A fatigue testing device for a scoliosis correction growing rod
By designing a fatigue testing device that combines an extended ball-and-socket base with a U-shaped displacement groove, the problem of insufficient clamping point adjustment for scoliosis correction growth rods with complex morphology in existing devices was solved, achieving large-angle interference-free locking and improving the accuracy and stability of the test.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING JISHUITAN HOSPITAL
- Filing Date
- 2026-07-02
- Publication Date
- 2026-07-31
AI Technical Summary
Existing fatigue testing devices are difficult to adapt to scoliosis correction growth rods with complex initial curvatures. The clamping point height adjustment and spatial posture adjustment are insufficient, and in-situ locking cannot be achieved, resulting in poor clamping posture consistency and repeatability accuracy.
Design a fatigue testing device including a base, a universal ball joint clamping unit and a long-stroke power transmission pressure cover. Through axial decoupling and a long-stroke clamping mechanism, interference-free rapid locking is achieved in a large-angle tilt position. An extended ball socket base and a U-shaped displacement groove are used to allow the ball joint neck to swing within a range of ±45° and achieve in-situ locking through the power transmission column.
It achieves interference-free and rapid locking under large-angle tilt poses, improves the consistency of clamping poses and repeatability of positioning accuracy, and ensures the stability and accuracy of mechanical testing.
Smart Images
Figure CN122487155A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the technical field of mechanical testing equipment for medical devices, and specifically relates to a fatigue testing device for a growth bar for scoliosis correction. Background Technology
[0002] Spinal deformities (such as early-onset scoliosis, EOS) are a significant cause of growth and development problems in adolescents, potentially leading to limited thoracic cavity volume, decreased cardiopulmonary function, and even death. Surgical intervention remains the primary treatment method. The Growing Rod system, a rapidly developing implantable device in recent years, allows for spinal growth while correcting deformities, and has therefore been widely used in clinical practice. To ensure the safety and reliability of the Growing Rod during long-term in vivo operation, rigorous mechanical performance evaluation is necessary. Currently, international standards such as ASTM F1717, ASTM F2193, and their modifications are commonly used for static and fatigue testing. During fatigue testing, the test fixture plays a crucial role in simulating the vertebral environment, fixing the specimen, and transferring loads. The fixture's geometric fit, fixation stability, angle adjustment capability, and repeatability directly affect the validity and consistency of the test data. Traditional fixtures often employ rigid metal blocks, V-grooves, and bolt clamping to create a fixed loading span by clamping the two ends of the growth rod.
[0003] As the structure of spinal growth rods becomes increasingly complex, they not only come in different diameters (such as the commonly used 5.5mm specification), telescopic mechanisms, and multi-segment modular structures, but also require adaptation to complex anatomical deformities during clinical implantation, resulting in specimens often exhibiting complex three-dimensional spatial curvature. This complex initial posture requires the experimental fixture to have a large-angle composite adjustment capability in both the sagittal plane (anterior / posterior convexity) and the coronal plane (lateral curvature).
[0004] Existing technologies include fatigue testing devices for spinal implants. For example, Chinese invention patent application CN113884395A discloses a fatigue testing device for spinal implants, comprising an upper clamp, a lower clamp, a pin, a polyethylene block, and a pin-rod fixation system. The pin-rod fixation system includes pedicle screws, connecting rods, and anti-loosening plugs. The polyethylene block simulates the vertebral body environment, and the upper and lower clamps are used in conjunction with a fatigue testing machine to fix and load the spinal implant. This type of device can meet the basic clamping and loading requirements in conventional spinal implant fatigue testing. However, the above-mentioned technical solutions mainly focus on the combined loading of the pin-rod fixation system, the polyethylene block, and the upper and lower clamps. Their clamping and support structures are more suitable for standardized fatigue testing of conventional spinal implants. For specimens such as scoliosis correction growth rods, which have complex initial curvatures, different length specifications, and multi-segment clamping requirements, existing devices still have shortcomings in terms of clamping point height adjustment, spatial posture adjustment, and locking stability under large-angle tilt postures. Especially when simulating large lateral bending postures, a predetermined spatial bending relationship often needs to be formed between different clamping points of the specimen. The existing combination structure of upper clamp, lower clamp and polyethylene block is difficult to adjust the angle of each clamping point independently, and it is also difficult to achieve in-situ locking while maintaining the target tilt posture of the specimen, thus affecting the consistency of clamping posture, repeatability accuracy and load transfer stability in the fatigue test of growth rod. Summary of the Invention
[0005] Based on the above analysis, the present invention aims to provide a fatigue testing device for a scoliosis correction growth bar, in order to solve the technical problems of insufficient adaptability, limited angle adjustment range, severe mechanical interference at extreme angles, inability to achieve in-situ rotation locking, and poor posture stability under large loads in the prior art.
