Variable-thickness integral control surface preform forming method and mold

Abstract

The invention relates to a variable-thickness integral control surface prefabricated body forming method and a mold, belongs to the technical field of control surface prefabricated body forming, and solves the technical problems of long forming preparation period and local layering of a control surface prefabricated body. Cutting cloth according to the size of the prefabricated body division area; preparing a lower layer-by-layer staggered triangular filling area prefabricated body, and preparing an upper layer-by-layer staggered triangular filling area prefabricated body; fixing the prefabricated body, and sewing; the upper die assembly and the lower die assembly are used for replacing the lower sewing tool and the upper sewing tool; and the upper mold assembly and the lower mold assembly are closed through a pressing strip, and the thickness-variable overall control surface prefabricated body is fixed. The method is used for forming the variable-thickness integral control surface preform.

Description

Technical Field

[0001] The invention belongs to the technical field of rudder surface preform molding, and in particular relates to a variable-thickness integral rudder surface preform molding method and a mold. Background Art

[0002] An important feature of hypersonic vehicle flight is the significant startup heating effect, which is particularly evident on the control surfaces. The aerodynamic and thermoelastic coupling of the control surfaces is a key technology that affects the control performance of the aircraft and even determines the cost of the flight mission.

[0003] Ceramic-based composites are a new type of thermal structural / functional integrated material that combines the performance advantages of metal materials, ceramic materials and carbon materials. They have the characteristics of high temperature resistance, low density, high specific strength, high specific modulus, oxidation resistance, ablation resistance, insensitivity to cracks, and no catastrophic damage. They are widely used in aviation, aerospace, nuclear energy, photovoltaics and other fields.

[0004] Ceramic-based composite rudder surfaces can not only meet the requirements of ablation resistance and strength, but also have the advantages of being lightweight.

[0005] The ceramic matrix composite rudder surface is formed by 2D layering method, and the preform is thick (see Figure 1 , 2 ), the densification process of the composite material is slow and the preparation cycle is long. Due to the large density gradient and poor dispersion of mechanical properties, the surface fibers are fractured after processing, and there is a risk of local stratification. Summary of the invention

[0006] In order to overcome the shortcomings of long preparation cycle and local delamination in the molding of rudder surface preforms, the present invention proposes a molding method and a mold for a variable thickness integral rudder surface preform.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A method for forming a variable thickness integral rudder surface preform comprises the following steps:

[0009] Step 1: Prefab division

[0010] The rudder surface preform is divided into a lower layer of uniform thickness paving area, a lower layer of staggered triangular filling area, a middle layer of uniform thickness paving area, an upper layer of staggered triangular filling area, and an upper layer of uniform thickness paving area.

[0011] Step 2: Cut the fabric

[0012] Cut the cloth according to the size of the preform divided area, splice two rudder carbon cloths together to cut one sheet, and then divide it into two sheets along the bevel.

[0013] Step 3: Prepare the lower layer of staggered triangle filling area preform

[0014] The lower triangular filling preform is prepared using the lower triangular filling shaping tool. The carbon cloth covers the flat area as a whole, and a layer is cut every time a step is encountered, and then the next layer is laid, and the last layer is laid in sequence.

[0015] Step 4: Prepare the upper layer of staggered triangle filling area preform

[0016] Use the upper triangle filling shaping tooling to cover the entire flat area with carbon cloth. Cut a layer every time a step is encountered, and then lay the next layer, and so on until the last layer.

[0017] Step 3: Fix the prefab

[0018] 3.1) Laying multiple layers of carbon cloth on the lower sewing tool to obtain a preform of the lower layer with equal thickness;

[0019] 3.2) Placing the pre-prepared lower layer staggered triangular filling area preform on the lower layer full-layer uniform thickness ply area preform;

[0020] 3.3) laying multiple layers of carbon cloth on the lower layer of staggered triangular filling area preform; the multiple layers of carbon cloth constitute the middle layer of the whole layer of equal thickness laying area preform;

[0021] 3.4) Place the prefabricated upper layer staggered triangular filling area prefabricated body on the middle layer full-layer equal-thickness ply area prefabricated body;

