Pre-tightening force enhanced type spin riveting blind bolt

Abstract

The invention provides a pre-tightening force enhanced type spin riveting blind bolt. The pre-tightening force enhanced type spin riveting blind bolt comprises a core rod, and a driving body, an expansion ring, a forming sleeve, a nail body, a locking ring and a spinning bushing which are arranged on the core rod in a sleeving manner, wherein the core rod is of a slender rod structure, the tail end of the core rod is connected with the riveter chuck, a broken diameter groove is formed in the middle of the core rod, and an end head is arranged at the head end of the core rod; the driving body, the forming sleeve and the nail body are of an integrally-arranged tubular structure, the forming sleeve forms a flexible deformation area, a containing cavity used for containing the expansion ring is formed in the forming sleeve, and the driving body is connected with the head end of the core rod in a clamped mode. The spinning bush is of a rotary body structure internally provided with a stepped hole, the locking ring is arranged in the stepped hole and connected with the end face of the stepped hole of the spinning bush in a meshed mode, and a shearing groove is formed in the outer ring of the spinning bush. The core rod pulling and rotating combined motion mode is achieved, the pre-tightening force of a product can be improved by 50% or above, and the connecting requirement of a high-clamping-force connecting part can be better met.

Description

Technical Field

[0001] This application belongs to the technical field of fasteners, and particularly relates to a pre-tightening force enhanced rotary pull riveting blind bolt. Background Art

[0002] During the design process of high-end equipment such as aerospace, considering factors such as volume and weight, the structural design is generally relatively compact. The connection and installation space of these compact structural parts is relatively narrow. Ordinary bolt and nut fasteners cannot meet the installation requirements of these occasions because they require double-sided installation. Therefore, riveting is generally selected in occasions where the installation space is relatively narrow and it is not convenient for double-sided operation. The riveting method used at the structural connection is generally a blind rivet. Blind rivets have the characteristics of light weight, more reliable connection, high strength, convenient and fast installation, etc., and have been widely used in various aerospace vehicles.

[0003] The currently used blind rivets are basically pull riveting type and rotary riveting type blind rivets, which drive the core rod to pull or rotate with a single action through a riveting gun, causing the nail sleeve to deform to achieve the function of fastening connection. The applicable sandwich range of the existing blind rivets for a single specification is relatively narrow, and more specifications need to be prepared during assembly to meet the riveting requirements of different thickness sandwiches. Moreover, the riveting fracture flatness of the existing blind rivets is mostly uneven, and a large part of the core rod fracture protrudes from the surface of the riveting body. It is necessary to perform secondary grinding treatment on the fracture of the core rod to meet the requirements of high flatness on the outer surface of stealth aircraft.

[0004] For general mechanical connection occasions, the existing blind rivets basically meet the assembly requirements of the products. However, in some special occasions, such as occasions with high requirements for pre-tightening force and riveting fracture flatness, it is also very difficult for the existing blind rivets to meet the above connection requirements. Summary of the Invention

[0005] In view of this, this application aims to propose a pre-tightening force enhanced rotary pull riveting blind bolt to solve the above technical problems.

[0006] To achieve the above object, the technical solution of this application is realized as follows: This application provides a pre-tightening force enhanced rotary pull riveting blind bolt, including a core rod, and a driving body, an expansion ring, a forming sleeve, a nail body, a locking ring and a spinning bushing sleeved on the core rod; Among them, the core rod is a slender rod structure, the end of the core rod is connected to the riveting gun chuck, a diameter-reducing groove is provided in the middle of the core rod, and a head is provided at the head end of the core rod; The driving body, the forming sleeve and the nail body are integrally arranged tubular structures. The forming sleeve forms a flexible deformation area, and an accommodation cavity for accommodating the expansion ring is provided inside it. The driving body is clamped with the head end of the core rod; The spinning bushing is a rotating structure with a stepped hole inside, and the locking ring is disposed in the stepped hole and engages with the end face of the stepped hole of the spinning bushing. The outer ring of the spinning bushing is provided with a shearing groove.

[0007] Furthermore, the end of the core rod is a flat structure and mates with a flat groove provided in the rivet gun chuck. The core rod is provided with a straight ring groove and is clamped and fixed by the rivet gun chuck. The inner wall of the end of the core rod is provided with a cross-shaped anti-rotation tooth, and the end face of the drive body is provided with a cross-shaped anti-rotation groove that cooperates with the cross-shaped anti-rotation tooth, so that the drive body and the core rod are correspondingly engaged.

