Method for infinitely adjusting axial stiffness

Abstract

The application discloses a method for infinitely adjusting axial rigidity, which comprises the following steps: connecting an elastic component between two axial butt-joint components, so that force transmission is realized by extruding the elastic component when the two axial butt-joint components extrude and pull out each other along the axial direction, and then axial rigidity is adjusted by changing the pre-tightening force of the elastic component along the axial direction; characterized in that the pre-tightening force of the elastic component is changed by extruding the elastic component through a bolt arranged at one end of the elastic component along the axial direction, so that the adjustment is realized. The application has the advantages that the axial rigidity of the connecting arm can be better infinitely adjusted, and the adjustment process is more simple, stable and reliable.

Description

Technical Field

[0001] This invention relates to a stiffness adjustment technology for the connecting arm of an orthopedic external fixator, specifically to a method for stepless adjustment of axial stiffness. Background Technology

[0002] In the rehabilitation process of fracture patients, especially those with limb fractures, orthopedic external fixators are usually required to immobilize the fracture site, prevent secondary damage during rehabilitation, and accelerate the healing process. Existing orthopedic external fixators typically consist of two fixation rings and connecting arms between them. In use, bone pins are installed on the fixation rings and fixed to both ends of the limb fracture site. The telescopic connecting arms then adjust the relative positions of the fixation rings to maintain the limb's normal growth.

[0003] In conventional orthopedic external fixators, while the connecting arms can be adjusted in length, their stiffness is often not adjustable. Furthermore, bone growth varies at different stages of limb fracture healing, leading to varying requirements for the stiffness and flexibility of the fixation support, which conventional orthopedic external fixators cannot meet. To overcome these shortcomings, it is necessary to consider installing variable stiffness adjustment joints on the connecting arms of the orthopedic external fixator. This would allow for adjustment of the axial stiffness of the connecting arms as needed, thus meeting the changing stiffness requirements of support at different stages of bone healing.

[0004] The applicant previously applied for a patent, CN202411638341.1, which disclosed a method for adjusting the axial stiffness of a connecting arm. The method involves connecting an elastic member between two axially mating components, so that whether the two axially mating components are mutually pressing or pulling outwards along the axial direction, the force is transmitted by pressing this elastic member. Then, by changing the preload of the elastic rubber ring along the axial direction, the axial stiffness of the connecting arm is adjusted. This invention can better achieve stepless adjustment of the axial stiffness of the connecting arm, while improving the convenience of adjustment, and enabling direct switching control of the connecting arm from flexible to full stiffness; it has advantages such as convenient adjustment, a large adjustable range, and better stability. However, this solution still has the following drawbacks: 1. This solution uses a rotatable nut to press the elastic member to achieve stepless adjustment of its preload. Therefore, in order to accommodate the right-end locking nut and stiffness adjustment nut, a large window must be machined on the shell, which significantly weakens the strength and stiffness of the shell, increases processing costs, and worsens structural stability. 2. The opening size of the window on the housing for adjusting the stiffness of the nut is limited, making it difficult and inconvenient to tighten when a higher stiffness is required. 3. To limit the relative rotation between the shaft-shaped mating member and the housing, a rectangular groove is machined inside the housing to accommodate the locating pin mounted on the shaft-shaped mating member; keyways are machined on the stiffness adjusting ring and the shaft-shaped mating member to accommodate the sliding key, which then limits the relative rotation between the stiffness adjusting ring and the shaft-shaped mating member. This process is more complex and costly.

[0005] Therefore, how to further improve its structure to make it simpler, more stable and reliable, and facilitate the implementation of the adjustment process has become a problem that needs to be further considered and solved by those skilled in the art. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a method for stepless adjustment of axial stiffness of connecting arm that can better realize the stepless adjustment of axial stiffness and make the adjustment process simpler, more stable and reliable.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for steplessly adjusting axial stiffness involves connecting an elastic member between two axially mating components, such that whether the two axially mating components are mutually pressing or pulling outward along the axial direction, the force is transmitted by pressing the elastic member. Then, the axial stiffness is adjusted by changing the preload of the elastic member along the axial direction. The method is characterized in that the preload of the elastic member is changed by pressing it with a bolt installed at one end of the elastic member along the axial direction, thereby achieving the adjustment.

