JPS5930455A - Cooling method of roll for production of quickly cooled light-gage strip - Google Patents

Abstract

PURPOSE:To decrease the thermal crown of a cooling roll and make the thickness in transverse and longitudinal directions of a light-gage strip uniform by supplying the cooling liquid to be introduced into the parts of the roll in and without contact with molten metal through separate systems and providing a temp. difference. CONSTITUTION:The cooling liquid to be introduced into a cooling roll 1 is supplied in separate systems for the part 1a into contact with molten metal 8 and the part 1b without contact therewith. The temp. of the cooling liquid to be introduced into the part 1b is made higher than the temp. of the cooling liquid to be introduced into the part 1a to provide at least 100 deg.C temp. difference. The rates of thermal expansion of the parts 1a and 1b of the roll 1 are respectively detected and the flow rate of the low temp. cooling liquid or high temp. cooling liquid is adequately changed according to the detected values thereof, whereby the thermal crown of the roll 1 is controlled.

Description

[Detailed Description of the Invention] The present invention relates to a method for cooling a roll for manufacturing a quenched ribbon,
In particular, it is possible to advantageously reduce the difference in thermal expansion between the contact area and the non-contact area with the molten metal of the a-ru during the production of the quenched ribbon, thereby increasing the thickness of the quenched ribbon in the width direction as well as in the longitudinal direction. The aim is to equalize the

In recent years, a method has been developed in which molten metal (including alloys; the same shall apply hereinafter) is continuously supplied onto a cooling body whose cooling surface is updated and moved at high speed, and is rapidly solidified to produce metal ribbon directly from the molten metal. has been developed.

In this type of manufacturing method, rolls made of copper or prepared alloys, which are highly thermally conductive, are often used as cooling bodies, and the heat removal effect is enhanced by cooling the inside of the rolls with K, such as water cooling.

By the way, it has been revealed that when a quenched ribbon is produced by repeated use of a roll equipped with such an internal cooling mechanism, the thickness in the width direction of the obtained metal ribbon varies in the longitudinal direction. .

The reason for this is thought to be as follows.

That is, when the inside of the roll is uniformly cooled in the axial direction as in the conventional case, as shown in FIG. Since the temperature rise in the non-contact part tb is small and it hardly expands, a thermal crown is generated on the roll body surface 1 in which the central part swells locally as shown in the figure, and this causes the ribbon to swell. 7. This results in non-uniformity in the cooling condition and thickness in the width direction, which in turn causes non-uniformity in the residual quality of the ribbon product. Cru.

Further, the thermal expansion at the contact portion 1a with the molten metal as described above gradually increases with the passage of time, and therefore the rapid cooling
The plate thickness also fluctuates in the longitudinal direction of the R band, resulting in 11
A) to bring out the temple's worst verses.

This invention was discovered after numerous experiments and studies in order to solve the problem described in (-). This method solves the problem described in - by performing the cooling in a separate system and making the temperature of the coolant introduced into the non-contact part higher than the temperature of the coolant introduced into the contact part.

In this invention, liquid nitrogen, liquid helium, salt water whose freezing point is below 0°C, ice water at 0°C, etc. can be introduced into the contact area of the cooling roll with the molten metal, and also introduced into the non-contact area. As such, boiling water is advantageously suitable for each, and the temperature difference between the two is 100~L5(1'(,
degree is preferred.

7. This invention will be explained in detail 6. FIG. 2 shows a cross section of a cooling roll suitable for carrying out this invention. 2 is a passage groove for the cooling liquid (hereinafter referred to as the low-temperature cooling liquid) in the contact area with the molten metal of the cooling roll]a; 8 is a passage groove for the cooling liquid (hereinafter referred to as the high-temperature cooling liquid) in the non-contact area 1b; The high-temperature cooling liquid is introduced into the roll from supply pipes 4 and 5, passes through passage grooves 2 and 3, and then discharged from discharge pipes 6 and 7.In the figure, number 8 is molten metal, and number 9 is a heat insulating material. be.

