Plug-in treatment device for improving internal quality in casting and forging solidification process

Abstract

The utility model discloses a plug-in processing device for improving internal quality in a casting and forging solidification process, which comprises an ingot mold, a melt is arranged in the ingot mold, a riser cover is buckled on the top of the ingot mold, a support structure is arranged on one side of the ingot mold, an electrode structure is mounted on the support structure, and the electrode structure penetrates through the riser cover to be inserted into the melt. The plug-in processing device for improving the internal quality in the solidification process of the casting and forging pieces relates to the technical field of electromagnetic processes of materials, has obvious effects on different sizes of cast ingots and is wide in application range, the weight of the cast ingots is from hundreds of grams to hundreds of tons, and the production efficiency of the cast ingots is improved. The method can be applied to a 600t cast ingot solidification process to the maximum extent, and from an existing theory, the solidification control technology mainly has the effects of an electric transmission effect, a Joule heat effect, a Peltier effect, a Seebeck effect, an electromagnetic force effect, a magnetostrictive effect, an inoculation modification effect and the like through current in the metal solidification process.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic processes of materials, and particularly relates to a plug-in processing device for improving the internal quality during the solidification process of castings and forgings. Background Technique

[0002] Casting is the basic process and technology of the machinery industry, and is an important process technology indispensable in social production and life. It is widely used in various fields such as machinery manufacturing, ocean, aerospace, chemical industry, construction, transportation, and social life. The material requirements of modern technical equipment and key projects are becoming more and more centralized and large-scale. Many key equipment requires advanced die casting processes, especially the need to improve the quality and performance of ingots. During the solidification process of large ingots, due to volume shrinkage, depressions will be generated at the top of the ingot when the remaining melt compensates for it. This situation becomes more serious as the volume of the ingot increases. Moreover, during the solidification process, internal defects are likely to occur due to untimely feeding. Especially for large ingots, the high-temperature molten metal during pouring and solidification reaches hundreds of tons, and the solidification time is long. There is a large difference in the cooling rate between different regions of the ingot during the solidification process. Therefore, non-uniformity problems such as uneven structure, macrosegregation, shrinkage porosity / porosity, hot cracking, and impurity enrichment in large ingots are very prominent.

[0003] More and more scholars have noticed that the technology of applying an external field during the solidification process can control the material structure and properties and change the internal structure of the ingot. It is found that by applying external force to control the internal flow, heat transfer, and mass transfer processes of the metal melt during the solidification forming process, the solidification structure can be changed. Currently, it is mainly achieved by controlling the cooling rate, introducing external force through vibration or stirring to accelerate the internal convection of the melt and enhance the heat exchange with the outside, and uniforming the temperature inside the molten steel to refine the solidification structure, thereby making the solidification structure refined.

[0004] Currently, the relevant solidification control technologies mainly include: mechanical stirring, electromagnetic stirring, electric field, ultrasonic sound field, and microgravity field, etc. Applying an external field during the solidification process of the ingot can improve the internal mass transfer and heat transfer conditions. Traditional mechanical stirring generates an unstable liquid surface and brings in gas, which is easy to form defects such as pores. Insufficient stirring leads to uneven elements inside the ingot; applying external force during later processing and forging can also improve the central quality of the billet, such as the soft reduction technology; during the solidification process of large steel ingots, the hydrostatic pressure of the molten steel is large. If a strong stirring force is added, it will affect the service life of the stirring equipment and the ingot mold.

[0005] The non-contact stirring with an external magnetic field does not introduce foreign inclusions. Meanwhile, the molten steel is purified during the stirring process. However, if the stirring intensity is too high, vortices will be generated at the center of the liquid surface, and the centrifugal force will strongly scour the meniscus of the molten metal and the inner wall of the mold, easily entraining the protective slag and other impurities on the inner wall into the molten steel to form inclusion defects and cause new quality problems. Electromagnetic stirring is also prone to segregation, which limits the development space of electromagnetic stirring. Ultrasonic treatment can improve the quality of ingots, but for alloys with high melting points, such as the tool head introduced into the molten steel, it will melt during the ultrasonic vibration process, polluting the molten steel and reducing the vibration effect at the same time. Researchers have been seeking more suitable treatment methods. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a plug-in treatment device for improving the internal quality during the solidification process of castings and forgings, which solves the problems of certain limitations of existing ingot molds and stirring equipment.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: A plug-in treatment method for improving the internal quality during the solidification process of castings and forgings includes the following steps:

[0008] (1) First, pre-adjust the equipment to a reasonable position, connect the power supply to the lifting system and turn it on, adjust and calibrate the position of the electrode, mark the descending height and the position of the equipment, raise the equipment to the original position, move the equipment to the edge, and ensure that it does not affect the casting and filling of the mold.

[0009] (2) Conduct filling or casting of the mold. If an intermediate frequency induction furnace is used, there is a process of melting the melt and refining and degassing.

[0010] (3) After the molten steel is filled, supply power to the electrode by the DC power supply, adjust the position of the electrode and insert it into a certain position inside the melt for stirring. After a period of time, pull out the electrode using the lifting system, raise the electrode to the original position, turn off the power supply of the electrode, cover the surface of the molten steel with protective slag, and lay a layer of heat insulation cotton above the protective slag. Wait for the ingot to cool and solidify.

[0011] (4) Transfer the equipment to a safe position and turn off the power supply of the electrode lifting device.

[0012] Preferably, the liftable range of the electrode lifting device is 0 - 700 mm, and the working voltage is 220 V;

[0013] The depth of the electrode inserted into the molten liquid surface is 20 mm - 500 mm;

[0014] The material of the electrode is copper or graphite;

[0015] The current intensity range is between 0 A and 6000 A. The current is direct current, alternating current, and pulsed current, and the current frequency is less than 1000 kHz;

[0016] The working voltage is less than 36V, and the power supply working voltage is 380V.

[0017] Preferably, it includes an ingot mold, there is a melt inside the ingot mold, a riser cover is buckled on the top of the ingot mold, a support structure is arranged on one side of the ingot mold, an electrode structure is installed on the support structure, the electrode structure penetrates through the riser cover and inserts into the melt, a heating and heat preservation device is wrapped outside the ingot mold, and a temperature sensor is installed outside the riser cover.

[0018] Preferably, the support structure includes a moving base, the moving base is placed on one side of the ingot mold, a pair of support rods are arranged in parallel on the moving base, a lifter is installed between the pair of support rods, a lifting shaft is installed on the telescopic end of the lifter, and a cross beam is installed at the top of the lifting shaft, and the cross beam is connected to the electrode structure.

[0019] Preferably, the electrode structure includes a power supply arranged on one side of the support structure, an electrode system is arranged on the support structure, the electrode system is electrically connected to the power supply through a cable, and the electrode system penetrates through the riser cover and inserts into the melt.

[0020] Preferably, the electrode system is a three-phase electrode composed of three independent electrodes or a parallel electrode composed of two independent electrodes. The independent electrodes in the three-phase electrode or the parallel electrode are respectively electrically connected to the power supply through cables. The independent electrodes are fixedly connected to the support structure, and the three-phase electrode or the parallel electrode are all inserted into the melt.

[0021] Preferably, the electrode system includes a single electrode and a ring electrode. The ring electrode surrounds the outside of the single electrode. The single electrode and the ring electrode are respectively electrically connected to the power supply through the cable. The ring electrode and the single electrode are respectively fixedly connected to the support structure. The ring electrode and the single electrode respectively penetrate through the riser cover and insert into the melt.

[0022] Beneficial effects

[0023] The utility model provides a plug-in processing device for improving the internal quality during the solidification process of castings. It has the following beneficial effects: This plug-in processing device for improving the internal quality during the solidification process of castings has obvious effects on different ingot sizes and has a wide application range. The ingot ranges from a few hundred grams to hundreds of tons, and it can be applied to the solidification process of a 600t ingot at most. From the existing theory, the effects generated by the current during the metal solidification process in this solidification control technology mainly include electrotransport effect, Joule heat effect, Peltier effect, Seebeck effect, skin effect, electromagnetic force effect, magnetostrictive effect, and inoculation and modification effect, etc.

