KR0178136B1 - Apparatus for extracting hydrogen gas and non-metal residues from liquefied metal - Google Patents

Abstract

An object of the present invention is to remove an apparatus for minimizing inert gas and the like in molten metal and spreading it uniformly to efficiently remove hydrogen gas and nonmetallic inclusions.

The present invention relates to a processing cylinder (14) for pooling molten metal, rotating shafts (5) and (6) rotatable in the forward and reverse directions, and the tip of which is located in the processing cylinder, and a bubble generator attached to the leading end of the rotating shaft. 30 and the like. The bubble generator 30 generates bubbles by injecting an inert gas into the molten metal while reversing in the forward and reverse directions every predetermined time.

Description

Device for removing hydrogen gas and non-metallic inclusions in molten metal

1 is an explanatory diagram showing an embodiment of the apparatus for removing hydrogen gas and non-metallic inclusions according to the present invention.

2 is a longitudinal sectional view showing the structure of the bubble generator.

3 is a plan view showing the structure of the gas diffuser.

4 is a cross-sectional view along the line A-A in FIG.

5 is a plan view showing the structure of a turntable.

6 is a sectional view taken along line B-B in FIG.

7 is a longitudinal sectional view showing another embodiment of the bubble generator.

8 is a bottom view showing another embodiment of the bubble generator shown in FIG.

* Explanation of symbols for main parts of the drawings

M: Device for removing hydrogen gas and non-metallic inclusions of molten metal

5,6: rotating shaft 14: processing barrel

15 gas passage 16 gas outlet

17: gas communication path 18: gas destruction

19a: Gas passage 19b: Gas turbulence groove

20: gas diffuser 21: attachment portion

21a: Lower part 22: Male thread part

30: bubble generator 30a: bubble generator

31: mounting hole 32: female thread

33: ejection groove 34: gas communication path

35: height 40: turntable

41: lower fitting portion 42: center fitting portion

43: upper fitting portion 43a: curved portion

43b: straight part 44: stair part

61: external thread 62: female thread

The present invention relates to a removal apparatus for removing hydrogen gas and non-metallic inclusions contained in molten metal such as aluminum or magnesium containing an alloy, and a bubble generator used therein.

Molten metals such as aluminum, aluminum alloys, and magnesium contain hydrogen gas and nonmetallic inclusions, as well as other impurities, and when they are cast as they are, defects occur in the product. For this reason, when casting, it is necessary to remove hydrogen gas and nonmetallic inclusions from the molten metal.

As a method for doing this, a gas bubble atomized by the cutting blades is blown into the molten metal by injecting an inert gas from the nozzle into the molten metal and rotating in one direction, such as the Spinning Nozzle Inert Flotation method or the Alpur method. There is a method of diffusing, harvesting by contacting with hydrogen gas and non-metallic inclusions, and floating by removing them from the surface of molten metal.

However, the above-described conventional method has the following problems.

That is, since the inert gas is to physically harvest and remove the hydrogen gas and non-metallic inclusions by the contact reaction with the molten metal, it is necessary to contact the inert gas with more molten metal in order to increase the removal efficiency. Accordingly, the flow distance may be increased by miniaturizing bubbles and generating turbulence into the molten metal. In addition, since the diffusion effect is reduced at low and medium speed rotation, the removal efficiency is improved by increasing the speed of the rotating body in order to achieve uniform diffusion. As the method, an inert gas is refined and discharged through a porous material, and then cut and refined again with a stirring blade rotating at 100 to 2000 rpm to diffuse into the molten metal.

However, the conventional stirring blade only rotates in one direction, and when it rotates at a high speed, a swirl flow occurs, so that the entire molten metal in the processing furnace causes a rotational movement, and the actual flow distance of bubbles in the molten metal becomes short, and the effect of the high speed rotation is achieved. Does not get. In addition, significant eddy currents are generated on the surface of the molten metal, and impurities in the gas or the surface of the molten metal are dried in the atmosphere, and the degassing effect and the removal effect of nonmetallic inclusions are rather reduced. Therefore, in the conventional apparatus, it was necessary to attach a baffle plate in the vertical direction with respect to the stirring blade and to suppress the swirl flow.

This baffle had a drawback of being consumed in a short period of time in that it was attached in a direction opposite to the rotational direction of the swirl flow of the molten metal. In addition, the use of a baffle plate causes dead zones for bubbles as long as molten metal is rotated, and a portion that does not come into contact with impurities occurs. In addition, since the porous material is in direct contact with the molten metal, the method of using the porous material is consuming, and the management of the device is cumbersome since the replacement is required in a short time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to efficiently remove hydrogen gas and non-metallic inclusions by minimizing and uniformly dispersing an inert gas in molten metal without using an obstruction plate or the like as a conventional apparatus. It is an object to provide a device.

