A spigot type single sided bolt fastener and method of installation thereof

Abstract

This invention belongs to the field of fastening component technology and discloses a core-type single-sided bolt fastener and its installation method. The fastener includes an outer sleeve, a central rod, a core cylinder, a rubber ring, and a nut. The outer sleeve includes an outer sleeve body, a conical groove, and an outer sleeve stop block. The central rod is installed inside the outer sleeve and includes a central rod body and a bolt head. The core cylinder is installed between the central rod and the outer sleeve and includes a core cylinder body, a core cylinder mounting block, and a conical end. The installation process first uses the rubber ring to tighten the outer sleeve outside the central rod, then inserts it as a whole into the mounting hole of the connector, and then screws in the core cylinder to expand several identical cylindrical segments of the outer sleeve outward, with the outer sleeve stop block embedded in the limiting groove. Finally, the nut is screwed in outside the outer sleeve, the rubber ring is peeled off, and the nut is tightened. This invention not only solves the problem of single-sided construction of closed-section components but also avoids stress concentration caused by welding or section weakening of the base material caused by on-site drilling in traditional processes.

Description

Technical Field

[0001] This invention belongs to the field of fastening component technology, specifically, it relates to a single-sided bolt fastener. Background Technology

[0002] In conventional bolted connection processes, operators need to work simultaneously from both sides of the component: placing the bolt head on one side and tightening the nut on the other. However, with the widespread use of closed-section components (such as square steel pipe columns and round steel pipes) in modern engineering structures, especially in prefabricated buildings and steel structures, the limitations of this traditional process have become increasingly apparent. For example, at the connection joint between a rectangular steel pipe column and an H-beam, because the inside of the steel pipe is a closed space, operators cannot enter to fix and tighten the nut, making it difficult to directly apply ordinary high-strength bolts. To solve this engineering problem, the industry typically uses welding, on-site manhole drilling, or the use of complex connectors as alternatives in traditional techniques. However, these methods often weaken the cross-section of the base material, increase additional welding stress and deformation, result in low construction efficiency, and make subsequent anti-corrosion treatment difficult, seriously affecting the load-bearing capacity and construction quality of the structure.

[0003] Therefore, there is a need for a fastener that can lock and fix the other side of a component while it is operable on only one side; this is the single-sided bolt. This characteristic makes it highly valuable in many industrial fields, especially in building construction, machinery assembly, bridge engineering, vehicle manufacturing, and shipbuilding. Summary of the Invention

[0004] This invention provides a ferrule-type single-sided bolt fastener that, through the principle of internal mechanical expansion, not only solves the problem of single-sided construction of closed-section components, but also avoids stress concentration caused by welding or on-site drilling that weakens the cross-section of the base material in traditional processes.

[0005] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution:

[0006] According to one aspect of the present invention, a ferrule-type single-sided bolt fastener is provided, comprising an outer sleeve, a center rod, a core sleeve, a rubber ring, and a nut;

[0007] The outer sleeve is composed of several identical cylindrical segments assembled together, and includes an outer sleeve main body, a conical groove, and an outer sleeve stop. The outer sleeve main body, when the cylindrical segments are assembled, is a hollow cylindrical structure, and an outer sleeve thread is provided on the outer side of the outer sleeve main body. The conical groove is located at the first end of the outer sleeve, and the end face of the outer sleeve main body gradually slopes downward from the outside to the inside. The outer sleeve stop is located at the second end of the outer sleeve, and its outer diameter is larger than that of the outer sleeve main body.

[0008] The central rod is used to be installed inside the outer sleeve and includes a central rod body and a bolt head; the outer side of the central rod body is provided with a central rod external thread; the bolt head is located at the second end of the central rod, and its outer diameter is larger than that of the central rod body, and the outer diameter of the bolt head is smaller than the mounting hole of the connector; the bolt head is provided with a plurality of limiting grooves on the outer edge of the surface facing the central rod body, and the plurality of limiting grooves are used to respectively embed the outer sleeve stop block after the expansion of the cylinder assembly;

[0009] The core cylinder is installed between the central rod and the outer sleeve, and includes a core cylinder body, a core cylinder mounting block, and a conical end. The core cylinder body is a hollow cylindrical structure with an internal thread on its inner side. The internal thread of the core cylinder matches the external thread of the central rod, enabling the core cylinder and the central rod to engage through threaded engagement. The core cylinder mounting block is located at the first end of the core cylinder and protrudes relative to the first end face of the core cylinder body, serving as a force-applying part for screwing the core cylinder in. The conical end is located at the second end of the core cylinder and matches the conical groove of the outer sleeve.

