A constant force self-tightening anti-loosening bolt

Abstract

The present invention discloses a constant force self-tightening anti-loosening bolt, comprising a fixing seat, a closing component, a tapered bolt and a curved surface push rod; the fixing seat and the closing component are fixedly connected, a threaded through hole is provided inside the fixing seat, and the closing component is provided with an inner hole connected to the threaded through hole; the tapered bolt comprises a bolt head, a bolt rod and an inner tapered sleeve fixedly connected in sequence, the tapered bolt passes through the threaded through hole, and one end of the inner tapered sleeve extends into the inner hole; the curved surface push rod comprises a cylindrical rod and a curved surface rod fixedly connected, the outer surface of the curved surface rod is an arc surface, the curved surface push rod is provided in the inner hole, and one end of the curved surface rod is stuck in the inner tapered sleeve. The constant force self-tightening anti-loosening bolt provided by the present invention has a large locking force between the fixing seat and the tapered bolt, a good anti-loosening effect, and does not require frequent maintenance after use.

Description

Technical Field

[0001] The invention belongs to the technical field of bolts, and in particular relates to a constant-force self-tightening anti-loosening bolt. Background Art

[0002] Threaded connections have been widely used in the automotive, machine tool, aerospace, railway and other industries due to their compact structure, easy assembly and disassembly, strong connection force, and reusability. Traditional threaded connections meet the self-locking conditions under static loads and small temperature changes. The loosening torque between the threads is less than the self-locking torque. The connection system is in a balanced state and can be effectively locked. Generally, there is no need to introduce additional anti-loosening methods to prevent loosening. However, when the structure is subjected to impact, vibration, and especially dynamic loads in the form of lateral cycles, the preload force of the threaded connection is likely to gradually decrease, eventually causing connection failures in the form of loosening, falling off, and falling off. In safety and critical applications, this failure can be catastrophic.

[0003] Thread loosening prevention is a global problem, and accidents caused by thread loosening are common. Although there are thousands of anti-loosening structures and patents, there is currently no ideal solution for how to eliminate dynamic clearance caused by thermal deformation, plastic deformation and structural deformation and keep the preload basically constant in the harsh environment of "large vibration, large temperature difference and large deformation".

[0004] At present, high-performance anti-loosening technology is monopolized by Japan's Hardlock, the United States' Spiralock and Sweden's Nordi-Lock, but they cannot avoid the adverse effects of dynamic clearance on performance, and their reliability is not high in harsh environments, resulting in limited applications. Generally, the durability of a mechanical structure is proportional to the number of bolt connections it uses. With the development of modern manufacturing, avoiding the loosening of threaded connection structures during work has also become one of the core issues of concern in the design of threaded connection structures. Therefore, it is particularly important to design and use safe and reliable anti-loosening methods for threaded connections. Although there are many anti-loosening methods for threaded fasteners, there are generally four types: the first is friction anti-loosening, which mainly relies on increasing friction; the second is mechanical anti-loosening, which mainly uses pins, washers, and steel wires to jam the bolts; the third is riveting and punching anti-loosening, which mainly rivets and welds the thread pairs; the fourth is structural anti-loosening, such as Hard Lock anti-loosening nuts, American Spiralock anti-loosening nuts, Swedish Nordi-Lock anti-loosening washers, Tang's thread anti-loosening, ST2 thread anti-loosening, SLB thread anti-loosening, etc.

[0005] The first type of anti-loosening is the most widely used anti-loosening method. This method generates a positive pressure between the thread pairs that does not change with the external force, thereby obtaining a friction force that can prevent the thread pairs from rotating relative to each other. This friction force can be achieved by pressing the thread pairs axially or in two directions at the same time. For example, elastic washers, double bolts, self-locking bolts and nylon inserts are used to lock bolts. This anti-loosening method is more convenient for bolt disassembly, but in the case of impact, vibration and variable load, the bolts will initially loosen, resulting in a decrease in preload. As the number of vibrations increases, the loss of preload slowly increases, which will eventually lead to bolt loosening and threaded connection failure. However, there is a limit to increasing friction by increasing the positive pressure between the thread pairs.

[0006] The second method of mechanical anti-loosening is to use a stopper to directly limit the relative rotation of the thread pair. For example, cotter pins, serial steel wires and stop washers are used. This method makes disassembly inconvenient, and its anti-loosening method has no pre-tightening force, that is, the anti-loosening method can only take effect when the thread pair is loosened to the anti-loosening position. Therefore, this method is actually not anti-loosening, but anti-falling.

