Device and method for improving roundness of graphite in nodular cast iron

Abstract

The invention discloses a device and a method for improving the roundness of graphite in nodular cast iron, which can improve the spheroidizing effect and facilitate addition of a nucleating agent in different time periods so as to improve the roundness of graphite in cast iron after subsequent casting molding. The device for improving the roundness of the graphite in the spheroidal graphite cast iron comprises a spheroidizing bag body, wherein a suspender bracket is arranged on the spheroidizing bag body; the spheroidizing device further comprises a spheroidizing bag base, an industrial processor and a spectral data processing module. A ladle cover capable of moving up and down is arranged above the spheroidizing ladle body; a nucleating agent adding device and a telescopic device are arranged on the ladle cover; the method comprises the following steps: S1, pretreating molten iron; and S2, a device for improving the roundness of graphite in the nodular cast iron is adopted for spheroidizing treatment. By adopting the device and the method for improving the roundness of the graphite in the nodular cast iron, the nodulizing effect of the molten iron can be conveniently monitored in real time, the additive amount of the inoculant can be adjusted, non-contact stirring of the molten iron can be realized, and the inoculant and the molten iron can be sufficiently and uniformly mixed.

Description

Technical Field

[0001] The invention relates to the field of ductile iron casting, and in particular to a device and method for improving the roundness of graphite in ductile iron. Background Art

[0002] The roundness of graphite in cast iron is a key indicator of ductile iron quality and has a significant impact on its performance, primarily in terms of mechanical, machining, and physical properties. Factors influencing graphite morphology during the casting process include chemical composition, cooling conditions, alloying elements, and process control.

[0003] The roundness of graphite in ductile iron depends primarily on the spheroidization process, which is typically achieved using a spheroidizing bag. During the spheroidization of molten iron, a spheroidizing agent and an inoculant are added. Spheroidizing agents, also known as rare earth magnesium silicon iron alloys, are metals or alloys added to the molten iron to produce spherical graphite cast iron. They promote the crystallization of graphite into spheres. Inoculants promote nucleation and inhibit growth, resulting in grain refinement.

[0004] Existing spheroidizing ladles typically use a flushing method to achieve spheroidization. After spheroidization, an inoculant must be added before or during casting to delay decay. However, adding the inoculant after spheroidization is inconvenient, and stirring the molten iron to ensure uniform mixing is difficult. Consequently, the spheroidization effect is poor during the subsequent casting process. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a device for improving the spheroidization effect, facilitating the addition of inoculant at different times, facilitating real-time monitoring of the spheroidization effect of molten iron, adjusting the amount of inoculant added, realizing contactless stirring of molten iron, facilitating full and uniform mixing of the inoculant and molten iron, thereby improving the roundness of graphite in cast iron after subsequent casting.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a device for improving the roundness of graphite in ductile iron, comprising a spheroidizing bag body, a suspension rod support provided on the spheroidizing bag body; a turning drive device provided at the lower end of the suspension rod support;

[0007] It also includes a spheroidization bag base, an industrial processor and a spectral data processing module; a bag cover that can move up and down is provided above the spheroidization bag body;

[0008] The spheroidizing bag base is provided with a turntable; the turntable has a turntable; a limit ring is provided above the turntable; a support plate is provided between the limit ring and the spheroidizing bag base; the spheroidizing bag body is mounted on the turntable, and a limit wheel matching the limit ring is provided on the boom bracket outside the spheroidizing bag body; a brake device is provided between the support plate and the spheroidizing bag body;

[0009] The boom bracket is provided with a lifting device for driving the bag cover to move up and down; the bag cover is provided with an inoculant adding device and a telescopic device;

[0010] The telescopic device has a telescopic shaft passing through the cover, and a high-temperature resistant probe protective cover is provided at the lower end of the telescopic shaft; a spectrometer probe and a laser ranging sensor are provided in the probe protective cover; and a high-temperature resistant glass is provided at the lower end of the protective cover;

[0011] The spectrometer probe is electrically connected to a spectral data processing module; the spectral data processing module is used to analyze and process the spectral signal detected by the spectrometer probe to detect the content of magnesium, rare earth, silicon, sulfur, aluminum, titanium, and barium in the molten iron;

[0012] The industrial processor is used to control the amount of inoculant added by the inoculant adding device according to the detected content of magnesium, rare earth, silicon, sulfur, aluminum, titanium and barium elements in the molten iron; and to control the telescopic length of the telescopic shaft of the telescopic device.

