refers to both power tongs for rotating tubular members and back-up power tongs for holding tubular members stationary against rotation. 
   In a preferred embodiment, the invention provides a pivoting power tong jaw as seen in  FIGS. 3 and 5 . The jaw  205  comprises an upper plate  200 , a lower plate  201 , and three column members  203 . The upper plate  200  and lower plate  201  are arranged horizontally, the former above the latter. The upper plate  200  and the lower plate  201  each contain two column member slots  206  and one column member opening  207 . In a preferred embodiment, the upper and lower plates will be formed by a high speed, precision cutting process. Examples of high speed precision cutting processes would include laser cutting or water jet cutting, shear or punch press types of heavy metal fabrication techniques, and may include plasma torch cutting. Plasma torch cutting and flame torch cutting would generally not be considered precision cutting processes, and conventional milling would not be considered high speed, although these methods could be used in less preferred embodiments for producing the plates, as could casting processes. As illustrated in  FIGS. 3 and 5 , each of the column members  203  is positioned vertically. Two of the column members  203   a  have die insert grooves  204  formed in them for receiving dies. (A close-up view of a column member  203   a  is depicted in  FIG. 4 , which clearly shows the die insert groove  204 .) As seen in  FIGS. 3 and 5 , the two column members  203   a  having the die insert grooves  204  are positioned between the upper plate  200  and lower plate  201  such that each end of each of these column members  203   a  fits into a corresponding column member slot  206 . The column members  203  are welded into place, or secured by another common method (e.g., using bolts or screws). The third column member  203   b  is also positioned between the upper plate  200  and the lower plate  201 . This column member  203   b  does not have a die insert groove  204  and has points  208  at each end which extend through the column member openings  207  in the upper plate  200  and lower plate  201 , thereby stabilizing the column member  203   b.    
   As seen in  FIGS. 3 and 5 , the jaw insert  101  (depicted in  FIG. 2 ) is not present in this embodiment of the present invention. Thus, this design greatly reduces the amount of material and machining required to produce the jaw. Additionally, the column members can be formed by a more economical method than machining, such as investment casting. Thus, a large number of identical column members could be produced for use in constructing the tong jaws of the present invention. Because the column members contain the complex detail required to retain the dovetail die inserts, the casting further reduces the amount of machining required to produce each tong jaw. Moreover, the same column members may be used on a variety of different jaw sizes (i.e., jaws designed to grip different diameter tubulars). To produce different sized jaws, it is only necessary to modify the top and bottom plates. Thus, one benefit of this design is that a jaw for an usual diameter tubular may be manufactured very quickly by cutting the correct size top and bottom plates and assembling them with pre-manufactured column members, which would be the same size regardless of the top and bottom plate dimensions. This method can reduce the time necessary to produce a nonstandard sized jaw from days to hours. This method is also far more economical than prior art methods, allowing jaws of the present invention to be produced at approximately 77% of the material and production cost of prior art jaws. 
   In another embodiment, the invention provides a power tong jaw member as seen in  FIGS. 6 and 7 . The jaw member  301  comprises an upper plate  304 , a lower plate  305 , and four column members  302 . The upper plate  304  and lower plate  305  are arranged horizontally, the former above the latter. The upper plate  304  and lower plate  305  contain column member slots  306 . The column members  302  are connected to the upper plate  304  and lower plate  305  at the column member slots  306 . Two of the column members  302   a  have die insert grooves  303  for retaining die inserts  307 . As illustrated in  FIG. 7 , the column members  302   a  having die insert grooves  303  are positioned such that the die inserts  307  face inwardly in an arcuate orientation corresponding to the curvature of the particular diameter tubular being gripped, thereby allowing both of the die inserts  307  to come into contact with the surface of a tubular when the power tong jaw member  301  is in use. The column members  302   b  which do not have die insert grooves  303  are positioned parallel to each other on opposite sides of the upper plate  304  and lower plate  305 . 
   The power tong jaw member seen in  FIGS. 6 and 7  could be used in a sliding jaw adaptor for pivoting jaw power tongs as seen in U.S. patent application Ser. No. 10/139,053, which is incorporated by reference herein. The jaw members of the present invention could replace the sliding solid jaw members seen therein. 
   This embodiment of the present invention could also be used to replace the solid arcuate jaw members found in back-up power tongs known in the art, for example, the back-up power tongs shown in U.S. Pat. No. 5,702,139 to Buck, which is incorporated herein by reference in its entirety. A back-up power tong design incorporating power tong jaw members according to the present invention is illustrated in  FIG. 8 .  FIG. 8  shows a back-up power tong  402  a having power tong jaw member  401  mounted on an outside jaw assembly  404  and an inside jaw assembly  403 . As shown in  FIG. 8 , this jaw member is similar to that seen in  FIGS. 6 and 7 , however, there are no column members on the side of this embodiment of the jaw member. As discussed in U.S. Pat. No. 5,702,139 to Buck, when actuated, the outside jaw assembly  404  and inside jaw assembly  403  of the back-up power tong shown in  FIG. 8  lock together around a tubular (not shown). A cylinder assembly  405  having an arcuate jaw member  407  is extended toward the jaw members  401  so that the arcuate jaw member  407  engages the tubular. The contact between the arcuate jaw member  407  and the tubular brings the tubular into contact with the die inserts  406  on the jaw members  401 , which, in cooperation with the arcuate jaw member  407 , grip the tubular. A polyurethane cylindrical spring  408  is used to hold the jaw member  407  in the proper position for the initial bite, but allows the jaw member  407  to move to accommodate undersized tubulars or to compensate when subjected to high torques. While only one spring  408  is shown in contact with each of the jaw members  401  in  FIG. 8 , it will be understood a second spring  408  is located on the other side of jaw  401 , but is hidden from view. The springs  408  are composed of relatively rigid elastic material and are secured by being positioned between the jaw member  401  and bolts  500  (or bolts  501  for the spring hidden from view). The springs  408  could be secured by other means known in the art, e.g., it could be secured by pins running through the jaw assembly and the spring. While the pivoting jaw embodiment of the present invention offers the greatest cost savings, the sliding jaw adapter embodiment and the back-up power tong embodiment also offer significant savings over earlier power tong jaw designs known in the art. 
   While many parts of the present invention have been described in terms of specific embodiments, it is anticipated that still further alterations and modifications thereof will no doubt become apparent to those skilled in the art. For example, other designs besides a dovetail slot might be used to retain die inserts, or the number of column members having die insert grooves could be altered. Other embodiments are possible and modifications may be made to the embodiments without departing from the spirit and scope of the invention. The preceding detailed description is not meant to limit the invention. Rather, the scope of the invention is defined by the appended claims. It is therefore intended that the following claims be interpreted as covering all such alterations and modifications as fall within the true spirit and scope of the invention.