JP7109014B2 - Air bubble disperser and impeller - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bubble dispersing device and an impeller for blowing refined gas into molten metal.

Molten aluminum or aluminum alloy contains impurities such as alkali metals, aluminum carbide, hydrogen gas, and fine powder of furnace materials. Impurities with a low specific gravity are floated and separated by blowing refined gas such as chlorine, nitrogen, or Ar gas into the molten metal as fine bubbles. At the time of blowing the purified gas, if the purified gas is blown into the molten metal while generating a whirlpool, the blown purified gas becomes fine bubbles and is efficiently dispersed in the molten metal, thereby improving the treatment efficiency.

For example, Patent Literature 1 discloses a bubble dispersion device provided with a rotary shaft having a through hole for purified gas and an impeller fixed to the tip. According to this air bubble dispersing device, the impeller generates a vortex in the molten metal. A cover with a cylindrical skirt is provided above the impeller, and the molten metal that has entered between the impeller and the cover is pushed out by the rotation of the impeller, forming a circulating flow of molten metal that flows through the container. Circulate. The purified gas is blown out into the molten metal from an opening provided in the bottom surface of the impeller, and is evenly dispersed throughout the molten metal as fine bubbles on the circulating flow of the molten metal. In the bubble dispersion device of Patent Document 1, the lower end of the skirt portion of the cover is formed at a position higher than the upper surface of the impeller. With such a configuration, a sufficient amount of molten metal that enters between the impeller and the coating is ensured, thereby stabilizing the molten metal circulation flow and improving the dispersibility of fine bubbles in the molten metal. It is possible to efficiently refine the molten alloy.

Japanese Patent Application Laid-Open No. 2000-309829

The purified gas blown out from the opening in the bottom surface of the impeller is flowed into the molten metal by the obliquely downward discharge flow generated by the rotation of the impeller. At this time, the outer periphery of the lower end of the impeller (the part through which the tips of the blades pass) becomes a dividing area where the bubbles of the purified gas are efficiently divided. be done. However, when the radial dimension of the impeller blades is large, part of the purified gas passes through the gap between the base ends of the blades near the center of the impeller and escapes upward without passing through the dividing region. As a result, large bubbles may remain. In other words, there is still room for improvement in the bubble dispersion efficiency.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide an air bubble dispersing device and an impeller capable of efficiently dividing air bubbles.

A first invention for solving such problems is a bubble dispersion device for blowing a refined gas into a molten metal, wherein a rotating shaft having a through hole for supplying the refined gas and attached to the lower end of the rotating shaft with an impeller that is The impeller includes a central body portion having gas ejection holes communicating with the through holes, a plurality of blade portions arranged at equal intervals in the circumferential direction of the impeller and inclined with respect to the axial direction of the impeller, and a plurality of blade portions adjacent to each other. and a bubble guiding portion that covers the gap between the blades that are aligned with each other, and the upper surface of the bubble guiding portion is inclined so that the base end side of the blade portion is higher and the tip side of the blade portion is lower. It is characterized by

According to the air bubble dispersion device of the present invention, the purified gas ejected from the gas ejection holes is caused to flow to the tip portion of the blade portion by the air bubble guide portion. In the bubble dividing region through which the tip of the blade passes, the bubbles of the purified gas are efficiently divided. As a result, finely divided air bubbles can be efficiently dispersed in the molten metal. Further, as the impeller rotates, the molten metal flows along the upper surface of the air bubble guiding portion and is straightened, so that the discharge amount of the discharge flow generated obliquely downward from the outer peripheral portion of the impeller increases. This creates a circulating flow within the melt and the purified gas spreads throughout the melt.

Further, in the air bubble dispersion device according to the present invention, it is preferable that the outer end of the air bubble guiding portion is positioned closer to the base end than the tip of the blade portion. According to such a configuration, the purified gas ejected from the gas ejection hole is flowed by the air bubble guiding portion to the divided region of the tip portion of the blade portion, and then begins to float and collide with the tip portion of the blade portion. , is more efficiently decoupled.

Furthermore, in the air bubble dispersion device according to the present invention, it is preferable that the bottom surface of the air bubble guiding portion is flush with the bottom surface of the blade portion. According to such a configuration, the purified gas ejected from the gas ejection holes smoothly flows to the outer peripheral side along the bottom surfaces of the vane portion and the bubble guide portion.
Further, in the air bubble dispersing device according to the present invention, it is preferable that the side surface of the blade portion, which is forward in the rotation direction, is slanted obliquely downward. With such a configuration, the molten metal is urged downward by the vanes, and a circulating flow is generated in the molten metal container.

