Large-range automatic centering, tensioning and centering device and control method

Abstract

The invention provides a large-range automatic centering, tensioning and centering device and a control method, and belongs to the technical field of automatic machining. The problems that a traditional tensioning mechanism is small in tensioning range, poor in universality and low in automation degree, and the centering precision is difficult to guarantee are solved. According to the technical scheme, the device comprises a mounting base, a stretching oil cylinder, a stretching rod, a guide sleeve, an upper diameter limiting block, a multi-petal type inner cone tensioning block, a lower diameter limiting block and an inner cone guide block, the tensioning block is driven by the oil cylinder to move in the axial direction of the fixed guide block, and the axial stroke is amplified into radial tensioning through conical surface fit. An elastic split ring is arranged outside to restrain resetting, and an adjustable position sensor is adopted to achieve stroke closed-loop control. The tensioning device has the advantages of being large in tensioning range, high in centering precision, high in self-adaption and easy to integrate and automatically control.

Description

Technical Field

[0001] This invention relates to the field of automated processing technology, and in particular to a large-range automatic centering and tensioning device and control method. Background Technology

[0002] In fields such as automated assembly, welding of components, and bushing processing, tensioning mechanisms serve as core bushing positioning tools, and their performance directly impacts positioning accuracy, operational efficiency, and automation levels. Traditional tensioning mechanisms, especially those with rigid or small-deformation tensioning shafts, generally suffer from the following significant technical bottlenecks:

[0003] First, the tensioning range is extremely limited. For example, for a standard tensioning shaft with a diameter of 50mm, the effective radial tensioning range is typically only between 0.05mm and 0.2mm. This tiny adjustment margin makes the tolerance requirements for workpiece holes extremely stringent during assembly or welding; even slight mismatches can result in ineffective tensioning or interference damage. This significantly increases assembly difficulty and limits its application in workpieces with wide tolerance ranges or varied specifications.

[0004] Secondly, they lack versatility and adaptability. Traditional tensioning mechanisms are mostly specialized tooling designed and manufactured for specific hole diameters. Once the inner hole size of the workpiece changes, the entire tensioning mechanism must be replaced or redesigned and manufactured. This not only increases additional tooling costs and inventory management pressure, but also leads to longer preparation time on production lines with frequent product changes, severely restricting production flexibility and efficiency.

[0005] Furthermore, the integration of automation and intelligence is low. To achieve precise centering and clamping of the bushing, existing technologies often rely on complex multi-part auxiliary tooling and require repeated manual adjustments and interventions. This complex operational mode, which depends on human experience, makes it difficult to achieve efficient and reliable integration of the tensioning process with automated systems such as robots, thus hindering the realization of fully automated production lines and unmanned workshops.

[0006] Therefore, there is an urgent need for a new type of automatic centering and tensioning technology and device with a wide range, high precision, strong adaptability and easy automation control, in order to solve the core problems of existing technologies such as small tensioning stroke, poor workpiece adaptability and difficulty in automation integration, and meet the needs of modern intelligent manufacturing for flexible, efficient and high-precision positioning. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems in the prior art and provide a large-range automatic centering and tensioning device and control method. This invention utilizes a tensioning cylinder to drive a multi-lobed inner cone tensioning block to move axially along a fixed inner cone guide block. Through the conical surface fit, the small axial stroke is accurately converted into a large-range radial extension and contraction. At the same time, the upper and lower elastic open rings constrain the synchronous reset of the tensioning block, and an adjustable position sensor is used to control the cylinder stroke in a closed loop, thereby achieving high-precision, adaptive, and automated centering and tensioning for bushings of different diameters.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a large-range automatic centering and tensioning device, characterized in that it includes: a mounting base, a tension cylinder fixed on the mounting base, a tension rod connected to the piston rod of the tension cylinder, and a guide sleeve, an upper diameter limiting block, a multi-lobed inner cone tensioning block, a lower diameter limiting block, and an inner cone guide block, which are sequentially sleeved on the outside of the tension rod from top to bottom.

