A tool and process for close fitting of an elongate tube to a core

Abstract

The application discloses a tool and a process for closely adhering an elongated pipe and a core, relates to the technical field of metal plastic processing and forming, and comprises a rotary clamping mechanism, a driving traction rotary clamping mechanism and an ultrasonic staggered distance rotary pressing adhering mechanism. The rotary clamping mechanism clamps one end of a pipe-core composite and drives the pipe-core composite to rotate around the axis of the pipe-core composite. The driving traction rotary clamping mechanism clamps the other end of the pipe-core composite and applies a controllable axial tensile displacement to the pipe-core composite during processing. The ultrasonic staggered distance rotary pressing adhering mechanism comprises a movable base, at least three rotary pressing units and a plurality of ultrasonic vibration units. The movable base can move axially along the pipe-core composite. Each rotary pressing unit is arranged on the movable base, is distributed circumferentially along the pipe-core composite and is axially staggered with each other, thereby forming a multi-stage rotary pressing channel with a gradient increase in radial pressing amount. The ultrasonic vibration units are correspondingly arranged on each rotary pressing unit and apply high-frequency micro-amplitude mechanical vibration to the pipe-core composite, so that the pipe and the core are uniformly, stably and highly accurately closely adhered.

Description

Technical Field

[0001] This invention relates to the field of metal plastic processing and forming technology, and in particular to a tooling and process for tightly fitting slender tubes with a core. Background Technology

[0002] In the nuclear industry and high-end equipment manufacturing, the tight bonding between ultra-long tubing and the inner core is a crucial manufacturing step. Taking nuclear fuel elements as an example, the fuel core is encapsulated within the cladding tube to form a fuel unit. As the basic heat-bearing, pressure-bearing, and protective component of the reactor, it has extremely high requirements for structural integrity, heat transfer efficiency, dimensional accuracy, and service reliability. Similar ultra-long tubing-core composite structures are also widely used in various special functional tubing materials such as bimetallic composite tubes and heat exchange tubes. These components are typically long, small in diameter, thin-walled, and have a high length-to-diameter ratio. Methods such as diameter reduction, cladding, or compaction are required to ensure a continuous, uniform, and stable tight bond between the tubing and the inner core along its entire length to meet requirements for heat conduction, support, and other functions.

[0003] For such operating conditions, the relevant processes must meet multiple requirements. On the one hand, the tubing must reliably cover the inner core with a relatively small diameter reduction (e.g., nuclear fuel core encapsulation typically involves a radial diameter reduction on the order of 0.1-0.3 mm), ensuring the quality of the bonding interface while avoiding damage to the core. On the other hand, the straightness, roundness, wall thickness uniformity, and external surface quality of the ultra-long components must be considered to ensure subsequent assembly and service performance. Furthermore, due to the slender nature of the components, the forming process must also consider processing stability, efficiency, and consistency to avoid bonding failures caused by localized deformation, springback, or uneven stress.

[0004] However, there are many technical challenges in the diameter reduction and bonding process of ultra-long and slender tubes. First, the tube itself has low rigidity, and during horizontal or long-distance processing, it is prone to deflection and vibration due to its own weight and external loads, affecting the stress and coaxiality of the forming zone. Second, the local plastic deformation of thin-walled tubes is sensitive to surface condition, and surface quality problems such as indentations and scratches are prone to occur. Third, when ultra-long tubes are spun and compressed under local loading, the material tends to flow and accumulate axially in front of the forming zone. When radial deformation is restricted by the inner core, it is easy to induce surface wrinkling and other problems, affecting dimensional accuracy and bonding uniformity. In addition, there are also problems such as difficulty in controlling springback, difficulty in maintaining coaxiality over long distances, limited processing cycle time, and narrow matching window of process parameters, which constitute high-precision, long-dimensional, thin-walled composite forming challenges.

[0005] Currently, the main engineering processes for tightly fitting ultra-long tubes to the core include interference fit or heat shrink fit, cold drawing reduction, rolling or roll forming reduction, rotary forging reduction, and rotary forming reduction. Interference fit or heat shrink fit is simple, but its fit consistency and control precision are limited; cold drawing reduction is a mature and efficient process, but its adaptability to thin-walled, slender tubes and fragile cores is limited; rolling, roll forming, and rotary forging processes have strong local compaction capabilities, but they require high support and load distribution for ultra-long and slender tubes; rotary forming involves local continuous loading and is suitable for thin-walled precision forming, but in cases of long dimensions, thin walls, and small reduction amounts, deflection control and other requirements still need to be considered.

[0006] Therefore, there is an urgent need to develop a special tooling and process suitable for the tight bonding of ultra-long and slender tubes with cores, in order to solve the key technical problems existing in the current technology, such as difficulty in deflection control, easy deterioration of surface quality, wrinkling caused by axial flow accumulation, insufficient springback control accuracy, and difficulty in maintaining coaxiality over long distances, so as to achieve high-precision, high-efficiency, and high-quality continuous forming manufacturing. Summary of the Invention

[0007] The purpose of this invention is to provide a tooling and process for tightly fitting slender tubes and cores, so as to solve the problems existing in the prior art and effectively ensure uniform, stable and high-precision tight fitting of slender tubes and cores throughout the entire length range.

[0008] To achieve the above objectives, the present invention provides the following solution: This invention provides a tooling for tightly fitting a slender tube to a core, comprising: a first fixed base, a second fixed base, a rotary clamping mechanism, an active traction rotary clamping mechanism, and an ultrasonic staggered spinning bonding mechanism. The first fixed base and the second fixed base are disposed opposite to each other on a worktable, and a processing space for the tube-core composite is formed between the first fixed base and the second fixed base. The rotary clamping mechanism is mounted on the first fixed base and is used to clamp one end of the tube-core composite and drive the tube-core composite to rotate around its own axis. The active traction rotary clamping mechanism is mounted on the second fixed base and is used to clamp the other end of the tube-core composite. The active traction rotary clamping mechanism has a degree of freedom of movement along the axial direction of the tube-core composite, and is used to control the tube-core composite during processing. The core-tube composite is subjected to a controllable axial tensile displacement; the ultrasonic staggered spinning bonding mechanism includes a movable base, at least three spinning units and multiple ultrasonic vibration units. The movable base is movably disposed between the first fixed base and the second fixed base along the axial direction of the core-tube composite. Each spinning unit is mounted on the movable base, and each spinning unit is distributed circumferentially along the core-tube composite and staggered relative to each other along the axial direction of the core-tube composite. The spinning units form a multi-stage spinning channel with an increasing radial reduction gradient in the working sequence. The ultrasonic vibration units are correspondingly disposed on each spinning unit and are used to apply high-frequency micro-amplitude mechanical vibration to the core-tube composite to reduce interfacial frictional resistance and promote plastic flow of the material.

[0009] Preferably, it further includes at least one follower support mechanism, which is disposed in the processing space of the core composite and located below the core composite. The follower support mechanism has a degree of freedom of movement along the axial direction of the core composite and a degree of freedom of lifting perpendicular to the axial direction of the core composite, and is used to dynamically support the core composite near the theoretical maximum deflection position during the processing of the core composite.

[0010] Preferably, the follow-up support mechanism includes a support wheel slide, a lifting drive unit, a support wheel frame, and a follow-up support wheel. The support wheel slide is movably mounted on the worktable along the axial direction of the core composite. The fixed end of the lifting drive unit is mounted on the support wheel slide, and the movable end of the lifting drive unit extends and retracts in a direction perpendicular to the axial direction of the core composite. The support wheel frame is fixedly connected to the movable end of the lifting drive unit. The follow-up support wheel is rotatably mounted on the support wheel frame via a bearing. The wheel surface of the follow-up support wheel is concave arc-shaped and has an elastic wear-resistant coating layer.

