Method for forming a composite rod and forming die therefor

Abstract

The present application relates to the technical field of composite rod production, in particular to a composite rod forming method and a forming die thereof, the forming die comprises a soluble die, a core die and a positioning die; the soluble die is a tubular structure with an axial circular through hole, and the two ends of the soluble die are provided with slopes inclined to the axial direction, and the two ends of the two slopes are respectively provided with a limiting boss, and the two limiting bosses are respectively connected with a metal embedded part; the core die is a cylinder provided with fixing holes at both ends, the core die passes through the axial circular through hole of the soluble die, and the two ends of the core die extend to the outside of the soluble die, and the two ends of the core die are respectively provided with a first fixing hole penetrating through; the two ends of the soluble die are fixed with the core die through the positioning die; the manufacturing problem of the composite rod is solved, and the obtained composite rod has a smooth and flat outer surface, and is beautiful and practical.

Description

Technical Field

[0001] This invention patent relates to the technical field of composite material tie rod production, and more specifically, to a molding method for composite material tie rods and its molding die. Background Technology

[0002] With the development of the composite materials industry and the increasing demand for lightweight aircraft, more and more components on aircraft require the use of composite materials for replacement. Composite material tie rods are a type of aircraft cabin door locking mechanism component that needs to withstand large tensile / compressive loads. Due to the space limitations inside the cabin door and the functional requirements of the composite material tie rod itself, it is designed as a lightweight circular tubular structural component with metal threads at both ends, requiring the metal threads at both ends to be coaxial, and the shape to be thinner at both ends and thicker in the middle.

[0003] For circular tubular products that are thin at both ends and thick in the middle, traditional composite material molding methods face the problem of being unable to demold; for circular tubular products with metal threads at both ends, traditional composite material molding methods also cannot guarantee the coaxiality and strength of the metal threads.

[0004] In summary, due to the shape limitations and functional and lightweight requirements of composite tie rods, traditional composite molding methods can no longer meet their manufacturing needs.

[0005] Therefore, a molding method for composite material tie rods and its molding die are provided. Summary of the Invention

[0006] The purpose of this invention is to provide a molding method and molding die for composite material tie rods, which solves the manufacturing problem of composite material tie rods and produces composite material tie rods with a smooth and flat outer surface, which are aesthetically pleasing and practical.

[0007] The present invention is achieved by using a molding die for a composite material tie rod, the molding die comprising a soluble mold, a core mold, and a positioning mold;

[0008] The soluble mold is a tubular structure with an axial circular through hole, and both ends of the soluble mold are provided with slopes inclined towards the axis, and each end of the two slopes is provided with a limiting boss, and each of the two limiting bosses is connected to a metal embedded part.

[0009] The core mold is a cylinder with fixing holes at both ends. The core mold passes through the axial circular through hole of the soluble mold, and both ends of the core mold extend to the outside of the soluble mold. A first fixing hole is also opened at each end of the core mold.

[0010] The soluble mold is fixed to the core mold at both ends by a positioning mold, wherein when each positioning mold is fixed to the core mold, the metal embedded part is located between the soluble mold and the positioning mold;

[0011] The positioning mold has an axially penetrating mounting inner hole, and the core mold passes through the mounting inner hole and is connected to it. The positioning mold also has a second fixing hole perpendicular to the axis. When the positioning mold is connected to the core mold, the first fixing holes at both ends of the core mold are connected to the second fixing hole of the positioning mold by a pin, and the pin passes through the first fixing hole and the second fixing hole.

[0012] Furthermore, the metal embedded part has an axially penetrating through hole, and the outer surface of the metal embedded part is provided with a positioning boss. One end of the through hole with the positioning boss is provided with an internal thread. The outer surface of the middle end of the metal embedded part is provided with a ring of inward groove. The outer surface of the other end of the metal embedded part is provided with an inclined platform that is inclined away from the axis, and a limiting circular hole is formed at the through hole of the inclined platform.

[0013] A positioning groove is formed at one end of the mounting inner hole of the positioning mold, and the positioning groove cooperates with the positioning boss of the metal embedded part.

[0014] The limiting boss on the soluble mold is inserted into the limiting hole of the metal embedded part.

[0015] Furthermore, the soluble mold is a water-soluble mold.

[0016] Furthermore, a method for molding composite material tie rods is provided, including the following steps:

[0017] S1, the outer surfaces of the two metal embedded parts are knurled and sandblasted, a sealing agent is sprayed on the outer surface of the soluble mold, the soluble mold and the two metal embedded parts are installed on the core mold, and the two positioning molds are fixed to both ends of the core mold with steel pins.

