Soft pneumatic rigidity-variable finger structure, curing mold and manufacturing process

Abstract

The invention relates to a soft pneumatic variable-rigidity finger structure, a curing mold and a manufacturing process, the finger structure comprises a vacuum negative pressure pipe which is filled with plastic particles and is provided with a first air pressure adjusting port in a matched mode, at least two air box bodies provided with second air pressure adjusting ports are arranged outside the vacuum negative pressure pipe in a winding mode, and memory alloy pieces are arranged in cooperation with the air box bodies; the curing mold comprises a first curing mold and a second curing mold; a curing mold for preparing the vacuum negative pressure pipe and the air box body is assembled, raw material liquid is injected, curing is conducted, and the vacuum negative pressure pipe is filled with plastic particles; all the bellows bodies are evenly bonded and fixed to the outer side of the vacuum negative pressure pipe, and the memory alloy pieces are arranged and fixed to the outer sides of the bellows bodies. The bending direction and rigidity changes required by the fingers under different working conditions are achieved, the flexible response during driving can be guaranteed, the structural stability can be improved under the load, the deformation degree and rigidity output are controlled through air pressure changes, the manufacturing difficulty is reduced, and the movement consistency is improved.

Description

Technical Field

[0001] This invention relates to the technical field of robotic arms and containers equipped with manipulation devices, and particularly to a soft pneumatic variable stiffness finger structure, a curing mold, and a manufacturing process. Background Technology

[0002] Pneumatic muscles are actuators that mimic biological muscles. Traditional pneumatic muscles mainly consist of an internal flexible tube and an external woven mesh for constraint, enabling contraction movements similar to human skeletal muscles. With research advancements, pneumatic muscles have become increasingly diverse in terms of structure, materials, and movement effects. For example, structures include woven, embedded, and air-chamber shapes; materials include silicone, shape memory alloys, photosensitive materials, and magnetic materials; and movement effects can include contraction, stretching, and bending. Therefore, pneumatic muscles are widely used in fields such as bionic robotics, medical rehabilitation, intelligent prosthetics, and entertainment.

[0003] Chinese Patent Publication No. CN118438424A discloses a pneumatic artificial muscle, comprising: a pneumatic muscle body, with a connector fixedly connected to it via a connecting block; a connecting assembly, including a first threaded sleeve and a second threaded sleeve threadedly connected to the outer ring of the connecting block, the first and second threaded sleeves being threadedly connected to a first threaded groove and a second threaded groove respectively, the first and second threaded grooves being located inside the pneumatic muscle connector and the connector respectively; a synchronization assembly, including a first annular block, the first annular block being fitted onto the outer ring of the connecting block, the second annular block being fixedly connected to the inner ring of the first annular block, and a linkage rod being rotatably connected inside the first annular block; and a toggle assembly, including a square block, the square block being fixedly connected to the side wall of the first threaded sleeve, the square block being connected to the inner wall of a third annular block, and the third annular block being fitted onto the outer ring of the first threaded sleeve. This invention aims to solve the problems of inconvenient assembly and disassembly and unstable connection in existing pneumatic artificial muscles.

[0004] Chinese Patent Publication No. CN112757276A discloses a negative pressure driven pneumatic artificial muscle and its preparation method. The pneumatic muscle body includes an internal skeleton, an outer covering membrane, and a sealing device. The internal skeleton is a deformable structure made of elastic material that is compressible and resilient along the axial direction. End rods are provided at both ends of the internal skeleton. The outer covering membrane wraps around the outer periphery of the internal skeleton. The sealing device is located on the end rods of the internal skeleton to seal the ends of the outer covering membrane and the internal skeleton, forming a sealing structure. The pneumatic muscle body is driven by negative pressure; by changing the negative pressure value inside the pneumatic muscle body, the contraction length of the pneumatic muscle body can be controlled. Compared with traditional positive pressure driven systems, this invention, by using negative pressure driven systems, has certain advantages in terms of movement.

[0005] However, since human fingers, especially the thumb, have different degrees of freedom than the other four fingers, fine operations such as gripping and pinching are crucial. Therefore, they need to have good flexibility and controllable stiffness. Most importantly, they need to achieve bidirectional bending. Although the above-mentioned patented technology can effectively improve the pneumatic muscle driving effect and reduce manufacturing complexity, it is still relatively complex in structure and cannot achieve the bidirectional bending function of pneumatic muscles, that is, it cannot achieve thumb-like driving. Summary of the Invention

[0006] This invention solves the problems existing in the prior art and provides a soft pneumatic variable stiffness finger structure, a curing mold and manufacturing process, especially for the thumb structure, curing mold and manufacturing process.