[0008] Furthermore, a retaining ring groove is provided on the side of the core rod near the straight ring groove in the middle, for interference engagement with the inner hole of the spinning bushing to clamp the spinning bushing.

[0009] Furthermore, the molding sleeve is a hollow tubular structure with a rotating groove inside, and the thickness of the rotating groove at the end near the nail body is greater than the thickness at the end near the driving body, so as to form an accommodating cavity.

[0010] Furthermore, the expansion ring has a circular rotating structure, the cross-sectional shape of which matches the shape of the rotating groove, and an inclined groove is provided in the middle of the ring.

[0011] Furthermore, the nail body is a hollow rotary structure with a stepped hole inside, and the nail body also has a locking hole that communicates with the stepped hole, wherein the stepped hole cooperates with the blocking step provided in the middle of the core rod; A conical spiral locking groove is provided between the break-off groove and the blocking step. The locking groove and the locking hole cooperate to form a wedge-shaped space. The driving end of the spinning bushing pushes the locking ring so that the locking ring is squeezed into the wedge-shaped space along the locking groove.

[0012] Furthermore, the end face of the spinning bushing near the rivet gun head is a conical surface with a cone angle ranging from 150 degrees to 160 degrees, and a first meshing tooth is provided on the conical surface, which meshes with the end face of the rivet gun head.

[0013] Furthermore, the stepped hole end face inside the spinning bushing is provided with a second meshing tooth, and one side end face of the locking ring is provided with a third meshing tooth that meshes with the second meshing tooth.

[0014] Furthermore, the locking ring is a thin-walled circular structure, and the hardness of the metal matrix at one end of the third meshing tooth is greater than the hardness of the metal matrix at the other end of the locking ring.

[0015] Furthermore, the outer surface of the locking ring is also coated with a lubricating coating.

[0016] Compared with the prior art, the preload-enhanced spin-pull blind bolt described in this application has the following advantages: The preload-enhanced spin-pull blind bolt described in this application achieves a combined motion of core rod pulling and rotation by setting a rotating meshing tooth drive structure and a conical spiral structure with enhanced locking performance of the locking groove. This drives the locking ring to lock the core rod locking groove more tightly, which can increase the preload of the product by more than 50% and better meet the connection requirements of high clamping force connection parts. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 This is a schematic diagram of a preload-enhanced spin-pull rivet blind bolt installation structure according to an embodiment of this application; Figure 2 This is a schematic diagram of the core rod structure described in the embodiments of this application; Figure 3 This is a schematic diagram of the nail body, molding sleeve, expansion ring, and driving body structure described in the embodiments of this application; Figure 4 This is a schematic diagram of the spun bushing structure described in the embodiments of this application; Figure 5 This is a schematic diagram of the locking ring structure described in an embodiment of this application; Figure 6 This is a schematic diagram of the spun bushing and locking ring structure described in the embodiments of this application; Figure 7 This is a schematic diagram illustrating the combined extrusion and torsional load effect of the spinning bushing drive body on the locking ring as described in the embodiments of this application; Figure 8 This is a diagram showing the effect of the device after installation according to an embodiment of this application.

[0019] Explanation of reference numerals in the attached figures: 1-Core rod; 11-Straight ring groove; 12-Snap ring groove; 13-Break-off groove; 14-Locking groove; 15-Blocking step; 16-End; 17-Cross-shaped anti-rotation tooth; 2-Drive body; 21-Cross-shaped anti-rotation groove; 3-Expansion ring; 31-Slanted groove; 4-Forming sleeve; 41-Rotating groove; 5-Nail body; 51-Locking hole; 52-Step hole; 6-Spinning bushing; 61-First meshing tooth; 62-Second meshing tooth; 63-Shearing groove; 7-Locking ring; 71-Third meshing tooth. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0021] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can refer to any connection.

[0022] This includes electrical connections, whether direct or indirect. Terms like "up," "down," "left," and "right" are used only to indicate relative positional relationships; these relative relationships may change if the absolute position of the object being described changes.

