An easily assembled thread

Abstract

The utility model discloses an easy assembly thread relates to mechanical fastener technical field, including the first thread and the second thread of mutual helical engagement connection on the nut and bolt, be equipped with the first thread on the nut, be equipped with the second thread on the bolt, and the first thread and the second thread cross section are trapezoidal, the first thread root bottom end is equipped with the bevel part, and the bevel part forms line contact with the first thread bottom end, and the radial angle alpha of bevel part and nut is 13 degrees~23 degrees. Make the pushing resistance when assembling smaller, and the convenience of dismounting has been improved.

Description

Technical Field

[0001] This utility model relates to the field of mechanical fastener technology, specifically to an easy-to-assemble thread. Background Technology

[0002] In the field of mechanical connections, traditional threaded structures are widely used due to their simple structure and high load-bearing capacity. Their core principle is to achieve axial locking and positioning of components through the interlocking of internal and external thread profiles. However, existing threaded pairs mostly employ a surface contact design, resulting in a large meshing area. This easily generates significant frictional resistance during engagement, especially in deep holes, blind holes, or connections made of high-strength materials. This significantly increases assembly torque, easily leading to thread damage, jamming, or even failure. Furthermore, surface contact exacerbates wear, reduces reusability, and makes them prone to loosening under high-frequency vibration conditions, limiting their application in precision and automated assembly scenarios.

[0003] Chinese Patent Publication No. CN112983961A, Publication Date: June 18, 2021, discloses a utility model called an anti-loosening nut, comprising a nut body and a flange face. The nut body is connected to the upper part of the flange face, and the nut body and the flange face are integrally formed. The anti-loosening nut has a threaded hole in the axial direction and a relief groove in the radial direction. The upper thread of the relief groove is an anti-loosening thread, and the lower thread of the relief groove is a normal thread. The anti-loosening thread has a tooth profile angle α between two adjacent tooth sides, and the normal thread has a tooth profile angle β between two adjacent tooth sides. The thread of this nut is a tooth profile, and it is in surface contact with the bolt, resulting in high friction and making it difficult to assemble. Utility Model Content

[0004] This utility model discloses an easy-to-assemble thread. By setting an angled portion, the friction between the first thread and the second thread is reduced, thereby reducing the pushing resistance during assembly and facilitating assembly.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an easy-to-assemble thread, including a first thread and a second thread that are helically engaged on a nut and a bolt, wherein the nut is provided with the first thread and the bolt is provided with the second thread, and the cross-sections of the first thread and the second thread are trapezoidal; the root end of the first thread is provided with a beveled portion, which forms line contact with the bottom end of the first thread, and the beveled portion and the radial angle α between the beveled portion and the nut is 13 degrees to 23 degrees.

[0006] Preferably, both the first and second threads have right-angled trapezoidal cross-sections. The first thread is located on the inner wall of the bottom end of the nut, and the second thread is located on the outer wall of the top end of the bolt, with the two threads engaging. The hypotenuse of the right-angled trapezoid is located at the top, and the right-angled side is located at the bottom. Using a right-angled trapezoidal cross-section provides clear guidance from the hypotenuse and right-angled side, improving self-alignment by 30% during thread engagement and effectively reducing localized jamming caused by assembly misalignment. Simultaneously, the right-angled side bears the main axial load, preventing excessive wear on the hypotenuse and extending its service life. The nut is made of nylon, and the thread material is steel. Nylon has excellent shock absorption properties, effectively absorbing vibrations generated during bolt use, reducing noise, and improving the comfort of the operating environment. The nylon material also prevents the bolt from slipping due to vibration during long-term use. Under strong vibration, the nylon nut will deform to prevent the bolt from slipping.

[0007] Preferably, the bottom surfaces of the first and second threads are horizontal. All corresponding surfaces of the first and second threads are parallel. The combination of the horizontal bottom surface and the parallel surface ensures a uniform force distribution on the threads, eliminating wedge-shaped compression, reducing assembly and disassembly torque, and avoiding the "seizing" phenomenon caused by wedging between surfaces in traditional trapezoidal threads. It also facilitates the use of conventional grinding processes, improving the machining pass rate.

[0008] Preferably, the inclination angle β of the trapezoidal hypotenuse of the first and second threads is 40 to 55 degrees. A 45-degree angle is preferred. The 45° hypotenuse balances self-locking and loosening performance, reduces the loosening angle, lowers resistance during reverse rotation, and achieves a dynamic balance of "tight but not rigid, loose but not detached," significantly improving assembly and disassembly efficiency.

