Carbon fiber rod of exoskeleton robot and preparation method of carbon fiber rod

Abstract

The invention discloses a carbon fiber rod of an exoskeleton robot and a preparation method thereof, and the preparation method comprises the following steps: a, processing a core mold according to the shape of an inner cavity of the carbon fiber rod, and polishing the surface of the core mold; b, the air bag comprises an inner air bag body and an outer air bag body, the core mold is sleeved with the inner air bag body, and the inner air bag body is attached to the core mold; c, paving a carbon fiber layer on the outer wall of the inner air bag; d, the outer air bag is vacuumized so that the outer air bag can be attached to the carbon fiber layer, and a core mold assembly is obtained; e, the core mold assembly is put into a forming mold, and a gap exists after the upper mold and the lower mold are closed; f, the core mold assembly and the forming mold are heated to 120-150 DEG C together and kept for 20-30 min, and in the heating process, the inner air bag is inflated, and the outer air bag is exhausted; and g, cooling and demolding, taking out the core mold and the air bag, and curing the carbon fiber layer into the carbon fiber rod. According to the invention, the quality of the prepared carbon fiber rod is reliable through the expansion shaping of the inner air bag and the vacuum adsorption fitting of the outer air bag.

Description

Technical Field

[0001] This invention relates to the field of exoskeleton robot technology, and more specifically, to a carbon fiber rod for an exoskeleton robot and its preparation method. Background Technology

[0002] Existing exoskeleton robots have extensively used carbon fiber materials for their struts and arms to meet weight reduction requirements, as exemplified by Chinese invention patent application CN120606370A, entitled "A Carbon Fiber Exoskeleton Arm and Its Manufacturing Method." However, this approach also has limitations. For instance, when the manufactured strut has a non-smooth surface, the silicone inner membrane used cannot adequately fill the non-smooth surface during heating and expansion. Furthermore, the entire outer wall of the strut is not covered with the same layer of carbon fiber material during carbon fiber application; a seam is typically left at the edge of the strut. If this seam is located precisely at the gap between the upper and lower molds during subsequent heating, the quality of the formed carbon fiber strut at the seam is unreliable and requires improvement. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a carbon fiber rod for an exoskeleton robot and its preparation method. The method uses an air bag composed of an inner air bag and an outer air bag. The inner air bag expands and shapes the rod, while the outer air bag is vacuum-adsorbed and adheres to the edge of the rod for protection. The resulting carbon fiber rod has a smooth appearance and reliable quality.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for fabricating a carbon fiber rod for an exoskeleton robot includes the following steps:

[0006] a. Machining a core mold according to the inner cavity shape of the carbon fiber rod, and polishing its surface;

[0007] b. Insert the core mold into the air bag, which includes an inner air bag and an outer air bag. Both the inner and outer air bags have an air inlet and the two air inlets are arranged opposite to each other. The core mold is inserted into the inner air bag and the inner air bag fits the core mold.

[0008] c. Lay a carbon fiber layer on the outer wall of the inner air bag, with the carbon fiber layer located between the inner and outer air bags;

[0009] d. After laying the carbon fiber layer, the outer air bag is vacuumed to make the outer air bag adhere to the carbon fiber layer, thus obtaining the core mold assembly.

[0010] e. Place the core mold assembly into the forming mold composed of the upper mold and the lower mold. There is a gap after the upper mold and the lower mold are closed.

[0011] f. Heat the core mold assembly and the molding mold together to 120℃-150℃ and maintain for 20-30 minutes. During the heating process, inflate the inner air bag and de-inflate the outer air bag.

[0012] g. Cool and demold, remove the core mold and air bag, and the carbon fiber layer is cured into a carbon fiber rod.

[0013] As a further provision, the core mold is made of EPS foam.

[0014] As a further step, in step b, the inner air bag is evacuated to make it conform to the outer surface of the mandrel.

[0015] As a further step, in step c, the carbon fiber prepreg is first cut according to the template; 10 layers of the cut carbon fiber / epoxy resin-based unidirectional prepreg are laid, with the innermost and outermost layers laid at 90°, the middle layers laid at ±45°, and then a layer of carbon fiber / epoxy resin plain weave prepreg is laid. Each layer must be compacted.

