A four - stage sealed blind rivet for use with a blind - ended stepped hole

Abstract

The present invention provides a four - stage sealed blind rivet for use with a blind - ended stepped hole, comprising a core rod, a tube body, a shape - memory alloy expansion body, a strip - shaped rubber sealing ring, a nail body, a locking ring, a pressing bushing, a closing gasket, a square rubber sealing ring, a secondary circular sealing ring and a primary circular sealing ring. The beneficial effects of the present invention are as follows: simple structure, convenient installation, reliable performance and high sealing performance; this blind rivet needs to be used in conjunction with a blind - ended stepped hole to achieve its most stable and reliable sealing performance.

Description

Technical Field

[0001] The present invention belongs to the field of fasteners, and particularly relates to a four - level sealed blind rivet for use with a blind - end stepped hole. Background Art

[0002] In the design process of high - end equipment such as aerospace and navigation, considering factors such as volume and weight, the structural design is generally relatively compact. The connection and installation spaces of these compact structural parts are relatively narrow. Ordinary bolt - nut fasteners cannot meet the installation requirements of these occasions because they require double - sided installation. Therefore, riveting is generally selected in these 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 are widely used in various aerospace vehicles.

[0003] Most of the currently used blind rivets can only be used in ordinary atmospheric environments. Because they do not have a sealing and anti - corrosion function or have a low sealing and anti - corrosion level, they cannot be used for the structural connection of storage spaces such as oil fluids. For example, at the connection of some fuel tank structural parts with a relatively narrow space, and basically they cannot meet the requirements for single - sided connection of the outer surface of a navigation or deep - sea submersible or an oil - fluid storage area. Aerospace Precision Industry Co., Ltd. has previously designed a sealed blind rivet, but its qualified rate of batch riveting can only reach about 80% at present. There is a possibility that the rubber sealing ring is displaced during large - batch riveting, resulting in sealing failure. When using this product, it is necessary to strictly detect the riveting state of the product. Unqualified riveted products need to be disassembled and reinstalled, which has the disadvantage of inconvenient use. Summary of the Invention

[0004] In view of this, the present invention aims to provide a four - level sealed blind rivet for use with a blind - end stepped hole, so as to provide a blind rivet with a simple structure, convenient installation, reliable performance and high sealing performance; this blind rivet needs to be used in cooperation with a blind - end stepped hole to achieve its most stable and reliable sealing performance.

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

[0006] A four - stage sealed blind rivet for use with a blind - end stepped hole, comprising a core rod, a tube body, a shape - memory alloy expansion body, a strip - shaped rubber sealing ring, a nail body, a locking ring, a pressing bushing, a closing gasket, a diamond - shaped rubber sealing ring, a secondary circular sealing ring, and a primary circular sealing ring. The outer wall of the core rod is sequentially sleeved with a pressing bushing, a locking ring, a nail body, a strip - shaped rubber sealing ring, a shape - memory alloy expansion body, a tube body, and a diamond - shaped rubber sealing ring from left to right. The locking ring is nested outside into the inside of the pressing bushing. The strip - shaped rubber sealing ring is nested outside into the inside of the nail body. The shape - memory alloy expansion body is nested outside into the inside of the tube body. One end of the outer wall of the tube body is sequentially sleeved with a primary circular sealing ring and a secondary circular sealing ring from left to right. The other end of the outer wall of the tube body is provided with a closing gasket, and the diamond - shaped rubber sealing ring is nested inside the closing gasket.

[0007] Further, the core rod is of a slender rod structure. One end of the outer wall of the core rod is provided with straight lines, which are used to increase the friction between the core rod and the rivet gun chuck. In the middle of the outer wall of the core rod, a neck - breaking groove, a locking groove, and a blocking step are respectively provided from left to right. The neck - breaking groove is used for the core rod to break at the neck - breaking groove after the tensile force borne by the core rod exceeds the strength of the core rod. The locking groove and the blocking step are both used in cooperation with the nail body. The other end of the outer wall of the core rod is provided with a closing and sealing groove, which is used for facilitating the closing of the tube body and for arranging the diamond - shaped rubber sealing ring and the closing gasket.

