Fusion shrinkage sleeve rod end sealing device

Abstract

The invention belongs to the technical field of optical fiber manufacturing, and particularly relates to a fusion shrinkage sleeve rod end sealing device which is used for centering a fusion shrinkage sleeve rod composed of a glass core rod and a glass tube, the end sealing device comprises two end sealing assemblies located at the two ends of the fusion shrinkage sleeve rod respectively, and each end sealing assembly comprises a center supporting sleeve and an expansion protection sleeve; the center supporting sleeve comprises a sleeve body, and an elastic contraction part is arranged at one end of the sleeve body. The expansion sheath comprises a lantern ring body, and the lantern ring body is configured to be in clearance fit with the inner wall of the glass tube; the sleeve body is coaxially arranged in the lantern ring body and connected with the lantern ring body through threads in a matched mode, and an elastic expansion part is arranged at one end of the lantern ring body. Through threaded fit and an elastic structure, in the centering process, the displacement distance of the sleeve body relative to the lantern ring body in the axial direction is accurately controlled through the number of rotation turns of the sleeve body and the lantern ring body, and the centering effect is guaranteed.

Description

A shrinkable sleeve end sealing device Technical Field

[0001] This application belongs to the field of optical fiber manufacturing technology, and more specifically, relates to a fusion-shrinkable end-sealing device. Background Technology

[0002] The main component of optical fiber preforms is high-purity quartz glass. The HEC process is an important optical fiber preform processing technology. The HEC process can melt and shrink a small-diameter quartz glass rod and glass tube that have been assembled together into a new large-diameter quartz glass rod through high temperature. The small-diameter quartz glass rod and glass tube that have been assembled together are called SCR (SleeveCore Rod).

[0003] To ensure alignment between the glass rod and glass tube during the melting and shrinking process, an alignment retaining device is generally required to maintain their structure. In existing technologies, a retainer is typically installed at the end, hence the name end-sealing device. The existing end-sealing device generally uses two coaxially fitted tubular structures connected to the glass tube and glass rod respectively to achieve alignment. This structure can only be used for simple structural retention, but it cannot accurately judge whether the fit between the end-sealing device and the glass tube is appropriate. In actual use, situations often occur where the fit is too tight, making it difficult to remove, or too loose, leading to inaccurate alignment. Summary of the Invention

[0004] In response to the deficiencies or improvement needs of the prior art, this application provides a shrink tubing end-sealing device, which aims to solve the technical problem that the end-sealing device of the shrink tubing in the prior art cannot accurately judge whether the fit between the end-sealing device and the glass tube is appropriate, resulting in poor fit.

[0005] This application provides a shrinkable sleeve end-sealing device for centering a shrinkable sleeve composed of a glass core rod and a glass tube. The end-sealing device includes two end-sealing assemblies located at both ends of the shrinkable sleeve. Each end-sealing assembly includes a central support sleeve and an expansion sleeve. The central support sleeve includes a sleeve body for accommodating the end of the glass core rod, and one end of the sleeve body is provided with an elastic contraction portion. The expansion sleeve includes a collar body configured to have a clearance fit with the inner wall of the glass tube. The sleeve body is coaxially disposed inside the collar body and threadedly connected to the collar body. One end of the collar body is provided with an elastic expansion portion. When the elastic contraction portion approaches the collar body, it abuts against the elastic expansion portion, causing the elastic contraction portion to elastically contract inward and the elastic expansion portion to elastically expand outward.

[0006] As a further preferred embodiment, the elastic contraction portion includes a plurality of contraction petals evenly distributed circumferentially along the sleeve body, the inner wall of the contraction petals forming a cylindrical cavity, and a gap groove extending axially along the sleeve body is formed between adjacent contraction petals, and the outer wall of the contraction petals expands outward in a direction away from the sleeve body; the elastic expansion portion includes a plurality of tightening petals evenly distributed circumferentially along the collar body, and the cross-section of each tightening petal is a fan-shaped annular shape.