[0011] Preferably, there are multiple follower support mechanisms, and the distance between two adjacent follower support mechanisms along the axial direction of the core composite is no more than 500mm. Each follower support mechanism is linked with the ultrasonic staggered spinning bonding mechanism. During the axial feeding process of the ultrasonic staggered spinning bonding mechanism, the follower support mechanism located behind the ultrasonic staggered spinning bonding mechanism descends in sequence and moves to the front of the ultrasonic staggered spinning bonding mechanism before rising again, so as to always maintain the support in the middle position between two adjacent support points.

[0012] Preferably, the number of spinning units is three. The three spinning units are distributed at equal angles of 120° along the circumference of the core composite and are spaced 8mm to 15mm apart along the axial direction of the core composite. The three spinning units are arranged in a two-below-one-above structure, with two spinning units located on the lower two sides of the core composite and one spinning unit located directly above the core composite.

[0013] Preferably, the movable base is arch-shaped, and the inner arch space of the movable base is used to provide clearance space for the lifting and lowering action of the follow-up support mechanism. The movable base is provided with a plurality of sliding grooves extending along the axial direction of the tube core composite. Each spinning unit includes a spinning wheel axial displacement base, a radial feed unit and a spinning wheel. The spinning wheel axial displacement base is slidably connected to the corresponding sliding groove. The radial feed unit is mounted on the spinning wheel axial displacement base and extends radially along the tube core composite. The spinning wheel is rotatably mounted on the radial feed unit through a bearing.

[0014] Preferably, the rotary clamping mechanism includes a first rotary drive unit, a first clamping disk, and a solid end plug. The first rotary drive unit is embedded in the first fixed base. The first clamping disk is drively connected to the output end of the first rotary drive unit. The solid end plug is used to be embedded in the tube of the tube-core composite and abuts against the core end of the tube-core composite. The first clamping disk includes a plurality of first radial clamping claws. Each first radial clamping claw is evenly distributed along the circumference of the first clamping disk and can synchronously retract radially to clamp the outer wall of the tube, so that each first radial clamping claw, the tube, and the solid end plug are tightly fitted. The active traction rotary clamping mechanism includes a second rotary drive unit, a second clamping disk, a hollow end plug, a tail-end hydraulic rod, a traction slide, and an active traction drive unit. The second rotary drive unit is embedded in the traction slide, and the traction slide is slidably mounted on the base along the axial direction of the tube-core composite. The second fixed base is described above. The fixed end of the active traction drive unit is installed on the second fixed base. The movable end of the active traction drive unit is driven to the traction slide to drive the traction slide to move axially. The second clamping disk is driven to the output end of the second rotary drive unit. The hollow end plug is used to be embedded in the tube of the tube-core composite. One end of the tail hydraulic rod passes through the hollow end plug axially and abuts against the core end of the tube-core composite. The other end passes through the traction slide and is fixedly connected to the second fixed base. The second clamping disk includes a plurality of second radial clamping claws. Each second radial clamping claw is evenly distributed around the second clamping disk and can synchronously retract radially to clamp the outer wall of the tube, so that each second radial clamping claw, the tube and the hollow end plug are tightly fitted. The tail hydraulic rod has a relative axial displacement degree of freedom to compensate for the difference in axial deformation between the core and the tube.

[0015] The present invention also provides a process for tightly bonding a slender tube to a core, employing the tooling described above for tightly bonding the slender tube to the core, and including the following steps: S1: Assembly and clamping: The core is inserted into the slender tube to form a tube-core composite. A solid end plug is pressed into one end of the slender tube, and a hollow end plug is pressed into the other end of the slender tube. The solid end plug is clamped in the rotary clamping mechanism, so that each of the first radial clamping claws retracts radially to clamp the outer wall of the tube. The hollow end plug is clamped in the active traction rotary clamping mechanism. The tail hydraulic rod is controlled to extend, so that it passes through the hollow end plug and presses against the end of the core. Each of the second radial clamping claws retracts radially to clamp the outer wall of the tube. S2: Pre-support and alignment: Activate the follow-up support mechanism, control the lifting drive unit to raise the follow-up support wheel to support the core composite, adjust the lifting height of each follow-up support mechanism to control the radial runout of the entire length of the core composite within the set range. S3: Parameter settings: Set the rotation speed of the rotary clamping mechanism and the active traction rotary clamping mechanism, the axial feed speed of the ultrasonic staggered spinning bonding mechanism, the radial pressing amount of each spinning unit, the vibration frequency and amplitude of each ultrasonic vibration unit, and the axial traction speed of the active traction drive unit. S4: Spinning and bonding: Drive the tube-core composite to rotate to a set speed, turn on each of the ultrasonic vibration units to make them resonant working state, control each of the spinning units to feed radially to the predetermined working position in a set sequence, and then drive the ultrasonic staggered spinning and bonding mechanism to feed uniformly along the axial direction of the tube-core composite. At the same time, control the active traction drive unit to drive the traction slide to move backward synchronously at a set axial traction speed, so that the slender tube will radially reduce its diameter and fit tightly with the core. S5: Dynamic following: During the axial feeding process of the ultrasonic staggered spinning bonding mechanism, the axial position of the ultrasonic staggered spinning bonding mechanism is detected in real time, and the axial position and lifting height of each follower support mechanism are adjusted according to the detection results, so that the follower support mechanism located behind the ultrasonic staggered spinning bonding mechanism descends in sequence, moves to the front of the mechanism and then rises again, so as to always keep the follower support wheel supported near the theoretical maximum deflection position of the tube core composite. S6: Finishing and Unloading: When the ultrasonic staggered spinning bonding mechanism is fed to a predetermined distance from the tail end of the core composite, the axial feed speed is reduced. After the tail end diameter reduction is completed, each spinning unit is controlled to withdraw radially in sequence, each ultrasonic vibration unit and rotary drive is turned off, each follower support mechanism is controlled to descend to the lowest position, the tail top hydraulic rod is controlled to retract, the clamping of each radial clamping claw is released, and the processed core composite is taken out.

[0016] Preferably, in S4, the radial feed sequence of the three spinning units is as follows: the first spinning unit located obliquely below the core composite cuts in first, the second spinning unit located directly above the core composite then presses in, and the third spinning unit located obliquely below the other side of the core composite presses in last for finishing. In step S4, the axial traction speed of the active traction drive unit Calculated using the following formula: Where 'a' represents the axial feed speed of the ultrasonic staggered spinning bonding mechanism. , , These represent the pre-deformation radius of the tube after being pressed into the first, second, and third spinning units, respectively. These are the outer radius and core radius of the slender tube after being pressed into place by the first spinning unit, respectively. These are the outer radius and core radius of the slender tube after being pressed in by the second spinning unit, respectively. These are the outer radius and core radius of the slender tube after it is pressed in by the third spinning unit, respectively.

[0017] Preferably, in step S2, the radial runout of the entire length of the core composite is controlled within 0.05 mm, and the axial preload of the tail hydraulic rod on the end of the core is controlled between 200 N and 300 N. In step S6, the predetermined distance is 20mm to 50mm, the axial feed speed is reduced by 10% to 30%, and the feed is stopped after rotating 1 to 3 revolutions at the tail end of the core composite.

