Our company's 3 Hole Yoke Plate is a core power fitting for high-voltage and ultra-high-voltage transmission lines and substations. It is mainly used for mechanical connections and load distribution between tower crossarms, insulator strings, and conductor clamps. Its product quality directly affects the operational safety, structural stability, and service life of transmission lines. Under long-term use in complex environments, the yoke plate needs to withstand multiple stresses, including tension, bending, torsion, vibration, wind loads, icing loads, and temperature fluctuations, while also resisting corrosion from acid rain, salt spray, and industrial pollution. Therefore, stringent standards are applied to the performance of raw materials, molding precision, mechanical strength, and the quality of the anti-corrosion coating. Whether these standards are met is closely related to the manufacturing process.
Raw materials are the foundation for determining the final mechanical properties and service life of the 3 Hole Yoke Plate. The use of recycled and inferior steel is strictly prohibited for this product. Structural steel that meets national and international standards must be selected, and a strict incoming inspection process must be implemented. Main application scenarios are divided into ordinary transmission lines, lines in heavy icing areas, coastal salt spray areas, and high-load ultra-high voltage lines, corresponding to different material grades:
Standard load lines: Q235B carbon structural steel is selected, possessing good plasticity, weldability, and cold working performance, with moderate cost, meeting general engineering needs;
Medium-high load lines: Q355B low-alloy high-strength structural steel is selected, with higher yield strength, excellent resistance to deformation and fracture, suitable for large spans and heavy load scenarios;
Special corrosive environments: Q355NH weathering steel or 304/316 stainless steel can be selected to improve corrosion resistance and reduce later maintenance costs;
Plate specifications are mainly hot-rolled steel plates, with common thicknesses of 12mm, 14mm, 16mm, 18mm, 20mm, and 22mm. Width and length are customized according to the external dimensions of the connecting plate to ensure no defects such as delamination, cracks, or excessive oxide scale.
After the raw materials arrive at the factory, they must be inspected, which is the first step in the production of 3 Hole Yoke Plates. The steel mill's quality certificate is checked to confirm that the chemical composition and mechanical properties meet the standards. The steel plate surface is flat, free of cracks, folds, scars, delamination, and bubbles; the oxide scale is dense and not peeling off. Thickness tolerances, length and width tolerances are checked using a tape measure, calipers, and micrometer to ensure sufficient machining allowance. After passing inspection, moisture-proof, rust-proof, and label management are implemented to prevent mixing and corrosion.
Blanking is the first forming process for 3 hole Yoke Plates. The goal is to cut the hot-rolled steel plate into a blank shape, ensuring dimensional accuracy, cut quality, and material utilization. The main processes are CNC cutting and die stamping, with CNC cutting being the primary method for mass production. For small-batch, multi-specification customization, CNC plasma/flame cutting machines are used, offering high flexibility, eliminating the need for molds, and adapting to three-hole Yoke Plates with different hole spacings and dimensions. For large-scale standardized production, closed-loop presses with dedicated stamping dies are used, offering high efficiency and consistency, suitable for large-scale production of fixed models.
The core function of the 3 hole Yoke Plate relies on three mounting holes for connection. The accuracy of the hole positions, the tolerance of the hole diameter, and the roughness of the hole walls directly affect the assembly effect and the uniformity of force distribution, making them the core control targets in the machining process. Using the flat sides and end faces of the connecting plate as positioning references, vises or special tooling fixtures are used for fixation to ensure secure clamping and prevent displacement or loosening during machining. All hole openings and plate edges must be chamfered to C1–C2, removing sharp burrs. The entire surface is then ground using a grinding wheel and flap wheel, resulting in a smooth surface free of tool marks, burrs, and oxide scale, providing a good base for subsequent hot-dip galvanizing.
Considering the long-term outdoor service of 3 hole yoke plates, hot-dip galvanizing is the only mainstream anti-corrosion process. Its core function is to form a dense zinc layer, achieving a dual anti-corrosion effect of physical shielding and cathodic protection. The quality of the zinc layer directly determines the product's service life. The hot-dip galvanizing process is as follows: degreasing → water washing → pickling and rust removal → water washing → flux treatment → drying → hot-dip galvanizing → cooling → passivation → finishing → inspection. This process removes oil, cutting fluid, and rust-preventive oil from the workpiece surface to avoid affecting the adhesion of the zinc layer. Alkaline chemical degreasing is used, with a degreasing agent temperature of 50–70℃ and an immersion time of 10–15 minutes, supplemented by mechanical stirring to ensure complete wetting of the workpiece surface. Thorough water washing ensures no degreasing agent residue remains before galvanizing.
After galvanizing, the workpiece is finely finished to ensure that it meets the installation and appearance requirements. Residual zinc spots and local zinc nodules on the hangers are removed, and the workpiece is polished with special tools without damaging the zinc layer. The mounting holes are then refinished to ensure that the holes are unobstructed and free from zinc layer blockage. The planes are aligned and corrected to eliminate galvanizing heat deformation. The matching bolts, nuts, flat washers, and spring washers are assembled and inspected to ensure that the assembly is flexible and usable.
