JPH07276012A - Cooling roll for producing short length rapidly cooled/ solidified strip - Google Patents

Abstract

PURPOSE:To provide a cooling roll for efficiently producing a short length rapidly cooled/solidified strip having flat shape, in an apparatus for producing the above strip by a single roll method. CONSTITUTION:The cooling roll 1 is used to produce the rapid cooled/solidified strip by supplying molten metal onto the surface 9 of the cooling roll rotated at high velocity, band-shaped insulation films 10 are arranged on the surface 9 of the cooling roll in the rotating axial direction at a prescribed interval from the peripheral direction of the roll to produce the short length rapid cooled/solidified strip. The short length rapid cooled/solidified strip having flat shape can be produced by using this cooling roll 1 and further, the service life of the cooling roll 1 can be further extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short metal fiber or a short metal ribbon (hereinafter referred to as a short ribbon) manufactured by a single roll method for reinforcing materials such as concrete and plastic, or as an intermediate product of powder. The present invention relates to a cooling roll for producing a metal ribbon).

[0002]

2. Description of the Related Art Conventionally, short metal materials such as short metal fibers used to reinforce materials have been manufactured by cutting a thin wire or cutting a thin steel plate into small pieces. , There is a difficulty in productivity.

On the other hand, a method for producing a short metal ribbon with high productivity by impinging and solidifying a molten metal on a cooling roll moving at high speed is disclosed in, for example, Japanese Patent Laid-Open No. 59-157322.
c. of Inter.on Rapid Quenched Metals (1985) P.27 F
ig.8A and Japanese Patent Application No. 5-54248. JP-A-59-157322, Proc. Of Inte
r. on Rapid Quenched Metals (1985) P.27 In the method disclosed in Fig. 8A, the molten metal supplied to the roll surface is formed in the grooves by providing a plurality of grooves on the surface of the roll in the rotation axis direction. It is cut off to make short fibers or short strips that are equal between the grooves. Further, the method previously proposed by the present applicant in Japanese Patent Application No. 5-54248 reduces the heat removal capability of the roll partially by installing a hole in the roll rotation axis direction at a predetermined position from the roll surface. A short fiber or a short ribbon is formed by preventing the molten metal from solidifying.

[0004]

When a short metal ribbon is produced by the above-mentioned cooling roll which rotates at a high speed, surface polishing is required each time it is produced.

JP-A-59-157322, Proc.
of Inter. on Rapid Quenched Metals (1985) P.27 Fi
In the method disclosed in g.8A, which uses a roll with a groove formed on the surface, polishing is performed before the casting to clean the roll surface. You just have to clean it. That is, it takes time to prepare the roll, and there is a problem in productivity. In addition, a notch is formed at the end of the obtained short metal ribbon, which is difficult to peel off from the roll, and adheres at the time of collection to complicate the collection work, or the space factor is deteriorated when used as a reinforcing material. There is a problem of doing.

Further, in the method proposed in Japanese Patent Application No. 5-54248, a roll is provided with a hole parallel to the rotation axis at a position distant from the surface of the roll in the radial direction. The life of the roll depends on the radial thickness of the roll, as the roll wears due to polishing for care. However, when the roll is provided with a hole, the roll becomes hollow, and therefore the thickness of the roll in the radial direction which enables casting becomes thin. Therefore, there is a problem that the life of the roll is shortened by installing the holes in the roll.

The present invention solves the above-mentioned conventional problems, and provides a roll capable of producing a short-length rapidly solidified ribbon having a flat shape and further extending the life of the roll. With the goal.

[0008]

In order to achieve the above object, the present invention relates to a cooling roll used in an apparatus for producing a rapidly solidified ribbon by supplying molten metal to a cooling roll rotating at a high speed. In the cooling roll, a belt-shaped heat insulating film extending in the roll rotation axis direction is provided on the surface at predetermined intervals in the roll circumferential direction, and the heat insulating film has K / L ≦ 2000.
It is preferably a film satisfying 0 w / m ² ° C (K; thermal conductivity, L; film thickness).

