A compression molding method for hexahedral carbon fiber beams

Abstract

The present invention discloses a compression molding method for a hexahedral carbon fiber beam, comprising the following steps: preparing a first molding die, a second molding die and prepreg; installing a glass fiber prefabricated block equipped with a core shaft on the first molding die, laying material sheets on the upper side of the molding template according to a laying order, removing the mold after the laying is completed, and obtaining the entire length portion of the carbon beam fiber; tightly aligning the entire length portion of the carbon beam fiber to obtain a carbon beam preform; installing the carbon beam preform in a second molding die; laying material sheets on the front and back sides of the carbon beam preform according to a laying order; removing the mold, removing the carbon beam blank, and trimming the shape; installing the trimmed carbon beam blank in the second molding die for local filling; closing the mold and curing; using the present invention, a hexahedral carbon fiber beam can be reliably prepared, and most of the carbon fibers in the prepared carbon fiber beam are in a straight and non-tight state, thereby reducing local stress concentration and making the load evenly distributed on the carbon fiber beam.

Description

Technical Field

[0001] The invention relates to the technical field of composite material preparation, in particular to a compression molding method for a hexahedral carbon fiber beam. Background Art

[0002] The prior art discloses a method named "A carbon beam mold and a method for preparing a carbon beam", with publication number CN111284046 A and publication date 2020.06.16. The shape of the carbon beam is a "U"-shaped long strip with a circular hole at the end of the "U". The long strip part has a torsion angle. The forming mold is a base and a long strip mold with the same torsion angle as the carbon beam. The long strip mold is fixed on the base. The overall appearance of the carbon beam is relatively flat and is formed in an autoclave, which is suitable for the manufacture of large fan blades.

[0003] Carbon beams are the main load-bearing structural components in various blades and propellers, and are required to have high precision, high strength and good aerodynamic performance. However, the carbon fiber beams suitable for the rotor system blades of a helicopter are hexahedral, with different surface features on each side and a torsion angle. The above method for preparing carbon beams cannot reliably prepare hexahedral carbon fiber beams. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] In view of the above problems and / or problems existing in the preparation of existing carbon fiber beams, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to provide a molding method for a hexahedral carbon fiber beam. The present invention can reliably prepare a hexahedral carbon fiber beam. Most of the carbon fibers in the prepared carbon fiber beam are in a straight and loose state, reducing local stress concentration and making the load evenly distributed on the carbon fiber beam.

[0007] To solve the above technical problems, the present invention provides the following technical solution: a method for compression molding a hexahedral carbon fiber beam, comprising the following steps:

[0008] S1. Prepare a first molding die and a second molding die. The first molding die includes a molding template and a detachable vertical plate. The molding template has a plurality of plug holes arranged on an upward end. The detachable vertical plate has a plurality of plug portions arranged on a bottom portion thereof, each corresponding to the plug holes. The molding template has a plurality of first limiting holes formed on one side of the plug portions in the longitudinal direction.

[0009] S2. Take out the prepreg stored in the cold storage in advance and leave it for a set time until there is no moisture on the surface of the sealed bag and it is ready for use;

[0010] S3. Import the designed blanking drawing into the blanking machine supporting software, use the blanking machine to cut the prepreg into the process design shape, sort the pieces in order according to the number, place the sorted pieces in the order of the numbers, and use vacuum bag packaging for storage;

[0011] S4. Lay release cloth on the front and rear sides of the detachable vertical plate, respectively. Install the glass fiber prefabricated block with the mandrel mounted on it on the first forming mold, align the mandrel with the corresponding first limiting hole, insert the first positioning pin into the through hole of the mandrel and then into the first limiting hole, lay the sheet material on the upper side of the forming template in the laying order, and pre-vacuum it according to the set pre-vacuum treatment process during the laying process. After all the sheets are laid, loosen the two sides of the central detachable vertical plate and pull it upward to obtain the full-length portion of the carbon beam fiber.

