Conical composite material hybrid triangular grid structure and its forming tooling

Abstract

The embodiments of the present application provide a hybrid triangular mesh structure of a conical composite material and its forming tooling. The triangular mesh structure includes an upper end frame, a lower end frame, bidirectional spiral ribs, and upper ring ribs, middle ring ribs, and lower ring ribs; the outer contour surface of the hybrid triangular mesh structure is a conical surface; the upper end frame, the lower end frame, the bidirectional spiral ribs, and the ring ribs are an integrally formed structure; the upper end frame and the lower end frame are both "L"-shaped; the bidirectional spiral ribs are symmetrical to each other; the center line of the outer contour surface of the bidirectional spiral ribs includes equal pitch spirals, equal helical angle spirals, and short-range lines; the center line of the outer contour surface of the ring ribs is a circle on the conical surface, the middle ring ribs are located in the middle of the hybrid triangular mesh structure, and the upper ring ribs and lower ring ribs are evenly distributed along the direction of the upper end frame and the lower end frame. The present application solves the technical problem that the traditional hyperbolic oblique rib skinless composite mesh structure is not suitable for cone section structures with small structural dimensions and limited internal envelope dimensions or cone section structures with requirements for aerodynamic shape.

Description

Technical Field

[0001] The present application relates to the technical field of cone segment structures, and in particular to a cone surface composite material hybrid triangular grid structure and a forming tool thereof. Background Art

[0002] The hyperbolic oblique rib skinless composite grid structure has been designed, produced, and tested, and can be used in rocket interstages, satellite brackets, and other structures. Due to the meridian curvature of the rotating single-blade hyperboloid, the single-blade hyperboloid composite grid structure is concave and has a poor aerodynamic shape. The hyperbolic oblique rib skinless composite grid structure is particularly unsuitable for cone-section structures with small structural dimensions and limited internal envelope dimensions or cone-section structures with requirements for aerodynamic shape.

[0003] The above information disclosed in the background section is only for enhancing understanding of the background of the present application and therefore it may contain information that does not form the prior art known to a person of ordinary skill in the art. Summary of the invention

[0004] The embodiments of the present application provide a conical composite hybrid triangular grid structure and its forming tooling to solve the technical problem that the traditional hyperbolic oblique rib skinless composite grid structure is not particularly suitable for conical segment structures with small structural dimensions and limited internal envelope dimensions or conical segment structures with requirements for aerodynamic shape.

[0005] According to a first aspect of an embodiment of the present application, a conical composite material hybrid triangular grid structure is provided, characterized in that it includes an upper end frame, a lower end frame, a bidirectional spiral rib, and an upper ring rib, a middle ring rib, and a lower ring rib; wherein:

[0006] The outer contour surface of the hybrid triangular mesh structure is a conical surface;

[0007] The upper end frame, the lower end frame, the bidirectional spiral ribs and the ring ribs are an integrally formed structure, and the ring ribs include upper ring ribs, middle ring ribs and lower ring ribs;

[0008] The upper frame and the lower frame are both "L" shaped;

[0009] The bidirectional spiral ribs are symmetrical to each other; the center line of the outer contour surface of the bidirectional spiral ribs includes an equal pitch spiral line, an equal helix angle spiral line and a short distance line;

[0010] The center line of the outer contour of the ring rib is a circle on the conical surface. The middle ring rib is located in the middle of the mixed triangular grid structure. The upper ring rib and the lower ring rib are evenly distributed along the upper end frame and the lower end frame.

[0011] According to a second aspect of the embodiment of the present application, a hard mold forming tool is provided.

[0012] In the winding state, it includes a mandrel, a lower head, a lower flange, a core mold, an aluminum split male mold, a steel sleeve, an upper flange, an upper head, a retaining ring, a key, and a small key;

[0013] In the forming state, it includes a core mold, an aluminum split male mold, a steel sleeve, an upper pressure ring, an outer mold, a small hoop), a large hoop, and a lower pressure ring;

[0014] Among them: the outer contour surface of the aluminum split male mold is a cone surface with the geometric parameters of the expansion amount corrected;

[0015] The center line of the rib groove on the aluminum split male mold used to form the bidirectional spiral rib is a conical spiral line with corrected expansion geometric parameters.

[0016] According to a third aspect of the embodiments of the present application, a soft mold forming tool is provided.

[0017] In the winding state, it includes a mandrel, a lower head, a lower flange, a core mold, an aluminum pad, a silicone rubber mesh soft mold, a steel sleeve, an upper flange, an upper head, a retaining ring, a key, and a small key;

[0018] In the forming state, it includes a core mold, an aluminum split male mold, a steel sleeve, an upper pressure ring, an outer mold, a small hoop, a large hoop, and a lower pressure ring;

[0019] The center line of the rib groove on the unfolded silicone rubber grid soft mold used to form the structural bidirectional spiral rib is a plane spiral line or a straight line with corrected expansion geometric parameters.

[0020] The embodiment of the present application adopts the above technical solution, which has the following technical effects:

[0021] The conical composite material hybrid triangular mesh structure of the embodiment of the present application is suitable for a conical segment structure with a small structural size and a limited inner envelope size or a conical segment structure with requirements for aerodynamic shape. The conical composite material hybrid triangular mesh structure of the embodiment of the present application meets the requirements of productization, has good structural integrity, good molding processability, and high production efficiency, thereby realizing a low-cost, lightweight, and rapid prototyping composite material mesh structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 A three-dimensional diagram of a hybrid triangular mesh structure of a conical composite material according to an embodiment of the present application;

[0024] Figure 2 It is a schematic diagram of the longitudinal section of the cone segment;

[0025] Figure 3Schematic diagram of the spiral line of the hybrid triangular mesh structure of the conical composite material;

[0026] Figure 4 It is a cross-sectional view of the hybrid triangular mesh structure of the conical composite material;

[0027] Figure 5 Schematic diagram of the expansion of the conical geodesic grid structure.

[0028] Figure 6 It is a schematic diagram of the helix angle and the bundle width of the close-packed helix;

[0029] Figure 7 It is a schematic diagram of the equal thickness laying of closely packed spiral lines in the cone segment;

[0030] Figure 8 It is a schematic diagram of the longitudinal section of the cone segment used for expansion correction;

[0031] Fig. 9 It is a schematic diagram of the winding state of the hybrid triangular mesh structure of the cone composite material;

[0032] Fig.10 It is a schematic diagram of the curing state of the hybrid triangular mesh structure of the cone composite material;

[0033] Fig.11 It is a top view of the three-dimensional model of the male mold of the cone-surface composite material hybrid triangular grid structure forming tooling;

[0034] Fig.12 It is a schematic diagram of the winding trajectory of the fiber tow of the cone surface composite material hybrid triangular grid structure double-end winding;

[0035] Fig.13 It is a schematic diagram of the winding trajectory of the large end-to-end winding fiber tow of the hybrid triangular grid structure of the conical composite material;

[0036] Fig.14 It is a schematic diagram of the longitudinal section of the lower head of the cone surface composite material hybrid triangular grid structure forming tooling;

[0037] Fig.15 It is a cross-sectional view of the large end-to-end winding of the cone-surface mixed triangular grid structure hard mold forming tooling;

[0038] Fig.16 It is a three-dimensional picture of the cone surface composite material hybrid triangular grid structure after winding and before the head is removed;

[0039] Fig.17 It is a schematic diagram of the aluminum backing plate and the silicone rubber grid soft mold;

[0040] Fig.18 This is a cross-sectional view of the aluminum pad;

[0041] Fig.19It is a schematic diagram of a silicone rubber mesh soft mold;

[0042] Fig. 20 It is the positive mold of the silicone rubber rib groove grid that is cast;

[0043] Fig.21 Schematic diagram comparing the cone surface and the three unfolded spiral lines.

[0044] Fig. 22 Schematic diagram of the hybrid triangular mesh structure with equal pitch spiral ribs;

[0045] Fig.23 Schematic diagram of a hybrid triangular mesh structure with spiral ribs of equal helical angles;

[0046] Fig.24 Schematic diagram of the hybrid triangular mesh structure with geodesic spiral ribs.