[0006] The objective of this invention is achieved as follows: A fatigue testing device for a scoliosis correction growth bar, comprising: The base has a fastening area, a cylinder extension area and a ball socket swing area connected sequentially from top to bottom. The cylinder extension area is configured to achieve spatial decoupling between the fastening area and the ball socket swing area in the axial direction. The universal ball joint clamping unit has a ball and a ball joint neck, and the ball joint is rotatably mounted in the ball socket swing area; A long-stroke power transmission cap has a cap body and a power transmission column disposed on the cap body. The cap body is mounted in the fastening area, and the power transmission column is configured to extend through the cylindrical extension area into the ball socket swing area to lock the ball to a predetermined deflection angle.
[0007] Furthermore, the base has a ball-and-socket chamber and a longitudinally extending clearance chamber, the clearance chamber being located above the ball-and-socket chamber and communicating with it; the sidewall of the base is provided with a longitudinally extending U-shaped displacement groove, the U-shaped displacement groove extending downward from the top of the base and communicating with the ball-and-socket chamber and the clearance chamber; the ball head neck extends laterally through the U-shaped displacement groove and can swing up and down within the U-shaped displacement groove.
[0008] Furthermore, the axial length of the power transmission column is greater than the longitudinal length of the fastening zone.
[0009] Furthermore, the deflection angle is the angle α between the axis of the ball head and the horizontal plane, and the ball head can swing within the range of -45°≤α≤45°.
[0010] Furthermore, the diameter of the sphere is 20 mm; the diameter of the sphere's neck is 12 mm; the power transmission column is a cylinder with a diameter of 10 mm; the diameter of the sphere's cavity is 20.2 mm; the longitudinal height of the cylindrical extension area is configured to maintain a clearance between the sphere's neck and the fastening area when the sphere swings within the range of -45°≤α≤45°; and the axial extension length of the power transmission column is configured to pass through the cylindrical extension area and press the sphere.
[0011] Furthermore, the bottom locking end of the power transmission column is provided with a concave arc surface, and the curvature of the concave arc surface is adapted to the spherical curvature of the sphere.
[0012] Furthermore, the bottom locking end of the power transmission column is provided with an elastic anti-slip pad.
[0013] Furthermore, the cover of the long-stroke power transmission pressure cap and the fastening area are fastened by external thread or by embedded set screw.
[0014] Furthermore, the long-stroke power transmission cover is provided with an internal hexagonal or cross-shaped drive groove.
[0015] Furthermore, the universal ball joint clamping unit also includes a growth rod clamping head, with the growth rod clamping head and the ball respectively located at both ends of the ball joint neck.
[0016] Compared with existing technologies, the fatigue testing device for scoliosis correction growth rods provided by this invention can meet the simulation requirements of large deflection angles of ±45° and above for growth rods. It overcomes the problems of interference between the rotation path of the pressure cap and the head and neck of the tilting ball, which leads to the inability to lock in place, and the low consistency of the growth rod clamping posture and the low dynamic locking stability. This invention enables fatigue testing to obtain more stable, accurate and clinically relevant mechanical test results. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings. Figure 1 An isometric view of the overall assembly of the universal locking adjustment device provided by the present invention; Figure 2 This is an overall assembly side view of the universal locking adjustment device provided by the present invention; Figure 3 This is a cross-sectional view of the clamping portion of the universal locking adjustment device provided by the present invention; Figure 4 This is a schematic diagram of the structure of the base provided by the present invention; Figure 5 A cross-sectional structural diagram of the base provided by the present invention; Figure 6 This is a schematic diagram of the structure of the universal ball joint clamping unit provided by the present invention; Figure 7 This is a schematic diagram of the universal ball joint clamping unit provided by the present invention lying in the U-shaped displacement groove for pre-positioning; Figure 8 This is a schematic diagram of the structure of the long-stroke power transmission gland provided by the present invention; Figure 9 This is a schematic diagram of the long-stroke power transmission pressure cap and the sphere provided by the present invention; Figure 10 This is a structural schematic diagram of the support column connecting base provided by the present invention; Figure 11 This is a schematic diagram of the structure of the outer sleeve tube provided by the present invention; Figure 12 A schematic diagram of the inner tube of the sleeve provided by the present invention.
