Self-plugging rivet with adjustable pre-tightening force

Abstract

The invention provides a self-plugging rivet with an adjustable pre-tightening force. The self-plugging rivet comprises a core rod, a rivet sleeve, a pre-tightening force adjusting threaded rod, an extrusion nut, a U-shaped spring and a pre-tightening force adjusting universal rotating head. The nail sleeve is sleeved with the core rod, the core rod penetrates through the nail sleeve, the core rod is sleeved with the pre-tightening force adjusting threaded rod in a threaded mode, the pre-tightening force adjusting threaded rod is rotationally connected with the pre-tightening force adjusting universal rotating head, the pre-tightening force adjusting universal rotating head is connected with the U-shaped spring, the core rod is sleeved with the extrusion nut in a threaded mode, and the extrusion nut is connected with the nail sleeve in a sawtooth mode. The pre-tightening force adjusting threaded rod, the U-shaped spring and the pre-tightening force adjusting universal rotating head are all located in the core rod. The high-reliability spin riveting type self-plugging rivet has the beneficial effects that the high-reliability spin riveting type self-plugging rivet is simple in structure, high in shear resistance, neat in section after forming, adjustable in pre-tightening force and free of looseness forever.

Description

Technical Field

[0001] The invention belongs to the technical field of fasteners, and in particular relates to a blind rivet with adjustable pre-tightening force. Background Art

[0002] Blind rivets are single-sided fasteners suitable for closed structures (such as boxes, pipes, and thin plates) that cannot be accessed from the other side. Their core structure consists of a rivet body (nail sleeve) and a core rod (nail core). A rivet gun applies tension, breaking the core rod and expanding the rivet body to form a mechanical lock. Installation can be completed without the need for tools to access the other side.

[0003] In the manufacturing of high-end equipment such as aerospace, designers often use blind rivets to fasten components to meet the needs of lightweight, high-strength connections and quick installation. Blind rivets can achieve single-sided connections, and the riveting process requires a rivet gun or a rotary riveter. They are particularly suitable for scenarios where conventional rivets are inconvenient to install (double-sided connections). Currently, common blind rivets can only provide a preload force. When connecting materials of different strengths, products of different specifications must be used to meet the connection requirements. This leads to a complex variety of blind rivet products on the market and a wide range of specifications. Summary of the Invention

[0004] In view of this, the present invention aims to propose a blind rivet with adjustable preload force to solve the problems of the existing blind rivets, such as the inability to provide adjustable preload force, resulting in complicated product types and numerous specifications.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] An adjustable preload blind rivet, characterized by comprising a core rod, a rivet sleeve, a preload adjustment threaded rod, an extrusion nut, a U-shaped spring and a preload adjustment universal rotating head;

[0007] The nail sleeve is sleeved with the core rod, and the core rod passes through the nail sleeve, the core rod is threadedly sleeved with the preload adjustment threaded rod, the preload adjustment threaded rod is rotatably connected to the preload adjustment universal rotating head, the preload adjustment universal rotating head is connected to the U-shaped spring, the extrusion nut is threadedly sleeved with the core rod, and the extrusion nut is connected to the nail sleeve serrations, the preload adjustment threaded rod, the U-shaped spring and the preload adjustment universal rotating head are all located inside the core rod;

[0008] The core rod includes a flat driving end, a broken neck groove, a supporting surface, a thread 1, a U-shaped spring accommodating chamber, two core rod oblique circular holes, two U-shaped spring mounting grooves, and a preload adjustment rod accommodating chamber. The core rod head is provided with a flat driving end, the core rod neck is provided with a broken neck groove, the broken neck groove is connected to the supporting surface, the core rod tail is provided with a thread 1, and the thread 1 is an external thread. A U-shaped spring accommodating chamber is provided in the core rod tail, and core rod oblique circular holes are provided directly above and directly below the U-shaped spring accommodating chamber, and the two core rod oblique circular holes are mirror-symmetrical along the axis. U-shaped spring mounting grooves are provided directly above and directly below the U-shaped spring accommodating chamber, and the U-shaped spring mounting grooves are communicated with the core rod oblique circular holes. A preload adjustment rod accommodating chamber is provided inside the core rod, and the preload adjustment rod accommodating chamber is communicated with the U-shaped spring accommodating chamber.