[0047] Reference numerals:

[0048] 1 mandrel, 2 lower head, 3 lower flange, 4 core mold, 5 aluminum split male mold, 6 steel sleeve, 7 upper flange, 8 upper head, 9 retaining ring, 10 key, 11 small key,

[0049] 12 upper pressure ring, 13 outer mold, 14 small hoop, 15 large hoop, 16 lower pressure ring,

[0050] 17 The silicone rubber male mold casting mold comprises a left end frame,

[0051] 18 equal pitch spiral rib silicone rubber grid male mold casting mold bottom plate,

[0052] 19 equal helical angle spiral rib silicone rubber grid positive mold casting mold bottom plate,

[0053] 20 short-range spiral rib silicone rubber grid male mold casting mold bottom plate,

[0054] 21 short end frame 1, 22 right end frame, 23 short end frame 2, 24 bolts, 25 steel sleeve, 26 upper cover plate,

[0055] 101 upper end frame, 102 upper end frame, 103 bidirectional spiral reinforcement, 104 ring reinforcement,

[0056] 111 aluminum backing plate, 112 silicone rubber grid soft mold. DETAILED DESCRIPTION

[0057] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0058] The inventor of the present application has found that the hyperbolic oblique rib skinless composite mesh structure has been designed, produced, and tested, and can be used in rocket interstages, satellite brackets and other structures. Due to the meridian curvature of the rotating single-leaf hyperboloid, the single-leaf hyperboloid composite mesh structure is concave and has a poor aerodynamic shape. Therefore, the cone section structure with a small structure size and a limited inner envelope size or a cone section structure with requirements for aerodynamic shape should be designed as a cone surface composite mesh structure.

[0059] The present application provides an automatically formed conical composite material hybrid triangular grid structure and its forming tooling. The automatically formed conical composite material hybrid triangular grid structure and its forming tooling are reasonably designed to achieve low cost and light weight of the structure, and the forming tooling is suitable for automatic batch production of automatically formed conical composite material hybrid triangular grid structures.

[0060] Embodiment 1

[0061] Figure 1 This is a stereoscopic diagram of a cone composite material hybrid triangular mesh structure according to an embodiment of the present application; the skin is not shown to clearly show the mesh. Figure 1 As shown, the embodiment of the present application provides an automatically formed conical composite material hybrid triangular grid structure, including an upper end frame 101, a lower end frame 102, a bidirectional spiral rib 103, and an upper ring rib, a middle ring rib, and a lower ring rib; wherein:

[0062] The outer contour surface of the hybrid triangular mesh structure is a conical surface;

[0063] The upper end frame 101, the lower end frame 102, the bidirectional spiral ribs 103 and the ring ribs 104 are an integrally formed structure, and the ring ribs 104 include upper ring ribs, middle ring ribs and lower ring ribs;

[0064] The upper frame 101 and the lower frame 102 are both "L" shaped;

[0065] The bidirectional spiral ribs 103 are symmetrical to each other; the center line of the outer contour surface of the bidirectional spiral ribs 103 includes an equal pitch spiral line, an equal helical angle spiral line and a short distance line;

[0066] The center line of the outer contour surface of the ring rib 104 is a circle on the cone surface, the middle ring rib is located in the middle of the mixed triangular grid structure, and the upper ring rib and the lower ring rib are evenly distributed along the upper end frame and the lower end frame.

[0067] The conical composite material hybrid triangular mesh structure of the embodiment of the present application is suitable for a conical segment structure with a small structural size and a limited inner envelope size or a conical segment structure with requirements for aerodynamic shape. The conical composite material hybrid triangular mesh structure of the embodiment of the present application meets the requirements of productization, has good structural integrity, good molding processability, and high production efficiency, thereby realizing a low-cost, lightweight, and rapid prototyping composite material mesh structure.

[0068] During implementation, the cross-sections of the bidirectional spiral reinforcement and annular reinforcement are both trapezoidal, and the center lines of the annular reinforcement cross-sections are all along the normal of the cone surface; all bidirectional spiral reinforcements and annular reinforcements together form a mixed triangular grid structure with alternating triangles and rhombuses.

[0069] In practice, the material of the hybrid triangular grid structure is carbon fiber or epoxy resin composite material.

[0070] Specifically, equal pitch helical lines, equal helical angle helical lines and short-range lines are simple and feasible in terms of technology.

[0071] Specifically, by adjusting the position of the symmetry plane of the bidirectional spiral reinforcement, the middle ring reinforcement is located in the middle of the overall structure of the hybrid triangular grid structure.

[0072] During implementation, the bidirectional spiral ribs and annular ribs are automatically and continuously wound into shape.

[0073] In practice, for a truncated cone section with a height of 415 mm, a lower end diameter of φ = 950 mm, and a semi-cone angle β = 15°;

[0074] The equation of the cone generatrix of the hybrid triangular mesh structure is: The z value range is (1357.72,1772.72), and the coordinate origin is at the vertex of the cone.

[0075] The conical composite material mixed triangular grid structure can be designed as a conical equal-pitch spiral rib composite material mixed triangular grid structure, a conical equal-helix angle spiral rib composite material mixed triangular grid structure, and a conical short-range line spiral rib composite material mixed triangular grid structure that is simple and feasible in terms of process. The bidirectional spiral ribs are respectively swept along the conical equal-pitch spiral line, the conical equal-helix angle spiral line, and the conical short-range line.

[0076] In practice, for a truncated cone section with a height of 415 mm, a lower end diameter of φ = 950 mm, and a semi-cone angle of β = 15°, the center line equation of the outer contour surface of one of the two-way spiral ribs is:

[0077] 1) Conical surface equal pitch helix trajectory equation:

[0078]

[0079] 2) Equation of the helix trajectory of the cone with equal helix angle:

[0080]

[0081] 3) Cone surface geodesic trajectory equation:

[0082]

[0083] or

[0084] (x, y, z) are the coordinates of the point on the curve, and θ is the parameter. For ease of comparison, the starting and ending points of the three conical spirals coincide.

[0085] In practice, the cross-sections of the bidirectional spiral reinforcements are all congruent trapezoids, with the geometric dimensions of the trapezoidal cross-section being 9 mm in height, 6 mm in width at the top and 15° at the bottom. The bending and torsion loads jointly determine that the height-to-width ratio of the reinforcement should be greater than or equal to and less than or equal to

[0086] Preferably, the bending and torsion loads jointly determine that the aspect ratio of the rib is 1.5, thereby taking into account both strength and stiffness, and bending resistance and torsion resistance.

[0087] Optionally, the bending and torsion loads jointly determine that the aspect ratio of the ribs can be 1.6, thus approaching the golden ratio value.

[0088] Specifically, the trapezoidal section is perpendicular to the center line of the outer contour surface of the bidirectional spiral rib, the center line of the trapezoidal section points to the direction of the cone rotation axis, and the midpoint of the lower base of the trapezoidal section is swept along the center line of the outer contour surface of the oblique rib to form the oblique rib.

[0089] In implementation, for a truncated cone section with a height of 415 mm, a lower end diameter of φ=950 mm, and a semi-cone angle β=15°, the center line of each annular rib cross section is a circular ring on the cone surface.

[0090] The center line of the trapezoidal section is along the normal line of the cone surface, and the midpoint of the lower base of the trapezoidal section is swept along the center line of the outer contour surface of the ring rib to form the ring rib.

[0091] In practice, the cone-surface composite material hybrid triangular grid structure can be designed as a structure with skin or without skin. The skin of the cone-surface composite material hybrid triangular grid structure is formed by combining automatic winding with close-packed spiral equal-thickness automatic placement.

[0092] The equation of the dense spiral line for the automatic placement of skin with equal thickness is:

[0093]

[0094] z0=1352.56. Adjust the z0 value to get skin layers with different helix angles.

[0095] To explain the sources and basis of formula (8), formula (12), formula (26), formula (27), and formula (45), the following is an explanation of the equations and structural parameter determination methods in this application:

[0096] 1) Design of conical surface equal pitch spiral reinforcement grid structure

[0097] For the convenience of comparison, the simplest equal-pitch spiral rib grid structure in the cone segment grid structure is designed first, and then the equal-helix angle spiral rib grid structure and the short-range spiral rib grid structure are designed.