[0018] Figure label: 1. Base; 11. Ball-and-socket chamber; 12. Clearance chamber; 13. U-shaped displacement groove; 2. Universal ball joint clamping unit; 21. Ball body; 22. Ball joint neck; 23. Growth rod clamping head; 3. Long-stroke power transmission gland; 31. Cover body; 32. Power transmission column; 321. Arc-shaped pressure groove; 4. Support column connected to base; 5. Outer sleeve; 6. Inner tube of the sleeve; 7. Growth rods to be tested. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be noted that, unless otherwise specified, the implementation methods and features in the implementation methods in this disclosure can be combined, separated, interchanged, and / or rearranged. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0020] In the accompanying drawings, the dimensions and relative dimensions of components may be exaggerated for clarity and / or descriptive purposes. When exemplary embodiments can be implemented differently, a specific process sequence may be performed in a different order than that described. For example, two consecutively described processes may be performed substantially simultaneously or in the reverse order of their description. Furthermore, the same reference numerals denote the same components.
[0021] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms “a” and “the” are intended to include the plural forms as well. Furthermore, when the terms “comprising” and / or “including” and variations thereof are used in this specification, it indicates the presence of the stated features, integrals, steps, operations, parts, components, and / or groups thereof, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, parts, components, and / or groups thereof. It should also be noted that, as used herein, the terms “substantially,” “about,” and other similar terms are used as approximate terms rather than as terms of degree, thus explaining the inherent biases in measurements, calculated values, and / or provided values that would be recognized by one of ordinary skill in the art.
[0022] Example 1 To address the shortcomings of existing spinal growth rod fatigue testing fixtures, such as physical interference at extreme angles, inability to lock in place, and insufficient dynamic stability, a specific embodiment of the present invention discloses a fatigue testing device for scoliosis correction growth rods. This device is a long-stroke universal locking spinal growth rod fatigue testing device with axial decoupling function. Through the synergistic effect of spatial decoupling design and long-stroke clamping mechanism, interference-free and rapid locking is achieved under large-angle tilt positions. The fatigue testing device for scoliosis correction growth rods includes a base, a universal ball joint clamping unit, and a long-stroke power transmission pressure cap. The base is an extended ball joint base, which spatially decouples the top fastening area from the bottom ball joint swinging area by extending its cylindrical height longitudinally. The universal ball joint clamping unit is connected inside the base. The long-stroke power transmission pressure cap is used to lock the position of the universal ball joint clamping unit. The long-stroke power transmission pressure cap integrates a power transmission column that extends into the ball joint cavity. Through this power transmission column, the fastening pressure is transmitted from the top of the base to the deep ball joint surface, realizing in-situ (non-alignment) rotational locking under large-angle tilt.
[0023] like Figures 1 to 12 As shown, the base 1 has a fastening area, a cylindrical extension area, and a ball-and-socket swing area connected sequentially from top to bottom. The cylindrical extension area is configured to spatially decouple the fastening area and the ball-and-socket swing area in the axial direction. The universal ball head clamping unit 2 has a ball 21, a ball head neck 22, and a growth rod clamping head 23. The ball 21 is rotatably mounted in the ball-and-socket swing area. The growth rod clamping head 23 is used to clamp and fix the growth rod 7 to be tested. The growth rod clamping head 23 and the ball 21 are respectively located at both ends of the ball head neck 22. The long-stroke power transmission pressure cap 3 has a cover 31 and a power transmission column 32 provided on the cover 31. The cover 31 is mounted in the fastening area. The power transmission column 32 is configured to extend into the ball-and-socket swing area through the cylindrical extension area to lock the ball 21 to a predetermined deflection angle.
