A weight-bearing soft bionic finger and its manufacturing process

Abstract

The present invention relates to a weight-bearing soft bionic finger and a manufacturing process thereof, which is characterized in that the weight-bearing soft bionic finger comprises a skin glue layer, a negative Poisson's ratio knitted layer, a silicone resin layer and an air cavity, and is characterized in that the skin layer is the outermost layer and is in a cylindrical shape with one end closed, the inside of the skin glue layer is a negative Poisson's ratio knitted layer and a silicone resin layer, the negative Poisson's ratio knitted layer is formed into a zigzag structure by arranging positive and negative coils, the air cavity composed of square air chambers is located inside the negative Poisson's ratio knitted layer and the silicone resin layer, and the air cavity is connected to the external air cavity through a vent, and the manufacturing process comprises weaving the negative Poisson's ratio knitted layer, mold making, molding and curing and demoulding. The present invention utilizes the negative Poisson's ratio knitted layer to restrain the tensile deformation of the silicone resin layer, thereby improving the tensile strength of the bionic finger, solving the problem that the bionic finger is easily elongated and deformed when bearing weight, and can adjust the hardness and deformation degree of the bionic finger according to the different composite structures of the negative Poisson's ratio knitted layer and the silicone resin layer.

Description

Technical Field

[0001] The invention relates to the technical field of bionic robots, and in particular to a weight-bearing soft bionic finger and a manufacturing process thereof. Background Art

[0002] Bionic fingers are one of the important topics in the field of bionic robot research and are widely used in practical engineering. Bionic fingers can be divided into two categories: rigid bionic fingers and soft bionic fingers. Among them, soft bionic fingers are mostly made of soft materials. Compared with rigid fingers, they have greater freedom and can actively or passively change their own shape according to the surrounding environment. In addition, the materials of soft bionic fingers are similar to soft biological tissues, which can well simulate the movement of soft animals. They have unique advantages in the fields of movement, grasping, medical treatment and human-computer interaction. Therefore, the manipulators made of soft bionic fingers have broad application prospects in service robots, special robots, medical rehabilitation equipment and light industry.

[0003] However, most of the current soft bionic fingers use springs, yarns, rope windings, etc. as the support of the silicone resin material of the soft bionic fingers, which makes the soft bionic fingers easy to stretch and deform when loaded, limiting the load-bearing application of the soft bionic fingers and affecting the effective service life of the soft bionic fingers. Therefore, it is hoped that the anti-deformation ability of the soft bionic fingers can be improved and the application range of the soft bionic fingers can be expanded. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a weight-bearing soft bionic finger with reasonable structural design, high tensile strength, good flexibility, controllable hardness and deformation, as well as to provide a manufacturing process of the weight-bearing soft bionic finger.

[0005] The technical solution adopted by the present invention to solve the above problems is: the weight-bearing soft bionic finger includes a skin glue layer, a negative Poisson's ratio knitted layer, a silicone resin layer and an air cavity, characterized in that: the skin glue layer is the outermost layer of the bionic finger, the skin glue layer is a cylindrical shape with one end closed, the negative Poisson's ratio knitted layer and the silicone resin layer are located inside the skin glue layer, the negative Poisson's ratio knitted layer is arranged by positive and negative coils to form a zigzag tissue, the silicone resin layer and the negative Poisson's ratio knitted layer are laminated and distributed, the air cavity is located inside the negative Poisson's ratio knitted layer and the silicone resin layer, the air cavity is composed of a number of square air chambers, and the air cavity is connected to the external air cavity through a vent. The skin glue layer plays a protective role and has a shape similar to that of a human finger. The strain direction of the negative Poisson's ratio knitted layer is perpendicular to the load direction. When stretched, the negative Poisson's ratio knitted layer widens in a direction perpendicular to the stretching direction, which is used to restrain the tensile deformation of the silicone resin layer and make it stretch and expand, thereby improving the tensile strength of the bionic finger. The air cavity mainly plays the role of supporting and controlling the bending of the bionic finger. When the bionic finger needs to bend, gas is introduced into the air cavity through the vent to increase the air pressure inside the air cavity, and the square air chamber expands and gradually bends downward, thereby driving the bionic finger to bend; similarly, when the bionic finger needs to be straightened, gas is released through the vent to reduce the air pressure inside the air cavity, and the deformation of the square air chamber is restored, thereby restoring the bionic finger to the straight state.

