Abstract:
A portable tool for squaring the ends of tubes is adapted to be coupled to an electrically powered hand drill for driving a shaft carrying a cutting tool at the free end thereof. The shaft is journaled for rotation in a tubular torque housing that is effectively clamped to the drive motor partially. Surrounding the torque housing is an axial feed housing that is keyed to the torque housing by elongated keys disposed in axially aligned keyways formed in both the torque housing and the axial feed housing. A portion of the axial feed housing has external threads adapted to mate with internal threads on a manually rotatable feed ring. A workpiece clamping collet assembly is affixed to the end of the axial feed housing such that when the feed ring is rotated, the workpiece is may be axially displaced against the spinning/cutting tool.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to power tools used for metal working, and more particularly to a machine for preparing industrial tubing by squaring the end thereof prior to joining same to another tube or fitting in a welding operation and/or for trimming such a tube to a precise length in plumbing a fluid flow system. 
     II. Discussion of the Prior Art 
     The E.H. Wachs Company of Welling, Ill., produces and sells a tube squaring tool that conforms to the teachings of the Pierce U.S. Pat. No. 5,619,893. It comprises a hand-held, electrically-powered drive motor similar in construction to a conventional ½″ power drill with a pistol grip, but instead of supporting a drill bit in a chuck, the motor shaft is coupled to a coaxially aligned shaft of the tube squaring tool which has a cutting tool retainer formed at the free end thereof. Surrounding the squaring tool shaft is a housing that is fixedly clamped to the drive motor housing at one end thereof, with the opposite end including a collet retainer for holding a collet used to clamp a tubular workpiece to be squared. Coaxially disposed about the housing is a feed nut having internal threads that mesh with external threads on a feed ring. When the feed nut is rotated in a clockwise direction, the shaft is displaced axially toward the end of the tube workpiece to be squared. In this manner, the rotatable cutting tool may be brought into contact with the end of a tube to thereby shave material from it. 
     Unfortunately, tube squaring machines conforming to the Pierce patent have a serious design flaw that adversely impacts the quality of the machining operation being performed. The shaft is journaled for rotation at two relatively closely spaced locations proximate the midpoint of the shaft such that a substantial portion of the tool&#39;s shaft and the weight of the tool holder portion thereof is cantilevered relative to the journal bearings. The cantilevered shaft length increases as the feed nut is rotated to advance the cutting tool toward the stationary workpiece. It is found that after a relatively short period of use, the cutting tool not only rotates but wobbles in a plane perpendicular to the normal axis of the shaft resulting in “chattering”. This chattering leads to irregularities in the end of the tube being machined. In addition, the bearings themselves are subject to relatively rapid wear that requires that the tool be taken out of service for refurbishment. 
     SUMMARY OF THE INVENTION 
     The present invention obviates the foregoing difficulties by providing a tool for squaring the ends of tubular workpieces having a shaft member with first and second ends, the first end including a clamping device for holding a cutting tool bit therein and the second end adapted to be coupled to a shaft of a drive motor. A tubular torque housing surrounds the shaft and the torque housing has axially extending keyways formed in a peripheral surface thereof. The shaft is journaled for rotation within a central bore of the torque housing by bearings that are located proximate opposite ends of the shaft so that only a relatively small portion of the shaft is cantilevered beyond the end of the frontmost bearing. The shaft is constrained from axial displacement within the torque housing. 
     A generally cylindrical axial feed housing having first and second ends and a central bore extending therethrough receives the torque housing and cutting tool shaft therein and it, too, has axially extending keyways projecting radially outward of its central bore. Key members share the keyways of both the torque housing and the axial feed housing, preventing rotation of the axial feed housing about the torque housing. The first end of the axial feed housing has external threads formed thereon and its second end includes a circular flange. A workpiece holding collet clamping assembly is affixed to this circular flange. A feed ring fits over the axial feed housing and the feed ring has internal threads that engage the external threads on the axial feed housing. Now, when the feed ring is manually rotated, it will axially displace the axial feed housing with its attached workpiece holding collet in an axial direction toward or away from the cutting tool secured to the outer end of the rotatable shaft, depending upon the discretion of rotation of the feed ring. 
     Because the shaft is immovable in the axial direction and is well supported by journal bearings proximate opposed ends thereof, with only a short length of the shaft being cantilevered, there is no tendency for chattering to occur as in the prior art E.H. Wachs Co. tube squaring tool. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The foregoing features, objects and advantages of the present 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: 
     FIG. 1 is an exploded view of a tool for squaring the ends of tubular workpieces constructed in accordance with the present invention; 
     FIG. 2 is a longitudinal cross-sectional view illustrating the cooperative relationship between the part shown in FIG. 1; and 
     FIG. 3 is an exploded view showing the manner in which the tube squaring tool is coupled to a power drill as a drive motor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     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. 
