A method for forming a thin-walled pipe of a carbon fiber metal composite material

Abstract

The present invention discloses a method for forming a thin-walled pipe fitting of a carbon fiber metal composite material, and belongs to the technical field of thin-walled pipe fitting forming. The method for forming a thin-walled pipe fitting of a carbon fiber metal composite material comprises the following steps: S1, treating a metal strip; S2, laying a carbon fiber prepreg on the surface of the metal strip to obtain a thin-walled composite material strip; S3, winding the thin-walled composite material strip on a round rod, the metal strip contacts the round rod, and obtaining a preform; S4, demoulding the preform from the round rod to obtain a thin-walled pipe blank; S5, placing the thin-walled pipe blank in a curing device and curing it under the protection of an inert gas to obtain a thin-walled pipe fitting. The method for forming a thin-walled pipe fitting of a carbon fiber metal composite material described in the present invention can solve the problems of complex process, high cost, and long cycle of the existing thin-walled pipe fitting forming method.

Description

Technical Field

[0001] The invention relates to the technical field of thin-wall pipe fitting forming, and in particular to a method for forming a carbon fiber metal composite material thin-wall pipe fitting. Background Art

[0002] Common methods for forming carbon fiber / metal composite thin-walled pipe fittings include compression molding + metal insert combination method, pultrusion molding + metal coating method, composite material lamination + metal welding / mechanical connection method, etc. Compression molding + metal insert combination method is to place the carbon fiber prepreg in the mold according to the predetermined layer sequence and thickness, and combine it with the metal insert. This method can produce carbon fiber / metal micro-laminated composite pipe fittings with high dimensional accuracy, but it is difficult to prepare very thin pipe fittings. At the same time, the mold cost is high and the production cycle is relatively long. Pultrusion molding + metal coating method is usually suitable for surface treatment of pipe fittings rather than the preparation of multi-layer composite structures. Composite material lamination + metal welding / mechanical connection method is to laminate multiple layers of fiber composite materials together by hot pressing or other means to form a carbon fiber material pipe section, and then weld or mechanically connect the metal pipe section with the carbon fiber material pipe section to form a multi-layer composite pipe fitting. The disadvantage is that the molding process is complicated and it is difficult to achieve uniform distribution of carbon fiber layers and metal layers. Summary of the invention

[0003] The purpose of the present invention is to provide a carbon fiber metal composite material thin-wall pipe forming method to solve the problems of complex process, high cost and long cycle of the existing thin-wall pipe forming method.

[0004] To achieve the above object, the present invention provides a method for forming a carbon fiber metal composite thin-wall pipe, comprising the following steps:

[0005] S1. Processing the metal strip;

[0006] S2, laying the carbon fiber prepreg on the surface of the metal strip to obtain a composite material strip;

[0007] S3, winding the composite material thin strip on the round rod, the metal thin strip is in contact with the round rod, and a preform is obtained;

[0008] S4, demoulding the preform from the round rod to obtain a thin-walled tube;

[0009] S5. Put the thin-walled tube blank into a curing device and cure it under the protection of inert gas to obtain a thin-walled tube fitting.

[0010] Preferably, in S1, the metal strip processing comprises the following steps:

[0011] S11, pre-treating the surface of the metal strip;

[0012] S12, placing the pretreated metal strip into a corrosion solution for corrosion;

[0013] S13, soaking the corroded metal strip in a coupling agent hydrolysis solution.

[0014] Preferably, in S11, the pretreatment is to perform sandblasting and rust removal on the surface of the metal strip, and to use acetone to clean the surface of the metal strip.

[0015] Preferably, in S12, the corrosion liquid is a sodium hydroxide solution with a mass concentration of 5wt.% to 15wt.%, and the corrosion time is 1h to 3h.

[0016] Preferably, in S13, the mass fraction of the silane coupling agent solute in the coupling agent hydrolysis solution is 0.5wt.%~2wt.%, the silane coupling agent is mixed with distilled water and then hydrolyzed for 5min~15min, and the metal strip is immersed in the coupling agent hydrolysis solution for 1min~5min.

[0017] Preferably, in S2, the thickness of the metal strip is not greater than 0.1 mm, and the thickness of the carbon fiber prepreg laying layer is not greater than 0.1 mm.

[0018] Preferably, in S5, the curing treatment temperature is 100° C. to 150° C., the curing pressure is 0.5 MPa, and the curing time is 2.5 h.

