Anti-loose internally threaded fastener

Abstract

The invention relates to an anti-loose internally threaded fastener, which comprises an internal thread substrate, and is characterized in that the shape of an internal thread arranged on the internal thread substrate is as follows: the oblique angle of an internal thread profile is 38 degrees to 40 degrees, the intermediate diameter D2 = D-(0. 42 to 0.43) P, the variable angle inflection point diameter phiD = D-(0.48 to 0.50)P, the minor diameter D1 = D-(0.90 to 0.91) P, the theoretical interference width is 0.12B, the theoretical interference height is 0.22Td, the failure theoretical distance is 0.098P, the intermediate diameter position is 0.215P, and the inflection point position is 0.24P. By improving the design parameters of the thread, and connecting the internal thread with six-level machining precision and an ordinary external thread with six-level machining precision, the mechanical properties of a thread pair are greatly improved, the contact stress of the thread pair is reduced, the plastic deformation of an external thread profile crest zone is reduced, the overloading assembly ability is strong, the anti-loose reliability is good, no interference occurs in a limit size state, the rotation following phenomenon is avoided, and the assembly quality and efficiency are high.

Description

technical field [0001] The invention relates to the field of fasteners, and is an anti-loosening internal thread fastener that can be widely used in the industries of automobiles and engineering machinery. Background technique [0002] Chinese Patent Publication (Announcement) No. CN202560774U discloses the applicant's utility model patent titled "Lock-proof Internal Thread Fastener". This anti-loosening internal thread fastener is set on the internal thread base with the shape of the internal thread as the middle diameter D 2 =D-0.416P, bevel corner diameter φD=D-0.4646P, small diameter D 1 =D-0.85P, the theoretical interference width is 0.25B, the theoretical interference height is 0.25Td, the theoretical failure distance is 0.090P, the bevel angle of the internal thread profile X=36°, where: P is the pitch, B is the external thread Top width, Td is the major diameter tolerance of external thread, TD 2 is the pitch diameter tolerance of the internal thread. The pitch d...

AI Technical Summary

Problems solved by technology

However, in the process of use, it has been found that interference occurs in the state of limit size, and there are some cases of follow-up, which affect the quality and efficiency of assembly. There are design parameters that are not reasonable enough. Without more precise consideration, it is necessary to have reliable anti-loosening performance and also It is necessary to reduce the contact stress, reduce the plastic deformation of the tooth top of the external thread, and then improve the strength of the internal thread. Under the condition of constant assembly torque, a larger initial axial force can be obtained, which is more suitable for the characteristics of the assembly line of the automobile and construction machinery industries.

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