JP2003311391A - Apparatus for producing cast product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To nicely and smoothly produce a simple crystal cast product while holding a desired temperature gradient from the one end part toward the other end part of the product part with a simple and inexpensive constitution. <P>SOLUTION: This apparatus for producing the cast product, is provided with a heating mechanism 36 for heating the product part 28 constituting a mold 22, a cooling mechanism 38 which absorbs the heat by bringing it into contact with the lower part 28c of the mold in the product part 28 and solidifies molten alloy in the product part 28 in the unidirection from the lower part 28c of the mold toward the upper part 28d of the mold by relatively shifting the mold 22 in the reverse direction against the solidifying direction to the heating mechanism 36, and an inner baffle 48 for preventing the portion where the product part 28 is separated from the heating mechanism 36 from being heated. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting production apparatus for producing a casting by solidifying a melt in a mold in one direction.

[0002]

2. Description of the Related Art Generally, an investment casting method is known as a precision casting method for precision casting a product having a complicated shape. This investment casting method is also known as the lost wax method, in which a model is made using soluble wax or polystyrene resin, and a mud-like mixture of refractory is immersed around the model to form the refractory. After the refractory is laminated by repeating the steps of coating and drying several times to several tens of times, the model is melted and flowed out,
Further, it is poured as a baking mold.

In this type of precision casting, products are manufactured by unidirectional solidification (directional solidification). This is, for example, to optimize the temperature gradient of a single crystal alloy (for example, Ni-based alloy single crystal) such as a blade of a turbine rotor that constitutes a gas turbine engine, and improve the yield rate of the single crystal material.

As an apparatus for performing the above-mentioned unidirectional solidification, for example, an apparatus disclosed in US Pat. No. 4,609,029 is known. In this apparatus, as shown in FIG. 8, a mold 1 is placed on a chill plate 2, and the chill plate 2 can be raised and lowered with respect to the inside of the heating mechanism 3 via an actuator (not shown). In the mold 1,
A cavity 5 communicates with the molten metal inlet 4a through a runner (or runner) 4b.

The heating mechanism 3 is provided with a susceptor 7 having an induction heating coil 6 exteriorly mounted and a heat insulating material 7a. A funnel 9 is connected to an upper portion of the susceptor 7 via an upper plate 8. A baffle 10 is fixed to the lower portion of the susceptor 7 to separate the heating zone and the cooling zone.

In such a structure, the chill plate 2 on which the mold 1 is placed rises up, the mold 1 is placed in the heating chamber S and heated to a predetermined temperature under the action of the heating mechanism 3, and then the funnel. The molten metal of the casting alloy is injected from 9 into the molten metal injection port 4a of the mold 1. The molten metal is filled in the cavity 5 via the runner 4b. At that time, the mold 1 is in contact with the chill plate 2, and unidirectional solidification starts upward from the molten metal portion in contact with the chill plate 2.

Then, the chill plate 2 is moved downward at a predetermined speed so that the molten metal in the cavity 5 is
It is stated that crystal growth is promoted in the upward direction, and a cast product (product) is manufactured in the cavity 5 by directional solidification.

[0008]

However, in the above-mentioned conventional technique, as the chill plate 2 descends,
A large amount of heat enters and leaves between the baffle 10 and the mold 1 due to radiation and convection. Therefore, in the mold 1, the temperature on the lower side of the product part to be cooled rises, while the temperature on the upper side of the product part decreases. As a result, there is a problem in that it takes time to solidify the molten metal, a temperature gradient necessary for single crystallization cannot be obtained, and the crystal orientation of the single crystal shifts or a new crystal is generated. .

In particular, when casting a large blade that requires a further temperature gradient, only one blade may be arranged in some cases, and the gap between the baffle and the mold is very large, so that the temperature gradient required for single crystallization is large. Is difficult to obtain. Therefore, there is a problem that a single crystal cast cannot be cast.

At this time, it is considered that a baffle corresponding to the outer dimensions of the mold is prepared and this baffle is exchanged for use. However, since the baffle is usually sandwiched between the cooling section and the susceptor, the replacement work of this baffle is considerably complicated.