[0007] The third method is riveting and punching to prevent loosening. After tightening, punching, welding, bonding and other methods are used to make the thread pair lose the characteristics of the kinematic pair and the connection becomes an inseparable connection. The disadvantage of this method is that the bolt rod can only be used once and it is very difficult to disassemble. The thread pair must be destroyed before it can be disassembled. The scope of use is very limited.

[0008] The most classic of the fourth type of anti-loosening structure is the Japanese Hard Lock anti-loosening nut, which combines and improves the anti-loosening principle of double nuts and convex and concave nuts. The upper nut is a concave nut and the lower nut is a convex nut. During processing, the center is slightly offset and processed eccentrically, forming the effect of driving a wedge into the gap to prevent the thread from loosening. However, there are different corresponding eccentricities for different sizes and materials, which makes production and manufacturing troublesome and inefficient. Summary of the invention

[0009] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a constant force self-tightening anti-loosening bolt, which has a large locking force between a fixing seat and a tapered bolt, a good anti-loosening effect, and does not require frequent maintenance after use.

[0010] The present invention provides the following technical solutions:

[0011] A constant force self-tightening anti-loosening bolt, comprising a fixing seat, a closing component, a tapered bolt and a curved top rod;

[0012] The fixing seat and the closing component are fixedly connected, a threaded through hole is provided inside the fixing seat, and the closing component is provided with an inner hole connected to the threaded through hole;

[0013] The tapered bolt comprises a bolt head, a bolt rod and an inner tapered sleeve which are fixedly connected in sequence, the tapered bolt passes through the threaded through hole, and one end of the inner tapered sleeve extends into the inner hole;

[0014] The arc surface push rod comprises a cylindrical rod and an arc surface rod which are fixedly connected. The outer surface of the arc surface rod is an arc surface. The arc surface push rod is arranged in the inner hole, and one end of the arc surface rod is clamped in the inner cone sleeve.

[0015] Preferably, the outer surfaces of the bolt rod and the inner tapered sleeve are both provided with external threads, and the threaded through hole of the fixing seat is provided with internal threads matching the external threads.

[0016] Preferably, it also includes a push rod disc spring, which is arranged in the inner hole of the closing component and contacts the cylindrical rod of the arc push rod.

[0017] Preferably, it also includes a bolt rod disc spring, wherein the bolt rod disc spring is installed between the bolt head of the bolt rod and the fastening object.

[0018] Preferably, the surface of the inner cone sleeve is a cone, and the inner cone sleeve is provided with a plurality of through grooves extending along the axial direction of the inner cone sleeve.

[0019] Preferably, the cone angle of the inner cone sleeve is 1-20°, and the through grooves are evenly distributed along the circumferential direction of the inner cone sleeve.

[0020] Preferably, the cross-sectional circular diameter of the cylindrical rod is larger than the cross-sectional circular diameter of the arc surface rod, and the end surface of the cylindrical rod close to the arc surface rod is parallel to the outer end surface of the inner tapered sleeve and has a gap therebetween.

[0021] Preferably, the closing assembly comprises a push rod seat and a rear cover plate that are fixedly connected, and the inner hole is provided inside the push rod seat.

[0022] Preferably, the rear cover plate is provided with an outer bolt hole, and the push rod seat and the fixing seat are both provided with inner bolt holes corresponding to the outer bolt hole, so that the rear cover plate, the push rod seat and the fixing seat are bolted together.

[0023] Preferably, the rear cover plate and the push rod seat, as well as the push rod seat and the fixing seat are fixedly connected by welding.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The constant force self-tightening anti-loosening bolt provided by the present invention has a fixed seat and a closed component fixedly connected, a threaded through hole is provided inside the fixed seat, and the closed component is provided with an inner hole connected to the threaded through hole. The tapered bolt comprises a bolt head, a bolt rod and an inner tapered sleeve which are fixedly connected in sequence, the tapered bolt passes through the threaded through hole, and one end of the inner tapered sleeve extends into the inner hole. The tail of the tapered bolt is a cantilever beam structure, which is deformed to form an undercut structure to prevent the thread from moving, thereby preventing the tapered bolt from loosening, and does not require frequent maintenance after use;

