Self-locking one-way high-strength bolt of anti-loosening type

Abstract

The present application relates to steel structure connecting technical field, disclose a kind of anti-loose type self-locking unidirectional high-strength bolt, including the screw rod with bolt head and threaded end, and steel washer, rubber washer, slotted sleeve and conical nut threaded connection in threaded end are successively set on screw rod.Slotted sleeve is equipped with several notches, and the expansion petals that can be radially opened are formed between adjacent notches;Friction part is provided on the outer periphery of conical nut, for limiting its relative rotation and allowing axial movement Slotted sleeve.When screwing bolt head, conical nut is fed along the axial direction of screw rod and wedged into slotted sleeve, and drives the expansion petals to be opened on the blind side of the connected component to form support, and together with steel washer, it is pre-tightening force that is formed by clamping component.Conical nut can be provided with wedge-shaped anti-loose internal thread, to generate radial compression force in pre-tightening state, increase the resistance to reverse rotation of threaded pair, so as to be suitable for unilateral installation connection of closed or semi-closed steel structure component.

Description

Technical Field

[0001] This invention relates to the field of steel structure connection technology, and in particular to a loosening-resistant self-locking unidirectional high-strength bolt. Background Technology

[0002] In steel structure engineering, H-beams often require high-strength bolts to reliably connect with rectangular steel columns, box columns, box beams, and other closed-section members. For ordinary bolt connections, it is typically necessary to tighten the bolt head or nut on one side of the bolt and clamp or provide a reaction force to the opposite member on the other side. When the connected object is a closed or semi-closed member, the internal space of the member may be inaccessible, or the wrench may not be able to reach the blind side due to cross-sectional dimensions, node construction, construction location, etc., making it difficult to install ordinary bolts.

[0003] To address the issue of operation only from one side, unidirectional connectors capable of providing support on the blind side can be used in engineering. These connectors typically create a bearing zone inside the component after passing through the mounting hole via deformable sleeves, expanders, or other radially deployable members, eliminating the need for personnel to enter the component to clamp the nut. While unilateral installation improves the accessibility of closed-section joints, its tightening process introduces new structural requirements: the blind-side expander must reliably deploy within a confined space, the deployment position must be outside the plate thickness or hole depth, and synchronous rotation of the expander and screw must be avoided when applying large preload.

[0004] If the expansion member or the blind-side nut that mates with the screw rotates with the screw during tightening, the screw's rotation cannot be stably converted into axial feed of the blind-side nut, which may result in unstable expansion speed, insufficient expansion amount, or expansion position deviation. Especially in high-strength connections that require large tightening torque, relying solely on the occasional friction between the sleeve and the mounting hole is insufficient to cover the entire process from initial tightening to final pre-tightening.

[0005] On the other hand, after installation, the blind side fasteners of one-way bolts are usually located in an inaccessible position. Once the connection is subjected to long-term vibration, cyclic loads, impact loads, or temperature changes, if relative slippage or reverse rotation occurs in the threaded pair, subsequent maintenance and re-tightening will be limited by the closed cross-sectional space.

[0006] Therefore, it is necessary to provide a non-loosening self-locking unidirectional high-strength bolt to solve the above-mentioned technical problems. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides an anti-loosening self-locking unidirectional high-strength bolt.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a self-locking, anti-loosening unidirectional high-strength bolt, comprising:

[0009] A screw, having a bolt head and a threaded end;

[0010] A steel washer, a rubber washer, and a slotted sleeve are sequentially fitted onto the bolt in the direction from the bolt head to the threaded end; the slotted sleeve has several grooves on its surface, and radially opening flaps are formed between adjacent grooves; and

[0011] A tapered nut, threadedly connected to the threaded end, has a friction part on its outer circumferential surface;

[0012] Wherein, the outer diameter of the end of the tapered nut facing the slotted sleeve is smaller than the inner diameter of the slotted sleeve, and the friction part contacts the inner wall of the slotted sleeve to restrict relative rotation between the two and allow axial relative movement, so that when the bolt head is tightened, the tapered nut moves axially along the screw and weds into the slotted sleeve, driving the expansion flap to open radially inside the connected component and form a blind side support.

[0013] In a preferred embodiment of the present invention, the friction part is a plurality of concave stripes provided around the outer peripheral surface of the conical nut, and the concave stripes extend along the axial direction of the conical nut.

[0014] In a preferred embodiment of the present invention, a plurality of the slots are spaced apart circumferentially along the slotted sleeve, the slots facing the threaded end and extending axially to the through end face.

[0015] In a preferred embodiment of the present invention, after the expansion flap is radially opened, the outer diameter of the slotted sleeve is increased, forming a blind side support portion that abuts against the blind side surface of the connected component.

