molten metal pump

Abstract

To provide a molten metal pump capable of renewing a molten metal flow channel easily at low cost.SOLUTION: A molten metal pump 1 includes a bottomed tubular body 10 having a side wall 11 and a bottom wall 12, a molten metal flow channel body 20 having a molten metal flow channel C connecting an inlet P1 and an outlet P2, the molten metal flow channel body being separated from the bottomed tubular body, and a molten metal driving part 30 having a magnetic field device 31 and an electric motor 32 to drive molten metal in the molten metal flow channel C. The magnetic field device 31 has plural permanent magnets 31a disposed in such a manner that alternately differing magnetic poles stand in line along a circumference of a revolving shaft 33. The molten metal flow channel body 20 is detachably provided on the bottomed tubular body 10 at a position around the side wall 11 where magnetic fluxes ML from a first permanent magnet in the plural permanent magnets 31a penetrate the side wall 11 and an inner flow channel wall 21 to reach to the molten metal flow channel C and then penetrate the inner flow channel wall 21 and the side wall 11 from the molten metal flow channel C to return to a second permanent magnet next to the first permanent magnet.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a molten metal pump, and more particularly to a molten metal pump that circulates or transports molten metal in a furnace. [Background technology]

[0002] Conventionally, there is known a molten metal pump that drives a molten non-ferrous metal (hereinafter simply referred to as "molten metal") by electromagnetic force. For example, Patent Document 1 describes a molten metal pump that drives the molten metal by utilizing electromagnetic force generated by magnetic lines of force emitted from a permanent magnet that move while penetrating the molten metal. In this molten metal pump, a permanent magnet is rotatably disposed inside a cylindrical container, and a spiral molten metal flow path is provided inside the side wall of the cylindrical container. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5546974 Summary of the Invention [Problem to be solved by the invention]

[0004] The molten metal pump of Patent Document 1 was invented by the present inventor, but the present inventor has since been working on research and development to realize a more practical and high-performance molten metal pump. In the course of his research, he has independently discovered the following problems.

[0005] When the use of a molten metal pump is suspended, the molten metal gradually solidifies in the flow passage, narrowing the cross-sectional area of ​​the molten metal flow passage. As a result, the discharge volume (discharge pressure) of the molten metal pump decreases, and in the worst case, the molten metal pump becomes unusable. Conversely, when a molten metal pump is in use, the molten metal flowing through the molten metal flow passage can wear down the molten metal flow passage. In any case, wear on the molten metal flow passage is unavoidable as the molten metal pump is used.

[0006] If one were to renew the molten metal flow passage in order to maintain the performance of the molten metal pump, in the case of the above-mentioned molten metal pump, since the molten metal flow passage is formed in a cylindrical container, it would be necessary to replace the cylindrical container that constitutes the main body with a new one, which would entail a great deal of cost (money and time).

[0007] Furthermore, while it is desirable to increase the discharge volume of molten metal pumps, in the case of conventional molten metal pumps, increasing the cross-sectional area of ​​the molten metal flow path results in an increase in the weight of the cylindrical vessel due to the thickening of the side walls, which makes it difficult to install the molten metal pump inside the furnace, and other problems arise regarding ease of handling.

[0008] The present invention has been made based on the above recognition, and an object of the present invention is to provide a molten metal pump which allows the molten metal flow path to be renewed easily and at low cost. [Means for solving the problem]

[0009] The molten metal pump according to the present invention comprises: A molten metal pump for driving molten metal in a furnace, A bottomed cylinder having a side wall and a bottom wall; a molten metal flow passage body having a molten metal flow passage connecting a suction port and a discharge port and being separate from the bottomed cylinder body; a molten metal driving unit including a magnetic field device rotatably disposed inside the bottomed cylinder around a vertical rotation axis and an electric motor for rotating the magnetic field device, the molten metal driving unit driving the molten metal in the molten metal flow path; Equipped with The magnetic field device includes a plurality of permanent magnets arranged such that alternating magnetic poles are aligned along the circumference of the rotation shaft; The molten metal flow path body is removably mounted on the bottomed cylinder at a position around the side wall of the bottomed cylinder, where magnetic field lines from a first permanent magnet among the multiple permanent magnets pass through the side wall of the bottomed cylinder and the inner flow path wall of the molten metal flow path body to reach the molten metal flow path, and then pass from the molten metal flow path through the inner flow path wall of the molten metal flow path body and the side wall of the bottomed cylinder to return to a second permanent magnet adjacent to the first permanent magnet.

[0010] In the molten metal pump, The molten metal flow passage may have a vertical cross-sectional shape that is substantially rectangular.

