Self-tightening anti-loosening fastening device

Abstract

The present invention discloses a self-tightening anti-loosening fastening device to improve the anti-loosening performance of the device, reduce the manufacturing cost of the product, and meet the needs of high standards, high safety and complex working conditions. It includes bolts and self-tightening nuts. The bolts are provided with ordinary, standard external threads; the self-tightening nuts are composed of two continuous deformed, self-tightening threads, the front deformed threads play a tightening role, and the rear deformed threads play a role in maintaining and increasing the anti-loosening ability; the self-tightening nuts are connected with the bolts to clamp the workpiece more and more tightly, or there is a certain pre-tightening force at any position of the bolt. The technical solution of the present invention can bring reliable anti-seismic and anti-loosening performance, significantly improve the manufacturing cost, reuse rate and service life of the nuts, ensure that the thread pairs of each link do not loosen under various harsh working environments such as frequent vibrations and load changes, and play a real anti-loosening and locking effect, and has a wide range of applications.

Description

Technical Field

[0001] The invention relates to an anti-loosening nut device and belongs to the technical field of anti-loosening and fastening workpieces. Background Art

[0002] Fasteners are often indispensable for connection and assembly processes in production and daily life, bringing convenience to the machinery industry. Among these connections and assemblies, bolt and nut connections are the most commonly used fastening structure. However, in actual use, machinery using bolt and nut fasteners is subject to complex operating conditions, and the nuts and bolts inevitably fall out in environments with frequent vibration and alternating loads, creating operational hazards.

[0003] To address the problem of loose fasteners, scientists and engineers in many countries around the world have conducted extensive experimental research. While anti-loosening fasteners originated abroad, they typically employ methods such as locking plates, pins, nylon inserts, deformed threads, and chemical coatings. While these methods delay the time it takes for fasteners to loosen, they do not fundamentally address the problem. Numerous anti-loosening methods exist in China, including non-detachable methods that employ welding, bonding, or riveting to convert a removable threaded connection into a non-detachable one. These methods are relatively reliable, but they also have significant drawbacks: threaded fasteners cannot be reused and are cumbersome to install and remove. Another approach involves mechanical fasteners, which utilize mechanical fasteners to secure and pin the threaded fastener to the connected member or between the threaded fasteners to prevent loosening. However, these methods increase the weight of the fastener, complicating manufacturing and installation, preventing flexible installation, and resulting in high costs. There is also an anti-loosening method that increases friction, which uses the method of increasing the friction between threads or the end faces of screws and nuts or increasing the friction of both at the same time to achieve the purpose of anti-loosening. This anti-loosening method has poor reliability and does not fundamentally solve the problem. There are still multiple safety hazards and it is difficult to adapt to the needs of high standards, high safety and other complex environmental working conditions. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a self-tightening anti-loosening fastening device, which achieves a better and more reliable anti-loosening purpose by improving the structure of the nut thread portion.

[0005] The present invention specifically adopts the following technical solutions:

[0006] A self-tightening anti-loosening fastening device includes a bolt and a nut; the nut and the bolt are connected by a thread, and the inner hole thread of the nut is composed of two continuous deformed threads with the same pitch. The deformation structure and method of the front deformed thread and the rear deformed thread are different. The median diameter of the front deformed thread is larger than the median diameter of the rear deformed thread. The front deformed thread is provided with a wedge angle, and the rear deformed thread is provided with a trapezoidal angle.

[0007] Furthermore, the front section of the deformed thread is a thread with a deformed tooth profile angle. A wedge-shaped bevel is provided at the root of the thread. The angle between the wedge-shaped bevel and the axis (wedge angle) is smaller than the tooth edge angle. The mean diameter of this section of the internal thread is the same as that of a normal thread. When the nut and bolt are tightened together to compress the workpiece, the tooth tips of the bolt's external thread can tightly press against the wedge-shaped bevel of the front section of the deformed thread, thereby generating a relatively large locking force. Due to the change in tooth profile angle, the normal force applied to the contact between the threads increases. Therefore, the normal pressure of the front section of the deformed thread is much greater than the clamping pressure, and the resulting anti-loosening friction force is greatly increased. At the same time, when the external thread of the bolt engages with the deformed internal thread of the front section of the nut, the wedge-shaped bevel evenly distributes the load over the entire length of the contacting helix, avoiding the situation in which more than 80% of the total load is concentrated on the thread surfaces of the first and second teeth when ordinary threads engage. Therefore, the front section of the deformed thread coupling overcomes the disadvantage of ordinary standard couplings that are prone to loosening under vibration.

