Winding forming process for cone-like pressure-resistant shell and pressure-resistant shell

Abstract

The invention relates to the field of composite material forming, in particular to a winding forming process for a cone-like pressure-resistant shell and the pressure-resistant shell, and the process comprises the following steps: giving the appearance size of a product, including the large-end outer diameter D1, the large-end inner diameter D2, the small-end outer diameter d1, the small-end outer diameter d2 and the axial length L; manufacturing a mold; dividing winding point positions; the winding angle alpha of each winding point position is determined, alpha = arcsin (C / D2), and C is the diameter of the section circle where each winding point position is located; and winding and molding: curing and demolding. The thickness increase of the fibers at each position in the axial direction is reasonably distributed by changing the winding mode, adjusting the layering sequence and the like, the damage to the fiber continuity is reduced as much as possible on the premise of ensuring the appearance curve of the shell, and the compression strength of the shell is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite material forming, more particularly, to a kind of conical pressure shell winding forming process and pressure shell. BACKGROUND

[0002] Fiber wet winding process is a kind of composite material forming technology. It refers to that during fiber winding, continuous fiber bundle (or tape) is first passed through a resin dipping tank, so that it is fully impregnated with liquid resin matrix (usually containing resin, curing agent, etc.), becomes "wet" fiber bundle, then is wound onto a rotating core mold according to a specific trajectory under preset tension control until the required product thickness is reached, and finally is cured by heating or room temperature to form a product, and the core mold is removed to obtain the final composite material product.

[0003] Generally, the forming of general rule cylindrical pressure shell adopts fiber wet winding process, and the longitudinal / circumferential layers are alternately laid according to a certain proportion. However, for conical shell, the outer shape line has a certain curvature, and at the position with large curvature, the circumferential fiber will slide during surface winding forming, and cannot be wound at the given position. Moreover, due to the influence of different curvatures of each point on the outer shape line of the conical shell, the fiber thickness accumulation speed at each position is inconsistent, and the smaller the cross-sectional diameter at the position, the faster the fiber thickness accumulation speed. This situation is particularly obvious for thick-walled shells, which affects the product outer shape size and requires machining to ensure the outer shape curve. However, the continuity of fiber has a great influence on the pressure-bearing performance of the shell, and machining of the outer surface will affect the performance of the fiber, resulting in a significant decrease in pressure-bearing capacity. SUMMARY The present application provides a kind of conical pressure shell winding forming process, which reasonably distributes the thickness increase of fiber at each position in axial direction by changing winding mode and adjusting layer sequence, reduces the damage to fiber continuity as much as possible under the premise of ensuring the outer shape curve of the shell, and improves the pressure-bearing strength of the shell.

[0004] In the first aspect, the present application provides a kind of conical pressure shell winding forming process, which adopts the following technical solution: A kind of conical pressure shell winding forming process, comprising the following steps: Given product outer shape size: including large end outer diameter D1, large end inner diameter D2, small end outer diameter d1, small end outer diameter d2, axial length L; Making mold: determine the mold outer shape surface according to the product inner shape surface, wherein each mold corresponds to two products, the mold is made as left-right symmetrical two parts, and the regions corresponding to the products of the two parts are A1 and A2 respectively, and the large end side of the mold is relatively connected; Divide the winding points: On the A1 and A2 regions of the mold, divide them equally along the axial direction to determine the winding points. The winding points in the A1 region are M1 and M2, and the winding points in the A2 region are N1 and N2. M1 and N1 are symmetrical from left to right, and M2 and N2 are symmetrical from left to right. M1 and M2 are concentric circles, and N1 and N2 are concentric circles. The axial distance between adjacent winding points in each region is set as b. Each circle containing M1 and M2 and the circle containing N1 and N2 encloses a winding area S. Confirm the winding angle: Determine the winding angle α for each winding point, α=arcsin(C / D2), where C is the diameter of the cross-sectional circle where each winding point is located; Winding process: Determine the starting winding area and winding point. According to the winding angle, in each winding area S, start the fiber from the winding point M1, and use the line connecting M1 and N1 and the line connecting M2 and N2 as the fiber turning points, and finally return to the winding point M1; until the fiber covers this winding area S, which is one cycle of this winding area S; the number of cycles in each winding area S is calculated based on the thickness increase of the fiber winding in each cycle and the composite thickness of the winding area S.

[0005] Curing and demolding.