[0010] The rubber ring is used to tighten and fix several identical cylinder segments of the outer sleeve to the outside of the central rod before the core cylinder is installed; during this process: the outer diameter of the fastener front end formed by the outer sleeve stop and the bolt head is smaller than the inner diameter of the mounting hole of the connector; the second end of the central rod and the second end of the outer sleeve pass through the mounting hole from the operating side of the connector to the blind side.

[0011] During the installation of the core tube, as the core tube is screwed in, several identical tube segments of the outer sleeve expand outward simultaneously, and the outer sleeve blocks open outward until they are embedded in the limiting groove. As a result, the supporting surface formed by the outer sleeve blocks and the bolt head is larger than the mounting hole of the connector.

[0012] The nut is used to fit over the expanded outer sleeve after the core is installed; the internal thread of the nut matches the thread of the outer sleeve to achieve threaded engagement between the nut and the outer sleeve; after the nut is screwed in and stabilized, the rubber ring is detached from the outer sleeve; after the nut is tightened, the outer sleeve stop is pressed against the blind side surface of the connector under the squeezing action of the bolt head.

[0013] Preferably, the number of tube flap assemblies in the outer sleeve is 3-5.

[0014] Preferably, the two core tube mounting blocks are distributed circumferentially at 180° on the first end face of the core tube body.

[0015] Preferably, a washer is provided between the connector and the nut.

[0016] According to another aspect of the present invention, an installation method based on the above-described insert-type single-sided bolt fastener is provided, comprising:

[0017] (1) The four identical cylinder segments of the central rod and the outer sleeve are pre-assembled using the rubber ring. The rubber ring makes the outer sleeve tight outside the main body of the central rod. The outer sleeve stop is in a retracted state, and the overall diameter of the front end of the fastener formed by the outer sleeve stop and the bolt head is smaller than the mounting hole of the connector.

[0018] (2) Insert the center rod with the rubber ring tightened and the outer sleeve as a whole into the mounting hole of the connector, so that the front end of the fastener composed of the outer sleeve stop block and the bolt head passes through the mounting hole from the operating side of the connector to the blind side;

[0019] (3) Align the conical end of the core tube with the annular gap between the center rod and the outer sleeve, and use the core tube mounting block to screw the core tube between the center rod and the outer sleeve;

[0020] (4) As the core cylinder is screwed in, several identical cylinder segments of the outer sleeve expand outwards simultaneously, and the outer sleeve blocks open outwards to the circumferential side until they are embedded in the limiting groove, thereby forming a stable support plane with the bolt head on the blind side surface of the connector.

[0021] (5) Screw the nut into the outer side of the outer sleeve. After the nut is screwed in and stabilized, peel the rubber ring off the outer sleeve. Continue to screw the nut in until it is tightened. The outer sleeve stop block presses tightly against the blind side surface of the connector under the squeezing action of the bolt head.

[0022] The beneficial effects of this invention are:

[0023] Compared with the prior art, the present invention has the following characteristics:

[0024] (i) The present invention designs a special ferrule expansion system to ensure that the outer sleeve block of the four cylinder components can be forcibly and correctly rotated and unfolded during the installation process, thus avoiding installation failure; the fastener can achieve fast and accurate single-sided fixed connection, solving the engineering problem that closed section components cannot be operated on both sides, and the installation process is simple and reliable, with good mechanical properties and can withstand large load preload.

[0025] (ii) The present invention replaces the traditional bolt head by means of the central rod. The central rod is the core part of the bolt. The limiting groove set in the bolt head makes the outer sleeve block and the bolt head form a whole, which is more conducive to the fastening function of the bolt.

[0026] (iii) The present invention achieves the expansion effect of the bolt head by screwing the core into it. The conical groove of the outer sleeve and the conical end of the core make it easier for the core to be screwed into the single bolt. In addition, the threads of the core and the center rod match each other, making the center rod and the core almost form a whole. Under the tightening action of the nut, the center rod, the core and the outer sleeve form a whole to replace the traditional bolt rod.

