JPH0753804Y2 - Rotating body for stirring molten metal - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is for stirring a molten metal for stirring a molten metal of a non-ferrous metal material such as aluminum or an aluminum alloy to float impurities on the surface of the molten metal and separate them. It concerns a rotating body.

[Conventional technology]

Conventionally, when casting a casting made of non-ferrous metal material such as aluminum or aluminum alloy, in order to float and separate impurities in the molten metal and absorbed hydrogen,
A purifying means is used in which a gas such as nitrogen or argon is blown into the molten metal, and bubbling and atomization are performed. In this case, rotating bodies such as rotary blades and rotary pumps are used. However, since these rotating bodies are mostly made of sintered carbon, the consumption in molten metal or molten metal is extremely large. There is a drawback that. In order to eliminate such drawbacks, attempts have been made in recent years to form the rotating body with a ceramic material, but as is well known, the ceramic material is, for example, silicon carbide or silicon nitride. However, it suffers from the drawback of being vulnerable to rapid thermal shock, and when the rotor is immersed in the molten metal, cracks occur, and in some cases, the rotor is damaged or destroyed. In order to eliminate such an inconvenience caused by the thermal shock, it has been attempted to form a rotor having a small wall thickness.

FIG. 6 is a longitudinal sectional view of an essential part showing an example of a conventional rotating body.
In FIG. 6, 1 is a rotating shaft, and a screw 2 is engraved on the lower end portion. Reference numeral 3 denotes a rotor, which is formed in a flat plate shape, has a female screw 4 engraved in the central portion thereof, and the female screw 4 is screwed into the male screw 2 to fix the rotor 3 to the lower end portion of the rotary shaft 1. .

[Problems to be solved by the device]

As described above, the rotor 3 is subjected to a rapid thermal shock due to the molten metal, but if the thickness t of the rotor 3 is made small in order to eliminate the inconvenience caused by this thermal shock, The length of the female screw 4 for fixing becomes short.
Therefore, the sticking force of the rotor 3 to the rotating shaft 1 is reduced, and when the rotor 3 is rotated in the molten metal, the rotor 3 swings as shown by an arrow M, and in an extreme case, the rotor 3 rotates. There is a problem of falling out of. On the other hand, it is not preferable to increase the wall thickness t in order to increase the fixing force of the rotor 3 to the rotating shaft 1 because the rotor 3 is cracked by thermal strain.

FIG. 7 is a longitudinal sectional view of a main part showing another example of the conventional rotating body. In FIG. 7, the rotor 3 has a large thickness in the central portion and a small thickness in the peripheral portion. By forming in this way, the female screw 4 to be engraved on the rotor 3
Of the rotor 3 can be sufficiently secured, and the fixing force of the rotor 3 to the rotary shaft 1 can be increased. However, as a result of forming the stepped portion 3a on the rotor 3 and this portion becomes a notch, there is a problem that mechanical stress and / or thermal stress is concentrated, resulting in damage.

In order to solve the problems existing in the above-mentioned prior art, the present applicant has already proposed a stirring machine for molten metal, which comprises a vertical rotary shaft having a hollow portion for gas supply and a rotor fixed to the lower end of the rotary shaft. In the rotating body, the rotating shaft and the rotor are formed of a nitride-based, boride-based, or carbide-based ceramic material, and the thickness of the rotor is gradually reduced from the central portion toward the peripheral portion. Applying for a device (Practical application 1-151279
issue).

4 and 5 are respectively a longitudinal sectional view and a bottom view of an essential part showing an embodiment of the above-mentioned improved device, and the same portions are the same as those of the sixth embodiment.
It is designated by the same reference numeral as in FIGS. In both figures, the rotating shaft 1 and the rotor 3 are formed in a disk shape by a nitride-based ceramic material such as silicon nitride or sialon, a boride-based ceramic material such as titanium boride or zirconium boride, or a carbide-based ceramic material of silicon carbide. To do. A concave portion 6 communicating with the hollow portion 5 of the rotary shaft 1 is provided on the bottom surface of the rotor 3, and a radial groove 7 communicating with the concave portion 6 and opening to the peripheral portion of the rotor 3 is provided. The bottoms of the recesses 6 and the radial grooves 7 are formed horizontally. Next, reference numeral 8 is a concave groove, and a plurality of grooves are provided on the peripheral portion of the rotor 3. Further, the wall thickness of the rotor 3 is formed so as to gradually decrease from the central portion toward the peripheral portion. That is, the rotor 3 is formed in, for example, a truncated cone shape.

