A method for stitching a prefabricated body

Abstract

The present invention belongs to the field of fiber preforms for composite materials, and specifically relates to a method for suturing and forming a preform. It includes the following steps: Step (1): Suturing track design: the suturing track is designed according to the shape of the preform; the suturing track is in the shape of a "fish skeleton" as a whole, and the "fish skeleton" includes a main bone and bone spurs. The main bone is in a cross shape, with the longest side passing through the center point of the open end of the preform as one side of the cross-shaped main bone, and the other side of the main bone passes through the center point and is perpendicular to the longest side; the main bones are sutured in the form of bone spurs; Step (2): Suturing: the preform is placed in a dimensional mold and reinforced by a suturing process. The present invention innovatively adopts a "fish skeleton" type suturing method, so that deformation is not easy to occur during suturing, and the preform surface accuracy is high; and according to the shape of the product, the position and number of fish bones and bone spurs are reasonably designed, so that the suture line track is regular and the suture spacing is highly uniform.

Description

Technical Field

[0001] The invention belongs to the field of composite material preforms, and in particular relates to a preform stitching molding method. Background Art

[0002] The needle-punched preform overcomes the shortcomings of the weak interlayer strength of the 2D laminated preform and the complex process and high cost of the 3D woven preform, and has the characteristics of uniform pore distribution, good densification and high in-plane performance. However, since the interlayers are connected by short fibers, they are easy to delaminate in harsh service environments and need to be reinforced through the stitching process.

[0003] At present, the use of stitching technology to prepare preforms has been seen in many documents, such as Chinese patent

[0004] 201210452764.5 A method for forming a single-sided stitching line of a three-dimensional composite material preform, Chinese patent 202010242891.7 A method for stitching a composite material, etc. Some patents also mention needle punching stitching reinforcement, but the existing technology is only applicable to products of certain thickness and no patent mentions the design method of the trajectory line and stitching path. Summary of the invention

[0005] The object of the present invention is to provide a method for stitching and forming a preform.

[0006] The technical solution to achieve the purpose of the present invention is: a method for stitching a preform, comprising the following steps:

[0007] Step (1): Suture track design: design the suture track according to the shape of the preform;

[0008] The suture track is in the shape of a "fish skeleton". The "fish skeleton" includes the main bone and bone spurs. The main bone is in a cross shape, with the longest side of the open end of the preform passing through the center point as one side of the cross-shaped main bone, and the other side of the main bone passing through the center point and perpendicular to the longest side; the main bones are sutured in the form of bone spurs;

[0009] Step (2): Stitching: The preform is placed in a stitching female mold and reinforced by stitching technology.

[0010] Furthermore, step (1) specifically includes the following steps:

[0011] Step (11): determine the position and number of rows of the main bones;

[0012] Step (12): determining the location and number of rows of bone spurs;

[0013] Step (13): Determine the suturing order.

[0014] Furthermore, step (11) is specifically as follows: the two sides of the long side of the main bone are A and B, and the two sides of the short side are C and D;

[0015] The number of main bone rows is determined by the suture spacing c of the long side a and the short side b: A=B=[b / c], C=D=[a / c]. If a=b, then A=B=C=D=[a / c].

[0016] Furthermore, step (12) is specifically as follows: the number of rows of bone spurs [l / c-2([a / c]+[b / c])] is determined according to the circumference l of the open end of the preform and the suture spacing, and the bone spurs are arranged in sequence parallel to a group of main bones.

[0017] Further, step (13) is specifically as follows: the suturing order is symmetrically from the main skeleton A, B to the main skeleton C, D to the bone spur;

[0018] The bone spur is removed from C to AB, and then from D to AB.

[0019] Furthermore, the profile of the sewing female mold used in step (2) is processed based on the outer profile of the preform.

[0020] Furthermore, the stitching process in step (2) adopts a stitching process of variable depth stitching and variable spacing stitching, the stitching spacing is 2 to 30 mm, and the stitching depth is ≤ the preform thickness.

[0021] Furthermore, the variable depth stitching is specifically as follows: the stitching spacing is d, the preform thickness is b, the inner length is l1, and the outer length is l2. Then, there are l1 / d and l2 / d stitching points on the inner and outer sides respectively, wherein the stitching depth of the l1 / d stitching points is b, (l2 / d-l1 / d) stitching points are evenly distributed between the l1 / d stitching points, and the number of stitching points between two adjacent l1 / d stitching points is c. i (≥1), the suture depths are: b / (c+1), 2b / (c+1), 3b / (c+1)…

[0022] Furthermore, the variable spacing stitching is specifically as follows: let the number of stitching points per unit area be c, the unit area be s, and the stitching spacing be d, then c = s / d 2 If the local anti-delamination ability requirement is high, the number of suture points will be large and the suture spacing will be small.

