Method and apparatus for producing bypass grooves

The present invention is directed to a method and apparatus for simultaneously producing multiple linear grooves on the internal surface of cylindrical tubes. The apparatus comprises an outer cage assembly with a mandrel assembly axially and slideably disposed therein. Additionally, each assembly is capable of independent nonrotational linear motion. The cage assembly is introduced into the inner diameter of the tube along their common cylindrical axis. A multiplicity of spherical roller elements, retained within circumferentially spaced ports near the entry end of the cage assembly maintain resting contact with the mandrel assembly disposed within the cage assembly. The entry end of the mandrel assembly is conically tapered to define a range of radial motion for the rollers upon linear movement of the mandrel assembly. This linear movement of the mandrel assembly generates radial expansion of the circumferentially spaced rollers into pressing contact with the pressure tube. Thereafter, linear nonrotational movement of the cage assembly defines the length of the linear grooves made by the rolling motion of the rollers upon maintained radial expansion. Variable radial expansion during motion of the cage assembly permits production of the grooves having tapered geometric profiles.