[0098] The structural parameters of the conical segment equal pitch helix mesh are calculated as follows.

[0099] The height of the truncated cone section is 415 mm, the lower end diameter φ = 950 mm, and the semi-cone angle β = 15°. Figure 2 shown.

[0100] Equation of the trajectory of the equal pitch conical helix (cone-cylindrical helix short-range line and grid winding molding technology [J]. Aerospace Materials and Technology, 2018, 49 (1) 22-29 Equation 5):

[0101]

[0102] Helix angle calculation formula:

[0103]

[0104] Depend on Figure 2 Geometric relations:

[0105]

[0106]

[0107] From (4), we can get:

[0108]

[0109]

[0110] The meaning and calculation of structural parameters are shown in the following table:

[0111]

[0112]

[0113] The trajectory equation of the equal pitch conical helix is:

[0114]

[0115] For the convenience of comparison, the upper and lower end points of the spiral reinforcement are made to coincide with the two intersection points of the equal pitch spiral line and the upper and lower end surfaces of the structure, as shown in Figure 3 As shown. The angle difference between the upper and lower ends of the equal pitch helix:

[0116] ∠AOB=Δθ=θ 下端 -θ 上端 =20.93645° Formula (9)

[0117] therefore Figure 3 The coordinates of each point of the structure shown are:

[0118] A(475,0,0), B(443.6392,169.7328,0),

[0119] C(339.7819,129.9978,415), D(363.801,0,415)

[0120] The arc of the conical segment equal pitch helix AC = 456.3 mm is calculated by formula 11 of "Short-range line and grid winding molding technology of conical cylindrical helix [J]. Aerospace Materials and Technology, 2018, 49(1)22-29".

[0121] Figure 3 Among the three arcs between points AC, the one on the right is an equal-pitch spiral, the one in the middle is an equal-helix angle spiral, and the one on the left is a short-range line.

[0122] After optimization calculation, the interval between the oblique reinforcement is 9°, and three ring reinforcements are added. The reinforcement height is 9mm. The reinforcement width is 6mm. The end frame is "L" shaped, such as Figure 4 shown.

[0123] The angle ψ between the symmetry plane of the bidirectional spiral reinforcement and the starting point of the lower end of the oblique reinforcement is calculated as follows:

[0124]

[0125] 2×8.218225°-2×9°=-1.56355°

[0126] When the lower ends of the two symmetrical oblique bars are 1.56355° apart, Figure 3 In the middle, ∠AOE = 1.56355°, which is equivalent to ψ = 8.218225°. The middle ring rib is located in the middle of the structure. Considering the large diameter of the lower end, ∠AOE = 1°. The lower end point is symmetrical at half of ∠AOE, i.e. 0.5°. Figure 3 After AC is symmetrical, EG is obtained. In this way, the ring reinforcement can be placed in the middle of the structure, so that the position of the node in the structure is optimized.

[0127] The center line of the ring reinforcement section is along the normal line of the cone surface, such as Figure 4 I is shown in the enlarged figure.

[0128] 2) Design of spiral reinforcement grid structure with equal spiral angle on cone surface

[0129] The difference between the spiral rib grid structure with equal helical angle on the conical surface and the spiral rib grid structure with equal pitch on the conical surface is only that the center line of the outer surface of the spiral rib is different, and the other structural parameters are the same.

[0130] The trajectory equation of the conical helix with equal helix angle (cone-cylinder helix short-range line and grid winding forming technology [J]. Aerospace Materials and Technology, 2018, 49 (1) 22-29 Equation 4):

[0131]

[0132] The parameter values ​​of the fourth formula in formula (11) are:

[0133] ρ=ρ 下端 =1835.26,ρ0=ρ 上端 =1405.62

[0134] The half cone angle β = 15°, the angle difference between the upper and lower ends of the equal pitch helix is ​​shown in formula 9,

[0135] Right now:

[0136] From this we can calculate: α = 19.52460617°.

[0137] The trajectory equation of the helix line with equal helix angle on the conical surface is:

[0138]

[0139] The arc of the conical equal pitch helix AC = 455.84 mm is calculated by formula 8 of "Short-range line and grid winding molding technology of conical cylindrical helix [J]. Aerospace Materials and Technology, 2018, 49(1)22-29".

[0140] 3) Conical surface geodesic spiral rib grid structure design

[0141] The difference between the conical surface geodesic spiral rib grid structure and the conical surface equal pitch spiral rib grid structure is only the center line of the outer surface of the spiral rib, and the other structural parameters are the same.

[0142] Cone geodesic trajectory equation (cone-cylinder spiral geodesic and grid winding molding technology [J]. Aerospace Materials and Technology, 2018, 49 (1) 22-29 Equation 66):

[0143]

[0144] In formula (13), φ = θ·sinβ. Expand at 72°.

[0145] Figure 5 In the left figure, ∠AO′I=72°·sin15°=18.63497125°,

[0146] ∠AO′B=20.93645°·sin15°=5.418751997°

[0147] The coordinates of each point of the structure expansion are:

[0148] A(1835.26,0), B(1827.058427,173.3111995),

[0149] C(1399.338441,132.7385157), D(1405.62,0).

[0150] AC=455.68mm.

[0151] The lower endpoints are symmetrical at 0.5°, that is:

[0152] ∠AO′E=1°·sin15°=0.258819045°.

[0153] The short-range spiral pitch is still 9°.

[0154] ∠AO′L=9°·sin15°=2.329371406°

[0155]

[0156] ∠ADB=∠ACB=∠CAD+∠AO′B=22.3542927°

[0157] Figure 5 Right figure, calculate the coordinate x of point J on the ZOX plane J , z J .

[0158] ∠AMJ=180°·sin15°=46.58742812°

[0159] ∠OMJ=∠OMA+∠AMJ=15°+46.58742812°=61.58742812°

[0160] ∠OAJ=∠OAM+∠MAJ=∠OAM+∠CAD=75°+16.93554073°

[0161] =91.93554073°

[0162] AK=AM·sin∠AMJ=1836.26·sin46.58742812°=1333.176713

[0163] ∠AJK=180°-∠AJM=180°-(360°-90°-∠OAJ-∠OMJ)

[0164] =63.52296885

[0165] KJ=AK·cot∠AJK=664.0302214

[0166] KM=AM·cos∠AMJ=1261.276782

[0167] JM=KM-KJ=597.2465607

[0168] x J =JM·sin∠OMJ=525.3047425,

[0169] z J =OM-JM·cos∠OMJ=1488.54394,

[0170] The coordinates of points A and M on the ZOX plane are: A(0,475), M(1772.724134,0)

[0171] r=475,h=1772.724134.

[0172]

[0173] The short-range arc of the cone surface AC = 455.68 mm.

[0174] The geodesic equation on the side of the cone can also be solved analytically using the Chairaut relationship.

[0175] Clairaut relation:

[0176] r1 sinα1=rsin90°=const Formula (15)

[0177] Where: r1 is the radius of any point on the busbar; α1 is the helix angle of this point; r=const is the polar hole radius of the short-range helical winding line.

[0178] R = ztanβ Formula (16)

[0179] "3D modeling and mold design of C / E composite grid winding structure [J]. Aerospace Materials and Technology, 2010, 40(4)23-26" Formula 9:

[0180]

[0181]

[0182] The above formula only takes positive values.

[0183] From formula (15), we get:

[0184] Rsinα=Rcosαtanα=c Formula (19)

[0185] Substituting formula (17) into formula (19), we get:

[0186]

[0187] Right now

[0188]

[0189] Only positive values ​​are taken, and the above formula is integrated to obtain:

[0190]

[0191]

[0192]

[0193] The coordinate systems are different when deriving the two equations. The origins of the coordinates differ in height h and are in opposite directions. In order to make the lower endpoints of the conical short-range lines all on the x-axis, after expanding the equation zh, yz takes a negative sign (rotates 180° around the x-axis), and the integral constant of the other equation θ is taken

[0194]

[0195] In formula (25):

[0196]

[0197]

[0198] When z = 1772.724134, θ = 0° in equation (27); when z = 1357.724134, θ = 20.93645°. It can be proved that the short-range line in equation (27) is Figure 3 The helix angle α at point A shown is equal to Figure 5 ∠CAD shown.

