Lightweight high-strength foundation pit edge protection net and forming process thereof

Abstract

The application relates to the technical field of building construction safety protection component processing, in particular to a lightweight high-strength foundation pit edge protection net and a forming processing technology thereof. The technology comprises the following steps: according to stress positions, the net is divided into different functional areas; metal plates are subjected to partition punching or punching-expanding forming to form gradient pore diameters and rib widths; the edges of the net are subjected to edge folding and ribbing treatment; a lightweight frame with an embedded groove is prepared and a reinforcing rib is arranged; under a pre-tensioning state, the net joint edge and the reinforcing rib are embedded into the frame groove together and locked through reverse clamping and edge pressing; the tension is released to make the net form a residual tensioning state; finally, partition corrosion prevention and sealing and overall coating are carried out. The application can effectively solve the problems of the existing protection net, such as large weight, insufficient strength after weight reduction, weak connection and easy corrosion, and realizes the unification of lightweight and high strength.

Description

Technical Field

[0001] This application relates to the field of processing technology for safety protection components in building construction, and in particular to a lightweight, high-strength foundation pit edge protection net and its forming and processing technology. Background Technology

[0002] During construction, safety protection of the pit's edge area is crucial to prevent falls, tool slippage, and accidental entry by outsiders. Existing pit edge protection devices typically consist of a frame made of steel pipes or angle steel combined with wire mesh, perforated plates, or welded mesh, and are fixed to the pit edge using posts, connectors, or pins. In production, these devices generally involve first punching or welding metal sheets to form the mesh, then installing the mesh onto the frame using spot welding, screw fixing, or simple slot embedding. Finally, an overall anti-corrosion coating is applied to the surface to meet basic fencing and protection requirements.

[0003] However, in the existing technology, due to the lack of differentiated molding control for stress zones and effective pre-tensioning and locking mechanisms, the protective net often suffers a significant decrease in overall strength when pursuing lightweight and weight reduction. Moreover, during long-term use, the connection between the net and the frame is prone to loosening or tearing, the net surface is prone to bulging and deformation, and the cut and locking areas are susceptible to environmental erosion, affecting the service life. Summary of the Invention

[0004] This application provides a lightweight, high-strength foundation pit edge protection net and its molding and processing technology to solve the above-mentioned problems.

[0005] In a first aspect, this application provides a molding and processing technology for a lightweight, high-strength foundation pit edge protection net, the molding and processing technology including: S1. Based on the stress location of the perimeter protection net of the foundation pit, the net to be processed is divided into the frame connection area, the middle transparent weight reduction area and the lower anti-kick and anti-collision area. S2. The metal sheet blank is punched in sections or expanded after punching, so that the aperture of the frame connection area and the lower anti-kick and anti-collision area is smaller than the aperture of the middle transparent weight reduction area, and the width of the rib between the holes in the frame connection area and the lower anti-kick and anti-collision area is greater than the width of the rib between the holes in the middle transparent weight reduction area. S3. Fold and press the edges of the punched or expanded mesh to form interlocking edges for embedding into the frame, and press the lower anti-kick and anti-collision zone laterally. S4. Prepare a lightweight frame profile with interlocking grooves and undercut edges, and arrange reinforcing ribs on the back side of the mesh or at the corresponding position on the edge of the mesh. S5. Place the wire mesh after edge folding and rib pressing in the tensioning fixture, and apply pre-tension force along the length and height of the wire mesh so that the wire mesh is in a tensioned and flat state before entering the frame. S6. Under the pre-tensioned state, the insertion edge and the end of the reinforcing rib are fed into the fitting groove of the frame profile, and the undercut edge is closed into the fitting groove by rolling, riveting or flanging pressing to lock the mesh edge and the end of the reinforcing rib together in the frame profile. S7. After the frame profile is closed and locked, release the pre-tension force so that the mesh is in a residual tension state inside the frame, and perform shape correction treatment on the frame and the mesh surface. S8. Local anti-corrosion sealing is applied to the punched cuts, interlocking edges, frame fitting grooves, and ribbed areas. Then, the entire protective net is coated with anti-corrosion paint to obtain a lightweight, high-strength foundation pit edge protection net.

[0006] Through the above technical solutions, the partitioned design and gradient aperture forming of S1 to S2 reduce the amount of material used in the middle area while ensuring the lower impact resistance and edge connection strength, thus achieving the basic goal of lightweighting. Secondly, the edge folding and pressing of S3 and the special frame preparation of S4 provide a high-precision interface for subsequent mechanical locking. Furthermore, the pre-tensioning of S5 and the co-pressure fitting of S6 are the core links. Pre-tensioning eliminates the initial defects of the mesh, while co-pressure locking establishes an integrated rigid connection of frame, mesh, and ribs under tension, ensuring effective load transfer. Subsequently, the tension release of S7 utilizes the principle of elastic rebound to form a beneficial residual tension state of the mesh within the frame, fundamentally solving the problems of mesh bulging and loosening. Finally, the partitioned anti-corrosion sealing of S8 specifically strengthens the easily corroded parts, making up for the anti-corrosion shortcomings caused by machining. Each step is interconnected, and their combined effect results in a protective net that is lightweight, high-strength, flat, corrosion-resistant, and long-lasting, effectively overcoming the technical defects of existing technologies, such as heavy weight, weak connections, easy deformation, and easy corrosion.

[0007] Optionally, in step S1, the mesh to be processed is further divided into corner connection areas located at the four corners of the mesh and around the connection holes; The border connection area is arranged around the perimeter of the mesh, with a width of 30mm-80mm; The lower anti-kick and anti-collision zone is located at the bottom of the mesh, with a height of 150mm-350mm; The central transparent weight reduction zone is located between the frame connection area and the lower anti-kick and anti-collision zone; The corner connection area is used to form a rounded transition structure or a local flanging reinforcement structure during subsequent punching, folding, or rib-pressing processes.

[0008] Through the above technical solutions, by setting a frame connection area with a width of 30mm-80mm, sufficient contact area and interlocking depth are ensured between the edge of the mesh and the frame profile, providing a reliable anchoring foundation for subsequent pre-tensioning and locking. A lower anti-kick and anti-collision zone with a height of 150mm-350mm precisely covers the main impact sources in the construction scenario, and combined with a small-diameter, large-rib design, forms a high-strength bottom barrier. By establishing corner connection areas at the four corners and around the connection holes, and guiding subsequent processes to form rounded transitions and local flanging reinforcement structures, stress concentration at sharp corners is effectively eliminated, and the initiation and propagation of cracks around the holes are suppressed. Furthermore, the central transparent weight-reduction zone, as the main body connecting the various reinforced areas, reduces the overall weight with the help of the large-diameter weight-reduction design, while maintaining the overall stability of the mesh surface through the constraint of the surrounding high-strength areas. This technical solution of zoning definition, differential processing, and collaborative load-bearing enables the protective net to be lightweight while significantly improving the corner crack resistance, edge locking reliability, and lower impact resistance, thus solving the problem of early failure caused by stress concentration and insufficient local strength in traditional protective nets.

[0009] Optionally, in step S2, the partition punching includes: A first group of holes with a hole diameter of 4mm-12mm and a rib width of 6mm-15mm is punched in the frame connection area; A second set of holes with a diameter of 20mm-60mm and a rib width of 3mm-10mm is punched in the central transparent weight reduction zone; A third set of holes with a diameter of 8mm-25mm and a rib width of 6mm-15mm is punched in the lower anti-kick and anti-collision zone; The hole shapes in the first hole group, the second hole group, and the third hole group are one or more of the following: round hole, oblong hole, rhomboid hole, hexagonal hole, or rounded rectangular hole.

[0010] Through the above technical solution, the small-diameter, wide-rib design of the first hole group ensures the locking reliability of the frame connection area; the large-diameter, narrow-rib design of the second hole group maximizes the weight reduction effect in the middle area; and the medium-diameter, wide-rib design of the third hole group strengthens the impact resistance of the lower area. These three hole groups are spatially arranged in an orderly manner, forming a strong-weak-strong or strong-weak-secondary-strong gradient distribution in rib width parameters, allowing the material to be fully utilized in critical stress areas and removed in non-critical areas. Furthermore, the diverse hole shape selection further enhances the mesh's adaptability to complex loads. This refined punching strategy based on stress zoning not only solves the problem of traditional uniform-diameter mesh failing to balance weight reduction and local strength, but also provides an ideal substrate state for subsequent pre-tensioning and edge-locking processes, resulting in a protective mesh that maintains lightweight while possessing excellent edge tear resistance and overall impact resistance stability.

[0011] Optionally, in step S2, the central transparent weight reduction area is punched and then expanded, with the expansion direction set along the length of the mesh or along a direction that is intersecting with the extension direction of the reinforcing rib. The magnification of the central perspective weight reduction zone is 1.05-1.40; The border connection area is not expanded, or its expansion ratio is less than that of the central perspective weight reduction area; The expansion ratio of the lower anti-kick and impact-resistant zone is less than the expansion ratio of the middle transparent weight-reducing zone.

[0012] Through the aforementioned technical solution, by implementing directional expansion at a ratio of 1.05-1.40 in the central transparent weight-reduction zone, and utilizing the staggered or parallel configuration of the expansion direction and the reinforcing rib direction, the extensibility and energy absorption efficiency of the central part of the mesh are significantly improved, solving the problem of insufficient rigidity caused by simple punching. Simultaneously, the expansion ratio of the frame connection area and the lower anti-kick and impact-resistant area is strictly limited to be lower than that of the central area, ensuring the solid strength of the edge locking parts and the rigidity reserve of the lower impact-resistant area. This zoned and differentiated expansion process allows the protective mesh to withstand enormous tensile forces at the frame locking points while significantly reducing overall weight, and to maintain structural integrity when subjected to impact at the bottom. This effectively avoids the risk of edge tearing or brittle fracture in the center caused by excessive local weight reduction, achieving a perfect balance between lightweight and high strength.

[0013] Optionally, in step S3, the edge-folding and rib-pressing process includes: The edges of the mesh are bent once to form an interlocking edge with a fold width of 8mm-25mm; The interlocking edge is reinforced with secondary ribs to form raised ribs, grooves, or corrugated ribs with a height of 1mm-6mm. The four corners of the wire mesh are pre-punched or pressed to round the corners. Reinforce the area around the connection hole with circumferential ribs or flanges; The transverse reinforcement treatment involves forming shallow corrugated ribs or transverse reinforcing rib grooves extending along the length of the mesh in the lower anti-kick and anti-collision zone.

[0014] Through the above technical solution, the basic interlocking geometry is formed by a single bend, and then microstructural reinforcement is introduced through secondary ribs, which greatly improves the bending stiffness and resistance to local crushing of the interlocking edges. This ensures that the locking force during the snap-fit ​​is evenly distributed rather than concentrated on the fold line, effectively preventing edge tearing. The rounded corners eliminate stress concentration sources, significantly reducing the risk of corner cracking during handling. The annular ribs or flange reinforcement around the connecting holes specifically address the problem of fretting wear at the hoisting and splicing points. The transverse shallow corrugated ribs in the lower anti-kick zone create a continuous load distribution path. These technical features work together to transform the originally weak mesh edges and local areas into high-strength load-bearing units. This not only meets the locking requirements of the interlocking groove but also provides a solid structural foundation for the subsequent co-pressure interlocking of the frame and mesh reinforcement under pre-tension, thus ensuring that the final pit edge protection net has high-reliability frame and mesh connection strength and a long service life.