[0012] S5. Tightly align all the full-length portions of the carbon beam fibers, and perform a pre-vacuum treatment after the alignment is completed to obtain a carbon beam preform;

[0013] S6. Remove the second positioning pin from the second forming die, place the carbon beam preform into the die cavity of the second forming die, insert the second positioning pin into the mandrel and the second limiting hole of the second forming die, and complete the positioning of the carbon beam preform in the second forming die;

[0014] S7. Lay the carbon fiber sheets on the second forming molds on the front and rear sides of the carbon beam preform in a layup order. During the layup process, vacuum is applied according to the set pre-vacuuming process. After the layup is completed, check that there is no obvious height difference between the carbon fiber strips in the local full-length portion and the carbon beam preform, and then perform pre-vacuuming again.

[0015] S8, remove the components in the second forming mold, remove the carbon beam blank, determine whether it needs to be repaired, and then clean the surface of each component in the second forming mold and apply a release agent;

[0016] S9. Install the trimmed carbon beam blank and various components into the second forming die one by one, perform partial filling, and fill the entire die with 3-5 layers of unidirectional strips;

[0017] S10, close the mold, hoist the mold to the hot press platform, and solidify;

[0018] S11, after curing is completed, the mold is removed and the preformed carbon beam is taken out;

[0019] S12. Perform excess removal according to the process marking lines of the carbon beam, and polish off excess resin or fiber burrs to obtain a carbon fiber beam.

[0020] As a further improvement of the present invention, in step S4, the pre-vacuum treatment process is to perform pre-vacuum treatment once on the first layer of paving, and then perform pre-vacuum treatment once every 10-15 layers and the last layer. The pre-vacuum time is not less than 15 minutes, and the pre-vacuum timing is based on the vacuum degree in the vacuum bag not being higher than -0.85MPa.

[0021] As a further improvement of the present invention, in step S5, when aligning, a layer of medium-temperature epoxy film is laid on the aligning surface of the entire fiber length portion of the carbon beam to fill the aligning gap; when the aligning is completed and pre-vacuumed, the pre-vacuum time is not less than 15 minutes, and the pre-vacuum timing is based on the vacuum degree in the vacuum bag not being higher than -0.85MPa.

[0022] As a further improvement of the present invention, the second forming mold includes a lower mold with an upward mold cavity and an upper mold detachably connected to the upper side of the lower mold, and a compacting molding part adapted to the shape of the upper surface of the carbon fiber beam is fixed on the lower side of the upper mold, and a second limiting hole corresponding to the core shaft is opened on the lower mold, and the lower part of the second locating pin can be just inserted into the second limiting hole, and the front and rear sides of the center in the front-to-back direction of the lower mold are respectively detachably connected to the first long insert and the second long insert, and the lower mold between the front side of the first long insert and the rear side of the inner wall of the front end of the lower mold is detachably connected to the first slider and the second slider arranged at intervals in the left and right directions, and the lower mold between the rear side of the second long insert and the front side of the inner wall of the rear end of the lower mold is detachably connected to the third slider and the fourth slider arranged at intervals in the left and right directions. When the first slider and the second slider are pushed downward, the first long insert moves horizontally toward the direction of the center in the front-to-back direction of the lower mold, and when the third slider and the fourth slider are pushed downward, the second long insert moves horizontally toward the direction of the center in the front-to-back direction of the lower mold.

[0023] As a further improvement of the present invention, the rear sides of the first slider and the second slider each have a first inclined surface inclined from top to bottom toward the direction of the inner wall of the front end of the lower mold, and the first slider and the second slider can be respectively attached to the front side of the first long insert through the first inclined surface, and the front sides of the third slider and the fourth slider each have a second inclined surface inclined from top to bottom toward the direction of the inner wall of the rear end of the lower mold, and the third slider and the fourth slider can respectively be attached to the rear side of the second long insert through the second inclined surface.

[0024] As a further improvement of the present invention, a short insert is detachably connected to the lower mold on the left side of the first long insert, and a short slider is detachably connected to the lower mold between the short insert and the inner wall of the left end of the lower mold. The right side of the short slider has a third inclined surface inclined from top to bottom toward the direction of the inner wall of the right end of the lower mold, and the short slider can be attached to the left side of the short insert through the third inclined surface.