[0022] 3.5) laying multiple layers of carbon cloth on the upper layer of the staggered triangular filling area preform; the multiple layers of carbon cloth constitute the upper layer of the whole layer of equal thickness paving area preform;

[0023] 3.6) The upper sewing tool and the lower sewing tool fix the lower layer staggered triangular filling area preform, the middle layer whole layer equal thickness ply area preform, the lower layer whole layer equal thickness ply area preform, the upper layer staggered triangular filling area preform, and the upper layer whole layer equal thickness ply area preform;

[0024] The middle layer, the whole layer, the equal thickness layer area, and the upper layer, the whole layer, the equal thickness layer area. The upper sewing tooling and the lower sewing tooling fix the lower layer, the staggered triangle filling area, the middle layer, the equal thickness layer area, the lower layer, the upper layer, the staggered triangle filling area, and the upper layer, the equal thickness layer area.

[0025] Step 4, Sewing

[0026] Based on the upper sewing tooling and the lower sewing tooling, sew according to the sewing groove and sewing positioning holes. After sewing, lock the edges all around.

[0027] Step 5: Replace the mold

[0028] Use the upper die assembly to replace the lower sewing tooling; use the lower die assembly to replace the upper sewing tooling.

[0029] Step 6: Mold Closing

[0030] The variable thickness integral rudder surface preform is fixed by using pressure strips, bolts and nuts through the closing of the upper mold assembly and the lower mold assembly.

[0031] In the above-mentioned rudder surface preform molding method, in the step 3.2, the preparation steps of the lower layer staggered triangular filling area preform are as follows: the multi-layer carbon cloth is used to cover the flat area of ​​the lower triangular filling molding tooling as a whole, and a layer is cut every time a step is encountered, and then the next layer is laid, and the last layer is laid in sequence;

[0032] In step 3.2, the preparation steps of the upper layer staggered triangular filling area preform are as follows: cover the flat area of ​​the upper triangular filling shaping tooling with multiple layers of carbon cloth as a whole, cut a layer every time a step is encountered, and then lay the next layer, and so on to the last layer.

[0033] In the above-mentioned method for forming a rudder preform, the step 3 further comprises:

[0034] Use the sewing tool to cut several layers of carbon fiber cloth according to the dimensions of the preform;

[0035] Place the lower layer in the equal-thickness ply area and position it using the positioning pins;

[0036] Lay several layers in the middle layer and the whole layer with equal thickness paving area;

[0037] Place it in the upper layer of staggered triangular filling area and position it with positioning pins;

[0038] Lay several layers of whole cloth to complete the paving of the upper whole layer equal thickness paving area;

[0039] At the crease, the sewing thread is used for marking;

[0040] Place the upper sewing tooling on the upper layer staggered triangular filling area and the upper layer equal thickness laying area, and position it by the positioning pins;

[0041] Use the dowel pins and screws to secure the upper and lower sewing work.

[0042] In the above-mentioned rudder preform forming method, in step 3, the number of layers of the lower layer staggered triangular filling area is 10, the number of layers of the middle layer whole layer equal thickness paving area is 11, and the number of layers of the upper layer whole layer equal thickness paving area is 10.

[0043] In the above-mentioned method for forming a rudder preform, the step 4 further comprises:

[0044] The density of sewing is 5*5.

[0045] A stitch does not cross 2 or more sewing grooves.

[0046] In the above-mentioned method for forming a rudder preform, the step 5 further comprises:

[0047] The upper mold, the first mold and the second mold are combined into an upper mold assembly.

[0048] A variable thickness integral rudder surface preform forming die comprises an upper die assembly, a lower die assembly, a pressure strip, a lower sewing tool, an upper sewing tool, a lower triangular filling and shaping tool, an upper triangular filling and shaping tool, bolts, nuts and positioning pins.

[0049] The lower layer triangle filling shaping tooling is provided with positioning holes, and the shaping tooling cuts the limiting grooves layer by layer.

[0050] The lower sewing tool and the upper sewing tool are both provided with sewing grooves and sewing positioning holes, and the sewing grooves of the upper sewing tool and the lower sewing tool correspond to each other in upper and lower positions.

