Basic knowledge of common thread

2, thread identification③ Discrimination of thread typesGenerally first observe its tooth type, the ordinary thread of the tooth type is generally triangular, the top of the tooth and the bottom of the tooth has a small plane, the tooth Angle is 600; 55 brown seal pipe thread is 55° triangle, the top and bottom of the teeth are round; The tooth Angle of the 550 sealed pipe thread is the same as that of the 55 unsealed pipe thread, but the imaginary cone tangent to the crown of the external thread or the bottom of the internal thread is 1:16 taper, and the diameter at the end of the thread is small and the diameter at the end of the thread is large; The shape and Angle of the 600 taper pipe thread are the same as that of the ordinary thread, but the imaginary cone that is tangent to the top of the external thread or the bottom of the internal thread is 1:16 taper, the same as that of the 550 seal pipe thread; The tooth type Angle of trapezoidal thread and serrated thread is consistent with its name. Therefore, as long as the characteristics of various threads are grasped, they can be identified smoothly, and if possible, thread gauges can be used to measure them to help them identify correctly.② Determination of screw pitchMeasuring tools: steel ruler or vernier caliper;Measuring method: the external thread is measured directly with a steel ruler, as far as possible is a multi-tooth measurement, such as a measurement of 4 teeth, 5 teeth, 8 teeth, or even 10 teeth, a measurement of the number of teeth, measured the more accurate the pitch. Internal thread measurement is relatively difficult, it is best to use chalk or waste paper to print out the shape of the thread after the measurement is more accurate.Chapter 7 Tapping the thread1. TapTap is a tool for processing internal threads, which is divided into two kinds of hand tap and machine tap. According to the tooth type can be divided into ordinary thread tap, cylindrical pipe thread tap and taper thread tap. Ordinary thread tap is divided into coarse teeth and fine teeth two kinds.