| 摘要 |
A screw (2) which produces a thread which is to gauge when it is screwed into drilled holes is intended to be capable of being produced just as easily as normal screws. The shank in which the thread pitches (15) are rolled has a circular core cross-section over its entire length. Protuberances (16) which project radially out of the thread pitches (15), are formed out of the shank material. The protuberances (16) run steeply in a helical shape around the shank circumference and are superimposed on the thread pitches (15). Each protuberance (16) has a constant width over the thread edges and the thread tip of the respective thread pitch. The screws are produced on thread-rolling machines by means of grooved flat jaws which have a hardness between 2000 and 2600 N/mm<2>. In this case, screw blanks having a hardness of 400 to 500 N/mm<2> are used, into which the thread pitches (15) and the protuberances (16) are rolled at the same time. <IMAGE> |