[0009] Furthermore, the nail sleeve includes a supporting end, a local annealing area, a local quenching area, a serrated end and a cross groove. The nail sleeve head is provided with a supporting end, the inner conical surface of the supporting end matches the supporting surface of the core rod, and the two are in contact with each other. A cross groove is provided on the top of the supporting end, the supporting end is connected to the local annealing area, the local annealing area is connected to the local quenching area, and the end of the local quenching area is provided with a serrated end.

[0010] Furthermore, the preload adjustment threaded rod includes a straight drive groove, a threaded drive rod and a spherical rotating joint external buckle. The head of the preload adjustment threaded rod is provided with a straight drive groove, the base of the preload adjustment threaded rod is provided with a threaded drive rod, the outside of the threaded drive rod is provided with an external thread, the preload adjustment threaded rod is threadedly connected to the preload adjustment rod accommodating cavity, and the tail of the preload adjustment threaded rod is provided with a spherical rotating joint external buckle.

[0011] Furthermore, the extrusion nut includes a serrated end two, a closing area, six extrusion nut oblique circular holes and a thread two. The extrusion nut head is provided with a serrated end two, the serrated end two matches the serrated end one of the nail sleeve, and the two are connected. The extrusion nut is provided with a thread two, the thread two is an internal thread, the thread two matches the thread one of the core rod, and the two are connected. Three extrusion nut oblique circular holes are opened directly above and directly below the inside of the extrusion nut. The six extrusion nut oblique circular holes are mirror-symmetrical along the axis, and the closing area is formed by three-point extrusion.

[0012] Furthermore, the U-shaped spring includes an unlocking end and two locking ends. The U-shaped spring is U-shaped and has a mirror-symmetrical structure. The unlocking end is located in the middle of the U-shaped spring and is connected to the preload adjustment universal rotating head. The locking end is located at both ends of the U-shaped spring and is inserted into the oblique circular hole of the core rod or into the upper and lower overlapping oblique circular holes of the core rod and the oblique circular hole of the extrusion nut.

[0013] Furthermore, the preload adjustment universal rotating head includes a spherical rotating head, a U-shaped spring unlocking rectangular slot and a preload adjustment universal shaft. The head of the preload adjustment universal rotating head is provided with a spherical rotating head, and the spherical rotating head is rotatably connected to the spherical rotating joint of the preload adjustment threaded rod. The base of the preload adjustment universal rotating head is the preload adjustment universal shaft. The preload adjustment universal shaft is provided with a U-shaped spring unlocking rectangular slot, and the U-shaped spring unlocking rectangular slot is connected to the unlocking end of the U-shaped spring.

[0014] Furthermore, the local annealing area is a softening area, and the local quenching area is a hardening area.

[0015] Furthermore, the I-shaped driving groove is adapted to the I-shaped handle of the preload adjustment rod rotating driving head, and the preload adjustment threaded rod is rotated by the preload adjustment rod rotating driving head.

[0016] Furthermore, the oblique circular hole of the core rod is adapted to the locking end of the U-shaped spring, and the oblique circular hole of the extrusion nut is adapted to the locking end of the U-shaped spring.

[0017] Compared with the prior art, the adjustable preload blind rivet of the present invention has the following beneficial effects:

[0018] (1) The present invention designs a high-reliability spin-riveted blind rivet with a simple structure, high shear resistance, neat cross-section after forming, adjustable preload force and never loosening;

[0019] (2) Compared with ordinary blind rivets, the present invention is innovative in structural design. During installation, the preload force can be adjusted in three levels. At the same time, the preload force adjustment rod is designed to be a threaded connection type, so that the preload force adjustment threaded rod is completely locked after riveting is completed;

[0020] (3) The present invention enlarges the flat part at the tail of the core rod and the middle hole, increases the tightening torque at the tail of the core rod, reduces the risk of riveting slippage failure, and effectively improves the installation qualification rate and the service life of the installation tools. At the same time, due to the increase in the tightening torque at the tail of the core rod, the length of the flat part at the tail of the core rod is reduced by about 50%, which greatly reduces the production cost of the product. The design of enlarging the flat part at the tail of the core rod and the middle hole improves the flatness of the final riveted fracture. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0023] Figure 2This is a schematic diagram of a core rod according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of a nail sleeve according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of an extrusion nut according to an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of a U-shaped spring according to an embodiment of the present invention;

[0027] Figure 6 A schematic diagram of a preload adjustment rod according to an embodiment of the present invention;

[0028] Figure 7 Schematic diagram of a preload adjustment universal rotary head according to an embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of the assembly of the preload adjustment rod and the preload adjustment universal rotating head according to an embodiment of the present invention;