[0018] The present invention achieves the following technical effects compared to the prior art: This invention provides a tooling and process for tightly fitting slender tubes to a core. By employing a coordinated configuration of a first fixed base, a second fixed base, a rotary clamping mechanism, an active traction rotary clamping mechanism, an ultrasonic staggered spinning bonding mechanism, and a follower support mechanism, stable support and continuous spinning forming of ultra-long, slender core composites across their entire length are achieved. Specifically, the three spinning units are distributed at equal angles of 120° circumferentially and staggered axially. Combined with a multi-stage spinning channel design with progressively increasing radial reduction, this allows the tube to undergo gradual diameter reduction deformation, effectively avoiding surface wrinkling and uncontrolled springback caused by large single deformations. The introduction of the ultrasonic vibration unit significantly reduces the frictional resistance between the spinning wheel and the tube surface, promoting plastic flow of the interface material and improving bonding density and surface quality. The active traction rotary clamping mechanism applies controllable axial tensile displacement during spinning, compensating for axial flow accumulation of material and suppressing buckling tendency. Simultaneously, the floating support design of the tail hydraulic rod adaptively compensates for the axial deformation differences between the core and the tube, ensuring precise maintenance of coaxiality over long distances.

[0019] Furthermore, the follow-up support mechanism adopts a strategy of linkage control with the ultrasonic staggered spinning and bonding mechanism. Through real-time position detection and dynamic following algorithms, the support wheel is always located at the theoretical maximum deflection position behind the spinning and bonding area, forming a dynamic balance mode of "processing first, support closely following". This fundamentally solves the problem of deflection accumulation during cantilever processing of ultra-long workpieces. The arch-shaped movable base provides ample space for the lifting and lowering of the follow-up support wheel, avoiding motion interference between mechanisms and ensuring the continuity and reliability of the processing.

[0020] The process method of this invention establishes a process parameter window suitable for the combination of slender tubes and cores of different specifications through refined control methods such as stepped entry timing control, precise matching of axial traction speed and spinning feed speed, and tail-end deceleration and pressure holding. It realizes full-process automated control from clamping and positioning, pre-support centering, multi-stage spinning and bonding to dynamic follow-up support, which significantly improves the forming accuracy, production efficiency and quality consistency of ultra-long thin-walled composite tubes. It has important application value in high-end manufacturing fields such as aerospace precision conduits, nuclear fuel cladding tubes, and medical device conduits. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the tooling provided by the present invention for tightly fitting a slender tube to a core. Figure 2 This is a front view of the tooling provided by the present invention for tightly fitting a slender tube to a core. Figure 3 This is a front sectional view of the tooling provided by the present invention for tightly fitting a slender tube to a core. Figure 4 This is a schematic diagram of the ultrasonic staggered spinning bonding mechanism in the tooling provided by the present invention for tightly bonding slender tubes and cores. Figure 5 for Figure 4 Sectional view at point AA; Figure 6 A schematic diagram of the follower support mechanism in the tooling for tight fitting of slender tubes and cores provided by the present invention; Figure 7 A schematic diagram of the structure of the tooling for tightly fitting a slender tube and a core, provided by the present invention, after the solid end plug and the hollow end plug are installed at both ends of the tube-core composite. Figure 8 This is a schematic diagram of the radial successive feed depth of the staggered rotary wheel in Example 2; Figure 9 This is a schematic diagram of the axial spacing of the staggered rotating wheels in Example 2; Figure 10 The following is a simplified and shortened three-dimensional view of the core-tube composite in Example 2, where (a) is a side sectional view, (b) is a front sectional view, and (c) is a structural schematic diagram. Figure 11This is a schematic diagram of the mesh generation of the cladding tube blank in the three-dimensional finite element model of the core in Example 2, where (a) is a side sectional view and (b) is a front view; Figure 12 This is the equivalent plastic strain cloud diagram of the axial section from the start of feeding to the end of feeding in Example 2, which fits tightly without gaps; Figure 13 This is a diagram illustrating the effect of diameter reduction forming in Example 2; Figure 14 This is a schematic diagram of the failed tapering and forming process in Example 2; In the figure: 1. First fixed base; 2. Second fixed base; 3. Rotary clamping mechanism; 31. First rotary drive unit; 32. First clamping plate; 33. Solid end plug; 4. Active traction rotary clamping mechanism; 41. Second rotary drive unit; 42. Second clamping plate; 43. Hollow end plug; 44. Tail top hydraulic rod; 45. Traction slide; 46. Active traction drive unit; 5. Ultrasonic staggered spinning and bonding mechanism; 51. Movable base; 52. Spinning unit; 521. Rotary wheel axial displacement base; 522. Radial feed unit; 523. Rotary wheel; 524. Second threaded rod; 53. Ultrasonic vibration unit; 6. Follower support mechanism; 61. Support wheel slide; 62. Lifting drive unit; 63. Support wheel frame; 64. Follower support wheel; 7. Tube-core composite; 71. Tube; 72. Core. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The purpose of this invention is to provide a tooling and process for tightly fitting slender tubes and cores, so as to solve the problems existing in the prior art and effectively ensure uniform, stable and high-precision tight fitting of slender tubes and cores throughout the entire length range.

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1 This embodiment provides a tooling for tightly fitting a slender tube 71 to a core 72, such as... Figures 1-9As shown, the assembly includes: a first fixed base 1, a second fixed base 2, a rotary clamping mechanism 3, an active traction rotary clamping mechanism 4, and an ultrasonic staggered spin bonding mechanism 5. The first fixed base 1 and the second fixed base 2 are arranged opposite to each other on the worktable, and a processing space for the core-wafer composite 7 is formed between the first fixed base 1 and the second fixed base 2. By arranging the first fixed base 1 and the second fixed base 2 opposite to each other, the processing space for the core-wafer composite 7 is clearly defined, providing a stable working area for the entire processing process, ensuring that each mechanism works collaboratively within this space, and guaranteeing the accuracy and stability of the processing. The rotary clamping mechanism 3 is mounted on the first fixed base 1 and is used to clamp one end of the core-wafer composite 7 and drive the core-wafer composite 7 to rotate around its own axis. The rotating clamping mechanism 3 reliably clamps one end of the tube-core composite 7 and drives it to rotate around its own axis, providing the necessary rotational motion for subsequent spinning and other processing operations. This ensures the stability of the circumferential motion of the tube 71 during processing and helps to achieve uniform diameter reduction and fit. The active traction rotating clamping mechanism 4 is installed on the second fixed base 2 and is used to clamp the other end of the tube-core composite 7. The active traction rotating clamping mechanism 4 has a degree of freedom of movement along the axial direction of the tube-core composite 7 and is used to apply a controllable axial tensile displacement to the tube-core composite 7 during processing. The active traction rotating clamping mechanism 4 can not only clamp the other end of the tube-core composite 7, but also has a degree of freedom of movement along the axial direction and can apply a controllable axial tensile displacement. This helps to transform the material buildup caused by radial shrinkage during the diameter reduction process into axially controlled elongation, suppressing bulging, corrugation, and wrinkling, and improving the overall uniformity, dimensional accuracy, and forming stability of the tube 71 and core 72. The ultrasonic staggered spinning bonding mechanism 5 includes a movable base 51, at least three spinning units 52, and multiple ultrasonic vibration units 53. The movable base 51 is movably disposed between the first fixed base 1 and the second fixed base 2 along the axial direction of the tube-core composite 7. Each spinning unit 52 is mounted on the movable base 51, and each... Spinning units 52 are distributed circumferentially along the core-tube composite 7 and staggered relative to each other along the axial direction of the core-tube composite 7. The spinning units 52 form a multi-stage spinning channel with increasing radial reduction gradient in the sequence of the working process. An ultrasonic vibration unit 53 is correspondingly disposed on each spinning unit 52 to apply high-frequency micro-amplitude mechanical vibration to the core-tube composite 7 to reduce interfacial frictional resistance and promote plastic flow of the material. A movable base 51 can move axially, providing a moving carrier for the spinning units 52, allowing the spinning process to proceed along the axial direction of the core-tube composite 7. At least three spinning units 52 are circumferentially distributed and axially staggered, forming a multi-stage spinning channel with increasing radial reduction gradient, achieving progressive plastic deformation round by round, precisely controlling the deformation of the tube 71, and improving dimensional control accuracy. The ultrasonic vibration unit 53 applies high-frequency micro-amplitude mechanical vibration, effectively reducing interfacial frictional resistance, promoting plastic flow of the material, improving the uniformity of metal plastic flow, reducing surface indentations, scratches, and other defects, and improving bonding quality.