[0008] Further, the nail body is of a hollow structure. One end of the outer of the nail body is provided with a conical surface, and the other end of the outer of the nail body is provided with a nail head. The conical surface is used in cooperation with the shape - memory alloy expansion body and the tube body. Inside the nail body, a blocking platform, a second sealing groove, and a locking hole are sequentially provided from right to left. The blocking platform is used in cooperation with the blocking step of the core rod. The second sealing groove is used for sealing the internal structure of the rivet. The locking hole is used in cooperation with the locking groove on the core rod.

[0009] Further, the tube body is of a hollow structure with a stepped hole inside. The inner - wall aperture of the tube body near the closing and sealing groove is smaller than the inner - wall aperture of the tube body near the conical surface. And a bulging - forming guiding section is provided on the outer wall of the tube body near the conical surface, which is used for placing the secondary circular sealing ring and the primary circular sealing ring.

[0010] Further, the shape - memory alloy expansion body is a hollow thin - walled part, made of shape - memory alloy material. The shape - memory alloy expansion body is placed in the inner wall of the tube body near the conical surface, and the core rod is sleeved inside the shape - memory alloy expansion body.

[0011] Further, the long strip rubber sealing ring, the closing gasket, the diamond rubber sealing ring, the secondary circular sealing ring and the primary circular sealing ring are all of annular structure. The cross-section of the closing gasket and the diamond rubber sealing ring is of diamond structure, and the cross-sections of the secondary circular sealing ring, the primary circular sealing ring and the long strip rubber sealing ring are of circular structure.

[0012] Further, the locking ring is an annular metal hoop, the inside of the pressing bushing is of hollow structure, and a relief hole for accommodating the locking ring is formed in one side of the inner wall of the pressing bushing.

[0013] Compared with the prior art, the four-stage sealed blind rivet for use with a blind-end stepped hole of the present invention has the following advantages:

[0014] The four-stage sealed blind rivet for use with a blind-end stepped hole of the present invention is simple in structure, convenient to install, reliable in performance and has a high sealing performance; this blind rivet needs to be used in cooperation with a blind-end stepped hole to achieve its most stable and reliable sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0016] Figure 1 is a schematic diagram of the overall structure according to an embodiment of the present invention;

[0017] Figure 2 is a schematic diagram of the core rod according to an embodiment of the present invention;

[0018] Figure 3 is a schematic diagram of the nail body according to an embodiment of the present invention;

[0019] Figure 4 is a schematic diagram of the tube body and the shape memory alloy expansion body according to an embodiment of the present invention;

[0020] Figure 5 is a schematic diagram of the closing gasket, the diamond rubber sealing ring, the circular rubber sealing ring and the long strip rubber sealing ring according to an embodiment of the present invention;

[0021] Figure 6 is a schematic diagram of the locking ring and the pressing bushing according to an embodiment of the present invention;

[0022] Figure 7 is a schematic diagram of the blind-end two-stage stepped hole according to an embodiment of the present invention;

[0023] Figure 8 is a schematic diagram of the blind rivet inserted into the stepped hole according to an embodiment of the present invention;

[0024] Figure 9 Schematic diagram of step 1 (inserting the pipe body into the second-stage stepped hole) in the riveting process according to the embodiment of the present invention;

[0025] Figure 10 Schematic diagram of step 2 (forming a bulge on the stepped guide of the pipe body and pushing the No. 1 rubber ring into the first-stage stepped hole) in the riveting process according to the embodiment of the present invention;

[0026] Figure 11 Schematic diagram of step 3 (continuing to bulge the pipe body and compressing the No. 1 rubber ring in the second-stage stepped hole, and the stepped groove of the pipe body seal starts to compress the No. 2 rubber ring) in the riveting process according to the embodiment of the present invention;

[0027] Figure 12 Schematic diagram of the effect after installation according to the embodiment of the present invention;

[0028] Figure 13 Enlarged schematic diagram of the S-shaped two-stage rubber seal structure formed by the stepped pipe body and the two-stage stepped hole according to the embodiment of the present invention;

[0029] Figure 14 Enlarged schematic diagram of the internal stepped seal structure and the core rod pipe body seal structure according to the embodiment of the present invention;

[0030] Figure 15 Schematic diagram of the sealing failure caused by the riveting failure that is likely to occur in the old-fashioned sealed blind rivet according to the embodiment of the present invention.