[0007] As a further preferred embodiment, the inner wall of the expansion valve has a guide cone surface formed at the end away from the collar body. The guide cone surface is used to fit against the outer wall of the contraction valve to receive force, and the end of the guide cone surface transitions to the end face of the expansion valve with an arc surface.

[0008] As a further preferred embodiment, the end-sealing assembly further includes an elastic sealing ring, which is fitted onto the outside of the elastic expansion portion and used for sealing contact with the inner wall of the glass tube.

[0009] As a further preferred embodiment, the expansion sleeve is provided with a plurality of airflow holes, which are evenly spaced along the axial direction of the collar body. The airflow holes are used to allow the gap between the outer surface of the glass core rod and the inner surface of the glass tube to flow with the outside.

[0010] As a further preferred embodiment, the end-sealing assembly further includes a support sleeve locking nut; the support sleeve locking nut is threaded to the outside of the sleeve body and located outside the expansion sleeve.

[0011] As a further preferred embodiment, the central support sleeve further includes a clamping member, which is coaxially connected to the end of the sleeve body away from the elastic contraction portion, and the clamping member is used to cooperate with the clamping drive member.

[0012] As a further preferred embodiment, the clamping element is hexagonal prism-shaped.

[0013] As a further preferred embodiment, the end-sealing assembly further includes a tightening bolt and a bolt locking nut. A locking hole is formed inside the clamping member. The locking hole is coaxially arranged with the sleeve body and communicates with the internal space of the sleeve body. The tightening bolt is adapted to engage with the locking hole threadedly and extend movably into the sleeve body. The bolt locking nut is threadedly connected to the tightening bolt and located outside the clamping member.

[0014] As a further preferred embodiment, the end-sealing assembly further includes a dust cap for covering both ends of the glass tube, with the central support sleeve and the expansion sleeve located inside the dust cap.

[0015] Overall, compared with the prior art, the above-conceptual technical solutions proposed in this application have the following main technical advantages: 1. The end-sealing device provided in this application, through threaded fit and elastic structure, enables precise control of the axial displacement distance of the sleeve body relative to the collar body by the number of rotations of the sleeve body and the collar body during the alignment process. This controls the degree of contact between the elastic contraction part and the elastic expansion part, achieving precise control of the fit between the elastic expansion part and the inner wall of the glass tube. It transforms the unjudgeable fit into an adjustable and observable one, solving the technical problem of the difficulty in accurately judging and controlling the fit.

[0016] 2. The elastic contraction section and the elastic expansion section are designed as multiple circumferentially evenly distributed petal-shaped structures. The inner wall of the contraction petal forms a cylindrical cavity to contain the core rod, and its outer wall expands outward. The expansion petal is fan-shaped and has an axial gap groove. This allows the contraction petal to clamp the glass core rod more evenly and gently, and the expansion petal to expand outward more smoothly to fit the inner wall of the glass tube. This enhances the adaptability to small dimensional deviations between the core rod and the glass tube.

[0017] 3. By setting a guide cone surface at the end of the inner wall of the expansion valve, which contacts the outer wall of the contraction valve, this curved surface structure can smoothly and continuously convert the axial thrust into radial expansion and contraction forces when the two collide during threaded adjustment. Compared with planar contact, curved surface contact plays a guiding and force transmission optimization role, making the adjustment process more linear and stable, and reducing jamming.

[0018] 4. By fitting an elastic sealing ring on the outside of the elastic expansion part, when the expansion valve expands, the sealing ring is pressed against the inner wall of the glass tube to form a circumferential seal, which effectively enhances the positioning stability of the end sealing assembly inside the glass tube and prevents the end sealing assembly from slipping inside the glass tube.