[0009] Preferably, the radial distance t between the first and second threads is 0.5 to 1.5 mm. A 1 mm radial clearance is preferred. A 1 mm radial clearance allows for slight displacement due to thermal expansion and contraction while controlling the amount of runout to within 0.02 mm, avoiding adhesion caused by excessive tightness and fatigue fretting caused by excessive looseness, thus improving the reliability of the connection under alternating high and low temperature conditions.

[0010] Preferably, the axial distance d between the first and second threads is 0.45–0.85 mm. A preferred value is 0.65 mm. This 0.65 mm pitch, determined through repeated experiments, reduces the unit tooth load under the same axial force, minimizes localized plastic deformation, and increases the number of repeated assembly and disassembly cycles to over 50 without locking. The smaller axial distance d between the first and second threads also distributes some of the load across the beveled portion, resulting in a more stable structure and extended service life.

[0011] Preferably, the beveled portion is the pressure-bearing part, and only the beveled portion of the first thread contacts the second thread. The first thread bears pressure only at the beveled portion, and the second thread only at the right-angle end, forming line contact. This line contact reduces the friction area, and the contact area is concentrated at the high-hardness bevel, avoiding interference between the thread crest and root, reducing resistance during assembly and disassembly, and facilitating assembly.

[0012] Preferably, the right angle of the second thread trapezoid is located at the bottom end, and the right angle end and the beveled part are in contact. The contact method between the right angle end and the beveled part further optimizes the force distribution of the thread, making the thread more stable when bearing load.

[0013] Preferably, the length L of the beveled portion is 1 to 4 mm. More preferably, it is 3 mm. A 3 mm beveled portion length ensures sufficient bearing area while reducing the contact area between threads, lowering friction, and further improving the thread's anti-locking performance and ease of assembly.

[0014] Preferably, the height h of the bevel portion is 0.47–1.47 mm. A preferred setting is 0.975 mm. A bevel height of 0.975 mm ensures good anti-loosening performance of the thread under vibration conditions, while reducing friction between threads during assembly and disassembly, thus lowering the risk of locking.

[0015] Beneficial effects: By setting an angled portion, this utility model enables the first thread and the second thread to form line contact, significantly reducing the risk of thread lock-up during disassembly and assembly, and improving the convenience of disassembly and assembly. Simultaneously, under vibration conditions, this thread structure can maintain higher stability, effectively preventing loosening of the connection position, thereby enhancing the reliability of the connection and extending the service life of the threaded connection. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the nut and bolt of this utility model.

[0017] Figure 2 for Figure 1 Enlarged view of point A.

[0018] Figure 3 for Figure 2 Enlarged view at point B.

[0019] Reference numerals: 1: Bolt; 2: Nut; 3: First thread; 4: Second thread; 5: Angled portion; 6: Right-angle end. Detailed Implementation

[0020] The easy-to-assemble thread disclosed in this utility model effectively solves the problems of traditional threads being difficult to disassemble and assemble, easily locking during disassembly and assembly, and easily loosening under vibration conditions through optimized design of thread cross-sectional shape and contact method, significantly improving the reliability and durability of threaded connections.

[0021] exist Figure 1 and Figure 2 In the illustrated embodiment, the easy-to-assemble thread consists of a first thread 3 and a second thread 4 that helically engage on a nut 2 and a bolt 1. The first thread 3 is located on the inner wall of the nut 2, and the second thread 4 is located on the outer wall of the bolt 1. The two are tightly connected through a helical structure. Unlike traditional threads, the cross-sections of the first thread 3 and the second thread 4 are trapezoidal. This shape design lays the foundation for the stress distribution and ease of assembly of the thread. The root of the first thread 3 has a beveled portion 5. When the first thread 3 and the second thread 4 engage, the beveled portion 5 forms a line contact with the bottom of the second thread 4, rather than the surface contact of traditional threads. The line contact reduces the friction area during thread engagement, effectively reducing the risk of locking due to excessive friction during disassembly and assembly. The inclination angle α of the beveled portion 5 is set to 13 degrees to 23 degrees, preferably 18 degrees. This angle range has been repeatedly verified to ensure the stability of the line contact without reducing the thread's load-bearing capacity due to an excessively large angle. This thread is suitable for connecting components of heavy-duty equipment such as jaw crushers and cone crushers.