[0051] The upper mold assembly includes an upper mold, a first mold and a second mold.

[0052] The materials of the rudder surface preform forming mold, the upper mold assembly, the lower mold assembly, the pressure strip, the bolts, the nuts and the positioning pins are all graphite.

[0053] In the above-mentioned rudder surface preform forming mold, the lower layer of triangular filling and shaping tooling is made of metal.

[0054] In the above-mentioned rudder surface preform forming mold, the bolts are stud bolts that match the nuts and are M20.

[0055] The positioning hole of the above-mentioned rudder surface preform forming mold is φ10.

[0056] The beneficial effects of the present invention are:

[0057] A method for forming a variable thickness integral rudder preform is proposed. Aiming at the problems existing in the integrated forming method of the 2D laying method of the ceramic-based composite rudder, a shaping tool and a sewing tool are designed. During the preform laying process, preforms of unequal wall thicknesses are prepared, the efficiency of composite material preparation and densification is widened, the density uniformity is improved, and the overall strength is improved. At the same time, the laying direction of the outermost layer is parallel to the surface of the part, which can prevent the surface carbon cloth from being fractured after processing and effectively solve the problem of local stratification. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a stereogram of the prefabricated structure of the prior art;

[0059] Figure 2 It is a cross-sectional view of a prefabricated body in the prior art;

[0060] Figure 3This is a three-dimensional diagram of the preform structure of an embodiment of the present invention;

[0061] Figure 4 Schematic diagram of equal thickness area of ​​a preform according to an embodiment of the present invention;

[0062] Figure 5 Schematic diagram of the triangular filling area of ​​the preform according to the embodiment of the present invention;

[0063] Figure 6 Schematic diagram of carbon fiber cloth plying of a preform according to an embodiment of the present invention;

[0064] Figure 7 is a schematic cross-sectional view of a preform according to an embodiment of the present invention;

[0065] Figure 8 yes Figure 7 The enlarged view at A in the middle shows the carbon cloth layer layup at the tip of the preform;

[0066] Fig. 9 yes Figure 7 The enlarged view at B in the middle shows the carbon cloth layer layup at the corner of the preform;

[0067] Fig.10 It is the shaping tooling for the lower triangular filling preform;

[0068] Fig.11 It is a schematic diagram of shaping the lower triangular filling preform;

[0069] Fig.12 It is a schematic diagram of the lower triangle filling preform;

[0070] Fig.13 It is a lower layer whole cloth layup preform located on the lower sewing tooling;

[0071] Fig.14 It is a schematic diagram of the implantation of the lower triangular filling preform, with the pins positioned;

[0072] Fig.15 It is a schematic diagram of the implantation of the lower triangular filling preform;

[0073] Fig.16 It is the middle layer whole cloth ply preform forming;

[0074] Fig.17 It is a schematic diagram of the implantation of the upper triangular filling preform, with the pins positioned;

[0075] Fig.18 It is a schematic diagram of the implantation of the upper triangular filling preform;

[0076] Fig.19 It is the upper whole cloth layer preform forming;

[0077] Fig. 20 It is used to place the upper sewing work clothes;

[0078] Fig.21 It is a schematic diagram of the sewing slot of the sewing tool;

[0079] Fig. 22 yes Fig.21 Enlarged view of point C in the middle;

[0080] Fig.23 It is a schematic diagram of mold splicing;

[0081] Fig.24 It is a schematic diagram of the replacement upper mold;

[0082] Fig.25 It is a schematic diagram of flip placement;

[0083] Fig.26 It is a schematic diagram of placing the lower mold, pressure strip, and bolt connection and fixing.