[0011] In the molten metal pump, The plurality of permanent magnets of the magnetic field device may have a vertical length greater than that of the molten metal flow path and may encompass the molten metal flow path in the vertical direction when viewed from the side.

[0012] In the molten metal pump, The molten metal flow path body may be provided so as to surround the side wall of the bottomed cylinder.

[0013] In the molten metal pump, The molten metal flow path body may have a substantially U-shaped planar shape.

[0014] In the molten metal pump, The melt drive may further include a thermal insulation hood configured to cover the magnetic field device and the electric motor of the molten metal drive and to define a cooling air flow path for cooling air to flow through the magnetic field device and the electric motor.

[0015] In the molten metal pump, The insulating hood is a fixed hood that is fixed to a base plate that defines, together with the bottomed cylinder, a space for accommodating the magnetic field device, covers the motor, and is provided with an air intake for taking in cooling air; a movable hood that is attached to the magnetic field device so as to define the cooling air flow path together with the fixed hood and cover an outer circumferential surface of the magnetic field device and rotate together with the magnetic field device; may have the following structure:

[0016] In the molten metal pump, The fixed hood includes: an upper fixed hood having a lower end portion fixed to an upper surface of the base plate; a lower fixed hood having an upper end portion fixed to a lower surface of the base plate; may have the following structure:

[0017] In the molten metal pump, The fixed hood and the movable hood may be lined with a thermal insulating material.

[0018] In the molten metal pump, The fixed hood and the movable hood may be made of a metallic material.

[0019] In the molten metal pump, The lower end of the fixed hood may be loosely inserted into the upper end of the movable hood, or the upper end of the movable hood may be loosely inserted into the lower end of the fixed hood.

[0020] In the molten metal pump, The base plate is provided with a first air hole located inside the fixed hood and a second air hole located outside the fixed hood, The cooling air taken in through the air intake of the fixed hood may flow downward through the cooling air flow path through the first air hole, pass through the magnetic field device and be released from the lower end of the movable hood, and then be discharged to the outside through the second air hole through the space between the side wall of the bottomed cylinder and the insulating hood.

[0021] In the molten metal pump, The bottomed cylinder may have a support portion protruding radially outward from the side wall, and the molten metal flow path body may be detachably supported by the bottomed cylinder by the support portion.

[0022] In the molten metal pump, The electric motor may be configured to vary the rotation speed of the magnetic field device in accordance with the discharge rate of the molten metal.

[0023] In the molten metal pump, The melting machine may further include a molten metal discharge pipe connected to the discharge port of the molten metal flow path for pumping up the molten metal. Effect of the Invention

[0024] According to the present invention, it is possible to provide a molten metal pump that enables the molten metal flow path to be replaced easily and at low cost. [Brief description of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a molten metal pump according to an embodiment. [Diagram 2] 1 is a plan view showing a schematic configuration of a molten metal pump according to an embodiment; [Diagram 3] FIG. 2 is a plan view showing the molten metal pump according to the embodiment with the molten metal flow path body removed. [Figure 4] FIG. 2 is a plan view showing a molten metal flow path body of the molten metal pump according to the embodiment. [Diagram 5] FIG. 1 is a plan view showing a magnetic field device according to an embodiment. [Figure 6] FIG. 13 is a plan view showing a magnetic field device according to a modified example of the embodiment. [Figure 7] FIG. 2 is a cross-sectional view of the molten metal pump according to the embodiment in a state where it is immersed in molten metal in a furnace. [Figure 8] FIG. 2 is a plan view of the molten metal pump according to the embodiment in a state where it is immersed in the molten metal in a furnace. [Figure 9]FIG. 2 is a side view showing a molten metal pump according to an embodiment, in which a molten metal discharge pipe is attached to the discharge port of a molten metal flow passage body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, components having equivalent functions are denoted by the same reference numerals.

[0027] <Molten metal pump> The configuration of a molten metal pump 1 according to an embodiment will be described with reference to Figures 1 to 5. Figure 1 is a cross-sectional view taken along line AA in Figure 2, and shows a schematic configuration of the molten metal pump 1.

[0028] The molten metal pump 1 of this embodiment is configured such that a portion of it (at least the molten metal flow path body 20) is immersed in the molten metal in a furnace such as a melting furnace or a holding furnace, and drives the molten metal by utilizing electromagnetic force generated by eddy currents, as described below.

[0029] As shown in Figure 1, the molten metal pump 1 comprises a bottomed cylindrical body (main body) 10, a molten metal flow path body 20 in which a molten metal flow path C is provided through which molten metal flows, a molten metal driving unit 30 that drives the molten metal in the molten metal flow path C, an insulating hood 40 that thermally protects the molten metal driving unit 30, and a base plate 50 that divides the internal space of the bottomed cylindrical body 10 and supports the molten metal driving unit 30.