[0022] exist Figure 1 and Figure 2 In the preferred embodiment shown, the cross-sections of the first thread 3 and the second thread 4 are further optimized into right-angled trapezoids, with the hypotenuse at the top and the right-angled side at the bottom. The right-angled trapezoidal structure provides clear guidance during thread engagement. When the nut 2 and bolt 1 are screwed together, the hypotenuses fit together to form a guide, automatically centering the thread and reducing local jamming caused by misalignment during assembly. Compared to ordinary trapezoidal threads, this design significantly improves self-centering and effectively enhances assembly convenience. Simultaneously, the right-angled end 6, as the main load-bearing part, directly bears the axial load, preventing wear caused by excessive force on the hypotenuse and extending the thread's service life. The first thread 3 is located on the inner wall of the bottom end of the nut 2, and the second thread 4 is located on the outer wall of the top end of the bolt 1. This layout ensures that the force point during thread engagement is concentrated at the root, further enhancing the stability of the connection.

[0023] exist Figure 1 and Figure 2 In the preferred embodiment shown, the bottom surfaces of the first thread 3 and the second thread 4 are designed as horizontal planes, and all corresponding surfaces of the two are parallel. The combination of the horizontal bottom surface and the parallel surface ensures a uniform surface distribution of the threads under force, eliminating the wedge-shaped squeezing effect caused by the inclined contact surface of traditional threads. Traditional trapezoidal threads often experience "seizing" due to the wedging effect between the surfaces, while this design, through the cooperation of the horizontal bottom surface and the parallel surface, significantly reduces the torque during assembly and disassembly, improving the ease of assembly. Furthermore, the horizontal bottom surface design facilitates machining using conventional grinding processes, improving the machining accuracy and yield rate of the threads and reducing production difficulty.

[0024] exist Figure 1 and Figure 2 In the preferred embodiment shown, the inclination angle β of the trapezoidal bevel of the first thread 3 and the second thread 4 is set to 40 degrees to 55 degrees, preferably 45 degrees. The 45-degree bevel angle achieves a perfect balance between self-locking performance and loosening performance: on the one hand, this angle provides sufficient self-locking force to prevent the thread from loosening under axial load; on the other hand, when disassembly is required, the reverse resistance generated by the 45-degree bevel is small, facilitating the separation of the nut 2 and the bolt 1, achieving a dynamic balance of "tight but not rigid, loose but not detached." This design makes the threaded connection particularly outstanding in scenarios involving frequent disassembly and assembly, significantly improving work efficiency.

[0025] exist Figure 1 and Figure 2 In the preferred embodiment shown, the radial distance t between the first thread 3 and the second thread 4 is set to 0.5–1.5 mm, preferably 1 mm. This radial clearance provides necessary buffer space for the threaded connection, accommodating minute displacements caused by thermal expansion and contraction under alternating high and low temperature conditions, thus preventing thread sticking or jamming due to insufficient clearance. Simultaneously, the 1 mm clearance controls the amount of thread wobble during vibration to a very small range, ensuring connection stability. It avoids fatigue fretting wear caused by excessive clearance, and also prevents difficulties in assembly and disassembly due to insufficient clearance. This design significantly improves the reliability of the threaded connection under complex operating conditions and is suitable for equipment with drastic temperature changes or frequent vibrations.

[0026] During actual assembly, the advantages of this easy-to-assemble thread gradually become apparent. When nut 2 is screwed onto bolt 1, the beveled portion 5 of the first thread 3 forms line contact with the bottom end of the second thread 4. During the tightening process, the right-angled sides of the trapezoid gradually come into contact, bearing the main axial load, while the beveled side acts as a guide and assists in self-locking. The horizontal bottom surface and the parallel surface fit together. The two do not contact each other, reducing the contact area, lowering friction, and improving assembly efficiency; the 45-degree beveled angle makes the tightening process smooth and effortless, while providing a reliable self-locking effect; the 1 mm radial clearance provides space for the thread's thermal expansion and contraction and minor vibrations, preventing locking or loosening.

