JPS62119180A - Manufacture of ceramic shafted turbine blade - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a turbine impeller with an IIMII used in a turbocharger for an internal combustion engine, a gas turbine, etc. The present invention relates to a method for connecting a blade wheel and a metal shaft member.

Comparing to metals, ceramics have superior heat resistance and strength comparable to metals1. For example, the bending strength of silicon nitride (SLsN4) ceramics, which has been attracting attention in recent years, is Although it has a bending strength of 90 to 9 f/m' at room temperature, it still has a bending strength of 80 Kgf/m' even at 1000°C.

Ceramics having such excellent heat resistance are being used in place of metal members for various mechanical parts that are subject to severe usage conditions. One example is a turbine wheel used in a turbocharger for an internal combustion engine. A turbocharger is a device that precompresses intake air or air-fuel mixture by using engine exhaust energy to turn a tillage turbine and using that power to drive a compressor. Since this is a member that is exposed to heat, it is effective to form it from Hiramix, which has excellent heat resistance.

As a conventional method for manufacturing a ceramic turbine wheel with a shaft, for example, as shown in FIG. Cylindrical body made of low thermal expansion coefficient metal 0
3 are fitted and soldered, and the collar 05 of the shaft member 04 formed of a metal different from the above metal is fitted into the cylindrical body 03, and then electron beam welding is performed from the direction of the arrow at the fitting part, There is a method of joining the cylindrical body 03 and the shaft member 04.

°　'l　　.

However, when using this method, the rigid cylinder body 0
Residual tensile stress (thermal stress) in the direction perpendicular to the fitting surface of the cylindrical body 03 and the collar 05 is generated in the welded part restrained by 3,
Cracks are likely to occur in welded parts.

It was.

An object of the present invention is to ensure the soundness of a welded portion of a metal shaft member attached to a ceramic turbine wheel.

The purpose of this is to fit a cylindrical body made of metal whose coefficient of thermal expansion is close to that of the ceramics forming the blade wheel onto the shaft protrusion formed at the rotation center of the ceramic turbine wheel. Then, the entire fitting surface is soldered, and a shaft member made of a metal different from the metal is attached to the end face of the cylinder, and a plane that intersects at right angles to the rotation center line of the turbine blade wheel is formed. This is achieved by performing electron beam welding from the outer periphery at the contact surface along the cylindrical body and the shaft member.

To solder a gold B cylinder to the shaft protrusion of a HIRAMIX turbine wheel, fit the metal cylinder onto the shaft protrusion, and apply solder material to the same part with the end of the shaft protrusion facing upward. Then, the turbine wheel is placed in a vacuum furnace in that position and heated to the soldering temperature, and the molten solder material permeates through the mating surface of the shaft protrusion and the metal cylindrical body. Leave to cool. In addition to this heating and cooling, the turbine wheel as a completed product with a metal shaft member attached thereto is heated to an operating temperature when it is assembled into an m-leaf and used, and is cooled down after use.

However, the coefficient of thermal expansion (α) of ceramics is considerably smaller than that of general metals, such as silicon nitride (SLs).
In N4), α = 2.6 to 4.5 x 10-''7°C, so if the metal cylinder fitted to the shaft protrusion of the turbine wheel is made of a normal metal with a large coefficient of thermal expansion, the shaft The difference in expansion and contraction between the protrusion and the cylindrical body is too large and will have an unfavorable effect on the shaft protrusion.Therefore, in the present invention, the coefficient of thermal expansion (α) is determined by the thermal expansion of the ceramic forming the impeller. Metals with values close to the ratio (α), such as copal (NL2
3-30wt%, Co 17-30wt%, Mn
O, 6~0.8wt%, balance Fe: Ct=4.4~
5.2×10′/° C.) (trade name) to form a cylinder.

Branch JLJI The present invention is carried out by the following procedure.

■ Ceramic (e.g. β-8L3N4, α=3.0~5,
Ox 10'6/ 'C) "A A cylindrical body 14 made of a low thermal expansion coefficient metal (eg, Copal (trade name)), which is slightly longer than the shaft projection 12, is fitted into the shaft projection 12 of the turbine wheel 10. Match.

However, this fitting portion is provided with a slight gap to allow entry of the solder material.

Next, as described above, granular solder material is supplied to the surface of the shaft projection 12, the whole is placed in a vacuum furnace and heated to the soldering temperature, and the molten solder material is applied to the shaft projection 12 and the cylindrical body 12. After allowing the material to seep between the mating surfaces of the material, it is allowed to cool.

■ The protrusion 20 is fitted to the outer end of the cylindrical body 14 which is fitted and soldered to the shaft protrusion 12.
Attach the collar 18 of the shaft member 16 (IS G4105-3CH420 material) to the abutment surface included in a plane that intersects at right angles (including cases where it is almost at right angles) to the rotation center line, using arrow B. Electron beam welding is performed from the direction to the entire circumference (see FIGS. 2 and 3. However, FIG. 3 is a view taken along the line ■-■ in FIG. 2).

Since no restraining force acts on the welded joint W of the turbine impeller 10 with the shaft member 16 obtained by the above procedure as in the example shown in FIG.
No residual tensile stress is generated in the direction parallel to the rotation center line, and cracking due to residual thermal stress can be effectively prevented.

Furthermore, by forming the cylindrical body 14 to be longer than the shaft protrusion 12, the solder joint part and the weld joint part W can be separated from each other, and the influence of welding heat on the solder material can be sufficiently reduced. can.

Furthermore, in the structure in which the collar 18 is brought into contact with the outer end of the cylindrical body 14 and the two are welded, compared to the example shown in FIG.
Since the welded joint is separated from the center of rotation, the torque transmission load is small and durability is improved.

As is clear from the above explanation, the shaft protrusion formed at the center of rotation of the ceramic turbine impeller has a coefficient of thermal expansion close to that of the Hiramix that forms the impeller. A cylindrical body formed of a metal of A ceramic turbine blade with a shaft, characterized in that a cylindrical body and a shaft member are joined by electron beam welding from the outer periphery at the contact surface along a plane perpendicular to the rotation center line of the vehicle. A method of manufacturing a car was proposed.

According to this method, there is no undesirable restraining force on the welded joint between the cylinder and the shaft member, and no residual tensile stress is generated in the direction perpendicular to the welding surface, resulting in a sound welded joint without vj deviation. 1q can be obtained.

[Brief explanation of drawings]

Figure 1 is publicly known! ! ! Fig. 2 is a cutaway side view of a main part of a ceramic turbine wheel with a shaft obtained by the manufacturing method of the present invention; Fig. 3 is a cutaway side view of a main part of a ceramic turbine wheel with a shaft obtained by the method of the present invention. It is a view taken along the line ■-■ in FIG. 2. 10... Turbine impeller, 12... Shaft protrusion, 14...
・Cylindrical body, 16... Shaft member, 18... Tsuba, 20...
・Rumps.

Claims (1)

[Claims] A cylindrical body made of a metal whose coefficient of thermal expansion is close to that of the ceramics forming the blade wheel is fitted onto the shaft protrusion formed at the center of rotation of a ceramic turbine wheel. All fitting surfaces are soldered together, a shaft member made of a metal different from the above metal is attached to the end face of the cylinder, and its contact is made along a plane perpendicular to the rotational center line of the turbine wheel. A method of manufacturing a ceramic turbine blade wheel with a shaft, characterized in that electron beam welding is performed from the outer periphery at the contact surface part to join the cylinder and the shaft member.