A forming process for large size composite tubular beams

Abstract

The application discloses a forming process of a large-size composite pipe beam; S1, a plurality of foam core molds with the same diameter are spliced to form a long foam core mold A; S2, the surface of the foam core mold A is cleaned, and then inner inflation bags and tear-off layers are sequentially laid; S3, prepregs are laid on the tear-off layers to form a preform, and the tear-off layers are continuously laid on the preform; meanwhile, the prepregs are laid in a lap joint mode and lap joints are formed; S4, the foam core mold A is placed in a lower forming mold, and the lap joints are ensured to be staggered with the joint seam positions of the lower forming mold and an upper forming mold; the upper forming mold and the lower forming mold are closed, and a gas guide channel is arranged at the joint seam; S5, after the closing, a vacuum bag is sleeved outside the lower forming mold and the upper forming mold, pressure is added by means of the combination of the inner inflation bags and the vacuum bag, meanwhile, the mold is placed in an oven for heating, and after temperature rising, pulse pressure is added; S6, after curing, demolding is carried out, appearance quality and internal quality inspection are carried out, and the large-size composite pipe beam is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite material manufacturing, in particular to a forming process of large-size composite material pipe beam. BACKGROUND

[0002] Generally, the composite material pipe is particularly suitable for manufacturing by using mature automatic methods such as pipe winding, winding, pultrusion and the like. However, for some large-size variable diameter pipes, the pultrusion, winding and pipe winding forming processes are not suitable, one is that the composite material pipe cannot be smoothly demolded, two is that for research projects, the one-time investment cost and research and development cost of automatic equipment are high, three is that for pipes with high appearance requirements, internal and external diameter size requirements and internal quality requirements, such as large unmanned aerial vehicle main load-bearing pipe beam, the existing forming process cannot meet the design requirements. SUMMARY

[0003] The purpose of the present application is to propose a forming process of large-size composite material pipe beam in view of the fact that the existing process cannot meet the manufacturing requirements of large-size composite material pipe, the process of the present application can not only meet the manufacturing of large-size composite material pipe, but also guarantee the control of the appearance and internal quality of the manufactured pipe.

[0004] The present application is realized by the following technical scheme:

[0005] A forming process of large-size composite material pipe beam, characterized in that the process comprises the following steps:

[0006] S1, core mold making: splice several foam core molds with the same diameter to form a foam core mold A with a specified length;

[0007] S2, laying a tear layer: clean the surface of the foam core mold A, then lay an inner expansion bag on the surface of the foam core mold A, and then lay a tear layer;

[0008] S3, pre-impregnated material laying: lay composite pre-impregnated material on the tear layer to form a preform, and continue to lay the tear layer on the preform after the pre-impregnated material is completely laid; at the same time, ensure that the several pre-impregnated materials are laid in a lap joint manner and form a lap joint seam;

[0009] S4, mold closing: place the foam core mold A with laid composite pre-impregnated material in a forming lower mold, and ensure that the lap joint seam is staggered with the mold closing seam position of the forming upper mold and the forming lower mold; then close the forming upper mold and the forming lower mold, and set a gas guide channel at the mold closing seam;

[0010] S5, curing: after clamping, a vacuum bag is sleeved outside the molding lower mold and the molding upper mold, pressure is applied by combining the inner inflation bag with the vacuum bag, and meanwhile the mold is placed in an oven for heating, pulse pressure is applied after the mold temperature rises to a certain temperature, and the above heating and pressurizing mode is repeated for curing;

[0011] S6, after the curing is completed, demolding is performed, and appearance quality and internal quality inspection is performed to obtain a large-size composite pipe beam.

[0012] Specifically, the length of the composite pipe beam to be manufactured is relatively long, which exceeds the length of the foam core mold, so a plurality of foam core molds need to be spliced to form a composite length (i.e., a spliced foam core mold A), before splicing the foam core mold, the end face of each foam core mold is assembled, and the large joint area needs to be cut flat before splicing. The foam core mold is spliced by hot melt glue, the hot melt glue is melted by a hot air gun, and is quickly scraped evenly on the cross section of the foam core mold. The total length tolerance of the spliced foam is +5mm to +15mm.

