RTM (Resin Transfer Molding) mold and method for molding ducted fan blade made of woven composite material

Abstract

The invention provides an RTM mold and a method for forming a braided composite ducted fan blade, and belongs to the technical field of composite forming. Comprising an upper mold, a lower mold, a left mold and a right mold, the upper mold is located over the lower mold, the left mold and the right mold are oppositely installed between the upper mold and the lower mold through embedding openings, and the inner side face of the upper mold, the inner side face of the lower mold, the left mold and the right mold are matched to form a cavity for containing a braided composite material prefabricated body. According to the RTM mold, efficient, high-precision and low-defect forming of the complex special-shaped structure composite material can be achieved.

Description

Technical Field

[0001] The present application relates to an RTM mould and a method for forming a braided composite ducted fan blade, belonging to the technical field of composite material forming. Background Art

[0002] Three-dimensional braided composite materials have excellent properties such as light weight, high strength, good structural designability and easy complex component molding. They are widely used in aerospace, transportation, military energy and other fields, such as rocket throat linings, propeller blades, engine nozzles, missile nose cones and carbon fiber frames. The corresponding two-dimensional braiding technology has the advantages of less material loss and high degree of automation, so it can realize the one-time molding of complex components, which is very suitable for the molding of various curved surfaces and special-shaped structural parts.

[0003] Although two-dimensional weaving technology has many of the above advantages, the composite molding of complex special-shaped structural preforms after weaving is also a key link in determining the final composite material product. In order to ensure the accuracy of the external dimensions of complex special-shaped structures, common composite material molding processes include compression molding and resin transfer molding (RTM), but compression molding is suitable for the composite molding of preforms made of prepreg laying, while RTM technology is more suitable for the composite molding of complex special-shaped structural preforms made of dry fiber weaving. However, the above molding methods cannot avoid the problem of glue leakage and lack of glue, which is a major defect in the current composite material molding. Summary of the invention

[0004] In view of this, the present application first provides an RTM mold that can achieve efficient, high-precision and low-defect molding of complex and special-shaped composite materials.

[0005] Specifically, the present application is implemented through the following scheme: An RTM mold comprises an upper mold, a lower mold, a left mold and a right mold. The upper mold is located directly above the lower mold. The upper mold comprises a back side, an end side wall and an inner side, a locking bolt hole is arranged on the back side, and at least three groups of the locking bolt holes are arranged. The locking bolt holes are through holes and are distributed on the back side of the upper mold; there are two end side walls, and the side of the two end side walls facing the lower mold is a parting surface, and a non-through hole positioning hole is arranged on the parting surface; a glue inlet connection hole is arranged on one of the end side walls, and an upper groove is arranged on the inner side near the end side wall, and the glue inlet connection hole is a through hole, and a glue inlet hole is arranged on the inner side corresponding to the glue inlet connection hole, and an L-shaped channel is formed from the glue inlet connection hole to the glue inlet hole; The lower mold comprises a back side, an end side wall and an inner side, the end side walls are two, the two end side walls facing the upper mold are parting surfaces, the parting surfaces are provided with two locking threaded holes and two positioning holes, the two locking threaded holes and the two positioning holes are not through holes; the glue outlet connection hole is provided on one of the end side walls, and is not at the same end as the glue inlet connection hole, a lower card slot is provided on the inner side surface away from the end side wall, the glue outlet connection hole is a through hole, a glue outlet hole is provided on the inner side surface corresponding to the glue outlet connection hole, and a linear channel is formed from the glue outlet connection hole to the glue outlet hole; The upper card slot and the lower card slot are arranged correspondingly and form an embedding opening. The left mold and the right mold are relatively installed between the upper card slot and the lower card slot through the embedding opening. The inner side surface of the upper mold, the inner side surface of the lower mold, the left mold, and the right mold cooperate to form a cavity for accommodating the braided composite material preform.

[0006] Further, as a preference: An upper mold pin hole is provided on the back side surface corresponding to the upper card slot, and a lower mold pin hole is provided on the back side surface corresponding to the lower card slot. The upper mold pin hole and the lower mold pin hole are provided correspondingly and are through holes for fixing the upper mold, the lower mold, the left mold and the right mold.

[0007] The first locking mold bolt holes are provided with six holes, two in each group, and are respectively distributed at the two ends and the middle of the back side of the upper mold.

[0008] A plurality of mold opening top screw thread holes are arranged on the back side surface of the upper mold, and the mold opening top screw thread holes are through holes.

[0009] An upper mold handle is arranged on the end side wall of the upper mold.