[0013] Furthermore, the braking device includes a curved brake pad that matches the outer surface of the spheroidized package body;

[0014] A horizontal fixed plate is provided on the support plate; a pressure plate is hinged on the horizontal fixed plate; the arc-shaped brake pad has a sliding shaft; the sliding shaft passes through the support plate; a roller is provided at one end of the sliding shaft; an annular boss is provided under the roller; a spring is provided between the annular boss and the support plate; the spring is mounted on the sliding shaft; the upper end of the pressure plate is in contact with the roller.

[0015] Furthermore, an annular mounting groove is provided on the limiting ring; a thrust bearing is provided in the annular mounting groove.

[0016] Furthermore, the boom support includes two booms; a crossbeam is provided above the two booms; and a hook is provided on the crossbeam;

[0017] The lifting device includes a vertical screw rod arranged on the inner side of the boom bracket and a horizontal rotating shaft arranged below the crossbeam; side ears are arranged on both sides of the cover; the vertical screw rod passes through the side ears; the vertical screw rod is threadedly engaged with the side ears; a turbine is arranged on the upper end of the vertical screw rod; the vertical screw rod is connected to the horizontal rotating shaft through a worm gear;

[0018] A driven wheel is provided at one end of the transverse rotating shaft; a driving wheel is provided at the lower end of the boom; the driving wheel is connected to the driven wheel through a chain; and a manual turntable is provided on the driving wheel.

[0019] Furthermore, the telescopic device includes a driving motor and a supporting boss arranged on the cover; a rotating boss is arranged on the supporting boss; a rotating sleeve is rotatably mounted on the rotating boss; a driving turbine is arranged on the rotating shaft of the driving motor; the driving turbine is connected to the rotating sleeve by a worm gear transmission; the telescopic shaft passes through the rotating sleeve, the rotating boss and the supporting boss in sequence, and the telescopic shaft is threadedly engaged with the rotating sleeve.

[0020] Furthermore, the turntable is provided with a mounting groove matching the spheroidizing bag body; and the bottom of the mounting groove is provided with evenly distributed anti-slip bosses.

[0021] Furthermore, the spheroidizing bag body has an inner cavity; the inner wall of the inner cavity is provided with a high temperature resistant lining.

[0022] Furthermore, the package cover is provided with an infrared temperature sensor and an openable and closable inert gas connection channel.

[0023] Furthermore, a heat insulation layer is provided on the inner wall of the inner cavity of the probe protection cover.

[0024] The present invention also provides a method for improving the roundness of graphite in ductile iron, which uses a device for improving the roundness of graphite in ductile iron and further includes the following steps:

[0025] S1, molten iron pretreatment;

[0026] Controlling the C, Si, and S contents in the molten iron to achieve a C content of 3.6-3.8%, a Si content of 2.2-2.5%, and an S content of ≤0.015%; spraying a CaC2-based desulfurizer into the molten iron with a particle size of 0.2-0.5 mm and a flow rate of 8-12 kg / t; applying an axial static magnetic field to the electric furnace with a magnetic field strength of 0.3-0.5 T for 5-8 minutes;

[0027] S2. Spheroidizing treatment is performed using a device for improving the roundness of graphite in ductile iron;

[0028] The spheroidizing ladle body is hoisted and transferred to the spheroidizing ladle base; the spheroidizing ladle body is installed on the turntable; the ladle cover is raised to the highest position by the lifting device; then, a spheroidizing agent is laid on one side of the bottom of the inner cavity of the spheroidizing ladle body, wherein the spheroidizing agent is a composite spheroidizing agent with an Mg content of 5-7%, an RE content of 1-2%, and a Bi content of 0.02-0.05%; a layer of a primary inoculant is covered on the upper surface of the spheroidizing agent; the primary inoculant is a 0.5-0.8% silicon-barium inoculant;

[0029] Then the molten iron is poured into the nodulizing ladle; when the molten iron is two-thirds filled, a secondary inoculant is added to the molten iron through the inoculant adding device on the ladle cover; the secondary inoculant uses 0.1-0.2% silicon strontium powder;

[0030] After the molten iron is poured into the spheroidizing ladle, the ladle cover is lowered to cover the opening on the upper part of the spheroidizing ladle body through the lifting device; then, a tertiary inoculant is added to the molten iron through the inoculant adding device on the ladle cover. The tertiary inoculant uses a silicon-barium-calcium long-term inoculant; then the turntable is started to rotate, thereby driving the spheroidizing ladle body to rotate. After rotating for 30 to 60 seconds, the spheroidizing ladle body is braked by the brake device.

