JP2009114506A - Impeller for stirring molten metal and molten metal stirring apparatus therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impeller for stirring molten metal excellent in stirring capacity. <P>SOLUTION: The impeller 1 for stirring the molten metal includes four stirring blades 5 projecting in the diameter direction from the neighborhood of the low end part 4 of a rotating shaft 2. The stirring blades 5 are respectively formed generally as a square-column state having an upper surface 11, a lower surface 12, a front surface 13, a rear surface 14 and an outer side surface 15. The stirring blade 5 is further provided with a rear part upper cutting-off surface 16 as an inclining surface cutting off the corner part from the upper surface 11 to the rear surface 14, a front part outer cutting-off surface 17 as the inclining surface cutting off the corner part from the front surface 13 to the outer side surface 15 and the front lower cutting-off surface 18 as the inclining surface cutting off the corner part from the lower surface 12 to the front surface 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an impeller for stirring a molten metal that is used for mixing an additive having a specific gravity lower than that of a molten metal and the molten metal, and is immersed in the molten metal and rotated and stirred, and a molten metal stirring device including the impeller.

  Conventionally, refining to reduce impurities in molten metal is performed by blowing or mechanically stirring the molten metal while adding flux or adding flux. Since the refining reaction proceeds at the interface between the molten metal and the flux, it is preferable for promoting the reaction to stir the molten metal and wind the flux into the molten metal to widen the reaction interface between the molten metal and the flux. Flux has a smaller specific gravity than molten metal and floats on the surface of the molten metal only by adding it. Therefore, in order to mix the molten metal and the flux to widen the reaction interface, gas blowing stirring or mechanical stirring is performed.

  Comparing gas blowing agitation with mechanical agitation, mechanical agitation is more likely to repeatedly entrain flux that rises after being entrained in the molten metal, so that the refining reaction can proceed more effectively. For this reason, for example, in the desulfurization of molten steel, a mechanical stirring type desulfurization method is performed in which a desulfurization flux is added to the molten steel in the ladle, and a rotating body having a stirring blade called an impeller is immersed in the molten steel and rotated and stirred. ing.

  In the desulfurization of molten steel that is mechanically stirred using an impeller, various proposals have been made to realize efficient desulfurization. For example, it has been proposed to increase the rotational speed of the impeller to reduce the temperature dependence of the desulfurization rate and to improve the desulfurization rate by low-temperature operation (see Non-Patent Document 1). However, when the number of revolutions of the impeller is increased, there is a problem that the life of the impeller is shortened, the scattering of molten steel is increased, and vibration due to the rotation is increased.

  In addition, it has been proposed that a baffle plate is provided in a vessel in which the molten steel is placed, thereby generating irregular upstream and downstream in the molten steel during stirring, and efficiently entraining the flux to improve the desulfurization rate (non- Patent Document 2). However, since the molten steel is hot, the baffle plates that are provided in the molten steel are likely to be damaged by heat and the flow of the molten steel, and the fragments of the baffle that are mixed into the molten steel due to the damage cause nonmetallic inclusions. There is a problem.

  Further, it has been proposed to make the flow of the molten steel irregular and improve the stirring ability by rotating the impeller so that the axis of the impeller is deviated from the center line of the container in which the molten steel is placed (see Non-Patent Document 3). ). However, when the impeller is eccentrically arranged and rotated, vibration is promoted. If the amount of eccentricity is reduced, vibration can be reduced to an extent that there is no problem, but if the amount of eccentricity is small, there is a problem that the effect of improving the stirring ability due to the eccentricity cannot be expected.