[0030] Each component of the molten metal pump 1 will be described in detail below.

[0031] The bottomed cylinder 10 is a bottomed cylinder having a side wall 11 and a bottom wall 12. The side wall 11 is configured in a cylindrical shape. The bottom wall 12 closes the lower end of the side wall 11. In this embodiment, as shown in Figures 1 and 3, the bottomed cylinder 10 has a support portion (flange portion) 13 that protrudes radially outward from the side wall 11. The support portion 13 supports the molten metal flow path body 20 in a detachable manner on the bottomed cylinder 10.

[0032] The bottomed cylinder 10 is made of a non-magnetic and fire-resistant material.

[0033] It is preferable that the bottomed cylindrical body 10 is formed integrally with the side wall 11 and the bottom wall 12. In this case, the bottomed cylindrical body 10 is manufactured integrally by pouring mortar or the like into a formwork.

[0034] The molten metal flow path body 20 is provided around the side wall 11 of the bottomed cylinder 10 as a separate body from the bottomed cylinder 10. The molten metal flow path body 20 is immersed in the molten metal in the furnace when the molten metal pump 1 is in use, and the molten metal flow path C is filled with the molten metal (see FIG. 7). The molten metal flow path body 20 is made of a non-magnetic and fire-resistant material, for example, the same material as the bottomed cylinder 10.

[0035] Inside the molten metal flow passage body 20, a molten metal flow passage C is provided that connects the suction port P1 and the discharge port P2. The molten metal flow passage C in this embodiment is formed to have a closed vertical cross section. In detail, as shown in FIG. 1, the molten metal flow passage body 20 has an inner flow passage wall 21, an outer flow passage wall 22, an upper flow passage wall 23, and a lower flow passage wall 24, and these flow passage walls form the molten metal flow passage C having a substantially rectangular vertical cross section. Since the molten metal flow passage C does not open upward, the discharge pressure of the molten metal can be easily increased. It is preferable that the molten metal flow passage body 20 is formed by integrally molding the inner flow passage wall 21, the outer flow passage wall 22, the upper flow passage wall 23, and the lower flow passage wall 24.

[0036] Preferably, the vertical cross-sectional shape of the molten metal flow path C is a vertically long, substantially rectangular shape. As a result, under the condition that the cross-sectional area of ​​the flow path is constant, the radial length of the molten metal flow path C becomes relatively short, so that the magnetic field device 31's magnetic field lines can easily penetrate the molten metal in the molten metal flow path C, thereby improving the driving force of the molten metal.

[0037] 1, the vertical length (L1) of the multiple permanent magnets 31a of the magnetic field device 31 may be greater than the vertical length (L2) of the molten metal flow path C (i.e., L1>L2), and may encompass the molten metal flow path C in the vertical direction when viewed from the side. This makes the magnetic field lines of the magnetic field device 31 approximately parallel to each other in the molten metal flow path C. As a result, it becomes easier to control the driving force of the molten metal pump, and the discharge rate of the molten metal can be easily adjusted.

[0038] The vertical cross-sectional shape of the molten metal flow path C is not limited to a rectangle, and may be a circle, an ellipse, a polygon, or the like. When a high discharge pressure is not required, the molten metal flow path C may be open at the top by eliminating the upper flow path wall 23. In this case, the surface of the molten metal in the furnace needs to be lower than the upper end of the outer flow path wall 22.

[0039] As shown in FIG. 2, in order to facilitate the sucking of the molten metal, the vicinity of the inlet of the molten metal flow path C may be formed in a tapered shape so that the suction port P1 is wider than the discharge port P2.

[0040] Furthermore, the width of the molten metal flow path C may be greater than the thickness of the side wall 11 of the bottomed cylinder 10. This increases the cross-sectional area of ​​the flow path compared to the conventional case where a flow path is provided on the side wall, and allows the discharge amount to be increased.

[0041] In this embodiment, as shown in Fig. 2, the molten metal flow path body 20 has a substantially U-shaped planar shape. By arranging the molten metal flow path C so as to surround the side wall 11 in this manner, the molten metal in the molten metal flow path C can be driven efficiently. However, the planar shape of the molten metal flow path body 20 is not limited to a U-shape and may be, for example, a substantially C-shape or a substantially L-shape. Furthermore, the molten metal flow path body 20 may have a spiral molten metal flow path C.

[0042] The molten metal flow path body 20 is detachably provided on the bottomed cylinder 10, as shown in Figures 3 and 4. Figure 3 shows a plan view of the main body of the molten metal pump 1 with the molten metal flow path body 20 removed, and Figure 4 shows a plan view of the molten metal flow path body 20 removed from the molten metal pump 1.