[0015] Optionally, in step S4, the lightweight frame profile is obtained by roll forming, cold bending, bending or extrusion forming; The frame profile includes an outer frame wall, an inner limiting shoulder, a fitting groove, a buckle edge, and a reinforcing rib receiving groove; The opening width of the fitting groove is 2mm-8mm, and the groove depth is 8mm-25mm; The undercut edge deforms toward the inside of the fitting groove during the pressing process in step S6 to form a mechanical engagement and locking of the insertion edge.

[0016] The aforementioned technical solution, employing various forming methods such as roll forming and cold bending, produces a specialized profile comprising an outer frame wall, inner limiting shoulder, interlocking groove, undercut edge, and reinforcing rib receiving groove. This profile provides a precise geometric carrier for the pre-tensioning and tensioning of the mesh and the co-pressing and interlocking of the frame and mesh ribs. The 2mm-8mm opening width and 8mm-25mm groove depth of the interlocking groove ensure smooth insertion of the interlocking edge while reserving reasonable space for the plastic deformation of the undercut edge, avoiding assembly failure or locking ineffectiveness due to dimensional mismatch. Furthermore, the mechanism of the undercut edge deforming into the groove and engaging the interlocking edge during pressing, combined with the synchronous accommodating of the reinforcing rib receiving groove at the end of the reinforcing rib, creates a tight mechanical unity between the frame, mesh, and reinforcing ribs. This structure not only solves the problems of simple traditional frame structures and low fault tolerance in interlocking, but also replaces spot welding or screw connections with mechanical interlocking and locking, which significantly improves the edge pull-out resistance and overall load-bearing rigidity. Thus, while reducing the weight of the protective net, it ensures its high-strength protective performance and long-life turnover capability under complex working conditions at the edge of the foundation pit.

[0017] Optionally, in step S5, the tensioning fixture includes a fixed clamping end, a movable clamping end, a tensioning mechanism in the length direction, a tensioning mechanism in the height direction, and a frame positioning fixture; When applying pre-tension force to the mesh, the pre-tension elongation rate in the length direction is controlled to be 0.05%-0.50%, and the pre-tension elongation rate in the height direction is controlled to be 0.03%-0.35%. When the mesh is made of steel, the pretension force on one side is 300N-2000N; When the mesh is made of aluminum alloy, the pretension force on one side is 150N-1200N.

[0018] Through the aforementioned technical solution, the coordinated use of the fixed clamping end, the movable clamping end, and the bidirectional tensioning mechanism provides stable two-dimensional force boundary conditions for the mesh. Based on this, by precisely controlling the pre-tension elongation rate in the length and height directions, the abstract concept of tension flatness is transformed into a quantifiable geometric deformation index, ensuring the uniformity and rationality of the residual stress distribution within the mesh. Furthermore, by dynamically adjusting the numerical range of the pre-tension force on one side according to the mesh material, and utilizing the mutual verification mechanism between force value and elongation rate, the risk of overload failure or insufficient tension due to material differences is effectively avoided. This deep coupling of tooling structure and process parameters not only solves the problems of mesh looseness, bulging, and localized stress concentration in traditional processes, but also enables the mesh to spontaneously form a stable residual tension state after tension release. This significantly improves the overall flatness of the protective mesh, its impact resistance, and the precision of subsequent edge-locking processes, laying a solid mechanical foundation for achieving a balance between lightweight and high strength.

[0019] Optionally, in step S6, the rolling, riveting, or flanging pressing method is a multi-pass pressing method, including: The first pressing process initially closes the groove of the frame profile to prevent the insertion edge from coming out of the groove. The second pressing process presses the undercut edge into the rib area of ​​the interlocking edge. The third pressing step causes the undercut edge to simultaneously press the insertion edge and the end of the reinforcing rib; The fourth shaping process corrects the external dimensions, straightness, and groove closure of the frame profile. The reinforcing rib is one or more of the following: a horizontal reinforcing rib, a vertical reinforcing rib, a lower anti-kick reinforcing rib, or a corner short reinforcing rib.

[0020] Through the above technical solution, firstly, the first pressing pass establishes initial spatial constraints, eliminating the risk of macroscopic displacement between components and providing a stable operational foundation for subsequent processes. Based on this, the second pressing pass utilizes the rib features of the interlocking edges to achieve deep mechanical interlocking, solving the technical problem of easy slippage in traditional planar pressing. Furthermore, the third pressing pass incorporates the ends of the reinforcing ribs into the locking system, making the frame, mesh, and reinforcing ribs form a unified force-bearing whole, significantly improving the tear resistance and load transfer efficiency of the edge areas. Finally, the fourth shaping pass eliminates residual deformation from previous processing, ensuring high-precision product delivery. This phased, progressive pressing strategy avoids material cracking or dimensional instability caused by large single deformations. Especially for complex combinations of different materials and rib types, optimal matching can be achieved by adjusting the pressing amount of each pass.

[0021] Optionally, after step S8, a molding quality inspection step is also included; The molding quality inspection steps include at least three of the following: mesh surface flatness inspection, edge locking force inspection, impact deformation inspection, corner crack resistance inspection, and coating integrity inspection; The mesh flatness detection is used to determine the bulge height of the mesh center relative to the frame plane; The edge locking force detection is used to determine whether the insertion edge has come out of the fitting groove under tension. The impact deformation detection is used to determine the maximum deflection and recovery rate of the protective net after it has been subjected to an impact; Based on the test results, the lightweight high-strength foundation pit edge protection net is classified into ordinary perimeter type, reinforced perimeter type, or deep foundation pit reinforced type.

[0022] Through the above technical solutions, the mesh flatness test corresponds to the pre-tensioning process, ensuring the initial morphological stability of the mesh; the edge locking force test corresponds to the frame mesh reinforcement co-pressure embedding process, ensuring the static bearing limit of the connection structure; the impact deformation test is coupled with the gradual aperture and residual tension state, verifying the dynamic energy absorption characteristics of the protective net; the corner crack resistance test corresponds to the local edge reinforcement process, confirming the fatigue life of weak areas; and the coating integrity test is matched with the partitioned anti-corrosion sealing process, ensuring the corrosion resistance performance for long-term service. Based on this, the products are scientifically classified into ordinary perimeter type, reinforced perimeter type, and deep foundation pit reinforced type according to multi-dimensional test data. This not only provides a quantitative basis for product quality but also provides clear guidance for selection under different construction scenarios, thereby significantly improving the overall safety, reliability, and market adaptability of the foundation pit edge protection net.

[0023] Secondly, this application provides a lightweight, high-strength foundation pit edge protection net, including a lightweight frame, a gradient aperture mesh, reinforcing ribs, and an anti-corrosion coating; The lightweight frame surrounds the gradient aperture mesh, and the lightweight frame is provided with a fitting groove for accommodating the edge of the mesh and an undercut pressing edge that closes toward the fitting groove. The gradient aperture mesh includes a frame connection area, a middle transparent weight reduction area, and a lower anti-kick and anti-collision area. The aperture of the frame connection area and the lower anti-kick and anti-collision area is smaller than the aperture of the middle transparent weight reduction area, and the width of the inter-aperture ribs in the frame connection area and the lower anti-kick and anti-collision area is greater than the width of the inter-aperture ribs in the middle transparent weight reduction area. The gradient aperture mesh has interlocking edges formed by folded edge ribs around its perimeter. The interlocking edges are embedded in the fitting grooves of the lightweight frame and are pressed and locked by the undercut edge. The reinforcing rib is disposed on the back side or edge of the tapered mesh, and the end of the reinforcing rib and the insertion edge are embedded together in the fitting groove and locked together by the undercut pressing edge. The lower anti-kick and anti-collision zone is provided with a transverse pressure rib structure, and the gradient aperture mesh is in a tensioned and flat state within the lightweight frame. The anti-corrosion coating covers the lightweight frame, the gradient aperture mesh, the interlocking edge, the fitting groove, and the surface of the transverse rib structure.

[0024] Through the above technical solution, the use of a gradient aperture mesh design allows for a larger inter-pore rib width in the frame connection area and the lower anti-kick and impact zone to withstand high stress, while the central transparent weight-reducing zone uses a large aperture to reduce weight. Therefore, while significantly reducing the overall weight of the protective net, the strength and impact resistance of key stress areas are guaranteed, resolving the contradiction between lightweight and high strength. Furthermore, the lightweight frame with undercut edges, and the embedding of the mesh's interlocking edges and the ends of the reinforcing ribs into the fitting grooves for co-pressure locking, form a continuous mechanical interlocking structure. This significantly improves the pull-out resistance and shear resistance at the edge connections, avoiding the loosening problems associated with traditional welding or screw connections. Because the mesh is stretched and flat within the frame, residual tensile stress offsets deformation caused by processing and assembly, ensuring the mesh surface remains flat and eliminating bulges and slack, thus improving the appearance quality and protective consistency of the protective net. The transverse rib structure in the lower anti-kick and impact zone enhances the lateral stiffness and bending resistance of this area, effectively resisting localized deformation caused by kicks and tool impacts. The anti-corrosion coating fully covers all key areas, including the interlocking edges, fitting grooves, and rib structures, with particular focus on protecting processing cuts and stress concentration areas, significantly improving the corrosion resistance and service life of the protective net in harsh construction environments such as dampness and dust. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A process flow diagram illustrating the molding and processing of a lightweight, high-strength foundation pit edge protection net, provided in one embodiment of this application; Figure 2 This is a front view schematic diagram of the overall structure of a lightweight, high-strength foundation pit edge protection net provided in an embodiment of this application; Figure 3 This is a side view of the overall structure of a lightweight, high-strength foundation pit edge protection net provided in an embodiment of this application; Figure 4 for Figure 3 A magnified view of the locking structure of the frame at point A in the middle. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0029] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0030] Example 1 See Figure 1 The present application provides a flowchart of the molding and processing technology for a lightweight, high-strength foundation pit edge protection net, which includes the following steps: Step 1: Based on the stress location of the perimeter protection netting of the foundation pit, divide the netting to be processed into the frame connection area, the middle transparent weight reduction area, and the lower anti-kick and anti-collision area; The mesh to be processed refers to the metal sheet blank used to make the main body of the protective net. The material can be high-strength steel plate, galvanized steel plate, or aluminum-magnesium alloy plate, with a thickness typically between 0.8mm and 1.8mm. The division is based on the actual stress distribution of the protective net after installation: the frame connection area is located around the perimeter of the mesh, mainly used for subsequent mechanical locking with the frame profiles, requiring high material density to withstand the locking force; the central transparent weight-reduction area is located in the middle of the mesh body, primarily responsible for visual transparency and experiencing relatively less stress, making it the core area for weight reduction; the lower kick and impact-resistant area is located at the bottom of the mesh, typically 150mm to 350mm high. This area is susceptible to kicks from construction workers, impacts from dropped tools, and small stones, thus requiring higher impact rigidity. This zoning design allows different areas to be matched with different aperture and rib width parameters, achieving an optimized material layout that maintains strength in dangerous areas and reduces weight in non-dangerous areas.

