Stretching process of double-curved honeycomb aluminum plate skin

Abstract

The application provides a kind of hyperbolic honeycomb aluminum plate skin stretching processing technology, comprising: providing mould, according to the Gauss curvature of hyperbolic honeycomb aluminum plate to determine the form of mould; Put flat honeycomb aluminum plate on the mould; Cover flat honeycomb aluminum plate and mould with silica gel leather, form skin; Vacuum between silica gel leather and mould to form negative pressure; Under the action of skin negative pressure, carry out high temperature treatment, wait for flat honeycomb aluminum plate to complete sufficient stretching to form hyperbolic, glue film solidification. The application can make larger plate width workpiece, different mould forms are used for different Gauss curvature hyperbolic honeycomb plate, so that there is no stress wrinkle phenomenon in the forming process. The whole process has low dependence on site and equipment, and has the advantages of low cost.

Description

Technical Field

[0001] This invention relates to the field of honeycomb aluminum panel processing technology, specifically to a hyperbolic honeycomb aluminum panel skin stretching process. Background Technology

[0002] With the rapid development of technology in the construction industry, building shapes are becoming increasingly diverse and complex. Various graceful curves are gradually becoming the finishing touches in architectural works. This complex design places new demands on the processing technology of interior and exterior decorative materials during the finishing stage. Due to the unique advantages of honeycomb aluminum panels in the decoration of building interiors and exteriors, they are increasingly being used in numerous projects.

[0003] For flat panels, the processing technology of honeycomb aluminum panels is very mature, but the processing of curved panels is still in the exploratory stage, and a complete process flow has not yet been formed. Curved surfaces can be divided into three categories based on their Gaussian curvature K value: hyperboloids with a negative Gaussian curvature K value, typically represented by a saddle surface; surfaces with a zero Gaussian curvature K value, called single-curved surfaces, typically represented by various cylindrical surfaces; and hyperboloids with a positive Gaussian curvature K value, typically represented by spheres or the bottom of a pot. Among these, single-curved surfaces with a zero Gaussian curvature K value can be directly formed using a roll forming process along the surface structure lines; the other two types of curved surfaces cannot be formed using roll forming and require new forming processes.

[0004] The existing hyperbolic forming process is widely used in the automotive, shipbuilding and military industries. Large components are basically formed by either "integral die casting" or "CNC dot matrix stamping technology". In the aluminum plate industry, "CNC dot matrix stamping technology" and "convex and concave die combination stamping" are also used for aluminum single plates with a thickness of 2mm or more. CNC dot matrix stamping technology uses a combination of convex and concave dies to form a set of dies that can be controlled independently to stamp the workpiece.

[0005] The search revealed:

[0006] Chinese invention patent application CN103433380A discloses a punch forming method for a drawing die for automotive body panels. This method first uses stamping simulation analysis to simulate the forming process, checking areas where there is no double-sided contact between the sheet metal and the punch and die surfaces, and areas where the sheet metal does not wrinkle during forming. These areas are mapped onto the profiles of the punch and die. Then, the punch and die surfaces are divided into two types of features: punch and die. The boundary curves of the punch and die features are obtained, and the punch and die surfaces are divided by the boundary curves. The punch features of the forming parts of the punch and die of the sheet metal drawing die are retained, and the profiles of the punch and die of the actual drawing die are designed and processed accordingly.

[0007] However, the above-mentioned existing technologies are not very suitable for thin plates less than 2mm, mainly because: 1) The process of combining punch and die is too expensive and is only suitable for batch processing. It is not suitable for each plate, which is unique; 2) CNC dot matrix stamping equipment is expensive and the worktable (800mm*800mm) is small, making it impossible to produce workpieces with larger plate sizes; 3) The springback of the aluminum plate after stamping is too large, making it impossible to accurately press the hyperboloid that meets the requirements. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide a stretching process for hyperbolic honeycomb aluminum panel skins.

[0009] According to one aspect of the present invention, a stretching process for hyperbolic honeycomb aluminum panel skin is provided, comprising:

[0010] Provide a mold, and determine the mold form based on the Gaussian curvature of the hyperbolic honeycomb aluminum panel; place the flat honeycomb aluminum panel on the mold;

[0011] The mold and flat honeycomb aluminum plate are covered with silicone fabric to form a skin;

[0012] A vacuum is drawn between the silicone sheet and the mold surface to create negative pressure, so that the flat honeycomb aluminum plate is completely bonded to the mold.

