JPS5950161A - Manufacture of one-side hot-dipped steel plate - Google Patents

Abstract

PURPOSE:To manufacture efficiently a non-side hot-dipped steel plate of superior quality, by passing a steel plate coated with a hot dipping inhibitor on one side through an annealing furnace heated to a higher temp. than the set temp. in regular baking work to bake the inhibitor and by dipping the steel plate in a hot dipping vessel. CONSTITUTION:At the beginning of line operation, the amount 19' of gaseous fuel to be fed to an annealing furnace is increased as compared to the conventional amount 19 of gaseous fuel to make the furnace temp. 20' higher than the conventional furnace temp. 20. At the time 21 when a steel plate coated with a hot dipping inhibitor on one side begins to enter the annealing furnace, the furnace temp. t21 is made higher than the set furnace temp. tN in regular baking work. Conventional under baking due to a drop in the furnace temp. is prevented, and the productivity and yield can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a single-sided plated steel plate, and more particularly to a method for producing a single-sided plated steel plate using the so-called inhibitor method.

A method for producing a single-sided galvanized copper plate, which is referred to as the inhibitor method, according to the present invention will be explained by taking the case of a single-sided galvanized steel plate as an example. Figure 1 shows an overall diagram of the inhibitor type single-sided galvanizing line. In the figure, 1 is a steel plate, 2 is a payoff reel, 3.13, 7 is a looper, 4 is a cleaning, 5 is a roll coke for applying a plating inhibitor to the steel plate 1, 16 is a pre-drying furnace, 7 is an annealing furnace, 8 is a zinc roll, 9 is a zinc pot, 10 is a wiper, 11 is a cooling device, 12
1 is a blocking layer removing device, 14 is a skin pass mill, 15 is a tension leveler, 16 is a chemical conversion treatment device, and 18 is a tension reel.

The surface of the steel plate 1 unwound from the payoff reel 2 is cleaned by a cleaning 4, and then a plating inhibitor is applied only to one surface by a roll coater 5. The plating inhibitor is usually an inorganic liquid mainly composed of water glass, and the steel plate 1 coated with this inhibitor is placed in a pre-drying oven 6.
The moisture in the inhibitor is removed in the annealing furnace 7, and then the annealing furnace 7
The steel plate 1 is heated to a temperature close to .degree. C., and a plating detergent is baked into a glass-like form over the entire surface of the steel plate 1 coated with the inhibitor.

Meanwhile, the side and first plate materials are also heated and heat treated at the same time.

After this, the steel plate I was immersed in 1/c lead bot 9, and the zinc plating was removed by hm on the surface of gII+ which had not been coated with an inhibitor.

With the wiper 10, the amount of zinc deposited on the galvanized surface can be adjusted to an appropriate value, and on the side where the plating inhibitor has been baked, the saliva attached to the plating inhibiting layer of the steel plate 1 can be wiped away by flame, jet gas, etc. be dropped.

cooled, applying zinc on one side and anti-glaze on the other;
p7. on one side of the fired second plate l. The blocking layer 1 which has been cut off and formed is removed by a blocking layer removing device 12. As a result, ((1) the plate 1 becomes a single-sided galvanized steel plate. Fired plating 1<1
'i, , +h layers are folded with benzoinoglol, (
÷9A1+ is formed so that it is peeled off from the surface of the plate 1 and removed by brushing with a plan roll. Thereafter, the skin bath mill 14 is used to give the specified surface roughness, and the steel plate 1 is processed to remove any defects in shape such as L and C scratches using a tensor roller 15.
Wind the peak with the angion reel 18.

A single-sided galvanized steel sheet is manufactured by IlJ through the step e as explained above, but depending on the heating temperature of the steel sheet in the annealing furnace 7 in this step, the I There is a risk that zinc may remain on the surface of the flllll to which the agent has been baked, or the closing layer itself may remain without being completely removed by the blocking layer removal device fffr, 12.

Of course, if this plating lX11 inhibitor coating or coating with an anti-plating layer remains on the surface, the product will be defective. If 4 remains, the plating blocking layer will adhere to the equipment after the tilt stopper removal device 12, such as the looper 13.170 roll, the -t-tr-trs skin bath mill 14. h: F, Steel 4/T 1 Since this may cause scratches, it is necessary to immediately stop the line and inspect all rolls. This inspection process requires many people and a long time, and when manufacturing galvanized steel sheets, especially single-sided galvanized steel sheets, the steel sheets need to be heat treated at an appropriate temperature, so the furnace conditions of the annealing furnace 7 are The steel sheets 1 produced before stabilization will not become products, and this will have a significant impact on the yield of non-defective products, so stopping the line will significantly reduce productivity. Furthermore, it is difficult to heat the steel plate while it is stopped in the furnace because the steel plate may break in the furnace.