[0031] Step 2: Punch or expand the metal sheet blank in sections so that the hole diameter formed in the frame connection area and the lower anti-kick and anti-collision area is smaller than the hole diameter formed in the middle transparent weight reduction area, and the width of the rib between the holes in the frame connection area and the lower anti-kick and anti-collision area is greater than the width of the rib between the holes in the middle transparent weight reduction area. Partial punching refers to the process of punching holes of different specifications in different areas using a stamping die. Specifically, for the frame connection area and the lower anti-kick and anti-collision area, holes with smaller diameters (e.g., 4mm-25mm) and larger inter-hole rib widths (e.g., 6mm-15mm) are punched to ensure that this area has sufficient solid material to resist tearing and impact. For the central transparent weight reduction area, holes with larger diameters (e.g., 20mm-60mm) and smaller inter-hole rib widths (e.g., 3mm-10mm) are punched to minimize the weight of the mesh. Post-punching expansion forming refers to stretching and expanding the holes in a specific direction (e.g., the length direction) after punching in the central transparent weight reduction area, turning the round holes into rhomboid or oblong holes, further increasing the opening ratio and improving material utilization. The expansion ratio can be controlled between 1.05 and 1.40. For example, when processing the central transparent weight reduction zone, a 20mm diameter circular hole is first punched, and then expanded laterally by 1.2 times to form a diamond-shaped mesh with higher permeability, while the frame connection area remains unexpanded or slightly expanded. Through this differentiated forming method, the protective netting achieves an overall weight reduction of more than 30% while retaining high structural strength in key stress-bearing parts, effectively avoiding a decrease in overall rigidity caused by uniform thinning.

[0032] Step 3: Fold and press the edges of the punched or expanded mesh to form interlocking edges for embedding into the frame, and press the lower anti-kick and anti-collision area laterally. The edge-folding and rib-pressing treatment involves bending the edges of the mesh once or multiple times to form interlocking edges with a width of 8mm-25mm. Raised ribs, grooves, or corrugated ribs with a height of 1mm-6mm are then pressed onto these interlocking edges to increase the moment of inertia of the edge section and improve tear resistance. The transverse rib-pressing treatment refers to pressing shallow corrugated ribs or transverse reinforcing rib grooves along the length of the mesh in the lower kick-resistant and impact-resistant zone, creating a corrugated board-like structural effect that significantly improves the bending stiffness and resistance to localized indentations in this area. This structure not only provides a reliable mechanical interlocking foundation for subsequent frame embedding but also, through geometric reinforcement, makes the lower area less prone to plastic deformation when subjected to kicks or tool impacts, thereby extending the service life of the protective mesh.

[0033] Step 4: Prepare a lightweight frame profile with interlocking grooves and undercut edges, and arrange reinforcing ribs on the back side of the mesh or at the corresponding position on the edge of the mesh; The lightweight frame profile is a thin-walled metal profile produced by roll forming, cold bending, or extrusion forming. Its cross-sectional structure includes an outer frame wall, an inner limiting shoulder, a fitting groove to accommodate the edge of the mesh, and an inwardly deformable undercut edge. The opening width of the fitting groove is typically 2mm-8mm, and the groove depth is 8mm-25mm, designed to receive the interlocking edges formed in the preceding steps. Reinforcing ribs can refer to strip-shaped reinforcing members independent of the mesh, such as cap-shaped steel strips, square tubes, or angle aluminum. Their placement can be set in the middle or edge of the back side of the mesh according to stress requirements, to share the load borne by the mesh. This step constructs the skeleton system of the protective netting, laying the physical foundation for the subsequent integrated load-bearing capacity of the frame and mesh through the structural strength of the profile itself and the auxiliary support of the reinforcing ribs.

[0034] Step 5: Place the wire mesh after edge folding and rib pressing in the tensioning fixture, and apply pre-tension force along the length and height of the wire mesh to make the wire mesh in a tensioned and flat state before entering the frame; The tensioning fixture includes a fixed clamping end, a movable clamping end, and tensioning mechanisms acting in the length and height directions respectively. Applying pre-tension force can be achieved by controlling the displacement of the movable clamping end or through feedback from a tension sensor, causing the mesh to produce a small elastic elongation in two orthogonal directions. The pre-tension elongation rate in the length direction is controlled at 0.05%-0.50%, and the pre-tension elongation rate in the height direction is controlled at 0.03%-0.35%. For steel mesh, the pre-tension force on one side can be set to 300N-2000N; for aluminum alloy mesh, it is set to 150N-1200N. This step aims to eliminate uneven internal stress generated in the mesh during punching and transportation, ensuring that the mesh reaches ideal flatness before entering the frame, creating preconditions for the subsequent formation of a uniform residual tension state.

[0035] Step 6: Under the pre-tensioned state, insert the interlocking edge and the end of the reinforcing rib into the fitting groove of the frame profile, and close the undercut edge into the fitting groove by rolling, riveting or flanging pressing to lock the edge of the mesh and the end of the reinforcing rib into the frame profile. The "simultaneous insertion" refers to simultaneously inserting the mesh's interlocking edges and the ends of the reinforcing ribs into the deep fitting grooves of the frame profile while maintaining tension on the mesh. Rolling, riveting, or flanging pressing methods involve applying pressure to the undercut edges of the frame using a multi-pass forming die, causing plastic deformation and bending them inwards into the fitting groove, thus tightly pressing the interlocking edges and the ends of the reinforcing ribs. For example, a four-pass rolling process can be used: the first pass initially closes the groove opening to prevent slippage; the second pass presses the undercut edge into the rib area of ​​the interlocking edge; the third pass simultaneously presses the ends of the reinforcing ribs; and the fourth pass performs shaping and correction. This step achieves a mechanical interlocking connection between the frame, mesh, and ribs, changing the traditional connection method that relies on spot welding or screws. This allows impact loads to be transmitted to the frame through multiple paths via the interlocking edges and reinforcing ribs, significantly improving the fatigue resistance and pull-out resistance of the connection joints.

[0036] Step 7: After the frame profile is closed and locked, release the pre-tension force so that the mesh is in a residual tension state inside the frame, and perform shape correction treatment on the frame and the mesh surface; Releasing pre-tension force refers to releasing the clamping constraints of the tensioning fixture. Since the edges of the mesh are firmly locked by the frame, the mesh cannot fully shrink back to its original size under the action of elastic restoring force, thus forming uniform residual tensile stress inside the frame, i.e., residual tension. Shaping treatment refers to straightening the components after edge locking, verifying the diagonals, and slightly flattening any local bulges on the mesh surface to ensure the dimensional accuracy of the finished product. For example, when 0.2% of the pre-tension elongation is released, the central area of ​​the mesh remains taut due to tension, effectively counteracting the sagging tendency caused by its own weight. This step utilizes the principle of material elasticity to ensure that the mesh remains flat throughout long-term use, avoiding the loosening and bulging phenomena common in traditional protective nets, and significantly improving the appearance quality and impact resistance of the protective net.

[0037] Step 8: Perform localized anti-corrosion sealing on the punched cuts, interlocking edges, frame fitting grooves, and ribbed areas, and then apply anti-corrosion coating to the entire protective netting to obtain a lightweight, high-strength foundation pit edge protection netting.

[0038] Localized anti-corrosion sealing refers to the application of zinc-rich primer or penetrating anti-corrosion sealant to the burrs and cuts from punching, micro-cracks formed by folding, gaps in the edge fitting grooves, and stress concentration points in the rib area, forming a first dense protective layer with a thickness of 10μm-40μm. Overall anti-corrosion coating refers to electrostatic powder coating, dip coating, or painting on the entire surface of the protective mesh after localized sealing and curing, forming a topcoat with a thickness of 60μm-150μm. For example, a zinc-rich primer is first applied to all punched edges and locking grooves of the mesh to fill micro-defects, followed by overall green powder coating and high-temperature curing. This dual anti-corrosion strategy of localized key sealing and overall comprehensive coverage effectively blocks the path of moisture and corrosive media intrusion from weak points, solving the problems of easy rusting and short lifespan of traditional protective mesh cuts, enabling it to adapt to the harsh rain and mud environment of the foundation pit site, and significantly extending the product's turnover period.

[0039] Example 2 In another alternative embodiment, the method of partitioning the mesh to be processed in step S1 is further refined.

[0040] Step 1: In step S1, the mesh to be processed is further divided into corner connection areas located at the four corners of the mesh and around the connection holes; The corner connection zone refers to the four vertices of the mesh to be processed, as well as the area around the connection holes used for hoisting, stacking, or installation. This zone is designed to address the cracking and failure problems in existing protective mesh caused by stress concentration at the corners or fretting wear at the edges of the connection holes during repeated handling, stacking, and installation. The specific location of the corner connection zone is determined based on the geometric center of the mesh and the pre-defined connection hole positions, covering the entire material area required for the subsequent rounded corner transition structure or local flanging reinforcement structure. For example, when the mesh size is 2000mm × 1200mm, the corner connection zone can be defined as a square area 100mm-150mm from each side of the mesh vertex, and an annular area extending outwards from the center of the connection hole by 20mm-40mm. By pre-delineating this zone, a rounded corner pre-punching process can be used instead of sharp corner punching in the subsequent punching process, or an annular flanging can be implemented around the connection holes in the folding and ribbing process, thereby transforming potential crack initiation sources into stress dispersion areas. This step, through the pre-definition of geometric partitions, provides clear processing boundaries for the subsequent formation of rounded corner transition structures or local flanging reinforcement structures, effectively improving the fatigue life of the corners of the protective mesh and the reliability of the connecting holes for repeated use.

[0041] Step 2: The border connection area is arranged around the perimeter of the mesh, with a width of 30mm-80mm; The frame connection area refers to a strip-shaped region that extends continuously along the four edges of the mesh to be processed. Its main function is to provide sufficient material area to form the interlocking edge and ensure a stable mechanical engagement with the frame profile during the subsequent edge-locking process. The width of this area is set according to the depth of the interlocking groove of the frame profile and the deformation of the undercut edge, specifically ranging from 30mm to 80mm. If the width is too small (less than 30mm), the interlocking edge will not be deeply embedded and will be unable to resist pull-out forces; if the width is too large (greater than 80mm), it will lead to material waste and unnecessary weight increase. For example, for a frame profile with a wall thickness of 1.5mm, the width of the frame connection area can preferably be set to 50mm to ensure that the interlocking edge formed after folding can completely fill the interlocking groove and leave an appropriate amount of pressing redundancy. This width parameter, in conjunction with the folding width in step S3 and the locking method in step S6, ensures that the edge of the mesh will not come out of the frame when subjected to impact loads. The width range defined by this step achieves an optimal balance between edge strength and material lightweighting, providing a fundamental guarantee for the structural integrity of the entire protective net.

[0042] Step 3: The lower anti-kick and impact zone is located at the bottom of the mesh panel, with a height of 150mm-350mm; The lower kick-resistant and impact-resistant zone refers to the functional area located at the bottom of the mesh to be processed, specifically designed to resist kicks, tool slips, and impacts from small objects. The height of this zone is determined based on ergonomic data and the height distribution of common impact sources on construction sites, specifically ranging from 150mm to 350mm. This height range covers the typical height of an unintentional kick by a construction worker (approximately 120mm) and the maximum impact range of an accidental slip of a small handheld tool (usually not exceeding 300mm). For example, in deep foundation pit construction scenarios, the height of the lower kick-resistant and impact-resistant zone can be set to 250mm, employing a punching strategy with smaller apertures and larger rib widths within this area, combined with transverse rib reinforcement to form a high-density impact barrier. This height setting, in conjunction with the zoned punching parameters in step S2 and the transverse rib reinforcement in step S3, ensures that the lower part of the protective mesh has significantly higher impact stiffness than the middle part. This step, through precise height limitation, achieves targeted reinforcement of high-risk impact areas, avoiding weight redundancy caused by a full-area high-strength design.

