JPH03275248A - Method for forming inert gas atmosphere in apparatus for producing metal strip using rapid cooling roll - Google Patents

Abstract

PURPOSE:To obtain the atmosphere having low oxygen concn. in a short time by making low vacuum degree having the specific Torr of an inner part of a chamber surrounding a molten metal charging vessel and a nozzle arranged to this and a cooling roll and successively, repeating the process for introducing inert gas. CONSTITUTION:In the production apparatus for metal strip S, the charging vessel 7 for molten metal M and the pouring nozzle 9 arranged to this and the cooling roll 10 set below this, are set. This apparatus is surrounded with the chamber 14. Then, the inner part of chamber 14 is made to low vacuum degree of about 1-100Torr. Following to this, the inert gas is introduced from an introducing hole 16. By repeating this process at plural times, the inert gas atmosphere is formed. By this method, replacement of the inert gas atmosphere under comparatively low vacuum degree, can be executed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to an inert gas in an apparatus for producing oxidizable crystalline metal ribbons of iron-based alloys such as stainless steel or aluminum-based alloys by a roll quenching method. Concerning the method of replacing the atmosphere.

[Conventional technology]

The molten metal is continuously flowed down onto the cooling roll for 30~
Forming a 200 μm thick crystalline metal ribbon itself is
For example, as described in Japanese Patent Publication No. 61-5821, it has been widely known before the filing of the present application.

In particular, when this single roll quenching method is applied to crystalline materials such as stainless steel and aluminum alloys where surface oxidation is undesirable, it is necessary to make the atmosphere inside the apparatus inert.

As a countermeasure for this, it is conceivable to construct the entire apparatus in a sealed structure with a chamber like a normal vacuum apparatus, and to replace the atmospheric gas with an inert gas. However, the method of covering the entire device with a chamber is limited to a laboratory scale due to the equipment, and cannot be applied to a relatively large-scale metal ribbon manufacturing device.

In addition, it is possible to partially form an inert gas atmosphere, and in particular, apply a method of sealing only the vicinity of the molten metal pouring nozzle where the metal is heavily oxidized, for example by spraying inert gas. Since the cooling roll rotates at high speed, air entrainment cannot be avoided and cannot be an effective countermeasure.

For this reason, the entire casting device is spatially comprised of a molten metal holding part, a nozzle part provided in the holding part, and a cooling roll part that receives the molten metal poured from the nozzle part and cools it into a thin ribbon. and a winding section that receives and winds up the metal ribbon formed by the casting section, a driving device for the casting section is disposed outside the system, and the entire casting section is sealed by a chamber. was suggested.

In this way, the method of sealing the casting area separate from the winding area and creating an inert gas atmosphere in this area does not pose any particular hindrance to the operation of the apparatus itself and the handling of the obtained ribbon. It has a great advantage in that it can efficiently create an inert gas atmosphere and operate under this inert gas atmosphere without using particularly large-scale replacement equipment.

However, when creating an inert gas atmosphere in the casting area in such an apparatus, it is difficult to introduce the inert gas after first evacuating the chamber because it creates an atmosphere containing a low oxygen content. This is a technique commonly used in vacuum heat treatment furnaces and the like.

[Problem to be solved by the invention]

However, in a metal ribbon manufacturing apparatus that includes various devices such as a molten metal storage container, a nozzle, and a quenching roll, and also includes many accessories such as wiring and piping, there are disadvantages such as the conventional vacuum processing apparatus. If the active gas replacement method is applied as it is, a high vacuum of 10-' to 10-5 Torr or higher is required, and a sophisticated sealing mechanism is accordingly required, which increases equipment costs and operational load.

The problem to be solved by the present invention is to provide an inert gas atmosphere forming method that can form an inert gas atmosphere under a relatively low load in an apparatus for casting metal ribbon using a quench roll.

[Means to solve the problem]

In the present invention, after creating a low vacuum of approximately 1 to 100 Torr in a chamber that integrally surrounds a molten metal storage container, a pouring nozzle provided in the container, and a cooling roll placed below the nozzle, It is characterized in that the process of subsequently introducing an inert gas is repeated multiple times.

[Effect]

In the present invention, the degree of vacuum created for inert gas replacement is sufficient in the conventional process time of 100 minutes, so although the number of times for vacuum creation increases, the chamber structure for sealing and the vacuum The capacity of the pump is also extremely small,
Accordingly, the entire device can be simple, and the atmospheric oxygen concentration required for oxidation prevention, which is 1000 ppm or less, can be easily achieved.

〔Example〕

FIG. 1 is a diagram showing the overall configuration of a metal ribbon manufacturing apparatus using quench rolls suitable for applying the method of the present invention.

Referring to the figure, the manufacturing apparatus consists of a casting section 1 and a winding section 2.

The casting zone 1 has a molten metal holding part, a nozzle part provided in the holding part, and a cooling roll part that receives the molten metal poured from the nozzle part and cools it into a ribbon.

