thread is the ornate spiral with a constant pitch, deposited on a cylindrical or conical surface.It is a key element to connect two types of fasteners and screw and toothed helical gears.The main parameters of the threads on modern Fasteners defined in GOST 11708-82: it is the thread pitch between adjacent turns of the outer and inner diameters of the fastener elements, the angle of the top of the thread.
types of threads on the fasteners are divided into:
- internal - applied to the nut, sleeve anchors, couplings, pipe;
- external - located on screws, screws, screws, bolts, studs.
The following types of thread at the appropriate STATE:
- metric - a profile in the form of an equilateral triangle (sometimes with small, medium and large steps);
- inch - a triangular or trapezoidal shape;
- metric conical - has a triangular profile;
- round - the top of the ledge round shape;
- trapezoidal - the top of the ledge trapezoidal shape;
- resistant - asymmetrical trapezoidal profile;
- modular - trapezoidal profile;
- pipe bevel (profile has the form of an isosceles triangle with rounded inch size (or ploskosrezannoy) peaks and troughs round);
- conical inch - profile with ploskosrezannoy apex of the triangular shape.
There are also these types of threads, like a square and rectangular.They are applied to fasteners lathes for individual drawings.These kinds of threads do not provide a high degree of accuracy, so used rarely.They do not exist guests.
Today for engineering application basic outer and inner thread metric is considered.In the drawings, it is denoted by a capital letter "M" indicating the outer diameter in millimeters.Pipe thread types are used to connect different pipes.Their nominal diameter is the internal diameter of the tubes, the outside of which is threaded.In the drawings, it is denoted by a capital letter «G» with said inner pipe diameter in inches.
main thread sizes are all types of reference data.They can be found in any reference mechanic.For metric thread reference data are described in detail according to GOST 9150-81, 24705-81 and 8724-81.For cylindrical pipe thread sizes specified in GOST 6357-81.
One common fasteners with metric thread is a bolt.It is a metal rod with a head at one end.Along the length of the rod coated spiral groove.Purpose bolts - the connection of different parts of the mechanisms and structures with a nut.The head of the bolt is hexagonal and shaped (secret, semicircular, butt, BS, terminal).
The following types of bolts intended:
- furniture - used to connect products in the furniture industry;
- mechanic - used in industries value;
- plowshare - are designed to grip the equipment of machines in the agricultural sector;
- road - used to connect a variety of metal structures and guardrails.
