Nuclear fuel conduit expanded connection device

Abstract

The invention provides a nuclear fuel conduit expanded connection device which is characterized in that an outer conduit and an inner conduit are arranged among a plurality of expanded connection petals, and the inner side walls of the expanded connection petals are provided with protruding parts used for abutting against the outer conduit. The expanded connection rings are arranged on the outer sides of the expanded connection petals in a sleeving mode. The inner diameter of one end, close to the connecting pipe, of the expanded connection ring is larger, and the inner diameter of the other end is smaller. The thickness of the expanded connection petals close to the connecting pipe is small, and the thickness of the expanded connection petals far away from the connecting pipe is large. When the transmission assembly drives the expanded connection ring to move away from the connecting pipe along the outer sides of the expanded connection petals, the expanded connection ring abuts against the outer side walls of the expanded connection petals, so that the ends, away from the connecting pipe, of the expanded connection petals are close to one another, then the abutting force between the protruding parts and the outer catheter is increased, and the outer catheter and the inner catheter generate plastic deformation. Therefore, the outer catheter and the inner catheter are mutually expanded and fixed. The mode that pressure is applied from the outer side to generate plastic deformation is not prone to cracking of the inner guide pipe and the outer guide pipe, and the rate of finished products is higher after expanded connection.

Description

Technical Field

[0001] The invention generally relates to the technical field of nuclear fuel skeleton expansion connection, and in particular to a nuclear fuel conduit expansion connection device. Background Art

[0002] The existing nuclear fuel skeleton assembly includes a grid assembly, and the grid assembly has a plurality of square holes. In the actual working process, it is necessary to first select some of the square holes and install the conduits inside the square holes. The conduits include inner and outer conduits, and the inner and outer conduits can be expanded and fixed to each other first, and then welded to the grid assembly. It is also possible to weld the outer conduit to the grid assembly, and then set the inner conduit inside the outer conduit, and expand the parts of the two that extend out of the grid assembly.

[0003] The existing expansion process includes: Insert the inner catheter into the outer catheter; insert the thinner end of the mandrel with one end thicker than the other into the expansion flap; insert the mandrel and the expansion flap into the inner catheter; the mandrel continues to be inserted into the expansion flap, and the thicker end enters the expansion flap, driving the expansion flap to open and abut against the inner wall of the inner catheter, so that the inner catheter and the outer catheter undergo plastic deformation to form an expansion bag.

[0004] It can be seen that the existing expansion process is to expand from the inside of the tube, thereby generating plastic deformation, and the resulting expansion bag bulges outward from the tube. This expansion method is prone to cracks in the outer tube or the inner tube during the expansion process, resulting in damage, and the finished product rate after expansion is low. Summary of the invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a nuclear fuel conduit expansion device.

[0006] The present invention provides a nuclear fuel conduit expansion device, which is used for expanding an outer conduit and an inner conduit, and comprises: A connecting tube and a plurality of expansion flaps; the plurality of expansion flaps are connected to the same end of the connecting tube and are parallel to each other in a natural state; the inner side wall of the end of the expansion flap away from the connecting tube has a convex portion; the thickness of the expansion flap gradually decreases from the end away from the connecting tube to the end close to the connecting tube; the outer conduit is arranged in the connecting tube and the plurality of expansion flaps, and the inner conduit is arranged in the outer conduit; An expansion ring, the expansion ring is sleeved on the outer sides of the plurality of expansion petals; the inner diameter of the expansion ring gradually decreases from an end away from the connecting pipe to an end close to the connecting pipe; When the plurality of expansion petals are in a natural state, the inner diameter of the expansion ring close to one end of the connecting pipe is smaller than the distance between the ends of the two expansion petals away from the connecting pipe along the second direction; a transmission assembly, the transmission assembly being mounted on the connecting tube and connected to the expansion ring, and being used for driving the expansion ring to move along a first direction, so that the inner side wall of the expansion ring abuts against the outer side walls of the plurality of expansion petals, and so that the plurality of expansion petals are close to each other away from the end of the connecting tube; When the ends of the plurality of expansion flaps away from the connecting tube approach each other, the abutment force between the protrusion and the outer side wall of the outer conduit increases, so that the outer conduit and the inner conduit undergo plastic deformation and are fixed to each other.