[0023] Furthermore, in step (2), before suturing, the robot is programmed off-line, and a metal needle is carried by the robot to perform positioning and preset suturing holes, and then suturing is performed using the suturing needle with fiber.

[0024] Furthermore, the suturing method in the suturing process in step (2) is lock stitching or temporary stitching.

[0025] Furthermore, the number of suture fiber strands in step (2) is N, where N is greater than or equal to 1.

[0026] Furthermore, the raw material of the suture fiber in step (2) is carbon fiber, quartz fiber, basalt fiber, aramid fiber, polyimide fiber or alumina fiber.

[0027] Furthermore, the shape of the open end of the preform is circular, elliptical or polygonal.

[0028] An application of the above method is used for the suture reinforcement of acupuncture, 2.5D, orthogonal three-dimensional, three-dimensional woven structures or the suture reinforcement of any combination of the above structures.

[0029] Compared with the prior art, the present invention has the following significant advantages:

[0030] (1) The preform sewing method prepared by the present invention innovatively adopts a "fish skeleton" sewing method, which makes it difficult to deform during sewing and the preform surface precision is high;

[0031] (2) The present invention proposes a design method for the position and number of fishbones and bone spurs according to the specific product shape, so that the suture line trajectory is regular and the suture spacing is highly uniform;

[0032] (3) The suture yarn is not easy to wear, has a high strength retention rate, and has excellent mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the main skeleton of Example 1.

[0034] Figure 2 Schematic diagram of suture trajectory in Example 1; (a) is a schematic diagram of the two sides of the main bone, and (b) is a schematic diagram between the main bones.

[0035] Figure 3 This is a schematic diagram of the main skeleton of Example 2.

[0036] Figure 4 Schematic diagram of suture trajectory in Example 2; (a) is a schematic diagram between the main bones, and (b) is a schematic diagram on both sides of the main bones. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0038] Example 1

[0039] A quartz fiber needle-punched end-sealed rotating body is sutured and reinforced. The open end of the preform is an elliptical shape, wherein the major axis is 300 mm long, the minor axis is 200 mm long, the outer diameter at the top is 50 mm long, the minor axis is 30 mm long, the thickness is 20 mm, the total length of the preform is 600 mm, and the volume density of the preform is 0.80 g / cm 3 The suture spacing is (7.0±0.5) mm×(7.0±0.5) mm, the suture yarn is quartz fiber 190tex, and the Z-direction fiber is 2 strands. The preparation process is as follows:

[0040] 1) Suture track design. The number of rows of the main bones of the "fish skeleton" is respectively the main bones on the left and right: A = B = [30 / 7] = 4, and the number of rows of the upper and lower main bones C = D = [50 / 7] = 7. The number of rows of "fish bones" in the "fish skeleton" is [828 / 7-2(7+4)] = 96 rows, and the suture track design diagram is as follows Figure 1-2 As shown;

[0041] 2) Place the preform in the suture female mold, sew the main bones A and B first, then sew the main bones C and D, and finally sew the bone spurs to A and B in sequence with C as the center, and sew to A and B in sequence with D as the center. When suturing, use a 0.9mm needle to expand the hole and a 0.6mm diameter needle for suturing. When suturing, follow the "fish skeleton" suture path, use lock suture and temporary suture alternately, and the temporary suture depth is 10mm.

[0042] Example 2

[0043] A quartz fiber needle-punched end-sealed preform is sutured and reinforced. The outer surface of the open end of the preform is a rhombus, the diagonal length of the rhombus is 400 mm, the short axis length is 300 mm, the top is a hemispherical shape with a diameter of 50 mm, a thickness of 15 mm, a total length of 300 mm, and a volume density of 0.85 g / cm 3 The suture spacing is (10.0±0.5) mm×(10.0±0.5) mm, the suture yarn is quartz fiber 85tex, and the Z-direction fiber is 2 strands. The preparation process is as follows:

[0044] 1) Suture track design. The number of rows of the main bones of the "fish skeleton" is the main bones on the left and right: A = B = [50 / 10] = 5, and the number of rows of the upper and lower main bones is C = D = [50 / 10] = 5. The number of rows of "fish bones" in the "fish skeleton" is [1000 / 10-2(5+5)] = 80 rows. The suture track design diagram is as follows Figure 3-4 As shown;

[0045] 2) Place the preform in the suture female mold, sew the main bones A and B first, then sew the main bones C and D, and finally sew the bone spurs with C as the center to A and B in sequence, and sew with D as the center to A and B in sequence. When suturing, use a 0.6mm needle to expand the hole and a 0.5mm diameter needle for suturing. When suturing, follow the "fish skeleton" suture path, use lock suture and temporary suture alternately with one stitch every two stitches, and the temporary suture depths are 7.5mm and 5.0mm respectively.

