Spin riveting type single-face installation blind bolt structure

Abstract

The invention provides a spin riveting type single-face installation blind bolt structure. The spin riveting type single-face installation blind bolt structure comprises a core rod, a rivet sleeve, an adjusting bolt, an extrusion nut, a U-shaped spring and a universal rotating head. One end of the core rod main body is matched with the riveter head to rotate, a first through hole which is obliquely formed is formed in the position, corresponding to the second containing cavity, of the core rod main body, the U-shaped spring is located in the second containing cavity, and the first through hole is matched with the U-shaped spring; the adjusting bolt is correspondingly arranged in the penetrating structure and is in threaded fit with the limiting step, and one end of the adjusting bolt is connected with the universal rotating head in a clamped mode. The extrusion nut and the nail sleeve are both in threaded connection with the core rod, the extrusion nut and the nail sleeve are coupled in a sawtooth shape, and a plurality of second via holes which are obliquely formed are formed in the extrusion nut to correspond to the insertion positions of the U-shaped springs with the multi-gear pre-tightening force. The key performance of the single-face-installed blind bolt at the high temperature is improved, the thermal adaptability of a product under the high-temperature working condition is remarkably improved, and therefore the use reliability of the product under the high-temperature working condition is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fasteners, and particularly relates to a blind rivet type single-sided installation blind bolt structure. BACKGROUND

[0002] In high-end equipment manufacturing such as aerospace, designers often use single-sided installation blind rivets or blind bolts for fastening connection between components in order to meet the requirements of lightweight, high-strength connection and rapid installation. At present, there is a blind rivet type blind rivet with adjustable pre-tightening force, which can be applied to different strength installation materials and different pre-tightening connection scenes, but the installation working conditions in the aerospace field are complex, and the performance requirements of the blind rivet are different.

[0003] In some application parts of the aerospace type, the long-term working temperature can reach 400-600°C, and in the high-temperature region of the air friction on the outer surface of the skin, the sharp point will have a heat concentration effect, which is a sensitive trigger factor for combustion. In order to avoid the ignition of the sharp point, it is required that the cross section of the single-sided fastener is as flat as possible or recessed, and no sharp point should appear. At the same time, the blind rivet mainly bears the combined load of tensile shear and thermal stress at high temperature under high temperature, and the conventional blind rivet is affected by the material properties such as the thermal expansion coefficient. At high temperature, the blind end of the rivet is abnormally formed, various installation forming defects may occur, and the key performance such as tensile and shear strength may be attenuated at 600°C high temperature. This results in that the key performance such as tensile and shear strength of the conventional blind rivet is low, and the cross section of the blind rivet after installation is limited by the process and cannot be completely flat, so the cross section needs to be flattened again, which cannot meet the installation requirements under the high-temperature working condition of the aerospace. SUMMARY

[0004] Therefore, the application aims to provide a blind rivet type single-sided installation blind bolt structure to solve at least one of the above problems.

[0005] To achieve the above-mentioned purpose, the technical scheme of the application is as follows: The application provides a blind rivet type single-sided installation blind bolt structure, which comprises a core rod, a rivet sleeve, an adjusting bolt, an extrusion nut, a U-shaped spring and a universal rotating head. One end of the core rod body is a driving end which is matched with a chuck inside a gun head of a rivet gun for rotation. A through structure composed of a containing countersunk hole, a first containing cavity, a limiting step and a second containing cavity is formed in the core rod body. An inclined first through hole is formed in the core rod body corresponding to the position of the second containing cavity. The U-shaped spring is located in the second containing cavity, and the first through hole is matched with the U-shaped spring. The adjusting bolt is correspondingly arranged in the through structure and is threadedly matched with the limiting step. One end of the adjusting bolt is clamped and connected with the universal rotating head. The extrusion nut and the nail sleeve are both in threaded connection with the core rod, the serrated end of the extrusion nut is coupled with one end of the nail sleeve sleeved on the core rod through serration, a plurality of second through holes obliquely arranged are formed on the extrusion nut, and the plurality of second through holes correspond to the insertion positions of the U-shaped springs of multiple pre-tightening forces respectively.

