A sunken roll preheating method with sufficient preheating and uniform heating

Abstract

The present invention discloses a heat sink roll preheating method with full preheating and uniform heating. The method is as below: A, hanging a sink roll into a preheating box, preheating at the speed of 40-60 DEGC / h, insulating for 2-2.5 h when the temperature rises to 180-220 DEG C, then preheating at the speed of 90-110 DEG C / h for 2-2.5 h to 380-420 DEG C; B, insulation: insulating for 2-2.5 h after step A, and then cooling in the furnace to 25-40DEG C, so as to eliminate the thermal stress generated in an assembly process and the preheating process; and C, secondary preheating: 8-9 h before the usage of the sink roll, preheating at a speed of 40-60 DEG C / h to 200DEG C, insulating for 2-2.5 h, then preheating at a speed of 90-110DEG C / h for 2 to 380-420DEG C, and insulating for 1-1.5 h. The invention uses a secondary preheating mode to achieve uniform preheating temperature, uniform expansion and uniform surface tissue change of the sink roll, improves the corrosion resistance of the roll in galvanizing zinc, and reduces the probability of forming zinc-iron alloy particles on the sink roll surface and the groove.

Description

technical field [0001] The invention belongs to the technical field of sinking roll preheating, and in particular relates to a sinking roll preheating method with sufficient preheating and uniform heating. Background technique [0002] The sinking roll is one of the important parts of the hot-dip galvanizing line. During the production period, it is immersed in the zinc liquid at about 465°C. The roller rotates at the same speed as the running strip in the zinc liquid, and is eroded by the zinc liquid to form a zinc-iron alloy. Particles adhere to the roller surface, causing pits on the surface of the galvanized sheet, which affects the quality of the galvanized sheet. Currently, the sinking roller must be replaced after 10-15 days of use. If the preheating is not good, it must be replaced in 5 days. The cost of changing the roller is about 50,000 yuan. At the same time, waste and defective products are produced, more energy media are consumed, and the number of roll changes...

AI Technical Summary

Problems solved by technology

After use, it was found that this preheating method caused insufficient preheating of the rollers, uneven heating of the roller bearings and bushings, and incomplete and uneven expansion due to different expansion coefficients in a short period of time.

After 3-5 days in the zinc pot, pits on the surface of the galvanized sheet and poor rotation of the rollers began to appear, and product roll marks and pit defects appeared after galvanizing

Images