Lightweight aluminum alloy bar smelting method

Abstract

The invention relates to a smelting method of a light-weight aluminum alloy bar, which comprises the following steps of: proportioning, smelting, refining, refining and degassing, slagging off and pouring, adding a refining agent into a refining furnace for refining, degassing refined aluminum alloy melt in the refining furnace by adopting a double-rotor degassing machine, a driving mechanism for driving the rotating rod to do periodic positive and negative rotation movement is arranged outside the refining furnace; and the rotating rod rotates forwards and then rotates backwards in a single period. The formula of the light-weight aluminum alloy bar is adopted, the smelting method is optimized, especially the refining process is further optimized, the refined aluminum alloy melt in the refining furnace is degassed through the double-rotor degassing machine, the hydrogen content in the melt can reach the preset standard in a short time, meanwhile, the slagging-off loss is low, and the energy consumption is low. And the quality of the light-weight aluminum alloy bar can be improved, and economic benefits are good.

Description

Technical Field

[0001] The invention relates to a method for smelting a lightweight aluminum alloy bar, and belongs to the technical field of aluminum alloy smelting. Background Art

[0002] Lightweight aluminum alloys are increasingly used in rail transit, 3C electronic products and other fields. Therefore, major aluminum alloy manufacturers have developed various lightweight aluminum alloy products.

[0003] In the smelting process of lightweight aluminum alloy, due to its low density, during the refining process, when a degasser is used for degassing, the hydrogen content is not easy to control. For example, when the hydrogen content needs to be reduced to about 0.2 ml / 100 mg, the general inert gas is 10-20 L / min, the rotor speed is 360-600 rpm, and the degassing time is more than 30 min; it requires a longer degassing time, a higher rotor speed, etc. to achieve a lower hydrogen content.

[0004] However, longer degassing time and higher rotor speed will lead to increased slag removal losses, which is not conducive to improving the quality of lightweight aluminum alloy bars.

[0005] Based on this, the present invention is proposed. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for smelting lightweight aluminum alloy bars, and the specific technical scheme is as follows:

[0007] A method for smelting a lightweight aluminum alloy bar comprises the following steps:

[0008] Step 1: Ingredients

[0009] The components of the lightweight aluminum alloy bar include the following components in weight percentage:

[0010] Ti: 1-2%; Mn: 0.5-0.8%; Fe: 0.5-1%; B: 0.075-0.11%; Si: 1-2%; Zn: 0.5-1%; Mg: 0.5-1.2%; the rest is Al;

[0011] Step 2: Melting

[0012] Weigh the raw materials according to the above formula and put them into a medium frequency induction furnace for smelting to obtain a primary molten aluminum alloy;

[0013] Step 3: Refine

[0014] Adding a grain refiner to the primary molten aluminum alloy, raising the temperature, and allowing the molten aluminum alloy to stand, thereby obtaining a refined molten aluminum alloy;

[0015] Step 4: Refining and degassing

[0016] The refined aluminum alloy melt is transferred to a refining furnace, and a refining agent is added to the refining furnace for refining;

[0017] A double-rotor degasser is used to degas the refined aluminum alloy melt in the refining furnace, and the temperature in the refining furnace is controlled to be always higher than 715°C during the degassing process. After the refining is completed, a refined aluminum alloy melt is obtained;

[0018] Step 5: Slag removal and pouring

[0019] The refined aluminum alloy melt is deslagging and then transferred into a tundish for pouring to obtain lightweight aluminum alloy bars.

[0020] As a further improvement, in step 2, the smelting temperature is 680-720°C.

[0021] As a further improvement, in step 3, the temperature is raised to 740-750° C. and allowed to stand for 15-20 minutes.

[0022] As a further improvement, in step 3, the grain refiner is an aluminum-titanium-boron grain refiner.

[0023] As a further improvement, in step 4, the amount of refining agent added is 0.09-0.11% of the mass of the refined aluminum alloy melt, and the temperature in the refining furnace is controlled to be 720-740°C.

[0024] As a further improvement, two groups of degassing rotors are arranged inside the refining furnace, the degassing rotors comprising a rotating rod and a rotor head, and the rotating rods of the two groups of degassing rotors rotate in opposite directions;

[0025] The refining furnace is provided with a driving mechanism outside for driving the rotating rod to perform periodic forward and reverse motions; the rotating rod first rotates forward and then reverses in a single cycle.