[0006] Furthermore, the skin glue layer of the present invention is made of a silicone-based resin material with a Shore hardness of 10HA and a Young's elastic modulus of 152Ka. The skin glue layer is usually made of a high-hardness, high-elasticity material to enhance the touch and wear resistance of the bionic finger and extend its service life.

[0007] Furthermore, the negative Poisson's ratio knitted layer of the present invention is woven from carbon fiber, glass fiber and polyamide fiber / spandex coated yarn. The structure of the front and back coil loops is unbalanced during weaving, which causes the fabric to wrinkle and shrink after production and processing, forming a distinct three-dimensional effect. After folding and unfolding, the structure becomes larger, that is, the negative Poisson's ratio effect is exhibited. The more the fabric is bent, the denser the zigzag texture is, and the more obvious the negative Poisson's ratio effect is.

[0008] Furthermore, the single-layer thickness of the negative Poisson's ratio knitted layer and the silicone-based resin layer of the present invention is 1-3 mm.

[0009] Furthermore, the negative Poisson's ratio knitted layer and the silicone-based resin layer of the present invention are molded, which has high production efficiency, good product consistency and stable quality.

[0010] Furthermore, the molded composite structure of the present invention includes 1+1 type (1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone resin layer), 1+2 type (1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone resin layer + 1 layer of negative Poisson's ratio knitted layer) and 2+2 type (1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone resin layer + 1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone resin layer). By forming different composite structures of the negative Poisson's ratio knitted layer and the silicone resin layer, the hardness and deformation degree of the bionic finger can be controlled.

[0011] A manufacturing process of a weight-bearing soft bionic finger comprises the following steps:

[0012] Step 1: Weave a negative Poisson's ratio knitted layer. The specific steps are as follows:

[0013] (Ⅰ) Plate making: Use Hengqiang electronic plate making software to make patterns and weaving plates;

[0014] (II) Yarn feeding: Passive yarn feeding is adopted, and the yarn is withdrawn from the creel and led to the weaving area by the tension generated by the loop forming mechanism during weaving;

[0015] (III) Weaving: Weaving is done on a computerized flat knitting machine;

[0016] Step 2: 3D print the soft bionic finger mold. The specific steps are as follows:

[0017] (I) CAD drawing: Use CAD software to draw a three-dimensional image of the upper and lower layers of the finger mold;

[0018] (II) 3D printing: using photosensitive resin as raw material to print the mold on an industrial-grade 3D printer;

[0019] Step 3: Molding the composite structure of the negative Poisson's ratio knitted layer and the silicone-based resin layer. The specific operation steps are as follows:

[0020] (I) 1+1 type composite structure molding: a negative Poisson's ratio knitted layer is laid in the upper mold, and then a silicone resin layer is poured; the operation steps of the lower mold are the same as the upper mold, the upper mold is buckled on the lower mold, and the mold is put into an oven for curing and demoulding;

[0021] (II) 1+2 type composite structure molding: a negative Poisson's ratio knitted layer is laid in the upper mold, and then a silicone resin layer is poured, and then a negative Poisson's ratio knitted layer is laid; the operation steps of the lower mold are the same as the upper mold, the upper mold is buckled on the lower mold, and the mold is put into an oven for curing and demoulding;

[0022] (III) 2+2 type composite structure molding: a negative Poisson's ratio knitted layer is laid in the upper mold, and then a silicone resin layer is poured, and then a negative Poisson's ratio knitted layer is laid, and then a silicone resin layer is poured; the operation steps of the lower mold are the same as the upper mold, and the upper mold is buckled on the lower mold, and then put into the oven for curing and demoulding;

[0023] Step 4: Shape the skin glue layer. The specific steps are as follows:

[0024] (I) placing the composite structure prepared in step 3 into another mold with a larger cavity;

[0025] (II) injecting a silicone-based resin from the upper end of the mold so that the silicone-based resin completely covers the outer surface of the composite structure to form a skin glue layer;

[0026] (III) Place the mold in an oven for curing and demoulding.

[0027] Furthermore, in the step 1 of weaving the negative Poisson's ratio knitted layer in the manufacturing process of the present invention, the yarns are fed in parallel into the same yarn guide.

[0028] Furthermore, the 3D printing software bionic finger mold in step 2 of the manufacturing process of the present invention adopts stereolithography.

[0029] Furthermore, the oven temperature in step three of the manufacturing process of the present invention is set to 45° C., and the heating time is 1.5 hours to 2 hours.

