NS blade / Advanced Air Knife for Hot Dip Continuous Galvanizing Line

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1 NS blade / Advanced Air Knife for Hot Dip Continuous Galvanizing Line NS means Nippon steel & Sumikin engineering. Hatsuki KAKUNO Makoto KATSUBE Muneshige OGAWA NIPPON STEEL & SUMIKIN ENGINEERING CO., LTD., JAPAN

2 1. Difficulty of High Speed CGL Operation Generation of edge splash and top dross loss in High Speed Operation Air knife Strip Generation of edge splash leads to the loss of zinc consumption. 1 Top dross loss 2Difficulty in thin coating Zinc pot As Line Speed increases, zinc-takeout pulled by strip increases. 3Edge over coat Strip Coating target Over Coat 2

3 1. Difficulty of High Speed CGL Operation Generation of edge splash in High Speed Operation 3

4 1. Difficulty of High Speed CGL Operation Ordinary nozzle Jet collision issue Wiping width(> Strip width) Jet collision Wiping gas flow Strip Nozzle Impinging jet Splash edge over coating 4

5 1. Difficulty of High Speed CGL Operation Baffle plate issue Wiping width(> Strip width) Wiping gas flow Strip Nozzle Edge baffle plate Ineffective condition Less than 5mm 5

6 2. Features of NS blade Configuration of NS blade Air knife NS blade Wiping gas flow Wiping nozzle Tracking NS blade Strip Cross section of nozzle 6

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8 2. Features of NS blade BLADE Wiping width ( Strip width) Wiping gas flow NS blade advantage 1. Non contact baffle setting Safety for high speed operation Nozzle Position variable 2. According to the jet effect, EOC and splash shall be avoided even at high speed operation *EOC: Edge over coating 8

9 High speed coating test using NS blade Schematic of experiment apparatus Air pressure Sound meter Nozzle gap Nozzle 1.5m Camera Strip width Strip thickness :280mm :0.71mm Zinc temperature :460 9

10 3. High speed coating test using NS blade Test results 1 / Edge splash (Front view and side view) Wiping nozzle Edge splash Reduce Edge Splash Front view Side view Front view Side view (a) Ordinary nozzle (b) NS blade 10

11 3. High speed coating test using NS blade Test results 1 / Edge splash (Front view and side view) Without NS blade With NS blade 11

12 3. High speed coating test using NS blade Flow velocity vector Z Z X Y X Y 12

13 Coating weight 3. High speed coating test using NS blade Test results 2/ Coating thickness distribution +60% +40% Coating weight distribution (near the strip edge) Edge over coat F w/o EB without BLADE (F) Strip B w/o EB without BLADE (B) +20% F With EB with BLADE (F) Target -20% Distance from strip edge (mm) with BLADE (B) B with EB Very little variation in the coating weight NS blade is effective in prevent of Edge over coat and allow thin coating 13

14 3. High speed coating test using NS blade Test results 3/ Noise level Improve Noise level 14

15 4. Commercial line test Operation condition Galvanizing Line Coil spec. 0.23mm thick X 914mm width 55%Aluminum+Zinc coating line 0.35mm thick X 1200mm width Line 160mpm 150mpm speed Coating Z08(40g/m 2 per side) AZ40(20g/m 2 per side) thickness Splash None None Overcoat None None Noise 105dB 100dB 15

16 Relateive Coating thickness[%] 4. Commercial line test Coating weight distribution NS blade Ordinary nozzle Left side Distance from strip edge [mm] Right side 16

17 5. Conclusion Coating test at test line Reduce EOC, noise level and zinc splash Without NS blade With NS blade Commercial line operation (GI and 55% Al+Zinc bath) Achieve maximum line speed and minimum coating weight operation 17

18 Thank you for your attention. 18