[0027] (iv) The present invention achieves pre-assembly and flexible positioning through rubber rings. Compared with conventional welding or hole-opening schemes, it avoids weakening of the cross section of the base material and thermal impact, and maintains the integrity and corrosion resistance of the structure. After installation, the outer sleeve block on the blind side and the bolt head form a multi-point circumferential force, with a large force area and uniform distribution.

[0028] (v) The overall structure of the present invention is simple and compact, and does not require special professional tools. Workers can complete the installation simply by rotating the components, which greatly reduces the difficulty of construction and improves the assembly efficiency. At the same time, the design of the rubber ring effectively prevents the risk of parts falling into the components during the installation process, thus improving construction safety. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention and the prior art, the accompanying drawings used in the description of the specific embodiments will be introduced below, wherein:

[0030] Figure 1 This is a schematic diagram of the structure of the insert-type single-sided bolt fastener of the present invention on the operating side of the connector;

[0031] Figure 2 This is a schematic diagram of the structure of the insert-type single-sided bolt fastener of the present invention on the blind side of the connector;

[0032] Figure 3 This is a schematic diagram of the outer sleeve of the insert-type single-sided bolt fastener of the present invention;

[0033] Figure 4 This is a schematic diagram of the structure of the central rod of the insert-type single-sided bolt fastener of the present invention;

[0034] Figure 5 This is a schematic diagram of the core cylinder structure of the insert-type single-sided bolt fastener of the present invention;

[0035] Figure 6 This is a schematic diagram of the structure of the insert-type single-sided bolt fastener of the present invention before installation;

[0036] Figure 7 This is a schematic diagram of the installation of the insert-type single-sided bolt fastener of the present invention.

[0037] In the above figure: 1. Outer sleeve, 11. Outer sleeve main body, 12. Conical groove, 13. Outer sleeve stop block, 14. Outer sleeve thread; 2. Center rod, 21. Center rod main body, 22. Bolt head, 23. Center rod external thread, 24. Limiting groove; 3. Core tube, 31. Core tube main body, 32. Core tube mounting block, 33. Conical end, 34. Core tube internal thread; 4. Rubber ring; 5. Connector; 6. Nut; 7. Washer. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art described in this application.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when used in this specification, the words “comprising” and / or “including” indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] In this invention, terms such as "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "side," and "bottom" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are merely used to facilitate the description of the structural relationships of the various components or elements of this invention and do not specifically refer to any component or element in this invention. They should not be construed as limitations on this invention.

[0042] In this invention, terms such as "fixed connection," "connected," and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0043] Where there is no conflict, the features in the embodiments of this invention can be combined with each other.

[0044] The following will be based on embodiments of the present invention. Figure 1-7 The technical solutions in the embodiments of the present invention will be clearly explained.

[0045] like Figure 1 and Figure 2 As shown, the insert-type single-sided bolt fastener of this embodiment includes an outer sleeve 1, a center rod 2, a core cylinder 3, a rubber ring 4, a nut 6, and a washer 7. The mounting hole of the connector 5 is a standard round hole.

[0046] like Figure 3 As shown, the outer sleeve 1 is composed of four identical sleeve components, with the interfaces of the four sleeve components arranged radially along the outer sleeve 1. Axially, the outer sleeve 1 includes an outer sleeve body 11, a conical groove 12, and an outer sleeve stop 13. The outer sleeve body 11 is a hollow cylindrical structure with an outer sleeve thread 14 on its outer side, which is a standard bolt thread. The conical groove 12 is located at the first end of the outer sleeve 1, and its end face at the outer sleeve body 11 gradually slopes downwards from the outside to the inside, making it easier for the core sleeve 3 to be screwed in. The outer sleeve stop 13 is located at the second end of the outer sleeve 1, and its outer diameter is larger than that of the outer sleeve body 11. The outer diameter of the outer sleeve stop 13 is smaller than the mounting hole of the connector 5, allowing the outer sleeve stop 13 to pass smoothly through the mounting hole of the connector 5.

[0047] like Figure 4 As shown, the center rod 2 is used to install inside the outer sleeve 1, and includes a center rod body 21 and a bolt head 22 in the axial direction. The center rod body 21 is a solid cylindrical structure with a center rod external thread 23 on its outer side, which adopts a standard bolt thread. The bolt head 22 is located at the second end of the center rod 2, and its outer diameter is larger than that of the center rod body 21. The outer diameter of the bolt head 22 is smaller than that of the mounting hole of the connector 5, so that the bolt head 22 can pass smoothly through the mounting hole of the connector 5. The bolt head 22 has four limiting grooves 24 on the outer edge of the surface facing the center rod body 21. The four limiting grooves 24 can respectively allow the outer sleeve stop blocks 13 of the four cylinder assemblies to be inserted.