[0013] The entire structure is aged under negative pressure on the skin until the adhesive film of the flat honeycomb aluminum panel is cured and the hyperbolic honeycomb aluminum panel is shaped.

[0014] Furthermore, the provision of the mold includes: forming a wooden mold by laser engraving.

[0015] Furthermore, the step of placing the flat honeycomb aluminum plate on the mold base is configured such that the contact position between the flat honeycomb aluminum plate and the mold base and the direction of deformation of the flat honeycomb aluminum plate are configured such that the in-plane non-deformable area of ​​the flat honeycomb aluminum plate first fits with the mold base, and during the skin stretching process, as the amount of stretching deformation increases, the deformed area gradually fits with the mold base.

[0016] Furthermore, the concave-convex form of the mold is determined by the sign of the Gaussian curvature value of the formed hyperbolic honeycomb aluminum plate.

[0017] Furthermore, for curved honeycomb aluminum panels with negative Gaussian curvature, a mold with a concave mold in the length direction and a convex mold in the width direction is used; during stretching, the length direction of the flat honeycomb aluminum panel is bonded to the mold in the middle area of ​​the width by gravity, and the unbonded area is stretched during skin stretching to bond the unbonded area to the mold.

[0018] Furthermore, for curved honeycomb aluminum panels with a positive Gaussian curvature, a mold with concave dies in both the length and width directions is used; during stretching, the edge of the flat honeycomb aluminum panel in the length direction first fits into the mold, and then the skin is stretched, stretching the center part so that the center part extends and fits into the mold.

[0019] Furthermore, the step of creating a negative pressure by drawing a vacuum between the silicone fabric and the mold surface includes: using a vacuum pump to create a negative pressure between the silicone fabric and the mold surface.

[0020] Furthermore, the adhesive film is cured by aging treatment under the negative pressure of the skin, wherein the aging treatment includes static aging or high temperature aging treatment.

[0021] Furthermore, the thickness of the face and back panels of the formed hyperbolic honeycomb aluminum panel is less than 1.5 mm, and the total thickness is no more than 25 mm.

[0022] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0023] 1. The hyperbolic honeycomb aluminum panel skin stretching process of the present invention utilizes skin stretching technology to enable the formed hyperbolic honeycomb aluminum panel to be free from the limitations of the stamping worktable. Theoretically, the size of the hyperbolic panel can be processed as large as the size of the aluminum plate raw material. Compared with the existing technology, it can produce hyperbolic honeycomb aluminum panel workpieces with larger plate widths.

[0024] 2. The hyperbolic honeycomb aluminum panel skin stretching process of the present invention determines the mold form according to the Gaussian curvature of the hyperbolic honeycomb aluminum panel, thereby enabling the deformation of the flat honeycomb aluminum panel to be entirely in-plane tensile deformation during the entire skin stretching process, and avoiding the stress wrinkling and ripple phenomenon that occurs when the aluminum panel is under pressure.

[0025] 3. The hyperbolic honeycomb aluminum panel skin stretching process of the present invention has the advantages of being economical and reusable. The entire process has a low dependence on site and equipment and the cost is controllable. Attached Figure Description

[0026] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0027] Figure 1 This is a diagram showing the interaction between the curved honeycomb aluminum plate with a positive Gaussian curvature, the mold, and the silicone rubber sheet in one embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of a curved honeycomb aluminum plate with a positive Gaussian curvature being bonded to a mold in one embodiment of the present invention;

[0029] Figure 3This is a schematic diagram of a curved honeycomb aluminum plate with a positive Gaussian curvature after shaping, according to one embodiment of the present invention.

[0030] Figure 4 This is a diagram showing the interaction between the curved honeycomb aluminum plate with a negative Gaussian curvature, the mold, and the silicone rubber sheet in one embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram of a curved honeycomb aluminum plate with a negative Gaussian curvature being bonded to a mold in one embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of a curved honeycomb aluminum plate with a negative Gaussian curvature after shaping, according to an embodiment of the present invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0034] This invention provides a stretching process for hyperbolic honeycomb aluminum panel skins, referring to... Figure 1-6 The process includes:

[0035] S1. Provide a mold, and determine the mold form according to the Gaussian curvature of the hyperbolic honeycomb aluminum panel; place the newly composited flat honeycomb aluminum panel (i.e., Figure 1 and Figure 4 The flat aluminum plate before stretching is placed on the mold.

