JP5168211B2 - Rapidly solidifying ribbon casting nozzle - Google Patents

Description

  The present invention relates to a rapidly solidified ribbon casting nozzle suitable for casting an amorphous alloy ribbon used in a power transformer, a high-frequency transformer, and the like.

  Conventionally, as a method of casting an amorphous alloy ribbon (hereinafter sometimes referred to as a ribbon), the molten alloy is rapidly solidified by ejecting the molten alloy from a nozzle close to the surface of a rotating cooling roll. A single roll method is generally used in which an amorphous alloy ribbon is continuously obtained. When manufacturing on an industrial scale, this rapidly solidified amorphous ribbon is usually wound up and collected by a winding device. What is important in the amorphous ribbon produced in this single roll method is the surface property as well as the uniformity of the plate thickness. This surface property affects not only the magnetic properties of the amorphous alloy ribbon on a single plate but also the core properties because it is used like a core for power transformers. The important manufacturing factors governing the ribbon properties are the nozzle shape, the distance between the nozzle and the chill roll surface (hereinafter referred to as the gap), the jet pressure from the nozzle of the molten alloy, and the moving speed of the chill roll surface, In particular, various proposals have been made for the nozzle shape in order to realize stable casting.

  For example, in the technique described in Patent Document 1, the relationship between the width of the roll surface of the front lip in the traveling direction and the slit width of the nozzle is defined. In the technique described in Patent Document 2, the slit width of the nozzle and the thickness of the bottom surface of the front lip and the rear lip are defined.

  Furthermore, in the technique described in Patent Document 3, the nozzle walls on both sides in the width direction of the nozzle are inclined toward the inner side of the nozzle so that the pooled portion (hereinafter referred to as paddle) from which the molten alloy is ejected can be directly observed. Yes. Based on the observation result, the gap between the nozzle and the surface of the cooling roll and the injection pressure of the molten alloy are adjusted.

JP-A-61-159246 Japanese Patent Laid-Open No. 3-77751 JP-A-10-263761

  In the single roll method, in order to obtain an amorphous ribbon having good surface properties, it is necessary to reduce the gap described above.

  However, the shape of the nozzles described in Patent Document 1 and Patent Document 2 cannot sufficiently prevent the ribbon from being damaged when an amorphous alloy ribbon is manufactured with a small gap.

  Further, in the technique described in Patent Document 3, when an abnormality occurs in the paddle, the abnormality of the paddle progresses rapidly, and even if the gap or the injection pressure is adjusted after observation, it may not be in time. Furthermore, if the gap or injection pressure is changed, characteristics such as the surface shape of the cast ribbon may change, and the ribbon cannot be stably cast.

  In view of the above-mentioned problems, the present invention provides a rapidly solidified ribbon casting that can stably cast an amorphous alloy ribbon having good magnetic properties used in a power transformer, a high-frequency transformer, etc. in a single roll method. The purpose is to provide a nozzle.

The present invention is summarized as follows as a result of intensive studies to solve the above problems.
(1) a front lip located in front of the rotation direction of the cooling roll, and a rear lip located in the rear direction of rotation of the cooling roll and forming a slit through which the molten alloy flows between the front lip, And at least an end surface of the front lip on the discharge side of the molten alloy is a plane perpendicular to the direction in which the slit extends and passes through the discharge port of the molten alloy of the slit. And the slit is inclined in a direction away from the cooling roll, and the angle formed by the end surface and the reference surface is 5 ° to 45 °, and rapidly solidified ribbon casting Nozzle.
(2) The rapidly solidified ribbon casting nozzle according to (1), wherein the thickness of the front lip and the rear lip is at least 0.2 mm.
(3) The rapidly solidified ribbon casting nozzle according to (1) or (2), wherein the slit has a thickness of 0.3 mm to 2 mm.
(4) A step of injecting a molten alloy from the rapidly solidified ribbon casting nozzle according to any one of (1) to (3) onto a rotating cooling roll, and solidifying the molten alloy on the surface of the cooling roll. And a step for producing the amorphous ribbon.

  According to the present invention, it is possible to stably carry out continuous casting for a long time without causing a ribbon breakage, and it is possible to produce an amorphous alloy ribbon having a good surface property.

It is a figure explaining the outline | summary of the single roll method which casts an amorphous alloy ribbon. It is a figure which shows an example of the detailed structure of the nozzle which concerns on embodiment of this invention. It is a figure which shows the structural example of the front lip and the back lip in the nozzle which concerns on embodiment of this invention. It is a figure which shows the other structural example of the front lip and the back lip in the nozzle which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining the outline of a single roll method for casting an amorphous alloy ribbon.
As shown in FIG. 1, the opening surface of the nozzle 4 is brought close to the circumferential surface of the cooling roll 5 rotating at high speed. When the stopper 3 in the tundish 1 is raised, the molten alloy 2 is jetted onto the circumferential surface of the cooling roll 5. The jetted molten alloy 2 is rapidly solidified on the surface of the cooling roll, and an amorphous alloy ribbon 6 is obtained. The amorphous alloy ribbon 6 is wound around a winding roll 7 provided close to the cooling roll 5.

