CN114749634A - A differential pressure casting crucible furnace - Google Patents

Abstract

The invention discloses a crucible furnace for differential pressure casting, comprising a crucible, a heating element and an electromagnetic coil, the electromagnetic coil is arranged outside the crucible, the electromagnetic coil is connected with an external power source, the electromagnetic coil can generate a magnetic field, and the crucible is located in the magnetic field generated by the electromagnetic coil. When working, the heating element heats the crucible, and then achieves the purpose of heating and insulating the aluminum alloy melt in the crucible, so that the aluminum alloy melt is kept in a molten state; an electromagnetic coil is arranged outside the crucible, and the electromagnetic coil is connected to an external power supply, and the electromagnetic The energization of the coil can generate a magnetic field, thereby applying electromagnetic treatment to the melt in the crucible, affecting the energy system in the melt, compensating for the energy required to form critical nuclei inside the melt, and reducing the nucleation activation required for the nucleation process. It can promote the melt to overcome the nucleation barrier, thereby increasing the number of primary crystal nuclei in the melt, and improving the nucleation rate in the melt, thereby improving the final casting to grain refinement and improving the performance of the finished casting.

Description

A differential pressure casting crucible furnace

technical field

The invention relates to the technical field of metallurgical equipment and its peripheral supporting facilities, in particular to a differential pressure casting crucible furnace.

Background technique

Differential pressure casting, also known as "reverse pressure casting", is a process in which metal melt is filled into a mold with a certain pressure in advance under the action of pressure difference, and solidified to obtain castings. Under the action of high solidification and holding pressure, the metal melt can pass through the narrow intergranular gap, and the isolated liquid phase region can be well fed. It is very suitable for the production of castings with complex contours with high air tightness, and the contours of the castings are clear. , the size is accurate. During the differential pressure casting process, the pressure in the crucible is greater than the pressure in the mold. Under the action of the pressure difference, the aluminum alloy liquid in the crucible fills the mold through the liquid riser. During the sequential solidification process, the aluminum alloy liquid in the crucible fills the mold. The casting is continuously fed and solidified under higher pressure.

Obtaining uniform and fine equiaxed crystals can significantly reduce casting defects and improve the mechanical properties of materials. The solidification structure is usually controlled by changing the phase structure and crystal morphology, wherein the phase structure is directly affected by the alloy composition, while the crystal morphology and grain size are determined by the solidification process. The increase of the degree of undercooling in the undercooled melt can significantly increase the solid-liquid phase Gibbs free energy difference and reduce the critical nucleation work. This system energy intervention can achieve the purpose of grain refinement. For example, rapid solidification technology, although it can obtain fine grain size and even nanocrystalline, it cannot prepare large-sized ingots and is difficult to achieve industrial production. Heterogeneous nucleation makes it easier to achieve grain refinement of large cross-section ingots. By adding a modifier to suppress the grain growth to obtain a refined structure, the nucleation of the liquid metal on the surface of the solid phase particle can greatly reduce the surface energy, but it will cause pollution to the material itself. For example, the addition of Al-5Ti-B to the aluminum alloy can achieve significant grain refinement, but the formation of TiB2 in the metal will impair the properties of the final product. The above methods all have their own limitations, and it is difficult to achieve industrialization.

With the continuous advancement of the lightweight process of automobiles, the standard of parts and components has gradually increased, and the differential cast aluminum alloy products have encountered the bottleneck that the mechanical properties and mold filling performance are difficult to improve due to the uncontrollable solidification and homogenization process.

In the process of aluminum alloy differential pressure casting, the main function of the crucible furnace is to provide aluminum alloy melt for the differential pressure casting equipment. The differential pressure casting crucible furnace in the prior art is only a simple furnace, and the heat is transferred to the charge through the crucible, which cannot be Processing of the melt is achieved to refine the casting grains.

Therefore, how to change the current situation in the prior art that the differential pressure casting equipment for industrial production cannot achieve grain refinement during operation, resulting in poor product performance, has become an urgent problem for those skilled in the art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a differential pressure casting crucible furnace to solve the above-mentioned problems in the prior art, improve the melt nucleation rate, and promote the grain refinement of the casting, thereby improving the quality and performance of the casting.

To achieve the above object, the present invention provides the following solutions: the present invention provides a differential pressure casting crucible furnace, comprising:

a crucible capable of accommodating an aluminum alloy melt;

a heating element, the heating element is arranged outside the crucible, and the heating element can use the crucible to heat the aluminum alloy melt;

an electromagnetic coil, the electromagnetic coil is arranged outside the crucible and the heating element, the electromagnetic coil is connected to an external controllable electromagnetic energy source, the electromagnetic coil can generate a magnetic field, and the crucible is located in the electromagnetic coil to generate within the magnetic field.