[0036] S2. Cover the mold and the flat honeycomb aluminum plate with silicone cloth, and seal the edges with the surface of the mold with tape to form a skin. The silicone cloth and the surface of the mold form a cavity to wrap the honeycomb aluminum plate inside.

[0037] S3. Vacuum is drawn between the silicone rubber sheet and the surface of the mold to form a negative pressure; the mold serves as the mold for forming the hyperbolic honeycomb panel, and the flat honeycomb aluminum panel is completely bonded to the mold through negative pressure to obtain the desired hyperbolic surface;

[0038] S4. Under negative pressure, the flat honeycomb aluminum panel undergoes aging treatment until it is fully stretched and the hyperbolic honeycomb aluminum panel film is cured and formed. Figure 3 and Figure 6 The double-curved aluminum sheet after molding is shaped.

[0039] This invention utilizes skin stretching technology, allowing the formed hyperboloidal honeycomb aluminum panels to be produced without being limited by the stamping worktable. Theoretically, the size of the hyperboloidal panel can be processed based on the size of the raw aluminum sheet, enabling the production of larger hyperboloidal honeycomb aluminum panel workpieces compared to existing technologies. The mold form is determined based on the Gaussian curvature of the hyperboloidal honeycomb aluminum panel, ensuring that the deformation of the flat honeycomb aluminum panel during the entire skin stretching process is entirely in-plane tensile deformation, eliminating the stress wrinkling and ripple phenomenon that occurs when the aluminum sheet is under pressure. The silicone skin has the advantages of being economical and reusable, and the entire process has low dependence on site and equipment, making the cost controllable.

[0040] In some embodiments, a mold is provided, including forming a wooden mold using laser engraving. Using a wooden mold offers advantages such as ease of processing and low cost. It should be noted that in other embodiments, if the specifications of the hyperboloid board are relatively uniform, a metal frame plus a metal plate can also be used to make the mold, which is beneficial for improving reusability.

[0041] In this invention, an uncured flat honeycomb aluminum panel with a composite adhesive film is formed using a skin negative pressure pressing method. The contact position between the flat honeycomb aluminum panel and the mold, as well as the direction of deformation of the flat honeycomb aluminum panel, are crucial to ensure that the flat honeycomb aluminum panel remains in an in-plane tension state throughout the deformation process, thus preventing wrinkles from forming. In some embodiments, the flat honeycomb aluminum panel is placed on the mold, wherein the contact position between the flat honeycomb aluminum panel and the mold, and the direction of deformation of the flat honeycomb aluminum panel, are configured such that the in-plane non-deformable area of ​​the flat honeycomb aluminum panel initially adheres to the mold, and during the skin stretching process, as the stretching deformation increases, the deformed area gradually adheres to the mold.

[0042] The Gaussian curvature of the hyperbolic honeycomb aluminum panel determines the shape of the mold, making the selection of the mold crucial. In some embodiments, the concave-convex form of the mold is determined based on the sign of the Gaussian curvature value of the formed hyperbolic honeycomb aluminum panel.

[0043] Specifically, refer to Figure 4-6For curved honeycomb aluminum panels with negative Gaussian curvature, such as saddle-shaped honeycomb aluminum panels, A, B, C, and D represent four fixed points of the aluminum panel, V1 and V2 represent the midpoints of the two short sides of the aluminum panel, and U1 and U2 represent the midpoints of the two long sides of the aluminum panel. A mold with a concave die in the length direction and a convex die in the width direction is used. During stretching, the length direction of the flat honeycomb aluminum panel relies on gravity to adhere to the mold in the middle area of ​​the width (V1, V2). That is, under its own weight, the area connecting V1 and V2 is in contact with the mold. During skin stretching, the un-adhered area (U1, U2) produces... The stretching deformation brings the unbonded areas into contact with the mold, meaning that under negative pressure, the area outside the line connecting V1 and V2 gradually comes into contact with the mold. During skin stretching, the flat honeycomb aluminum plate deforms in both width and length directions. The width deformation is clearly the result of contact with the mold. Because the radius of curvature of the honeycomb aluminum plate increases after deformation, it must withstand tensile force in the length direction during deformation. During the process of the skin contacting the curved mold, there is a horizontal component force towards both ends, causing the honeycomb aluminum plate to undergo stretching deformation, achieving the desired hyperboloid shape. Conversely, if the horizontal component force of the skin is directed towards the center, the thin honeycomb aluminum plate cannot withstand in-plane compressive stress, resulting in wrinkling. Therefore, determining the mold form for skin stretching based on hyperboloids with different Gaussian curvatures is the key to the process of this application.