Claims

1. A method for stitching a preform, characterized in that: The steps include: Step (1): Suture track design: design the suture track according to the shape of the preform; The overall suture track is in the shape of a "fish skeleton", which includes the main bone and bone spurs. The main bone is in a cross shape, with the longest side of the open end of the preform passing through the center point as one side of the cross-shaped main bone, and the other side of the main bone passing through the center point and perpendicular to the longest side; the main bones are sutured in the form of bone spurs; Step (2): Stitching: placing the preform in a stitching female mold and reinforcing it by stitching technology; Step (1) specifically includes the following steps: Step (11): determine the position and number of rows of the main bones; Step (12): determining the location and number of rows of bone spurs; Step (13): determine the suturing order; Step (11) is specifically as follows: the two sides of the long side of the main bone are A and B, and the two sides of the short side are C and D; The number of main bone rows is determined by the suture spacing c of the long side a and the short side b, A=B=[b / c], C=D=[a / c]. If a=b, then A=B=C=D=[a / c]; Step (12) specifically comprises: determining the number of rows of bone spurs [1 / c-2([a / c]+[b / c])] according to the perimeter l of the open end of the preform and the suture spacing, and the bone spurs are arranged in sequence parallel to a group of main bones; Step (13) is specifically as follows: the suturing order is symmetrical from the main skeleton A, B to the main skeleton C, D to the bone spur; The bone spur is removed from C to AB, and then from D to AB.

2. The method for sewing and forming a preform according to claim 1, characterized in that: The profile of the sewing female mold used in step (2) is processed based on the outer profile of the preform.

3. The method for sewing and forming a preform according to claim 1, characterized in that: The stitching process in step (2) adopts a stitching process of variable depth stitching and variable spacing stitching, the stitching spacing is 2 to 30 mm, and the stitching depth is ≤ the preform thickness.

4. The method for sewing and forming a preform according to claim 3, characterized in that: The specific variable depth stitching is: the stitching spacing is d, the preform thickness is b, the inner length is l1, and the outer length is l2. There are l1 / d and l2 / d stitching points on the inner and outer sides respectively, among which the stitching depth of l1 / d stitching points is b, (l2 / d-l1 / d) stitching points are evenly distributed between l1 / d stitching points, and the number of stitching points between two adjacent l1 / d stitching points is c i (≥1), the suture depths are: b / (c+1), 2b / (c+1), 3b / (c+1)… 5. The method for sewing and forming a preform according to claim 4, characterized in that: The specific method of variable spacing stitching is: let the number of stitching points per unit area be c, the unit area be s, and the stitching spacing be d, then c = s / d 2 If the local anti-delamination ability requirement is high, the number of suture points will be large and the suture spacing will be small.

6. The method for sewing and forming a preform according to claim 5, characterized in that: Step (2) Before suturing, the robot is programmed offline, and a metal needle is carried by the robot to perform positioning and preset suturing holes, and then suturing is performed using the suturing needle with fiber.

7. The method for sewing and forming a preform according to claim 6, characterized in that: The suturing method in the suturing process in step (2) is lock stitching or temporary stitching.

8. The method for sewing and forming a preform according to claim 7, characterized in that: The number of suture fiber strands in step (2) is N, where N is greater than or equal to 1.

9. The method for sewing and forming a preform according to claim 8, characterized in that: The raw material of the suture fiber in step (2) is carbon fiber, quartz fiber, basalt fiber, aramid fiber, polyimide fiber or alumina fiber.

10. The method for sewing and forming a preform according to claim 1, characterized in that: The shape of the open end of the preform is circular, elliptical or polygonal.

11. Use of the method for stitching a preform according to any one of claims 1 to 10, characterized in that: Used for stitching reinforcement of needle punched, 2.5D, orthogonal three-way, three-dimensional woven structures or any combination of the above structures.

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