[0010] A lower mold handle is arranged on the end side wall of the lower mold.

[0011] The lower mold, the left mold and the right mold are provided with sealing grooves at positions corresponding to the edges of the cavity, and the sealing grooves are filled with rubber rings.

[0012] The above-mentioned RTM mold proposed in the present invention directly prepares the finished composite material without the need for post-processing steps such as grinding and polishing, which greatly reduces the production cost while ensuring the quality of the composite material; and the arrangement of structures such as the locking bolt hole, the glue inlet connecting hole, the positioning hole, and the glue inlet hole can ensure that the final composite material will not have major defects such as lack of glue and leakage of glue.

[0013] The upper mold, the lower mold, the left mold and the right mold with the above characteristics form a mold as a whole, and switch valves are respectively arranged on both sides of the mold as a whole. Therefore, the second object of the applicant is to provide a method for forming a braided composite ducted fan blade using the above RTM mold, and the steps are as follows: Step 1: Check whether the glue inlet and outlet holes are unobstructed. After the edge of the cavity is sealed, evenly spread the mold release wax or release agent on the inner surface of the cavity. Step 2: Select the resin model according to the requirements of the braided composite ducted fan blades, and ensure that the selected resin viscosity does not exceed 600mPa·s. First, tighten the left mold, the right mold and the braided composite preform, and then lock the upper mold and the lower mold. Connect the glue inlet connection hole and the glue outlet connection hole to the external air compressor and vacuum pump respectively. Step 3. Open the switch valve connecting the vacuum pump to the mold as a whole, check the air tightness of the mold as a whole, and after reaching a negative atmospheric pressure, turn on the air compressor and adjust the pressure value to no more than 0.5 MPa. Open the switch valve connecting the air compressor to the mold as a whole, and when resin appears in the air pipe connected to the vacuum barrel without bubbles, close the switch valves on both sides, remove the vacuum barrel and high-pressure barrel, place the entire mold in the oven, set the oven temperature program according to the resin curing process, and form it. Step 4: After the mold is cooled as a whole, remove the locking bolts, open the mold in the reverse order of mold installation, conduct an initial inspection, remove excess resin, and obtain a molded braided composite ducted fan blade.

[0014] The molding process proposed in combination with the RTM mold with the above characteristics can achieve efficient, high-precision and low-defect molding of complex and special-shaped composite materials. Among them, the block-type RTM mold will help to mold the preforms of complex and special-shaped structures and reduce the extrusion, wrinkling and damage of the surface fibers during the molding process.

[0015] Preferably, In step one, the release wax or release agent is applied by smearing or spraying.

[0016] In step 2: A high-pressure barrel is arranged between the glue inlet connection hole and the air compressor, the mixed and degassed resin barrel is placed in the high-pressure barrel, and the high-pressure barrel and the glue inlet connection hole are connected by a high-pressure resistant air pipe; A vacuum barrel is arranged between the glue outlet connection hole and the vacuum pump, and the resin collection barrel is placed in the vacuum barrel to prevent the extracted resin from flowing into the vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a schematic diagram of the assembly of the RTM mold and the ducted fan blade in this application; Figure 2 This is a schematic diagram of the back side structure of the RTM upper mold in this application; Figure 3 This is a schematic diagram of the inner side structure of the RTM upper mold in this application; Figure 4 Schematic diagram of the relative position relationship between the glue inlet connection hole and the glue inlet hole in this application; Figure 5 This is a schematic diagram of the inner side structure of the RTM lower mold in this application; Figure 6 This is a schematic diagram of the back side structure of the RTM lower mold in this application; Figure 7 This is a schematic diagram of the RTM left mold structure in this application; Figure 8 This is a schematic diagram of the RTM right mold structure in this application; Fig. 9 Schematic diagram of glue injection into braided composite ducted fan blades; Fig.10 A schematic diagram of the forming of a braided composite ducted fan blade; Fig.11 This is a schematic diagram of the processing flow for this application.