Preferably, the electromagnetic coil is connected with a controllable electromagnetic energy power source, and the controllable electromagnetic energy power source can control the magnetic field generated by the electromagnetic coil.

Preferably, the electromagnetic coil is arranged outside the crucible in a spiral around the axis of the crucible.

Preferably, the electromagnetic coil is sleeved on the outside of the heating element, and a heat insulating layer is provided between the heating element and the electromagnetic coil, and the heat insulating layer is made of nano heat insulating material.

Preferably, the heating element is a heating rod, the heating rods are uniformly distributed around the axis of the crucible, and the heating rods are connected to an external power source.

Preferably, the outside of the electromagnetic coil is further provided with a refractory layer, the refractory layer is sleeved on the outside of the electromagnetic coil, and the refractory layer is made of refractory bricks.

Preferably, the electromagnetic coil is connected to the inner wall of the refractory layer.

Preferably, an outer casing of the crucible is sheathed, and the heating element and the electromagnetic coil are both arranged in the casing.

Preferably, a support frame is provided at the bottom of the electromagnetic coil, and the support frame is connected with the inner wall of the housing.

Preferably, the electromagnetic coil can generate a magnetic field when working, the duty ratio of the electromagnetic energy is 10%-70%, the output current of the electromagnetic energy is 100A-200A, the output frequency is 10Hz-100Hz, and the strength of the magnetic field in the crucible is ≥10mT.

Compared with the prior art, the present invention achieves the following technical effects: the differential pressure casting crucible furnace of the present invention, during operation, the heating element heats the crucible, and then realizes the purpose of heating and insulating the aluminum alloy melt in the crucible, so that the aluminum alloy is heated and kept warm. The melt is kept in a molten state; more importantly, in the present invention, an electromagnetic coil is arranged outside the crucible, and the electromagnetic coil is connected to an external controllable electromagnetic energy power source. The electromagnetic coil can be energized to generate a magnetic field, thereby applying electromagnetic treatment to the melt in the crucible. It affects the energy system in the melt, compensates the energy required for the formation of critical crystal nuclei in the melt, reduces the nucleation activation energy required for the nucleation process, and promotes the melt to overcome the nucleation barrier, thereby increasing the primary crystals in the melt. The number of nuclei increases the nucleation rate in the melt, thereby refining the grain of the final casting, improving the uniformity of the microstructure of the casting, and then improving the performance of the finished casting.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the structural representation of the differential pressure casting crucible furnace of the present invention;

Fig. 2 is the fixed front schematic view of the electromagnetic coil of the differential pressure casting crucible furnace of the present invention;

Fig. 3 is the fixed top view schematic diagram of the electromagnetic coil of the differential pressure casting crucible furnace of the present invention;

Fig. 4 is the rectangular pulse magnetic field waveform diagram of the magnetic field when the differential pressure casting crucible furnace of the present invention works;

Fig. 5 is the triangular pulse magnetic field waveform diagram of the magnetic field when the differential pressure casting crucible furnace of the present invention works;

Fig. 6 is the sinusoidal pulse magnetic field waveform diagram of the magnetic field when the differential pressure casting crucible furnace of the present invention works;

FIG. 7 is a waveform diagram of a magnetic field with a dB/dt of 1157 mT/s when the differential pressure casting crucible furnace of the present invention works.

Among them, 1 is a crucible, 2 is a heating element, 3 is an electromagnetic coil, 4 is a heat insulation layer, 5 is a refractory layer, 6 is a shell, and 7 is a support frame.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of 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.

The purpose of the present invention is to provide a differential pressure casting crucible furnace to solve the above-mentioned problems in the prior art, improve the melt nucleation rate, and promote the grain refinement of the casting, thereby improving the quality and performance of the casting.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Please refer to FIGS. 1-7, wherein, FIG. 1 is a schematic structural diagram of a crucible furnace for differential pressure casting of the present invention, FIG. 2 is a schematic front view of a fixed electromagnetic coil of the crucible furnace for differential pressure casting of the present invention, and FIG. A schematic top view of the fixed electromagnetic coil of the differential pressure casting crucible furnace, FIG. 4 is a rectangular pulse magnetic field waveform diagram of the magnetic field when the differential pressure casting crucible furnace of the present invention is in operation, and FIG. 5 is a triangle of the magnetic field when the differential pressure casting crucible furnace of the present invention is in operation. Pulse magnetic field waveform diagram, Fig. 6 is the sinusoidal pulse magnetic field waveform diagram of the magnetic field when the differential pressure casting crucible furnace of the present invention is working, Fig. 7 is the waveform that the dB/dt of the magnetic field is 1157mT/s when the differential pressure casting crucible furnace of the present invention is working picture.

