Double-finger mechanical clamping jaw based on shape memory alloy

Abstract

According to the double-finger mechanical clamping jaw based on the shape memory alloy, the SMA material is creatively applied to a clamping device. The SMA wire is deflected multiple times through the multiple fixed pulleys to drive the driving gear to rotate to drive the transmission connecting arm to rotate, then the clamping jaw is driven to be opened and closed, the opening width equivalent to that of a traditional clamping jaw is achieved, meanwhile, the overall installation space and structural mass of the clamping jaw are remarkably reduced, and a larger operation range and a lighter load are provided for the technical field of automation. In addition, the device adopts the combination of gear transmission and a lever arm, the transmission mechanism enables the mechanical clamping jaw to achieve large motion conversion, and the compactness of the structure is further improved. The opening width can be adjusted by adjusting the size and the tooth number of the gear according to the actual use requirement, meanwhile, clamping fingers of different shapes can be installed on the clamping finger joints, the adaptability and adjustability of the whole device are improved, and the requirements of different clamping scenes are met.

Description

Technical Field

[0001] The invention belongs to the field of gripper control, and in particular relates to a two-finger mechanical gripper based on shape memory alloy. Background Art

[0002] With the development of industrial automation technology, shape memory alloys (SMA) are widely used in the development of new gripping devices due to their high energy density. SMA can autonomously return to its original shape under thermal activation, which makes it potential in the manufacture of small, lightweight and energy-efficient actuators.

[0003] There are micro clamping devices on the market, but such clamping devices are still in the research stage. It is difficult for clamping devices to take into account both the structure and the opening and closing width. Clamping devices usually have limited opening and closing widths, while clamping devices with sufficient opening and closing widths have large structures and heavy weights. Therefore, a clamping device that can take into account both the installation space and the opening and closing width is needed to solve the actual needs in production. Summary of the invention

[0004] The object of the present invention is to provide a two-finger mechanical gripper based on shape memory alloy to solve the problem that the clamping device in the prior art is difficult to take into account both the installation space and the opening and closing width.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A two-finger mechanical gripper based on shape memory alloy, comprising a gripper and a mechanical transmission system arranged on a mounting plate;

[0007] The mechanical transmission system includes a winding fixed block, an SMA winding, a plurality of fixed pulleys, a torsion spring, a lever arm, a driving gear, a first driven gear, and a second driven gear;

[0008] The winding fixing block is arranged on the rear side of the mounting plate, the driving gear is rotatably arranged in the middle of the mounting plate through the rotating shaft, a lever arm is fixedly sleeved in the middle of the rotating shaft, a torsion spring is sleeved at the bottom of the rotating shaft, one end of the torsion spring is fixedly connected to the mounting plate, and the other end is fixedly connected to the lever arm;

[0009] The plurality of fixed pulleys are distributed along the circumference of the driving gear; one end of the SMA winding is fixedly wound inside the winding fixed block as a fixed end, and the other end of the SMA winding is a movable end that passes through each fixed pulley in turn and is finally fixedly connected to the lever arm;

[0010] The SMA winding can output torque to the lever arm through its own deformation to make the lever arm rotate, thereby driving the driving gear to rotate;

[0011] A first driven gear and a second driven gear are arranged in parallel and rotatably on the front part of the mounting plate along the length direction, and the first driven gear and the second driven gear have the same shape and mesh with each other;

[0012] The first driven gear is also meshed with the driving gear, and the module of the first driven gear is smaller than that of the driving gear;

[0013] The central axes of the first driven gear and the second driven gear are respectively fixedly connected to one end of the first transmission connecting arm and the second transmission connecting arm; the clamping claw comprises a pair of clamping fingers, the front part of the clamping fingers is used as a clamping part, and the rear part is used as a connecting part, and the other ends of the first transmission connecting arm and the second transmission connecting arm are respectively rotatably connected to the connecting parts of the pair of clamping fingers;

[0014] The driving gear, the first driven gear, the second driven gear, the first transmission connecting arm, the second transmission connecting arm and a pair of clamping fingers all rotate in a horizontal plane.

[0015] The present invention also has the following features:

[0016] Furthermore, it also includes a third transmission connecting arm and a fourth transmission connecting arm;

[0017] The third transmission connecting arm and the fourth transmission connecting arm are respectively arranged in parallel on the left and right sides of the first driven gear and the second driven gear as a whole;

[0018] The two ends of the third transmission connecting arm and the fourth transmission connecting arm are rotatably connected to the mounting plate and the corresponding clamping fingers respectively.