[0027] In a preferred embodiment, at least one follower support mechanism 6 is further included. The follower support mechanism 6 is disposed within the processing space of the core composite 7 and located below the core composite 7. The follower support mechanism 6 has a degree of freedom of movement along the axial direction of the core composite 7 and a degree of freedom of lifting perpendicular to the axial direction of the core composite 7. It is used to dynamically support the core composite 7 near its theoretical maximum deflection position during processing. The follower support mechanism 6 provides dynamic support in real time during the processing of the core composite 7 by axial movement and lifting actions, based on changes in its theoretical maximum deflection position. This effectively suppresses the deflection and vibration caused by the sag of the core composite 7 due to its own weight, ensuring that the tube 71 has a stable coaxial posture before entering the spinning deformation zone, and improving the coaxiality, straightness, and dynamic stability during processing.

[0028] In a preferred embodiment, the follower support mechanism 6 includes a support wheel slide 61, a lifting drive unit 62, a support wheel frame 63, and a follower support wheel 64. The support wheel slide 61 is movably mounted on the worktable along the axial direction of the core composite 7. The fixed end of the lifting drive unit 62 is mounted on the support wheel slide 61, and the movable end of the lifting drive unit 62 extends and retracts in a direction perpendicular to the axial direction of the core composite 7. The support wheel frame 63 is fixedly connected to the movable end of the lifting drive unit 62. The follower support wheel 64 is rotatably mounted on the support wheel frame 63 via a bearing. The wheel surface of the follower support wheel 64 is concave arc-shaped and has an elastic wear-resistant coating. This structural design allows the follower support mechanism 6 to move flexibly along the axial direction of the core composite 7 and to rise and fall vertically. The concave arc-shaped follower support wheel 64 with an elastic wear-resistant coating can better fit the tube 71, provide stable support force, reduce damage to the surface of the tube 71, and adapt to the support requirements of the tube 71 at different positions, ensuring stable support for the tube core composite 7.

[0029] In a preferred embodiment, a plurality of first guide rods and first threaded rods are provided between the first fixed base 1 and the second fixed base 2, which are parallel to the axis of the core composite 7. The support slide 61 includes a support slide 61 body, a first drive motor, a first worm gear, and a first turbine. The first turbine is threaded to the first threaded rod and rotatably mounted on the support slide 61 body. The first worm gear meshes with the first turbine gear for transmission. The first drive motor is mounted on the support slide 61 body and is connected to the first worm gear for transmission. The first guide rod slides through the support slide 61 body to provide guidance and constraint. The lifting drive unit 62 includes a lifting hydraulic cylinder, a servo electric cylinder, or a pneumatic support cylinder. The cylinder body of the lifting drive unit 62 is fixed to the top of the support slide 61 body. The piston rod end is fixedly connected to the support wheel frame 63. The first guide rod and the first threaded rod cooperate to provide precise guidance and transmission for the support slide 61, so that the support slide 61 can move smoothly along the axial direction of the core composite 7. The first drive motor achieves precise control over the movement of the support wheel slide 61 through the transmission of the first worm gear and the first turbine. The lifting hydraulic cylinder or servo electric cylinder serves as the lifting drive unit 62, which can precisely control the lifting height of the support wheel frame 63, thereby achieving precise adjustment of the height of the follower support wheel 64, ensuring that the follower support wheel 64 is always near the theoretical maximum deflection position, providing stable and reliable support.

[0030] In a preferred embodiment, multiple follower support mechanisms 6 are used, with the distance between two adjacent follower support mechanisms 6 along the axial direction of the tube-core composite 7 not exceeding 500 mm. Each follower support mechanism 6 is linked with the ultrasonic staggered spinning bonding mechanism 5. During the axial feeding process of the ultrasonic staggered spinning bonding mechanism 5, the follower support mechanism 6 located behind the ultrasonic staggered spinning bonding mechanism 5 descends sequentially and moves to the front of the ultrasonic staggered spinning bonding mechanism 5 before rising again, so as to always maintain the support in the middle position between two adjacent support points. Multiple follower support mechanisms 6 with a distance of no more than 500 mm can more effectively suppress the deflection of the tube 71 caused by its own weight. The linkage with the ultrasonic staggered spinning bonding mechanism 5 allows the follower support mechanism 6 to dynamically adjust its position during the feeding process of the ultrasonic staggered spinning bonding mechanism 5, always maintaining the middle position between two adjacent support points, that is, near the theoretical maximum deflection position, continuously providing effective support for the tube-core composite 7, and further improving the stability and coaxiality during the processing.

[0031] In a preferred embodiment, three spinning units 52 are used. These three spinning units 52 are distributed at equal angles of 120° along the circumference of the core-tube composite 7, and are spaced 8mm to 15mm apart along the axial direction of the core-tube composite 7. The circumferential arrangement of the three spinning units 52 is a two-below-one-above structure, with two spinning units 52 located on the lower sides of the core-tube composite 7 and one spinning unit 52 located directly above it. The three spinning units 52, distributed at equal angles of 120° circumferentially and spaced apart axially, form a staggered spinning structure, achieving radial force balance and preventing the tube 71 from deflecting and becoming eccentric due to uneven force distribution. This "two-below-one-above" structural layout, combined with axial stagger, creates alternating bending moments within the deformation zone of the tube 71. Utilizing the metal stress redistribution mechanism, it achieves self-calibration of the straightness of the tube 71, reducing the self-weight deflection of the ultra-long thin tube during processing and the adverse additional load on the internal core 72, thereby improving processing accuracy.

[0032] In a preferred embodiment, the movable base 51 is arch-shaped, and the inner arch space of the movable base 51 provides clearance space for the lifting and lowering movement of the follower support mechanism 6. The movable base 51 is provided with multiple sliding grooves extending axially along the core composite 7. Each spinning unit 52 includes a spinning wheel axial displacement base 521, a radial feed unit 522, and a spinning wheel 523. The spinning wheel axial displacement base 521 is slidably connected to the corresponding sliding groove. The radial feed unit 522 is mounted on the spinning wheel axial displacement base 521 and extends radially along the core composite 7. The spinning wheel 523 is rotatably mounted on the radial feed unit 522 via bearings. The spinning wheel axial displacement base 521 includes an axial displacement adjustment mechanism for adjusting the axial spacing between each spinning unit 52 to adapt to the processing requirements of core composites 7 of different specifications. The axial displacement adjustment mechanism includes a second drive motor and a second threaded rod 524. The second drive motor is fixedly connected to the movable base 51. One end of the second threaded rod 524 is fixedly connected to the second drive motor, and the other end is rotatably connected to the movable base 51. The second threaded rod 524 is threadedly connected to the axial displacement base 521 of the rotating wheel to drive the axial displacement base 521 of the rotating wheel to slide along the groove. The radial feed unit 522 adopts a servo electric cylinder or a precision ball screw pair. Its moving end is fixedly connected to the wheel axle of the rotating wheel 523. It is used to drive the rotating wheel 523 to make precise feed movements along the radial direction of the tube core composite 7, so as to realize the radial compression control of the tube 71. The radial feed unit 522 includes multiple electric telescopic rods and a rotating wheel bracket. The top end of the electric telescopic rod is fixedly connected to the axial displacement base 521 of the rotating wheel, and the bottom end is fixedly connected to the rotating wheel bracket. The rotating wheel 523 is installed at the end of the rotating wheel bracket through a bearing. The arch-shaped movable base 51 provides clearance space for the follow-up support mechanism 6 to avoid interference between the follow-up support mechanism 6 and the movable base 51 during operation, and ensure the normal operation of each mechanism. The axial displacement adjustment mechanism can flexibly adjust the axial spacing between each spinning unit 52, enhancing the tooling's adaptability to processing composite tubes 7 of different specifications. The radial feed unit 522 precisely controls the radial feed of the spinning wheel 523 through an electric telescopic rod, ensuring that the pressure and deformation of the spinning wheel 523 on the tube 71 are precisely controlled, thus improving processing accuracy and quality.

