JP2848074B2 - Galvanizing steel strip alloying equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot dip galvanized steel strip alloying apparatus for producing a galvannealed steel strip by alloying a hot dip galvanized steel strip.

[0002]

2. Description of the Related Art An alloyed hot-dip galvanized steel strip is more excellent in paintability and weldability than a hot-dip galvanized steel strip, so that a high corrosion resistance is required and a high welding strength is required. It is used for steel plates for automobiles that require workability.

[0003] The alloyed hot-dip galvanized steel strip described above is
5 is manufactured by the steps shown in. That is, molten zinc 2
Steel strip 2 immersed in hot-dip galvanizing tank 22 filled with 1
3 is moved upward by the sink roll 24 and is lifted upward. The amount of zinc adhering to the front and back surfaces of the steel strip 23 increases almost in proportion to the pulling speed from the hot-dip galvanizing tank 22, so that in general, excess zinc tends to adhere. Zinc is squeezed out by blowing high-pressure gas such as air or nitrogen gas by a wiping nozzle 25 provided above the hot-dip galvanizing tank 22.

[0004] The hot-dip galvanized steel strip 26 to which a predetermined amount of zinc has adhered is led into a heating furnace 28 for alloying through a touch roll 27 and heated to about 500 to 600 ° C by a high-temperature gas. After that, the heat is kept at a constant temperature, which is the preserving zone 29, and further cooled in the cooling zone 30 provided above the preserving zone 29, to form the alloyed hot-dip galvanized steel strip 31 and disposed above the cooling zone 30. The traveling direction is changed from the vertical direction to the horizontal direction by the top roll 32, and the process proceeds to the next step.

[0005]

However, when an alloyed hot-dip galvanized steel strip is manufactured by an alloying facility such as the above-mentioned conventional alloying furnace, there are the following problems. That is, since the high-temperature gas generated in the alloying furnace rises upward (rearward), there are the following problems.

(1) It is difficult to control heat retention as needed. (2) Cooling from immediately after the exit from the heating furnace for alloying is impossible due to the rising high temperature gas. (3) In order to control to the required heat pattern, it is necessary to measure the temperature of the hot-dip galvanized steel strip on the exit side of the heating furnace for alloying. Difficult to measure. For this reason, the iron content in the alloyed hot-dip galvanized film is too high, and the performance called powdering resistance is degraded. The steel sheet is pressed against the surface of the steel strip to generate flaws (referred to as star flaws), or the temperature exceeds the proper alloying temperature, so that the film crystals become coarse and cannot satisfy the quality requirements of consumers.

The present invention solves the above-mentioned problems of the prior art, and enables not only heat retention but also cooling to be started from the outlet of the alloying furnace, and a hot-dip galvanized steel strip which can adopt various heat patterns. The purpose of the present invention is to provide an alloying facility.

[0008]

According to the present invention, there is provided an alloying apparatus for a hot-dip galvanized steel strip, which comprises an alloying furnace so that subsequent equipment is not thermally affected by the generated high-temperature gas. After that, a cooling zone and a tropical zone are provided in parallel, and it is possible to select either to immediately cool the hot-dip galvanized steel strip heated by the alloying furnace or to keep the heat for a certain time before cooling.

[0009]

The hot-dip galvanized steel strip alloying equipment according to the present invention has an alloying furnace configured to prevent the subsequent equipment from being thermally affected by the generated high-temperature gas, and has a cooling zone behind the alloying furnace. In parallel with the preservation zone, the hot-dip galvanized steel strip heated by the alloying furnace can be cooled immediately or kept for a certain time before cooling. Therefore, there are various heat patterns, from the heat pattern in which the hot-dip galvanized steel strip is heated at a high temperature for a short time in an alloying furnace and then cooled immediately, to the heat pattern in which a long time is heated and kept at a low temperature and then cooled. Can be selected, and an alloying process according to the purpose can be performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A galvanizing steel strip alloying equipment according to one embodiment of the present invention will be described with reference to FIG. An apparatus for alloying a hot-dip galvanized steel strip according to one embodiment of the present invention includes an alloying furnace 1 provided above a hot-dip galvanizing tank 22 and a wiping nozzle 25, and a hot-dip galvanizing provided above the alloying furnace 1. A first cooling zone 2 and a first preservation zone 3 which can be switched by sliding in a direction orthogonal to the pass line of the steel strip, and a first cooling zone 2
A second cooling zone 4 and a second cooling zone 5 which are slidable in the direction orthogonal to the pass line and connected to the first zone 3 and which can be switched, and a third cooling zone 6 and a fourth zone fixedly provided. And a belt 7.