[0025] As a further improvement of the present invention, the specific steps of laying the sheet in step S7 are:

[0026] The strips of material laid on the lower molds on the front and rear sides of the carbon beam preform are laid flatly in the horizontal direction to fill the remaining mold cavity space in the 0° direction;

[0027] When the material strips are laid to a certain thickness, the first and second long inserts are placed in the lower molds on the front and rear sides of the carbon beam preform respectively. Initially, the front side of the first long insert is against the inner wall of the front end of the lower mold, and the rear side of the second long insert is against the inner wall of the rear end of the lower mold. The material strips are trimmed and laid along the rear side of the first long insert and the front side of the second long insert to ensure that there is no interference after the long inserts and sliders are installed.

[0028] After the mold trimming is completed, the long inserts, sliders, and the first connecting pins on the sliders are placed separately. Soft rubber pads are placed in the lower mold to raise each slider 1-2mm above the upper edge of the lower mold. The soft rubber pads are placed in the position without the first connecting pin.

[0029] After installation, continue to lay the material strips in the order of laying. Use a flat rolling board to pre-compact each layer. Arrange vacuum equipment and perform pre-vacuum treatment every 3-5mm thickness until all the material strips are laid.

[0030] As a further improvement of the present invention, the time for the pre-vacuum treatment is not less than 30 minutes, and the pre-vacuum timing is set so that the vacuum degree in the vacuum bag is not higher than -0.85 MPa.

[0031] As a further improvement of the present invention, the step S9 is specifically as follows: the carbon beam blank, the first long insert, the second long insert, each soft rubber pad, each slider and the first connecting pin of the slider are installed into the lower mold one by one, and the upper side of each slider exceeds the upper edge height of the lower mold by 1-2 mm; in step S10, during molding and curing, the molding machine presses down the upper mold so that each slider pushes the corresponding insert to apply force toward the center of the carbon beam to ensure that each insert is in place during curing.

[0032] As a further improvement of the present invention, in step S11, the layout of demolding is to take out each second connecting pin connecting the upper mold and the lower mold, use a mold opening tool to apply force upward evenly, pry until it is loose, lift and remove the upper mold, use a screw tool to apply force upward on the first to fourth sliders until it is loose, take out each slider, loosen each insert in the direction away from the carbon fiber beam, and take out the carbon fiber beam.

[0033] Compared with the prior art, the present invention has the following technical effects: in the present invention, the preforming of the complete full-length portion of the carbon fiber is first completed with the help of a first forming mold, and the complete full-length portion of the carbon fiber is located in the middle position, and the high strength and high compressive resistance of the carbon fiber are used to bear the main tensile load, thereby ensuring the overall stiffness and stability of the carbon beam; single-sided carbon fiber local full-length portions are prepared on both sides of the complete normal portion of the carbon fiber, and when assembly and repair with other parts are needed, the focus can be on the side carbon fiber local full-length portions, thereby ensuring the continuity of the entire full length to the maximum extent and reducing the loss of tensile strength; the carbon fiber beam prepared using the present invention can effectively ensure that most of the carbon fibers are in a straight and non-tight state, reduce local stress concentration, and make the load evenly distributed on the carbon beam; the present invention is simple to manufacture, has low forming difficulty, and improves the consistency and reliability of carbon beam forming; and can be applied to the preparation of hexahedral carbon fiber beams. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0035] Figure 1 It is a three-dimensional structural diagram of the first molding die in the present invention.

[0036] Figure 2 This is an exploded view when the detachable vertical plate is not inserted into the molding die body.

[0037] Figure 3 This is a top view of the entire carbon beam fiber section before demolding after all layers are laid.

[0038] Figure 4 It is the front view of the second forming mold in the present invention.

[0039] Figure 5 This is an exploded schematic diagram of the second molding die when the upper die is not closed on the lower die.

[0040] Figure 6 This is a cross-sectional view of the first slider in the second molding die.

[0041] Figure 7 This is a top view of the lower mold at the end of step S8.