[0043] The molten metal flow path body 20 is removably mounted on the bottomed cylindrical body 10 at a position around the side wall 11 of the bottomed cylindrical body 10, where magnetic field lines from a first permanent magnet of the multiple permanent magnets 31a of the magnetic field device 31 penetrate the side wall 11 and the inner flow path wall 21 of the molten metal flow path body 20 to reach the molten metal flow path C, and then penetrate from the molten metal flow path C through the inner flow path wall 21 and the side wall 11 to return to a second permanent magnet adjacent to the first permanent magnet.

[0044] The connection between the bottomed cylinder 10 and the molten metal flow path body 20 is not limited to the connection by the support portion 13 of the bottomed cylinder 10. As another example, a convex portion (or a concave portion) may be provided on the side wall 11 of the bottomed cylinder 10, a concave portion (or a convex portion) may be provided on the inner flow path wall 21 of the molten metal flow path body 20, and the convex portion of the side wall 11 may be fitted into the concave portion of the inner flow path wall 21, thereby detachably connecting the molten metal flow path body 20 to the bottomed cylinder 10. As yet another example, fixing holes (not shown) may be formed in the side wall 11 and the outer flow path wall 22, respectively, and the molten metal flow path body 20 may be detachably connected to the bottomed cylinder 10 by inserting ends of connecting members (for example, U-shaped connecting members) into the respective holes.

[0045] Furthermore, a plurality of molten metal flow passage structures 20 each having a different flow passage cross-sectional area (height, etc.) of the molten metal flow passage C may be prepared and used according to the desired discharge amount, etc.

[0046] 1, the inner flow path wall 21 of the molten metal flow path body 20 is in contact with the side wall 11 of the bottomed cylinder 10 with no gap. This shortens the distance between the molten metal flow path C and the magnetic field device 31, and strengthens the magnetic field penetrating the molten metal in the molten metal flow path C, thereby increasing the driving force of the molten metal. However, the present invention is not limited to this, and a gap may be provided between the side wall 11 and the inner flow path wall 21.

[0047] Next, the molten metal driving unit 30 will be described.

[0048] The molten metal driving unit 30 is configured to use electromagnetic force to drive the molten metal in the molten metal flow path C formed in the molten metal flow path body 20. The molten metal driving unit 30 drives the molten metal in the molten metal flow path C from the suction port P1 toward the discharge port P2, thereby discharging the molten metal from the discharge port P2 and sucking the molten metal in the furnace into the molten metal flow path C from the suction port P1.

[0049] The molten metal driving section 30 has a magnetic field device (rotating magnet body) 31, an electric motor 32 for rotating the magnetic field device 31, a rotating shaft 33 connected to the magnetic field device 31, a coupling 34, a stand 35, and a bearing housing 36.

[0050] As shown in Fig. 1, the magnetic field device 31 is disposed inside the bottomed cylinder 10 so as to be rotatable around a vertical rotation shaft 33. As shown in Figs. 1 and 5, the magnetic field device 31 has a plurality of permanent magnets (magnet pieces) 31a and support plates 31b and 31c that support the plurality of permanent magnets 31a. Note that the support plate 31c is not shown in Fig. 5 (the same applies to Fig. 6). In this embodiment, four permanent magnets 31a are fixed on the support plate 31b. The support plates 31b and 31c fix the plurality of permanent magnets 31a by sandwiching them from above and below.

[0051] Each permanent magnet 31a has an outer surface magnetic pole and an inner surface magnetic pole that are magnetized so that the outer peripheral portion and the inner peripheral portion become magnetic poles, and the magnetic field device 31 is positioned within the bottomed cylindrical body 10 so that the outer surface magnetic pole faces the side wall 11 of the bottomed cylindrical body 10.

[0052] As shown in Fig. 5, the multiple permanent magnets 31a are arranged on the circumference of the rotating shaft 33. More specifically, the multiple permanent magnets 31a are arranged so that the outer surface magnetic poles that are different from each other are lined up along the circumference of the rotating shaft 33. As a result, the magnetic field lines ML emanating from the N pole of a certain permanent magnet 31a (first permanent magnet) enter the S pole of the permanent magnet 31a (second permanent magnet) adjacent to that permanent magnet. Note that in order to form such magnetic field lines ML for all the permanent magnets 31a, it is preferable that the number of permanent magnets 31a is an even number.

[0053] As shown in Fig. 5, the support plate 31b is provided with an air hole H5 so that the cooling air introduced into the insulating hood 40 flows around the multiple permanent magnets 31a. The shape of the support plate 31b is not limited to that shown in Fig. 5 and may be, for example, substantially cross-shaped. The support plate 31c may have the same shape as the support plate 31b.

