Anti-fatigue hexagonal round nut

Abstract

The utility model discloses an anti-fatigue hexagonal round nut, and relates to the technical field of nut connecting pieces. The nut comprises a regular hexagonal structural section and a cylindrical structural section which are integrally formed in a hot forging mode, the regular hexagonal structural section and the cylindrical structural section are coaxially arranged, six transition conical surfaces are arranged on the outer side between the regular hexagonal structural section and the cylindrical structural section, the dip angle of each transition conical surface is 55 degrees, and the length of an inner chamfer at the front end of the cylindrical structural section is 8 mm. The anti-fatigue hexagonal round nut is of an appearance structure with the upper portion and the lower portion being round, the regular hexagonal structural section on the upper portion of the nut is used for being wrenched by a wrench, the cylindrical structural section on the lower portion of the nut increases the area of a nut supporting face, a gasket can be replaced, pre-tightening force loss in the installation process is reduced, and the service life of the nut is prolonged. The accuracy of the pre-tightening force and the mounting quality during actual mounting are ensured; the transition conical surface is adopted to eliminate stress concentration at two structural change positions of the regular hexagonal structural section and the cylindrical structural section, and the anti-fatigue performance of the nut is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of nut connecting pieces, in particular to an anti-fatigue hexagonal round nut. Background Art

[0002] A large number of failure analyses of bolt / stud and nut connections have shown that fatigue fracture of bolts / studs is the main failure mode, accounting for 60-80%. Further inspection of the broken bolts or studs revealed that the fractured part is usually at the first thread after the bolt or stud is screwed into the nut (such as Figure 1 ), accounting for about 65-70%.

[0003] Comprehensive analysis shows that the reason for fatigue failure of bolts or studs is that there is alternating stress in the first thread after the bolt / stud is screwed with the nut, which causes local damage to the thread. The alternating stress continues, and the local damage forms cracks. The cracks further expand until they break and fail. On the other hand, bolt / stud joints are usually installed by torque method, applying torque on the nut. A set of standard bolt / stud joints includes a bolt / stud, a nut, and two washers (such as Figure 2 ).

[0004] The torque coefficient is calculated as follows:

[0005]

[0006] Where:

[0007] K is the torque coefficient;

[0008] T is the Schneider torque (peak value), in Newton meters (N·m);

[0009] P is the bolt pretension (peak value), in kilonewtons (kN);

[0010] d is the nominal thread diameter of the bolt, in millimeters (mm).

[0011] Since there are many factors affecting the torque coefficient K, over-tightening and under-tightening often occur at the installation site, which will affect the fatigue resistance of the bolts / studs and thus affect the safety of the equipment. Utility Model Content

[0012] The utility model aims to provide an anti-fatigue hexagonal round nut to solve the problems raised in the above background technology.

[0013] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0014] A fatigue-resistant hexagonal round nut comprises a regular hexagonal structure section and a cylindrical structure section integrally formed by hot forging, the regular hexagonal structure section and the cylindrical structure section are coaxially arranged, and six transition cone surfaces are provided on the outer sides between the regular hexagonal structure section and the cylindrical structure section.

[0015] Furthermore, the inclination angle of the transition cone is 55°.

[0016] Furthermore, the inner chamfer length of the front end of the cylindrical structure segment is 8 mm.

[0017] Furthermore, the outer diameter of the cylindrical structure segment is the same as the diameter of the geometric circumscribed circle of the regular hexagonal structure segment.

[0018] Furthermore, the surfaces of the regular hexagonal structure segment and the cylindrical structure segment are covered with an anti-corrosion coating.

[0019] Compared with the prior art, the utility model has the following beneficial effects:

[0020] 1. The fatigue-resistant hexagonal round nut of the utility model has an outer shape structure with an upper part and a lower circle. The regular hexagonal structural section on the upper part of the nut is used for tightening with a wrench, and the cylindrical structural section on the lower part of the nut increases the area of ​​the nut support surface. In this way, when the nut is installed with a bolt or a stud, the cylindrical structural section on the lower part of the nut replaces the washer, and there is no need to use a washer under the nut support surface, thereby reducing the friction between the washer and the nut, and between the washer and the connected part, thereby reducing the preload loss during the installation process of the bolt / stud and nut connection pair, and ensuring the accuracy of the preload and the installation quality during actual installation.

[0021] 2. The outer sides of the regular hexagonal structural section and the cylindrical structural section of the anti-fatigue hexagonal round nut of the utility model adopt transition cone surface transition, which eliminates the stress concentration at the place where the two structures change, and improves the anti-fatigue performance of the nut.