[0026] (2) The arc surface push rod of the present invention comprises a cylindrical rod and an arc surface rod which are fixedly connected. The outer surface of the arc surface rod is an arc surface. The arc surface push rod is arranged in the inner hole, and one end of the arc surface rod is clamped in the inner tapered sleeve. During installation, the tapered bolt rotates, and the arc surface rod will give a reaction force to the inner tapered sleeve. The reaction force can be decomposed into an axial force and a radial force. The radial force is several times the axial force, thereby preventing the tapered bolt from sliding and loosening. Frequent maintenance is not required after use. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of a constant force self-tightening anti-loosening bolt;

[0028] Figure 2 It is a schematic diagram of the overall cross-sectional structure of a constant force self-tightening anti-loosening bolt;

[0029] Figure 3 It is a schematic diagram of the structure of a tapered bolt;

[0030] Figure 4 It is a schematic diagram of the cross-sectional structure of the fastening object and the fixing seat;

[0031] Figure 5 It is a schematic diagram of the cross-sectional structure of the curved top rod;

[0032] Figure 6 It is a structural schematic diagram of the ejector seat;

[0033] Figure 7 It is a schematic diagram of the structure of the rear cover;

[0034] The markings in the figure are: 1. tapered bolt; 1-1. bolt head; 1-2. bolt rod; 1-3. inner tapered sleeve; 1-4. through groove; 2. fastening object; 2-1. through hole; 3. fixing seat; 3-1. threaded through hole; 4. arc-surface push rod; 4-1. arc-surface rod; 4-2. cylindrical rod; 4-3. arc-shaped surface; 5. push rod seat; 5-1. inner hole; 5-2. inner bolt hole; 6. rear cover plate; 6-1. outer bolt hole; 7. push rod disc spring; 8. bolt rod disc spring. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0036] It should be noted that, in the description of the present invention, the directions or positional relationships indicated by terms such as "front", "rear", "left", "right", "up", "down", "inside" and "outside" are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0037] like Figure 1-5 As shown, a constant force self-tightening anti-loosening bolt comprises a fixing seat 3, a closing component, a tapered bolt 1 and a curved top rod 4; the fixing seat 3 and the closing component are fixedly connected, a threaded through hole 3-1 is provided inside the fixing seat 3, and the closing component is provided with an inner hole 5-1 connected to the threaded through hole 3-1; the tapered bolt 1 comprises a bolt head 1-1, a bolt rod 1-2 and an inner tapered sleeve 1-3 which are fixedly connected in sequence, the tapered bolt 1 passes through the threaded through hole 3-1, and one end of the inner tapered sleeve 1-3 extends into the inner hole 5-1, the tail of the tapered bolt 1 forms a cantilever beam structure, which is easy to deform. The outer surfaces of the bolt rod 1-2 and the inner tapered sleeve 1-3 are both provided with external threads, and the threaded through hole 3-1 of the fixing seat 3 is provided with internal threads matching the external threads; the arc surface top rod 4 includes a cylindrical rod 4-2 and an arc surface rod 4-1 that are fixedly connected, the outer surface of the arc surface rod 4-1 is an arc surface 4-3, the arc surface top rod 4 is arranged in the inner hole 5-1, and one end of the arc surface rod 4-1 is stuck in the inner tapered sleeve 1-3.

[0038] like Figure 2 As shown, the constant force self-tightening anti-loosening bolt provided in this embodiment also includes a push rod disc spring 7, which is arranged in the inner hole 5-1 of the closing component and contacts the cylindrical rod 4-2 of the arc push rod 4.

[0039] like Figure 1-2 As shown, the constant force self-tightening anti-loosening bolt provided in this embodiment also includes a bolt rod disc spring 8, which is installed between the bolt head 1-1 of the bolt rod and the fastening object 2. The bolt rod disc spring 8 can compensate for the dynamic clearance caused by various deformations (thermal deformation and structural deformation, etc.) during use, thereby keeping the thread preload basically constant. The fastening object 2 is provided with a through hole 2-1, and the diameter of the through hole 2-1 is larger than the diameter of the bolt rod 1-2.

[0040] like Figure 2-3As shown, the surface of the inner cone sleeve 1-3 is a cone surface, and the inner cone sleeve 1-3 is provided with a plurality of through grooves 1-4 extending along the axial direction of the inner cone sleeve. The cone angle of the inner cone sleeve 1-3 is 1-20°. The through grooves 1-4 are evenly distributed along the circumferential direction of the inner cone sleeve 1-3. The through grooves 1-4 make the inner cone sleeve 1-4 deform evenly in the radial direction within a certain range, thereby eliminating the gap between the external thread on the bolt rod 1-2 and the internal thread of the fixing seat 3, and increasing the fitting area and locking friction.