[0031] The beneficial effects of the present invention are as follows: the device for improving the roundness of graphite in ductile iron of the present invention is provided with a spheroidizing ladle base, and a turntable is provided on the spheroidizing ladle base. The turntable can realize the back and forth rotation of the spheroidizing ladle, and the spheroidizing ladle is stopped by providing a brake device. By rotating the spheroidizing ladle back and forth, the liquid in the spheroidizing ladle is shaken evenly under the action of inertia, thereby facilitating the uniform mixing of the inoculant and the molten iron, thereby ensuring the spheroidizing effect;

[0032] Secondly, the spheroidizing bag base and the spheroidizing bag body are designed to be separated, which makes it easier to lift and transport the spheroidizing bag;

[0033] Thirdly, a bag cover is provided on the spheroidization bag to facilitate sealed spheroidization during the spheroidization process, and further protection by introducing inert gas can effectively reduce air oxidation;

[0034] Thirdly, by arranging an inoculant adding device and a spectral probe on the spheroidizing ladle, it is convenient to realize real-time monitoring of elements in the molten iron in the spheroidizing ladle, further judge the spheroidizing effect, and thus facilitate the adjustment of the spheroidizing agent and inoculant dosage; and the entire spheroidizing process can be monitored, which is convenient for optimizing the spheroidizing process;

[0035] Furthermore, the bag cover is raised and lowered by a lifting device, which is implemented by a worm gear combined with a lead screw. The worm gear can achieve effective self-locking, and the lifting is controlled by rotating a manual turntable. Therefore, the operation is simple and the lifting position can be accurately controlled.

[0036] The present application also discloses a method for improving the roundness of graphite in ductile iron. Since the method adopts the device for improving the roundness of graphite in ductile iron described in the present application, the spheroidization effect can be improved, the roundness of graphite in subsequent castings can be ensured, and the product quality can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of an explosion of a device for improving the roundness of graphite in ductile iron according to an embodiment of the present invention;

[0038] Figure 2 is a three-dimensional diagram of a device for improving the roundness of graphite in ductile iron according to an embodiment of the present invention;

[0039] Figure 3 2. It is a front view of a device for improving the roundness of graphite in ductile iron according to an embodiment of the present invention;

[0040] Figure 4 is a side view of a device for improving the roundness of graphite in ductile iron according to an embodiment of the present invention;

[0041] Figure 5 This is a three-dimensional view of the device for improving the roundness of graphite in ductile iron according to an embodiment of the present invention, with the cover opened;

[0042] Figure 6 yes Figure 3 AA section view;

[0043] Figure 7 yes Figure 4 BB cross-sectional view;

[0044] Figure 8 yes Figure 6 A partial enlarged view of center C;

[0045] Figure 9 yes Figure 7 A partial enlarged view of middle D;

[0046] Figure 10 is a top view of the cover in an embodiment of the present invention;

[0047] Figure 11 is a perspective view of a cover according to an embodiment of the present invention;

[0048] Markings in the figure: 100-spheroidizing bag base, 200-spheroidizing bag body, 300-bag cover, 400-hanging rod, 500-beam. DETAILED DESCRIPTION

[0049] The present invention will be further described below with reference to the accompanying drawings and examples.

[0050] like Figures 1 to 10 As shown, the device for improving the roundness of graphite in ductile iron described in the present invention includes a spheroidizing ladle body 200, on which a hanger bracket is provided; a flip driving device 420 is provided at the lower end of the hanger bracket; specifically, the spheroidizing ladle body 200 has an inner cavity; the inner wall of the inner cavity is provided with a high-temperature resistant lining 210; the lining 210 is made of aluminum silicon carbide castable.

[0051] Specifically, the main function of the spheroidizing ladle body 200 is to accommodate molten iron, and the spheroidizing ladle body 200 can be made of cast iron. The height-to-diameter ratio of the spheroidizing ladle body 200 is 1.5:1.

[0052] The main function of the boom support is to lift the spheroidizing ladle, facilitating its transport and molten iron casting. The boom support can be a single-piece forging to reduce the risk of breakage. The boom support comprises two booms 400 , above which is a crossbeam 500 , and on which is a hook 510 .