[0042] In the figure: 1 first molding die, 101 molding template, 101-1 plug hole, 101-2 first limiting hole, 102 detachable vertical plate, 102-1 plug part, 103 first positioning pin, 2 second molding die, 201 lower die, 201-1 lower positioning hole, 202 upper die, 202-1 compaction molding part, 202-2 upper positioning hole, 203 second slider, 204 first slider, 205 second connecting pin, 206 short insert, 207 short slider, 208 third slider, 209 fourth slider, 210 first connecting pin, 211 second long insert, 212 first long insert, 213 second positioning pin, 3 core shaft, 4 glass fiber prefabricated block, 5 carbon beam fiber full-length portion, 6 carbon fiber partial full-length portion, X second inclined surface, S fourth inclined surface. DETAILED DESCRIPTION

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0045] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments. Example 1

[0046] Reference Figure 1 and 2 , which is the first embodiment of the present invention, provides a molding method for a hexahedral carbon fiber beam. The present invention can reliably produce a hexahedral carbon fiber beam.

[0047] A compression molding method for a hexahedral carbon fiber beam comprises the following steps:

[0048] S1. Prepare a first molding die and a second molding die. The first molding die includes a molding template and a detachable vertical plate. The molding template has a plurality of plug holes arranged on an upward end. The detachable vertical plate has a plurality of plug portions arranged on a bottom portion thereof, each corresponding to the plug holes. The molding template has a plurality of first limiting holes formed on one side of the plug portions in the longitudinal direction.

[0049] S2. Take out the prepreg stored in the cold storage in advance and place it outside for at least 6 hours. When there is no moisture on the surface of the sealed bag, it is ready for use;

[0050] S3. Import the designed blanking drawing into the blanking machine supporting software, use the blanking machine to cut the prepreg into the process design shape, sort the blanks in order according to the number, check whether the blanks are complete and undamaged, and compare them with the electronic blanking drawing to see if there are any missing blanks or obvious blank cutting errors. For problematic blanks, find the blanking drawing number and re-cut them. Clean up any white or blue film debris on the edge of the blank in time. Place the sorted blanks in the order of the number and seal them in vacuum bags for storage;

[0051] S4. Grind the surfaces of the two mandrels and the glass fiber prefabricated block with coarse sandpaper, clean them with acetone, and lay a layer of medium-temperature epoxy film on them. Perform pre-vacuum treatment. After the treatment is completed, install the two mandrels and the glass fiber prefabricated block on the forming template. The two mandrels are respectively inserted into the connecting holes of the glass fiber prefabricated block. Use the first positioning pin to insert the through hole of the mandrel and then insert it into the first limiting hole. The tip of the glass fiber prefabricated block is against the left side of the detachable vertical plate (such as Figure 3 As shown in the figure), release cloth is laid on the front and back sides of the detachable vertical plate respectively, and the material sheet is laid on the upper side of the forming template in the order of laying. Pre-vacuum treatment is performed on the first layer of laying, and then every 10-15 layers and the last layer. The pre-vacuum treatment time is not less than 15 minutes. The pre-vacuum timing is that the vacuum degree in the vacuum bag is not higher than -0.85MPa. After all the laying is completed, loosen the two sides of the central detachable vertical plate and pull it upward to obtain the full-length part of the carbon beam fiber. After disassembly, the full-length part of the carbon beam fiber can remain vertical and not fall down;

[0052] S5. Tightly align all the full-length sections of the carbon beam fibers, perform a pre-vacuum treatment after alignment, observe the surface condition of the carbon beam after pre-vacuum treatment, and fill and trim any gaps with unidirectional material strips or adhesive films to obtain a carbon beam preform;

[0053] S6. Remove the second positioning pin from the second forming die, place the carbon beam preform into the die cavity of the second forming die, insert the second positioning pin into the mandrel and the second limiting hole of the second forming die, and fit the right side of the carbon beam preform against the inner wall of the right end of the second forming die, thereby completing the positioning of the carbon beam preform in the second forming die.

[0054] S7. Lay the carbon fiber strips on the second forming molds on the front and rear sides of the carbon beam preform in a layup order. During the layup process, vacuum is performed according to the set pre-vacuuming process. After the layup is completed, check that there is no obvious height difference between the carbon fiber strips of the local full-length portion (the strips laid on the front and rear sides of the carbon beam preform are collectively referred to as the local full-length portion of carbon fiber) and the carbon beam preform, and then perform pre-vacuuming again.