[0009]

When the cooling single roll is adopted in the apparatus for producing the rapidly solidified ribbon, the cooling of the supplied molten metal is suppressed on the heat-insulating film provided on the surface of the cooling roll, so that solidification is achieved. Almost no formation of thin ribbon due to. Therefore, the fibers and ribbons are divided on the heat-insulating film, and the obtained products are short fibers and short ribbons, that is, short and rapidly solidified ribbons. By selecting the arrangement position of the above-mentioned heat insulating coating at an arbitrary predetermined interval in the circumferential direction of the roll, it is possible to continuously manufacture short rapid solidification with an arbitrary length.

The present invention will be described in detail below. FIG. 1 is a conceptual diagram showing an example of an apparatus for carrying out the present invention. Reference numeral 1 is a cooling roll, which is rotated at a high speed in the direction of the arrow via a rotating shaft 2 by a rotating device (not shown). Reference numeral 3 is a crucible for containing the molten metal 4, and a nozzle 5 is provided below the crucible 3.
6 is a heating device (work coil for high frequency induction heating in the figure)
That is, the metal is melted or the molten metal is kept warm. Reference numeral 7 is a stripping device for the short-sized rapidly solidified ribbon 8 which is solidified and adhered to the roll surface and conveyed.

FIG. 2 is an enlarged view of the cooling roll 1 of the present invention as seen from the roll surface. That is, a film 10 made of a substance having a thermal conductivity smaller than that of the roll material is provided on the roll surface 9 in the roll rotation axis direction. The film 10 is continuously formed in the roll rotation axis direction. Usually, the body of the cooling roll is made of copper (Cu) having a high thermal conductivity in order to improve the heat removal of the molten metal. By this, a continuous long ribbon can be obtained, but in the present invention, the coatings 10 are provided at appropriate intervals in the circumferential direction, and the heat transfer is worse on this coating 10 part than in the area where the coating is not present. Since the heat removal from the roll surface is almost shut off, and therefore the solidification of the molten metal does not proceed, the ribbon is divided at this position to become a short rapid solidified ribbon.

Generally, the progress of solidification depends on the cooling rate and the cooling time, but in the case of solidification by the single roll method, it depends on the heat removal capability of the roll and the thickness of the thin strip. Therefore,
Factors that affect the cutting of the ribbon by the roll of the present invention include the heat insulating ability of the coating 10 and the thickness of the ribbon 8.

Of the above two factors, when considered in terms of heat transfer as an index showing the heat insulating ability of the film 10, the film 1
It is general to adopt the heat transfer coefficient in the portion where 0 is present. The heat transfer coefficient is the thermal conductivity K and the film thickness L of the film 10.
Is represented by K / L, and if the value of this heat transfer coefficient is small, high adiabaticity is exhibited. Therefore, the film 10
The material (thermal conductivity K) that forms the film and the film thickness L thereof may be appropriately selected so as to have a required heat transfer coefficient K / L in order to delay the progress of solidification of the ribbon and enable the division. Good.

Therefore, the inventors conducted an experiment for obtaining an appropriate range of heat transfer coefficient that enables the ribbon to be divided.
In this experiment, the material forming the film 10 was an organic paint (trade name: oil-based magic, thermal conductivity: about 0.1 W / mK), and the thickness of the film 10 was varied in order to change the heat transfer coefficient. The thickness of the film 10 was measured using a contact type ultra-light load thickness sensor. In addition, since the plate thickness of the thin strip usually produced by the single roll method is 20 to 80 μm,
The thickness of the thin strip 8 in this study is about 20, 50, 80 μm
3 levels. In this experiment, copper (1% C
A roll containing r) was adopted.

The cutting conditions of the ribbon in this experiment are shown in Table 1. In Table 1, the case where the obtained ribbon can be cut is indicated by ◯, and the case where it cannot be cut is indicated by x. As is clear from Table 1, the thickness of the film 10 is 1-2 μm.
m, that is, the heat transfer coefficient is 50,000 to 100,000 W / m
^In the case of ² K, only a thin strip of 24 μm could be cut, but the thickness of the coating 10 was 5 to 7 μm, that is, the heat transfer coefficient was 1
78 if it goes down to about 4000-20000 W / m ² K
It became clear that thin strips with a thickness of up to μm were cut. Therefore, according to the above experiment, K / L ≦ 20,000 W / m
^It can be said that by providing the film 10 satisfying ² K on the roll 1, it becomes possible to manufacture the short rapid solidification ribbon 8.
Further, it is preferable that the value of the heat transfer coefficient of the heat insulating film 10 is small in consideration of the cutting property of the ribbon. Therefore, the film thickness and physical properties of this heat insulating film 10 are K / L ≦ 20000 W / m
^It may be set appropriately within the range of 2K. Other paints that form such a heat insulating film may be resins, adhesives, and various oils.

