Abstract:
The intermediate support brace is used to prevent bending or deflecting of a cylindrical work piece being machined by a journal turning lathe. A U-shaped frame is mounted to the journal turning lathe, and secured to the journal turning lathe by a first and second clamping means which secure the intermediate support brace to the guide rails of the journal turning lathe. A generally circular opening in the frame surrounds the cylindrical work piece, and the work piece is centered by a series of jacks. The clamshell lathe assembly is translated from a first end bracket to the intermediate support bracket. The clamshell lathe is then stopped; the intermediate support bracket is released and mounted downstream from the clamshell lathe assembly. The clamshell lathe assembly is then restarted and translated to a second end bracket.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a portable machining lathe, and in particular to a mechanism for preventing deflection of the guide rails of a journal turning lathe used for cutting and finishing relatively long spans of large diameter pipes. 
     2. Description of the Related Art 
     Split frame journal turning lathes of the type described herein are known in the art. The journal turning lathe generally comprises first and second end brackets which are concentrically mounted on a cylindrical work piece at a predetermined axial spacing. A plurality of guide rails extend between the first and second end brackets in parallel relations to the cylindrical work piece. The journal turning lathe assembly further has a relatively heavy clamshell lathe assembly having a first and second semicircular segments that are designed to be joined together to form an annular assembly for encircling a shaft or pipe to be machined. The assembly includes a stationary ring, and a rotatable ring abutting the stationary ring. The rotatable ring is made of steel and on its peripheral surface and is journaled to the stationary portion for rotation about a concentrically disposed pipe or shaft to be machined. 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. Also, a heavy tool block for supporting a cutting tool is mounted on the rotatable segment. The cutting tool is adapted to be advanced in 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 that the guide rails carrying the clamshell assembly may bend or deflect under the weight of the clamshell lathe assembly as the midpoint of the guide rails is approached. As the journal turning lathe progresses to the center of the cylindrical work piece, the weight of the lathe assembly causes the supporting structure to sag at the center. This sagging, in turn, results in uneven machining of the work piece. It is the purpose of this invention to remedy this problem. 
     SUMMARY OF THE INVENTION 
     The present invention comprises an intermediate support brace for a journal turning lathe for supporting the guide rails and cylindrical work piece. The support brace includes a somewhat U-shaped frame, and a first and second clamping member. The U-shaped frame has a series of semi-circular notches cut into the surface of the frame along the thickness dimension thereof. The U-shaped frame is lifted onto the journal turning lathe, and the guide rails of the lathe are received in the concaved notches in the U-shaped frame. The clamping members each have a pair of corresponding inverted semicircular notches which are placed over the top half of each guide rail. The concaved notches of the frame cooperate with the inverted notches of the clamping members to encircle and trap the guide rails. The frame and first clamping member have a series of regularly spaced threaded apertures which locator members pass through to center the pipe in the frame. 
     The primary advantage of the present invention is that it provides support for the guide rails preventing any appreciable sag thereof due to the weight of the clamshell assembly of the journal turning lathe that are suspended on the guide rails. 
     Another feature of the present invention is that it is relatively easy to affix to and remove the support brace from the journal turning lathe to allow the clamshell assembly to traverse the entire length of the work piece being machined. 
     An additional advantage of the present invention is that it is portable and can be taken to a variety of job sites along with the journal turning lathe. 
     For a better understanding of the invention, and of 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 accompanying drawings in which like numerals in the several view refer to corresponding parts: 
     FIG. 1 is a perspective view of the present invention mounted on a journal turning lathe; 
     FIG. 2 illustrates a perspective view of the support brace in accordance with the present invention; 
     FIG. 3 is a perspective view of the U-shaped frame portion of the assembly in FIG. 1; 
     FIG. 4 is a perspective view of the first clamping member; 
     FIG. 5 is a perspective view of the second clamping member; and 
     FIG. 6 is a perspective view of the locator member for centering the work piece; 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a journal turning lathe  1  mounted on a shaft  2  whose exterior is to be machined. Journal turning lathe  1  includes end brackets  3  and  4  and a plurality of guide rails as at  5 ,  6 ,  7  and  9  extending between the end brackets and the parallel cylindrical work piece  2 . A clamshell lathe  8  of the type described in the Ricci U.S. Pat. No. 5,549,024, which is hereby incorporated by reference, is supported by the elongated guide rails and is arranged to be axially driven there along by a motor driven lead screw LS. A second motor  11  is mounted on the stationary segment of the clamshell and drives the movable gear ring of the clamshell that carries a tool slide that holds a tool bit. 
