A tension fixture

Abstract

This utility model relates to the field of welding equipment technology, specifically to a tension fixture, comprising: a frame on which a spool for winding shape memory alloy wire is mounted, and at least two wire pressing devices disposed on one side of the spool. Each wire pressing device includes a lower pressing member and a wire pressing plane disposed below the lower pressing member. At least two guide members are disposed between the two wire pressing devices, and a load device is disposed below the guide members. When the lower pressing member moves toward the wire pressing plane, the shape memory alloy wire is clamped between the lower pressing member and the wire pressing plane. This utility model ensures that the tension of the shape memory alloy wire passing through the guide members and the load device remains stable based on the gravity or tension of the load device.

Description

Technical Field

[0001] This utility model relates to the field of welding equipment technology, specifically to a tension fixture. Background Technology

[0002] With the development of minimally invasive medical devices and precision sensors, shape memory alloys (such as TiNi-based alloys) are often used as driving elements to connect with stainless steel structural components due to their superelasticity and deformation recovery properties. Current Braille module locking methods employ mechanical friction locking or electromagnetic locking. Mechanical friction locking requires very high material wear resistance, increases the number of structural components leading to a larger module size, and has a slow response. Electromagnetic locking requires continuous power to the module to resist user pressure, resulting in very high power consumption. Traditional soldering methods, such as soldering iron welding, generate excessively high temperatures, causing the shape memory alloy to fail instantly. Furthermore, due to the small size of Braille modules, traditional soldering is difficult to perform. Laser welding, due to its high energy release, causes a rapid increase in temperature, easily forming brittle intermetallic compounds such as TiFe2, TiCr2, and Ni3Ti at the welding point, leading to unreliable welds. Additionally, because the shape memory alloy deforms when energized (e.g., shrinking or expanding), thereby moving the locking plate in the Braille template's locking mechanism to achieve locking, it is necessary to ensure that the shape memory alloy maintains a certain tension during the welding process. In traditional welding processes, in order to ensure that the wire being welded has a certain tension, the wire is usually stretched directly using a spool, thereby maintaining a certain tension.

[0003] For example, Chinese patent document CN110756956B discloses an automatic wire feeding machine with constant tension for welding robots and its operating method. The automatic wire feeding machine includes a bobbin clamping mechanism, a wire feeding mechanism, a bobbin for loading the welding wire, and a ball screw. The bobbin is rotatably connected inside the bobbin clamping mechanism, and the ball screw is fixedly connected to the top of the bobbin clamping mechanism. The wire feeding mechanism is laterally movably connected to the ball screw. A window is provided at the top of the bobbin clamping mechanism, through which the welding wire passes sequentially. During welding, the wire feeding mechanism moves according to the change in the wire's feeding position on the bobbin, and the bobbin drive motor can actively adjust its speed according to the change in wire tension detected by the wire tension sensor to maintain a constant wire tension.

[0004] However, the patent documents mentioned above address solder wire, such as solder wire. Their wire feeding devices only have a single wire guide spool. This spool tensions the wire, maintaining a certain tension, but this tension is lost once the wire is cut. In actual manufacturing processes, batch welding is common; welding is performed on one component before moving on to the next. Therefore, it's crucial to maintain a stable tension throughout the wire feeding process. Furthermore, shape memory alloys possess a certain degree of elasticity even when not energized, i.e., in their normal state. Therefore, relying solely on the spool to apply tension introduces errors, making it impossible to guarantee the consistency of tension across the shape memory alloy wires on different components during batch welding. Utility Model Content

[0005] The purpose of this utility model is to provide a tension fixture that partially solves or alleviates the above-mentioned deficiencies in the prior art. During the welding of shape memory alloy wires, it provides a stable load to generate stable tension and can ensure the consistency of the tension of the shape memory alloy wires welded on each component during batch welding to a certain extent.