Means of the present invention devised to achieve the above object are as follows.

In the first means, there is provided a removal device for removing hydrogen gas and non-metallic inclusions in molten metal, the device comprising a processing passage for agglomeration of the molten metal, a rotating shaft rotatable in the forward and reverse direction, and having a tip end located in the processing cylinder as described above. And a bubble generator attached to the distal end of the rotary shaft, wherein the bubble generator reverses the forward and reverse directions at regular time intervals and injects inert gas into the molten metal to generate bubbles. And a non-metallic inclusion removing device.

In the second means, it is a bubble generator for use in a device for removing hydrogen gas and non-metallic inclusions in molten metal, the bubble generator being provided on a rotating body attachable to a rotating shaft, and the rotating center of the rotating body. And a gas passage for supplying the inert gas supplied from the whole, a gas ejection outlet of the required number provided in the outer surface of the rotating body, and a gas communication passage for communicating these gas ejections with the gas passage. It is a bubble generator.

According to the apparatus for removing hydrogen gas and non-metallic inclusions in the molten metal, the inert gas supplied from the gas passage in the center of rotation by blowing the bubble generator in the molten metal is ejected into the molten metal from the gas outlet through the gas communication passage. At this time, in the gas ejection port, the ejecting gas is continuously cut and fine bubbles are generated. The generated bubbles flow in the molten metal turning by the rotation of the bubble generator, and while staying, the hydrogen gas and nonmetallic inclusions are harvested and floated on the molten metal surface.

In addition, since the bubble generator reverses in the forward and reverse directions, continuous vortices do not occur on the surface of the molten metal, and it is difficult to produce gas in the atmosphere or impurities in the surface of the molten metal. Furthermore, turbulence is generated in the molten metal by reversal of the forward and reverse directions, whereby bubbles become interesting and efficient removal of hydrogen gas and nonmetallic inclusions is performed.

EXAMPLE

The present invention will be described with reference to the embodiments shown in the drawings. 1 is an explanatory diagram showing an embodiment of a hydrogen gas and non-metallic inclusion removal apparatus according to the present invention.

Symbol M is a device for removing hydrogen gas and nonmetallic inclusions in molten metal. Reference numeral 14 denotes a processing cylinder for accommodating molten metal 50, such as aluminum, and a lid 13 holding a window at the center is covered with an upper opening of the processing cylinder 14. On the cover 13, a plate 12 is provided via a support base 9. In the center portion of the plate 12, a metal rotating shaft 5 is provided. The carbon rotary shaft 6 is connected to the lower end of the tip end portion of the rotary shaft 5 via the flange 8. The rotating shaft 6 may be formed of another material excellent in heat resistance such as ceramics.

At the lower end of the tip end portion of the rotary shaft 6, a bubble generator 30 is provided which emits gas by miniaturizing it. The bubble generator 30 is mentioned later. The rotary shaft 5 has a pulley at the top and is driven by the motor 10 and the belt 3.

Reference numeral 11 denotes a controller such as an inverter for controlling the rotational direction, rotation time and the like of the motor 10, numeral 4 denotes a bearing and numeral 2 a rotary seal. The gas passage 15 is formed in the rotary seal 2, the rotating shaft 5, the bearing 4, and the rotating shaft 6, and the processing gas supplied from the gas supply pipe 1 installed at the upper end is It is discharged into the molten metal 50 from the gas ejection port 16 of the bubble generator 30 provided in the front end of the rotating shaft 6.

FIG. 2 is a longitudinal sectional view showing the structure of the bubble generator, FIG. 3 is a plan view showing the structure of the gas diffuser, FIG. 4 is a sectional view AA in FIG. 3, and FIG. 5 is a plan view showing the structure of the rotary disk, 6 is a sectional view taken along line BB in FIG.

The bubble generator 30 is provided with the gas diffuser 20 and the rotating disk 40. As shown in FIG. In the lower part of the gas diffuser 20, a disk-shaped gas fine plug 19 is provided. The attachment part 21 for attaching with the rotating shaft 6 is provided in the upper part of the gas atomization plug 19. As shown in FIG. On the outer circumferential surface of the attachment portion 21, there is provided a male screw portion 22 which is screwed together with the female screw portion 62 of the distal end portion of the rotating shaft. In addition, the gas passage 15 is formed in the longitudinal direction at the center of rotation.

A gas cake 18 is provided at the tip of the gas passage 15 of the gas atomizing plug 19. The gas atomization plug 19 is provided with six gas communication paths 17 which penetrate from the gas lump 18 to the outer circumferential surface in a horizontal and radial shape. Furthermore, a gas passage 19a which functionally assists the gas ejection opening 16 formed between the gas microfluidic plug 19 and the gas ejection opening 16 formed between the 40 and the rotary disk described later is connected to the gas communication passage 17 in succession. Plural are installed. Moreover, the gas turbulence groove 19b is provided in the outer peripheral part of the gas refinement plug 19 over the whole circumference.

