Cam-controlled tube end finishing apparatus and method

An apparatus for finishing an end of a rotating hollow tube, said finishing apparatus comprising:

• (a) a cutting bit having multiple cutting faces;
• (b) a platform supporting said cutting bit adjacent to the end of the rotating tube;
• and
• (c) means for moving said platform and thereby said cutting bit relative to the end of the rotating tube along a closed path of travel including
• (i) a cutting leg in which said moving means is capable of moving said cutting bit from a home position and from the outside to the inside of the rotating tube to sever an initial portion of the tube end at an acute angle to a plane normal to the rotational axis of the tube so as to define an initial cut face on the tube end extending in inclined relation to a plane normal to the rotational axis of the tube,
• (ii) a traversing leg in which said moving means is capable of moving said cutting bit toward the rotational axis of the tube in a plane normal to the rotational axis of the tube,
• (iii) a facing leg in which said moving means is capable of moving said cutting bit from the inside to the outside of the rotating tube to sever a final portion of the tube end at an acute angle to a plane normal to the rotational axis of the tube so as to provide a substantially burr-free cut face on the tube end extending in a plane normal to the rotational axis of the tube, and
• (iv) a retracting leg in which said moving means is capable of moving said cutting bit away from the rotational axis of the tube and back to said home position of the cutting bit.

A method for finishing an end of a rotating hollow tube, said finishing method comprising the steps of:

• (a) supporting a cutting bit adjacent to the end of the rotating tube;
• and
• (b) moving the cutting bit relative to the end of the rotating tube along a closed polygonal path of travel,
• (i) first, from a home position along a cutting leg of the path to sever an initial portion of the tube end is in a direction from the outside to the inside of the rotating tube at an acute angle to a plane normal to the rotational axis of the tube so as to define an initial cut face on the tube end extending in inclined relation to a plane normal to the rotational axis of the tube,
• (ii) second, along a traversing leg of the path toward the rotational axis of the tube in a plane normal to the rotational axis of the tube,
• (iii) third, along a facing leg of the path to sever a final portion of the tube end in a direction from the inside to the outside of the rotating tube at an acute angle to a plane normal to the rotational axis of the tube so as to provide a substantially burr-free cut face on the end of the tube extending in a plane normal to the rotational axis of the tube, and
• (iv) fourth, along a retracting leg of the path away from the rotational axis of the tube back to the home position of the cutting bit.