[0033] In a preferred embodiment, the radial feed unit 522 can achieve a feed accuracy of 0.01 mm for the rotary wheel 523, and the resolution and repeatability of the radial pressing amount of the rotary wheel 523 reach the micrometer level, which can meet the stringent dimensional control requirements of the progressive forming of high-precision thin-walled tubes 71. The transmission structure of the servo motor and ball screw pair has the characteristics of small backlash and high transmission efficiency. With the full closed-loop feedback system of the grating ruler or magnetic grating ruler, the position of the rotary wheel 523 can be monitored and dynamically compensated in real time, ensuring the stability of the pressing amount during long-term continuous processing and avoiding dimensional drift caused by thermal deformation or mechanical wear.

[0034] In a preferred embodiment, a plurality of second guide rods and third threaded rods are provided between the first fixed base 1 and the second fixed base 2, which are parallel to the axis of the core composite 7. Each second guide rod and third threaded rod is located outside the first guide rod and the first threaded rod. The movable base 51 includes a movable base 51 body and a third drive motor. The bottom of the movable base 51 is provided with a threaded hole and a plurality of through holes. The third drive motor is fixedly connected to the first fixed base 1. One end of the third threaded rod is drivenly connected to the output end of the third drive motor, and the other end passes through the threaded hole and is rotatably connected to the second fixed base 2, and is threadedly connected to the threaded hole. Both ends of each second guide rod are fixedly connected to the first fixed base 1 and the second fixed base 2, respectively, and the second guide rod passes through the corresponding through hole and is slidably connected to the movable base 51 body. The arrangement of the second guide rods and third threaded rods provides a stable guiding and transmission structure for the movable base 51. The third drive motor drives the movable base 51 to move axially along the core-tube composite 7 via the third threaded rod. The second guide rod ensures the straightness and stability of the movement of the movable base 51, enabling the ultrasonic staggered spinning bonding mechanism 5 to feed precisely along the axial direction, ensuring the accuracy and stability of the spinning process.

[0035] In a preferred embodiment, the rotary clamping mechanism 3 includes a first rotary drive unit 31, a first clamping disk 32, and a solid end plug 33. The first rotary drive unit 31 is embedded in the first fixed base 1. The first clamping disk 32 is connected to the output end of the first rotary drive unit 31. The solid end plug 33 is used to be embedded in the tube 71 of the tube-core composite 7 and abuts against the end of the core 72 of the tube-core composite 7. The first clamping disk 32 includes a plurality of first radial clamping claws, each of which is evenly distributed circumferentially along the first clamping disk 32 and is capable of... Synchronous radial contraction clamps the outer wall of the tube 71, ensuring a tight fit between the first radial clamping claws, the tube 71, and the solid end plug 33. The active traction rotary clamping mechanism 4 includes a second rotary drive unit 41, a second clamping disc 42, a hollow end plug 43, a tail hydraulic rod 44, a traction slide 45, and an active traction drive unit 46. The second rotary drive unit 41 is embedded in the traction slide 45, which is slidably mounted on the second fixed base 2 along the axial direction of the tube core composite 7. The fixed end of the active traction drive unit 46 is mounted on the second fixed base. 2. The movable end of the active traction drive unit 46 is drivenly connected to the traction slide 45 to drive the traction slide 45 to move axially. The second clamping disk 42 is drivenly connected to the output end of the second rotary drive unit 41. The hollow end plug 43 is used to be embedded in the tube 71 of the tube-core composite 7. One end of the tail hydraulic rod 44 passes through the hollow end plug 43 axially and abuts against the end of the core 72 of the tube-core composite 7. The other end passes through the traction slide 45 and is fixedly connected to the second fixed base 2. The second clamping disk 42 includes a plurality of second radial clamping claws. The grippers are evenly distributed circumferentially along the second clamping disk 42 and can synchronously retract radially to clamp the outer wall of the tube 71, so that each second radial clamping gripper, the tube 71, and the hollow end plug 43 are tightly fitted. The tail hydraulic rod 44 has relative axial displacement freedom to compensate for the difference in axial deformation between the core 72 and the tube 71. The rotating clamping mechanism 3, through the cooperation of the first rotating drive unit 31, the first clamping disk 32, and the solid end plug 33, achieves a firm clamping of one end of the tube-core composite 7 and ensures that the end of the core 72 is pressed against, thus ensuring the stability of the tube 71 during rotation. The components of the active traction rotating clamping mechanism 4 work together to not only clamp the other end of the tube-core composite 7, but also achieve axial displacement through the active traction drive unit 46, applying axial tensile force to the tube 71. The tail hydraulic rod 44 abuts against the end of the core 72 and has axial displacement freedom, which can compensate for the difference in axial deformation between the core 72 and the tube 71, ensuring the coaxiality and stability of the tube-core composite 7 during processing and improving processing quality.

[0036] Example 2 This embodiment provides a process for tightly bonding a slender tube 71 to a core 72, including the following steps: (1) Equipment status check and no-load calibration: Before loading, check whether the rotary clamping mechanism 3, the active traction rotary clamping mechanism 4, the ultrasonic staggered spinning and bonding mechanism 5, the follower support wheel 64 mechanism, the guiding mechanism, and the hydraulic / electric control system are in normal working condition. Ensure that all three rotating wheels 523 are retracted to the safe position, the active traction rotary clamping mechanism 4 is returned to zero, and the follower support wheel 64 is in the lowest clearance position. Check the coaxiality of the rotary clamping mechanism 3 and the active traction rotary clamping mechanism 4, preferably controlled within 0.02 mm; check the radial runout of the working surface of the rotating wheel 523, preferably not greater than 0.01 mm; check the straightness and smoothness of movement of the radial feed unit 522. Run the rotary clamping mechanism 3, the active traction rotary clamping mechanism 4, and the follower support wheel 64 mechanism under no-load conditions, and connect the ultrasonic power supply of the ultrasonic vibration unit 53 for resonance self-test. The ultrasonic working frequency is preferably 18-30 kHz, commonly 20 kHz or 28 kHz, ensuring the stable connection of the transducer, amplitude transformer, and cable of the ultrasonic vibration unit 53.

[0037] (2) Workpiece pretreatment and size screening: The tube 71 and core 72 to be bonded to the tube-core composite 7 undergo dimensional inspection, surface cleaning, and pre-assembly screening. Preferably, the outer diameter, inner diameter, wall thickness, roundness, ellipticity, and straightness of the tube 71 are inspected along its entire length. Initial straightness is preferably controlled within 0.3–0.5 mm / 1000 mm, and roundness error is preferably no greater than 0.02–0.05 mm. A 15°–30° chamfer can be pre-machined at the end of the tube 71, with a chamfer length preferably 0.3–1.0 mm, to reduce the initial cutting impact of the spinning wheel 523. If the residual stress in the tube 71 or core 72 is large, appropriate stress-relieving treatments such as stress-relief annealing can be performed first. Before assembly, oil, scale, and particulate impurities should be removed, and a small amount of spinning lubricating medium should be applied to the contact area of ​​the spinning wheel 523. The lubricant can be low-viscosity extreme pressure spinning oil or a lubricating film containing solid lubricating components, with a preferred flow rate of 0.5–2 L / min.

