CN115106500A - A movable induction heating device for vacuum centrifugal casting equipment - Google Patents

Abstract

The invention belongs to the technical field of centrifugal casting equipment, in particular to a movable induction heating device for vacuum centrifugal casting equipment, comprising an induction melting coil located above a vacuum centrifugal casting chamber and connected with a driving mechanism, and the induction melting coil is connected to an overfrequency power supply; A crucible holder is arranged in the middle of the upper cover of the centrifugal casting chamber, and a disposable crucible with a pre-opened bottom is arranged in the crucible holder; an ingot is arranged in the crucible, which is connected with the centrifugal casting mould through the sprue; the driving mechanism drives the smelting process. The induction melting coil moves downwards and moves from top to bottom to heat the ingot by induction melting, so that the ingot is gradually melted from top to bottom. After the entire ingot is completely melted, the alloy liquid is poured into the mold shell from the pre-opened bottom of the crucible. For centrifugal casting, the present invention provides different heat sources for different smelting stages, realizes that the overall temperature of the alloy liquid in the pouring process is uniform and precisely controllable, reduces the volume and complexity of centrifugal casting equipment, and improves casting quality.

Description

A movable induction heating device for vacuum centrifugal casting equipment

technical field

The invention belongs to the technical field of centrifugal casting equipment, and particularly relates to a movable induction heating device for vacuum centrifugal casting equipment.

Background technique

Centrifugal casting is a technical method in which the high-speed rotation of the mold makes the molten metal in the mold fill the mold by centrifugal motion and form a casting. Centrifugal casting was originally used to produce cast pipes, and the production of cast iron pipes, internal combustion engine cylinder liners and shaft sleeves was the most common. With the development of technology, some small special-shaped castings, such as small valves, motor rotors, impellers, etc., have also begun to be produced by the method of investment casting + centrifugal casting.

The traditional induction melting process of centrifugal casting mainly relies on the induction coil to energize the pre-set metal alloy ingot in the crucible. After the alloy ingot is completely melted into the alloy liquid, the crucible is tilted so that the alloy liquid flows into the runner to realize centrifugal casting, such as CN111842845A and CN105710331A. The main problems in this process are: during the smelting process, due to the uneven distribution of the magnetic field lines during heating, the temperature field of the alloy liquid in the crucible is uneven and has no obvious regularity. The surface of the molten metal enters the casting together with the tilting of the crucible, resulting in a high content of inclusions in the casting and a decrease in the performance of the casting; secondly, during the tilting process of the crucible, it is difficult for the induction coil to continuously heat the alloy liquid, the temperature of the alloy liquid drops, and the pouring temperature is difficult to be accurate. At the same time, due to the different quality of the molten metal poured out of the crucible at different tilting angles, the pouring speed of the alloy liquid is difficult to control, which increases the uncertainty of the casting quality, so it is not suitable for the centrifugal casting of high-precision complex thin-walled workpieces. In order to leave a pouring space for the gating system, and adding a pouring mechanism will significantly increase the volume and complexity of the centrifugal casting equipment.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a movable induction heating device for vacuum centrifugal casting equipment, which is matched with a ceramic fiber crucible with an opening at the bottom, which can realize the pouring of molten metal into the mold shell from the bottom of the crucible for centrifugal casting.

To achieve the above purpose, the complete technical scheme of the present invention includes:

A movable induction heating device for vacuum centrifugal casting equipment, comprising a movable induction melting coil, the induction melting coil is located above the vacuum centrifugal casting chamber, and is connected with a driving mechanism through a coil fixing bracket, and the driving mechanism is driven by a transmission rod The bracket and the induction melting coil move up and down, and the induction melting coil is connected to the overfrequency power supply;

A crucible holder is arranged in the middle of the upper cover of the vacuum centrifugal casting chamber, and a disposable crucible is arranged in the crucible holder; the ingot for induction melting is placed in the disposable crucible, and the disposable crucible has a pre-opened bottom, and is connected with the sprue through the sprue. The mold shells of centrifugal casting are connected;

During the smelting process, the induction smelting coil is connected to the over-frequency power supply, and the drive mechanism drives the induction smelting coil to move down into the area where the disposable crucible is located, and moves from top to bottom to conduct induction smelting and heating of the ingot, so that the ingot is gradually melted from top to bottom. After the entire ingot is completely melted, the alloy liquid is poured into the mold shell from the pre-opened bottom of the disposable crucible for centrifugal casting.