[0024] The inspiration for using Lorentz force generated by current through the inserted electrode to stir the melt comes from the stir casting method. The difference is that under the action of Lorentz force, the mass transfer and heat transfer conditions inside the melt are improved, and problems such as gas inclusions in the alloy are effectively and stably discharged; the metal melt will also generate Joule heat effect and thermoelectric effect with the inserted position, heat preservation and heating are carried out at the position where the melt finally solidifies, and the stirring action and Joule heat effect act simultaneously to provide more feeding channels for the solidification process, enhance the feeding effect of the molten metal, and significantly reduce shrinkage porosity. The current changes the growth mode of dendritic structure and the morphology of carbides. Under the action of direct current, the solidification structure is refined, causing changes in the growth of the solidification structure and the distribution and morphology of the second phase. Brief Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the plug-in treatment device for improving the internal quality during the solidification process of castings and forgings.

[0026] Figure 2 For the morphology of ingots: (a) Ingot under natural solidification, (b) Ingot treated with current, (c) Schematic cross-sectional view of two groups of ingots (a) and (b).

[0027] Figure 3 It is a schematic diagram of the principle of the present invention.

[0028] In the figure: 1, ingot mold; 2, melt; 3, heating and heat preservation equipment; 4, riser cover; 5, elevator; 6, moving base; 7, power supply; 8, cable; 9, cross beam; 10, support rod; 11, lifting shaft; 12, electrode system; 13, temperature sensor. Specific Embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Through those skilled in the art, all electrical components in this case are connected to their adapted power supplies through wires, and a suitable controller should be selected according to the actual situation to meet the control requirements. For the specific connection and control sequence, reference should be made to the working principle below, and the electrical connection should be completed according to the sequential working order between electrical components. The detailed connection means are well-known techniques in the art. The following mainly introduces the working principle and process, and will not explain the electrical control.

[0031] Please refer to Figures 1 - 3, the present utility model provides a technical solution: As shown in the figure, in the three systems of the present utility model, the ingot melting and casting device can be adjusted according to actual needs; the lift range of the electrode lifting device is 0 - 700 mm, and the working voltage is 220V; in the electrode DC power supply system, the electrode spacing, diameter, and length are configured according to experimental needs. There are three types of electrodes: parallel electrodes, annular electrodes, and three-phase electrode (AC) current. The working voltage of the DC power supply is 36V, the output current is 0 - 6000A, the working voltage is 380V / 400V, and the frequency is less than 100HZ. The present utility model has a wide range of applications. The ingots range from a few hundred grams to hundreds of tons, and the maximum can be applied to the solidification process of 600t ingots. It can be applied to the solidification processes of various different alloys.

[0032] The following embodiments are implemented on the premise of the technical solution of the present utility model, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present utility model is not limited to the following embodiments. The methods used in the following embodiments are all conventional methods unless otherwise specified.

[0033]

Embodiment 1

[0034] For the aluminum-silicon ingot solidification experiment, a 270g 7% aluminum-silicon alloy ingot was placed in a crucible, and the heating system was turned on for melting. The temperature was raised to 690°C, and the DC power supply was turned on and energized. The current intensity was between 5A and 15A. The parallel double electrode (Φ10mm) lifting device was started to insert the electrode into the melt to a certain depth, and the power was continuously supplied for 5 minutes until the ingot cooled. Test results: From the solidification morphology, the structure was refined to varying degrees after being strengthened by the current. Within a certain range, the greater the current intensity, the higher the refinement degree of the ingot. At the same time, the hardness and hardness uniformity of the alloy were improved.