     The present invention comprises an intermediate supporting brace for use with a conventional, prior art journal turning lathe. Referring to the perspective views in FIGS. 2 and 3, the supporting brace is indicated generally by numeral  10  and comprises a generally U-shaped frame  12  with a front wall  13   a  and a back wall  13   b , a first clamping member  14 , and a second clamping member  16 . The generally U-shaped frame  12  has a base segment  18  and a pair of arms  20  and  22 . On the first top edge surface  24  of the first arm segment  20  is a first concaved semi-circular notch  26  adapted to receive a lower half of a first cylindrical guide rail  5 . The first concaved notch  26  is defined by the elevation of the top edge surface  24  and extends from the front wall  13   a  to the back wall  13   b  of the U-shaped frame  12 . A first shoulder  28  is formed along the inside of the first arm segment  20  adjacent to the first concaved notch  26 . 
     A corresponding structure is found on the top edge surface  30  of the second arm segment  22 . A second concaved notch  32  is defined by the elevation of the second top edge surface  30 . A second shoulder  34  is formed along the inside of the surface of the second arm segment  22  adjacent to the second concaved notch  32 . The second concaved notch  32  is adapted to receive the lower half of a second guide rail  6  and is generally semi-circular in shape. 
     The first and second guide rails  5  and  6  are captured on the arms of the supporting brace  10  by applying the first or upper clamping device  14  atop the brace to span the first and second arm segments  20 ,  22 . The first clamping member  14  is shown in FIG.  4 . It has a first and second end portion  36  and  38 . Between the first and second ends  36 ,  38  is a rounded arch segment  40  which is integral with the first and second end  36 ,  38 . The first clamping member  14  has a front wall  41   a  and a back wall  41   b . The bottom surface  42  has a first inverted semi-circular notch  44  formed inward thereof. Likewise, the bottom surface  46  of the second end  38  includes a second inverted semi-circular notch  48 . Adjacent the bottom surfaces  42  and  46  is a flat  50  which supports the arch  40 . 
     When the first clamping member  14  is placed on the U-shaped frame  12 , the flats  50  rest upon the shoulder  28  and  34  of the first and second arm segment  20 ,  22 . Thus, the first concaved notch  26  cooperates with the first inverted notch  44  to form a cylindrical bore or aperture  52 . The second concaved notch  32  cooperates with the second inverted notch  48  to form a circular aperture  54 . Aperture  52  encircles and captures a first guide rail  5  and aperture  54  encircles and captures a second guide rail  6 . The first clamping member  14  combines with the U-shaped frame  12  to form a central opening for receiving a cylindrical work piece therethrough. 
     The base segment  18  of the generally U-shaped frame  12  has a third concaved semicircular notch  56  in its inside surface  58  adjacent to the first arm segment  20 . The third concaved notch  56  is defined by the elevation of the first arm segment  20  and the inside surface  58 . The third concaved notch  56  is adapted to receive a third guide rail  9  (FIG.  1 ). The third concaved notch  56  extends from the front wall  13   a  to the back wall  13   b  of the U-shaped frame  12 . A fourth concaved notch  60  is disposed on the base segment  18  and is defined by the elevation of the inside surface  58  and the second arm segment  22 . The fourth concaved semi-circular notch is  60  is adapted to receive a fourth guide rail  7 . (FIG.  1 ). The fourth concaved notch  60  extends from the front wall  13   a  to the back wall  13   b  of the U-shaped frame  12 . A fifth concaved notch  62  is defined by the elevation of the inside surface  58  between the third concaved notch  56  and the fourth concaved notch  60 . The fifth concaved notch  62  is generally semicircular in shape and extends from the front wall  13   a  to the back wall  13   b  of the U-shaped frame. 
