Metric common thread

1 metric common thread with a capital M , said tooth type angle 2α = 60 ° (α represents tooth-type half-width ) ;2 Metric thread according to the pitch of ordinary coarse thread and fine Hydraulic pipe fittingsthread two kinds ;2.1 coarse thread pitch mark is generally not indicated , expressed as M20 coarse thread ; fine thread pitch mark must be marked as M30 × 1.5 represents fine thread , where the pitch is 1.5 .2.2 The common thread for the connection between mechanical parts and fastening , multi- threaded connections generally coarse thread , fine thread diameter than the same nominal strength slightly coarse thread , self-locking performance is better.3 Metric common thread tag : M20-6H, M20 × 1.5LH-6g-40, where M denotes metric common thread , 20 represents the thread nominal diameter of 20mm, 1.5 represents pitch , LH represents L , 6H, 6g represent thread accuracy class , uppercase accuracy class code represents the internal thread , lowercase accuracy class code represents external thread, 40 denotes screwing Length ;