The alloying furnace 1 employs an induction heating type heating furnace which does not have a thermal effect on a subsequent process, or, in the case of a gas heating type alloying furnace, a subsequent cooling by a generated high temperature gas. The furnace has a sealed structure so that the belt and the tropical zone are not affected by heat, and the generated high-temperature gas is discharged through a duct.

FIG. 2 is an explanatory view showing an example of a seal structure of a gas heating type alloying furnace. On the outlet side near the first cooling zone 2 or the first holding zone 3 of the alloying furnace 1, a negative pressure chamber 11 that becomes a negative pressure with respect to the atmospheric pressure is provided, and the negative pressure chamber 11 is blown (not shown). To the place where the heat does not affect the first cooling zone 2 or the first preservation zone 3 by sucking the high-temperature in-furnace gas having a positive pressure with respect to the atmospheric pressure of the alloying furnace 1. Is what you do.

FIG. 3 is an explanatory view showing another example of the seal structure of the gas heating type alloying furnace. A negative pressure chamber 12 is provided on the outlet side of the alloying furnace 1 and a positive pressure chamber 13 is provided on the inlet side. The side of the negative pressure chamber 12 and the positive pressure chamber 13 which communicates with the atmosphere has a labyrinth structure to prevent the intrusion of the atmosphere and the leakage of gas in the furnace. Then, a high-temperature furnace gas is sucked into the negative pressure chamber 12 by the blower 14, and the sucked furnace gas is sent to the positive pressure chamber 13.

In the galvanizing steel strip alloying equipment described above, the following cases can be selected as the route of the hot-dip galvanized steel strip after leaving the alloying furnace. 1st tropical zone-2nd tropical zone-3rd cooling zone-4th cooling zone (low temperature and long heating type) 1st tropical zone-2nd cooling zone-3rd cooling zone-4th cooling zone (intermediate heating type) First cooling zone-second cooling zone-third cooling zone-fourth cooling zone (high-temperature, short-time heating type) In this embodiment, two zones can be switched between the tropical zone and the cooling zone. By increasing the number of zones that can be switched, it is possible to select a route that is equal to or greater than the above-described route and, consequently, select a heat pattern.

FIG. 4 is a graph showing a heat pattern of the galvannealed steel strip manufactured by the galvanizing steel strip alloying equipment. The dotted line is 495-520 ° C
The alloyed hot-dip galvanized steel, which is heated at a high temperature and continuously cooled from the first cooling zone to the fourth cooling zone to prevent over-alloying, and is excellent in press formability and powdering resistance Suitable for the production of belts. The solid line is obtained by heating to 495 ° C. or lower in an alloy furnace, keeping the temperature in the first and second preserving zones, and then cooling in the third and fourth cooling zones. Suitable for the production of galvannealed steel strip with excellent powdering resistance. In addition, the temperature of the steel strip near the top roll is 350 to 400 ° C. in order to prevent the occurrence of a flaw due to seizure on the top roll.
Since it is necessary to lower the temperature to the following level, only the cooling zone is required near the top roll.

[0016]

According to the present invention, an alloyed hot-dip galvanized steel strip having a required degree of alloying and a coating structure can be manufactured.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a galvanizing steel strip alloying facility according to one embodiment of the present invention.

FIG. 2 is an explanatory view showing an example of a seal structure of a gas heating type alloying furnace.

FIG. 3 is an explanatory view showing another example of a seal structure of a gas heating type alloying furnace.

FIG. 4 is a graph showing a heat pattern using the hot-dip galvanized steel strip alloying equipment of one embodiment of the present invention.

FIG. 5 is an explanatory view showing a conventional method for producing a galvannealed steel strip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Alloying furnace 2 1st cooling zone 3 1st holding zone 4 2nd cooling zone 5 2nd holding zone 6 3rd cooling zone 7 4th cooling zone 11 Negative pressure room 12 Negative pressure room 13 Positive pressure room 14 Blower

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoichi Miyagawa 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Naohiko Ide 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Examiner Mitsuo Teramoto, Inc. (56) References JP-A-2-122058 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C23C 2/00-2/40

Claims (1)

(57) [Claims] 1. An alloying furnace is configured so that the subsequent equipment is not thermally affected by the generated high-temperature gas, and a cooling zone and a preservation zone are provided in parallel behind the alloying furnace, and the alloying furnace is heated by the alloying furnace. Cooling the hot-dip galvanized steel strip immediately or
A hot-dip galvanized steel strip alloying facility characterized in that it is possible to select whether to keep heat for a certain time and then cool.