Abstract:
A machine tool for re-surfacing gasket seats surrounding elliptical openings in oval manways includes a housing of an oval configuration that is adapted to be mounted in the opening of the manway to be machined. A motor and a tool slide assembly are secured to the motor mount in such a fashion that the tool slide assembly is confined to travel in an oval orbit along a second major surface of the housing. A cam actuated feed screw is appropriately disposed to engage a tripper bar disposed in the path of travel to effect radial displacement of a tool holder and tool bit. A cam locking and unlocking control lever cooperates with the cam and is disposed such that an operator located outside of the vessel on which the manway is disposed can readily control the machining operation.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    I. Field of the Invention  
           [0002]    This invention relates generally to portable machining lathes, and more particularly to a machine for re-facing worn, corroded, pitted and leaking gasket seat surfaces of oval manways commonly found on pressurized industrial vessels such as tanks, steamlines, pipelines, etc.  
           [0003]    II. Discussion of the Prior Art  
           [0004]    Industrial facilities, such as power generating plants, petroleum processing plants and other like facilities have high pressure tanks and pipelines that commonly incorporate sealed entrance ports called manways. Maintenance personnel can use the manways to gain access to the interior of the vessel.  
           [0005]    In many instances, these access ports have an oval or elliptical profile. With time, the gasket seat surface between the manway and the vessel may become pitted, corroded and worn to the point where leaks develop. When this happens, it becomes necessary to reface the gasket seat area. To minimize the downtime of the industrial production, it is imperative that the re-facing be accomplished in situ.  
           [0006]    One approach for re-facing oval manways in the past has been to use a grinder such as the Oval Manway Seat Grinder commercially available from the D. L. Ricci Corp., the assignee of the present application. This grinder produces a very smooth, fine finish on the manway seat area. However, in some applications, such a smooth surface is disadvantageous. More particularly, in high pressure applications, the gasket used between the manway and the vessel can be extruded radially outwardly due to the high pressures encountered. It is, therefore, desirable in such high pressure applications that the re-surfacing of the gasket seat area result in a slightly ridged surface resembling the somewhat concentric grooves of a phonograph record. This roughened surface has been found to inhibit gasket extrusion even under very high pressures developed within the vessel in question.  
           [0007]    It is unduly heavy, making it difficult to set up from a location outside of the vessel. Also, the opening of the oval manway is substantially occluded, making adjustments from outside of the vessel and observation of the surface being machined difficult to do.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides an improved machine for re-surfacing the face of an oval manway gasket seat. It includes a housing having first and second oval-shaped major surfaces having an oval-shaped central opening that is formed through the thickness dimension of the housing. The housing is designed to fit within and be supported by an oval manway to be machined. It has a first track member affixed to the first major surface in surrounding relation to the oval-shaped central opening. Likewise, a second track member is disposed on the second major surface, also in surrounding relation to the central opening. A drive means supported by the housing and cooperating with the first track member causes the drive means to orbit the oval-shaped central opening when the drive means is energized. The drive means carries a bracket member having an arm that extends through the oval-shaped central opening. The arm pivotally supports a link member that is operatively coupled to the second track member and that link member carries a machine tool slide assembly in an orbital path defined by the second track member. The machine tool slide assembly supports a cutting tool for engaging the face of the oval manway.  
           [0009]    The machine tool slide assembly comprises a cam actuated feed screw for incrementally translating the cutting tool in a radial direction as the machine tool slide assembly is carried in its orbital path.  
           [0010]    Because the central opening of the housing does not become blocked by the tool slide assembly and structure supporting it, an operator, from the outside, can reach through the central opening to make depth-of-cut adjustments and can selectively engage and disengage the cam actuated lead screw that controls the radial translation of the cutting tool. Moreover, because the oval manway is not appreciably blocked or occluded by the facer assembly, the surface being worked can be readily viewed. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0011]    The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several view is referred to corresponding parts.  
         [0012]    [0012]FIG. 1 is a perspective view of the oval manway facer when viewed from the outside of the manway in which the machine is to be installed;  
         [0013]    [0013]FIG. 2 is a perspective view of the oval manway facer when viewed from the inside of a oval manway; and  
         [0014]    [0014]FIG. 3 is an exploded perspective view of the oval manway facer comprising a preferred embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the device and associated parts thereof Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.  