[0026] A further improvement is that the driving mechanism includes a half gear ring, a half gear coaxially arranged with the half gear ring, a gear, and a gear fixing frame, the lower end of the half gear ring is provided with a circular groove, one side of the circular groove is provided with a semicircular light groove portion, and the other side of the circular groove is provided with a gear tooth portion 1; one side of the half gear is provided with a gear tooth portion 2, the center of the half gear is coaxially connected with an input shaft, the input shaft is coaxially connected to the half gear ring, the gear tooth portion 2 is located on one side of the input shaft, and the gear tooth portion 1 is located on the other side of the input shaft; the half gear and the gear are both located inside the circular groove, the gear tooth portion 2 matches the gear, the gear tooth portion 1 matches the gear, the gear is coaxially connected to a rotating rod, the outer sleeve of the rotating rod is provided with a bearing, and the outer ring of the bearing is fixedly connected to the gear fixing frame.

[0027] A further improvement is that when the gear is internally meshed with the gear tooth portion 1, the gear is not meshed with the gear tooth portion 2;

[0028] When the gear is externally meshed with the gear tooth portion 2, the gear is not meshed with the gear tooth portion 1.

[0029] As a further improvement, in step 4, the flow rate of the inert gas introduced by the degassing rotor into the refined aluminum alloy melt is 10-20 L / min, the rotation speed of the degassing rotor is 120-240 rpm, and the degassing time is 6-12 min.

[0030] In a further improvement, the inert gas is argon or nitrogen.

[0031] Beneficial effects of the present invention:

[0032] The present invention adopts a formula of lightweight aluminum alloy rods and optimizes the smelting method, especially further optimizes the refining process. By using a double-rotor degasser to degas the refined aluminum alloy melt in the refining furnace, the hydrogen content in the melt can reach a preset standard in a short time. At the same time, the slag removal loss is low, which is beneficial to improving the quality of the lightweight aluminum alloy rods and has good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the distribution of two groups of degassing rotors in the refining furnace of the present invention;

[0034] Figure 2 It is a structural schematic diagram of the driving mechanism of the present invention;

[0035] Figure 3 It is a connection diagram of the half gear ring, half gear and gear of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] Example 1

[0038] Step 1: Ingredients

[0039] The components of the lightweight aluminum alloy bar include the following components in weight percentage:

[0040] Ti: 1-2%; Mn: 0.5-0.8%; Fe: 0.5-1%; B: 0.075-0.11%; Si: 1-2%; Zn: 0.5-1%; Mg: 0.5-1.2%; the rest is Al;

[0041] Step 2: Melting

[0042] According to the above formula, raw materials are weighed and put into a medium frequency induction furnace for smelting at a smelting temperature of 680-690° C. to obtain an initial molten aluminum alloy;

[0043] Step 3: Refine

[0044] Adding aluminum-titanium-boron grain refiner to the primary aluminum alloy melt and heating to 740-750° C., standing for 15 minutes, to obtain refined aluminum alloy melt;

[0045] Step 4: Refining and degassing

[0046] The refined aluminum alloy melt is transferred to a refining furnace, and a refining agent is added into the refining furnace for refining; the amount of the refining agent added is 0.09% of the mass of the refined aluminum alloy melt, and the temperature in the refining furnace is controlled to be 720-730°C.

[0047] A single-rotor degasser (conventional degasser, a set of degassing rotors, an argon flow rate of 10-20 L / min, a rotation speed of the degassing rotor of 360 rpm, and a degassing time of 30 min) was used to degas the refined aluminum alloy melt in the refining furnace. The temperature in the refining furnace was controlled to be always higher than 715°C during the degassing process. After the refining was completed, a refined aluminum alloy melt was obtained. The hydrogen content was tested, and the hydrogen content was approximately 0.21 ml / 100 mg.

[0048] Step 5: Slag removal and pouring

[0049] The refined aluminum alloy melt is deslagging and then transferred into a tundish for pouring to obtain lightweight aluminum alloy bars. The deslagging loss is 27.5kg / t.