Thus, it has been proposed to improve the stirring ability by devising the shape of the impeller stirring blade and forming upstream and downstream in the molten steel in the container (see, for example, Patent Document 1 and Patent Document 2). In Patent Documents 1 and 2, it is assumed that the stirring ability is improved by devising the shape of the impeller stirring blade, and the effect of shortening the desulfurization time can be obtained even at low speed rotation.
CAMP-ISIJ, Japan Iron and Steel Institute, 2002, Vol. 15, p. 873 Iron and steel, Japan Iron and Steel Association, 2004, Vol. 90, no. 6, p. 329-333 Iron and Steel, Japan Iron and Steel Association, 2002, Vol. 88, no. 1, p. 1-7 Japanese Utility Model Publication No. 05-27044 Japanese Utility Model Publication No. 07-41400

  In Patent Documents 1 and 2, molten steel of ordinary carbon steel is targeted for desulfurization refining. However, in the refining of molten metal, there is a case where the refining cannot be efficiently performed unless the stirring is stronger than that in the desulfurization of ordinary carbon steel. For example, desulfurization of molten stainless steel. Stainless steel melt contains a large amount of Cr in order to improve corrosion resistance. Since Cr is an element that reduces the activity of S, the desulfurization reaction does not easily proceed in stainless steel containing Cr. Therefore, desulfurization of molten stainless steel requires stronger stirring than desulfurization of ordinary carbon steel. The stirrability that can be achieved with ordinary carbon steel by the impeller having the stirrer blade shape disclosed in Patent Documents 1 and 2 is not sufficient for desulfurization of molten stainless steel.

  The objective of this invention is providing the impeller for molten metal stirring which is excellent in stirring capability, and a molten metal stirring apparatus provided with the same.

  The impeller for stirring a molten metal according to the present invention is used to stir molten metal with a plurality of stirring blades that are immersed in the molten metal in a container from above and rotate and project radially from the vicinity of the lower end of the rotating shaft. It is done. The stirring blades are each roughly formed in a prismatic shape having an upper surface, a lower surface, a front surface, a rear surface, and an outer surface, the front surface is the front side in the rotational direction, the rear surface is the rear side in the rotational direction, and the outer surface is the radial direction. Outside. The stirring blade further includes a rear upper notch surface that is an inclined surface with a corner notched from the upper surface to the rear surface, a front outer notch surface that is an inclined surface with a corner notched from the front surface to the outer surface, and a lower surface to the front surface. It has the front lower notch surface used as the inclined surface which notched the corner | angular part, It is characterized by the above-mentioned.

  In the present invention, the front outer notch surface is formed to be inclined downward as it goes rearward in the rotation direction.

  In the present invention, the stirring blade has a rear lower notch surface that is an inclined surface with a corner portion notched from the lower surface to the rear surface.

  In the present invention, the stirring blade is characterized in that an angle formed by a rear surface with respect to the lower surface is less than 90 degrees.

  Further, the present invention includes any one of the above-described molten metal stirring impellers and a container in which the molten metal is placed, and the molten metal stirring impeller is disposed so that the axis of the rotation axis is deviated from the center line of the container. This is a molten metal stirring device.

  According to the present invention, the rear upper notch surface of the stirring blade creates a flow that draws the molten metal downward, and the front outer notch surface extrudes the molten metal radially outward of the rotating shaft and flows downward. The front lower notch surface creates a flow that pushes the molten metal downward. By forming a notch surface in the stirring blade in this way, it becomes possible to create a strong flow in the outward and vertical directions in the molten metal in the container, and therefore, an impeller for stirring the molten metal having excellent stirring ability is provided. Can do.

  Further, by forming a rear lower notch surface on the molten metal stirring impeller, an upward flow toward the impeller side is created. Stagnation of the flow is likely to occur on the rear surface of the impeller, but the lower notch surface reduces the flow stagnation and can supply a larger volume to the front surface of the impeller. An impeller can be provided.

  In addition, by making the angle formed by the rear surface connected to the rear upper notch surface with respect to the lower surface less than 90 degrees, the molten metal drawn downward on the rear upper notch surface flows smoothly downward along the rear surface. Therefore, it is possible to provide an impeller for stirring a molten metal that is further excellent in stirring ability.

  Furthermore, according to the molten metal stirring device of the present invention, the molten metal stirring impeller excellent in stirring ability is arranged and rotated so that the axis of the rotation axis is deviated from the center line of the container. By rotating the impeller for stirring the molten metal eccentrically, it is possible to create an irregular and complicated flow in the molten metal. Moreover, since the impeller for stirring a molten metal having excellent stirring ability can stir sufficiently strongly with a small amount of eccentricity, vibration of the apparatus due to eccentricity is suppressed. Thus, the molten metal stirring apparatus which is excellent in stirring ability can be provided.

