What is the structural classification of the threaded elements of the barrel mandrel?

Time:2021-12-20

Cylinder mandrel threaded elementWhat is the structural classification?

Cylinder mandrel thread elements are divided into triangular thread, rectangular thread, trapezoidal thread and sawtooth thread according to their cross-sectional shape (profile). The triangular thread is mainly used for connection (see thread connection), and the rectangular, trapezoidal and serrated threads are mainly used for transmission. Threads distributed on the outer surface of the parent body are called external threads, and those on the inner surface of the parent body are called internal threads. The thread formed on the cylindrical matrix is called the cylindrical thread, and the thread formed on the conical matrix is called the conical thread. The thread is divided into two kinds of left and right according to the spiral direction, and the right-handed thread is generally used. Threads can be divided into single-wire and multi-wire, and most of them are single-wire connections. When it is used for transmission, it requires fast lifting or high efficiency. Double or multi-wire is adopted, but generally it does not exceed 4 wires.

Triangular thread is mainly used for connection, rectangular, trapezoidal and zigzag thread is mainly used for transmission. According to the spiral direction, it is divided into thread and right-handed thread, and right-handed thread is generally used. According to the number of spirals, it is divided into single thread, double thread and multi-thread. The connection is mostly single thread, and the transmission is double or multi-thread. According to the size of the tooth, it is divided into coarse thread and fine thread, it can be divided into fastening thread, pipe thread, transmission thread, special thread, etc.

The triangular thread in the cylindrical thread has good self-locking performance. It is divided into thick teeth and fine teeth two general connection using thick tooth thread. The fine tooth pitch is small, the rising angle is small, the self-locking performance is good, and it is often used in the vibration or variable load connection and precision adjustment device of the small parts of the thin-walled tube. Pipe threads are used for tight connections. Rectangular threads have high efficiency, but because they are not easy to grind, internal and external threads are difficult to fix, and trapezoidal threads are often used instead. The working side of the serrated thread is close to the straight side of the rectangle and is usually used to withstand uniaxial forces.

The tapered thread is triangular. Mainly used for pipe fittings, because the thread deformation, to ensure the tightness of the thread pair.

According to the sealing is divided into a sealed thread and non-sealed thread.

Cylinder mandrel threaded elementWhat is the standard drawing method?

In mechanical drawing, the view drawing of threads and threaded fasteners is very complicated. In order to improve the drawing efficiency, the prescribed drawing method is usually used (see figure). Both the international standard iso and the Chinese mechanical drawing standard stipulate that the top of the thread is represented by a thick solid line, and the bottom of the thread is represented by a thin solid line. On the projection plane perpendicular to the thread axis, the thin solid line at the bottom of the thread is represented by only 3/4 circle, and the thread termination limit is represented by thick solid line. Thread type, diameter, pitch, etc., are marked with thread code in the dimensions. In the sectional view of the assembly drawing, all fasteners with specified threads are drawn as uncut parts. For ordinary threaded fasteners, a set of hexagon head bolts, hexagon nuts and washers can be drawn as shown in the figure. A simplified drawing method is provided.


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