[0006] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution: A tension fixture includes: a frame, on which a spool for winding shape memory alloy wire is disposed, and at least two wire pressing devices are disposed on one side of the spool; The pressing device includes: a lower pressing member and a pressing plane disposed below the lower pressing member; at least two guide members are disposed between the two pressing devices; and a load device is disposed below the guide members. The load device includes: a fixing member, the fixing member having a guide groove, a load member that can move up and down along the guide groove, and the load member having a mating groove that mates with the shape memory alloy wire; or, the load device includes: a drive module, and a telescopic component connected to the drive module, the free end of the telescopic component having a wire-passing hole for the shape memory alloy wire to pass through. The shape memory alloy wire drawn from the drum passes sequentially through the pressure plane near the drum, the guide and the load, until it is sent to the welding station after moving away from the pressure plane of the drum. As the pressing member moves toward the pressure line plane, the shape memory alloy wire is clamped between the pressing member and the pressure line plane; When the drum is rotated, causing the shape memory alloy wire to move the load member upward from the first extreme position to any height and suspend the load member, or to the second extreme position, the shape memory alloy wire remains under a preset tension; or... When the drum is rotated, causing the shape memory alloy wire to move the free end of the telescopic component upward from the first limit position to any height and causing the load component to be in a suspended state, or moving to the second limit position, the shape memory alloy wire is always in a preset tension state.

[0007] Furthermore, the guide component is a pulley, which is fixed to the frame by a support rod.

[0008] Furthermore, the load-bearing component has a dumbbell-shaped structure, the mating groove is located in the middle of the dumbbell-shaped structure, and the shape memory alloy wire is wound in the mating groove.

[0009] Furthermore, the drum is connected to a power device that drives the drum to rotate.

[0010] Furthermore, the fastener includes: a first body arranged symmetrically, and a second body vertically connecting the two first bodies, the second body being fixed on the frame, and each first body having the guide groove formed along the axial direction.

[0011] Furthermore, the fixing member has a limiting member at one end near the guide member; or, the fixing member has a limiting member slidably disposed on it.

[0012] Furthermore, clamping members are provided on both sides of the fixing member, and the clamping members are fixed on the frame.

[0013] Furthermore, the wire pressing device also includes: a wire pressing table, wherein a groove is provided on the wire pressing table, and the wire pressing plane is disposed on the bottom of the groove; The lower pressing component includes: a pressing post that can move up and down relative to the pressing plane; When the pressure post moves downward along the axial direction to the pressure plane, the pressure post presses the shape memory alloy wire against the pressure plane.

[0014] Furthermore, the end of the pressure post near the pressure plane is provided with a bottom plane, the bottom plane is provided with a slot for engaging the shape memory alloy wire, and the slot is provided with anti-slip texture.

[0015] Furthermore, the power unit is configured as a motor, and the drum is mounted on the output shaft of the motor.

[0016] Beneficial effects: Existing tensioning devices are designed for welding wires, while this application targets shape memory alloy wires. Furthermore, the welding process does not require additional welding wire, such as solder wire; instead, the shape memory alloy wire is welded onto a stainless steel locking plate (typically, the locking plate has multiple welding points spaced along its central axis for welding the shape memory alloy wire, such as…). Figure 10 Furthermore, each welding point on the locking piece is equipped with a gripper for holding and wrapping the shape memory alloy wire. During welding, an electric field is directly applied to the gripper without the need for additional solder wire. This invention ensures that the tension of the shape memory alloy wire passing through the guide and load device remains stable based on the gravity or tension of the load device. For example, the shape memory alloy wire is pulled out from the spool, passes through the guide and load, and then passes through the wire pressing device. During welding, the first wire pressing device presses the wire, thereby applying a stable force to the wire through the load device, thus maintaining a stable tension. When the shape memory alloy wire needs to be cut after welding, the second wire pressing device presses the shape memory alloy wire to prevent the cut wire from becoming tangled and hindering the welding of the next locking piece.

[0017] This invention allows the load component to move within a guide groove, ensuring that the load component moves along a specific spatial direction and preventing it from swinging arbitrarily during its ascent, thus keeping the tension direction of the shape memory alloy wire stable at all times.