[0024] In this embodiment, the base 1 adopts a longitudinally extending cylindrical structure, and the axial height of the base 1 is increased, thereby forming an independent clearance chamber 12 above the ball-and-socket chamber 11. That is, the base 1 has an elongated ball-and-socket structure inside, which has a ball-and-socket chamber 11 and a longitudinally extending clearance chamber 12. The clearance chamber 12 is located above the ball-and-socket chamber 11 and communicates with it. The side wall of the base 1 is provided with a longitudinally extending U-shaped displacement groove 13. The U-shaped displacement groove 13 extends downward from the top of the base 1 and extends to the edge of the ball-and-socket chamber 11, or extends to the vicinity of the equatorial plane of the center of the ball-and-socket chamber 11, and communicates with the ball-and-socket chamber 11 and the clearance chamber 12. The U-shaped displacement groove 13, together with the extended clearance chamber 12 of the base 1, constructs a large-angle active envelope space that supports bidirectional composite bending simulation, providing a physical channel for the deflection of the ball neck 22. The ball neck 22 extends laterally through the U-shaped displacement groove 13 and can swing up and down within it. This extended design of the base 1 completely separates the top fastening area from the bottom ball socket swing area in space, eliminating the encroachment of the fastening cover 31 on the universal swing space. Specifically, the ball neck 22 can achieve a large-scale deflection (±45° or more) within the U-shaped displacement groove 13 of the base 1, and can even directly "lie" into the U-shaped displacement groove 13 for pre-positioning. Due to the increased longitudinal height of the base 1, the ball neck 22 and the locking area at the top of the base 1 do not overlap axially when the ball 21 is tilted, providing a geometric prerequisite for in-situ locking.
[0025] It should be noted that the width and shape of the U-shaped displacement groove 13 can be changed to accommodate ball necks 22 of different specifications.
[0026] In this embodiment, the cover 31 of the long-stroke power transmission pressure cap 3 is connected to the fastening area of the base 1 via a threaded pair. Specifically, the cover 31 extends at least partially into the fastening area of the base 1, forming a threaded fit between the cover 31 and the fastening area. When the cover 31 is screwed on, it drives the power transmission column 32 to move downward along the axial direction of the base 1, allowing the power transmission column 32 to pass through the cylinder extension area and extend into the ball socket swing area to press the ball 21 and lock the universal ball head clamping unit 2 at a predetermined deflection angle. Because the cover 31 adopts a recessed threaded connection structure, the lower outer contour of the cover 31 near the base 1 does not exceed or substantially does not exceed the outer diameter of the base 1, thereby reducing the risk of radial interference between adjacent clamps during multi-segment spinal growth rod testing. In multi-segment spinal growth rod fatigue testing, multiple of these test devices can be set at intervals on the same fatigue test platform. Each supporting column is connected to the base 4 and is connected to the fatigue test platform. The spacing between adjacent devices is adjusted according to the length of the growth rod 7 to be tested, the number of clamping points, and the target bending posture. The extension height of the inner sleeve tube 6 relative to the outer sleeve tube 5 is used to adjust the height of each clamping point. Each universal ball joint clamping unit 2 clamps the growth rod 7 to be tested at different positions and is adjusted to the corresponding deflection angle according to the simulation requirements of spinal physiological curvature or scoliosis. After adjustment, each long-stroke power transmission pressure cap 3 is screwed in through the threaded pair and drives the corresponding power transmission column 32 to press the ball 21, thereby locking the angle of each clamping point in place, so that the growth rod 7 to be tested forms a predetermined spatial bending posture between multiple clamping points and is subjected to fatigue loading in this posture.
[0027] Furthermore, the long-stroke power transmission cap 3 is equipped with an internal hexagonal or cross-shaped drive groove, which allows a constant locking torque to be applied by standardized tools, ensuring that the locking stiffness of the clamp on the growth rod meets the stability requirements of high-cycle fatigue testing under extreme postures simulating pathological lateral bending.
[0028] In this embodiment, the long-stroke power transmission cover 3 not only has fastening threads, but also integrates a power transmission column 32 extending longitudinally downward inside. The power transmission column 32 protrudes from the cover body 31, and the axial length of the power transmission column 32 is greater than the axial length of the cover body 31, that is, the axial length of the power transmission column 32 is greater than the longitudinal length of the fastening area.