[0019] Preferably, the curing device includes an upper die seat, which is arranged on the movable beam of the hydraulic press, an upper die is arranged below the upper die seat, the upper die and the upper die seat are connected via an upper support seat, a lower die is arranged below the upper die, the lower die is connected to the workbench via a lower support seat, the workbench is arranged on the support platform of the hydraulic press, an induction coil is arranged on the lower support seat, the induction coil is located outside the upper die and the lower die, a lower forming groove for placing a thin-walled tube blank is arranged on the upper surface of the lower die, an upper forming groove matched with the lower forming groove is arranged on the lower surface of the upper die, the upper forming groove and the lower forming groove are spliced ​​together to form a forming cavity, the two ends of the forming cavity are open, and a stamping structure for pressurizing the forming cavity is arranged on the workbench.

[0020] Preferably, the stamping structure includes a first punch and a second punch, the first punch is arranged on the first bracket through the first hydraulic cylinder, and the second punch is arranged on the second bracket through the second hydraulic cylinder, the first bracket and the second bracket are both arranged on a workbench, and the interior of the second punch is provided with an air hole for introducing inert gas into the molding cavity, and the air inlet end of the air hole is connected to the inert gas bottle through an air pipe, and the first punch and the second punch seal the openings at both ends of the molding cavity under the action of the first hydraulic cylinder and the second hydraulic cylinder respectively.

[0021] Preferably, the first punch and the second punch are of conical structure, and both ends of the forming cavity are provided with flaring sections adapted to the conical surfaces of the first punch and the second punch; the upper surface of the lower die is provided with a positioning platform for facilitating the closing of the upper die and the lower die, and the lower surface of the upper die is provided with a positioning groove adapted to the positioning platform.

[0022] The advantages and positive effects of the carbon fiber metal composite thin-wall pipe forming method of the present invention are:

[0023] 1. The thickness of the thin-walled pipe fittings described in the present invention can be controlled according to the number of winding turns. The thickness of the thin-walled pipe fittings can be flexibly set according to needs, and thin-walled pipe fittings with different wall thicknesses can be produced.

[0024] 2. The present invention produces thin-walled pipe fittings by means of laying, winding and curing, which is highly efficient and low in cost.

[0025] 3. The thin-walled tube blank is formed by inert gas protection and pressurization, which improves the forming quality of thin-walled pipe fittings, makes the tube wall thickness more uniform, and has high surface forming quality.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a flow chart of an embodiment of the present invention;

[0028] Figure 2 It is a schematic diagram of the exploded structure of the curing device according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the curing device in use state according to an embodiment of the present invention;

[0030] Figure 4 It is a schematic diagram of the mold structure of the curing device according to an embodiment of the present invention.

[0031] Reference numerals

[0032] 1. Metal strip; 2. Carbon fiber prepreg; 3. Round rod; 4. Thin-walled tube; 5. Workbench; 6. Upper die seat; 7. Upper support seat; 8. Lower support seat; 9. Upper die; 10. Lower die; 11. Induction coil; 12. First hydraulic cylinder; 13. Second hydraulic cylinder; 14. First punch; 15. Second punch; 16. First bracket; 17. Second bracket; 18. Positioning groove; 19. Positioning platform; 20. Air hole; 21. Hydraulic press movable beam; 22. Hydraulic press support platform; 23. Hydraulic system. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] Example

[0036] like Figure 1 A method for forming a carbon fiber metal composite thin-wall pipe fitting comprises the following steps:

[0037] S1. Processing the metal strip 1.

[0038] The metal strip 1 treatment comprises the following steps:

[0039] S11, pre-treating the surface of the metal strip 1.

[0040] The pretreatment is to perform sandblasting on the surface of the metal strip 1 to remove rust. The sandblasting can not only remove the rust on the surface of the metal strip 1, but also improve the fatigue resistance of the metal strip 1 and increase the adhesion area and adhesion between the metal strip 1 and the carbon fiber prepreg 2. The surface of the metal strip 1 is cleaned with acetone.

[0041] S12, placing the pretreated metal strip 1 into a corrosion solution for corrosion.

[0042] The etching liquid is a sodium hydroxide solution with a mass concentration of 10 wt.%, and the etching time is 2 hours. The surface of the metal strip 1 is corroded and the surface of the metal strip 1 is hydroxylated.

[0043] S13, soaking the corroded metal strip 1 in a coupling agent hydrolysis solution.

[0044] The mass fraction of the silane coupling agent solute in the coupling agent hydrolysis solution is 0.5wt.%~2wt.%, the silane coupling agent is mixed with distilled water and then hydrolyzed for 5min~15min, and the metal strip 1 is immersed in the coupling agent hydrolysis solution for 1min~5min.

[0045] S2. Laying the carbon fiber prepreg 2 on the surface of the metal strip 1 to obtain a composite material strip.

[0046] The thickness of the metal strip 1 is not greater than 0.1 mm, and the thickness of the carbon fiber prepreg 2 laying layer is not greater than 0.1 mm.