[0027] During disassembly, the low-friction characteristics of line contact make thread separation easier, and even after long-term use, the "seizing" phenomenon common in traditional threads will not occur. The 45-degree bevel angle reduces resistance during reverse rotation, reduces the torque required for disassembly, and improves maintenance efficiency. In addition, the right-angled trapezoidal structure allows the thread to maintain good accuracy after repeated disassembly and assembly, extending the thread's service life.

[0028] Under vibration conditions, the stability of this easy-to-assemble thread is particularly outstanding. The nylon nut ensures that the friction between the threads remains stable, preventing loosening due to minor displacements caused by vibration; the 1 mm radial clearance limits excessive wobble, avoiding fatigue wear between the threads; and the 45-degree bevel angle provides appropriate self-locking force, preventing the threads from loosening on their own during vibration. This design ensures that the threaded connection remains reliable during the operation of mechanical equipment, reducing the risk of failure due to loosening.

[0029] This invention constructs a highly efficient and easily assembled threaded system through a design combination of "line contact + right-angled trapezoid + reasonable angle and clearance". The line contact of the beveled portion 5 reduces friction and the risk of locking; the cross-section of the right-angled trapezoid optimizes force distribution and guiding performance; the horizontal base and parallel surface avoid wedge-shaped compression; the 45-degree bevel balances self-locking and loosening performance; and the 1 mm radial clearance adapts to complex working conditions. These design features work together to significantly improve the ease of assembly and disassembly, vibration stability, and adaptability to various working conditions, providing a reliable solution for threaded connections in various types of mechanical equipment.

[0030] exist Figure 1 and Figure 2 In the preferred embodiment shown, the axial distance d between the first thread 3 and the second thread 4 is set to 0.45–0.85 mm, preferably 0.65 mm. This pitch parameter has been verified through extensive experiments and can reduce the load per tooth under the same axial force. With traditional threads, if the pitch is too small, the pressure on the thread teeth is concentrated, easily leading to localized plastic deformation, and the high friction makes disassembly and assembly inconvenient; if the pitch is too large, the tightness of the connection decreases, and it is prone to loosening during vibration. The axial distance of 0.65 mm achieves a balance between load distribution and connection stability, allowing the thread to maintain good fit performance even after more than 50 repeated disassembly and assembly cycles, and significantly reducing disassembly and assembly time, thus significantly improving the durability and maintenance efficiency of the thread.

[0031] exist Figure 1 and Figure 2 In the preferred embodiment shown, the beveled portion 5 serves as the core pressure-bearing part of the first thread 3, and its contact method is crucial for preventing lock-up and facilitating assembly. Only the beveled portion 5 contacts the second thread 4 in the first thread 3, while the second thread 4 bears pressure only at its right-angle end 6, forming a pure line contact. This design significantly reduces the frictional area during thread engagement, decreasing the frictional torque during assembly and disassembly, and lowering the risk of "cold welding" lock-up due to overheating. Simultaneously, the beveled portion 5 undergoes hardening treatment, possessing high hardness. The contact area is concentrated in this high-hardness region, effectively resisting wear and avoiding jamming caused by interference between the crest and root of the thread in traditional threads, ensuring smooth tightening and loosening of the thread.

[0032] exist Figure 1 and Figure 2In the preferred embodiment shown, the right angle of the trapezoid of the second thread 4 is located at the bottom, and its right-angle end 6 makes precise contact with the beveled portion 5 of the first thread 3. This contact method further optimizes the force distribution. When the thread is subjected to axial load, the force transmission path is concentrated on the line contact surface between the beveled portion 5 and the right-angle end 6, and the load is dispersed along the inclination direction of the beveled portion 5, avoiding thread deformation caused by excessive local stress. The rigid structure of the right-angle end 6 provides stable support for load transmission, and together with the elastic buffer of the beveled portion 5, the thread can remain stable even when subjected to impact loads.

[0033] exist Figure 1 and Figure 2 In the preferred embodiment shown, the length L of the beveled portion 5 is set to 1–4 mm, preferably 3 mm. A length of 3 mm ensures sufficient bearing area. Too short a length would cause excessive contact stress, leading to accelerated wear of the beveled portion 5; too long a length would expand the friction area, increasing the risk of locking. The 3 mm length design allows the beveled portion 5 to stably bear axial force while controlling the contact area within a reasonable range, reducing friction and further improving the thread's anti-locking performance. In practical use, this length, combined with the line contact method, allows the thread to maintain low frictional resistance even during frequent disassembly and assembly, making operation more effortless. Under vibration conditions, the frictional force generated by the line contact, combined with the moderate pressure from the 0.975 mm height, effectively suppresses minor thread displacement and prevents loosening. The 1 mm radial clearance provides space for thermal expansion and contraction, while the 0.65 mm axial spacing avoids squeezing interference between thread teeth, ensuring stable engagement of the thread under temperature changes and vibration impacts.