[0009] In this way, this method directly adjusts the axial stiffness of the (connecting arm) by changing the degree of compression of the elastic rubber ring along the axial direction and altering its axial preload. Therefore, the adjustment process does not require a change in the direction of force, making the adjustment more direct and convenient, and improving its stability and reliability. Furthermore, this method uses bolts to adjust the elastic component by compressing it and changing the preload. The bolts can be adjusted using appropriate wrenches, making it easier to apply force and further simplifying the adjustment process, making it more stable and reliable.

[0010] Furthermore, the elastic component is made of rubber material (preferably TPU rubber). This has advantages such as low cost and a wide range of elasticity adjustment.

[0011] Furthermore, both ends of the elastic member along the axial direction simultaneously abut against two axially mating members. In this way, whether the two axially mating members are pressing against each other or pulling outward along the axial direction, they will compress the elastic member, giving it sufficient flexibility, and the stiffness can be adjusted by changing the degree of compression of the elastic member beforehand.

[0012] Furthermore, this method relies on a bolt-based stepless adjustment device for axial stiffness. This bolt-based stepless adjustment device includes a shaft-shaped mating member and a cylindrical mating member coaxially inserted and mated. The shaft-shaped mating member has a flange at its inner end. It also includes a cylindrical elastic member coaxially disposed between the shaft-shaped and cylindrical mating members, and a preload adjustment mechanism for adjusting the axial preload of the elastic member. The opening of the cylindrical mating member has an inwardly protruding first inner step, and the outer surface of the shaft-shaped mating member has an outwardly protruding first outer step corresponding to the position of the first inner step. The elastic member... One end abuts against the side of the first inner step and the first outer step, and the other end abuts against the pre-tightening adjustment mechanism. The pre-tightening adjustment mechanism includes a ring of adjusting bolts axially arranged along one end of the elastic member. The inner end of the adjusting bolt abuts against the end face of the elastic member, and the other end passes through the flange and the outer end of the cylindrical docking member to form an adjustable bolt head. The flange and the outer end of the cylindrical docking member are each provided with holes that cooperate with each adjusting bolt. Some adjusting bolts are threadedly screwed into the threaded holes on the flange and are clearance-fitted with the sliding holes on the outer end of the cylindrical docking member. Other adjusting bolts are clearance-fitted with the sliding holes on the flange and are threadedly screwed into the threaded holes on the outer end of the cylindrical docking member.

[0013] In this way, when using the device, the outer ends of the axial and cylindrical connecting components are connected to the connecting arm respectively. One end of the elastic component acts on both the axial and cylindrical connecting components simultaneously through the first inner and outer steps, while the other end acts on both components through different adjusting bolts. Therefore, regardless of whether the axial and cylindrical connecting components are under axial compression or tension, the elastic component will be subjected to compression along the axial direction. Thus, the elastic force allows the connecting arm to have an axial movement margin, forming a flexible connection along the axial direction. This allows for stepless adjustment of the axial stiffness of the connecting arm simply by pre-tightening the adjusting bolts to adjust the compression of the elastic component, which is very convenient and provides higher stability. Simultaneously, the bolts themselves also provide an anti-rotation effect between the axial and cylindrical connecting components, making the structure simpler and more ingenious.

[0014] Furthermore, a cylindrical sub-shell is threadedly connected to the opening of the cylindrical docking member, and the first inner step is formed on the inner ring wall of the sub-shell.

[0015] This facilitates the formation of the first inner step and also makes it easier to assemble the internal components.

[0016] Furthermore, the shaft-shaped docking member is threadedly connected to an annular threaded sleeve at the position of the sub-shell. The first outer step is formed on the outer wall of the threaded sleeve, and a gap is left between the outer surface of the threaded sleeve and the inner surface of the sub-shell.

[0017] This facilitates the formation of the first outer step and also makes it easier to assemble the internal components.

[0018] Furthermore, a first rigid gasket is also provided between the step side of the first inner step and the first outer step and the end of the elastic member.