[0023] Please see Figure 1 As shown, this embodiment provides a preload-enhanced spin-riveting blind bolt, including a core rod 1, and a drive body 2, an expansion ring 3, a forming sleeve 4, a nail body 5, a locking ring 7, and a spin-forming bushing 6 sleeved on the core rod 1; Among them, the core rod 1 is a slender rod structure. The end of the core rod 1 is connected to the rivet gun chuck. The middle part of the core rod 1 is provided with a cut-off groove 13, and the beginning end of the core rod 1 is provided with an end head 16. The driving body 2, the forming sleeve 4 and the nail body 5 are integrally formed in a tubular structure. The forming sleeve 4 forms a flexible deformation area and has an internal cavity for accommodating the expansion ring 3. The driving body 2 is engaged with the first end of the core rod 1. The spinning bushing 6 is a rotating structure with a stepped hole 52 inside, and the locking ring 7 is set in the stepped hole 52 and engages with the end face of the stepped hole 52 of the spinning bushing 6. The outer ring of the spinning bushing 6 is provided with a shearing groove 63.

[0024] The preload-enhanced rotary pull riveting blind bolt described in this embodiment has the characteristics of simple structure, easy installation and inspection, wide range of applicable interlayers, large preload, and good post-riveting flatness. By setting a rotary meshing tooth drive structure and a conical spiral structure with enhanced locking performance of locking groove 14, a combined pulling and rotating motion of core rod 1 is achieved, thereby driving locking ring 7 to more tightly lock core rod 1 and locking groove 14. This can increase the preload of the product by more than 50%, and can better meet the connection requirements of high clamping force connection parts.

[0025] In some embodiments, the end of the core rod 1 is a flat structure and cooperates with the flat groove provided in the rivet gun chuck. The core rod 1 is provided with a straight ring groove 11 and is clamped and fixed by the rivet gun chuck. The inner wall of the end 16 of the core rod 1 is provided with a cross-shaped anti-rotation tooth 17, and the end face of the drive body 2 is provided with a cross-shaped anti-rotation groove 21 that cooperates with the cross-shaped anti-rotation tooth 17, so that the drive body 2 and the core rod 1 are correspondingly engaged.

[0026] The core rod 1 has a retaining ring groove 12 on the side near the straight ring groove 11 in the middle, which is used to interfere with the inner hole of the spinning bushing 6 to clamp the spinning bushing 6.

[0027] Specifically, in this embodiment, such as Figure 2 As shown, the core rod 1 is a slender rod structure, which is provided with a straight ring groove 11, an anti-rotation flat structure, a retaining ring groove 12, a neck break groove, a spiral locking groove 14, a blocking step 15, and a cross-shaped anti-rotation tooth 17.

[0028] The purpose of the straight ring groove 11 is to increase the friction between the core rod 1 and the rivet gun chuck. When the rivet gun is working, the rivet gun chuck clamps the core rod 1 and pulls the core rod 1 backward under the action of the air piston. The straight groove prevents the rivet gun chuck from slipping when clamping the core rod 1.

[0029] The anti-rotation flat structure is designed to fit into the flat groove in the rivet gun head. The anti-rotation flat structure is inserted into the flat groove in the gun head. Since the flat groove cannot rotate, it will prevent the core rod 1 from rotating.

[0030] The retaining ring groove 12 is designed to interfer with the inner hole of the spinning bushing 6, thereby securing the spinning bushing 6 and preventing the blind bolt from loosening during transportation, storage, or handling.

[0031] The function of the neck groove is to prevent the core rod 1 from breaking at the neck groove after the combined load of the tensile force and the breaking moment exceeds the strength of the core rod 1.

[0032] After the blind end bulge is formed, the axial displacement of the core rod 1 is restricted by the two blocking steps 15. The rivet gun chuck clamps the core rod 1 and cannot move it backward. When the combined tensile and torsional load on the tail of the core rod 1 exceeds the limit that the neck groove can withstand, it will break.

[0033] The cross-shaped anti-rotation tooth 17 is designed to cooperate with the cross-shaped anti-rotation groove 21 on the drive body 2 to restrict the rotation of the nail body 5 and the core rod 1, thereby better transmitting the torque of the holster to the locking ring 7 and driving the locking ring 7 to screw into the bottom of the locking groove 14.

[0034] In some embodiments, the molding sleeve 4 is a hollow tubular structure with a rotating groove 41 inside, the thickness of the rotating groove 41 near the nail body 5 is greater than the thickness of the end near the driving body 2, so as to form a receiving cavity.