The present invention solves this kind of problem and is capable of maintaining a desired temperature gradient from one end to the other end of a product part with a simple and inexpensive structure, and single crystal casting An object of the present invention is to provide an apparatus for producing a cast product, which is capable of producing a good product smoothly.

[0012]

In a casting manufacturing apparatus according to the present invention, a heating mechanism for heating a product part constituting a mold and one end of the product part for contacting and absorbing heat,
A cooling mechanism for solidifying the melt in the product portion in one direction from the one end to the other end by moving the mold relative to the heating mechanism in a direction opposite to the solidification direction; And a heat shield member for preventing heating of a portion of the product portion that is separated from the heating mechanism when the mold and the heating mechanism are moved relative to each other (claim 1). invention).

Therefore, the mold and the heating mechanism relatively move in opposite directions, and when the product part constituting the mold is cooled from one end to the other end, it is separated from the heating mechanism. The part, that is, the one end side is not heated. Therefore, in the product part, a relatively large temperature difference occurs between the one end and the other end, and the crystal orientation can be well controlled, and the quality and strength of the single crystal cast are effectively improved.

Further, the heating mechanism is arranged so as to surround the mold and has a baffle arranged in the vicinity of the cooling mechanism, and the heat shield member is arranged in the vicinity of the baffle.
When relatively moving the mold and the heating mechanism,
The heat from the heating mechanism is prevented from being transmitted to the product portion side through the inside of the baffle (the invention according to claim 2).

With this, the heat from the heating mechanism is surely shielded through the baffle and the heat shield member, so that the temperature difference between the one end side and the other end side of the product portion can be effectively made with a simple structure. It becomes possible to spread.

Further, the heat shield member is set in the shape of a plate protruding toward the mold side with respect to the baffle (the invention according to claim 3). Therefore, the workability of the heat shield member is improved, and it becomes possible to easily cope with various molds having different shapes and dimensions. Therefore, it is excellent in versatility and economical because it is not necessary to prepare various heat shielding members.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic structural explanatory view of a casting manufacturing apparatus 20 according to an embodiment of the present invention.
FIG. 3 is an exploded perspective view of the main part of the manufacturing apparatus 20.

The manufacturing apparatus 20 is equipped with a mold 22 for casting the blades of a turbine rotor, for example. The casting mold 22 includes a sprue portion 24 and a plurality of, for example, 18 runner portions 26 radially provided from the sprue portion 24.
And a blade product portion 28 provided on the lower end side of the runner portion 26.

Each product section 28 is provided with a selector 30 and a starter 32, and the starter 32 is integrally provided with a disk-shaped base 34. Starter 32
Is a portion for generating crystal nuclei (columnar crystals) from the molten metal, and the selector 30 is a portion for growing one crystal from the generated crystal nuclei to obtain a single crystal.

The manufacturing apparatus 20 includes a heating mechanism 36 for heating the peripheral surfaces of the product parts 28 constituting the mold 22 including the mold outer side surface 28a and the mold inner side surface 28b; A cooling mechanism 38 for solidifying the molten metal in the mold 22 in one direction by moving the mold 22 in the direction opposite to the heating mechanism 36 (direction of arrow A) (direction of arrow B). The mold 22 includes a heat shield umbrella member 40 and an inner baffle (heat shield member) 48 described later.

The heating mechanism 36 is provided so as to surround the mold 22 and includes a carbon susceptor 44 and a heat insulating material 45 which are heated by the high frequency coil 42 at a high frequency. The carbon susceptor 44 has a substantially cylindrical shape, and a ring-shaped baffle 46 is supported on the lower portion thereof. An inner baffle 48 is inserted on the inner peripheral surface of the carbon susceptor 44 while being supported on a baffle 46.

The inner baffle 48 has a substantially disc shape, and the diameter of the inner peripheral surface 48a thereof is set to be equal to or smaller than the diameter of the disc base 34 which constitutes the mold 22. Specifically, the inner baffle 48 has a thickness of 10 m.
m, outer diameter 500 mm, inner diameter 380 mm,
The outer diameter of the mold 22 is 360 mm. The inner baffle 48 is made of, for example, a heat insulating molded body made of graphite. The inner baffle 48 only needs to have a heat insulating effect, and can be made of, for example, an alumina refractory material.