[0019] In this way, whether it is the force exerted on the end of the elastic member by the first outer step when under compression, or the force exerted on the end of the elastic member by the first inner step when under tension, it is transmitted to the end of the elastic member through the rigid pad, making the force more stable and balanced, and avoiding the instability caused by unilateral force on the end of the elastic member resulting in bending deformation.

[0020] Furthermore, the elastic member is made of TPU rubber material.

[0021] Furthermore, in the pre-tightening adjustment mechanism, there are an even number of adjusting bolts evenly distributed along the circumference, with half of the adjusting bolts staggered and threaded onto the flange, and the other half of the adjusting bolts threaded onto the outer end of the cylindrical connecting member.

[0022] In this way, the overall force on the device is more balanced and stable.

[0023] Furthermore, the inner ends of each adjusting bolt abut against the end of the elastic member via a second rigid washer.

[0024] In this way, each adjusting bolt transmits force between the second rigid washer and the elastic component, making the force more stable and balanced, and avoiding instability caused by unilateral force on the end of the elastic component, which would result in folding deformation.

[0025] Furthermore, an external locking nut is threadedly screwed onto the axial docking member located on the outer side of the sub-shell, and an internal locking nut is threadedly screwed onto the end of the sub-shell adjacent to the external locking nut. The end of the internal locking nut away from the external locking nut can abut against a protruding boss on the outer peripheral surface of the sub-shell, and the adjacent ends of the external locking nut and the internal locking nut can abut against each other and lock together.

[0026] In this way, the outer locking nut, through the inner locking nut, abuts against the boss surface on the outer side of the sub-housing, thereby improving the locking force and achieving a self-locking effect. By locking, the connecting arm can be transformed from a flexible connection state with adjustable stiffness to a fully rigid state. Therefore, it allows for switching control when the connecting arm does not need to maintain flexibility, and can be directly locked into a fully rigid state regardless of its current flexibility. It has the advantages of simple structure and convenient adjustment and switching control.

[0027] Furthermore, a shaft joint extends outward from the middle of the outer end of the cylindrical docking component. This facilitates the installation and docking of the device during use.

[0028] In summary, the present invention has the advantages of enabling stepless adjustment of the axial stiffness of the connecting arm, making the adjustment process simpler, more stable and reliable. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the bolt-based stepless adjustment device for axial stiffness variable adjustment used in the implementation of this invention.

[0030] Figure 2 for Figure 1 A schematic diagram of the three-dimensional structure.

[0031] Figure 3 for Figure 1 AA sectional view.

[0032] Figure 4 for Figure 1 A schematic diagram of the device under pressure at both ends.

[0033] Figure 5 for Figure 1 A schematic diagram of the device under tension at both ends. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0035] In a specific implementation, a method for steplessly adjusting axial stiffness involves connecting an elastic member between two axially mating components. This ensures that whether the two axially mating components are pressing or pulling against each other along the axial direction, the force is transmitted by pressing the elastic member. Then, by changing the preload of the elastic member along the axial direction, the axial stiffness can be adjusted. The key feature is that the adjustment is achieved by pressing the elastic member with a bolt installed along the axial direction at one end of the elastic member to change its preload.

[0036] In this way, this method directly adjusts the axial stiffness of the (connecting arm) by changing the degree of compression of the elastic rubber ring along the axial direction and altering its axial preload. Therefore, the adjustment process does not require a change in the direction of force, making the adjustment more direct and convenient, and improving its stability and reliability. Furthermore, this method uses bolts to adjust the elastic component by compressing it and changing the preload. The bolts can be adjusted using appropriate wrenches, making it easier to apply force and further simplifying the adjustment process, making it more stable and reliable.

[0037] The elastic component is made of rubber material (preferably TPU rubber). This has advantages such as low cost and a wide range of elasticity adjustment.

[0038] In this design, both ends of the elastic member along the axial direction simultaneously abut against two axially mating members. This ensures that whether the two axially mating members are pressing against or pulling against each other along the axial direction, they will compress the elastic member, giving it sufficient flexibility. Furthermore, the stiffness can be adjusted by changing the degree of pre-compression of the elastic member.