     Referring to FIG. 1, the tube squaring machine is indicated generally by numeral  10  and is seen to include a base plate  12  having a pedestal  14  secured thereto and projecting upwardly therefrom. Affixed to the upper end  16  of the pedestal by a bolt (not shown) is a motor mount adapter  18  comprising a cylinder having a notch  20  formed in its lower surface for indexing the motor mount adapter  18  to the pedestal  14 . Referring to both FIG.  1  and FIG. 3, the motor mount adapter  18  includes a reduced diameter portion  22  that is split, as at  24 , and a central, axially extending bore  26  extends through it, allowing the nose portion  27  of a power drill drive motor housing  29  to fit therein. A motor clamp ring  28 , comprising two semi-circular segments  30  and  32 , is adapted to fit over the reduced diameter portion  22  of the motor mount adapter. Now, when bolts  31  (FIG. 3) are passed through apertures as at  34  in the segment  30  and into a tapped hole as at  36  in segment  32  (FIG.  1 ), the two halves can be drawn tightly together to clamp about the reduced diameter portion  22  and squeeze the split segments thereof against the nose  27  of the motor housing  29  to thereby firmly clamp and support the drive motor  33  relative to the tube squaring tool  10  of the present invention. 
     Bolted to the front face  38  of the motor mount adapter  18  is a torque housing  40  (FIGS.  1  and  2 ). It is tubular in configuration and has a central bore  42  therethrough. Counterbores  44  and  46  are formed at opposed ends thereof for receiving a front needle bearing assembly  48  and a rear needle bearing assembly  50  therein. The tubular torque housing  40  includes axially extending keyways, as at  52 , formed inwardly from the outer peripheral surface thereof for partially receiving approximately one-half the thickness of elongated key members  54  and  56  therein. 
     The needle bearings  48  and  50  are used to journal a cutting tool drive shaft member  58  for rotation within the torque housing  40 . As can be seen in FIG. 1, the shaft  58  has a first end  60  comprising a cutting tool bit holder  62  that is adapted to hold a tool bit (not shown) within a diametrically extending groove  64 , formed in a front face thereof. The tool bit is held in place by one or more set screws fitted into threaded bores as at  66 . The cutting tool drive head shaft  58  has a smooth, machined shoulder portion  68  dimensioned to closely fit within the inner race of the front needle bearing assembly  48  which, in turn, fits within the counterbore  44 . A second shoulder portion of reduced diameter  70  cooperates with the needle bearing  50  disposed in the counterbore  46  of the torque housing  40 . A thrust bearing  72 , along with thrust washers  74  and  76 , is placed between the front bearing  48  and the tool holding member  60  of the shaft  58 . Likewise, a rear thrust bearing  78  and associated thrust washers  80  and  82  cooperate with the rear needle bearing assembly  50  and a shoulder (not shown) defined by the counterbore  46  when a lock nut  84  is screwed onto the threaded portion  86  of the cutting head shaft  58 . Thus, the shaft member  58  is captured and journaled for rotation within the torque housing  40 . 
     The cutting tool drive shaft  58  includes a squared end portion  88  that is adapted to fit within a complimentary opening  90  of a shaft coupler  92 . Shaft coupler  92  also fits over the drive shaft  35  of the drill motor  33  used to power the tube squaring machine. 
     Surrounding the torque housing  40  is a generally cylindrical axial feed housing member, indicated generally by numeral  94 . The axial feed housing has a first end  96  that has external threads  98  formed thereon. The second end  100  includes an annular flange  102 . The flange  102  includes a plurality of regularly angularly spaced recesses as at  104 , for receiving corresponding mounting feet  106  of a collet housing member  108 . Screws (not shown) are used to secure the feet  106  to the flange  102 . 
     As can further be seen in FIG. 1, the axial feed housing  94  includes keyways  110  and  112  formed radially outward of the central bore  115  of the axial feed housing. Their depth is about one-half the thickness of key members  54  and  56 . When the axial feed housing  94  is fitted over the torque housing  40 , the axially extending keys  54  and  56  share both the keyways  52  on the torque housing and the keyways  110  and  112  on the axial feed housing. In that the torque housing  40  is rigidly affixed by bolts to the motor mount adapter  18 , neither the torque housing nor the axial feed housing is able to rotate because of the presence of the keys  54  and  56  shared in the keyways. 