[0050] Example 2

[0051] Step 1: Ingredients

[0052] The components of the lightweight aluminum alloy bar include the following components in weight percentage:

[0053] Ti: 1-2%; Mn: 0.5-0.8%; Fe: 0.5-1%; B: 0.075-0.11%; Si: 1-2%; Zn: 0.5-1%; Mg: 0.5-1.2%; the rest is Al;

[0054] Step 2: Melting

[0055] According to the above formula components, raw materials are weighed and put into a medium frequency induction furnace for smelting at a smelting temperature of 690-700° C. to obtain an initial molten aluminum alloy;

[0056] Step 3: Refine

[0057] Adding aluminum-titanium-boron grain refiner to the primary aluminum alloy melt and heating to 740-750° C., standing for 20 minutes, to obtain refined aluminum alloy melt;

[0058] Step 4: Refining and degassing

[0059] The refined aluminum alloy melt is transferred to a refining furnace, and a refining agent is added into the refining furnace for refining; the amount of the refining agent added is 0.11% of the mass of the refined aluminum alloy melt, and the temperature in the refining furnace is controlled to be 730-740°C.

[0060] A double-rotor degasser (conventional degasser, two sets of degassing rotors, the two sets of degassing rotors rotate in opposite directions; the argon flow rate is 10-20L / min, the speed of the degassing rotor is 300rpm, and the degassing time is 20min) is used to degas the refined aluminum alloy melt in the refining furnace. The temperature in the refining furnace is always controlled to be higher than 715°C during the degassing process. After the refining is completed, a refined aluminum alloy melt is obtained; the hydrogen content is tested, and the hydrogen content is about 0.18ml / 100mg.

[0061] Step 5: Slag removal and pouring

[0062] The refined aluminum alloy melt is deslagging and then transferred into a tundish for pouring to obtain lightweight aluminum alloy bars. The deslagging loss is 23.9kg / t.

[0063] Example 3

[0064] Step 1: Ingredients

[0065] The components of the lightweight aluminum alloy bar include the following components in weight percentage:

[0066] Ti: 1-2%; Mn: 0.5-0.8%; Fe: 0.5-1%; B: 0.075-0.11%; Si: 1-2%; Zn: 0.5-1%; Mg: 0.5-1.2%; the rest is Al;

[0067] Step 2: Melting

[0068] According to the above formula, raw materials are weighed and put into a medium frequency induction furnace for smelting at a smelting temperature of 700-720° C. to obtain an initial molten aluminum alloy;

[0069] Step 3: Refine

[0070] Adding aluminum-titanium-boron grain refiner to the primary aluminum alloy melt and heating to 740-750° C., standing for 20 minutes, to obtain refined aluminum alloy melt;

[0071] Step 4: Refining and degassing

[0072] The refined aluminum alloy melt is transferred to a refining furnace, and a refining agent is added into the refining furnace for refining; the amount of the refining agent added is 0.11% of the mass of the refined aluminum alloy melt, and the temperature in the refining furnace is controlled to be 730-740°C.

[0073] A double-rotor degasser is used to degas the refined aluminum alloy melt in the refining furnace, and the temperature in the refining furnace is controlled to be always higher than 715°C during the degassing process. After the refining is completed, a refined aluminum alloy melt is obtained;

[0074] like Figure 1 As shown, two groups of degassing rotors are arranged inside the refining furnace 10, and the degassing rotors include a rotating rod 11 and a rotor head 12, and the rotating rods 11 of the two groups of degassing rotors rotate in opposite directions;

[0075] The refining furnace 10 is provided with a driving mechanism 20 outside for driving the rotating rod 11 to perform periodic forward and reverse motions; the rotating rod 11 first rotates forward and then reverses in a single cycle; for example, it first rotates clockwise and then counterclockwise, and one cycle ends; the next cycle repeats.

[0076] Step 5: Slag removal and pouring

[0077] The refined aluminum alloy melt is deslagging and then transferred into a tundish for pouring to obtain lightweight aluminum alloy bars.