[0006] Further, the driving end is a double driving rotation structure of inner and outer flat shapes to cooperate with the chuck in the interior of the riveting gun head to rotate. The core rod body is provided with a conical protrusion extending outward, and a diameter breaking groove is arranged between the driving end and the conical protrusion.

[0007] Further, the adjusting bolt is composed of a light rod, a threaded driving rod, a countersunk head and a spherical rotary joint outer buckle, the light rod is located in the first accommodating cavity, the limiting step is a threaded step hole, the threaded driving rod is in threaded connection with the threaded step hole, the countersunk head is matched with the accommodating countersunk hole, and the spherical rotary joint outer buckle is in clamping connection with the universal rotary head. One end of the light rod is further provided with a cross-shaped driving groove for cooperating with a cross-shaped handle arranged on the rotary driving head of the adjusting bolt.

[0008] Further, the universal rotary head comprises a rotary head body, one end of the rotary head body is provided with a spherical rotary head matched with the spherical rotary joint outer buckle, and a rectangular groove hole is further formed in the rotary head body, the rectangular groove hole is used for unlocking and accommodating the U-shaped spring during single-sided installation of a blind bolt pre-tightening force gear shifting adjustment.

[0009] Further, the length of the rectangular groove hole corresponds to the stroke length of the U-shaped spring unlocking and is greater than the depth of the second through hole.

[0010] Further, the smoothness of the rectangular groove hole is ≤Ra1.6, and a smooth transition fillet is further arranged in the rectangular groove hole.

[0011] Further, the U-shaped spring comprises a middle unlocking end and two locking ends. The unlocking end is towards one end of the universal rotary head and cooperates with the adjusting universal rotary head, and the inclination angle of the locking end port is matched with the first through hole and the second through hole.

[0012] Further, the U-shaped spring is made of spring steel material.

[0013] Further, an external thread is arranged on the outer side of one end of the core rod body away from the driving end, an internal thread matched with the external thread is arranged on the inner wall of the extrusion nut, and the extrusion nut is in threaded connection with the core rod. The second through hole provided on the extruding nut is a slanting circular hole, and the opening faces inward to one end of the universal rotating head.

[0014] Further, the extruding nut is made of GH4169 high-temperature alloy material.

[0015] Compared with the prior art, the blind bolt structure of the present application has the following beneficial effects: (1) Improving the key performance of the single-sided blind bolt at high temperature. The conventional single-sided fastener will be attenuated by 30%-40% at 400°C-600°C high temperature, which cannot meet the use requirements. The present application improves the key performance indexes such as shear resistance, tensile resistance and anti-loosening through the structural innovation design of the core rod, adjusting bolt and U-shaped spring.

[0016] (2) At high temperature, the pull-out bolt is affected by thermal stress load, and various thermal effect failure modes (fatigue attenuation, performance reduction, etc.) may occur. In order to ensure the thermal expansion coefficient matching of the pull-out bolt and the base material, the blind bolt parts in the present application are made of high-temperature alloy materials with different thermal expansion coefficients, which can significantly improve the thermal adaptability of the product under high-temperature working conditions, thereby improving the use reliability of the product under high-temperature working conditions.

[0017] (3) In order to avoid the problem that the sharp point of the fracture section is easy to cause sharp point burning due to air friction at high temperature, the present application designs a structure containing a countersunk hole and an inner and outer flat type double driving groove. Under the same breaking torque, the effective area of the breaking groove is further reduced, so as to ensure that there is no sharp point on the fracture section after the core rod is broken.