[0030] Compared with the prior art, the present invention has the following advantages and effects: the present invention has the advantages of light weight, high strength and good flexibility of negative Poisson's ratio knitted fabric, and utilizes the performance of transverse expansion when longitudinally stretched and transverse contraction when compressed of the negative Poisson's ratio knitted layer to restrain the tensile deformation of the silicone-based resin layer, thereby improving the tensile strength of the bionic finger, solving the problem that the bionic finger is easily stretched and deformed when loaded, and can adjust the hardness and deformation of the bionic finger according to the different composite structures of the negative Poisson's ratio knitted layer and the silicone-based resin layer, and control the bending and straightening of the bionic finger by the change of air pressure inside the air cavity. In addition, the manufacturing process of the present invention is highly modernized, the production efficiency is high, the obtained bionic finger has good consistency, and the quality is stable and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1It is a schematic diagram of the main structure of an embodiment of the present invention.

[0033] Figure 2 2 is a schematic diagram of a top view of the structure of an embodiment of the present invention.

[0034] Figure 3 1 is a design diagram of a negative Poisson's ratio knitted layer pattern according to an embodiment of the present invention.

[0035] Figure 4 1 is a knitting diagram of a negative Poisson's ratio knitting layer according to an embodiment of the present invention.

[0036] Explanation of the accompanying drawings: 1. Skin adhesive layer; 2. Negative Poisson's ratio knitted layer; 3. Silicone-based resin layer; 4. Air cavity; 5. Ventilation hole. DETAILED DESCRIPTION

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0038] Embodiment 1.

[0039] See also Figures 1 to 4 The weight-bearing soft bionic finger of this embodiment includes a skin glue layer 1, a negative Poisson's ratio knitted layer 2, a silicone-based resin layer 3 and an air cavity 4.

[0040] The skin adhesive layer 1 of this embodiment is the outermost layer of the bionic finger. It is made of a silicone-based resin material with a Shore hardness of 10HA and a Young's elastic modulus of 152Ka. It has the characteristics of high hardness and high elasticity to enhance the touch and wear resistance of the bionic finger and extend its service life. The skin adhesive layer 1 is cylindrical with one end closed, and its shape is similar to that of a human finger. The negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3 are located inside the skin adhesive layer 1.

[0041] like Figure 3 and Figure 4 As shown, the negative Poisson's ratio knitted layer 2 of this embodiment is woven from carbon fiber, glass fiber and polyamide fiber / spandex coated yarn. The structure of the front and back coil loops is unbalanced during knitting, which causes the fabric to wrinkle and shrink after production and processing, forming a zigzag structure with a distinct three-dimensional effect. The zigzag structure becomes larger after folding and unfolding, that is, it shows a negative Poisson's ratio effect. The specific manifestation of the negative Poisson's ratio effect is that the strain direction of the knitted layer is perpendicular to the load direction. When stretched, the knitted layer widens in a direction perpendicular to the stretching direction, and when compressed, the knitted layer narrows in a direction perpendicular to the stretching direction. The more the fabric formed by the negative Poisson's ratio knitted layer 2 is bent, the denser the texture of the zigzag structure, and the more obvious the negative Poisson's ratio effect. The negative Poisson's ratio knitted layer 2 is used to restrain the tensile deformation of the silicone-based resin layer 3, causing it to stretch and expand, thereby improving the tensile strength of the bionic finger.

[0042] The negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3 of this embodiment are laminated and distributed and molded. The molded composite structure adopts a 1+1 composite structure, that is, it includes a layer of negative Poisson's ratio knitted layer 2 and a layer of silicone-based resin layer 3. The hardness and deformation degree of the formed bionic finger are moderate. Molding has the advantages of high production efficiency, good product consistency, stable quality, etc. The single-layer thickness of the negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3 are both controlled within the range of 1-3mm.

[0043] The negative Poisson's ratio knitted layer 2 and the silicone resin layer 3 of this embodiment form an air cavity 4, which is composed of a number of square air chambers. The air cavity 4 is connected to the external air cavity through the vent 5. The air cavity 4 mainly supports and controls the bending of the bionic finger. When the bionic finger needs to bend, gas is introduced into the air cavity 4 through the vent 5 to increase the air pressure inside the air cavity 4, so that the square air chamber expands and gradually bends downward, thereby driving the bionic finger to bend; similarly, when the bionic finger needs to be straightened, the air is released through the vent 5 to reduce the air pressure inside the air cavity 4, so that the deformation of the square air chamber is restored and the bionic finger is restored to the straight state.