[0038] (3) Assembly of pipe 71, core 72 and end plug: The core 72 is inserted into the tube 71, and the grooved solid end plug 33 and hollow end plug 43 are assembled in sequence. The solid end plug 33 preferably has a tight fit or a slight transition fit with the inner hole of the tube 71 and the first clamping disc 32, and the hollow end plug 43 preferably has a tight fit or a slight transition fit with the inner hole of the tube 71 and the second clamping disc 42, to reduce the relative slippage between the first or second radial clamping claw and the tube 71 during rotation. Typical clearance can be controlled within the range of 0–0.02 mm. After assembly, ensure good contact between the end of the core 72 and the end of the tail hydraulic rod 44 to maintain the coaxial support of the tube 71 and the core 72 during subsequent active traction and axial positioning.

[0039] (4) Clamping, alignment and pre-support: First, the end containing the solid end plug 33 is completely locked in the first clamping plate 32; then, one end of the tail hydraulic rod 44 passes through the hollow end plug 43 and presses against the core 72, applying an axial preload. For slender tubes 71 with an outer diameter of 3–25 mm, the preload of the tail hydraulic rod 44 is preferably controlled within the range of 200–300 N. A smaller value is preferable for small-diameter thin-walled tubes, while a larger value can be used for large-diameter or high-rigidity end plugs. After clamping, dynamic alignment begins: the follow-up support mechanism 6 is activated, and the lifting pressure of the pneumatic support cylinder is set to 0.2 MPa–0.5 MPa (adjusted according to the linear density of the tube 71). The concave follower support wheel 64 with a polyurethane wear-resistant coating lifts the pipe 71 from bottom to top, ensuring that there is a support point every ≤500mm. If necessary, this can be further reduced to 300-400mm. In the initial position, the follower support mechanism 6 should be arranged as close as possible to the middle of adjacent support points, i.e., near the theoretical maximum deflection position. Using a dial indicator, the height of the support cylinder is finely adjusted by moving the dial indicator along the axial direction of the pipe core composite 7. This forces the radial runout (TIR) ​​of the 2000mm long pipe 71 to be corrected and controlled within 0.05mm, ensuring absolute positioning on the theoretical horizontal centerline.

[0040] (5) Design of spinning, ultrasonic and traction parameters: Based on the target bonding amount, the dimensions of the tube 71, the core 72, the material rigidity, and the workpiece length, the rotational speeds of the first rotary drive unit 31 and the second rotary drive unit 41, the axial feed speed of the movable base 51, the radial pressing amount of the three spinning units 52, the ultrasonic parameters of the ultrasonic vibration unit 53, and the traction speed of the active traction drive unit 46 are set and input into the CNC system. For tight bonding of ultra-long, ultra-thin-walled tubes 71 and cores 72, the rotational speeds of the first rotary drive unit 31 and the second rotary drive unit 41 can generally be set in a lower range of 200–500 mm / min; the overall axial feed speed of the ultrasonic staggered spinning bonding mechanism 5 can be set to 100–1000 mm / min, preferably 400–800 mm / min for the nuclear industry where precision and quality are paramount, and can be appropriately increased if the precision requirements are not extreme; with ultrasonic assistance, a traction system, and sufficient support, the theoretical feed speed under conventional precision conditions can be further increased to 600–1200 mm / min. The three wheels are arranged in an inverted Y-shape with 120° equal division along the circumference, two wheels below and one above. The axial offset is preferably 8 to 15 mm, and in this embodiment, it is 13.5 mm.

[0041] for Figure 8The typical working condition shown can be set sequentially according to the cumulative radial reduction: Roller 1 0.10 mm (bearing 50% of the deformation), Roller 2 0.15 mm, Roller 3 0.20 mm + δ (δ is a small overpressure margin, usually around 10% to compensate for material elastic rebound, friction fluctuations, and local gradual deformation differences, ensuring the final diameter reduction is locked at an accurate 0.2 mm); or the total reduction can be distributed as follows: 40%–60%, 20%–35%, and 15%–30%. The preferred ultrasonic parameters are: frequency 20–28 kHz, amplitude 8–20 μm, and power 300–1500 W.

[0042] The tail-end active traction speed is calculated based on the principle of constant volume, meaning that before wheel 1 first contacts the pipe, the outer diameter of the pipe is... The inner diameter is The pre-deformation radius is The elongation of the pipe caused by the feed of wheel 1 is as follows: Subsequently, before vessel number 2 came into contact with the pipe, the outer diameter of the pipe was... The inner diameter is The pre-deformation radius is The elongation of the pipe caused by the feed of wheel 2 is as follows: Before the third wheel finally contacts the pipe, the outer diameter of the pipe is... The inner diameter is The pre-deformation radius is The elongation of the pipe caused by the feed of wheel 3 is as follows: After the tight bonding process is completed, the final outer diameter of the pipe is [missing information]. The inner diameter is The feed lengths of rotary wheels 1, 2, and 3 (523) are all... The axial traction speed component of the active traction drive unit caused by the feed of the No. 1 rotating wheel is: The axial traction speed component of the active traction drive unit caused by the feed of the No. 2 rotating wheel is The axial traction speed component of the active traction drive unit caused by the feed of the No. 3 rotating wheel is: .

[0043] The calculation formula is as follows: Similarly, we can conclude that: Therefore, the axial traction speed of the active traction drive unit is obtained as follows: by Figure 7 Taking the parameters of CNNC fuel tubing 71 and the feed speed of the rotary wheel 523 (a=600 mm / min) as an example, the calculated average active traction speed at the tail end is approximately 21.77 mm / min.

[0044] (6) Positioning and trial operation of the 523 rotating wheel: Move the ultrasonic staggered spinning bonding mechanism 5 to the starting end of the workpiece, so that the No. 1 spinning wheel 523 is in the predetermined pressure-initiating position. First, check the rotational stability of the pipe 71 by low-speed test rotation, preferably 50-100 r / min. After idling for 2-5 revolutions, confirm that there is no obvious wobbling, slippage, or abnormal noise; then raise the spindle to the set processing speed to make it rotate stably. 1-3 seconds before the spinning wheel 523 begins to press down, turn on the ultrasonic vibration to bring the ultrasonic system into a stable working state; at the same time, turn on the lubrication supply to confirm that the lubrication can evenly cover the contact area of ​​the spinning wheel 523.

[0045] (7) Stepped entry and integral spinning feed: Subsequently, the three staggered rotary wheels 523 are synchronously or nearly synchronously pressed radially downwards to their respective predetermined working positions to establish a stable circumferential force balance and initial support state. After all the rotary wheels 523 have completed their set pressing, the ultrasonic staggered spinning and bonding mechanism 5 is fed axially at a uniform speed along the first guide rod towards the active traction rotary clamping mechanism 4, and runs synchronously with the active traction drive unit 46 to achieve progressive micro-diameter reduction bonding wheel by wheel. For a typical pipe 71 with an outer diameter of about 12 mm, a wall thickness of about 0.7 mm, and a total length of not less than 2000 mm, continuous processing can be carried out using process parameters of spindle speed of 200~500 r / min and axial feed speed of 400~800 mm / min.

[0046] (8) Dynamic following and interference avoidance of the follow-up support mechanism 6: During the spinning process, each follower support mechanism 6 axially follows the ultrasonic staggered spinning bonding mechanism 5 according to its real-time position, ensuring that the follower support mechanism 6 is always near the theoretical maximum deflection position between two adjacent support points, thereby dynamically supporting the sag of the pipe 71. To prevent spatial interference between the follower support mechanism 6 and the ultrasonic staggered spinning bonding mechanism 5, this invention adopts an arch-type spinning mechanism base, and cooperates with the lifting drive unit 62 of the follower support mechanism 6 to achieve vertical avoidance; when the ultrasonic staggered spinning bonding mechanism 5 moves forward more than one support spacing, the follower support mechanism 6, which is already located behind the processing area, can pass through from under the arch structure to the new position to be supported, thereby ensuring that the distance between any adjacent support points does not exceed the preset upper limit throughout the entire processing process.