[0013] The large-size composite forming process control method of the application not only solves the problems of surface fiber wrinkles, internal pore layering and difficult demolding of the circular pipe beam, but also has simple equipment, lower manufacturing cost compared with the autoclave, and the shape size precision and internal porosity quality of the autoclave process parts, completely meets the lossless A-level requirement, and is suitable for circular pipe forming with a diameter of 10mm or more and unlimited length.

[0014] Further, a large-size composite pipe beam forming process: in step S1, the foam core mold is spliced by hot melt glue.

[0015] Further, a large-size composite pipe beam forming process: the straightness of the spliced foam core mold A (1) in step S1 is ≤2mm / 1m.

[0016] Further, a large-size composite pipe beam forming process: the circumference of the foam core mold A (1) is controlled, and the circumference calculation formula is C=(Φ-t*2)*π*Δ; in the formula, C is the circumference, Φ is the part outer diameter, t is the part thickness, and Δ is the scaling factor of the foam core mold, and the scaling factor is 0.9-1.05.

[0017] Further, a large-size composite pipe beam forming process: the number of layers of the tear layer is 1-3 layers.

[0018] Further, a large-size composite pipe beam forming process: in step S3, the circumference of the preform is measured after 3-5 layers of prepreg are laid, and the circumference tolerance of the preform is controlled to be-10% to 0; and the width of the splicing joint is 1-10mm.

[0019] Specifically, the circumference of the preform after laying 3-5 layers of composite material prepreg is controlled within a tolerance range: the prepreg is laid on the foam core mold to ensure that the fibers do not wrinkle, and the circumference of the preform is measured after laying 3-5 layers, and the circumference tolerance of the preform is controlled within -10% to 0.

[0020] Further, a forming process of a large-size composite material pipe beam: the lap joint in step S4 is staggered by at least 20mm from the upper and lower positions of the mold joint.

[0021] Specifically, the position of the lap joint of the fixed prepreg layer is staggered by at least 20mm from the upper and lower positions of the mold joint, which is used to ensure that the position of the mold joint does not wrinkle during the mold closing process.

[0022] Further, a forming process of a large-size composite material pipe beam: in step S4, a tear layer is laid at the mold joint, the mold joint has a certain gap by using the tear layer to form an air guide channel, and the width of the gap is 0.2-0.5mm.

[0023] Specifically, the air guide channel provided at the mold joint of the present application can assist in the discharge of gas during the curing process, and can further ensure the internal quality of the product.

[0024] Further, a forming process of a large-size composite material pipe beam: in step S5, the inner inflation bag is inflated to generate an inner inflation pressure, and the inner inflation pressure is 1-20 atmospheres; and the mold temperature is raised to 70-90℃ for pulse pressure.

[0025] Preferably, during the curing and forming process, the inner inflation pressure ranges from 1 to 20 atmospheres, and pulse pressure is adopted when the viscosity of the composite material prepreg is the lowest, and the cycle number is at least 2 times, to exclude the gas in the system and ensure the internal quality. The method of combining the inner inflation bag with the outer vacuum bag in the present application can provide stable pressure and gas discharge channels during the curing process.

[0026] The beneficial effects of the present application are:

[0027] (1) The process steps of the present application are simple, and the forming process of the present application can obtain a large-size composite material pipe beam with excellent apparent quality and A-level internal quality.

[0028] (2) The oven inner inflation bag negative mold forming process of the present application not only solves the problems of apparent fiber wrinkles, internal porosity layering and difficult demolding of the circular pipe beam, but also has simple equipment required by the forming method of the present application, and the manufacturing cost is lower than that of the autoclave. At the same time, the forming method of the present application has the shape size precision and internal porosity quality of the autoclave process parts, completely meets the lossless A-level requirements, and is suitable for forming large-size composite material circular pipes with a diameter of 10mm or more and unlimited length.

[0029] (3) The process of the present application can avoid the wrinkle of the composite material fiber and affect the apparent quality by controlling the circumference of the foam core mold and controlling the actual circumference to be less than the theoretical outer circumference after laying the prepreg, and the prepreg is directly laid on the foam core mold, the laying efficiency is obviously improved, the mold occupation time is reduced, multiple processes can be parallel, and the forming efficiency is obviously improved.