[0035] Specifically, in this embodiment, the nail body 5, the forming sleeve, and the driving body 2 are as follows: Figure 3 As shown, the nail body 5 and the driving body 2 are made of the same high-strength titanium alloy material, which has high strength and hardness, and is similar to a rigid body, so it will not deform during the riveting process; the forming sleeve is made of softer pure titanium material, which has lower hardness and is mainly used to prevent bulging deformation during the riveting process; the three parts are finally welded into one part by high-speed metal friction welding, which becomes a nail body 5 assembly with high strength at both ends and low strength in the middle.

[0036] Formed sleeves, such as Figure 3 As shown, it is a hollow tubular part with a rotating groove 41 (expansion ring 3 accommodating cavity) inside. The rotating groove 41 is thicker at the end near the head of the nail body 5 and thinner at the end near the drive body 2, which can more conveniently and evenly guide the fastener to bulge from the smallest to the largest interlayer range. The second function of the rotating groove 41 is to place the shape memory alloy expansion ring 3. The forming sleeve is made of a relatively soft pure titanium alloy material and is formed by upsetting and extrusion. Due to the presence of the groove, the middle part has slightly lower strength, which is used to bulge first during riveting. The length of the expansion ring 3 accommodating cavity is positively correlated with the applicable interlayer length of the fastener.

[0037] During the riveting process, under the squeezing action of the rivet body 5 and the driving body 2, the rotating groove 41 will gradually form a bulge at the blind end of the mounting plate, thereby achieving the purpose of clamping.

[0038] The driving body 2 is a ring-shaped part, which is made of the same high-strength titanium alloy material as the nail body 5. It is a rigid body and is not easily deformed. The right end face of the driving body 2 is provided with a cross-shaped anti-rotation groove, which cooperates with the cross-shaped anti-rotation teeth on the lower support surface of the core rod 1 to fix the driving body 2 and the core rod 1 and prevent them from rotating.

[0039] In some embodiments, the expansion ring 3 has a circular rotating structure, the cross-sectional shape of which matches the shape of the rotating groove 41, and an inclined groove 31 is provided in the middle of the ring.

[0040] Specifically, in this embodiment, the expansion ring 3 component is as follows: Figure 3 As shown, it is made of shape memory alloy material and is a circular rotating part. Its cross-sectional shape is the same as the groove shape in the forming sleeve. The ring has a slanted groove 31 in the middle, which makes the expansion ring 3 have a certain elasticity in the radial direction, so that the expansion ring 3 can be easily installed into the expansion ring 3 receiving cavity in the nail body 5 assembly.

[0041] In some embodiments, the nail body 5 is a hollow rotary structure with a stepped hole 52 inside. The nail body 5 also has a locking hole 51 that communicates with the stepped hole 52 inside. The stepped hole 52 cooperates with the blocking step 15 provided in the middle of the core rod 1. A spiral locking groove 14 with a conical structure is provided between the cut-off groove 13 and the blocking step 15. The locking groove 14 and the locking hole 51 cooperate to form a wedge-shaped space. The driving end of the spinning bushing 6 pushes the locking ring 7 so that the locking ring 7 is squeezed into the wedge-shaped space along the locking groove 14.

[0042] Specifically, in this embodiment, the nail body 5 is a hollow rotating part with a stepped hole 52 inside. The stepped hole 52 and the locking hole 51 are connected inside the nail body 5. The blocking platform is used in conjunction with the blocking step 15 of the core rod 1. During the riveting process, after the core rod 1 is pulled to the position, its displacement is restricted by the blocking platform. The locking hole 51 is used in conjunction with the locking groove 14 on the core rod 1. After the core rod 1 is pulled to the position, a wedge-shaped space is formed between the locking hole 51 of the nail body 5 and the locking groove 14 on the core rod 1, which makes it easy for the locking ring 7 to be squeezed in to achieve the locking purpose.

[0043] The locking groove 14 works in conjunction with the locking hole 51 of the nail body 5. After the core rod 1 is pulled to the position, a wedge-shaped space is formed between the core rod 1 and the nail body 5. The locking ring 7 is squeezed into the wedge-shaped space under the pushing action of the sheared spinning bushing 6, thereby achieving the purpose of locking. The locking groove 14 is also provided with a spiral tapered protruding thread. When the spinning bushing 6 spins the locking ring 7, it will screw the locking ring 7 along the tapered thread into the deeper part of the wedge-shaped locking space, which will enhance the preload. Due to the mechanical locking effect of the tapered protruding thread, the locking ring 7 will not elastically slip in the locking groove 14 at the moment the core rod 1 is twisted off, and there will be no loss of preload.