[0016] In a preferred embodiment of the present invention, the outer periphery of the steel washer is provided with a plurality of circumferentially distributed protrusions, which are used to cooperate with the reaction force component of the fastening tool to limit the steel washer from rotating with the screw during the fastening process.

[0017] In a preferred embodiment of the present invention, the outer periphery of the steel washer is provided with two symmetrical straight edges, which are used to cooperate with the reaction force component of the fastening tool to limit the steel washer from rotating with the screw during the fastening process.

[0018] In a preferred embodiment of the present invention, the rubber gasket is sandwiched between the steel gasket and the slotted sleeve, and forms frictional contact with the steel gasket and the slotted sleeve respectively under axial compression, so as to transmit the circumferential constraint force on the steel gasket to the slotted sleeve.

[0019] In a preferred embodiment of the present invention, when the slotted sleeve is inserted into the mounting hole of the connected component, a portion of the outer peripheral surface of the slotted sleeve is used to contact the hole wall of the mounting hole, so as to form a circumferential constraint on the slotted sleeve through the contact friction between the two.

[0020] In a preferred embodiment of the present invention, the internal thread of the tapered nut is a wedge-shaped anti-loosening internal thread, and the root region of the wedge-shaped anti-loosening internal thread is provided with a wedge-shaped pressure-bearing part, and the wedge-shaped pressure-bearing part has a pressure-bearing surface that is inclined relative to the screw axis;

[0021] When the unidirectional high-strength bolt forms a preload, the crest of the external thread of the bolt presses against the bearing surface, so that the external thread of the bolt and the wedge-shaped anti-loosening internal thread of the tapered nut generate a radial clamping force.

[0022] A method for using a self-locking, anti-loosening, unidirectional high-strength bolt includes:

[0023] The unidirectional high-strength bolt is passed through the mounting hole from the outside of the connected component, so that the expansion flap of the slotted sleeve and the conical nut are located on the blind side of the connected component.

[0024] Tighten the bolt head so that the friction part of the conical nut contacts the inner wall of the slotted sleeve, restricting their relative rotation, and move the conical nut along the screw axis and wed it into the slotted sleeve, causing the expansion flap to open radially to form a blind side support;

[0025] Continue to tighten the bolt head so that the blind side support and the steel washer together clamp the connected components and form a preload.

[0026] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0027] (1) This invention provides a non-loosening self-locking unidirectional high-strength bolt. By feeding the conical nut along the axial direction of the bolt under circumferential constraint, and using the radial component force generated after its conical surface weds into the slotted sleeve to drive the expansion flap to unfold outward, the bolt can be inserted from one side of the component, form blind side support, and axially pre-tighten. This force conversion continuously transforms the rotational input generated by tightening the bolt head into the axial displacement of the blind side nut and the radial expansion of the expansion flap. Compared with the installation method of ordinary bolts that require clamping the nut inside the component, it avoids the problem of not being able to arrange tools inside the closed section. At the same time, it reduces the insufficient expansion or positional displacement of the blind side component caused by the bolt spinning freely, so that the formed blind side bearing area can continuously bear the axial reaction force generated by the pre-tightening force.

[0028] (2) The conical nut of the present invention forms an axially extending anti-rotation fit with the inner wall of the slotted sleeve, which restricts the rotation in the circumferential direction while retaining the ability to move relative to each other in the axial direction. When the screw rotates, the frictional contact between the concave stripes on the outer periphery of the conical nut and the inner wall of the slotted sleeve can withstand the circumferential force, while the axial extension direction of the concave stripes provides a feed channel for the conical nut. Therefore, the anti-rotation structure will not block the wedging stroke. Compared with the random friction of the smooth contact surface that restricts the rotation of the nut, this structure increases the micro-irregularity of the contact surface through the longitudinal concave area of ​​the concave stripes, which can form a more stable circumferential friction constraint, so that the relative rotation generated by the threaded pair is more stably converted into axial displacement, and the multiple expansion petals obtain a more continuous radial expansion effect in the main wedging stroke.

[0029] (3) After the steel washer of the present invention is circumferentially restricted by the fastening tool, the rubber washer increases the contact normal force between itself, the steel washer, and the slotted sleeve under axial compression. This transfers the circumferential reaction force generated on the outside to the slotted sleeve through interface friction. At the same time, the sleeve and the wall of the mounting hole, as well as the expanded flap and the blind side surface after unfolding, form additional friction constraints. Compared with the method of relying solely on the friction between the sleeve and the hole wall to prevent rotation, this reaction force transmission path can gradually increase with the degree of tightening, so that the slotted sleeve can still maintain circumferential stability under a large tightening torque, and provide a more stable reaction force basis for the continuous axial feed of the tapered nut.