[0030] (4) The forming process of the present application increases the air guide channel and optimizes the process parameters, solves the internal porosity and delamination problem of the pipe beam, greatly improves the product qualification rate, and significantly reduces the cost.

[0031] (5) The composite parts produced by the method of the present application have many apparent quality and internal quality problems, after using the forming process of the present application, the apparent quality and internal quality problems of the parts are completely solved, and the qualification rate is improved to 100%. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 The forming process flow chart of the present application embodiment 1;

[0034] Figure 2 The installation schematic diagram of the foam core mold on the lower mold of the present application;

[0035] Figure 3 The schematic diagram of the composite prepreg lap joint;

[0036] Figure 4 The schematic diagram of the tear layer and the preform position laid on the foam core mold A;

[0037] Figure 5 The setting position schematic diagram of the air guide channel after the lower mold and the upper mold of the present application are combined.

[0038] Marked in the figure: 1 foam core mold A, 2 tear layer, 3 preform, 4 lap joint, 5 lower mold, 6 upper mold, 7 combined mold seam, 8 air guide channel, 1-1 foam core mold. DETAILED DESCRIPTION

[0039] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The description of the at least one example embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0040] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc. indicate the orientation or positional relationship, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more features. Moreover, the terms "first", "second" and the like are used to distinguish similar objects, and do not necessarily be used to describe a particular order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0041] Embodiment 1

[0042] A forming process of a large-size composite pipe beam, the length of the formed large-size composite pipe beam is about 14 meters, and the specific forming process comprises the following steps:

[0043] S1, core mold making: 7 pieces of foam core mold 1-1 with a length of about 2 meters and the same diameter are spliced by hot melt glue to form a longer foam core mold A1 (as shown in Figure 2 Before splicing the foam core mold 1-1, the end face of each foam core mold 1-1 is pre-assembled, the large joint area is cut flat, and then spliced, the foam core mold 1-1 is spliced by hot melt glue, the hot melt glue is melted by a hot air gun, and is quickly scraped evenly on the cross section of the foam core mold 1-1, the total length of the spliced foam core mold A1 is about: 14015mm, and the straightness is ≤2mm / 1m;

[0044] S2, laying the tear-off layer: the surface of the foam core mold A1 is cleaned, and then an inner expansion bag is laid on the surface of the foam core mold A1, and then 2 layers of tear-off layer 2 are laid;

[0045] S3, prepreg laying: lay composite prepreg on the tear layer 2 to form a preform 3 (a total of 16 layers of prepreg are laid), and continue to lay the tear layer 2 on the preform 3 after the laying of the prepreg is completed; ensure that the prepreg is laid in an overlapping manner and forms an overlap joint 4 when the composite prepreg is laid, and the width of the overlap joint 4 of the first to third layers of prepreg in this embodiment 1 is about 10 mm, the width of the overlap joint of the fourth to fifteenth layers is about 1 mm, and the width of the overlap joint of the sixteenth layer is about 5 mm; measure the circumference of the preform 3 after laying 3-5 layers of prepreg in this step S3, and control the tolerance of the circumference of the preform 3 to be -10%~0; as shown in Figure 3 、 Figure 4

[0046] S4, mold closing: place the foam core mold A1 on which the composite prepreg is laid into the lower mold 5, and ensure that the overlap joint 4 is staggered by about 85 mm from the upper and lower positions of the mold joint 7 of the upper mold 6 and the lower mold 5, and is not near the mold joint position (here, the overlap joint 4 and the mold joint 7 are staggered by a distance d, as shown in Figure 3 ); then close the upper mold 6 and the lower mold 5, and continue to lay the tear layer material at the mold joint 7, so that the mold joint (between the upper mold 6 and the lower mold 5) has a certain gap (the width of the gap is 0.3 mm) by using the tear layer, and the tear layer is connected with the air-permeable felt in the outer bag as an air guide channel 8; as shown in Figure 3 、 Figure 5