FIG. 8 also shows another preferred cooling roll, shown in radial section in FIG. 8a and in cutaway section A--A in FIG. The internal cooling mechanism of the white roll is the same as that of the twin roll described above.

Next, Fig. 4 shows the results of an investigation on the crown change of the roll cylinder when a quenched ribbon is produced while cooling the roll according to the present invention, in comparison with the conventional method. The crown change is shown in Figure 1 above in 7), where the contact area with the molten metal during ribbon production], a and the non-contact area 1.
Evaluation was made based on the thermal expansion difference Δl with respect to b.

As shown in Figure 4, if conventional methods are followed, such as not applying water cooling at all or simply applying water cooling uniformly over the roll shaft, the thermal expansion difference Δl will gradually increase over time. On the other hand, according to the present invention, the thermal expansion difference Δl could be reduced to almost zero within 6 hours.

Examples of the present invention will be described below.

Example 1 Using a single roll equipped with the internal cooling mechanism shown in No. 31 ¥1 above, 0°C water was applied to the contact area with the molten metal, and 100°C hot water was applied to the non-contact area. While introducing into the roll as a heating medium, Fe: 78%, B in atomic %
A quenched metal ribbon was prepared by injecting 30 kg of molten metal at 1250° C. having a composition of 13% Si and 9% Si onto the single roll rotating at high speed from a 160 mm wide slit nozzle.

Table 1 shows the results of examining the thickness, width, and shape of the obtained ribbon. For comparison, a similar experiment was also conducted in the case where the roll was cooled uniformly in the axial direction of the roll according to the conventional method, and the results are also listed in Table 1.

Example 2 Using twin rolls equipped with the internal cooling mechanism shown in Figure 4 above, +1'C water was applied to the contact area with the molten metal, and 1.00C hot water was applied to the non-contact area. Sl in weight %: 6.5%, introduced into the roll as a medium;
A quenched ribbon was prepared by injecting 50 kg of a 1.5 (10° C.) molten metal having a composition of balFe from a slit nozzle with a width of 201 mm and rr. Table 2 shows the results of examining the thickness, width, and shape of the obtained ribbon in comparison with the conventional method.

Note that the control of the thermal crown of the roll according to the present invention is as follows:
The amount of thermal expansion of the contact portion and the non-contact portion of the roll with the molten metal is detected, and the flow of the low-temperature cooling liquid or the high-temperature cooling liquid is changed as appropriate according to the detected values. This allows the process to be carried out easily and continuously.

As described above, according to the present invention, in the method of manufacturing a quenched ribbon using a cooling roll, a drum-like shape is generated due to the different amount of thermal expansion μ in the contacting part and non-contacting part of the molten metal of the roll. The thermal crown of the quenched ribbon can be effectively reduced, and the thickness of the quenched ribbon can be made uniform in the width direction as well as in the longitudinal direction.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the occurrence of a thermal crown, FIGS. 2 and 8 are cross-sectional views showing the case of a twin roll and a single roll cooling roll suitable for carrying out the present invention, respectively. is a graph showing a comparison of the change in ff5 over time of the thermal expansion difference Δe between the present invention method and the conventional method. Patent applicant Kawasaki Steel Corporation Figure 1 Figure 2 Figure 3 and a) (b) 2

Claims (1)

[Scope of Claims] L A cooling roll that receives a falling flow of molten metal and forces the metal to rapidly solidify into a thin ribbon. The cooling liquid is introduced into the molten metal contact area and the non-contact area under separate systems, and the temperature of the coolant introduced into the non-contact area is higher than the temperature of the coolant introduced into the contact area. A method for cooling rolls for manufacturing quenched ribbons. 2. The method according to claim 1, wherein the temperature difference between the coolant introduced into the contact area and the non-contact area with the molten metal is at least 100°C.