[0030] (4) The conical nut of the present invention adopts a wedge-shaped anti-loosening internal thread with an inclined bearing surface. After the preload is established, the crest of the external thread of the screw applies a normal contact force to the bearing surface. In addition to transmitting the axial load, this force also generates a radial component, forming an additional radial clamping between the internal and external threads. Compared with ordinary threads that mainly rely on the friction of the thread surface to maintain the locking state, this structure requires overcoming the additional frictional resistance generated by the wedge contact to reverse rotation. Furthermore, this radial clamping increases with the increase of the axial preload, thereby reducing the possibility of relative slippage and reverse rotation of the thread pair under vibration, impact, or cyclic load. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the installation of the unidirectional high-strength bolt of the present invention;

[0033] Figure 2 This is a schematic diagram of the unidirectional high-strength bolt structure of the present invention;

[0034] Figure 3 This is a schematic diagram of the installation state after the unidirectional high-strength bolt of the present invention passes through the connected components and forms an expansion support on the blind side;

[0035] Figure 4 This is a schematic diagram of a toothed steel washer structure;

[0036] Figure 5 This is a schematic diagram of a straight-edge steel washer structure;

[0037] Figure 6 This is a diagram showing the installation steps for unidirectional high-strength bolts;

[0038] Figure 7 This is a partial axial schematic diagram of a wedge-shaped anti-loosening thread;

[0039] In the diagram: 1. Screw; 11. Bolt head; 12. Threaded end; 2. Steel washer; 21. Raised tooth; 22. Straight edge; 3. Rubber washer; 4. Slit sleeve; 41. Groove; 42. Expansion flap; 5. Tapered nut; 51. Friction part; 52. Wedge-shaped anti-loosening internal thread; 522. Wedge-shaped pressure bearing part; 6. Connected component; 61. Mounting hole; 62. Blind side surface. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0042] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] Example 1:

[0045] like Figure 1 and Figure 2 As shown, the anti-loosening self-locking unidirectional high-strength bolt of this embodiment includes: a screw 1, a steel washer 2, a rubber washer 3, a slotted sleeve 4, and a conical nut 5. One end of the screw 1 forms a bolt head 11, and the other end forms a threaded end 12 with external threads. The steel washer 2, the rubber washer 3, and the slotted sleeve 4 are sequentially fitted onto the outside of the screw 1, and the conical nut 5 is screwed onto the threaded end 12.

[0046] Specifically, the bolt head 11 can be an external hexagonal head, other polygonal heads, or a drive structure that can transmit tightening torque, which is easy to drive with a power wrench or manual wrench; without changing the working principle of the present invention, the specific shape of the bolt head can be determined according to the matching tools.

[0047] Furthermore, the slotted sleeve 4 is a hollow sleeve extending along the screw axis, including a relatively complete cylindrical part and a slotted end near the threaded end 12; the slotted end is provided with a number of slots 41 in the circumferential direction, each slot 41 extending axially from the end face near the conical nut 5 towards the bolt head 11, and an expansion flap 42 is formed between adjacent slots 41.

[0048] The number of slots 41 should preferably form four or more expansion petals 42 that can independently generate radial displacement. In specific implementation, four, six or other numbers can be selected according to the sleeve diameter, material plasticity, required unfolding profile and load-bearing requirements. The multiple slots 41 are preferably distributed basically evenly along the circumference so that the multiple expansion petals 42 can open outward in a more balanced manner under the action of the conical nut.

[0049] The conical nut 5 has an internal thread at its center, which forms a threaded pair with the threaded end 12 of the screw 1. The outer circumferential surface of the conical nut 5 is provided with a friction part 51, and the outer diameter of the end of the conical nut 5 facing the slotted sleeve 4 is smaller than the inner diameter of the slotted sleeve 4. When not tightened, the conical nut 5 is located outside the slotted end of the slotted sleeve 4 or in a position where it has only initially entered the slotted sleeve 4, and the multiple expansion flaps 42 are in a retracted state. At this time, the maximum outer diameter of the slotted sleeve 4 at the slotted end is not greater than the outer contour allowed by it passing through the mounting hole 61, so that the entire blind side assembly can pass through the connected component 6 from the operating side.