[0047] (9) Tail-end section processing and finishing control: When the spinning mechanism approaches the tail end of the workpiece within 20–50 mm, to reduce local instability and dimensional fluctuations at the tail end, the axial feed speed of the ultrasonic staggered spinning bonding mechanism 5 can be appropriately reduced. The reduction is preferably 10%–30% of the original set value. If necessary, it can pause briefly for 1–3 revolutions to complete the final pressing and sizing. The active traction drive unit 46 should continue to maintain synchronization to avoid local bulging or uneven springback of the tail end material due to sudden tension changes.

[0048] (10) Shutdown, unloading and quality inspection: After processing, the three rotating wheels 523 are withdrawn sequentially, and the ultrasonic power supply, lubrication system, active traction drive unit 46, first rotary drive unit 31, and second rotary drive unit 41 are turned off. After the workpiece comes to a complete stop, the follower support mechanism 6 is lowered and the clamping of the first clamping plate 32 and the second clamping plate 42 on the workpiece is released, and the workpiece is removed. Subsequently, the dimensions and surface quality of the formed core composite are inspected, including outer diameter, roundness, straightness, bonding uniformity, surface roughness, and end morphology. Ideally, the straightness, roundness, and dimensional fluctuations along the entire length after bonding should meet product requirements, and the continuity and reliability of the bonding interface are evaluated by methods such as sampling sectioning, eddy current testing, ultrasonic testing, or airtightness testing.

[0049] (11) Implementation Case Description: Taking the tight bonding of a nuclear fuel tube 71 and core 72 as an example, the initial outer diameter of tube 71 is 12 mm, the inner diameter is 10.6 mm, and the length is not less than 2000 mm; the final outer diameter after bonding is 11.6 mm and the inner diameter is 10.2 mm. The axial misalignment of the three wheels is 13.5 mm, and the cumulative radial reduction is 0.10 mm, 0.15 mm, and 0.20 mm respectively. Due to the extremely high precision requirements, the spindle speed can be 400 r / min, the axial feed speed can be 600 mm / min, the ultrasonic frequency is 20 kHz, the amplitude is 10-15 μm, the power is 800-1000 W, and the average active traction speed at the tail end is calculated to be approximately 21.8 mm / min. Under the above parameters, continuous, stable, and low-damage tight bonding of the ultra-long and slender tube 71 to the core 72 can be achieved with a relatively small reduction in diameter.

[0050] This invention provides a simplified simulation of the ultrasonic staggered spinning tight bonding process of the ultra-long tube 71 and core 72 using the process simulation function of Simufact Forming software. This serves as a reference for using simulation software to perform multiple simulations to confirm the optimal parameters when performing tight bonding of tube 71 and core 72 under the process tooling of this invention.

[0051] (1) Material selection: Taking into account the actual working conditions and the calculation accuracy and computation time of finite element analysis, the lengths of the two pipes 71 were reasonably reduced. After reduction, the two pipes 71 were modeled in UG 3D, as shown below. Figure 10 The material used is P91 material, which has similar properties to the actual material. Table 1 shows the materials and properties used in the cladding tube blank.

[0052] Table 1. Mechanical properties of P91 material

[0053] (2) Mesh Generation: The cladding blank is meshed using a ring-shaped hexahedral mesh centered on the Y-axis. The mesh size is 1mm × 1mm × 1mm, and the total number of meshes is approximately 32,000. The mesh of the cladding blank is adaptively re-divided at level 2 during the subsequent forming process. The specific mesh generation of the cladding blank is as follows: Figure 11 As shown. Other geometric models, such as the 523 spool, are designed as rigid bodies, meaning they do not undergo theoretical plastic deformation during finite element simulation, and therefore are not meshed.

[0054] (3) Boundary conditions and process conditions: In the spinning forming scheme of this part, the mold action is as follows: the shell tube blank is tightly attached to the solid end plug 33 and the hollow end plug 43, and is driven by the solid end plug 33 and the hollow end plug 43 to rotate together at a certain speed. The three spinning wheels 523 simultaneously feed radially to the shell tube so that it partially attaches with the core tube. Then the three spinning wheels 523 synchronously feed axially to achieve the effect of shrinking the diameter of the shell tube. Therefore, according to the motion and spinning design manual, the friction relationship between the molds is set as follows: the friction coefficient between the three forming spinning wheels 523 and the shell tube is 0.05; the friction coefficient between the core tube and the shell tube is 0.3. The end plug speed is selected as 300 r / min, the initial radial pressing speed of the spinning wheel 523 is selected as 0.05 mm / s, and the axial feed speed of the spinning wheel 523 is selected as 300 mm / min.

[0055] (4) Results: such as Figure 12 The equivalent plastic strain contour plot shown and Figure 13 The forming effect diagram shown illustrates that after the diameter reduction and bonding process, the tube 71 and the core 72 are tightly bonded. At this point, the minimum thickness of the outer casing tube is reduced from 0.7mm to 0.6889mm, the maximum gap between the tube 71 and the core 72 is 0.01581mm, and the average deviation rate of the tube wall thickness of the tube 71 is 0.7285%. All of the above data are within a reasonable range.

[0056] At the same time, give as Figure 14 The diagram shown is for reference only and illustrates defects caused by unreasonable parameters. Defects such as instability and wrinkling are present in the diagram.

[0057] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A tooling for tightly fitting a slender tube to a core, characterized in that: include: A first fixed base and a second fixed base are disposed opposite each other on the worktable, and a processing space for the core composite is formed between the first fixed base and the second fixed base; A rotating clamping mechanism is mounted on the first fixed base and is used to clamp one end of the core-tube composite and drive the core-tube composite to rotate around its own axis. An active traction rotary clamping mechanism is installed on the second fixed base and is used to clamp the other end of the core-tube composite. The active traction rotary clamping mechanism has a degree of freedom of movement along the axial direction of the core-tube composite and is used to apply a controllable axial tensile displacement to the core-tube composite during processing. as well as An ultrasonic staggered spinning bonding mechanism includes a movable base, at least three spinning units, and multiple ultrasonic vibration units. The movable base is movably disposed between a first fixed base and a second fixed base along the axial direction of the core-tube composite. Each spinning unit is mounted on the movable base and is distributed circumferentially along the core-tube composite and staggered relative to each other along the axial direction of the core-tube composite. The spinning units form a multi-stage spinning channel with an increasing radial reduction gradient in the sequential order of the working process. The ultrasonic vibration units are correspondingly disposed on each spinning unit and are used to apply high-frequency micro-amplitude mechanical vibration to the core-tube composite to reduce interfacial frictional resistance and promote plastic flow of the material.

2. The tooling for tightly fitting a slender tube to a core according to claim 1, characterized in that: It also includes at least one follower support mechanism, which is disposed in the processing space of the core composite and located below the core composite. The follower support mechanism has a degree of freedom of movement along the axial direction of the core composite and a degree of freedom of lifting perpendicular to the axial direction of the core composite, and is used to dynamically support the core composite near the theoretical maximum deflection position during the processing of the core composite.

3. The tooling for tightly fitting a slender tube to a core according to claim 2, characterized in that: The follow-up support mechanism includes a support wheel slide, a lifting drive unit, a support wheel frame, and a follow-up support wheel. The support wheel slide is movably mounted on the worktable along the axial direction of the core composite. The fixed end of the lifting drive unit is mounted on the support wheel slide, and the movable end of the lifting drive unit extends and retracts in a direction perpendicular to the axial direction of the core composite. The support wheel frame is fixedly connected to the movable end of the lifting drive unit. The follow-up support wheel is rotatably mounted on the support wheel frame via a bearing. The wheel surface of the follow-up support wheel is concave arc-shaped and has an elastic wear-resistant coating.

