| 摘要 |
<p>A method of obtaining on a workpiece a resilient screw thread with a closed helical cavity inside its profile comprises plastic deformation of the walls of a preliminarily manufactured screw groove with a depth exceeding that of the tooth spaces of the screw profile to be obtained, whereas the volume of material of the workpiece displaced when making the screw groove corresponds to the volume of the closed helical cavity inside the profile of the thus obtained screw thread. A thread-forming tool for implementing this method is provided with a shank (1) and a working part (2) consisting of two stages consecutively located along the same axis, one of them being a groove-forming stage (3) and the other a thread-forming stage (4), the thread profile pitches of both of them being equal to each other but shifted reciprocally by at least halfpitch in the axial direction and the external diameter of the groove-forming stage (3) exceeding the external diameter of the thread-forming stage (4). </p> |
