Cavity type soft driver one-shot molding method

Abstract

The application relates to a soft robot forming method, in particular to a one-time forming method of a cavity type soft driver. The method comprises the following steps: S1, preparing a wax core; S2, pouring and solidifying silica gel; and S3, removing the wax and obtaining a one-time formed soft driver. The method realizes one-time silica gel pouring forming, and the wax core is convenient to demold during preparation, and can be used for preparing a fluid type soft driver with a complex structure.

Description

Technical Field

[0001] This invention relates to a method for molding soft robots, and in particular to a method for molding a cavity-type soft actuator in one step. Background Technology

[0002] Currently, soft actuators have broad development prospects. Flexible soft actuators can be applied to biomimetic fish, using tail-shaped soft actuators to repeatedly wiggle and propel the fish forward. There are various soft actuation methods, such as using shape memory alloys to drive fluid actuation. Silicone is a commonly used material for making soft actuators. The manufacturing process uses a silicone casting and curing method, where uncured liquid silicone is poured into a specific mold and allowed to solidify.

[0003] Fluid-driven soft robots utilize the principle of cavity stamping and expansion for propulsion, and their structure contains sealed cavities. Due to the presence of these cavities, a specific mold is required to occupy the cavity space during silicone injection. Furthermore, since the mold needs to be removed after the silicone has cured, the silicone level cannot be higher than the mold to prevent the silicone from becoming impossible to remove after curing. This makes it impossible to achieve one-time molding with existing manufacturing methods. Therefore, distributed curing or bonding methods are typically used to create the sealed cavity. When soft robots manufactured using these methods are applied to biomimetic fish, as water depth and external pressure increase, excessive internal stress at the bonding surface can lead to breakage at the bonding joint, resulting in internal fluid leakage and functional failure of the biomimetic fish. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects in the prior art and to propose a one-time molding method for cavity-type soft actuators. This method realizes one-time silicone injection molding, facilitates demolding during wax core production, and can be used to manufacture fluid-type soft actuators with complex structures.

[0005] The technical solution of the present invention is: a method for one-time molding of a cavity-type soft actuator, comprising the following steps:

[0006] S1. Making the wax core;

[0007] Wax cores are made using wax core molds, which include:

[0008] The module is arranged in two symmetrical halves, and the inside of the module has a groove. The shape of the grooves of the two modules after they are joined corresponds to the shape of the wax core.

[0009] The module has several insertion slots spaced apart along the length of the joint surface between the two modules, and the insertion plate is slidably disposed in the insertion slots.

[0010] The fixing rod is located at the joint surface of the two modules. The fixing rod penetrates the inside of the wax core mold, and both ends of the fixing rod extend out of both ends of the module. After the wax core is formed, the fixing rod is fixedly inserted through the inside of the wax core.

[0011] S2. Pour and cure silicone;

[0012] The wax core is placed in a silicone mold, silicone is poured in and cured to obtain a silicone soft driver containing a wax core.

[0013] S3. Dewaxing and obtaining a one-piece molded software driver.

[0014] In this invention, the groove inside the module is an arc-shaped groove, and the width of the arc-shaped groove increases sequentially along the axial direction of the fixed shaft.

[0015] The insert plate is a cuboid plate, with the insert plate slots in the two side modules arranged opposite each other, and the corresponding insert plates in the two side modules arranged opposite each other.

[0016] The two modules are provided with slots at both ends of their mating surfaces, and a shaft hole is formed between the corresponding slots of the two modules. The fixing rod is set in the shaft hole.

[0017] The mating surfaces of the two side plates are provided with slots, and insertion holes are formed between the corresponding slots on both sides. The fixing rod passes through each insertion hole.

[0018] In step S1, the process of making a wax core using a wax core mold includes the following steps:

[0019] S1.1 Insert the fixing rod into the wax core mold, and insert the fixing rod into the shaft holes formed at both ends of the two side modules in sequence;

[0020] S1.2 Insert the insert plates into the insert plate slots of the mold in sequence, and set the fixing rods in the corresponding insertion holes formed by the insert plates on both sides.

[0021] S1.3 Spray an oily release agent onto the surface of the wax core mold, heat the paraffin wax to a liquid state, pour the liquid paraffin wax into the wax core mold, let it stand until the paraffin wax solidifies, and then demold to obtain the wax core.

[0022] In step S1.3 above, the demolding process includes the following steps:

[0023] S1.3.1. Process the cured paraffin wax surface into a flat surface;

[0024] S1.3.2 Pull the insert plate out from the inside to the outside of the insert plate groove: Pull the insert plate out one by one along the direction in which the width of the groove gradually increases.