[0007] The technical solution adopted in this invention is a soft pneumatic variable stiffness finger structure, including a vacuum negative pressure tube, wherein the vacuum negative pressure tube is filled with plastic particles; and a first air pressure regulating port is provided in conjunction with any of the vacuum negative pressure tubes. The vacuum negative pressure pipe is equipped with at least two air boxes, all of which are independent and arranged around the outside of the vacuum negative pressure pipe; each of the air boxes is equipped with a second air pressure regulating port. All of the bellows bodies are equipped with one or more shape memory alloy sheets, which are used to drive the finger structure back to its initial shape by utilizing the shape memory effect after the external air pressure is released.

[0008] Preferably, there are two bellows bodies, and the two bellows bodies are symmetrical about the central axis of the vacuum negative pressure pipe.

[0009] Preferably, the bellows body includes at least two vertebral segments, adjacent vertebral segments are connected by elastic recesses, and the two end vertebral segments are elastically connected to a vacuum negative pressure pipe; all the protruding ends of the vertebral segments are sequentially covered with a membrane layer.

[0010] Preferably, shape memory alloy sheets are provided on the outer membrane of the protruding ends of any two vertebral segments, and all the shape memory alloy sheets are connected sequentially.

[0011] Preferably, the vacuum negative pressure pipe and the bellows body are made of the same material.

[0012] A curing mold for the soft pneumatic variable stiffness finger structure includes a first curing mold that mates with a vacuum negative pressure tube and a second curing mold that mates with the bellows body.

[0013] Preferably, the first curing mold includes a first curing concave mold and a first curing convex mold, and the first curing concave mold and the first curing convex mold are provided with two sets of limiting grooves, and a curing core mold is provided in conjunction with the limiting grooves.

[0014] Preferably, the second curing mold includes a second curing concave mold and a second curing convex mold, with concave and convex portions on their opposite inner surfaces that match the outer wall of the wind box.

[0015] A manufacturing process for the aforementioned soft pneumatic variable stiffness finger structure includes the following steps: Assemble a curing mold for preparing a vacuum negative pressure tube, inject raw material liquid into the cavity of the assembled curing mold, and obtain a vacuum negative pressure tube after curing. Fill the vacuum negative pressure tube with plastic particles. Assemble the curing mold for the wind box body, inject the raw material liquid into the cavity of the assembled curing mold, and obtain the wind box body unit after curing. Repeat the process to make other wind box bodies until all wind box bodies are made. All the bellows bodies are evenly glued and fixed to the outside of the vacuum negative pressure tube to form the initial state of the finger structure; Shape memory alloy sheets are arranged and fixed to the outside of the air box body.

[0016] Preferably, the shape memory alloy sheet is passed through a pre-set hole on the outside of the air box or attached to its surface.

[0017] This invention relates to a soft pneumatic variable stiffness finger structure, a curing mold, and a manufacturing process. The finger structure includes a vacuum negative pressure tube filled with plastic particles and equipped with a first air pressure regulating port. At least two bellows are arranged around the outside of the vacuum negative pressure tube, and a second air pressure regulating port is provided with each bellows. One or more shape memory alloy sheets are provided with all the bellows. The curing mold for the finger structure includes a first curing mold for the vacuum negative pressure tube and a second curing mold for the bellows. The curing mold for the vacuum negative pressure tube and the bellows is assembled and prepared. Raw material liquid is injected, and after curing, the corresponding vacuum negative pressure tube and bellows unit are obtained. All bellows are repeatedly manufactured, and plastic particles are filled into the vacuum negative pressure tube. All the bellows are uniformly bonded and fixed to the outside of the vacuum negative pressure tube to form the initial state of the finger structure. The shape memory alloy sheets are arranged and fixed to the outside of the bellows.