[0018] This invention has a simple structure. By rationally arranging the guide components, load devices, and wire pressing devices on the frame, it makes full use of the spatial relationship to ensure that the tension of the shape memory alloy wire remains stable during welding. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of one embodiment of the tension fixture of this utility model; Figure 2 This is an exploded view of the present invention; Figure 3 This is the front view of the present invention; Figure 4This is a top view of the present invention; Figure 5 This is the left view of the present invention; Figure 6 This is a three-dimensional structural view of the present invention; Figure 7 This is a structural schematic diagram of the load-bearing component of this utility model when it is in the first extreme position; Figure 8 This is a structural schematic diagram of the load-bearing component of this utility model when it is in the second extreme position; Figure 9 This is a structural schematic diagram showing the positional relationship between the guide member and the load member in another embodiment of the tension fixture of this utility model; Figure 10 This is a schematic diagram showing how the tension fixture of this invention is used to assist in welding shape memory alloy wires onto a locking plate.

[0021] Summary of attached labeling and identification: 1. Drum; 2. Power unit; 3. Pressing component; 4. Pressing plane; 5. Support rod; 6. Guide component; 7. Clamping component; 8. Fixing component; 9. Loading component; 10. Limiting component; 11. Frame; 81. First body; 82. Second body; 100. Locking plate; 101. Gripper; 102. Shape memory alloy wire. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0023] In this document, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" can be used interchangeably.

[0024] In this document, the terms "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In this document, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," and "connected," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0026] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0027] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0028] The locking piece 100, as a key actuator of the locking mechanism in the Braille display device, needs to achieve precise locking action under the drive of the shape memory alloy wire 102 (such as TiNi wire). Figure 10 As shown, the shape memory alloy wire 102 needs to be laid along the central axis of the locking plate 100. When the shape memory alloy wire 102 deforms under energization, it can drive the locking plate 100 to move. Furthermore, multiple welding points are spaced apart along the central axis of the locking plate 100, which is equivalent to the shape memory alloy wire 102 forming multiple points of fixation with the locking plate 100, ensuring that the driving force of the shape memory alloy wire 102 can be evenly transmitted to the locking plate 100, thus ensuring a linear response of the locking action. Each welding point is provided with a clamp 101 for holding and wrapping the shape memory alloy wire, and an electric field is directly applied to the clamp 101 during welding. Since the TiNi wire diameter is only 0.03mm and has a certain degree of elasticity in the non-energized state, ensuring the tension of the shape memory alloy wire between each welding point is very important during the welding process. The tension fixture provided in this application is used to assist in welding the shape memory alloy wire on the locking plate, specifically, to provide a relatively stable tension to the shape memory alloy wire.

[0029] Example 1: As Figure 1 and Figure 8 As shown, this embodiment provides a tension fixture, including: a frame 11, on which a spool 1 for winding shape memory alloy wire 102 is provided, and at least two wire pressing devices are provided on the frame 11, the wire pressing devices being located on the same side of the spool 1.

[0030] In some embodiments, the crimping device includes: a lower pressing member 3, and a crimping plane 4 disposed below the lower pressing member 3, at least two guide members 6 are disposed between the two crimping devices, and a load device is disposed below the guide member 6.

[0031] Specifically, the guide 6 is a pulley, which is fixed to the frame 11 by a support rod 5. The shape memory alloy wire is wound around the pulley, and the direction of the shape memory alloy wire is changed by the pulley; and multiple guides 6 can be provided as needed.

[0032] In some embodiments, the load device includes: a fixing member 8, a guide groove provided on the fixing member 8, a load member 9 that moves up and down along the guide groove provided in the guide groove, and a mating groove provided on the load member 9 that mates with the shape memory alloy wire.

[0033] Preferably, the fixing member 8 includes: symmetrically arranged first bodies 81, and a second body 82 vertically connected to the two first bodies 81. The second body 82 is fixed on the frame 11, and each first body 81 has a guide groove along the axial direction. The guide groove allows the load to move in a specific spatial direction, preventing the load from swinging randomly during the upward movement, which would affect the stability of the shape memory alloy wire tension.

[0034] In some embodiments, the fixing member 8 is provided with a limiting member 10 at one end near the guide member 6. The opening end of the first body of the fixing member (the end near the guide member) is provided with a limiting member to prevent the load member from sliding out of the guide groove.