[0054] Either the support plate 31b or the support plate 31c may be omitted from the magnetic field device 31. When the support plate 31b is omitted, the multiple permanent magnets 31a are supported (suspended) by the support plate 31c.

[0055] 6 is a plan view of a magnetic field device 31A according to a modified example. In this magnetic field device 31A, the support plate 31b is rod-shaped, and permanent magnets 31a are fixed to both ends of the support plate 31b. In this modified example, the two permanent magnets 31a are also arranged so that the magnetic poles of the two permanent magnets 31a are arranged alternately along the circumference of the rotating shaft 33.

[0056] In addition to the above, magnetic field devices having six permanent magnets 31a, eight permanent magnets 31a, ... are also envisioned. In general, the fewer the number of permanent magnets in the magnetic field device, the more advantageous it is that the magnetic field lines ML reach farther. On the other hand, when the rotation speed of the magnetic field device 31 is the same, the more permanent magnets 31a in the magnetic field device are, the greater the change in the magnetic field lines over time in the molten metal, and the greater the driving force for the molten metal can be.

[0057] 1, the electric motor 32 has a rotating shaft 32a and is installed on a stand 35 so that the rotating shaft 32a is vertical. The rotating shaft 32a is connected to a rotating shaft 33 via a coupling 34. The magnetic field device 31 rotates around the rotating shaft 33 as the rotating shaft 32a rotates.

[0058] As shown in FIG. 1, the electric motor 32 is electrically connected to a power supply control panel 60 via a connecting conductor 61. For example, the electric motor 32 is a DC motor, and is connected to a positive terminal 60a and a negative terminal 60b of the power supply control panel 60. The rotation speed of the electric motor 32 (i.e., the rotation speed of the magnetic field device 31) can be controlled by adjusting the output (voltage, current, etc.) of the power supply control panel 60. The amount of molten metal discharged from the discharge port P2 of the molten metal flow path body 20 can be increased by increasing the rotation speed of the electric motor 32. In this way, the electric motor 32 is configured to change the rotation speed of the magnetic field device 31 according to the amount of molten metal discharged.

[0059] The type of the electric motor 32 is not particularly limited, and may be an AC motor, etc. In the case of an AC motor, the rotation speed of the electric motor 32 may be controlled by an inverter (not shown) of the power supply control panel 60.

[0060] 1, the rotating shaft 33 is inserted through the bearing housing 36 and the base plate 50 (shaft insertion hole H4), and connects the magnetic field device 31 and the electric motor 32. The lower end of the rotating shaft 33 is fixed to the magnetic field device 31 (support plate 31b), and the upper end of the rotating shaft 33 is connected to the rotating shaft 32a of the electric motor 32 via a coupling 34.

[0061] The base plate 50 is a plate-like member provided to divide the internal space of the bottomed cylinder 10. The base plate 50 and the bottomed cylinder 10 define a space for accommodating the magnetic field device 31. The base plate 50 is provided with air holes H2, H3 and a shaft insertion hole H4. More specifically, as shown in FIG. 1, the base plate 50 is provided with an air hole H2 located on the outside of the fixed hood 41, and an air hole H3 and a shaft insertion hole H4 located on the inside of the fixed hood 41. The base plate 50 may be a cover plate that closes the upper end of the bottomed cylinder 10.

[0062] The coupling 34 is a shaft joint member that joins the rotating shaft 32 a of the electric motor 32 and the rotating shaft 33 fixed to the magnetic field device 31 .

[0063] The stand 35 is fixed onto the base plate 50. The electric motor 32 is installed on the stand 35. The upper surface of the stand 35 is configured to allow cooling air to pass through. For example, the upper surface of the stand 35 is formed in a mesh or lattice shape. Note that in cases where the rotating shaft 32a and the rotating shaft 33 are integrally configured, the stand 35 may be omitted and the electric motor 32 may be installed directly on the base plate 50.

[0064] The bearing housing 36 accommodates a bearing (not shown) and is fixed to the lower surface of a base plate 50 as shown in FIG.

[0065] Next, the insulating hood 40 will be described.

[0066] The insulating hood 40 is provided to protect the molten metal driving part 30 (particularly the magnetic field device 31) from the heat of the molten metal in the furnace. As shown in Fig. 1, the insulating hood 40 is configured to cover the magnetic field device 31 and the electric motor 32 of the molten metal driving part 30 and to define a cooling air flow path S through which cooling air introduced from the outside flows through the magnetic field device 31 and the electric motor 32.

[0067] In this embodiment, the insulating hood 40 has a fixed hood 41 fixed to the base plate 50 and a movable hood 42 that rotates together with the magnetic field device 31.

