Abstract:
Disclosed is an adjustable locator for a machining lathe for machining a pipe or similar work piece. The locator includes a locator pad having a main body and a shoulder which is inserted into a socket in the stationary member of the machining lathe. The locator pad also includes an extension plate which can be both axially displaced or adjusted relative to the main body and shoulder to thereby position the clamshell lathe relative to the workpiece.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to a split frame clamshell machining lathe for cutting and finishing relatively large diameter pipes, and more particularly to adjustable locators for aligning the large diameter pipes in the clamshell lathe. 
     II. Discussion of the Prior Art 
     Split frame clamshell lathes of the type described herein are known in the art. U.S. Pat. Nos. 4,739,685; 4,939,964; 5,549,024; and 6,619,164 are illustrative of the technology involved. The teachings of these patents are hereby incorporated by reference. As described therein, a clamshell machining lathe generally comprises a first and a second semi-circular segment that are designed to be joined together to form an annular assembly for encircling a shaft or pipe to be machined. The assembly also generally includes a stationary ring, and a rotatable ring supported by bearings affixed to the stationary ring. The rotatable ring includes a spur gear on its outer peripheral surface and is journaled to the stationary ring for rotation about a concentrically disposed pipe or work piece. A motor is attached to the stationary assembly and includes a drive gear designed to mesh with the spur gear on the rotatable segment of the pipe lathe. A tool block for supporting a cutting tool is mounted to the rotatable segment and is designed such that a cutting tool is advanced in small incremental steps in a radial direction against the pipe to be machined upon each orbit of the ring gear about the work piece. 
     A problem has heretofore existed in the prior art when the diameter of the work piece does not exactly correspond with the diameter of the clamshell housing. If there are no locators mounted to the inner circumference of the stationary member of the clamshell lathe, then the cutting may be uneven. To solve this problem, standard locators were inserted into pockets machined into the housing of the stationary member. The standard locators were then axially adjusted manually to accommodate different sized work pieces and to precisely center the clamshell lathe on the work piece. This type of adjustment was somewhat uncontrolled and tended to be inaccurate. Placing the prior art locators in an ideal position both axially and radially is a time-consuming endeavor. 
     While the prior art locators prove marginally acceptable for clamshell lathes to be used with piping or shafts up to five feet in diameter, when a clamshell lathe is built to machine work pieces whose diameters may be ten feet or greater, it becomes increasingly difficult to set up the machine because of the overall weight thereof. While the standard, prior art locators can be used to effect radial positioning so that the clamshell lathe annulus is concentric with the work piece to be machined, axial positioning becomes increasingly difficult. In the past, a brute force approach has been used where workmen axially position the clamshell lathe on the work piece using a sledgehammer to beat the clamshell to a desired axial position. 
     It is the purpose of the present invention to simplify the alignment of the locators and therefore the clamshell lathe by providing an adjustable locator which can be adjusted in both the axial and the radial direction. It is a further object of this invention to reduce the setup time required for mounting a clamshell lathe in a pipe or shaft to be machined and to reduce the amount of physical work involved. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a device to be used in combination with a clamshell lathe for centering and aligning the clamshell lathe with a work piece to be machined. The device itself comprises a body member that is adapted to be positioned in a pocket formed in the stationary member of a clamshell lathe where the body member at least partially extends outward from an inner diameter of the stationary member. A set screw is rotatably coupled to the body member and has external threads thereon for cooperating with a threaded bore in the stationary member leading to the pocket whereby rotation of the set screw displaces the body member relative to the pocket in a radial direction. Slidingly secured to a base of the body member is an extension plate. The extension plate has a threaded nut affixed to it and a rotatable adjustment screw mounted for rotation in the body member cooperates with the threaded nut for axially translating the body member (therefore the clamshell lathe) relative to the extension plate. 
     A plurality of these adjustable locators are interleaved with conventional standard locators around the inner diameter of the clamshell lathe annular stationary member and by proper manipulation of the radial adjustment provided by the standard locators and the axial adjustment provided by the adjustable locators of the present invention, the clamshell lathe can be “walked” in the axial direction along the pipe using wrenches to turn the adjustment screws, thereby obviating the need to beat on the clamshell lathe annulus with a sledgehammer. 
     For a better understanding of this invention, and the advantages obtained in its use, reference should be made to the drawings and the accompanying descriptive material, in which there is illustrated and described a preferred embodiment of the invention. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in several views refer to the corresponding parts: 
         FIG. 1  illustrates a partial perspective view of a segment of the clamshell lathe with both an adjustable locator of the present invention and a standard locator affixed thereto; and 
         FIG. 2  shows an exploded perspective view of the adjustable locator of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the perspective view of  FIG. 1  and the exploded view of  FIG. 2 , the adjustable locator  10  includes a body member  12  having a rectangular block member  14  and a cylindrical pedestal  16 . The body member  12  has a top surface  15 , four mutually perpendicular sides  17 , and an open bottom. The cylindrical pedestal  16  projects from the top surface  15 . V-shaped gibs  28  are located on an inner surface of opposed sides of the body member. 
