Debeading tool for butt-welded plastic pipe

Abstract

A debeading tool capable of internally debeading butt-welded pipe made of PVC and similarly hard plastics has a work head that can be coupled to a distal end of a torque tube. The work head includes a motor carrying a cutter which is oriented at an angle, e.g., 12 degrees, to the interior pipe wall for cutting the weld bead as the tool is rotated inside the pipe. The work head cutter can be moved between an insertion/removal position away from the side wall and a cutting position against the bead on the side wall. A locator assembly that contacts the bead during insertion of the work head aids in positioning the cutter to straddle the weld bead. A pipe cleaner can be prepositioned in the pipe before butt-welding to be engaged upon removal of the work head to pull weld bead chips and fines from the pipe.

1 . A work head for a debeading tool for debeading a joint in butt-welded plastic pipe, comprising:
 a frame having a coupler to couple the work head to a distal end of a torque tube;   a rotary cutting motor mounted on the frame and having an output shaft;   means for moving the cutting motor transversely of the torque tube axis between an insertion position spaced away from an interior wall of the pipe and a cutting position in which the output shaft is oriented in a cutting position at a predetermined angle relative to the torque tube axis;   a locating gauge mounted on a distal end of the work head for contacting a weld bead when the tool is in the insertion position; and   a rotary multifluted cutter mounted on the output shaft in longitudinal alignment with the locating gauge;   the cutter having a plurality of cutting flutes oriented relative to the predetermined angle of the motor output shaft so that the flutes are substantially parallel to the interior wall of the pipe when the tool is in the cutting position for cutting the weld bead.   
   
   
       2 . A work head according to  claim 1  in which the frame is mounted on a transverse track and the cutting motor is fixed to the frame. 
   
   
       3 . A work head according to  claim 1  in the frame is affixed to the distal end of the torque tube and the cutting motor is pivotally mounted on the frame. 
   
   
       4 . A work head according to  claim 1  including a means mounted on the locating gauge for engaging a pipe cleaning tool to pull through the pipe after cutting the weld bead. 
   
   
       5 . A work head according to  claim 4  including a pipe cleaning tool for removal of chips and fines from inside a butt-welded plastic pipe, the pipe cleaning tool comprising:
 at least one cleaning disk mounted on an axial shaft; and   an engagement structure mounted on the shaft in position to be engaged by the means for engaging for retraction from the pipe;   the disk having a diameter sized to an inside diameter of the pipe to sweep fines and chips therefrom when pulled through the pipe.   
   
   
       6 . A work head according to  claim 1  in which the rotary multifluted cutter includes:
 a shank;   a plurality of flutes disposed helically around the shank and oriented at an angle relative to the shank so as to taper inward proceeding from the shank toward a distal end of the cutter; and   a circular bearing mounted at the distal end of the cutter defining a gauge for maintaining the flutes substantially parallel to a sidewall of the pipe.   
   
   
       7 . A work head according to  claim 6  in which the flutes are each curved arcuately about a predetermined radius such that the cutter has a maximum radius midway between the shank and the distal end. 
   
   
       8 . A work head according to  claim 6  in which the flutes are angled at about 12 degrees relative to the shank and are curved about approximately a 3.5 inch (8.9 cm.) radius. 
   
   
       9 . A method of debeading a joint in a butt-welded plastic pipe, comprising:
 inserting a rotary cutting motor having an output shaft and a rotary multifluted cutter mounted on the output shaft lengthwise inside a butt-welded plastic pipe while retaining the cutting motor and cutter in an insertion position spaced away from an interior wall of the pipe;   positioning the rotary cutting motor lengthwise in the pipe so that the rotary multifluted cutter is located radially adjacent a butt-weld bead in the pipe;   moving the cutting motor transversely between the insertion position and a cutting position in which the motor output shaft is oriented in a cutting position at a predetermined angle relative to an axis of the pipe so that the cutter engages the butt-weld bead; and   operating the cutting motor to cut the butt-weld bead while rotating the cutting motor around the inside of the pipe;   the cutter having a plurality of cutting flutes oriented relative to the predetermined angle of the motor output shaft so that the flutes are substantially parallel to the interior wall of the pipe when the tool is in the cutting position.   
   
   
       10 . A method according to  claim 8  in which the positioning step includes locating the cutting motor by detecting the butt-weld bead during insertion and fixing the cutting motor longitudinally in the pipe to retain the cutter adjacent the butt-weld bead. 
   
   
       11 . A method according to  claim 8  including:
 inserting a pipe cleaning tool for removal of chips and fines into the butt-welded plastic pipe prior to inserting the rotary cutting motor, the pipe cleaning tool comprising:   at least one cleaning disk mounted on an axial shaft; and   an engagement structure mounted on the shaft in position to be engaged by a debeading tool for retraction from the pipe;   the disk having a diameter sized to an inside diameter of the pipe to sweep fines and chips therefrom when pulled through the pipe; and   after operating the cutting motor to cut the butt-weld bead, with drawing the rotary cutting motor and the pipe cleaning tool from the pipe.   
   
   
       12 . A pipe cleaner for removal of chips and fines from inside a butt-welded plastic pipe, comprising:
 at least one cleaning disk mounted on an axial shaft; and   an engagement structure mounted on the shaft in position to be engaged by a debeading tool for retraction from the pipe;   the disk having a diameter sized to an inside diameter of the pipe to sweep fines and chips therefrom when pulled through the pipe.