Anti-cracking sheet metal part structure
Patent Information
- Application Number
- CN202522699803.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-19
- Publication Date
- 2026-09-22
- Estimated Expiration
- 2035-12-19
AI Technical Summary
1、该一种防裂钣金件结构，在钣金基体与外部功能涂层之间设置了弹性模量居中的中间过渡层，该层在物理性能上构成了一个连续的“缓冲阶梯”，能够有效弥合刚性基体与脆性涂层之间巨大的物理性能差异，当部件受外力或热循环作用时，该过渡层通过其适中的变形能力，平滑地吸收并重新分布界面处的剪切应力和剥离应力，避免了应力在涂层结合面处的急剧集中，从而从根源上消除了涂层因内应力过载而开裂的主要诱因。
Smart Images
Figure CN224786880U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of sheet metal parts technology, specifically to a crack-resistant sheet metal part structure. Background Technology
[0002] Sheet metal parts are widely used in automobiles, home appliances, construction, and server racks due to their excellent machinability and structural strength. To achieve corrosion protection, decoration, or specific surface properties, functional coatings such as paint, powder coatings, and electroplating are usually applied to the surface of the sheet metal substrate.
[0003] However, in actual production and use, the functional coatings adhering to the surface of sheet metal parts are prone to cracking and peeling, seriously affecting the product's appearance quality, protective performance, and service life. The main reasons for this are as follows: 1. Interfacial stress concentration due to material property mismatch. The sheet metal substrate (usually metals such as steel or aluminum) and the external functional coating (usually organic polymers or ceramics) have significant differences in physical properties, especially in elastic modulus and coefficient of thermal expansion. When the component is subjected to external force, deformation, or temperature changes, significant shear stress and peel stress are generated between the two materials. Because traditional processes involve the coating being directly adhered to the smooth substrate surface, this stress cannot be effectively buffered and dispersed, ultimately accumulating at the interface, leading to cracks in the brittle coating or even peeling it off from the substrate.
[0004] 2. Insufficient adhesion between the coating and the substrate. Currently, improving coating adhesion mainly relies on chemical bonding (such as phosphating and passivation) and physical roughening (such as sandblasting). However, chemically treated layers may be unstable, and the roughness formed by sandblasting is random and limited, providing insufficient mechanical bonding force to resist long-term, repeated dynamic stress. Once microcracks appear inside the coating, they can easily propagate into macroscopic cracks at weak points in the interfacial adhesion.
[0005] 3. Localized stress concentration caused by the structure of sheet metal parts themselves. After sheet metal parts are bent or stamped, or when there are large flat areas in the design, certain areas (such as the inside of the bend radius or the center of the flat surface) will form inherent stress concentration zones. When the entire component is subjected to force or heat, the deformation of these areas is greater, and the strain transferred to the coating is also greater, becoming the "disaster area" for coating cracking.
[0006] In summary, existing crack prevention methods mostly focus on optimizing the coating material itself or improving the spraying process, which is a form of "passive defense." These methods fail to fundamentally solve the cracking problem caused by the mismatch between the substrate and coating interface properties and the stress concentration within the sheet metal structure itself.
[0007] Therefore, we propose a crack-resistant sheet metal structure. Utility Model Content
[0008] (a) Technical problems to be solved To address the shortcomings of existing technologies, this utility model provides a crack-resistant sheet metal part structure. By adding an intermediate layer with a stepped transition of elastic modulus between the sheet metal substrate and the coating, setting microstructures to enhance adhesion at the bonding surface, and pre-setting controllable deformation grooves in the stress concentration area of the substrate, it achieves a transformation from "passive crack prevention" to "active energy release." This collaboratively solves the problems of cracking and peeling caused by interfacial stress mismatch, insufficient bonding force, and stress concentration in the substrate, thereby improving the reliability and lifespan of the product and effectively solving the problems in the background technology.
[0009] (II) Technical Solution To achieve the above objectives, the technical solution adopted by this utility model is as follows: a crack-resistant sheet metal part structure, comprising a sheet metal substrate and an external functional coating attached to its outer surface, wherein an intermediate transition layer is provided between the sheet metal substrate and the external functional coating; the elastic modulus of the intermediate transition layer is between that of the sheet metal substrate and the external functional coating; microstructures for increasing the bonding area and adhesion are provided on the bonding surface between the sheet metal substrate and the intermediate transition layer, and on the bonding surface between the intermediate transition layer and the external functional coating; and controllable weak areas for actively releasing stress are provided on the sheet metal substrate.
[0010] Preferably, the microstructure is an array of micropores or pits.
[0011] Preferably, the controllable weak area is a U-shaped groove or V-shaped groove formed on the sheet metal substrate.
[0012] Preferably, the controllable weak area is located at the center of a large plane of the sheet metal substrate or in a stress concentration area.
[0013] Preferably, the groove depth of the controllable weak area is 20% to 30% of the thickness of the sheet metal substrate.
