Qingdao Haorui Steel Products Co., Ltd.
Mob: 15966945003
Contact: Yanan Wang
Tel: 0532-87881070
Fax: 0532-87980111
Email: wang@qdhaorui.com
Add: No. 375, Zhengyang East Road, Xifu Town, Chengyang District, Qingdao
What are the main geometric parameters of mechanical threads?
As for the thread of standard parts, the outer diameter, pitch, tooth type, length, etc. have different index requirements. The following is a brief introduction to these problems.
(1) Thread major diameter/tooth outer diameter (D, d): It is the imaginary cylinder diameter where the top of the external thread or the bottom of the internal thread overlaps. The major diameter of the thread basically represents the nominal diameter of the thread size.
(2) The pitch diameter of the thread (D2, d2): D2=d2=D(d)－2x3H/8, where H is the height of the original triangle:
H=(√3 /2)P=0.866025P(60O Asan Cape); H=0.960491P(55O Asan Cape)
(3) Minor diameter of thread/bottom diameter (D1, d1): It is the diameter of an imaginary cylinder where the crest of the external thread or the crest of the internal thread overlaps.
(4) Thread pitch (P): It is the axial distance between two adjacent teeth on the pitch line corresponding to two points or the distance between adjacent tooth mountains or two adjacent tooth valleys. In the imperial system, the number of teeth per inch (25.4mm) is used to indicate the pitch (see the table below).
specification | Tooth pitch | specification | Weigh call path | Number of teeth | ||||||
Coarse teeth | Fine teeth | Very fine teeth | Coarse teeth | Fine teeth | Webster teeth | |||||
M3 | 0.5 | 0.35 | 4# | 2.9 | 40 | 48 | ||||
M4 | 0.7 | 0.5 | 6# | 3.5 | 32 | 40 | ||||
M5 | 0.8 | 0.5 | 8# | 4.2 | 32 | 36 | ||||
M6 | 1.0 | 0.75 | 10# | 4.8 | 24 | 32 | ||||
M7 | 1.0 | 0.75 | 12# | 5.5 | 24 | 28 | ||||
M8 | 1.25 | 1.0 | 0.75 | 1/4 | 6.35 | 20 | 28 | 20 | ||
M10 | 1.5 | 1.25 | 1.0 | 5/16 | 7.94 | 18 | 24 | 18 | ||
M12 | 1.75 | 1.5 | 1.25 | 3/8 | 9.53 | 16 | 24 | 16 | ||
M14 | 2.0 | 1.5 | 1.0 | 7/16 | 11.11 | 14 | 20 | 14 | ||
M16 | 2.0 | 1.5 | 1.0 | 1/2 | 12.7 | 13 | 20 | 12 | ||
M18 | 2.5 | 2.0 | 1.5 | 9/16 | 14.29 | 12 | 18 | 12 | ||
M20 | 2.5 | 2.0 | 1.5 | 5/8 | 15.86 | 11 | 18 | 11 | ||
M22 | 2.5 | 2.0 | 1.5 | 3/4 | 19.05 | 10 | 16 | 10 | ||
M24 | 3.0 | 2.0 | 1.5 | 7/8 | 22.23 | 9 | 14 | 9 | ||
M27 | 3.0 | 2.0 | 1.5 | 1 | 25.40 | 8 | 12 | 8 | ||
M30 | 3.5 | 3.0 | 2.0 | |||||||
(5) Half angle of thread profile (α/2): the included angle between the flanks and the vertical line of the thread axis, the half angle of ordinary thread profile is 60O/2, and the half angle of Webster's thread (BSW) thread profile is 55O/ 2. Generally, the angle of the tooth of the wood screw is 60O, and the angle of the tail tip is 60O.
(6) Thread screwing length: the length of the two-phase matching thread, which is the length of the mutual screwing part along the thread axis.