[0031] Explanation of reference numerals:

[0032] 1. Core rod; 101. Straight thread; 102. Neck-breaking groove; 103. Locking groove; 104. Blocking step; 105. Closing and sealing groove; 2. Pipe body; 201. Bulge forming guide section; 3. Memory alloy expansion body; 4. Long strip rubber sealing ring; 5. Nail body; 501. Conical surface; 502. Blocking platform; 503. Second sealing groove; 504. Locking hole; 6. Locking ring; 7. Pushing and pressing bushing; 8. Closing gasket; 9. Diamond-shaped rubber sealing ring; 10. Second-stage circular sealing ring; 11. First-stage circular sealing ring. Detailed implementation manners

[0033] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0034] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 thus cannot be construed as a limitation on 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 specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0035] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0036] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0037] As Figures 1 to 15 shown, a four - stage sealed blind rivet for use with a blind - end stepped hole, the blind rivet comprising an eleven - part assembly including a mandrel 1, a tube body 2, a shape - memory alloy expansion body 3, a long - strip rubber sealing ring 4, a nail body 5, a locking ring 6, a pressing bushing 7, a closing gasket 8, a diamond - shaped rubber sealing ring 9, a secondary circular sealing ring 10, and a primary circular sealing ring 11.

[0038] As Figures 7 - 14 ( Figure 12In the figure, B refers to the rubber seal. The riveting process is as follows: First, use a blind-end stepped hole machining tool and a tool to drill a stepped riveting hole corresponding to the outer diameter of the blind rivet on the component to be riveted and the base body. Then, dip the first half of the assembled blind rivet in sealant, and then insert it into the stepped riveting hole of the component to be riveted, so that the nail cap on the nail body 5 abuts against the orifice of the riveting hole of the component to be riveted. Then, insert the end of the core rod 1 into the gun head of the riveting gun, and use the end face of the riveting gun head to press the pressing bushing 7 of the blind rivet against the component to be riveted. Subsequently, press the trigger of the riveting gun, and the riveting gun starts to work. The riveting gun clamps the core rod 1 of the blind rivet through the chuck inside the gun head. The chuck clamps the core rod 1 and retreats under the action of air pressure. During the retreat of the core rod 1, the support surface at the head of the core rod 1 squeezes the closing gasket 8 and squeezes the end of the tube body 2, so that the tube body 2 drives the shape memory alloy expansion body 3 to also retreat. During the retreat, the end of the tube body 2 and the shape memory alloy expansion body 3 close to the nail body 5, that is, the bulge forming guiding section 201 expands and deforms along the conical surface of the nail body 5. During the continuous retreat of the tube body 2, the bulge forming guiding section 201 will climb onto the conical surface 501 of the nail body 5. During this process, the secondary seal groove on the tube body 2 will drive the secondary circular seal ring 10 and the primary circular seal ring 11 on it to retreat together. The tube body 2 continues to retreat under the drive of the core rod 1. During the retreat, the bulge forming guiding section 201 will be inserted into the second-stage stepped hole of the stepped hole until the tube body 2 touches the plate surface in the stepped hole and contacts the mounting plate surface. Subsequently, under the clamping and guiding action of the second-stage stepped hole, the bulge forming guiding section 201 of the tube body 2 is ready to expand and bend outwards. Then, the bulge forming guiding section 201 of the tube body 2 starts to expand and deform outwards under the extrusion of the core rod 1 and the mounting plate surface, and gradually forms a blind-end foot on the mounting plate surface. During the process of the bulge forming guiding section 201 expanding and deforming outwards, the secondary seal groove on the tube body 2 plays a role of limiting and lifting the secondary circular seal ring 10 and the primary circular seal ring 11. It can prevent the secondary circular seal ring 10 and the primary circular seal ring 11 from slipping out of position to the head position of the core rod 1, ensuring that the secondary circular seal ring 10 and the primary circular seal ring 11 can only move on the bulge forming guiding section 201 of the tube body 2. During the continuous outward expansion and deformation of the bulge forming guiding section 201 of the tube body 2, the primary circular seal ring 11 will slide into the first-stage stepped hole in the stepped hole during the outward expansion of the bulge forming guiding section 201. During the continuous outward expansion of the bulge forming guiding section 201 of the tube body, the primary circular seal ring 11 will be gradually pressed tightly in the sealing space formed by the tube body 2 and the first-stage stepped hole until the tube body 2 contacts the edge of the first-stage stepped hole. At this time, since the volume of the primary circular seal ring 11 is slightly larger than the sealing space formed by the contact between the tube body 2 and the edge of the first-stage stepped hole, the primary circular seal ring 11 is tightly pressed in the primary seal groove.At this time, the bulging forming guiding section 201 of the pipe body 2 continues to bend and bulge under the compression of the core rod. At this time, the secondary circular sealing ring 10 is located between the pipe body sealing groove and the plate surface. During the deformation of the pipe body 2, the pipe body sealing groove gradually compresses the secondary circular sealing ring 10 until the other side of the pipe body sealing groove presses against the plate surface. At this time, the secondary circular sealing ring 10 is gradually pressed tightly in the two-stage sealing space formed by the pipe body sealing groove and the mounting plate surface. At this time, since the volume of the secondary circular sealing ring 10 is slightly larger than the sealing space formed by the contact between the pipe body sealing groove and the plate surface, the secondary circular sealing ring 10 is tightly pressed in the two-stage sealing groove, thus realizing the two-stage sealing of the blind end of the rivet.

