A forming method for non-standard nuts

Abstract

The present invention discloses a method for forming a non-standard nut, comprising the steps of: fixing a bolt on a first connected part, wherein the connecting thread of the bolt is located on a side close to the second connected part; stretching the bolt with a theoretical axial preload; obtaining the axial cross-sectional geometric parameters of the bolt at the connecting thread; determining the thread geometric parameters of the non-standard nut according to the axial cross-sectional geometric parameters of the connecting thread; and processing the non-standard nut according to the thread geometric parameters. Non-standard nuts are applied to thread fastening, which improves the adverse effect of poor uniformity of stress distribution of metric thread connection on its connection performance, solves the problem that the connection pair is prone to failure due to the concentrated bite force of the thread teeth in the existing metric thread connection, and improves the strength and fatigue resistance of the connection pair. The non-standard nut has better strength and mechanical reliability, and the connection strength of the bolt pair is improved.

Description

Technical Field

[0001] The invention relates to the technical field of non-standard fasteners, and in particular to a molding method for non-standard nuts. Background Art

[0002] The connection between nuts and bolts is one of the most commonly used fastening methods. When ordinary nuts and bolts are used to fix mechanical parts, the thread bite force tends to be concentrated in the 1st to 3rd thread area of ​​the thread near the fitting surface under the action of the preload. The resulting higher stress amplitude makes it easy for the fasteners to break and fail at this position during the operation of the machine, or causes the fasteners to lose too much preload under long-term service conditions and cause the connected parts to slip and fail. The mechanical properties of fasteners are not only related to the reliability of the product, but also to the production cost and maintenance cost. In order to solve the above-mentioned related technical problems, it is necessary to develop a non-standard nut.

[0003] In summary, how to effectively solve the problem that the connection pair is prone to failure due to the concentrated bite force of the thread in the existing metric thread connection is an issue that the technicians in this field urgently need to solve. Summary of the invention

[0004] The purpose of the present invention is to provide a method for forming a non-standard nut, which solves the problem that the connection pair is prone to failure due to the concentrated bite force of the thread teeth in the existing metric thread connection, and improves the fatigue resistance of the connection pair.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for forming a non-standard nut comprises the following steps:

[0007] Fixing a bolt on the first connected member, wherein the connecting thread of the bolt is located on a side close to the second connected member;

[0008] stretching the bolt with a theoretical axial preload;

[0009] Obtaining axial cross-sectional geometric parameters of the bolt at the connecting thread;

[0010] Designing the thread geometry parameters of the non-standard nut according to the axial cross-section geometry parameters of the connecting thread;

[0011] The non-standard nut is processed according to the thread geometric parameters.

[0012] Optionally, in determining the thread geometric parameters of the non-standard nut according to the axial cross-sectional geometric parameters of the connecting thread, the axial cross-sectional geometric parameters are the same as the thread geometric parameters.

[0013] Optionally, after the non-standard nut is processed, the process of connecting the non-standard nut to the bolt includes:

[0014] Screw the non-standard nut onto the bolt through the thread;

[0015] Stretching the bolt with an actual axial preload, wherein the actual axial preload is equal to the theoretical axial preload;

[0016] Maintain the actual pre-tightening force and tighten the non-standard nut to fit the second connected member.

[0017] Optionally, the bolt is a single-head bolt having a bolt head or a stud bolt with a fastening nut connected to one end.

[0018] Optionally, fixing the bolt to the first connected member includes:

[0019] Screw the bolt head of the bolt into the thread of the first connected member, or fit the fastening nut to the end surface of the first connected member;

[0020] The end surface of the bolt head or the fastening nut is welded to the first connected member.

[0021] Optionally, before the non-standard nut is screwed onto the bolt through threads, the method further includes: connecting a gasket to the bolt.

[0022] The forming method of the non-standard nut provided by the present invention comprises the following steps: fixing a bolt on a first connected member, wherein a connecting thread of the bolt is located on a side close to a second connected member; stretching the bolt with a theoretical axial preload force; obtaining axial cross-sectional geometric parameters of the bolt at the connecting thread; determining thread geometric parameters of the non-standard nut according to the axial cross-sectional geometric parameters of the connecting thread; and processing the non-standard nut according to the thread geometric parameters.