The rotary disk 40 has a disk shape and is provided with three lower fitting portions 41, a central fitting portion 42, and an upper fitting portion 43 each having a different diameter. The lower fitting portion 41 has a small diameter in the upper staircase portion 44 to form the central fitting portion 4, and furthermore, has a large diameter at the upper end to form the upper fitting portion 43. The lower fitting portion 41 is circular and has an inner diameter that is slightly larger than the diameter of the gas atomizing plug 19 described above, so that the micronized plug 19 of the gas atomizing plug 19 is shown in FIG. A gas ejection opening 16 is formed between the outer circumference and the inner circumference of the lower fitting portion 41. In addition, the inner diameter of the center fitting part 42 is a diameter substantially the same as the lower part 21a of the attachment part 21 mentioned above.

The upper fitting portion 43 is to ensure that the fit state with the rotary disk 40 is always maintained even if the rotating shaft 6 is reversed during operation, and cuts the circumference every 45 degrees and the outer surface is equally spaced. This is a shape composed of four curved portions 43a and a straight portion 43b. In addition, the lower end of the rotating shaft 6 also has a shape corresponding to the upper fitting portion 43.

The use of the bubble generator 30 described above is not limited to the hydrogen gas and the non-metallic inclusion removing device M having a mechanism for reversing in the forward and reverse directions according to the present invention, and the hydrogen gas of the mechanism rotating in only one conventional direction. It can also be applied to non-metallic inclusion removal device.

The operation of this embodiment will be described with reference to FIGS.

The support base 9 is fixed to the predetermined position of the lid 13 of the processing container while releasing the inert gas from the gas supply pipe 1, so that the plate 12 sets each mechanism. At the same time, the rotary shaft 6 and the bubble generator 30 are immersed in the molten metal. For this reason, the gas passes through the gas communication passage 17 of the bubble generator 30 from the gas passage 15 and is blown into the molten metal 50 at the gas ejection opening 16.

The motor 10 is operated to rotate the bubble generator 30 together with the rotary shafts 5 and 6. Since the forward rotation time and the reverse rotation time are set in advance by the controller 11, the motor 10 inverts in the forward and reverse directions according to the setting, and repeats it.

Gas passing through the gas passage 15 collides with the gas mass 18 and passes through the gas communication passage 17 in the gas atomization plug 19 to make the bubbles finer than the gas outlet 16 and each gas passage 19a. It is discharged.

The fine structure of the gas in this case is demonstrated. First, as the gas passing through the gas passage 15 passes through the narrower gas communication passage 17 or the gas ejection port 16, the gas velocity increases. Furthermore, since the gas ejector 16 is provided slightly from the center of the rotation shaft 6, the gas is outwardly and tangentially directed at the outlet of the gas ejection port 16 by the action of the gas ejection speed and the centrifugal force. It is efficiently cut, and micronized bubbles are generated.

Next, the experiment example performed using the aluminum alloy AC4C (JIS) of 500 kg of melt | dissolution amount by this Example is shown.

Example 1

Hydrogen gas in the molten metal was analyzed by an Arscan analyzer with 20 liters of inert gas (nitrogen gas) blown out every minute, rotation speed of 450 rpm and forward / reverse interval of 8 seconds.

Hydrogen gas amount before treatment 0.37cc / 100g Al

Hydrogen gas content after 5 minutes 0.12cc / 100g Al

In the conventional apparatus, for example, the one-way rotating apparatus which does not possess a microbubble generator having a rotational speed of 300 rpm, the processing time for obtaining the above-described processing result required 10 minutes. In general, defective products are less likely to occur when the amount of hydrogen gas is 0.15 cc / 100 g Al or less.

In addition, in the hydrogen gas and nonmetallic inclusion removing device M of the molten metal of this embodiment, the gas communication passages 17 connected to the gas outlet 16 are not limited to six as in this embodiment, but can be set to the required number. have. The same also applies to the gas passage 19a. In addition, the gas-refining plug 19 does not use a low-density porous material as in the prior art, and the durability is improved and troublesome in that a material having the same density or higher than that of the rotating shaft 6 or the rotary disk 40 can be used. No exchange was required.

Example 2

The experiment example performed using the aluminum alloy AC-4C (JIS) of melt | dissolution amount 400 kg is shown. The amount of inert gas (argon gas) to be blown out was 18 liters per minute, the rotation speed was 450 rpm, and the interval between forward and reverse rotations was 8 seconds, and the inclusions in the molten metal were measured by the K-molding method. The following results were obtained.