[0044] In some embodiments, the end face of the spinning bushing 6 near the rivet gun head is a conical surface with a cone angle range of 150 degrees to 160 degrees, and a first meshing tooth 61 is provided on the conical surface, which meshes with the end face of the rivet gun head. The stepped hole inside the spinning bushing 6 has a second meshing tooth 62 on its end face, and a third meshing tooth 71 that meshes with the second meshing tooth 62 is provided on one side end face of the locking ring 7.

[0045] Specifically, in this embodiment, the spun bushing 6 is as follows: Figure 4 As shown, it is a rotating part with a stepped hole inside. The end with the larger hole diameter mates with the locking ring 7 to accommodate the locking ring 7, as shown. Figure 1 and Figure 6 As shown.

[0046] During riveting, the spinning bushing 6 is first subjected to the squeezing action of the rivet gun head and the end face of the rivet body 5. When the squeezing force exceeds a certain limit, the spinning bushing 6 will break at the shearing groove 63 position of the stepped hole, thereby allowing the locking ring 7 to be pushed into the wedge-shaped locking space.

[0047] The left end face of the spinning bushing 6 is a conical surface with a cone angle ranging from 150 to 160 degrees. Engaging teeth are provided on the conical surface. During installation, it mates with the end face of the rivet gun head. The end face of the rivet gun head also has engaging teeth with a matching number and profile. When the sleeving rotates, the engagement of the engaging teeth drives the spinning bushing 6 to rotate synchronously. Engaging teeth are also provided on the end face of the stepped hole 52 inside the spinning bushing 6. After the spinning bushing 6 is sheared and the locking ring 7 base is squeezed into the locking groove 14, the sleeving drives the spinning bushing 6 drive body 2 to rotate. The spinning bushing 6 drive body 2 also transmits torque to the locking ring 7 base through the engagement of its engaging teeth with the locking ring 7's contact end face, driving the locking ring 7 to rotate synchronously. When the locking ring 7 rotates in the wedge-shaped space, it spirals along the conical spiral line on the locking groove 14 of the core rod 1 towards the bottom of the locking groove 14.

[0048] In some embodiments, the locking ring 7 is a thin-walled annular structure, and the hardness of the metal matrix at one end of the third meshing tooth 71 is greater than the hardness of the metal matrix at the other end of the locking ring 7. The outer surface of the locking ring 7 is also coated with a lubricating coating.

[0049] Specifically, in this embodiment, the locking ring 7 is as follows: Figure 5 and Figure 6 As shown, it is a thin-walled circular part composed of two metal parts. The left side is a high-hardness metal matrix with a hardness of HRC50-60, and has meshing teeth on its end face. These teeth cooperate with the meshing teeth in the stepped hole 52 of the spinning bushing 6, ensuring that the high-hardness meshing teeth on the left side are not easily deformed during use. The right side of the locking ring 7 is a lower-hardness metal with a hardness of HRC30-35. Its main function is to facilitate the plastic forming of the softer part of the locking ring 7, allowing it to be accurately and timely squeezed into the wedge-shaped locking groove 14 space, and providing sufficient locking performance to ensure the tensile and fatigue strength of the product after installation. The two metal parts of the locking ring 7 with different hardness are also welded together by high-speed rotary friction welding to form a complete part. Afterwards, simple turning is performed to remove excess metal at the weld.

[0050] The surface of the finished locking ring 7 is also coated with a special lubricating coating. When the driving body 2 of the spinning bushing 6 squeezes and twists the locking ring 7, it can more easily and stably squeeze and then spin the locking ring 7 into the wedge-shaped locking groove 14 space.

[0051] like Figure 1 , Figure 6 , Figure 7 and Figure 8 As shown, the riveting process of this structure is as follows: First, drill a riveting hole on the part to be riveted and the base that corresponds to the outer diameter of the blind rivet; then insert the assembled blind rivet into the riveting hole of the part to be riveted, so that the rivet head on the rivet body 5 is pressed against the riveting hole support surface of the part to be riveted; then insert the end of the core rod 1 into the chuck of the rivet gun, at which point the flat structure at the end of the core rod 1 is inserted into the flat groove of the rivet gun chuck, and the two are matched; then use the end face of the rivet gun head to press the spin-pressed bushing 6 of the blind rivet against it, and by applying axial force, the entire blind bolt is completely pressed against the mounting hole.