[0068] The fixed hood 41 covers the electric motor 32 and is provided with an air intake H1 for taking in cooling air from the outside. In this embodiment, the air intake H1 is provided on the upper surface of the upper fixed hood 41a. A blower (not shown) may be connected to the air intake H1.

[0069] The movable hood 42 is attached to the magnetic field device 31 so as to define the cooling air flow path S together with the fixed hood 41 and to cover the outer circumferential surface of the magnetic field device 31. In this embodiment, as shown in FIG. 1, the inner diameter of the upper end of the movable hood 42 is adjusted to be slightly larger than the outer diameter of the fixed hood 41 (lower fixed hood 41b), and the lower end of the fixed hood 41 (lower fixed hood 41b) is loosely inserted into the upper end of the movable hood 42. A small gap is provided between the fixed hood 41 and the movable hood 42, which allows the movable hood 42 to rotate while suppressing leakage of cooling air. The upper end of the movable hood 42 may be loosely inserted into the lower end of the fixed hood 41 (lower fixed hood 41b).

[0070] The insulating hood 40 (fixed hood 41 and movable hood 42) is preferably made of a material that satisfies the required mechanical strength and heat resistance even if the thickness is relatively thin, for example, made of a metal material such as stainless steel. Even if the movable hood 42 is made of a metal material, the movable hood 42 rotates together with the magnetic field device 31, so no eddy current is generated in the movable hood 42. Therefore, by adopting the configuration of the movable hood 42, the rotation speed of the electric motor 32 can be significantly increased (for example, up to 500 to 750 revolutions per minute) compared to the case where the magnetic field device 31 is covered with the fixed hood 41. As a result, the driving force of the molten metal can be significantly improved.

[0071] In order to improve the heat insulating effect, it is preferable that fixed hood 41 and movable hood 42 are covered with a heat insulating material.

[0072] The fixed hood 41 of the present embodiment has an upper fixed hood 41a and a lower fixed hood 41b.

[0073] The upper fixed hood 41a is a cylinder whose lower end is fixed to the upper surface of the base plate 50. As shown in FIG. 1, the upper fixed hood 41a of this embodiment has a closed upper end and an air intake H1 is provided on the upper surface. The air intake H1 may be provided on a side surface of the upper fixed hood 41a. The upper fixed hood 41a may also be a cylinder whose upper end is open. The shape of the upper fixed hood 41a is not limited to a cylindrical shape, and may be a dome shape, etc.

[0074] The lower fixed hood 41b is a cylinder having an upper end portion fixed to the lower surface of the base plate 50. In this embodiment, the lower fixed hood 41b has open upper and lower ends, and the upper end portion is fixed to the lower surface of the base plate 50.

[0075] The fixed hood 41 may be configured as an integrated unit, rather than as separate units such as the upper fixed hood 41a and the lower fixed hood 41b. In this case, for example, the fixed hood 41 is fixed to the base plate 50 in a state in which it penetrates the base plate 50.

[0076] <Motion of molten metal pump 1> Next, the operation of the molten metal pump 1 according to the above-described embodiment will be described.

[0077] As shown in Fig. 7, the molten metal pump 1 is submerged in the molten metal M in the furnace 100. The furnace 100 is, for example, a melting furnace for melting a non-ferrous metal such as aluminum, or a holding furnace for holding the molten metal. The non-ferrous metal may be, for example, Al, Cu, Zn, or an alloy of at least two of these metals, or an Mg alloy.

[0078] In order to reduce thermal shock, it is preferable to preheat the bottomed cylinder 10 and the molten metal flow path body 20 before installing the molten metal pump 1 in the furnace 100. The preheating process is performed, for example, by blowing hot air through the air intake H1.

[0079] After that, the power supply control panel 60 is operated to drive the electric motor 32 at a rotation speed according to the desired discharge amount. As the magnetic field device 31 rotates, the magnetic field lines ML that emerge from one permanent magnet 31a and enter the adjacent permanent magnet 31a move while penetrating the molten metal M' in the molten metal flow path C. The movement of the magnetic field lines ML generates an eddy current in the molten metal M'. The molten metal M' in the molten metal flow path C is driven in the circumferential direction of the rotating shaft 33 by the electromagnetic force acting on the molten metal M' due to the eddy current, as shown in FIG. 8. As a result, the molten metal M' in the molten metal flow path C is discharged from the discharge port P2, and the molten metal M in the external furnace 100 is sucked into the molten metal flow path C from the suction port P1. As a result, the molten metal in the furnace 100 circulates.