[0039] Specifically, this method relies on a bolt-based stepless adjustment device for axial stiffness, which can be found in [reference needed]. Figure 1-5As shown, the assembly includes a shaft-shaped mating member 7 and a cylindrical mating member 13 coaxially inserted and mated. The inner end of the shaft-shaped mating member 7 has a flange 5. It also includes a cylindrical elastic member 12 coaxially disposed between the shaft-shaped mating member and the cylindrical mating member, and a preload adjustment mechanism for adjusting the axial preload of the elastic member. The opening of the cylindrical mating member 13 has an inwardly protruding first inner step, and the outer surface of the shaft-shaped mating member 7 has an outwardly protruding first outer step corresponding to the position of the first inner step. One end of the elastic member 12 simultaneously abuts against the step sides of both the first inner step and the first outer step. One end abuts against the pre-tightening adjustment mechanism, which includes a ring of adjusting bolts 1 arranged axially along one end of the elastic member 12. The inner end of the adjusting bolt 1 abuts against the end face of the elastic member 12, and the other end passes through the flange 5 and the outer end of the cylindrical docking member 13 to form an adjusting bolt head. The outer ends of the flange 5 and the cylindrical docking member 13 are each provided with holes that mate with each adjusting bolt 1. Some adjusting bolts are threadedly screwed into the threaded holes on the flange and are clearance-fitted with the sliding holes on the outer end of the cylindrical docking member. Other adjusting bolts are clearance-fitted with the sliding holes on the flange and are threadedly screwed into the threaded holes on the outer end of the cylindrical docking member.

[0040] In this way, when using the device, the outer ends of the axial and cylindrical connecting components are connected to the connecting arm respectively. One end of the elastic component acts on both the axial and cylindrical connecting components simultaneously through the first inner and outer steps, while the other end acts on both components through different adjusting bolts. Therefore, regardless of whether the axial and cylindrical connecting components are under axial compression or tension, the elastic component will be subjected to compression along the axial direction. Thus, the elastic force allows the connecting arm to have an axial movement margin, forming a flexible connection along the axial direction. This allows for stepless adjustment of the axial stiffness of the connecting arm simply by pre-tightening the adjusting bolts to adjust the compression of the elastic component, which is very convenient and provides higher stability. Simultaneously, the bolts themselves also provide an anti-rotation effect between the axial and cylindrical connecting components, making the structure simpler and more ingenious.

[0041] The cylindrical docking member 13 has a cylindrical sub-shell 11 threadedly connected to its opening, and the first inner step is formed on the inner wall of the sub-shell 11.

[0042] This facilitates the formation of the first inner step and also makes it easier to assemble the internal components.

[0043] The shaft-shaped docking member 7 is threadedly connected to an annular threaded sleeve 10 at the position of the sub-shell 11. The first outer step is formed on the outer side wall of the threaded sleeve 10, and there is a gap between the outer surface of the threaded sleeve 10 and the inner surface of the sub-shell 11.

[0044] This facilitates the formation of the first outer step and also makes it easier to assemble the internal components.

[0045] A first rigid gasket 14 is also provided between the side of the first inner step and the first outer step and the end of the elastic member.

[0046] In this way, whether it is the force exerted on the end of the elastic member by the first outer step when under compression, or the force exerted on the end of the elastic member by the first inner step when under tension, it is transmitted to the end of the elastic member through the rigid pad, making the force more stable and balanced, and avoiding the instability caused by unilateral force on the end of the elastic member resulting in bending deformation.

[0047] The elastic member 12 is made of TPU rubber material.

[0048] In the pre-tightening adjustment mechanism, there are an even number of adjusting bolts 1 evenly distributed along the circumference. Half of the adjusting bolts are staggered and threaded onto the flange 5, while the other half are threaded onto the outer end of the cylindrical docking member.

[0049] In this way, the overall force on the device is more balanced and stable.

[0050] The inner end of each adjusting bolt 1 is abutted against the end of the elastic member 12 by a second rigid washer 15.

[0051] In this way, each adjusting bolt transmits force between the second rigid washer and the elastic component, making the force more stable and balanced, and avoiding instability caused by unilateral force on the end of the elastic component, which would result in folding deformation.