[0052] Then, press the trigger of the rivet gun, and the rivet gun starts to work. The rivet gun clamps the straight ring groove 11 at the tail of the core rod 1 of the pop rivet through the chuck inside the gun head sleeve. The chuck clamps the core rod 1 under the action of air pressure through the piston mechanism and begins to retract. At this time, the gun sleeve on the rivet gun head is still in the state of pressing against the fastener and will not move.

[0053] As the chuck clamps the core rod 1 and moves backward, the support surface under the core rod 1 compresses the driving body 2, which also moves towards the blind end plate. The driving body 2, the forming sleeve 4, and the nail body 5 are welded together as a whole by friction welding. As the driving body 2 moves towards the plate, the driving forming sleeve 4 begins to undergo compression and expansion deformation. As the core rod 1 continues to compress the driving body 2 and moves backward, the forming sleeve 4 continues to bulge and deform, eventually forming a large bulge on the plate to be installed.

[0054] After the core rod 1 retracts to its final position, that is, when the blocking step 15 of the core rod 1 coincides with the blocking step 15 of the inner hole of the nail body 5, the core rod 1 can no longer retract. However, the rivet gun chuck continues to apply tension, pulling the tail of the core rod 1. At this time, the holster is still pressed against the spinning bushing 6. When the tension exerted by the rivet gun chuck on the tail of the core rod 1 increases to a certain value, under the action of the reverse force, the spinning bushing 6 will be sheared from the shearing groove 63. Under the action of the tension of the rivet gun chuck, the sheared spinning bushing 6... The drive unit will push the locking ring 7 to move into the formed locking wedge space, and finally squeeze the locking ring 7 completely into the wedge space. At this time, the tension on the tail of the core rod 1 continues to increase under the drive of the rivet gun chuck. When it increases to the set value of the rivet gun, the second movement of the rivet gun will be triggered, that is, the gun sleeve on the gun head will start to rotate. At this time, the chuck inside the gun sleeve is still clamping the annular groove at the tail of the core rod 1 and applying a continuous and stable tension. The backward tension is also completely acted on the meshing tooth end face of the spinning bushing 6 by the gun sleeve through the reaction force.

[0055] During the rotation of the holster, the meshing teeth on the end face of the holster and the meshing teeth on the end face of the spinning bushing 6 will drive the spinning bushing 6 to start rotating synchronously. However, due to the flat structure at the tail of the core rod 1, after being clamped by the flat groove of the gun head chuck, the core rod 1 will not rotate. Due to the matching and limiting effect of the cross boss on the lower end face of the core rod 1 and the cross groove on the end face of the drive body 2, the nail body 5 will not rotate either. Only the holster drives the spinning bushing 6 to rotate.

[0056] During the rotation of the spinning bushing 6 drive unit, the meshing teeth on the right side of the spinning bushing 6 drive unit and the meshing teeth on the locking ring 7 body of the locking ring 7 are engaged to synchronously drive the deformed locking ring 7 to rotate. At this time, the locking ring 7 is subjected to a combined load of thrust and torsional force applied to it by the spinning bushing 6, and the tail of the core rod 1 is still continuously subjected to the fixing tension applied by the rivet gun chuck.

[0057] Driven by the rotation of the spinning bushing 6, the locking ring 7 also begins to rotate slightly. When the locking ring 7 rotates, it will rotate along the spiral line on the conical inclined surface of the locking groove 14 of the core rod 1. Guided by the spiral line and under the thrust applied by the spinning bushing 6, the locking ring 7 will spirally squeeze forward into the deeper part of the wedge-shaped locking space along the spiral line until the locking ring 7 is completely spirally squeezed into the lowest part of the wedge-shaped space. At this time, the locking ring 7 can no longer move forward or rotate, but the rotational torque acting on the holster continues to increase. After the holster can no longer rotate, the torque in the reverse action also acts on the annular groove at the tail of the core rod 1 through the flat rod at the tail of the core rod 1. When the torque increases to a certain extent, the tail of the core rod 1 will be twisted off from the neck groove under the combined action of tension and torque. At this time, the entire riveting process is completed.