[0007] The technical solution provided by the present invention also includes: An abutment shaft assembly is installed in the connecting tube and is used to abut against the inner wall of the inner conduit to support the inner conduit when the abutment force between the protrusion and the outer wall of the outer conduit increases.

[0008] According to the technical solution provided by the present invention, the abutment shaft assembly includes: A first abutment shaft and a second abutment shaft, wherein the first abutment shaft is located in the connecting tube, and one end of the first abutment shaft is fixedly connected to the connecting tube, and the other end of the first abutment shaft is detachably connected to one end of the second abutment shaft; The inner conduit is sleeved on the outside of the first abutment shaft and the second abutment shaft; A first groove is formed on the outer side wall of the connecting end of the first abutting shaft and the second abutting shaft; a second groove is formed on the outer side wall of the end of the second abutting shaft close to the first connecting shaft; When the first abutment shaft and the second abutment shaft are connected, the first groove and the second groove form a smooth groove structure; the groove structure and the protrusion are arranged in positions corresponding to each other and have matching shapes.

[0009] According to the technical solution provided by the present invention, the end of the second abutment shaft away from the first abutment shaft extends out of the outer catheter and the inner catheter.

[0010] According to the technical solution provided by the present invention, the transmission assembly includes: A first mounting plate, wherein the first mounting plate is fixedly connected to an outer side wall of the connecting pipe; A first driving device, wherein the first driving device is fixedly mounted on the first mounting plate, and a driving end is fixedly connected to the expansion ring; a moving direction of the driving end of the first driving device is parallel to the first direction, and is used to drive the expansion ring to move along the first direction.

[0011] According to the technical solution provided by the present invention, a slide rail is provided on the outer side wall of the connecting pipe; The transmission assembly comprises: A second mounting plate, wherein the second mounting plate is fixedly connected to an outer side wall of the connecting pipe; A first transmission tube, the first transmission tube is sleeved on the outside of the connecting tube, and one end of the first transmission tube is fixedly connected to the expansion ring; the outer wall of the first transmission tube has a first threaded portion, and the inner wall is provided with a sliding groove; the slide rail is arranged in the sliding groove, and is used to enable the first transmission tube to slide relative to the expansion ring along a first direction, drive the expansion ring to move along the first direction, and prevent the first transmission tube from rotating relative to the expansion ring; A second transmission tube, the second transmission tube is sleeved on the outside of the first transmission tube, and one end of the second transmission tube is rotatably connected to the second mounting plate; the inner side wall of the second transmission tube has a second threaded portion for engaging with the first threaded portion, and the outer side wall has an engaging portion; A driving assembly, the driving assembly is mounted on the second mounting plate and meshed with the meshing portion, and is used to drive the second transmission tube to rotate; When the second transmission tube rotates, the first threaded portion and the second threaded portion interact with each other, thereby driving the first transmission tube to move along a first direction.

[0012] According to the technical solution provided by the present invention, the driving component includes: a second driving device, the second driving device being fixedly mounted on the second mounting plate; A gear is fixedly connected to the driving shaft of the second driving device and is used to mesh with the meshing portion to drive the second transmission tube to rotate.

[0013] According to the technical solution provided by the present invention, the expansion ring comprises: A ring body, the ring body is sleeved on the outer sides of the plurality of expansion petals; A ball is rotatably mounted on the inner side wall of the ring body and is used to abut against the outer side wall of the expansion flap to generate relative rolling.