With the above configuration, when the rotary shaft 1 is connected to the drive device and the gas supply device (neither is shown), the rotary shaft 1 is rotated and the gas for cleaning the molten metal is introduced from the hollow portion 5, so that the rotor is If 3 is immersed in the molten metal, the molten metal can be purified. In this case, since the rotor 3 is formed so that the wall thickness gradually decreases from the central portion toward the peripheral portion as described above, it is possible to secure a sufficient length of the female screw 4 engraved on the rotor 3. Therefore, the fixing force of the rotor 3 to the rotating shaft 1 can be increased. Further, since the rotor 3 does not have the stepped portion 3a as shown in FIG. 7, it is possible to eliminate any accidental damage due to concentration of mechanical stress and / or thermal stress.

However, there is a problem that the above-mentioned improved invention should be further improved. That is, the above-mentioned nitrogen, argon, etc. are generally used as the gas for purifying the molten metal, but these gases are usually in a liquefied state to facilitate storage, transportation and handling. Is used after being vaporized under reduced pressure. For this reason, the rotary shaft 1 forming the gas supply passage is easily cooled rapidly, and the rotary shaft 1 made of a ceramic material whose tensile strength is not necessarily high.
There is a risk of cracks and breakage. When such an undesired accident occurs, not only is it impossible to carry out the molten metal purification action, but there is also the problem that the cleaning gas may leak and pollute the environment at the work site.

The present invention solves the problems existing in the above-mentioned prior art, and also solves some problems existing in the improved device, which is highly reliable and has a long life expectancy. Intended to provide the body.

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, a rotary body for stirring molten metal, comprising a vertical rotary shaft having a hollow portion for gas supply and a rotor fixed to the lower end of the rotary shaft, The rotor is made of a nitride-based, boride-based, or carbide-based ceramic material, and a hollow cylinder-shaped blow pipe for gas supply is coaxially inserted and fixed through a gap in the rotating shaft. We adopted the technical means of doing.

In the present invention, the gap between the inner surface of the rotary shaft and the outer surface of the blow pipe may be formed to have a substantially equal size therebetween, so that the two are locally closely adhered and a gap is formed in the other portion. But it's okay.

The rotary shaft and / or the blowing pipe may have a circular vertical cross-sectional profile, or may have a rectangular or other geometrical shape.

〔Example〕

1 and 2 are a partially omitted longitudinal sectional view and a bottom view, respectively, showing an embodiment of the present invention, and the same reference numerals are the same as those in FIGS. 4 and 5. In FIG. 1, reference numeral 10 denotes a blow pipe, which is made of, for example, solid carbon in a hollow cylindrical shape and is coaxially inserted and fixed in the rotary shaft 1.
A stepped portion 11 having a slightly larger outer diameter is formed at the upper end of the blow-in pipe 10, and is engaged with the stepped portion 12 provided on the inner surface of the rotary shaft 1 so that the blow-in pipe 10 is fixed. Configured. Next, at the upper end of the rotary shaft 1, four locking portions 13 having a plane parallel to the axis are provided. Next, the lower end portion of the connecting member 14 is formed into a hollow cylindrical surface having an inner diameter corresponding to the outer diameter dimension of the rotary shaft 1, so that the upper end portion of the rotary shaft 1 can be fitted. A set screw 15 is provided so as to face the locking portion 13 provided on the rotary shaft 1. Reference numeral 16 is a contact plate, which is formed of, for example, a steel material into a strip shape, and is abutted against the locking portion 13 and interposed. Then, when the set screw 15 is tightened, the contact plate 16 can be firmly pressed against the locking portion 13 of the rotary shaft 1, so that the rotary shaft 1 and the connecting member 14 can be integrally fixed.