[0030] Figure 9 A schematic diagram of a rotary drive head for a preload adjustment rod according to an embodiment of the present invention;

[0031] Figure 10 This is a schematic diagram of the initial riveting state according to an embodiment of the present invention;

[0032] Figure 11 This is a schematic diagram of a state where the riveting is performed to a first level of preload and the system is locked, according to an embodiment of the present invention;

[0033] Figure 12 Schematic diagram of the rivet according to an embodiment of the present invention being unlocked by rotating the driving head through the preload adjustment rod;

[0034] Figure 13 This is a schematic diagram of driving the rivet toward a higher preload force position after unlocking according to an embodiment of the present invention;

[0035] Figure 14 This is a schematic diagram of the rivet according to an embodiment of the present invention restoring the position of the preload adjustment rod by rotating the driving head through the preload adjustment rod;

[0036] Figure 15 This is a schematic diagram of riveting to the second level of preload and locking according to an embodiment of the present invention;

[0037] Figure 16 This is a schematic diagram showing the completion of installation of the intermediate and highest preload force gears according to an embodiment of the present invention.

[0038] Description of reference numerals:

[0039] 1. Core rod; 11. Flat drive end; 12. Neck break groove; 13. Support surface; 14. Thread one; 15. U-shaped spring accommodating chamber; 16. Core rod oblique circular hole; 17. U-shaped spring mounting groove; 18. Preload adjustment rod accommodating chamber; 2. Nail sleeve; 21. Support end; 22. Local annealing area; 23. Local quenching area; 24. Serrated end one; 25. Cross groove; 3. Preload adjustment threaded rod; 31. I-shaped drive groove; 32. Threaded drive rod; 33. External buckle of spherical rotary joint; 4. Extrusion nut; 41. Serrated end two; 42. Closing area; 43. Extrusion nut oblique circular hole; 44. Thread two; 5. U-shaped spring; 51. Locking end; 52. Unlocking end; 6. Preload adjustment universal swivel head; 61. Spherical swivel head; 62. U-shaped spring unlocking rectangular slot. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0044] like Figures 1 to 16As shown, an adjustable preload force blind rivet includes a core rod 1, a nail sleeve 2, a preload force adjustment threaded rod 3, an extrusion nut 4, a U-shaped spring 5 and a preload force adjustment universal rotating head 6. The nail sleeve 2 is sleeved on the core rod 1, and the core rod 1 passes through the nail sleeve 2. The core rod 1 is threadedly sleeved on the preload force adjustment threaded rod 3, and the preload force adjustment threaded rod 3 is rotatably connected to the preload force adjustment universal rotating head 6. The preload force adjustment universal rotating head 6 is connected to the U-shaped spring 5. The extrusion nut 4 is threadedly sleeved on the core rod 1, and the extrusion nut 4 is serrated with the nail sleeve 2. The preload force adjustment threaded rod 3, U-shaped spring 5 and the preload force adjustment universal rotating head 6 are all located inside the core rod 1.

[0045] The specific implementation is as follows:

[0046] In a preferred embodiment of the present invention, the core rod 1 includes a flat driving end 11, a broken neck groove 12, a support surface 13, a thread 14, a U-shaped spring accommodating chamber 15, two core rod oblique circular holes 16, two U-shaped spring mounting grooves 17, and a preload adjustment rod accommodating chamber 18. The core rod 1 is provided with a flat driving end 11 at the head, a broken neck groove 12 at the neck of the core rod 1, and the broken neck groove 12 is connected to the support surface 13. The tail of the core rod 1 is provided with a thread 14, and the thread 14 is an external thread. A U-shaped spring accommodating chamber 15 is provided in the tail end of the core rod 1, and core rod oblique circular holes 16 are provided directly above and below the U-shaped spring accommodating chamber 15, and the two core rod oblique circular holes 16 are mirror-symmetrical along the axis, and U-shaped spring mounting grooves 17 are provided directly above and below the U-shaped spring accommodating chamber 15, and the U-shaped spring mounting grooves 17 are communicated with the core rod oblique circular holes 16, and a preload adjustment rod accommodating chamber 18 is provided inside the core rod 1, and the preload adjustment rod accommodating chamber 18 is communicated with the U-shaped spring accommodating chamber 15. In this embodiment, the flat driving end 11 rotates with the chuck inside the rivet gun head to drive the rivet. The flat driving end 11 is a thickened flat design, which increases the wrench torque while shortening the flat length of the tail. The diameter of the middle circular hole is correspondingly increased to ensure that a stepped hole flush with the cross section is formed, thereby improving the flushness of the final fracture. The broken neck groove 12 is the smallest diameter point of the core rod 1. When the torque of the core rod 1 reaches the limit value, it breaks here and the riveting process ends. The supporting surface 13 is a smooth structure, and its surface treatment will coat it with a lubricating layer, which slides relative to the inner conical surface of the nail sleeve 2. The threaded area can realize the relative movement of the extrusion nut 4 and the core rod 1, and ensure that the two will not slide relative to each other after the riveting is completed. The U-shaped spring accommodating cavity 15 can hold the U-shaped spring 5. The U-shaped spring mounting groove 17 and the oblique circular hole are used to guide the installation and fix the U-shaped spring 5. The preload adjustment rod accommodating cavity 18 is used to place the preload adjustment rod that transitionally matches it.