[0039] In this process, the closing end of the pipe body 2, the closing gasket 8 and the head supporting surface of the core rod 1 are completely pressed and adhered together, and the diamond-shaped rubber sealing ring 9 is also completely compressed into the defined area, thus completing the self-sealing function of the fastener head and achieving the three-stage sealing effect. During the formation of the blind end foot, the plate surface is gradually pressed completely, and the two circular rubber sealing rings are compressed into the defined areas of the pipe body sealing groove, the stepped hole and the blind end plate surface, thus completing the sealing function of the fastener blind end. In this process, the shape memory alloy expansion body 3 starts to deform synchronously under the driving action of the pipe body step. When the blind end foot of the pipe body 2 is finally completely formed, the shape memory alloy expansion body 3 has also completely filled the inside of the foot, and under the action of its own elasticity and recovery deformation force, the blind end foot is completely pressed against the plate surface, thus completing the high-sealing function of the fastener and the connecting base body.

[0040] Specifically, due to the partitioning effect of the closing gasket 8, the pressure will not act entirely on the diamond-shaped rubber sealing ring 9. Most of the pressure is transmitted through the closing gasket 8 to the pipe body 2 and the core rod 1, and only a small part of the pressure is transmitted to the rubber sealing ring, just compressing the sealing ring within its elastic range. Thus, while ensuring that the mechanical properties of the product after riveting do not decline, the rubber sealing ring will not be damaged under the action of pressure, thereby ensuring the sealing grade and reliability of the product. During the continuous retraction of the core rod 1, the shape memory alloy expansion body 3 will fill the interior of the forming blind-end bottom foot through deformation. Eventually, a large bottom foot bulge will form at the blind end of the plate surface, firmly pressing the connected part. At this time, the secondary circular sealing ring 10 and the primary circular sealing ring 11 are completely compressed into the limited area formed by the pipe body sealing groove and the plate surface, thus completing the sealing function of the blind end of the rivet. Due to the partitioning effect of the sealing groove formed by the pipe body and the plate surface, the pressure will not act entirely directly on the secondary circular sealing ring 10 and the primary circular sealing ring 11. Most of the pressure is directly transmitted to the blind-end bottom foot and the connected part, and only a small part of the pressure is transmitted to the secondary circular sealing ring 10 and the primary circular sealing ring 11, just compressing the sealing ring within its own elastic range. Thus, while ensuring that the mechanical properties of the product after riveting do not decline, the secondary circular sealing ring 10 and the primary circular sealing ring 11 will not be damaged under the action of pressure, thereby ensuring a higher sealing grade and reliability of the product.

[0041] During the retraction of the core rod 1, the strip-shaped rubber sealing ring 4 on the core rod blocking step 104 also retracts together and will gradually retract into the internal sealing groove formed by the nail body 5 and the core rod blocking step 104 until the strip-shaped rubber sealing ring 4 contacts the end face of the internal sealing groove of the nail body 5. During the continuous retraction of the core rod 1, at this time, the strip-shaped sealing ring 4 begins to be gradually compressed. When the core rod 1 retracts to the final position, that is, when the blocking step of the core rod 1 coincides with the blocking platform 502 of the inner hole of the nail body 5, the core rod 1 cannot continue to retract. At this time, the strip-shaped sealing ring 4 is completely compressed, thus completing the sealing function inside the core rod 1 and the nail body 5 and achieving the four-stage sealing effect of the entire fastening connection system. At this time, the locking groove of the core rod 1 will form a wedge-shaped space with the locking hole of the nail body 5. When the riveting gun continues to pull, the push sleeve 7 will be cut off. The cut-off push sleeve 7 will push the lock ring 6 to move towards the wedge-shaped space and finally be squeezed and deformed and completely enter the wedge-shaped space. When the pulling force on the core rod 1 continues to increase and exceeds the force value that the core rod neck-breaking groove 102 can withstand, the core rod 1 will break from the neck-breaking groove 102, and the tail of the core rod and the push sleeve 7 and the riveting body will be separated, thus completing the riveting and locking process.