[0025] The silicone mold includes:

[0026] The mold body has a cavity inside that corresponds to the shape of the wax core. The two ends of the mold body have mounting grooves. The two ends of the fixing rod are set in the mounting grooves. Wax core fixing blocks are respectively set in the mounting grooves and above the fixing rods.

[0027] The top cover plate is fixedly connected to the top surface of the mold body, and the top cover plate is provided with a side groove;

[0028] The locating pins pass through the pin holes on the mold body and the top cover plate in sequence.

[0029] Step S2 includes the following steps:

[0030] Place the wax core into the cavity of the mold body. Place the two ends of the fixing rod, which is fixed inside the wax core, into the mounting slots at both ends of the mold body. Use the wax core fixing block to clamp and fix the ends of the fixing rod into the mounting slots, thereby fixing the wax core into the mold body. Prepare liquid silicone and inject it into the mold body through a syringe until the level of the silicone liquid in the mold body rises above the upper surface of the mold body and overflows. Wait 7-15 minutes, then tilt the top cover plate onto the mold body so that one side of the top cover plate contacts the liquid surface first, and then slowly press down the other side of the top cover plate until the top cover plate is horizontally covering the silicone liquid surface and there are no obvious air bubbles inside.

[0031] The positioning pins pass through the pin holes on the mold body and the top cover plate in sequence, and the top cover plate is fixed to the top surface of the mold body; the silicone mold is left to stand so that the silicone can be cured, and after demolding, the silicone soft actuator with the inner wax core is obtained.

[0032] The liquid silicone uses Purston 30-degree platinum mold transparent coating. Mix A and B adhesives in a 1:1 mass ratio and stir clockwise for 3 minutes. Pour the mixture into a syringe, seal the plug, pull out the piston to perform vacuuming, repeat the vacuuming action 2-3 times, and then inject the adhesive into the mold body through the injection port reserved on the top cover plate.

[0033] In step S3, the fixing rod is removed from the wax core, and the silicone soft actuator containing the wax core obtained in step S2 is placed in the dewaxing water and heated by the water source. The liquid paraffin obtained after the wax core solution floats on the water surface, thus obtaining a one-time molded silicone soft actuator.

[0034] The beneficial effects of this invention are:

[0035] (1) One-time silicone injection molding was achieved, which effectively prevented performance defects at the connection surface when the soft robot was made in parts;

[0036] (2) A plate-type wax core mold is proposed. By setting the plate, the risk of overall demolding is distributed to each independent demolding step, which reduces the risk of demolding failure and improves the molding efficiency of wax core.

[0037] (3) This method does not require the use of professional wax injection equipment and is more suitable for exploratory trial production in the laboratory stage;

[0038] (4) This method can be used to create complex fluid-type soft actuators, and its production range can be expanded to any porous object with an internal cavity. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the wax core mold;

[0040] Figure 2 This is a schematic diagram of the structure of a silicone mold.

[0041] In the diagram: 1 Module; 2 Arc-shaped groove; 3 First slot; 4 Fixing rod; 5 Insert plate slot; 6 Insert plate; 7 Second slot; 8 Top cover plate; 9 Mold body; 10 Bolt; 11 Side groove; 12 Mounting groove; 13 Wax core fixing block; 14 Wax core; 15 Positioning pin. Detailed Implementation

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] Specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many ways other than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0044] The cavity-type soft actuator one-time molding method of the present invention includes the following steps.

[0045] The first step is to make the wax core.

[0046] This step uses, for example Figure 1 The wax core mold shown is used to make wax cores. The wax core mold includes two symmetrically arranged modules 1. Each module 1 has an arc-shaped groove 2 in its center. When the two modules are joined, the combined shape of the two arc-shaped grooves 2 corresponds to the shape of the wax core to be made. In this embodiment, the width of one end of the arc-shaped groove 2 along the length of the joint surface is greater than the width of the other end along the length direction, and the width gradually increases.

[0047] Both modules have a first slot 3 on their mating surfaces. In this embodiment, the first slots are symmetrically arranged at both ends along the length of the mating surfaces of the two modules, and a shaft hole is formed between the corresponding two first slots on the two modules. The fixing rod 4 passes through the shaft holes at both ends of the mating surfaces in sequence, thereby inserting the fixing rod 4 into the wax core mold. The fixing rod is positioned by the shaft holes at the ends of the two mold halves.

[0048] Several insertion slots 5 are evenly spaced along the length of the joint surface within the two modules. The insertion slots 5 extend through the width of the modules, and the slots on both sides of the modules are correspondingly arranged, meaning they are connected. Insertion plates 6 are installed within each insertion slot 5. Each insertion plate 6 is a flat cuboid. Second slots 7 are provided at the joint surfaces of both insertion plates, forming insertion holes between the corresponding second slots on both sides. A fixing rod passes through the insertion holes formed by each insertion plate.