[0035] In some embodiments, clamping members 7 are provided on both sides of the fixing member 8, and the clamping members 7 are fixed to the frame 11. The clamping members are provided to fix the fixing member.

[0036] Preferably, two guide members are provided above the load device, and the distance between the two guide members is equal to the width of the mating groove on the load member, so that the shape memory alloy wires passing around both sides of the mating groove on the load member are parallel to each other. See [reference needed] Figure 3 At this point, the load component only needs to remain suspended within the guide groove, without contacting the bottom end, to maintain stable tension in the shape memory alloy wire. For example, when the load component has a circular structure, the shape memory alloy wire forms a U-shape as it passes over the guide component and the load component, such as... Figure 3 As shown. This method ensures that a stable external force is always applied to the shape memory alloy wire.

[0037] In practical industrial applications, different customers may require applying varying tensions to shape memory alloy wires due to differing quality requirements. This can be addressed by providing load devices of different specifications. For example, for applications requiring higher tension, a heavier load and a matching fastener (i.e., a guide groove that aligns with the load) can be provided; conversely, for applications requiring lower tension, a lighter load and a matching fastener can be provided.

[0038] In other embodiments, the load device includes a drive module and a telescopic component connected to the drive module. The free end of the telescopic component has a threading hole for the shape memory alloy wire to pass through. Preferably, the drive module is a hydraulic cylinder or a pneumatic cylinder, and the telescopic component is the push rod of the hydraulic cylinder or pneumatic cylinder, with the end of the push rod away from the hydraulic cylinder or pneumatic cylinder being the free end. In specific implementation, the shape memory alloy wire passes through one of the two symmetrically arranged pulleys on the top of the load device, closer to the drum, then through the threading hole on the telescopic component, and then through the other of the two symmetrically arranged pulleys.

[0039] In this embodiment, due to the symmetrical arrangement of the two guide members, and the fact that the threads on both sides of the load member are parallel to each other, the tension of the threads remains stable regardless of how high the load member rises, provided that the weight of the load member remains constant. Of course, the load member with the corresponding weight can be selected in advance according to the required tension.

[0040] Preferably, a pressing device is provided on each side of the load device, and the load member is located on the vertical line between two symmetrically arranged guide members (or first guide members). A second guide member is also provided between the pressing device away from the drum and the two first guide members. The height of the second guide member is lower than the height of the first guide members, the height of the first guide members is greater than the height of the pressing plane of the pressing device closer to the drum, and the height of the pressing plane of the pressing device away from the drum is the same as or slightly higher than the height of the second guide member. By providing guide members, the direction of the shape memory alloy wire is changed, and simultaneously, in conjunction with the pressing device, a stable tension is generated in the shape memory alloy wire.

[0041] This embodiment makes full use of the spatial relationship through the arrangement of various guide components, load devices and wire pressing devices on the frame, so that the tension of the shape memory alloy wire remains stable during the welding of the shape memory alloy wire.

[0042] The working principle of this device during shape memory alloy wire welding: The shape memory alloy wire is pulled out from the drum 1, and passes sequentially through the pressure plane 4 near the drum 1, the first guide, the load device, and the second guide, until it is fed into the welding station after moving away from the pressure plane 4 of the drum 1; at this time, the load device is at the bottom of the guide groove, i.e. Figure 7 At the first extreme position shown; After the first weld point is completed, and the free end of the shape memory alloy wire 102 is welded to the workpiece, the drum 1 rotates (either manually or driven by the power module). The shape memory alloy wire is pulled and drives the load member 9 to move upward along the guide groove. When the load member 9 moves to any height, causing it to suspend, or moves to the top of the guide groove (i.e.,...), the load member 9 is pulled upward. Figure 8 When the second extreme position is shown, stop rotating the drum and move the lower pressure member 3 on the side closer to the drum 1 toward the pressure plane 4, thereby clamping the shape memory alloy wire between the lower pressure member 3 and the pressure plane 4. At this time, the shape memory alloy wire on the other side is welded.