[0018] (4) The product structure is more compact. Through structural innovation, the overall length of the pull-out bolt is shortened, and the exposed height of the blind end before and after installation is effectively shortened by 1 / 3. Under the premise of improving the performance index, the pull-out bolt weighs lighter, which better meets the requirement of lightweight of aerospace products. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings: Figure 1 A blind bolt structure of the present application is shown in the accompanying drawings. Figure 2 A core rod structure of the present application is shown in the accompanying drawings. Figure 3 An adjusting bolt structure of the present application is shown in the accompanying drawings. Figure 4 A U-shaped spring structure of the present application is shown in the accompanying drawings. Figure 5Extrusion nut structure schematic diagram described in the embodiments of the present application; Figure 6 Universal rotation head structure schematic diagram described in the embodiments of the present application; Figure 7 Adjusting bolt and universal rotation head assembly schematic diagram described in the embodiments of the present application; Figure 8 Adjusting bolt rotation drive head structure schematic diagram described in the embodiments of the present application; Figure 9 Riveting initial state schematic diagram described in the embodiments of the present application; Figure 10 Riveting to the first pre-tightening force and locking state schematic diagram described in the embodiments of the present application; Figure 11 Blind bolt unlocking after the adjusting bolt drive head is unlocked schematic diagram described in the embodiments of the present application; Figure 12 Blind bolt unlocking to a higher pre-tightening force drive schematic diagram described in the embodiments of the present application; Figure 13 Rivet restoring the adjusting bolt position through the adjusting bolt drive head schematic diagram described in the embodiments of the present application; Figure 14 Riveting to the second pre-tightening force and locking state schematic diagram described in the embodiments of the present application; Figure 15 Blind bolt unlocking at the second pre-tightening force state schematic diagram described in the embodiments of the present application; Figure 16 Intermediate and highest pre-tightening force gear installation completed schematic diagram described in the embodiments of the present application.

[0020] Explanation of reference signs: 1-core rod; 2-nail sleeve; 3-adjusting bolt; 4-extrusion nut; 5-U-shaped spring; 6-universal rotation head; 7-driving end; 8-neck breaking groove; 9-conical protrusion; 10-external thread; 11-second accommodating cavity; 12-first through hole; 13-U-shaped spring installation groove; 14-first accommodating cavity; 15-limiting step; 16-accommodating counterbore; 17-cross-shaped driving groove; 18-threaded driving rod; 19-spherical rotary joint outer buckle; 20-shear-resistant small counterbore; 21-shear-resistant light rod; 22-unlocking end; 23-locking end; 24-sawtooth end; 25-closed region; 26-second through hole; 27-internal thread; 28-spherical rotary head; 29-rectangular slot hole. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application is further described in detail below in combination with specific embodiments and with reference to the drawings.

[0022] For the purpose of clarity, technical and scientific terms used in the present embodiments have the same meaning as those that are commonly understood by one of ordinary skill in the art to which the present embodiments belong unless specifically defined otherwise. The terms "first", "second", and similar terms do not imply any order, quantity, or importance, but are used to distinguish one element from another, and are used arbitrarily. The terms "include", "comprise", and the like are used synonymously to encompass a possibility that there are further elements or a possibility that there are other elements in addition to those listed. The terms "connected" and "coupled" and the like are not limited to a physical or mechanical connection or coupling, and can include an electrical connection or coupling, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are used to indicate relative positions only and can change according to the position of the described object.

[0023] The present embodiments provide a single-sided installation blind bolt of rivet type, which has high tensile strength, high shear strength, light weight, low height of blind end after installation, and no sharp point in cross section after installation, and can be applied to high-performance blind bolts installed on one side under high temperature of 400°C to 600°C. Compared with a common reliable pre-tightening force blind bolt installed on one side, the present product adopts a unique innovative design in structure and material, the small countersunk head structure and the threaded locking fit are used in the tensile fit part of the core rod and the pre-tightening force adjusting bolt, the cross section after installation has no concave-convex sharp point, the effect of heat concentration and easy ignition under high temperature is avoided, the tensile performance can be improved by more than 30% compared with the light rod through hole fit, the shear performance can be improved by more than 30% compared with the original threaded fit, and can be improved by more than 15% compared with the non-locking light rod fit. By changing the bending and locking direction of the U-shaped spring, the height of the pre-tightening force adjusting bolt is reduced by more than 30%, the length of the threaded guide end of the core rod is reduced by more than 30%, the height of the blind end after installation is reduced by more than 20%, and the overall weight of the rivet after riveting is reduced by more than 30%. Through the above design, the tensile and shear performance of the rivet under high temperature of 400°C to 600°C and the installation flushness are improved, and the installation and use requirements of the product under high temperature are met.