The present invention provides a crucible furnace for differential pressure casting, comprising a crucible 1, a heating element 2 and an electromagnetic coil 3, wherein the crucible 1 can accommodate aluminum alloy melt; the heating element 2 is arranged outside the crucible 1, and the heating element 2 can use the crucible 1. The charge is heated; the electromagnetic coil 3 is arranged outside the crucible 1 and the heating element 2, and the electromagnetic coil 3 is connected to an external controllable electromagnetic energy power source. The electromagnetic coil 3 can generate a magnetic field, and the crucible 1 is located in the magnetic field generated by the electromagnetic coil 3.

In the differential pressure casting crucible furnace of the present invention, when working, the heating element 2 heats the crucible 1, and then achieves the purpose of heating and maintaining the aluminum alloy melt in the crucible 1. The crucible 1 can be made of heat-resistant materials such as graphite, so that aluminum The alloy melt is kept in a molten state; more importantly, in the present invention, an electromagnetic coil 3 is arranged outside the crucible 1, and the electromagnetic coil 3 is connected with an external controllable electromagnetic energy power supply. Electromagnetic treatment is applied to the melt, which affects the energy system in the melt, compensates for the energy required for the formation of critical nuclei in the melt, reduces the nucleation activation energy required for the nucleation process, and promotes the melt to overcome the nucleation barrier. Increase the number of primary crystal nuclei in the melt and increase the nucleation rate in the melt, thereby refining the grains of the final casting, improving the uniformity of the microstructure of the casting, and then improving the performance of the finished casting.

It should be emphasized that the electromagnetic coil 3 is connected with a controllable electromagnetic energy power supply, which can control the magnetic field generated by the electromagnetic coil 3, and adjust the magnetic field parameters through a dedicated controllable electromagnetic energy power supply. Different types such as triangular wave and sine wave, adjust parameters such as current, frequency, voltage, duty cycle and so on according to the required magnetic field strength to adapt to different production needs. In actual production, the controllable electromagnetic energy power supply can choose a professional power supply control cabinet to further improve the operation convenience of adjusting the magnetic field parameters. What needs to be explained here is that changing the number of layers, turns and winding method of the electromagnetic coil 3 can adjust the magnetic field strength. When the setting method and quantity of the electromagnetic coil 3 in the production process are certain, the controllable electromagnetic energy power supply can be used to adjust The magnetic field parameters further improve the controllability of the device.

Specifically, the electromagnetic coil 3 is spirally disposed outside the crucible 1 around the axis of the crucible 1 , so as to improve the uniformity of electromagnetic treatment applied by the electromagnetic coil 3 to the melt and further improve the uniformity of grain refinement of the casting.

Since the electromagnetic coil 3 is sleeved on the outside of the heating element 2, in order to protect the electromagnetic coil 3 and prevent the electromagnetic coil 3 from being overheated and affecting its normal operation, an insulating layer 4 is arranged between the heating element 2 and the electromagnetic coil 3, and the insulating layer 4 is composed of Made of nano heat insulating material, the heat insulating layer 4 can reduce the heat loss of the heating element 2 and improve the heating efficiency while providing protection for the electromagnetic coil 3 . In practical applications, the electromagnetic coil 3 is insulated and cured to improve operational safety. Since the temperature of the electromagnetic coil 3 needs to be controlled within 200°C, the electromagnetic coil 3 can also be ventilated and air-cooled to prolong the service life of the electromagnetic coil 3 and ensure The electromagnetic coil 3 works reliably.

In this specific embodiment, the heating element 2 is a heating rod. In practical applications, other forms of heating elements 2 can also be selected; in order to improve the heating efficiency and ensure the uniformity of the heating of the melt, a plurality of heating rods can be provided. It is evenly distributed around the axis of the crucible 1, the heating rod is an electric heating rod, and the heating rod is connected with an external power supply.

More specifically, the outside of the electromagnetic coil 3 is also provided with a refractory layer 5, the refractory layer 5 is sleeved on the outside of the electromagnetic coil 3, the refractory layer 5 is made of refractory bricks, the refractory layer 5 can further play the role of heat insulation, and also It can play the role of supporting the heating element 2 .

In other specific embodiments of the present invention, the electromagnetic coil 3 is connected to the inner wall of the refractory layer 5 to improve the stability of the electromagnetic coil 3 .

Further, the crucible 1 is sheathed with an outer casing 6, and the heating element 2 and the electromagnetic coil 3 are arranged in the outer casing 6. The installation of the outer casing 6 improves the structural integrity of the device and improves the convenience of hoisting and transportation of the device.

In this specific embodiment, the bottom of the electromagnetic coil 3 is provided with a support frame 7 , the support frame 7 is connected with the inner wall of the casing 6 , the support frame 7 can provide stable support for the electromagnetic coil 3 , and the support frame 7 is connected with the bottom inner wall of the casing 6 . , further improving the stability of the device. The connecting wire between the electromagnetic coil 3 and the external power source is passed out of the casing 6, the wire outlet of the casing 6 is sealed, and the connecting wire is insulated.