[0042] Such as Figure 2As shown in the figure, the core rod 1 is a slender rod structure, on which there are straight lines 101, neck-breaking grooves 102, locking grooves 103, blocking steps 104 and closing and sealing grooves 105. The purpose of the straight lines 101 is to increase the friction between the core rod 1 and the riveting gun chuck. When the riveting gun works, the riveting gun chuck clamps the straight line part of the core rod under the action of high-pressure gas and pulls the core rod 1 backward. The straight lines prevent the riveting gun chuck from slipping when clamping the core rod 1 for work; the function of the blocking step 104 is to cooperate with the blocking step inside the nail body 5 to limit the axial displacement of the core rod 1, so that the core rod 1 cannot be pulled continuously after being pulled to the corresponding position; the locking groove 103 is used in cooperation with the locking hole 504 of the nail body 5. After the core rod 1 is pulled to the position, a wedge-shaped space will be formed between the core rod 1 and the nail body 5. The lock ring 6 will be squeezed into the wedge-shaped space under the pushing action of the cut pushing bushing 7, so as to achieve the purpose of locking; the function of the neck-breaking groove 102 is to break at the neck-breaking groove 102 after the tensile force borne by the core rod 1 exceeds the strength of the core rod 1. After the axial displacement of the core rod 1 is restricted by the two blocking steps, the riveting gun chuck clamps the core rod 1 and cannot retreat backward. When the tensile force value exceeds the limit value that the neck-breaking groove 102 can bear, it will break; the closing and sealing groove 105 is for the convenience of closing the tube body 2, ensuring that the fastener after closing does not turn out the tube body 2 during the riveting process, and also for the convenience of setting the diamond rubber seal ring 9 and the closing gasket 8.

[0043] The nail body 5 is as Figure 3 shown. It is a hollow rotary part with a stepped hole inside. A conical surface 501 is provided at the head of the nail body 5. The conical surface 501 cooperates with the shape memory alloy expansion body 3 and the tube body 2, so that during riveting, the ring and the tube body 2 can be flared and deformed along the conical surface; a blocking platform 502, a second sealing groove 503 and a locking hole 504 are provided inside the nail body 5. The function of the blocking platform 502 is to cooperate with the blocking step 104 of the core rod 1. During the riveting process, after the core rod 1 is pulled to the position, its displacement will be restricted by the blocking platform 502. The function of the second sealing groove 503 is to seal the internal structure of the rivet. It is used in cooperation with the blocking step 104 of the core rod 1. After the core rod 1 is pulled to the position, the blocking step 104 of the core rod 1 abuts against the blocking platform 502 of the nail body 5. At this time, the strip-shaped sealing ring 4 on the blocking step 104 of the core rod 1 is compressed to play a sealing role.

[0044] The locking hole 504 is used in cooperation with the locking groove 103 on the core rod 1. After the core rod 1 is pulled to the position, a wedge-shaped space will be formed between the locking hole 504 of the nail body 5 and the locking groove 103 on the core rod 1, which is convenient for the lock ring 6 to be squeezed in to achieve the locking purpose.

