JPS6058766B2 - Metal strip cooling method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a metal strip cooling method.

Approximately 4 hours after completion of overaging treatment in continuous metal strip treatment line
It is known that a metal strip is cooled to a temperature range of 000C to 450C to allow temper rolling, and conventional methods include the following.

That is, the metal strip is heated from 4000C to 4500C to 20 to 40℃.
Figure 1 shows the gas jet cool method for cooling.

In the figure, the steel strip S is the first cooling zone 10 and the second cooling zone 11.
The first cooling zone 10 is equipped with a gas jet cooler 12 using water as a refrigerant.
It is cooled to 0C to 250'C, and then cooled to 20C to 40C in a second cooling zone 11 equipped with a gas jet cooler 13 using a refrigerator. 14 indicates a hearth roll.

This method uses a gas jet cooler with a cooling rate of 5 to 15
It has the disadvantages that only about 0 C/sec can be obtained, the cooling furnace volume is large, the equipment cost is high, the blower motor capacity is large, and the running cost is high.

There is also a combination of the gas jet cooling method and the water cooling method, but in the method of cooling the metal strip from 400 to 450°C to 20 to 400°C, the metal strip is first cooled to about 250 to 100°C using a gas jet cooler using water as a refrigerant. The metal strip is then plunged directly into water and cooled from said temperature to 20-40°C. J Although this system partially overcomes the disadvantages of the gas jet cooling method by using underwater cooling, the gas jet cooling section is still large in terms of equipment.

This invention proposes a method in which a high temperature region with high cooling efficiency is cooled by a rotary cooling body, and a low temperature region with low cooling efficiency is cooled with a cooling liquid.

That is, in a continuous metal strip processing line, a high temperature metal strip (400 to 450 degrees Celsius) after overaging treatment is wound around a plurality of rotary cooling bodies that circulate a coolant around the inner peripheral surface of the body, while the metal strip is heated for 20 minutes.
Cool to 0-300°C.

It is then cooled to below 50'C either by spraying and immersion cooling with either water or a water-soluble rolling agent, or by spraying alone or immersion alone. The material used for cooling may be water if it is completely dry after cooling, or in the case of skin-pass rolling after cooling, a water-soluble rolling agent may be used since it is passed through a water-soluble rolling agent solution in advance to apply the rolling agent. But that's fine. The present invention will be explained below with reference to the drawings. FIG. 2 is an explanatory diagram showing an embodiment of the present invention, in which the rope S which has been overaged in the overaging zone 9 is passed through the first cooling zone 10 and the second cooling zone 11 via the hearth roll 14. Introduced into the next process.

The first cooling zone has a plurality of rotary cooling bodies 15 disposed therein, through which a refrigerant flows through the inner peripheral surface of the body.

The second cooling zone has a cooling zone provided with a desired number of spray nozzles 16 and an immersed rotating body 18, and the spray nozzles 16 incorporate a pump 17. The secondary cooling zone can use a method using a submerged rotating body, a spray method, or a combination of both methods. A continuous annealing line equipped with a rotary cooling body is proposed, for example, in JP-A-51-104417, but in this invention, the continuous annealing line equipped with a rotary cooling body is
A high-temperature metal band at 450°C is cooled to a temperature range of 200°C to 300'C while being wound around a rotary cooling body. According to experiments conducted by the present inventors, this can be explained as follows.

Figure 3 is a diagram showing the relationship between temperature and time when a high-temperature metal band at 400°C was cooled by the method of the present invention and the conventional method. In the figure, A is gas jet cool, B is gas jet cool + Water cooling, C is water (or water-soluble rolling agent) cooling, and D is the cooling rate using a rotary cooling body system.

Also, in Fig. 4, A shows the relationship between cooling rate and temperature for the gas jet cooling method, C for water (or water-soluble rolling agent) cooling, and D for the rotary cooling body method. , D method has a higher cooling rate, but if the temperature exceeds the service limit temperature, temper color occurs and post-treatment facilities are required.

Its upper limit temperature is about 300°C. Moreover, if method A and method D are compared, method D has a higher cooling rate in the entire temperature range. In other words, as is clear from FIGS. 3 and 4 above, the combination of method D (rotary cooling body) and method C (water or water-soluble rolling agent cooling) shown in FIG. It becomes E when shown in the figure. Therefore, in the present invention, the high-temperature metal strip is cooled to a temperature range of 200 to 300'C by a rotary cooling body, and then cooled to 50C or less by cooling with water (or water-soluble rolling agent).

Furthermore, by comparing the method of this invention with the conventional method described above, it has become clear that the method of this invention is superior as follows.

That is, according to the present invention, the material and shape of the high-temperature metal strip in the continuous annealing line can be improved, and the equipment cost and running cost can be reduced, resulting in great industrial effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the conventional method, FIG. 2 is an explanatory diagram of the present invention, FIG. 3 is a graph of temperature versus cooling time, and FIG. 4 is a graph of cooling rate per hour. 9... Overaging zone, 10... First cooling zone, 11... Second cooling zone, 15... Rotary cooling body, 16... ···spray nozzle.

Claims (1)

[Scope of Claims] 1. In cooling a high-temperature metal band after overaging treatment in a continuous metal processing line, as a first step, the metal band is heated to 200°C to 300°C while being wound around a plurality of rotary cooling bodies that circulate a refrigerant around the inner peripheral surface of the body.
A metal strip cooling method characterized by cooling to 50°C or less with a cooling liquid as a subsequent step. 2. The metal strip cooling method according to claim 1, wherein the latter stage is cooled by immersion in a cooling liquid. 3. The metal strip cooling method according to claim 1, wherein cooling in the latter stage is performed by spraying a cooling liquid. 4. The metal strip cooling method according to claim 1, wherein the latter stage is cooled by immersion in a cooling liquid, and the remaining part is cooled by spraying the cooling liquid. 5. The metal strip cooling method according to claim 1, wherein water or a water-soluble temper rolling agent is used as the cooling liquid.