[0019] Furthermore, the opening width of the clamping jaws is greater than 40 mm.

[0020] Furthermore, a cover plate is arranged on the mounting plate, and the mechanical transmission system is arranged inside the cover plate.

[0021] Furthermore, it also includes a cooling device, and the output end of the cooling device is close to the SMA winding.

[0022] Compared with the prior art, the present invention has the following technical effects:

[0023] The two-finger mechanical gripper based on shape memory alloy of the present invention creatively applies SMA material to the clamping device. The high energy density provided by the SMA material enables the mechanical gripper to complete a large amount of work with a small size and light weight, which is difficult to match with traditional electric or pneumatic grippers.

[0024] Secondly, by deflecting the SMA wire multiple times through multiple fixed pulleys, the active gear is driven to rotate, which drives the transmission connecting arm to rotate, and then drives the clamping jaw to open and close, achieving an opening width equivalent to that of the traditional clamping jaw. At the same time, the overall installation space and structural mass of the clamping jaw are significantly reduced, providing a larger operating range and lighter load for the field of automation technology.

[0025] In addition, the device adopts a combination of gear transmission and lever arm. This transmission mechanism enables the mechanical gripper to achieve a larger motion conversion, further improving the compactness of the structure. The opening width can be adjusted by adjusting the size and number of teeth of the gear according to actual use needs. At the same time, different shapes of grippers can be installed on the gripper joints, which improves the adaptability and adjustability of the overall device to meet the needs of different gripping scenarios.

[0026] In general, the shape memory alloy-based two-finger mechanical gripper of the present invention integrates the high-efficiency energy density of shape memory alloy (SMA), realizes a large opening width of the gripper, a compact transmission mechanism to optimize the structural installation space, and a high degree of adaptability and adjustability. It can take into account both the installation space and the opening and closing width, has breakthrough performance and broad application potential in the field of automation technology, and is suitable for large-scale use and promotion in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the two-finger mechanical gripper based on shape memory alloy of the present invention;

[0028] Figure 2 It is a working principle diagram of the torsion spring in the present invention;

[0029] Figure 3 It is a front view of the two-finger mechanical gripper based on shape memory alloy of the present invention;

[0030] Figure 4 It is a left view of the two-finger mechanical gripper based on shape memory alloy of the present invention;

[0031] Figure 5 It is a schematic diagram of the opening and closing process of the two-finger mechanical gripper based on shape memory alloy of the present invention.

[0032] The meaning of the symbols in the figure is:

[0033] 1. Mounting plate; 2. Winding fixing block; 3. SMA winding; 4. Fixed pulley; 5. Torsion spring; 6. Lever arm; 7. Driving gear; 8. First driven gear; 9. Second driven gear; 10. First transmission connecting arm; 11. Second transmission connecting arm; 12. Clamping finger; 13. Third transmission connecting arm; 14. Fourth transmission connecting arm; 15. Cover plate. DETAILED DESCRIPTION

[0034] It should be noted that, unless otherwise specified, all components in the present invention are components known in the prior art, such as the clamping jaws that are commonly used.

[0035] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0036] A two-finger mechanical gripper based on shape memory alloy, such as Figures 1 to 5 As shown, it includes a clamping jaw and a mechanical transmission system arranged on a mounting plate 1;

[0037] The mechanical transmission system includes a winding fixed block 2, an SMA winding 3, a plurality of fixed pulleys 4, a torsion spring 5, a lever arm 6, a driving gear 7, a first driven gear 8 and a second driven gear 9;

[0038] The winding fixing block 2 is arranged on the rear side of the mounting plate 1, and the driving gear 7 is rotatably arranged in the middle of the mounting plate 1 through the rotating shaft. A lever arm 6 is fixedly installed on the rotating shaft, and a torsion spring 5 is sleeved at the bottom of the rotating shaft. One end of the torsion spring 5 is fixedly connected to the mounting plate 1, and the other end is fixedly connected to the lever arm 6;

[0039] A plurality of fixed pulleys 4 are distributed along the circumference of the driving gear 7;

[0040] One end of the SMA winding 3 is fixedly wound inside the winding fixed block 2 as a fixed end, and the other end of the SMA winding 3 is wound around each fixed pulley 4 in turn as a movable end and fixedly connected to the lever arm 6; the SMA winding 3 can output torque to the lever arm 6 through its own deformation to rotate the lever arm 6 and drive the driving gear 7 to rotate;

[0041] Two first driven gears 8 and a second driven gear 9 are arranged in parallel and rotatably arranged in the front of the mounting plate 1 and distributed along the length direction. The first driven gear 8 and the second driven gear 9 have the same shape and mesh with each other.

