Abstract An improvement in the method of controlling a metal material in a hot-dip metal plating process jetting at least one stream of compressed gas toward the metal plating coating on the surface of the sheet metal material drawn out of a hot-dip bath before said plating coating has solidified. The stream of compressed gas when it collides with the coated sheet metal material forms an upwardly flowing branch stream of gas. The improvement lies in directing at least one stream of ripple eliminating gas at a pressure at least substantially equal to the pressure of the first mentioned stream of compressed gas downwardly and toward the metal plating coating on the surface of the sheet material from a point above the point at which said first mentioned stream of gas is directed at the surface of the sheet material and at a point ahead of, with respect to the direction of advance of the sheet material, the point at which the metal plating coating solidifies and sufficiently close to the point at which the first mentioned stream of gas collides with said sheet material to cancel the upwardly flowing branch stream of gas. The stream of ripple eliminating gas prevents formation of ripple patterns on the plated surface of the sheet material.
The improvement as claimed in claim 1 in which the stream of ripple eliminating gas is directed downwardly at an angle of from 45 to 60* to a normal to the surface of the sheet material, and has an elongated cross sectional shape extending in the direction of the width of the sheet material.
Claim 2
Dependent Claim
49 words
The improvement as claimed in claim 1 in which the point at which the stream of ripple eliminating gas collides with the sheet material is spaced a distance of up to 10 mm. above the point at which the first mentioned stream of gas collides with said sheet material.
Claim 3
Dependent Claim
49 words
The improvement as claimed in claim 3 in which the point at which the stream of ripple eliminating gas collides with the sheet material is spaced a distance of up to 2 mm. above the point at which the first mentioned stream of gas collides with said sheet material.
Claim 4
Dependent Claim
63 words
The improvement as claimed in claim 1 in which the stream of ripple eliminating gas is directed at the sheet material through a nozzle which is spaced a distance of from 100 to 150 mm. from the point at which the ripple eliminating gas collides with the sheet material, said distance being measured in the direction of said stream of ripple eliminating gas.
Claim 5
Dependent Claim
28 words
The improvement as claimed in claim 1 in which the stream of ripple eliminating gas is a gas taken from the group consisting of air and inert gas.
Claim 6
Dependent Claim
15 words
The improvement as claimed in claim 1 in which the ripple eliminating gas is nitrogen.
Claim 7
Dependent Claim
38 words
The improvement as claimed in claim 1 in which the sheet metal material is a strip of cold rolled steel sheet and said hot-dip bath is a metal taken from the group consisting of zinc and zinc alloy.
Claim 8
Dependent Claim
24 words
The improvement as claimed in claim 1 in which the pressure of the stream of ripple eliminating gas is greater than 0.1 kg./cm.2 gauge.
Claim 9
Dependent Claim
25 words
The improvement as claimed in claim 9 in which the pressure of the stream of ripple eliminating gas is from 0.3 to 5 kg./cm.2 gauge.
Claim 10
Dependent Claim
47 words
The improvement as claimed in claim 1 wherein there are a plurality of said first mentioned streams of compressed gas and a plurality of ripple eliminating streams of compressed gas, there being one stream of ripple eliminating gas for each of said first mentioned streams of gas.