[0006] It should also be noted that M1 and N1, as well as M2 and N2, mentioned in the text do not refer to a specific point, but rather to any point on the circle where the winding point is located. That is, there can be multiple M1 and N1, as well as multiple M2 and N2. Moreover, in order to cover the winding area S, after the previous winding, the next winding is required. The starting point M1 of the next winding is offset from the starting point M1 of the previous winding, so that the fibers wound in the same direction in two adjacent times are adjacent but do not overlap.

[0007] In addition, the process for confirming the winding angle in this application is as follows: the most stable and slip-free winding method is to use geodesic winding, the angle between the yarn sheet and the core mold axis is the winding angle, and the winding angle of each winding point is α.

[0008] Furthermore, in the step of dividing the winding points, the minimum value of the spacing b should not be less than the ply width of the fiber yarn during winding, and the maximum value should not be greater than 6 times the ply width of the fiber yarn during winding.

[0009] Furthermore, in the winding molding step, the thickness increase of the fiber formed by winding the fiber around a cylinder with a diameter of D2 for one cycle is E0. The formula for calculating the thickness increase E of the fiber winding one cycle in the winding zone S is: E / E0=D2 / C. Further still, the total thickness of the composite material in each winding zone of the mold is H, and the increase in composite material thickness in each winding zone due to the winding process of the other winding zones is h. The number of cycles in each winding zone S = (Hh) / E.

[0010] By adopting the above technical solution, due to the curvature change of the cone-shaped shell, during the fiber winding process, along the direction from the large end to the small end, the thickness of the same type of fiber gradually increases during the winding process. Therefore, this application can calculate the thickness of the single-layer fiber at each position, rationally allocate the thickness increase of the fiber at each position in the axial direction, and more accurately control the number of winding cycles and the final thickness of the composite material.

[0011] Furthermore, in the winding molding step, the winding begins from the winding area S formed at the winding point at the large end of the mold and is wound sequentially.

[0012] Furthermore, in the mold-making step, the mold has allowances at the middle connecting end and both the left and right ends. The allowance at the middle connecting end of the mold is a straight section with a winding angle of 90°. Here, the straight section refers to the cylindrical position at the mold connecting end.

[0013] Furthermore, the curing and demolding step employs multi-stage curing.

[0014] Secondly, this application provides a pressure-resistant shell prepared by the above-mentioned conical pressure-resistant shell winding molding process, using the following technical solution: In summary, this application has the following beneficial effects: 1. This method can rationally distribute the increase in fiber thickness at various axial positions when winding a conical pressure-resistant shell. Under the premise of ensuring the outer curve of the shell, it can minimize the damage to the fiber continuity and improve the pressure resistance of the shell.

[0015] 2. The shell forming process uses symmetrical mold winding, which can complete the winding and forming of two shells at the same time, greatly improving production efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the shell shape in an embodiment of this application.

[0017] Figure 2 This is a schematic diagram of the mold shape in an embodiment of this application. Figure 3 This is a schematic diagram of the winding points of the mold in the embodiments of this application.

[0018] Figure 4 This is a schematic diagram of the fiber orientation during the winding process in an embodiment of this application.

[0019] Explanation of reference numerals in the attached drawings: 1. Shell; 2. Mold; 3. Straight section. Detailed Implementation

[0020] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] Example In this embodiment, the reinforcing material used is Toray T700SC-12K from Japan, with a linear density of 800 tex and a bulk density of 1.8 g / cm3; the number of yarn balls is 6, the yarn spreading width (ply width) during winding is 18 mm, and the resin matrix is ​​a medium-temperature curing epoxy system, specifically E51 epoxy resin system with a mass content of 30%.

[0022] This embodiment provides a winding molding process for a cone-shaped pressure-resistant shell, including the following steps: (1) Given the product's external dimensions: including the outer diameter of the large end D1, the inner diameter of the large end D2, the outer diameter of the small end d1, the outer diameter of the small end d2, and the axial length L; In this embodiment, as Figure 1 As shown, in this embodiment, the outer diameter of the large end of the housing 1 is D1=540mm, the inner diameter of the large end is D2=460mm, the outer diameter of the small end is d1=235.56mm, the inner diameter of the small end is d2=200mm, and the axial length is L=610mm.

[0023] (2) Mold making: Determine the outer surface of the mold according to the inner surface of the product. Each mold corresponds to two products. Make the mold into two symmetrical parts, with the areas of the two parts corresponding to the products being A1 and A2 respectively. The large end of the mold is connected to each other.