[0047] In a preferred embodiment of the present invention, the nail sleeve 2 includes a supporting end 21, a local annealing area 22, a local quenching area 23, a serrated end 24 and a cross groove 25. The head of the nail sleeve 2 is provided with a supporting end 21, the inner conical surface of the supporting end 21 matches the supporting surface 13 of the core rod 1, and the two are in contact with each other. A cross groove 25 is provided on the top of the supporting end 21, the supporting end 21 is connected to the local annealing area 22, the local annealing area 22 is connected to the local quenching area 23, and a serrated end 24 is provided at the end of the local quenching area 23. The local annealing area 22 is a softening area, and the local quenching area 23 is a hardening area. In this embodiment, the outer conical surface of the support end 21 is adapted to the mounting hole, and the inner conical surface is adapted to the support surface 13 of the core rod 1. The local annealing area is a softened area of the nail sleeve 2, and the extrusion nut 4 is squeezed here to deform to form a bulge foot. The local quenching area is a hardened area, and its serrated end matches the tooth surface of the serrated end of the extrusion nut 4. The local quenching area does not deform under the extrusion of the extrusion nut 4, and the cross groove 25 matches the cross tooth of the rivet gun head.

[0048] In a preferred embodiment of the present invention, the preload adjustment threaded rod 3 includes a straight drive groove 31, a threaded drive rod 32 and a spherical rotary joint external buckle 33. The head of the preload adjustment threaded rod 3 is provided with a straight drive groove 31, the base of the preload adjustment threaded rod 3 is provided with a threaded drive rod 32, the outside of the threaded drive rod 32 is provided with an external thread, the preload adjustment threaded rod 3 is threadedly connected to the preload adjustment rod accommodating cavity 18, the tail of the preload adjustment threaded rod 3 is provided with a spherical rotary joint external buckle 33, the straight drive groove 31 is adapted to the straight handle of the preload adjustment rod rotary drive head, and the preload adjustment threaded rod 3 is rotated by twisting the preload adjustment rod rotary drive head. In this embodiment, the I-shaped drive groove 31 is used to adapt to the I-shaped handle at the upper end of the preload adjustment rod rotating drive head. The preload adjustment rod rotating drive head drives the preload adjustment threaded rod 3, thereby unlocking the U-shaped spring 5. The preload adjustment threaded rod 3 matches the internal thread of the core rod 1 to prevent relative sliding between the preload adjustment threaded rod 3 and the core rod 1 after riveting is completed.

[0049] In a preferred embodiment of the present invention, the extrusion nut 4 includes a serrated end 241, a closing area 42, six extrusion nut oblique circular holes 43 and a thread 24. The head of the extrusion nut 4 is provided with a serrated end 241, and the serrated end 21 matches the serrated end 24 of the nail sleeve 2, and the two are connected. The inside of the extrusion nut 4 is provided with a thread 24, and the thread 244 is an internal thread. The thread 244 matches the thread 14 of the core rod 1, and the two are connected. Three extrusion nut oblique circular holes 43 are opened directly above and directly below the inside of the extrusion nut 4. The six extrusion nut oblique circular holes 43 are mirror-symmetrical along the axis, and the closing area 42 is formed by three-point extrusion. In this embodiment, the toothed surface of the serrated end 41 is matched with the serrated end 24 of the nail sleeve 2, and the closing area 42 is formed by three-point extrusion to ensure a certain locking force during installation and anti-loosening performance after installation. There are three groups of oblique circular holes, and each group of oblique circular holes is symmetrical along the axis of the extrusion nut 4. The three groups of oblique circular holes are axially spaced a certain distance apart and correspond to the insertion positions of the U-shaped spring 5 of the three-speed preload force. This structure is a key structure for realizing the three-speed adjustable preload force, ensuring the anti-loosening effect after installation. The internal thread area is threaded with the core rod 1 to realize the rotation of the drive nut relative to the core rod 1.

