JPH03206301A - Radial ceramic turbine rotor - Google Patents

Abstract

PURPOSE:To obtain a rotor having a high mechanical strength absolutely without cracking in a corner part, where the cracking is apt to occur at the time of manufacturing, by forming the corner part being placed in a gas outlet side root part in a connection part between a blade part and a hub part, into a specific curved surface. CONSTITUTION:In a rotor main unit, a hub part 2 is integrally connected to a shaft part 4 while a blade part 1 is integrally formed in this hub part 2. The end surface of a gas outlet side in the hub part 2 is protruded from the gas outlet side root part of the blade part 1. Here, a corner part 3 of the gas outlet side root part in a connection part between the blade part 1 and the hub part 2 is formed into a curved surface of 3Rmm or more. In this way, a turbine rotor of large mechanical strength, with no crack generated at all in the corner part 3 where the cracking is apt to occur at the time of manufacturing, is obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a mechanically strong radial ceramic turbine rotor that does not have a crank at the root on the gas outlet side of the joint between the blade section and the hub section. .

(Prior Art) Silicon ceramics such as silicon nitride, silicon carbide, and sialon have excellent heat resistance and thermal shock resistance, and are also lightweight, so they are attracting attention as structural materials for gas turbine engines, diesel engines, etc. In particular, radial turbine rotors made of these ceramic materials are lighter than metal turbine rotors, can be used at high temperatures, and have extremely high thermal efficiency, so they are attracting attention as turbocharger rotors for automobile engines or gas turbine rotors. ing.

(Problems to be Solved by the Invention) Since the radial turbine rotor has a complicated shape, it is usually shaped by an injection molding method or the like. However, in order to use the ceramic raw material for injection molding, it is necessary to add a large amount of resin, wax, etc. as a plasticizer. When Wankus, etc. is removed by heating or firing, due to its structure, the thickness of the base on the gas outlet side of the joint between the blade and the hub changes rapidly, resulting in uneven deresin and wax removal, which causes the formation of a pre-shaped body. The density of the airfoils is non-uniform, and local shrinkage differences occur during degreasing or burning, resulting in tensile stress that tends to cause cranks at the base of the joint between the blade and the hub on the gas outlet side.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned drawbacks of the conventional technology. This relates to a radial-type ceramic turbine rotor that was completely destroyed by fire, and includes a shaft portion, a hub portion integrally connected to the cough shaft portion, and a blade integrally formed with the hub portion. In a radial turbine rotor, the end face of the hub part on the gas outlet side protrudes from the root part of the blade part on the gas outlet side,
The rotor is a radial type ceramic turbine rotor, in which a fillet portion of a root portion on the gas outlet side of a joint portion between the blade portion and the hub portion is shaped into a curved surface of 3RfflII1 or more.

In addition, "r3Rmm or more" in the present invention indicates that the curved surface of the fillet part is "R of 3 or more" as shown in JIS BO703-1962.

(Function) To describe the more detailed structure of the present invention regarding the manufacturing method, the raw material is at least one selected from silicon nitride, silicon carbide, sialon, or a substance that produces these by sintering, preferably any one of them. In the case of silicon nitride, Yz(h, MgAl 2041 Mgo, Ce
Sintering aids such as Oz, SrO, and in the case of silicon carbide, B
Sintering aids such as E, Al, B, and C are added and mixed to prepare a ceramic raw material for injection molding. As shown in FIG. 1, the fillet part 3 at the base of the gas outlet side of the joint between the wing part 1 and the hub part 2 after burning is 3Rmm or more, preferably IOR mark or less, more preferably 4Rmm to 6Rmm. The ceramic raw material is injected and shaped using an injection mold that is adjusted to form a curved surface.

Next, the resin and plasticizer such as Wanox contained in the molded body obtained by injection molding are removed by heating to perform degreasing.

The heating conditions vary depending on the type and content of the resin and wax, etc., but the temperature is raised at a rate of 100°C/hr or less, preferably 10°C/hr or less, to a temperature of approximately 300 to 600'C. Heat it up and degrease it.