[0050] like Figure 4 and Figure 5 As shown, during installation, the screw 1, along with the steel washer 2, rubber washer 3, slotted sleeve 4, and tapered nut 5, is inserted into the mounting hole 61 from the outside of the component 6 being connected. The slotted sleeve 4 is at least partially located within the mounting hole 61, with the slotted end of the sleeve 4 and the tapered nut 5 extending beyond the mounting hole 61 into the blind side. After tightening the bolt head 11, the tapered nut 5 experiences circumferential resistance due to the contact friction between the friction part 51 and the inner wall of the slotted sleeve 4. Because the slotted sleeve 4 itself is constrained by the wall of the mounting hole 61 and the reaction force transmission from the steel washer 2 and rubber washer 3, the tapered nut 5 does not easily rotate synchronously with the screw 1, resulting in relative rotation between the screw 1 and the tapered nut 5.

[0051] The threaded pair converts the relative rotation into the movement of the conical nut 5 along the axial direction of the screw 1. The conical nut 5 with the smaller outer diameter enters the slotted sleeve 4 first and gradually wedges in as it is fed axially. The normal force generated by the contact between the outer periphery of the conical nut 5 and the inner wall of the slotted sleeve 4 has a radially outward component. This radial component acts on the expansion flap 42, causing the expansion flap 42 to open outward around the area near the root of the slot 41. The friction part 51 maintains effective contact with the inner wall of the slotted sleeve 4 during the axial movement, but this contact does not form a rigid axial lock on the conical nut 5. The conical nut 5 can still continue to be fed under the axial driving force generated by the threaded pair.

[0052] As the expansion flaps 42 open, the outer contour of the blind side of the slotted sleeve 4 gradually exceeds the edge of the mounting hole 61. Multiple expansion flaps 42 eventually form a blind side support facing the bolt head 11, abutting against the blind side surface 62 of the connected component 6. Subsequently, as the bolt head 11 continues to be tightened, the tapered nut 5 continues to generate axial feed, and the distance between the blind side support and the steel washer 2 located on the operating side relatively decreases, clamping the connected component 6 and establishing axial tension in the screw 1. In actual design, the unfolded size of the expansion flaps 42 should be sufficient to exceed the edge of the mounting hole 61 to form an effective bearing area, while ensuring that the expansion flap material, thickness, and groove root have strength matching the designed clamping force.

[0053] Regarding dimensional relationships, this embodiment does not require implementation with a fixed set of values, but three basic conditions must be met: First, the slotted sleeve 4 when the expansion flap 42 is not open can pass through the mounting hole 61; second, the portion of the slotted sleeve 4 located in the mounting hole 61 can establish contact with the hole wall or establish contact after being subjected to bias pressure, thereby providing initial frictional constraint; third, the outward profile of the expansion flap 42 after opening exceeds the edge of the mounting hole 61, so that the formed blind side support can withstand the axial reaction force generated by the preload. For unidirectional high-strength bolts of different nominal diameters, the sleeve outer diameter, wall thickness, groove length, and effective stroke of the tapered nut 5 can be determined proportionally or according to the above relationships or the load-bearing design.

[0054] Example 2:

[0055] This embodiment further explains the anti-rotation fit between the conical nut 5 and the slotted sleeve 4. A friction part 51 is provided on the outer circumferential surface of the conical nut 5. The friction part 51 is located in the effective area where the conical nut 5 can continuously contact the inner wall of the slotted sleeve 4 after entering the slotted sleeve 4. After the friction part 51 contacts the inner wall of the slotted sleeve 4, when the screw 1 rotates and the conical nut 5 tends to rotate due to the thread friction, the contact interface can apply a circumferential friction force to the conical nut 5 in the opposite direction to its rotation.

[0056] In this embodiment, the friction part 51 is preferably composed of a plurality of concave stripes. The concave stripes are provided on the outer peripheral surface of the tapered nut 5 and extend along the axial direction of the tapered nut 5. The plurality of concave stripes can be distributed circumferentially at intervals, so that the outer periphery of the tapered nut 5 forms a plurality of longitudinally recessed areas, preferably in a sawtooth shape. The axial extension direction of the concave stripes is consistent with the main feed direction of the tapered nut 5. Therefore, when the tapered nut 5 moves into the slotted sleeve 4 under the side effect of the thread, the concave stripes can slide axially along the inner wall of the slotted sleeve 4.

[0057] Even without the concave stripes, the friction part 51 can still directly form frictional contact with the inner wall of the slotted sleeve 4 and provide circumferential resistance. The concave stripes are a preferred further limitation, their function being to increase the microscopic irregularity of the contact surface based on frictional contact, thereby improving the stability and repeatability of the circumferential resistance. Regardless of the fit used, the axial feed of the tapered nut 5 is generated by the threaded pair between the screw 1 and the tapered nut 5, and its axial driving force should be able to overcome the resistance when the friction part 51 slides axially.