[0014] The beneficial effects of the present invention are: The outer tube and the inner tube are arranged between a plurality of expansion flaps, and the inner wall of the expansion flap has a protrusion for abutting against the outer tube. The expansion ring is sleeved on the outside of the plurality of expansion flaps. The inner diameter of the expansion ring close to one end of the connecting tube is larger, and the inner diameter of the other end is smaller. The thickness of the expansion flap is smaller near one end of the connecting tube, and larger at the end away from the connecting tube. When the transmission assembly drives the expansion ring to move along the outside of the plurality of expansion flaps away from the connecting tube, the expansion ring abuts against the outer wall of the expansion flap, so that the ends of the plurality of expansion flaps away from the connecting tube are close to each other, thereby increasing the abutment force between the protrusion and the outer tube, and both the outer tube and the inner tube undergo plastic deformation. Thereby, the outer tube and the inner tube are expanded and fixed to each other. This method of applying pressure from the outside to produce plastic deformation makes it difficult for the inner and outer tubes to produce cracks, and the yield rate after expansion is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is a structural schematic diagram of a nuclear fuel conduit expansion device under an embodiment; Figure 2 for Figure 1 A partial enlarged view of the middle A; Figure 3 It is a structural schematic diagram of a nuclear fuel conduit expansion device in another embodiment; Figure 4 is a schematic structural diagram of a first abutting shaft in another embodiment; Wherein: 1. outer conduit; 2. inner conduit; 3. expansion ring; 4. connecting tube; 5. expansion flap; 6. protrusion; 7. first abutment shaft; 8. second abutment shaft; 9. first groove; 10. second groove; 11. first mounting plate; 12. first driving device; 13. slide rail; 14. second mounting plate; 15. first transmission tube; 16. second transmission tube; 17. meshing part; 18. second driving device; 19. gear; 20. ring body; 21. ball; 22. conical part. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0017] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] Please refer to Figure 1The present invention provides a nuclear fuel conduit expansion device for expanding an outer conduit 1 and an inner conduit 2, comprising: A connecting tube 4 and a plurality of expansion flaps 5; the plurality of expansion flaps 5 are connected to the same end of the connecting tube 4 and are parallel to each other in a natural state; the inner side wall of the end of the expansion flap 5 away from the connecting tube 4 has a protrusion 6; the thickness of the expansion flap 5 gradually decreases from the end away from the connecting tube 4 to the end close to the connecting tube 4; the outer conduit 1 is arranged in the connecting tube 4 and the plurality of expansion flaps 5, and the inner conduit 2 is arranged in the outer conduit 1; An expansion ring 3, wherein the expansion ring 3 is sleeved on the outer sides of the plurality of expansion petals 5; the inner diameter of the expansion ring 3 gradually decreases from an end away from the connecting pipe 4 to an end close to the connecting pipe 4; When the plurality of expansion petals 5 are in a natural state, the inner diameter of the expansion ring 3 close to the end of the connecting pipe 4 is smaller than the distance between the ends of the two expansion petals 5 away from the connecting pipe 4 along the second direction; a transmission assembly, the transmission assembly being mounted on the connecting tube 4 and connected to the expansion ring 3, and being used for driving the expansion ring 3 to move along a first direction, so that the inner side wall of the expansion ring 3 abuts against the outer side walls of the plurality of expansion petals 5, and so that the ends of the plurality of expansion petals 5 away from the connecting tube 4 are brought closer to each other; When the ends of the plurality of expansion flaps 5 away from the connecting tube 4 approach each other, the abutment force between the protrusion 6 and the outer side wall of the outer conduit 1 increases, so that the outer conduit 1 and the inner conduit 2 undergo plastic deformation and are fixed to each other.

[0019] Specifically, a plurality of expansion flaps 5 are integrally provided with the connection pipe 4 and have deformation capability.

[0020] When the driving assembly drives the expansion ring 3 to move away from the connecting tube 4 along the first direction, the inner diameter of the expansion ring 3 and the expansion flap 5 at the abutment point gradually decreases, and the abutment force between the expansion ring 3 and the outer wall of the expansion flap 5 gradually increases, causing the outer catheter 1 and the inner catheter 2 to undergo plastic deformation and finally achieve mutual fixation.

[0021] The driving assembly drives the expansion ring 3 to move closer to the connecting pipe 4, and the multiple expansion petals 5 return to a natural state. This method of applying pressure from the outside to produce plastic deformation is not easy to cause cracks in the inner and outer conduits, and the yield rate after expansion is higher.

[0022] Furthermore, it also includes: An abutment shaft assembly is installed in the connecting tube 4 and is used to abut against the inner wall of the inner tube 2 to support the inner tube 2 when the abutment force between the protrusion 6 and the outer wall of the outer tube 1 increases.

[0023] Specifically, refer to Figure 2 , the abutment shaft assembly comprises: A first abutment shaft 7 and a second abutment shaft 8, wherein the first abutment shaft 7 is located in the connecting tube 4, and one end of the first abutment shaft 7 is fixedly connected to the connecting tube 4, and the other end of the first abutment shaft 7 is detachably connected to one end of the second abutment shaft 8; The inner conduit 2 is sleeved on the outside of the first abutment shaft 7 and the second abutment shaft 8; A first groove 9 is formed on the outer wall of the end portion where the first abutting shaft 7 and the second abutting shaft are connected; a second groove 10 is formed on the outer wall of the end portion of the second abutting shaft 8 close to the first connecting shaft; When the first abutting shaft 7 and the second abutting shaft 8 are connected, the first groove 9 and the second groove 10 form a smooth groove structure; the groove structure and the protrusion 6 are arranged in a position corresponding to each other and have the same shape.