Therefore, when starting the line, the fuel is adjusted while passing through the steel plate, which is not coated with a plating ISI inhibitor, at a predetermined speed, and when the target furnace temperature is reached, the coating of the plating inhibitor is started. That's what I do. However, in the conventional method in which coating is started when the target furnace temperature is reached, the phenomenon that the plating prevention layer on the steel plate l immediately after the coating starts remains without being peeled off often occurs. This situation will be explained using drawings. FIG. 2 is a conventional drilling model diagram (time chart) for manufacturing single-sided galvanized steel sheets.

In FIG. 2, reference numeral 19 indicates the transition of the fuel gas h1', 20 indicates the transition of the furnace temperature, and 21 indicates the time at which the steel plate coated with the anti-plating agent starts to enter the annealing furnace 7. As the fuel gas increases, the furnace temperature rises and reaches the set temperature at 1. However,
Immediately after the steel plate coated with the plating inhibitor enters the annealing furnace 7, the furnace temperature drops rapidly as shown in section A of FIG. Therefore, in order to maintain the set temperature, fuel gas must be added. However, it was found that due to this rapid decrease in furnace temperature, a sticking prevention layer remained on the steel plate 1 that passed through the furnace until the furnace temperature recovered to the set temperature.

The present invention was made to solve this problem, and its purpose is to provide a method that can efficiently produce single-sided plated steel sheets of excellent quality.

The present invention provides single-sided plating, which includes the steps of applying a plating inhibitor to one side of a steel sheet, passing it through an annealing furnace, baking the plating inhibitor onto the surface of the copper sheet in the furnace, and then immersing the steel sheet in a hot-dip plating tank. (In the method for manufacturing 1'1 plate, the furnace temperature of the annealing furnace immediately before the steel plate coated with the plating β11 inhibitor enters is set higher than the furnace temperature set during steady baking work. This achieves the above objective.

The present invention will be explained below based on the drawings.

FIG. 3 is an operational model diagram of the present invention in the case of producing a single-sided galvanized plate. In FIG. 3, 19'iJ:
20' shows the change in the amount of fuel gas, and 20' shows the change in the furnace temperature. +9.
20U: Each single-sided galvanized steel sheet shown in Figure 2 is j! ! ! This is a graph of the conventional fuel gas amount and furnace temperature trends when manufacturing.

As shown in FIG. 3, at the same time as the line operation starts, the fuel gas is increased and the furnace temperature is raised, but in the present invention, the steel plate coated with the anti-stick agent starts to enter the annealing furnace 7 at time 21. The furnace temperature t□ is set higher than the set furnace temperature tN during steady baking (=J) operation.This prevents plating Is!1 and residual d-agent from occurring due to a decrease in furnace temperature as in the conventional method. In this case, the furnace temperature is below 20°C!1
- At temperatures above 60°C, a plating prevention layer remains, and at temperatures above 60°C, Q
If the temperature is too high, the plating prevention layer will peel off and the yP will become low.
It has been found that better results can be obtained by setting the furnace temperature more preferably higher than the set temperature of about 40°C. When the plating inhibitor is applied in this way, the emissivity (ε) of the steel plate surface changes from small to large, so the amount of heat absorbed by the steel plate changes. Therefore, by setting the furnace temperature slightly higher than the estimated furnace temperature, it is possible to reduce fluctuations in the actual furnace temperature with respect to the set furnace temperature. This solves the problem of residual peeling.

Furthermore, 11] of the copper plate to be plated is 10001117
If it is about 1, then the optimum furnace temperature for straight work when the plating inhibitor is applied and the lζ steel sheet starts entering the annealing furnace, for example, the set furnace temperature is kept at about 40°C. It was confirmed that no residue was generated due to peeling of the blocking layer, but when the thickness of the steel plate becomes wider between 1,400 and 1,500, the number of heat-absorbing F points on the steel plate increases, and the steel plate coated with the plating inhibitor increases. When entering the annealing furnace, the amount of furnace temperature drop becomes large, and the plating prevention layer remains! It has been found that there are cases in which the lower limit of the temperature at which this occurs can be determined.