[0019] 5. The external design of the hexagonal clamping component allows for direct adjustment of the relative position of the central support sleeve and the tightening sleeve using a standard hexagonal wrench. The number of rotations of the external hexagonal prism makes it easier to determine the number of rotations of the sleeve body relative to the collar body. Attached Figure Description

[0020] Figure 1 is a cross-sectional schematic diagram of the end-sealing device of the molten shrink sleeve provided in the embodiment of this application, equipped with a dust cap; Figure 2 is a cross-sectional schematic diagram of the end-sealing device of the molten shrink sleeve provided in the embodiment of this application, with the dust cap removed; Figure 3 is an enlarged schematic diagram of the right end of Figure 2; Figure 4 is a structural schematic diagram of the end-sealing assembly of the molten shrink sleeve provided in the embodiment of this application after the dust cap is removed; Figure 5 is a cross-sectional schematic diagram of Figure 4; Figure 6 is a cross-sectional schematic diagram of the central support sleeve in the molten shrink sleeve provided in the embodiment of this application; Figure 7 is a three-dimensional structural schematic diagram of the expansion sleeve in the molten shrink sleeve provided in the embodiment of this application; Figure 8 is a cross-sectional schematic diagram of the expansion sleeve along the expansion flap position in the molten shrink sleeve provided in the embodiment of this application; Figure 9 is a cross-sectional schematic diagram of the expansion sleeve in the molten shrink sleeve provided in the embodiment of this application. A cross-sectional schematic diagram of the tight-fitting sleeve at intervals between adjacent expansion flaps; in all figures, the same reference numerals are used to denote the same elements or structures, including: 10, end-sealing assembly; 11, central support sleeve; 111, sleeve body; 112, contraction flap; 113, clamping element; 11a, gap groove; 111a, external thread; 113a, locking hole; 12, expansion sleeve; 121, collar body; 122, expansion flap; 123, limiting ring; 121a, internal thread; 122a, sealing groove; 1221, guide cone surface; 1222, arc surface; 12a, crack-resistant groove; 12b, airflow hole; b1, main airflow hole; b2, secondary airflow hole; 13, elastic sealing ring; 14, support sleeve locking nut; 15, tightening bolt; 16, bolt locking nut; 17, dust cap; 20, glass core rod; 30, glass tube. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] As shown in Figures 2 and 3, this application provides a shrinkable sleeve end sealing device for centering a shrinkable sleeve composed of a glass core rod 20 and a glass tube 30.

[0023] As shown in Figures 4 and 5, the end-sealing device includes two end-sealing assemblies 10 located at both ends of the shrink tubing, and the end-sealing assembly 10 includes a central support sleeve 11 and a tightening sleeve 12.

[0024] As shown in Figure 6, the central support sleeve 11 includes a sleeve body 111 for accommodating the end of the glass core rod 20. It can be understood that, in order to facilitate the insertion of the end of the glass core rod 20 into the sleeve body 111, the inner diameter of the sleeve body 111 will be slightly larger than the outer diameter of the glass core rod 20. Therefore, the glass core rod 20 is in a movable state inside the sleeve body 111. In order to fix the glass core rod 20, an elastic contraction part is provided at one end of the sleeve body 111, which contracts inward to clamp the glass core rod 20.

[0025] As shown in Figure 5, the expansion sleeve 12 includes a collar body 121, which is configured to have a clearance fit with the inner wall of the glass tube 30. Similar to the above, in order to facilitate the insertion of the collar body 121 into the glass tube 30, since the outer diameter of the collar body 121 is smaller than the inner diameter of the glass tube 30, the collar body 121 is unstable inside the glass tube 30. Therefore, to ensure that the collar body 121 is coaxial with the glass tube 30, one end of the collar body 121 is provided with an elastic expansion portion. When the elastic contraction portion approaches the collar body 121, it abuts against the elastic expansion portion, causing the elastic contraction portion to elastically contract inward and the elastic expansion portion to elastically expand outward. Through the elastic expansion of the elastic expansion portion, the collar body 121 is strictly located at the center position on the cross-section of the glass tube 30.

