Coating weight control apparatus and coating weight control method

Patent metadata

Field	Value
Publication number	US-11525177-B2
Application number	US-202117405193-A
Country	US
Kind code	B2
Filing date	Aug 18, 2021
Priority date	Dec 28, 2018
Publication date	Dec 13, 2022
Grant date	Dec 13, 2022

Abstract

A coating weight control apparatus includes: a strip passing position movement amount estimate part configured to estimate an movement amount of a strip passing position, in response to any of activation factors for movement of a strip passing position, that is, a welding point passing, a change in tension, and an operation of a correcting roll; and a nozzle position control part configured to shift each of positions of a front side nozzle and a back side nozzle by an amount corresponding to the movement amount of the strip passing position estimated by the strip passing position movement amount estimate part.

First claim

The invention claimed is:

1. A coating weight control method performed by a coating weight control apparatus that provides control on a coating plant in which a series of continuously-fed strips in which two adjacent strips are welded at a welding point: are immersed in a pot of a hot-dip coating bath so as to coat the strips with the hot-dip coating bath; are removed therefrom; are sprayed with gas from each of a front side nozzle and a back side nozzle facing a front side and a back side of the strips, respectively; and are subjected to removal of excessive hot-dip coating bath, to thereby coat the strips with the hot-dip coating bath in a desired thickness, the coating weight control apparatus including a coating weight prediction model, a controller, and a strip passing position movement amount estimate part, the coating weight prediction model describing relationships among a speed of the strips, respective pressures of the nozzles, respective distances between each of the nozzles and the strips, and a coating weight which is an amount of the hot-dip coating bath coated on the strips, the coating weight control method comprising:
the step, performed by the controller, of controlling at least one of the pressures of the nozzles and respective positions of the nozzles such that, by referencing the coating weight prediction model, the coating weight of the hot-dip coating bath coated on the strips takes a desired value;
the step, performed by the strip passing position movement amount estimate part, of estimating a movement amount of a strip passing position, the strip passing position being a position at which the strips pass through with respect to a height of the any one of the nozzles, when at least one of the following changes, (1) thicknesses between two adjacent strips across a welding point, (2) tensions of the strips, and (3) a position of a correcting roll that supports the strips in the pot, and of outputting the estimated movement amount to the controller; and
the coating weight control method performed by the coating weight control apparatus further including at least one or more of: a welding point passing detection part configured to detect whether or not the welding point passes through a prescribed position of the coating plant; a tension change detection part configured to detect whether or not there is a change in the tensions of the strips; and a correcting roll position operation detection part configured to detect whether or not the correcting roll position has been operated, the strip passing position movement amount estimate part being activated in accordance with the result detected by any of the welding point passing detection part, the tension change detection part, and the correcting roll position operation detection part, the coating weight control method further comprising the step, performed by the strip passing position movement amount estimate part, of estimating a movement amount of a strip passing position.

2. The coating weight control method according to claim 1 , further comprising: the step, performed by the strip passing position movement amount estimate part, of, when activated by the welding point passing detection part, estimating the movement amount of the strip passing position by a computing using at least one of thicknesses of two welded adjacent strips, strengths thereof, tensions thereof, and a position of the correcting roll, the step, performed by the strip passing position movement amount estimate part, of, when activated by the tension change detection part, estimating the movement amount of the strip passing position by a computing using any of amounts of a tension change of the strips, thicknesses thereof, strengths thereof, and a position of the correcting roll, and the step, performed by the strip passing position movement amount estimate part, of, when activated by the correcting roll position operation detection part, estimating the movement amount of the strip passing position by a computing using any of thicknesses of the strips, strengths thereof, tensions thereof, a position of the correcting roll before being operated, and a position thereof after being operated.

3. The coating weight control method according to claim 1 , the coating weight control method performed by the coating weight control apparatus including the controller, the controller further including a nozzle position control part configured to control respective positions of the nozzles, the coating weight control method comprising the step, performed by the nozzle position control part, of shifting each of the positions of the nozzles in a direction in which the strip passing position changes, by a value corresponding to the movement amount of the strip passing position outputted by the strip passing position movement amount estimate part.

4. The coating weight control method according to claim 2 , the coating weight control method performed by the coating weight control apparatus including the controller, the controller further including a nozzle position control part configured to control respective positions of the nozzles, the coating weight control method comprising the step, performed by the nozzle position control part, of shifting each of the positions of the nozzles in a direction in which the strip passing position changes, by a value corresponding to the movement amount of the strip passing position outputted by the strip passing position movement amount estimate part.

5. The coating weight control method according to claim 3 , the coating weight control method performed by the coating weight control apparatus further including an allowable nozzle gap input part configured to allow input of minimum allowable distances between each of the nozzles and the strips, the coating weight control method further comprising the steps, performed by the nozzle position control part, of: calculating instructions for the control of the nozzle positions; determine a point situated in each of the front side nozzle and the back side nozzle, the point being the closest to the strips, when the nozzle position control instructions are calculated; and computing a distance between each of the points and the strips as a first distance; if the first distance is smaller than the minimum distance inputted from the allowable nozzle gap input part, adding a second distance to the nozzle position control instructions, the second distance being obtained by subtracting the first distance from the minimum distance, and outputting the resultant instructions; and if the first distance is not smaller than the minimum distance inputted from the allowable nozzle gap input part, outputting the nozzle position control instructions as they are.

6. The coating weight control method according to claim 4 , the coating weight control method performed by the coating weight control apparatus further including an allowable nozzle gap input part configured to allow input of minimum allowable distances between each of the nozzles and the strips, the coating weight control method further comprising the steps, performed by the nozzle position control part, of: calculating instructions for the control of the nozzle positions; determine a point situated in each of the front side nozzle and the back side nozzle, the point being the closest to the strips, when the nozzle position control instructions are calculated; and computing a distance between each of the points and the strips as a first distance; if the first distance is smaller than the minimum distance inputted from the allowable nozzle gap input part, adding a second distance to the nozzle position control instructions, the second distance being obtained by subtracting the first distance from the minimum distance, and outputting the resultant instructions; and if the first distance

Assignees

• Hitachi Ltd
• Nippon Steel Nisshin Co Ltd

Inventors

• Kayama Masahiro
• Kurihara Shigetoshi
• Iwahiro Takanori
• Morishita Hisao
• Soga Kazuhiko
• Hirano Yuta

Classifications

• C23C2/20 Primary

  Strips; Plates · CPC title

• C23C2/40

  Plates; Strips · CPC title

• C23C2/003

  Apparatus · CPC title

• B05C3/02

  the work being immersed in the liquid or other fluent material · CPC title