[0042] The first driven gear 8 is also meshed with the driving gear 7, and the module of the first driven gear 8 is smaller than that of the driving gear 7;

[0043] The central axes of the first driven gear 8 and the second driven gear 9 are respectively fixedly connected to one end of the first transmission connecting arm 10 and the second transmission connecting arm 11; the clamping jaws include a pair of clamping fingers 12, the front of the clamping fingers 12 is used as a clamping part, and the rear is used as a connecting part, and the other ends of the first transmission connecting arm 10 and the second transmission connecting arm 11 are respectively rotatably connected to the connecting parts of the pair of clamping fingers 12;

[0044] The driving gear 7, the first driven gear 8, the second driven gear 9, the first transmission connecting arm 10, the second transmission connecting arm 11 and the pair of clamping fingers 12 all rotate in a horizontal plane.

[0045] In actual use, a plurality of fixed pulleys 4 form a winding path, and the number and specific positions of the fixed pulleys are determined according to actual use requirements. Those skilled in the art can design them according to the knowledge in this field, and this embodiment will not be described in detail.

[0046] The SMA winding 3 is connected to both ends of the winding path, one end is a fixed clamping end, and the other end is a movable free end. At the fixed clamping end, the SMA winding 3 is fixed inside the winding fixing block 2.

[0047] In this embodiment, the SMA winding 3 is fixed in the deflection path by four fixed pulleys 4 respectively. At the movable free end, the SMA winding 3 is port-connected by a lever arm 6. The lever arm 6 transmits the input force of the SMA winding 3 as torque and transmits it to the driving gear 7. A torsion spring 5 is installed under the driving gear 7 to reset the shape memory alloy effect and automatically close the clamp. Starting from the driving gear 7, the transmission is first transmitted to the first driven gear 8, and the first driven gear 8 is transmitted to the second driven gear 9 at a ratio of 1:1, and finally acts on the clamping finger at the other end.

[0048] The clamping jaw can adjust the opening and closing width of the clamping fingers 12 by adjusting the size and number of teeth of the first driven gear 8 and the second driven gear 9 .

[0049] As a specific implementation manner, one end of the two connecting arms is respectively embedded in the middle of the corresponding first driven gear 8 and the second driven gear 9, and the other end is connected to the corresponding clamping finger 12 joint.

[0050] The clamping jaws can have different shapes of clamping fingers, so that the shape of the clamping jaws fits the object to be clamped.

[0051] If the SMA winding wire generates mechanical fatigue due to stretching during its service life, it is re-tensioned and fixed inside the winding fixing block 2 .

[0052] The specific working principle of the two-finger mechanical gripper based on shape memory alloy in this embodiment is as follows:

[0053] Since SMA materials have a shape memory effect, that is, they can recover to a predetermined shape from seemingly permanent plastic deformation after thermal or mechanical activation, based on the phase change inside the material, that is, the diffusion-free phase transition between martensite (low-temperature phase) and austenite (high-temperature phase). SMA is activated by applying voltage to generate Joule heat, induction or high-temperature ambient medium, so that it changes from martensite to austenite, thereby achieving a length change (up to 8% telescopic length). During the cooling process, the material is restored to martensite by an external reaction force (such as a spring or additional weight), completing the shape memory process.

[0054] According to the above principles, the mechanical clamp and mechanical transmission system in this embodiment convert the small stroke generated by the SMA winding 3 into a large opening width between the two clamping fingers 12 of the clamp through a gear train and a lever arm. When the SMA winding 3 is activated, it will generate an output force, which transmits torque to the active gear 7 through the lever arm 6 to counteract the torque generated by the torsion spring 5. The active gear 7 transmits the torque to the first driven gear 8, and the first driven gear 8 transmits the torque to the corresponding first transmission connecting arm 10 to open the clamp. When the mechanical clamp needs to be closed, the effect of the SMA winding 3 is disabled, and the output force gradually decreases until it reaches 0N, resulting in a change in the direction of the torque and the clamp is closed. The opening and closing time of the clamp depends on the activation speed and cooling speed of the SMA winding.

[0055] As a preferred solution, a main power supply is further provided, which increases the input voltage to the SMA winding 3 so as to accelerate the activation of the SMA winding 3 .