[0014] (III) Beneficial Effects Compared with the prior art, this utility model provides a crack-resistant sheet metal part structure, which has the following beneficial effects: 1. This anti-crack sheet metal structure has an intermediate transition layer with a moderate elastic modulus between the sheet metal substrate and the external functional coating. This layer forms a continuous "buffer step" in terms of physical properties, which can effectively bridge the huge difference in physical properties between the rigid substrate and the brittle coating. When the component is subjected to external force or thermal cycling, the transition layer smoothly absorbs and redistributes the shear stress and peel stress at the interface through its moderate deformation capacity, avoiding the sharp concentration of stress at the coating interface, thereby eliminating the main cause of coating cracking due to internal stress overload from the root.
[0015] 2. This anti-crack sheet metal structure achieves dual reinforcement by setting microstructures on both the sheet metal substrate and the transition layer, as well as on the dual bonding surfaces of the transition layer and the functional coating: First, these microstructures (such as arrayed micropores or pits) significantly increase the actual contact area between layers and provide a strong "rivet"-like mechanical interlocking force, making each layer firmly bonded and effectively resisting delamination; Second, these regular and dense microstructures divide the continuous coating material into numerous small and independent units at the microscopic level, which is equivalent to setting up a microscopic "crack-stopping zone"; Even if local microcracks occur under extreme conditions, their propagation path will be blocked by the boundary of the microstructure, preventing them from penetrating and forming macroscopically visible cracks, thus improving the overall toughness and reliability of the coating.
[0016] 3. This crack-resistant sheet metal structure features a pre-designed controllable weak area (such as a U-shaped or V-shaped groove of a specific depth) on the sheet metal substrate, which is a kind of "active mine clearance" design. As the priority deformation zone of the design, this area can undergo controllable and minute elastic deformation under external loads, thereby actively guiding and releasing the peak strain energy accumulated inside the structure (especially in traditional high-stress areas such as the center of a large-area plane), changing "passive bearing" to "active guidance", fundamentally resolving the stress concentration risk brought about by the structure of the sheet metal itself, and ensuring the safety of the coating on top. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the overall structure of a crack-resistant sheet metal part according to the present invention.
[0018] Figure 2 This is a partial exploded view of the anti-crack sheet metal part structure of this utility model.
[0019] In the diagram: 1. Sheet metal substrate; 2. External functional coating; 3. Intermediate transition layer; 4. Controllable weak area; 5. Microstructure. Detailed Implementation
[0020] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.
[0021] This embodiment provides a crack-resistant sheet metal structure, which aims to fundamentally solve the problem of cracking and peeling of external functional coatings through comprehensive means such as interface stress buffering, bonding strength enhancement and active release of structural stress.
[0022] like Figure 1 and Figure 2 As shown, the present invention provides a crack-resistant sheet metal part structure, the core of which includes a sheet metal substrate 1, an external functional coating 2, an intermediate transition layer 3, a controllable weak area 4, and a microstructure 5.
[0023] Sheet metal base 1 is the main load-bearing component of this structure. It is usually made of metal sheets such as cold-rolled steel sheet, galvanized steel sheet, and aluminum alloy sheet through processes such as stamping and bending. Its shape is determined according to the final product requirements.
[0024] An intermediate transition layer 3 is provided between the sheet metal substrate 1 and the outer functional coating 2. This intermediate transition layer 3 is a critical functional layer, and its material selection is crucial. Preferably, this layer can be made of a polymer material with moderate modulus and high toughness, such as epoxy-modified resin, elastic polyurethane, or specific engineering plastics. Its elastic modulus should be strictly designed to be between that of the sheet metal substrate 1 and the outer functional coating 2, forming a gradient transition from rigid to flexible. This "soft-medium-hard" interlayer modulus gradient can effectively absorb and redistribute the interfacial shear stress and peel stress caused by the difference in thermal expansion coefficients and elastic moduli of the two materials when the component is deformed by external forces or temperature changes, through the elastic deformation of the intermediate transition layer 3, thus avoiding stress concentration directly at the bottom of the brittle outer functional coating 2.
[0025] To enhance the bonding force between layers and prevent interlayer delamination, microstructures 5 are provided on the bonding surfaces of the sheet metal substrate 1 and the intermediate transition layer 3, as well as on the bonding surfaces of the intermediate transition layer 3 and the external functional coating 2, to increase the bonding area and adhesion. In this embodiment, the microstructures 5 are regularly arrayed micropores or pits formed by laser processing, chemical etching, or precision imprinting. The diameter or width of these micropores or pits can be between 10 micrometers and 200 micrometers, and the depth can be between 5 micrometers and 50 micrometers, arranged uniformly in a honeycomb or lattice pattern. They serve a dual purpose: firstly, these microscopic three-dimensional structures significantly increase the physical contact surface area between layers, providing more wetting and anchoring space for the coating material; secondly, when the coating material (including the intermediate transition layer material and the external functional coating material) flows into and solidifies in these micropores or pits, a large number of microscopic "rivets" or "locking" structures are formed, generating a strong mechanical interlocking force, making the interlayer bonding strength exceed that of simple chemical adhesion. Furthermore, these dense microstructures divide the coating into numerous small units at the microscopic level, effectively blocking the propagation path of cracks.
