JPS5838492B2 - Continuous annealing equipment for surface treatment original plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous annealing apparatus for surface treatment blanks, and more particularly to a continuous annealing apparatus that can be applied to all blanks for tinplate, regardless of the hardness level of the product.

Along with galvanized iron sheets, tinplate is a typical surface-treated steel material.
It is manufactured by rolling an original sheet to a desired thickness, annealing it, skin-pass rolling it, and tin-plating it.

However, tinplate usually has a hardness of T-1 to T-.
It is known that it is classified into a temper grade of 6.

Conventionally, in the annealing process of tin plates, soft systems (T-1 to T-3)
A two-system manufacturing process is used: box type annealing is used for hard types (T-4 or higher), and continuous annealing is used for hard types (T-4 or higher).

That is, in the past, it has been considered difficult to manufacture softer tin plates using ordinary capped steel or aluminum killed steel materials by continuous annealing.

For this reason, in the conventional manufacturing of tinplate plates, the process becomes complicated, delivery date management is complicated due to the difference in the number of manufacturing days between the two systems,
In addition to the variations in quality due to box annealing, there are various problems such as the need to adjust the composition at the steel material stage according to each temper grade. There was a strong desire to establish a manufacturing method for this.

In order to solve these problems in the conventional manufacturing method of tinplate blanks, the present inventors conducted various research and found that
By controlling the material quality by controlling the elongation rate during skin pass rolling, it is possible to simplify or consolidate the materials, and by continuously annealing all temper grades, it is possible to produce high-quality tin plates at low cost and with high efficiency. The method has been perfected.

It is an object of the present invention to provide a new method for manufacturing the above-mentioned tinplate original plate, and in particular, to provide a continuous annealing apparatus that can concretely implement the annealing process.

Specifically speaking, the purpose of the present invention is to process all temper grade tin plates regardless of whether they are soft or hard.
It is an object of the present invention to provide a continuous annealing device which can carry out annealing in a standard continuous annealing facility, can efficiently manufacture tin plate blanks, and can reduce the installation space and the number of steps.

The present invention will be explained in detail below.

The heating/cooling cycle for the conventional continuous annealing process is as shown in Figure 2.After heating at a recrystallization temperature of 1 in the heating process,
In the soaking process, the temperature is maintained at a constant temperature for a predetermined time, and then heated to 400℃
It goes through a slow cooling step of slow cooling at 500° C. 1 and then a rapid cooling step of rapid cooling to room temperature 1 (see the chain line A in FIG. 2 for the cooling process).

In this normal cycle, as mentioned above, (:C) and [N], which were solidly dissolved in the steel at the time of heating and soaking, remain even at room temperature due to insufficient re-precipitation during the next cooling process. become.

Therefore, the remaining (C) and (N"l) harden the material, making it difficult to manufacture a soft tin plate.

On the other hand, as shown by the solid line B in Fig. 2, when the cooling button is pressed after heating and soaking, the temperature is first rapidly cooled and then heated to 300 to 500°.
When the secondary rapid cooling is performed after intermediate low temperature retention at a temperature of C, the above-mentioned residual solid solution (C) and (N) are reduced and the material is softened.

In this way, the cooling process failed and the cooling was temporarily interrupted.
It has been found that a soft tin plate can be obtained by performing a so-called over-aging treatment in which the material is kept at an intermediate temperature of 500°C.

The present invention enables these two different cooling cycles to be performed in the same continuous annealing equipment, thereby making it possible to manufacture hard tinplate blanks and soft tinplate blanks, which were considered impossible to produce with conventional equipment. .

Specific examples thereof will be explained below based on the drawings.

Figure 1 shows conventional continuous annealing equipment (Figure 1a) for reference.
is shown in comparison with the continuous annealing equipment of the present invention (FIG. 1b).

That is, for FIG. 1a, the strips (
A vertical furnace equipped with a built-in hearth roll that makes it possible to run the tin plate (original tin plate) S is installed in the heating zone 1. Soaking zone 2. slow cooling zone 3
and rapid cooling zone 4 are divided in series.

As heating/cooling means for each zone, for example, a radiant tube 5 may be used in the heating zone 1, an electric heater 6 in the soaking zone 2, a cooling tube 7 in the slow cooling zone 3, and a jet cooler 8 in the rapid cooling zone 4.

Fig. 1 shows an example in which the continuous annealing equipment shown in Fig. 1a is used, and the slow cooling zone and rapid cooling zone are modified.

That is, the heating zone 1 and the soaking zone 2 are exactly the same as those in FIG. A partition wall 10 is provided between the first bus and the third pass to separate and install a primary cooling zone 11.

The remaining part of the slow cooling zone 3 (from the third pass onwards) is equipped with a cooling tube 7 for slow cooling and an electric heater 12 along the pass route for overaging treatment, as in the conventional case. .