[0043] Step 4: The central perspective weight reduction zone is located between the frame connection area and the lower anti-kick and anti-collision zone; The central transparent weight-reduction zone refers to the main area filled inside the frame connection area and located above the lower anti-kick and anti-collision zone. This area is defined by the inner boundary of the frame connection area and the upper boundary of the lower anti-kick and anti-collision zone, occupying the majority of the visible area of ​​the mesh. The main function of the central transparent weight-reduction zone is to minimize the mesh's weight while maintaining good visibility, while ensuring overall structural stability, through a hole design with a larger aperture and smaller rib width. For example, when the width of the frame connection area is 50mm and the height of the lower anti-kick and anti-collision zone is 200mm, the central transparent weight-reduction zone automatically forms in the remaining central area of ​​the mesh, and oblong holes with a diameter of 40mm can be punched in this area to achieve weight reduction. The layout of this area complements the enclosure function of the frame connection area and the anti-collision function of the lower anti-kick and anti-collision zone, creating a gradient stress structure that is strong on the outside and light on the inside, dense at the bottom and sparse at the top. This step clarifies the spatial logic relationship of each functional area, ensuring that the protective mesh achieves the goal of lightweighting while meeting safety regulations.

[0044] Step 5: The corner connection area is used to form a rounded transition structure or a local flanging reinforcement structure during subsequent punching, folding, or rib pressing processes.

[0045] The rounded corner transition structure refers to a non-sharp-angled arc edge formed by die stamping at the apex of the corner connection area, used to eliminate stress concentration caused by right-angle cutting. The local flanging reinforcement structure refers to annular protrusions or depressions formed around the connection holes by flanging, used to increase the thickness and rigidity of the plate around the holes. The existence of the corner connection area allows subsequent processes to perform differentiated processing on specific locations: in the punching stage, a large rounded corner die is used in this area to avoid the initiation of sharp-corner cracks; in the folding stage, special rounded bending treatment is applied to the corners to prevent cracking at the folds; in the rib-pressing stage, annular ribs are applied around the connection holes to suppress fretting wear. For example, around the lifting hole, annular ribs with a height of 3mm can be pressed using the material properties of the corner connection area, increasing the local load-bearing capacity at that location by more than 50%. This correspondence between structure and function makes the corner connection area a key part for improving the service life of the protective net. This step, by clarifying the functional use of the corner connection area, transforms potential weak points into structural reinforcement points, significantly improving the protective net's resistance to failure in complex construction environments.

[0046] Example 3 One possible implementation also includes performing fine-grained zone punching on the metal sheet blank to form a hole group structure with different mechanical properties.

[0047] Step 1: Punch the first set of holes in the frame connection area with a hole diameter of 4mm-12mm and a rib width of 6mm-15mm between holes; The first hole group refers to an array of perforations distributed around the perimeter of the mesh for subsequent fitting and locking with the frame profile. The hole diameter of this first hole group is set to 4mm to 12mm, and the rib width between holes is set to 6mm to 15mm. The smaller hole diameter combined with the wider rib width aims to increase the material density and section modulus of the frame connection area, ensuring sufficient shear strength and tear resistance at the mesh edge during subsequent edge folding, pressing, and undercutting processes, preventing edge cracking due to localized stress concentration. For example, when using a 1.2mm thick galvanized steel sheet, 8mm diameter holes with a 10mm rib width can be punched as the first hole group. In this case, the rib width is approximately 1.25 times the hole diameter, effectively resisting the radial extrusion force generated during rolling and locking. This layout of small hole diameter and wide rib width allows the frame connection area to maintain connection strength close to that of a solid sheet while reducing weight slightly, providing a reliable load-bearing carrier for subsequent frame-mesh-rib co-pressing and fitting.

[0048] Step 2: Punch a second set of holes with a diameter of 20mm-60mm and a rib width of 3mm-10mm in the central perspective weight reduction zone; The second perforation group refers to a large-diameter perforated array distributed in the central area of ​​the mesh body to achieve lightweighting and visual transparency. The diameter of this second perforation group is set between 20mm and 60mm, and the width of the ribs between the holes is set between 3mm and 10mm. The larger diameter significantly reduces the amount of sheet material used per unit area, thus achieving overall weight reduction, while the limited rib width ensures that the mesh surface does not buckle and become unstable under pre-tension. For example, for a protective mesh with a height of 1200mm, the central transparent weight-reducing area can be punched with oblong holes of 45mm major diameter and 20mm minor diameter as the second perforation group, with the rib width between the holes controlled at around 5mm. This configuration can reduce the weight of this area by about 40% while ensuring the rigidity of the mesh surface. Through this design of large diameter and narrow rib width, the second perforation group forms a clear gradient difference from the first perforation group, which not only meets the needs of construction personnel to observe the internal conditions of the foundation pit, but also avoids the softening of the mesh surface and the decrease in impact resistance caused by excessive weight reduction.

[0049] Step 3: Punch a third set of holes with a diameter of 8mm-25mm and a rib width of 6mm-15mm between the holes in the lower anti-kick and anti-collision zone; The third perforation group refers to a transitional array of perforations distributed within a specific height range at the bottom of the mesh, specifically designed to resist kicks, tool impacts, and small object impacts. The diameter of this third perforation group is set between 8mm and 25mm, and the rib width between the perforations is set between 6mm and 15mm. Its diameter falls between the first and second perforation groups, while the rib width is comparable to the first group. This parameter setting allows the lower anti-kick and impact-resistant zone to possess both a certain degree of transparency and high impact rigidity. For example, in an area with a lower height of 200mm, hexagonal holes with a side length of 15mm can be punched as the third perforation group, with an rib width of 8mm. The hexagonal structure helps to evenly distribute point impact loads to the surrounding ribs. The synergy between this third perforation group and the first perforation group in terms of rib width parameters ensures the continuity of mechanical properties at the connection between the lower part of the protective mesh and the frame, preventing inconsistent damage patterns such as excessive deformation at the bottom while the edges remain intact, or vice versa, during lateral impacts.

[0050] Step 4: The hole shapes in the first hole group, the second hole group, and the third hole group are one or more of the following: round hole, oblong hole, rhomboid hole, hexagonal hole, or rounded rectangular hole.

[0051] Here, hole shape refers to the geometric contour shape of each individual perforation in each hole group. Different hole shapes correspond to different stress distribution characteristics and molding process adaptability. Circular holes are the simplest to process and are suitable for general scenarios; when oblong holes and rounded rectangular holes are arranged along the length of the mesh, they can significantly improve the tensile strength of the mesh under longitudinal tension and reduce stress concentration at sharp corners; rhomboid holes and hexagonal holes can provide better in-plane isotropic stiffness and are suitable for withstanding multi-directional impact loads. For example, in deep foundation pit scenarios requiring extremely high tensile strength, the second hole group in the middle can be designed as rounded rectangular holes extending horizontally, while the third hole group at the bottom can be designed as hexagonal holes to enhance impact resistance. By flexibly selecting or combining the above hole shapes, this application can customize the mechanical performance requirements of the protective mesh for different construction environments, further optimizing the balance between lightweight and high strength.

[0052] Example 4 In one optional embodiment, the method further includes a specific step of punching and expanding the central perspective weight reduction zone.

[0053] Step 1: In step S2, the central transparent weight reduction area is punched and then expanded to form a shape. The expansion direction is set along the length of the mesh or along a direction that is intersecting with the extension direction of the reinforcing rib. Post-punching expansion forming refers to the process of applying directional tensile force to the mesh blank using an expansion die after the basic punching process, causing plastic flow in the metal around the holes and expanding the initial hole shape (such as round or oblong holes) into a rhomboid, elliptical, or elongated circle. The choice of expansion direction directly determines the microscopic grain orientation and macroscopic load-bearing capacity of the ribs. When the expansion direction is set along the length of the mesh, the ribs are elongated and arranged longitudinally, which can significantly improve the anti-sagging ability and longitudinal impact toughness of the protective mesh in a vertically suspended state. When the expansion direction is set in a direction that intersects with the extension direction of the reinforcing ribs, for example, the reinforcing ribs are arranged laterally and the expansion direction is longitudinal, or the reinforcing ribs are arranged obliquely, this interlaced texture structure can form a weaving-like mechanical effect, effectively dispersing local impact loads and preventing cracks from propagating rapidly in a single direction. For example, in scenarios such as subway pits where lateral impact resistance is emphasized, the expansion direction can be set to intersect with the transverse reinforcing ribs at a 90-degree angle, so that the ribs formed by longitudinal stretching provide an additional yield plateau when subjected to lateral impact, thereby absorbing more energy. Through this directional expansion, the central perspective weight reduction zone achieves further weight reduction through increased aperture without increasing the thickness of the sheet material. At the same time, the work hardening effect is used to improve the ductility and energy absorption capacity of the ribs.

[0054] Step 2: The expansion ratio of the central fluoroscopic weight loss zone is 1.05-1.40; The expansion ratio refers to the ratio of the expanded mesh area (or characteristic dimension) to the original mesh area (or characteristic dimension), reflecting the degree of aperture expansion and the extent of rib thinning and stretching. This parameter range is set based on a balance between weight reduction and structural integrity: if the expansion ratio is less than 1.05, the aperture change is minimal, making it impossible to effectively utilize metal plastic flow to improve the rib orientation strength, resulting in minimal weight reduction and energy absorption gains; if the expansion ratio is greater than 1.40, the ribs become excessively thin, making them prone to necking or even breakage during expansion, leading to mesh damage or premature failure under subsequent stress. In this embodiment, the expansion ratio is controlled between 1.05 and 1.40, preferably between 1.15 and 1.30. For example, for a mesh initially punched with 20mm diameter holes, after expansion at a ratio of 1.20, the holes are elongated in the expansion direction, increasing the equivalent aperture. This results in an additional 8%-15% reduction in the overall weight of the mesh, while simultaneously increasing impact energy absorption capacity by over 25%. This expansion range ensures that the central transparent weight reduction zone maximizes lightweighting while maintaining sufficient connection strength and tear resistance.

[0055] Step 3: The border connection area is not expanded, or its expansion ratio is less than that of the central perspective weight reduction area; The frame connection area is a crucial region for the mechanical interlocking and locking of the mesh and the lightweight frame profile. Its structural stability directly determines the edge pull-out resistance of the entire protective mesh. This area is either not expanded or only expanded at a low ratio to preserve the original thickness of the metal sheet and the high inter-rib density. If the frame connection area uses the same high expansion ratio as the central area, the ribs at the interlocking edge will become excessively thin. During the subsequent undercutting and pressing closure process in step S6, the fragile ribs are easily crushed or develop micro-cracks, significantly reducing the locking strength. For example, when the expansion ratio of the central transparent weight-reducing area is 1.25, the expansion ratio of the frame connection area can be set to 0 (i.e., no expansion) or below 1.05 to ensure that the inter-hole rib width in this area remains at a relatively high level of 6mm-15mm, providing a solid support base for the undercutting and pressing, and preventing the mesh from detaching from the interlocking groove due to excessive edge deformation.