[0050] In a preferred embodiment of the present invention, the U-shaped spring 5 includes an unlocking end 52 and two locking ends 51. The U-shaped spring 5 is U-shaped and has a mirror-symmetrical structure. The unlocking end 52 is located in the middle of the U-shaped spring 5, and the unlocking end 52 is connected to the preload adjustment universal rotating head 6. The locking end 51 is located at both ends of the U-shaped spring 5, and the locking end 51 is inserted into the core rod oblique circular hole 16 or the upper and lower overlapping core rod oblique circular hole 16 and the extrusion nut oblique circular hole 43. The core rod oblique circular hole 16 is adapted to the locking end 51 of the U-shaped spring 5, and the extrusion nut oblique circular hole 43 is adapted to Equipped with a locking end 51 of a U-shaped spring 5, the preload adjustment universal rotating head 6 includes a spherical rotating head 61, a U-shaped spring unlocking rectangular slot 62 and a preload adjustment universal shaft. The head of the preload adjustment universal rotating head 6 is provided with a spherical rotating head 61, and the spherical rotating head 61 is rotatably connected to the spherical rotating joint outer buckle 33 of the preload adjustment threaded rod 3. The base of the preload adjustment universal rotating head 6 is a preload adjustment universal shaft. The preload adjustment universal shaft is provided with a U-shaped spring unlocking rectangular slot 62, and the U-shaped spring unlocking rectangular slot 62 is connected to the unlocking end 52 of the U-shaped spring 5. In this embodiment, the preload adjustment threaded rod 3 rotates forward or reverse to drive the preload adjustment universal rotating head 6 to move forward or backward, thereby driving the U-shaped spring 5 to contract or restore. When the U-shaped spring 5 contracts, the locking end 51 is pulled out from the oblique circular hole 43 of the extrusion nut, and the locking end 51 is only inserted into the oblique circular hole 16 of the core rod, thereby realizing the relative movement of the unlocking extrusion nut 4 and the core rod 1. When the U-shaped spring 5 restores, the locking end 51 is inserted into the overlapping oblique circular hole 16 of the core rod and the oblique circular hole 43 of the extrusion nut, thereby realizing the relative movement of the locking extrusion nut 4 and the core rod 1.

[0051] Example 1:

[0052] First, a rivet hole that is compatible with the blind rivet is processed on the part to be riveted and the base, and then the assembled blind rivet is inserted into the rivet hole so that the nail cap support end 21 on the nail sleeve 2 is pressed against the rivet hole opening of the part to be riveted; then the flat driving end 11 at the end of the flat core rod 1 is inserted into the rivet gun head that is compatible with its shape. Then the nail sleeve 2 of the blind rivet is pressed against the installation base through the rivet gun head. The end face of the rivet gun head is cross-toothed and fits tightly with the cross groove 25 on the surface of the support end 21 of the nail sleeve 2. Then the rivet gun trigger is pressed and the rivet gun starts to work. The rivet gun head will rotate at a certain speed, which will drive the core rod 1 to rotate at the same time. The nail sleeve 2 will not rotate because it fits tightly with the cross groove 25 on the end face of the gun head. The serrated end of the extrusion nut 4 and the top of the nail sleeve 2 are coupled through the serrated shape and will not rotate. The front end of the core rod 1 drives the extrusion nut 4 to move toward the installation position under the drive of the thread. Due to the high strength of the material, the extrusion nut 4 itself will not be deformed, but the local annealing area 22 of the nail sleeve 2 will be squeezed and deformed, slowly forming a bulge foot. As the rivet gun continues to rotate, the nail sleeve 2 is extruded and bulges more Since the core rod 1 and the extrusion nut 4 are locked by the U-shaped spring 5, the core rod 1 will not be able to rotate. Subsequently, under the torsion force of the rivet gun chuck, it can only break from the neck groove 12 at the end of the core rod 1, thus completing the entire installation process.