With the above configuration, when the rotary shaft 1 is connected to the drive unit and the gas supply unit (both not shown) via the connecting member 14, the rotary shaft 1 rotates and the gas for purifying the molten metal flows from the blow pipe 10. Since it is introduced, the molten metal can be purified by immersing the rotor 3 in the molten metal. In this case, the gas flowing through the blow-in pipe 10 has a low temperature, but since the blow-in pipe 10 is made of a heat insulating material such as solid carbon, the quenching action on the rotating shaft 1 can be almost ignored.
Therefore, the rotating shaft 1 is prevented from cracking, damage, etc., and the purification action of the molten metal is not hindered at all. Further, with the above configuration, the contact area between the contact plate 16 and the locking portion 13 to which torque is transmitted is increased, so that the fixing force between the connecting member 14 and the rotary shaft 1 can be increased, and the relative movement between them or Relative rotation is eliminated, and the runout of the rotating shaft 1 and the occurrence of eccentricity can be prevented. Further, the rotary shaft 1 to be formed of a ceramic material does not need to be engraved with a screw as in the conventional one, and therefore there is no notch which causes local concentration of stress. The most general polishing means can be used for processing the locking portion 13, and the material can be formed into a rough shape in the state of the material, so that the processing operation is relatively easy.

FIG. 3 is a longitudinal sectional view of an essential part showing another embodiment of the present invention, in which the same parts are designated by the same reference numerals as those in FIGS. 1 and 2. In FIG. 3, 17 is a gap, and the rotary shaft 1
It is provided between the inner surface of the blow tube and the outer surface of the blow pipe 10. Reference numeral 18 denotes a sealing member, which is formed, for example, by filling a paste made of a refractory material such as Al ₂ O ₃ into a gap 17 near the lower end of the rotary shaft 1 in a ring shape. The structure near the upper end of the rotary shaft 1 is the same as that of the embodiment shown in FIG.

With the above configuration, it is possible to prevent the phenomenon that the rotary shaft 1 is rapidly cooled by the low temperature gas flowing in the blow pipe 10, but by forming the gap 17 between the rotary shaft 1 and the blow pipe 10, The heat insulation effect can be further improved.

In this embodiment, an example in which the rotor is formed into a frusto-conical shape has been shown, but the upper contour line in the vertical cross section of the rotor is formed into a curved line (the upper side may be concave or convex). Good. In addition, we described an example in which the bottom of the recess and the radial groove to be provided on the bottom surface of the rotor were formed horizontally, but it was partially or entirely flat or curved so as to incline upward from the center of the rotor toward the peripheral edge. You may form in. In the case of a curved surface, the curved surface is such that the inclination angle increases toward the peripheral edge. By forming as described above, it is possible to prevent the gas from staying in the radial groove and to make the movement of the gas toward the peripheral portion smoother. Further, even if a protrusion is provided in place of or together with the concave groove provided in the peripheral portion of the rotor, the stirring and flowing action of the molten metal and / or bubbles is the same. Note that these concave grooves and / or protrusions may be provided in the peripheral opening of the radial groove.

[Effect of device]

Since the present invention has the structure and operation as described above,
It is possible to prevent the rapid cooling action of the rotating shaft due to the flow of the low-temperature gas for purifying the molten metal, and prevent the rotating shaft from cracking or damage. Therefore, the molten metal cleaning action can be smoothly performed, the reliability can be significantly improved, and the molten metal can withstand long-term use.

[Brief description of drawings]

FIGS. 1 and 2 are vertical cross-sectional views and bottom views of a partially omitted main part showing an embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view of the main part showing another embodiment of the present invention, and FIG. 5 and 6 are a longitudinal sectional view and a bottom view of a main part showing an embodiment of the improved device, respectively.
Each of FIG. 7 and FIG. 7 is a longitudinal sectional view of an essential part showing an example of a conventional rotating body. 1: rotating shaft, 3: rotor, 10: blow-in pipe.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-86827 (JP, A) Actual development: S58-58647 (JP, U) JP-B-59-38815 (JP, B2)

Claims (1)

[Scope of utility model registration request] 1. A molten metal stirring rotor comprising a vertical rotary shaft having a hollow portion for supplying gas and a rotor fixed to the lower end of the rotary shaft, wherein the rotary shaft and the rotor are nitride-based, Molten metal characterized in that it is formed of a compound-based or carbide-based ceramic material, and that a blow tube for gas supply, which is formed into a hollow cylindrical shape by a heat insulating material in the rotating shaft, is coaxially inserted and fixed through a gap. Rotating body for stirring.