[0056] Step 4: The expansion ratio of the lower anti-kick and impact zone is less than the expansion ratio of the middle transparent weight reduction zone.

[0057] The lower kick-resistant and impact-resistant zone is the part of the protective netting most vulnerable to kicks, tool impacts, and small object slips during construction. It requires high out-of-plane stiffness and resistance to localized deformation. Limiting the expansion ratio of this zone to be lower than that of the middle zone ensures both weight reduction and high material density and rib section modulus. If the expansion ratio of the lower zone is too high, while weight reduction is possible, it reduces its resistance to impacts from hard objects, making it prone to permanent bulges or perforations under point loads. Through differentiated control, the expansion ratio of the lower kick-resistant and impact-resistant zone is positioned between that of the frame connection zone and the middle transparent weight-reduction zone. For example, when the expansion ratio of the middle zone is 1.30, the expansion ratio of the lower zone can be controlled between 1.05 and 1.15. This gradient expansion strategy ensures that the lower zone of the protective netting possesses both appropriate extensibility to buffer impact energy and sufficient stiffness to prevent excessive deformation, thus achieving the design goal of maintaining strength in hazardous areas and reducing weight in non-hazardous areas.

[0058] Example 5 One possible implementation method also includes fine edge folding and rib pressing of the mesh to solve the problems of insufficient edge rigidity of traditional single edge folding, which makes it easy to warp, detach or tear under inverted pressing and repeated impact.

[0059] Step 1: Bend the four edges of the mesh once to form an interlocking edge with a fold width of 8mm-25mm; In this context, a single bend refers to the operation of folding the edges of the punched or expanded mesh sheet 90° to 135° towards the back or inward along a preset bending line using a bending die or roller equipment. The interlocking edge is a crucial connection point for subsequent embedding into the frame profile's fitting groove; its width directly determines the contact area with the frame and the reliability of the locking mechanism. The folded edge width is set at 8mm-25mm, a matching design based on the groove depth (typically 8mm-25mm): if the width is less than 8mm, the effective engagement length of the interlocking edge within the groove is insufficient, resulting in low pull-out resistance; if the width is greater than 25mm, interference due to material accumulation during subsequent rolling closure can increase processing difficulty and potentially cause frame deformation. For example, for a 1.2mm thick high-strength steel mesh sheet, the width of the single bend can be controlled at 15mm. This width ensures sufficient embedding depth while also providing ample deformation space for subsequent secondary pressing. The interlocking edge formed through this step not only provides a basic geometric interlocking shape, but also initially improves the moment of inertia of the edge section, laying the foundation for subsequent bearing of tension and impact loads.

[0060] Step 2: Apply secondary reinforcement to the interlocking edge to form raised ribs, grooves, or corrugated ribs with a height of 1mm-6mm. The secondary rib formation involves applying localized pressure to the surface of the interlocking edge after a single bend using a punch or roller, causing plastic deformation and creating raised or recessed microstructures. The raised ribs, grooves, or corrugated ribs significantly increase the flexural section modulus of the interlocking edge, preventing localized crushing or buckling during the frame's inverted pressing process. A rib height of 1mm-6mm is a mechanically validated optimized range: when the height is below 1mm, the strengthening effect is weak and cannot effectively disperse the locking stress; when the height exceeds 6mm, the stress concentration at the root of the bend is too high, easily leading to cracks or even breakage at the bend. For example, a semi-circular raised rib with a height of 2.5mm can be pressed at the center of a 15mm wide interlocking edge, or two corrugated ribs spaced 5mm apart can be pressed near the free end. Through the synergistic effect of the primary bend and the secondary rib formation, the interlocking edge possesses both the geometric conditions for embedding into the frame and the structural strength to resist localized crushing.

[0061] Step 3: Round the four corners of the wire mesh by pre-punching or pressing. Rounded corner pre-punching refers to directly processing the four corners into rounded shapes during the mesh cutting or punching stage; rounded corner pressing refers to using a special mold to press the right-angle corners after folding, transforming them into a rounded corner structure. This step aims to eliminate the stress concentration peak caused by theoretical right angles (90°). During the handling, stacking, and installation of protective netting, the four corners are the areas most prone to collisions and cracks, and sharp right angles can cause cracks to propagate rapidly. By optimizing the four corners into a rounded transition structure of R3-R10, the bending stress at the four corners can be reduced by about 60%, significantly improving the crack resistance of the corners. For example, pre-punching rounded notches with a radius of 5mm at each of the four corners of the mesh, or radially forging the corners after folding, allows the metal fibers to be continuously distributed along the arc direction. As a result, the four corners of the mesh can effectively avoid brittle fracture when subjected to drop impacts or hoisting tension, increasing the handling drop pass rate from the conventional 70% to 99%.

[0062] Step 4: Reinforce the area around the connection hole with circumferential ribs or flanges; The connecting holes refer to pre-drilled holes used for splicing protective netting, fixing to posts, or hoisting. The annular reinforcing rib refers to a raised reinforcing ring pressed around the connecting hole; the flanged reinforcement refers to folding the edge of the connecting hole outwards or inwards to form a rolled edge structure. This step aims to suppress the risk of tearing of the connecting holes under long-term fretting wear or high tensile force. By forming a raised reinforcing structure around the hole, the effective thickness and load-bearing area of ​​the hole wall are increased, more than doubling the tensile strength around the hole, meeting the requirements of more than 1000 hoisting cycles. For example, for a 10mm diameter hoisting hole, a 3mm wide and 1.5mm high annular rib can be pressed around it, or the edge of the hole can be folded outwards at 90° to form a 2mm high vertical edge. This localized reinforcement structure, combined with the gradually changing aperture design of the main mesh, ensures that the reliability of the connection at key stress points is not affected while reducing weight.

[0063] Among them, the transverse rib treatment is to form shallow corrugated ribs or transverse reinforcing rib grooves extending along the length of the mesh in the lower anti-kick and anti-collision zone. Specifically, for the lower anti-kick and impact-resistant zone defined in the above embodiments, this step further implements transverse ribbed treatment. This treatment involves continuously or intermittently pressing shallow corrugated undulating structures or elongated reinforcing grooves along the length of the lower area of ​​the mesh (typically 150mm-350mm in height). The function of the shallow corrugated ribs or reinforcing grooves is to form a continuous stiffness gradient in this high-frequency impact area. When subjected to impacts from kicks, tool collisions, or small objects slipping, the concentrated point load can be quickly dispersed and transmitted to both sides along the corrugated ridge, avoiding excessive local plastic deformation. For example, setting a shallow corrugated rib with a depth of 1.5mm every 20mm in the lower anti-kick and impact-resistant zone can reduce the maximum deflection of this area by 40% under the same impact force. This transverse ribbed structure, together with the aforementioned secondary ribbed reinforcement at the interlocking edges, constructs a dual reinforcement system for the mesh edge and the main body area, ensuring that the protective mesh has excellent impact resistance while maintaining a lightweight design.

[0064] Example 6 In another embodiment, based on the above embodiments, the specific preparation method, structural composition and dimensional parameters of the lightweight frame profile in step S4 are further defined.

[0065] Step 1: Lightweight frame profiles are produced by roll forming, cold bending, bending or extrusion forming; The lightweight frame profile refers to a frame component used to enclose and fix the gradually changing aperture mesh, preferably made of low-carbon steel, galvanized steel, aluminum-magnesium alloy, or steel-aluminum composite material. The forming method is a processing technology selected based on production batch size, cross-sectional complexity, and material properties: roll forming is suitable for large-scale continuous production, gradually bending the strip into the target cross-section through multiple roll passes, characterized by high efficiency and good dimensional consistency; cold bending involves bending the sheet material at room temperature using a die, suitable for medium-batch production with many cross-sectional variations; bending is suitable for small-batch trial production or single-piece processing of large-size frames; extrusion forming is particularly suitable for ductile materials such as aluminum alloys, allowing for the one-time extrusion of profiles with complex internal cavity structures. For example, when using 1.2mm thick galvanized steel strip, roll forming is used, with 8-10 roll passes for gradual deformation, ultimately forming a frame profile with high-precision cross-sectional dimensions; while when using aluminum alloy materials, extrusion forming is used, directly extruding a complex cross-section with reinforcing ribs and receiving grooves. By flexibly selecting from the above-mentioned various molding methods, it is possible to adapt to the needs of different material properties and production scales, ensuring that the frame profile has sufficient rigidity and dimensional accuracy while being lightweight, thus providing a reliable hardware foundation for subsequent mesh assembly.

[0066] Step 2: The frame profile includes the outer frame wall, the inner limiting shoulder, the fitting groove, the undercut edge, and the reinforcing rib receiving groove; The outer frame wall forms the outer facade of the protective net, mainly serving the functions of appearance display and resistance to external collisions; the inner limiting shoulder is located at the entrance of the interlocking groove, with a stepped or sloping structure, used to guide and limit the lateral displacement of the net during insertion, preventing the net from sliding laterally under pre-tension; the interlocking groove is the core channel for accommodating the mesh insertion edge and the end of the reinforcing rib; the undercut pressing edge is a cantilevered elastic or plastic deformation component located at the opening of the interlocking groove, serving as a key actuator for mechanical locking; the reinforcing rib receiving groove is a groove structure set at the bottom or side wall of the interlocking groove, specifically used to accommodate the end of the reinforcing rib.

[0067] Step 3: The opening width of the fitting groove is 2mm-8mm, and the groove depth is 8mm-25mm; The opening width refers to the net distance at the entrance of the interlocking groove before the undercut edge is closed; the groove depth refers to the vertical distance from the entrance of the interlocking groove to the bottom of the groove. The opening width setting must balance insertion smoothness and locking density: if the width is too small (less than 2mm), it will be difficult to smoothly insert the mesh interlocking edge, increasing assembly resistance and even causing jamming; if the width is too large (greater than 8mm), the radial gap of the mesh in the groove will be too large before locking, affecting positioning accuracy and increasing the deformation stroke requirement of the undercut edge. The groove depth setting must match the folded edge width of the mesh interlocking edge: if the groove depth is too shallow (less than 8mm), it cannot fully accommodate the interlocking edge and the end of the reinforcing rib, causing the cantilever to easily fall off under stress; if the groove depth is too deep (greater than 25mm), it will increase the material usage of the profile, violating the principle of lightweighting, and may also lead to excessive internal gaps affecting the locking effect. For example, for a 12mm folded edge, the design of the fitting groove opening width is 4mm and the groove depth is 15mm. This allows the fitting edge to slide smoothly into the bottom of the groove, while also providing sufficient space for the undercut edge to deform and press downwards. By optimizing the dimensional matching of the opening width and groove depth, both the error tolerance during automated assembly and the secure containment of the mesh edge within the groove after locking are ensured, preventing loosening or abnormal noise caused by improper gaps.

[0068] Step 4: The undercut edge deforms toward the inside of the fitting groove during the pressing process in step S6 to form a mechanical engagement and locking of the mating edge.