[0049] When making a wax core using the aforementioned wax core mold, firstly, the fixing rod 4 is inserted into the wax core mold. The fixing rod 4 passes through the shaft holes at both ends of the wax core mold in sequence, and its positioning is achieved through the shaft holes at the joint surfaces of the two modules. The axial position of the fixing rod 4 is then adjusted to fix its position.

[0050] Insert the insert plates 6 one by one into the insert plate slots 5 of the wax core mold. Spray an oil-based release agent onto the surface of the wax core mold to reduce the friction between the paraffin wax and the wax core mold during the wax core making process.

[0051] The paraffin wax is heated to a liquid state. In this embodiment, No. 62 white beeswax is used, which has a melting point of 62°C. When the temperature of the liquid paraffin wax drops to 65-75°C, the liquid paraffin wax is poured into the wax core mold and allowed to cool and stand at room temperature for 1-2 hours. After the paraffin wax solidifies, it is demolded.

[0052] During the demolding process, firstly, the surface of the cured paraffin wax is processed into a flat surface. In this embodiment, a utility knife can be used to flatten the protrusions on the surface of the paraffin wax. Then, the insert plate 6 is pulled out from the inside to the outside of the insert plate groove 5. To prevent the paraffin wax sheet from slipping on the fixing rod during the extraction of the insert plate, the insert plates are pulled out sequentially along the direction where the width of the arc-shaped groove increases from small to large.

[0053] After removing all the inserts, finally remove the two modules 1. At this point, the modules can be easily removed from the wax core, and the wax core is obtained.

[0054] The second step is to pour in and cure the silicone.

[0055] First, prepare the silicone mold.

[0056] like Figure 2 As shown, the silicone mold in this embodiment includes a top cover plate 8 and a mold body 9. The top cover plate 8 is located on top of the mold body 9, and the top cover plate 8 and the mold body 9 are fixedly connected by several bolts 10. The top cover plate 8 in this embodiment is made of acrylic material and is transparent, which facilitates observation of air bubbles during glue pouring and real-time observation of the situation inside the mold. At the same time, the top cover plate 8 is also provided with a side groove 11.

[0057] The mold body 9 has a cavity inside, and the wax core 10 is placed inside the cavity of the mold body 9. The shape of the cavity corresponds to the shape of the wax core. The mold body 9 has mounting grooves 12 at both ends. The two ends of a fixing rod fixed inside the wax core are placed in the mounting grooves 12 at both ends of the mold body. Wax core fixing blocks 13 are respectively provided in the two mounting grooves and above the fixing rods. The wax core fixing blocks 13 clamp and fix the two ends of the fixing rods in the mounting grooves, thereby fixing the wax core 14 inside the mold body 9.

[0058] Next, we will prepare the liquid silica gel.

[0059] In this embodiment, Purston 30-degree platinum transparent silicone for mold making is used. A and B adhesives are mixed in a 1:1 mass ratio and stirred clockwise for 3 minutes. The mixture is poured into a syringe, the plug is sealed, and the piston is pulled to create a vacuum. This vacuuming process is repeated 2-3 times. Then, silicone is poured into the mold until the silicone level rises slightly above the top surface of the mold body and some overflows. After waiting 7-15 minutes, the top cover is tilted and placed on the mold body. One side of the top cover contacts the silicone surface first, then the other side is slowly pressed down until the top cover is horizontally placed on the silicone surface and no obvious air bubbles are generated inside the mold body. If gaps appear at the edges, silicone can be added to the mold body through the side groove 11. The top surface of the mold is then closed, and the cover is placed after several minutes.

[0060] Positioning pins 15 are inserted sequentially into the pin holes of the mold body 9 and the top cover plate 8, thus achieving accurate positioning and connection between the mold body 9 and the top cover plate 8. Then, the top cover plate is fixed to the top surface of the mold body using bolts 10.

[0061] Finally, allow the silicone mold to cure at room temperature for 12-24 hours. After curing, demold to obtain a silicone soft actuator containing a wax core.

[0062] The third step is to remove the wax.

[0063] The retaining rod is pulled out of the wax core, and the silicone soft actuator containing the wax core obtained in the second step is placed in the dewaxing water for water bath heating. Since the density of paraffin is less than that of water, the liquid paraffin produced after the wax core liquefies will float on the water surface. When the paraffin inside the silicone soft actuator melts and flows out completely from the silicone soft actuator, a one-piece molded soft actuator can be obtained.