         [0016]    Referring first to FIG. 1, there is indicated generally by numeral  10  the oval manway facer comprising a preferred embodiment of the present invention. It comprises a housing  12  having a first major surface  14  that is oval-shaped, having its minor access in a vertical direction and its major access in a horizontal direction. The housing  12  has a second major surface  16  best shown in FIG. 2. It too is oval in shape.  
         [0017]    Formed centrally through the housing  12  is an oval-shaped opening  18  and bolted to or otherwise affixed to the first major surface  14  in surrounding relation to the central oval opening  18  is an endless chain  20  whose individual links  22  are spaced by a predetermined pitch. In FIG. 1, the chain  20  is shown as being fastened by connectors  22  that are affixed by screws  24  to the outer wall of the housing comprising the first major surface  14 .  
         [0018]    A plurality of locator jack screws  26  fit into threaded bores formed at the opposed ends of the major and minor axis of the oval-shaped housing  12 . During setup, the screws are used to center the manway facer  10  within the oval opening of the manway to be machined. To further facilitate mounting of the oval manway facer machine  10  in the manway, there is provided a plurality of generally L-shaped locator legs, as at  28 , that fit into rectangular sockets  30  formed through the second major surface  16  of the housing  12 . These locator legs are designed to engage an edge surface of the manway opening to establish the depth of placement and to insure that the facing machine  10  is disposed squarely within the oval manway to be resurfaced.  
         [0019]    With continued reference to FIG. 1, there is shown a motor mount  32  having a face  34  to which a pneumatic, hydraulic or electric motor can be bolted and the shaft of the motor (not shown) passes through the central bore  36  and attached to it is a sprocket wheel having gear teeth whose pitch corresponds to the pitch of the chain  20 .  
         [0020]    The motor mount  32  carries a support arm  38  that extends through the central opening  18  of the housing  12 . As can be seen in the view of FIG. 2, affixed to the free end of the arm  38  carried by the motor mount  32  is a bearing pivot bracket  40 . Also visible in the view of FIG. 2 is a second oval track  42  formed on the second major surface  16  and that surrounds the central opening  18 . This track is preferably formed in the housing by milling first and second concentric grooves separated by a central ridge  44  therebetween. As will be explained in greater detail when the exploded view of FIG. 3 is described, the bearing pivot bracket  40  secured to the arm  38  carries a pair of Vee-grooved rollers that cooperate with the track  42  to effectively clamp the motor mount  32  with its arm  38  to the housing  12  while allowing the motor mount to orbit the first track defined by the endless chain  20  as the sprocket wheel on the motor&#39;s shaft is driven.  
         [0021]    With reference again to FIG. 2, pivotally mounted to the bearing pivot bracket  40  is a manway pivot link member  46 , the pivot axis being about a bolt on which the nut  48  is fastened.  
         [0022]    Affixed to the manway pivot link  46  is a tool slide assembly that includes a tool block  52  that is adapted to slide in the radial direction relative to a slide member  54 , which in turn, is pivotally secured to the manway pivot link  46 . As will be explained further herein below, a cam member  56  having a roller  58  thereon cooperates with the wall  59  defining the central opening  18  of the housing and operates to incrementally displace the tool block  52  carrying the cutting tool (not shown) in a radial direction each time the roller  58  engages a tripper pin  60  on wall  59  in the course of orbital travel of the roller.  
         [0023]    Referring again to FIG. 1, identified by numeral  62  is a manually actuable pull knob that is used to selectively engage and disengage the cam  56  to thereby allow or inhibit axial displacement of the tool block and cutting tool relative to the slide  54 . The way in which this is accomplished is described below.  
