Operating procedure for a liquid-dissolved holding furnace

Abstract

The present invention provides an operating method for a liquid-immersed melting and holding furnace that can reduce wear on the mixer used for degassing molten aluminum and suppress the generation of oxides. [Solution] In a liquid-submerged melting and holding furnace having a melting and holding chamber in which aluminum material is introduced into a liquid of flowing molten aluminum and melted, the rotation speed of the mixer that degasses the molten aluminum is increased or decreased in accordance with the increase or decrease in the amount of aluminum material introduced relative to a set amount Sw.

Description

Technical Field

[0001] The present invention relates to an operation processing method for a submerged melting and holding furnace.

Background Art

[0002] A submerged melting and holding furnace has a melting and holding chamber for charging and melting an aluminum material into a flowing aluminum melt. The flow of the aluminum melt in the melting and holding chamber is formed by utilizing the rotation of a mixer for degassing the aluminum melt. The degassing process is a process for reducing the amount of hydrogen gas in the aluminum melt. The mixer has a shaft inserted into the aluminum melt, a stirring blade attached to the tip of the shaft, and a gas supply passage formed in the shaft (see Patent Document ). An inert gas flows through the gas supply passage of the rotating mixer and is blown into the aluminum melt from the tip of the shaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The mixer for degassing rotates at a high speed constantly. Therefore, there is a problem that the wear is fast and the lifespan is short. The wear appears remarkably in the region of the shaft near the aluminum melt surface.

[0005] In addition, due to the mixer rotating at a high speed constantly, the undulation of the aluminum melt surface becomes relatively large. Therefore, there is a problem that it is difficult to suppress the generation of oxides.

[0006] Therefore, the present invention aims to provide an operating method for a liquid-immersed dissolution and holding furnace that can reduce wear on the mixer used for degassing molten aluminum and suppress the generation of oxides. [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a method for operating a liquid-immersed melting and holding furnace having a melting and holding chamber in which aluminum material is introduced into a liquid of flowing molten aluminum and melted. In the method for operating the liquid-immersed melting and holding furnace, the rotation speed of a mixer that degasses the molten aluminum is increased or decreased in accordance with the increase or decrease in the amount of aluminum material introduced relative to a set amount. [Effects of the Invention]

[0008] According to the present invention, the rotation speed of the mixer is increased or decreased in accordance with the increase or decrease in the amount of aluminum material added relative to the set amount, so the rotation speed of the mixer can be reduced when the amount of aluminum material added is small. As a result, compared to when the mixer is constantly rotating at high speed, the wear of the mixer can be reduced and the life of the mixer can be extended, and the wavering of the molten aluminum surface can be made relatively small, thereby suppressing the generation of oxides. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic plan view showing a liquid dissolution and holding furnace. [Figure 2] This is a schematic front view showing the dissolution and holding chamber of a liquid dissolution and holding furnace. [Figure 3] This is a schematic side view showing the dissolution and holding chamber of a liquid dissolution and holding furnace. [Figure 4] This is a schematic diagram showing the degassing treatment tank of the dissolution and holding chamber. [Figure 5] This is a block diagram showing the control system for operating a liquid-based dissolution and holding furnace. [Figure 6] This is a schematic diagram illustrating the control of increasing or decreasing the mixer's rotation speed according to the amount of aluminum material input and the temperature at which the aluminum material is input. [Figure 7]This is a schematic diagram illustrating the control of increasing or decreasing the flow rate of inert gas in accordance with the amount of aluminum material input. [Figure 8] This is a flowchart illustrating the operation method of a liquid-based dissolution and holding furnace. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The embodiments shown herein are illustrative examples for embodying the technical idea of ​​the present invention and do not limit the present invention. Therefore, all other implementable forms, examples, and operational techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included in the scope and spirit of the present invention, as well as in the claims and their equivalents.

[0011] Furthermore, the drawings attached to this specification may be schematically represented with changes to scale, aspect ratio, shape, etc., from the actual object for the sake of illustration and ease of understanding, but these are merely examples and do not limit the interpretation of the present invention.

[0012] <Embodiment> As shown in Figures 1, 2, 3, and 4, the liquid-immersed melting and holding furnace 10 of the embodiment includes a melting and holding chamber 20 into which aluminum material 50 is introduced and melted in a liquid of flowing molten aluminum 40, and a preheating device 30 for preheating the ingot of aluminum material 50 to be introduced into the melting and holding chamber 20. The liquid-immersed melting and holding furnace 10 also has a pressurizing chamber (not shown) into which the molten aluminum 40 from the melting and holding chamber 20 is sent into a mold under pressure. The molten aluminum 40 is made of Al or an Al alloy.