The molten metal holding section includes a molten metal transport vehicle 4 moving on a support frame 3 and a container 7 having a heating means 6 such as a high frequency coil for maintaining the temperature of the contained molten metal.
The molten metal M inside is sealed by a lid 8 placed on the top opening, and the surface of the molten metal can be pressurized by supplying gas to the inside. Furthermore, when manufacturing a large amount of ribbon, a melting furnace is installed above the molten metal holding section.
molten metal can be continuously supplied through the opening 5.

The nozzle section disposed below the molten metal holding section has a nozzle 9 with a hole formed in a shape that allows a certain amount of molten metal to be poured out continuously over time and over the entire width.

Further, below the nozzle 9, a cooling roll section is arranged which includes a cooling roll 10 rotated by a drive source (not shown), a guide 11, a conveyance means 12 using a suction belt, and the like.

Reference numeral 13 indicates a gap measuring device connected to a control means for measuring the gap between the lower surface of the nozzle 9 and the surface of the cooling roll 10 and keeping the distance between the nozzle and the cooling roll constant.

The entire casting area is surrounded by a chamber 14, and near the bottom of the chamber 14 there is an inert gas source connected to an inert gas source such as a suction unit 15 connected to a vacuum pump for replacing the atmosphere. The introduction port 16 is open.

Further, 17 is a communication port for conveying the formed metal ribbon S to the winding area 2, and indicates a gas curtain using an inert gas. As a result, the continuously formed thin strip S
can be continuously introduced into the winding section 2 without outside air entering the inert gas atmosphere inside the chamber 14.

The winding section 2 comprises a winding machine 19 and a conveying means 18 for receiving the metal ribbon S produced in the casting zone 1 sealed by a chamber 20 and with its oxygen concentration reduced.

As this winder 19, for example, a winder having a structure described in Japanese Patent Application Laid-Open No. 1-136958 proposed by the present inventors can be suitably used.

Further, in this area of the winding zone 2, if the surface temperature of the ribbon S conveyed from the casting zone 1 is below the oxidation temperature, no atmosphere adjustment is necessary; Even at the stage of being transported to the machine 19, the temperature may be in a range where oxidation progresses.

To prevent this, oxidation can be completely prevented by forming the winding section 2 into a chamber 20 for simple sealing and by introducing a low degree of inert gas through the inlet 21.

Figure 2 shows N2 gas as an inert gas. FIG. 2 is a diagram showing a process of replacing the atmosphere in the chamber shown in FIG. 1 using Ar, He.

Referring to Figure 2, using a vacuum pump (oil rotary pump) inside the chamber, 0,015 kg/cm2 was generated in approximately 9 minutes.
The pressure was reduced to (11)-L).

Under this condition, each replacement gas was purged to return the chamber pressure to atmospheric pressure.

Furthermore, by suctioning each atmospheric gas, 0.075
kg/cm2 (-57) -l) NJ3E (D) The replacement gas was purged again.

FIG. 3 shows the oxygen concentration in the atmosphere reached as a result of the inert gas replacement step shown in FIG. 2 above.

In the case of N2, 500 to 60002 after 23 minutes of treatment
Achieved ppm. In addition, in the case of Ar, about 19 minutes to 2
An oxygen concentration of 500-60002 ppm could be achieved with a 3 minute treatment, and in the case of He, an oxygen concentration of 200-400021111 m could be achieved with a treatment of about 15-17 minutes.

In addition, the difference in replacement time depending on the gas type in this example is as follows:
This is due to a difference in flow rate at the same supply pressure, and is not an essential difference. In order to ensure an atmosphere with a low oxygen concentration, it is important to complete the replacement operation in as short a time as possible.

〔Effect of the invention〕

The following effects can be achieved by the present invention.

(1) The low oxygen concentration required for non-oxidative casting of active metal ribbons can be reached in a short time, so it is suitable for producing wide active metal ribbons.

(2) Since the inert gas atmosphere can be replaced under a relatively low vacuum, the equipment can be small.

[Brief explanation of drawings]

FIG. 1 shows an outline of a metal ribbon manufacturing apparatus suitable for applying the method of the present invention. FIG. 2 shows an embodiment of the present invention, and FIG. 3 shows the oxygen concentration distribution achieved by the process shown in FIG. 2 for each inert gas. 1: Casting zone 2: Winding zone 3: Support frame 4: Molten metal carrier 5; Opening 6: Heating means 7; Container 8: Lid 9: Nozzle 10: Cooling roll 11 guide 12: Conveying means 13: Gap measuring device 14 : Chamber 15: Suction port 16: Inert gas inlet 17; Gas curtain 18; Conveying means 19: Winder 20: Chamber 21: Inert gas inlet (u, +dd)

Claims (1)

[Claims] 1. Create a low vacuum of about 1 to 100 Torr in the chamber surrounding the metal ribbon manufacturing equipment, which has a molten metal storage container, a pouring nozzle installed in the container, and a cooling roll placed below the nozzle. , followed by a method for forming an inert gas atmosphere in which the step of introducing an inert gas is repeated multiple times.