[0048] like Figure 5 As shown, the core cylinder 3 is installed between the central rod 2 and the outer sleeve 1. The core cylinder 3 includes a core cylinder body 31, a core cylinder mounting block 32, and a conical end 33 in the axial direction. The core cylinder body 31 is a hollow cylindrical structure with an internal core cylinder thread 34 on its inner side. The internal core cylinder thread 34 matches the external thread 23 of the central rod, enabling the core cylinder 3 and the central rod 2 to engage through threaded engagement. The core cylinder mounting block 32 is located at the first end of the core cylinder 3. Two core cylinder mounting blocks 32 protrude from the first end face of the core cylinder body 31 and are distributed circumferentially at 180°, serving as the force-applying part for screwing the core cylinder 3 in. The conical end 33 is located at the second end of the core cylinder 3, and its outer diameter gradually decreases relative to the core cylinder body 31 to form a conical guide surface. This conical guide surface matches the conical groove 12 of the outer sleeve 1 to reduce the frictional resistance when the core cylinder 3 is screwed in and to increase the radial expansion force.

[0049] Among them, the first ends of the outer sleeve 1, the center rod 2, and the core sleeve 3 are in the same direction, and the second ends of the outer sleeve 1, the center rod 2, and the core sleeve 3 are in the same direction.

[0050] During the process of screwing the core cylinder 3 between the central rod 2 and the outer sleeve 1, the threaded engagement between the core cylinder 3 and the central rod 2, as well as the compression of the outer sleeve 1 by the core cylinder 3, forces the four identical cylinder segments of the outer sleeve 1 to disperse evenly in four directions. At the same time, the outer sleeve stop 13 opens outwards until it is embedded in the limiting groove 24, thereby forming a blind side support plane. Thus, during the tightening of the nut 6, the outer sleeve stop 13 and the bolt head 22 can work together to achieve the function of a traditional bolt head, realizing the fastening installation of a single-sided bolt.

[0051] Before installation, the insert-type single-sided bolt fastener of the present invention uses a rubber ring 4 to tighten and fix the central rod 2 and the outer sleeve 1, which is composed of four identical cylindrical segments, as shown in the figure. Figure 6 As shown. With the rubber ring 4 taut and fixed, the outer sleeve stop 13 is pressed against the surface of the bolt head 22 facing the central rod body 21. At this time, the overall diameter of the front end of the fastener formed by the outer sleeve stop 13 and the bolt head 22 is smaller than the inner diameter of the mounting hole of the connector 5. After the front end of the fastener passes through the mounting hole of the connector 5, the core cylinder 3 is manually screwed in through the core cylinder mounting block 32, causing the outer sleeve stop 13 of the four identical cylinder segments to expand and open outwards until they are respectively embedded in the limiting groove 24. The supporting area formed by the outer sleeve stop 13 and the bolt head 22 is larger than the area of ​​the mounting hole of the connector 5.

[0052] The rubber ring 4 is set to a certain length, which serves two purposes: firstly, to fix the center rod 2 and the outer sleeve 1 formed by the four identical cylinder components and to squeeze the outer sleeve 1 tightly; secondly, to facilitate handholding when screwing in the core cylinder 3.

[0053] Nut 6 is used to install on the outside of the expanding outer sleeve 1 after the core sleeve 3 is installed. The internal thread of nut 6 matches the outer sleeve thread 14 of the outer sleeve 1. Washer 7 is fitted on the outside of the expanding outer sleeve 1 before nut 6 is installed and is located between connector 5 and nut 6 to protect connector 5.

[0054] When installing the insert-type single-sided bolt fastener, the center rod 2 and the outer sleeve 1, which is locked outside the center rod 2 by the rubber ring 4, pass through the mounting hole from the operating side of the connector 5 to the blind side; then, the core cylinder 3 is screwed in, and the wedge-shaped expansion of the core cylinder 3 causes the outer sleeve stop 13 to spread out in all directions; finally, the washer 7 is placed on the operating side of the connector 5 and the nut 6 is tightened. After the nut 6 has been screwed in a certain distance, the rubber ring 4 is cut open with a knife to loosen it and make it fall off. During the gradual tightening of the nut 6, the outer sleeve stop 13 will press tightly against the blind side surface of the connector under the squeezing action of the bolt head 22, thus completing the installation of the insert-type single-sided bolt fastener.