An upper plate 50 is provided above the carbon susceptor 44.
The upper plate 50 is provided with a molten metal supply part 52, and the molten metal supply part 52 can be opened and closed via a cover 54. Inside the carbon susceptor 44,
A heating chamber 55 for disposing the mold 22 is provided. The heating chamber 55 is maintained in a vacuum atmosphere.

The cooling mechanism 38 includes a chill plate 56 on which the mold 22 is placed. This chill plate 56
Is cooled by water cooling by supplying cooling water to the inside, and a concave portion 58 for arranging the disk-shaped base 34 forming the mold 22 is formed on the upper surface 56a (see FIG. 2). The disk-shaped base 34 is attached to the chill plate 56 via a plurality of stoppers (not shown).

The chill plate 56 is provided with a lifting rod 59 connected to an actuator (not shown). The mold 22 can move with respect to the heating mechanism 36 by moving the elevating rod 59 in the directions of arrow A and arrow B.

On the outer periphery of the chill plate 56, a ring-shaped cooling pipe 64 is arranged coaxially with the carbon susceptor 44. Cooling water is circulated and supplied to the cooling pipe 64 to form a cooling zone.

The heat-shielding umbrella member 40 is made of a heat-resistant cloth-like member such as alumina wool or carbon felt in a cloth shape. As the heat shield umbrella member 40, various materials can be applied as long as they can withstand a heating temperature (for example, 1500 ° C to 1600 ° C) and maintain their shape. The heat shield umbrella member 40 is formed in a substantially ring shape, and is disposed so as to cover the sprue portion 24 of the mold 22 and the upper portion of the runner portion 26.

As shown in FIG. 3, on the mold outer peripheral surface 28a side, 30 mm and 60 mm from the upper surface 56a of the chill plate 56.
B type thermocouples 66a, 66b, 66c and 66d are respectively bonded to the height positions of mm, 90 mm and 105 mm, and the B type thermocouple 68a is positioned at the height positions of 60 mm and 90 mm on the mold inner side surface 28b side. And 68b are glued together. The 60 mm and 90 mm height positions correspond to the tips and roots of the blades cast in the product section 28.

The operation of the manufacturing apparatus 20 thus constructed will be described below.

First, as shown in FIG. 2, the chill plate 5
The disk-shaped base 34 of the mold 22 is disposed in the recess 58 of the mold 6, and the disk-shaped base 34 is supported by the chill plate 56 via a stopper (not shown). The heat shield umbrella member 40 is disposed on the runner portion 26 of the mold 22. The heat shield umbrella member 40 covers the runner portion 26 up to a position near the R portion (corner portion) of the runner portion 26.

Therefore, the chill plate 56 supporting the mold 22 moves into the heating mechanism 36 under the action of an actuator (not shown) so that the mold 22 is placed in the heating chamber 55 and the heating mechanism 36 is driven. (See FIG. 1). Therefore, the carbon susceptor 44 is heated at a high frequency through the high frequency coil 42, and the mold 22 is heated by the radiant heat generated from the carbon susceptor 44.

At that time, the heating atmosphere is a vacuum, and the mold 2
After 2 is heated to 1500 ° C. and the mold temperature is stabilized, the nickel-base heat-resistant alloy melted in a high-frequency melting furnace (not shown) is poured from the melt supply part 52 into the gate part 24 of the mold 22. The pouring temperature is 1550 ° C.

The molten alloy poured into the sprue portion 24 is filled into the product portion 28 from the plurality of runner portions 26, and columnar crystals are generated upward in the starter 32 under the cooling action of the chill plate 56. Furthermore, the selector 30 above the starter 32
Then, a large number of columnar crystals are introduced, and finally one crystal selectively grows through the bent portion to become a single crystal in the product portion 28.

After the alloy temperature stabilizes in the mold 22, the elevating rod 59 moves in the direction of arrow B under the action of an actuator (not shown). Specifically, the lowering speed of the mold 22 is 350 mm / hr from the upper surface 56a of the chill plate 56 to a height of 30 mm, and then 200 m
m / hr.