[0024] Referring to FIG. 1, Figure 1 As shown in FIG. 1, the single-sided installation blind bolt structure according to the present embodiments mainly includes a core rod 1, a rivet sleeve 2, an adjusting bolt 3, an extrusion nut 4, a U-shaped spring 5, and an adjusting universal rotating head 6.

[0025] Figure 2The core rod 1 is a schematic diagram of a structure, and the core rod 1 body is an elongated rod structure, which is provided with a flat drive end 7, a neck breaking groove 8, a conical protrusion 9 (used to provide a support surface), an external thread 10, a second accommodating cavity (U-shaped spring accommodating cavity) 11, a first via hole 12 (i.e., an inclined circular hole), a U-shaped spring mounting groove 13 (used to mount a U-shaped spring), a first accommodating cavity (anti-shear type light rod accommodating cavity) 14, a limiting step 15, and an accommodating counterbore 16.

[0026] Specifically, in the embodiment, the limiting step 15 is a threaded step hole, which is used to limit the mechanical axial displacement of the adjusting bolt 3 (also called a pre-tightening force adjusting bolt 3), control the extension amount of the pre-tightening force adjusting bolt 3 within a design range, and avoid the axial movement of the pre-tightening force adjusting bolt 3 from causing the adjusting bolt 3 to protrude after installation. After riveting is completed, the threaded step hole completely limits the position of the adjusting bolt 3, so that the adjusting bolt 3 will not move and affect the flatness of the cross section under the condition of a certain expansion deformation of a high-temperature material product.

[0027] The accommodating counterbore 16 is matched with the small counterbore of the adjusting bolt 3, and is used to accommodate the small counterbore of the adjusting bolt 3. The small counterbore structure ensures that the single-sided installation blind bolt is flush and flat after riveting, can ensure that the surface is flat without protrusion or depression, installation is more stable, the risk of loosening is reduced, and the reliability of the connecting pair is ensured. The first accommodating cavity 14 is a smooth surface and is in transition cooperation with the adjusting bolt 3. The shear bearing cooperation position of the core rod 1 and the adjusting bolt 3 is a light rod cooperation, and the shear resistance performance is improved by more than 30% compared with the original threaded cooperation, and is improved by more than 15% compared with the non-locking light rod cooperation structure.

[0028] The inclined circular hole is matched with the U-shaped spring 5, the opening is inwardly directed to one end of the universal rotary head 6, and the inclination is about 60°±10°. The drive end 7 is an inner and outer two-circle thickened flat structure, which is in cooperation with the chuck inside the riveter head to rotate and drive the single-sided installation blind bolt to complete the riveting installation. The application designs the inner and outer two-layer flat drive end 7, adopts a double-drive rotary structure, increases the biting area, increases the plate torque, and effectively compensates for the demand of different specifications of the core rod 1 to transmit different torques. The double-circle flat drive end 7 also compensates for the difference in the thermal expansion coefficient between the riveter and the core rod 1 at different temperatures, reserves a gap, and ensures efficient torque transmission.

[0029] Figure 3 The adjusting bolt 3 is a schematic diagram of a structure, which is composed of a cross-shaped driving groove 17, a threaded driving rod 18, a spherical rotary joint outer buckle 19, an anti-shear type small counterbore 20, and an anti-shear type light rod 21.

[0030] Specifically, in the embodiment, the cross-shaped driving groove 17 is used to adapt to the rotary driving head (the rotary driving head is, for example, a ball joint) of the adjusting bolt 3. Figure 8The cross handle at the top (as shown) enables the driving adjustment bolt 3 to unlock the U-shaped spring 5. Compared with the straight drive groove, the cross drive groove 17 is easier to align and apply force, and is more suitable for the tightening torque of small-sized single-sided blind bolt structures, resulting in higher installation efficiency.