[0013] Between the melting and holding chamber 20 and the preheating device 30, a robot 60 is positioned to introduce the preheated aluminum material 50 into the melting and holding chamber 20, and a temperature sensor 51 is positioned to detect the temperature at which the aluminum material 50 is introduced.

[0014] The melting and holding chamber 20 is divided into an input tank 21, a melting tank 22, and a degassing treatment tank 23. In the input tank 21, ingots of aluminum material 50, preheated by a preheating device 30, are fed in through an input port 21a. The melting tank 22 is equipped with a heater 22a for melting the aluminum material 50. The degassing treatment tank 23 is equipped with a degassing treatment device 23a for performing degassing treatment. Degassing treatment is a process to remove or reduce hydrogen gas in the molten aluminum 40. The input tank 21 and the melting tank 22 are connected via a passage 24. The melting tank 22 and the degassing treatment tank 23 are connected via a passage 25. The degassing treatment tank 23 and the input tank 21 are connected via a passage 26.

[0015] The degassing apparatus 23a includes a rotatable mixer 70 for stirring the molten aluminum 40, a motor 71 for rotating the mixer 70, a gas supply source 72 filled with an inert gas (for example, argon or nitrogen), and a flow control valve 73 for adjusting the flow rate of the inert gas. As shown in Figure 4, the mixer 70 includes a shaft 70a inserted into the molten aluminum 40, a stirring blade 70b attached to the tip of the shaft 70a, and a gas supply passage 70c formed within the shaft 70a. The inert gas 74 flows through the gas supply passage 70c of the rotating mixer 70 and is blown into the molten aluminum 40 as fine bubbles from the tip of the shaft 70a. Hydrogen gas in the molten aluminum 40 is removed by diffusing into the bubbles.

[0016] The flow of molten aluminum 40 within the melting and holding chamber 20 is formed by the rotation of the mixer 70. As shown by the dashed arrows in Figure 1, the rotation of the mixer 70 causes the molten aluminum 40 to circulate and flow through the degassing tank 23 → passage 26 → input tank 21 → passage 24 → melting tank 22 → passage 25 → degassing tank 23 → ... During the degassing process, it is important to keep the surface of the molten aluminum as wavy as possible to suppress the generation of new oxides.

[0017] As shown in FIG. 5, the robot 60 and the temperature sensor 51 are connected to a controller 100 provided with a CPU and a memory. Information on the input amount of the aluminum material 50 associated with the operation of the robot 60 and information on the input temperature of the aluminum material 50 being input are input to the controller 100. The controller 100 is connected to the motor 71 and the flow rate adjustment valve 73. Control signals for controlling the rotation speed of the mixer 70 and control signals for adjusting the supply flow rate of the inert gas 74 are output from the controller 100.

[0018] As shown in FIG. 6, the controller 100 controls the increase and decrease of the rotation speed of the mixer 70 according to the input amount of the aluminum material 50 and the input temperature of the aluminum material 50.

[0019] The controller 100 increases or decreases the rotation speed of the mixer 70 for degassing the molten aluminum 40 as the input amount of the aluminum material 50 increases or decreases with respect to the set amount Sw. For example, when the input temperature of the aluminum material 50 is relatively low (below the set temperature St), when the input amount of the aluminum material 50 increases with respect to the set amount Sw, the mixer 70 is rotated at a high speed (region of reference sign A4). On the other hand, when the input amount of the aluminum material 50 decreases with respect to the set amount Sw, the mixer 70 is decelerated from high-speed rotation to medium-speed rotation (region of reference sign A3). Also, when the input temperature of the aluminum material 50 is relatively high (higher than the set temperature St), when the input amount of the aluminum material 50 increases with respect to the set amount Sw, the mixer 70 is rotated at a medium speed (region of reference sign A2). On the other hand, when the input amount of the aluminum material 50 decreases with respect to the set amount Sw, the mixer 70 is decelerated from medium-speed rotation to low-speed rotation (region of reference sign A1).

