The main parameters of the thread:
1) Ball screw outer diameter d (major diameter) (D)-the diameter of an imaginary cylindrical surface coincident with the crest of the external thread-also known as the nominal diameter.
2) Inner diameter (minor diameter) d1 (D1)-the diameter of the imaginary cylindrical surface coincident with the bottom of the external thread, which is used as the calculated diameter of the dangerous section in the strength calculation.
3) Pitch diameter d2——The diameter of the imaginary cylindrical surface where the tooth thickness is equal to the width between the teeth in the axial section, which is approximately equal to the average diameter of the thread d2≈0.5 (d+d1).
4) Pitch P-the axial distance between two adjacent teeth on the generatrix of the cylindrical surface of the pitch diameter.
5) Lead (S)-the axial distance between two adjacent teeth on the same spiral line on the generatrix of the cylindrical surface of the pitch diameter.
6) Number of threads n——the number of spiral threads, generally for the convenience of manufacturing n≤4 The relationship between pitch, lead and number of threads: S=nP.
7) Helix angle ψ——the angle between the tangent of the helix on the cylindrical surface of the middle diameter and the plane perpendicular to the axis of the helix.
8) Thread angle α-the angle between the two sides of the thread profile in the thread axial plane 9) Thread bevel angle β-the angle between the side of the thread profile and the vertical plane of the thread axis. Symmetrical teeth.
The main geometric dimensions of various threads (except rectangular threads) can be found in the relevant standards-the nominal size is the outer diameter of the thread to the pipe thread approximately equal to the inner diameter of the pipe.
The self-locking condition of the screw pair is: the thread lift angle is less than or equal to the equivalent friction angle of the screw pair.
The transmission efficiency of the screw pair is: the ratio of the effective work to the input work when the nut rotates once.
The circumferential force required to overcome the axial force Q rising at a constant speed
