| 摘要 |
A thread cutting milling tool comprises a shank with a working portion formed with a recess for receiving a thread cutting insert. The thread cutting insert has one edge formed with a line of thread-form teeth of identical profile. The thread cutting teeth project laterally for cutting engagement with a work-piece while the tool spins about its axis. The tool also orbits within or about a work piece, and in one orbit of the tool in a helical cutting path relative to the work piece a number of complete turns of the screw-thread are formed which is equal to the number of teeth of the insert in engagement with the work-piece. A secondary cutter carried on the thread cutting milling tool provides for formation of a pilot portion or counter bore on the work piece at an end of the screw thread. The pilot portion or counter bore provides for alignment of a threaded member which is to engage the screw thread. Also, the secondary cutter provides for formation of a blunt or scalloped full-thread starting end for the screw thread at the pilot portion. The blunt starting end for the screw thread is robust, resists damage, and resists cross threading.
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