[0029] In this embodiment, the deflection angle α is the angle between the axis of the ball head neck 22 and the horizontal plane. Through the cooperation of the ball socket chamber 11, the clearance chamber 12, the U-shaped displacement groove 13, the ball head neck 22 with a diameter of 12mm, and the retracted long-stroke power transmission pressure cap 3, the ball head neck 22 can swing upward and downward relative to the horizontal plane in the longitudinal direction, and its swing range is -45°≤α≤45°. When the ball head neck 22 is at the target position of α=45° or α=-45°, clearance gaps are maintained between the ball head neck 22, the growth rod clamping head 23 and the base 1, the cap 31 and the power transmission column 32.
[0030] For example, the diameter of the ball-and-socket chamber 11 is 20.2 mm, and the diameter of the ball 21 is 20 mm, allowing the ball 21 to rotate within the ball-and-socket chamber 11 and form a clearance fit; the diameter of the ball head neck 22 is 12 mm; the power transmission post 32 is a cylindrical structure with a diameter of 10 mm. The diameter of the power transmission post 32 is smaller than the inner diameter of the clearance chamber 12, allowing the power transmission post 32 to move axially downward along the clearance chamber 12 and extend into the ball-and-socket swing area; at the same time, the radial dimension of the power transmission post 32 is configured to avoid the spatial projection of the ball head neck 22 when the ball head neck 22 is in an inclined posture of α=45° or α=-45°, thereby avoiding interference between the power transmission post 32 and the ball head neck 22 during rotational downward movement or axial downward pressure.
[0031] In this embodiment, the clearance chamber 12 is a longitudinal chamber communicating with the ball-and-socket chamber 11, and the inner diameter of the clearance chamber 12 is 20.2 mm; the power transmission column 32 is a cylindrical structure with a diameter of 10 mm. The power transmission column 32 can move downward along the axial direction of the base 1 as the cover 31 is screwed in, and extends into the ball-and-socket swing area via the clearance chamber 12. Since the diameter of the power transmission column 32 is smaller than the inner diameter of the clearance chamber 12, the power transmission column 32 can avoid the ball neck 22 in an inclined position during the downward movement, and transmit the axial locking force generated by the threaded pair to the ball 21, thereby reducing the risk of attitude drift of the universal ball head clamping unit 2 during fatigue testing.
[0032] In existing fatigue testing devices, the angle adjustment space and locking space are usually arranged quite compactly. When the ball joint neck is in a large tilt position, it is easy for the ball joint neck to interfere with the fasteners or the upper structure of the base, thus limiting its swing angle range and making it difficult to stably cover the target clamping posture of ±45°. In this embodiment, the base 1 has a cylindrical extension area above the ball socket chamber 11, and a longitudinally extending clearance chamber 12 is formed through the cylindrical extension area, so that the fastening area at the top of the base 1 and the ball socket swing area at the bottom are separated axially. As a result, when the universal ball joint clamping unit 2 swings within the deflection angle range of -45°≤α≤45°, the ball joint neck 22 and the fastening area at the top of the base 1 do not overlap in physical space, thus adapting to the large-angle clamping requirements in scoliosis simulation.
[0033] In one specific embodiment, the longitudinal height of the cylinder extension area is 33mm, and the axial length of the power transmission column 32 extending downward from the cover 31 is 26mm, so that the power transmission column 32 can pass through the avoidance chamber 12 and press the ball 21 in the ball socket chamber 11; the above-mentioned 26mm is the axial extension length of the power transmission column 32, rather than the actual movement stroke of the long-stroke power transmission pressure cap 3 during the screwing process.
[0034] In this embodiment, the bottom locking end of the power transmission column 32 is provided with a concave arc-shaped surface. The curvature of the concave arc-shaped surface matches the spherical curvature of the sphere 21, and the concave arc-shaped surface perfectly fits the sphere 21 to obtain the optimal centripetal pressure distribution. That is, the bottom end of the power transmission column 32 is provided with an arc-shaped pressure groove 321 that matches the spherical surface of the sphere 21. The arc-shaped pressure groove 321 directly contacts the surface of the 20mm sphere 21. The axial pressure generated by the helical pair achieves high-rigidity locking of the sphere 21's position, and the surface contact between the concave arc-shaped surface and the surface of the sphere 21 achieves uniform distribution of the locking load.