  FIG. 1 shows a configuration of a molten metal stirring impeller 1 according to an embodiment of the present invention. The molten metal stirring impeller 1 is immersed in the molten metal in the container from above and rotates clockwise as indicated by an arrow 10 to protrude in the radial direction from the vicinity of the lower end 4 of the rotating shaft 2. Used to stir the molten metal. In the present embodiment, a molten metal stirring impeller 1 having four stirring blades 5 is illustrated. Hereinafter, the impeller for stirring molten metal is simply abbreviated as an impeller.

  The stirring blades 5 are each generally formed in a prismatic shape having an upper surface 11, a lower surface 12, a front surface 13, a rear surface 14, and an outer surface 15. Here, the front surface 13 is the front side in the rotational direction, the rear surface 14 is the rear side in the rotational direction, and the outer surface 15 is the outer side in the radial direction. The lower surface 12 is formed so as to be perpendicular to the axis 3 of the rotating shaft 2.

  The stirring blade 5 further includes a rear upper cut surface 16 that is an inclined surface with a corner cut out from the upper surface 11 to the rear surface 14, and a front outer cut surface that is an inclined surface with a corner cut out from the front surface 13 to the outer surface 15. 17, a front lower notch surface 18 that is an inclined surface with a corner notched from the bottom surface 11 to the front surface 13, and a rear lower notch surface 19 that is an inclined surface with a corner notched from the bottom surface 12 to the rear surface 14. The front outer notch surface 17 is formed so as to incline downward as it goes rearward in the rotational direction.

  The stirring blade 5 is formed such that the angle θ formed by the rear surface 14 with respect to the lower surface 12 is less than 90 degrees. The lower limit of θ is not particularly limited, but is preferably 60 degrees or more. This is because if θ is less than 60 degrees, the thickness of the stirring blade 5 in the rotational direction is reduced, and there is a concern about strength reduction.

  As the material of the impeller 1, an amorphous refractory such as a refractory mortar is preferably used. The impeller 1 can be manufactured by forming an amorphous refractory into a desired shape and firing it.

  FIG. 2 shows the state of the molten metal flow formed by the stirring blade 5. Since each of the stirring blades 5 has the same shape, only one stirring blade 5 is shown in FIG. 2 for easy understanding of the flow state. All or part of the stirring blade 5 is immersed from above into the molten metal contained in the container, and the stirring blade 5 rotates around the axis 3 as the impeller 1 rotates about the axis 3. Due to the revolving motion of the stirring blade 5, the respective notch surfaces 16, 17, 18, 19 formed on the stirring blade 5 make the following flow in the molten metal.

  The rear upper notch surface 16 creates a flow 21 that draws molten metal downward. The front outer notch surface 17 creates a flow 22 for extruding the molten metal radially outward and circumferentially of the rotary shaft 2 and a flow 23 for extruding the molten metal downward. The front lower notch surface 18 creates a flow 24 that pushes the molten metal downward.

  Further, the rear lower cut surface 19 creates an upward flow 25 toward the impeller side. The rear surface side of the impeller is liable to cause stagnation of the flow and reduces the volume of molten metal that can be extruded by the front surface of the impeller. The stagnation on the rear surface side of the impeller is eliminated by the flow 25, and a larger amount of molten metal can be discharged from the front surface of the impeller.

  Each notch surface 16, 17, 18, 19 of the stirring blade 5 draws and extrudes the molten metal to create an irregular and complex flow in the outward and vertical directions in the molten metal in the container, thereby improving the stirring ability. . Thus, by setting it as the stirring blade 5 of the shape which has a notch surface, the impeller 1 which is excellent in the stirring ability of a molten metal can be provided.

  The impeller 1 has a stirring ability mainly because the front outer notch surface 17 pushes the molten metal in the radial direction and the circumferential direction of the rotary shaft 2, and the front lower notch surface 18 lowers the molten metal toward the bottom surface of the container. The rear upper notch surface 16 is achieved by a circulating flow that draws the molten metal surface layer downward. It is considered that the rear lower notch surface 19 contributes to further improvement of the stirring ability by eliminating the stagnation that tends to be formed in the circulating flow.