[0055] like Figure 7 As shown, based on this embodiment of the insert-type single-sided bolt fastener, this embodiment also provides an installation method for the insert-type single-sided bolt fastener, including the following process:

[0056] In the initial preparation stage, the operator first uses rubber rings 4 to pre-assemble the four identical cylinder segments of the center rod 2 and the outer sleeve 1. The elastic tightening force provided by the rubber rings 4 keeps the inner wall of the outer sleeve 1 tightly against the main body 21 of the center rod, ensuring that the outer sleeve stops 13 of the four identical cylinder segments are in a retracted state. At this time, the overall diameter of the front end of the fastener formed by the outer sleeve stops 13 and the bolt head 22 is smaller than the mounting hole of the connector 5, so that it can pass smoothly through the mounting hole to reach the blind side of the connector 5.

[0057] Once the front end of the fastener has completely passed through the mounting hole of the connector 5, the core cylinder 3 enters the locking stage. The operator holds the core cylinder 3 and, utilizing the tapered guide surface design with its tapered end 33 gradually decreasing in outer diameter, aligns it with the annular gap between the center rod 2 and the outer sleeve 1. By rotating the core cylinder mounting block 32, the core cylinder 3 is pushed deeper along the center rod 2.

[0058] As the core cylinder 3 is continuously screwed in, the wedge-shaped compression effect forces the four cylinder segments of the outer sleeve 1 to disperse evenly in the radial direction due to the engagement between the conical end 33 of the core cylinder 3 and the conical groove 12 of the outer sleeve 1. At this time, the outer sleeve stop 13 located on the blind side of the connector 5 will expand outward and embed into the limiting groove 24. The outer sleeve stop 13 and the bolt head 22 form a stable support plane on the blind side surface of the connector 5, thereby replacing the traditional fixing function of the bolt head in the enclosed space.

[0059] After the core cylinder 3 is screwed in to a certain depth, the final tightening process begins. The operator inserts the washer 7 onto the outside of the outer sleeve 1 and rotates the nut 6. As the nut 6 is tightened along the thread 14 of the outer sleeve, the resulting axial tension firmly presses the unfolded outer sleeve stop 13 against the blind side surface of the connector 5, achieving a clamping effect together with the nut 6 tightened on the outer surface of the connector 5. After the nut 6 has been screwed in a certain distance, the rubber ring 4 is cut open and removed with a knife without affecting the final mechanical properties of the structure.

[0060] After completing the above installation steps, the insert-type single-sided bolt fastener of the present invention forms a unique "three-layer nesting" system in terms of structural stress. When the nut 6 applies preload, the axial tensile force first acts on the central rod 4 and the bolt head 22. Since part of the outer sleeve stop 13 is embedded in the bolt head 22 and forms an integral part with it, they together form pull-out resistance on the blind side of the connector 5. At the same time, the core cylinder 3, as the intermediate medium of stress, has its internal thread 34 meshing with the external thread 23 of the central rod. Since the core cylinder 3 is in a wedge-shaped compression state when screwed in, the thread engagement not only significantly increases the contact area and structural rigidity, but also greatly enhances the frictional resistance between the threads; ultimately, this insert-type single-sided bolt fastener has extremely excellent anti-loosening performance when subjected to dynamic loads or vibration conditions.

[0061] The insert-type single-sided bolt fastening design of this invention, through the principle of internal mechanical expansion, not only solves the problem of single-sided construction of closed-section components, but also avoids stress concentration caused by welding or on-site drilling that weakens the cross-section of the base material in traditional processes.

[0062] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the principles of this practice should be included within the protection scope of this practice.