[0031] The shear-resistant smooth rod 21 is the main structure of the preload adjusting bolt 3. It is a smooth rod with a smooth surface and transition fits with the core rod 1. Compared with the threaded structure, the smooth rod structure has less attenuation of tensile and shear strength at high temperatures of 400°C to 600°C, which can improve shear strength and avoid thread deformation and strength reduction at high temperatures.

[0032] The threaded drive rod is located at the tail end of the preload adjusting bolt 3, and its length accounts for about 1 / 4 of the entire preload adjusting bolt 3. It engages with the internal thread 27 on the threaded limit step 15 of the adjusting bolt 3 to prevent relative sliding between the preload adjusting bolt 3 and the core rod 1 after riveting. This increases the tensile and shear resistance while ensuring the stability of the connection.

[0033] Figure 7 The diagram shows the assembly of the adjusting bolt 3 and the universal rotating head 6. During use, when the preload adjusting bolt 3 is loosened, it will pull the universal rotating head 6 and the U-shaped spring 5 backward to the left until the threaded drive rod 18 is completely unscrewed from the threaded limit step 15 of the preload adjusting bolt 3. At this time, the U-shaped spring 5 is also unlocked from the oblique round hole of the core rod 1. Subsequently, due to the elastic tension of the U-shaped spring 5 and the blocking effect of the right shoulder of the threaded drive rod 18, no matter how the preload adjusting bolt 3 is loosened, it can only rotate freely and cannot continue to move backward to the left. This ensures that the preload adjusting bolt 3 remains on the riveting structure and will not fall off, thus improving the convenience of installation and maintenance. To ensure product performance at high temperatures, the preload adjusting bolt 3 is made of high-temperature alloy materials such as GH or GH.

[0034] Figure 4 The diagram shows the structure of the U-shaped spring 5, including the unlocking end 22 and the locking end 23. The U-shaped spring 5 is made of spring steel and utilizes elastic deformation to achieve quick unlocking.

[0035] Specifically, in this embodiment, the tilt angle of the locking end 23 of the U-shaped spring 5 is about 45°~60°. The tilt angle is compatible with the oblique round hole on the core rod 1 and the compression nut 4, ensuring that the U-shaped spring 5 can be smoothly inserted and locked when locked. The unlocking end 22 faces the universal rotating head 6 and cooperates with the pre-tightening force adjusting universal rotating head 6. Through the action of the rotating drive head of the pre-tightening force adjusting bolt 3, the U-shaped spring 5 can be retracted and unlocked, preparing for further adjustment of the pre-tightening force level.

[0036] In existing adjustable preload single-sided blind bolts, after installation at the second and third preload settings, the core rod 1 protrudes a certain distance from the compression nut 4 to accommodate the U-shaped spring 5. In this embodiment, an innovative structural design, combined with changes in the bending and locking direction of the U-shaped spring 5, makes the riveting structure more compact. This significantly shortens the length of the entire space accommodating the compression nut 4, core rod 1, and U-shaped spring 5, reducing the height of the preload adjusting bolt 3 by 30%, the length of the threaded guide end of the core rod 1 by 30%, and the height of the blind end after installation by 15%. The overall weight after riveting is reduced by 30%, allowing the product to be installed on one side in more confined areas.

[0037] Figure 5 The diagram shows the structure of the compression nut 4, including the serrated end 24, the constriction area (the constriction area is a recessed part designed to deform the internal thread of the compression nut, thereby preventing the compression nut from loosening and locking it) 25, the second through hole 26 (i.e., the oblique round hole), and the internal thread 27.