[0026] The sleeve body 111 is coaxially disposed inside the collar body 121 and threadedly connected to the collar body 121. As shown in Figures 6, 8, and 9, the sleeve body 111 has an external thread 111a with a defined pitch, and the collar body 121 has an internal thread 121a with a corresponding pitch. The pitch is determined by the precise value of the actual number of rotations. Those skilled in the art will understand that, for the same number of rotations, the smaller the pitch, the smaller the movement distance of the sleeve body 111 relative to the collar body 121, and the smaller the outward expansion distance of the elastic expansion part; conversely, the larger the pitch, the larger the movement distance of the sleeve body 111 relative to the collar body 121, and the larger the outward expansion distance of the elastic expansion part.

[0027] Through the threaded fit and elastic structure, during the alignment process, the axial displacement distance of the sleeve body 111 relative to the collar body 121 can be precisely controlled according to the number of rotations of the sleeve body 111 and the collar body 121. This controls the degree of contact between the elastic contraction part and the elastic expansion part, achieving precise control over the fit between the elastic expansion part and the inner wall of the glass tube 30. This transforms the fit from being unassessable to being adjustable and observable, solving the technical problem of the fit being difficult to accurately assess and control.

[0028] In a preferred embodiment of this application, the elastic contraction portion includes a plurality of contraction petals 112 evenly distributed circumferentially along the sleeve body 111. The inner wall of the contraction petal 112 forms a cylindrical cavity, and a gap groove 11a extending axially along the sleeve body 111 is formed between adjacent contraction petals 112. The outer wall of the contraction petal 112 expands outward in a direction away from the sleeve body 111.

[0029] As shown in Figure 7, the elastic expansion section includes multiple tightening flaps 122 that are evenly distributed circumferentially along the collar body 121, and the cross-section of each tightening flap 122 is a fan-shaped ring.

[0030] The elastic contraction section and the elastic expansion section are designed as multiple circumferentially evenly distributed petal-shaped structures. The inner wall of the contraction petal 112 forms a cylindrical cavity to contain the glass core rod 20, and its outer wall expands outward. The expansion petal 122 is fan-shaped and has an axial gap groove 11a. This allows the contraction petal 112 to clamp the glass core rod 20 more evenly and gently, and the expansion petal 122 to expand outward more smoothly to fit the inner wall of the glass tube 30. This enhances the adaptability to small dimensional deviations between the core rod and the glass tube 30.

[0031] More preferably, a guide cone surface 1221 is formed at the end of the inner wall of the expansion valve 122 away from the collar body 121. The guide cone surface 1221 is used to fit against the outer wall of the contraction valve 112 to receive force. The end of the guide cone surface 1221 and the end face of the expansion valve 122 transition with the arc surface 1222.

[0032] By providing a guide cone surface 1221 at the end of the inner wall of the expansion valve 122, which contacts the outer wall of the contraction valve 112, this curved surface structure can smoothly and continuously convert the axial thrust into radial expansion and contraction forces when the two come into contact during threaded adjustment. Compared with planar contact, curved surface contact plays a guiding and force transmission optimization role, making the adjustment process more linear and stable, reducing jamming. The design of the arc-shaped surface 1222 transition prevents the expansion valve 122 from scratching the outer wall of the contraction valve 112 when relative sliding occurs between the sleeve body 111 and the collar body 121, thus improving the service life of the end sealing device.

[0033] With the sleeve body 111 and the collar body 121 threadedly connected, rotating the sleeve body 111 causes the contraction flap 112 to move closer to the collar body 121. The outer wall of the contraction flap 112 and the guide cone surface 1221 abut against each other, and the guide cone surface 1221 compresses the contraction flap 112 inward, thereby clamping the glass core rod 20 located inside it. At the same time, the outer wall of the contraction flap 112 pushes the expansion flap 122 outward, and the outer wall of the expansion flap 122 approaches and contacts the inner wall of the glass tube 30, thereby achieving relative fixation of the glass core rod 20 and the glass tube 30 in a coaxial alignment.