[0080] During operation of the molten metal pump 1, cooling air A is blown into the heat-insulating hood 40 through the air inlet H1 to cool the magnetic field device 31 and the electric motor 32. As shown in Fig. 7, the cooling air taken in from the air inlet H1 of the fixed hood 41 cools the electric motor 32, then flows downward through the cooling air passage S through the air hole H3, passes through the magnetic field device 31 and is discharged from the lower end of the movable hood 42, and then passes through the space (cooling air passage T) between the side wall 11 of the bottomed cylinder 10 and the heat-insulating hood 40 and is discharged to the outside through the air hole H2 of the base plate 50. This prevents the cooling air from accumulating at the bottom of the bottomed cylinder 10, and effectively cools the magnetic field device 31 and the electric motor 32.

[0081] The molten metal pump 1 can be used not only to circulate the molten metal in the furnace, but also to pump up the molten metal. In this case, as shown in FIG. 9, a molten metal discharge pipe 25 is connected to the discharge port P2 of the molten metal flow path C. One end of the molten metal discharge pipe 25 is connected to the discharge port P2 of the molten metal flow path body 20, and the other end (discharge port P3) is open. The discharge port P3 is located above the molten metal level ML when the molten metal pump 1 is installed in the furnace. As a result, the molten metal in the molten metal flow path C is driven and discharged from the discharge port P2, and then passes through the molten metal discharge pipe 25 and is pumped up into an external bucket (not shown) or the like.

[0082] As described above, in the molten metal pump 1 according to this embodiment, the molten metal flow path body 20 is provided detachably on the bottomed cylinder 10 as a separate body from the bottomed cylinder 10. More specifically, the molten metal flow path body 20 is provided detachably on the bottomed cylinder 10 at a position around the side wall 11 of the bottomed cylinder 10, where the magnetic field lines from the first permanent magnet among the multiple permanent magnets 31a penetrate the side wall 11 and the inner flow path wall 21 to reach the molten metal flow path C, and then penetrate the inner flow path wall 21 and the side wall 11 from the molten metal flow path C and return to the second permanent magnet adjacent to the first permanent magnet. This allows the molten metal flow path C to be renewed easily and at low cost according to this embodiment. As a result, the molten metal in the molten metal flow path C is driven efficiently during use, and when the discharge rate decreases, the performance of the molten metal pump can be restored quickly and at low cost by replacing the molten metal flow path body 20.

[0083] Furthermore, according to this embodiment, since the molten metal flow passage C is provided in the molten metal flow passage body 20 which is separate from the bottomed cylinder 10, the flow passage cross-sectional area can be easily increased compared to the case where the molten metal flow passage is provided in the side wall as in the conventional molten metal pump. This allows the discharge rate of the molten metal to be significantly increased. Even if the flow passage cross-sectional area of ​​the molten metal flow passage C is increased, the weight of the bottomed cylinder 10 does not change, and an increase in the weight of the molten metal pump 1 can be suppressed. This prevents the ease of handling of the molten metal pump 1 from being adversely affected, and allows relatively easy installation work inside a furnace, etc.

[0084] Furthermore, according to this embodiment, the insulating hood 40 thermally protects the molten metal driving part 30 and defines the cooling air flow paths S and T. This prevents the cooling air from accumulating at the bottom of the bottomed cylinder 10 as in the conventional molten metal pump, and improves the cooling efficiency.

[0085] Furthermore, according to this embodiment, since the movable hood 42 of the insulating hood 40 is configured to rotate together with the magnetic field device 31, even if the movable hood 42 is made of a metallic material, it is possible to prevent eddy currents from being generated in the movable hood 42 while the magnetic field device 31 is rotating. This allows the rotation speed of the magnetic field device 31 to be increased, so that the discharge rate of the molten metal can be significantly increased while suppressing power consumption. As a result, the molten metal pump 1 can be used to sufficiently circulate the molten metal in the furnace.

[0086] The insulating hood is not limited to the configuration of the above embodiment, and may be applied to a molten metal pump in which a molten metal flow path is formed in the side wall of a bottomed cylinder. This can improve the cooling efficiency of the permanent magnets of the molten metal pump of Patent Document 1, for example.