[0023] By applying the technical solution provided in the embodiment of the present invention, non-standard nuts are used in threaded fastening, which improves the adverse effect of poor stress distribution uniformity of metric threaded connections on their connection performance, solves the problem that the connection pair is prone to failure due to concentrated bite force of the thread teeth in existing metric threaded connections, optimizes the distribution of loads between threaded connection pairs, obtains a more reasonable stress distribution of the threaded connection, improves the stress condition of the threaded connection, improves the strength and fatigue resistance of the connection pair, and provides more reasonable suggestions for the design optimization of threaded fasteners; the non-standard nut has better strength and mechanical reliability, and its maintenance friendliness after mass production can reduce the overall cost; the connection strength of the bolt pair is improved, and the interface size of the connected parts can be optimized, thereby achieving design cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A flowchart of a method for forming a non-standard nut provided in a specific embodiment of the present invention;

[0026] Figure 2 A schematic diagram of bolt fixing;

[0027] Figure 3 This is a schematic diagram of bolt tension;

[0028] Figure 4 This is a schematic diagram of non-standard nut connection;

[0029] Figure 5 This is a schematic diagram of the bolt being stretched after being connected with a non-standard nut;

[0030] Figure 6 This is a schematic diagram of fastening with non-standard nuts;

[0031] Figure 7 It is a schematic diagram of the structure of non-standard nuts and bolts connecting the connectors.

[0032] The following are marked in the accompanying drawings:

[0033] Non-standard nut 1, bolt 2, bolt head 3, second connected part 4, first connected part 5, gasket 6. DETAILED DESCRIPTION

[0034] The core of the present invention is to provide a method for forming a non-standard nut, which solves the problem that the connection pair is prone to failure due to the concentrated bite force of the thread teeth in the existing metric thread connection, and improves the fatigue resistance of the connection pair.

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Please refer to Figure 1 , Figure 1 The flowchart of a method for forming a non-standard nut provided in a specific embodiment of the present invention includes the following steps:

[0037] S110: Fixing the bolt 2 to the first connected member 5, wherein the connecting thread of the bolt 2 is located at a side close to the second connected member 4;

[0038] In practical applications, the end of the bolt 2 with the connecting thread penetrates from the first connected member 5, and the connecting thread penetrates from the second connected member 4, and the connecting thread extends out of the second connected member 4. The end of the bolt 2 away from the connecting thread is fixed to the second connected member 4. At this time, the connecting thread of the bolt 2 has not yet undergone any deformation, such as Figure 2 shown.

[0039] S120: stretch bolt 2 with theoretical axial preload;

[0040] In practical applications, the magnitude of the axial tensile preload required for the bolt 2 to connect the first connected member 5 and the second connected member 4 is determined based on experience, that is, the magnitude of the theoretical axial preload is determined, and the bolt 2 is stretched from one side of the connecting thread with the theoretical axial preload Fz1 of this magnitude, and the theoretical axial preload is applied to the bolt 2, such as Figure 3 shown.

[0041] S130: Obtaining axial cross-sectional geometric parameters of the bolt 2 at the connection thread;

[0042] In practical applications, the bolt 2 produces tensile deformation under the action of the theoretical axial preload Fz1, and the geometric features of the connecting thread of the bolt 2 change under the theoretical axial preload. The axial cross-sectional geometric parameters of the bolt 2 under the theoretical axial preload are recorded, that is, the axial cross-sectional geometric parameters of the bolt 2 at the connecting thread are obtained. The axial cross-sectional geometric parameters include but are not limited to the tooth profile, tooth profile angle, pitch, lead angle, number of threads, etc.

[0043] S140: determining the thread geometric parameters of the non-standard nut 1 according to the axial cross-sectional geometric parameters of the connecting thread;

[0044] In practical applications, when the nut is fastened to the bolt 2 and the connecting thread is stretched and deformed, the thread geometry parameters of the nut match the axial cross-sectional geometry parameters of the bolt 2 after stretching, that is, the thread geometry parameters of the nut are close to or even the same as the axial cross-sectional geometry parameters of the bolt 2 at the connecting thread. Therefore, the thread geometry parameters of the non-standard nut 1 can be determined based on the axial cross-sectional geometry parameters of the connecting thread.

