ISO metric screw external thread root contour according to ISO 965-1
for positions e, f, g
Parameter |
Equation |
Height of fundamental triangle
[H] |
$$H=\frac { \sqrt { 3 } }{ 2 } P$$ |
Thread basic pitch diameter [d2 , D2] |
$${ d }_{ 2 }={ D }_{ 2 }=d-2\times \frac { 3 }{ 8 } H=D-2\times \frac { 3 }{ 8
} H$$ |
Thread basic minor diameter [d1 , D1 ] |
$${ d }_{ 1 }={ D }_{ 1 }=d-2\times \frac { 5 }{ 8 } H=D-2\times \frac { 5 }{ 8
} H$$ |
External thread minimum truncation [Cmin] |
$${ C }_{ min }=0.125P$$ |
External thread maximum truncation [Cmax] |
$${ C }_{ max }=\frac { H }{ 4 } -{ R }_{ min }\left\{ 1-\cos { \left[ \frac {
\pi }{ 3 } -\arccos { \left( 1-\frac { { T }_{ d2 } }{ 4{ R }_{ min } } \right)
} \right] } \right\} +\frac { { T }_{ d2 } }{ 2 }$$ |
External thread maximum major diameter [dmax] |
$${ d }_{ max }=d+es$$ |
External thread minimum major diameter [dmin] |
$${ d }_{ min }={ d }_{ max }-{ T }_{ d }$$ |
External thread maximum pitch diameter [d2max] |
$${ d }_{ 2max }={ d }_{ 2 }+es$$ |
External thread minimum pitch diameter [d2min] |
$${ d }_{ 2min }={ d }_{ 2max }-{ T }_{ d2 }$$ |
External thread maximum minor diameter [d3max] |
$${ d }_{ 3max }={ d }_{ 1 }-es-2y$$ |
External thread minimum minor diameter [d3min] |
$${ d }_{ 3min }={ d }_{ 1 }-es-2z$$ |
Dimension y |
$$y={ R }_{ min }\left\{ 1-\cos { \left[ \frac { \pi }{ 3 } -\arccos { \left(
1-\frac { { T }_{ d2 } }{ 4{ R }_{ min } } \right) } \right] } \right\} $$ |
Dimension z |
$$z=\frac { H }{ 4 } +\frac { { T }_{ { d }_{ 2 } } }{ 2 } -\frac { P }{ 8 }$$ |
Internal thread minimum major diameter [Dmin] |
$${ D }_{ min }=D+EI$$ |
Internal thread maximum pitch diameter [D2max] |
$${ D }_{ 2max }={ D }_{ 2min }+{ T }_{ D2 }$$ |
Internal thread minimum pitch diameter [D2min] |
$${ D }_{ 2min }={ D }_{ 2 }+EI$$ |
Internal thread maximum minor diameter [D1max] |
$${ D }_{ 1max }={ D }_{ 1min }+{ T }_{ D1 }$$ |
Internal thread minimum minor diameter [D1min] |
$${ D }_{ 1min }={ D }_{ 1 }+EI$$ |
Note:
es, EI-
Fundamental deviation,
Td-Major diameter tolerance of external thread,Td2-Pitch diameter tolerance of external thread,TD1-Minor diameter tolerance of
internal thread,
TD2-Pitch diameter tolerance of internal thread