Service HotlineIn general, the size, mechanical properties and working performance requirements of self-tapping screws have the following standards: 1. Self-tapping screw size standard ASME B18.6.3 2010 standard not only introduces the dimensions of slotted and cross-recessed self-tapping screws and metal drive screws, but also includes the mechanical properties and work performance requirements of carbon steel self-tapping screws. The appendix gives instructions for measuring the various dimensions and application guidance on clamping lengths and test apertures. 2. Self-tapping screw performance standards (including mechanical properties and work performance): (1) SAE J933: Introduces the mechanical performance and work performance requirements of carbon steel ordinary self-tapping screws and white-cut self-tapping screws. The requirements for selection of raw materials, heat treatment, depth of carburized layer, surface hardness, and core hardness are further specified. (2) SAE J81: The mechanical properties and working performance of self-extrusion self-tapping screws (self-tapping locking screws) are introduced. (3) SAE J78: The mechanical properties and working properties of self-drilling and self-tapping screws are introduced. (4) IFl-113: The mechanical properties and working properties of self-drilling and self-tapping screws are introduced. (5) ASTM C1513: Introduces the mechanical properties and performance requirements of carbon steel self-tapping screws. For other special types of self-tapping screws, there is no corresponding national or industrial standard, and no data for self-tapping screws made of other metal materials other than carbon steel have been recognized. For technical data on these self-tapping screws, you can check with the manufacturer.
Commonly used national standard GB41Ⅰ type hexagon nut——C grade GB6170Ⅰ type hexagonal nut——, B grade GB6171Ⅰ type hexagonal nut-fine thread-, B grade GB6172 hexagonal thin nut——, B grade - chamfering GB6173 hexagonal thin nut—— Fine thread—, B grade GB6174 hexagonal thin nut—B grade—without chamfering
1. Material strain hardening When the material is cyclically loaded, the phenomenon of cyclic strain hardening or cyclic strain softening will occur, that is, under the condition of constant cyclic strain, the stress amplitude will increase or decrease with the increase of the number of cycles. . After several cycles, the stress amplitude enters a cyclic steady state. The low-cycle fatigue of the lock nut is carried out under the condition that the strain is constant, and the strain hardening or softening of the threaded piece will affect the size of its maximum unscrewing torque. The alloy steel used to make the lock nut is a cyclic strain hardening material, and the hardening of the material will increase the elastic restoring force FN of the threaded sheet and increase the unscrewing torque.
As one of the indispensable parts in automobiles, the main function of the screw is to fix the parts with through holes and the parts with screw holes together. The existing automobile screws include a screw rod and a head, and the thread pitches on the screw rod are equal. , When in use, directly screw the screw into the screw hole, so as to connect and fix the two parts, this connection method, however, when the screw has different thread spacing or part of the thread is damaged, the thread cannot be repaired and replaced. Then the whole screw will be scrapped.
A nut provided by Yueluo. The nut is in the shape of a sleeve and has a threaded section inside. An annular groove is set on the inner wall of one end of the threaded section. The notch of the groove points to the hole core. The hole diameter at the groove notch at the front end is larger than the nominal size of the thread segment or the hole diameter at the groove notch at the rear end in the screwing direction is smaller than the nominal size of the thread segment.
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