Preferably, the driving mechanism is fixed above the frame of the vacuum centrifugal casting equipment.

Preferably, the driving mechanism is a hydraulic cylinder or a motor.

Preferably, a transparent observation chamber is set on the outer side of the disposable crucible to observe the melt in the disposable crucible.

Preferably, the transparent observation chamber is a transparent quartz cover.

Preferably, an infrared thermometer is provided on the top of the transparent observation chamber to monitor the temperature change in the ingot smelting process in real time.

Preferably, the induction melting coil is kept heated during the casting process.

Preferably, the temperature of the upper alloy liquid in the disposable crucible is higher than that of the lower alloy liquid during the smelting process.

The advantages of the present invention relative to the prior art are:

1. The induction smelting coil of the present invention moves from top to bottom in the smelting process to inductively heat the ingot in the crucible, providing different heat sources for different smelting stages, so that the alloy ingot is gradually melted from top to bottom, and the alloy is poured during the pouring process. The liquid is always heated by the coil to ensure the consistency of the pouring temperature of the alloy liquid during the pouring process, and the alloy liquid will not be interrupted. During the pouring process, the lower alloy liquid enters the mold first, and the upper metal liquid enters later. Therefore, the uniformity of the alloy liquid and the final pouring temperature can be controlled by controlling the moving speed of the coil, the size of the heating power and the real-time infrared temperature measurement device. , improve the casting quality.

2. When the induction melting coil reaches the bottom, the entire ingot is completely melted, and the molten metal is poured into the mold shell from the bottom pre-opened at the bottom of the disposable crucible. Bottom pouring ensures the purification and filling ability of the alloy liquid. Low-density slag inclusions and bubbles have sufficient time to float, reducing the generation of pores and inclusion defects, ensuring the purity of the melt, further improving the quality of castings, and reducing the processing cost of ingots.

3. There is no need to reserve a dumping space and a dumping mechanism, which reduces the volume and complexity of the centrifugal casting equipment.

4. The induction melting system is equipped with an infrared thermometer, and the red thermometer detects the melting state of the ingot in real time, realizing the automatic control process of melting and casting.

Description of drawings

FIG. 1 is a top view of the movable induction heating device of the present invention.

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1 .

FIG. 3 is a schematic diagram of the overall structure of the centrifugal casting equipment to which the movable induction heating device is adapted.

In the picture: 1- hydraulic cylinder, 2- frame, 3- induction melting coil, 4- casting chamber cover, 5- solenoid valve, 6- vacuum gauge, 7- centrifugal casting chamber, 8- tooling plate, 9- positioning Pin, 10-transparent quartz cover, 11-crucible, 12-crucible holder, 13-mould platen, 14-turntable, 15-adjustable seat, 16-mould, 17-magnetic fluid seal, 18-magnetic coupling device, 19-rebound slider, 20-casting chamber shell, 21-electric rotating shaft.

Detailed ways

The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only used as examples and are not used to limit the present application.

A movable induction heating device for vacuum centrifugal casting equipment, as shown in Figures 1-3, the movable induction heating device is installed on the vacuum centrifugal casting equipment, including a movable induction melting coil 3, the induction melting coil 3 The coil is connected to the hydraulic cylinder 1 through the coil fixing bracket, and the coil and the coil fixing bracket are connected by flanges and screws. The hydraulic cylinder 1 is fixed above the frame 2 of the vacuum centrifugal casting equipment. The hydraulic cylinder 1 can drive the bracket and the frame through the transmission rod. The induction melting coil 3 moves up and down, the induction melting coil is located above the casting chamber upper cover 4 of the centrifugal casting chamber 7, and the induction melting coil is connected to a 70KW high-power overclocking (80-200khz) power supply through a water-cooled cable;

A disposable crucible 11 is arranged inside the induction melting coil, and a crucible holder 12 is arranged in the middle of the upper cover 4 of the vacuum centrifugal casting chamber to support the disposable crucible 11; The mold shells 16 of centrifugal casting are connected together, the ingot for induction melting is placed in the crucible 11, the outer side of the crucible is covered with a transparent quartz cover 10, and the top of the transparent quartz cover 10 is provided with an infrared thermometer, and the infrared thermometer monitors the ingot melting process in real time. temperature change.