FIG. 2 is a diagram illustrating an example of a detailed structure of the nozzle 4 according to the present embodiment.
As shown in FIG. 2, the nozzle 4 is formed with a slit 43 through which the molten alloy 2 flows. The end surface 44 on the discharge side of the molten alloy 2 of the front lip 41, which is a portion located in front of the slit 43 in the rotation direction (traveling direction) of the cooling roll 5, is an inclined surface. That is, the reference plane 45 that is a plane perpendicular to the direction in which the slit 43 extends (the direction in which the molten alloy 2 flows) and passes through the discharge port 46 of the slit 43 is the portion of the cooling roll 5 where the molten alloy 2 is injected. Although substantially parallel to the surface, the end surface 44 is inclined in a direction away from the cooling roll 5 by an angle θ (θ> 0 °) from the reference surface 45. On the other hand, the end surface on the discharge side of the molten alloy 2 of the rear lip 42, which is a portion located behind the slit 43 in the rotation direction (traveling direction) of the cooling roll 5, is substantially parallel to the reference surface 45.

  Here, the reason why the front lip is inclined will be described. The inventors of the present invention performed detailed observation of the nozzle portion during casting and investigated the cause of occurrence of the ribbon breakage. As a result, at the start of production of the ribbon, a phenomenon was observed in which a part of the molten alloy sprayed from the nozzle was scattered and adhered to the bottom surface of the front lip. In addition, deposits were also formed due to disturbance of the paddle at the time of manufacture, and these deposits grew as the production of the ribbons progressed.

  Even if the deposit occurs, it will not affect the ribbon, but if the deposit grows and contacts the ribbon, the ribbon will be scratched. However, the ribbon rupture started from scratches.

  In addition, when the deposit was large, it contacted the cooling roll and not only scratched the ribbon but also destroyed the nozzle.

  When the conventional nozzle is used, these phenomena cannot be avoided unless the gap is kept large so that deposits do not come into contact with each other. However, as the gap is increased, air is easily entrapped in the molten metal, so that the surface properties of the ribbon are deteriorated and the properties of the ribbon are deteriorated.

  Therefore, it is conceivable to increase the jet pressure of the molten alloy. However, the plate thickness becomes thicker and partially crystallized, resulting in not only brittleness but also deterioration of magnetic properties.

  For this reason, in this embodiment, the front lip is inclined. That is, in the present embodiment, the end surface 44 of the front lip 41 is inclined from the reference surface 45 by an angle θ. And since such an inclination is provided, even if the deposit | attachment 21 generate | occur | produces, the deposit | attachment 21 cannot contact the amorphous alloy ribbon 6 easily. As a result, it is possible to stably cast an amorphous alloy ribbon having good surface properties and magnetic properties while reducing the gap so that air is not involved.

  If the gap of the front lip 41 is made larger than the gap of the rear lip 42 without making the end surface 44 an inclined surface, the molten alloy 2 tends to overflow to the front lip 41 side and the paddle becomes unstable. . Therefore, the ribbon cannot be stably cast.

  Here, the angle θ is desirably 5 ° to 45 °. When the angle θ is less than 5 °, the deposit may come into contact with the ribbon when the gap is reduced. On the other hand, if it exceeds 45 °, the load of the thermal shock on the tip portion of the front lip 41 becomes large, and the front lip 41 may be lost. Furthermore, it may be difficult to ensure the accuracy of alignment with the rear lip 42. Therefore, the angle θ is desirably 5 ° to 45 °. In order to prevent breakage more reliably, the angle θ is more desirably 7 ° to 45 °, and a more desirable angle θ is 10 ° to 45 °.

The thicknesses W ₁ and W ₂ of the front lip 41 and the rear lip 42 are preferably 0.2 mm or more. If the thicknesses W ₁ and W _{2 of the} front lip 41 and the rear lip 42 are less than 0.2 mm, it may be difficult to accurately process each lip. Further, particularly at the tip portion, the thermal shock load increases, and the front lip 41 and the rear lip 42 may be lost. In addition, since the cost is increased when the thickness of the front lip 41 and the rear lip 42 is large, the thicknesses W ₁ and W ₂ of the front lip 41 and the rear lip 42 are 0.2 mm to 20 mm from a practical viewpoint. More desirably.

In addition, as shown in FIG. 3, the front-end | tip part of the rear lip 42 may have a projection shape. According to such a structure, the cost of material can be reduced. In this case, it is desirable that the thickness W ₄ of the tip is 0.2 mm or more. Moreover, as shown in FIG. 4, the front-end | tip part of the front lip 41 and the rear lip 42 may be projecting. Also in this case, it is desirable that the thicknesses W ₃ and W ₄ of the tip end portion are 0.2 mm or more.