[0038] Specifically, in this embodiment, the three sets of oblique circular holes serve as locking slots for the U-shaped springs and also as unlocking guide slots. Their openings face inwards towards the universal rotating head 6, with an oblique angle set between 45° and 60°. This ensures sufficient locking depth for stable spring insertion while preventing excessive unlocking travel and potential jamming. The oblique circular holes are symmetrically positioned along the axis of the compression nut 4 and spaced a certain distance apart, corresponding to the insertion positions of the U-shaped springs 5 ​​at the three preload levels. To ensure product performance at high temperatures, the compression nut 4 is made of GH4169 high-temperature alloy material. GH4169 material exhibits higher high-temperature yield strength and creep resistance than the GH2132 material used in the sleeve 2, and has a lower coefficient of thermal expansion. This means that at the same temperature range of 400°C to 600°C, GH4169 has better resistance to deformation. At high temperatures, the compression nut 4 can continuously compress the sleeve 2 to form a bulge, compensating for the bulging deformation of the sleeve 2 and preventing extrusion defects caused by thermal expansion at high temperatures.

[0039] Figure 6 The universal rotating head 6 comprises a rotating head body, a spherical rotating head 28, and a rectangular slot 29 mounted on the rotating head body. The universal rotating head 6 is connected to the outer snap-fit ​​19 of the spherical rotating joint. The rectangular slot 29 allows for the unlocking and accommodating of the U-shaped spring 5 during the adjustment of the preload of the blind bolt on one side. The length of the rectangular slot 29 is also the stroke length for unlocking the U-shaped spring. To balance structural compactness and ease of operation, the length of the rectangular slot 29 is twice the depth of the oblique circular hole of the compression nut 4 (the wall thickness of the compression nut 4). To reduce wear at high temperatures, the surface finish of the rectangular slot 29 is ≤Ra1.6, and the rectangular slot 29 has smooth transition radii.

[0040] The bolt sleeve 2 is the main tensile component of the single-sided blind bolt. In this embodiment, the bolt sleeve 2 is made of high-temperature alloy material with grade GH2132 (A286). This high-temperature alloy material has high yield strength and creep strength at high temperatures, and its tensile strength in the temperature range of 400°C to 600°C is superior to other grades of high-temperature alloys. Using this material for the bolt sleeve 2 can improve the mechanical properties of the product, such as tensile strength, at high temperatures, while ensuring the local annealing performance of the material.

[0041] In this embodiment, as Figure 1 As shown, the nail sleeve 2 adopts a conventional structural design, including a support surface, a local annealing zone, a local quenching zone, a serrated end 24, and a cross groove structure. The outer conical surface of the support end matches the mounting hole, and the inner conical surface matches the support surface of the core rod 1. The local annealing zone is a softened area on the nail sleeve 2, where a bulge base can be formed. The local quenching zone is a harder area located at the top of the nail sleeve 2. The serrated end 24 and the toothed surface of the compression nut 4 cooperate to drive the nail sleeve 2 to deform. Because it is located at the top of the local quenching zone, it can ensure that it does not deform under the pressure of the compression nut 4. The cross groove cooperates with the cross teeth of the rivet gun head to drive the single-sided blind bolt to complete the riveting.

[0042] Example 1: When using a rivet gun to rivet a blind rivet to a component to be riveted, the riveting process is as follows: The riveting process is as follows: First, a riveting hole adapted to the single-sided blind bolt is machined on the part to be riveted and the base. Then, the assembled single-sided blind bolt is inserted into the riveting hole, so that the head support end on the bolt sleeve 2 abuts against the opening of the riveting hole of the part to be riveted. Then, the flat drive end 7 at the end of the flat core rod 1 is inserted into the rivet gun head that matches its shape. Figure 9 As shown.