[0024] In some embodiments, an abutment shaft assembly is also installed in the connecting tube 4 for abutting against the inner conduit 2. This approach can prevent the inner conduit 2 from deforming too much during the expansion process, causing the entire tube body to be squeezed into an irregular shape.

[0025] In some embodiments, the abutment shaft assembly includes a first abutment shaft 7 and a second abutment shaft 8, and before expansion, the second abutment shaft 8 is installed on the first abutment shaft 7. After expansion, the second abutment shaft 8 is removed from the first abutment shaft 7, and the outer catheter 1 and the inner catheter 2 fixed together are taken out from the expansion flap 5.

[0026] When the first abutment shaft 7 and the second abutment shaft 8 are connected to each other, the first groove 9 and the second groove 10 are connected to each other to form a smooth groove structure. The inner wall of the inner conduit 2 fits with the groove structure, and the groove structure supports the inner conduit 2, thereby shaping the inner conduit 2.

[0027] In some embodiments, the protrusions 6 are all arc-shaped with equal radius, and the first groove 9 and the second groove 10 have the same length. This shape can prevent the groove structure from getting stuck with the deformed inner conduit 2 after being disassembled into the first groove 9 and the second groove 10.

[0028] In some embodiments, reference Figure 4 One end of the first abutting shaft 7 has a larger radius and is used to connect with the connecting pipe 4; the other end has a smaller radius and is a free end; there is a tapered portion 22 between the two ends of the first abutting shaft 7 with different radii. When expansion joint is performed, the tapered portion 22 is used to abut against the inner wall of the inner conduit 2.

[0029] After the primary expansion joint is completed, the first abutment shaft 7 moves toward the end with a larger radius, and the end with a smaller radius can be taken out from the inner conduit 2 .

[0030] When multiple expansion joints are required, the first abutment shaft 7 can be fully inserted into the inner conduit 2. After one expansion joint, the first abutment shaft 7 is driven to move to the end with a larger radius, and then the expansion joint is performed again; multiple expansion joints can be performed in this way.

[0031] Furthermore, an end of the second abutting shaft 8 away from the first abutting shaft 7 extends out of the outer catheter 1 and the inner catheter 2 .

[0032] In some embodiments, the second abutment shaft 8 extends out of the inner catheter 2 , so that the second abutment shaft 8 can be easily controlled to be removed from the first abutment shaft 7 .

[0033] Furthermore, the transmission assembly comprises: A first mounting plate 11, wherein the first mounting plate 11 is fixedly connected to an outer side wall of the connecting pipe 4; The first driving device 12 is fixedly mounted on the first mounting plate 11, and a driving end is fixedly connected to the expansion ring 3; a moving direction of the driving end of the first driving device 12 is parallel to the first direction, and is used to drive the expansion ring 3 to move along the first direction.

[0034] Specifically, the first driving device 12 is a servo cylinder, and the extension direction of the driving end thereof is parallel to the first direction.

[0035] In this embodiment, three groups of driving devices 12 are provided, and three driving ends are respectively fixedly connected to three different positions of the expansion ring 3. This method can more stably support the expansion ring 3 and drive the expansion ring 3 to move along the first direction.

[0036] Further, refer to Figure 3 , a slide rail 13 is provided on the outer side wall of the connecting pipe 4; The transmission assembly comprises: A second mounting plate 14, wherein the second mounting plate 14 is fixedly connected to the outer side wall of the connecting pipe 4; A first transmission tube 15, which is sleeved on the outside of the connecting tube 4 and fixedly connected to the expansion ring 3 at one end; the outer wall of the first transmission tube 15 has a first threaded portion, and the inner wall is provided with a sliding groove; the slide rail is arranged in the sliding groove, and is used to enable the first transmission tube 15 to slide relative to the expansion ring 3 along a first direction, drive the expansion ring 3 to move along the first direction, and prevent the first transmission tube 15 from rotating relative to the expansion ring 3; A second transmission tube 16, which is sleeved on the outside of the first transmission tube 15 and one end of which is rotatably connected to the second mounting plate 14; the inner side wall of the second transmission tube 16 has a second threaded portion for engaging with the first threaded portion, and the outer side wall has an engaging portion 17; A driving assembly, the driving assembly is mounted on the second mounting plate 14 and meshed with the meshing portion 17, and is used to drive the second transmission tube 16 to rotate; When the second transmission tube 16 rotates, the first transmission tube 15 is driven to move along the first direction through the interaction between the first threaded portion and the second threaded portion.