[0019] Numbers in the figure: 1. Upper mold; 11. Locking bolt hole 1; 12. Mold opening screw thread hole; 13. Upper mold pin hole; 14. Upper mold handle; 15. Glue inlet connection hole; 16. Positioning hole 1; 17. Glue inlet hole; 18. Upper slot; 1a. Back side; 1b. End side wall; 1c. Parting surface; 1d. Inner side; 1e. Cavity top; 2. Lower mold; 21. Locking thread hole 2; 22. Positioning hole 2; 23. Lower mold pin hole; 24. Lower mold handle; 25 . Glue outlet hole; 26. Glue outlet connection hole; 27. Lower mold sealing ring groove; 28. Lower card slot; 3. Left mold; 31. Pin hole one; 32. Sealing ring groove one; 4. Right mold; 41. Pin hole two; 42. Sealing ring groove two; 5. The mold as a whole; 51. Switch valve; 52. Pressure-resistant air pipe; 6. Air compressor; 61. Resin barrel; 62. High-pressure barrel; 7. Vacuum pump; 71. Resin collection barrel; 72. Vacuum barrel; 8. Oven; A. Braided composite material preform. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer, the technical solutions in the embodiments of this application will be further described in detail below in conjunction with the drawings in the embodiments of this application. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the technical solutions of this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0021] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and should not be construed as limitations on the present technical solution.

[0022] Example 1

[0023] This embodiment is a RTM mold, combined with Figure 1 , including an upper mold 1, a lower mold 2, a left mold 3 and a right mold 4, and the upper mold 1 is located directly above the lower mold 2.

[0024] Combination Figures 2 to 4 The upper mold 1 includes a back side surface 1a, an end side wall 1b, a parting surface 1c, an inner side surface 1d and a cavity top 1e. A locking bolt hole 11 is arranged on the back side surface 1a. The locking bolt hole 11 is a through hole. There are three groups of six locking bolt holes 11, which are distributed at the two ends and the middle of the back side surface 1a of the upper mold; there are two end side walls 1b, and the side of the two end side walls 1b facing the lower mold 2 is the parting surface 1c. A non-through hole positioning hole 16 is arranged on the parting surface 1c; a glue inlet connecting hole 15 is arranged on one of the end side walls, and an upper groove 18 is arranged on the inner side surface 1d near the end side wall. The glue inlet connecting hole 15 is a through hole, and a glue inlet hole 17 is arranged on the inner side surface corresponding to the glue inlet connecting hole 15, and an L-shaped channel is formed from the glue inlet connecting hole 15 to the glue inlet hole 17.

[0025] Combination Figure 5 , Figure 6: The lower mold 2 also includes a back side, an end side wall and an inner side surface. There are two end side walls, and the two end side walls facing the side of the upper mold 1 are parting surfaces. The parting surfaces are provided with a locking threaded hole 21 and a positioning hole 22. The locking threaded hole 21 and the positioning hole 22 are not through holes; the glue outlet connecting hole 26 is provided on one of the end side walls, the glue outlet connecting hole 26 is a through hole, and is not at the same end as the glue inlet connecting hole 15, and a lower card groove 28 is provided on the inner side surface away from the end side wall, and a glue outlet hole 27 is provided on the inner side surface corresponding to the glue outlet connecting hole 26, and a linear channel is formed from the glue outlet connecting hole 26 to the glue outlet hole 27.

[0026] The upper card slot 18 and the lower card slot 28 are arranged correspondingly and form an embedding opening. The left mold 3 and the right mold 4 are relatively installed between the upper card slot 1 and the lower card slot 2 through the embedding opening. The inner side surface of the upper mold 1 is provided with a cavity top 1e, and the inner side surface of the lower mold 2 is provided with a cavity bottom. The cavity top 1e and the cavity bottom are arranged correspondingly, and cooperate with the left mold 3 and the right mold 4 to form a cavity for accommodating the woven composite material preform A.

[0027] In the above scenario: An upper mold pin hole 13 is provided on the back side surface corresponding to the upper card slot 18, and a lower mold pin hole 23 is provided on the back side surface corresponding to the lower card slot 28. The upper mold pin hole 13 and the lower mold pin hole 23 are provided correspondingly, and both are through holes. Figure 7 , Figure 8 The left mold and the right mold corresponding to the upper mold pin hole 13 and the lower mold pin hole 23 are respectively provided with a pin hole 1 31 and a pin hole 2 41. The upper mold pin hole 13, the lower mold pin hole 23, the pin hole 1 31, and the pin hole 2 41 are loaded with connectors such as pins to complete the fixation of the upper mold 1, the lower mold 2, the left mold 3, and the right mold 4.

[0028] Four mold opening top screw thread holes 12 are arranged on the back side of the upper mold 1, and the mold opening top screw thread holes 12 are through holes.

[0029] For easy installation, an upper mold handle 14 may be provided on the end side wall 1b of the upper mold 1, and a lower mold handle 24 may be provided on the end side wall of the lower mold 2. The upper mold handle 14 and the lower mold handle 24 may be provided selectively or simultaneously.