[0035]

Embodiment 2

[0036] In this embodiment, 35CrMoA steel was selected for the ingot solidification experiment, and a 20kg steel ingot was melted. Raw material preparation: Graphite electrodes with a diameter of Φ20mm, and preliminary preparation work was carried out with an intermediate frequency steelmaking furnace. Magnesium sand and heat insulation lining were laid inside and the coil was covered. After the sand mold in the furnace solidified, a mold crucible (520mm deep) was placed, steel bars were placed in the crucible, and it was baked at a low temperature to remove moisture to avoid splashing of the molten steel during the steelmaking process. The intermediate frequency steelmaking furnace was started to melt the steel bars. After the steel bars in the crucible were completely melted, the DC power supply was turned on. The parallel double electrodes were inserted into the steel liquid surface using the lifting device, and the power was supplied at 150A for 10 minutes, then stopped for 8 minutes, and then supplied with 150A for 5 minutes, and the current was increased to 350A for 3 minutes. The power supply was turned off, the electrodes were pulled out, and finally protective slag was covered. After the ingot cooled, it was demolded. Test results: As Figure 2Observation: Under the action of double - electrode direct current, the shrinkage porosity and looseness of the ingot are reduced, and the surface scale and pores are decreased. After inspection, the degree of element segregation in the internal solidification structure is reduced, the composition is more uniform, and the comprehensive quality is significantly improved.

[0037]

Example 3

[0038] In this example, a 38t ingot from a certain steel plant was selected for the plug - in experiment during the solidification process, with parallel electrodes of Φ50mm. The molten steel was filled from the bottom, with a filling speed of 33.95 Kg / s and a filling time of 20 minutes. After the molten steel was filled, the electrodes were inserted into the riser cover of the reserved gap. The direct - current power supply first passed a current of 1000A, and the parallel electrodes were inserted into the molten steel. During the insertion process, the molten steel would splash. After the molten - steel surface became stable, the current was increased to 2000A. After keeping the power on for a period of time, the electrodes were pulled out and covered with flux. After the ingot cooled and was demolded. It can be observed from the simulation results that during the solidification process, the Lorentz force generated by the large current has a stirring effect on the internal flow field of the molten steel during the solidification process. The acceleration of the internal flow field improves the heat transfer between the inside and outside of the ingot, improves the internal heat - transfer conditions, provides more feeding channels, and is conducive to providing a better feeding effect during the solidification process of the molten steel.

[0039] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0040] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An electric plugging treatment device for improving the internal quality of castings and forgings during solidification, characterized in that , comprising an ingot mold (1), wherein a melt (2) is arranged in the ingot mold (1), a riser cover (4) is buckled on the top of the ingot mold (1), a support structure is provided on one side of the ingot mold (1), an electrode structure is installed on the support structure, the electrode structure penetrates the riser cover (4) and is inserted into the melt (2), the outer side of the ingot mold (1) is wrapped with a heating and heat preservation device (3), and the outer side of the riser cover (4) is installed with a temperature sensor (13).

2. The device for improving the internal quality of castings and forgings during solidification according to claim 1 is characterized in that The support structure comprises a movable base (6), the movable base (6) being arranged on one side of the ingot mold (1), a pair of support rods (10) being arranged in parallel on the movable base (6), a lift (5) being installed between the pair of support rods (10), a lift shaft (11) being installed on the telescopic end of the lift (5), a crossbeam (9) being installed on the top end of the lift shaft (11), and the crossbeam (9) being connected to the electrode structure.

3. The device for improving the internal quality of castings and forgings during solidification according to claim 1, characterized in that The electrode structure comprises a power source (7) arranged on one side of a support structure, an electrode system (12) is arranged on the support structure, the electrode system (12) is electrically connected to the power source (7) via a cable (8), and the electrode system (12) penetrates the riser cover (4) and is inserted into the melt (2).

4. The device for improving the internal quality of castings and forgings during solidification according to claim 3 is characterized in that The electrode system (12) is a three-phase electrode composed of three independent electrodes or a parallel electrode composed of two independent electrodes. The independent electrodes in the three-phase electrode or the parallel electrode are electrically connected to the power supply (7) through cables (8), and the independent electrodes are fixedly connected to the support structure. The three-phase electrode or the parallel electrode are inserted into the melt (2).

5. The device for improving the internal quality of castings and forgings during solidification according to claim 3, characterized in that The electrode system (12) includes a single electrode and an annular electrode, wherein the annular electrode surrounds the outer side of the single electrode, the single electrode and the annular electrode are electrically connected to the power supply (7) via the cable (8), the annular electrode and the single electrode are fixedly connected to the support structure, and the annular electrode and the single electrode are respectively inserted into the melt (2) through the riser cover (4).

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