Inclusions Before Treatment 28.9

Inclusions after 7 minutes of treatment 1.2

It has been recognized that when the above-described treatment is carried out with a conventional apparatus, for example, a one-way rotating apparatus having a baffle plate at a rotational speed of 600 rpm, the inclusion after the treatment increases inversely than the amount of inclusion before the treatment.

In this respect, it is considered that the treatment in one direction rotation causes the oxide film on the surface of the melt to be wound into the melt, thereby increasing the inclusions.

The present invention can prevent the casting of the surface oxide into the molten metal and reduce the casting defect due to the inclusions without incurring continuous swirl on the molten surface by inverting in the forward and reverse directions.

7 is a longitudinal sectional view showing another embodiment of the bubble generator, and FIG. 8 is a bottom view.

The bubble generator 30a which concerns on a present Example is a bubble generator which does not use a plug unlike the above-mentioned embodiment. The bubble generator 30a is disk-shaped, and the mounting hole 31 is provided in the center of the upper part to the depth of about 1/2. A female screw portion 32 is formed in the inner circumferential portion of the mounting hole 31. At the bottom of the bubble generator 30a, eight gas ejection grooves 33 are provided radially. The guide end of each gas ejection groove 33 is circular in the same distance from the center, and the outer end reaches the outer periphery of the bubble generator 30a. A gas communication path 34 is provided between the mounting hole 31 and each gas ejection groove 33 so as to communicate with each other.

The bubble generator 30a is screwed into the female screw portion 32 of the mounting hole 31 by a male screw portion 61 provided on the outer circumferential portion of the tip end portion of the rotary shaft 6. At this time, a space 62 is provided between the lower end of the rotary shaft 6 and the lower portion of the mounting hole 31, whereby the gas passage 15 and the respective ejection grooves 33 of the rotary shaft 6 are thereby provided. ) Is communicating.

Reference numeral 35 denotes a key and is mounted so as to be attached to and detached from the lower part of the bubble generator 30a so as to act as both the outer circumferential portion of the rotating shaft 6 and the inner circumferential portion of the mounting hole 31. In addition, as described above, when screwed in, the adhesive is applied to the threaded surface so that the bubble generator 30a can be more firmly fixed, and the looseness caused by the inertial force of the bubble generator 30a during the reverse direction in the forward and reverse directions. To prevent the burden.

According to the bubble generator 30a of this embodiment, since each blowing groove 33 becomes a cut | disconnected part of a bubble over the whole length, there exists an advantage that the refinement | miniaturization of a bubble is performed more effectively.

In addition, this invention is not limited to the above-mentioned embodiment, A various deformation | transformation is possible for it within the range described in a claim.

The present invention has the following effects with the above-described configuration.

(a) In the hydrogen gas and non-metallic inclusion removal device of the present invention, since the bubble generator reverses in the forward and reverse directions, continuous vortex does not occur on the molten metal surface, and the gas in the atmosphere or the impurities on the molten metal surface are rolled up. This is hard to occur. Furthermore, turbulence is generated in the molten metal by reversal of the forward and reverse directions, and thus the bubbles become interesting and the flow time is long, thereby efficiently removing hydrogen gas and non-metallic inclusions. The overall working time is shortened and the amount of gas used is also reduced, thus saving energy.

(b) According to the bubble generator according to the present invention, while rotating in the molten metal, the inert gas supplied from the gas passage in the center of rotation passes through the gas communication passage by centrifugal force and is ejected into the molten metal from the gas outlet to the gas outlet. In this way, the blowing gas is continuously cut to generate fine bubbles. As described above, since bubbles are generated as in the related art, it is not necessary to use a member that is insufficient in durability such as a porous material, and an obstruction plate for suppressing vortex is no longer necessary, and the device can be easily managed.

Claims (2)

A removal device that removes hydrogen gas and non-metallic inclusions in molten metal while preventing the mixing of oxides on the molten metal surface by preventing continuous swirling on the molten metal surface. (14), a mechanism for inverting the rotating shaft in the forward and reverse directions, rotating shafts 5 and 6 whose tip portions are located in the processing cylinder as described above, and the rotating shaft are attached to the tip end. And a bubble generator (30), wherein the bubble generator (30) is inverted in the forward and reverse directions at regular time intervals to inert gas into the molten metal to generate bubbles to generate hydrogen gas in the molten metal. And non-metallic inclusions removal device. The bubble generator (30) according to claim 1, wherein the bubble generator (30) is provided with a rotating body attachable to a rotating shaft, a gas passage provided at the center of rotation of the rotating body, and supplying an inert gas supplied from the rotating body; It is characterized by comprising a gas outlet port 16 of the required water provided in the outer surface portion of the rotating body, and a gas communication passage 17 connecting the gas outlet port 16 and the gas passage described above. Apparatus for removing hydrogen gas and non-metallic inclusions in molten metal.