[0056] As a preferred solution, a cooling device is provided on the outer side of the two-finger mechanical gripper based on shape memory alloy, and the output end of the cooling device is close to the SMA winding 3.

[0057] As a specific implementation, the cooling device uses a fan, which can accelerate the cooling time of the SMA winding 3 and thus significantly reduce the closing time of the clamping jaws.

[0058] As a preferred solution, it further includes a third transmission connecting arm 13 and a fourth transmission connecting arm 14;

[0059] The third transmission connecting arm 13 and the fourth transmission connecting arm 14 are respectively arranged in parallel on the left and right sides of the first driven gear 8 and the second driven gear 9;

[0060] The third transmission connecting arm 13 and the fourth transmission connecting arm 14 are respectively rotatably connected to the mounting plate 1 and the corresponding clamping fingers 12. This arrangement can enhance the stability during rotation.

[0061] Furthermore, the opening width of the clamping jaws is greater than 40 mm.

[0062] As a preferred solution, a cover plate 15 is provided on the mounting plate 1, and the mechanical transmission system is arranged inside the cover plate 15 to protect the entire device and extend its service life.

Claims

1. A two-finger mechanical gripper based on shape memory alloy, characterized in that: It comprises a clamping claw and a mechanical transmission system arranged on a mounting plate (1); The mechanical transmission system comprises a winding fixed block (2), an SMA winding (3), a plurality of fixed pulleys (4), a torsion spring (5), a lever arm (6), a driving gear (7), a first driven gear (8) and a second driven gear (9); The winding fixing block (2) is arranged on the rear side of the mounting plate (1), the driving gear (7) is rotatably arranged in the middle of the mounting plate (1) via a rotating shaft, a lever arm (6) is fixedly sleeved in the middle of the rotating shaft, a torsion spring (5) is sleeved at the bottom of the rotating shaft, one end of the torsion spring (5) is fixedly connected to the mounting plate (1), and the other end is fixedly connected to the lever arm (6); The plurality of fixed pulleys (4) are distributed along the circumference of the driving gear (7); one end of the SMA winding (3) is fixedly wound inside the winding fixed block (2) as a fixed end, and the other end of the SMA winding (3) is wound around each fixed pulley (4) in turn as a movable end and finally fixedly connected to the lever arm (6); The SMA winding (3) can output torque to the lever arm (6) through its own deformation to cause the lever arm (6) to rotate, thereby driving the driving gear (7) to rotate; A first driven gear (8) and a second driven gear (9) are rotatably arranged in parallel along the length direction on the front portion of the mounting plate (1); the first driven gear (8) and the second driven gear (9) are of the same shape and mesh with each other; The first driven gear (8) is also meshed with the driving gear (7), and the module of the first driven gear (8) is smaller than that of the driving gear (7); The central axes of the first driven gear (8) and the second driven gear (9) are respectively fixedly connected to one end of the first transmission connecting arm (10) and the second transmission connecting arm (11); the clamping claw comprises a pair of clamping fingers (12), the front part of the clamping fingers (12) is used as a clamping part, and the rear part is used as a connecting part, and the other ends of the first transmission connecting arm (10) and the second transmission connecting arm (11) are respectively rotatably connected to the connecting parts of the pair of clamping fingers (12); The driving gear (7), the first driven gear (8), the second driven gear (9), the first transmission connecting arm (10), the second transmission connecting arm (11) and the pair of clamping fingers (12) all rotate in a horizontal plane.

2. The two-finger mechanical gripper based on shape memory alloy as claimed in claim 1, characterized in that: It also includes a third transmission connecting arm (13) and a fourth transmission connecting arm (14); The third transmission connecting arm (13) and the fourth transmission connecting arm (14) are respectively arranged in parallel on the left and right sides of the first driven gear (8) and the second driven gear (9); The third transmission connecting arm (13) and the fourth transmission connecting arm (14) are rotatably connected to the mounting plate (1) and the corresponding clamping fingers (12) at both ends.

3. The two-finger mechanical gripper based on shape memory alloy as claimed in claim 1, characterized in that: The opening width of the clamping jaws is greater than 40 mm.

4. The two-finger mechanical gripper based on shape memory alloy as claimed in claim 1, characterized in that: The mounting plate (1) is provided with a cover plate (15), and the mechanical transmission system is provided on Inside the cover plate (15).

5. The two-finger mechanical gripper based on shape memory alloy as claimed in claim 1, characterized in that: It also includes a cooling device, wherein the output end of the cooling device is close to the SMA winding (3).

Images