[0043] Then, the rivet gun head is used to press the single-sided blind bolt sleeve 2 against the mounting base. The end face of the rivet gun head is cross-shaped and closely fits the groove on the support end surface of the rivet sleeve 2. The rivet gun trigger is then pressed, and the rivet gun begins to work. The rivet gun head rotates at a certain speed, causing the core rod 1 to rotate simultaneously. The rivet sleeve 2 does not rotate because it is tightly fitted with the cross groove on the end face of the rivet gun head. The serrated end 24 of the compression nut 4 and the top of the rivet sleeve 2 are coupled through serrated edges, so they also do not rotate. Driven by the thread, the front end of the core rod 1 moves the compression nut 4 closer to the mounting location. Due to the high material strength, the compression nut 4 itself does not deform, but it will cause localized deformation of the rivet sleeve 2, gradually forming a bulge. As the rivet gun continues to rotate, the bulge in the rivet sleeve 2 becomes larger and larger under the compressive force. The preload force of the single-sided blind bolt on the mounting plate also increases accordingly. When the rivet gun stops after one cycle, the compression nut 4 moves down to a certain position. At this time, the oblique round hole on the U-shaped spring 5 accommodating cavity of the core rod 1 coincides with the first oblique round hole on the compression nut 4. Under its own elasticity, the end of the U-shaped spring 5 will simultaneously pass into the coinciding oblique round hole. The core rod 1 and the compression nut 4, as well as the core rod 1 and the preload adjustment bolt 3, cannot move relative to each other. If the rivet gun is released at this time and the trigger is pulled again to start the second working cycle of the rivet gun, the inner chuck of the gun head will continue to rotate under air pressure. Since the core rod 1 and the compression nut 4 are locked by the U-shaped spring 5, the core rod 1 will not be able to rotate. Subsequently, under the torque of the rivet gun chuck, it can only break from the neck groove 8 at the end of the core rod 1, thus completing the entire installation process. The effect after installation is shown in the figure. Figure 10 As shown.

[0044] If the first preload is insufficient to meet the connection requirements, the preload can be increased to the second or third setting of the single-sided blind bolt. When the single-sided blind bolt is installed at the first preload setting, the rivet gun completes one cycle and stops. The rivet gun is then removed, and the preload adjusting bolt 3 is rotated and driven by the rotating drive head inserted into the cross groove at the tail of the preload adjusting bolt 3. Rotating the preload adjusting bolt 3 drives the preload adjusting bolt 3 to move away from the installation location. Because the bottom end of the U-shaped spring 5 unlocking rectangular slot 29 of the preload adjusting universal rotating head 6 abuts against the middle unlocking end of the U-shaped spring 5, the inclined locking ends of the U-shaped spring 5 slide out from the inclined circular holes of the compression nut 4 under the action of the pushing force. Finally, the preload adjusting bolt 3 will move to the fully unlocked position, completing the unlocking of the core rod 1 and the compression nut 4. Subsequently, due to the elastic tension of the U-shaped spring 5 and the blocking effect of the right shoulder of the threaded drive rod 18, no matter how loose the preload adjusting bolt 3 is, it can only rotate freely and cannot continue to move away from the installation position. This ensures that the preload adjusting bolt 3 will remain on the rivet structure and will not fall off, thus improving the convenience of installation and maintenance.