     As best seen in the cross-sectional view of FIG. 2, a feed ring  114  partially surrounds the axial feed housing  94  and formed on the internal diameter of the feed ring  114  are threads  116  that mate with the threads  98  of the axial feed housing  94 . The feed ring  114  also has a central opening  118  formed in a rear surface thereof whose diameter is only slightly larger than the outside diameter of the rear portion  46  of the torque housing  40 . Front and rear thrust washers  120  and  122  are placed about the reduced diameter portion  46  of the torque housing to sandwich the feed ring flange therebetween. 
     As seen in FIG. 1, it has been found expedient to provide equally spaced fiducial scale markings  124  about the periphery of the axial feed housing and these scale markings cooperate with indexing notches  126  formed on the front edge of the feed ring. The outer surface of the feed ring is scalloped to facilitate manual gripping and rotation thereof. 
     The collet housing  108  is adapted to support a variety of different size collets, only one of which is shown and is identified by numeral  128 . Each of the collets comprise first and second semi-circular members  130  and  132  that cooperate with one another to form a circular opening of a predetermined size for receiving a cylindrical workpiece therethrough. The lower segment  130  is held in clamped relationship to the face  134  of the collet housing  108  by cover plates  136  and  138  which attach to the collet housing by bolts (not shown). The right cover plate  138  is pivotally connected to the collet housing  108  by a pin (not shown) passing through the aperture  140  therein and into a corresponding bore or aperture in the face  134 . An eye bolt member  142  has an enlarged, flattened end portion  144  with a bore  146  formed therethrough in the transverse direction, the head portion dimensioned to fit in a slot  148  formed in the collet housing. A dowel pin  150  is inserted through aligned holes in the housing and in the head of the eye bolt, allowing it to pivot into a slot  152  formed in the upper end of the right cover plate  138 . Now, when the knob  154  is screwed down along the shaft of the eye bolt  142  the cover plate  138  clamps the lower half  130  of the collet tightly in place. 
     To adjust the effective diameter of the collet, there is provided a threaded shaft  156  that passes through a threaded bore  157  in the collet housing. The lower end of the threaded rod  156  has an annular notch  158  defining a head portion  160  that is adapted slide into a T-slot  162  in the upper half  132  of the collet. A knob  164  is affixed to the threaded rod  156  to facilitate its rotation. Rotation of the knob  164  effectively displaces the upper portion  132  of the collet  128  relative to the lower half to clamp and unclamp a tubular workpiece inserted through the central opening of the collet as well as the central opening  166  formed through the face plate  134  of the collet housing  108 . 
     Operation 
     In use, the knob  154  will be loosened on the threaded shaft  142  to the point where the eye bolt can be rotated out of the groove  152  on the right collet holder  138 . The right collet holder can then be swung clockwise when viewed in FIG. 1, allowing the insertion of a collet of a desired size to accommodate the outside diameter of the tubular workpiece to be squared. The collet halves  130  and  132  are then assembled into the collet holder  108  and the right collet holder  138  is now rotated counterclockwise and the eye bolt  142  is lowered into the notch  152 . Tightening the knob  154  firmly clamps the lower collet member  130  in place. As the upper collet member  132  is being inserted, the head  160  on the threaded shaft  156  is slid into the T-notch  162 . Next, the tubular workpiece has one end thereof slipped through the circular opening of the collet and through the central opening  166  in the collet holder in facing relationship to the cutting tool located in the notch  64  on the left end of the cutting head shaft  58 . Now, the knob  164  is rotated so as to close the collet around the workpiece and tightly clamp it in place. 
     The motor  33  can now be energized to rotate the shaft  58  within its bearings  48  and  50  contained in the torque housing  40 . To bring the rotating cutting tool into engagement with the end of the workpiece to be squared, the operator will rotate the feed ring  114  in a clockwise direction. Because of the presence of the keys  54  and  56  in both the keyways of the torque housing  40  and the axial feed housing  94 , the axial feed housing is constrained to move rearward in the axial direction, carrying the collet housing assembly  108  and the workpiece with it and against the spinning cutting tool supported in the tool holding member  60  on the end of shaft  58 . 
     The scale  124  is such that as one of the notches  126  on the feed ring moves from one fiducial mark on the scale  124  to the next, the workpiece is moved 0.002″, given the pitch on the threads  98  and  116 . 
     This 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 such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.