  FIG. 3 shows a simplified configuration of a molten metal stirring device 31 according to another embodiment of the present invention. The molten metal stirring device 31 includes an impeller 1 and a container 33 into which the molten metal 32 is placed so that the axis 3 of the rotating shaft 2 is deviated and decentered with respect to a line 34 that passes through the center of the container 33 and extends in the vertical direction. The impeller 1 and the container 33 are disposed relative to each other. Here, a line 34 that passes through the center of the container 33 and extends in the vertical direction is referred to as a center line 34. Although not shown in FIG. 3, the molten metal stirring device 31 includes a motor for rotating the impeller 1 and a frame for attaching the motor and the impeller 1 around the container 33.

  The container 33 has a cylindrical shape with a bottom and includes an iron outer shell 35 and a refractory 36 lined on the outer shell 35. An example of such a container 33 is a ladle in which molten stainless steel is placed as the molten metal 32.

  When impeller 1 is immersed in molten metal 32 and stirred, it exhibits excellent stirring ability due to its characteristic shape. The molten metal stirring device 31 can exhibit even more excellent stirring ability by decentering the axis 3 of the impeller 1 from the center line 34. The amount of eccentricity between the axis 3 of the impeller 1 and the container center 34 is represented by Ec.

  FIG. 4 shows a simplified state of the flow of the molten metal 32 in the molten metal stirring device 31. FIG. 4A shows a state seen from a cross section, and FIG. 4B shows a state seen from a plane. The flow formed in the molten metal 32 in the container 33 by the rotation of the impeller 1 eccentrically arranged with respect to the center line 34 is indicated by arrows in FIG.

  The flow of the molten metal 32 will be described below. As for the vertical direction, on the side where the distance to the inner wall of the container 33 is narrowed due to eccentricity, the molten metal extruded downward collides with the bottom surface of the container 33 and is reflected and turned upward. It creates a very irregular and complicated flow of being drawn. Further, in the circumferential direction, the molten metal extruded outward in the radial direction by the front outer notch surface 17 on the side where the distance to the inner wall of the container 33 is widened due to eccentricity disturbs the flow in the circumferential direction. Form an irregular flow.

  The impeller 1 that exhibits a strong stirring force is provided, and the axial line 3 and the center line 34 of the impeller 1 are slightly decentered, so that the flow of the molten metal formed by the impeller 1 is prevented without encouraging vibration of the apparatus. Regularity and complexity can be amplified. This makes it possible to provide a molten metal stirring device having a further excellent stirring ability.

  Thus, since the molten metal stirring apparatus 31 has an extremely excellent stirring ability, it is suitable as a desulfurization apparatus for, for example, stainless molten steel that requires a strong stirring force. When the flux is added to the molten stainless steel and stirred by the molten metal stirring device 31, the strong stirring force allows the flux to be strongly wound into the molten stainless steel, and can be repeatedly wound even after floating once, The area of the reaction interface between the molten stainless steel and the flux can be increased.

(Example)
Examples of the present invention will be described below.
FIG. 5 shows a simplified configuration of the test apparatus 41 used for the stirring ability test. The test apparatus 41 is a water model machine 41 simulating a molten metal stirring apparatus equipped with an impeller. As a real machine of the molten metal stirring apparatus provided with the impeller, a mechanical stirring type desulfurization apparatus using a molten steel stainless steel as a molten metal, a desulfurization flux as a flux, and a ladle as a container was assumed. In the water model machine 41, water 42 was used instead of molten stainless steel, silica hollow spheres were used instead of the desulfurized flux, and acrylic resin containers 43 were used instead of the ladle. Hereinafter, the silica-based hollow sphere is referred to as a tracer.

  In this example, the stirring ability was tested with a water model machine 41 of about 1/3 size of the actual machine. In the water model machine 41, the diameter dm of the container 43 is set to 920 mm, the water depth dw in a stationary state is set to 660 mm, and the immersion depth de that is the height from the bottom surface of the impeller when the impeller is immersed is set to 270 mm. .