[0024] Mold 2 shape as Figure 2 As shown, a metal mold or a soluble mold can be selected according to the actual situation. A 50mm allowance is reserved at the middle connection position, and the middle allowance section is a straight cylinder, i.e., straight section 3. A 10mm allowance is reserved at each of the left and right ends for cutting and processing.

[0025] (3) Divide the winding points: On the A1 and A2 regions of the mold, divide them equally along the axial direction to determine the winding points. The winding points in the A1 region are M1 and M2, and the winding points in the A2 region are N1 and N2. M1 and N1 are symmetrical from left to right, M2 and N2 are symmetrical from left to right, M1 and M2 are concentric circles, and N1 and N2 are concentric circles. The axial distance between adjacent winding points in each region is set as b. Each group of circles containing M1 and M2 and N1 and N2 forms a winding area S. like Figure 3 As shown, in this embodiment, the left and right sides of mold 2 are equally divided into 6 regions. The left side is region A1, with winding points M61 and M62, M51 and M52, M41 and M42, M31 and M32, M21 and M22, and M11 and M12. The right side is region A2, with winding points N61 and N62, N51 and N52, N41 and N42, N31 and N32, N21 and N22, and N11 and N12.

[0026] The spacing b satisfies the following conditions: its minimum value should be greater than the ply width of the fiber yarn during winding, and its maximum value should not exceed 6 times the ply width of the fiber yarn during winding. In this embodiment, the spacing b is 100mm.

[0027] (4) Confirm the winding angle: Determine the winding angle α for each winding point, α=arcsin(C / D2), where C is the diameter of the cross-sectional circle where each winding point is located; according to the calculation, in this embodiment, the winding angle corresponding to each winding point in regions A1 and A2, starting from the large end, is shown in Table 1. Among them, the winding angle of the straight section 3 is 90°, and its winding point is located at the position where the curvature of the mold begins to change along the axial direction, that is, the winding area is a cylindrical area.

[0028] (5) Winding and curing demolding: Determine the starting winding area and winding point. According to the winding angle, in each winding area S, start the fiber from the winding point M1, and use the line connecting M1 and N1 and the line connecting M2 and N2 as the fiber turning points, and finally return to the winding point M1; until the fiber covers this winding area S, which is one cycle of this winding area S.

[0029] Specifically, such as Figure 4 As shown, taking the two circles containing M61 and N61 and M62 and N62 on mold 2 to form the winding area S6 as an example, first, according to the green mark, the fiber starts from the winding point M61, and takes the line connecting M61 and N61 and the line connecting M62 and N62 as the fiber turning point, and the winding fiber eventually returns to the winding point M61; until the fiber covers this winding area S6, this is one cycle of the winding area S.

[0030] Furthermore, the number of cycles in each winding zone S is calculated based on the thickness increase of each fiber winding cycle and the composite material thickness of the winding zone S. Specifically, the thickness increase of the fiber formed by winding one cycle on a cylinder with a diameter of D2 is E0, that is, the thickness increase of two layers of fiber is E0. The formula for calculating the thickness increase E of the fiber winding one cycle in the winding zone S is: E / E0=D2 / C. The total composite material thickness of each winding zone of the mold is H, and the composite material thickness increase of each winding zone due to the winding process of the other winding zones is h. The number of cycles in each winding zone S = (Hh) / E.

[0031] In this embodiment, the fiber layers at various angles are arranged alternately with winding angles ranging from 75° to 26° for winding lay-up, that is, winding lay-up starts from the large end.

[0032] For the reinforcing material in this embodiment, the thickness of a single fiber layer is 0.25 mm, and E0 is 0.5 mm. The parameters for other locations are shown in Table 1.

[0033] Table 1. Parameters at various locations of the mold In this embodiment, due to the thickness of the composite material, the curing and demolding process is carried out in three stages: the first two stages are pre-curing, and the third stage is final curing, as detailed below: The first and second stage layups are detailed in Table 2: Table 2 Layup Parameters for Stage 1 and Stage 2 In both the first and second stages, the layers are alternately arranged at various angles and wound according to the above layup sequence. At this point, calculated based on the center position of the mold, the thickness of the first and second stages increases by 13mm each, approximately 1 / 3 of the total thickness. A pre-curing process is performed between the first and second stages, with a curing regime of 95℃ for 6 hours.

[0034] The third stage of layup is detailed in Table 3: Table 3. Layup Parameters for the Third Stage Following the above layup sequence, the layers are alternately arranged and wound. At this point, calculated from the center of the mold, the third stage thickness increases by 14.5mm, approximately 1 / 3 of the total thickness. Final curing is then performed in the third stage, with a curing regime of 95℃ for 6 hours, 125℃ for 2 hours, and 150℃ for 6 hours.