[0053] The tilting drive device 420 uses a traditional worm gear reducer. It features a copper worm gear and a 45# steel quenched and tempered worm, with bidirectional reversibility to prevent "knocking." The worm gear reducer can be driven manually or electrically. Manual operation is used for loads ≤ 3 tons, while motor drive is used for loads ≥ 5 tons.

[0054] The device for improving the roundness of graphite in ductile iron also includes a spheroidizing ladle base 100, an industrial processor and a spectrum data processing module; a ladle cover 300 that can move up and down is provided above the spheroidizing ladle body 200.

[0055] A turntable 110 is provided on the ball-forming package base 100; the turntable 110 has a turntable 180; a limiting ring 130 is provided above the turntable 180; a support plate 120 is provided between the limiting ring 130 and the ball-forming package base 100; the ball-forming package body 200 is installed on the turntable 180, and a limiting wheel 440 matching the limiting ring 130 is provided on the boom bracket outside the ball-forming package body 200; a brake device is provided between the support plate 120 and the ball-forming package body 200.

[0056] The turntable 110 provided on the pelletizing bag base 100 facilitates the installation of the pelletizing bag body 200 thereon, while also enabling the rotation of the pelletizing bag. The turntable 110 utilizes a conventional horizontal turntable. Furthermore, a turntable 181 is provided on the turntable 180, separating the turntable 180 from the pelletizing bag body 200 to prevent damage to the turntable 180 from the pelletizing bag body. This also facilitates the replacement of turntables of different sizes for pelletizing bags, facilitating the installation and positioning of the pelletizing bag.

[0057] By providing a limiting ring 130 above the turntable 110, the pelletizing bag is prevented from being thrown off the turntable during rotation, thereby improving the stability of the pelletizing bag body 200 during rotation. Furthermore, the turntable 180 is provided with a mounting groove that matches the pelletizing bag body 200; the bottom of the mounting groove is provided with evenly distributed anti-slip bosses 181.

[0058] The main function of the brake device is to achieve braking. The brake device can be implemented in various ways, such as pneumatic braking. In order to facilitate operation, simplify the structure and reduce costs, the brake device specifically includes a curved brake pad 150 that matches the outer surface of the spheroidizing package body 200;

[0059] A horizontal fixing plate 121 is provided on the support plate 120; a pressure plate 170 is hinged on the horizontal fixing plate 121; the arc-shaped brake pad 150 has a sliding shaft 151; the sliding shaft 151 passes through the support plate 120; a roller 152 is provided at one end of the sliding shaft 151; an annular boss is provided below the roller; a spring 160 is provided between the annular boss and the support plate 120; the spring 160 is mounted on the sliding shaft 151; the upper end of the pressure plate 170 is in contact with the roller 152.

[0060] During use, when braking is required, one end of the pressure plate 170 is manually pulled, causing the other end to press the roller 152 and drive the sliding shaft 151, so that the arc-shaped brake pad 150 is in contact with the outer surface of the spheroidizing bag, thereby achieving a stop. After braking, the pressure plate 170 is released, and the pressure plate 170 returns to its original position under the action of the spring 160.

[0061] The boom bracket is provided with a lifting device that drives the baling cover 300 to move up and down; the baling cover 300 is provided with an inoculant adding device 310 and a telescopic device 330; the telescopic device 330 has a telescopic shaft 335 that passes through the baling cover 300. Specifically, the inoculant adding device 310 can be provided with a screw feeding device or a rotary feeding device. The screw feeding device can be a storage bin with a screw conveyor provided at the bottom of the storage bin. The rotary feeding device also includes a storage bin with a discharge port provided at the lower end. The discharge port is provided with a rotating wheel that seals the storage port. The rotating wheel is provided with grooves evenly distributed along the circumference.

[0062] The telescopic device 300 can be a variety of telescopic devices, such as an electric push rod. The lifting device in the technical solution described in this application includes a vertical screw rod 410 disposed on the inner side of the boom bracket and a horizontal shaft 435 disposed below the crossbeam 500; side ears 340 are disposed on both sides of the cover 300; the vertical screw rod 410 passes through the side ears 340; the vertical screw rod 340 and the side ears 340 are threadedly engaged; a turbine 411 is disposed at the upper end of the vertical screw rod 410; and the vertical screw rod 410 is connected to the horizontal shaft 435 by a worm gear transmission.