[0009] The multi-lobed inner conical tensioning block is composed of at least three independent tensioning block lobes surrounding each other, and its inner wall is a conical surface with a gradually expanding diameter from top to bottom; the inner conical guide block has an outer conical surface that matches the taper of the inner wall of the multi-lobed inner conical tensioning block, and is inserted inside the multi-lobed inner conical tensioning block.

[0010] A transmission mechanism is provided between the upper diameter limiting block and the tension rod. The tension cylinder drives the upper diameter limiting block and the multi-lobed inner cone tensioning block to move axially through the tension rod and the transmission mechanism, so that the inner cone surface of the multi-lobed inner cone tensioning block slides relative to the outer cone surface of the inner cone guide block, thereby realizing the expansion or contraction of the multi-lobed inner cone tensioning block in the radial direction.

[0011] The outer wall of the multi-lobed inner conical tensioning block is fitted with at least one elastic open ring to constrain the tensioning block lobes to converge and reset when they contract radially; an elastic reset element is provided between the lower diameter limiting block and the multi-lobed inner conical tensioning block.

[0012] Furthermore, the transmission mechanism includes an annular groove on the tension rod and a double-lobed stop block embedded in the groove. The inner wall of the upper diameter limiting block is provided with a first annular platform that mates with the double-lobed stop block. When the tension rod is pulled downward by the tension cylinder, the double-lobed stop block presses against the first annular platform, causing the upper diameter limiting block and the multi-lobed inner cone tensioning block connected thereto to move downward synchronously. This solves the problems of reliability and structural simplification in power transmission, achieving the technical effect of efficiently and stably converting the linear tension of the cylinder into the axial movement of the tensioning block.

[0013] Furthermore, the elastic open ring includes a top elastic open ring fitted on the upper part of the multi-lobed inner cone tensioning block and a bottom elastic open ring fitted on the lower part. The elastic open ring is made of spring steel and has an opening gap on its ring body. This addresses the problem of asynchronous or jammed segments during the contraction of the multi-lobed tensioning block. The upper and lower elastic open rings provide a uniform and sustained radial tightening force, ensuring that the tensioning block can quickly and synchronously return to its initial minimum diameter, thereby improving the technical effect of resetting accuracy and reliability.

[0014] Furthermore, the inner wall of the lower diameter limiting block is provided with a second annular platform, and the bottom of the multi-lobed inner cone tensioning block is located above the second annular platform, and moves axially within the space defined by the multi-lobed inner cone tensioning block and the second annular platform. This solves the problem of radial displacement or swaying that may occur during the expansion and resetting of the multi-lobed inner cone tensioning block. Through the guiding and limiting function of the second annular platform, it is constrained to move smoothly only within a set path, thus achieving the technical effect of ensuring centering accuracy and motion stability.

[0015] Furthermore, the elastic reset element is a spring. The upper end of the spring is housed in the upper circular groove at the bottom of the multi-lobed inner conical tensioning block, and the lower end of the spring is located in the lower circular groove on the upper surface of the lower diameter limiting block. The spring remains in a compressed state, even when the diameter of the tensioning sleeve is reduced and the spring length is at its maximum, providing a certain elastic force. This solves the problem of the tensioning block needing rapid and automatic reset after the hydraulic cylinder releases force. The spring provides a stable axial reset thrust, and the grooved structure effectively prevents the spring from dislodging or shifting during compression and reset, achieving the technical effect of ensuring the reliability of the device's cyclic operation and the accuracy of reset.

[0016] Furthermore, the piston rod of the tensioning cylinder is equipped with a sensing magnetic ring, and the cylinder barrel of the tensioning cylinder is equipped with a position sensor whose installation position can be adjusted along its axial direction. The position sensor is used to detect the position of the sensing magnetic ring and output a signal. This solves the problem that traditional tensioning mechanisms are difficult to accurately control the final tensioning diameter to adapt to workpieces of different specifications. Through the cooperation of the position sensor and the sensing magnetic ring, accurate detection and control of the cylinder stroke are achieved, thereby achieving the technical effect of flexibly and accurately setting and automatically achieving the predetermined tensioning size according to the target diameter.