[0035] Furthermore, the bottom locking end of the power transmission column 32 is provided with an elastic anti-slip pad to enhance micro-displacement compensation.
[0036] In this embodiment, the fatigue testing device for scoliosis correction growth rods further includes a support column connecting base 4, an outer sleeve tube 5, and an inner sleeve tube 6. The support column connecting base 4 is used to connect to the fatigue testing platform; the lower end of the outer sleeve tube 5 is connected to the support column connecting base 4; the inner sleeve tube 6 is inserted into the outer sleeve tube 5, and the extension height of the inner sleeve tube 6 relative to the outer sleeve tube 5 can be adjusted; the base 1 is connected to the top end of the inner sleeve tube 6. By adjusting the extension height of the inner sleeve tube 6 relative to the outer sleeve tube 5, the installation height of the base 1 and the universal ball joint clamping unit 2 can be adjusted, thereby adapting to growth rods 7 of different lengths and bending postures to be tested.
[0037] The aforementioned support column connecting base 4, outer sleeve tube 5, and inner sleeve tube 6 are mainly used to provide a height-adjustable support foundation for the base 1. Their improved function lies in their ability to coordinate with the angle adjustment of the universal ball joint clamping unit 2, enabling combined adjustment of different clamping points in both height and angle directions. In the fatigue test of multi-segment spinal growth rods, multiple of these test devices can be spaced apart on the same fatigue test platform. By adjusting the installation spacing of adjacent support column connecting bases 4 and the extension height of each inner sleeve tube 6, multiple universal ball joint clamping units 2 can clamp different positions of the growth rod 7 to be tested, forming a predetermined spatial bending posture. Subsequently, each long-stroke power transmission pressure cap 3 locks the corresponding ball 21, allowing the growth rod 7 to be tested to undergo fatigue loading in this spatial posture.
[0038] In one alternative embodiment, the base 1, the universal ball joint clamping unit 2, the long-stroke power transmission pressure cover 3, the support column connecting base 4, the outer sleeve tube 5, and the inner sleeve tube 6 are preferably made of high-strength stainless steel to resist high-frequency vibration loads in fatigue tests.
[0039] When using the fatigue testing apparatus of this embodiment, the universal ball joint unit is first placed into the extended base 1. According to the experimental requirements, the ball joint is directly moved to the target tilt angle (e.g., lying in the U-shaped displacement groove 13). Then, the long-stroke power transmission cover 3 is screwed into the fastening area at the top of the base 1. During the downward rotation of the long-stroke power transmission cover 3, the power transmission column 32 passes through the clearance chamber 12 of the base 1. Due to the presence of the extended clearance chamber 12, the tilted ball joint neck 22 does not interfere with the cover body 31 of the long-stroke power transmission cover 3, until the arc-shaped pressure groove 321 at the bottom precisely presses the ball 21. The entire process achieves one-click locking without needing to straighten the ball joint, significantly improving assembly efficiency and repeatability.
[0040] Compared with the prior art, the fatigue testing device for scoliosis correction growth bars provided in this embodiment can achieve at least one of the following beneficial effects: 1. Through axial spatial decoupling and long-stroke power transmission design, the in-situ interference-free rotational locking under large-angle poses is achieved while significantly improving the universal adjustment angle range. By extending the base height by 16mm, the fastening area is completely moved out of the physical envelope of the ball head deflection, solving the geometric interference problem that traditional test devices are prone to when the tilt angle exceeds 30°. This allows the device to easily achieve extreme pose simulations of ±45° and above, thereby improving the simulation accuracy of scoliosis experiments.
[0041] 2. By using a long-stroke downward pressure transmission column with a diameter of 10mm, the projection of the 12mm ball head neck in an inclined position can be effectively avoided during the locking process. This achieves efficient operation of "in-situ locking" without the need to straighten the sample. This not only greatly shortens the experimental assembly time, but also more effectively ensures the consistency of position and repeatability of positioning accuracy during multi-node linkage adjustment.
[0042] 3. By utilizing the concave arc-shaped surface at the bottom of the power transmission column to form an annular contact with the sphere, the stability of load transmission within the deep cavity of the base is enhanced, ensuring that the universal ball joint clamping unit always maintains zero drift lock when subjected to large load cyclic fatigue testing, significantly improving the reliability of test data.