[0199] Find the tangent line of equation (27):

[0200]

[0201] When z=1772.724134, that is, at point A:

[0202]

[0203] The cone generatrix at the lower end point A is φ=105°, θ=0°

[0204]

[0205] Considering the different coordinate systems of equations (29) and (30), a1=-tan15.

[0206] Short-range line Figure 3 The helix angle α at point A is shown:

[0207]

[0208] α=∠CAD Formula (32)

[0209] Since the short-range lines expressed by equations (26) and (27) are on the same conical surface, have the same starting point and the same spiral angle at the starting point, it can be seen from Clairaut's rule that equations (26) and (27) represent the same short-range line; the three-dimensional structural modeling also shows that the curves constructed by equations (26) and (27) are the same curve.

[0210] 4) Hyperbolic helix and chain helix on cone surface

[0211] In addition to the above three types of conical spiral rib composite mesh structures, other conical spiral lines can be derived based on the equal-pitch conical spiral line, thereby obtaining other conical spiral rib composite mesh structures.

[0212] For example, on the basis of the equal pitch conic helix ρ=aθ, let a=ρθ, and we get the hyperbolic helix:

[0213]

[0214] Still let the upper and lower endpoints of the hyperbolic helix coincide with the two endpoints of the equal pitch helix. ρ1=1405.62,ρ2=1835.26,a=ρ1θ1=ρ2θ2,

[0215]

[0216] The solution is: θ1 = 1.561, θ2 = 1.19559

[0217]

[0218] make Get the chain spiral:

[0219]

[0220] Let the upper and lower endpoints of the interlocking spiral coincide with the two endpoints of the equal pitch spiral. ρ1=1405.62,ρ2=1835.26,

[0221]

[0222] The solution is: θ1 = 0.883909804, θ2 = 0.518499818,

[0223]

[0224] The conical hyperbolic helix and interlocking helix are not as simple as the conical equal-pitch helix, and the corresponding grid structure is not as manufacturable as the conical equal-pitch spiral rib grid structure, so they are not designed in detail.

[0225] 5) Equation of close-packed spirals on a cone

[0226] like Figure 6 As shown, assuming that the width of the fiber bundle during automatic placement is d, there are n fiber bundles in total. The circumference at R0 is: 2πR0 = nd, and the circumference at R is: 2πR = nd R .

[0227] In order to automatically lay the center line of the fiber tow along the dense spiral line on the cone surface, then:

[0228] d=d R cosα Formula (39)

[0229] thereby

[0230] R0=Rcosα Formula (40)

[0231]

[0232] R0: R when β = 0 is R0

[0233] Combining formula (17), we can know that:

[0234]

[0235]

[0236] Points can be obtained:

[0237]

[0238] The equation of the close-packed spiral on the conical surface is:

[0239]

[0240] z0=1352.56. Adjust the z0 value to get skin layers with different helix angles.

[0241] like Figure 7 As shown, the densely packed spiral wires are used for the automatic placement of fiber bundles in the skin of conical sections and curved mother lines composite materials to obtain skins of equal thickness.

[0242] Embodiment 2

[0243] The embodiment of the present application provides a hard mold forming tool for realizing the automated and precise forming of a hybrid triangular grid structure of a conical composite material.

[0244] Hard mold forming tooling for cone composite material hybrid triangular grid structure,

[0245] like Fig. 9 As shown, in the winding state, it includes a mandrel 1, a lower head 2, a lower flange 3, a core mold 4, an aluminum split male mold 5, a steel sleeve 6, an upper flange 7, an upper head 8, a retaining ring 9, a key 10, and a small key 11;

[0246] like Fig.10 As shown, in the forming state, it includes a core mold 4, an aluminum split male mold 5, a steel sleeve 6, an upper pressure ring 12, an outer mold 13, a small hoop 14, a large hoop 15, and a lower pressure ring 16; three types of conical mixed triangular composite material grid structure hard mold forming tools share the same core mold.

[0247] In practice, the outer contour surface of the aluminum split male mold 5 is a conical surface with corrected expansion geometric parameters.

[0248] For a truncated cone section with a height of 415 mm, a lower end diameter of φ = 950 mm, and a semi-cone angle of β = 15°, the generatrix equation of the outer contour cone surface of the aluminum split male mold 5 is: The value range of z is (1354.7,1768.8), and the coordinate origin is at the vertex of the cone.

[0249] The outer contour surface of the aluminum split male mold 5 is a cone surface whose geometric parameters are corrected by taking into account the expansion amount, and the center line of the oblique rib groove is a cone spiral line whose geometric parameters are corrected by taking into account the expansion amount; the cross sections of the spiral rib groove and the annular rib groove are both trapezoidal, and the center line of the annular rib groove cross section is along the corrected cone normal line; the inner contour surface of the female mold of the forming device is an uncorrected cone surface; the forming device has upper and lower ellipsoid heads, and its positioning dimensions and outer contour geometric parameters are determined by precise calculation. Thus, accurate forming of the structure is achieved.

[0250] The position of the symmetry plane of the bidirectional spiral ribs is adjusted, thereby adjusting the node position to optimize its position in the structure. The automated winding process increases the tension of the fiber bundle to ensure the continuity of the fiber bundle at the node, and the curing tank is formed to improve the node molding quality. The optimal structural parameter combination is combined with the optimal process molding method to design and manufacture the optimal structure.

[0251] In practice, the center line of the rib groove on the aluminum split male mold 5 for forming the structural bidirectional spiral rib is a conical spiral line with modified expansion geometric parameters.

[0252] For a truncated cone section with a height of 415 mm, a lower end diameter of φ = 950 mm, and a semi-cone angle β = 15°, the centerline equation of a spiral rib groove in the rib groove for forming a bidirectional spiral on the aluminum split male mold (5) is:

[0253] 1) Equation of the helix trajectory of the hard die cone with equal pitch:

[0254]

[0255] 2) Equation of the helix trajectory of the hard die cone with equal helix angle:

[0256]

[0257] 3) Hard die cone short-range trajectory equation:

[0258]

[0259] or

[0260] (x, y, z) are the coordinates of the point on the curve, and θ is the parameter; the starting points and end points of the three conical spirals coincide.

[0261] The bidirectional spiral rib groove is processed by a tool having an oblique rib cross-section shape, which is perpendicular to the center line of the spiral rib groove, the center line of the tool points to the direction of the rotation axis of the outer surface of the forming tool male mold, and is processed along the center line of the bidirectional spiral rib groove.

[0262] During implementation, the position of the symmetry plane of the bidirectional spiral rib groove of the hard mold forming tooling is the same as the position of the symmetry plane of the bidirectional spiral rib groove of the structure.

[0263] For the truncated cone section with a height of 415 mm, a lower end diameter of φ=950 mm, and a semi-cone angle of β=15°, the angle between the symmetry plane and the xoz plane is 0.5°, and the above-mentioned spiral rib groove is symmetrically obtained through this symmetry plane to obtain another spiral rib groove.

[0264] During implementation, the center line of the annular rib groove forming the structural annular rib on the aluminum split male mold 5 is a circle on the cone surface whose geometric parameters have been corrected taking into account the expansion amount, and the center line of the annular rib groove section is along the corrected cone surface normal; the annular rib groove is processed by the tool center line of the annular rib cross-section shape along the corrected cone surface normal and the center line of the oblique rib groove.

[0265] The following is an explanation of the design process of the hard mold forming tooling:

[0266] For the convenience of comparison, the parameters of the cone segment equal pitch helical wire grid structure forming device are calculated first, and then the other two cone surface composite material grid structure forming devices are designed.

[0267] Calculation of the semi-cone angle β after taking the expansion into account:

[0268] The thickness of the upper and lower end frames is 8mm. Figure 8 The four points A1B1C1D1 are shown, and the thickness of the end frame is removed, and only the solid part is calculated. H2 is the distance between the straight lines A1B1 and C1D1.

