CN2808362Y - Equipment for manufacturing oriental-congealing casting pieces - Google Patents

Abstract

The utility model provides equipment for manufacturing oriental-congealing casting pieces. The utility model mainly comprises a smelting chamber, a holding furnace, a crystallizer, wherein a crucible is arranged in the smelting chamber, and the circumference of the crucible is provided with induction heating coils; holes are arranged in the bottom of the crucible and covered through diaphragm plates. The holding furnace is arranged under the smelting chamber, and a casting mold is arranged inside the holding furnace; the circumference of the casting mold is provided with heating elements, and a funnel is arranged above the casting mold; a chassis of the crystallizer underlays the casting mold, and the crystallizer is arranged under the holding furnace and installed on a lifting mechanism; the crystallizer and the holding furnace are connected with a vacuum system. The utility model is characterized in that the crystallizer belongs to an alloy melting bath with low melting points, and a heat insulation layer is arranged on the surface of alloy solution with low melting points. The device has the advantages that the temperature gradient which is generated in the oriental-congealing operation is raised by big percentages, and the temperature gradient can be enhanced to 120-180k/cm from 40-60k/cm of the traditional HRS technology, so the device can make the highest casting piece with the large size of from 35 cm to 40 cm; the production efficiency is enhanced obviously; the utility model solves the problem that metal is easy to react with ceramic molds with high temperatures for the long time; the microsegregation of the alloy oriental-congealing organization is eased, and the alloy thermal treatment time following up is shortened, so the utility model also saves the cost.

Description

A kind of equipment for producing directionally solidified castings

technical field

The utility model relates to a device for producing directional solidification castings, in particular to a device for directional solidification casting of large-size directional and single crystal castings (such as gas turbine blades, etc.).

Background technique

Directional solidification technology can produce metal castings with eliminated transverse grain boundaries (orientated columnar grains) or completely eliminated grain boundaries (single crystals), which have better longitudinal mechanical properties compared with castings obtained by traditional casting methods. Static and moving blades of gas turbines and aero-engines are an example of the application of directional solidification technology.

The industrialized directional solidification technology mainly refers to the high-speed solidification method (HRS). As shown in Figure 1, the formwork (3) is placed on the water-cooled crystallizer (6) and passed through the heating element (1) in the holding furnace (2). After heating above the melting point of the metal and casting the molten metal in the formwork, the formwork is pulled from the holding furnace in the direction of the arrow to form a directionally solidified casting. A key determinant of the quality of directional solidification castings is the temperature gradient that directional solidification equipment can achieve during the entire directional solidification process. If the entire casting is directional solidified under a higher temperature gradient, the production efficiency will be higher and the pass rate of the product will be higher. high. In order to increase the temperature gradient, some HRS equipment uses a heat insulation baffle (4) at the bottom of the holding furnace, and uses a water cooling ring (5) under the heat insulation baffle, so that the heat of the mold shell can be transferred to the water cooling crystallization through heat conduction on the one hand. The device is lost, and on the other hand, it is lost to the water cooling ring through heat radiation.

In order to obtain molten alloy, general directional solidification equipment adopts induction heating method, as shown in Figure 1, the superalloy master alloy is placed in the crucible (11), after being heated and melted by the induction coil (12), it passes through the sprue (13) Pour into the formwork of the holding furnace.

In the traditional HRS equipment, since the heat insulation baffle cannot change with the shape of the casting, a gap will inevitably be left between the mold shell (3) and the heat insulation baffle (4), which will greatly reduce the temperature of the directional solidification process gradient; similarly, the cooling effect of the water-cooling ring is also affected by the shape of the casting; in addition, the water-cooling crystallizer (6) moves downward during the directional solidification process, gradually away from the holding furnace, and the heat taken away by the heat conduction of the water-cooling crystallizer is getting more and more Generally, when the mold height exceeds 7cm, the heat of the mold shell is mainly taken away by radiation to the vacuum chamber wall (7), so as the length of the casting increases, the temperature gradient that the HRS equipment can achieve gradually decreases. The relationship between solidification speed (approximately equal to the stretching rate of water-cooled crystallizer), temperature gradient and casting size in directional solidification is shown in Figure 2. Equiaxed grains, shrinkage cavities, spots, and small-angle grain boundaries in the figure are all common defects in directional and single crystal castings. Obviously, when producing large blades by HRS method, due to the small temperature gradient that the equipment can achieve, the production Only a very low solidification rate (stretching rate) can be used. On the one hand, the production efficiency is extremely low, and on the other hand, it is close to the limit of the process conditions (the gray ellipse area in the figure), castings are prone to defects, and the product qualification rate is very low. Therefore, the HRS method is extremely costly when producing large-size oriented and single-crystal castings.