[0016]

[Table 1]

The cutting property of the ribbon may depend on the material of the cooling roll, that is, the thermal conductivity. When the heat conductivity of the roll material is high, the movement of heat is accelerated even if the heat insulating film 10 is present, so that the solidification suppressing ability is lowered and the cutting property is impaired. Although noble metals such as silver and diamond can be considered as the substance having a high thermal conductivity, the copper roll has the highest thermal conductivity when the material of the roll is selected within the industrially used range. Therefore, it can be said that the conditions for the heat-insulating film 10 obtained in the above experiment using the copper roll are the most strict and the conditions under which the ribbon can be reliably cut in consideration of the material of the roll. For confirmation, a Ni-plated roll or a stainless roll having a lower thermal conductivity than the copper roll was used, and K / L ≦ 2 was set on each roll surface.
An experiment was carried out in which the coating film 10 satisfying 0000 W / m ² K was installed, and it was confirmed that the ribbon could be divided by any of the rolls.

Regarding the influence of the width of the ribbon in the circumferential direction of the coating roll when the ribbon is cut by the coating 10, when the coating width is narrow, the region in which the solidification in the circumferential direction of the roll is suppressed becomes short and the cutting of the ribbon becomes insufficient.
The width of the coating needs to be appropriately determined depending on the casting conditions, but is usually preferably 0.5 mm or more, more preferably 1 mm or more.

[0019]

EXAMPLE A cooling roll having a diameter of 300 mm and a width of 30 mm is provided on a surface of a copper roll, and a film having a length of 1 mm in the circumferential direction and a small heat transfer coefficient of the entire width in the width direction of the roll is formed by an oil-based magic ( K = 0.1 W / mK), and the film thickness of the film 10 was set to two levels of 10 and 30 μm. In addition, the distance between each film in the roll circumferential direction is 2
It was set to 0 mm.

Using this roll, casting was performed in the apparatus shown in FIG. 1 under the following conditions. Dissolved component: Fe-Si6.5-B12-C1 (amorphous alloy) and Fe-4.5Si (crystalline alloy) Film thickness: 5.25 μm Roll material: Cu, stainless steel Dissolved sample weight: 50 g of roll surface Velocity: 25 m / sec Nozzle gap: 0.3 mm Nozzle opening shape: 0.6 mm x 10 mm A total of 8 levels of experiments were conducted under the above conditions. All of them had a width of 10 mm and a length of about 20 mm. The obi was obtained. Further, all of the obtained short rapid solidified ribbons were flat and no burrs were generated.

[0021]

As described above, according to the present invention, it becomes possible to obtain flat short fibers and short ribbons having no notches on the end faces thereof, which eliminates the troublesomeness of recovery work and is used as a reinforcing material. If so, the space factor can be increased. Also,
Unlike conventional groove forming rolls, there is no need to clean and grind the groove part when polishing the roll, only the surface of the roll needs to be polished. Therefore, the roll can be prepared in a short time, improving productivity. it can.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of an apparatus for carrying out the method of the present invention.

FIG. 2 is an enlarged explanatory view of the cooling roll of the present invention seen from the roll surface.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cooling roll 2 Rotating shaft 3 Crucible 4 Molten metal 5 Nozzle 6 Heating device 7 Peeling device 8 Short length rapid solidification ribbon 9 Cooling roll surface 10 Film

Claims (2)

[Claims] 1. A cooling roll for use in an apparatus for producing a rapidly solidified ribbon by supplying molten metal to the surface of a cooling roll that rotates at a high speed, wherein the cooling roll surface has a belt-shaped heat insulating film in the direction of the rotation axis of the roll. A cooling roll for producing a short rapid solidified ribbon, characterized in that the rolls are provided at predetermined intervals in the circumferential direction of the roll. 2. The heat insulating coating is K / L ≦ 20000 w /
The cooling roll according to claim 1, which satisfies m ² ° C. (However, K: thermal conductivity, L: film thickness)