     Third and fourth guide rails of the journal turning lathe  1  are received by the third concaved notch  56  and the fourth concaved notch  60 , respectively. The threaded drive screw shaft LS of the journal turning lathe  1  extends loosely through the fifth concaved notch  62 . The third and fourth guide rails  7  and  9  are clamped in the U-shaped frame  12  by the second clamping member  16  when the two are bolted together. 
     The second clamping member  16  (FIG. 5) extends lengthwise from the inside wall  64  (FIG. 3) of the first arm segment  20  and the inside wall  66  of the second arm segment  22 . As shown in FIG. 2, the second clamping member  16  has a first end  68  adjacent to inside wall  64  and a second end  70  adjacent to inside wall  66 . The second clamping member  16  further has a planar bottom surface  72 , a front wall  73   a  and back wall  73   b . A generally semicircular third inverted notch  74  is formed in the bottom surface  72  near the first end  68 . Likewise, a generally semi-circular fourth inverted notch  76  is formed in the bottom surface  72  near the second end  70 . Finally, a smaller inverted notch  78  is disposed midway between the third inverted notch  74  and the fourth inverted notch  76 . 
     As seen in FIG. 2, when the second clamping member  16  is placed on the base of the U-shaped frame  12 , the third inverted notch  74  cooperates with third concaved notch  56  to form circular bore  80  to encircle and capture the third guide rail  9  of the journal turning lathe  1 . Likewise, fourth inverted notch  76  cooperates with the fourth concaved notch  60  to form a bore  82  to encircle and capture the guide rail  7 . Finally, the drive shaft of the journal turning lathe is allowed to rotate in the bore created by the fifth concaved notch  62  in the frame base  12  and the fifth inverted notch  78 . 
     The first clamping member  14  is secured to the upper ends of the U-shaped frame  12  by a first series of fasteners  84 . The second clamping member  16  is secured to the to the base of the U-shaped frame  12  by a second series of fasteners  86 . 
     The combination of the U-shaped frame  12  and the rounded arch  40  of the first clamping members  14  creates a central opening  88  (FIG. 1) adapted to receive the work piece to be machined. A plurality of jack pads  90  (FIGS. 1 and 6) are used to center the work piece in the supporting brace  10 . The threaded shanks of jack pads  90  extend through a pair of threaded sidewall apertures  92  in the first and second arm segments  20 ,  22  of the U-shaped frame  12 , and through a pair of threaded apertures  94  in the top of the first clamping member  14 . 
     In use, the journal turning lathe  10  is first mounted on the work piece to be machined as shown in FIG.  1 . The split clamshell lathe is positioned about the work piece adjacent to an end bracket  3  or  4 . The support brace  12  is then releasably secured to the guide rails of the journal turning lathe at a predetermined location along the guide rails, preferably about half way between the two end brackets. The tool holder on the rotatable ring gear of the clamshell lathe is made to orbit the work piece as the clamshell is translated from a first position, adjacent to the first end bracket of the journal turning lathe, to a second position closely adjacent to the mounting brace  10 . The clamshell lathe is then momentarily stopped, while the mounting brace  10  is removed from the journal turning lathe and repositioned on the journal turning lathe upstream of the clamshell lathe assembly. The clamshell lathe is then restarted and made to translate from the location proximate the mounting brace  10  to the second end bracket of the journal turning lathe. The process can be repeated on the return travel of the clamshell and on all subsequent passes. 
     Because of the presence of the mounting brace  10  operatively disposed between the work piece  2  and the plurality of journal turning lathe guide rails, the rails do not deflect under the weight of the clamshell assembly, resulting in a more perfect machining operation. In practice, the use of the movable brace  10  has permitted a shaft 8 feet long to be turned over its entire length while maintaining a tolerance of 0.004 inch. Even though numerous characteristics and advantages of the invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes can be made in detail, specially in areas of shape, size, and arrangement of parts, within the principles of the invention, to the full extent indicated by the broad, general meaning of the appended claims.