Contents of the invention

The purpose of the utility model is to provide a device for producing directional solidification castings, which can greatly increase the temperature gradient in the directional solidification process, and the temperature gradient remains unchanged throughout the directional solidification process without being affected by the size of the castings.

The utility model provides equipment for producing directional solidification castings, which mainly includes a melting chamber (34), a holding furnace (37), a crystallizer (40), a lifting mechanism (46), a vacuum system (50, 51), a melting chamber (34) At the top of the equipment, there is a crucible (32) in the melting chamber (34), surrounded by induction heating coils (31), and there are holes (36) on the bottom of the crucible (32), holes (36) Cover with partition (33), holding furnace (37) is below smelting chamber (34), places mold (10) in holding furnace (37), heating body (38) is arranged around, and funnel (10) is arranged above mold (10) 35), the mold (10) is placed under the crystallizer chassis (58), the crystallizer (40) is under the holding furnace (37), and the crystallizer (40) is installed on the lifting mechanism (46) to control the lifting speed, the crystallizer (40) and holding furnace (37) are connected with vacuum system (50), to keep vacuum, it is characterized in that: crystallizer (40) is low-melting-point alloy melting pool, and there is insulation layer (42) on the surface of low-melting-point alloy solution ).

In the equipment for producing directional solidification castings provided by the utility model, the low-melting point alloy molten pool (40) may be a Sn molten pool (40), equipped with a temperature control system (41), which is kept at 232-380°C.

The utility model provides equipment for producing directional solidification castings, the shape of the heat insulating layer (42) is adapted to the shape of the mold, and the material is high temperature resistant, low thermal conductivity, and does not react with the mold material at high temperature. The thickness is 0.1-10cm.

The equipment for producing directional solidified castings provided by the utility model has an agitator (44) extending from top to bottom in the molten pool of low-melting alloy (40).

The advantages of the equipment for producing directional solidification castings provided by the utility model include:

1. The temperature gradient in directional solidification is greatly increased, and the temperature gradient can be increased from 40-60K/cm in the traditional HRS process to 120-180K/cm. Large-size castings up to 35-40 cm can be prepared, and the temperature gradient has nothing to do with the size of the casting during directional solidification.

2. Fast stretching rate in directional solidification, such as 7-20mm/min, the production efficiency is obviously improved.

3. Solve the problem that the metal is easy to react with the ceramic mold under long-term high temperature.

4. The micro-segregation of the directional solidification structure of the alloy is reduced, which shortens the subsequent heat treatment time of the alloy and saves costs.

Description of drawings

Figure 1 is a schematic diagram of the directionally solidified casting prepared by the traditional HRS process.

Fig. 2 is a schematic diagram of the relationship between temperature gradient, stretching rate, dimension and defect of directional solidification casting in directional solidification process.

Fig. 3 is a structural schematic diagram of the utility model.

Detailed ways

Example 1

A structure of equipment for producing directional solidification castings is shown in Figure 3, mainly including a melting chamber (34), a holding furnace, a crystallizer, a lifting mechanism, and a vacuum system (50, 51).

The upper part is an induction melting vacuum chamber melting chamber (34). There is a crucible (32) in the melting chamber (34). The crucible (32) is surrounded by induction coils (31). There are holes (36) on the bottom of the crucible (32), and the holes ( 36) Cover with spacer (33).

The casting mold (10), the casting mold holding furnace (37) and the low melting point metal Sn molten pool (40) etc. are installed in the lower vacuum chamber below the smelting chamber (34), and the vacuum pump system includes a mechanical pump, a Roots pump and a booster pump connected. Casting mold (10) is placed in holding furnace, has heating body (38) all around, and funnel (35) is arranged on casting mold (10) top, and casting mold (10) underlays chassis (58).

The low-melting point metal molten pool (40) is kept between 232～380 DEG C with the temperature control system (41) of German SIEMENS company, and there is a thermal insulation layer (42) on the surface of the alloy solution; Stirrer (44).

The lower vacuum chamber is equipped with a stretching drive mechanism of the mold to control the lifting speed of the crystallizer chassis (58).