[0037] In some embodiments, the sliding groove inside the first transmission tube 15 cooperates with the slide rail 13 on the connecting tube 4 to ensure that the first transmission tube 15 can only slide along the first direction relative to the connecting tube 5 and cannot rotate relative to it.

[0038] When the second transmission tube 16 rotates, it is threadedly engaged with the first transmission tube 15 , thereby driving the first transmission tube 15 to move along the first direction, and further driving the expansion ring 3 to move along the first direction.

[0039] Specifically, due to the cylinder drive method, a longer space is required along the first direction. However, this transmission method can make the nuclear fuel conduit expansion device in this embodiment adapt to a smaller space.

[0040] Furthermore, the driving assembly comprises: A second driving device 18, wherein the second driving device 18 is fixedly mounted on the second mounting plate 14; The gear 19 is fixedly connected to the driving shaft of the second driving device 18 and is used to mesh with the meshing portion 17 to drive the second transmission tube 16 to rotate.

[0041] Specifically, the driving device 18 is a motor. When the driving device 18 rotates forward, the gear 19 and the meshing portion 17 mesh, driving the second transmission tube 16 to rotate reversely, and driving the first transmission tube 15 and the expansion ring 3 to move forward along the first direction.

[0042] When the driving device 18 rotates in reverse, the gear 19 and the meshing portion 17 mesh, thereby driving the second transmission tube 16 to rotate forward, and driving the first transmission tube 15 and the expansion ring 3 to move in the opposite direction along the first direction.

[0043] Furthermore, the expansion ring 3 comprises: A ring body 20, wherein the ring body 20 is sleeved on the outer sides of the plurality of expansion petals 5; The ball 21 is rotatably mounted on the inner wall of the ring body 20 , and the ball 21 is used to abut against the outer wall of the expansion flap 5 to generate relative rolling.

[0044] In some embodiments, a ball groove is provided on the inner side wall of the ring body 20, and the ball 21 can be rotatably installed in the ball groove. The friction force can be reduced by the abutment between the ball 21 and the expansion petal 5, so as to facilitate the expansion.

[0045] At least three non-collinear balls 21 abut against the same expansion flap 5 . This method can prevent the expansion flap 5 from deforming perpendicular to the first direction during the expansion process, thereby preventing the outer tube 1 and the inner tube 2 from having irregular shapes.

[0046] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present invention is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present invention (but not limited to) to form a technical solution.

Claims

1. A nuclear fuel conduit expansion device, characterized in that: Used for expanding an outer conduit (1) and an inner conduit (2), comprising: A connecting tube (4) and a plurality of expansion flaps (5); the plurality of expansion flaps (5) are connected to the same end of the connecting tube (4) and are parallel to each other in a natural state; the inner side wall of the end of the expansion flap (5) away from the connecting tube (4) has a protrusion (6); the thickness of the expansion flap (5) gradually decreases from the end away from the connecting tube (4) to the end close to the connecting tube (4); the outer conduit (1) is arranged in the connecting tube (4) and the plurality of expansion flaps (5), and the inner conduit (2) is arranged in the outer conduit (1); An expansion ring (3), the expansion ring (3) being sleeved on the outer sides of the plurality of expansion petals (5); the inner diameter of the expansion ring (3) gradually decreases from an end away from the connecting tube (4) to an end close to the connecting tube (4); When the plurality of expansion flaps (5) are in a natural state, the inner diameter of the expansion ring (3) at one end close to the connection pipe (4) is smaller than the distance between the ends of the two expansion flaps (5) away from the connection pipe (4) along the second direction; a transmission assembly, the transmission assembly being mounted on the connecting tube (4) and connected to the expansion ring (3), and being used for driving the expansion ring (3) to move along a first direction, so that the inner side wall of the expansion ring (3) abuts against the outer side walls of the plurality of expansion petals (5), and so that the ends of the plurality of expansion petals (5) away from the connecting tube (4) are brought closer to each other; When the ends of the plurality of expansion flaps (5) away from the connecting tube (4) approach each other, the abutment force between the protrusion (6) and the outer side wall of the outer conduit (1) increases, causing the outer conduit (1) and the inner conduit (2) to undergo plastic deformation and be fixed to each other.