[0044] The manufacturing process of the weight-bearing soft bionic finger of this embodiment includes the following steps:

[0045] Step 1: knitting a negative Poisson's ratio knitted layer 2. The specific steps are as follows:

[0046] (Ⅰ) Plate making: Use Hengqiang electronic plate making software to make patterns and weaving plates;

[0047] (II) Yarn feeding: Passive yarn feeding is adopted. With the help of the tension generated by the loop forming mechanism during weaving, the yarn is withdrawn from the creel and led to the weaving area, so that all yarns are fed into the same yarn guide in parallel;

[0048] (III) Weaving: Weaving is done on a computerized flat knitting machine;

[0049] Step 2: 3D print the soft bionic finger mold. The specific steps are as follows:

[0050] (I) CAD drawing: Use CAD software to draw a three-dimensional image of the upper and lower layers of the finger mold;

[0051] (II) 3D printing: using photosensitive resin as raw material to print the mold using stereolithography on an industrial 3D printer;

[0052] Step 3: Molding the composite structure of the negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3. The specific operation steps are as follows: laying a layer of negative Poisson's ratio knitted layer 2 in the upper mold, and then pouring a layer of silicone-based resin layer 3; the operation steps of the lower mold are the same as the upper layer, buckling the prepared upper mold on the lower mold, putting it into an oven for curing and demolding, the oven temperature is set to 45°C, and it is taken out and demolded after heating for 1.5 to 2 hours;

[0053] Step 4: Shape the skin glue layer 1. The specific steps are as follows:

[0054] (I) placing the composite structure prepared in step 3 into another mold with a larger cavity;

[0055] (II) injecting a silicone-based resin from the upper end of the mold so that the silicone-based resin completely covers the outer surface of the composite structure to form a skin glue layer 1;

[0056] (III) Place the mold in an oven for curing and demoulding.

[0057] Embodiment 2.

[0058] The content of this embodiment is basically the same as that of Embodiment 1, and the same parts are not repeated. The difference from Embodiment 1 is that the composite structure of the negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3 molded in this embodiment adopts a 1+2 composite structure, that is, from the outside to the inside, it includes a layer of negative Poisson's ratio knitted layer 2, a layer of silicone-based resin layer 3 and a layer of negative Poisson's ratio knitted layer 2. The hardness and deformability of the bionic finger formed are improved compared with Embodiment 1.

[0059] Correspondingly, in step three of the manufacturing process, the specific operating steps of molding the composite structure of the negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3 become: laying a layer of negative Poisson's ratio knitted layer 2 in the upper mold, then pouring a layer of silicone-based resin layer 3, and then laying a layer of negative Poisson's ratio knitted layer 2; the operating steps of the lower mold are the same as the upper layer, the prepared upper mold is buckled on the lower mold, put into the oven for curing and demolding, the oven temperature is set to 45°C, and it is heated for 1.5 hours to 2 hours and then taken out and demolded.

[0060] Embodiment three.

[0061] The content of this embodiment is basically the same as that of Embodiment 1, and the same parts are not repeated. The difference from Embodiment 1 is that the composite structure of the negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3 molded in this embodiment adopts a 2+2 composite structure, that is, from the outside to the inside, it includes a layer of negative Poisson's ratio knitted layer 2, a layer of silicone-based resin layer 3, a layer of negative Poisson's ratio knitted layer 2 and a layer of silicone-based resin layer 3. The hardness and deformability of the bionic finger formed are significantly improved compared with Embodiment 1.

[0062] Correspondingly, in step three of the manufacturing process, the specific operating steps of molding the composite structure of the negative Poisson's ratio knitted layer 2 and the silicone-based resin layer 3 become: lay a layer of negative Poisson's ratio knitted layer 2 in the upper mold, then pour a layer of silicone-based resin layer 3, then lay another layer of negative Poisson's ratio knitted layer 2, and then pour another layer of silicone-based resin layer 3; the operating steps of the lower mold are the same as the upper layer, buckle the prepared upper mold on the lower mold, put it into the oven for curing and demolding, set the oven temperature to 45°C, and take it out and demold it after heating for 1.5 to 2 hours.