[0055] S8. Remove all components from the second forming mold, remove the existing carbon beam blank and weigh it to determine whether it needs to be reshaped. After reshaped, weigh the carbon beam blank and the remaining material again to control the weight to be within the theoretical weight of 1g-5g. Then, clean the surface of all components in the second forming mold and apply a release agent.

[0056] S9. Install the trimmed carbon beam blank and various components into the second forming die one by one, perform partial filling, and fill the entire die with 3-5 layers of unidirectional strips;

[0057] S10, close the mold, hoist the mold to the hot press platform, and solidify;

[0058] S11, after curing is completed, the mold is removed and the preformed carbon beam is taken out;

[0059] S12. Perform excess removal according to the process marking lines of the carbon beam, and polish off excess resin or fiber burrs to obtain a carbon fiber beam.

[0060] After the repair is completed, the quality inspectors will inspect the parts according to the relevant inspection standards and record them. The inspection includes:

[0061] Appearance inspection: Visually inspect the surface quality to check whether there are pits, wrinkles, deformations, bumps, glue accumulation and stains on the surface;

[0062] Nondestructive testing: Ultrasonic testing of composite rods is performed in accordance with GJB 1038.1A-2004 "Nondestructive testing methods for fiber-reinforced composite materials - Part 1: Ultrasonic testing" to examine the types and distribution of defects such as porosity, delamination, debonding, inclusions, and looseness, as well as the area and size of debonding defects.

[0063] Weighing: Use an electronic scale to weigh the carbon beam and record the weight.

[0064] Products that pass the above tests without any problems are considered qualified products.

[0065] When laying the material strips, the lower mold is placed on a heating platform at 45°C to ensure that the prepregs fit tightly and reduce the gap between layers.

[0066] Before curing, place the thermocouple according to the thermocouple placement position marked on the second molding die, and stick the thermocouple with a medium-temperature sealing strip.

[0067] The solidification system is:

[0068] 1) With an initial pressure of 8MPa±0.1MPa, heat the mold to 80℃±5℃ at a heating rate of no more than 1.5℃ / min. Keep it at this temperature for 30min±5min, then check the mold clearance. If the clearance is greater than 0.3mm, open the mold to check the mold edge and perform trimming. If the clearance is ≤0.3mm, continue heating and curing.

[0069] 2) The pressure is 10MPa±0.1MPa, and the heating rate is no more than 1.5℃ / min. The temperature can be further raised to 135℃±5℃, and kept at this temperature for 180±10min; then the mold is cooled to below 45℃ at a cooling rate of no more than 2℃ / min before the mold can be opened.

[0070] The curing temperature is based on the thermocouple.

[0071] In the present invention, the preforming of the complete full-length portion of the carbon fiber is first completed with the help of a first forming mold. The complete full-length portion of the carbon fiber is located in the middle position, and the high strength and high compressive resistance of the carbon fiber are used to bear the main tensile load, thereby ensuring the overall rigidity and stability of the carbon beam; single-sided carbon fiber partial full-length portions are respectively prepared on both sides of the complete normal portion of the carbon fiber, and when assembly and repair with other parts are needed, the focus can be on the side carbon fiber partial full-length portion, thereby ensuring the continuity of the entire full length to the maximum extent and reducing the loss of tensile strength; the carbon fiber beam prepared using the present invention can effectively ensure that most of the carbon fibers are in a straight and non-tight state, reduce local stress concentration, and make the load evenly distributed on the carbon beam; the present invention is simple to manufacture, has low forming difficulty, and improves the consistency and reliability of carbon beam forming. Example 2

[0072] like Figures 1 to 7 , which is the second embodiment of the present invention, and this embodiment provides a compression molding method for a hexahedral carbon fiber beam, which further realizes the preparation of the carbon fiber beam.