[0016] As a further feature, in step c, each layer of carbon fiber prepreg is compacted by roller compaction or by vacuum compaction with an external air bag covering the carbon fiber prepreg.

[0017] As a further feature, external air ports are installed on both sides of the molding die, and the air inlets of the inner air bag and the outer air bag are respectively connected to the external air port on one side.

[0018] As a further feature, the carbon fiber rod includes a rod edge, and the gap between the upper mold and the lower mold when they are closed is opposite to the rod edge.

[0019] As a further feature, the air bag is made of nylon, polytetrafluoroethylene, or polyimide, and the inner air bag and the outer air bag are not connected.

[0020] As a further setting, in step f, the inflation pressure of the inner air bag is 0.15~0.3 MPa, and the vacuum degree inside the outer air bag is -0.1~-0.12 MPa.

[0021] A carbon fiber rod for an exoskeleton robot is prepared using a specific method.

[0022] In summary, the present invention has the following beneficial effects: by using an air bag composed of an inner air bag and an outer air bag, the outer air bag vacuum adsorbs and compacts the carbon fiber layer during the laying process. During the heating process, the inner air bag expands and shapes, and the outer air bag vacuum adsorbs and adheres to the edge of the rod for protection. The resulting carbon fiber rod has a smooth appearance and reliable quality. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the molding die used in an embodiment.

[0024] Figure 2 This is a perspective view of the carbon fiber rod as an example.

[0025] Figure 3 This is a cross-sectional view of the core mold assembly in an embodiment.

[0026] Figure 4 This is a schematic diagram of the core mold assembly in an embodiment.

[0027] Figure 5 This is a schematic diagram of the core mold assembly being placed into the molding die in an embodiment.

[0028] Reference numerals: Upper mold 1, Lower mold 2, Core mold assembly 3, External air port 4, Core mold 5, Carbon fiber layer 6, Air bag 7, Inner air bag 71, Outer air bag 72, Air interface 73, Carbon fiber rod 8, Rod edge 81, Rod recess 82, Gap 9. Detailed Implementation

[0029] 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, and 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.

[0030] Reference Figures 1-5 As shown, a method for fabricating a carbon fiber rod for an exoskeleton robot includes the following steps:

[0031] a. Mandrel 5 is fabricated according to the inner cavity shape of the carbon fiber rod, and its surface is polished; the material of mandrel 5 is EPS foam. Contouring EPS foam is used as the carrier for prepreg coverage; the volume of the EPS foam will shrink during the subsequent heating process.

[0032] Reference Figure 3 , Figure 4 ,in Figure 4 This is an illustrative diagram added to specifically illustrate the function of airbag 7; its size and shape are not the actual size and shape of airbag 7. Airbag 7 includes an inner airbag 71 and an outer airbag 72. Both the inner airbag 71 and the outer airbag 72 have an air inlet 73, and the two air inlets 73 are arranged opposite each other. Figure 4 For reference, the air inlet 73 of the inner air bag 71 faces left, and the air inlet 73 of the outer air bag 72 faces right. The inner air bag 71 and the outer air bag 72 are not connected. Part of the outer wall of the inner air bag 71 is used as the inner wall of the outer air bag 72, and part of the inner air bag 71 is located inside the outer air bag 72.

[0033] The air bag 7 is made of nylon, polytetrafluoroethylene, or polyimide. The nylon can be PA46 or PA9T, and can be made by double-layer co-extrusion or heat sealing and bonding.

[0034] b. The core mold 5 is fitted into the inner air bag 71, and the inner air bag 71 is evacuated to make the inner air bag 71 fit against the outer surface of the core mold 5.

[0035] c. Using contoured EPS foam as a carrier, a carbon fiber layer 6 is laid on the outer wall of the inner air bag 71. When laying the carbon fiber layer 6, Figure 4 For reference, the outer air bag 72 needs to be flipped to the left and moved out of the area of ​​the conformal EPS foam to make room for laying carbon fiber.