[0044] Reference Figure 1-3 For curved honeycomb aluminum panels with a positive Gaussian curvature, such as the bottom honeycomb aluminum panel of a pot, A, B, C, and D represent four fixed points of the aluminum panel, V1 and V2 represent the midpoints of the two short sides of the aluminum panel, U1 and U2 represent the midpoints of the two long sides of the aluminum panel, and P is the center point of the aluminum panel. A mold with concave dies in both the length and width directions is used. During stretching, the edges of the flat honeycomb aluminum panel in the length direction first fit with the mold (AD, BC), that is, under its own weight, the two long sides of the flat honeycomb aluminum panel first fit with the mold. Then, the skin is stretched, and the central V1, P, and V2 areas are stretched to extend the central part to fit with the mold. That is, under negative pressure, the area other than the two long sides gradually fits with the mold. During the stretching process, deformation occurs in both the length and width directions, similar to curved honeycomb aluminum panels with a negative Gaussian curvature. During the skin stretching process, the skin provides a horizontal component force to the honeycomb aluminum panel (similar to blowing up a balloon), causing the honeycomb aluminum panel to undergo tensile deformation and achieve the required hyperbolic shape.

[0045] The above-mentioned mold design ensures that during the skin stretching and forming process of the hyperbolic honeycomb aluminum panel, the non-deformable areas in the panel first adhere to the mold, and during the skin stretching process, the panels gradually adhere to the mold according to the amount of stretching deformation, ensuring that all parts of the panel are under tension during the forming process.

[0046] In some embodiments, the silicone sheet is a canvas-like material coated with silicone, possessing high strength and scratch resistance, while also exhibiting good sealing properties to meet the sealing requirements during the vacuuming process. Creating a negative pressure by evacuating the silicone sheet to the mold surface includes: using a vacuum pump (air compressor) to cover the silicone sheet around the mold surface and seal it before evacuating to create negative pressure. The vacuum pump equipment is conventional standard equipment, belonging to general-purpose equipment, and this process has low dependence on site and equipment. The magnitude of the negative pressure is affected by the air compressor; the negative pressure should be controlled to ensure that the honeycomb aluminum plate undergoes plastic deformation and adheres to the mold, while preventing the honeycomb aluminum plate from being crushed or developing honeycomb-like indentations. Therefore, the negative pressure value is related to the plate thickness and curvature changes. Since operation is in an atmospheric environment, the maximum negative pressure will not exceed one atmosphere. Preferably, a 22kW vacuum pump with a volumetric flow rate of 3.5 cubic meters / minute and an exhaust pressure of 0.8MPa is used. It is understood that the power of the vacuum pump is also related to the simultaneous evacuation of several molds. The negative pressure of the skin causes the honeycomb aluminum panel to undergo a certain degree of elastic-plastic deformation both inside and outside the plane, so that it fits into the mold and achieves the required hyperbolic panel shape.

[0047] In some embodiments, aging treatment is performed under negative pressure on the skin. This aging treatment includes static aging or high-temperature aging. Static aging refers to placing the film at room temperature for approximately 24 hours to cure, while high-temperature aging refers to accelerating the curing of the film at approximately 70 degrees Celsius for 20 minutes. Aging treatment accelerates the curing of the film, and this curing process also serves to shape the hyperboloid honeycomb panel, bonding the honeycomb core of the aluminum honeycomb panel to the face and back panels to achieve the desired shape.

[0048] In this embodiment of the invention, the hyperbolic honeycomb aluminum panel comprises three layers of material: an aluminum face plate, a back plate, and a honeycomb core. The sum of the thicknesses of the face plate, the back plate, and the honeycomb core is the total thickness of the hyperbolic honeycomb aluminum panel. The thickness of the face plate and the back plate of the formed hyperbolic honeycomb aluminum panel is less than 1.5 mm, and the total thickness is not greater than 25 mm. This facilitates the formation of a hyperbolic shape by deformation under negative pressure, and the panel can be formed within one atmosphere of pressure.