[0053] If the first gear preload cannot meet the connection requirements, the preload can be increased to the second or third gear of the blind rivet. When the blind rivet is installed to the first gear preload state, the rivet gun works for a cycle and is in a stopped state. Pull out the rivet gun, use the preload adjustment rod to rotate the driving head to insert it into the tail slot of the preload adjustment rod, and rotate the preload adjustment rod to drive the preload adjustment rod away from the installation position. Since the bottom end of the U-shaped spring unlocking rectangular slot 62 of the preload adjustment universal rotating head 6 is against the middle unlocking end 52 of the U-shaped spring 5, the oblique locking ends 51 at both ends of the U-shaped spring 5 slide out of the oblique circular hole of the extrusion nut 4 under the action of the ejection force, and the preload adjustment rod moves to the unlocking position, completing the unlocking of the core rod 1 and the extrusion nut 4. At this time, the preload adjustment rod rotating drive head is removed, the rivet gun is reinstalled, and the rivet gun trigger is pulled. The rivet gun continues to work, driving the core rod 1 to rotate. After rotating to a certain angle, for example, degrees, the oblique circular hole on the core rod 1 and the oblique circular hole of the extrusion nut 4 are misaligned. When the rivet gun stops working for one cycle, the oblique circular hole in the core rod 1 coincides with the second-stage preload oblique circular hole on the extrusion nut 4. At this time, the rivet gun is removed, and the preload adjustment rod rotating drive head is reinserted to rotate in the opposite direction, driving the preload adjustment rod and the preload adjustment universal rotating head 6 to move toward the mounting plate. When the locking end 51 of the U-shaped spring 5 coincides with the second-stage preload oblique circular hole of the extrusion nut 4, it will quickly reset. During this process, the extruded and deformed part of the nail sleeve 2 will be subjected to greater preload, forming a larger bulge foot. After that, you can choose to complete the installation or continue to increase the clamping force installation according to the assembly working conditions. The process is the same as the first stage before, so it will not be explained again.

[0054] Working principle of the present invention:

[0055] The present invention can achieve the effect of three-level preload adjustment during the installation process. When performing single-sided connection of softer materials, the first level preload can be used for riveting. This process can be achieved by lightly pressing the rivet gun trigger. The extrusion nut 4 is displaced relative to the core rod 1 toward the end of the rivet gun under the thread drive. The U-shaped spring 5 enters the oblique circular hole of the first-level U-shaped spring installation groove 17. The preload adjustment threaded rod 3 is completely locked. At this time, if you want to end the installation, you only need to continue to press the rivet gun trigger. The chuck will continue to drive the tail of the core rod 1 to rotate under the action of compressed air, and finally it can only break from the neck groove 12 at the end of the core rod 1, thereby completing the first-level preload riveting installation process. After the screwdriver is driven, the rivet gun is rotated and the rivet gun is turned, and the rivet gun is rotated again, and the rivet gun is turned again, and the rivet gun is turned again, and the rivet gun is turned again, and the rivet gun is turned again, and the rivet gun is turned again, and the rivet gun is turned again, the rivet gun is turned again, and the rivet gun is turned again, and the rivet gun is turned again, the rivet gun is turned again, and the rivet gun is turned again, and the rivet gun is turned again, the rivet gun is turned again, and the rivet gun is turned again, and the rivet gun is turned again, the rivet gun is turned again, and the rivet gun is turned again, When the rivet is tightened, the rivet sleeve 2 is tightened again, and the rivet sleeve 2 is tightened again. At this point, the rivet's clamping force is at the second level, or the middle level. To apply a higher preload to the mounting plate, the rivet can be installed at the third level, following the same process as above. This level will result in the maximum preload and the largest deformed bulge.

[0056] When assembling the components of the present invention, first, insert the preload adjustment threaded rod 3 from the head of the core rod 1 into the preload adjustment rod accommodating cavity 18, then insert the U-shaped spring 5 into the U-shaped spring unlocking rectangular slot 62 of the preload adjustment universal rotating head 6, and then insert the preload adjustment universal rotating head 6 from one end of the U-shaped spring accommodating cavity 15 of the core rod 1 into the preload adjustment rod accommodating cavity 18 of the core rod 1, so that it is connected with the preload adjustment threaded rod 3, and install the U-shaped spring 5 into the U-shaped spring installation groove 17 of the core rod 1. At this time, the U-shaped spring 5 is at In the compressed state, the core rod 1 equipped with the U-shaped spring 5 is then passed through the tapered hole at the head of the nail sleeve 2, so that the support surface 13 of the core rod 1 and the inner conical surface of the nail sleeve 2 are tightly attached, and then the extrusion nut 4 is screwed in from the threaded end of the core rod 1 until the toothed surface of the extrusion nut 4 and the toothed surface of the nail sleeve 2 are in contact and engaged, and then the position of the U-shaped spring 5 is adjusted until the ends of the U-shaped spring 5 pass through the oblique circular hole of the core rod 1 under the action of elasticity, and then the extrusion nut 4 is squeezed and closed with a closing device, thereby completing the component assembly process of the blind rivet.

