1) outer diameter d (large diameter) (d) — the diameter of the imaginary cylinder that coincides with the top of the outer thread tooth — also known as the nominal diameter
2) inner diameter (path) d1(d1) — the diameter of the imaginary cylinder that coincides with the bottom of the outer thread, and is used to calculate the diameter of the dangerous section in the strength calculation
3) median diameter d2 –The diameter of the imaginary cylinder at the position where the tooth thickness is equal to the width between the teeth in the axial section 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 corresponding to two points on the bus of the middle diameter cylinder
5) lead (S) — the axial distance between two adjacent teeth on the same spiral line and corresponding two points on the bus of the cylinder with the middle diameter
6) number of threads n — number of thread helix, generally for the convenience of manufacturing n less than or equal to 4 the relationship between pitch, lead and number of threads: S=nP
7) spiral lift Angle — the Angle between the tangent line of a spiral line on a cylinder of median diameter and a plane perpendicular to the axis of the spiral line.
8）Tooth type alpha — the Angle between the two sides of the thread type in the axial plane of the thread
9) profile bevel Angle — the Angle between the side of the profile and the vertical plane of the thread axis.Symmetric teeth type
The main geometrical dimensions of various threads (except rectangular threads) are referred to the relevant standards — nominal dimensions are the outer diameter of the thread and the inner diameter of the pipe approximately equal to that of the pipe.
The self-locking condition of screw pair is that the rise Angle of thread is less than or equal to the equivalent friction Angle of screw pair.
The transmission efficiency of screw pair is: the ratio of effective work to input work when the nut rotates once.
Circumferential force required to overcome the axial force Q to rise uniformly
Post time: Nov-27-2018