[0034] To facilitate understanding of the technical solution of this application, a specific optional embodiment is described below: In one optional embodiment, the thread pitch between the collar body 121 and the central support sleeve 11 is 1.5 mm, and the taper of the contraction flap 112 is 1:10. When the outer wall of the contraction flap 112 contacts the guide cone surface 1221, for each rotation of the central support sleeve 11, the central support sleeve 11 will move 1.5 mm relative to the collar body 121. Without considering the contraction of the contraction flap 112, the central support sleeve 11 will expand the outer diameter of the expansion flap by 1.5 mm. 2 = 3mm. In this way, during the assembly process, the number of turns required to tighten the central support sleeve 11 is calculated based on the design dimensions of the collar body 121 and the glass tube 30 to fix the collar body 121 and the glass tube 30 relative to each other.

[0035] In order to ensure that the collar body 121 is not too loose when it is inserted into the glass tube 30, the end of the collar body 121 away from the expansion valve 122 extends outward to form a limiting ring 123, the outer diameter of the limiting ring 123 being larger than the inner diameter of the glass tube 30.

[0036] In addition, in order to prevent the glass tube 30 from cracking when the expansion valve 122 expands outward, an annular anti-crack groove 12a is provided on the outer side of the collar body 121.

[0037] In a preferred embodiment of this application, the end-sealing assembly 10 further includes an elastic sealing ring 13, which is fitted onto the outside of the elastic expansion portion and used for sealing contact with the inner wall of the glass tube 30.

[0038] Since the glass tube 30 and glass core rod 20 produced in the optical fiber manufacturing process are not standard processed parts, there are certain dimensional differences in the diameter of different glass tubes 30 and glass core rods 20. This application uses the elastic sealing ring 13 to generate deformation to compensate for the gap difference between the glass tube 30 and glass core rod 20, which allows for a large gap difference and has a wide range of applications.

[0039] More preferably, in this embodiment, sealing grooves 122a are provided at both ends of the expansion flap 122, and each sealing groove 122a is provided with an elastic sealing ring 13. The double sealing design makes the glass tube 30 fit more stably and tightly with the expansion sleeve 12, ensuring structural stability and further reducing the risk of slippage.

[0040] The expansion sleeve 12 is provided with a plurality of airflow holes 12b, which are evenly distributed along the axial direction of the collar body 121. The airflow holes 12b allow the gap between the outer surface of the glass core rod 20 and the inner surface of the glass tube 30 to flow to the outside.

[0041] In a preferred embodiment of this application, the airflow hole 12b extends axially through the expansion sleeve 12. The airflow holes 12b are divided into main airflow holes b1 and secondary airflow holes b2 according to their distribution. Each main airflow hole b1 is located at the center of the end face of each expansion flap 122, and each secondary airflow hole b2 is located between two adjacent expansion flaps 122. The design of the main airflow holes b1 and secondary airflow holes b2 ensures a stable airflow channel inside the shrinking sleeve during the HEC process, achieving internal and external pressure balance and preventing deformation or bubble formation in the glass tube 30 and / or glass core rod 20 due to internal air thermal expansion during the HEC process.

[0042] In this application, in order to prevent the center support sleeve 11 from being displaced relative to the expansion sleeve 12 during the HEC process and affecting the alignment effect, the end sealing assembly 10 also includes a support sleeve locking nut 14; the support sleeve locking nut 14 is threaded to the outside of the sleeve body 111 and located outside the expansion sleeve 12.

[0043] In order to ensure that the support sleeve locking nut 14 does not affect the airflow effect of the airflow hole 12b, the outer tangent circle of the support sleeve locking nut 14 is slightly smaller than the pitch circle diameter of the airflow hole 12b.