[0045] At this point, remove the preload adjustment bolt 3 and rotate the drive head, reinstall the rivet gun, and pull the rivet gun trigger. The rivet gun continues to work, driving the core rod 1 to rotate. After rotating a certain angle, such as 90 degrees, the oblique round hole on the core rod 1 and the oblique round hole on the compression nut 4 become misaligned. At this point, remove the rivet gun and re-insert the preload adjustment bolt 3 and rotate the drive head in the opposite direction. This will cause the preload adjustment bolt 3 and the preload adjustment universal rotating head 6 to move towards the mounting plate until the countersunk head of the preload adjustment bolt 3 and the countersunk head of the core rod 1 are completely sealed together, preventing further rotation. At this point, the unlocking end of the U-shaped spring 5 is in contact with the left end face of the inner cavity of the universal rotating head 6. Then, re-insert the rivet gun for installation. When the rivet gun stops after one cycle, the oblique round hole in the core rod 1 coincides with the second preload oblique round hole on the compression nut 4. The U-shaped spring 5 will quickly return to its original position. During this process, the extruded and deformed part of the rivet sleeve 2 will be subjected to a greater preload, forming a larger bulge at the bottom. The above process is as follows: Figures 11-15 As shown. The next step is to choose to complete the installation or continue increasing the clamping force, depending on the assembly conditions. The process is the same as the first stage and will not be described again. The finished installation at the intermediate and highest pre-tightening force settings is shown in the following diagram. Figure 16 As shown.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0047] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A single-sided blind bolt structure for rotary riveting, characterized in that: Includes core rod, nail sleeve, adjusting bolt, compression nut, U-shaped spring and universal rotating head; One end of the core rod body is the driving end, which rotates in conjunction with the chuck inside the rivet gun head. The core rod body has a through structure consisting of a countersunk hole, a first receiving cavity, a limiting step, and a second receiving cavity. The core rod body has a first through hole that is inclined at the position corresponding to the second receiving cavity. The U-shaped spring is located in the second receiving cavity, and the first through hole matches the U-shaped spring. The adjusting bolt is correspondingly disposed within the through structure and threadedly engaged with the limiting step, and one end of the adjusting bolt is engaged with the universal rotating head; Both the compression nut and the nail sleeve are threadedly connected to the core rod. The serrated end of the compression nut is coupled to one end of the nail sleeve fitted on the core rod through a serrated shape. The compression nut has multiple inclined second through holes, which correspond to the insertion positions of U-shaped springs with multiple preloads.

2. The single-sided blind bolt structure for riveting as described in claim 1, characterized in that: The drive end is an inner and outer flat dual-drive rotating structure, which is used to cooperate with the chuck inside the rivet gun head for rotation. The core rod body is provided with an outwardly extending conical protrusion, and a cut-off groove is provided between the drive end and the conical protrusion.

3. The single-sided blind bolt structure for riveting as described in claim 1, characterized in that: The adjusting bolt consists of a smooth rod, a threaded drive rod, a countersunk head, and a ball joint external buckle. The smooth rod is located in the first accommodating cavity. The limiting step is a threaded step hole. The threaded drive rod is threadedly connected to the threaded step hole. The countersunk head matches the accommodating countersunk head hole. The ball joint external buckle is engaged with the universal rotating head. One end of the optical rod is also provided with a cross-shaped drive groove, which is used to cooperate with the cross handle provided on the rotating drive head of the adjusting bolt.

4. The single-sided blind bolt structure for riveting as described in claim 3, characterized in that: The universal rotating head includes a rotating head body, one end of which is provided with a spherical rotating head. The spherical rotating head cooperates with the outer buckle of the spherical rotating joint. The rotating head body is also provided with a rectangular slot, which is used for unlocking and accommodating the U-shaped spring during the adjustment of the preload of the blind bolt on one side.

5. The single-sided blind bolt structure for riveting as described in claim 4, characterized in that: The length of the rectangular slot corresponds to the travel length of the U-shaped spring during unlocking, and is greater than the depth of the second through hole.

6. The single-sided blind bolt structure for riveting as described in claim 4, characterized in that: The surface finish of the rectangular slot is ≤Ra1.6, and the rectangular slot is also provided with smooth transition rounded corners.

7. The single-sided blind bolt structure for riveting as described in claim 1, characterized in that: The U-shaped spring includes an unlocking end in the middle and locking ends at both ends; The unlocking end faces one end of the universal rotating head and cooperates with the adjusting universal rotating head, and the tilt angle of the locking end port is adapted to the first through hole and the second through hole.

8. A single-sided blind bolt structure for riveting as described in claim 7, characterized in that: The U-shaped spring is made of spring steel.

9. A single-sided blind bolt structure for riveting as described in claim 1, characterized in that: The outer side of the core rod body away from the drive end is provided with an external thread, and the inner wall of the compression nut is provided with an internal thread that matches the external thread. The compression nut is threadedly connected to the core rod. The second through hole on the compression nut is an oblique circular hole, and the opening faces inward toward one end of the universal rotating head.

10. A single-sided blind bolt structure for riveting as described in claim 1, characterized in that: The compression nut is made of GH4169 high-temperature alloy material.

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