JPH06229203A - Cast hot impeller and manufacture thereof - Google Patents

Abstract

PURPOSE:To eliminate defects in casting of a hot impeller used in a turbocharger and facilitate the centering during joining of the impeller to a rotary shaft, by uniformly maintaining the temperature gradient of molten metal during casting. CONSTITUTION:A hot impeller is composed of a body 14 formed thereon several radial vanes 12, a clip seat part 16 projected into the center of the front end side base part 14a of the body, a joint part 32 formed at the center of the rear end side base part 14b of the body, and allowed to be jointed to one end part 18a of a separate rotary shaft 18, all of these component parts being integrally cast from an ultra-high heat-resistant allay material. With the use of a molding having a cavity 34 with which the hot impeller is integrally cast, and a runner 40 communicated with a part for forming the clip seat part, molten metal whose temperature is controlled so as to be maintained at a suitable temperature during casting is filled into the part for forming the clip seat part, through the runner so as to manufacture the impeller.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting hot casting which can easily perform centering when a separate rotating shaft is joined to a hot impeller used in a turbocharger which uses exhaust gas of an automobile, for example. The present invention relates to an impeller and a method for casting the impeller.

[0002]

2. Description of the Related Art For example, in a turbocharger of an automobile, exhaust gas from an engine rotates a turbine at a high speed, and a large amount of compressed air is sent to a combustion chamber of the engine by suction force at that time to increase an engine output. It is preferably used for. A member incorporated in the exhaust side of the turbocharger and receiving exhaust gas from the engine to rotate at high speed is the hot impeller 10 shown in FIG. The hot impeller 10 includes a main body 14 in which a large number of vanes 12 are radially formed at required intervals, a chrysanthemum seat portion 16 protruding from the center of a front end side base portion 14a of the main body 14, and a rear end side base portion of the main body 14. The rotary shaft 18 is connected to the center of the rotary shaft 14 with its axis aligned, and a cold impeller 20 for sucking external air is additionally attached to the other end of the rotary shaft 18.

Since the hot impeller 10 is placed in a harsh environment where it is directly exposed to a high temperature exhaust gas reaching 900 ° C., it is manufactured by casting a nickel (Ni) -based superalloy. As a conventional technique, the lost wax method is used as an example for manufacturing a hot impeller. That is, as shown in FIG. 5, the superheat-resistant alloy melted by using the lost wax technique was poured into the individual cavities 24 of the mold 22 having air permeability and having a substantially tree shape as a whole, and the alloy was cooled and solidified. By performing mold separation later, the cast product 26 shown in FIG.
Is what you get. In this case, one side of the casting 26 has a runner 28 communicating with the cavity 24 of the mold 22.
The rod-shaped portion 30 in which the remaining molten metal is solidified is integrally formed. Therefore, as shown in FIG. 6, the hot impeller 10 as a product is obtained by cutting the rod-shaped portion 30 from the cast product 26 at an appropriate portion. A rotary shaft 18 as a separate body is joined to the hot impeller 10 by means such as electron beam welding or rotary friction welding. The hot impeller 10 to which the rotary shaft 18 is joined is further provided with the cold impeller 20 and then subjected to a rotational balance check and various inspections.
It is assembled into a turbocharger casing (not shown) to complete the product.

[0004]

[Problems to be Solved by the Invention] Hot impeller 10
When casting the conventional mold 22, as shown in FIG. 5, the part which becomes the chrysanthemum seat part 16 protruding from the tip side base part 14a of the impeller 10 is set to the innermost part of the cavity 24 in the mold 22 as shown in FIG. In addition to being located at a point, the rear end side base portion 14b of the impeller 10 is located on the side communicating with the runner 28 of the mold 22. It is considered that this is because if the rod-shaped portion 30 (which is integrally connected to the casting 26) obtained in the runner 28 portion by casting is cut, the rotating shaft 18 as a separate body can be joined to the cut end face. . By the way, in order to cast a sound cast product having no cavity or the like, the temperature gradient of the molten metal in the mold during casting is extremely important. In particular, the temperature gradient tends to be large at the center of the mold and the outside of the mold, which is not preferable. Moreover, the diameter of the chrysanthemum seat portion 16 of the hot impeller 10 is smaller than the diameter of the rear end side base portion 14b of the impeller 10, and the chrysanthemum seat portion 16 has the runner 2 in the cavity 24.
Since it is located at the deepest point from No. 8, casting defects were often caused.