The heating method using the movable induction heating device of the present invention is as follows: the induction melting coil is connected to a high-power over-frequency power supply, and then the coil is moved from top to bottom to perform induction melting of the ingot in the ingot. And move down, so that the ingot is gradually melted from top to bottom, so that when the induction melting coil reaches the bottom, the whole ingot is completely melted, and the molten metal flows into the mold shell from the pre-opened bottom of the bottom of the disposable crucible for centrifugation. For casting, because the coil moves from top to bottom during the smelting process, the temperature of the molten metal above is slightly higher than that of the molten metal below, achieving a certain temperature gradient from top to bottom, and flowing into the mold shell from the bottom of the crucible. In the crucible, the alloy liquid is always heated by the coil, which can quickly and completely melt the mother alloy ingot and ensure the continuous flow of the molten metal during the pouring process. At the same time, the moving speed of the induction melting coil plays a very critical role in the whole casting process. If the moving speed is too fast, the ingot cannot be fully melted, the degree of superheat is low, the viscosity of the alloy liquid is large, and the purity of the alloy liquid decreases, which is easy to cause thin-walled parts. Under pouring, the final solidification part has poor feeding, which is prone to shrinkage porosity defects; if the moving speed is too slow, the pouring temperature will be too high, the heating power and time will be increased, and the temperature gradient will be too large, which is easy to coarsen the grains .

Therefore, the present invention adopts the following method to control the moving speed of the coil:

为线圈向下移动速度，单位为m/s；

为线圈加热功率，单位为W；

为线圈的移动行程，单位为m；

为铸造所用合金换算后的相变潜热，单位为J/Kg；

为铸造所用合金的浇注过热度，单位为℃；

为铸造所用合金的液态比热容，单位为J/(Kg·℃)；

为铸锭质量，单位为Kg；

为加热损耗系数，取值范围为0.3~0.9。In the formula,

is the downward moving speed of the coil, in m/s;

is the heating power of the coil, the unit is W;

is the moving stroke of the coil, the unit is m;

It is the latent heat of phase transformation after conversion of the alloy used for casting, the unit is J/Kg;

is the pouring superheat of the alloy used for casting, in °C;

is the liquid specific heat capacity of the alloy used for casting, in J/(Kg ℃);

is the mass of the ingot, the unit is Kg;

is the heating loss coefficient, the value range is 0.3~0.9.

In the movable induction heating device of the present invention, the induction melting system is provided with an infrared thermometer and an induction melting coil that can move up and down. The melting state of the ingot is detected in real time by the red thermometer, and the automatic control process of smelting and casting is realized. The induction smelting coil is connected to a high-power over-frequency power supply, and the up and down movement of the induction coil is used to provide different heat sources for the smelting stage, so as to realize the rapid smelting process of the ingot and realize the melting process of the ingot from top to bottom and from outside to inside, so as to ensure that the molten metal is fully charged. During the molding process, it can flow into the mold shell from the bottom of the crucible steadily and continuously.

The centrifugal casting equipment paired with the movable induction heating device is further described below.

The centrifugal casting equipment used in conjunction with the mobile induction heating device of the present invention includes a vacuum centrifugal casting chamber 7, the side wall of the casting chamber is provided with a solenoid valve 5, an external vacuum pump is provided, and a vacuum gauge 6 is provided to ensure the vacuum environment of the entire smelting and forming process; A crucible rack is provided above the centrifugal casting chamber 7, where a disposable crucible 11 can be placed. The bottom of the crucible 11 is provided with a pre-opening for pouring. The crucible 11 is aligned with the centerline of the mold shell 16, so that the alloy liquid flows from the bottom of the crucible into the mold shell 16. .

The mold shell 16 is fixed on the turntable 14 by the adjustable fixing seat 15, the mold shell pressing plate 13 and the positioning pin 9; the mold shell pressing plate 13 is provided with a resilient slider 19. When the turntable 14 rotates, the resilient slider 19 It will be automatically locked to fasten the mold shell 16; the turntable 14 is connected with the electric rotating shaft 21 through the magnetic coupling 18, and the turntable 14 and the casting chamber are sealed with magnetic fluid 17, so that the turntable 14 can be independent of casting The chamber housing 20 realizes relative rotation.