[0030] Combination Figure 5 , Figure 7 , Figure 8 A lower mold sealing ring groove 27 is provided at the position corresponding to the edge of the lower mold 2 and the cavity, and a sealing ring groove 1 32 and a sealing groove 2 42 are provided at the positions corresponding to the edge of the left mold and the right mold and the cavity, respectively. The lower mold sealing ring groove 27, the sealing ring groove 1 32 and the sealing groove 2 42 are filled with rubber rings for sealing resin.

[0031] The above-mentioned RTM mold proposed in the present invention directly prepares the finished composite material without the need for post-processing steps such as grinding and polishing, which greatly reduces the production cost while ensuring the quality of the composite material; and the arrangement of structures such as the locking bolt hole, the glue inlet connecting hole, the positioning hole, and the glue inlet hole can ensure that the final composite material will not have major defects such as lack of glue and leakage of glue.

[0032] After the upper mold 1, the lower mold 2, the left mold 3 and the right mold 4 form a mold body 5, the braided composite material ducted fan blade can be formed. Fig.11 , the specific steps are as follows: Step 1: Check whether the glue inlet hole 17 and the glue outlet hole 25 are unobstructed, install the sealing strips on each block mold to complete the sealing treatment of the cavity edge, and evenly cover the inner surface of the cavity with release wax or release agent by smearing or spraying. Step 2: Select the resin model according to whether the braided composite ducted fan blades have requirements for high temperature resistance, toughening and wear resistance, and ensure that the viscosity of the selected resin does not exceed 600mPa·s. First, tighten the left mold 3, the right mold 4 and the braided composite preform A, and then lock the upper mold 1 and the lower mold 2 to complete the assembly of the mold as a whole 5.

[0033] Step 3: Combine Fig. 9 , connect the glue inlet connection hole 15 and the glue outlet connection hole 26 as Fig.10 The method shown is to connect the external air compressor 6 and the vacuum pump 7 respectively: A high-pressure barrel 62 is provided between the glue inlet connection hole 15 and the air compressor 6 , and the mixed and degassed resin barrel 61 is placed in the high-pressure barrel 62 . The high-pressure barrel 62 and the glue inlet connection hole 15 are connected via a high-pressure resistant air pipe 52 .

[0034] A vacuum barrel 72 is provided between the glue outlet connection hole 26 and the vacuum pump 7 , and the resin collecting barrel 71 is placed in the vacuum barrel 72 to prevent the extracted resin from flowing into the vacuum pump 7 .

[0035] Step 4: Open the switch valve 52 connecting the vacuum pump 7 and the mold as a whole 5, check the air tightness of the mold as a whole 5, and after reaching a negative atmospheric pressure, open the air compressor 6 and adjust the pressure to a suitable value, generally not higher than 0.5 MPa, open the switch valve connecting the air compressor 6 and the mold as a whole 5, and when resin appears in the air pipe connected to the vacuum barrel 72 without bubbles, close the switch valves 52 on both sides, remove the vacuum barrel 72 and the high-pressure barrel 62, and combine Fig.10 , place the whole mold 5 in the oven 8, set the oven temperature program according to the resin curing process, and form it. Step 5: After the mold is cooled as a whole, remove the locking bolts, open the mold in the reverse order of mold assembly, use the top screw to complete the upper mold opening, conduct preliminary inspection and classification of the obtained composite material products, clean up the excess resin in the disassembled RTM mold, and obtain the formed braided composite material ducted fan blade. Start the preparation of the next product.

[0036] The molding process proposed in combination with the RTM mold with the above characteristics can achieve efficient, high-precision and low-defect molding of complex and special-shaped composite materials. Among them, the block-type RTM mold will help to mold the preforms of complex and special-shaped structures and reduce the extrusion, wrinkling and damage of the surface fibers during the molding process.

[0037] The above-mentioned embodiments only express several feasible implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention, and the embodiments are not used to limit the scope of protection in the claims of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and all equivalent implementations or changes that do not depart from the present invention should be included in the technology of the present invention.