[0052] The axial docking member 7 is threaded with an external locking nut 8 located on the outer side of the sub-shell 11. The sub-shell 11 and the adjacent end of the external locking nut 8 are also threaded with an internal locking nut 9. The end of the internal locking nut 9 away from the external locking nut 8 can abut against a protruding boss on the outer peripheral surface of the sub-shell. The adjacent ends of the external locking nut 8 and the internal locking nut 9 can abut against each other and lock together.

[0053] In this way, the outer locking nut, through the inner locking nut, abuts against the boss surface on the outer side of the sub-housing, thereby improving the locking force and achieving a self-locking effect. By locking, the connecting arm can be transformed from a flexible connection state with adjustable stiffness to a fully rigid state. Therefore, it allows for switching control when the connecting arm does not need to maintain flexibility, and can be directly locked into a fully rigid state regardless of its current flexibility. It has the advantages of simple structure and convenient adjustment and switching control.

[0054] The cylindrical docking member 13 has a shaft joint 4 extending outward from the middle of its outer end. This facilitates the installation and docking of the device during use.

[0055] In this embodiment, there are 6 adjusting bolts. It is assumed that the bolts with even numbers, i.e., the upper bolts shown in the cross-sectional view, have their left ends threaded to the threaded holes on the flange and their right ends clearance-fitted to the sliding holes corresponding to the outer ends of the cylindrical docking components. The bolts with odd numbers, i.e., the lower bolts shown in the cross-sectional view, have their left ends clearance-fitted to the sliding holes on the flange and their right ends threaded to the threaded holes corresponding to the outer ends of the cylindrical docking components.

[0056] Rotating the bolt group consisting of six bolts causes the bolt group to press the second washer to the left, increasing the preload of the elastic component 7 and increasing the axial stiffness at both ends of the device, thus enabling stepless adjustment of the axial stiffness at both ends of the device.

[0057] When the entire device is under pressure, the elastic member is squeezed from the right end by the odd-numbered bolts. Because the right end of the odd-numbered bolts is threaded into the threaded hole of the cylindrical mating member, and the left end is clearance-fitted into the sliding hole on the flange, the odd-numbered bolts do not move to the right with the shaft-shaped mating member, but remain stationary relative to the cylindrical mating member. Conversely, the left end of the even-numbered bolts is threaded into the flange, and the corresponding hole in the cylindrical mating member is clearance-fitted; therefore, the even-numbered bolts move to the right with the shaft-shaped mating member. (See attached diagram). Figure 4 As shown. At this time, the force transmission path of the entire device is as follows: shaft-shaped connecting member → threaded sleeve → first rigid washer → elastic member → second rigid washer → bolt with odd number → cylindrical connecting member.

[0058] When the entire device is under tension, the elastic member is compressed from the right end by the even-numbered bolts. Because the right end of the even-numbered bolts has a clearance fit with the hole corresponding to the cylindrical connecting member and a threaded connection with the flange, the even-numbered bolts move to the left together with the shaft-shaped connecting member. However, the left end of the odd-numbered bolts has a clearance fit with the flange and a threaded connection with the hole corresponding to the cylindrical connecting member. Therefore, the odd-numbered bolts do not move to the left with the shaft-shaped connecting member but remain stationary relative to it. (See attached diagram). Figure 5 As shown. At this time, the force transmission path of the entire device is as follows: shaft-shaped docking component → even-numbered bolts → second rigid washer → elastic component → first rigid washer → sub-shell → cylindrical docking component.

[0059] To lock the device in any position and maximize its rigidity, simply rotate the inner locking nut until its right inner end face is pressed against the left end face of the threaded sleeve, then rotate the outer locking nut until its right end face is pressed against the left end face of the inner locking nut. This prevents relative axial movement between the housing and the shaft-shaped mating component, and at this point, the axial rigidity at both ends of the device is at its maximum.