[0058] Example 3:

[0059] To ensure the circumferential stability of the slotted sleeve 4 under high tightening torque, this embodiment utilizes the contact between the wall of the mounting hole 61, the steel washer 2, the rubber washer 3, and the expansion flap 42 with the blind side surface 62 to form a progressive anti-rotation mechanism. This anti-rotation mechanism does not require each constraint source to work strictly in sequence and individually, but rather it is gradually established and superimposed on each other as the tightening degree changes.

[0060] During initial installation, the slotted sleeve 4 is at least partially inserted into the mounting hole 61. The outer circumferential surface of the slotted sleeve 4 within the hole contacts the wall of the mounting hole 61, or, when assembly clearance exists, it partially contacts the hole wall due to the weight of the bolt, construction eccentric load, or initial stress. Friction is generated at the contact interface, giving the slotted sleeve 4 a basic circumferential resistance. This resistance helps prevent the slotted sleeve 4 from spinning freely during the initial tightening stage and provides a reaction force basis for the friction part 51 of the tapered nut 5 to play its anti-rotation role.

[0061] like Figure 4As shown, the steel washer 2 is located on one side of the bolt head 11, and its outer circumference forms multiple circumferentially distributed protrusions 21. For example... Figure 6 As shown, the fastening tools used during installation include an electric wrench and a reaction component. The electric wrench serves as the driving component, while the reaction component has a shape similar to a regular wrench, but its contact surface with the steel washer 2 has a meshing surface that matches the teeth 21. The electric wrench engages with the bolt head 11 to apply rotational torque to the screw 1. The reaction component engages with the teeth 21 of the steel washer 2, restricting the steel washer 2 from rotating with the screw 1 through clamping, abutting, or meshing. Thus, the reaction force of the driving torque on the screw 1 can be borne by the steel washer 2, eliminating the need for a reaction tool to be installed on the blind side of the closed-section member.

[0062] like Figure 5 As shown, in another embodiment, the outer periphery of the steel washer 2 forms two symmetrically distributed straight edges 22. During installation, a regular wrench can be used to hold the straight edges 22 to fix the steel washer 2.

[0063] The rubber washer 3 is located between the steel washer 2 and the slotted sleeve 4. During the tightening process, the axial distance between the steel washer 2 and the slotted sleeve 4 gradually decreases, and the rubber washer 3 is compressed. As the degree of compression increases, the contact normal force between the rubber washer 3 and the steel washer 2 and the slotted sleeve 4 increases, and the circumferential friction force that can be transmitted between the two contact interfaces increases accordingly. The circumferential constraint applied to the steel washer 2 by the reaction component is thus transmitted to the slotted sleeve 4 through the rubber washer 3, forming a reaction force transmission chain from the outer tool to the blind-side expansion sleeve.

[0064] When the slotted sleeve 4 is constrained by both the friction of the bore wall and the transmission of the tool reaction force, the friction part 51 between the tapered nut 5 and the slotted sleeve 4 can obtain a more stable relative reaction force. When the screw 1 rotates, the tapered nut 5 tends to rotate with it, and the friction part 51 transmits this tendency to the slotted sleeve 4; the slotted sleeve 4 then transmits the reaction force to the connected component 6 and the fastening tool 8 through the above two types of constraints. Therefore, the tapered nut 5 tends to maintain its circumferential position and move axially along the screw 1.

[0065] As the conical nut 5 is wedged in, the expansion flap 42 gradually opens outward. Once the expansion flap 42 begins to abut against the blind side surface 62, its contact normal force increases with continued tightening. This blind side contact not only bears the final axial clamping force but also increases the frictional resistance that the slotted sleeve 4 must overcome when it rotates circumferentially relative to the connected component 6. Therefore, as it approaches the design preload, the slotted sleeve 4 itself gains stronger self-restraint, and its anti-rotation capability increases with the degree of tightening.

[0066] In summary, during the initial tightening stage, basic constraints are established primarily through the contact friction between the slotted sleeve 4 and the wall of the mounting hole 61. As the tool is positioned and axial pressure is generated, the reaction force transmission between the steel washer 2, the rubber washer 3, and the slotted sleeve 4 is enhanced. After the expansion flap 42 abuts against the blind side surface 62, the blind side provides self-reinforcing friction. This structure ensures that the entire process does not rely on a single source of friction and also allows the anti-rotation effect of the outer peripheral friction part 51 of the tapered nut 5 to extend throughout the main wedging stroke.