This phenomenon occurs because conventional furnace temperature control throttles the fuel when the actual furnace temperature is higher than the furnace temperature to be controlled, and opens the fuel control valve when the actual furnace temperature is lower. This is because there is a time lag between when the fuel decreases or increases, and it is difficult to quickly respond to large changes in furnace temperature.

Therefore, the present inventors have found that it is effective to increase the amount of fuel gas corresponding to the set furnace temperature 2 to 3 minutes before the time when the steel plate coated with the plating inhibitor starts to enter the annealing furnace. This was further confirmed by experiment. In order to perform this control, the conventional feedback method after detecting the furnace temperature is not sufficient, so the input heat charge is adjusted in advance according to the heat h'1 calculated from the steel plate dimensions and line speed. It is preferable to use a feed-forward method that provides training. Time 0 when the steel plate coated with inhibitor starts entering the annealing furnace
By performing the fuel control operation only once 2 to 3 minutes beforehand, I was able to perform this operation with ease.

In this way, during the period when the emissivity (ε) of the steel plate surface coated with the inhibitor changes greatly from small to large, In addition, by starting the control of fuel 1, it is possible to reduce fluctuations in the actual furnace temperature with respect to the set furnace temperature, and it is possible to reduce the amount of peeling of the coating (lLt stop layer) on the surface of the steel sheet after galvanizing. This problem has been solved.This has greatly contributed to improving productivity and hX yield.

Note that the present invention is not limited to the production of single-sided galvanized steel sheets, but also single-sided galvanized steel sheets that use a plating inhibitor method! QQ plate, for example, single-sided plating such as single-sided nickel-plated steel plate? (Can be used on one board.

A single-sided galvanized steel sheet was produced under the above conditions, and a beautiful single-sided galvanized steel sheet was obtained on both the front and back surfaces.

Comparative Example 1 A single-sided galvanized steel plate using the inhibitor method was fabricated under the conditions shown in Table 2.
Zinc adhesion occurred in No. 1, and the blocking layer was not peeled off in this area.

8L of single-sided galvanized steel plate under the conditions shown in Table 3! ! When fabricated, a single-sided galvanized steel plate was obtained that was solid on both the front and back sides.

In this example, the gas (C gas) is supplied into the furnace 2 minutes before the 19b portion coated with the plating inhibitor starts to fully enter.
From 1000 Nm3/Hr to 1400 Nm3/
The amount of HrVC was increased.

Comparative Example 2 A single-sided galvanized steel sheet using an inhibitor method was produced under the conditions shown in Table 4. However, zinc adhesion occurred over approximately 3071 mm on the side of the steel sheet coated with the plating inhibitor fjc, and this area was unable to prevent plating. The layers did not peel off either.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an inhibitor type single-sided galvanizing line, FIG. 2 is a conventional operational model diagram, and FIG. 3 is an operational model diagram of the present invention. l... Steel plate, 2... Payoff reel, 3... Looper, 4... Cleaning, 5... Roll coke-16... Pre-drying oven, 7...
...Annealing furnace, 8...Zinchlor, 9.
... Zinc pot, lO ... wiper, 11.
... Cooling 1 only 1.12 ... Blocking layer removal device, 1
3... Looper 14... Skin pass mill,
15... Tension leveler, +6... Chemical conversion treatment device, 17... Looper, 18...
...Tension reel, 19.. Transition of fuel gas level, 20.. Transition of furnace temperature, 21.. Inhibitor application start time. Agent Tatsuyuki Unuma (and 2 others)

Claims (2)

[Claims] (1) Single-sided plated steel sheet, which involves the process of applying a plating inhibitor to one side of the steel sheet, passing it through an annealing furnace, baking the plating inhibitor onto the surface of the steel sheet in the furnace, and then immersing the steel sheet in a hot-dip plating bath. Single-sided plating, characterized in that the furnace temperature of the annealing furnace immediately before the steel plate coated with the plating inhibitor enters is higher than the furnace temperature set during normal baking work. Method of manufacturing steel plates. (2) A patent characterized in that the furnace temperature of the annealing furnace immediately before the steel plate coated with the plating inhibitor enters is set at a temperature of 20 to 60 degrees Celsius during steady baking work. A method for producing a single-sided plated steel sheet according to claim 1.