A second aspect of the present invention for solving the above-mentioned problems is an impeller used in a bubble dispersing device for blowing refined gas into molten metal. A central body portion having gas ejection holes for supplying the purified gas from the bottom surface, a plurality of blade portions arranged at equal intervals in the circumferential direction of the impeller and inclined with respect to the axial direction of the impeller, and the adjacent and a bubble guiding portion that covers a gap between the blades , and the upper surface of the bubble guiding portion is inclined so that the base end side of the blade portion is higher and the blade tip portion side is lower. characterized by

When the impeller according to the present invention is attached to the lower end of the rotating shaft and is rotated in the molten metal while supplying the purified gas, the purified gas ejected from the gas ejection holes forms bubbles in the same manner as in the invention according to claim 1. It is flowed to the tips of the blades by the guide section. In the bubble dividing region through which the tip of the blade passes, the bubbles of the purified gas are efficiently divided. As a result, finely divided air bubbles can be efficiently dispersed in the molten metal. Further, as the impeller rotates, the molten metal flows along the upper surface of the air bubble guiding portion and is straightened, so that the discharge amount of the discharge flow generated obliquely downward from the outer peripheral portion of the impeller increases. This creates a circulating flow within the melt and the purified gas spreads throughout the melt.

In the impeller according to the present invention, it is preferable that the outer ends of the air bubble guiding portions are positioned closer to the base end than the tips of the blades. Further, it is preferable that the bottom surface of the air bubble guiding portion is flush with the bottom surface of the blade portion. Further, it is preferable that the side surface of the blade portion, which is forward in the rotation direction, is slanted obliquely downward. According to such a configuration, it is possible to obtain the same effects as those of the second to fourth aspects of the invention.

According to the present invention, bubbles in molten metal can be efficiently divided.

It is a top view showing the impeller concerning the embodiment of the present invention. It is a front view showing an impeller according to an embodiment of the present invention. It is a bottom view showing the impeller according to the embodiment of the present invention. It is the perspective view which showed the impeller which concerns on embodiment of this invention from diagonally upward. It is the perspective view which showed the impeller which concerns on embodiment of this invention from diagonally downward. FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A; FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A; It is a perspective view for explaining the shape of the impeller according to the embodiment of the present invention. 1 is an exploded perspective view showing an air bubble dispersion device according to an embodiment of the present invention; FIG. 1 is a side view showing a bubble dispersion device according to an embodiment of the present invention; FIG. It is the side view which showed the use condition of the air-bubble dispersion apparatus which concerns on embodiment of this invention.

A bubble dispersion device and an impeller according to embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 8, the bubble dispersing device 1 is a device for blowing refined gas as fine bubbles into molten metal M to float and separate impurities. The metal is for example aluminum or an aluminum alloy. As also shown in FIGS. 6 and 7, the air bubble dispersion device 1 according to this embodiment includes a rotating shaft 10 and an impeller 20. As shown in FIG.

The rotating shaft 10 is made of graphite, ceramics, or the like, which has excellent heat resistance and can withstand erosion by molten metal. The rotating shaft 10 has a through hole 11 extending in the axial direction. The through-hole 11 is a channel for supplying purified gas, and is formed over the entire length of the rotating shaft 10 . A male threaded portion 12 that is screwed into a female threaded portion 25 of the impeller 20 is formed at the lower end of the rotating shaft 10 . The male threaded portion 12 is oriented to be tightened by the female threaded portion 25 of the impeller 20 when the rotary shaft 10 is rotated with respect to the impeller 20 in the rotational direction of the impeller 20 .

The impeller 20 is made of the same material as the rotating shaft 10 and attached to the lower end of the rotating shaft 10 . As shown in FIGS. 1 to 4, the impeller 20 includes a central body portion 21, blade portions 22, and air bubble guide portions 23. As shown in FIGS. The central trunk portion 21 is positioned at the center of rotation of the impeller 20 and extends vertically. A gas ejection hole 24 communicating with the through hole 11 is formed in the center body portion 21 . The gas ejection holes 24 vertically penetrate the central body portion 21 . The upper end portion of the gas ejection hole 24 is enlarged in diameter, and a female screw portion 25 is formed on the inner peripheral surface. The male threaded portion 12 of the rotary shaft 10 is screwed into the female threaded portion 25 .