[0036] First, cut the carbon fiber prepreg into the required shape according to the template, and simultaneously assign layup sequence numbers as layup indicators. There are two types of carbon fiber prepreg: carbon fiber / epoxy resin-based unidirectional prepreg and carbon fiber / epoxy resin plain weave prepreg. The epoxy resin content in both types of prepreg is between 35% and 42%. Lay 10 layers of the cut carbon fiber / epoxy resin-based unidirectional prepreg, with the innermost and outermost layers laid at a 90° angle, and the middle layers laid at ±45°. Then lay another layer of carbon fiber / epoxy resin plain weave prepreg, compacting each layer. The ±45° middle layer layup means one layer at +45°, one layer at -45°, then another layer at +45°, then another layer at -45°, and so on, in a cycle.

[0037] Each layer of carbon fiber prepreg is compacted using roller compaction or by vacuum compaction with an external air bag (72). Figure 4 For reference, after laying a layer of carbon fiber prepreg, the outer air bag 72, which was originally on the left and had been flipped over, was flipped to the right and moved to cover the area where the carbon fiber prepreg was located. After vacuuming and maintaining the vacuum, the outer air bag 72 was flipped to the left and moved out of the area of ​​the conformal EPS foam to prepare for the next laying of carbon fiber prepreg.

[0038] d. After laying the carbon fiber layer 6, the outer air bag 72 is evacuated to ensure it adheres to the carbon fiber layer 6. After laying, the carbon fiber layer 6 is located between the inner air bag 71 and the outer air bag 72, resulting in the core mold assembly 3. Figure 3 , Figure 4 The product shown.

[0039] e. Place the core mold assembly 3 into the forming mold composed of the upper mold 1 and the lower mold 2, as shown in the reference. Figure 1 As shown, external air ports 4 are installed on both sides of the molding die, and the air inlets 73 of the inner air bag 71 and the outer air bag 72 are respectively connected to one of the external air ports 4. Inflation or vacuuming can be performed through the external air ports 4.

[0040] Reference Figure 5 As shown, Figure 5 This is a schematic diagram added to illustrate the fit between the gap 9 of the molding die and the core mold assembly 3; its dimensions and shape are not actual dimensions and shapes. The usage of this molding die is consistent with Chinese patent application CN120606370A, namely, mold closing is guided by positioning guide pillars, and the mold closing gap between the upper and lower molds is controlled by tightening bolts; after mold closing, the upper and lower molds are fixed with connecting bolts. Therefore, a gap 9 exists after the upper mold 1 and lower mold 2 are closed.

[0041] Reference Figure 2 As shown, the carbon fiber rod 8 includes two rod edges 81 and a rod recess 82. Due to the presence of the rod recess 82, it is equivalent to a non-smooth surface of the carbon fiber rod 8, making the use of a silicone inner film method unsuitable. The carbon fiber rod 8 is double-sided, meaning that carbon fiber prepreg is laid on the roughly rectangular arc-shaped surface where the rod recess 82 is located, and carbon fiber prepreg is also laid on the opposite side. The carbon fiber prepreg laid on both sides will form a seam line at the two rod edges 81.

[0042] Reference Figure 5 The gap 9 between the upper mold 1 and the lower mold 2 is opposite to the edge 81 of the rod, that is, the gap 9 is opposite to the seam line. Therefore, except for the edge 81 of the rod, the rest of the parts can be heated well under force. Due to the presence of the seam line, the carbon fiber layer 6 may detach at the seam line or the molded product may not be strong and reliable due to the internal expansion pressure.

[0043] f. Fix the core mold assembly 3 and the molding die together on the molding machine and heat to 120℃-150℃ for 20-30 minutes, then maintain at 120℃ for 30 minutes and at 150℃ for 20 minutes. During the heating process, due to the shrinkage of the EPS foam, the inner air bag 71 needs to be inflated. The inflation pressure of the inner air bag 71 is 0.15~0.3Mpa, ensuring that the carbon fiber rod 8 is subjected to air pressure inside and molding die pressure outside during the molding process. The outer air bag 72 is evacuated; the vacuum degree inside the outer air bag 72 is -0.1~-0.12Mpa. The vacuum inside the outer air bag 72 does not affect the expansion of the inner air bag 71. At the same time, the vacuum inside the outer air bag 72 can firmly protect the edge 81 of the rod, especially the seam line of the rod edge 81, which will be tightly sealed by the outer air bag 72. Even if the expansion of the inner air bag 71 causes the edge 81 of the rod to expand slightly outward, it will not affect the seam line being sealed by the outer air bag 72, so that the seam line will not come apart, ensuring the quality of the finished product.