The process of centrifugal casting corresponding to the above induction melting method is: preheating the mold shell - encapsulating the casting chamber - vacuuming - rapid induction melting - pouring and forming - breaking vacuum cooling. After the vacuum degree meets the requirements, the vacuum centrifugal casting chamber is assembled to the electric rotating shaft through the tooling plate 8 and the magnetic coupling. The induction melting coil is connected to a high-power over-frequency power supply, and the coil is moved from top to bottom to quickly and completely melt the mother alloy ingot to ensure the continuous flow of molten metal during the pouring process. When pouring, make the turntable mold shell reach a predetermined speed in advance. When the alloy liquid is heated to the pouring temperature, it flows into the rotating mold shell from the pre-opening of the crucible, so that the melt solidifies and forms under the action of centrifugal force. After the casting is solidified, the entire vacuum centrifugal casting chamber is disassembled for vacuum breaking cooling.

The centrifugal casting equipment adopts a centrifugal casting packaging structure that can be vacuumed independently. During the smelting and casting process, the next set of centrifugal casting chambers can be packaged, and preheated and vacuumed. After the previous set of packaging structures are disassembled, replace The pretreated package structure continues the rapid induction melting and pouring process, and repeats the operation to realize the flow production of superalloy castings. It not only shortens the vacuuming time, but also realizes the double-thread flow operation of the preheating, vacuuming process, smelting and pouring molding process, so that the whole process becomes a closed-loop system, which greatly improves the work efficiency.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. Replacement should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (8)

1. A movable induction heating device for vacuum centrifugal casting equipment, characterized in that, the movable induction heating device comprises a movable induction melting coil, and the induction melting coil is located above the vacuum centrifugal casting chamber, and is connected to the vacuum centrifugal casting chamber through the coil fixing bracket. The drive mechanism is connected to each other, and the drive mechanism drives the bracket and the induction melting coil to move up and down through the transmission rod, and the induction melting coil is connected to the overfrequency power supply; A crucible holder is arranged in the middle of the upper cover of the vacuum centrifugal casting chamber, and a disposable crucible is arranged in the crucible holder; the ingot for induction melting is placed in the disposable crucible, and the disposable crucible has a pre-opened bottom, and is connected with the sprue through the sprue. The mold shells of centrifugal casting are connected; During the smelting process, the induction smelting coil is connected to the over-frequency power supply, and the drive mechanism drives the induction smelting coil to move down into the area where the disposable crucible is located, and moves from top to bottom to conduct induction smelting and heating of the ingot, so that the ingot is gradually melted from top to bottom. After the entire ingot is completely melted, the alloy liquid is poured into the mold shell from the pre-opened bottom of the disposable crucible for centrifugal casting. 2 . The movable induction heating device for vacuum centrifugal casting equipment according to claim 1 , wherein the driving mechanism is fixed above the frame of the vacuum centrifugal casting equipment. 3 . 3 . The movable induction heating device for vacuum centrifugal casting equipment according to claim 1 or 2 , wherein the driving mechanism is a hydraulic cylinder or a motor. 4 . 4 . The movable induction heating device for vacuum centrifugal casting equipment according to claim 1 , wherein a transparent observation chamber is set on the outer side of the disposable crucible to observe the melt in the disposable crucible. 5 . 5 . The movable induction heating device for vacuum centrifugal casting equipment according to claim 4 , wherein the transparent observation chamber is a transparent quartz cover. 6 . 6 . The movable induction heating device for vacuum centrifugal casting equipment according to claim 4 , wherein an infrared thermometer is provided on the top of the transparent observation chamber to monitor the temperature change of the ingot smelting process in real time. 7 . 7 . The movable induction heating device for vacuum centrifugal casting equipment according to claim 6 , wherein the induction melting coil is kept heated during the casting process. 8 . 8 . The movable induction heating device for vacuum centrifugal casting equipment according to claim 7 , wherein the temperature of the upper alloy liquid in the disposable crucible is higher than that of the lower alloy liquid in the smelting process. 9 .

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