Continuous hot-dip metal plating device and continuous hot-dip metal plating method
A continuous hot-dip plating machine includes: a sink roll provided in a plating bath and configured to upwardly change a transfer direction of the steel strip; a first support roll provided in the plating bath and located above the sink roll, the first support roll being in contact with a first surface of the steel strip in contact with the sink roll; and a second support roll provided in the plating bath and located above the first support roll, the second support roll being in contact with a second surface of the steel strip opposite the first surface. A diameter of the first support roll, a diameter of the second support roll, and a vertical distance between a rotation axis of the first support roll and a rotation axis of the second support roll satisfy specific conditions.
1. A continuous hot-dip plating machine comprising:
a plating bath;
a sink roll provided in the plating bath and configured to upwardly change a transfer direction of a steel strip;
a first support roll provided in the plating bath, the first support roll being positioned above the sink roll and in contact with a first surface of the steel strip in contact with the sink roll; and
a second support roll provided in the plating bath, the second support roll being positioned above the first support roll and in contact with a second surface of the steel strip opposite the first surface, wherein
a diameter of the first support roll, a diameter of the second support roll, and a vertical distance between a rotation axis of the first support roll and a rotation axis of the second support roll satisfy conditions represented by formulae (1) to (4) below,
D
=
D
2
-
0.376
D
1
(
1
)
420
-
0.839
L
≤
D
≤
445
-
0.655
L
(
2
)
D
1
≥
210
(
3
)
D
1
+
D
2
≤
1000
-
2
L
+
2
(
20
-
D
1
2
)
2
(
4
)
where:
D 1 represents the diameter (mm) of the first support roll,
D 2 represents the diameter (mm) of the second support roll, and
L represents the vertical distance (mm) between the rotation axis of the first support roll and the rotation axis of the second support roll, and
wherein a lower end of the first support roll is spaced apart from an upper end of the sink roll by 200 mm or more.
2. The continuous hot-dip plating machine according to claim 1 , further comprising: an adjuster configured to adjust a vertical position of the first support roll.
3. A continuous hot-dip plating method comprising:
upwardly changing a transfer direction of a steel strip using a sink roll provided in a plating bath;
passing the steel strip through between a first support roll and a second support roll, the first support roll being provided in the plating bath at a position above the sink roll and in contact with a first surface of the steel strip in contact with the sink roll, the second support roll being provided in the plating bath at a position above the first support roll and in contact with a second surface of the steel strip opposite the first surface; and
adjusting in advance a vertical position of the first support roll so that a diameter of the first support roll, a diameter of the second support roll, and a vertical distance between a rotation axis of the first support roll and a rotation axis of the second support roll satisfy conditions represented by formulae (1) to (4) below,
D
=
D
2
-
0.376
D
1
(
1
)
420
-
0.839
L
≤
D
≤
445
-
0.655
L
(
2
)
D
1
≥
210
(
3
)
D
1
+
D
2
≤
1000
-
2
L
+
2
(
20
-
D
1
2
)
2
(
4
)
where:
D 1 represents the diameter (mm) of the first support roll,
D 2 represents the diameter (mm) of the second support roll, and
L represents the vertical distance (mm) between the rotation axis of the first support roll and the rotation axis of the second support roll, and
wherein a lower end of the first support roll is spaced apart from an upper end of the sink roll by 200 mm or more.