[0269] A1B1=2×8×tan15°+727.602=731.889

[0270] C1D1=950-2×8×tan15°=945.713

[0271] Expansion calculation:

[0272] Diameter (steel core mold, aluminum split mold) thermal expansion coefficient difference Δα=10.7

[0273] ΔA1B1=731.889×10.7×110×10 -6 =0.861

[0274] ΔC1D1=945.713×10.7×110×10 -6 =1.113

[0275] Height (aluminum split mold) thermal expansion coefficient difference Δα=20

[0276] ΔH2=399×20×110×10 -6 =0.8778

[0277]

[0278] Since ΔA1OB1 is similar to ΔC1OD1,

[0279]

[0280] Solving for H1 = 1362.659

[0281] H=H1+H2=1760.759

[0282]

[0283] β=15.015°

[0284] Calculation of the upper and lower end diameters and a after taking into account the expansion:

[0285] φ 上端 =731.03-2×8×tan15.015°=726.74

[0286] φ 下端 =944.6+2×8×tan15.015°=948.892

[0287] The ∠AOB on the rotating single-leaf hyperboloid oblique rib composite grid structure forming device is the same as the structure, that is: ∠AOB = Δθ = 0.36541 radians = 20.93645°

[0288] ρ 下端 -ρ 上端 =aΔθ

[0289] 1831.33-1402.58=0.36541a

[0290] From this solution, we can get: a = 1173.34 mm / radian

[0291] The meaning and calculation of molding device parameters are shown in the following table:

[0292]

[0293] The trajectory equation of the hard die equal pitch conical helix:

[0294]

[0295] Hard mold forming tooling Fig. 9 , Fig.10 and Fig.11 .

[0296] Design of aluminum alloy hard die forming device for spiral rib grid structure with equal spiral angle on conical surface

[0297] The trajectory equation of the helix line with equal helix angle in the conical segment is formula (11).

[0298] The parameter values ​​of the fourth formula in formula (11) are:

[0299] ρ=ρ 下端 =1831.33,ρ0=ρ 上端 =1402.58

[0300] Half cone angle β = 15.015°, angle difference between the upper and lower ends of the equal pitch helix

[0301] ∠AOB=Δθ=θ 下端 -θ 上端 =20.93645°.

[0302] Right now:

[0303] From this we can calculate: α = 19.54078765°.

[0304] The trajectory equation of the helix line with equal helix angle on the hard die cone surface is:

[0305]

[0306] The cone segment equal helix angle helical wire mesh structure hard mold forming device and the cone segment equal pitch helical wire mesh structure hard mold forming device share the core mold, only the male mold spiral rib groove is different, and the cone segment equal helix angle spiral rib groove can be processed on the male mold according to formula (47). Since the cone surface equal helix angle helix contains an exponential function, it has higher requirements on the processing equipment.

[0307] Design of aluminum alloy hard die forming device for conical geodesic spiral rib grid structure

[0308] The equation of the cone surface geodesic trajectory is formula (13), where φ = θ·sinβ.

[0309] Figure 5 In the left figure, ∠AO′B=20.93645°·sin15.015°=5.424046195°

[0310] The coordinates of each point of the mold male mold are:

[0311] A(1831.33,0), B(1823.130002,173.1085335),

[0312] C(1396.299781,132.5804562), D(1402.58,0).

[0313]

[0314]

[0315] ∠ADB=∠ACB=∠CAD+∠AO′B=22.3732485°

[0316] Figure 5 Right figure, calculate the coordinate x of point J on the ZOX plane J , z J .

[0317] ∠AMJ=180°·sin15.015°=46.6329447°

[0318] ∠OMJ=∠OMA+∠AMJ

[0319] =15.015°+46.6329447°=61.6479447°

[0320] ∠OAJ=∠OAM+∠MAJ=∠OAM+∠CAD

[0321] =74.985°+16.9492023°=91.9342023°

[0322] AK=AM·sin∠AMJ

[0323] =1831.33·sin46.6329447°=1331.321277

[0324] ∠AJK=180°-∠AJM

[0325] =180°-(360°-90°-∠OAJ-∠OMJ)=63.582147°

[0326] KJ=AK·cot∠AJK=661.390754

[0327] KM=AM·cos∠AMJ=1257.518678

[0328] JM=KM-KJ=596.1279241

[0329] x J =JM·sin∠OMJ=524.6201524,

[0330] z J =OM-JM·cos∠OMJ=1485.91796,

[0331] The coordinates of the known points A and M on the ZOX plane are:

[0332] A(0,474.446),M(1768.80416,0).

[0333] Therefore r = 474.446, h = 1768.80416.

[0334] The trajectory equation of the short-range line of the hard die cone surface is:

[0335]

[0336] The conical geodesic trajectory equation can also be expressed as formula (25), where:

[0337] c=r·sin∠CAD=474.446·sin16.9492023=138.3122735 Formula (49)

[0338] The trajectory equation of the geodesic line of the hard die cone surface can be expressed as:

[0339]

[0340] Formula (50) is simpler than formula (48) and should be used in the processing of the male mold of the grid structure hard mold forming device. However, when calculating the constant c of formula (50), ∠CAD obtained in the process of solving formula (48) is used.

[0341] The cone segment geodesic grid structure hard mold forming device and the cone segment equal pitch helical grid structure hard mold forming device share the core mold, only the male mold spiral rib groove is different, and the cone segment geodesic spiral rib groove can be processed on the male mold according to formula 50. Since the conical surface geodesic contains inverse trigonometric functions, the processing equipment is required to be relatively high.

[0342] The cone segment short-range line grid structure hard mold forming device is suitable for composite grid structures that require uniform force, high dimensional accuracy, and are precisely wound according to short-range lines and designed as an integrated part of a separation structure.

[0343] Through the above comparative design, from the perspective of simple process and low production cost, the equal pitch conical spiral wire mesh structure hard mold forming device is recommended among the three types of conical segment mesh structure hard mold forming devices. It can also be selected according to the actual situation of engineering application and the characteristics of the male mold of the three types of conical segment mesh structure hard mold forming devices. For example, the composite mesh structure designed as a whole with the separation structure should use the conical segment geodesic wire mesh structure hard mold forming device.

[0344] Fiber tow winding trajectory of hybrid triangular grid structure of conical composite material

[0345] As mentioned above, the arc of the conical segment equal pitch helix AC=456.3mm, the arc of the conical equal pitch helix AC=455.84mm, and the arc of the conical surface short-range line AC=455.68mm. The difference between the three is very small. Considering that the fiber tow is also constrained by the rib groove during tension winding, the three grid structures can share the short-range line winding trajectory. After the process molding test, the conical segment equal pitch helix with the longest arc length also achieved automatic winding molding, so it is feasible for the three grid structures to share the short-range line winding trajectory in terms of technology.

[0346] like Fig. 9 As shown, in order to realize automatic winding, the forming device contains an upper and a lower ellipsoidal head.

[0347] In order to achieve continuous and smooth winding, the outer contour surface of the ellipsoidal head needs to be tangent to the structural cone surface. 9.1) The formula of the short-range line on the ellipsoidal head

[0348] Let the ellipsoid generatrix be:

[0349]

[0350] The tangent line of the generatrix is:

[0351]

[0352] The z-axis is used as the rotation axis to form a rotation surface, and the direction vector of the generatrix tangent is:

[0353] Assume that the parametric equation of the ellipsoidal geodesic with φ as parameter is:

[0354]

[0355] The direction vector of the helix tangent is:

[0356]

[0357] The angle between the generatrix tangent and the helix tangent, that is, the helix angle α, satisfies the following relationship:

[0358]

[0359]

[0360] From formula (57), we can know that:

[0361]

[0362] Multiply both sides by R 2 =g 2 (φ)=a 2 cos 2 φ(Formula (51) 1st formula),

[0363] From Chairaut's relation (15):

[0364]

[0365] The solution is:

[0366]

[0367] Due to the symmetry of the helix on the surface of revolution, only the positive sign is taken in the above formula.

[0368] Let asinα′=c, that is, α′ is the spiral angle of the short-range line of the ellipsoidal surface at the major semi-axis of the ellipse.