Claims

1. An RTM mold, characterized in that: It includes an upper mold, a lower mold, a left mold and a right mold. The upper mold is located directly above the lower mold. The upper mold comprises a back side, an end side wall and an inner side, a locking bolt hole is arranged on the back side, and at least three groups of the locking bolt holes are arranged. The locking bolt holes are through holes and are distributed on the back side of the upper mold; there are two end side walls, and the side of the two end side walls facing the lower mold is a parting surface, and a non-through hole positioning hole is arranged on the parting surface; a glue inlet connection hole is arranged on one of the end side walls, and an upper groove is arranged on the inner side near the end side wall, and the glue inlet connection hole is a through hole, and a glue inlet hole is arranged on the inner side corresponding to the glue inlet connection hole, and an L-shaped channel is formed from the glue inlet connection hole to the glue inlet hole; The lower mold comprises a back side, an end side wall and an inner side, the end side walls are two, the two end side walls facing the upper mold are parting surfaces, the parting surfaces are provided with two locking threaded holes and two positioning holes, the two locking threaded holes and the two positioning holes are not through holes; the glue outlet connection hole is provided on one of the end side walls, and is not at the same end as the glue inlet connection hole, a lower card slot is provided on the inner side surface away from the end side wall, the glue outlet connection hole is a through hole, a glue outlet hole is provided on the inner side surface corresponding to the glue outlet connection hole, and a linear channel is formed from the glue outlet connection hole to the glue outlet hole; The upper card slot and the lower card slot are arranged correspondingly and form an embedding opening. The left mold and the right mold are relatively installed between the upper card slot and the lower card slot through the embedding opening. The inner side surface of the upper mold, the inner side surface of the lower mold, the left mold, and the right mold cooperate to form a cavity for accommodating the braided composite material preform.

2. The RTM mold according to claim 1, characterized in that: An upper mold pin hole is provided on the back side surface corresponding to the upper card slot, and a lower mold pin hole is provided on the back side surface corresponding to the lower card slot. The upper mold pin hole and the lower mold pin hole are provided correspondingly and are through holes for fixing the upper mold, the lower mold, the left mold and the right mold.

3. The RTM mold according to claim 1, characterized in that: The first locking mold bolt holes are provided with six holes, two in each group, and are respectively distributed at the two ends and the middle of the back side of the upper mold.

4. The RTM mold according to claim 1, characterized in that: A plurality of mold opening top screw thread holes are arranged on the back side surface of the upper mold, and the mold opening top screw thread holes are through holes.

5. The RTM mold according to claim 1, characterized in that: An upper mold handle is arranged on the end side wall of the upper mold.

6. The RTM mold according to claim 1, characterized in that: A lower mold handle is arranged on the end side wall of the lower mold.

7. The RTM mold according to any one of claims 1 to 6, characterized in that: The lower mold, the left mold and the right mold are provided with sealing grooves at positions corresponding to the edges of the cavity, and the sealing grooves are filled with rubber rings.

8. A method for forming a braided composite ducted fan blade using the RTM mold of claim 1, characterized in that: Here are the steps: The upper mold, the lower mold, the left mold and the right mold form a mold as a whole, and switch valves are respectively set on both sides of the mold as a whole. Step 1: Check whether the glue inlet and outlet holes are unobstructed. After the edge of the cavity is sealed, evenly spread the mold release wax or release agent on the inner surface of the cavity. Step 2: Select the resin model according to the requirements of the braided composite ducted fan blades, and ensure that the selected resin viscosity does not exceed 600mPa·s. First, tighten the left mold, the right mold and the braided composite preform, and then lock the upper mold and the lower mold. Connect the glue inlet connection hole and the glue outlet connection hole to the external air compressor and vacuum pump respectively. Step 3. Open the switch valve connecting the vacuum pump to the mold as a whole, check the air tightness of the mold as a whole, and after reaching a negative atmospheric pressure, turn on the air compressor and adjust the pressure value to no more than 0.5 MPa. Open the switch valve connecting the air compressor to the mold as a whole, and when resin appears in the air pipe connected to the vacuum barrel without bubbles, close the switch valves on both sides, remove the vacuum barrel and high-pressure barrel, place the entire mold in the oven, set the oven temperature program according to the resin curing process, and form it. Step 4: After the mold is cooled as a whole, remove the locking bolts, open the mold in the reverse order of mold assembly, conduct an initial inspection, remove excess resin, and obtain a molded braided composite ducted fan blade.

9. The method for using an RTM mold to weave composite ducted fan blades according to claim 8, characterized in that: In step one, the release wax or release agent is applied by smearing or spraying.

10. The method for using an RTM mold to weave composite ducted fan blades according to claim 8, characterized in that: In step 2: A high-pressure barrel is arranged between the glue inlet connection hole and the air compressor, the mixed and degassed resin barrel is placed in the high-pressure barrel, and the high-pressure barrel and the glue inlet connection hole are connected by a high-pressure resistant air pipe; A vacuum barrel is arranged between the glue outlet connection hole and the vacuum pump, and the resin collection barrel is placed in the vacuum barrel to prevent the extracted resin from flowing into the vacuum pump.

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