[0078] like Figures 1 to 3 As shown, the driving mechanism 20 includes a half gear ring 21, a half gear 22 coaxially arranged with the half gear ring 21, a gear 23, and a gear fixing frame 25. The lower end of the half gear ring 21 is provided with a circular groove 210, one side of the circular groove 210 is provided with a semicircular light groove portion 211, and the other side of the circular groove 210 is provided with a gear tooth portion 1 212; one side of the half gear 22 is provided with a gear tooth portion 221, and the center of the half gear 22 is coaxially connected with an input shaft 222, and the input shaft 222 is connected to the half gear 221. The ring gear 21 is coaxially connected, the gear tooth portion 221 is located on one side of the input shaft 222, and the gear tooth portion 1 212 is located on the other side of the input shaft 222; the half gear 22 and the gear 23 are both located inside the circular groove 210, the gear tooth portion 221 matches the gear 23, the gear tooth portion 1 212 matches the gear 23, the gear 23 is coaxially connected to the rotating rod 11, and the outer sleeve of the rotating rod 11 is provided with a bearing 24, and the outer ring of the bearing 24 is fixedly connected to the gear fixing frame 25.

[0079] The gear fixing frame 25 is used to fix the bearing 24 and the half gear ring 21. The input shaft 222 is driven by a servo motor to rotate 360°. Due to the special structure of the half gear ring 21 and the half gear 22, generally speaking, if a gear has only half the number of teeth, it is called a "half gear" or "half gear ring". When one of the half gear ring 21 and the half gear 22 is engaged with the gear 23, there will be no interference between the other and the gear 23.

[0080] When the gear 23 is meshed with the gear tooth part 1 212, the gear 23 is not meshed with the gear tooth part 221. Since the half gear 22 and the half gear ring 21 always rotate synchronously under the drive of the servo motor, if the half gear 22 and the half gear ring 21 rotate clockwise at this time, the gear 23 will also rotate clockwise.

[0081] Since the half gear 22 always rotates clockwise, when the gear 23 is meshed with the outer gear tooth portion 221, the gear 23 is not meshed with the gear tooth portion 1 212, and the gear 23 will rotate counterclockwise.

[0082] When the driving mechanism 20 of the present invention drives the rotating rod 11 to rotate, it is suitable for rotating at 240 rpm or below.

[0083] In step 4, the flow rate of the inert gas (argon) introduced by the degassing rotor into the refined aluminum alloy melt is 10-20 L / min, the rotation speed of the degassing rotor is 120-240 rpm, and the degassing time is 11 minutes.

[0084] The rotor head 12 is a gas rotating nozzle made of graphite. The gas forms fine and dispersed small bubbles through the nozzle. At the same time, as the degassing rotor rotates, the bubbles are evenly dispersed in the entire melt, increasing the contact area between the gas and the liquid, extending the movement distance and residence time of the bubbles in the aluminum liquid, increasing the gas volume, and absorbing the gas and oxide inclusions in the melt to float to the surface of the melt, thereby achieving the purification effect of degassing and impurity removal.

[0085] In the present invention, the hydrogen content of the refined aluminum alloy melt is detected, and the hydrogen content is about 0.09 ml / 100 mg; the slag loss is 6.2 kg / t (the aluminum slag loss produced in each ton of melt is 6.2 kg).

[0086] The continuous forward and reverse rotation of the melt of the present invention can generate a violent impact force at the moment of switching between forward and reverse rotation or reverse and forward rotation, which can prompt the inert gas to form finer bubbles and disperse better and deeper in the melt, thereby further improving the degassing effect.

[0087] Since a higher rotation speed creates more agitation, it produces more aluminum slag, which results in greater losses.

[0088] Comparative Example 1

[0089] Compared with Example 2, the two groups of degassing rotors have the same direction of rotation, the speed of the degassing rotor is 500rpm, the degassing time is 25min, and the rest are the same; the hydrogen content of the final refined aluminum alloy melt is about 0.17ml / 100mg, and the slag loss is 50.5kg / t.

