Milling head and methods for tube end preparation

Abstract

A milling head for use in conjunction with a rotary milling tool that is utilized to perform an operation on a tube, preferably of a tube bank or tube wall of a boiler system. The milling head is utilized to remove material or film from the outer diameter of a tube, or place a bevel on a tube end, or both. In one embodiment, the milling head includes at least one outer diameter milling element and at least one bevel milling element that are adjustable in relation to each other as well as the milling head body. Methods for milling a tube are also described.

1 . A milling head for a rotary milling tool, comprising:
 a body adapted to be connected to a rotary milling tool; and   at least one milling element support connected to the body, wherein the milling element support is spaced a distance from a central rotational axis of the milling head, wherein a recess extends a distance between the milling element support and the central rotational axis, wherein the milling element support includes a channel, and wherein the channel has a back wall that longitudinally extends in relation to the central rotational axis of the milling head at an angle of 0° to about 45°; and wherein a bevel milling element having a cutting edge adapted to mill a bevel on a tube is adjustable in the channel and is secured in the channel via a pressure fit.   
     
     
         2 . The milling head according to  claim 1 , wherein a portion of the bevel milling element contacts the channel back wall. 
     
     
         3 . The milling head according to  claim 1 , wherein the channel includes a side, the back wall, and a locking element, and wherein the bevel milling element is secured between the channel side and the locking element. 
     
     
         4 . The milling head according to  claim 3 , wherein the locking element is secured to the milling element support with a securing element. 
     
     
         5 . The milling head according to  claim 4 , wherein the back wall extends longitudinally at an angle from 0° to about 20° with respect to the central axis. 
     
     
         6 . The milling head according to  claim 5 , wherein the back wall extends longitudinally at an angle from 0° to about 10° with respect to the central axis. 
     
     
         7 . The milling head according to  claim 5 , wherein the bevel milling element cutting edge is fixed at an angle of from about 20° to about 60° in relation to the central axis. 
     
     
         8 . The milling head according to  claim 7 , wherein the bevel milling element cutting edge is fixed at an angle from about 30° to about 45° in relation to the central axis. 
     
     
         9 . The milling head according to  claim 6 , wherein the milling element support further includes a guide, wherein an outer diameter milling element is adjustable in relation to the guide and is secured between the guide and a fixing element, wherein the fixing element is connected to the milling element support by a securing element, and wherein the outer diameter milling element has a cutting edge adapted to remove material from the outer diameter of the tube. 
     
     
         10 . The milling head according to  claim 9 , wherein the guide includes a track that extends longitudinally at an angle measured perpendicular to the central rotational axis of the milling head of from 0° to about 45°. 
     
     
         11 . The milling head according to  claim 10 , wherein a portion of the outer diameter milling element contacts the track and is movable along the track before being secured to the milling head and, wherein one cutting edge of the outer diameter milling element has a longitudinal axis that is fixed at an angle with respect to the central axis of the milling head of 0° to about 30°. 
     
     
         12 . A method for milling a tube, comprising the steps of:
 providing a tube having an end portion;   providing a rotary tool having a milling head comprising a body adapted to be connected to a rotary milling tool, wherein the body has an annular recess and one or more milling element supports connected to the body, wherein at least one milling element support includes a channel, wherein a bevel milling element having a cutting edge is adjustable in the channel, wherein the bevel milling element is connected via a pressure fit in the channel between a side of the milling element support and a locking element, wherein at least one milling element support includes a guide, wherein an outer diameter milling element having a cutting edge is adjustable in relation to the guide, wherein the outer diameter milling element is connected to the guide via a pressure fit between a back of the milling element support and a fixing element, wherein the bevel milling element has an annular cutting sweep that is at least concentric with an inner end of a cutting sweep of the outer diameter milling element and radially inward a distance from the outer diameter milling element cutting sweep;   adjusting at least one of the outer diameter milling elements or bevel milling elements in relation to the milling head body and securing the at least one element to the milling head; and   milling the end portion of the tube by removing material from an outer diameter of the tube and placing a bevel on the end of the tube.   
     
     
         13 . The method for milling a tube according to  claim 12 , including the step of removing from about 1% to about 50% of an annular thickness of the tube with the milling head. 
     
     
         14 . The method for milling a tube according to  claim 12 , including the step of utilizing a gauge to set at least one of the milling head milling elements.