A square tube forming process relying on a recycled use mold forming
By using a molding process that recycles molds, the problems of incomplete R-angle pressing and poor appearance quality in the molding of carbon fiber composite square tubes have been solved, resulting in smooth surfaces, reduced costs, and increased productivity. This technology is suitable for manufacturing composite square tubes in the aerospace and marine industries.
Patent Information
- Application Number
- CN202211569080.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-08
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2042-12-08
AI Technical Summary
Existing carbon fiber composite square tube forming processes cannot be properly compacted at the radius corners, easily causing delamination and wrinkles, resulting in poor appearance quality, failure to meet mechanical performance requirements, high costs, and no improvement in productivity.
The molding process employs a reusable mold, which involves laying carbon fiber composite material and wet prepreg on the inner surfaces of the upper and lower molds, using a layer-drop design and co-bonding technology, combined with autoclave curing, to achieve mold recycling and simultaneous molding of multiple square tubes.
It achieves a smooth and flat surface on the composite square tube, with no wrinkles when the R-angle is compacted, and can be laid at any angle, reducing costs, improving production efficiency, and reducing energy consumption.
Smart Images
Figure CN116394542B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of pipe fitting manufacturing, and in particular to a square tube forming process that relies on the recycling of molds. Background Technology
[0002] Carbon fiber composite materials are now widely used in aviation, shipbuilding and other fields. Composite square tubes are a common type of molded parts. The molding process is as follows: (1) Positive mold laying: laying, bag making and curing are carried out on the positive mold. The outer surface of this molding method is the bag making surface, which has poor appearance quality. The R corners are not pressed firmly and wrinkles are obvious. (2) Winding process: the laying angle cannot be selected and the mechanical properties with directional requirements cannot be met. (3) For molding methods with good appearance quality, a release film is wrapped on the foam, and the material is laid on the release film. After laying, it is placed in the upper and lower mold clamping fixture for internal expansion and curing.
[0003] This method is well-established for use on round tubes, but when applied to square tubes, the corners are not properly compacted, easily leading to delamination, wrinkles, and insufficient resin. Furthermore, after high-temperature curing, the foam shrinks, making it unusable, increasing costs, and failing to improve productivity. Summary of the Invention
[0004] In view of the problems mentioned in the background art, the purpose of this invention is to provide a square tube forming process that relies on the recycling of molds to solve the problems mentioned in the background art.
[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:
[0006] A square tube forming process relying on the recycling of molds includes the following steps:
[0007] S1. Lay carbon fiber composite material on the inner surface of the upper mold. During the layup process, a layer-dropping design is used to make Part A1 into bags. Curing is done in an autoclave. Demolding is done after natural cooling to below 60°C to obtain Part A1.
[0008] S2. Lay the wet prepreg-made Part B1 on the inner surface of the lower mold. During the layering process, a layer-dropping design is adopted. The cured part Part A1 is turned upside down and co-bonded with Part B1. The upper and lower molds are connected with bolts and combined together to make bags.
[0009] S3. The upper mold, lower mold and their components connected by bolts are sent to the autoclave for curing. At the same time, Part A2 is laid on the inner surface of the upper mold to make bags.
[0010] S4. Demold the lower mold part to obtain the desired finished square tube, and demold the upper mold to produce the half part PartA2.
[0011] S5. Lay the wet prepreg part B2 on the inner surface of the lower mold, turn the demolded part A2 upside down, and bond it together with part B2. Connect the upper and lower molds with bolts and combine them to make bags. At the same time, lay part A3 on the inner surface of the upper mold to make bags.
[0012] S6. Repeat steps S3-S5 to produce PartAn and PartBn in a loop.
[0013] Preferably, in S1, S2 and S5, during bag making, a release cloth, a non-porous release film, a breathable felt and a vacuum bag are applied sequentially to the surface of the workpiece, and then a vacuum pump is turned on for cold vacuuming at room temperature.
[0014] Preferably, in S1 and S2, when using an autoclave for curing, the pressure is 0.3-1 MPa throughout the process, the vacuum degree is -0.09 MPa, the temperature is increased from room temperature to 120±5℃ at a heating rate of 1-2℃ / min, and the temperature is held at 120±5℃ for 90±5min.
[0015] Preferably, in S1 and S2, when using an autoclave for curing, the pressure is 0.6 MPa throughout the process, the vacuum degree is -0.09 MPa, the temperature is increased from room temperature to 120±5℃ at a heating rate of 2℃ / min, and the temperature is held at 120±5℃ for 90±5min.
[0016] Preferably, the wet prepreg used in S2 is carbon fiber epoxy resin.
[0017] Preferably, in step S2, when co-bonding the prepreg with the wet prepreg part Part B, the prepreg is cut into sheets and then bonded.