     The body member  12  is adapted to be positioned in a pocket formed in the stationary member  18  of the clamshell housing. The body member  12  at least partially extends outward from an inner diameter of the stationary member. 
     An extension plate  20  is slidingly coupled to the body member  14  of the locator pad  12  is extension  20 . Extension plate  20  has a bottom surface  22  and a top surface with a nut  24  welded to it. 
     The adjustable locator  10  has a means for axial adjustment. This means for axial adjustment includes the nut  24  which has a threaded bore  26  extending longitudinally through the it. The nut  24  includes a V-shaped projections  27  on opposed side surfaces thereof. The V-shaped projections  27  extend parallel to the threaded bore  26 , and are adapted to fit in the V-shaped gibs  28  in the body member  14 . A rotatable adjustment screw  30  is also provided. The rotatable adjustment screw  30  has a first end  32 , a flange element  34  and a threaded portion  38 . The threaded portion  38  is coupled to threaded bore  26  of nut  24  and rotation of the rotatable adjustment screw  30  axially translates the body member  14  relative to the extension plate  20 . 
     A bracket  40  captures the annular flange portion  34  of rotatable adjustment screw  30 . The head  32  of the rotatable adjustment screw  30  extends through inverted u-shaped cavity  42 . The bracket  40  is secured in the body member  14  by inserting it into a cavity in the side wall and is secured by set screw  44   a  and  44   b  which pass through apertures  46  in the body member  14  and into threaded aperture  44  in the bracket  40 . Further, socket head set screws  52  pass through front apertures  50  in the bracket  40  into threaded bores in the ends of the V-shaped gibs  28 . 
     The adjustable locator  10  also has a means for radially adjusting the body member  12  relative to a workpiece on which the too is being used. This includes a set screw  54  having a first end  56  and a second end  58 , the second end being rotatably coupled to the body member  12  at the cylindrical pedestal  16 . The set screw  54  has external threads which cooperate with a threaded bore in the stationary member  18  leading to the pocket whereby rotation of the set screw  54  displaces the body member  12  radially within the pocket. The cylindrical pedestal  16  includes a longitudinal bore  68  for receiving a shoulder bolt  60  having a first end  62  and a second end  64 . The second end  58  of the set screw  54  has a concentric threaded bore and is adapted to receive the second end  64  of shoulder bolt  60 . The second end  64  passes through bore  68  in the pedestal  16  to be received by the second end  58  of the set screw  54 . As previously described, because cylindrical pedestal  16  is inserted into a pocket in the stationary member  18  set screw  54  is also disposed in an internally threaded socket. Thus, when the body member  12  needs to be radially adjusted an Allen wrench is inserted into first end  56  of the set screw  54  which is now disposed in the socket and rotated. This rotation displaces the body member  12  radially relative to the pocket. 
     Thus, now the locator can be easily adjusted either radially or axially to properly align the lathes cutting tool with the surface of a work piece to be machined. To axially adjust the locator the first hex end  32  of rotatable adjustment screw  30  is rotated by a suitable wrench to move the stationary member  18  axially relative to the work piece on which the extension plate  22  rests. As previously described, in order to radially adjust the body member  12 , an Allen wrench is applied to the first end  56  of the set screw  54  which rotates locator set screw  54 , displacing to the adjustable locator  10  relative to the clamshell lathe on which it is mounted. 
     In use, a plurality of the adjustable locators described herein are interleaved with standard, non-axially displacable locators around the inside diameter of the clamshell lathe assembly. If on initial installation, the plane of the clamshell lathe is not perfectly perpendicular to the center line of the work piece, various ones of the axially adjustable locator members can be actuated by applying a suitable wrench to the hex end  32  of the adjustment screw  30  and turning the screw in a direction to translate a predetermined arc of the clamshell lathe so that it is no longer inclined relative to the center axis of the work piece. 
     Further, by appropriately manipulating the radial adjustment screws on the several locators, the extension plates  20  of the adjustable locators  10  can be lifted from the surface of the workpiece, allowing the extension plates to be cranked back to a start position before again being lowered onto the workpiece through radial adjustment of the standard locators. In this fashion, the clamshell lathe can be displaced further in the axial direction. Repeating the foregoing steps results in the ability to “walk” the clamshell lathe through several inches in the axial direction if necessary to obtain a desired purchase between the cutting tool of the clamshell lathe and the surface of the workpiece to be machined. 
     Even though numerous characteristics and advantages of the invention have been set forth in the foregoing description, together with the details of the structure and the function of the invention, the disclosure is illustrative only, and changes can be made in detail, especially in areas of shape, size and arrangements of parts, within the principles of the invention, to the full extent indicated by the broad, general meaning of the appended claims.