[0058] After the core rod 1 is broken off at the neck groove, the presence of the raised spiral line on the inclined surface of the locking groove 14 of the core rod 1 increases the friction on the conical surface of the locking groove 14. Due to the presence of the conical thread, the release and consumption of preload caused by elastic slippage, which was present in previous products, does not occur between the locking ring 7 and the core rod 1. Compared to previous blind rivet products, the innovative content of this patent can effectively improve the preload of such products by more than 0%.

[0059] 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.

[0060] 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 preload-enhanced type blind rivet bolt, characterized in that: It comprises a core rod, and a driving body, an expansion ring, a forming sleeve, a nail body, a locking ring and a spinning bushing sleeve which are sleeved on the core rod; The core rod is a slender rod structure, the end of the core rod is connected to the chuck of the rivet gun, the middle of the core rod is provided with a diameter-breaking groove, and the head end of the core rod is provided with a terminal; The driving body, the forming sleeve and the nail body are in an integral tubular structure, the forming sleeve forms a flexible deformation area, and a receiving cavity for accommodating the expansion ring is provided inside the forming sleeve, and the driving body is clamped with the head end of the core rod; The spun bushing is a rotating body structure with a stepped hole inside, and the locking ring is arranged in the stepped hole and meshedly connected with the end face of the stepped hole of the spun bushing. The outer ring of the spun bushing is provided with a shearing groove.

2. The preload-enhanced type blind rivet bolt according to claim 1, characterized in that: The end of the core rod is a flat structure and matches with the flat groove in the rivet gun chuck. The core rod is provided with a straight ring groove and is clamped and fixed by the rivet gun chuck. The inner wall of the end of the core rod is provided with a cross-shaped anti-rotation tooth, and the end surface of the driving body is provided with a cross-shaped anti-rotation groove matched with the cross-shaped anti-rotation tooth, so that the driving body and the core rod are correspondingly engaged.

3. The preload-enhanced type blind rivet bolt according to claim 2, characterized in that: A clamping ring groove is provided on one side of the middle part of the core rod close to the straight ring groove, which is used for interference fit with the inner hole of the spun bushing to clamp the spun bushing.

4. The preload-enhanced type blind rivet bolt according to claim 1, characterized in that: The forming sleeve is a hollow tubular structure with a revolving groove provided inside. The thickness of one end of the revolving groove close to the nail body is greater than the thickness of one end close to the driving body, so as to form an accommodating cavity.

5. The preload-enhanced type blind rivet bolt according to claim 4, characterized in that: The expansion ring is a circular rotating structure, the cross-sectional shape of which matches the shape of the rotating groove, and an inclined groove is provided in the middle of the circular ring.

6. The preload-enhanced type blind rivet bolt according to claim 1, characterized in that: The nail body is a hollow rotary structure with a step hole provided inside, and a locking hole connected to the step hole is provided inside the nail body, wherein the step hole cooperates with a blocking step provided in the middle of the core rod; A spiral locking groove with a conical structure is provided between the breaking groove and the blocking step. The locking groove cooperates with the locking hole to form a wedge-shaped space. The driving end of the spun bushing pushes the locking ring so that the locking ring is squeezed into the wedge-shaped space along the locking groove.

7. The preload-enhanced type blind rivet bolt according to claim 1, characterized in that: The end face of the spinning bushing close to the rivet gun head is a conical surface, the angle range of the conical surface is 150 degrees to 160 degrees, and a first meshing tooth is arranged on the conical surface, and the first meshing tooth meshes with the end face of the rivet gun head.

8. The preload-enhanced type blind rivet bolt according to claim 7, characterized in that: A second meshing tooth is disposed on the end surface of the step hole disposed in the spun bushing, and a third meshing tooth meshing with the second meshing tooth is disposed on one end surface of the lock ring.

9. The preload-enhanced type blind rivet bolt according to claim 8, characterized in that: The locking ring is a thin-walled annular structure, and the hardness of the metal matrix at one end of the third meshing tooth is greater than the hardness of the metal matrix at the other end of the locking ring.

10. The preload-enhanced type blind rivet bolt according to claim 9, characterized in that: The outer surface of the lock ring is also coated with a lubricating coating.

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