Claims

1. A ferrule-type single-sided bolt fastener, characterized in that, Includes outer sleeve, center rod, core sleeve, rubber ring, and nut; The outer sleeve is composed of several identical cylindrical segments assembled together, and includes an outer sleeve main body, a conical groove, and an outer sleeve stop. The outer sleeve main body, when the cylindrical segments are assembled, is a hollow cylindrical structure, and an outer sleeve thread is provided on the outer side of the outer sleeve main body. The conical groove is located at the first end of the outer sleeve, and the end face of the outer sleeve main body gradually slopes downward from the outside to the inside. The outer sleeve stop is located at the second end of the outer sleeve, and its outer diameter is larger than that of the outer sleeve main body. The central rod is used to be installed inside the outer sleeve and includes a central rod body and a bolt head; the outer side of the central rod body is provided with a central rod external thread; the bolt head is located at the second end of the central rod, and its outer diameter is larger than that of the central rod body, and the outer diameter of the bolt head is smaller than the mounting hole of the connector; the bolt head is provided with a plurality of limiting grooves on the outer edge of the surface facing the central rod body, and the plurality of limiting grooves are used to respectively embed the outer sleeve stop block after the expansion of the cylinder assembly; The core cylinder is installed between the central rod and the outer sleeve, and includes a core cylinder body, a core cylinder mounting block, and a conical end. The core cylinder body is a hollow cylindrical structure with an internal thread on its inner side. The internal thread of the core cylinder matches the external thread of the central rod, enabling the core cylinder and the central rod to engage through threaded engagement. The core cylinder mounting block is located at the first end of the core cylinder and protrudes relative to the first end face of the core cylinder body, serving as a force-applying part for screwing the core cylinder in. The conical end is located at the second end of the core cylinder and matches the conical groove of the outer sleeve. The rubber ring is used to tighten and fix several identical cylinder segments of the outer sleeve to the outside of the central rod before the core cylinder is installed; during this process: the outer diameter of the fastener front end formed by the outer sleeve stop and the bolt head is smaller than the inner diameter of the mounting hole of the connector; the second end of the central rod and the second end of the outer sleeve pass through the mounting hole from the operating side of the connector to the blind side. During the installation of the core tube, as the core tube is screwed in, several identical tube segments of the outer sleeve expand outward simultaneously, and the outer sleeve blocks open outward until they are embedded in the limiting groove. As a result, the supporting surface formed by the outer sleeve blocks and the bolt head is larger than the mounting hole of the connector. The nut is used to fit over the expanded outer sleeve after the core is installed; the internal thread of the nut matches the thread of the outer sleeve to achieve threaded engagement between the nut and the outer sleeve; after the nut is screwed in and stabilized, the rubber ring is detached from the outer sleeve; after the nut is tightened, the outer sleeve stop is pressed against the blind side surface of the connector under the squeezing action of the bolt head.

2. The insert-type single-sided bolt fastener according to claim 1, characterized in that, The number of cylinder flap assemblies in the outer sleeve is 3-5.

3. The insert-type single-sided bolt fastener according to claim 1, characterized in that, The two core mounting blocks are distributed circumferentially at 180° on the first end face of the core body.

4. A ferrule-type single-sided bolt fastener according to claim 1, characterized in that, A gasket is provided between the connector and the nut.

5. An installation method for a single-sided bolt fastener with insert as described in any one of claims 1-4, characterized in that, include: (1) The four identical cylinder segments of the central rod and the outer sleeve are pre-assembled using the rubber ring. The rubber ring makes the outer sleeve tight outside the main body of the central rod. The outer sleeve stop is in a retracted state, and the overall diameter of the front end of the fastener formed by the outer sleeve stop and the bolt head is smaller than the mounting hole of the connector. (2) Insert the center rod with the rubber ring tightened and the outer sleeve into the mounting hole of the connector, so that the front end of the fastener composed of the outer sleeve stop block and the bolt head passes through the mounting hole from the operating side of the connector to the blind side; (3) Align the conical end of the core tube with the annular gap between the center rod and the outer sleeve, and use the core tube mounting block to screw the core tube between the center rod and the outer sleeve; (4) As the core cylinder is screwed in, several identical cylinder segments of the outer sleeve expand outwards simultaneously, and the outer sleeve blocks open outwards to the circumferential side until they are embedded in the limiting groove, thereby forming a stable support plane with the bolt head on the blind side surface of the connector. (5) Screw the nut into the outer side of the outer sleeve. After the nut is screwed in and stabilized, peel the rubber ring off the outer sleeve. Continue to screw the nut in until it is tightened. The outer sleeve stop block presses tightly against the blind side surface of the connector under the squeezing action of the bolt head.

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