  The size of the impeller used for the test was also set to about 1/3 of the actual machine. One type of example and three types of comparative examples were used for the impeller. In the example, an impeller 1 having a shape shown in FIG. 1 was used. For the three types of Comparative Examples 1 to 3, impellers 44a, 44b, and 44c that are similar in shape to the example and do not have any notch surface as compared with the example were used. When impellers of Comparative Examples 1 to 3 are collectively referred to by reference numeral 44. The impellers 1 and 44 used in the water model machine 41 are made of steel.

  FIG. 6 shows a simplified configuration of the impeller 44a of the first comparative example. The impeller 44a of Comparative Example 1 has an angle θ between the lower surface 12a and the rear surface 14a set to 85 degrees, but does not have a notch surface.

  FIG. 7 shows a simplified configuration of the impeller 44b of the second comparative example. The impeller 44b of Comparative Example 2 has a front lower notch surface 18b and a rear lower notch surface 19b, and the angle θ formed between the lower surface 12b and the rear surface 14b is set to 85 degrees. Does not have an upper cutaway surface.

  FIG. 8 shows a simplified configuration of the impeller 44c of the third comparative example. The impeller 44c of Comparative Example 3 has a front outer notch surface 17c, a front lower notch surface 18c, and a rear lower notch surface 19c, and an angle θ formed between the lower surface 12c and the rear surface 14c is set to 85 degrees. It does not have a rear upper notch.

FIG. 9 shows the dimension measurement position of each part regarding the shape of the impellers 1 and 44 used in the water model machine 41. The dimension measurement position will be described below, and the actual measurement values are shown in Table 1.
A: Impeller diameter at the upper end of the stirring blade in the direction in which the stirring blade protrudes B: Impeller diameter at the lower end of the stirring blade in the direction in which the stirring blade protrudes C: Thickness in the rotation direction of the stirring blade D: During impeller rotation H: Width that is the length of the stirring blade in the vertical direction θ: Angle formed between the lower surface and the rear surface

  Considering the similarity law with the assumed actual machine, the fluid number and the stirring power of the unit capacity are the same, and the number of rotations of the impellers 1 and 44 of the water model machine 41 and the size of the tracer are calculated by the equations (1) and (2). The bulk and bulk specific gravity were determined.

N ₂ = N ₁ (D ₂ / D ₁ ) ^2/3 (1)
Where N _{1 is} the speed of the impeller of the actual machine
N ₂ : Speed of impeller of water model machine
D ₁ : Maximum outer diameter during impeller rotation of actual machine
D ₂ : Maximum outer diameter of the water model machine when the impeller rotates

r ₂ / r ₁ = (N ₂ D ₂ / N ₁ D ₁ )
× √ {(1-ρ _s1 / ρ _l1 ) / (1-ρ _s2 / ρ _l2 )} (2)
Where r _{1 is} the diameter of the flux
r ₂ : Diameter of the tracer
ρ _s1 : Flux bulk specific gravity
_ρs2 : Bulk specific gravity of the tracer
ρ ₁₁ : Specific gravity of molten stainless steel
ρ _l2 : Specific gravity of water

  In addition, since the average particle diameter of 120 μm and the bulk specific gravity of 0.29 were obtained from the formula (2), the tracer was subjected to a preliminary test for stirring, but the time for the tracer to disperse in water by stirring was extremely short. The behavior could not be observed sufficiently. Therefore, the test was performed by changing to a tracer having an average particle size of 10 mm suitable for observation and a bulk specific gravity of about 0.8.

  Regarding the rotation of the impellers 1, 44, the case where there was no eccentricity in which the center line 34 of the container 33 and the axis 3 of the impellers 1, 44 coincided and the case where they were shifted eccentrically were tested. The amount of eccentricity Ec was changed in three stages of 25 mm, 50 mm and 75 mm.

  Returning to FIG. 5, a method for evaluating the stirring ability will be described. There are three evaluation elements in the state where the impellers 1 and 44 are rotating and agitating: a water surface rising height hi, a vortex center position depth hw, and a tracer penetration depth he. The water surface rising height hi refers to the height from the bottom surface of the container where the water surface becomes the highest when the impeller 1, 44 rotates and the water surface in the container 43 becomes higher than the static water surface. The vortex center position depth hw means that when the impeller 1, 44 rotates to form a vortex and the water surface is lower than the stationary water surface at the center of the vortex, the water surface is at the lowest position from the bottom of the container. Say height. The tracer penetration depth he refers to the height from the bottom of the container at the deepest position where the tracer caught in water can reach in the container 43.