[0060] Therefore, the present invention has the following beneficial effects: 1. Compared with other variable stiffness joints, the present invention has a larger stiffness adjustment range and the ability to adjust stiffness infinitely; 2. Compared with other variable stiffness joints, the present invention can lock the entire device at any position during the extension and contraction deformation of the device, achieving maximum stiffness, unlike similar related inventions which can only reset to a single designated position to lock the device; 3. Compared with the applicant's prior patent solution described in the background art, this application uses bolts to adjust stiffness, which not only allows for more convenient adjustment using a special wrench, but also ensures that even if one bolt connection fails, the remaining normally connected bolts can still function normally, resulting in better reliability; 4. The present invention has a simple and compact structure with lower processing and manufacturing costs; 5. The present invention has a high degree of modularity of components, making maintenance convenient and economical.

Claims

1. A bolt-based stepless axial stiffness adjustment device, comprising a shaft-shaped mating member and a cylindrical mating member coaxially inserted and mated, the shaft-shaped mating member having a flange at its inner end, and further comprising a cylindrical elastic member coaxially disposed between the shaft-shaped mating member and the cylindrical mating member, and a preload adjustment mechanism for adjusting the axial preload of the elastic member; characterized in that, The opening of the cylindrical docking member has an inwardly protruding first inner step, and the outer surface of the shaft-shaped docking member has an outwardly protruding first outer step corresponding to the position of the first inner step. One end of the elastic member abuts against the side of both the first inner step and the first outer step, and the other end abuts against the pre-tightening adjustment mechanism. The pre-tightening adjustment mechanism includes a ring of adjusting bolts arranged axially along one end of the elastic member. The inner end of the adjusting bolt abuts against the end face of the elastic member, and the other end passes through the flange and the outer end of the cylindrical docking member to form an adjustable bolt head. The flange and the outer end of the cylindrical docking member are each provided with holes that cooperate with each adjusting bolt. Some adjusting bolts are threadedly screwed into the threaded holes on the flange and clearance-fitted into the sliding holes on the outer end of the cylindrical docking member. Other adjusting bolts are clearance-fitted into the sliding holes on the flange and threadedly screwed into the threaded holes on the outer end of the cylindrical docking member. The opening of the cylindrical docking member is threadedly connected to a cylindrical sub-shell, and the first inner step is formed on the inner ring wall of the sub-shell. The shaft-shaped docking member is threadedly connected to an annular threaded sleeve at the position of the sub-shell. The first outer step is formed on the outer wall of the threaded sleeve, and a gap is left between the outer surface of the threaded sleeve and the inner surface of the sub-shell. The elastic member connected between the two axially mating members allows the force to be transmitted by pressing the elastic member, whether the two axially mating members are pressing or pulling against each other along the axial direction. The axial stiffness can be adjusted by changing the preload of the elastic member along the axial direction. The adjustment can also be achieved by pressing the elastic member with a bolt installed at one end of the elastic member along the axial direction to change its preload.

2. The bolt-based stepless axial stiffness adjustment device as described in claim 1, characterized in that, The elastic component is made of rubber material.

3. The bolt-based stepless axial stiffness adjustment device as described in claim 1, characterized in that, Both ends of the elastic member along the axial direction simultaneously abut against two axially mating members.

4. The bolt-based stepless axial stiffness adjustment device as described in claim 1, characterized in that, A first rigid pad is also abutting between the side of the first inner step and the first outer step and the end of the elastic member; The elastic component is made of TPU rubber material.

5. The bolt-based stepless axial stiffness adjustment device as described in claim 1, characterized in that, In the pre-tightening adjustment mechanism, there are an even number of adjusting bolts evenly distributed along the circumference. Half of the adjusting bolts are staggered and threaded onto the flange, while the other half are threaded onto the outer end of the cylindrical connecting member.

6. The bolt-based stepless axial stiffness adjustment device as described in claim 5, characterized in that, The inner ends of each adjusting bolt are abutted against the end of the elastic member by a second rigid washer.

7. The bolt-based stepless axial stiffness adjustment device as described in claim 1, characterized in that, An external locking nut is threadedly connected to the axial docking member located on the outer side of the sub-shell. An internal locking nut is threadedly connected to the end of the sub-shell adjacent to the external locking nut. The end of the internal locking nut away from the external locking nut can abut against a protruding boss on the outer circumferential surface of the sub-shell. The adjacent ends of the external locking nut and the internal locking nut can abut against each other and lock together.

Images