[0008] Furthermore, the rear deformed thread is a tooth angle deformed thread, and a trapezoidal angle is provided at the bottom of the tooth. The angle between the trapezoidal tooth edge and the center axis of the tooth (trapezoidal tooth angle) is smaller than the original tooth angle, and the median diameter of the internal thread of this section is smaller than the median diameter value of the mating bolt thread, and its preferred value is 0.05mm-0.2mm; when the nut and bolt are screwed together or the workpiece is pressed, the two side surfaces of the tooth profile of the external thread of the bolt can be tightly attached to the two side surfaces of the tooth profile of the rear deformed thread, thereby generating greater friction and locking force.

[0009] Since the mean diameter of this section of thread becomes smaller, first of all, there is an interference fit between the threaded connection with the external thread of the bolt. As the interference fit increases, the friction and anti-loosening locking force generated on the threaded connection surface will gradually increase; secondly, the smaller mean diameter will make the major diameter of this section of internal thread smaller (smaller than the major diameter of the external thread of the connecting bolt), which will compress the tooth tip of the external thread of the bolt at the connection and cause it to deform or even damage it. The space formed by the trapezoidal angle of the tooth bottom design effectively avoids damage to the tooth tip of the external thread of the bolt and increases the expansion space caused by deformation due to interference fit.

[0010] When the bolt thread engages with the deformed thread at the rear section of the nut, the deformed thread connection pair not only overcomes the disadvantage of ordinary standard connection pairs being easily loosened under vibration conditions, but also protects the external thread of the bolt and extends its service life.

[0011] Furthermore, the outer peripheral shapes of the deformed threaded portion at the front section and the deformed threaded portion at the rear section of the nut are different. In the present invention, the nut is directional when tightened, and the end face of the deformed threaded portion at the front section contacts the workpiece. Changing the outer peripheral shape of the nut can effectively distinguish them.

[0012] The working principle of the present invention is that the inner hole thread of the nut has two continuous sections with the same pitch of deformed threads. The wedge surface provided on the front section increases the normal force, greatly improving the ability of the nut to resist loosening caused by vibration during tightening; the trapezoidal angle and the interference fit of 0.05mm-0.2mm provided on the rear section enable the nut to form friction resistance due to interference when it is at any position of the bolt or when tightening the workpiece. At the same time, the trapezoidal angle is also designed to prevent damage to the external thread of the bolt; when the frictional anti-loosening locking force formed by the two sections of the thread is superimposed and enhanced on each other, a good anti-loosening ability will inevitably be formed.

[0013] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0014] 1. Reliable anti-seismic and anti-loosening performance: The present invention can achieve double locking, that is, on the one hand, locking is achieved by increasing the normal force of the wedge-shaped surface of the deformed thread at the front section of the nut, and on the other hand, locking is achieved by increasing the interference fit of the deformed thread at the rear section of the nut, so that the nut can achieve double self-locking and self-tightening when locking the bolt, thereby better achieving anti-seismic and anti-loosening performance.

[0015] 2. According to the principle of the present invention, the present invention can lock the bolt without damaging the thread pair structure, thereby significantly improving the service life of the nut and bolt.

[0016] 3. Reusable: The design of the trapezoidal deformation angle of the rear section of the nut plays a role in protecting the outer teeth of the bolt and providing space for deformation, so the present invention can be reused.

[0017] 4. No auxiliary locking elements are required, such as spring washers, stop washers, etc. This fastening device does not require any external auxiliary elements and can achieve the purpose of complete self-locking.

[0018] 5. It can greatly reduce product costs and increase market share.

[0019] 6. The present invention is a unified type fastening device, and the specifications and models adopt standard sizes and match the standard external threads.

[0020] 7. The present invention is not affected by drastic temperature changes and can be widely used in parts requiring self-locking functions, such as high-speed railways, aerospace, ships, automobiles, etc., and the specifications can be set according to actual needs.

[0021] 8. Any metal or non-metal can be used to achieve no restrictions on material, shape, and size.

[0022] 9. The same locking force can be achieved when screwing in and out, so that the nut will not loosen BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the structural diagram of the device of the present invention

[0024] Figure 2 Schematic diagram of the thread pair structure of the present invention

[0025] Figure 3 Schematic diagram of the front section deformed thread of the present invention

[0026] Figure 4 Schematic diagram of the rear section deformed thread of the present invention

[0027] Figure 5 Schematic diagram of an embodiment of the present invention DETAILED DESCRIPTION

[0028] In order to facilitate those skilled in the art of fastening to understand and implement the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 As shown, the device is a self-tightening anti-loosening fastening device, including a bolt and a nut; the nut and the bolt are connected by a thread, and the inner hole thread of the nut is composed of two continuous deformed threads with the same pitch. The deformation structure and method of the front deformed thread and the rear deformed thread are different. The middle diameter of the front deformed thread is larger than the middle diameter of the rear deformed thread. The front deformed thread is provided with a wedge angle, and the rear deformed thread is provided with a trapezoidal angle.