[0045] The tube body 2 is as Figure 4 shown Figure 4In it, A represents the secondary sealing groove, which is a hollow tubular part with a stepped hole inside. The smaller-diameter end of the hole is fitted with the caulking seal groove 105 of the core rod 1, and caulking treatment is required after assembly. The larger-diameter end of the hole is fitted with the conical surface 501 of the nail body 5. A bulging forming guiding section 201 is provided on the outer surface of the larger-diameter end to place circular rubber seals (secondary circular seal 10 and primary circular seal 11), and to guide the expansion and deformation of the pipe body 2. The wall thickness of the bulging forming guiding section 201 is 2 / 3 smaller than the normal wall thickness of the pipe body 2. The diameter of the circular rubber seals (secondary circular seal 10 and primary circular seal 11) is 2 / 3 of the normal wall thickness of the pipe body 2. The bulging forming guiding section 201 and the normal pipe body section are connected by an arc transition. The wall thickness difference between the bulging forming guiding section 201 and the normal pipe body section can ensure that during the bulging deformation process of the pipe body 2, the circular rubber seals (secondary circular seal 10 and primary circular seal 11) on it will not slip out of position, thus ensuring the absolute reliability of the sealing effect. The bulging forming guiding section 201 is inserted into the second-stage hole of the blind-end stepped hole during the riveting process to guide the smooth generation of the bottom feet of the pipe body 2 after contacting the mounting plate surface, and to ensure that the end face of the pipe body will not turn outwards after contacting the mounting plate surface. During the riveting process, under the extrusion of the nail body 5 and the core rod 1, the larger-diameter end of the pipe body 2 will start to deform along the conical surface 501 of the nail body 5, and finally a bottom foot will be formed on the deformed end face, so as to achieve the purpose of pressing the connecting parts. In this process, the two-stage rubber seals of the blind-end bulge will also be completed. The shape memory alloy expansion body 3 is as Figure 4 shown, which is a hollow thin-walled part made of shape memory alloy material. It is made into this shape at room temperature. When deformed, it will return to its pre-deformed shape at room temperature or low temperature. The expansion body is placed in the inner hole of the larger-diameter end of the pipe body 2 and plays the role of filling the blind-end bottom feet during the riveting process. And after the riveting is completed, due to its own elasticity and deformation recovery force, it will provide a continuous and stable pressing force to the connected parts and the circular rubber seals through the blind-end bottom feet.

[0046] The caulking gasket 8, the diamond-shaped rubber seal 9, the circular seals (secondary circular seal 10 and primary circular seal 11) and the strip-shaped rubber seal 4 are as Figure 5As shown in the figure. All four are circular. The closing gasket 8 and the rhombic rubber sealing ring 9 have a rhombic cross-section, the circular sealing rings (the secondary circular sealing ring 10 and the primary circular sealing ring 11) have a circular cross-section, and the strip-shaped rubber sealing ring 4 has a circular cross-section. When assembling the components, first install the strip-shaped rubber sealing ring 4 at the blocking step 104 of the core rod 1 under certain temperature conditions, then install the rhombic rubber sealing ring 9 at the closing sealing groove 105 of the core rod 1 under certain temperature conditions, then install the closing gasket 8 on the core rod 1, place it outside the rhombic rubber sealing ring 9, and then install the remaining parts such as the pipe body 2, the shape memory alloy expansion body 3 and the nail body 5. Then, on the closing machine, close the pipe body 2 and the closing gasket 8 on the component. After closing, the first half of the pipe body 2 becomes conical and tightly wraps around the closing sealing groove 105 of the core rod 1. The outer diameter and inner diameter of the closing gasket 8 also decrease to a certain extent under the action of external force, so as to tightly press the rhombic rubber sealing ring 9 at the closing sealing groove 105 of the core rod 1. After closing, finally install the circular rubber sealing rings (the secondary circular sealing ring 10 and the primary circular sealing ring 11) on the bulge forming guiding section 201 on the surface of the pipe body 2 under certain temperature conditions.

[0047] The lock ring 6 and the push pressing bushing 7 are as Figure 6 shown. The lock ring 6 is a ring-shaped metal hoop; the push pressing bushing 7 is a rotary part with a stepped hole inside. The larger-diameter end of the hole is matched with the lock ring 6 and can accommodate the lock ring 6. During riveting, the push pressing bushing 7 will be subjected to the extrusion of the riveting gun head and the end face of the nail body 5. When the extrusion force exceeds a certain limit value, the push pressing bushing 7 will break at the stepped hole position, so that the lock ring 6 can be pushed into the wedge-shaped locking space.

