1. Field of the Invention
This invention relates to the field of cutting tools in general and specifically to such tools which are adapted for cutting circular holes in sheet metal, piping, or the like.
2. Discussion of Related Art
Hole saws have been used for many years for the purpose of producing circular apertures in prescribed locations on both planar and curved work surfaces. One of the problems encountered with the use of such saws, especially when used to cut a hole in an enclosed structure, is the retrieval of the cut portion from the interior of the structure. U.S. Pat. No. 485,715, issued Nov. 8, 1892, to Smith, shows a milling tool or cutter used in connection with an apparatus for tapping water mains or other pipes. The Smith device includes a drill which is provided with one or more spring catches which are properly secured to the drill in suitable recesses. The upper portion of the springs project a little beyond the surface of the drill and as the milling tool is being operated, the upper ends will gradually be pressed inward until they pass entirely through the pilot hole. The springs are then effective to retain the cut portion. U.S. Pat. No. 2,800,812, issued July 30, 1957, to Mueller et al, shows a shell cutter assembly which is provided with a pilot drill with means provided on the pilot drill for retaining cut sections. Such means takes the form of a threaded shoulder or detent which is retracted to pass through the hole drilled by the pilot drill and then extended radially outward to engage beneath the cut section. The means comprises a plug which engages one end of a coil spring, the other end of which seats within a bore formed in the detent. U.S. Pat. No. 2,941,427, issued June 21, 1960, to Ver Nooy shows a coupon retainer means for use with tapping machines. The coupon retainer comprises a sleeve which is mounted on the shank of the pilot drill so as to permit rotation of the drill within the sleeve, while the sleeve is limited in longitudinal movement with respect to the pilot drill. Crimping means are provided on the body of the sleeve for engaging and carrying the coupon when the sleeve has advanced into the pilot drill bore hole.
USPTO Backgrounds
USPTO Backgrounds