[0090] Comparative Example 2

[0091] Compared with Example 2, the two groups of degassing rotors in this example rotate in opposite directions, the argon flow rate is 10-20 L / min, the speed of the degassing rotor is 240 rpm, the degassing time is 11 min, and the motor is directly used to drive the rotating rod 11 to rotate in one direction; the rest are the same; the hydrogen content of the final refined aluminum alloy melt is about 0.53 ml / 100 mg. The slag loss is 11.1 kg / t.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for smelting lightweight aluminum alloy bars, characterized in that: The following steps are involved: Step 1: Ingredients The components of the lightweight aluminum alloy bar include the following components in weight percentage: Ti: 1~2%; Mn: 0.5~0.8%; Fe: 0.5-1%; B: 0.075~0.11%; Si: 1~2%; Zn: 0.5~1%; Mg: 0.5-1.2%; the rest is Al; Step 2: Melting Weigh the raw materials according to the above formula and put them into a medium frequency induction furnace for smelting to obtain a primary molten aluminum alloy; Step 3: Refine Adding a grain refiner to the primary molten aluminum alloy, raising the temperature, and allowing the molten aluminum alloy to stand, thereby obtaining a refined molten aluminum alloy; Step 4: Refining and degassing The refined aluminum alloy melt is transferred to a refining furnace, and a refining agent is added to the refining furnace for refining; A double-rotor degasser is used to degas the refined aluminum alloy melt in the refining furnace, and the temperature in the refining furnace is controlled to be always higher than 715°C during the degassing process. After the refining is completed, a refined aluminum alloy melt is obtained; Step 5: Slag removal and pouring The refined aluminum alloy melt is deslagging and then transferred into a tundish for pouring to obtain lightweight aluminum alloy bars.

2. A lightweight aluminum alloy bar smelting method according to claim 1, characterized in that: In step 2, the smelting temperature is 680-720°C.

3. The method for smelting a lightweight aluminum alloy bar according to claim 1, characterized in that: In step 3, the temperature is raised to 740-750° C. and allowed to stand for 15-20 minutes.

4. The method for smelting a lightweight aluminum alloy bar according to claim 1, characterized in that: In step 3, the grain refiner is an aluminum titanium boron grain refiner.

5. The method for smelting a lightweight aluminum alloy bar according to claim 1, characterized in that: In step 4, the amount of refining agent added is 0.09-0.11% of the mass of the refined aluminum alloy melt, and the temperature in the refining furnace is controlled to be 720-740°C.

6. The method for smelting a lightweight aluminum alloy bar according to claim 1, characterized in that: Two groups of degassing rotors are arranged inside the refining furnace (10), the degassing rotors comprising a rotating rod (11) and a rotor head (12), and the rotating rods (11) of the two groups of degassing rotors rotate in opposite directions; The refining furnace (10) is provided with a driving mechanism (20) outside thereof for driving a rotating rod (11) to perform periodic forward and reverse motions; within a single cycle, the rotating rod (11) first rotates forward and then reverses.

7. A lightweight aluminum alloy bar smelting method according to claim 6, characterized in that: The driving mechanism (20) comprises a half gear ring (21), a half gear (22) coaxially arranged with the half gear ring (21), a gear (23), and a gear fixing frame (25); a circular groove (210) is arranged at the lower end of the half gear ring (21); a semicircular light groove portion (211) is arranged on one side of the circular groove (210); and a first gear tooth portion (212) is arranged on the other side of the circular groove (210); a second gear tooth portion (221) is arranged on one side of the half gear (22); an input shaft (222) is coaxially connected to the center of the half gear (22); the input shaft (222) is connected to the half gear ring (211) and the input shaft (222) is connected to the half gear ring (211). The input shaft (21) is coaxially connected, the second gear tooth portion (221) is located on one side of the input shaft (222), and the first gear tooth portion (212) is located on the other side of the input shaft (222); the half gear (22) and the gear (23) are both located inside the circular groove (210), the second gear tooth portion (221) matches the gear (23), and the first gear tooth portion (212) matches the gear (23), the gear (23) is coaxially connected to the rotating rod (11), the outer sleeve of the rotating rod (11) is provided with a bearing (24), and the outer ring of the bearing (24) is fixedly connected to the gear fixing frame (25).

8. A lightweight aluminum alloy bar smelting method according to claim 7, characterized in that: When the gear (23) is internally meshed with the first gear tooth portion (212), the gear (23) is not meshed with the second gear tooth portion (221); When the gear (23) is externally meshed with the second gear tooth portion (221), the gear (23) is not meshed with the first gear tooth portion (212).

9. A lightweight aluminum alloy bar smelting method according to claim 8, characterized in that: In step 4, the flow rate of the inert gas introduced into the refined aluminum alloy melt by the degassing rotor is 10 to 20 L / min, the rotation speed of the degassing rotor is 120 to 240 rpm, and the degassing time is 6 to 12 minutes.

10. A lightweight aluminum alloy bar smelting method according to claim 9, characterized in that: The inert gas is argon or nitrogen.

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