1.What are the typical characteristics and causes of burrs/burrs?
The cut edge has protruding metal burrs, or debris that has not been removed and is stuck to the edge.
Improper gap or overlap between scissors, or wear on the scissors.
2.What are the typical characteristics and specific causes of serrations/edge cracks?
The cut edge has fine serrations or micro-cracks.
The shear gap is too small, the material itself has poor toughness, and there are micro-cracks in the hot-rolled material.
3.How to perform precise calibration from the equipment perspective?
Core Adjustment (Disc Shears): This is the most direct step. Precise adjustment of the lateral clearance (typically 8%-12% of the material thickness) and overlap is required. Excessive clearance can lead to burrs, while insufficient clearance may cause cracks or accelerate tool wear.
Tool Maintenance: Ensure the cutting edge is sharp and free from chipping. It is recommended to establish a tool life management system, promptly re-sharpening or replacing the tool when the cutting edge radius exceeds a certain limit (e.g., 50μm).
Equipment Accuracy: Regularly check the radial runout of the cutter shaft (should be less than 0.01mm-0.03mm) and parallelism; these are fundamental to ensuring stable shearing.
4.How to optimize parameters from a process perspective?
Tension Control: Maintaining stable tension is crucial; fluctuations should be controlled within ±5%. Unstable tension is a major cause of strip misalignment and uneven trimming.
Alignment Control: Ensure the alignment device (CPC) is sensitive and reliable. If one side of the incoming material is defective and requires more trimming, while the other side is intact, modern production lines support asymmetrical trimming. This involves adjusting the alignment reference so that the disc shear only trims the defective side, thereby improving yield.
Speed Matching: Adjust the shearing speed according to the material. For example, the speed for cold-rolled low-carbon steel is typically 60-80 m/min, while the speed for more brittle silicon steel needs to be reduced to 30-50 m/min.
5.What are the procedures for rapid screening?
Inspect the cutting tools: First, check if the shears are worn, and whether the clearance and overlap settings are reasonable.
Inspect the alignment: Observe whether the strip remains centered on the production line throughout its movement, and whether the alignment and correction system is functioning properly.
Inspect the strip shape: When the line stops, use a ruler or visually inspect the strip shape before trimming for obvious wavy or cambered edges.
Inspect the tension: Check whether the tension display value on the control screen is stable and whether fluctuations are within the acceptable range.