[0369]

[0370] 9.2) Design of winding trajectory of upper head and calculation of short-range length of ellipsoidal surface

[0371] a=kb Formula (61)

[0372]

[0373] Cone upper radius

[0374]

[0375] c=asinα′=rsin∠CAD=138.3654336° Formula (64)

[0376]

[0377] φ2=90°-α′ Formula (66)

[0378]

[0379] 2×(θ2-θ1)-18×9°=5×9°-20.93645°×2-1°=2.1271°(68)

[0380] Solve the equations composed of equations (61)-(68), and the obtained parameter values ​​are shown in the following table:

[0381]

[0382] z=bsinφ1=81.30413258

[0383] The distance from the top of the cone to the upper end of the truncated cone is 1357.723816, and the z coordinate of the center of the ellipsoid is 1439.027949.

[0384] The relationship between the coordinate systems:

[0385] The origin of the cone coordinate system is Figure 2 The top of the cone is shown in the figure. The Z axis is the height direction of the cone, and it points from the top of the cone to the bottom of the cone. The origin of the ellipsoidal geodesic coordinate system is at the center of the ellipsoid. The distance from the center of the ellipsoid to the top of the cone is 1439.027949. The Z axis is opposite to the cone coordinate system, and the X axis is Figure 3 The X-axis of the coordinate system rotates -15.8280012 (20.93645-θ1) around the Z-axis of the cone coordinate system.

[0386] Ellipsoid geodesic equation:

[0387]

[0388] in:

[0389] a=374.5353262, b=342.0510743

[0390]

[0391] In order to achieve continuous winding with tension, the length of the short-range line on the ellipsoid surface must be accurately calculated:

[0392] The parametric equation of the ellipse is (61),

[0393] Assume that the angle between the tangent line of the ellipse generatrix and the Z axis is γ ，

[0394]

[0395] The angle between the tangent line of the ellipse generatrix and the tangent line of the ellipsoid short-range line is α

[0396]

[0397] The values ​​of the major-minor axis ratio k, the angle α′ between the tangent line of the ellipsoid generatrix and the tangent line of the ellipsoid short-range line, the minor semi-axis b of the ellipsoid, the starting angle φ1 of the ellipse, and the ending angle φ2 of the ellipse are shown in the table above.

[0398] The integral gives the arc length of the short-range line on the ellipsoid: L = 471.0310935 mm

[0399] Design of winding trajectory of lower head

[0400] The eight equations (61)-(68) are still used to solve the structural parameters, but the specific values ​​of equations (63) and (68) have changed:

[0401] Cone lower end radius

[0402]

[0403] 2×(θ1+θ2)-18×9°=∠AOE=1° Equation (68)

[0404] The values ​​of the parameters obtained by solving the equations are shown in the following table:

[0405]

[0406] z=bsinφ=40.554517, from the top of the cone to the lower end of the truncated cone: 1772.724134, z coordinate of the center of the ellipsoid: 1813.27865.

[0407] The relationship between the coordinate systems:

[0408] The conical surface and small head ellipsoid geodesic coordinate system are the same as above. The origin of the large head ellipsoid geodesic coordinate system 1 is at the center of the ellipsoid, and the distance from the center of the ellipsoid to the vertex of the cone is: 1813.27865. The Z axis direction is opposite to the conical surface coordinate system, and the X axis is Figure 3 The coordinate system X axis rotates 181.4835236° around the cone surface geodesic coordinate system Z axis. The origin of the ellipsoid geodesic coordinate system 2 is at the center of the ellipsoid, and the distance from the center of the ellipsoid to the vertex of the cone is 1813.27865. The direction of the Z axis is the same as that of the cone surface geodesic coordinate system, and the X axis is Figure 3 The X-axis of the coordinate system rotates 1.4835236° around the Z-axis of the conical geodesic coordinate system.

[0409] Single-piece winding of cone section and head:

[0410] 2×18×9°+2.1271°+1°+20.93645°×2=369°, 369°-360°=9°, which can be wound continuously. The winding trajectory of the fiber tow of the double-end conical composite material hybrid triangular grid structure is shown in Fig.12 .

[0411] 9.4) Design of fiber tow winding trajectory for large end-to-end winding of two products

[0412] In order to further reduce costs and improve efficiency, the length-to-short axis ratio of the head is increased, and the large end-to-end winding trajectory of the two products is designed.

[0413] Replace equation (68) in 9.2) with:

[0414] 2×(θ2-θ1)-16×9°=2.1271°.

[0415] The values ​​of the parameters obtained by solving the equations are shown in the following table:

[0416]

[0417] z=bsinφ=23.17931027

[0418] Cone top to upper end of truncated cone: 1357.723816

[0419] Ellipsoid center z coordinate: 1378.903126

[0420] Coordinate system and the relationship between the three coordinate systems:

[0421] The origin of the conical geodesic coordinate system is at the top of the cone, and the Z axis is the height direction of the cone, pointing from the top of the cone to the bottom of the cone. The origin of the ellipsoidal geodesic coordinate system is at the center of the ellipsoid, and the distance from the center of the ellipsoid to the top of the cone is 1378.903126. The Z axis is opposite to the conical geodesic coordinate system, and the X axis is the X axis of the conical geodesic coordinate system, which rotates -19.56396825° (20.93645-θ1) around the Z axis of the conical geodesic coordinate system.

[0422] A cylindrical spiral line is used in the middle to transition 5.5°.

[0423] The equation of a cylindrical helix is:

[0424]

[0425] The origin of the cylindrical helix coordinate system is at the bottom of the cone, 1772.723816 from the vertex of the cone, and the direction of the coordinate axis is the same as that of the conical surface geodesic coordinate system. The ellipsoid and its geodesic lines are symmetrical to the conical surface and its geodesic lines.

[0426] The distance between the symmetry plane and the vertex of the cone is 1847.595062, and the distance between the symmetry plane and the base of the cone is 74.87124626, which is the z value obtained by taking θ of 2.75° in the third equation of equation (72). After symmetry, the plane rotates 4.5° around the z axis.

[0427] (144°+2.1271°+1°+4.5°+20.93645°×2)×2=387°, 387°-360°=27°, 27° / 9°=3, 40 spiral ribs in total, which can be wound continuously. The winding track of the fiber bundle of two products with large ends wound together is shown in Fig.13 .

[0428] Ellipsoid head outer contour dimensions and positioning dimensions

[0429] Taking the double-head wrapped lower head as an example, the calculation method of the outer contour and positioning dimensions of the ellipsoidal head is as follows.

[0430] like Fig.14 As shown, the center of the ellipse is taken as the coordinate origin, the y-axis is taken as the horizontal coordinate, and the z-axis is taken as the vertical coordinate.

[0431] The winding trajectory is based on the outer surface of the structure. The head ellipsoid of the forming device should reduce the rib height and expansion amount, that is, reduce 9.554mm. The major axis of the ellipsoid is (480.403-9.554)×2=941.7mm, the minor semi-axis is 271.176-9.554=261.62mm, and the axial positioning dimension is 40.55-3=37.55mm.

[0432] Similarly, the outer contour dimensions and positioning dimensions of the ellipsoidal upper head can be calculated.

[0433] Embodiment 3

[0434] The embodiment of the present application provides a soft mold forming tool for realizing the automated and precise forming of a hybrid triangular grid structure of a conical composite material.

[0435] like Fig.17 As shown, the soft mold forming tool replaces the aluminum split male mold 5 of the hard mold forming tool of the second embodiment with an aluminum pad 111 and a silicone rubber mesh soft mold 112 (i.e., a silicone rubber male mold casting mold composition). In this way, the soft mold forming tool of the third embodiment and the hard mold forming tool of the second embodiment can share the core mold 4. At the same time, the silicone rubber mesh soft mold (i.e., a silicone rubber male mold casting mold composition) of the soft mold forming tool is shared.

[0436] Fig.19 It is a schematic diagram of a silicone rubber mesh soft mold; (it is to show the silicone rubber mesh positive mold casting mold bottom plate, and the upper cover plate of the main view is not shown).

[0437] like Fig.19As shown, the silicone rubber grid soft mold 112 (i.e., the silicone rubber positive mold casting mold) includes:

[0438] Left end frame 17;

[0439] Silicone rubber grid male mold casting mold bottom plate 18 with equal pitch spiral ribs;

[0440] Silicone rubber grid male mold casting mold bottom plate 19 with spiral ribs of equal helical angles;

[0441] Silicone rubber grid male mold casting mold bottom plate 20 for geodesic spiral ribs;

[0442] Short end frame 1 21 , right end frame 22 , short end frame 23 , bolts 24 , steel sleeve 25 , upper cover plate 26 .