[0017] A control method for a wide-range automatic centering and tensioning device includes the following steps:

[0018] S1: Set the target change in tension diameter ΔD;

[0019] S2: The target stroke ΔL of the tensioning cylinder is calculated according to the formula ΔL = ΔD / tan(X°); where X° is the cone angle of the inner cone surface of the multi-lobed inner cone tensioning block.

[0020] S3: Adjust and fix the installation position of the position sensor on the cylinder barrel of the stretching oil cylinder according to the calculated target stroke ΔL.

[0021] S4: Control the stretching oil cylinder to actuate and drive the multi-lobe inner conical tightening block to expand radially; when the position sensor detects that the induction magnetic ring on the piston rod moves to its set position, send a signal to control the stretching oil cylinder to stop and maintain pressure. At this time, the device reaches the target tightening diameter.

[0022] Further, in step S2, the included angle X° of the inner conical surface of the multi-lobe inner conical tightening block ranges from: 0° < X < 90°. This is to solve the problem that improper selection of the included angle leads to too small tightening stroke or reduced mechanical efficiency and structural strength. By limiting the included angle within a reasonable acute angle range, it ensures that while obtaining a large radial tightening amount, good mechanical transmission efficiency and structural stability are maintained, achieving the technical effect of optimizing the comprehensive performance of the device.

[0023] Further, in step S3, a graduated chute is provided on the cylinder barrel of the stretching oil cylinder. The position sensor is detachably installed in the chute through a fastener and can move along the chute to the graduated position corresponding to the target stroke ΔL and then be locked and fixed. This is to solve the problem that the adjustment process of the position sensor is cumbersome and not intuitive. Through the design of the graduated chute, the position adjustment of the sensor becomes intuitive, fast and accurate, facilitating quick setting according to the calculated ΔL, achieving the technical effect of improving the adjustment efficiency and operation convenience of the equipment when adapting to different workpiece specifications.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] First, the core beneficial effect of the present invention is that it fundamentally overcomes the inherent defect of the narrow adjustment range of the traditional tightening mechanism. Through the innovative "axial small displacement - radial large deformation" transmission principle, that is, by using the conical surface fit between the multi-lobe inner conical tightening block and the fixed inner conical guiding block, the limited axial stroke (ΔL) of the oil cylinder is amplified into a significant radial tightening amount (ΔD) through the tangent trigonometric function relationship (tanX°). This design enables a single set of devices to cover a wider aperture tolerance range, achieving a breakthrough from "special shaft and special hole" to "one shaft with multiple diameters", significantly improving the versatility of the tooling and the tolerance for workpiece fluctuations, and reducing the assembly failure rate caused by dimensional microdifferences.

[0026] Secondly, this device achieves a wide range of tension while excellently ensuring high centering accuracy and operational reliability. The multi-lobed tensioning block, under the uniform constraint of the elastic open ring, can synchronously and symmetrically expand and contract radially, avoiding skewing and jamming, ensuring uniform distribution of tension force, and thus providing extremely high centering accuracy for the bushing. Furthermore, an integrated position sensor that can be flexibly adjusted along a graduated groove constructs a simple yet precise closed-loop control system. Users only need to calculate and set the sensor position according to the formula to automatically and repeatedly achieve the preset tension diameter, transforming complex precision control into intuitive and reliable programmed operation, greatly reducing reliance on operator experience.

[0027] Third, this invention significantly improves the level of production automation and overall efficiency. Its compact, integrated structure makes it easy to integrate into automated production lines or robotic end effectors. The entire positioning-tensioning-releasing cycle can be completed via a simple hydraulic cylinder extension / retraction signal, perfectly adapting to the rhythm of automated production. This not only frees manual labor from tedious debugging and clamping work, but also greatly shortens the tooling preparation and positioning time when switching between different product specifications through rapid changeover and precise reproduction capabilities. Therefore, this invention is not only a high-performance positioning tool, but also a key functional component driving efficient and flexible automated production in fields such as assembly and welding. Attached Figure Description

[0028] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0030] Figure 2 This is an exploded view of the overall structure of the present invention.