[0067] Example 4:

[0068] This embodiment, based on the above embodiment, further defines the threaded fit structure between the tapered nut 5 and the screw 1. For example... Figure 7 As shown, the inner hole of the conical nut 5 is provided with a wedge-shaped anti-loosening internal thread 52, and the threaded end 12 of the screw 1 is provided with an external thread that engages with the wedge-shaped anti-loosening internal thread 52.

[0069] In this embodiment, the external thread of the screw 1 adopts a helical thread profile with an external thread crest, a load-bearing side thread surface, a non-load-bearing side thread surface, and a thread root. The wedge-shaped anti-loosening internal thread 52 of the conical nut 5 includes an internal thread crest, a load-bearing side thread surface, a non-load-bearing side thread surface, and a thread root region located between adjacent thread surfaces.

[0070] Unlike ordinary internal threads, a wedge-shaped bearing portion 522 is provided at the root of the wedge-shaped anti-loosening internal thread 52 near the bearing side tooth surface. The wedge-shaped bearing portion 522 extends continuously along the helical direction of the wedge-shaped anti-loosening internal thread 52, so that each turn of the internal thread participating in the bearing has a corresponding wedge-shaped bearing area.

[0071] In an axial section passing through the axis of screw 1, the wedge-shaped bearing portion 522 is characterized as a wedge-shaped bearing surface inclined relative to the axis of screw 1. One side of the wedge-shaped bearing surface is connected to the root of the internal thread, and the other side extends toward the bearing side tooth surface of the internal thread, thereby forming an inclined bearing area between the root of the internal thread and the bearing side tooth surface for mating with the crest of the external thread of screw 1.

[0072] In one specific embodiment, the bearing surface of the wedge-shaped bearing portion 522 forms an acute angle α with the axis of the screw 1, wherein the acute angle α can be approximately 30°. The wedge-shaped bearing portion 522 preferably uses a rounded or rounded transition with the root of the internal thread and the bearing side thread surface to avoid sharp corners in the bearing area and reduce local stress concentration.

[0073] After the external thread of the screw 1 engages with the wedge-shaped anti-loosening internal thread 52, when no axial preload is generated or the preload is small, a radial assembly clearance is left between the crest of the external thread of the screw 1 and the wedge-shaped bearing portion 522 to allow normal engagement of the threaded pair. At this time, the tapered nut 5 can move axially along the screw 1 with the relative rotation of the threaded pair, and will not lock before the tapered nut 5 has completed axial wedging due to the setting of the wedge-shaped bearing portion 522.

[0074] As the bolt head 11 continues to be tightened, the conical nut 5 enters the slotted sleeve 4 axially along the screw 1, causing the expansion flap 42 to open radially. When the expansion flap 42 abuts against the blind side surface 62 of the connected component 6, the bolt head 11 continues to be tightened, causing the screw 1 to be subjected to axial tension and the conical nut 5 to be subjected to an axial reaction force in the opposite direction, thereby establishing an axial preload between the screw 1 and the conical nut 5.

[0075] Under the axial preload, the relative axial force between the external thread of the screw 1 and the wedge-shaped anti-loosening internal thread 52 increases, and the crest of the external thread of the screw 1 or the outer edge of the adjacent crest gradually presses against the bearing surface of the wedge-shaped bearing portion 522. Since the wedge-shaped bearing portion 522 is inclined relative to the axis of the screw 1, the contact force of the external thread crest acting on the wedge-shaped bearing portion 522 is transmitted along the normal direction of the wedge-shaped bearing surface. This normal contact force has both axial and radial components.

[0076] The axial component is used to transmit the axial preload between the screw 1 and the tapered nut 5; the radial component causes the external thread of the screw 1 and the wedge-shaped anti-loosening internal thread 52 of the tapered nut 5 to press against each other radially, so that a large radial contact pressure is formed between the thread teeth that participate in the load.

[0077] Ordinary threads primarily transmit axial loads through corresponding thread surfaces. However, this embodiment further utilizes the wedge-shaped contact formed between the external thread crest and the wedge-shaped bearing portion 522 to convert part of the axial load into a radial compressive load. As the preload of the unidirectional high-strength bolt increases, the resistance force of the external thread crest on the wedge-shaped bearing portion 522 increases synchronously, and the radial compressive strength between the threaded pairs increases accordingly.

[0078] When the connecting structure is subjected to vibration, impact, or cyclic load, causing the tapered nut 5 to tend to rotate in the opposite direction relative to the screw 1, it is necessary to simultaneously overcome the frictional resistance of the normal bearing contact surfaces of the internal and external threads, as well as the frictional resistance formed by radial compression between the external thread crest and the wedge-shaped bearing portion 522. Therefore, without additional locking elements provided from the blind side of the closed section member 6, the resistance to the reverse rotation of the tapered nut 5 relative to the screw 1 can be increased.