[0073] Specifically, the second molding die includes a lower die with an upward mold cavity and an upper die detachably connected to the upper side of the lower die, a compacting and molding part adapted to the shape of the upper surface of the carbon fiber beam is fixed on the lower side of the upper die, the compacting and molding part has two jacks corresponding to the core shaft one by one, a plurality of lower positioning holes are opened on the lower die, a plurality of upper positioning holes corresponding to the lower positioning holes are opened on the upper die, a second limiting hole corresponding to the core shaft one by one is opened on the lower die, the lower part of the second positioning pin can be just inserted into the second limiting hole, and a first long insert and a second long insert are respectively placed in front and behind the center in the front-to-back direction of the lower die, and the first long insert The right side of the second long insert is in contact with the inner wall of the right end of the lower mold, and the first slider and the second slider arranged at intervals in the left and right directions are detachably connected to the lower mold between the front side of the first long insert and the rear side of the inner wall of the front end of the lower mold, and the third slider and the fourth slider arranged at intervals in the left and right directions are detachably connected to the lower mold between the rear side of the second long insert and the front side of the inner wall of the rear end of the lower mold. When the first slider and the second slider are pushed downward, the first long insert moves horizontally toward the center of the lower mold in the front and rear directions, and when the third slider and the fourth slider are pushed downward, the second long insert moves toward the front and rear directions of the lower mold. The first and second sliders are respectively fitted with the front side of the first long insert via the first inclined surface, and the front sides of the third and fourth sliders are respectively fitted with the rear side of the second long insert via the second inclined surface; a short insert is detachably connected to the lower mold on the left side of the first long insert, and the lower mold between the short insert and the inner wall of the left end of the lower mold is provided with a first inclined surface. A short slider is detachably connected to the mold, and there is a disassembly gap between the short slider and the inner wall of the lower mold. The right side of the short slider has a third inclined surface inclined from top to bottom toward the direction of the inner wall of the right end of the lower mold, and the short slider can be fitted on the left side of the short insert through the third inclined surface; the short slider, the first slider and the second slider are all connected with a number of first connecting pins that can move up and down, and the bottom of the lower mold is provided with a number of third limiting holes corresponding to the first connecting pins. Through the first connecting pins and the third limiting holes, after the first connecting pins are installed on the lower mold and each slider, the slider can only move up and down, so that the corresponding slider is accurately positioned.

[0074] The specific steps of laying the sheet in step S7 are:

[0075] The strips of material laid on the lower molds on the front and rear sides of the carbon beam preform are laid flatly in the horizontal direction to fill the remaining mold cavity space in the 0° direction;

[0076] When the thickness is 2-5 mm, the first and second long inserts are placed in the lower molds on the front and rear sides of the carbon beam preform respectively. Initially, the front side of the first long insert is against the inner wall of the front end of the lower mold, and the rear side of the second long insert is against the inner wall of the rear end of the lower mold. The laid material strip is trimmed along the rear side of the first long insert and the front side of the second long insert. Then, the first long insert is moved backward and the second long insert is moved forward a set distance. Then, trimming is performed along the rear side of the first long insert and the front side of the second long insert until there is no interference after the installation of each long insert and the slider.

[0077] After the mold trimming is completed, the long inserts, sliders, and the first connecting pins on the sliders are placed separately. Soft rubber pads are placed in the lower mold to raise each slider 1-2mm above the upper edge of the lower mold. The soft rubber pads are placed in the position without the first connecting pin.

[0078] After the installation is completed, continue to lay the material strips in the order of laying, use a flat rolling board to pre-compact each layer, and arrange the vacuum equipment every 3-5mm thickness (this is a conventional technology, not an improvement point of this application, and the arrangement process does not need to be described in detail), and perform a pre-vacuum treatment until all the material strips are laid. The pre-vacuum treatment time is not less than 30 minutes, and the pre-vacuum timing is based on the vacuum degree in the vacuum bag not being higher than -0.85MPa.

[0079] Specifically, step S9 includes inserting the carbon beam blank, the first long insert, the second long insert, each soft rubber pad, each slider and the first connecting pin of the slider into the plug hole of the lower mold one by one, and the upper side of each slider exceeds the upper edge of the lower mold by 1-2 mm; in step S10, during molding and curing, the molding machine presses down the upper mold so that each slider pushes the corresponding insert to apply force toward the center of the carbon beam to ensure that each insert is in place during curing.