[0018] S2, First application: Apply the adhesive film to the outer surface of the metal embedded part, apply a small amount of prepreg to the outer surface of the metal embedded part and the outer surfaces of both ends of the exposed soluble mold, wrap the whole with BOPP tape, wrap with breathable felt, vacuum seal with vacuum bags and sealing tape, and then put it into the curing equipment for the first curing.

[0019] S3, remove the vacuum auxiliaries and BOPP tape, do not demold, roughen the area after the prepreg has been cured, and obtain an intermediate product with composite material blanks at both ends;

[0020] S4, Second application: Apply the adhesive film to the outer surface of the composite material blank, apply the prepreg to the outer surface of the composite material blank and the exposed soluble mold, then wrap the entire surface with BOPP tape, wrap with breathable felt, vacuum seal with vacuum bags and sealing tape, and then put it into the curing equipment for a second curing.

[0021] S5, remove the positioning mold from the core mold, remove the core mold, remove the vacuum auxiliary material and BOPP tape from the surface of the product, dissolve the soluble mold and sealing agent, polish the outer surface of the product to a smooth finish, remove excess resin, and obtain the composite material tie rod.

[0022] Furthermore, the outer surface of the metal embedded part laid for the first time in S2 is the outer surface of the inner side of the positioning boss of the metal embedded part, and does not include the positioning boss.

[0023] Furthermore, during the second paving process in S4, prepreg is used to gradually fill the recessed groove in the middle of the metal embedded part.

[0024] Furthermore, during the first and second application processes, in addition to proper overlap after wrapping the prepreg once, excess prepreg is cut off to ensure that each piece of prepreg is wrapped once, in order to avoid wrinkles and uneven appearance defects in the composite material tie rod. Moreover, there are temperature and humidity requirements during the application of prepreg and adhesive film: temperature 22℃±4℃ and relative humidity ≤65%.

[0025] Furthermore, the prepreg is carbon fiber prepreg, and the vacuum accessories are breathable felt, vacuum bags, and sealing tape.

[0026] Furthermore, the curing equipment for the first curing described in S2 is an oven or curing furnace, which does not apply pressure during curing; or an autoclave is used, which applies pressure during curing.

[0027] Furthermore, the curing equipment for the second curing described in S4 is an autoclave, which is used to pressurize the curing process.

[0028] Compared with existing technologies, this invention can successfully manufacture composite material tie rods. The composite material tie rod is thinner at both ends and thicker in the middle, meeting shape requirements, and its outer surface is smooth and flat, making it both aesthetically pleasing and practical. The composite material tie rod contains no other materials besides the composite material and the metal embedded parts themselves, making it lightweight and meeting weight reduction requirements. The inner holes at both ends of the composite material tie rod have metal threads that are coaxial, and the metal embedded parts at both ends are firmly connected to the composite material, preventing them from easily loosening. This allows it to withstand large tensile / compressive loads, meeting functional requirements. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a finished composite material tie rod produced according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic cross-sectional view of the finished composite material tie rod produced according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of a metal embedded part according to an embodiment of the present invention;

[0032] Figure 4 This is a schematic cross-sectional view of a metal embedded part according to an embodiment of the present invention;

[0033] Figure 5 This is a schematic diagram of a core mold according to an embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram of a positioning mold according to an embodiment of the present invention;

[0035] Figure 7 This is a schematic cross-sectional view of the positioning mold according to an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of a soluble mold according to an embodiment of the present invention;

[0037] Figure 9 This is a schematic cross-sectional view of a soluble mold according to an embodiment of the present invention;

[0038] Figure 10 This is a schematic diagram of the composite material tie rod after assembly with the metal embedded part according to an embodiment of the present invention.

[0039] Figure 11 This is a schematic diagram showing the assembly of the molding die and the metal embedded part of the composite material tie rod according to an embodiment of the present invention.