[0018] The beneficial effects of this invention are that, through the design of a soft pneumatic structure, the bending direction and stiffness of the finger can be varied under different working conditions, ensuring a smooth response during actuation and improving structural stability under load. The construction method combining silicone material with a vacuum negative pressure tube utilizes air pressure changes to control the degree of deformation and stiffness output. Combined with an integrated molding process, this improves manufacturing precision and repeatability, reduces the difficulty of manufacturing the finger, and enhances the consistency of movement, providing a solution that is closer to physiological function for intelligent prostheses and rehabilitation equipment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the main view structure of the present invention; Figure 2 for Figure 1 A schematic diagram of the AA cross-sectional view structure; Figure 3 This is a schematic diagram of the structure of the first curing mold; Figure 4 This is a schematic diagram of the structure of the second curing mold; Figure 5 This is a schematic diagram of filling plastic particles into a vacuum negative pressure tube in this invention; Figure 6 This is a process flow diagram of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention relates to a soft pneumatic variable stiffness finger structure, comprising a vacuum negative pressure tube 1, wherein the vacuum negative pressure tube 1 is filled with plastic particles (not shown in the figure); and a first air pressure regulating port (not shown in the figure) is provided in conjunction with any of the vacuum negative pressure tubes 1. At least two air boxes 2 are provided in conjunction with the vacuum negative pressure pipe 1, and all the air boxes 2 are independent and arranged around the outside of the vacuum negative pressure pipe 1; a second air pressure regulating port 13 is provided in conjunction with any one of the air boxes 2; All of the bellows bodies 2 are equipped with one or more shape memory alloy sheets 3, which are used to drive the finger structure back to its initial shape by utilizing the shape memory effect after the external air pressure is released.

[0022] In this invention, the plastic particles filled in the vacuum negative pressure tube 1 are mainly composed of lightweight polyethylene foam. When the finger needs to increase the output torque, the air in the vacuum negative pressure tube 1 is extracted by a vacuum pump. When the vacuum negative pressure tube 1 is under negative pressure, the polyethylene foam adheres tightly to each other due to the negative pressure and no longer slides relative to each other, but locks itself together to achieve the purpose of variable stiffness. When any one of the bellows 2 (muscles) is filled with air, the inner cavity formed by each protrusion of the bellows 2 expands due to the increased pressure, and they affect each other to achieve the stretching movement. Since the other side is not filled with air, it will not stretch. This is reflected in the finger structure as a unilateral bending movement. After the action is completed, the negative pressure applied to the vacuum negative pressure tube 1 and the positive pressure applied to the bellows body 2 are removed. The shape memory alloy sheet 3 plays an auxiliary function of "returning to center". That is, when the external air pressure is released, the shape memory alloy sheet causes the soft muscles to return to their initial position due to the shape memory effect.

[0023] In this invention, the first air pressure regulating port and the second air pressure regulating port 13 are generally located at the bottom of the finger structure.

[0024] There are two air box bodies 2, and the two air box bodies 2 are symmetrical about the central axis of the vacuum negative pressure pipe 1.

[0025] The bellows body 2 includes at least two vertebral segments 4, adjacent vertebral segments 4 are connected by elastic recesses 5, and the two end vertebral segments 4 are elastically connected to the vacuum negative pressure pipe 1; all the protruding ends of the vertebral segments 4 are sequentially covered with a membrane layer 6.

[0026] Any two vertebral segments 4 have a shape memory alloy sheet 3 attached to the outside of the membrane layer 6 at their protruding ends, and all the shape memory alloy sheets 3 are connected sequentially.

[0027] In a specific implementation of the present invention, the memory alloy sheet 3 is a nickel-titanium memory alloy wire arranged axially on the outer side of the muscle, which is used to quickly return the soft pneumatic variable stiffness finger to its initial position after the movement ends, providing better motion performance.

[0028] The vacuum negative pressure pipe 1 and the air box body 2 are made of the same material.

[0029] In this invention, both the vacuum negative pressure pipe 1 and the outer wind box body 2 are made of 10-degree AB silicone. Using the same material ensures a tight bond, and the vacuum negative pressure pipe 1 is locked with foam plastic by vacuum negative pressure to achieve the function of strengthening rigidity.

[0030] The present invention also relates to a curing mold for the aforementioned soft pneumatic variable stiffness finger structure, comprising a first curing mold that mates with a vacuum negative pressure tube 1 and a second curing mold that mates with the bellows body 2.

[0031] The first curing mold includes a first curing concave mold 7 and a first curing convex mold 8. The first curing concave mold 7 and the first curing convex mold 8 are provided with two sets of limiting grooves 9, and a curing core mold 10 is provided in conjunction with the limiting grooves 9.

[0032] The second curing mold includes a second curing concave mold 11 and a second curing convex mold 12, with concave and convex portions on their opposite inner surfaces that fit the outer wall of the wind box body 2; obviously, in fact, the second curing concave mold 11 and the second curing convex mold 12 also have limiting grooves and corresponding curing core molds.