  Further, in order to inject the molten alloy 2 onto the cooling roll 5 and stabilize the shape of the paddle, the slit thickness W is desirably 0.3 mm to 2 mm. When the slit thickness W is less than 0.3 mm, it becomes difficult for the molten alloy 2 to flow through the slit 43, and it may be difficult to stably cast the ribbon. If the slit thickness W exceeds 2 mm, the paddle shape may become unstable even if the gap is reduced, and it may be difficult to maintain stable surface properties. In order to cast the ribbon more stably, the slit thickness W is more preferably 0.5 mm to 1.5 mm.

  The end surface 44 does not need to be a flat surface, and it is sufficient that the distance between the end surface 44 and the reference surface 45 increases as the distance from the slit 43 increases. That is, the end surface 44 may be a curved surface. However, when the nozzle 4 is made of ceramics, it is desirable that the nozzle 4 be flat for processing efficiency. Further, it is conceivable that the end surface of the rear lip is also inclined, but only the processing is increased, and the inclination may or may not be added.

Examples of the present invention will be described below.
In the apparatus shown in FIG. 1, the nozzle 4 made of silicon nitride and provided with a front lip having an inclination angle of 6 ° (sample No. 1) was used. At this time, the thickness of the front lip and the rear lip was 10 mm, and the slit thickness was 0.85 mm. Then, a molten alloy 2 having a composition of atomic% Fe: 80.5%, Si: 6.5%, B: 12.0%, C: 1.0% is supplied to the tundish 1, and the stopper 3 is pulled up. The molten alloy 2 was sprayed from the discharge port 46 of the rectangular slit-shaped nozzle 4 having a slit thickness of 0.85 mm and a slit width of 170 mm toward the cooling roll 5 having a diameter of 1198 mm and a roll width of 250 mm. When spraying, the peripheral speed of the cooling roll 5 was 21 m / s, and the gap was 200 μm.

  Under the above conditions, an amorphous alloy ribbon having a plate width of 170 mm and a plate thickness of about 30 μm was cast, and the fracture occurrence rate was investigated. In addition, the same experiment was carried out on the same silicon nitride made with front lips with 12 °, 26 °, and 45 ° end face inclination angles θ (sample Nos. 2 to 4), and cast under the respective conditions. The fracture rate of the amorphous alloy ribbon was also investigated. The fracture occurrence rate is the ratio of the number of castings at which fractures occur to the number of castings.

  In addition, as a comparative example, an experiment was similarly performed on the same silicon nitride made of the same silicon nitride and having an end surface inclination angle θ of 0 ° (sample No. 5), and the fracture occurrence rate was investigated. The respective measurement results are shown in Table 1 below.

  As shown in Table 1, when a nozzle having an inclination angle θ of 0 ° was used, fracture was almost 100% when the gap was set to 200 μm. On the other hand, no breakage occurred when using nozzles with inclination angles θ of 12 °, 26 °, and 45 °. Further, when a nozzle having an inclination angle θ of 6 ° was used, the fracture occurrence rate was 10%, and the fracture was small.

  In addition, good results were obtained with respect to surface properties and magnetic properties in any sample.

  As described above, according to this example, even when an amorphous alloy ribbon is cast with a gap of 200 μm, the ribbon fracture hardly occurs and the amorphous alloy ribbon with excellent surface properties is stabilized. It can be said that it can be cast. Thus, it can be said that an amorphous alloy ribbon having good magnetic properties can be stably cast.

DESCRIPTION OF SYMBOLS 1 Tundish 2 Molten alloy 3 Stopper 4 Nozzle 5 Cooling roll 6 Amorphous alloy ribbon 7 Winding roll 21 Deposit 41 Front lip 42 Rear lip 43 Slit 44 End surface 45 Reference surface 46 Discharge port

Claims (4)

A front lip located in front of the rotation direction of the cooling roll ;
A rear lip located behind the cooling roll in the rotational direction and forming a slit through which the molten alloy flows between the front lip;
Have
At least the end surface on the discharge side of the molten alloy of the front lip is a plane perpendicular to the direction in which the slit extends and passes through the molten alloy discharge port of the slit. Is inclined in a direction away from the cooling roll from the boundary of
The angle between the end face and the reference plane is 5 ° to 45 °, and the rapidly solidified ribbon casting nozzle.   The rapidly solidified ribbon casting nozzle according to claim 1, wherein the front lip and the rear lip have a thickness of at least 0.2 mm.   The rapidly solidified ribbon casting nozzle according to claim 1 or 2, wherein the slit has a thickness of 0.3 mm to 2 mm. Injecting a molten alloy from the rapidly solidified ribbon casting nozzle according to any one of claims 1 to 3 onto a rotating cooling roll;
Solidifying the molten alloy on the surface of the cooling roll;
A method for producing an amorphous ribbon characterized by comprising:

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