[0047] S5, curing: after the mold is closed, a vacuum bag is provided outside the lower mold 5 and the upper mold 6, and then the inner bag is inflated (about 8 atmospheres), the vacuum bag is vacuumed, and the inner bag is combined with the vacuum bag to pressurize, and at the same time, the mold is placed in an oven for heating, and after the temperature of the mold rises to about 75℃, pulse pressure is applied; the above heating and pressurizing method is repeated twice for curing and forming;

[0048] S6, after the curing is completed, the mold is demolded, and the apparent quality and internal quality are inspected to obtain a large-size composite pipe beam; the inner and outer surfaces of the obtained product are free of fiber wrinkles, resin-rich and resin-poor apparent quality, and the internal part is free of porosity and delamination problems, which completely meets the delivery requirements.

[0049] The pulse pressure in the above embodiment 1 is shown in the following table:

[0050] Cycle number Starting temperature Pressure First cycle 75℃ Depressurisation (1 bar) -> pressurisation (7 bar) Second cycle 85℃ Depressurisation (1 bar) -> pressurisation (7 bar) Fourth cycle 91℃ Depressurisation (1 bar) -> pressurisation (7 bar) Fifth cycle 96℃ Depressurisation (1 bar) -> pressurisation (7 bar)

[0051] The molding process flow of the above embodiment 1 is shown in Figure 1 .

[0052] ​​The above are only used for explaining the present application, and are not intended to limit the present application. Any obvious changes or modifications derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A forming process for large size composite material pipe beams, characterized in that, The process comprises the following steps: S1, core mold making: splice several sections of foam core mold (1-1) with the same diameter to form a foam core mold A (1) of a specified length; S2, laying the tear layer: clean the surface of the foam core mold A (1), then lay the inner expansion bag on the surface of the foam core mold A (1), and then lay the tear layer (2); S3, prepreg laying: lay composite prepreg on the tear layer (2) to form a preform (3), and after the prepreg laying is completed, continue to lay the tear layer (2) on the preform (3), so that several prepregs are laid in a lap joint manner and a lap joint (4) is formed; Wherein, the circumference of the preform (3) is measured after laying 3-5 layers of prepreg, and the circumference tolerance of the preform (3) is controlled to be-10%-0, and the width of the lap joint (4) is 1-10mm; S4, mold closing: place the foam core mold A (1) laid with composite prepreg into the forming lower mold (5) and ensure that the lap joint (4) is staggered with the mold joint (7) position of the forming lower mold (5) and the forming upper mold (6), then close the forming upper mold (6) and the forming lower mold (5) and set the air guide channel (8) at the mold joint (7); S5, curing: after closing the mold, a vacuum bag is provided outside the forming lower mold (5) and the forming upper mold (6), the inner expansion bag is combined with the vacuum bag to pressurize, and the mold is placed in an oven for heating, and after the mold temperature rises to a certain temperature, pulse pressure is applied; repeat the above heating and pressurizing method for curing and forming; Wherein, the inner expansion bag is inflated to generate an inner expansion pressure, and the inner expansion pressure is 1-20 atm, and pulse pressure is applied when the mold temperature rises to 70-90℃; S6, after curing is completed, demolding is performed, and the apparent quality and internal quality are inspected to obtain a large-size composite pipe beam.

2. A process for forming a large composite tube beam according to claim 1, wherein In step S1, the foam core mold (1-1) is spliced by hot melt adhesive.

3. The process of claim 1, wherein, The straightness of the foam core mold A (1) formed by splicing in step S1 ≤2mm / 1m.

4. The process of claim 1, wherein, The circumference of the foam core mold A (1) is controlled, and the circumference calculation formula is: C=(Φ-t*2)*π*Δ; C: circumference; Φ: part outer diameter; t: part thickness; Δ: scaling factor of foam core mold, and the scaling factor is 0.9-1.

05.

5. The process of claim 1, wherein, The number of layers of the tear layer (2) is 1-3 layers.

6. The process of claim 1, wherein, In step S4, the lap joint (4) is staggered by at least 20mm above and below the mold joint (7).

7. The process of claim 1, wherein, In step S4, the tear layer is laid at the mold joint (7), and the tear layer is used to make the mold joint have a certain gap to form an air guide channel (8), and the width of the gap is 0.2-0.5mm.

Images