[0087] Based on the above description, a person skilled in the art may be able to conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the above-mentioned embodiments. Various additions, modifications, and partial deletions are possible within the scope of the conceptual idea and intent of the present invention derived from the contents defined in the claims and their equivalents. [Explanation of symbols]

[0088] 1. Molten metal pump 10 Bottomed cylinder 11 Side wall 12 Bottom wall 13 Support part 20 Molten metal flow path body 21 Inner channel wall 22 Outer channel wall 23 Upper channel wall 24 Lower channel wall 25 Molten metal discharge pipe 30 Molten metal drive section 31,31A magnetic field device 31a permanent magnet 31b,31c Support plate 32 Electric motor 32a Rotation axis 33 Rotation axis 34 Coupling 35 Mount 36 Bearing housing 40 Insulated Hood 41 Fixed Hood 41a Upper fixed hood 41b Lower fixed hood 42 Movable hood 50 Base Plate 60 Power supply control panel 60a, 60b terminals 61 Connecting conductor 100 furnace A Cooling Air C Molten metal flow path H1 Air Intake H2,H3 air vents H4 shaft insertion hole H5, H6 air vents M,M' Molten metal ML magnetic field lines P1 Intake port P2 outlet P3 outlet S,T Cooling air passage

Claims

1. A molten metal pump for driving molten metal in a furnace, A bottomed cylinder having a side wall and a bottom wall; a molten metal flow passage body that has a molten metal flow passage connecting a suction port and a discharge port and is separate from the bottomed cylinder body; a molten metal driving unit including a magnetic field device rotatably disposed inside the bottomed cylinder around a vertical rotation axis and an electric motor for rotating the magnetic field device, the molten metal driving unit driving the molten metal in the molten metal flow path; a heat insulating hood configured to cover the magnetic field device and the electric motor of the molten metal driving unit and to define a cooling air flow path for cooling air to flow through the magnetic field device and the electric motor; Equipped with The magnetic field device includes a plurality of permanent magnets arranged such that alternating magnetic poles are aligned along the circumference of the rotating shaft; The molten metal pump is characterized in that the molten metal flow path body is detachably mounted to the bottomed cylinder at a position around the side wall of the bottomed cylinder, where magnetic field lines from a first permanent magnet among the multiple permanent magnets pass through the side wall of the bottomed cylinder and the inner flow path wall of the molten metal flow path body to reach the molten metal flow path, and then pass from the molten metal flow path through the inner flow path wall of the molten metal flow path body and the side wall of the bottomed cylinder to return to a second permanent magnet adjacent to the first permanent magnet.

2. 2. The molten metal pump according to claim 1, wherein the molten metal flow passage has a vertical cross-sectional shape that is substantially rectangular.

3. 3. The molten metal pump according to claim 1, wherein the plurality of permanent magnets of the magnetic field device have a vertical length greater than that of the molten metal flow path and encompass the molten metal flow path in the vertical direction when viewed from the side.

4. 4. The molten metal pump according to claim 1, wherein the molten metal flow passage body is provided so as to surround the side wall of the bottomed cylinder.

5. 5. The molten metal pump according to claim 4, wherein the molten metal passage body has a substantially U-shaped planar shape.

6. The insulating hood is a fixed hood that is fixed to a base plate that defines, together with the bottomed cylinder, a space for accommodating the magnetic field device, covers the motor, and is provided with an air intake for taking in cooling air; a movable hood that is attached to the magnetic field device so as to define the cooling air flow path together with the fixed hood and cover an outer circumferential surface of the magnetic field device and rotate together with the magnetic field device; The molten metal pump according to any one of claims 1 to 5, further comprising:

7. The fixed hood includes: an upper fixed hood having a lower end portion fixed to an upper surface of the base plate; a lower fixed hood having an upper end portion fixed to a lower surface of the base plate; 7. The molten metal pump according to claim 6, further comprising:

8. 8. The molten metal pump according to claim 6, wherein the fixed hood and the movable hood are covered with a heat insulating material.

9. 9. The molten metal pump according to claim 6, wherein the fixed hood and the movable hood are made of a metallic material.

10. 10. The molten metal pump according to any one of claims 6 to 9, characterized in that a lower end of the fixed hood is loosely inserted into an upper end of the movable hood, or an upper end of the movable hood is loosely inserted into a lower end of the fixed hood.

11. The base plate is provided with a first air hole located inside the fixed hood and a second air hole located outside the fixed hood, 11. The molten metal pump according to any one of claims 6 to 10, characterized in that the cooling air taken in through the air intake of the fixed hood flows downward through the cooling air flow path through the first air hole, passes through the magnetic field device and is released from the lower end of the movable hood, and then passes through the space between the side wall of the bottomed cylinder and the insulating hood and is discharged to the outside from the second air hole.

12. The molten metal pump according to any one of claims 1 to 11, characterized in that the bottomed cylinder has a support portion protruding radially outward from the side wall, and the molten metal flow path body is removably supported by the bottomed cylinder by the support portion.

13. 13. The molten metal pump according to claim 1, wherein the electric motor is configured to vary the rotation speed of the magnetic field device in accordance with the discharge rate of the molten metal.

14. 14. The molten metal pump according to claim 1, further comprising a molten metal discharge pipe connected to the discharge port of the molten metal flow path for pumping up the molten metal.

Images