Threads are classified into triangular threads, rectang […]
Threads are classified into triangular threads, rectangular threads, trapezoidal threads and serrated threads according to their cross-sectional shape (tooth profile). Among them, triangular threads are mainly used for connection (see thread connection), and rectangular, trapezoidal and sawtooth threads are mainly used for transmission.
In mechanical drawing, the view drawing of threads and threaded fasteners is more complicated. In order to improve the efficiency of drawing, the prescribed drawing method is usually adopted. The international standard ISO and the Chinese mechanical drawing standard both stipulate: the thread crest should be thick solid line, the drawing method of the thread and the threaded fastener
Indicates that the bottom of the tooth is represented by a thin solid line. In the view of the projection plane perpendicular to the thread axis, the thin solid line representing the bottom of the tooth is drawn only 3/4 circle, and the end limit of the thread is represented by a thick solid line. The thread type, diameter, pitch... etc. are indicated by the thread code in the dimensioning. In the sectional view of the assembly drawing, threaded fasteners are required to be drawn without sectioning, and a simplified drawing method is provided for common threaded fasteners. For example, a set of fasteners such as hexagon head bolts, hexagon nuts and washers can be drawn according to The drawing method in the picture is drawn.
German standard screw thread measurement:
1. For general standard threads, thread ring gauges or plug gauges are used to measure.
2. The thread micrometer is used to measure the pitch diameter of the thread. The method of measuring the pitch diameter of the thread with a needle can also be called the three-needle method.
3. Tooth thickness vernier caliper is used to measure the pitch diameter of the trapezoidal thread and the pitch diameter of the worm.
4. Special measuring tools and instruments for measuring other parameters.
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