[0079] To ensure that the wedge-shaped anti-loosening internal thread 52 can engage normally in the early stage of tightening and exert a wedging effect after the preload is formed, the radial position of the wedge-shaped bearing portion 522 should match the tooth crest position of the external thread of the screw 1. In the unloaded state, the clearance required for manufacturing and engagement is allowed between the two; after the predetermined axial load is reached, the elastic deformation of the thread teeth and the change in the bearing position between the internal and external threads allow the tooth crest of the external thread to enter the effective bearing area of ​​the wedge-shaped bearing portion 522.

[0080] In terms of machining, the central threaded hole of the tapered nut 5 can be machined using a special tap corresponding to the tooth profile of the wedge-shaped anti-loosening internal thread 52, so that the wedge-shaped bearing portion 522 and the internal thread are continuously formed along the same pitch; other cutting, forming, or rolling machining methods that can form the same internal thread profile can also be used. The external thread of the screw 1 does not need to have the same wedge-shaped tooth root structure as the wedge-shaped bearing portion 522; it is only necessary to ensure that the crest of the external thread can enter and press against the effective bearing area of ​​the wedge-shaped bearing portion 522 in the pre-tightened state.

[0081] Example 5:

[0082] like Figure 3 As shown, this embodiment uses the connection between the end plate of an H-beam and a rectangular steel pipe column, box column, or other closed-section member as an example to illustrate the installation method. First, corresponding mounting holes 61 are machined on the member being connected 6 and the connecting plate that fits therewith, so that the mounting holes allow the slotted sleeve 4 and the tapered nut 5 to pass through when the expansion flap 42 is closed.

[0083] The unidirectional high-strength bolt is inserted into the mounting hole 61 from the operable side of the node, so that the steel washer 2 is located outside the connected component 6, and the slotted sleeve 4 is at least partially located in the mounting hole 61, with the expansion flap 42 and the conical nut 5 extending beyond the mounting hole 61 and located on the blind side. At this time, the conical nut 5 is still not fully wedged in, and the expansion flap 42 remains closed to ensure that the insertion process is not significantly interfered with.

[0084] The electric wrench is engaged with the bolt head 11, causing the reaction component to engage with the outer peripheral teeth 21 or straight edge 22 of the steel washer 2. The reaction component applies a circumferential reaction force to the steel washer 2, and the constraint on the steel washer 2 is transmitted to the slotted sleeve 4 through the axially compressed rubber washer 3. At the same time, the outer peripheral surface of the slotted sleeve 4 located in the mounting hole 61 contacts the hole wall, and the contact friction forms a basic circumferential constraint on the slotted sleeve 4.

[0085] Start the electric wrench to tighten the bolt head 11. The screw 1 rotates around its own axis, and the tapered nut 5 experiences circumferential resistance due to the contact between the friction part 51 and the inner wall of the slotted sleeve 4. Under the condition that the slotted sleeve 4 is restricted by the hole wall and the tool reaction force, the tapered nut 5 is not easy to rotate relative to the slotted sleeve 4, but a relative rotation occurs between the screw 1 and the tapered nut 5. The threaded pair converts this relative rotation into the movement of the tapered nut 5 along the axial direction of the screw 1 into the slotted sleeve 4.

[0086] When the preferred structure with concave stripes is adopted, the concave stripes slide axially along the inner wall of the slotted sleeve 4, and the frictional contact between the concave stripes and the inner wall of the slotted sleeve 4 further restricts the rotation of the conical nut 5 relative to the slotted sleeve 4. The smaller outer diameter end of the conical nut 5 enters first, and then the larger outer diameter area gradually acts on the inner wall of the slotted sleeve 4 and the expansion flaps 42, generating a radially outward component force, causing the multiple expansion flaps 42 to open outward synchronously or nearly synchronously.

[0087] As tightening continues, the outward profile of the expansion flap 42 extends beyond the edge of the mounting hole 61 and abuts against the blind side surface 62. Once the abutment is established, the friction between the expansion flap 42 and the blind side surface 62 further enhances the circumferential constraint of the slotted sleeve 4, increasing the sleeve's anti-rotation capability with the tightening degree. Subsequently, as tightening torque continues to be applied, the blind side support and the outer steel washer 2 together clamp the connected component 6 and the connecting plate located therebetween, gradually forming the axial preload required by the design in the screw 1.