After degreasing, calcination and hydrostatic pressurization are performed as necessary. The calcination is carried out at a temperature of 800 to 1200°C in order to make the shaped body easier to handle and to give it the strength necessary for machining. In addition, for hydrostatic pressurization, the degreased body is covered with an elastic bag and
This is done at a pressure of ~5000 kg/cm'' to densify the preformed body.The preform is then densified at a temperature such as 1600 to 200 kg/cm, at which each material is completely sintered, depending on the type of raw material.
Baking is performed at 200°C for about 10 to 200 minutes. In addition, silicon nitride,
When using raw materials producing silicon carbide, sialon, etc., not only the firing temperature but also the atmosphere are extremely important; for example, in the case of silicon nitride, the firing is performed in a nitrogen atmosphere, and in the case of silicon carbide, the firing is performed in an argon atmosphere. Then, by firing, the fillet part 3 at the base of the gas outlet side of the joint between the wing part 1 and the hub part 2 becomes 3R.
The radial ceramic turbine rotor of the present invention is obtained which has no cracks in the fillet portion of the root portion having a curved surface of mm or more. The reason why the fillet part of the gas outlet side base of the joint between the blade and the hub after firing is limited to a curved surface of 3Rmm or more is that if it is a curved surface without a groove of 3Rmm, the connection between the blade and the hub will be reduced. This is because the thickness of the joint portion on the gas outlet side rapidly changes, resulting in uneven degreasing, and cracks occur due to stress caused by the non-uniform degreasing. Also 1
If it is larger than 0 Rmm, the aerodynamic characteristics of the rotor tend to deteriorate, so it is preferably 10 Rmm or less.

(Example) Next, the effects of the present invention will be explained based on examples.

As a sintering aid to 100 parts by weight of SiJ4 powder with an average particle size of 0.5μ? 3 parts by weight of lg0, 2 parts by weight of SrO, Ce
2 parts by weight of Oz and 15 parts by weight of polypropylene resin as a plasticizer were added and mixed and kneaded to prepare a ceramic material for injection molding. In order to obtain a radial turbine rotor in which the maximum diameter of the blade is 60 mm and the fillet on the gas outlet side of the joint between the rear blade part and the hub part has a curved surface with the numerical values shown in Table 1, The ξ7 raw material was injection molded using a mold adjusted to have the predetermined dimensions. Thereafter, these preforms were heated to 500°C at a heating rate of 5°C/hr.
After raising the temperature to 500°C for 10 hours to degrease, place the defatted Kai-shaped body in a rubber bag and incubate at 300°C.
It was densified by hydrostatic pressurization at a pressure of 0 kg/crn, and then baked at 1720°C for 30 minutes in a nitrogen atmosphere. Table 1 shows the occurrence of cranks in the fillet of the rotor after baking. The rotor of the present invention (Samples 1 to 4) in which the fillet part 3 on the gas outlet side of the joint between the burned rear wing part and the hub part has a curved surface of 3 Rmm or more,
While no cranking was observed, the curved rotors with fillet 3 smaller than 3Rmm (Samples 5 and 6) had a fillet on the gas outlet side of the joint between the blade and hub. In both cases, cranks with lengths of 3 mm and 6 mm occurred, respectively. Then, in order to conduct a rotation test using these samples, the dynamic unbalance of the rotor was adjusted to 0.05 gcm by grinding, and then a metal shaft was attached and the dynamic unbalance of the entire rotor was further adjusted to 0.001 gcm. The balance was adjusted and the test was conducted while gradually increasing the number of rotations using a rotation tester. Figure 2 shows the numerical values in Table 1 partially supplemented with data from the test. 1st
As is clear from the table and FIG. 2, the rotor of the present invention (
Samples 1 to 4) are 150.00O RPM (7)
The rotors other than the present invention (Sample 5 and Sample 6) did not break due to the rotational speed of 70. It was destroyed at a rotation speed below OOORPM.

As described above, the radial type ceramic turbine rotor of the present invention and the manufacturing method thereof are such that the fillet part of the gas outlet side root of the joint between the blade part and the hub part of the rotor is 3Rmm after being sintered. By integrally injecting or shaping the rotor to form the curved surface described above, a turbine rotor with strong mechanical strength can be obtained, with no cracks occurring at the root fillet where cranking is most likely to occur during manufacturing. It can be used as a radial type ceramic rotor for turbocharger rotors for diesel engines and gasoline engines, gas turbine engine rotors, etc., and is extremely useful industrially.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram specifically explaining the radial turbine rotor of the present invention. Figure 2 shows the size of the curved surface of the fillet, presence or absence of cranks, length of cracks, and rotational speed shown in Table 1. Figure 3 is a diagram showing the ceramic turbine rotor of the present invention incorporated into a turbocharger. 1... Wing part 2... Hub part 2A...
Hub tip 2B... Hub protrusion 3... Fillet 4... Shaft 5... Gas outlet side

Claims (1)

[Claims] 1. Consists of a shaft portion 4, a hub portion 2 integrally connected to the shaft portion 4, and a wing portion 1 integrally formed with the hub portion 2,
In a radial turbine rotor having a shape in which the end face of the gas outlet side 5 of the hub part 2 projects from the gas outlet side root part of the blade part 1, the gas outlet side of the joint part between the blade part 1 and the hub part 2 A radial ceramic turbine rotor characterized in that a fillet 3 at the base is formed into a curved surface of 3 Rmm or more.