[0043] When the shape memory alloy wire welding is completed and it needs to be cut (for example, when all welding points on a locking piece have been completed), first move the lower pressure member 3 away from the drum 1 towards the pressure plane 4. The shape memory alloy wire at this point is clamped, and then the shape memory alloy wire is cut. The shape memory alloy wire is kept under tension due to the combined action of the load device and the lower pressure device. When it is necessary to continue welding the next workpiece, move the two lower pressure members 3 away from the corresponding pressure plane 4, and then pull the shape memory alloy wire to the target position to weld the first welding point.

[0044] In this embodiment, when the drum 1 is rotated, the shape memory alloy wire drives the load member 9 to move upward from the first extreme position to any height, causing the load member to suspend, or when it moves to the second extreme position, the shape memory alloy wire is always in a preset tension state; or, When the drum 1 is rotated, causing the shape memory alloy wire to move the free end of the telescopic component upwards to any height from the first limit position to suspend the load component, or to move to the second limit position, the shape memory alloy wire is always in a preset tension state.

[0045] In this embodiment, the second extreme position refers to the end of the guide groove of the fixing member closer to the guide member (the top position of the fixing member), and the first extreme position refers to the end of the guide groove of the fixing member farther from the guide member (the bottom position of the fixing member). Preferably, the first and second extreme positions are preset according to the required tension magnitude. Specifically, the tension magnitude and the height between the first and second extreme positions can be obtained through simulation.

[0046] In some embodiments, the load member 9 has a dumbbell-shaped structure, the mating groove is located in the middle of the dumbbell-shaped structure, and the shape memory alloy wire is wound in the mating groove.

[0047] In some embodiments, the wire pressing device further includes: a wire pressing table, the wire pressing table having a groove, the wire pressing plane being disposed on the bottom of the groove, and the lower pressing member 3 including: a wire pressing post, the wire pressing post being movable up and down relative to the wire pressing plane 4; When the pressure post moves downward along the axial direction to the pressure plane 4, the pressure post presses the shape memory alloy wire against the pressure plane 4.

[0048] In some embodiments, the end of the pressure post near the pressure plane has a bottom plane, and the bottom plane has a groove for engaging the shape memory alloy wire, with anti-slip texture inside the groove. This groove ensures that the shape memory alloy wire is more stable on the pressure plane when the pressure post abuts against it.

[0049] Specifically, the guide 6, the pressure plate, the lower pressure member 3, and the support rod 5 are fixed to the frame 11 by bolts.

[0050] In some embodiments, the drum 1 is connected to a power device 2 that drives the drum 1 to rotate.

[0051] Specifically, the power unit 2 is a motor, and the drum is mounted on the output shaft of the motor.

[0052] In practical industrial applications, providing load devices of different specifications not only requires manual equipment replacement but also necessitates manufacturers to equip themselves with load devices of various specifications. This increases costs, and the higher idle rate of less frequently used load devices further increases hidden costs. Therefore, in some embodiments, the distance between the two first guide members above the load member is relatively large (e.g., much larger than the width of the load member; preferably, the distance L1 between them is 2-4 times the diameter D1 of the circular load member; of course, if...). Figure 9 The load member 9 shown has a square cross-section, and correspondingly, L1 is larger than the side length of the square, thus causing the shape memory alloy wire passing through the two first guide members and the load member to form a V-shape. Different forces are applied to the shape memory alloy wire when the load member is lifted to different heights. See [link to relevant documentation]. Figure 9 .

[0053] Preferably, the required heights for various tensions are determined in advance through numerous experiments or simulations (or, by calculating the forces corresponding to different heights using the included angle between the triangle formed by the two positioning members and the load member and the magnitude of the load member's weight; this principle is existing technology and will not be elaborated here). Corresponding height and force magnitude scales are then set at appropriate positions on the fixing member. (Generally, since the types of locking plates (preferably made of SUS304 stainless steel) are limited in Braille display devices, the required tension levels are also limited. Therefore, the height values ​​corresponding to different forces are reasonably allocated based on the maximum movable distance Hmax of the limiting member 10 in the height direction of the fixing member). In practice, the required tension magnitude or corresponding height can be determined in advance. Then, the limiting member 10, which can slide up and down along its height, is slid to the corresponding height on the fixing member. The load member can then be raised to the corresponding height by pulling the shape memory alloy wire. Of course, the limiting member 10 is also fixed at the corresponding height by fasteners (such as screws, and correspondingly, screw holes that cooperate with the screws are provided at the corresponding positions) to prevent it from shifting.