[0063] A driven wheel 434 is provided at one end of the transverse rotating shaft 435 ; a driving wheel 431 is provided at the lower end of the boom 400 ; the driving wheel 431 is connected to the driven wheel 434 via a chain 433 ; a manual turntable 432 is provided on the driving wheel 431 .

[0064] During use, when the cover 300 needs to be raised or lowered, the manual turntable 432 is manually rotated, which drives the driven wheel via a chain, and the driven wheel drives the horizontal shaft 435 to rotate. The horizontal shaft 435 is connected to the vertical screw rod 410 through a worm gear mechanism. Therefore, the horizontal shaft 435 drives the vertical screw rod 410 to rotate, and the vertical screw rod 410 drives the cover 300 to be raised or lowered.

[0065] The main function of the telescopic device 330 is to adjust the position of the lower end of the telescopic shaft 335 within the spheroidizing bag up and down, thereby facilitating adjustment of the position of the probe on the telescopic shaft 335. The telescopic device 330 can employ an electric push rod. To facilitate high-temperature resistance and simplify the structure, the telescopic device 330 further includes a drive motor and a support boss 331 disposed on the bag cover 300; a rotating boss 332 is disposed on the support boss 331; a rotating sleeve 333 is rotatably mounted on the rotating boss 332; a drive turbine 334 is disposed on the rotating shaft of the drive motor; the drive turbine 334 is connected to the rotating sleeve 333 by a worm gear transmission; the telescopic shaft 335 passes through the rotating sleeve 333, the rotating boss 332, and the support boss 331 in sequence, and the telescopic shaft 335 is threadedly engaged with the rotating sleeve 333.

[0066] In practical applications, the drive motor is simply started to rotate the drive turbine 334, which then drives the rotating sleeve 333 to rotate. The rotating sleeve 333 then drives the telescopic shaft 335 to move upward or downward. The direction of rotation of the motor is controlled to control the upward or downward movement of the telescopic shaft 335.

[0067] A high-temperature resistant probe protection cover 336 is provided at the lower end of the telescopic shaft 335 ; a spectrometer probe 338 and a laser ranging sensor 339 are provided in the probe protection cover 336 ; and a high-temperature resistant glass 3310 is provided at the lower end of the protection cover 336 .

[0068] The spectrometer probe 338 is electrically connected to the spectral data processing module; the spectral data processing module is used to analyze and process the spectral signal detected by the spectrometer probe to detect the content of magnesium, rare earth and sulfur elements in the molten iron; the industrial processor is used to control the amount of inoculant added by the inoculant adding device 310 according to the detected content of magnesium, rare earth, silicon, sulfur, aluminum, titanium and barium elements in the molten iron; and is used to control the telescopic length of the telescopic shaft 335 of the telescopic device 330.

[0069] The specific functions of the corresponding elements in molten iron are:

[0070] Magnesium is the primary nodulizer in ductile iron, transforming graphite from flakes into spheres, significantly improving the cast iron's strength, plasticity, and toughness. Residual content should be controlled between 0.03% and 0.06%. A lower content results in poor nodulization, while a higher content increases the tendency toward white cast iron. The synergistic use of magnesium and rare earth elements (RE) can counteract interference from sulfur and oxygen, improving nodulization stability.

[0071] Among them, rare earth has a dual role. First, the purification effect, strong desulfurization and deoxidation, generating high melting point rare earth sulfides / oxides (such as Ce2O3, La2S3), reducing pores and slag inclusions.

[0072] Second, it assists in spheroidization, neutralizes anti-spheroidizing elements (Pb, Bi, etc.), and enhances the spheroidization effect of magnesium; this is especially critical in high-sulfur molten iron.

[0073] Silicon (Si) acts as a strong graphitizing element, promoting graphite precipitation, refining graphite nodules, increasing ferrite content, and improving plasticity and toughness. Furthermore, it can reduce the solidification range of molten iron and reduce shrinkage defects.

[0074] Among them, the role of barium is a long-term inoculant component, which delays the decline of inoculum, refines the eutectic clusters, and improves the distribution of graphite.

[0075] Sulfur consumes spheroidizing agents (Mg, RE), leading to poor or declining spheroidization (1 part sulfur consumes 0.7 parts magnesium). This forms MnS inclusions, which degrade mechanical properties. The sulfur content of base iron must be ≤0.02% (ductile iron) or ≤0.06%.