The blades 22 stir the molten metal M and are provided in plurality around the central body 21 . The blades 22 are arranged at equal intervals in the circumferential direction and radially extend outward from the central body 21 . The blade portion 22 has an upper surface 22a and a lower surface 22b offset from the center of the shaft portion of the impeller 20 by a predetermined angle (30° in this embodiment). Both the upper surface 22a and the lower surface 22b are horizontal. A tip surface 22c connecting the upper surface 22a and the lower surface 22a and both side surfaces 22d and 22e are inclined. A center line (extending in the vertical direction) connecting the widthwise intermediate portions of the tip end face 22c is inclined with respect to the axial direction of the impeller 20 when the tip end face 22c is viewed from the front. One side surface 22d faces obliquely upward, and the other side surface 22e faces obliquely downward. The angle of inclination of the vanes 22 (the angle of inclination between the center line of the tip surface 22c and the axial direction of the impeller 20) is 30 to 60°, taking into consideration the thrust applied to the molten metal M and the driving force required to rotate the impeller 20. is preferably in the range of

The bubble guiding portion 23 guides the purified gas ejected from the gas ejection hole 24 to the tip portion side of the blade portion 22 . The air bubble guiding portion 23 covers the gap between the blade portions 22, 22 adjacent in the circumferential direction by a predetermined length from the base end portion of the blade portion 22 toward the tip side. The bubble guide portions 23 are provided at six locations corresponding to the six blade portions 22, 22, . . . . The tip (outer end) of the air bubble guiding portion 23 is positioned closer to the base end than the tip of the blade. The upper surface of the air bubble guiding portion 23 is inclined so that the base end side of the blade portion 22 is higher and the tip end portion side of the blade portion 22 is lower. The upper end of the base end portion of the air bubble guiding portion 23 is at the same height as the upper surface of the blade portion 22 . The bottom surface of the bubble guide portion 23 is flush with the bottom surface of the blade portion 22 . Virtually connecting the six bubble guiding portions 23, 23, . . . forms a truncated cone (see FIG. 5). That is, as shown in FIG. 5, the impeller 20 has a shape in which a truncated cone 23a is combined with a shape including a central body portion 21 and blade portions 22. As shown in FIG.

When fixing the impeller 20 to the rotating shaft 10 , the male threaded portion 12 of the rotating shaft 10 is screwed into the female threaded portion 25 of the impeller 20 . As the male threaded portion 12 is screwed in, the surface around the base end of the male threaded portion 12 of the rotating shaft 10 is pressed against the upper surface of the impeller 20 , so the impeller 20 is in close contact with the rotating shaft 10 without a gap. Further, since the male threaded portion 12 is formed so as to be tightened when the impeller 20 rotates, the impeller 20 can be firmly crimped without loosening during operation.

When the air bubble dispersion device 1 is immersed in the molten metal M stored in the molten metal container 2 and the impeller 20 is rotated, the molten metal M to which the impeller 20 is applied with thrust is sent into the molten metal container 2 . At this time, the molten metal M is urged downward by the vanes 22 and rectified along the upper surface of the air bubble guiding portion 23, and is sent out obliquely downward from the lower portion of the outer peripheral portion of the impeller 20. As shown in FIG. Since the discharged flow of the molten metal M is rectified by the upper surface of the air bubble guiding portion 23 , the discharge amount of the discharged molten metal M is increased, so that a circulating flow is generated in the molten metal container 2 .

The bubbles G of the purified gas ejected from the gas ejection holes 24 are flowed to the tip portions of the blade portions 22 by the bottom surface of the impeller 20 including the bottom portion of the bubble guide portion 23 . The peripheral speed of the tip of the blade 22 is high, and the corner of the tip of the blade 22 cuts through the air bubbles. That is, the portion through which the tip of the blade portion 22 passes becomes the division region of the air bubble G. As shown in FIG. In the dividing region, the bubbles G of the purified gas are efficiently divided, but in the present embodiment, the bubbles G are guided to the dividing region by providing the bubble guiding portion 23, so that the bubbles G are efficiently divided. be able to. By finely dividing the bubbles G, the surface area thereof increases, and the impurity removal reaction of the molten metal M is promoted.

