Power generating or other plants circulate fluids, such as water or steam, through tubes or banks of tubes. The fluid is often heated and used, for example, to drive turbines which generate electricity. On account of deterioration due to corrosion and the like, tubes occasionally require replacement. The tubes to be repaired or replaced are generally cut out in a predetermined area utilizing a power saw or cutting torch. For example, see U.S. Pat. No. 5,033,347, herein fully incorporated by reference.
Such tubes requiring replacement or repair can be heat exchanger tubes comprising a tube having heat dissipating elements arranged on an outer surface of the tube. The heat dissipating elements are arranged in any pattern and are typically welded or adhered to the tube, or the like. The heat dissipating elements aid in transferring heat between the tube and the ambient atmosphere. Such heat exchanger tubes are well known in the art, see U.S. Pat. No. 4,051,586 to Hicks for example.
In order to repair heat exchanger tubes, the end of the tube must be prepared and often it is desirable to remove any heat dissipating elements within an area a predetermined distance from the tube end. Various devices and methods for removing heat dissipating elements have been proposed in the prior art.
U.S. Pat. No. 4,747,886 relates to a robot drive for cutting fins having pipes extending on opposite sides therefrom, with the pipes laying in parallel spaced apart rows, comprising a carriage which can move in the longitudinal direction between rows of the pipes. A pair of drive guide rollers is mounted to the carriage for rolling against the pipe of one of the rows. The carriage also carries four spring loaded pressure wheels which bear against the fins of the pipe in an adjacent row so as to press the carriage and guide rollers against the pipe on which the guide rollers roll. A pair of cutting torches or mechanical cutters are connected to the carriage on opposite sides of the guide rollers so they can cut the fins of the pipes on which the guide rollers roll.
U.S. Pat. No. 5,160,549 relates to a tube fin trimming machine adapted for clamping and cutting elongated finned structures, such as finned tubes. The trimming machine includes an elongated main frame having at least one guideway, support means attached to the base plate and adapted for supporting the finned structure of a carriage unit longitudinally movable relative to the main frame and guideway, and at least one cutting torch unit movably mounted on the carriage unit. Each cutting torch is mounted above an elongated fin and is moved both longitudinally and laterally relative to the fin, so as to provide a desired elongated tapered shape for the fin. The invention also relates to a method for operation of the fin trimming machine to perform desired trimming operations on elongated finned structures, such as finned tubes.
In order to prepare heat exchanger tubes for further use, it would be beneficial to provide a rotary milling tool having a milling head capable of removing heat dissipating elements from the end of a tube. After selected heat dissipating elements are removed, the tube can be further processed and joined with a second tube as known in the art.