Service HotlineThe lifting ring screws are generally not surface treated, but according to the requirements, surface treatment such as galvanized passivation and chrome plating can be carried out, and it is specified in GB5267-85. The chemical composition and mechanical properties of the material should be treated immediately after electro-galvanizing. The test methods are specified in GB699. During routine inspection, the grain size test may not be advanced, and the grain size test method shall be in accordance with the provisions of YB27. Thread inspection is performed with thread gauges and smooth limit gauges or universal energy tools.
Screws and nuts, as the most commonly used fastening devices, have the defect that they may loosen and fall off, especially those in a long-term vibrating environment are more likely to loosen and fall off. Additional anti-off parts such as anti-off washers and anti-off caps are added, so that an extra anti-off part is used in the fastening process, and these anti-off parts are sometimes difficult to find when they are not always needed and are inconvenient to use.
The general nut will loosen itself due to vibration and other reasons during use. In order to prevent this phenomenon, the self-locking nut was invented. The main functions of self-locking nuts are anti-loose and anti-vibration. For special occasions. Its working principle is generally self-locking by friction. The types of self-locking nuts classified by function include those with nylon rings, those with neck closures, and those with metal anti-loosening devices. They are all effective torque type lock nuts (refer to GB/T3098.9-2002 national standard)
In the fastening connection parts and parts assembly of various equipment and tooling, if the screw and nut anti-loosening treatment is required, there is a contradiction between anti-loosening and tightening or tightening and loosening. For example, the resistance is large when tightening. , or the resistance is large when loosening, or the anti-loosening effect is not good, or the service life is short, and it will be scrapped after 2 to 3 times of use. In a word, all kinds of anti-loosening nuts have the above problems at present. Therefore, it is necessary to utilise a new type of anti-loosening nut with low resistance when tightening or loosening, but with better anti-loosening effect and long service life.
The self-tapping locking screw is a series of coarse thread and ordinary thread, and the thread size is M3~M12mm. The threaded rod of the self-tapping locking screw is a thread with an arc-shaped triangular section. The screw is surface hardened and can be screwed into a prefabricated hole of black or non-ferrous metal material (which can be made by drilling, punching or die casting), and extruded to form an internal thread. The threaded rod portion can be made into a cylindrical or triangular shape with a diameter equal to or less than the circumscribed circle. Self-tapping locking screws have low screw-in torque and high locking performance. The varieties of self-tapping locking screws in the product standard of Chinese commodity fasteners include GB/T6560 (cross-recessed pan head), GB/T6561 (cross-recessed countersunk head), GB/T6562 (cross-recessed half-sunk head), GB/T6563 ( Hexagon head), GB/T6564 (hexagonal flower-shaped cylindrical head) five series. Self-tapping locking screws are generally fastened with pneumatic or electric screwdrivers. Most of the automotive industry uses hexagonal head, cross recessed pan head and hexagonal socket head self-tapping locking screw with high fastening efficiency.
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