[0084] The reference numerals are as follows:

[0085] 1. Original preform, 2. Carbon fiber cloth laminated section, 3. Rudder surface product cross-sectional structure, 4. Preform of the present invention, 5. Lower layer full-layer equal-thickness plying area, 6. Lower layer staggered triangular filling area, 7. Middle layer full-layer equal-thickness plying area, 8. Upper layer staggered triangular filling area, 9. Upper layer full-layer equal-thickness plying area, 10. Preform cross-sectional view of the present invention;

[0086] 11. Carbon fiber cloth layer-by-layer cutting area, 12. Equal thickness area, 13. Sewing thread ends;

[0087] 101. lower sewing tooling, 102. positioning hole, 104. positioning pin, 106. height limit surface, 107. upper sewing tooling, 108. screw, 109. sewing groove, 110. sewing positioning hole;

[0088] 201. upper mold assembly, 202. lower mold assembly, 203. pressure strip, 205. bolt, 206. nut, 207. upper mold, 208. first mold, 209. second mold;

[0089] 301. The lower triangle fills the shaping tool, 305. The shaping tool cuts the limiting groove layer by layer, 306. The upper triangle fills the shaping tool. DETAILED DESCRIPTION

[0090] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0091] Embodiment 1

[0092] A method for forming a variable thickness integral rudder surface preform comprises the following steps:

[0093] 1. Preform 4 of the present invention (see Figure 3) is divided into five parts, the lower layer of uniform thickness paving area 5, the lower layer of layer-by-layer staggered triangular filling area 6, the middle layer of uniform thickness paving area 7, the upper layer of layer-by-layer staggered triangular filling area 8, the upper layer of uniform thickness paving area 9, see Figure 4 and Figure 5 ; The cross section of the preform of the present invention 10 (see Figure 6 ) is a structure of unequal thickness.

[0094] Its advantages are as follows:

[0095] 1) Local thinning can improve the subsequent densification effect;

[0096] 2) The appearance quality after subsequent processing can be improved by the lower layer full-layer equal-thickness ply area 5 and the upper layer full-layer equal-thickness ply area 9;

[0097] 3) The middle layer of the same thickness ply area 7 can ensure that the internal continuous fibers are the most, and the preform ply interface ( Figure 7 ) Local enlargement of area A ( Figure 8 ), it can be seen that the continuous fibers are the most in the central area, ensuring the overall strength after processing;

[0098] 4) The lower layer staggered triangular filling area 6 and the upper layer staggered triangular filling area 8 ensure the overall dimensional integrity, and the other preforms in the triangular area fit tightly. Figure 7 ) Local enlargement of area B ( Fig. 9 ) can be seen in .

[0099] The original preform 1 is a uniform thickness folded surface structure. Figure 1 , which is made of carbon fiber cloth layer by layer. The cross section of the carbon fiber cloth laminate is shown in 2 Figure 2 , completely wrap the rudder product cross-section structure 3, see Figure 2 .

[0100] 2. Cut the carbon fiber cloth according to the size of the preform. The single-layer carbon fiber of this product is in a triangular shape. Two layers are spliced ​​into a rectangle for cutting, which can maximize the utilization rate of the carbon cloth;

[0101] 3. Use the lower triangle filling shaping tool 301 to prepare the lower triangle filling area 6 layer by layer. The carbon cloth covers the flat area as a whole. Cut a layer every time a step is encountered, and then lay the next layer, and so on to the last layer ( Fig.11 ).

[0102] Lower triangle filling molding tooling 301 ( Fig.10 ) features, including φ10 positioning holes, height limit surfaces, and fixed tooling that cuts limit grooves 305 layer by layer;

[0103] The lower layer of staggered triangular filling area 6 is characterized by the carbon fiber cloth layer by layer cutting area 11 and the equal thickness area 12. Fig.12.

[0104] 4. Use the upper triangle filling molding tool 306 ( Fig.17 ), and the upper layer of staggered triangular filling area 8 is prepared in the same way.

[0105] 5. Preparation of preform

[0106] 1) Use the lower sewing work 101 to cut 10 layers of carbon fiber cloth according to the dimensions of the preform. Fig.13 ;

[0107] 2) Based on 1), put the prepared lower layer of equal thickness ply area 5, and position it by φ10 positioning pin 104, see Fig.14 ;

[0108] The preparation of the lower layer uniform thickness paving area 5, the lower layer staggered triangular filling area 6 and the middle layer uniform thickness paving area 7 is completed. Fig.15 ;

[0109] 3) Then, lay 11 layers of middle layer and the entire layer of equal thickness in the ply area 7, see Fig.16 ;