[0041] like Figure 2 , 5 As shown, the cross-sectional circular diameter of the cylindrical rod 4-2 is larger than the cross-sectional circular diameter of the cambered rod 4-1, and the end surface of the cylindrical rod 4-2 close to the cambered rod 4-1 is parallel to the outer end surface of the inner conical sleeve 1-3 and has a gap therebetween.

[0042] like Figure 1-2 As shown in Figures 6-7, the closure assembly includes a mandrel seat 5 and a rear cover plate 6 that are fixedly connected, and an inner hole 5-1 is provided inside the mandrel seat 5. The rear cover plate 6 is provided with an outer bolt hole 6-1, and the mandrel seat 5 and the fixing seat 3 are both provided with an inner bolt hole 5-2 corresponding to the outer bolt hole 6-1, so that the rear cover plate 6, the mandrel seat 5 and the fixing seat 3 are bolted. In addition, the rear cover plate 6 and the mandrel seat 5, and the mandrel seat 5 and the fixing seat 3 can also be fixedly connected by welding.

[0043] like Figure 2 As shown, the cross-sectional diameter of the cylindrical rod 4-2 is smaller than the diameter of the inner hole 5-1 of the top rod seat 5, so that the cylindrical rod 4-2 can float in the radial direction and eliminate the influence of errors.

[0044] like Figure 1-5As shown, during installation, the bolt rod 1-2 of the tapered bolt 1 is passed through the bolt rod disc spring 8 and the through hole 2-1 of the fastening object 2 in sequence, and then the bolt head 1-1 is rotated so that the thread on the bolt rod 1-2 matches the internal thread of the fixing seat 3, and the tapered bolt 1 moves to the left. The bolt head 1-1 is continued to be rotated so that the inner tapered sleeve 1-4 contacts the arc surface 4-3 of the arc surface rod 4-1. While the tapered bolt 1 compresses the bolt rod disc spring 8, the arc surface push rod 4 overcomes the elastic force of the push rod disc spring 7, thereby driving the arc surface push rod 4 to move to the left together. The locking torque applied during rotation should meet the requirements of the specification. At this time, the inner cone sleeve 1-4 is subjected to both the axial force given by the locking force and the elastic force of the push rod disc spring 7, and the reaction force given by the arc surface 4-3 (which can be decomposed into axial force and radial force). The radial force is several times the axial force. The tail of the tapered bolt 1 is a cantilever beam structure, which is deformed to form an undercut structure to prevent the thread from moving to the right and prevent loosening. At the same time, during the installation process, the inner cone sleeve 1-3 is deformed radially within a certain range, eliminating the gap between the threads, so that the outer thread of the tapered bolt 1 and the inner thread of the fixing seat 3 are tightly fitted together, increasing the fitting area of ​​the inner cone sleeve 1-3 and the fixing seat 3, thereby greatly increasing the thread locking force and playing an anti-loosening and locking role. After the tapered bolt 1 is installed, the anti-loosening effect is good.

[0045] like Figure 1-5 As shown, the constant force self-tightening anti-loosening bolt provided by the present invention, in addition to adopting the above-mentioned undercut structure for anti-loosening locking, also adopts the principle of expansion screws, combines the wedge-shaped force-enhancing structure with through grooves 1-4 and the spring structure, and the axial preload force remains unchanged while the radial preload force increases exponentially. Different from other traditional structures, due to the presence of the through grooves 1-4, the front end of the inner cone sleeve 1-3 is easily deformed as a whole under the action of the radial preload force, and at the same time, the internal thread on the fixing seat 3 matches the external thread on the tapered bolt 1 (the thread shape and pitch are completely consistent), thereby effectively eliminating the axial gap and radial gap between the bolt and the nut, so that the actual contact area between the bolt and the nut is significantly increased, and the reliability of thread locking is increased, which can avoid excessive local wear and damage between the locking surfaces during disassembly. The locking force does not change significantly after disassembly for more than 50 times and can continue to be used; the spring structure can provide a constant and lasting preload force, and the anti-loosening effect is better in occasions with large vibration and temperature changes.