Further, as described above, the rod portion 30 integrally connected to the cast product 26 is cut at an appropriate portion, and the rotary shaft 18 is joined to the cut end face by means such as electron beam welding or rotary friction welding. However, the cut end surface is not always perpendicular to the central axis of the hot impeller 10. Therefore, it is necessary to correct and grind the cut end face and then join the rotary shaft 18 so as to be at right angles to the central axis line of the hot impeller 10, but these require a complicated process and are difficult to be centered. There were inherent difficulties such as.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve the above-mentioned drawbacks inherent in the hot impeller according to the prior art, and to provide a uniform temperature gradient of the molten metal during casting. By holding, it is possible to preferably eliminate the casting defects of the hot impeller used for the turbocharger, and a hot impeller that can facilitate centering when joining a rotating shaft that is a separate body to this hot impeller, An object of the present invention is to provide a method for casting the hot impeller.

[0007]

In order to solve the above-mentioned problems and preferably achieve the intended purpose, the casting hot impeller according to the present invention comprises a main body in which a large number of vanes are formed radially at required intervals. A chrysanthemum seat portion protruding from the center of the tip end side base portion of the main body and a center of the rear end side base portion of the main body,
It is characterized in that it is provided with a joining portion which is allowed to be joined to one end portion of a rotating shaft which is a separate body, and all of them are integrally cast from a super heat resistant alloy material.

Further, in order to preferably cast the above-mentioned casting hot impeller, a method of casting a hot impeller according to another invention of the present application is such that a main body in which a large number of vanes are radially formed at required intervals and a tip side base portion of the main body. Has a cavity for integrally casting a hot impeller having a chrysanthemum seat portion projecting at the center of the main body and a joint portion formed at the center of the rear end side base portion of the main body, and at the portion serving as the chrysanthemum seat portion. Using a mold provided with a communicating runner, the molten metal whose temperature during casting is controlled to be appropriate is poured from the side of the portion that will be the chrysanthemum part through the runner. Is characterized by.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A casting hot impeller and a method for manufacturing the same according to the present invention will be described below with reference to the accompanying drawings, with reference to a preferred embodiment. It should be noted that the same members as those described above with reference to FIG. 4 among the members constituting the hot impeller are designated by the same reference numerals.

As shown in FIG. 1, the hot impeller according to the preferred embodiment has a main body 14 in which a large number of vanes 12 are radially formed at required intervals, and a base 14a on the tip end side of the main body 14 projecting from the main body 14. A chrysanthemum portion 16 having a strip around it and a joint 32 formed at the center of the rear end side base portion 14b of the main body 14, all of which are nickel (Ni) -based super heat-resistant alloy materials. It is integrally cast from. Since the diameter of the joint portion 32 is a portion where the joint portion 32 is joined to the rotary shaft 18 as described later, the chrysanthemum portion 1
The diameter is set to be equal to 6. The joint portion 32 is formed as, for example, a hollow cylindrical portion that extends in the axial direction from the rear end side base portion 14b of the impeller body 14, and the one end portion 1 of the rotary shaft 18 that is a separate body from the hollow cylindrical portion.
8a is joined. In this joining, electron beam welding, rotary friction welding, or the like is performed to achieve complete joining between the impeller body 14 and the rotating shaft 18. However, in the illustrated example, the joining portion 32 is configured as a hollow cylindrical portion extending from the rear end side base portion 14b of the impeller body 14, but may be formed in advance as a flat flat surface.

For the casting of the hot impeller 10 according to the illustrated example, for example, a mold 36 having a cavity 34 as shown in FIG. 2 is used, and a molten metal 38 controlled so as to have an appropriate temperature gradient during casting is poured. It is done by doing. That is, the hot impeller 10 shown in FIG.
A main body 14 in which a large number of vanes 12 constituting the main body 14 are radially formed at required intervals, a chrysanthemum portion 16 projecting from the center of a front end side base portion 14a of the main body 14, and a center of a rear end side base portion 14b of the main body 14. A mold 36 having a cavity 34 in which a portion to be the joint portion 32 formed in the above is defined is used. In this case, the portion to be the joint portion 32 is located at the deepest position in the cavity 34, and the portion to be the chrysanthemum portion 16 is the mold 3
It is located at a portion communicating with the runner 40 provided in FIG.
The reason is that, when the molten metal is poured into the mold 36 as described above, the diameter of the portion to be cast defined in the cavity 34 is small, and the portion is located away from the runner 40. This is because there is a tendency that the temperature gradient tends to be large and there is a fear of causing poor casting. The joint 32
Is set to have a larger diameter than the chrysanthemum portion 16.

