Ton Tube and Rod Extrusion Press Fig

The nominal tensile stress in the cross-section F of the core of the thread is with 

The thread is in saw-tooth form as per DIN 2781 (see Table 19) with approximately the same fatigue-stress concentration factor as that of Whitworth threads consequently — 2.2 —3.2 for medium carbon steel. Let = 2.7, then the maximum stress at the notch is 

The columns are made of steel C 35 having a yield point = 3,200 kg/cm and approximately equal fatigue limit, consequently a Then the safety factor 

It has still to be mentioned that the middle part of the column with some of the pitches, which cannot be prestressed, is subjected to a full repetitive stress however, no forces are transmitted from these pitches to the nut. The fatigue-stress concentration factor existing here is therefore the considerably lower one of the notched bar. 

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