[0069] The undercut edge refers to the edge of the frame that undergoes plastic deformation and buckles into the interlocking groove under the action of rolling, riveting, or flanging pressing. Its working principle utilizes the plastic flow of the material to force the edge, which was originally in an open state, into the interlocking groove, so that its tip or side is tightly pressed against the surface of the mesh interlocking edge, especially into the pre-formed ribs, grooves, or corrugations on the interlocking edge, forming an irreversible mechanical interlocking structure. This internal locking method differs from traditional external flanging or spot welding fixation. When subjected to external tension or impact, the undercut edge receives greater clamping force, exhibiting a self-locking characteristic that tightens as it is pulled. For example, in the multi-pass pressing process of step S6, the first pass initially closes the undercut edge to restrict the interlocking edge from detaching; the second pass forces the tip of the undercut edge into the rib area of ​​the interlocking edge; and the third pass makes it fully conform to the surface of the interlocking edge and simultaneously presses the end of the reinforcing rib, ultimately forming a mechanical interlocking connection with a locking force exceeding 2000N. The synergistic effect of the undercut edge, the interlocking groove, and the plug-in edge not only eliminates the material deterioration problem caused by the heat-affected zone of welding, but also evenly transfers the impact load on the mesh to the entire frame profile through the interlocking method of surface contact or line contact, which greatly improves the tear resistance and reliability of the protective mesh edge.

[0070] Example 7 In one alternative implementation, the method further includes a specific step of applying a pre-tension force to the mesh.

[0071] Step 1: In step S5, the tensioning fixture includes a fixed clamping end, a movable clamping end, a tensioning mechanism in the length direction, a tensioning mechanism in the height direction, and a frame positioning fixture; The fixed clamping end can refer to a rigid support component used to anchor one edge of the mesh sheet, which remains stationary during processing and provides a reaction force base point for the tensioning operation. The movable clamping end can refer to a clamping component that is set opposite to the fixed clamping end and can be displaced along the normal or tangential direction of the mesh sheet plane, used to clamp the other edge of the mesh sheet and perform the tensioning action. The length-direction tensioning mechanism and the height-direction tensioning mechanism can refer to power execution units that independently drive the movable clamping end to move along the long and short sides of the mesh sheet, respectively. They are usually composed of servo motors, lead screw drives, or hydraulic cylinders, used to achieve bidirectional independent tension control. The frame positioning fixture can refer to a positioning jig set around the tooling table to limit the placement position of the frame profile or to assist in the centering and installation of the mesh sheet. This step aims to create a mechanical environment that can precisely control the stress distribution within the two-dimensional plane of the mesh. By coordinating the fixed clamping end and the moving clamping end, combined with a bidirectional independent tensioning mechanism, it ensures that the mesh can simultaneously achieve uniform and controllable tensile deformation in both length and height dimensions before entering the frame. This avoids mesh distortion or local stress concentration caused by unidirectional force, providing a flat base for subsequent frame-mesh fitting.

[0072] Step 2: When applying pre-tension force to the mesh, control the pre-tension elongation rate in the length direction of the mesh to be 0.05%-0.50%, and the pre-tension elongation rate in the height direction to be 0.03%-0.35%; The pre-tension elongation rate refers to the ratio of the length increment of the mesh after being subjected to tension during the elastic deformation stage to its original length. This parameter directly determines the magnitude of the residual tensile stress formed within the frame after the mesh releases tension. The pre-tension elongation rate in the length direction is set at 0.05%-0.50%, which is based on the geometric characteristics that the length of the protective mesh is usually greater than its height and the main stress direction. If it is lower than 0.05%, the residual stress after the mesh rebounds will not be sufficient to offset the relaxation deformation during transportation and installation, resulting in bulging of the mesh surface. If it is higher than 0.50%, it may exceed the elastic limit of the material, causing permanent plastic distortion of the mesh or yielding and breakage of the ribs. The pre-tension elongation rate in the height direction is set at 0.03%-0.35%, slightly lower than that in the length direction, to accommodate the stiffness difference in the height direction of the mesh and prevent the frame from warping due to excessive tightness at the top. For example, for a steel mesh sheet with a length of 2000mm, the pre-tension elongation rate in the length direction can be set to 0.20%, which controls the displacement of the moving clamping end by 4mm; for a mesh sheet with a height of 1200mm, the pre-tension elongation rate in the height direction can be set to 0.15%, which controls the displacement by 1.8mm. Through this bidirectional differentiated control, a matching residual stress field can be formed in the length and height directions of the mesh sheet, ensuring that the mesh surface is in an ideal tensioned and flat state after the tension is released, thus eliminating the initial waviness while retaining sufficient impact stiffness.

[0073] Step 3: When the mesh is made of steel, the pretension force on one side is 300N-2000N; when the mesh is made of aluminum alloy, the pretension force on one side is 150N-1200N.

[0074] The unilateral pretension force refers to the tensile force exerted by the tensioning mechanism on one side of the mesh during the tensioning process. This value is set based on the yield strength and safety factor of different metal materials. Steel mesh is usually made of galvanized steel plate or high-strength steel plate, which has a high yield strength (about 200MPa or more). Therefore, a larger pretension force (300N-2000N) is required to produce effective elastic elongation and form sufficient residual stress. This range corresponds to the safe elastic range of a typical size (e.g., 1500mm wide × 1.0mm thick) steel mesh, which can ensure the tensioning effect and avoid permanent deformation caused by overload. Aluminum alloy mesh has a relatively low yield strength (about 100MPa) and a small elastic modulus. If the same force value as steel mesh is applied, it is very easy to undergo plastic deformation or breakage. Therefore, its unilateral pretension force is limited to a lower range of 150N-1200N. For example, when processing 1.2mm thick steel mesh, the pretension force on one side can be controlled at around 800N; while when processing 1.5mm thick aluminum-magnesium alloy mesh, the pretension force on one side should be controlled at around 400N. By strongly linking the pretension force with the material properties, this step ensures that meshes of different materials can achieve the best pretension effect within their respective elastic ranges, realizing the universality and precision of the process parameters.

[0075] Example 8 One possible implementation also includes using a multi-pass pressing method in step S6 to collaboratively lock the frame profile, the interlocking edge, and the end of the reinforcing rib.

[0076] Step 1: The first pressing process initially closes the groove of the frame profile to prevent the interlocking edge from coming out of the groove. The first pressing step involves applying initial radial pressure to the undercut edge of the frame profile using a rolling roller or pressing die, causing elastic or slight plastic deformation towards the inward side of the interlocking groove. This step aims to reduce the width of the open interlocking groove from the initial assembly gap to a preset limit size, typically controlled between 70% and 85% of its fully closed state. This initial contraction significantly restricts the axial freedom of the interlocking edge, preventing axial movement or accidental dislodgement during subsequent high-pressure pressing, thus establishing stable initial constraints for subsequent fine pressing. For example, when the interlocking edge width is 15mm, the remaining opening width after the first pressing step can be controlled to 2mm-4mm, at which point the interlocking edge is held but has not yet undergone permanent deformation. This step provides the necessary geometric reference for subsequent deep interlocking, effectively avoiding pressing misalignment caused by component loosening.

[0077] Step 2: The second pressing is to press the undercut edge into the rib area of ​​the interlocking edge; The second pressing step involves further increasing the pressing force to drive significant plastic deformation of the undercut edge, precisely embedding its tip or inner edge into the pre-formed ribs, grooves, or corrugated structures on the interlocking edge. The core function of this step is to utilize the undulating structure of the interlocking edge surface to form the first layer of mechanical self-locking, preventing the mesh from axially dislodging from the frame under tension. The pressing depth is typically designed to be 60%-90% of the rib height to ensure sufficient pull-out resistance without damaging the mesh substrate. For example, if the rib height on the interlocking edge is 3mm, the second pressing step will cause the undercut edge to penetrate approximately 2mm-2.5mm into the root of the rib, forming a tight interference fit. During this process, the undercut edge and the rib area of ​​the interlocking edge cooperate, increasing the coefficient of friction and mechanical interlocking strength of the connection interface through the work-hardening effect of the local material. This step achieves a transformation from positional constraint to mechanical locking, significantly improving the reliability of the edge connection.

[0078] Step 3: The third pressing is to simultaneously press the undercut edges against the insert edge and the end of the reinforcing rib. The third pressing step involves applying a final closing force to completely close the undercut edge, simultaneously pressing and fixing the end of the reinforcing rib located in the interlocking groove together with the insertion edge. This step aims to achieve coordinated load-bearing of the frame, mesh, and reinforcing ribs, creating a continuous force transmission path. At this stage, the undercut edge not only locks the insertion edge but also firmly fixes the end of the reinforcing rib in the reinforcing rib receiving groove through compression, eliminating assembly gaps between components. The reinforcing rib can be one or more of the following: horizontal reinforcing ribs, vertical reinforcing ribs, lower anti-kick reinforcing ribs, or short corner reinforcing ribs, arranged according to different stress requirements. For example, for deep foundation pit reinforced protective netting, when horizontal and vertical reinforcing ribs are arranged in a cross pattern, the third pressing step ensures that all rib ends form a rigid connection with the frame, allowing impact loads to be seamlessly transferred from the mesh through the insertion edge and reinforcing ribs to the frame body. Through this synchronous pressing mechanism, the maximum stress concentration factor in the edge area can be reduced by more than 50%, effectively avoiding the problem of single-point welding or snap-fit ​​failure.

[0079] Step 4: The fourth shaping process involves correcting the external dimensions, straightness, and groove closure of the frame profile. The fourth shaping step involves fine-tuning and correcting the overall geometry of the frame profile using shaping molds or rollers after locking. Because the material undergoes plastic flow during the first three pressing processes, slight bending, elliptical grooves, or uneven surfaces may occur in some areas of the frame. This step restores the design dimensional accuracy of the frame by applying reverse force or precision rolling. This step ensures that the final product's installation interface tolerances meet construction requirements and guarantees flatness and sealing when multiple protective nets are spliced. Specifically, the straightness error of the corrected frame can be controlled within 0.5mm per meter, and the groove closure gaps are uniform with no visible gaps. For example, for long frames that have accumulated bending deformation after continuous rolling, the fourth shaping step corrects it to a straightness tolerance of ≤±0.3mm through multi-point support and localized pressure. As the final control step in the process, this step eliminates dimensional deviations caused by processing stress, ensuring the appearance quality and assembly performance of the protective net.

[0080] Example 9 In another embodiment, a molding quality inspection step is performed after step S8.

[0081] Step 1: Following step S8, a molding quality inspection step is also included; The forming quality inspection step refers to the process of quantitatively evaluating and classifying the key performance indicators of the protective netting after the overall anti-corrosion coating treatment is completed. This step aims to verify the actual effectiveness of the aforementioned pre-tensioning and locking edges, gradual aperture punching and expansion, and zoned anti-corrosion processes, ensuring that the product meets the safety and durability requirements of pit edge protection. The inspection process is based on automated testing equipment or standard test benches, collecting physical quantity data and comparing it with preset thresholds to form a quality judgment conclusion.