[0043] 4. The long-stroke power transmission cover adopts a recessed threaded connection structure. The cover body and the base fastening area are matched. The power transmission column extends into the ball socket swing area through the avoidance chamber and transmits the locking force to the ball in the ball socket chamber. While ensuring the locking stability of the universal ball head clamping unit, it can reduce the space occupied in the radial direction of the clamping unit composed of the base, universal ball head clamping unit and long-stroke power transmission cover. This reduces the risk of collision between adjacent clamping units when simulating multi-vertebral segments. Moreover, the overall structure of this invention is simple and stable, easy to operate, and has high engineering application value and promotion prospects.
[0044] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A fatigue testing device for a scoliosis correction growth bar, characterized in that, include: The base (1) has a fastening area, a cylinder extension area and a ball socket swing area connected sequentially from top to bottom. The cylinder extension area is configured to achieve spatial decoupling between the fastening area and the ball socket swing area in the axial direction. The universal ball joint clamping unit (2) has a ball (21) and a ball head neck (22), and the ball head is rotatably mounted in the ball socket swing area; The long-stroke power transmission cap (3) has a cap (31) and a power transmission column (32) provided on the cap (31). The cap (31) is installed in the fastening area. The power transmission column (32) is configured to extend through the cylinder extension area into the ball socket swing area to lock the ball (21) to a predetermined deflection angle.
2. The fatigue testing device for a scoliosis correction growth bar according to claim 1, characterized in that, The base (1) has a ball-and-socket chamber (11) and a longitudinally extending clearance chamber (12), the clearance chamber (12) being located above the ball-and-socket chamber (11) and communicating with the ball-and-socket chamber (11); the side wall of the base (1) is provided with a longitudinally extending U-shaped displacement groove (13), the U-shaped displacement groove (13) extending downward from the top of the base (1) and communicating with the ball-and-socket chamber (11) and the clearance chamber (12); the ball head neck (22) extends laterally through the U-shaped displacement groove (13) and can swing up and down within the U-shaped displacement groove (13).
3. The fatigue testing device for a scoliosis correction growth bar according to claim 2, characterized in that, The axial length of the power transmission column (32) is greater than the longitudinal length of the fastening zone.
4. The fatigue testing device for a scoliosis correction growth bar according to claim 3, characterized in that, The deflection angle is the angle α between the axis of the ball head neck (22) and the horizontal plane, and the ball head neck (22) can swing within the range of -45°≤α≤45°.
5. The fatigue testing device for a scoliosis correction growth bar according to claim 4, characterized in that, The diameter of the sphere (21) is 20 mm; the diameter of the sphere head and neck (22) is 12 mm; The power transmission column (32) is a cylinder with a diameter of 10 mm; The diameter of the ball-and-socket chamber (11) is 20.2 mm; The longitudinal height of the cylindrical extension area is configured to allow the ball neck (22) to maintain a clearance from the fastening area when it swings within the range of -45°≤α≤45°, and the axial extension length of the power transmission column (32) is configured to pass through the cylindrical extension area and press the ball (21).
6. The fatigue testing device for a scoliosis correction growth bar according to claim 5, characterized in that, The bottom locking end of the power transmission column (32) is provided with a concave arc surface, and the curvature of the concave arc surface is adapted to the spherical curvature of the sphere (21).
7. The fatigue testing device for a scoliosis correction growth bar according to claim 1, characterized in that, The bottom locking end of the power transmission column (32) is provided with an elastic anti-slip pad.
8. The fatigue testing device for a scoliosis correction growth bar according to claim 1, characterized in that, The cover (31) of the long-stroke power transmission cover (3) is fastened to the fastening area by external thread or by embedded set screw.
9. The fatigue testing device for a scoliosis correction growth bar according to claim 1, characterized in that, The long-stroke power transmission cover (3) is provided with an internal hexagonal or cross-shaped drive groove.
10. The fatigue testing device for a scoliosis correction growth bar according to claim 1, characterized in that, The universal ball head clamping unit (2) also includes a growth rod clamping head (23), and the growth rod clamping head (23) and the ball (21) are respectively located at both ends of the ball head neck (22).