2. A nuclear fuel conduit expansion device according to claim 1, characterized in that: Also includes: An abutment shaft assembly is installed in the connecting tube (4) and is used to abut against the inner wall of the inner tube (2) to support the inner tube (2) when the abutment force between the protrusion (6) and the outer wall of the outer tube (1) increases.

3. A nuclear fuel conduit expansion device according to claim 2, characterized in that: The abutment shaft assembly comprises: a first abutment shaft (7) and a second abutment shaft (8), wherein the first abutment shaft (7) is located in the connecting tube (4), and one end of the first abutment shaft (7) is fixedly connected to the connecting tube (4), and the other end of the first abutment shaft (7) is detachably connected to one end of the second abutment shaft (8); The inner conduit (2) is sleeved on the outside of the first abutment shaft (7) and the second abutment shaft (8); A first groove (9) is provided on the outer wall of the end portion where the first abutting shaft (7) and the second abutting shaft (8) are connected; a second groove (10) is provided on the outer wall of the end portion of the second abutting shaft (8) close to the first connecting shaft (8); When the first abutment shaft (7) and the second abutment shaft (8) are connected, the first groove (9) and the second groove (10) form a smooth groove-shaped structure; the groove-shaped structure and the protrusion (6) are arranged in a position corresponding to each other and have matching shapes.

4. A nuclear fuel conduit expansion device according to claim 3, characterized in that: The end of the second abutment shaft (8) away from the first abutment shaft (7) extends out of the outer catheter (1) and the inner catheter (2).

5. A nuclear fuel conduit expansion device according to claim 1, characterized in that: The transmission assembly comprises: A first mounting plate (11), the first mounting plate (11) being fixedly connected to an outer side wall of the connecting pipe (4); A first driving device (12), wherein the first driving device (12) is fixedly mounted on the first mounting plate (11), and a driving end is fixedly connected to the expansion ring (3); a moving direction of the driving end of the first driving device (12) is parallel to the first direction, and is used to drive the expansion ring (3) to move along the first direction.

6. A nuclear fuel conduit expansion device according to claim 1, characterized in that: The outer side wall of the connecting pipe (4) is provided with a slide rail (13); The transmission assembly comprises: a second mounting plate (14), the second mounting plate (14) being fixedly connected to an outer side wall of the connecting pipe (4); a first transmission tube (15), the first transmission tube (15) being sleeved on the outside of the connecting tube (4), and having one end fixedly connected to the expansion ring (3); the outer wall of the first transmission tube (15) having a first threaded portion, and the inner wall having a sliding groove; the sliding rail being arranged in the sliding groove, and being used for enabling the first transmission tube (15) to slide relative to the expansion ring (3) in a first direction, driving the expansion ring (3) to move in the first direction, and preventing the first transmission tube (15) from rotating relative to the expansion ring (3); a second transmission tube (16), the second transmission tube (16) being sleeved on the outside of the first transmission tube (15), and one end of the second transmission tube being rotatably connected to the second mounting plate (14); the inner side wall of the second transmission tube (16) having a second threaded portion for engaging with the first threaded portion, and the outer side wall having an engaging portion (17); a driving assembly, the driving assembly being mounted on the second mounting plate (14) and meshing with the meshing portion (17) and being used to drive the second transmission tube (16) to rotate; When the second transmission tube (16) rotates, the first threaded portion and the second threaded portion interact with each other, thereby driving the first transmission tube (15) to move along a first direction.

7. A nuclear fuel conduit expansion device according to claim 6, characterized in that: The drive assembly comprises: a second driving device (18), the second driving device (18) being fixedly mounted on the second mounting plate (14); A gear (19) is fixedly connected to the drive shaft of the second drive device (18) and is used to mesh with the meshing portion (17) to drive the second transmission tube (16) to rotate.

8. A nuclear fuel conduit expansion device according to claim 1, characterized in that: The expansion ring (3) comprises: A ring body (20), the ring body (20) being sleeved on the outer sides of the plurality of expansion flaps (5); A ball (21) is rotatably mounted on the inner wall of the ring body (20), and the ball (21) is used to abut against the outer wall of the expansion flap (5) to generate relative rolling.

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