[0018] In summary, the present invention has the following main beneficial effects:
[0019] 1. It can make the surface of composite material square tubes smooth and flat, and the R-angle compacted without wrinkles;
[0020] 2. You can choose to cut and lay the material at any angle.
[0021] 3. It can produce "one and a half" square tubes at a time, reducing costs. The mold can also be modified by adding molding grooves of the same or different sizes in the horizontal or vertical direction, depending on the size of the curing oven and the production quantity, to cure multiple "one and a half" square tubes at once, further reducing energy consumption. Attached Figure Description
[0022] Figure 1 This is a diagram of a mold for forming reusable square tubes.
[0023] Attached reference numerals: 1. Upper mold; 2. Lower mold. Detailed Implementation
[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] refer to Figure 1 A square tube forming process that relies on the recycling of molds includes the following steps:
[0026] S1. Carbon fiber composite material is laid on the inner surface of the upper mold 1. During the layup process, a layer-dropping design is adopted to make Part A1 into a bag. It is cured in an autoclave and then naturally cooled to 58°C to demold, thus obtaining Part A1.
[0027] S2. Lay the wet prepreg Part B1 on the inner surface of the lower mold 2. During the layering process, a layer-dropping design is adopted. The cured part Part A1 is turned upside down and co-bonded with Part B1. The upper and lower molds 2 are connected with bolts and combined together to make bags.
[0028] S3. The upper mold 1 and lower mold 2, which are connected by bolts, and their components are sent to a hot autoclave for curing. At the same time, Part A2 is laid on the inner surface of the upper mold 1 to make bags.
[0029] S4. Demold the lower mold 2 part to obtain the desired finished square tube, and demold the upper mold 1 to produce the half part PartA2.
[0030] S5. Lay the wet prepreg part B2 on the inner surface of the lower mold 2, turn the demolded part A2 upside down, and bond it together with part B2. Connect the upper and lower molds 2 with bolts and combine them to make bags. At the same time, lay part A3 on the inner surface of the upper mold 1 to make bags.
[0031] S6. Repeat steps S3-S5 to produce PartAn and PartBn in a loop.
[0032] refer to Figure 1 This manufacturing process ensures a smooth and flat surface for the composite square tube, with wrinkle-free compacted R-corners. It allows for material cutting and laying at any angle. Furthermore, it can produce "one and a half" square tubes at a time, reducing costs. The mold can also be modified by adding molding grooves of the same or different sizes horizontally or vertically, depending on the size of the curing oven and the production quantity, allowing for the curing of multiple "one and a half" square tubes at once, further reducing energy consumption.
[0033] refer to Figure 1In S1, S2 and S5, during bag making, a release cloth, a non-porous release film, a breathable felt and a vacuum bag are applied sequentially to the surface of the workpiece, and then a vacuum pump is turned on to perform cold vacuuming at room temperature.
[0034] refer to Figure 1 In S1 and S2, when using an autoclave for curing, a pressure of 0.3 MPa is used throughout the process, the vacuum degree is -0.09 MPa, the temperature is increased from room temperature to 122°C at a heating rate of 1°C / min, and then held at 124°C for 90 min.
[0035] refer to Figure 1 In S1 and S2, when using an autoclave for curing, a pressure of 0.6 MPa is used throughout the process, the vacuum degree is -0.09 MPa, the temperature is increased from room temperature to 118°C at a heating rate of 2°C / min, and then held at 119°C for 905 min.
[0036] refer to Figure 1 The wet prepreg used in S2 is carbon fiber epoxy resin. When co-bonding the wet prepreg with Part B in S2, the prepreg is cut into sheets.
[0037] refer to Figure 1 A square tube forming process that relies on the recycling of molds includes the following steps:
[0038] S1. Carbon fiber composite material is laid on the inner surface of the upper mold 1. During the layup process, a layer-dropping design is adopted to make Part A1 into a bag. It is cured in an autoclave and demolded after natural cooling to 56°C to obtain Part A1.
[0039] S2. Lay the wet prepreg Part B1 on the inner surface of the lower mold 2. During the layering process, a layer-dropping design is adopted. The cured part Part A1 is turned upside down and co-bonded with Part B1. The upper and lower molds 2 are connected with bolts and combined together to make bags.
[0040] S3. The upper mold 1 and lower mold 2, which are connected by bolts, and their components are sent to a hot autoclave for curing. At the same time, Part A2 is laid on the inner surface of the upper mold 1 to make bags.
[0041] S4. Demold the lower mold 2 part to obtain the desired finished square tube, and demold the upper mold 1 to produce the half part PartA2.