Next, a hot impeller is cast by using the mold 36 having the above-described structure. For example, in the breathable mold 36 obtained by the lost wax method, a large number of molds 36 are branched in a tree shape as shown in FIG.
The tree-shaped breathable mold 36 is housed vertically in a decompression chamber 42 connected to a vacuum suction source, and a main runner channel 44 that communicates in common with each mold is opened downward. The molten metal heating container 4 is provided directly below the decompression chamber 42.
6, a molten metal 38 of, for example, a nickel (Ni) -based super heat-resistant alloy that has been melted and reached a required temperature range is stored in the container 46. When a vacuum suction source (not shown) is energized to reduce the pressure in the decompression chamber 42, the tree-shaped mold 36 has air permeability, so that the inside of the mold 36 is also decompressed. Under this condition,
The decompression chamber 42 is vertically lowered together with the tree-shaped breathable mold 36, and the main runner 44 is immersed in the molten metal 38 in the container 46 located immediately below. Then, the molten metal 38 kept under the atmospheric pressure rises in the main runner channel 44 under the reduced pressure suction action in the mold 36, and the main runner channel 44 is divided into left and right branch runners 40 respectively. It enters the cavity 34 of the mold 36.

At this time, the temperature of the molten metal 38 is set to be sufficiently high by being controlled so that the temperature gradient in the cavity during casting becomes appropriate. Moreover, the molten metal 38 is
After the molten metal is poured from the side of the small-diameter chrysanthemum portion 16 (of the hot impeller 10) through the runner 40, it reaches the large-diameter joint portion 32 of the cavity 34, which is the cavity of the mold 36. Since there is no large difference in the temperature gradient at 34, sound casting is performed. After this casting, the mold 36 is dissipated, and the solid rod-shaped portion at the runner 40 is simply cut.
A hot impeller 10 as shown in is obtained. Therefore, as described above, the rear end side base portion 14 of the impeller body 14 is
The one end 18a of the rotating shaft 18, which is a separate body, is brought into contact with the hollow cylindrical portion 32 extending in the axial direction from b, and electron beam welding, rotational friction welding, or the like is performed, so that the main body 14 and the rotating shaft 18 are separated from each other. Is joined. In the illustrated example, the casting by the lost wax technique has been described, but a centrifugal casting method, a gypsum casting method, a full mold (FM) method and the like can also be suitably applied. Further, the joining portion 32 may have a large diameter, and one end portion of the rotary shaft 18 may be fitted into the hollow circular portion in advance, and then electron beam welding may be performed.

[0014]

As described above, according to the casting hot impeller and the method of manufacturing the same according to the present invention, the temperature gradient in the cavity in the mold during casting can be made uniform, and sound casting without defects can be performed. A hot impeller as a product can be manufactured. In addition, when a separate rotating shaft is joined to the hot impeller, the centering of the rotating shaft can be facilitated, and the rotating shaft can be joined accurately.

[Brief description of drawings]

FIG. 1 is a perspective view of a hot impeller according to a preferred embodiment.

FIG. 2 is a cross-sectional view of a breathable mold used to cast a hot impeller according to an embodiment.

FIG. 3 is an explanatory view showing a state in which a tree-like breathable mold obtained by the lost wax method is immersed in a molten metal in a container and the molten metal is sucked under reduced pressure.

FIG. 4 is a perspective view of a hot impeller according to the related art.

FIG. 5 is a cross-sectional view of a mold for casting a hot impeller according to a conventional technique by a lost wax method.

[FIG. 6] After casting by the lost wax method,
It is an external view of a cast product obtained by separating the mold.

[Explanation of symbols]

 10 Hot Impeller 12 Vane 14 Hot Impeller Main Body 14a Main Body Tip Side Base 14b Main Body Rear End Side Base 16 Kikuza 18 Rotating Shaft 32 Joint 34 Cavity 36 Mold 38 Molten Metal 40 Runway

Claims (4)

[Claims] 1. A main body (14) in which a large number of vanes (12) are radially formed at required intervals, and a chrysanthemum portion (16) projecting at the center of a tip side base portion (14a) of the main body (14). , The rear end side base of the body (14)
(14b) is formed at the center of the rotating shaft (18) and a joint (32) that is allowed to be joined to one end (18a) of the rotating shaft (18). A casting hot impeller characterized by being integrally cast. 2. The diameter of the joint portion (32) is equal to that of the chrysanthemum portion (1).
The casting hot impeller according to claim 1, wherein the diameter is set to be larger than the diameter of 6). 3. The joint portion (32) is formed as a hollow cylindrical portion axially extending from a rear end side base portion (14b) of the main body (14), and the rotary shaft (18) is formed in the hollow cylindrical portion. ) One end
The cast hot impeller according to claim 1, wherein (18a) is joined. 4. A body (14) in which a large number of vanes (12) are radially formed at required intervals, and a tip side base portion of the body (14).
A hot impeller having a chrysanthemum portion (16) protruding from the center of (14a) and a joint portion (32) formed at the center of the rear end side base portion (14b) of the main body (14) is integrally cast. Cavity for
Using the mold (36) having the (34) and the runner (40) communicating with the portion to be the chrysanthemum part (16), the molten metal is controlled so that the temperature during casting is appropriate. (38) to the runway (4
A method for producing a cast hot impeller, characterized in that pouring is performed from the side of the portion which becomes the chrysanthemum portion (16) through (0).