1.What are the core principles?
The biggest threats to cold-rolled coils are edge damage and interlayer misalignment. Once the edge of the coil is damaged or becomes stacked (misaligned), it can cause problems with threading the coil during uncoiling in downstream units, and may even damage the mill rolls, resulting in the entire coil being scrapped.
2.How to correctly select and use lifting gear?
C-Hook (Horizontal Coil Lifting Tool):
Applications: The most commonly used tool for loading and unloading horizontal coils.
Note: The supporting surface of the C-hook must be flat and smooth, and preferably covered with a polyurethane or nylon sheath. If there are metal filings or burrs on the C-hook, they will be pressed directly into the bottom layer of the steel coil, causing large-area indentation.
Alignment: The C-hook must be centered when inserted into the inner diameter of the steel coil. When lifting, apply force slowly first, and only lift after confirming stability to prevent the steel coil's center of gravity from shifting, causing it to slip or tip over.
Automatic Horizontal Coil Clamping Grippers (Grippers):
Applications: Crane loading and unloading.
Note: The contact points between the clamp arms and the edge of the steel coil must have soft protection (such as rubber pads or polyurethane boards). The clamping force needs to be adjusted appropriately-too much will flatten the steel coil, while too little may cause it to slip during rotation.
Vacuum suction cup lifting device (vertical coil):
If the coil is stored vertically, when using a vacuum suction cup, ensure that the surface of the cold-rolled coil is free of oil (oil will cause the suction cup to slip), and the suction cup can only be used on steel coils with good surface flatness. It is strictly forbidden to use it on steel coils with severe waviness.
3.What are the key details in the operation process?
Slow lifting and lowering, no sudden braking: Crane operation must be smooth. Rapid lifting or stopping will cause the steel coil to sway in the air, easily colliding with surrounding objects and generating a huge impact load on the lifting equipment.
Protect the edges (crucial):
The edges (circumference and sides) of the steel coil are the most vulnerable areas.
When placing the steel coil on the ground or on a saddle, ensure it is supported by rubber pads, wooden blocks, or a dedicated saddle. Direct contact between the steel coil and concrete surfaces or metal supports is strictly prohibited.
Avoid collisions between steel coils during placement (especially when stacking multiple coils).
Prevent moisture intrusion:
If your steel coils have undergone oil-free rust prevention treatment (such as passivation film) or vacuum packaging, pay special attention to the integrity of the packaging during loading and unloading.
Open-air loading and unloading operations are strictly prohibited in rainy or snowy weather. If it is necessary, use a proper rainproof tarpaulin to prevent rainwater from seeping in through packaging gaps (moisture inside vacuum packaging is almost impossible to escape and will quickly cause corrosion).
4.How to inspect before and after loading and unloading?
Packaging Inspection:
Before loading and unloading, ensure the outer packaging of the steel coils is intact.
After loading and unloading, check the packaging for new damage or punctures. This is especially important for vacuum-packed products, as even minor damage can lead to rust prevention failure.
Cleanliness:
Inspect the lifting equipment and storage area for water stains, oil, or debris.
For the "oil-free, high-cleanliness surface" product you mentioned earlier, operators should wear clean gloves to avoid contact between sweat and the steel plate surface (hand sweat contains salt, which can induce corrosion).
5.What are the safety red lines?
No standing allowed: During hoisting, no one is allowed to stand under the crane boom or near the movement path of the steel coil.
Secure securing: Whether transported by train, truck, or ship, the steel coil must be immediately secured after being placed to prevent displacement or overturning due to bumps during transport.