[0042] S5. Lay the wet prepreg part B2 on the inner surface of the lower mold 2, turn the demolded part A2 upside down, and bond it together with part B2. Connect the upper and lower molds 2 with bolts and combine them to make bags. At the same time, lay part A3 on the inner surface of the upper mold 1 to make bags.
[0043] S6. Repeat steps S3-S5 to produce PartAn and PartBn in a loop.
[0044] refer to Figure 1 This manufacturing process ensures a smooth and flat surface for the composite square tube, with wrinkle-free compacted R-corners. It allows for material cutting and laying at any angle. Furthermore, it can produce "one and a half" square tubes at a time, reducing costs. The mold can also be modified by adding molding grooves of the same or different sizes horizontally or vertically, depending on the size of the curing oven and the production quantity, allowing for the curing of multiple "one and a half" square tubes at once, further reducing energy consumption.
[0045] refer to Figure 1 In S1, S2 and S5, during bag making, a release cloth, a non-porous release film, a breathable felt and a vacuum bag are applied sequentially to the surface of the workpiece, and then a vacuum pump is turned on to perform cold vacuuming at room temperature.
[0046] refer to Figure 1 In S1 and S2, when using an autoclave for curing, the pressure is 1 MPa throughout the process, the vacuum degree is -0.09 MPa, the temperature is increased from room temperature to 125°C at a heating rate of 2°C / min, and then held at 115°C for 90 min.
[0047] refer to Figure 1 In S1 and S2, when using an autoclave for curing, a pressure of 0.6 MPa is used throughout the process, the vacuum degree is -0.09 MPa, the temperature is increased from room temperature to 123°C at a heating rate of 2°C / min, and then held at 122°C for 88 min.
[0048] refer to Figure 1 The wet prepreg used in S2 is carbon fiber epoxy resin. When co-bonding the wet prepreg with Part B in S2, the prepreg is cut into sheets.
[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A square tube forming process relying on the recycling of molds, characterized in that: Includes the following steps: S1. Carbon fiber composite material is laid on the inner surface of the upper mold (1). During the layup process, a layer-dropping design is adopted to make Part A1 into a bag. It is cured in a hot autoclave and naturally cooled to below 60°C to demold, thus obtaining Part A1. S2. Wet prepreg Part B1 is laid on the inner surface of the lower mold (2). During the laying process, a layer-dropping design is adopted. The cured part Part A1 is turned upside down and bonded together with Part B1. The upper and lower molds (2) are connected by bolts and combined together to make bags. S3. The upper mold (1), lower mold (2) and their components connected by bolts are sent to a hot autoclave for curing. At the same time, Part A2 is laid on the inner surface of the upper mold (1) to make bags. S4. Demold the lower mold (2) to obtain the desired finished square tube, and demold the upper mold (1) to produce the half part Part A2. S5. Lay the wet prepreg part B2 on the inner surface of the lower mold (2), turn the demolded part A2 upside down and bond it together with part B2. Connect the upper and lower molds (2) with bolts and combine them to make bags. At the same time, lay part A3 on the inner surface of the upper mold (1) to make bags. S6. Repeat steps S3-S5 to cyclically produce PartAn and PartBn; In S1 and S2, when using an autoclave for curing, the temperature is increased from room temperature to 120±5℃ at a rate of 1-2℃ / min, and then held at 120±5℃ for 90±5min.
2. The square tube forming process relying on the recycling of molds according to claim 1, characterized in that: In S1, S2 and S5, during bag making, a release cloth, a non-porous release film, a breathable felt, and a vacuum bag are sequentially applied to the surface of the workpiece, and then a vacuum pump is turned on for cold vacuuming at room temperature.
3. The square tube forming process relying on the recycling of molds according to claim 1, characterized in that: In S1 and S2, when using an autoclave for curing, a pressure of 0.3-1 MPa is used throughout the process, and the vacuum degree is -0.09 MPa.
4. The square tube forming process relying on the recycling of molds according to claim 1, characterized in that: In S1 and S2, when using an autoclave for curing, a pressure of 0.6 MPa is used throughout the process, with a vacuum degree of -0.09 MPa. The temperature is increased from room temperature to 120±5℃ at a heating rate of 2℃ / min, and then held at 120±5℃ for 90±5min.
5. The square tube forming process relying on the recycling of molds according to claim 1, characterized in that: The wet prepreg used in S2 is carbon fiber epoxy resin.
6. The square tube forming process relying on the recycling of molds according to claim 1, characterized in that: In S2, when co-bonding with the wet prepreg part Part B, the prepreg is cut into sheets and then bonded.
Citation Information
Patent Citations
Manufacturing method for unmanned aerial vehicle non-equal-diameter closed square pipe shaped carbon fiber beam
CN110654039A