/ / Threaded connections and their types

Threaded connections and their types

The screw connections from the outer and outerthe internal surface of the arrangement. They are internal, external, conical and cylindrical. There are different sections and sections: round, rectangular, thrust, trapezoidal. The appointment is running or fastening.

Mounting has a triangular profile and is divided into two groups: inch and metric.

Threaded connections
The inch threaded connection is measured in inches (hence the name), the pitch is 25.4 mm. Characterized by the number of threads of the screw-like line per inch of the cut piece.

Inch are used to connect pipes(called "pipe threads"). Also used for cutting on spare parts of various equipment. In machines that are manufactured in our time, inch carving is not used. The standards are designed for metric, so the design is carried out under this standard.

Threaded connections with threaded threadsThey are used for heavy loads. Trapezoidal serve as a fastener when transmitting motion (propellers) and forces, but do not produce rigid fastening of parts. For the valves use round thread, in machines it is used extremely rarely.

With a triangular profile, threaded connections are the most reliable, even with

Tightening torque of threaded connections
of the same diameter.Stubborn is less durable. Even less reliable thread will be trapezoidal, the weakest - rectangular. Due to the smooth rounding, the round has a high dynamic strength.

Threaded joints are divided into groups: screw, combined, bolt and hairpin.

The simplest joints consist of a nut and a screw.

In order to avoid self-loosening in the joints, stopping parts are used, which soften vibration and shock loading, reduce friction.

In the manuals, there are many ways to stop self-loosening.

Threaded connections for the car are madeusing bolts made of carbonaceous metal. In the fasteners, which require increased reliability and durability, alloyed chromium steel is used. At the moment of tightening the threaded joints, a dynamic key is used (stress load moments are normalized). Such keys are used in mechanisms where the strength of the connection is strictly defined in the technical documentation.

Calculation of threaded connections
Screw connections are first clamped, then loosen a little and then tighten again. So the correctness of the clamping force is controlled.

Calculation of threaded joints is done to determine the voltage that occurs in the connection. Also you need to calculate the safety factor for the bolts used.

The calculation is carried out according to the elements:

- without nut and with nut;

- with eccentric and concentric loads;

- with a pin;

- the contact zone is determined by the geometry of the thread;

- if many parts of the shafts are cylindrical;

- with a lot of plates.

In the calculations, only statistical loads are used.

Threaded connections are good because they can always be disassembled without damaging the parts themselves.