[0110] 4) Then, the prepared upper layer staggered triangular filling area 8 is placed and positioned by the tooling positioning pins 104. Fig.17 ;

[0111] Complete the preparation of the lower layer full-layer equal-thickness paving area 5, the lower layer layer-by-layer staggered triangular filling area 6, the middle layer full-layer equal-thickness paving area 7 and the upper layer layer-by-layer staggered triangular filling area 8, see Fig.18 ;

[0112] 5) On the basis of the above prefabricated body, continue to lay 10 layers of whole cloth to complete the upper layer of equal thickness laying area 9, see Fig.19 ;

[0113] 6) Sew thread ends 13 at the fold for marking, see Fig.19 ;

[0114] 7) Place the upper sewing tool on the above preform, see Fig. 20 ;

[0115] 8) Use the φ10 positioning pin 104 and M10 screw 108 to fix the upper sewing tooling and the lower sewing tooling in place, see Fig.21 ;

[0116] The features of the upper and lower sewing tools include sewing grooves 109 and sewing positioning holes 110, see Fig. 22 , and the sewing groove positions of the upper sewing tooling and the lower sewing tooling completely overlap up and down.

[0117] 6. Sewing

[0118] Sewing is carried out according to the sewing grooves and sewing positioning holes designed for the upper and lower sewing tooling, with a close seam density of 5*5;

[0119] After sewing, overlock the edges.

[0120] 7. Replace the mold

[0121] The graphite upper mold 207, the first mold 208 and the second mold 209 are combined into a graphite upper mold assembly 201. Fig.23 During the preparation of the composite material, the first mold 208 and the second mold 209 can be separated in advance, which can improve the chemical vapor deposition effect. At the same time, the upper mold 207 can press and fix the composite material product around and at the crease, which is beneficial to deformation control.

[0122] The graphite lower mold assembly 202 is assembled in the same manner;

[0123] The preform is turned over so that the graphite upper mold assembly 201 faces downward, and the graphite upper mold assembly 201 is used to replace and remove the lower sewing tooling 107. Fig.24 , Fig.25 ;

[0124] Use the same method to replace the sewing work clothes.

[0125] 8. Mould closing

[0126] The preform 4 of the present invention is fixed in place by the upper mold assembly 201 and the lower mold assembly 202 using a graphite pressure strip 203, an M20 graphite stud bolt 205 and an M20 graphite nut 206. Fig.26 .

Claims

1. A method for forming a variable thickness integral rudder surface preform, characterized in that: The following steps are involved: Step 1, prefab division: The rudder surface preform is divided into a lower layer full-layer uniform thickness paving area (5), a lower layer layer-by-layer staggered triangular filling area (6), a middle layer full-layer uniform thickness paving area (7), an upper layer layer-by-layer staggered triangular filling area (8), and an upper layer full-layer uniform thickness paving area (9); Step 2, cutting the fabric: Cut the fabric according to the size of the prefabricated area; Step 3, fix the prefab: 3.1) laying multiple layers of carbon cloth on the lower sewing tool (101) to obtain a preform of the lower layer of uniform thickness laying area (5); 3.2) placing the prefabricated lower layer staggered triangular filling area (6) prefabricated body on the lower layer uniform thickness paving area (5); 3.3) laying multiple layers of carbon cloth on the lower layer of the staggered triangular filling area (6) preform; the multiple layers of carbon cloth constitute the middle layer of the whole layer of equal thickness laying area (7) preform; 3.4) placing the prefabricated upper layer staggered triangular filling area (8) prefabricated body on the middle layer uniform thickness paving area (7); 3.5) laying multiple layers of carbon cloth on the upper layer of the preform of the staggered triangular filling area (8); the multiple layers of carbon cloth constitute the upper layer of the preform of the whole layer of equal thickness laying area (9); 3.6) The upper sewing tool (107) and the lower sewing tool (101) fix the preform of the lower layer staggered triangular filling area (6), the preform of the middle layer whole layer equal thickness laying area (7), the preform of the lower layer whole layer equal thickness laying area (5), the preform of the upper layer staggered triangular filling area (8), and the preform of the upper layer whole layer equal thickness laying area (9); Step 4, Sewing: Based on the upper sewing tool (107) and the lower sewing tool (101), sewing is performed according to the sewing groove (109) and the sewing positioning hole (110); after sewing is completed, the edges are locked all around; Step 5, replace the mold: Using the upper mold assembly (201) to replace the lower sewing tool (101); using the lower mold assembly (202) to replace the upper sewing tool (107); Step 6, mold closing: The variable thickness integral rudder surface preform is fixed by using pressure strips, bolts and nuts through the closing of the upper mold assembly and the lower mold assembly.