[0064] The above provides a detailed description of the one-time molding method for a cavity-type soft actuator provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for one-time molding of a cavity-type soft actuator, characterized in that, Includes the following steps: S1. Making the wax core; Wax cores are made using wax core molds, which include: The module is arranged in two symmetrical halves, with grooves inside. The shape of the grooves on both sides of the module after they are joined corresponds to the shape of the wax core. The module has several insertion slots spaced at intervals along the length of the module joint surfaces on both sides, and the insertion plates are slidably disposed in the insertion slots. The fixing rod is located at the joint surface of the two modules. The fixing rod penetrates the inside of the wax core mold, and both ends of the fixing rod extend out of the two ends of the module. After the wax core is formed, the fixing rod is fixedly inserted through the inside of the wax core. S2. Pour and cure silicone; The wax core is placed in a silicone mold, silicone is poured in and cured to obtain a silicone soft driver containing a wax core. S3. Dewaxing and obtaining a one-piece molded software driver; The groove inside the module is an arc-shaped groove, and the width of the arc-shaped groove increases sequentially along the axial direction of the fixing rod. The insert plate is a rectangular flat plate, with the insert plate slots in the two side modules arranged opposite to each other, and the corresponding insert plates in the two side modules arranged opposite to each other. Slots are provided at both ends of the mating surfaces of the two side modules, and shaft holes are formed between the corresponding slots of the two side modules. The fixing rod is set in the shaft hole. The mating surfaces of the two side plates are provided with slots, and the corresponding slots on both sides form insertion holes, through which the fixing rod passes. The silicone mold includes: The mold body has a cavity inside that corresponds to the shape of the wax core. The two ends of the mold body have mounting grooves. The two ends of the fixing rod are set in the mounting grooves. Wax core fixing blocks are respectively set in the mounting grooves and above the fixing rods. The top cover plate is fixedly connected to the top surface of the mold body, and the top cover plate is provided with a side groove; The locating pins pass through the pin holes on the mold body and the top cover plate in sequence.

2. The method for one-time molding of a cavity-type soft actuator according to claim 1, characterized in that, In step S1, the process of making a wax core using a wax core mold includes the following steps: S1.1 Insert the fixing rod into the wax core mold, and insert the fixing rod into the shaft holes formed at both ends of the two side modules in sequence; S1.2 Insert the insert plates into the insert plate slots of the mold in sequence, and set the fixing rods in the corresponding insertion holes formed by the insert plates on both sides; S1.3 Spray an oily release agent onto the surface of the wax core mold, heat the paraffin wax to a liquid state, pour the liquid paraffin wax into the wax core mold, let it stand until the paraffin wax solidifies, and then demold to obtain the wax core.

3. The method for one-time molding of a cavity-type soft actuator according to claim 2, characterized in that, In step S1.3 above, the demolding process includes the following steps: S1.3.

1. Process the cured paraffin wax surface into a flat surface; S1.3.2 Pull the insert plate out from the inside to the outside of the insert plate groove: Pull the insert plate out one by one along the direction in which the width of the groove gradually increases.

4. The method for one-time molding of a cavity-type soft actuator according to claim 1, characterized in that, In step S2 Includes the following steps: The wax core is placed inside the cavity of the mold body. The two ends of the fixing rod, which is fixed inside the wax core, are placed in the mounting slots at both ends of the mold body. The wax core fixing blocks clamp and fix the ends of the fixing rods in the mounting slots, thereby fixing the wax core inside the mold body. Prepare the liquid silicone. Pour the liquid silicone into the mold body through a syringe until the level of the silicone liquid in the mold body rises above the upper surface of the mold body and overflows. Wait 7-15 minutes, then tilt the top cover plate onto the mold body so that one side of the top cover plate contacts the liquid surface first, and then slowly press down the other side of the top cover plate until the top cover plate is horizontally covering the silicone liquid surface and there are no obvious air bubbles inside. The locating pins pass through the pin holes in the mold body and the top cover plate in sequence, and the top cover plate is fixed to the top surface of the mold body; The silicone mold is left to stand to allow the silicone to solidify. After demolding, a silicone soft driver with an internal wax core is obtained.

5. The method for one-time molding of a cavity-type soft actuator according to claim 4, characterized in that, The liquid silicone uses Purston 30-degree platinum mold transparent coating. Mix A and B adhesives in a 1:1 mass ratio and stir clockwise for 3 minutes. Pour into a syringe, seal the plug, pull out the piston to perform vacuuming, repeat the vacuuming action 2-3 times, and then inject the adhesive into the mold body through the injection port reserved on the top cover plate.

6. The method for one-time molding of a cavity-type soft actuator according to claim 1, characterized in that, In step S3, the fixing rod is removed from the wax core, and the silicone soft actuator containing the wax core obtained in step S2 is placed in the dewaxing water and heated by the water source. After the wax core is liquefied, the resulting liquid paraffin floats on the water surface, thus obtaining a one-time molded silicone soft actuator.

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