What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The research on rivet nuts started in the 1970s in my country and is still in the design and development stage. In the mid-1980s, equipment for the production of blind rivets was introduced from abroad, but no rivet nut has been produced so far. After the inventor's search, no low-carbon steel rivet nut was found to be publicly used.
Rivets for blind holes, including a cap head and a hole post, the cap head is fixed on one end face of the hole post, a tip is formed on the other end face of the hole post, and the end of the hole post close to the cap head is along its side circumference An annular groove is formed concave inward. After the hole column of the blind hole is placed in the blind hole position of the metal piece, the tip of the end face of the hole column is squeezed into the metal material under the end face of the hole column under the action of external force, and the metal material on the side of the hole column is also affected by the hole. The extrusion of the side of the column makes part of the metal material completely squeezed into the annular groove, so that the annular groove is filled more firmly, and at the same time, the tip is squeezed into the metal material, which can double-position the rivet. Therefore, the self-riveting of the rivet is realized. The rivet also has the advantages of simple structure, simple and fast installation, and no cracking caused by impact and other undesirable phenomena.
The standard specifies hexagon head bolts with thread specifications of M3~M64, grades A and B. Grade A is used for bolts with D<=24 and L<=10D or L<=150mm (whichever is smaller); grade B is used for bolts D > 24 or L > 10 D or L > 150 (according to the smaller value) bolt size specification mark: thread specification D = M12, nominal length L = 80mm, performance level is 8.8, the table is the same as oxidation, A level Hexagon head bolt tag example bolt GB / T5782-86-M12 × 80 national standard common hex bolt head on the side size and cooperation national standard wrench thread diameter \ pair of edge sidewalls Skin wrench Wrench Double-ended open-end wrench Double-ended Torx wrench. The outer hexagon bolt is the most frequently used type of bolts. The main function of the external thread it has is to cooperate with the nut. Using this threaded connection method, the two parts are integrated. Grade C hexagon bolts are mainly used in steel structure machinery and equipment with relatively rough surface and low precision requirements. Grade A and Grade B hexagon bolts are mainly used in machinery and equipment with smooth surface and high precision requirements. Most of the stainless steel outer hexagon screws are full-tooth and hexagonal head full-tooth bolts. Standard: DIN933, GB5783, ISO4017, ANSIB18. 2.1, JISB1180; non-full thread bolt standards DIN931, GB5782, ISO4014, ANSIB18.2.1, JISB1180.
Welding stud is also called welding screw, which belongs to a kind of fastener connected with high strength and rigidity. Welding stud is the abbreviation of cylindrical head welding stud for arc stud welding. Industrial plant construction, highways, railways, bridges, towers, automobiles, energy, transportation facilities, airports, stations, power stations, pipeline supports, lifting machinery and other types of steel structures and other projects.
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