Furthermore, the electromagnetic coil 3 can generate a magnetic field when working, the duty ratio of the electromagnetic energy is 10%-70%, the output current of the electromagnetic energy is 100A-200A, the output frequency is 10Hz-100Hz, and the magnetic field intensity in the crucible 1 is ≥ 10mT, set the magnetic field parameters reasonably to enhance the grain refinement effect. In actual production, it can also be adjusted according to actual working conditions.

In the differential pressure casting crucible furnace of the present invention, an electromagnetic coil 3 is arranged between the casing 6 and the crucible 1 , and the electromagnetic coil 3 is used to electromagnetically treat the melt in the crucible 1 , and the number of layers of the electromagnetic coil 3 is set according to the capacity of the crucible 1 . and the number of turns, thereby adjusting the strength of the magnetic field and controlling the energy applied to the melt. When working, the aluminum alloy melt is treated with pulsed electromagnetic energy to improve the nucleation rate of the aluminum alloy melt, thereby affecting the subsequent solidification process of the aluminum alloy, refining the grains of the aluminum alloy casting, improving the uniformity of the microstructure of the casting, and improving the The strength, toughness and plasticity of aluminum alloy parts.

The free energy in the metal melt needs to cross the nucleation energy barrier to nucleate and grow to form a crystal. Two-thirds of the energy required for nucleation is provided by the solid-liquid phase free energy difference, and the remaining third constitutes the energy barrier. In the melt without special treatment, it is necessary to increase the degree of undercooling to overcome the energy barrier nucleation. The electromagnetic energy grain refinement technology generates a magnetic field in the melt through a coil. Since the pulsed magnetic field can generate a large dB/dt (change rate of magnetic induction intensity), this intermittent non-contact high-energy infiltration brings electromagnetic energy into the aluminum. The alloy melt has an impact on the energy system inside the aluminum alloy melt, increasing the energy fluctuation in the aluminum alloy melt to compensate for one-third of the energy required to form a critical nucleus, thereby overcoming the nucleation energy barrier and promoting the melt formation. nuclear. The invention improves the nucleation rate in the aluminum alloy melt through the electromagnetic energy grain refinement technology, so as to achieve the purpose of refining the crystal grains of the casting.

In the present invention, specific examples are used to illustrate the principles and implementations of the present invention, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention; There will be changes in the specific implementation manner and application scope of the idea of the invention. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. A differential pressure casting crucible furnace, comprising:

a crucible capable of containing an aluminum alloy melt;

a heating element disposed outside the crucible, the heating element capable of heating the aluminum alloy melt with the crucible;

an electromagnetic coil disposed outside the crucible and the heating element, the electromagnetic coil being connected to an external controllable electromagnetic energy source, the electromagnetic coil being capable of generating a magnetic field, the crucible being located within the magnetic field generated by the electromagnetic coil.

2. The differential pressure casting crucible furnace of claim 1, wherein: a controllable electromagnetic energy power source is connected to the electromagnetic coil and is capable of controlling the magnetic field generated by the electromagnetic coil.

3. The differential pressure casting crucible furnace of claim 1, wherein: the electromagnetic coil is spirally arranged outside the crucible in a surrounding manner around the axis of the crucible.

4. The differential pressure casting crucible furnace of claim 1, wherein: the electromagnetic coil is sleeved outside the heating element, a heat insulation layer is arranged between the heating element and the electromagnetic coil, and the heat insulation layer is made of nanometer heat insulation materials.

5. The differential pressure casting crucible furnace of claim 1, wherein: the heating element is a heating rod, the heating rod winds the axis circumference equipartition of crucible, the heating rod links to each other with external power source.

6. The differential pressure casting crucible furnace of claim 1, wherein: the electromagnetic coil is characterized in that a fire-resistant layer is further arranged outside the electromagnetic coil and sleeved outside the electromagnetic coil, and the fire-resistant layer is made of refractory bricks.

7. The differential pressure casting crucible furnace of claim 6, wherein: the electromagnetic coil is connected with the inner wall of the fire-resistant layer.

8. The differential pressure casting crucible furnace of claim 1, wherein: the outer part of the crucible is sleeved with a shell, and the heating element and the electromagnetic coil are arranged in the shell.

9. The differential pressure casting crucible furnace of claim 8, wherein: the bottom of the electromagnetic coil is provided with a support frame, and the support frame is connected with the inner wall of the shell.

10. The differential pressure casting crucible furnace of any one of claims 1 to 9, wherein: the electromagnetic coil can generate a magnetic field when working, the duty ratio of the electromagnetic energy is 10% -70%, the output current of the electromagnetic energy is 100A-200A, the output frequency is 10Hz-100Hz, and the magnetic field intensity in the crucible is more than or equal to 10 mT.

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