[0034] exist Figure 1 and Figure 2 In the preferred embodiment shown, the height h of the beveled portion 5 is set to 0.47–1.47 mm, preferably 0.975 mm. This height parameter matches the overall dimensions of the thread, ensuring anti-loosening performance under vibration conditions. If the height is too low, the contact pressure between the beveled portion 5 and the second thread 4 is insufficient, which can easily create gaps during vibration, leading to loosening of the connection; if the height is too high, the contact pressure is too great, which can easily cause frictional locking. The height of 0.975 mm allows the beveled portion 5 to form a moderate pressure contact with the right-angle end 6 of the second thread 4, which can suppress loosening through friction during vibration without generating excessive friction during disassembly and assembly, achieving a dual balance between anti-loosening and anti-locking.

[0035] In actual assembly, the synergistic effect of various parameters is particularly significant. When nut 2 is screwed onto bolt 1, the beveled portion 5 of the first thread 3 and the right-angled end 6 of the second thread 4 form line contact. The axial spacing of 0.65 mm ensures that the thread teeth evenly distribute the load, avoiding local overload. The 3 mm long beveled portion 5 provides stable support, and the 0.975 mm height ensures moderate contact pressure, preventing both loosening and jamming. During tightening, the low friction characteristics of the line contact make operation easier, and the 45-degree bevel angle guides the thread to automatically center, reducing locking caused by misalignment. During multiple disassembly and assembly, the 0.65 mm axial spacing distributes the load of each disassembly and assembly, the 3 mm long high-hardness beveled portion 5 resists wear, and the line contact reduces frictional damage, allowing the threads to maintain a precise fit even after more than 50 disassembly and assembly cycles.

[0036] This invention constructs a highly efficient and easily assembled threaded system by optimizing axial spacing, defining contact areas, and precisely designing the length and height of the beveled portion 5. Line contact reduces friction and the risk of locking, the 3mm length of the beveled portion 5 balances pressure and friction, and the 0.975mm height ensures both anti-loosening and anti-locking. These parameters work synergistically to make the threaded connection excellent in terms of ease of assembly and disassembly, vibration stability, and reusability, significantly extending the service life of the threaded connection and enhancing the reliability of equipment operation.

Claims

1. An easy-to-assemble thread, comprising a first thread and a second thread on a nut and a bolt that are helically engaged, characterized in that, The nut has a first thread, and the bolt has a second thread. The cross-sections of the first and second threads are trapezoidal. The root of the first thread has a beveled part at the bottom, which forms a line contact with the bottom of the first thread. The beveled part and the radial angle α between the beveled part and the nut is 13 degrees to 23 degrees.

2. The easy-assembly thread according to claim 1, characterized in that, Both the first and second threads have right-angled trapezoidal cross-sections. The nut material is nylon, and the thread material is steel.

3. An easy-assembly thread according to claim 1 or 2, characterized in that, The bottom surfaces of the first and second threads are horizontal.

4. The easy-assembly thread according to claim 3, characterized in that, The inclination angle β of the trapezoidal hypotenuse of the first and second threads is 40 degrees to 55 degrees.

5. An easy-assembly thread according to claim 1 or 4, characterized in that, The radial distance t between the first and second threads is 0.5 to 1.5 mm.

6. An easy-assembly thread according to claim 1 or 4, characterized in that, The axial distance d between the first and second threads is 0.45 to 0.85 mm.

7. The easy-assembly thread according to claim 1, characterized in that, The beveled part is the pressure-bearing part, and only the beveled part of the first thread contacts the second thread.

8. The easy-assembly thread according to claim 7, characterized in that, The right angle of the second spiral trapezoid is located at the bottom, and the right angle end and the oblique angle part are in contact.

9. An easy-assembly thread according to claim 1, 7, or 8, characterized in that, The length L of the beveled portion is 1 to 4 millimeters.

10. An easy-assembly thread according to claim 1, 7, or 8, characterized in that, The height h of the angled portion is 0.47 to 1.47 mm.

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