[0031] Figure 3 This is the internal section of the invention when it is not expanded (the stretching cylinder is extended). Figure 1 .

[0032] Figure 4 This is the internal section of the invention when it is not expanded (the stretching cylinder is extended). Figure 2 .

[0033] Figure 5 This is a cross-sectional schematic diagram of the expansion (contraction of the stretching cylinder) of the present invention.

[0034] Figure 6 This is a schematic diagram of the structure of the double-lobed stop block in this invention.

[0035] Figure 7 This is a schematic diagram of the top elastic open ring structure in this invention.

[0036] Figure 8 This is a schematic diagram of the overall structure of the multi-lobed inner cone tensioning block in this invention.

[0037] Figure 9 This is a cross-sectional view of the multi-lobed internal conical tensioning block in this invention.

[0038] Figure 10 This is a bottom view of the multi-lobed inner cone tensioning block in this invention.

[0039] Figure 11 This is a schematic diagram of the overall structure of the inner cone guide block in this invention.

[0040] Figure 12 This is a schematic diagram of the overall structure of the lower diameter limiting block in this invention.

[0041] Figure 13 This is a schematic diagram of the tension rod in this invention.

[0042] The attached figures are labeled as follows: 1. Guide sleeve; 2. Double-lobed stop block; 3. Upper diameter limiting block; 4. Top elastic open ring; 5. Multi-lobed inner cone tensioning block; 6. Tension rod; 7. Inner cone guide block; 8. Pin; 9. Bottom elastic open ring; 10. Elastic reset element; 11. Lower diameter limiting block; 12. Mounting base; 13. Tensioning cylinder; 14. Position sensor; 15. Annular groove; 16. First annular platform; 17. Upper circular groove; 18. Lower circular groove; 19. Slide groove; 20. Tensioning block lobe; 21. Second annular platform. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] This invention provides a wide-range automatic centering and tensioning device, aiming to solve the problems of small tensioning range, poor versatility, low automation, and difficulty in guaranteeing centering accuracy in existing tensioning mechanisms. The device is axially arranged and mainly includes a mounting base 12, a tension cylinder 13 fixed on the mounting base 12, a tension rod 6 connected to the piston rod of the cylinder, and, from top to bottom, a guide sleeve 1, an upper diameter limiting block 3, a multi-lobed inner cone tensioning block 5, a lower diameter limiting block 11, and an inner cone guide block 7, which are coaxially sleeved outside the tension rod 6.

[0045] like Figures 1-13 As shown, the connections, positional relationships, and functions of each component are as follows:

[0046] Mounting base 12 serves as the base of the entire device and is typically fixed to an automated production line or robot end effector by bolts. The tension cylinder 13 is vertically fixed below mounting base 12. The lower end of the tension rod 6 is hinged to the piston rod of the tension cylinder 13 via a pin 8, and its upper end passes upwards through the center of the inner conical guide block 7, the lower diameter limiting block 11, the multi-lobed inner conical tensioning block 5, the upper diameter limiting block 3, and the guide sleeve 1.

[0047] 1. Core expansion actuator: Includes a multi-lobed inner conical tensioning block 5 and an inner conical guide block 7. The multi-lobed inner conical tensioning block 5 is composed of at least three independent tensioning block lobes 20 surrounding each other, with its inner wall machined into a conical surface whose diameter gradually increases from top to bottom, and the cone angle denoted as X° (0° < X° < 90°). The inner conical guide block 7 is fixedly installed above the mounting base 12, and its upper outer surface is machined with an outer conical surface that is completely consistent with the cone angle of the inner wall of the multi-lobed inner conical tensioning block 5, and extends into the internal cavity of the multi-lobed inner conical tensioning block 5. This pair of matching conical surfaces constitutes the core mechanism that amplifies axial displacement into radial displacement. When the hydraulic cylinder pulls the multi-lobed inner conical tensioning block 5 downward along the inner conical guide block 7, due to the guidance of the conical surface, each tensioning block lobe 20 is forced to expand outward radially synchronously, thereby achieving a large-range diameter tension. This design fundamentally solves the problem of the extremely limited adjustment range of traditional rigid tensioning shafts (usually only 0.05-0.2mm). By adjusting the cone angle X°, a single device can cover a wide range of bore diameters, achieving a major breakthrough of "one shaft for multiple uses".