[0076] Among them, the role of aluminum is to promote subcutaneous pores (generating AlN with nitrogen) and increase oxide inclusions; the content needs to be <0.03%.

[0077] The role of titanium is that a trace amount (<0.03%) can refine the grains; an excessive amount will form TiC hard spots, interfere with spheroidization (compete with Mg / RE), and reduce cutting performance.

[0078] The spectrometer probe 338 utilizes the detection probe of a conventional handheld spectrometer, and the data processing module utilizes the data processing module of a conventional handheld spectrometer. The laser ranging sensor 339 primarily detects the distance between the probe and the molten iron surface in real time, thereby controlling the lowering distance of the probe protective cover 336 by adjusting the extension length of the telescopic shaft 335.

[0079] The industrial processor utilizes a PLC programmable logic controller, specifically a Siemens S7-1500 controller. During the control process, the distance detected by the laser rangefinder 339 is used to control the extension and retraction length of the telescopic device 330, thereby maintaining a certain height above the molten iron surface for the protective cover 336. The specific height can be set according to actual needs. The data processing module analyzes the magnesium, rare earth, silicon, sulfur, aluminum, titanium, and barium content in the molten iron to control the amount of inoculant added. Specifically, if the molten iron contains rare earth or barium, the inoculant degradation can be slowed down, and the amount of inoculant added can be reduced. If the silicon content is high, the amount of inoculant added is reduced. For molten iron with high sulfur content, feedback is provided to select an inoculant containing calcium or strontium.

[0080] Secondly, the industrial processor can also provide feedback based on the detected element content, outputting data that can be displayed on an LED screen. The type of inoculant can be adjusted in real time based on the detected concentrations of key elements in the molten iron. Specifically, for molten iron with high sulfur content, such as gray cast iron, inoculants containing calcium and strontium should be used. Aluminum and titanium increase the surface tension of the molten iron and can easily cause subcutaneous pores. When the aluminum content exceeds 0.01% or the titanium content is too high, the use of aluminum-containing inoculants should be reduced, and low-aluminum ferrosilicon or barium-containing inoculants should be preferred. The specific inoculant addition amount corresponding to the content of each element can be set based on the actual production conditions and the type of molten iron being cast.

[0081] In a feasible embodiment, in order to avoid severe friction between the boom bracket and the limiting ring 130 during the rotation of the spheroidizing package body 200, an annular mounting groove is further provided on the limiting ring 130; and a thrust bearing 140 is provided in the annular mounting groove.

[0082] In a feasible embodiment, in order to prevent the spheroidizing bag from slipping on the turntable during rotation, the turntable 180 is further provided with a mounting groove matching the spheroidizing bag body 200; and the bottom of the mounting groove is provided with evenly distributed anti-slip bosses 181.

[0083] In a feasible embodiment, in order to detect the molten iron temperature in real time and facilitate the introduction of inert gas during the spheroidization process to achieve oxidation-free spheroidization, the cover 300 is further provided with an infrared temperature sensor 320 and an openable and closable inert gas connection channel 350.

[0084] In a feasible embodiment, in order to prevent high temperature from affecting the service life of the probe in the probe protection cover 336 , a heat insulation layer 337 is further provided on the inner wall of the inner cavity of the probe protection cover 336 .

[0085] The present invention also discloses a method for improving the roundness of graphite in ductile iron, which uses the device for improving the roundness of graphite in ductile iron;

[0086] The following steps are involved:

[0087] 1. Pretreatment of molten iron;

[0088] Control the C, Si and S contents in the molten iron; make C 3.6-3.8%, Si 2.2-2.5%, and S ≤ 0.015%; spray a CaC2-based desulfurizer into the molten iron, with a particle size of 0.2-0.5 mm and a flow rate of 8-12 kg / t; apply an axial static magnetic field to the electric furnace, with a magnetic field strength of 0.3-0.5 T and a duration of 5-8 minutes.

[0089] 2. Use a device to improve the roundness of graphite in ductile iron for spheroidizing treatment;

[0090] 2.1 The spheroidizing bag body 200 is hoisted and transported to the spheroidizing bag base 100 ; the spheroidizing bag body 200 is installed on the turntable 180 .