[0080] In step S11, the layout of the mold removal is to take out the second connecting pins connecting the upper mold and the lower mold, use the mold opening tool to apply force upward evenly, pry until it is loose, then lift and remove the upper mold, use the screw tool to apply force upward on the first to fourth sliders and the short slider respectively until they are loose, take out each slider, loosen each insert in the direction away from the carbon fiber beam, and take out the carbon fiber beam.

[0081] The excess is removed according to the process markings of the carbon beam, and the excess resin or fiber flash is polished off.

[0082] Through this embodiment, the reliable molding of the local full-length parts of the carbon fibers on both sides can be further completed. During the molding process, the mold gap relies on the downward force applied by the hot press, so that each slider is limited downward, the edge of the lower mold is highly flush, and precise limiting is completed to ensure the molding quality and accuracy of the carbon beam.

[0083] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A compression molding method for a hexahedral carbon fiber beam, characterized in that: The following steps are included: S1. Prepare a first molding die and a second molding die. The first molding die includes a molding template and a detachable vertical plate. The molding template has a plurality of plug holes arranged on an upward end. The detachable vertical plate has a plurality of plug portions arranged on a bottom side corresponding to the plug holes. The molding template has a plurality of first limiting holes formed on one side outside the plug portions in the longitudinal direction. S2. Take out the prepreg stored in the cold storage in advance and leave it for a set time until there is no moisture on the surface of the sealed bag and it is ready for use; S3. Import the designed blanking drawing into the blanking machine supporting software, use the blanking machine to cut the prepreg into the process design shape, sort the pieces in order according to the number, place the sorted pieces in the order of the numbers, and use vacuum bag packaging for storage; S4. Lay release cloth on the front and rear sides of the detachable vertical plate, respectively. Install the glass fiber prefabricated block with the mandrel mounted on it on the first forming mold, align the mandrel with the corresponding first limiting hole, insert the first positioning pin into the through hole of the mandrel and then into the first limiting hole, lay the sheet material on the upper side of the forming template in the laying order, and pre-vacuum it according to the set pre-vacuum treatment process during the laying process. After all the sheets are laid, loosen the two sides of the central detachable vertical plate and pull it upward to obtain the full-length portion of the carbon beam fiber. S5. Tightly align all the full-length portions of the carbon beam fibers, and perform a pre-vacuum treatment after the alignment is completed to obtain a carbon beam preform; S6. Remove the second positioning pin from the second forming die, place the carbon beam preform into the die cavity of the second forming die, insert the second positioning pin into the mandrel and the second limiting hole of the second forming die, and complete the positioning of the carbon beam preform in the second forming die; S7. Lay the carbon fiber sheets on the second forming molds on the front and rear sides of the carbon beam preform in a layup order. During the layup process, vacuum is applied according to the set pre-vacuuming process. After the layup is completed, check that there is no obvious height difference between the carbon fiber strips in the local full-length portion and the carbon beam preform, and then perform pre-vacuuming again. S8, disassembling the second forming die, removing the carbon beam blank, determining whether it needs to be reshaped, cleaning the surface of each component in the second forming die, and applying a release agent; S9. Install the trimmed carbon beam blank and various components into the second forming die one by one, perform partial filling, and fill the entire die with 3-5 layers of unidirectional strips; S10, closing the mold, hoisting the second molding mold to the hot press platform for curing; S11, after curing is completed, the mold is removed and the preformed carbon beam is taken out; S12. Perform excess removal according to the process marking lines of the carbon beam, and polish off excess resin or fiber burrs to obtain a carbon fiber beam.

2. The compression molding method of a hexahedral carbon fiber beam according to claim 1, wherein: In step S4, the pre-vacuum treatment process is to perform pre-vacuum treatment once on the first layer of paving, and then perform pre-vacuum treatment once every 10-15 layers and the last layer. The pre-vacuum time is not less than 15 minutes, and the pre-vacuum timing is set so that the vacuum degree in the vacuum bag is not higher than -0.85MPa.