[0040] Figure 12 This is an enlarged view of part A of the cross-sectional schematic diagram of the composite material tie rod after assembly with the molding die and the metal embedded part according to an embodiment of the present invention;

[0041] Figure 13 This is a schematic diagram of the product and mold state after the first curing according to an embodiment of the present invention;

[0042] The reference numerals in the above figures are as follows: 1. Metal embedded part; 2. Composite material tie rod; 3. Internal thread; 4. Positioning boss; 5. Inner recess; 6. Inclined platform; 7. Limiting circular hole; 8. Core mold; 801 first fixing hole; 9. Positioning mold; 901 second fixing hole; 902 positioning groove; 903 mounting inner hole; 10. Soluble mold; 1001 ramp; 1002 limiting protrusion; 1003 axial circular through hole; 11. Pin; 12. Composite material blank. Specific Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0045] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0046] Reference Figure 1-13 The image shown is a preferred embodiment of the present invention.

[0047] The molding die for the composite material tie rod 2 includes a soluble mold 10, a core mold 8, and a positioning mold 9. The positioning mold 9 is fixed to the core mold 8 using pins 11. The soluble mold 10 is fitted onto the core mold 8. There are two positioning molds 9 (assembly diagram shown). Figure 10-12 (as shown)

[0048] like Figure 8 As shown in / 9, the soluble mold 10 is a tubular structure with an axial circular through hole 1003, and both ends of the soluble mold 10 are provided with inclined slopes 1001 in the axial direction, and each end of the two inclined slopes 1001 is provided with a limiting boss, and each of the two limiting bosses is connected to a metal embedded part 1.

[0049] like Figure 5 As shown, the core mold 8 is a cylinder with fixing holes at both ends. The core mold 8 passes through the axial circular through hole 1003 of the soluble mold 10, and both ends of the core mold 8 extend to the outside of the soluble mold 10. A first fixing hole 801 is also opened at each end of the core mold 8. Each end of the soluble mold 10 is fixed to the core mold 8 by a positioning mold 9. When each positioning mold 9 is fixed to the core mold 8, the metal embedded part 1 is located between the soluble mold 10 and the positioning mold 9.

[0050] The positioning mold 9 has an axially penetrating mounting inner hole 903, and the core mold 8 passes through the mounting inner hole 903 and is connected to it. The positioning mold 9 also has a second fixing hole 901 that is perpendicular to the axis. When the positioning mold 9 is connected to the core mold 8, the first fixing holes 801 at both ends of the core mold 8 are connected to the second fixing holes 901 of the positioning mold 9 by pins 11. The pins 11 pass through the first fixing holes 801 and the second fixing holes 901.

[0051] like Figure 3As shown in / 4, the metal embedded part 1 has an axial through hole. The outer surface of the metal embedded part 1 is provided with a positioning boss 4. One end of the through hole with the positioning boss 4 is provided with an internal thread 3. The outer surface of the middle end of the metal embedded part 1 is provided with a ring of inward groove 5. The outer surface of the other end of the metal embedded part 1 is provided with an inclined platform 6 that is inclined away from the axis, and a limiting circular hole 7 is formed at the through hole of the inclined platform 6.

[0052] like Figure 6 As shown in Figure 7, a positioning groove 902 is formed at one end of the mounting inner hole 903 of the positioning mold 9. The positioning groove 902 cooperates with the positioning boss 4 of the metal embedded part 1. The limiting boss on the soluble mold 10 is inserted into the limiting round hole 7 of the metal embedded part 1.

[0053] A method for molding composite material tie rod 2 is provided, including the following steps:

[0054] S1, the outer surfaces of the two metal embedded parts 1 are knurled and sandblasted, and a sealing agent is sprayed on the outer surface of the soluble mold 10 (the soluble mold 10 is a water-soluble mold, and the sealing agent is a water-soluble sealing agent. The purpose of spraying the sealing agent is to prevent the resin from entering the pores of the soluble mold 10 when the prepreg is cured. If the resin enters the pores of the soluble mold 10, the soluble mold 10 will not be able to dissolve). The soluble mold 10 and the two metal embedded parts 1 are installed on the core mold 8, and the two positioning molds 9 are fixed to both ends of the core mold 8 with steel pins 11.

[0055] S2, First application: Apply the adhesive film to the outer surface of the metal embedded part 1, apply a small amount of prepreg to the outer surface of the metal embedded part 1 and the outer surfaces of both ends of the exposed soluble mold 10, wrap the whole with BOPP tape, wrap with breathable felt, vacuum seal with vacuum bags and sealing tape, and then put it into the curing equipment for the first curing.