[0057] Rivet gun operation instructions: When the operator pulls the trigger of the rivet gun and holds it in the firing state, the rivet gun will continue to rotate for a specific time, such as five or ten seconds, and then automatically stop rotating, even if the operator still holds the trigger in the firing state. Only when the operator releases the trigger of the rivet gun, allowing the trigger to automatically reset, and then pulls the trigger again, will the rivet gun continue to rotate for the same specific time and then automatically stop again.

[0058] Instructions for use of the preload adjustment rod rotary drive head: When the preload gear needs to be unlocked, insert it into the middle hole of the flat drive end 11 at the tail of the core rod 1. The top straight handle cooperates with the straight drive groove 31 at the tail of the preload adjustment rod. By twisting the preload adjustment universal shaft, the shaft is displaced relative to the core rod 1. After rotating it to a certain angle, the U-shaped spring 5 is driven to leave the oblique circular hole of the drive nut (but will not leave the oblique circular hole of the core rod 1), thereby unlocking the U-shaped spring 5. After removing the preload adjustment rod rotary drive head, continue to use the rivet gun for subsequent preload shifting operations. When the drive nut squeezes the nail sleeve 2 to reach the next preload gear, insert the preload adjustment rod rotary drive head again and restore the preload adjustment rod by reverse rotation.

[0059] Beneficial effects and advantages of the present invention:

[0060] (1) The present invention designs a high-reliability spin-riveted blind rivet with a simple structure, high shear resistance, neat cross-section after forming, adjustable preload force and never loosening;

[0061] (2) Compared with ordinary blind rivets, the present invention is innovative in structural design. During installation, the preload force can be adjusted in three levels. At the same time, the preload force adjustment rod is designed to be a threaded connection type, so that the preload force adjustment threaded rod is completely locked after riveting is completed;

[0062] (3) The present invention enlarges the flat part at the tail of the core rod and the middle hole, increases the tightening torque at the tail of the core rod, reduces the risk of riveting slippage failure, and effectively improves the installation qualification rate and the service life of the installation tools. At the same time, due to the increase in the tightening torque at the tail of the core rod, the length of the flat part at the tail of the core rod is reduced by about 50%, which greatly reduces the production cost of the product. The design of enlarging the flat part at the tail of the core rod and the middle hole improves the flatness of the final riveted fracture.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A blind rivet with adjustable preload, characterized by: It comprises a core rod (1), a nail sleeve (2), a preload adjustment threaded rod (3), an extrusion nut (4), a U-shaped spring (5) and a preload adjustment universal rotating head (6); The nail sleeve (2) is sleeved with the core rod (1), and the core rod (1) passes through the nail sleeve (2); the core rod (1) is threadedly sleeved with the preload adjustment threaded rod (3); the preload adjustment threaded rod (3) is rotatably connected to the preload adjustment universal rotating head (6); the preload adjustment universal rotating head (6) is connected to the U-shaped spring (5); the extrusion nut (4) is threadedly sleeved with the core rod (1), and the extrusion nut (4) is serratedly connected to the nail sleeve (2); the preload adjustment threaded rod (3), the U-shaped spring (5) and the preload adjustment universal rotating head (6) are all located inside the core rod (1); The core rod (1) comprises a flat driving end (11), a broken neck groove (12), a supporting surface (13), a thread one (14), a U-shaped spring accommodating cavity (15), two core rod oblique circular holes (16), two U-shaped spring mounting grooves (17), and a preload adjustment rod accommodating cavity (18). The core rod (1) is provided with a flat driving end (11) at its head, a broken neck groove (12) at its neck, and the broken neck groove (12) is connected to the supporting surface (13). The core rod (1) is provided with a thread one (14) at its tail, and the thread one (14) is an external thread. A U-shaped spring accommodating chamber (15) is provided in the tail of the rod (1), a core rod oblique circular hole (16) is provided directly above and directly below the U-shaped spring accommodating chamber (15), and the two core rod oblique circular holes (16) are mirror-symmetrical along the axis, a U-shaped spring mounting groove (17) is provided directly above and directly below the U-shaped spring accommodating chamber (15), and the U-shaped spring mounting groove (17) is communicated with the core rod oblique circular hole (16), a preload adjustment rod accommodating chamber (18) is provided inside the core rod (1), and the preload adjustment rod accommodating chamber (18) is communicated with the U-shaped spring accommodating chamber (15).