[0082] Step 2: The molding quality inspection steps include at least three of the following: mesh surface flatness inspection, edge locking force inspection, impact deformation inspection, corner crack resistance inspection, and coating integrity inspection; The aforementioned testing items are designed based on the main failure modes of the protective netting under actual working conditions. The netting surface flatness test assesses whether the pre-tensioning process effectively eliminates netting slack and bulging; the edge locking force test verifies the mechanical interlocking reliability of the frame-net co-pressure interlocking structure; the impact deformation test assesses the energy absorption and rebound capacity of the protective netting under dynamic loads; the corner crack resistance test confirms the fatigue resistance of the corner flange reinforcement structure during repeated handling; and the coating integrity test verifies the protective effect of the zoned anti-corrosion sealing treatment on the cut and edge locking areas. For example, for ordinary reusable products, only the netting surface flatness test, edge locking force test, and coating integrity test need to be selected as mandatory factory inspection items; while for deep foundation pit reinforced products, all five tests must be performed to ensure safety under extreme working conditions. By combining different testing items, the quality control requirements of different product grades can be flexibly adapted.

[0083] Step 3: Among them, the flatness detection of the mesh surface is used to determine the bulge height of the center of the mesh relative to the edge plane; One embodiment of this test is as follows: The protective netting is placed horizontally on the testing platform, with the upper surface of the frame as the reference plane. The vertical distance between the geometric center point of the netting and the reference plane is measured using a laser displacement sensor or a high-precision dial indicator. If the measured bulge height exceeds a preset threshold (e.g., 5mm), the flatness of the netting surface is deemed unqualified, indicating uneven distribution of residual stress after the release of pre-tension force or insufficient shaping. This indicator directly reflects the process stability of the pre-tension elongation control in step S5 and the shaping treatment in step S7. The smaller the bulge height, the flatter the netting surface, the better the visual consistency, and the higher the initial impact stiffness.

[0084] Step 4: Edge locking force test is used to determine whether the mating edge has come out of the fitting groove under tension; One implementation of this test involves taking a sample containing the locking edge structure or applying radial tension to the entire edge of the protective net. A universal testing machine is used to apply the load at a constant rate, and the maximum load value when the interlocking edge slips out of the groove or completely disengages is recorded. For example, the pass / fail standard is set as follows: after applying a 1500N tensile force for 1 minute, the interlocking edge shows no visible displacement and does not disengage from the groove. This test result directly verifies the quality of the multiple rolling passes and the closing of the undercut edge in step S6. Insufficient locking force means that the undercut edge has not been effectively pressed into the rib area of ​​the interlocking edge, posing a safety hazard.

[0085] Step 5: Impact deformation testing is used to determine the maximum deflection and recovery rate of the protective netting after being subjected to impact; One implementation of this test involves using a pendulum or drop hammer of specified mass to freely drop from a designated height onto the middle or lower anti-kick and impact zone of the protective net. A high-speed camera or displacement sensor records the maximum deflection at the moment of impact and the residual deformation after the impact stops, and then calculates the recovery rate (Recovery rate = (Maximum deflection - Residual deformation) / Maximum deflection × 100%). For example, using a 10kg pendulum impacting from a height of 1m, the maximum deflection should not exceed 30mm and the recovery rate should not be less than 95%. This indicator comprehensively reflects the dynamic response characteristics under the synergistic effect of the gradually changing aperture design, the transverse rib structure, and the residual tension state of the mesh. A high recovery rate indicates that the protective net has excellent elastic recovery ability and can withstand multiple impacts.

[0086] Step Six: Based on the test results, the lightweight high-strength foundation pit edge protection netting is classified into ordinary perimeter type, reinforced perimeter type, or deep foundation pit reinforced type.

[0087] The grading system is based on the compliance of various test data. If a product passes only the tests for mesh flatness, edge locking force, and coating integrity, and the indicators meet the basic standards, it is classified as a standard turnover type, suitable for general construction scenarios. If, in addition to the above, the product further passes the impact deformation test and corner crack resistance test, and the impact recovery rate and corner crack-free items meet the standards, it is classified as a reinforced turnover type, suitable for high-frequency turnover or medium-risk areas. If the product passes all tests, and the key indicators (such as locking force and impact deflection limits) reach higher and more stringent standards, it is classified as a deep foundation pit reinforced type, specifically for high-risk edge protection scenarios such as deep foundation pits and subway foundation pits. This grading mechanism achieves a precise match between production process output and engineering application needs, avoiding the safety risks caused by using low-end components for high-end applications or the cost waste caused by using high-end components for low-end applications.

[0088] Example 10 In foundation pit construction, subway construction, and underground utility tunnel projects, edge protection netting is a crucial component for preventing personnel falls, tool slippage, and ensuring construction safety. Existing foundation pit edge protection devices mostly employ a structure of steel pipe frames welded with steel wire mesh or perforated plates. However, this traditional structure has significant shortcomings in practical applications: on the one hand, the pursuit of strength often results in excessive overall weight, making manual handling and rapid installation difficult; on the other hand, simply reducing the mesh thickness or increasing the aperture to reduce weight can lead to bulging and deformation of the netting under impact, and the connections between the mesh and the frame (such as weld points and screw connections) easily become stress concentration areas, prone to loosening or tearing under repeated disassembly and impact loads. Furthermore, the flatness of existing protective netting surfaces is difficult to control, often exhibiting loosening and warping, and the perforated cuts and connection points are highly susceptible to corrosion, severely affecting service life and protective reliability.

[0089] To address the aforementioned issues, this application provides a lightweight, high-strength foundation pit edge protection net. This net achieves a balance between lightweight and high strength through a specific structural design. Rather than a simple assembly of components, this net is based on a zoned stress distribution concept, systematically integrating gradient aperture mesh, a lightweight frame with a special locking structure, reinforcing ribs, and an anti-corrosion coating. This ensures that all components function synergistically, forming a complete protection system with residual tension and excellent impact resistance.

[0090] In one optional embodiment, this application also provides a lightweight high-strength foundation pit edge protection net, including a lightweight frame, a gradient aperture mesh, reinforcing ribs, and an anti-corrosion coating; A lightweight frame surrounds the gradient aperture mesh, and the lightweight frame has a fitting groove for accommodating the edge of the mesh and an undercut pressing edge that closes toward the fitting groove. The gradient aperture mesh includes a frame connection area, a middle transparent weight reduction area, and a lower anti-kick and anti-collision area. The aperture of the frame connection area and the lower anti-kick and anti-collision area is smaller than the aperture of the middle transparent weight reduction area, and the width of the inter-aperture ribs in the frame connection area and the lower anti-kick and anti-collision area is greater than the width of the inter-aperture ribs in the middle transparent weight reduction area. The perimeter of the gradient aperture mesh is provided with interlocking edges formed by folded edge ribs. The interlocking edges are embedded in the fitting grooves of the lightweight frame and are pressed and locked by the inverted edge. The reinforcing ribs are set on the back or edge of the tapered mesh, and the ends of the reinforcing ribs and the interlocking edges are embedded in the fitting groove and locked together by the inverted pressing edge. The lower anti-kick and anti-collision zone is equipped with a horizontal rib structure, and the gradient aperture mesh is in a tensile and flat state within the lightweight frame. The anti-corrosion coating covers the lightweight frame, the gradient aperture mesh, the interlocking edge, the groove opening, and the surface of the transverse rib structure.

[0091] The lightweight frame can be made of thin-walled steel profiles, galvanized steel profiles, aluminum alloy profiles, or steel-aluminum composite profiles. Its cross-sectional shape can be designed as U-shaped, C-shaped, or other irregularly shaped structures with accommodating space, depending on actual installation requirements. The main function of this lightweight frame is to provide a rigid support frame for the internal gradually changing aperture mesh, and to achieve mechanical interlocking and locking with the mesh through its unique interlocking groove and undercut edge structure. The opening width and depth of the interlocking groove can be set according to actual conditions; for example, the opening width can be 2mm-8mm, and the groove depth can be 8mm-25mm, to ensure that the folded edges of the mesh and the ends of the reinforcing ribs can be accommodated. During the forming process, the undercut edge undergoes plastic deformation towards the inside of the interlocking groove, thereby forming an irreversible mechanical locking force on the embedded interlocking edge. This connection method avoids the heat-affected zone embrittlement and stress concentration problems caused by traditional welding.

[0092] The gradient aperture mesh is the core load-bearing component of this application, which can refer to a mesh structure obtained by punching or expanding metal sheets. The mesh is divided into different functional areas according to the actual stress distribution of the pit edge protection: the edge connection area is located around the perimeter of the mesh, mainly used for high-strength connection with the edge, therefore its aperture is smaller and the inter-aperture ribs are wider to provide sufficient material density to withstand locking force and edge shear force; the central transparent weight-reducing area is located in the main body of the mesh, its main function is to minimize the overall weight and maintain visibility while ensuring basic protective functions, therefore its aperture is larger and the inter-aperture ribs are narrower; the lower kick-resistant and impact-resistant area is located at the bottom of the mesh, used to resist impacts from workers kicking, tools hitting, or small objects slipping, therefore its aperture and rib width are between the former two or close to the edge connection area, forming a high-density impact barrier. This gradient distribution of aperture and rib width design allows the mesh to exhibit differentiated mechanical properties in different areas, achieving the technical effect of maintaining strength in dangerous areas and reducing weight in non-dangerous areas.

[0093] The interlocking edge is a specific structure formed by folding and ribbing the edges of a tapered mesh. This interlocking edge can refer to a flange formed by bending the mesh edge inwards or outwards, with further ribs, grooves, or corrugations pressed onto this flange. The presence of the interlocking edge not only increases the moment of inertia of the mesh edge and improves its tear resistance, but more importantly, the ribbed structure, in conjunction with the undercut edge of the frame, significantly increases the friction and mechanical interlocking capability of the contact surfaces. When the interlocking edge is embedded in the groove and pressed tightly by the undercut edge, the ribbed structure effectively prevents the mesh from sliding or coming out of the groove, thus ensuring the long-term stability of the connection.

[0094] Reinforcing ribs can refer to strip-shaped, cap-shaped, or angular reinforcing members installed on the back or edge of a mesh with varying apertures. Their material can be the same as or different from the mesh, for example, high-strength steel strips or aluminum alloy profiles. The main function of the reinforcing ribs is to distribute the localized concentrated load borne by the mesh and evenly transfer the load to the lightweight frame. In the technical solution of this application, the ends of the reinforcing ribs are not independently fixed, but are embedded together with the interlocking edges of the mesh into the fitting grooves of the frame, and are locked together by the same undercut edge. This frame-mesh-rib co-pressing and fitting structure makes the frame, mesh, and reinforcing ribs form a continuous overall load-bearing path, eliminating the weak points in the connection caused by individually fixing the reinforcing ribs in traditional structures, and significantly improving the overall rigidity and impact resistance of the protective net.

[0095] The transverse rib structure is a specific reinforcing feature installed in the lower kick and impact protection zone. It can refer to shallow corrugated ribs, transverse reinforcing grooves, or continuous raised stripes extending along the length of the mesh. The function of this structure is to improve the transverse stiffness and bending resistance of the lower area. When the lower part of the protective net is subjected to horizontal kicks or impacts, the transverse ribs can quickly disperse the impact force, limit local elastic deformation, and prevent the mesh from developing permanent dents or cracks.

[0096] The tensioned and flat state refers to a state of stress balance exhibited by the gradually changing aperture mesh within the lightweight frame. This state is achieved by applying pre-tension to the mesh during assembly and releasing the tension after the frame is locked. In this state, a certain amount of residual tensile stress remains within the mesh, keeping the mesh surface taut at all times. This eliminates slack, bulging, or warping caused by processing, transportation, or temperature changes, ensuring the flatness of the protective mesh's appearance and the consistency of its protective performance.