         [0024]    Now that the general construction of the oval manway facer machine of the present invention has been described, consideration will next be given to the details of implementation and, in this regard, reference will be made to the exploded perspective view of FIG. 3. Starting from the right in the drawing and proceeding towards the left, the motor mount  32  is illustrated as having a central, generally semi-circular opening  64  whose diameter accommodates the sprocket  66  which is keyed to the shaft of the drive motor (not shown). A cover plate  68  bolts to the motor mount  32  to enclose the sprocket wheel, except for a portion thereof that extends down below the confines of the motor mount  32  to engage the endless chain  20 . The arm  38  has one end  70  thereof fitted into a slot  72  of the motor mount  32  and fastened to it by bolts (not shown) passing through slots as at  74 .  
         [0025]    When the sprocket  66  is in engagement with the endless chain  20  the free end  76  of the arm  38  extends through the central opening  18  of the housing member  12  and is secured to the bearing pivot bracket  40  by bolts (not shown) passing through the bores  78  formed in the link  40 .  
         [0026]    Secured to the link  40  by a stationary bushing  80  and a rotatable bushing  82  are Vee bearings  84  and  86 , respectively. The bushing  82  is rotatable about a hex bolt  88  that threadingly fits into a threaded bore  90  formed in the bearing pivot bracket  40 . The spacing between Vee bearings  84  and  86  is such that they capture the track  44  therebetween.  
         [0027]    The manway pivot link  46  is pivotally secured to the bearing pivot bracket  40  using a bolt  92  that passes through a bore  94  formed in a cylindrical stub  96  that is a part of the bracket  40  and, thence, through a thrust washer  98 , a thrust bearing  100 , another thrust washer  102 , needle roller bearing  104 , a further thrust washer  106 , a thrust bearing  108  and thrust washer  110 . This assembly is held in place by a flat washer  112  and the nut  48 .  
         [0028]    The manway pivot link  46  has a generally triangular ear  114  extending from one end of its body and the ear has a threaded bore  116  for receiving a bolt (not shown) that is made to pass through a slide link bushing  118  that fits into a circular bore  120  formed through the manway facer slide  54 , which allows limited pivoting of the slide  54  relative to the pivot link  46 .  
         [0029]    Affixed to the back surface of the slide  54  is a pair of Vee bearings  122  and  124  that are journaled for rotation by a stationary bushing  126  and a rotatable bushing  128 , respectively. The stationary bushing  126  is held in place by a bolt  130  while the rotatable bushing is held by a bolt  132 . As with the bearings  84  and  86 , the bearings  122  and  124  also engage the track  44  therebetween to constrain the tool slide  54  as it is made to orbit the track as the drive motor drives the sprocket  66  along the chain  20 .  
         [0030]    The tool slide assembly  50  shown in FIG. 2 comprises the aforementioned tool slide  54  to which is slidingly affixed the tool block  52 . Specifically, the tool slide includes a dove-tail projection  134  adapted to fit into a dove-tail groove  136  formed in the tool block  52 . A gib  138 , also having a Vee groove, is adapted to mate with the dove-tail projection  140  when bolted to the inside of a flange  142  formed on the tool block. This arrangement allows the tool block  52  to move reciprocally relative to the slide block  54 . The reciprocal movement is imparted by means of a threaded feed screw  144  that passes through a threaded bore in a feed nut  146  that fits into an appropriately sized opening in the manway facer slide  54 .  
         [0031]    Rotation is imparted to the lead screw  144  through a Torrington clutch  148  that is captured in the bore  150  of the cam  56  between cam bushings  152  and  154 . The Torrington clutch functions as a one-way ratchet on the shaft of the feed screw  144 . The cam roller  58  screws into a threaded bore  156  of the cam  56 .  
         [0032]    Controlling the locked and unlocked state of the cam  56  is a control assembly, including a connector lock link  158  that is pinned to the cam lock  160  used to lock the cam  56 . When the cam  56  is locked, the feed screw  144  will not advance the tool in the block  52  radial direction. The other end of the connector lock link  158  is pinned to the push lock rod  162 , which slides in a cam top plate  164 . A compression spring  166  slides over the push lock rod  162 . The cam lock handle  62  slides over the other end of the push lock rod  162  and is held on by the lock nut  168 . Pulling the handle  62  and turning it a quarter turn compresses the spring  166  and holds the cam lock  160  away from the cam  56 . Turning the handle another quarter of a turn allows the spring  166  to push the cam lock  160  forward, which will lock the cam  56  the next time it is tripped by the tripper pin  60  disposed in the path of travel of the cam roller  58 .  