[0045] S150: Process non-standard nut 1 according to thread geometry parameters.

[0046] In practical applications, after the thread geometry parameters of the non-standard nut 1 are determined, the non-standard nut 1 can be processed. It should be noted that the above example takes a triangular thread as an example, but the thread design of the non-standard nut 1 should not be limited to the form of the tooth profile, including but not limited to trapezoidal, arc, rectangular, etc. The non-standard nut 1 can be freely designed to have a degree of stretching under different preloads through cylindrical parts, especially the bolt 2, to improve the thread stress condition and reduce the axial deformation of the thread according to the application conditions.

[0047] By applying the technical solution provided in the embodiment of the present invention, the non-standard nut 1 is applied to threaded fastening, which improves the adverse effect of poor stress distribution uniformity of metric threaded connections on their connection performance, solves the problem that the connection pair is prone to failure due to concentrated bite force of the thread teeth in existing metric threaded connections, optimizes the distribution of loads between threaded connection pairs, obtains a more reasonable stress distribution of the threaded connection, improves the stress condition of the threaded connection, improves the strength and fatigue resistance of the connection pair, and provides more reasonable suggestions for the design optimization of threaded fasteners; the non-standard nut 1 has better strength and mechanical reliability, and its maintenance-friendliness after mass production can reduce the overall cost; the connection strength of the bolt 2 pair is improved, and the interface size of the connected parts can be optimized, thereby achieving design cost reduction.

[0048] In one embodiment, when designing the thread geometric parameters of the non-standard nut 1 according to the axial cross-sectional geometric parameters of the connecting thread, the axial cross-sectional geometric parameters are the same as the thread geometric parameters, the connecting threads of the non-standard nut 1 and the bolt 2 are completely matched, no thread bite force concentration will occur between the metric thread connections, and the connection pair is not prone to failure.

[0049] On the basis of the above-mentioned specific embodiments, after the non-standard nut 1 is processed, the process of connecting the non-standard nut 1 to the bolt 2 may include:

[0050] Screw the non-standard nut 1 onto the bolt 2 through the thread;

[0051] The bolt 2 is stretched with an actual axial preload, and the actual axial preload is equal to the theoretical axial preload;

[0052] Maintain the actual pre-tightening force and tighten the non-standard nut 1 to fit the second connected part 4.

[0053] For ease of understanding, the above steps are combined for explanation below.

[0054] In practical applications, before applying the tensile force, the non-standard nut 1 is screwed into the cylindrical bolt 2 through the thread, such as Figure 4 shown.

[0055] Under the same working conditions as S120, the bolt 2 is stretched again. The actual axial preload Fz2 is the same as or similar to the theoretical axial preload Fz1 in S120, and the error does not exceed ±%2. Figure 5 shown.

[0056] The actual axial preload Fz2 in S120 is maintained and the non-standard nut 1 is tightened to fit the second connected part 4, and its thread is basically adapted to the changed thread geometry of the bolt 2, such as Figure 6 shown.

[0057] like Figure 7 As shown, Figure 7 The non-standard threaded connection in the installed state is shown, which is completely penetrated by the bolt 2. On the surface of the second connected part 4, non-standard nuts 1 and bolts 2 are arranged. On the surface of the first connected part 5, bolts 2 and bolt heads 3 are arranged. The non-standard nuts 1 and bolt heads 3 compress the bolts 2 from both sides of the second connected part 4 and the first connected part 5, and fix the second connected part 4 and the first connected part 5.

[0058] The non-standard nut 1 solves the problem that the connection pair is prone to failure due to the concentrated bite force of the thread teeth in the existing metric threaded connection, optimizes the distribution of loads between the threaded connection pairs, obtains a more reasonable stress distribution of the threaded connection, improves the stress condition of the threaded connection, and improves the strength and fatigue resistance of the connection pair.