2. The method for forming a rudder surface preform according to claim 1, characterized in that: In step 3.2, the preparation steps of the lower layer staggered triangular filling area preform (6) are as follows: the flat area of ​​the lower triangular filling shaping tool (301) is covered with a multi-layer carbon cloth as a whole, and a layer is cut every time a step is encountered, and then the next layer is laid, and the last layer is laid in sequence; In step 3.2, the preparation steps of the upper layer staggered triangular filling area preform (8) are as follows: the flat area of ​​the upper triangular filling shaping tooling (306) is covered with a multi-layer carbon cloth as a whole, and a layer is cut every time a step is encountered, and then the next layer is laid, and the last layer is laid in sequence.

3. The method for forming a rudder surface preform according to claim 1, characterized in that: The step 3 further comprises: Using a sewing tool (101), cutting several layers of carbon fiber cloth according to the outer dimensions of the preform; Place the lower layer of uniform thickness ply area (5) and position it by positioning pins (104); Laying several layers of middle layer and whole layer of equal thickness paving area (7); Place the upper layer of the staggered triangle filling area (8) and position it using the positioning pins (104); Lay several layers of whole cloth to complete the laying of the upper whole layer of equal thickness laying area (9); At the fold, a sewing thread (13) is used for marking; The upper sewing tool (107) is placed on the upper layer staggered triangular filling area (8) and the upper layer full-layer equal-thickness paving area (9), and positioned by the positioning pin (104); The upper sewing tool (107) and the lower sewing tool (101) are fixed by using the positioning pin (104) and the screw (108).

4. The method for forming a rudder surface preform according to claim 3, characterized in that: In the step 3, the lower triangular filling shaping tool (301) is used to cut the carbon fiber cloth into 10 layers according to the outer dimensions of the preform; the number of layers of the middle layer full-layer equal-thickness ply area (7) is 11 layers, and the number of layers of the upper layer full-layer equal-thickness ply area (9) is 10 layers.

5. The method for forming a rudder surface preform according to claim 1, characterized in that: The step 4 further comprises: the density of the sewing is 5*5; One stitch does not cross two or more sewing grooves (109).

6. The method for forming a rudder surface preform according to claim 1, characterized in that: The step 5 further comprises: The upper mold (207), the first mold (208) and the second mold (209) are combined into an upper mold assembly (201).

7. A mold for implementing the preform forming method according to claims 1 to 6, characterized in that: It comprises an upper mold assembly (201), a lower mold assembly (202), a pressure strip (203), a lower sewing tool (101), an upper sewing tool (107), a lower triangular filling and shaping tool (301), an upper triangular filling and shaping tool (306), a bolt (205), a nut (206), and a positioning pin (104); The lower triangle filling and shaping tool (301) is provided with positioning holes (102), and the shaping tool cuts limiting grooves (305) layer by layer; The lower sewing tool (101) and the upper sewing tool (107) are both provided with sewing grooves (109) and sewing positioning holes (110), and the sewing grooves of the upper sewing tool (107) and the lower sewing tool (101) are located in corresponding positions. The upper mold assembly (201) comprises an upper mold (207), a first mold (208) and a second mold (209).

8. The mold according to claim 7, characterized in that: The upper mold assembly (201), the lower mold assembly (202), the pressure strip (203), the bolt (205), the nut (206), and the positioning pin (104) are all made of graphite.

9. The mold according to claim 7, characterized in that: The lower triangular filling and shaping tooling (301) is made of metal.

10. The mold according to claim 7, characterized in that: The bolt (205) is a stud bolt, matched with the nut (206), and is M20; The positioning hole (102) is φ10.

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