3. The compression molding method of a hexahedral carbon fiber beam according to claim 1, wherein: In step S5, when aligning, a layer of medium-temperature epoxy film is laid on the aligning surface of the entire fiber length portion of the carbon beam to fill the aligning gap; when the aligning is completed, the pre-vacuuming time is not less than 15 minutes, and the pre-vacuuming timing is determined by the vacuum degree in the vacuum bag not exceeding -0.85 MPa.

4. The compression molding method of a hexahedral carbon fiber beam according to any one of claims 1 to 3, characterized in that: The cam is fixed to the upper side of the moulding board so as to enable the moulding board to move forward and backward, so as to prevent the moulding board from moving backward and backward, so as to avoid the moulding board from moving forward and backward.

5. The compression molding method of a hexahedral carbon fiber beam according to claim 4, wherein: The rear sides of the first slider and the second slider each have a first inclined surface inclined from top to bottom toward the inner wall of the front end of the lower mold, and the first slider and the second slider can be respectively attached to the front side of the first long insert through the first inclined surface. The front sides of the third slider and the fourth slider each have a second inclined surface inclined from top to bottom toward the inner wall of the rear end of the lower mold, and the third slider and the fourth slider can respectively be attached to the rear side of the second long insert through the second inclined surface.

6. The compression molding method of a hexahedral carbon fiber beam according to claim 5, wherein: A short insert is detachably connected to the lower mold on the left side of the first long insert, and a short slider is detachably connected to the lower mold between the short insert and the inner wall of the left end of the lower mold. The right side of the short slider has a third inclined surface inclined from top to bottom toward the direction of the inner wall of the right end of the lower mold, and the short slider can be attached to the left side of the short insert through the third inclined surface.

7. The compression molding method of a hexahedral carbon fiber beam according to claim 6, wherein: The specific steps of laying the sheet in step S7 are: The strips of material laid on the lower molds on the front and rear sides of the carbon beam preform are laid flatly in the horizontal direction to fill the remaining mold cavity space in the 0° direction; When the material strips are laid to a certain thickness, the first and second long inserts are placed in the lower molds on the front and rear sides of the carbon beam preform respectively. Initially, the front side of the first long insert is against the inner wall of the front end of the lower mold, and the rear side of the second long insert is against the inner wall of the rear end of the lower mold. The material strips are trimmed and laid along the rear side of the first long insert and the front side of the second long insert to ensure that there is no interference after the long inserts and sliders are installed. After the mold trimming is completed, the long inserts, sliders, and the first connecting pins on the sliders are placed separately. Soft rubber pads are placed in the lower mold to raise each slider 1-2mm above the upper edge of the lower mold. The soft rubber pads are placed in the position without the first connecting pin. After installation, continue to lay the material strips in the order of laying. Use a flat rolling board to pre-compact each layer. Arrange vacuum equipment and perform pre-vacuum treatment every 3-5mm thickness until all the material strips are laid.

8. The compression molding method of a hexahedral carbon fiber beam according to claim 7, wherein: The pre-vacuum treatment time shall not be less than 30 minutes, and the pre-vacuum timing shall be such that the vacuum degree in the vacuum bag is not higher than -0.85MPa.

9. The compression molding method of a hexahedral carbon fiber beam according to claim 7, wherein: Specifically, step S9 comprises installing the carbon beam blank, the first long insert, the second long insert, each soft rubber pad, each slider and the first connecting pin of the slider into the lower mold one by one, with the upper side of each slider protruding from the upper edge of the lower mold by 1-2 mm; in step S10, during molding and curing, the molding machine presses down the upper mold so that each slider pushes the corresponding insert toward the center of the carbon beam to ensure that each insert is in place during curing.

10. The compression molding method of a hexahedral carbon fiber beam according to claim 8, wherein: In step S11, the steps of demolding are as follows: taking out each second connecting pin connecting the upper mold and the lower mold, applying force upward uniformly using a mold opening tool, prying until it is loose, lifting and removing the upper mold, using a screw tool to apply force upward on the first slider, the second slider, the third slider and the fourth slider respectively until they are loose, taking out each slider, loosening each insert in a direction away from the carbon fiber beam, and taking out the carbon fiber beam.

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