[0443] Determine the neutral surface of the silicone rubber mesh soft mold.

[0444] The center line of the rib groove used to form the structural bidirectional spiral rib on the unfolded silicone rubber grid soft mold is a plane spiral line or a straight line whose expansion geometric parameters have been corrected.

[0445] For a truncated cone section with a height of 415 mm, a lower end diameter of φ = 950 mm, and a semi-cone angle of β = 15°, the centerline equation of a spiral rib groove in the bidirectional spiral rib groove of the silicone rubber grid soft mold of the soft mold molding tooling is expanded as follows:

[0446] 1) The trajectory equation of the soft mold equal pitch conical spiral line when it is unfolded on the neutral surface of the silicone rubber mesh soft mold:

[0447]

[0448] 2) The trajectory equation of the helix of the soft mold equal helical angle cone surface when it is unfolded on the neutral surface of the silicone rubber mesh soft mold:

[0449]

[0450] 3) The trajectory equation of the short-range line of the soft mold cone surface when it is unfolded on the neutral surface of the silicone rubber mesh soft mold:

[0451] y=-0.3045x+588.838358

[0452] During implementation, the conical composite material mixed triangular grid structure, bidirectional spiral ribs and annular ribs are automatically and continuously wound to form the structure. For this purpose, the winding trajectory needs to be accurately calculated to achieve simulated winding. The opposite end-to-end winding of the cone further improves efficiency, reduces costs and reduces material waste.

[0453] Solve the following eight equations to accurately calculate the automated continuous winding trajectory:

[0454] a=kb (s1)

[0455]

[0456]

[0457] c=rsinα=138.3654336° (s4)

[0458]

[0459] φ2=90°-α′ (s6)

[0460]

[0461] 2×(θ2-θ1)-18×9°=9×5°-20.93645°×2-1°=2.1271° (s8).

[0462] The following is an explanation of the design process of the soft mold forming tooling:

[0463] For the convenience of comparison, the soft mold forming device of the conical segment equal-pitch helical wire mesh structure is first designed, and then the soft mold forming device of the conical segment equal-helix angle spiral rib mesh structure and the conical segment short-range line spiral rib mesh structure are designed; and the upper and lower end points of the equal-helix angle spiral line and the short-range line are made to coincide with the end points of the equal-pitch spiral line.

[0464] In order to reduce the development cost, the aluminum pad and silicone rubber mesh soft mold are designed so that the conical composite material mesh structure soft mold forming device and the aforementioned hard mold forming device share the core mold; at the same time, except for the mesh bottom plate, the other parts of the silicone rubber soft mold casting mold are shared, further reducing costs.

[0465] The thickness of the silicone rubber male mold is 15mm, and the neutral layer is 4.5mm away from the outer surface of the aluminum pad. Since the position of the neutral layer can only be estimated, the structural dimensional accuracy prepared by the silicone rubber male mold is not as good as that of the aluminum alloy male mold. The four points ABCD are the four endpoints of the truncated cone segment, the four points PQRS are the intersections of the extension line of the outer surface of the aluminum pad and the upper and lower end surfaces of the truncated cone segment, and the four points TUVW are the intersections of the extension line of the neutral layer and the upper and lower end surfaces of the truncated cone segment. Fig.17 shown.

[0466] To facilitate demoulding, the aluminum backing plate is divided into 20 petals along the circumferential direction. Fig.18 shown.

[0467] Fig.19 Middle: 25 left end frame 26 equal pitch spiral rib silicone rubber grid positive mold casting mold bottom plate 27 equal helix angle spiral rib silicone rubber grid positive mold casting mold bottom plate 28 short-range spiral rib silicone rubber grid positive mold casting mold bottom plate 29 short end frame one 30 right end frame 31 short end frame two 32 bolts 33 steel sleeve 34 upper cover plate, to show the silicone rubber grid positive mold casting mold bottom plate, the upper cover plate is not shown in the main view.

[0468] Conical surface equal pitch helical wire grid structure hard mold forming device:

[0469] φ 上端 =726.74,φ 下端 =948.892

[0470]

[0471]

[0472]

[0473] Figure 5 Left: Calculation of the unfolding line parameters of three types of conical helices.

[0474] The uniform pitch conic spiral is expanded into an Archimedean spiral:

[0475] r=x0Θ Formula (73)

[0476]

[0477] in θ=sinβ·θ

[0478]

[0479] When the equal pitch helix is ​​unfolded on the neutral plane, since the generatrix length remains unchanged, a does not need to be corrected and is still 1173.34 mm / radian, the same as the hard die. This feature of the equal pitch helix is ​​conducive to simplifying design and processing.

[0480] The trajectory equation of the soft mold equal pitch conical helix when it is unfolded on the neutral surface of the silicone rubber mesh mold:

[0481]

[0482] Design of soft mold forming device for spiral mesh structure with equal helical angle on conical surface

[0483] A conic spiral with equal spiral angle can be expanded into a logarithmic spiral:

[0484] ρ(θ)=ρ0e cotα·Θ Formula (77)

[0485]

[0486] where Θ = sinβ·θ

[0487] ρ=ρ 下端 =1789.37,ρ0=ρ 上端 =1360.626

[0488] Half cone angle β = 15.015°, angle difference between upper and lower ends of pitch helix:

[0489] ∠AOB=Δθ=θ 下端 -θ 上端 =20.93645°.

[0490] ∠AO′B=Δθ·sinβ=5.424046195°

[0491] Right now:

[0492] From this we can calculate: α = 19.06536579°.

[0493] The trajectory equation of the soft mold conical helix with equal helical angle when it is unfolded on the neutral surface of the silicone rubber mesh mold is:

[0494]

[0495] Compared with the silicone rubber casting mold for the conical segment equal-helix angle helical wire mesh structure, the only difference between the silicone rubber casting mold for the conical segment equal-pitch helical wire mesh structure is the mesh bottom plate. The conical segment equal-helix angle helical rib grid can be processed on the mesh bottom plate according to formula (80).

[0496] Design of soft mold forming device for conical geodesic grid structure

[0497] The conical segment short-range line is unfolded into a straight line, connecting points A and C. The conical segment short-range line equation 48 is an analytical solution obtained by unfolding the side of the cone and using the shortest line segment between two points, and it can be proved that equation 48 and equation 50 are equivalent. Therefore, equation 48 is easy to understand that the rib grid of the male mold casting mold of the conical surface short-range line grid structure soft mold molding device is processed along the simplest straight line. Compared with the conical segment equal pitch helical grid structure silicone rubber casting mold, the conical segment short-range line grid structure silicone rubber casting mold only has a different grid bottom plate. By processing the straight rib grid on the grid bottom plate according to the straight line AC, the trajectory equation of the soft mold conical surface short-range line when unfolded on the neutral surface of the silicone rubber grid mold can be obtained:

[0498]

[0499] That is: y = -0.3045x + 588.838358 Formula (81)

[0500] Through the above comparative design, from the perspective of simple process and low production cost, the three types of cone segment grid structure soft mold forming devices are recommended to use the short-range grid structure soft mold forming device. It can also be selected according to the actual situation of engineering application and the characteristics of the male mold of the three types of cone segment grid structure soft mold forming devices. For example, when the equal pitch helix is ​​unfolded on the neutral plane, a does not need to be corrected, which is conducive to simplifying the design and processing.

[0501] The winding state of the molding device is as follows Fig. 9 and Fig.15 As shown; the curing state of the molding device is as follows Fig.10 shown.

[0502] like Fig. 9 and Fig.15 As shown, when the manufacturing tooling provided by the present invention is automatically winding and forming the conical composite material mixed triangular grid structure, the two ends of the core shaft 1 are placed on a trolley, and the core shaft 1 drives the entire tooling to rotate, so that the composite material grid structure is automatically wound and formed.

[0503] The cone composite material hybrid triangular grid structure is wound and before the head is removed. At this time, the fiber tow on the head has been removed. Fig.16 .