[0047] When the metal strip 1 is prepared, the width of the metal strip 1 is reserved by 10 mm to 15 mm. After the thin-walled pipe is formed, both ends of the metal strip 1 need to be cut to ensure the end quality of the thin-walled pipe.

[0048] S3, winding the composite material thin strip on the round rod 3, the metal thin strip 1 is in contact with the round rod 3, and a preform is obtained.

[0049] The composite material thin strip is wound on the round rod 3 in a multi-layer winding manner. Before winding, a boron nitride coating is sprayed on the surface of the round rod 3 to facilitate demoulding of the preform.

[0050] S4, demoulding the preform from the round rod 3 to obtain a thin-walled tube 4. The inner layer of the thin-walled tube 4 is a metal strip 1.

[0051] S5. Put the thin-walled tube blank 4 into a curing device and cure it under the protection of inert gas to obtain a thin-walled tube fitting.

[0052] The curing temperature is 100℃~150℃, the curing pressure is 0.5MPa, and the curing time is 2.5h. The inert gas can be high-purity argon.

[0053] like Figure 2 , Figure 3 , Figure 4 As shown. The curing device includes an upper die seat 6, and the upper die seat 6 is fixedly arranged on the movable beam 21 of the hydraulic press. The hydraulic press adopts the existing structure as needed. An upper die 9 is arranged below the upper die seat 6, and the upper die 9 is connected to the upper die seat 6 through an upper support seat 7. The upper support seat 7 is fixed to the upper die seat 6 by bolts, and the upper die 9 is fixed to the upper support seat 7 by bolts. A lower die 10 is arranged below the upper die 9, and the lower die 10 is connected to the workbench 5 through a lower support seat 8. The lower die 10 is fixed to the lower support seat 8 by bolts, and the lower support seat 8 is fixed to the workbench 5 by bolts. The workbench 5 is fixedly arranged on the support table 22 of the hydraulic press. A positioning table 19 is fixedly arranged on the upper surface of the lower die 10 for facilitating the mold closing of the upper die 9 and the lower die 10, and a positioning groove 18 adapted to the positioning table 19 is arranged on the lower surface of the upper die 9.

[0054] An induction coil 11 is provided on the lower support seat 8, and the induction coil 11 is located outside the upper die 9 and the lower die 10. The induction coil 11 is used to heat the upper die 9 and the lower die 10, thereby heating the thin-walled tube 4, which is convenient for solidification of the thin-walled tube 4. The induction coil 11 is used to heat the thin-walled tube 4, which can achieve a fast and uniform heating effect, and the heating power can be controlled by adjusting the frequency and amplitude of the high-frequency current to achieve precise control of the heating process.

[0055] The upper surface of the lower die 10 is provided with a lower molding groove for placing the thin-walled tube blank 4, and the lower surface of the upper die 9 is provided with an upper molding groove adapted to the lower molding groove, and the upper molding groove and the lower molding groove are assembled to form a molding cavity. Before curing the thin-walled tube blank 4, it is necessary to spray a release agent on the surface of the upper molding groove and the lower molding groove, and spray it again twice after the release agent dries; and place a release cloth in the molding groove to facilitate the demoulding of the thin-walled pipe fittings. The two ends of the molding cavity are open, and a stamping structure for pressurizing the molding cavity is provided on the workbench 5.

[0056] The punching structure includes a first punch 14 and a second punch 15. The first punch 14 is arranged on the first bracket 16 through the first hydraulic cylinder 12. The first hydraulic cylinder 12 is fixedly arranged on the first bracket 16, and the first punch 14 is fixedly arranged on the piston rod of the first hydraulic cylinder 12. The second punch 15 is arranged on the second bracket 17 through the second hydraulic cylinder 13. The second hydraulic cylinder 13 is fixedly arranged on the second bracket 17, and the second punch 15 is fixedly arranged on the piston rod of the second hydraulic cylinder 13. The first hydraulic cylinder 12 and the second hydraulic cylinder 13 are both connected to the hydraulic system 23. The first bracket 16 and the second bracket 17 are both fixedly arranged on the workbench 5. The first punch 14 and the second punch 15 seal the openings at both ends of the forming cavity under the action of the first hydraulic cylinder 12 and the second hydraulic cylinder 13, respectively, and the first punch 14 and the second punch 15 are both inserted into the interior of the thin-walled tube blank 4, and the end of the thin-walled tube blank 4 is expanded and sealed. The second punch 15 is provided with a gas hole 20 for introducing an inert gas into the forming cavity, and the gas inlet end of the gas hole 20 is connected to the inert gas bottle through a gas pipe. The inert gas enters the forming cavity through the second punch 15, and the gas outlet of the gas hole 20 is located inside the thin-walled tube blank 4, and the thin-walled tube blank 4 is formed from the inside of the thin-walled tube blank 4. The inert gas protects the thin-walled tube blank 4 and provides pressure for the forming of the thin-walled tube blank 4, so that the surface quality of the thin-walled tube fitting is improved.