[0035] After completion, the product undergoes processes such as lathe cutting of the middle and both ends, demolding, milling of the shape, and post-processing to obtain the final product.

[0036] Comparative Example The similarities between this comparative example and the embodiment will not be repeated here; only the differences will be described. The difference between this comparative example and the embodiment is that the winding process uses a single winding angle of 26° for winding and forming. After each winding and curing, the product's outer contour lines will deviate due to inconsistent thickness at various locations. In this case, milling is used to process the outer contour surface to ensure the product's shape. The remaining processes are the same as in the embodiment, corresponding to the production of the pressure-resistant shell.

[0037] Performance testing External water pressure test was conducted on the pressure-resistant shell products obtained in the embodiments and comparative examples. The pressure-resistant shell provided in this embodiment passed the external water pressure test of 30MPa, and no obvious defects were found in the ultrasonic test after the test. The pressure-resistant shell of the comparative example was subjected to the same test as in the embodiment and burst at 19.8MPa.

[0038] Therefore, this application rationally distributes the increase in fiber thickness at various axial positions by changing the winding method and adjusting the layup sequence, thereby minimizing damage to fiber continuity and improving the pressure resistance of the shell while ensuring the outer curve of the shell.

[0039] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A conical-type pressure-resistant shell winding forming process, characterized in that, The method comprises the following steps: Given product outer dimensions: including large end outer diameter D1, large end inner diameter D2, small end outer diameter d1, small end outer diameter d2, axial length L; Making a mold: determine the mold outer shape surface according to the product inner shape surface, wherein each mold corresponds to two products, the mold is made into two symmetrical parts, the two parts correspond to the product areas A1 and A2, and the large end side of the mold is relatively connected; Dividing winding points: divide the A1 and A2 areas of the mold equidistantly in the axial direction to determine the winding points, the winding points of the A1 area are M1 and M2, and the winding points of the A2 area are N1 and N2, wherein M1 and N1 are left-right symmetrical, M2 and N2 are left-right symmetrical, M1 and M2 are concentric, N1 and N2 are concentric, the axial distance between adjacent winding points in each area is b, and each group of M1 and M2 and N1 and N2 forms a winding area S; Confirming the winding angle: determine the winding angle α of each winding point, α = arcsin(C / D2), wherein C is the diameter of the cross-sectional circle of each winding point; Winding forming: determine the starting winding area and winding point of winding, and according to the winding angle, in each winding area S, the fiber is wound from the winding point M1, the connecting line between M1 and N1 and the connecting line between M2 and N2 are used as the fiber turning points, and finally returns to the winding point M1; until the fiber covers this winding area S, that is, one cycle of this winding area S; the number of cycles of each winding area S is calculated according to the thickening thickness of the fiber winding each cycle and the composite thickness of the winding area S. Curing and demolding.

2. A kind of conical pressure shell winding forming process, according to claim 1, characterized in that, In the step of dividing winding points, the minimum value of the interval b should be not less than the ply width of the fiber yarn during winding, and the maximum value should be not more than 6 times the ply width of the fiber yarn during winding.

3. A kind of conical pressure shell winding forming process, according to claim 1, characterized by, In the winding forming step, the thickening thickness of the fiber winding one cycle on the cylinder with a diameter of D2 is E0, and the calculation formula of the thickening thickness E of the fiber winding one cycle in the winding area S is: E / E0=D2 / C.

4. A kind of conical pressure shell winding forming process according to claim 3, characterized by, The total thickness of the composite of each winding area of the mold is H, and the composite thickness of each winding area due to the winding process of the remaining winding areas is h, and the number of cycles of each winding area S is (H-h) / E.

5. A kind of conical pressure shell winding forming process, according to claim 1, characterized by, In the winding forming step, the winding area S formed from the winding point at the large end of the mold is sequentially wound.

6. A kind of conical pressure shell winding forming process, according to claim 1, characterized by, In the step of making a mold, the middle connecting end and the left and right ends of the mold are provided with a margin.

7. A kind of conical pressure shell winding forming process according to claim 6, characterized in that, The margin of the middle connecting end of the mold is a flat section, and the winding angle is 90°.

8. A kind of conical pressure shell winding forming process, according to claim 1, characterized by, In the step of curing and demolding, curing is performed in multiple times.

9. A pressure shell prepared by the conical type pressure shell winding forming process according to any one of claims 1-8.

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