[0048] 2. Power Transmission and Limiting Mechanism: Composed of an upper diameter limiting block 3, a lower diameter limiting block 11, and a specific transmission mechanism. The transmission mechanism includes an annular groove 15 located at the top of the tension rod 6, and a double-lobed stop block 2 embedded in the groove. The inner wall of the upper diameter limiting block 3 is machined with a first annular platform 16. The double-lobed stop block 2 is engaged between the annular groove 15 and the first annular platform 16. When the tension cylinder 13 retracts, pulling the tension rod 6 downward, the double-lobed stop block 2 presses against the first annular platform 16, thereby driving the upper diameter limiting block 3 and the connected multi-lobed inner cone tensioning block 5 to move downward synchronously. This design solves the problem of how to efficiently and reliably transmit power from the central tension rod 6 to the peripheral moving parts, with a simple and compact structure and stable transmission.

[0049] The lower diameter limiting block 11 is fixed on the inner cone guide block 7, and its inner wall is provided with a second annular platform 21. The bottom of the multi-lobed inner cone tensioning block 5 is located above the second annular platform 21 and moves up and down within its defined space. This structure solves the problem of radial swaying or wobble that may occur during the movement of the tensioning block. Through the coordinated guidance and limiting of the upper and lower diameter limiting blocks (3, 11), it is ensured that the multi-lobed inner cone tensioning block 5 always moves smoothly along the preset axis, which is the key guarantee for achieving high-precision automatic alignment.

[0050] 3. Reset and Synchronization Constraint Mechanism: This includes elastic open rings and elastic reset element 10. Two elastic open rings are typically provided: a top elastic open ring 4 fitted onto the upper part of the multi-lobed inner cone tensioning block 5 and a bottom elastic open ring 9 fitted onto the lower part. They are made of spring steel such as 65Mn, with an opening gap in the ring body, and are embedded in corresponding ring grooves on the outer wall of the tensioning block. When the cylinder extends and the tensioning block needs to retract and reset, these two elastic open rings use their own elastic force to uniformly and synchronously clamp each tensioning block lobe 20 from both upper and lower positions, forcing it to radially contract and converge. This effectively solves the problems of asynchronous, jamming, or incomplete reset that easily occur during the contraction of multi-lobed structures, ensuring the consistency of the diameter after each contraction, thereby maintaining high repeatability positioning accuracy. The elastic reset element 10 is preferably a spring, with its two ends respectively housed in the upper circular groove 17 machined at the bottom of the multi-lobed inner cone tensioning block 5 and the corresponding lower circular groove 18 on the upper surface of the lower diameter limiting block 11. When the tensioning block moves downward and expands, the spring is compressed and stores energy. After the hydraulic cylinder extends to release the force, the spring releases its energy, providing an upward restoring thrust to the tensioning block, assisting it in returning to its initial position quickly and accurately. The circular groove structure effectively prevents lateral slippage of the spring during compression and reset, ensuring the reliability of the reset action.

[0051] 4. Intelligent control components are key to achieving "automatic" and "precise" tensioning. A sensing magnetic ring is installed on the piston rod of the tension cylinder 13, and an adjustable position sensor 14 with a graduated groove 19 is located outside the cylinder barrel. The position sensor 14 can be moved and locked in any position within the groove 19 using screws. By detecting the position of the sensing magnetic ring, the sensor can send an electrical signal when the piston rod of the cylinder moves to a preset point. This design solves the problem of how to accurately and conveniently control the final tensioning diameter according to different workpiece hole diameters. The operator only needs to calculate the required cylinder stroke ΔL based on the target tensioning diameter change ΔD and the known cone angle X° using the formula ΔL = ΔD / tan(X°), and then adjust the position sensor 14 to the scale position on the groove 19 corresponding to ΔL and lock it. This transforms complex diameter control into an intuitive linear displacement setting, greatly facilitating automation integration and rapid changeover.