[0044] g. Cool and demold, remove the core mold 5 and air bag 7, and solidify the carbon fiber layer 6 into carbon fiber rod 8. Subsequently, the end face, hole position and other key parts of the carbon fiber rod 8 blank are precision machined. The processed carbon fiber rod 8 is cleaned and polished, and then an epoxy varnish layer is sprayed on its outer surface and baked and cured to finally obtain the finished product.

[0045] This embodiment also discloses a carbon fiber rod for an exoskeleton robot, which is prepared using the above-described method.

[0046] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a carbon fiber rod for an exoskeleton robot, characterized in that, Includes the following steps: a. Process the core mold (5) according to the inner cavity shape of the carbon fiber rod, and polish its surface. b. Insert the core mold (5) into the air bag (7). The air bag (7) includes an inner air bag (71) and an outer air bag (72). Both the inner air bag (71) and the outer air bag (72) have an air inlet (73) and the two air inlets (73) are arranged opposite to each other. The core mold (5) is inserted into the inner air bag (71) and the inner air bag (71) fits against the core mold (5). c. Lay a carbon fiber layer (6) on the outer wall of the inner air bag (71), with the carbon fiber layer (6) located between the inner air bag (71) and the outer air bag (72); d. After laying the carbon fiber layer (6), the outer air bag (72) is vacuumed to make the outer air bag (72) fit the carbon fiber layer (6) to obtain the core mold assembly (3); e. Place the core mold assembly (3) into the molding mold consisting of the upper mold (1) and the lower mold (2). After the upper mold (1) and the lower mold (2) are closed, there is a gap (9). f. Heat the core mold assembly (3) and the molding mold together to 120℃-150℃ and keep it for 20-30 minutes. During the heating process, the inner air bag (71) is inflated and the outer air bag (72) is deflated. g. Cool and demold, remove the core mold (5) and air bag (7), and solidify the carbon fiber layer (6) into a carbon fiber rod (8).

2. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 1, characterized in that, The core mold (5) is made of EPS foam.

3. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 1, characterized in that, In step b, the inner air bag (71) is evacuated to make the inner air bag (71) fit against the outer surface of the core mold (5).

4. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 1, characterized in that, In step c, the carbon fiber prepreg is first cut according to the template; 10 layers of the cut carbon fiber / epoxy resin-based unidirectional prepreg are laid, with the innermost and outermost layers laid at 90°, the middle layers laid at ±45°, and then a layer of carbon fiber / epoxy resin plain weave prepreg is laid. Each layer must be compacted.

5. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 4, characterized in that, In step c, each layer of carbon fiber prepreg is compacted by roller compaction or by vacuum compaction using an external air bag (72) to cover the carbon fiber prepreg.

6. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 1, characterized in that, External air inlets (4) are installed on both sides of the molding die, and the air inlets (73) of the inner air bag (71) and the outer air bag (72) are respectively connected to the external air inlet (4) on one side.

7. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 1, characterized in that, The carbon fiber rod (8) includes a rod edge (81), and the gap (9) between the upper mold (1) and the lower mold (2) is opposite to the rod edge (81).

8. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 1, characterized in that, The air bag (7) is made of nylon, polytetrafluoroethylene or polyimide, and the inner air bag (71) and the outer air bag (72) are not connected.

9. The method for preparing a carbon fiber rod for an exoskeleton robot according to claim 1, characterized in that, In step f, the inflation pressure of the inner air bag (71) is 0.15~0.3 MPa, and the vacuum degree inside the outer air bag (72) is -0.1~-0.12 MPa.

10. A carbon fiber rod for an exoskeleton robot, characterized in that, It is prepared by the preparation method described in any one of claims 1-9.

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