[0030] Example 1:

[0031] like Figure 1 、 Figure 5 As shown, the bolt thread is a 60° standard thread, and the front section of the nut is a 60° ordinary internal thread with the same mean diameter as the ordinary thread; the angle between the wedge-shaped slope and the axis (wedge angle) of the front section deformed thread is 48°; when the nut and the bolt are tightened against each other to press the workpiece, the tooth tip of the bolt's external thread can be tightly pressed against the wedge-shaped slope of the front section deformed thread, forming a normal pressure increasing part, which increases the normal force applied to the contact between the threads. Therefore, the normal pressure of the front section deformed thread is much greater than the clamping pressure, and the anti-loosening friction force generated is also greatly increased; at the same time, when the external thread of the bolt and the deformed internal thread of the front section of the nut are engaged, the wedge-shaped slope makes the load evenly distributed on the entire length of the contacting section of the spiral line, avoiding more than 80% of the total load when the ordinary thread is engaged. It is concentrated on the thread surface of the first and second teeth, so that the front section deformed thread connection pair overcomes the disadvantage that the ordinary standard connection pair is easy to loosen under a vibration environment.

[0032] The rear deformed thread is a 60° deformed thread, and the thread median diameter is 0.1mm smaller than the median diameter of the mating bolt thread, and a 15° trapezoidal thread angle is provided at the tooth bottom. When the nut and the bolt are screwed to each other in any position or the workpiece is pressed, first of all, there is an interference with the thread connection with the external thread of the bolt, and the two side surfaces of the tooth profile of the 60° thread section of the deformed thread can be tightly attached to the two side surfaces of the tooth profile of the 60° thread of the bolt. As the interference increases, the friction and anti-loosening locking force generated will gradually increase. Secondly, the smaller the median diameter will make the major diameter of the internal thread of this section smaller (smaller than the major diameter of the external thread of the connecting bolt), which will compress the tooth tip of the external thread of the bolt at the connection and cause it to deform or even damage it. The space formed by the 15° trapezoidal angle designed at the tooth bottom can effectively avoid damage to the tooth tip of the external thread of the bolt, and will increase the elastic expansion space caused by the interference.

[0033] The inner hole thread of the nut has two continuous sections of deformed threads with the same pitch. The 48° wedge surface on the front section increases the normal force, greatly improving the nut's ability to resist loosening caused by vibration during tightening; the 15° trapezoidal angle and 0.1mm interference fit on the rear section allow the nut to form frictional resistance due to interference when it is at any position on the bolt or when tightening the workpiece. At the same time, the trapezoidal angle is designed to prevent damage to the external thread of the bolt. When the frictional anti-loosening locking force formed by the two sections of the thread is superimposed and enhanced on each other, a good anti-loosening ability will inevitably be formed.

[0034] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the concept of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A self-tightening anti-loosening fastening device, comprising a bolt and a nut, wherein the nut and the bolt are connected by mating threads, and characterized in that: The inner hole thread of the nut is composed of two continuous deformed threads with the same pitch. The deformation structure and method of the front deformed thread and the rear deformed thread are different. The median diameter of the front deformed thread is larger than the median diameter of the rear deformed thread. The front deformed thread is provided with a wedge angle, and the rear deformed thread is provided with a trapezoidal angle. The rear deformed thread is a tooth angle deformed thread, and a trapezoidal tooth surface is provided at the bottom of the tooth. The angle between the trapezoidal tooth edge and the center axis of the tooth profile, that is, the trapezoidal tooth angle, is smaller than the original tooth angle. The front deformed thread is a tooth angle deformed thread, and a wedge-shaped inclined surface is provided at the bottom of the tooth. The outer peripheral shapes of the front deformed thread and the rear deformed thread of the nut are different.

2. The self-tightening anti-loosening fastening device according to claim 1, characterized in that: The angle between the wedge-shaped inclined surface and the axis, that is, the wedge angle, is smaller than the tooth edge angle.

3. The self-tightening anti-loosening fastening device according to claim 1, characterized in that: The median diameter of the front deformed thread is the same as that of the ordinary thread; the median diameter of the rear deformed thread is 0.05mm-0.2mm smaller than the median diameter of the mating bolt thread.

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