         [0033]    A tension spring  170  fits in the clevis end of the cam  56  and is held by a dowel pin  172 . Another dowel pin  174  goes through the loop on the other end of the spring  170 , the dowel pin  174  being captured between a cam keeper plate  176  and a cam top plate  178 . The clevis end of the cam lock  160  is pinned to the connector lock link  158 . The opposite end of the connector lock link  158  is pinned to the clevis end  180  of the push lock rod  162  by a dowel pin  182 . The spring  170  functions to pull the cam  56  back after it strikes and passes over the tripper pin  60 . The cam  56 , its clutch  148 , along with its bushings  152  and  154  as well as the manually operated cam lock lever assembly are captured between the cam feed bracket  176  and the cam top plate  164  when these two parts are bolted to each other a cotter pin  184  passes through a bore that extends transversely through the bottom of the lead screw  144 .  
         [0034]    The tool bit is adapted to be captured and held in the tool holder  186 . Part  186  has a key way  188  formed in the back surface thereof for receiving a ramp like protrusion on part  190 . The part  190  is secured in a cavity  192  of the tool block  52  by means of dowel pins  194  and  196  the ends of which pass through elongated slots in the tool holder  186  as well as through the elongated slots as at  198  on the tool block. A depth-of-cut adjustment screw  198  passes through a bore in the side face of the tool block  52  and into a threaded bore  200  of the ramp member  190 . The adjustment screw  198  is captured by a bushing  202  that is bolted to the side surface of the tool block  52 . When the hex nut end of the adjustment screw  198  is rotated it moves the wedge member  190  causing displacement of the tool holder  186  along with its cutting bit (not shown).  
         [0035]    Having completely described the constructional features of the oval manway facer comprising a preferred embodiment of the present invention, consideration will next be given to its mode of operation.  
         [0036]    The assembly shown in FIGS. 1 and 2 is brought to the site and the housing  12  is centered in the oval opening of the manway to be refurbished. The centering jack screws  26  and the legs  28  with the depth stop pads  29  are used to center and align the oval manway facer within the central opening of the manway. A motor (not shown) is bolted to the face  34  of the motor mount  32  and its shaft is keyed to the sprocket wheel  66 . When the motor is energized, the sprocket will “walk” around the first track defined by the chain  20  affixed to the first major surface  14  of the housing  12 . As the motor and motor mount orbit the oval housing, the arm  38  carrying tool slide assembly  50  also travels in an elliptical, orbital path with the bearing pivot bracket  40  and the manway pivot link  46  constrained to follow the track  44  on the second major surface  16  of the housing  12  by virtue of the fact that the track is clamped between the Vee bearings  84 ,  86  and  122 ,  124 . As a result, a tool bit clamped in the tool holder  186  also moves in the orbital elliptical path. Upon each revolution of the assembly around the track, the cam roller  58  will strike and pass over the tripper bar  60  mounted on the wall defining the central oval opening  18  of the housing. Depending upon the positioning of the control lever  62 , the rotation of the cam  56  upon striking the tripper bar  56  will impart a rotation of the feed screw  144  through a predetermined arc. Rotation of the feed screw, in turn, causes a radial displacement of the tool block  45  along the dove-tail guides on the tool slide  54 . The feed rate of the feed screw  144  can be increased by providing more than one tripper bar  60  in the orbital path traversed by the cam roller  58 .  
         [0037]    As mentioned above, rotation of the height adjustment screw  198  is used to vary the depth-of-cut of the cutting tool with respect to the gasket surface of the manway being machined. This axial adjustment of the tool bit is achieved without need to remount the machine in the manway opening.  
         [0038]    In that the cam lock handle  62  extends through the central opening  18  of the housing it is easily accessible to an operator located outside of the vessel on which the manway is disposed. Thus, the radial feed of the cutting tool can be allowed or arrested by the operator. Because of the open central portion of the machine, the operation can readily inspect the surface as it is being machined so that less rework is required.  
         [0039]    While the invention has been described in detail, it is to be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention, as defined in the appended claims.