[0091] 2.2 Raise the cladding cover 300 to the highest position by means of a lifting device; then, lay a spheroidizing agent on one side of the bottom of the inner cavity of the spheroidizing cladding body 200. The spheroidizing agent is a composite spheroidizing agent with a Mg content of 5-7%, a RE content of 1-2%, and a Bi content of 0.02-0.05%.

[0092] Specifically, the spheroidizing agent is laid in layers, the bottom layer is MgFeSi alloy with a particle size of 2-4mm; the middle layer is RE-Mg composite cored wire with a diameter of 9mm; and the top layer is nano-silicon carbide coating with a thickness of 50-100nm.

[0093] Then, a layer of primary inoculant is covered on the surface of the spheroidizer; the primary inoculant is a 0.5-0.8% silicon-barium inoculant.

[0094] 2.3 Then the molten iron is injected into the spheroidizing ladle; when the molten iron is injected to two-thirds, a secondary inoculant is added to the molten iron through the inoculant adding device 310 on the ladle cover 300; the secondary inoculant uses 0.1-0.2% silicon strontium powder.

[0095] 3. After the molten iron is poured into the spheroidizing ladle, the ladle cover 300 is lowered by the lifting device to cover the opening on the upper part of the spheroidizing ladle body 200. Then, a tertiary inoculant is added to the molten iron through the inoculant adding device 310 on the ladle cover 300. The tertiary inoculant uses a silicon-barium-calcium long-term inoculant. Then, the turntable 110 is started to rotate forward 60 to 90 degrees, then reverse 60 to 90 degrees, and rotate back and forth, thereby driving the spheroidizing ladle body 200 to rotate back and forth. After rotating for 30 to 60 seconds, the spheroidizing ladle body 200 is braked by the brake device.

Claims

1. A device for improving the roundness of graphite in ductile iron, comprising a spheroidizing bag body (200), wherein a suspension rod support is provided on the spheroidizing bag body (200); and a turning drive device (420) is provided at the lower end of the suspension rod support; Its characteristics are: It also includes a spheroidizing bag base (100), an industrial processor, and a spectrum data processing module; a bag cover (300) that can move up and down is provided above the spheroidizing bag body (200); A turntable (110) is provided on the spheroidizing bag base (100); the turntable (110) has a turntable (180); a limiting ring (130) is provided above the turntable (180); a support plate (120) is provided between the limiting ring (130) and the spheroidizing bag base (100); the spheroidizing bag body (200) is mounted on the turntable (180), and a limiting wheel (440) matching the limiting ring (130) is provided on a boom bracket outside the spheroidizing bag body (200); a brake device is provided between the support plate (120) and the spheroidizing bag body (200); The boom bracket is provided with a lifting device for driving the bag cover (300) to move up and down; the bag cover (300) is provided with an inoculant adding device (310) and a telescopic device (330); The telescopic device (330) has a telescopic shaft (335) passing through the cover (300); a high-temperature-resistant probe protection cover (336) is provided at the lower end of the telescopic shaft (335); a spectrometer probe (338) and a laser distance sensor (339) are provided in the probe protection cover (336); and a high-temperature-resistant glass (3310) is provided at the lower end of the protection cover (336); The spectrometer probe (338) is electrically connected to a spectrum data processing module; the spectrum data processing module is used to analyze and process the spectrum signal detected by the spectrometer probe to detect the carbon, silicon and sulfur content in the molten iron; The industrial processor is used to control the amount of inoculant added by the inoculant adding device (310) according to the detected content of magnesium, rare earth, silicon, sulfur, aluminum, titanium and barium elements in the molten iron; and to control the telescopic length of the telescopic shaft (335) of the telescopic device (330).

2. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: The braking device comprises a curved brake pad (150) matched with the outer surface of the spheroidizing package body (200); A horizontal fixing plate (121) is provided on the support plate (120); a pressure plate (170) is hinged on the horizontal fixing plate (121); the arc-shaped brake pad (150) has a sliding shaft (151); the sliding shaft (151) passes through the support plate (120); a roller (152) is provided at one end of the sliding shaft (151); an annular boss is provided below the roller; a spring (160) is provided between the annular boss and the support plate (120); the spring (160) is mounted on the sliding shaft (151); the upper end of the pressure plate (170) contacts the roller (152).

3. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: An annular installation groove is provided on the limiting ring (130); a thrust bearing (140) is provided in the annular installation groove.

4. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: The boom support comprises two booms (400); a crossbeam (500) is provided above the two booms (400); and a hook (510) is provided on the crossbeam (500); The lifting device comprises a vertical screw rod (410) arranged on the inner side of the boom bracket and a horizontal rotating shaft (435) arranged below the crossbeam (500); side ears (340) are arranged on both sides of the cover (300); the vertical screw rod (410) passes through the side ears (340); the vertical screw rod (340) and the side ears (340) are threadedly engaged; a turbine (411) is arranged on the upper end of the vertical screw rod (410); the vertical screw rod (410) and the horizontal rotating shaft (435) are connected to each other by a worm gear transmission; A driven wheel (434) is provided at one end of the transverse rotating shaft (435); a driving wheel (431) is provided at the lower end of the boom (400); the driving wheel (431) is connected to the driven wheel (434) via a chain (433); and a manual turntable (432) is provided on the driving wheel (431).

5. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: The telescopic device (330) includes a driving motor and a supporting boss (331) provided on the cover (300); a rotating boss (332) is provided on the supporting boss (331); a rotating sleeve (333) is rotatably mounted on the rotating boss (332); a driving turbine (334) is provided on the rotating shaft of the driving motor; the driving turbine (334) is connected to the rotating sleeve (333) by a worm gear transmission; the telescopic shaft (335) passes through the rotating sleeve (333), the rotating boss (332) and the supporting boss (331) in sequence, and the telescopic shaft (335) is threadedly engaged with the rotating sleeve (333).

6. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: The turntable (180) is provided with a mounting groove matching the spheroidizing bag body (200); and the bottom of the mounting groove is provided with evenly distributed anti-slip bosses (181).

7. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: The spheroidizing bag body (200) has an inner cavity; the inner wall of the inner cavity is provided with a high-temperature resistant lining (210).

8. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: The package cover (300) is provided with an infrared temperature sensor (320) and an openable and closable inert gas connection channel (350).

9. The device for improving the roundness of graphite in ductile iron according to claim 1, wherein: A heat insulation layer (337) is provided on the inner wall of the inner cavity of the probe protection cover (336).

10. A method for improving the roundness of graphite in ductile iron, characterized by: The device for improving the roundness of graphite in ductile iron according to any one of claims 1 to 9 further comprises the following steps: S1, molten iron pretreatment; Controlling the C, Si, and S contents in the molten iron to achieve a C content of 3.6-3.8%, a Si content of 2.2-2.5%, and an S content of ≤0.015%; spraying a CaC2-based desulfurizer into the molten iron with a particle size of 0.2-0.5 mm and a flow rate of 8-12 kg / t; applying an axial static magnetic field to the electric furnace with a magnetic field strength of 0.3-0.5 T for 5-8 minutes; S2. Spheroidizing treatment is performed using a device for improving the roundness of graphite in ductile iron; The spheroidizing bag body (200) is hoisted and transferred to the spheroidizing bag base (100); the spheroidizing bag body (200) is installed on the turntable (180); the bag cover (300) is raised to the highest position by a lifting device; then, a spheroidizing agent is laid on one side of the bottom of the inner cavity of the spheroidizing bag body (200), wherein the spheroidizing agent is a composite spheroidizing agent, and the spheroidizing agent has an Mg content of 5-7%, an RE content of 1-2%, and a Bi content of 0.02-0.05%; a layer of a primary inoculant is covered on the upper surface of the spheroidizing agent; the primary inoculant is a 0.5-0.8% silicon-barium inoculant; Then, the molten iron is injected into the spheroidizing ladle; when the molten iron is injected to two-thirds, a secondary inoculant is added to the molten iron through the inoculant adding device (310) on the ladle cover (300); the secondary inoculant is 0.1-0.2% silicon strontium powder; After the molten iron is injected into the spheroidizing ladle, the ladle cover (300) is lowered to cover the opening on the upper part of the spheroidizing ladle body (200) by a lifting device; then, a tertiary inoculant is added to the molten iron by an inoculant adding device (310) on the ladle cover (300), wherein the tertiary inoculant is a silicon-barium-calcium long-term inoculant; then, the turntable (110) is started to rotate forward 60 to 90 degrees, and then reverse 60 to 90 degrees, and rotate back and forth, thereby driving the spheroidizing ladle body (200) to rotate back and forth. After rotating for 30 to 60 seconds, the spheroidizing ladle body (200) is braked by a brake device.

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