[0022] 3. The inner chamfer length of a standard nut is less than 1 mm, while the inner chamfer length of the fatigue-resistant hexagonal round nut of the utility model is 8 mm, which makes the first thread of the nut move backward, reduces the stress on the first thread of the bolt or stud at the nut support surface, and improves the fatigue resistance of the bolt / stud and nut connection pair. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram of the fracture failure location of the existing bolt connection pair;

[0024] Figure 2 It is a schematic diagram of a standard bolt connection substructure;

[0025] Figure 3 It is a half-section front view of an anti-fatigue hexagonal round nut of the utility model;

[0026] Figure 4It is a top view of an anti-fatigue hexagonal round nut of the utility model;

[0027] Figure 5 It is a structural schematic diagram of a connection pair consisting of a fatigue-resistant hexagonal round nut and a bolt of the utility model;

[0028] In the figure: 1-bolt, 2-nut, 3-first thread, 4-transition point between the bare rod and the thread, 5-transition fillet between the bolt head and the screw rod, 6-first washer, 7-second washer, 8-regular hexagonal structural section, 9-cylindrical structural section, 10-transition cone, 11-inner chamfer. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0030] It should be understood that the orientations or positional relationships indicated by the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0031] It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected or set, or detachably connected or set, or integrally connected or set. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0032] like Figure 1 As shown, the fracture failure sites of the existing bolt 1 connection pair are mainly at the first thread 3 after the bolt 1 or stud is screwed with the nut 2, accounting for about 65%; there is also the transition point 4 between the bare rod and the thread, accounting for about 20%; and the transition fillet between the bolt 1 head and the screw rod, accounting for about 15%.

[0033] like Figure 3 and 4As shown, this embodiment provides an anti-fatigue hexagonal round nut 2, including a regular hexagonal structure segment 8 and a cylindrical structure segment 9 integrally formed by hot forging, the regular hexagonal structure segment 8 and the cylindrical structure segment 9 are coaxially arranged, and there are six transition cone surfaces 10 on the outer side between the regular hexagonal structure segment 8 and the cylindrical structure segment 9.

[0034] Specifically, the inclination angle of the transition cone surface 10 is 55°, the length of the inner chamfer 11 at the front end of the cylindrical structure segment 9 is 8 mm, the outer diameter of the cylindrical structure segment 9 is the same as the diameter of the geometric circumscribed circle of the regular hexagonal structure segment 8, and the surfaces of the regular hexagonal structure segment 8 and the cylindrical structure segment 9 are covered with an anti-corrosion coating.

[0035] like Figure 2 The length of the inner chamfer 11 of the standard nut 2 used in the standard bolt 1 connection pair is less than 1 mm, while the length of the inner chamfer 11 at the front end of the cylindrical structure section 9 in this embodiment is 8 mm, so that the first thread of the nut 2 is moved backward, reducing the stress on the first thread of the bolt 1 or stud at the supporting surface of the nut 2, and improving the fatigue resistance of the bolt 1 / stud and nut 2 connection pair.

[0036] In this embodiment, the transition cone surface 10 provided between the regular hexagonal structure segment 8 and the cylindrical structure segment 9 eliminates the stress concentration at the location where the two structures change, thereby improving the fatigue resistance of the nut 2 .

[0037] like Figure 5 As shown, when the anti-fatigue hexagonal round nut 2 of the utility model is installed in combination with the bolt 1 or the stud, the lower cylindrical structure section 9 of the nut 2 replaces the second washer 7, and the second washer 7 is not needed under the supporting surface of the anti-fatigue hexagonal round nut 2, thereby reducing the preload loss during the installation of the connection pair of the bolt 1 / stud and the nut 2 and ensuring the installation quality.

[0038] The manufacturing process of the fatigue-resistant hexagonal round nut 2 of the utility model is: sawing material→hot forging→cutting processing→heat treatment→thread processing→surface anti-corrosion treatment.

[0039] Example 1: Shanxi Jinneng Shouyang Lingzhi Phase II 140MW wind power project, fatigue-resistant hexagonal round nuts M36: 4032 pieces; M45: 3136 pieces; manufacturing number: 2023-6-238.

[0040] Example 2: Datang Harbin Binxian 150MW project, fatigue-resistant hexagonal round nuts M36: 3456 pieces; M45: 2688 pieces; manufacturing number: 2023-6-155.

[0041] Example 3: Lingshan Phase I Wind Power Project of Lingshan Branch of SDIC Guangxi Wind Power Co., Ltd., fatigue-resistant hexagonal round nuts M36: 8512 pieces; M48: 6832 pieces; manufacturing number: 2023-6-129.

[0042] Based on the embodiments of the present utility model, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present utility model.

Claims

1. A fatigue-resistant hexagonal round nut, characterized in that: It comprises a regular hexagonal structure section and a cylindrical structure section which are integrally formed by hot forging. The regular hexagonal structure section and the cylindrical structure section are coaxially arranged, and six transition cone surfaces are arranged on the outer sides between the regular hexagonal structure section and the cylindrical structure section.

2. The anti-fatigue hexagonal round nut according to claim 1, characterized in that: The inclination angle of the transition cone is 55°.

3. The anti-fatigue hexagonal round nut according to claim 1, characterized in that: The inner chamfer length of the front end of the cylindrical structure section is 8 mm.

4. The anti-fatigue hexagonal round nut according to claim 1, characterized in that: The outer diameter of the cylindrical structure segment is the same as the diameter of the geometric circumscribed circle of the regular hexagonal structure segment.

5. The anti-fatigue hexagonal round nut according to claim 1, characterized in that: The surfaces of the regular hexagonal structure section and the cylindrical structure section are covered with an anti-corrosion coating.

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