  Both the water surface rising height hi and the vortex center position depth hw are indicators of the strength of the flow, but do not necessarily represent a state where water and the tracer are stirred and mixed. The tracer penetration depth he can be said to represent the time during which the tracer stays in the water because it takes time to rise as the depth of penetration of the tracer increases. If the tracer stays in the water for a long time, the amount of the tracer that can exist in the water at the same time increases, so it can be understood that the area of the contact interface between water and the tracer, that is, the reaction interface is large. Therefore, the stirring ability was evaluated by the tracer penetration depth he. It was determined that the smaller the tracer penetration depth he is, that is, the better the stirring ability is as the tracer penetrates to a deeper position.

Hereinafter, the test results will be described.
FIG. 10 shows the relationship between the rotational speed and the tracer penetration depth for Comparative Example 1 and Comparative Example 2 without eccentricity. FIG. 11 shows the relationship between the rotational speed and the tracer penetration depth for Comparative Example 3 and Example in the case of no eccentricity.

  In any of Examples and Comparative Examples 1 to 3, the tracer penetration depth he decreased as the rotational speed increased. In the case of the rotational speed of 100 rpm, the tracer penetration depth he reached to less than 50 mm in Example, Comparative Example 2 and Comparative Example 3, whereas in Comparative Example 1, the tracer penetration depth he reached only 450 mm. I could not.

  When the rotational speed is 150 rpm or more, the tracer penetration depth he is 0 mm in Example, Comparative Example 2 and Comparative Example 3, that is, the tracer reaches the bottom of the container, whereas in Comparative Example 1, the tracer penetration depth he is It could only reach up to about 180 mm. From this, it can be seen that the example having the notched surface and the comparative examples 2 and 3 have better stirring ability than the comparative example 1 having no notched surface.

  Furthermore, in the case of the low-speed rotation with the rotation speed of 50 rpm, the tracer penetration depth he reached less than 600 mm only in the examples, but in Comparative Examples 1 to 3, the tracer penetration depth he exceeded 600 mm. Thus, the embodiment having the front outer notch surface, the front lower notch surface, the rear upper notch surface, and the rear lower notch surface is the comparative example 2 and the rear portion having no front outer notch surface and rear upper notch surface. It can be seen that the stirring ability is higher than that of Comparative Example 3 which does not have an upper notch surface.

  Next, the test results when the axis 3 and the center line 34 of the impellers 1 and 44 have an eccentric amount Ec will be described. The test with eccentricity was performed on the impellers of Examples and Comparative Examples 2 and 3 in which the effect of the notched surface was recognized when there was no eccentricity. FIG. 12 shows the relationship between the rotational speed and the tracer penetration depth for Comparative Example 2, Comparative Example 3, and Example when the eccentricity Ec is 25 mm. FIG. 13 shows the relationship between the rotational speed and the tracer penetration depth for Comparative Example 2, Comparative Example 3, and Example when the eccentricity Ec is 50 mm. FIG. 14 shows the relationship between the rotational speed and the tracer penetration depth for Comparative Example 2, Comparative Example 3, and Example when the eccentricity Ec is 75 mm.

  When the amount of eccentricity Ec was as large as 75 mm, when the rotational speed was 100 rpm or more, the tracer reached the bottom of the container in any of Example, Comparative Example 2 and Comparative Example 3, and no difference occurred. Even at a low rotation speed of 50 rpm, the tracer penetration depth he of Example and Comparative Example 2 was 100 mm, and the tracer penetration depth he of Comparative Example 3 was 150 mm, and there was no significant difference between the three.

  However, when the eccentric amount Ec was made smaller than 75 mm, the tracer penetration depth he was different between the example, the comparative example 2 and the comparative example 3. In particular, when the eccentricity Ec is small 25 mm, the tracer penetration depth he of the example can reach 150 mm at a low speed rotation of 50 rpm, whereas the comparative example 2 is 300 mm and the comparative example 3 is 350 mm. Only reached.