In this case, as shown in FIG. 1, when the mold 22 is arranged in the heating chamber 55, the radiant heat generated from the carbon susceptor 44 causes the mold outer surface 28a and the mold inner surface 28b of the product part 28 to move. The peripheral surface including it is heated well.

Specifically, the outer surface 28a of the mold is the carbon susceptor 4 which the outer surface 28a of the mold closely faces.
The mold inner side surface 28b is heated by the radiant heat from the carbon susceptor 44, and the mold inner side surface 28b is heated by the radiant heat from the carbon susceptor 44 opposed to the mold inner side surface 28b. As a result, in the product portion 28, the outer mold surface 28a and the inner mold surface 28b are heated to a uniform temperature, and the lower mold part (one end) 28c and the upper mold part (the other end) 28d are also heated to a uniform temperature. It

When the mold 22 moves integrally with the chill plate 56 in the direction of the arrow B, the product portion 28 of the mold 22 is separated from the heating mechanism 36 to the cooling pipe 64 side, as shown in FIG. Moving. Therefore, in the product part 28, the cooling action of the cooling pipe 64 causes directional solidification (unidirectional solidification) from the mold lower part 28c side toward the mold upper part 28d side, and a single crystal is generated to produce the product part 28. A single crystal blade is manufactured in. At that time, chill plate 5
Since 6 is separated from the baffle 46, this baffle 46
A large amount of heat enters and leaves between the mold and the mold 22 due to radiation and convection.

Here, in this embodiment, an inner baffle 48 is provided which is close to the baffle 46 and projects toward the mold 22. Therefore, the product part 2 that constitutes the mold 22
When 8 is cooled from the lower mold part 28c on the chill plate 56 side toward the upper mold part 28d, heat input to the part separated from the heating mechanism 36, that is, the lower mold part 28c side is not induced.

As a result, in the product section 28, the lower mold part 28c moving from the heating chamber 55, which is the heating zone, to the inside of the cooling pipe 64, which is the cooling zone, and the upper mold part 28d, which is disposed in the heating chamber 55, are provided. During that time, a considerably large temperature difference occurs. Therefore, when the molten alloy is solidified in the product portion 28, the crystal orientation can be controlled well, and in particular, the effect of improving the quality and strength of the single crystal cast can be obtained.

Further, the inner baffle 48 is placed on the baffle 46.
When exchanging, the disassembling work of the manufacturing apparatus 20 becomes unnecessary. Therefore, when installing the mold 22, it is only necessary to arrange the inner baffle 48 corresponding to the shape of the mold, and the installation work of the inner baffle 48 can be performed simply and quickly. This simplifies the work of replacing the inner baffle 48 at once, as compared with the work of replacing the baffle 46 sandwiched between the carbon susceptor 44 and the cooling pipe 64 according to the shape of the mold, and simplifies the work. The cost for work can be effectively suppressed.

Moreover, the inner baffle 48 is composed of a heat insulating molded body made of graphite. Therefore, the inner baffle 48 can be easily cut with a cutter knife or the like, and, for example, even when a mold plan is added depending on the product shape, it can be easily dealt with. Thereby, it is excellent in general versatility and it is not necessary to prepare various inner baffles 48 according to various different molds 22, which is extremely economical.

Furthermore, when the molten alloy is poured into the mold 22, even if the molten alloy is scattered, it is protected by the inner baffle 48 and does not adhere to the baffle 46.
As a result, the baffle 46 can be effectively protected, and the frequency of maintenance and replacement work of the baffle 46 can be reduced.

By the way, in this embodiment, specifically, the lower mold part 28c (60) depending on the presence or absence of the inner baffle 48 is used.
An experiment was performed to detect the temperature difference between the position (mm position) and the upper part of the mold 28d (position 90 mm).

FIG. 5 shows that at the height positions monitored through the thermocouples 66a to 66d and 68a and 68b bonded to the mold 22, when the above casting operation is performed without using the inner baffle 48. It shows the temperature change.
As a result, when the lower mold part 28c of the product part 28 reached the liquidus temperature, the temperature difference from the upper mold part 28d was 20 ° C.

