Centrifugally-cast tube and related method and apparatus for making same

Abstract

An improved centrifugally-cast tube is provided, along with a related method and apparatus of making the tube. The tube includes a plurality of grooves and bosses that are mechanically machined into an interior surface of the tube, such as by a broaching process. The profile of grooves and bosses may be defined by a plurality of intersecting concave and convex radii. The tube is resistant to creep, carburization and metal dusting. The tube also has an enhanced heat transfer rate, and a desirable surface roughness. A method of making the tube is also provided. The method essentially consists of mechanically deforming the interior surface of the tube by passing a series of cutting inserts on support rings having incrementally-differing dimensions over the interior surface. An apparatus is also provided which includes a telescoping shaft upon which is mounted at least one cutting tool that has a plurality of cutting inserts and is adapted to form a plurality of grooves and bosses in the interior surface of the tube. The grooves and bosses may be straight or spiraled.

1 - 12 . (canceled) 
   
   
       13 . An apparatus for improving a centrifugally-cast tube comprising:
 a first and second guide adapted to hold the tube;   a shaft adapted to pass longitudinally through a bore of the tube; and   at least one cutting tool attached to the shaft and including a plurality of cutting inserts, the cutting tool being adapted to mechanically form a profile of grooves or bosses within the bore of the tube.   
   
   
       14 . The apparatus of  claim 13 , wherein the cutting inserts are indexable. 
   
   
       15 . The apparatus of  claim 13 , wherein the cutting inserts are provided with concave cutting surfaces. 
   
   
       16 . The apparatus of  claim 13 , wherein the cutting inserts are provided with convex cutting surfaces. 
   
   
       17 . The apparatus of  claim 13 , wherein the at least one cutting tool includes a plurality of cutting tools attached to the shaft, and further including at least one spacer collar disposed about the shaft and adapted to maintain the cutting tools in spaced relationship. 
   
   
       18 . The apparatus of  claim 13 , further including means for lubricating the apparatus. 
   
   
       19 . The apparatus of  claim 13 , further including means for attaching the at least one cutting tool to the shaft. 
   
   
       20 . The apparatus of  claim 13 , further including means for attaching the at least one cutting tool to the shaft. 
   
   
       21 . The apparatus of  claim 13 , further including at least one centering guide.