[0046] The performance of the Hard Lock anti-loosening nut and the constant force self-tightening anti-loosening bolt provided by the present invention was tested. The test equipment adopted an Ambunec lateral vibration testing machine. The test frequency was 12.5 Hz, the lubrication condition was engine oil, the number of vibrations was 1500 times, and the results are shown in Table 1. The numbers on the left side of the “ / ” sign in the table are the initial axial force or installation torque of the convex nut, and the numbers on the right side are the initial axial force or installation torque of the concave nut.

[0047] Table 1 Performance test data of Hard Lock anti-loosening nuts and constant force self-tightening anti-loosening bolts

[0048] sample Hard Lock Nut Constant force self-tightening anti-loosening bolt Initial axial force (kN) 13.8 / 21.6 75.5 30-second axial force (kN) 18.5 69.2 60 sec axial force (kN) 18.0 68.8 90 sec axial force (kN) 17.7 68.6 120 sec axial force (kN) 17.3 68.2 Residual / initial (%) 80.1 90.3 Installation torque (N·m) 42 / 59 252

[0049] The internationally accepted core anti-loosening index is: residual / initial (%), i.e. residual preload / initial preload) (%). In practical applications, residual / initial (%) greater than 80 is excellent, 80-50 is good, and occasions with anti-loosening requirements generally require residual / initial (%) greater than 75. As can be seen from Table 1, the residual / initial (%) of the constant force self-tightening anti-loosening bolt provided by the present invention is 90.3, far exceeding the excellent standard of 80, and greater than 80.1 of the Hard Lock anti-loosening nut.

[0050] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A constant force self-tightening anti-loosening bolt, characterized in that: It includes a fixing seat, a closing assembly, a tapered bolt and a curved ejector rod, and also includes an ejector rod disc spring; The fixing seat and the closing component are fixedly connected, a threaded through hole is provided inside the fixing seat, and the closing component is provided with an inner hole connected to the threaded through hole; The tapered bolt comprises a bolt head, a bolt rod and an inner tapered sleeve which are fixedly connected in sequence, the tapered bolt passes through the threaded through hole, and one end of the inner tapered sleeve extends into the inner hole; The arc surface push rod comprises a cylindrical rod and an arc surface rod which are fixedly connected. The outer surface of the arc surface rod is an arc surface. The arc surface push rod is arranged in the inner hole, and one end of the arc surface rod is clamped in the inner cone sleeve. The cross-sectional circular diameter of the cylindrical rod is smaller than the diameter of the inner hole, so that the cylindrical rod can float in the radial direction. The push rod disc spring is arranged in the inner hole of the closing component and contacts the cylindrical rod of the arc push rod.

2. The constant force self-tightening anti-loosening bolt according to claim 1, characterized in that: The outer surfaces of the bolt rod and the inner conical sleeve are both provided with external threads, and the threaded through hole of the fixing seat is provided with internal threads matching the external threads.

3. The constant force self-tightening anti-loosening bolt according to claim 1, characterized in that: It also includes a bolt rod disc spring, which is installed between a bolt head of the bolt rod and a fastening object.

4. The constant force self-tightening anti-loosening bolt according to claim 1, characterized in that: The surface of the inner cone sleeve is a cone surface, and the inner cone sleeve is provided with a plurality of through grooves extending along the axial direction of the inner cone sleeve.

5. The constant force self-tightening anti-loosening bolt according to claim 4, characterized in that: The cone angle of the inner cone sleeve is 1-20 degrees, and the through grooves are evenly distributed along the circumferential direction of the inner cone sleeve.

6. The constant force self-tightening anti-loosening bolt according to claim 1, characterized in that: The cross-sectional circular diameter of the cylindrical rod is larger than the cross-sectional circular diameter of the cambered rod, and the end surface of the cylindrical rod close to the cambered rod is parallel to the outer end surface of the inner conical sleeve and has a gap therebetween.

7. The constant force self-tightening anti-loosening bolt according to claim 1, characterized in that: The closing assembly comprises a mandrel seat and a rear cover plate which are fixedly connected, and the inner hole is arranged inside the mandrel seat.

8. The constant force self-tightening anti-loosening bolt according to claim 7, characterized in that: The rear cover plate is provided with an outer bolt hole, and the push rod seat and the fixing seat are both provided with an inner bolt hole corresponding to the outer bolt hole, so that the rear cover plate, the push rod seat and the fixing seat are bolted together.

9. The constant force self-tightening anti-loosening bolt according to claim 7, characterized in that: The rear cover plate and the push rod seat, as well as the push rod seat and the fixing seat are fixedly connected by welding.

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