Patent ID: 9003633
Filing Date: 2015-04-14
Classification: B23B,B25B,F16B,Y10T

Abstract:
1. A method for enlarging an inner end of a blind bore hole, said method comprising the step of forming in a transverse base wall at an inner end of an elongated circular cross-section blind bore hole extending inwardly into a solid body from an outer face thereof an oval cross-section enlargement having a major axis larger than a diameter of said circular cross-section blind bore hole, wherein said step of forming said oval cross-section enlargement in said base wall of said blind bore hole is performed using a bore-hole enlargement tool, said tool comprising; a. a flat fixture base plate having through its thickness dimension a laterally disposed horizontal slot which has a pair of parallel long side edges terminated at opposite ends thereof a pair of opposed transversely disposed short end edges, b. a pair of parallel spaced apart vertical guide members which protrude perpendicularly downwards from said fixture base plate, said vertical guide members having inner facing opposed vertical surfaces adjacent to said long side edges of said slot, c. a lower circular end plate joined to lower ends of said vertical guide members, said lower end plate having through its thickness dimension a central circular perforation coaxially aligned with the center of said slot in said fixture base plate, and d. a rotary cutting tool having an elongated straight drive shaft which is disposed through the slot and perforation, said cutting tool having at a lower end thereof a rotary cutting head, the drive shaft having a lower stop collar located above the cutting head, and an upper stop collar affixed to the drive shaft above the fixture base plate, the drive shaft being rotatable, and longitudinally movable within said slot and said perforation and pivotable between said short end edges of said slot.