[0044] In order to facilitate the relative rotation between the sleeve body 111 and the collar body 121, in a preferred embodiment of this application, the central support sleeve 11 further includes a clamping member 113, which is coaxially connected to the end of the sleeve body 111 away from the elastic contraction part, and is used to cooperate with the clamping drive member; more preferably, the clamping member 113 is a hexagonal prism.

[0045] The external design of the hexagonal clamping part 113 allows for direct adjustment of the relative position of the central support sleeve 11 and the tightening sleeve 12 using a standard hexagonal wrench. The number of rotations of the external hexagonal clamping part 113 also makes it easier to determine the number of rotations of the sleeve body 111 relative to the collar body 121.

[0046] Preferably, the end sealing assembly 10 further includes a tightening bolt 15 and a bolt locking nut 16. The clamping member 113 has a locking hole 113a formed inside. The locking hole 113a is coaxially arranged with the sleeve body 111 and communicates with the internal space of the sleeve body 111. The tightening bolt 15 is adapted to be threadedly engaged with the locking hole 113a and extend movably into the sleeve body 111. The bolt locking nut 16 is threadedly connected to the tightening bolt 15 and is located outside the clamping member 113.

[0047] The tightening bolt 15 extends into the fixing cylinder through the threaded hole in the clamping member 113, and can axially tighten the end of the glass core rod 20 to achieve axial fixation of the core rod; the bolt locking nut 16 can prevent the tightening bolt 15 from loosening. This structure provides auxiliary positioning and clamping of the glass core rod 20 in the axial direction, and together with the radial expansion, it achieves complete constraint of the core rod in the three-dimensional direction, further improving the centering accuracy and overall rigidity.

[0048] When the end sealing assembly 10 also includes a dust cap 17, the dust cap 17 is used to cover both ends of the glass tube 30. The center support sleeve 11 and the expansion sleeve 12 are located inside the dust cap 17. If the SCR sleeve assembly needs to be stored temporarily, the dust caps 17 can be installed at both ends to prevent fine dust and other foreign objects from entering the glass tube 30.

[0049] During installation, first tighten the limiting ring 123 to ensure it fits tightly against the end face of the glass tube 30. Use a wrench to rotate the hexagonal clamping part 113, causing the central support sleeve 11 to move outward relative to the expansion sleeve 12. At this time, the contraction valve 112 will squeeze the expansion valve 122, causing it to expand outward. This, in turn, pushes the elastic sealing ring 13 to deform elastically and press against the inner wall of the glass tube 30. Simultaneously, the contraction valve 112 will also squeeze the glass core rod 20 inward, tightly clamping it and fixing its radial direction, preventing relative rotation. Then, insert the tightening bolts 15 from both ends to tighten the glass core rod 20, fixing its axial direction. Finally, tighten the bolts and locking nuts 16 and 14 of the support sleeve to completely secure the tightening bolts 15, the central support sleeve 11, and the expansion sleeve 12. At this point, the entire SCR and end-sealing device are fixed together as one unit, forming the SCR sleeve assembly. If the SCR rod assembly needs to be stored temporarily, dust caps 17 can be installed at both ends to prevent fine dust and other foreign objects from entering the glass tube 30. The end-sealing assemblies 10 are used in pairs. When performing the HEC process, the dust caps 17 will be removed and the SCR will be fixed to the HEC equipment by clamping. According to the characteristics of the HEC process equipment, the SCR is divided into the pump end (PS) and the gas end (GS). During operation, air will flow from GS to PS.

[0050] In summary, the shrink sleeve end sealing device provided in this application, through threaded fit and elastic structure, enables precise control of the axial displacement distance of the sleeve body 111 relative to the collar body 121 by the number of rotations of the sleeve body 111 and the collar body 121 during the alignment process, thus ensuring the alignment effect.