4. The tooling for tightly fitting a slender tube to a core according to claim 3, characterized in that: The number of the follow-up support mechanisms is multiple, and the distance between two adjacent follow-up support mechanisms along the axial direction of the core composite is no more than 500mm. Each follow-up support mechanism is linked with the ultrasonic staggered spinning bonding mechanism. During the axial feeding process of the ultrasonic staggered spinning bonding mechanism, the follow-up support mechanism located behind the ultrasonic staggered spinning bonding mechanism descends in sequence and moves to the front of the ultrasonic staggered spinning bonding mechanism before rising again, so as to always maintain the support in the middle position between two adjacent support points.

5. The tooling for tightly fitting a slender tube to a core according to claim 4, characterized in that: The number of spinning units is three. The three spinning units are distributed at equal angles of 120° along the circumference of the core composite and are spaced 8mm to 15mm apart along the axial direction of the core composite. The three spinning units are arranged in a two-below-one-above structure, with two spinning units located on the lower two sides of the core composite and one spinning unit located directly above the core composite.

6. The tooling for tightly fitting a slender tube to a core according to claim 5, characterized in that: The movable base is arch-shaped, and the inner arch space of the movable base is used to provide clearance space for the lifting and lowering action of the follow-up support mechanism. The movable base is provided with multiple sliding grooves extending along the axial direction of the tube core composite. Each spinning unit includes a spinning wheel axial displacement base, a radial feed unit and a spinning wheel. The spinning wheel axial displacement base is slidably connected to the corresponding sliding groove. The radial feed unit is installed on the spinning wheel axial displacement base and extends radially along the tube core composite. The spinning wheel is rotatably installed on the radial feed unit through a bearing.

7. The tooling for tightly fitting a slender tube to a core according to claim 6, characterized in that: The rotary clamping mechanism includes a first rotary drive unit, a first clamping disk, and a solid end plug. The first rotary drive unit is embedded in the first fixed base. The first clamping disk is drivenly connected to the output end of the first rotary drive unit. The solid end plug is used to be embedded in the tube of the tube-core composite and abuts against the core end of the tube-core composite. The first clamping disk includes a plurality of first radial clamping claws. Each first radial clamping claw is evenly distributed along the circumference of the first clamping disk and can synchronously retract radially to clamp the outer wall of the tube, so that each first radial clamping claw, the tube, and the solid end plug are tightly fitted. The active traction rotary clamping mechanism includes a second rotary drive unit, a second clamping disk, a hollow end plug, a tail-end hydraulic rod, a traction slide, and an active traction drive unit. The second rotary drive unit is embedded in the traction slide, which is slidably mounted on a second fixed base along the axial direction of the core composite. The fixed end of the active traction drive unit is mounted on the second fixed base, and the movable end of the active traction drive unit is driven by the traction slide to drive the traction slide to move axially. The second clamping disk is driven by the output end of the second rotary drive unit. The core end plug is used to be embedded in the tube of the tube-core composite. One end of the tail-end hydraulic rod passes through the hollow end plug axially and abuts against the core end of the tube-core composite. The other end passes through the traction slide and is fixedly connected to the second fixed base. The second clamping disk includes a plurality of second radial clamping claws. Each second radial clamping claw is evenly distributed around the second clamping disk and can synchronously retract radially to clamp the outer wall of the tube, so that each second radial clamping claw, the tube and the hollow end plug are tightly fitted. The tail-end hydraulic rod has a relative axial displacement degree of freedom to compensate for the difference in axial deformation between the core and the tube.

8. A process for tightly bonding a slender tube to a core, characterized in that: The tooling for tightly fitting a slender tube to a core, as described in claim 7, includes the following steps: S1: Assembly and clamping: The core is inserted into the slender tube to form a tube-core composite. A solid end plug is pressed into one end of the slender tube, and a hollow end plug is pressed into the other end of the slender tube. The solid end plug is clamped in the rotary clamping mechanism, so that each of the first radial clamping claws retracts radially to clamp the outer wall of the tube. The hollow end plug is clamped in the active traction rotary clamping mechanism. The tail hydraulic rod is controlled to extend, so that it passes through the hollow end plug and presses against the end of the core. Each of the second radial clamping claws retracts radially to clamp the outer wall of the tube. S2: Pre-support and alignment: Activate the follow-up support mechanism, control the lifting drive unit to raise the follow-up support wheel to support the core composite, adjust the lifting height of each follow-up support mechanism to control the radial runout of the entire length of the core composite within the set range. S3: Parameter settings: Set the rotation speed of the rotary clamping mechanism and the active traction rotary clamping mechanism, the axial feed speed of the ultrasonic staggered spinning bonding mechanism, the radial pressing amount of each spinning unit, the vibration frequency and amplitude of each ultrasonic vibration unit, and the axial traction speed of the active traction drive unit. S4: Spinning and bonding: Drive the tube-core composite to rotate to a set speed, turn on each of the ultrasonic vibration units to make them resonant working state, control each of the spinning units to feed radially to the predetermined working position in a set sequence, and then drive the ultrasonic staggered spinning and bonding mechanism to feed uniformly along the axial direction of the tube-core composite. At the same time, control the active traction drive unit to drive the traction slide to move backward synchronously at a set axial traction speed, so that the slender tube will radially reduce its diameter and fit tightly with the core. S5: Dynamic following: During the axial feeding process of the ultrasonic staggered spinning bonding mechanism, the axial position of the ultrasonic staggered spinning bonding mechanism is detected in real time, and the axial position and lifting height of each follower support mechanism are adjusted according to the detection results, so that the follower support mechanism located behind the ultrasonic staggered spinning bonding mechanism descends in sequence, moves to the front of the mechanism and then rises again, so as to always keep the follower support wheel supported near the theoretical maximum deflection position of the tube core composite. S6: Finishing and Unloading: When the ultrasonic staggered spinning bonding mechanism is fed to a predetermined distance from the tail end of the core composite, the axial feed speed is reduced. After the tail end diameter reduction is completed, each spinning unit is controlled to withdraw radially in sequence, each ultrasonic vibration unit and rotary drive is turned off, each follower support mechanism is controlled to descend to the lowest position, the tail top hydraulic rod is controlled to retract, the clamping of each radial clamping claw is released, and the processed core composite is taken out.

9. The process for tightly bonding the slender tube to the core according to claim 8, characterized in that: In S4, the radial feed sequence of the three spinning units is as follows: the first spinning unit located obliquely below the core composite cuts in first, the second spinning unit located directly above the core composite then presses in, and the third spinning unit located obliquely below the other side of the core composite presses in last for finishing. In step S4, the axial traction speed of the active traction drive unit Calculated using the following formula: Where 'a' represents the axial feed speed of the ultrasonic staggered spinning bonding mechanism. , , These represent the pre-deformation radius of the pipe after pressing. These are the outer radius and core radius of the slender tube after being pressed into place by the first spinning unit, respectively. These are the outer radius and core radius of the slender tube after being pressed in by the second spinning unit, respectively. These are the outer radius and core radius of the slender tube after it is pressed in by the third spinning unit, respectively.

10. The process for tightly bonding the slender tube to the core according to claim 8, characterized in that: In S2, the radial runout of the entire length of the core composite is controlled within 0.05 mm, and the axial preload of the tail hydraulic rod on the end of the core is controlled between 200 N and 300 N. In step S6, the predetermined distance is 20mm to 50mm, the axial feed speed is reduced by 10% to 30%, and the feed is stopped after rotating 1 to 3 revolutions at the tail end of the core composite.

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