[0026] To further eliminate the risk of coating damage caused by the structural stress of the sheet metal part itself, this utility model provides a controllable weak area 4 on the sheet metal substrate 1 for active stress release. Specifically, the controllable weak area 4 is a U-shaped groove or V-shaped groove formed at a specific location on the sheet metal substrate 1 through precision cutting or etching. Its location is determined through mechanical analysis and is typically located in the center area of a large planar surface on the sheet metal substrate 1 (where bending stress concentration is prone to occur) or in an inherent stress concentration area formed after bending or stamping (such as the inner side of a small radius angle, as shown in the appendix to the specification). Figure 2(As shown). The groove depth of the controllable weak area 4 is precisely designed to be 20% to 30% of the thickness of the sheet metal substrate 1. This depth range is crucial: if the depth is too shallow, the stress release effect will be insignificant; if the depth is too deep, it may excessively weaken the overall strength of the substrate. By pre-setting this groove with precise geometry and depth, a controllable "safety valve" that preferentially induces minute elastic deformation is artificially created in the high-stress area. When the entire component is loaded, this area will first undergo flexible deformation within the design allowable range, thereby actively guiding and releasing the peak strain energy accumulated inside the structure, preventing this energy from being transmitted upward to the coating interface and causing the coating to crack.
[0027] In practice, the sheet metal substrate 1 is first cleaned and pre-treated. Then, an array of microstructures 5 is formed on its surface using techniques such as laser processing. Next, controllable weak areas 4 are machined in the stress concentration areas of the sheet metal substrate 1 with the pre-defined microstructures 5. Then, an intermediate transition layer 3 is applied to the surface of the sheet metal substrate 1 with the microstructures 5 using methods such as spraying, dipping, or scraping. The material fully fills the micropores under capillary action, and after curing, forms a first composite interface that firmly mechanically interlocks with the substrate. After the intermediate transition layer 3 has cured, its outer surface can be lightly polished or the microstructures 5 can be formed again using a similar method. Finally, an external functional coating 2 (such as topcoat, anti-corrosion coating, etc.) is applied to the surface of the intermediate transition layer 3. The external functional coating 2 material also penetrates into the underlying microstructures 5 and cures, forming a second strongly bonded composite interface. This completes a sheet metal structure with excellent crack resistance.
[0028] The working principle of this invention is as follows: When the sheet metal structure is subjected to mechanical loads or thermal cycling, the first line of defense is the controllable weak area 4 on the sheet metal substrate 1, which actively undergoes slight deformation to release the concentrated macroscopic strain energy within the structure. When the remaining deformation stress is transmitted to the coating interface, the intermediate transition layer 3 buffers and redistributes it through its gradient modulus, reducing the stress peak value transmitted to the external functional coating 2. At the same time, the strong mechanical interlocking force provided by the double-layer microstructure 5 firmly locks the layers together, resisting interlayer peeling; its microscopic segmentation function can prevent the propagation of microcracks that may occur inside the coating. The synergistic effect of these three elements comprehensively solves the coating cracking problem from macroscopic structure and interface performance to microscopic bonding.
[0029] It should be noted that, in this document, relational terms such as first and second (number one, number two), etc., are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0030] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.
Claims
1. A crack-resistant sheet metal structure, comprising a sheet metal substrate (1) and an external functional coating (2) attached to its outer surface, characterized in that: An intermediate transition layer (3) is provided between the sheet metal substrate (1) and the external functional coating (2); the elastic modulus of the intermediate transition layer (3) is between that of the sheet metal substrate (1) and the external functional coating (2); microstructures (5) for increasing the bonding area and adhesion are provided on the bonding surface of the sheet metal substrate (1) and the intermediate transition layer (3), as well as on the bonding surface of the intermediate transition layer (3) and the external functional coating (2); a controllable weak area (4) for actively releasing stress is provided on the sheet metal substrate (1).
2. The anti-crack sheet metal part structure according to claim 1, characterized in that: The microstructure (5) is an array of micropores or pits.
3. The anti-crack sheet metal structure according to claim 1 or 2, characterized in that: The controllable weak area (4) is a U-shaped groove or V-shaped groove opened on the sheet metal substrate (1).
4. The anti-crack sheet metal part structure according to claim 3, characterized in that: The controllable weak area (4) is located at the center of a large plane or in a stress concentration area of the sheet metal substrate (1).
5. The anti-crack sheet metal part structure according to claim 4, characterized in that: The groove depth of the controllable weak area (4) is 20% to 30% of the thickness of the sheet metal substrate (1).