[0057] The first punch 14 and the second punch 15 are conical structures, and the cone angle of the first punch 14 and the second punch 15 is 10°. The two ends of the forming cavity are provided with expansion sections adapted to the cone surfaces of the first punch 14 and the second punch 15, and the inclination angle of the expansion section is 10°. The length of the expansion section is set to 7 mm to improve the sealing effect between the first punch 14, the second punch 15 and the forming cavity.

[0058] Therefore, the carbon fiber metal composite material thin-walled pipe forming method of the present invention can solve the problems of complex process, high cost and long cycle of the existing thin-walled pipe forming method.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for forming a carbon fiber metal composite thin-wall pipe, characterized in that: The following steps are involved: S1. Processing the metal strip; S2, laying the carbon fiber prepreg on the surface of the metal strip to obtain a composite material strip; S3, winding the composite material thin strip on the round rod, the metal thin strip is in contact with the round rod, and a preform is obtained; S4, demoulding the preform from the round rod to obtain a thin-walled tube; S5, placing the thin-walled tube blank into a curing device and curing it under the protection of an inert gas to obtain a thin-walled tube fitting; In S5, the curing temperature is 100°C to 150°C, the curing pressure is 0.5MPa, and the curing time is 2.5h; The curing device comprises an upper die seat, which is arranged on a movable beam of a hydraulic press, an upper die is arranged below the upper die seat, the upper die and the upper die seat are connected via an upper support seat, a lower die is arranged below the upper die, the lower die is connected to a workbench via a lower support seat, the workbench is arranged on a support table of the hydraulic press, an induction coil is arranged on the lower support seat, the induction coil is located outside the upper die and the lower die, a lower forming groove for placing a thin-walled tube blank is arranged on the upper surface of the lower die, an upper forming groove adapted to the lower forming groove is arranged on the lower surface of the upper die, the upper forming groove and the lower forming groove are combined to form a forming cavity, both ends of the forming cavity are open, and a stamping structure for pressurizing the forming cavity is arranged on the workbench; The stamping structure includes a first punch and a second punch. The first punch is arranged on a first bracket through a first hydraulic cylinder, and the second punch is arranged on a second bracket through a second hydraulic cylinder. The first bracket and the second bracket are both arranged on a workbench. An air hole for introducing an inert gas into a molding cavity is arranged inside the second punch. The air inlet end of the air hole is connected to an inert gas bottle through an air pipe. The first punch and the second punch seal the openings at both ends of the molding cavity under the action of the first hydraulic cylinder and the second hydraulic cylinder respectively.

2. A carbon fiber metal composite material thin-wall pipe forming method according to claim 1, characterized in that: In S1, the metal strip processing comprises the following steps: S11, pre-treating the surface of the metal strip; S12, placing the pretreated metal strip into a corrosion solution for corrosion; S13, soaking the corroded metal strip in a coupling agent hydrolysis solution.

3. A carbon fiber metal composite material thin-wall pipe forming method according to claim 2, characterized in that: In the S11, the pretreatment is to perform sandblasting and rust removal on the surface of the metal strip, and to clean the surface of the metal strip with acetone.

4. A carbon fiber metal composite material thin-wall pipe forming method according to claim 2, characterized in that: In the S12, the etching liquid is a sodium hydroxide solution with a mass concentration of 5wt.% to 15wt.%, and the etching time is 1h to 3h.

5. The method for forming a carbon fiber metal composite thin-wall pipe according to claim 2, characterized in that: In S13, the mass fraction of the silane coupling agent solute in the coupling agent hydrolysis solution is 0.5wt.%~2wt.%, the silane coupling agent is mixed with distilled water and then hydrolyzed for 5min~15min, and the metal strip is immersed in the coupling agent hydrolysis solution for 1min~5min.

6. The method for forming a carbon fiber metal composite thin-wall pipe according to claim 1, characterized in that: In S2, the thickness of the metal strip is not greater than 0.1 mm, and the thickness of the carbon fiber prepreg laying layer is not greater than 0.1 mm.

7. The method for forming a carbon fiber metal composite thin-wall pipe according to claim 1, characterized in that: The first punch and the second punch are of conical structure, and both ends of the forming cavity are provided with expansion sections adapted to the conical surfaces of the first punch and the second punch; the upper surface of the lower die is provided with a positioning platform for facilitating the closing of the upper die and the lower die, and the lower surface of the upper die is provided with a positioning groove adapted to the positioning platform.

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