[0020] In this way, the rotation speed of the mixer 70 is increased or decreased in accordance with the increase or decrease in the amount of aluminum material 50 added relative to the set amount Sw. Therefore, when the amount of aluminum material 50 added is small, the rotation speed of the mixer 70 can be reduced. As a result, compared to when the mixer 70 is constantly rotating at high speed, wear on the mixer 70 is reduced and the lifespan of the mixer 70 can be extended. Furthermore, since the waviness of the molten aluminum surface is relatively small, the generation of oxides can be suppressed.

[0021] In the illustrated example, the rotation speed of the mixer 70 is controlled to increase or decrease in stages according to the amount of aluminum material 50 added, but it can also be controlled to increase or decrease in proportion to the amount added.

[0022] The controller 100 increases or decreases the rotation speed of the mixer 70 that degasses the molten aluminum 40 in accordance with the increase or decrease in the input temperature of the aluminum material 50 relative to the set temperature St. For example, when the input amount of aluminum material 50 is relatively small (less than or equal to the set amount Sw), and the input temperature of the aluminum material 50 decreases relative to the set temperature St, the mixer 70 is rotated at a medium speed (region A3). On the other hand, when the input temperature of the aluminum material 50 increases relative to the set temperature St, the mixer 70 is decelerated from medium speed to low speed (region A1). Also, when the input amount of aluminum material 50 is relatively large (greater than the set amount Sw), and the input temperature of the aluminum material 50 decreases relative to the set temperature St, the mixer 70 is rotated at a high speed (region A4). On the other hand, when the input temperature of the aluminum material 50 increases relative to the set temperature St, the mixer 70 is decelerated from high-speed rotation to medium-speed rotation (region A2).

[0023] In this way, the rotation speed of the mixer 70 is increased or decreased in accordance with the increase or decrease in the input temperature of the aluminum material 50 relative to the set temperature St. Therefore, when the input temperature of the aluminum material 50 is high, the rotation speed of the mixer 70 can be reduced. As a result, compared to when the mixer 70 is constantly rotating at high speed, wear on the mixer 70 is reduced and the lifespan of the mixer 70 can be extended. Furthermore, since the waviness of the molten aluminum surface is relatively small, the generation of oxides can be suppressed.

[0024] In the illustrated example, the rotation speed of the mixer 70 is controlled to increase or decrease in stages according to the input temperature of the aluminum material 50, but it can also be controlled to increase or decrease in proportion to the input temperature.

[0025] The setting amount Sw for the amount of aluminum material 50 to be input and the setting temperature St for the input temperature of aluminum material 50 can be changed in various ways depending on the production rate of castings per unit time, i.e., the consumption rate of molten aluminum 40 per unit time, the amount of aluminum material 50 to be input per unit time, the preheating temperature of the ingot, etc. For example, the setting amount Sw can be set to 100 kg / hour. The setting temperature St can be set to 150°C to 250°C when the preheating temperature of the ingot is, for example, 200°C. The rotation speed of the mixer 70 can also be set arbitrarily. For example, high-speed rotation can be set to 400 rpm, medium-speed rotation to 300 rpm, and low-speed rotation to 200 rpm. The low-speed rotation of the mixer 70 is set to a rotation speed that is sufficient to ensure the flow of molten aluminum 40 in the melting and holding chamber 20.

[0026] As shown in Figure 7, the controller 100 controls the flow rate of the inert gas 74 by increasing or decreasing it according to the amount of aluminum material 50 that is input.

[0027] The controller 100 increases or decreases the flow rate of the inert gas 74 used to degas the molten aluminum 40 in accordance with the increase or decrease in the amount of aluminum material 50 input relative to the set amount Sw. For example, when the amount of aluminum material 50 input increases relative to the set amount Sw, the flow rate of the inert gas 74 is increased. On the other hand, when the amount of aluminum material 50 input decreases relative to the set amount Sw, the flow rate of the inert gas 74 is decreased.

[0028] In this way, the flow rate of the inert gas 74 is increased or decreased in accordance with the increase or decrease in the amount of aluminum material 50 input relative to the set amount Sw. Therefore, when the amount of aluminum material 50 input is small, the amount of inert gas 74 injected can be reduced. As a result, the amount of inert gas 74 used can be reduced compared to when a large amount of inert gas 74 is constantly injected regardless of the operating status of the equipment.

[0029] In the illustrated example, the flow rate of the inert gas 74 is controlled by increasing or decreasing it in proportion to the amount of aluminum material 50 added, but it can be controlled in stages.

[0030] The flow rate of the inert gas 74 can be changed in various ways depending on the volume and temperature of the molten aluminum 40 in the degassing tank 23, the total volume of molten aluminum 40 in the melting and holding chamber 20, the amount of molten aluminum 40 consumed per unit time, and the amount of aluminum material 50 added per unit time.