[0049] Since hyperbolic honeycomb aluminum panels are processed piece by piece in the factory workshop and need to be installed at high altitudes on site, the processing accuracy of the hyperbolic honeycomb aluminum panels will have a great impact on the efficiency of on-site installation. After the hyperbolic honeycomb aluminum panels are formed, they are also tested and pre-assembled to verify the processing accuracy of the hyperbolic honeycomb aluminum panels and reduce the amount of rework on site.

[0050] Existing CNC dot matrix stamping technology can cause dot-like indentations on the surface of honeycomb aluminum panels. Furthermore, simultaneous extrusion of different parts of the curved surface leads to localized tension and compression, with the compressed areas exhibiting stress ripples resembling wrinkles. In contrast, this invention employs a skin stretching technology, fundamentally solving the problem of stress ripples during the forming process of hyperbolic aluminum panels. In fact, the literal meanings of the two technologies reveal that the existing technology focuses on "stamping," while this invention emphasizes "stretching." This invention utilizes the excellent ductility of aluminum alloy to uniformly and orderly (from the earliest contact point at the center outwards) achieve tensile plastic deformation of the aluminum panel, thereby forming the desired hyperbolic shape.

[0051] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. A stretching process for hyperbolic honeycomb aluminum panel skin, characterized in that, include: Provide molds, and determine the mold form based on the Gaussian curvature of the hyperbolic honeycomb aluminum panel; Place the flat honeycomb aluminum plate on the mold; The flat honeycomb aluminum plate and the mold are covered with silicone fabric to form a skin; A vacuum is drawn between the silicone sheet and the mold surface to create negative pressure, so that the flat honeycomb aluminum plate is completely bonded to the mold. The skin is subjected to aging treatment under negative pressure until the film of the flat honeycomb aluminum panel is cured and the hyperbolic honeycomb aluminum panel is shaped. in: The concave-convex form of the mold is determined by the sign of the Gaussian curvature value of the formed hyperbolic honeycomb aluminum plate. For curved honeycomb aluminum panels with negative Gaussian curvature, a mold with a concave mold in the length direction and a convex mold in the width direction is used. For curved honeycomb aluminum panels with a positive Gaussian curvature, a mold with concave dies in both the length and width directions is used.

2. The hyperbolic honeycomb aluminum panel skin stretching process according to claim 1, characterized in that, The provision of the mold includes: forming a wooden mold by laser engraving.

3. The hyperbolic honeycomb aluminum panel skin stretching process according to claim 1, characterized in that, The flat honeycomb aluminum panel is placed on the mold, wherein the contact position between the flat honeycomb aluminum panel and the mold and the direction of deformation of the flat honeycomb aluminum panel are configured such that the in-plane non-deformable area of ​​the flat honeycomb aluminum panel first fits with the mold, and during the skin stretching process, as the stretching deformation increases, the deformed area gradually fits with the mold.

4. The hyperbolic honeycomb aluminum panel skin stretching process according to claim 1, characterized in that, For curved honeycomb aluminum panels with negative Gaussian curvature, during stretching, the length direction of the flat honeycomb aluminum panel relies on gravity to adhere to the mold in the middle area of ​​the width. When the skin is stretched, the unadhered area undergoes tensile deformation, causing the unadhered area to adhere to the mold.

5. The hyperbolic honeycomb aluminum panel skin stretching process according to claim 1, characterized in that, For curved honeycomb aluminum panels with a positive Gaussian curvature, during stretching, the edges of the flat honeycomb aluminum panel along the length direction first fit with the mold, and then the skin is stretched, pulling the center part to extend and fit with the mold.

6. The hyperbolic honeycomb aluminum panel skin stretching process according to claim 1, characterized in that, The step of creating a negative pressure by drawing a vacuum between the silicone fabric and the mold surface includes: using a vacuum pump to create a negative pressure between the silicone fabric and the mold.

7. The hyperbolic honeycomb aluminum panel skin stretching process according to claim 1, characterized in that, The aging treatment is carried out under negative pressure on the skin, wherein the aging treatment includes static aging or heating aging treatment.

8. The hyperbolic honeycomb aluminum panel skin stretching process according to claim 1, characterized in that, The thickness of the face and back panels of the formed hyperbolic honeycomb aluminum panel is less than 1.5mm, and the total thickness is no more than 25mm.

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