[0054] Of course, in order to facilitate the lifting and lowering of the V-shaped shape memory alloy wire, the two sides of the fixing member 8 are open spaces (for example, the space between the two symmetrically arranged first bodies 81 is left for the lifting and lowering of the shape memory alloy wire).

[0055] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0056] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A tension fixture, characterized in that, include: A frame (11) is provided with a spool (1) for winding shape memory alloy wire (102), and at least two wire pressing devices are provided on the frame (11), the wire pressing devices being located on one side of the spool (1); The pressing device includes: a lower pressing member (3) and a pressing plane (4) disposed below the lower pressing member (3), at least two guide members (6) are disposed between the two pressing devices, and a load device is disposed below the guide member (6); The load device includes: a fixing member (8), a guide groove is provided on the fixing member (8), a load member (9) that can move up and down along the guide groove is provided in the guide groove, and a mating groove is provided on the load member (9) that cooperates with the shape memory alloy wire (102); or, the load device includes: a drive module and a telescopic component connected to the drive module, and a wire hole is provided at the free end of the telescopic component for the shape memory alloy wire (102) to pass through. The shape memory alloy wire (102) pulled out from the drum (1) passes sequentially through the pressure plane (4) close to the drum (1), the guide (6) and the load member (9) until it is far away from the pressure plane (4) of the drum (1) and then sent to the welding station; When the pressing member (3) moves toward the pressure plane (4), the shape memory alloy wire (102) is clamped between the pressing member (3) and the pressure plane (4); When the spool (1) is rotated, causing the shape memory alloy wire (102) to move the load member (9) upward from the first extreme position to any height and making the load member (9) suspended, or when it moves to the second extreme position, the shape memory alloy wire (102) is always in a preset tension state; or, When the spool (1) is rotated, causing the shape memory alloy wire (102) to move the free end of the telescopic component from the first limit position to any height and causing the load member (9) to be in a suspended state, or to move to the second limit position, the shape memory alloy wire (102) is always in a preset tension state.

2. The tension fixture according to claim 1, characterized in that, The guide (6) is a pulley, which is fixed to the frame (11) by a support rod (5).

3. The tension fixture according to claim 1, characterized in that, The load member (9) has a dumbbell-shaped structure, the mating groove is located in the middle of the dumbbell-shaped structure, and the shape memory alloy wire (102) is wound in the mating groove.

4. The tension fixture according to claim 1, characterized in that, The drum (1) is connected to a power device (2) that drives the drum (1) to rotate.

5. The tension fixture according to claim 1, characterized in that, The fastener (8) includes: a first body (81) arranged symmetrically, and a second body (82) vertically connecting the two first bodies (81). The second body (82) is fixed on the frame (11), and each first body (81) is provided with the guide groove along the axial direction.

6. The tension fixture according to claim 1, characterized in that, The fixing member (8) is provided with a limiting member (10) at one end near the guide member (6); or, the limiting member (10) is slidably provided on the fixing member (8).

7. The tension fixture according to claim 1, characterized in that, The fastener (8) is provided with clamping parts (7) on both sides, and the clamping parts (7) are fixed on the frame (11).

8. The tension fixture according to claim 1, characterized in that, The wire pressing device further includes: a wire pressing table, a groove is provided on the wire pressing table, and the wire pressing plane (4) is provided on the bottom of the groove; The lower pressure member (3) includes: a pressure post that can move up and down relative to the pressure plane (4); When the pressure post moves downward along the axial direction to the pressure plane (4), the pressure post presses the shape memory alloy wire (102) against the pressure plane (4).

9. The tension fixture according to claim 8, characterized in that, The end of the pressure post near the pressure plane (4) is provided with a bottom plane, the bottom plane is provided with a slot for engaging the shape memory alloy wire (102), and the slot is provided with anti-slip texture.

10. The tension fixture according to claim 4, characterized in that, The power unit (2) is a motor, and the drum (1) is mounted on the output shaft of the motor.

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