[0056] S3, remove the vacuum auxiliaries and BOPP tape, without demolding, roughen the area after the prepreg has cured, to obtain an intermediate product with composite material blanks 10 at both ends, such as... Figure 13 As shown;

[0057] S4, Second application: Apply the adhesive film to the outer surface of the composite material blank 12, apply the prepreg to the outer surface of the composite material blank 12 and the exposed soluble mold 10, then wrap the entire surface with BOPP tape, wrap with breathable felt, vacuum seal with vacuum bags and sealing tape, and then put it into the curing equipment for a second curing.

[0058] S5, remove the positioning mold 9 from the core mold 8, remove the core mold 8, remove the vacuum auxiliary material and BOPP tape from the product surface, dissolve the soluble mold 10 and sealing agent (the soluble mold 10 and sealing agent are dissolved in water), polish the outer surface of the product to a smooth finish, remove excess resin, and obtain the composite material tie rod 2, as shown. Figure 1 , 2 As shown.

[0059] The reason for using a two-stage application and two-stage curing method is that gaps cannot be completely avoided at the junction of the metal embedded part 1 and the water-soluble mold. Because of these gaps, resin can easily flow into them during curing, causing a depression at the junction of the composite tie rod 2 after curing. If a single-stage application and curing method were used, the composite tie rod 2 would suffer from poor appearance and insufficient strength due to the above reasons. Therefore, by performing the first application and first curing, the depression appears after the first curing. During the second application, after applying the adhesive film, the depression is first filled with prepreg before the entire prepreg is applied. This ensures that the composite tie rod 2 will not have a depression after the second curing and will meet the required strength.

[0060] It should be noted that because the number of prepreg layers in the first curing is relatively small, the first curing pressure is the vacuum pressure (approximately 0.092 MPa) to ensure product quality. Curing can be done using a curing oven, and there is no need to use an autoclave for additional pressure. Of course, using an autoclave for additional pressure or...

[0061] Because there are many layers of prepreg, the second curing process requires pressurization using an autoclave at a pressure of 0.5~0.6MPa, in addition to the vacuum pressure (approximately 0.092MPa), to ensure product quality.

[0062] The first and second curing temperatures are determined based on the type of resin in the prepreg. If the resin is a medium-temperature curing system, the curing temperature is required to be 120℃ (±5℃). If the resin is a high-temperature curing system, the curing temperature is required to be 180℃ (±5℃).

[0063] The outer surface of the metal embedded part 1 laid for the first time in S2 is the outer surface of the inner side of the positioning boss 4 of the metal embedded part 1, excluding the positioning boss 4.

[0064] During the second paving process in S4, prepreg is used to gradually fill the inward groove 5 in the middle of the metal embedded part 1.

[0065] During the first and second application processes, in addition to proper overlap after wrapping the prepreg once, excess prepreg should be cut off to ensure that each piece of prepreg is wrapped once, in order to avoid wrinkles and uneven appearance defects in the composite tie rod. There are temperature and humidity requirements during the application of prepreg and adhesive film: temperature 22℃±4℃, relative humidity ≤65%. Other operations (excluding curing) do not have strict temperature and humidity requirements: temperature 15℃~32℃, relative humidity ≤75%.

[0066] The prepreg is carbon fiber prepreg, and the vacuum accessories are breathable felt, vacuum bags and sealing tape.

[0067] The first curing in S2 is performed in an oven or curing furnace without pressurization; or an autoclave is used with pressurization during curing.

[0068] The second curing process in S4 uses an autoclave, which is pressurized during curing.

[0069] The composite material tie rod 2 can be successfully prepared using the above method. The composite material tie rod 2 is thin at both ends and thick in the middle, which meets the shape requirements. The outer surface of the composite material tie rod 2 is flat and smooth, which is both beautiful and practical. The composite material tie rod 2 contains no other materials besides the composite material and the metal embedded part 1 itself, so it is lightweight and meets the requirements for lightweighting. The inner holes at both ends of the composite material tie rod 2 have metal threads and the metal threads at both ends are coaxial. The metal embedded part 1 at both ends of the composite material tie rod 2 is firmly connected to the composite material and is not easy to loosen. It can withstand large tensile / compressive loads and meets the functional requirements.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A forming die for a composite rod, characterized by, The forming mold comprises a soluble mold, a core mold and a positioning mold; The soluble mold is a tubular structure with an axial circular through hole, and both ends of the soluble mold are provided with slopes inclined to the axial direction, and both ends of the two slopes are respectively provided with a limiting boss, and the two limiting bosses are respectively connected with a metal embedded part; The core mold is a cylinder provided with fixing holes at both ends, the core mold passes through the axial circular through hole of the soluble mold, and both ends of the core mold extend to the outside of the soluble mold, and both ends of the core mold are respectively provided with a first fixing hole penetrating through; Both ends of the soluble mold are fixed with the core mold through the positioning mold, wherein when each positioning mold is fixed with the core mold, the metal embedded part is located between the soluble mold and the positioning mold; The positioning mold is provided with an axial through mounting inner hole, and the core mold passes through the mounting inner hole and is connected with the mounting inner hole, and the positioning mold is provided with a second fixing hole perpendicular to the axial line, and when the positioning mold is connected with the core mold, the first fixing hole at both ends of the core mold is connected with the second fixing hole of the positioning mold through a pin, and the pin passes through the first fixing hole and the second fixing hole.