  When the eccentric amount Ec is increased, the tracer penetration depth he is reduced in the comparative example 2 and the comparative example 3 and the stirring ability is improved, but there is a concern about vibration of the apparatus. However, by using the impeller of the embodiment that has a notch surface and can exhibit high stirring ability, and setting it to a small amount of eccentricity, there is no problem of vibration and a molten metal stirring apparatus having excellent stirring ability Can be realized.

It is a figure which shows the structure of the impeller 1 for molten metal stirring which is one Embodiment of this invention. It is a figure which shows the state of the flow of the molten metal formed with the stirring blade. It is sectional drawing which simplifies and shows the structure of the molten metal stirring apparatus 31 which is other embodiment of this invention. It is a figure which simplifies and shows the state of the flow of the molten metal 32 in the molten metal stirring apparatus 31. It is sectional drawing which simplifies and shows the structure of the test apparatus 41 used for the test of stirring ability. It is a figure which simplifies and shows the structure of the impeller 44a of the comparative example 1. It is a figure which simplifies and shows the structure of the impeller 44b of the comparative example 2. It is a figure which simplifies and shows the structure of the impeller 44c of the comparative example 3. It is a figure which shows the dimension measurement position of each part regarding the shape of the impellers and 44 used for the water model machine. It is a graph which shows the relationship between a rotation speed and a tracer penetration | invasion depth about the comparative example 1 and the comparative example 2 in the case of no eccentricity. It is a graph which shows the relationship between a rotation speed and a tracer penetration | invasion depth about the comparative example 3 and Example in the case of no eccentricity. It is a graph which shows the relationship between a rotation speed and tracer penetration | invasion depth about the comparative example 2, the comparative example 3, and Example in case eccentricity Ec is 25 mm. It is a graph which shows the relationship between a rotation speed and a tracer penetration | invasion depth about the comparative example 2, comparative example 3, and Example in case eccentricity Ec is 50 mm. It is a graph which shows the relationship between a rotation speed and tracer penetration | invasion depth about the comparative example 2, the comparative example 3, and Example in case eccentricity Ec is 75 mm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,44 Impeller 2 Rotating shaft 3 Axis 5 Stirring blade 11 Upper surface 12 Lower surface 13 Front surface 14 Rear surface 15 Outer surface 16 Rear upper notch surface 17 Front outer notch surface 18 Front lower notch surface 19 Rear lower notch surface 31 Molten metal stirring device 32 Molten metal 33 Container 34 Center line 41 Water model machine

Claims (5)

In a molten metal stirring impeller that stirs molten metal with a plurality of stirring blades that are immersed in the molten metal in the container from above and rotate to protrude radially from the vicinity of the lower end of the rotating shaft.
The stirring blade
Each is roughly formed in a prismatic shape having an upper surface, a lower surface, a front surface, a rear surface and an outer surface, the front surface is the front side in the rotational direction, the rear surface is the rear side in the rotational direction, and the outer surface is the outer side in the radial direction,
Furthermore, a rear upper notch surface that is an inclined surface with a corner notched from the upper surface to the rear surface;
A front outer cut-out surface that is an inclined surface with a corner cut from the front surface to the outer surface;
A front lower cut surface that is an inclined surface with a corner cut from the bottom surface to the front surface;
An impeller for stirring a molten metal, comprising: The front outer cut-out surface is
The impeller for stirring molten metal according to claim 1, wherein the impeller is stirred so as to incline downward toward the rear in the rotational direction. The stirring blade is
3. The impeller for stirring a molten metal according to claim 1, further comprising a rear lower notch surface which is an inclined surface with a corner portion notched from the lower surface to the rear surface. The stirring blade is
The impeller for molten metal stirring according to any one of claims 1 to 3, wherein an angle formed by the rear surface with respect to the lower surface is less than 90 degrees. An impeller for stirring molten metal according to any one of claims 1 to 4,
A container for containing molten metal,
An apparatus for stirring molten metal, wherein an impeller for stirring a molten metal is disposed so that an axis of a rotating shaft is deviated from a center line of a container.

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