[0051] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0052] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0054] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0055] Those skilled in the art will readily understand that the above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A shrinkable sleeve end-sealing device for aligning a shrinkable sleeve composed of a glass core rod (20) and a glass tube (30), characterized in that, The end-sealing device includes two end-sealing assemblies (10) located at both ends of the shrinking sleeve. The end-sealing assembly (10) includes a central support sleeve (11) and an expansion sleeve (12). The central support sleeve (11) includes a sleeve body (111) for accommodating the end of the glass core rod (20). One end of the sleeve body (111) is provided with an elastic contraction portion. The expansion sleeve (12) includes a collar body (121). The collar body (121) is configured to have a clearance fit with the inner wall of the glass tube (30). The sleeve body (111) is coaxially disposed inside the collar body (121) and threadedly connected to the collar body (121). One end of the collar body (121) is provided with an elastic expansion portion. When the elastic contraction portion approaches the collar body (121), it abuts against the elastic expansion portion, causing the elastic contraction portion to elastically contract inward and the elastic expansion portion to elastically expand outward.

2. The end-sealing device for the shrink-fit sleeve according to claim 1, characterized in that, The elastic contraction section includes a plurality of contraction petals (112) evenly distributed circumferentially along the sleeve body (111). The inner wall of the contraction petals (112) forms a cylindrical cavity. A gap groove (11a) extending axially along the sleeve body (111) is formed between adjacent contraction petals (112). The outer wall of the contraction petals (112) expands outward in a direction away from the sleeve body (111). The elastic expansion section includes a plurality of tightening petals (122) evenly distributed circumferentially along the collar body (121). The cross-section of each tightening petal (122) is a fan-shaped ring.

3. The end-sealing device for the shrink-fit sleeve according to claim 2, characterized in that, The inner wall of the expansion valve (122) away from the collar body (121) has a guide cone surface (1221) formed at one end. The guide cone surface (1221) is used to fit against the outer wall of the contraction valve (112) to receive force. The end of the guide cone surface (1221) and the end face of the expansion valve (122) are transitioned by an arc surface (1222).

4. The end-sealing device for the shrink-fit sleeve according to claim 1, characterized in that, The end-sealing assembly (10) also includes an elastic sealing ring (13), which is fitted onto the outside of the elastic expansion portion and is used to make a sealing contact with the inner wall of the glass tube (30).

5. The end-sealing device for the shrink-fit sleeve according to claim 1, characterized in that, The expansion sleeve (12) is provided with a plurality of airflow holes (12b), which are evenly spaced along the circumference of the collar body (121). The airflow holes (12b) are used to allow the gap between the outer surface of the glass core rod (20) and the inner surface of the glass tube (30) to flow to the outside.

6. The end-sealing device for a shrink-fit sleeve according to claim 1, characterized in that, The end-sealing assembly (10) also includes a support sleeve locking nut (14); the support sleeve locking nut (14) is threaded to the outside of the sleeve body (111) and located outside the expansion sleeve (12).

7. The end-sealing device for a shrink-fit sleeve according to claim 1, characterized in that, The central support sleeve (11) also includes a clamping member (113), which is coaxially connected to the end of the sleeve body (111) away from the elastic contraction part. The clamping member (113) is used to cooperate with the clamping drive member.

8. The end-sealing device for a shrink-fit sleeve according to claim 7, characterized in that, The clamping component (113) is hexagonal prism.

9. The shrink-fit sleeve end-sealing device according to claim 7, characterized in that, The end-sealing assembly (10) further includes a tightening bolt (15) and a bolt locking nut (16). The clamping member (113) has a locking hole (113a) inside. The locking hole (113a) is coaxially arranged with the sleeve body (111) and communicates with the internal space of the sleeve body (111). The tightening bolt (15) is threadedly engaged with the locking hole (113a) and extends movably into the sleeve body (111). The bolt locking nut (16) is threadedly connected to the tightening bolt (15) and located outside the clamping member (113).

10. The shrink-fit end-sealing device according to any one of claims 1 to 9, characterized in that, The end-sealing assembly (10) also includes a dust cap (17) for covering both ends of the glass tube (30), and the central support sleeve (11) and the expansion sleeve (12) are located inside the dust cap (17).

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