[0031] The operation control of the liquid dissolution and holding furnace 10 will be explained with reference to the flowchart in Figure 8.

[0032] The controller 100 acquires information regarding the input temperature of the aluminum material 50 detected by the temperature sensor 51 (step S101). The controller 100 acquires information regarding the amount of aluminum material 50 input in conjunction with the operation of the robot 60 (step S102). The controller 100 acquires information regarding the flow rate of the inert gas 74 adjusted by the flow control valve 73 (step S103). The controller 100 acquires information regarding the rotational speed of the mixer 70 adjusted by the motor 71 (step S104).

[0033] The controller 100 determines whether the mixer rotation speed is appropriate for the amount of aluminum material 50 being added (step S105). If the controller 100 determines that the mixer rotation speed is appropriate for the amount of aluminum material 50 being added (step S105: Yes), it maintains the current mixer rotation speed (step S106). On the other hand, if the controller 100 determines that the mixer rotation speed is not appropriate for the amount of aluminum material 50 being added (step S105: No), it controls the mixer rotation speed (step S107). The controller 100 increases or decreases the rotation speed of the mixer 70 in accordance with the increase or decrease in the amount of aluminum material 50 being added relative to the set amount Sw (see Figure 6).

[0034] Next, the controller 100 determines whether the mixer rotation speed is appropriate for the input temperature of the aluminum material 50 (step S108). If the controller 100 determines that the mixer rotation speed is appropriate for the input temperature of the aluminum material 50 (step S108: Yes), it maintains the current mixer rotation speed (step S109). On the other hand, if the controller 100 determines that the mixer rotation speed is not appropriate for the input temperature of the aluminum material 50 (step S108: No), it controls the mixer rotation speed (step S110). The controller 100 increases or decreases the rotation speed of the mixer 70 in accordance with the increase or decrease in the input temperature of the aluminum material 50 relative to the set temperature St (see Figure 6).

[0035] Next, the controller 100 determines whether the inert gas flow rate is appropriate for the amount of aluminum material 50 being input (step S111). If the controller 100 determines that the inert gas flow rate is appropriate for the amount of aluminum material 50 being input (step S111: Yes), it maintains the current inert gas flow rate (step S112). On the other hand, if the controller 100 determines that the inert gas flow rate is not appropriate for the amount of aluminum material 50 being input (step S111: No), it controls the inert gas flow rate (step S113). The controller 100 increases or decreases the flow rate of the inert gas 74 used to degas the molten aluminum 40 in accordance with the increase or decrease in the amount of aluminum material 50 being input relative to the set amount Sw (see Figure 7).

[0036] The controller 100 then controls the operation of the liquid dissolution and holding furnace 10 by repeating the above-described process (steps S101 to S113).

[0037] The above describes embodiments of the operating method for the liquid dissolution and holding furnace 10 of the present invention. However, the present invention is not limited to the configuration described in the above embodiments, and can be modified as appropriate based on the claims. [Explanation of symbols]

[0038] 10 Submerged melting and holding furnace 20 Melting and holding chamber 21 Loading tank 21a Inlet 22 Dissolution tank 22a Heater 23 Degassing treatment tank 23a Degassing treatment apparatus 30 Preheating device 40 molten aluminum 50 Aluminum material 51 Temperature sensor 60 robots 70 Mixer 70a shaft 70b Agitator blade 70c gas supply channel 71 Motor 72 Gas supply sources 73 Flow control valve 74 Inert gas 100 controllers

Claims

1. In a method for operating a liquid-submerged melting and holding furnace having a melting and holding chamber in which aluminum material is immersed and melted in a liquid of flowing molten aluminum, A method for operating a liquid-immersed melting and holding furnace, comprising increasing or decreasing the rotation speed of a mixer that degasses the molten aluminum in accordance with the increase or decrease in the amount of aluminum material input relative to a set amount.

2. The method for operating a liquid-immersed melting and holding furnace according to claim 1, wherein the flow rate of an inert gas used to degas the molten aluminum is increased or decreased in accordance with the amount of aluminum material added increasing or decreasing relative to a set amount.

3. A method for operating a liquid dissolution and holding furnace according to claim 1 or 2, wherein the rotation speed of the mixer is increased or decreased in accordance with the increase or decrease in the input temperature of the aluminum material relative to the set temperature.

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