[0504] Fig. 9 , Fig.10 and Fig.19 Except for the outer contour surface and rib groove of the aluminum split male mold 5, the outer contour and positioning dimensions of the lower head 2 and the upper head 8, which have been described as above, the contents not described in detail in the specification of the present invention can adopt the existing technology. For example, the core shaft 1, lower flange 3, core mold 4, male mold 5, upper flange 7 and the installation method and connection method between the components mentioned in the present invention can adopt the existing technology.

[0505] Fig. 20 The positive mold of the silicone rubber rib groove grid is cast, such as Fig.17 Shown bonded to an aluminum backing plate.

[0506] Fig.21 Comparison of the conical surface and the unfolded three types of helices. It can be seen that the differences between the three types of helices with the same endpoints are very small.

[0507] Fig. 22 Schematic diagram of the hybrid triangular mesh structure with equal pitch spiral ribs; Fig.23 Schematic diagram of a hybrid triangular mesh structure with spiral ribs of equal helical angles; Fig.24 The schematic diagram of the mixed triangular mesh structure of geodesic spiral reinforcement. For the convenience of comparison, the coordinates of the two end points of the spiral lines of the three conical segment mesh structures are the same, and the symmetry angles of the spiral reinforcements in both directions are the same. The symmetry angles of the spiral reinforcements in both directions are calculated according to the equal pitch spiral mesh structure, resulting in the ring reinforcements in the equal pitch spiral mesh structure being located in the middle of the structure, while the ring reinforcements in the equal helix angle spiral mesh structure are located in the middle and slightly above the structure, and the ring reinforcements in the geodesic mesh structure are even higher. In engineering applications, the symmetry angles of the equal helix angle spiral mesh structure and the geodesic mesh structure should be appropriately increased so that the middle ring reinforcement is located in the middle of the corresponding structure.

[0508] The structure of the present invention has the advantages of reasonable design, low cost, light weight, etc., and the manufacturing tooling of the structure has the advantages of low manufacturing cost and suitability for automated mass production of the structure, etc.

[0509] (1) The design and forming methods of various conical spiral reinforcement grid structures have been mastered. Conical equal-pitch spiral reinforcements, equal-helix angle spiral reinforcements and short-range spiral reinforcements that are simple and feasible in terms of technology have been compared and designed, and can be selected according to specific engineering conditions.

[0510] (2) The skin is laid and wrapped in one piece, and the densely packed spiral wire laying can realize the automated equal thickness laying of the cone surface, thus avoiding the problem of thickening of the skin at the small end of the cone section structure caused by only automatic winding.

[0511] (3) Taking the expansion amount into account, the geometric parameters of the center line of the spiral rib groove of the male mold of the cone-surface composite material hybrid triangular grid structure forming tool and the corresponding cone surface geometric parameters are corrected to achieve precise forming of the structure so that the geometric dimensions of the structure formed by this forming tool meet the given requirements.

[0512] (4) The bidirectional spiral ribs and annular ribs are automatically wound and formed, with good processability. The ellipsoidal head is designed to achieve automatic continuous winding. The advantages of automatic winding are fully utilized to meet the requirements of mass production. The opposite end of the cone further improves efficiency, reduces costs, and reduces material waste.

[0513] (5) The automatically formed conical composite material hybrid triangular grid structure meets the requirements of productization. The unskinned conical composite material hybrid triangular grid structure is suitable for designing and forming conical segment satellite brackets. The skinned conical composite material hybrid triangular grid structure is suitable for designing and forming interstage structures. The structure has good integrity, strong stability, good forming processability and high production efficiency, thus realizing low-cost, lightweight and rapid forming of composite grid structures.

[0514] (6) Since the bidirectional spiral ribs and annular ribs of the automatically formed conical composite hybrid triangular grid structure are automatically and continuously wound, and the skin is formed by laying and winding in one piece, the composite fiber tow has good continuity, and the strength of the fiber tow in the tensile direction is fully exerted. The composite hybrid triangular grid structure with skin is conducive to bearing internal pressure, especially transient impact internal pressure. The nodes between the automatically wound ribs and between the ribs and the skin can achieve a similar effect to weaving. The automated laying and winding method can enhance the shear resistance of the interface between the grid and the skin.

[0515] (7) The aluminum split male mold is changed to an aluminum pad and a silicone rubber mesh soft mold to further reduce the cost. The conical surface geodesic line is a straight line on the neutral surface of the soft mold, so the processing technology is simplest and the cost is lowest.

[0516] (8) The common technology of the core mold of the soft and hard mold forming tooling of the conical hybrid triangular composite material grid structure, and the common technology of the structure other than the grid bottom plate of the silicone rubber male mold casting mold of the soft mold forming tooling can speed up the development progress and reduce the development cost. The more reused use of the above common technology is: the structure needs to change the interface size according to different requirements, especially the diameter size will change; the use of the above common technology can retain the core mold with the longest production cycle and higher cost, and only change the size of the aluminum pad and silicone rubber grid soft mold that are easy to process to meet the changes in structural design requirements, thereby speeding up the progress, reducing costs, and enhancing the commercial competitiveness of the structure.

[0517] In the description of the present application and its embodiments, it should be understood that the orientation or positional relationship indicated by the terms "top", "bottom", "height", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0518] In the present application and its embodiments, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0519] In the present application and its embodiments, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0520] The disclosure above provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described above. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0521] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0522] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A soft mold forming tool for automatically forming a conical composite material mixed triangular grid structure, characterized in that: It includes upper end frame, lower end frame, bidirectional spiral reinforcement and upper ring reinforcement, middle ring reinforcement and lower ring reinforcement; among which: The outer contour surface of the hybrid triangular mesh structure is a conical surface; The upper end frame, the lower end frame, the bidirectional spiral ribs and the ring ribs are an integrally formed structure, and the ring ribs include upper ring ribs, middle ring ribs and lower ring ribs; The upper frame and the lower frame are both "L" shaped; The bidirectional spiral ribs are symmetrical to each other; the center line of the outer contour surface of the bidirectional spiral ribs includes an equal pitch spiral line, an equal helical angle spiral line and a short distance line; The center line of the outer contour of the ring rib is a circle on the conical surface, the middle ring rib is located in the middle of the mixed triangular grid structure, and the upper ring rib and the lower ring rib are evenly distributed along the direction of the upper end frame and the lower end frame; The cross-sections of the bidirectional spiral reinforcement and the annular reinforcement are all trapezoidal, and the center lines of the annular reinforcement cross-sections are all along the normal line of the cone surface; all the bidirectional spiral reinforcements and annular reinforcements together form a mixed triangular grid structure with triangles and rhombuses alternating; When in a winding state, it comprises a mandrel (1), a lower end cap (2), a lower flange (3), a core mold (4), an aluminum backing plate, a silicone rubber mesh soft mold, a steel sleeve (6), an upper flange (7), an upper end cap (8), a retaining ring (9), a key (10), and a small key (11); In the forming state, it comprises a core mold (4), an aluminum split male mold (5), a steel sleeve (6), an upper pressure ring (12), an outer mold (13), a small hoop (14), a large hoop (15), and a lower pressure ring (16); The center line of the rib groove on the unfolded silicone rubber mesh soft mold for forming the structural bidirectional spiral rib is a plane spiral line or a straight line whose expansion geometric parameters have been corrected; For a truncated cone section with a height of 415 mm, a lower end diameter of φ = 950 mm, and a semi-cone angle of β = 15°, the centerline equation of a spiral rib groove in the bidirectional spiral rib groove of the silicone rubber grid soft mold of the soft mold molding tooling is expanded as follows: 1) The trajectory equation of the soft mold equal pitch conical spiral line when it is unfolded on the neutral surface of the silicone rubber mesh soft mold: 2) The trajectory equation of the helix of the soft mold equal helical angle cone surface when it is unfolded on the neutral surface of the silicone rubber mesh soft mold: Where θ is the angle between the projection of the vector on the XOY plane and the X axis, and k is the ratio of the major axis to the minor axis; 3) The trajectory equation of the short-range line of the soft mold cone surface when it is unfolded on the neutral surface of the silicone rubber mesh soft mold: y=-0.3045x+588.838358.

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