[0088] When the tapered nut 5 is equipped with a wedge-shaped anti-loosening internal thread 52, after reaching the pre-tightened state, the crest of the external thread of the screw 1 presses against the bearing surface of the wedge-shaped bearing part 522. The resulting contact normal force has a radial component, causing the external thread of the screw 1 and the wedge-shaped anti-loosening internal thread 52 of the tapered nut 5 to be radially pressed together. This increases the frictional resistance that needs to be overcome when the threaded pair experiences relative slippage and reverse rotation. After tightening, the tightening tool 8 is removed. The blind side support, threaded connection, and anti-loosening structure are all retained inside the closed section member, eliminating the need for additional operations from the blind side.

[0089] During the installation process, the anti-rotation constraint of the slotted sleeve 4 gradually increases with the tightening process: initially, the contact friction between the mounting hole 61 wall and the slotted sleeve 4 provides initial circumferential constraint; during tightening, the tightening tool 8 transmits circumferential reaction force to the slotted sleeve 4 through the steel washer 2 and the rubber washer 3; after the expansion flap 42 abuts against the blind side surface 62, its contact friction further enhances the circumferential constraint of the slotted sleeve 4. The above actions together restrict the rotation of the slotted sleeve 4, enabling the friction part 51 of the tapered nut 5 to restrict its rotation relative to the slotted sleeve 4 and maintain axial feed under the side effects of the thread until blind side support and pre-tightened connection are formed.

[0090] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A type of anti-loosening self-locking unidirectional high-strength bolt, characterized in that, include: A screw, having a bolt head and a threaded end; A steel washer, a rubber washer, and a slotted sleeve are sequentially fitted onto the bolt in the direction from the bolt head to the threaded end; the slotted sleeve has several grooves on its surface, and radially opening flaps are formed between adjacent grooves; and A tapered nut, threadedly connected to the threaded end, has a friction part on its outer circumferential surface; Wherein, the outer diameter of the end of the tapered nut facing the slotted sleeve is smaller than the inner diameter of the slotted sleeve, and the friction part contacts the inner wall of the slotted sleeve to restrict relative rotation between the two and allow axial relative movement, so that when the bolt head is tightened, the tapered nut moves axially along the screw and weds into the slotted sleeve, driving the expansion flap to open radially inside the connected component and form a blind side support.

2. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, The friction part consists of several concave stripes arranged around the outer peripheral surface of the conical nut, and the concave stripes extend along the axial direction of the conical nut.

3. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, A plurality of the slots are spaced apart circumferentially along the slotted sleeve, the slots facing the threaded end and extending axially to the through end face.

4. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, After the expansion flap opens radially, it increases the outer diameter of the slotted sleeve, forming a blind side support portion that abuts against the blind side surface of the connected component.

5. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, The outer circumference of the steel washer is provided with a plurality of circumferentially distributed protrusions. The protrusions are used to cooperate with the reaction force component of the fastening tool to limit the steel washer from rotating with the screw during the fastening process.

6. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, The steel washer has two symmetrical straight edges on its outer periphery. These straight edges are used to cooperate with the reaction force component of the fastening tool to limit the steel washer from rotating with the screw during the fastening process.

7. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, The rubber gasket is sandwiched between the steel gasket and the slotted sleeve, and in the axially compressed state, it forms frictional contact with the steel gasket and the slotted sleeve respectively, so as to transfer the circumferential constraint force on the steel gasket to the slotted sleeve.

8. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, When the slotted sleeve is inserted into the mounting hole of the connected component, part of the outer peripheral surface of the slotted sleeve is used to contact the hole wall of the mounting hole, so as to form a circumferential constraint on the slotted sleeve through the contact friction between the two.

9. The anti-loosening self-locking unidirectional high-strength bolt according to claim 1, characterized in that, The internal thread of the tapered nut is a wedge-shaped anti-loosening internal thread, and the root region of the wedge-shaped anti-loosening internal thread is provided with a wedge-shaped pressure bearing part, which has a pressure bearing surface that is inclined relative to the screw axis; When the one-way bolt generates preload, the crest of the external thread of the screw presses against the bearing surface, so that the external thread of the screw and the wedge-shaped anti-loosening internal thread of the tapered nut generate radial clamping force.

10. A method of using a self-locking, anti-loosening unidirectional high-strength bolt, based on any one of claims 1-9, characterized in that, include: The unidirectional high-strength bolt is passed through the mounting hole from the outside of the connected component, so that the expansion flap of the slotted sleeve and the conical nut are located on the blind side of the connected component. Tighten the bolt head so that the friction part of the conical nut contacts the inner wall of the slotted sleeve, restricting their relative rotation, and move the conical nut along the screw axis and wed it into the slotted sleeve, causing the expansion flap to open radially to form a blind side support; Continue to tighten the bolt head so that the blind side support and the steel washer together clamp the connected components and form a preload.

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