[0063] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A weight-bearing soft bionic finger, comprising a skin glue layer (1), a negative Poisson's ratio knitted layer (2), a silicone-based resin layer (3) and an air cavity (4), characterized in that: The skin glue layer (1) is the outermost layer of the bionic finger. The skin glue layer (1) is in the shape of a cylinder with one end closed. The negative Poisson's ratio knitted layer (2) and the silicone-based resin layer (3) are located inside the skin glue layer (1). The negative Poisson's ratio knitted layer (2) is formed of a sawtooth-shaped tissue by arranging positive and negative coils. The silicone-based resin layer (3) and the negative Poisson's ratio knitted layer (2) are laminated and distributed. The air cavity (4) is located inside the negative Poisson's ratio knitted layer (2) and the silicone-based resin layer (3). The air cavity (4) is composed of a plurality of square air chambers. The air cavity (4) is connected to an external air cavity through a vent (5). The skin adhesive layer (1) is made of a silicone-based resin material; the negative Poisson's ratio knitted layer (2) and the silicone-based resin layer (3) are molded; the molded composite structure includes the following types: 1+1 type, i.e., 1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone-based resin layer; Type 1+2, i.e. 1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone-based resin layer + 1 layer of negative Poisson's ratio knitted layer; type 2+2, i.e. 1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone-based resin layer + 1 layer of negative Poisson's ratio knitted layer + 1 layer of silicone-based resin layer.

2. The weight-bearing soft bionic finger according to claim 1, characterized in that: The skin adhesive layer (1) is made of a silicone-based resin material with a Shore hardness of 10HA and a Young's elastic modulus of 152Ka.

3. The weight-bearing soft bionic finger according to claim 1, characterized in that: The negative Poisson's ratio knitted layer (2) is woven from carbon fiber, glass fiber and polyamide fiber / spandex coated yarn.

4. The weight-bearing soft bionic finger according to claim 1, characterized in that: The single-layer thickness of the negative Poisson's ratio knitted layer (2) and the silicone-based resin layer (3) are both 1-3 mm.

5. A process for manufacturing a weight-bearing soft bionic finger according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: knitting a negative Poisson's ratio knitted layer (2). The specific steps are as follows: (Ⅰ) Plate making: Use Hengqiang electronic plate making software to make patterns and weaving plates; (II) Yarn feeding: Passive yarn feeding is adopted, and the yarn is withdrawn from the creel and led to the weaving area by the tension generated by the loop forming mechanism during weaving; (III) Weaving: Weaving is done on a computerized flat knitting machine; Step 2: 3D print the soft bionic finger mold. The specific steps are as follows: (I) CAD drawing: Use CAD software to draw a three-dimensional image of the upper and lower layers of the finger mold; (II) 3D printing: using photosensitive resin as raw material to print the mold on an industrial-grade 3D printer; Step 3: Molding the composite structure of the negative Poisson's ratio knitted layer (2) and the silicone-based resin layer (3). The specific operation steps are as follows: (I) 1+1 type composite structure molding: a negative Poisson's ratio knitted layer (2) is laid in the upper mold, and then a silicone resin layer (3) is poured; the operation steps of the lower mold are the same as the upper mold, the upper mold is buckled on the lower mold, and the mold is placed in an oven for curing and demoulding; (II) 1+2 type composite structure molding: a negative Poisson's ratio knitted layer (2) is laid in the upper mold, and then a silicone resin layer (3) is poured, and then a negative Poisson's ratio knitted layer (2) is laid; the operation steps of the lower mold are the same as the upper mold, the upper mold is buckled on the lower mold, and the mold is placed in an oven for curing and demoulding; (III) 2+2 type composite structure molding: a negative Poisson's ratio knitted layer (2) is laid in the upper mold, and then a silicone resin layer (3) is poured, and then another negative Poisson's ratio knitted layer (2) is laid, and then another silicone resin layer (3) is poured; the operation steps of the lower mold are the same as the upper mold, and the upper mold is buckled on the lower mold, and then placed in an oven for curing and demoulding; Step 4: Shaping the skin adhesive layer (1). The specific steps are as follows: (I) placing the composite structure prepared in step 3 into another mold with a larger cavity; (II) injecting a silicone-based resin from the upper end of the mold so that the silicone-based resin completely covers the outer surface of the composite structure to form a skin glue layer; (III) Place the mold in an oven for curing and demoulding.

6. The manufacturing process of the weight-bearing soft bionic finger according to claim 5, characterized in that: In the knitting of the negative Poisson's ratio knitted layer (2) in step 1, the yarns are fed in parallel into the same yarn guide.

7. The manufacturing process of the weight-bearing soft bionic finger according to claim 5, characterized in that: The 3D printing software bionic finger mold in step 2 adopts stereolithography.

8. The manufacturing process of the weight-bearing soft bionic finger according to claim 5, characterized in that: The oven temperature in step three is set to 45° C., and the heating time is 1.5 hours to 2 hours.

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