[0048] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A four - stage sealed blind rivet for use with a blind - end stepped hole, characterized in that: It includes a core rod (1), a tube body (2), a shape memory alloy expansion body (3), a strip-shaped rubber sealing ring (4), a nail body (5), a locking ring (6), a pressing bushing (7), a closing gasket (8), a diamond-shaped rubber sealing ring (9), a secondary circular sealing ring (10) and a primary circular sealing ring (11). The outer wall of the core rod (1) is sleeved with the pressing bushing (7), the locking ring (6), the nail body (5), the strip-shaped rubber sealing ring (4), the shape memory alloy expansion body (3), the tube body (2) and the diamond-shaped rubber sealing ring (9) in sequence from left to right. The outside of the locking ring (6) is nested inside the pressing bushing (7). The outside of the strip-shaped rubber sealing ring (4) is nested inside the nail body (5). The outside of the shape memory alloy expansion body (3) is nested inside the tube body (2). One end of the outer wall of the tube body (2) is sleeved with the primary circular sealing ring (11) and the secondary circular sealing ring (10) in sequence from left to right. The other end of the outer wall of the tube body (2) is provided with a closing gasket (8), and the diamond-shaped rubber sealing ring (9) is nested inside the closing gasket (8). One end of the outside of the nail body (5) is provided with a conical surface (501). One end of the outer wall of the tube body (2) close to the conical surface (501) is provided with a bulging forming guiding section (201), and the bulging forming guiding section (201) is used for placing the secondary circular sealing ring (10) and the primary circular sealing ring (11). The bulging forming guiding section (201) will be inserted into the second-stage hole of the blind-end stepped hole. The primary circular sealing ring (11) will slide into the first-stage stepped hole in the stepped hole during the outward expansion of the bulging forming guiding section (201).

2. The four - stage sealed blind rivet for use with a blind - end stepped hole according to claim 1, wherein: The core rod (1) is of a slender rod structure. One end of the outer wall of the core rod (1) is provided with straight lines (101), and the straight lines (101) are used to increase the friction between the core rod (1) and the riveting gun chuck. The middle part of the outer wall of the core rod (1) is respectively provided with a neck-breaking groove (102), a locking groove (103) and a blocking step (104) from left to right. The neck-breaking groove (102) is used for the core rod (1) to break at the neck-breaking groove (102) after the tensile force borne by the core rod (1) exceeds the strength of the core rod (1). The locking groove (103) and the blocking step (104) are both used in cooperation with the nail body (5). The other end of the outer wall of the core rod (1) is provided with a closing and sealing groove (105), and the closing and sealing groove (105) is used for facilitating the closing of the tube body (2) and for facilitating the setting of the diamond-shaped rubber sealing ring (9) and the closing gasket (8).

3. The four - stage sealed blind rivet for use with a blind - end stepped hole according to claim 2, wherein: The nail body (5) is of a hollow structure. The other end of the outside of the nail body (5) is provided with a nail head. The conical surface (501) is used in cooperation with the shape memory alloy expansion body (3) and the tube body (2). Inside the nail body (5), there are a blocking platform (502), a second sealing groove (503) and a locking hole (504) in sequence from right to left. The blocking platform (502) is used in cooperation with the blocking step (104) of the core rod (1). The second sealing groove (503) is used for sealing the internal structure of the rivet. The locking hole (504) is used in cooperation with the locking groove (103) on the core rod (1).

4. A four - stage sealed blind rivet for use with a blind - end stepped hole, characterized in that: The tube body (2) is a hollow structure with a stepped hole inside. The inner diameter of the inner wall of the tube body (2) near the closing sealing groove (105) is smaller than the inner diameter of the inner wall of the tube body (2) near the conical surface (501).

5. A four - stage sealed blind rivet for use with a blind - end stepped hole, characterized in that: The shape memory alloy expansion body (3) is a hollow thin-walled part made of shape memory alloy material. The shape memory alloy expansion body (3) is placed in the inner wall of the tube body (2) near the conical surface (501), and a core rod (1) is sleeved inside the shape memory alloy expansion body (3).

6. The four - stage sealed blind rivet for use with a blind - end stepped hole according to claim 1, wherein: The strip-shaped rubber sealing ring (4), the closing gasket (8), the diamond-shaped rubber sealing ring (9), the secondary circular sealing ring (10) and the primary circular sealing ring (11) are all annular structures. The cross-section of the closing gasket (8) and the diamond-shaped rubber sealing ring (9) is diamond-shaped, and the cross-section of the secondary circular sealing ring (10), the primary circular sealing ring (11) and the strip-shaped rubber sealing ring (4) is circular.

7. A four - stage sealed blind rivet for use with a blind - end stepped hole, characterized in that: The lock ring (6) is a ring-shaped metal hoop. The inside of the push sleeve (7) is a hollow structure, and a relief hole for accommodating the lock ring (6) is provided on one side of the inner wall of the push sleeve (7).

Images