[0033] In this invention, the curing mold is made of PLA material that does not react with silicone. The curing concave mold and the curing convex mold are fixed relative to each other by a slot, and an adhesive strip is arranged at the product seam. The curing core mold 10 is fixed in the center of the mold by a limiting groove. This is the content that is easy for those skilled in the art to understand, and those skilled in the art can set it according to their needs.

[0034] This invention also relates to a manufacturing process for the aforementioned soft pneumatic variable stiffness finger structure, comprising the following steps: Assemble the curing mold for preparing the vacuum negative pressure tube 1, inject the raw material liquid (AB silicone raw material liquid) into the cavity of the assembled curing mold, and obtain the vacuum negative pressure tube 1 after curing. Fill the vacuum negative pressure tube 1 with plastic particles. Assemble the curing mold for windbox body 2, inject raw material liquid (AB silicone raw material liquid) into the cavity of the assembled curing mold, and obtain windbox body 2 monomer after curing. Repeat the process to make other windbox bodies 2 until all windbox bodies 2 are made. All the bellows bodies 2 are evenly glued and fixed to the outside of the vacuum negative pressure tube 1 to form the initial state of the finger structure; here, generally the two bellows bodies 2 are glued to the inner vacuum negative pressure tube 1 with soft glue. The shape memory alloy sheets 3 are arranged and fixed on the outside of the air box body 2.

[0035] The shape memory alloy sheet 3 is passed through a pre-set hole on the outside of the air box body 2 or attached to its surface.

[0036] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0037] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A soft body pneumatic variable stiffness finger structure, characterized by: The vacuum negative pressure tube is filled with plastic particles, and a first air pressure adjusting port is arranged on the vacuum negative pressure tube. At least two bellows are arranged on the vacuum negative pressure tube, and the bellows are independent and arranged outside the vacuum negative pressure tube. A second air pressure adjusting port is arranged on the bellows.

2. A soft pneumatic variable-stiffness finger structure according to claim 1, characterized in that: When air is filled into the bellows, the bellows are expanded and elongated, and the finger structure is bent to the other side.

3. A soft pneumatic variable-stiffness finger structure according to claim 2, wherein: One or more memory alloy pieces are arranged on the bellows to drive the finger structure to return to the initial state by the shape memory effect.

4. A soft pneumatic variable-stiffness finger structure according to claim 3, wherein: The bellows are two, and the two bellows are symmetrical to the central axis of the vacuum negative pressure tube.

5. The soft pneumatic variable-stiffness finger structure of claim 1, wherein: The bellows include at least two vertebra members, and the adjacent vertebra members are connected by elastic recesses.

6. A curing mold for a soft pneumatic variable-stiffness finger structure according to any one of claims 1 to 5, characterized by: The protruding ends of the vertebra members are sequentially covered by a film layer.

7. The curing mold of claim 6, wherein: Memory alloy pieces are arranged on the film layers of the protruding ends of any two vertebra members, and the memory alloy pieces are sequentially connected.

8. The curing mold of claim 6, wherein: The materials of the vacuum negative pressure tube and the bellows are the same.

9. A process for making a soft body pneumatic variable stiffness finger structure according to any one of claims 1 to 5, characterized in that: A first curing mold matched with the vacuum negative pressure tube and a second curing mold matched with the bellows are included. The first curing mold includes a first curing recess and a first curing protrusion, and two sets of limiting grooves are arranged on the first curing recess and the first curing protrusion. A curing core is arranged on the limiting grooves. The second curing mold includes a second curing recess and a second curing protrusion, and recesses and protrusions matched with the outer walls of the bellows are arranged on the opposite inner sides of the second curing recess and the second curing protrusion. The following steps are included:

10. The fabrication process of claim 9, wherein: A curing mold for preparing the vacuum negative pressure tube is assembled, raw material liquid is injected into the cavity of the assembled curing mold, and the vacuum negative pressure tube is obtained after curing. A curing mold for preparing the bellows is assembled, raw material liquid is injected into the cavity of the assembled curing mold, and the bellows are obtained after curing. All the bellows are uniformly adhered and fixed to the outside of the vacuum negative pressure tube to form the initial state of the finger structure. The memory alloy pieces are arranged and fixed on the outside of the bellows. The memory alloy pieces are arranged on the outside of the bellows or attached to the surface of the bellows.

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