2. The forming die for composite material pull rods according to claim 1, characterized in that, The metal embedded part is provided with an axial through hole, the outer surface of the metal embedded part is provided with a limiting boss, one end of the through hole provided with the limiting boss is provided with an internal thread, the outer surface of the middle end of the metal embedded part is provided with a ring-shaped recess, and the outer surface of the other end of the metal embedded part is provided with a slope away from the axial direction, and the through hole at the slope forms a limiting circular hole; One end of the mounting inner hole of the positioning mold forms a limiting recess, and the limiting recess is matched with the limiting boss of the metal embedded part; The limiting boss of the soluble mold is inserted into the limiting circular hole of the metal embedded part.

3. The forming die for composite material pull rods according to claim 2, characterized in that, The soluble mold is a water-soluble mold.

4. A method of forming a composite rod, characterized by, The forming mold of claim 3 comprises the following steps: S1, the outer surface of the two metal embedded parts is knurled and sandblasted, the outer surface of the soluble mold is sprayed with a hole sealing agent, the soluble mold and the two metal embedded parts are installed on the core mold, and the two positioning molds are fixed on both ends of the core mold using steel pins; S2, first paving: the adhesive film is paved on the outer surface of the metal embedded part, a small amount of prepreg is paved on the outer surface of the metal embedded part and the outer surface of the exposed soluble mold at both ends, the whole is wrapped with BOPP tape, wrapped with air-permeable felt, vacuum packaged with a vacuum bag and sealing tape, and then placed in a curing device for first curing; S3, remove the vacuum accessories and BOPP tape, do not demold, polish the area of the cured prepreg to be rough, and obtain an intermediate product with composite material blanks at both ends; S4, second paving: the adhesive film is paved on the outer surface of the composite material blank, the prepreg is paved on the outer surface of the composite material blank and the exposed soluble mold, and the whole is wrapped with BOPP tape, wrapped with air-permeable felt, vacuum packaged with a vacuum bag and sealing tape, and then placed in a curing device for second curing; S5, remove the positioning mold from the core mold, take out the core mold, remove the vacuum accessories and BOPP tape on the surface of the product, dissolve the soluble mold and the hole sealing agent, polish the outer surface of the product to be smooth, remove the excess resin, and obtain a composite material pull rod.

5. The method of forming a composite rod according to claim 4, wherein, The outer surface of the metal embedded part in the first paving in S2 is the outer surface of the inner side of the positioning boss of the metal embedded part, and does not include the positioning boss.

6. The method of forming a composite rod according to claim 5, wherein, In the second paving in S4, the inner recess of the middle part of the metal embedded part is gradually filled and flattened by using the prepreg.

7. The method of forming a composite rod according to claim 6, wherein, In the first paving and the second paving, the prepreg is cut off except for the proper lap after being wrapped around once, so that each piece of prepreg is wrapped around once, to avoid the generation of wrinkles and uneven appearance of the composite material pull rod, and there are temperature and humidity requirements in the paving process of the prepreg and the adhesive film, the temperature is 22℃±4℃, and the relative humidity is less than or equal to 65%.

8. The method of forming a composite rod according to claim 7, wherein, The prepreg is carbon fiber prepreg, and the vacuum auxiliary material is air-permeable felt, a vacuum bag and a sealing tape.

9. The method of forming a composite rod according to claim 8, wherein, The curing equipment for the first curing in S2 is an oven or a curing furnace, and no pressure is applied during curing; or a hot press tank is used, and the hot press tank is used for pressure during curing.

10. The method of forming a composite rod according to claim 9, wherein, The curing equipment for the second curing in S4 is a hot press tank, and the hot press tank is used for pressure during curing.

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