2. The blind rivet with adjustable preload according to claim 1, characterized in that: The nail sleeve (2) comprises a supporting end (21), a local annealing area (22), a local quenching area (23), a serrated end (24) and a cross groove (25); the head of the nail sleeve (2) is provided with a supporting end (21); the inner conical surface of the supporting end (21) matches the supporting surface (13) of the core rod (1), and the two are in contact; the top of the supporting end (21) is provided with a cross groove (25); the supporting end (21) is connected to the local annealing area (22); the local annealing area (22) is connected to the local quenching area (23); and the end of the local quenching area (23) is provided with a serrated end (24).

3. The blind rivet with adjustable preload according to claim 1, characterized in that: The preload adjustment threaded rod (3) comprises a straight driving groove (31), a threaded driving rod (32) and a spherical rotating joint external buckle (33); the head of the preload adjustment threaded rod (3) is provided with a straight driving groove (31); the base of the preload adjustment threaded rod (3) is provided with a threaded driving rod (32); an external thread is provided on the outside of the threaded driving rod (32); the preload adjustment threaded rod (3) is threadedly connected to the preload adjustment rod accommodating cavity (18); and the tail of the preload adjustment threaded rod (3) is provided with a spherical rotating joint external buckle (33).

4. The blind rivet with adjustable preload according to claim 2, characterized in that: The extrusion nut (4) comprises a second serrated end (41), a closing region (42), six extrusion nut oblique circular holes (43) and a second thread (44). The head of the extrusion nut (4) is provided with a second serrated end (41), the second serrated end (41) matches the first serrated end (24) of the nail sleeve (2), and the two are connected. The interior of the extrusion nut (4) is provided with a second thread (44), the second thread (44) is an internal thread, the second thread (44) matches the first thread (14) of the core rod (1), and the two are connected. Three extrusion nut oblique circular holes (43) are provided directly above and directly below the interior of the extrusion nut (4), the six extrusion nut oblique circular holes (43) are mirror-symmetrical along the axis, and the closing region (42) is formed by three-point extrusion.

5. The blind rivet with adjustable preload according to claim 4, characterized in that: The U-shaped spring (5) includes an unlocking end (52) and two locking ends (51). The U-shaped spring (5) is U-shaped and has a mirror-symmetrical structure. The unlocking end (52) is located in the middle of the U-shaped spring (5) and is connected to the preload adjustment universal rotating head (6). The locking ends (51) are located at both ends of the U-shaped spring (5), and the locking ends (51) are inserted into the core rod oblique circular hole (16) or into the core rod oblique circular hole (16) and the extrusion nut oblique circular hole (43) that overlap with each other.

6. The blind rivet with adjustable preload according to claim 3 or 5, characterized in that: The preload force adjustment universal rotating head (6) comprises a spherical rotating head (61), a U-shaped spring unlocking rectangular slot (62) and a preload force adjustment universal shaft. The head of the preload force adjustment universal rotating head (6) is provided with a spherical rotating head (61). The spherical rotating head (61) is rotatably connected to the spherical rotating joint outer buckle (33) of the preload force adjustment threaded rod (3). The base of the preload force adjustment universal rotating head (6) is the preload force adjustment universal shaft. The preload force adjustment universal shaft is provided with a U-shaped spring unlocking rectangular slot (62). The U-shaped spring unlocking rectangular slot (62) is connected to the unlocking end (52) of the U-shaped spring (5).

7. The blind rivet with adjustable preload according to claim 2, characterized in that: The local annealing area (22) is a softening area, and the local quenching area (23) is a hardening area.

8. The blind rivet with adjustable preload according to claim 3, characterized in that: The I-shaped driving groove (31) is adapted to the I-shaped handle of the preload adjustment rod rotary driving head, and the preload adjustment threaded rod (3) is rotated by the preload adjustment rod rotary driving head.

9. The blind rivet with adjustable preload according to claim 5, characterized in that: The core rod oblique circular hole (16) is adapted to fit the locking end (51) of the U-shaped spring (5), and the extrusion nut oblique circular hole (43) is adapted to fit the locking end (51) of the U-shaped spring (5).

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