[0097] The anti-corrosion coating is a protective layer applied to the critical surfaces of the protective netting. It can refer to a zinc-rich primer, an electrostatic powder coating, a dip-coating, or a combination of both. This coating not only covers the exposed surfaces of the mesh and frame but also extends to areas that are difficult to cover or are susceptible to corrosion, such as interlocking edges, groove openings, and transverse rib structures. By providing comprehensive anti-corrosion sealing to these stress concentration areas and processing cuts, it effectively blocks the contact between moisture, oxygen, and corrosive media and the base metal, significantly extending the service life of the protective netting in harsh outdoor environments.

[0098] Specifically, when the lightweight, high-strength foundation pit edge protection net of this application is in operation, if an external impact load is applied to the surface of the net, the load is first absorbed and dispersed differentially by different areas of the gradually varying aperture net according to the distribution of its aperture and rib width: the central large-aperture area mainly undergoes elastic deformation to buffer energy, while the lower dense-aperture area and the frame connection area provide the main impact resistance support due to the higher material density and transverse rib structure. Subsequently, the load is transferred through the net to the embedded reinforcing ribs, which diffuse the concentrated load along their length and finally transfer it to the entire lightweight frame through the mechanical interlocking interface between the interlocking edge and the frame's fitting groove. Because the net is in a tensioned and flat state, the residual tensile stress inside can offset some of the compressive deformation caused by external impact, quickly restoring its original shape. At the same time, the tight cooperation between the undercut edge and the interlocking edge rib structure ensures the stability of the connection interface under dynamic loads, preventing the net from detaching from the frame or slipping relative to it.

[0099] As a preferred embodiment, the specific implementation of this application is as follows: A high-strength galvanized steel sheet with a thickness of 1.2mm is selected as the wire mesh blank, and it is divided into a 50mm wide frame connection area, a 250mm high lower anti-kick and anti-collision area, and a central transparent weight-reducing area located between the two. Round holes with a diameter of 10mm and an inter-hole rib width of 10mm are punched in the frame connection area and the lower anti-kick and anti-collision area. Oblong holes with a diameter of 40mm and an inter-hole rib width of 5mm are punched in the central transparent weight-reducing area and expanded by 1.2 times. The edges of the wire mesh are bent inward by 15mm to form interlocking edges, and corrugated ribs with a height of 3mm are pressed on the interlocking edges. Shallow transverse corrugated ribs are pressed on the lower anti-kick and anti-collision area. A C-shaped cold-formed steel profile with a wall thickness of 1.5mm is selected as the lightweight frame, and its fitting groove depth is 15mm. Two transverse cap-shaped reinforcing ribs are placed on the back side of the mesh, and their ends are inserted into the frame's fitting groove along with the mesh's interlocking edge. While maintaining a pre-tension elongation of 0.2% along the mesh's length, a rolling mill is used to close the frame's undercut edges inward, firmly locking the interlocking edge and the ends of the reinforcing ribs. After releasing the tension, the mesh forms a flat, stretched state within the frame. Finally, all cuts, grooves, and surfaces are treated with a zinc-rich primer and powder coating to obtain the finished protective mesh.

Claims

1. A molding and processing technology for a lightweight, high-strength foundation pit edge protection net, characterized in that, include: S1. Based on the stress location of the perimeter protection net of the foundation pit, the net to be processed is divided into the frame connection area, the middle transparent weight reduction area and the lower anti-kick and anti-collision area. S2. The metal sheet blank is punched in sections or expanded after punching, so that the aperture of the frame connection area and the lower anti-kick and anti-collision area is smaller than the aperture of the middle transparent weight reduction area, and the width of the rib between the holes in the frame connection area and the lower anti-kick and anti-collision area is greater than the width of the rib between the holes in the middle transparent weight reduction area. S3. Fold and press the edges of the punched or expanded mesh to form interlocking edges for embedding into the frame, and press the lower anti-kick and anti-collision zone laterally. S4. Prepare a lightweight frame profile with interlocking grooves and undercut edges, and arrange reinforcing ribs on the back side of the mesh or at the corresponding position on the edge of the mesh. S5. Place the wire mesh after edge folding and rib pressing in the tensioning fixture, and apply pre-tension force along the length and height of the wire mesh so that the wire mesh is in a tensioned and flat state before entering the frame. S6. Under the pre-tensioned state, the insertion edge and the end of the reinforcing rib are fed into the fitting groove of the frame profile, and the undercut edge is closed into the fitting groove by rolling, riveting or flanging pressing to lock the mesh edge and the end of the reinforcing rib together in the frame profile. S7. After the frame profile is closed and locked, the pre-tension force is released so that the mesh is in a residual tension state inside the frame, and the frame and mesh are corrected. S8. Local anti-corrosion sealing is applied to the punched cuts, interlocking edges, frame fitting grooves, and ribbed areas. Then, the entire protective net is coated with anti-corrosion paint to obtain a lightweight, high-strength foundation pit edge protection net.

2. The molding process according to claim 1, characterized in that, In step S1, the mesh to be processed is further divided into corner connection areas located at the four corners of the mesh and around the connection holes; The border connection area is arranged around the perimeter of the mesh, with a width of 30mm-80mm; The lower anti-kick and anti-collision zone is located at the bottom of the mesh, with a height of 150mm-350mm; The central transparent weight reduction zone is located between the frame connection area and the lower anti-kick and anti-collision zone; The corner connection area is used to form a rounded transition structure or a local flanging reinforcement structure during subsequent punching, folding, or rib-pressing processes.

3. The molding process according to claim 1, characterized in that, In step S2, the partition punching includes: A first group of holes with a hole diameter of 4mm-12mm and a rib width of 6mm-15mm is punched in the frame connection area; A second set of holes with a diameter of 20mm-60mm and a rib width of 3mm-10mm is punched in the central transparent weight reduction zone; A third set of holes with a diameter of 8mm-25mm and a rib width of 6mm-15mm is punched in the lower anti-kick and anti-collision zone; The hole shapes in the first hole group, the second hole group, and the third hole group are one or more of the following: round hole, oblong hole, rhomboid hole, hexagonal hole, or rounded rectangular hole.

4. The molding process according to claim 1, characterized in that, In step S2, the central transparent weight reduction area is punched and then expanded, with the expansion direction set along the length of the mesh or along a direction that is intersecting with the extension direction of the reinforcing rib. The magnification of the central perspective weight reduction zone is 1.05-1.40; The border connection area is not expanded, or its expansion ratio is less than that of the central perspective weight reduction area; The expansion ratio of the lower anti-kick and impact-resistant zone is less than the expansion ratio of the middle transparent weight-reducing zone.

5. The molding process according to claim 1, characterized in that, In step S3, the edge-folding and rib-pressing process includes: The edges of the mesh are bent once to form an interlocking edge with a fold width of 8mm-25mm; The interlocking edge is reinforced with secondary ribs to form raised ribs, grooves, or corrugated ribs with a height of 1mm-6mm. The four corners of the wire mesh are pre-punched or pressed to round the corners. Reinforce the area around the connection hole with circumferential ribs or flanges; The transverse reinforcement treatment involves forming shallow corrugated ribs or transverse reinforcing rib grooves extending along the length of the mesh in the lower anti-kick and anti-collision zone.

6. The molding process according to claim 1, characterized in that, In step S4, the lightweight frame profile is obtained by roll forming, cold bending, bending or extrusion forming; The frame profile includes an outer frame wall, an inner limiting shoulder, a fitting groove, a buckle edge, and a reinforcing rib receiving groove; The opening width of the fitting groove is 2mm-8mm, and the groove depth is 8mm-25mm; The undercut edge deforms toward the inside of the fitting groove during the pressing process in step S6 to form a mechanical engagement and locking of the insertion edge.

7. The molding process according to claim 1, characterized in that, In step S5, the tensioning fixture includes a fixed clamping end, a movable clamping end, a tensioning mechanism in the length direction, a tensioning mechanism in the height direction, and a frame positioning fixture; When applying pre-tension force to the mesh, the pre-tension elongation rate in the length direction is controlled to be 0.05%-0.50%, and the pre-tension elongation rate in the height direction is controlled to be 0.03%-0.35%. When the mesh is made of steel, the pretension force on one side is 300N-2000N; When the mesh is made of aluminum alloy, the pretension force on one side is 150N-1200N.

8. The molding process according to claim 1, characterized in that, In step S6, the rolling, riveting, or flanging pressing method is a multi-pass pressing method, including: The first pressing process initially closes the groove of the frame profile to prevent the insertion edge from coming out of the groove. The second pressing process presses the undercut edge into the rib area of ​​the interlocking edge. The third pressing step causes the undercut edge to simultaneously press the insertion edge and the end of the reinforcing rib; The fourth shaping process corrects the external dimensions, straightness, and groove closure of the frame profile. The reinforcing rib is one or more of the following: a horizontal reinforcing rib, a vertical reinforcing rib, a lower anti-kick reinforcing rib, or a corner short reinforcing rib.

9. The molding process according to claim 1, characterized in that, Following step S8, a molding quality inspection step is also included; The molding quality inspection steps include at least three of the following: mesh surface flatness inspection, edge locking force inspection, impact deformation inspection, corner crack resistance inspection, and coating integrity inspection; The mesh flatness detection is used to determine the bulge height of the mesh center relative to the frame plane; The edge locking force detection is used to determine whether the insertion edge has come out of the fitting groove under tension. The impact deformation detection is used to determine the maximum deflection and recovery rate of the protective net after it has been subjected to an impact; Based on the test results, the lightweight high-strength foundation pit edge protection net is classified into ordinary perimeter type, reinforced perimeter type, or deep foundation pit reinforced type.

10. A lightweight, high-strength perimeter protection net for foundation pits, characterized in that, Includes lightweight frame, gradient aperture mesh, reinforcing ribs, and anti-corrosion coating; The lightweight frame surrounds the gradient aperture mesh, and the lightweight frame is provided with a fitting groove for accommodating the edge of the mesh and an undercut pressing edge that closes toward the fitting groove. The gradient aperture mesh includes a frame connection area, a middle transparent weight reduction area, and a lower anti-kick and anti-collision area. The aperture of the frame connection area and the lower anti-kick and anti-collision area is smaller than the aperture of the middle transparent weight reduction area, and the width of the inter-aperture ribs in the frame connection area and the lower anti-kick and anti-collision area is greater than the width of the inter-aperture ribs in the middle transparent weight reduction area. The gradient aperture mesh has interlocking edges formed by folded edge ribs around its perimeter. The interlocking edges are embedded in the fitting grooves of the lightweight frame and are pressed and locked by the undercut edge. The reinforcing rib is disposed on the back side or edge of the tapered mesh, and the end of the reinforcing rib and the insertion edge are embedded together in the fitting groove and locked together by the undercut pressing edge. The lower anti-kick and anti-collision zone is provided with a transverse pressure rib structure, and the gradient aperture mesh is in a tensioned and flat state within the lightweight frame. The anti-corrosion coating covers the lightweight frame, the gradient aperture mesh, the interlocking edge, the fitting groove, and the surface of the transverse rib structure.

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