[0052] Work process

[0053] This device is typically integrated into automated production lines. During operation, the required radial tension ΔD is first determined based on the inner bore specifications of the bushing to be positioned. The target stroke ΔL of the tension cylinder 13 is calculated using the formula ΔL = ΔD / tan(X°). Subsequently, the position sensor 14 is adjusted and fixed at the scale position corresponding to ΔL on the groove 19 of the cylinder barrel.

[0054] After the bushing is placed over the multi-lobed inner cone tensioning block 5 of this device, the control system is activated. The solenoid valve of the tension cylinder 13 is energized, and the cylinder begins to contract. The piston rod pulls the tension rod 6 downward through the pin 8. The tension rod 6 presses against the first annular platform 16 of the upper diameter limiting block 3 through the double-lobed stop block 2 in its annular groove 15, thereby driving the upper diameter limiting block 3 and the multi-lobed inner cone tensioning block 5 fixed thereto to move downward synchronously.

[0055] During the downward movement, the inner conical surface of the multi-lobed inner conical tensioning block 5 slides along the outer conical surface of the fixed inner conical guide block 7. Due to the guiding effect of the conical surface, each tensioning block lobe 20 is forced to expand outward radially synchronously and uniformly until it is tightly tightened on the inner wall of the bushing, achieving high-precision centering and clamping. At the same time, the downward movement of the multi-lobed inner conical tensioning block 5 compresses the spring below, while the top elastic open ring 4 and the bottom elastic open ring 9 are stretched, but their elastic force always constrains each tensioning block lobe 20, ensuring the synchronicity and stability of the expansion process.

[0056] When the piston rod of the hydraulic cylinder moves the induction magnetic ring to the preset position ΔL, the position sensor 14 detects the magnetic signal and immediately sends an electrical signal. This signal is transmitted to the solenoid valve controlling the hydraulic cylinder. The solenoid valve switches, the hydraulic cylinder stops contracting and enters a pressure-holding state. At this time, the device accurately reaches the preset tension diameter ΔD. Subsequently, the robot arm can perform welding or assembly operations on the precisely positioned bushing.

[0057] After the operation is completed, the control system issues a command, the solenoid valve switches again, and the tension cylinder 13 extends. The cylinder releases the tension, and under the restoring thrust of the compressed spring below, as well as the combined action of the strong radial contraction force of the top elastic open ring 4 and the bottom elastic open ring 9, the multi-lobed inner cone tensioning block 5 moves upward synchronously and smoothly and contracts radially, completely separating from the inner wall of the bushing, returning to the initial minimum diameter state, waiting for the next working cycle.

[0058] In summary, this invention integrates a compact, wide-range, highly accurate, automated, and adaptable tensioning and centering device through innovative conical transmission amplification principle, precise mechanical limit guidance, reliable elastic reset constraint, and intelligent stroke closed-loop control. This effectively meets the high requirements of modern intelligent manufacturing for flexible chemical equipment.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A long-range automatic centering tensioning and centering device, characterized in that, The device is characterized in that it comprises a mounting base (12), a stretching oil cylinder (13) fixed on the mounting base (12), a stretching rod (6) connected with the piston rod of the stretching oil cylinder (13), and a guide sleeve (1), an upper diameter limiting block (3), a multi-petal inner cone expansion block (5), a lower diameter limiting block (11) and an inner cone guide block (7) which are sequentially sleeved outside the stretching rod (6) from top to bottom. The multi-petal inner cone expansion block (5) is composed of at least three independent expansion block petals (20) and has a conical inner wall which expands in diameter from top to bottom; the inner cone guide block (7) has an outer conical surface which matches the inner wall of the multi-petal inner cone expansion block (5) and is arranged inside the multi-petal inner cone expansion block (5). A transmission mechanism is arranged between the upper diameter limiting block (3) and the stretching rod (6), and the stretching oil cylinder (13) drives the upper diameter limiting block (3) and the multi-petal inner cone expansion block (5) to move axially through the stretching rod (6) and the transmission mechanism, so that the inner conical surface of the multi-petal inner cone expansion block (5) slides against the outer conical surface of the inner cone guide block (7), thereby realizing the expansion or contraction of the multi-petal inner cone expansion block (5) in the radial direction. The outer wall of the multi-petal inner cone expansion block (5) is sleeved with at least one elastic split ring for constraining the expansion block petals (20) to gather and reset when they contract in the radial direction; and an elastic resetting element (10) is arranged between the lower diameter limiting block (11) and the multi-petal inner cone expansion block (5).