In addition, the quenching zone 4a is equipped with a normal jet cooler 8 and an electric heater 13 for overaging treatment along the pass route from the entrance side, and the final two passes are separated by a partition wall 10' with only a jet cooler 14 for cooling. is installed to form a secondary quenching zone 15.

A quench tank 16 is placed at the outlet of the furnace for final cooling.

This quench tank 16 can be omitted if the desired final cooling can be performed in the secondary quenching zone 15.

In addition, in the illustrated example, in order to utilize the conventional continuous annealing equipment, a partition wall is provided in each of the slow cooling zone and the rapid cooling zone to separate the primary and secondary rapid cooling zones, but in the present invention, this is not possible. However, it is also possible to provide a separate primary cooling zone between the soaking zone and the slow cooling zone, and a separate secondary cooling zone at the rear of the cooling zone.

In addition, heating and cooling means are not limited to those shown in the drawings.
Of course, other known means that perform the same function may also be used.

In addition, in FIG. 1bGC, 17 is an 0N-() FF device of the jet cooler 9 facing the primary quenching zone 11, 18 is a switching device for the cooling tube 7 and electric heater 12 facing the slow cooling zone 3a, and 19 is a quenching switch. A switching device 20 for the jet cooler 8 and the electric heater 13 in the zone 4a is an 0N-FF switch for the jet cooler 14 in the secondary quenching zone 15, and these switch the jet cooler according to the hardness level of the tinplate original plate. Turn it on or off, or switch between the cooling tube or jet cooler and electric heater.

Next, to explain the operation of the continuous annealing apparatus shown in FIG. Jet coolers 9 and 14 are set to 0N-(
) turned off by the FF devices 17 and 20, and the slow cooling zone 3
Turn on the cooling tube 7 with the switch 18 of a.
The electric heater 12 is turned off, the jet cooler 8 of the quench zone 4a is turned on, and the electric heater 13 is turned off.

As a result, slow cooling and rapid cooling operations are performed based on the normal cycle A after heating and soaking shown in FIG.

For example, when manufacturing soft tin plate blanks of T-] to T-3, the jet coolers 9 and 14 are turned on, the cooling tube 7 of the slow cooling zone 3a is turned off, and the electric heater 12 is turned on. Furthermore, the jet cooler 8 in the quenching zone 4a is turned OFF and the electric heater X*13 is turned ON to perform heating, soaking, primary quenching, passing aging, and secondary quenching (B in Fig. 2).

Among them, it is possible to switch between the normal cycle for hard materials and the overaging cycle for soft materials within 30 minutes, including furnace condition adjustment.

This cycle switching is shown in Table 1 in an easy-to-understand manner.

Furthermore, Fig. 3 shows the hardness after annealing of the tinplate blanks produced in the continuous annealing apparatus of the present invention, and as can be seen from this figure, according to the present invention, the hardness of the soft tinplate blanks - hard tinplate blanks is hardened by the same continuous annealing apparatus according to the present invention. It becomes possible to create and separate products.

As explained above, according to the continuous annealing apparatus of the present invention, the quenching zone, the heating/cooling zone, and the quenching zone are arranged at the rear of the soaking zone, so that the over-aging process for soft tinplate blanks can be carried out. It is possible to perform both conventional heat treatment and conventional heat treatment for hard tin plates, and the conventional two-system equipment can be concentrated on only the highly efficient continuous annealing equipment, resulting in higher efficiency, labor savings, and installation space for heat treatment work. It makes a large contribution in terms of savings, and its industrial value is extremely large.

[Brief explanation of the drawing]

FIGS. 1a and 1b are schematic diagrams showing continuous annealing equipment for tin plate blanks, where a shows a conventional annealing equipment and b shows an annealing equipment according to an embodiment of the present invention. FIG. 2 is a chart explaining the heating/cooling cycle in continuous annealing, and FIG. 3 is a chart showing the distribution of products obtained by the present invention according to their hardness. 1... Heating zone, 2... Soaking zone, 3, 3a... Slow cooling zone, 4.4a... Rapid cooling zone, 7... Cooling tube, 8° 9... Jet cooler, 10 , 10'・
...Partition wall, 11...-Next rapid cooling zone, 12,13...
・Electric heater, 14...Jet cooler 15...
・Secondary rapid cooling zone, 16...quench tank.

Claims (1)

[Claims] 1 In continuous annealing equipment that has a heating zone, a soaking zone, a slow cooling zone, and a rapid cooling zone, the cooler is turned ON-OF after the soaking zone.
An original plate for surface treatment characterized by sequentially providing a primary cooling zone with a high capacity, a slow cooling zone and a rapid cooling zone having switching means for heating and cooling, and a secondary cooling zone in which the cooler can be turned on and off. continuous annealing equipment.