[0059] In one embodiment, the above example takes the stretching method as an example, but the application of the non-standard nut 1 should not be limited to the installation form. The bolt 2 can be a single-headed bolt 2 with a bolt head 3, or a double-headed bolt 2 with a fastening nut connected to one end. There should be no restriction on the fastening form of the other end of the bolt 2 fastener, including but not limited to the bolt head 3 and the fastening threaded connection, and the scope of use is wide.

[0060] On the basis of the above embodiment, fixing the bolt 2 on the first connected member 5 includes:

[0061] Screw the bolt head 3 of the bolt 2 into the thread of the first connected member 5, or fit the fastening nut to the end surface of the first connected member 5;

[0062] The bolt head 3 or the end face of the fastening nut is welded to the first connected member 5 .

[0063] In practical applications, the bolt 2 and the first connected member 5 can be connected by threads, which is detachable and convenient to connect; they can also be connected by welding, riveting, etc., which is firm and reliable, with many connection forms and convenient connection.

[0064] On the basis of the above-mentioned specific embodiments, before the non-standard nut 1 is screwed into the bolt 2 through a thread, the process further includes: connecting the gasket 6 to the bolt 2, and the gasket 6 can increase the contact area, reduce the pressure, and protect the non-standard nut 1 and the bolt 2. Of course, connecting through the gasket 6 is only a preferred implementation, not the only one, and the gasket 6 is not necessarily required, and the connection can also be made directly without the gasket 6.

[0065] The non-standard nut 1 should not restrict the additional parts of the fastener, such as the gasket 6, nor should it restrict the structural form and size of the connecting part and the connected part, including but not limited to the hexagonal flange nut.

[0066] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0067] The above is a detailed introduction to the forming method of the non-standard nut provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. Therefore, the present invention will not be limited to the embodiments shown in this article, but will conform to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A method for forming a non-standard nut, characterized in that: Includes steps: Fixing a bolt on the first connected member, wherein the connecting thread of the bolt is located on a side close to the second connected member; The bolt is stretched with a theoretical axial preload, and the bolt is stretched and deformed under the action of the theoretical axial preload, and the geometric features of the connecting thread of the bolt are changed under the theoretical axial preload; Record the axial cross-sectional geometric parameters of the bolt under the theoretical axial preload force, and obtain the axial cross-sectional geometric parameters of the bolt at the connecting thread; When the nut is tightened on the bolt and the connecting thread is stretched and deformed, the thread geometric parameters of the nut match the axial cross-sectional geometric parameters of the bolt after stretching, and the thread geometric parameters of the nut are consistent with the axial cross-sectional geometric parameters of the bolt at the connecting thread. The thread geometric parameters of the non-standard nut are determined according to the axial cross-sectional geometric parameters of the connecting thread. The stretching degree of the bolt under different preload forces can be freely designed, and the non-standard nut can be processed according to the thread geometry parameters.

2. The method for forming non-standard nuts according to claim 1, characterized in that: In designing the thread geometric parameters of the non-standard nut according to the axial cross-sectional geometric parameters of the connecting thread, the axial cross-sectional geometric parameters are the same as the thread geometric parameters.

3. The method for forming a non-standard nut according to claim 1 or 2, characterized in that: After the non-standard nut is processed, the process of connecting the non-standard nut to the bolt includes: Screw the non-standard nut onto the bolt through the thread; Stretching the bolt with an actual axial preload, wherein the actual axial preload is equal to the theoretical axial preload; Maintain the actual axial preload force and tighten the non-standard nut to fit the second connected member.

4. The method for forming non-standard nuts according to claim 3, characterized in that: The bolt is a single-head bolt with a bolt head or a double-head bolt with a fastening nut connected at one end.

5. The method for forming non-standard nuts according to claim 4, characterized in that: Fixing the bolt on the first connected member includes: Screw the bolt head of the bolt into the thread of the first connected member, or fit the fastening nut to the end surface of the first connected member; The end surface of the bolt head or the fastening nut is welded to the first connected member.

6. The method for forming non-standard nuts according to claim 3, characterized in that: Before the non-standard nut is screwed onto the bolt through threads, the method further includes: connecting a gasket to the bolt.

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