1.Why are cold-rolled coils suitable for making edge-sealing connectors?
Excellent formability: The cold rolling process gives the steel a finer grain structure and good plastic deformation capacity, enabling it to withstand complex bending, compression, and flow deformation during edge rolling without cracking.
High surface quality: Cold-rolled coils have a smooth, clean surface free of oxide scale. This is crucial for sealing, as the smooth surface allows for better adhesion to sealing gaskets, forming an effective sealing surface.
High dimensional accuracy: Uniform thickness and small tolerances ensure the stability and consistency of the edge rolling process, thereby guaranteeing uniform sealing.
Wide range of strength options: From soft, deep-drawn grades to high-strength steel grades, options can be selected based on the structural strength and forming difficulty of the connector.
2.What are the effects of plasticity and hardness on a material?
Plasticity: A grade with high elongation (e.g., A80 ≥ 20%) must be selected. Insufficient plasticity will cause cracking on the outer side of the material during crimping.
Hardness: Excessive hardness increases springback, making the crimp shape unstable and potentially damaging the sealing gasket. A softer grade is generally required.
3.What are the requirements for corrosion prevention?
Cold-rolled coils (such as SPCC and DC01) are essentially carbon steel and are highly susceptible to rust. If the application environment has any humidity, pure cold-rolled coils are not suitable for direct use in sealing connections.
Surface corrosion protection treatment is necessary. This typically means:
Preferred option: Use galvanized cold-rolled coils directly (such as SGCC and DX51D+Z). The zinc layer provides sacrificial anode protection and is the most cost-effective choice.
Other options: After cold-rolled coil forming, perform electroplating, nickel plating, powder coating, or oiling. Attention should be paid to the adhesion and integrity of the coating in the deformed areas of the coil edges.
4.What are some suggestions for material selection?
General Commercial/Stamping Grades:
Chinese Grade: DC01 (GB/T 5213)
Japanese Grade: SPCC (JIS G 3141) – The most common choice
American Grade: CS Type B (ASTM A1008)
Deep Drawing/Extra Deep Drawing Grades (for parts with complex shapes and demanding edge requirements):
Chinese Grades: DC03, DC04, DC05 (stamping performance increases sequentially)
Japanese Grades: SPCD, SPCE, SPCF (stamping performance increases sequentially)
Direct Choices for Corrosion Resistance:
Zinc Plate: DX51D+Z, SGCC (Hot-Dip Galvanized), SECC (Electro-Zinc).
Aluminized Zinc Plate: SGLD, with superior corrosion resistance.
5.What are the key design considerations for the rolled edge process?
Mold Design: Precisely control the path, pressure, and final shape of the crimping rollers. A multi-pass, step-by-step molding process is typically used to avoid excessive deformation at once.
Gasket Matching: The hardness, compression set, and cross-sectional shape of the gasket (usually rubber or silicone) must match the geometry and clamping force of the crimp. Fit testing is required.
Quality Control:
Visual Inspection: Inspect the crimp for uniformity, smoothness, and absence of cracks or wrinkles.
Dimensional Inspection: Measure key dimensions of the crimp, such as crimp height and tightness.
Sealing Test: Conduct airtightness or watertightness tests; this is the final and most important inspection.