In addition, since the outer end of the air bubble guiding portion 23 is positioned closer to the base end than the tip of the blade portion 22, the air bubbles G are easily guided to the dividing region. Specifically, most of the bubbles G of the purified gas ejected from the gas ejection holes 24 flow along the bottom surface of the bubble guide portion 23 to the outer end of the bubble guide portion 23, and then start to float. Since it collides with the tip corners of the blades 22 in the splitting region, it is split more efficiently. Furthermore, since the bottom surface of the air bubble guiding portion 23 is flush with the bottom surface of the blade portion 22 , the air bubbles G are smoothly flowed along the bottom surfaces of the blade portion 22 and the air bubble guiding portion 23 to the outer peripheral side.

As described above, the bubbles G efficiently divided in the dividing region are dispersed throughout the molten metal M due to the circulating flow of the molten metal M.

In addition, in the air bubble dispersion device 1 and the impeller 20 according to the present invention, the air bubble guiding portion 23 guides the air bubbles G to the outer peripheral portion of the impeller 20, so there is no need to provide a cover as in the prior art. Therefore, it is possible to reduce the number of components of the air bubble dispersion device 1 and reduce the manufacturing cost.

Although the embodiments of the present invention have been described above, the present invention can be appropriately modified in design within the scope of the invention. For example, in the above-described embodiment, the inclined surface of the upper surface of the air bubble guiding portion 23 is flat, but it may be curved. With such a configuration, the molten metal M may flow more smoothly.

Further, in the above-described embodiment, the bottom surface of the air bubble guiding portion 23 is flush with the bottom surface of the blade portion 22, but for example, a step may be provided so that the bottom surface of the air bubble guiding portion 23 is one step higher. According to such a configuration, the air bubble G can be guided to the gap between the blade portions 22, 22 at the outer end portion of the air bubble guiding portion 23, and the dividing efficiency can be further enhanced.

In the above embodiment, the air bubble dispersion device 1 is immersed in the molten metal M so that the rotating shaft 10 is vertical, but it is not limited to this. Depending on the shape of the molten metal container 2, the air bubble dispersion device 1 may be arranged so that the rotating shaft 10 is inclined. According to such a configuration, a circulating flow of the molten metal M may easily occur.

REFERENCE SIGNS LIST 1 air bubble dispersing device 10 rotating shaft 11 through hole 20 impeller 21 central body 22 vane 23 air bubble guide 24 gas ejection hole G air bubble M molten metal

Claims (8)

In a bubble dispersion device that blows refined gas into molten metal,
A rotating shaft having a through hole for supplying the purified gas, and an impeller attached to the lower end of the rotating shaft,
The impeller includes a central body portion having gas ejection holes communicating with the through holes, a plurality of blade portions arranged at equal intervals in the circumferential direction of the impeller and inclined with respect to the axial direction of the impeller, and a plurality of blade portions adjacent to each other. and a bubble guiding portion that covers the gap between the matching blades,
The air bubble dispersing device, wherein the upper surface of the air bubble guiding portion is inclined so that the base end side of the blade portion is higher and the tip end portion side of the blade portion is lower. 2. The air bubble dispersion device according to claim 1 , wherein an outer end portion of the air bubble guide portion is positioned closer to the base end portion than the tip of the blade portion. The air bubble dispersion device according to claim 1, wherein the bottom surface of the air bubble guiding portion is flush with the bottom surface of the blade portion. The air bubble dispersing device according to any one of claims 1 to 3 , wherein a side surface of the blade portion that is forward in the rotational direction is slanted downward. In the impeller used in the bubble dispersion device that blows refined gas into the molten metal,
A central body portion having gas ejection holes for supplying the purified gas from the bottom surface, a plurality of blade portions arranged at equal intervals in the circumferential direction of the impeller and inclined with respect to the axial direction of the impeller, and the adjacent and a bubble guiding portion that covers the gap between the blades,
The impeller, wherein the upper surface of the air bubble guiding portion is inclined so that the base end portion of the blade portion is higher and the tip end portion of the blade portion is lower. 6. The impeller according to claim 5 , wherein an outer end portion of the air bubble guide portion is positioned closer to the base end portion than the tip of the blade portion. The impeller according to claim 5 , wherein the bottom surface of the air bubble guiding portion is flush with the bottom surface of the blade portion. The impeller according to any one of claims 5 to 7 , wherein a side surface of the blade portion, which is forward in the rotational direction, is inclined obliquely downward.

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