Non cutting thread tap - has square section shaft ground to ellipse able to roll material in hole

Abstract

Abstract The tap is made from a square shaft section, with the corners well rounded while the sides bulge out. During mfr. of the tap, the grinding wheel which cuts the thread in the tap moves in and out to follow the circumference of the section. After the thread is cut, a thin grinding wheel with narrow cylindrical face is used to grind the tip of the thread and to grind the whole depth of thread away over part of the circumference of one thread so that the thread extends in one direction only. This part of the thread is rounded so that the part of the thread that remains is in the shape of the end of an ellipse. Each consecutive protruding part of the thread is off-set from the previous section by 90 deg. The part of the thread that is ground away ensures that there is room for the material that is being displaced when the tap is screwed into the hole.

Inventors

No inventors recorded.

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