On the other hand, in this embodiment using the inner baffle 48, as shown in FIG.
When c reached the liquidus temperature, the temperature difference with the upper part 28d of the mold was about 60 ° C., and the temperature difference above and below the mold 22 effectively expanded.

Then, after the solidification of the molten metal is completed with and without the inner baffle 48,
The blade, which is a casting material, was taken out of the mold 22 and subjected to etching treatment to observe the respective crystal morphology.
The result is shown in FIG.

That is, when the inner baffle 48 is not used (Comparative Examples 1 and 2), 8 out of 18 blades are used.
In contrast to the case where abnormal crystals were generated in 44 sheets (44%), no abnormal crystals were generated in all of the 18 blades when the inner baffle 48 was used, and a good single crystal morphology was obtained. After that, when casting was performed 20 times or more, when the inner baffle 48 was used, the generation of foreign crystals was 3% or less in total.

Further, when the inner baffle 48 was not used, there was a defect in the crystal orientation in which the single crystal grew. This crystal orientation means a solidification direction in which solidification proceeds in one direction from the starter 32 in contact with the chill plate 56 to the selector 30. On the other hand, when the inner baffle 48 was used, the crystal orientation was also good.

In the present embodiment, the chill plate 56 that constitutes the cooling mechanism 38 is configured to be movable in the directions of arrow A and arrow B via an actuator (not shown), but instead of this, a heating mechanism is used. 36 may be configured to be movable.

[0050]

In the casting manufacturing apparatus according to the present invention, when the mold and the heating mechanism are moved relative to each other and the product part constituting the mold is cooled from one end to the other end. ,
Preventing the one end from being heated. Therefore, a relatively large temperature difference is generated between the one end and the other end of the product part, and the crystal orientation can be controlled well, and the quality and strength of the single crystal cast are effectively improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory diagram of a casting manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of essential parts of the manufacturing apparatus.

FIG. 3 is an explanatory diagram of a thermocouple mounting position of a mold that constitutes the manufacturing apparatus.

FIG. 4 is an operation explanatory diagram when a chill plate constituting the manufacturing apparatus is lowered with respect to a heating mechanism.

FIG. 5 is a temperature change explanatory diagram of each part of the mold when the inner baffle is not used.

FIG. 6 is a temperature change explanatory diagram of each part of the mold when the inner baffle is used.

FIG. 7 is an explanatory diagram of an occurrence rate of various defects depending on the presence or absence of the inner baffle.

FIG. 8 is an explanatory diagram of a schematic configuration of an apparatus according to a conventional technique.

[Explanation of symbols]

20 ... Manufacturing apparatus 22 ... Mold 24 ... Gate section 26 ... Runner section 28 ... Product section 28a ... Mold outside surface 28b ... Mold inside surface 30 ... Selector 32 ... Starter 36 ... Heating mechanism 38 ... Cooling mechanism 40 ... Heat shielding umbrella member 44 … Carbon susceptor 46… Baffle 48… Inner baffle 56… Chill plate 64… Cooling pipe

Claims (3)

[Claims] 1. A casting production apparatus for producing a casting by solidifying a molten material in a casting mold in one direction, comprising: a heating mechanism for heating a product portion constituting the mold; and one end of the product portion. While contacting the part to absorb heat, the mold is moved relative to the heating mechanism in a direction opposite to the solidification direction, thereby moving the melt in the product part from the one end to the other end. A cooling mechanism for solidifying in one direction by means of heat, and a heat shield member for preventing heating of a part of the product portion that is separated from the heating mechanism when the mold and the heating mechanism are moved relative to each other, An apparatus for manufacturing a casting, comprising: 2. The manufacturing apparatus according to claim 1, wherein the heating mechanism is disposed so as to surround the mold, and includes a baffle arranged in proximity to the cooling mechanism, wherein the heat shield member is , Located in close proximity to the baffle,
When relatively moving the mold and the heating mechanism,
A casting manufacturing apparatus, wherein heat from the heating mechanism is prevented from being transmitted to the product portion side through the inside of the baffle. 3. The manufacturing apparatus according to claim 2, wherein the heat shield member is set in a plate shape projecting toward the mold side with respect to the baffle.