The method of liquid cooling of low-melting-point metal Sn is adopted to make the mold cool rapidly after contacting the low-melting-point alloy; the temperature of the low-melting-point alloy is controlled by the temperature control mechanism (41), and when a large casting enters the low-melting-point alloy molten pool (40), the low When the temperature of the melting point metal molten pool (40) rises, the temperature of the low melting point molten pool can be cooled by the temperature control mechanism; there is a layer of heat insulation layer (42) on the surface of the low melting point metal, and when the mold falls into the low melting point metal molten pool (40) , the heat insulation layer (42) ensures that the heat of the mold holding furnace will not be lost by radiation, and that the surface of the low melting point metal will not increase in temperature due to thermal radiation; accordingly:

1. The temperature gradient in directional solidification is greatly increased, and the temperature gradient can be increased from 40-60K/cm in the traditional HRS process to 120-180K/cm. Large size castings up to 35-40cm can be prepared. The temperature gradient is independent of casting size.

2. The drawing rate is fast, such as 7-20mm/min, and the production efficiency is obviously improved.

3. Solve the problem that the metal is easy to react with the ceramic mold under long-term high temperature.

4. The micro-segregation of the directional solidification structure of the alloy is reduced, which shortens the subsequent heat treatment time of the alloy and saves costs.

5. Using the liquid cooling method of low-melting-point metal Sn, the steady-state directional solidification can be interrupted by rapid quenching (up to 5m/s), and the morphology of the superalloy mushy zone can be retained, so as to obtain the dendrite growth form and dendrite during directional solidification. A large amount of information such as segregation and solid-liquid interface morphology is of great significance to material science research.

Example 2

The structure of a device for producing directional solidification castings is basically the same as that of Embodiment 1, the difference is that the molten pool of low-melting alloy (40) can be pulled out or pushed into the vacuum chamber through the slideway (45), and the device can be changed to For traditional HRS equipment.

This equipment can also be obtained by changing the water-cooled crystallizer of traditional HRS equipment into a low-melting-point metal molten pool (40).

Claims (10)

1. An equipment for producing directional solidified castings, mainly comprising a smelting chamber (34), a holding furnace (37), a crystallizer (40), a lifting mechanism (46), a vacuum system (50), and the smelting chamber (34) in At the top of the equipment, there is a crucible (32) in the smelting chamber (34), and the crucible (32) is surrounded by induction coils (31), and there is a hole (36) at the bottom of the crucible (32), and the hole (36) uses a spacer (33 ) to cover up, the holding furnace (37) is below the smelting chamber (34), and the casting mold (10) is placed in the holding furnace (37), and there is a heating body (38) around it, and there is a funnel (35) above the casting mold (10), and the casting mold ( 10) Underlay the chassis (58), the crystallizer (40) is under the holding furnace (37), the crystallizer (40) is installed on the lifting mechanism (46), the crystallizer (40) and the holding furnace (37) are connected with the vacuum system (50) are connected, and it is characterized in that: the crystallizer (40) is a low-melting-point alloy molten pool, and a heat-insulating layer (42) is arranged on the surface of the low-melting-point alloy solution. 2. The equipment for producing directionally solidified castings according to claim 1, characterized in that: the low-melting point alloy molten pool (40) is a Sn molten pool. 3. The equipment for producing directionally solidified castings according to claim 2, characterized in that: said Sn molten pool (40) is equipped with a temperature control system (41). 4. The equipment for producing directionally solidified castings according to claim 1, characterized in that: the shape of the heat insulating layer (42) is adapted to the shape of the mold. 5. The equipment for producing directional solidification castings according to any one of claims 1 to 4, characterized in that: the material of the heat insulation layer (42) is high temperature resistant, has low thermal conductivity, and is incompatible with the mold material at high temperature. React material. 6. The equipment for producing directionally solidified castings according to any one of claims 1-4, characterized in that: the thickness of the heat insulation layer is 0.1-10 cm. 7. The equipment for producing directionally solidified castings according to claim 5, characterized in that: the thickness of the heat insulation layer is 0.1-10 cm. 8. The equipment for producing directionally solidified castings according to any one of claims 1-4, characterized in that: the stirrer (44) extends from top to bottom in the low melting point alloy molten pool (40). 9. The equipment for producing directionally solidified castings according to claim 5, characterized in that: a stirrer (44) extends from top to bottom in the low melting point alloy molten pool (40). 10. The equipment for producing directionally solidified castings according to claim 7, characterized in that: the agitator (44) extends from top to bottom in the low melting point alloy molten pool (40).

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