2. A large range automatic centering tensioning and centering device according to claim 1, characterized in that, The transmission mechanism comprises an annular groove (15) arranged on the stretching rod (6) and a double-petal stop block (2) embedded in the groove, and the inner wall of the upper diameter limiting block (3) is provided with a first annular table (16) matched with the double-petal stop block (2); when the stretching rod (6) is pulled downward by the stretching oil cylinder (13), the double-petal stop block (2) presses against the first annular table (16), thereby driving the upper diameter limiting block (3) and the multi-petal inner cone expansion block (5) connected therewith to move downward synchronously.

3. A large range automatic centering tensioning and centering device according to claim 1 or 2, characterized in that, The elastic split ring comprises a top elastic split ring (4) sleeved on the upper part of the multi-petal inner cone expansion block (5) and a bottom elastic split ring (9) sleeved on the lower part, and the elastic split ring is made of spring steel and is provided with split gaps on the ring body.

4. A large range automatic centering tensioning and centering device according to claim 1, characterized in that, The inner wall of the lower diameter limiting block (11) is provided with a second annular table (21), and the bottom of the multi-petal inner cone expansion block (5) is located above the second annular table (21) and moves axially in the space defined by the second annular table (21).

5. A large range automatic centering tensioning and centering device according to claim 1, characterized in that, The elastic resetting element (10) is a spring, the upper end of the spring is accommodated in an upper circular groove (17) arranged at the bottom of the multi-petal inner cone expansion block (5), and the lower end of the spring is located in a lower circular groove (18) on the upper surface of the lower diameter limiting block (11).

6. A large range automatic centering tensioning and centering device according to claim 1, characterized in that, The piston rod of the stretching oil cylinder (13) is provided with an inductive magnetic ring, and the cylinder barrel of the stretching oil cylinder (13) is provided with a position sensor (14) which can be adjusted in the installation position along the axial direction, and the position sensor (14) is used for detecting the position of the inductive magnetic ring and outputting a signal.

7. A control method for a long-range automatic centering tensioning device as claimed in any one of claims 1-6, characterized in that, The method comprises the following steps: S1: setting a target expansion diameter change amount ΔD; S2: Calculate the target stroke AL of the stretching oil cylinder (13) according to the formula AL = AD / tan(X°), wherein X° is the taper angle of the inner taper surface of the multi-limb inner taper tensioning block (5); S3: Adjust and fix the installation position of the position sensor (14) on the cylinder barrel of the stretching oil cylinder (13) according to the calculated target stroke AL; S4: Control the stretching oil cylinder (13) to act and drive the multi-limb inner taper tensioning block (5) to expand radially; when the position sensor (14) detects that the sensing magnetic ring on the piston rod moves to its set position, a signal is sent to control the stretching oil cylinder (13) to stop and maintain pressure, at which time the device reaches the target tensioning diameter.

8. The control method according to claim 8, characterized by In step S2, the taper angle X° of the inner taper surface of the multi-limb inner taper tensioning block (5) is in the range of 0° < X < 90°.

9. The control method according to claim 7, characterized by, In step S3, the cylinder barrel of the stretching oil cylinder (13) is provided with a scale sliding groove (19), and the position sensor (14) is detachably installed in the sliding groove (19) through fasteners and can be locked and fixed after moving to the scale position corresponding to the target stroke AL along the sliding groove (19).

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