JPH0635806B2 - Method for manufacturing ceramic star bin wheel - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a ceramics turbine wheel used for a turbocharger of an automobile or the like. The ceramics turbine wheel is made by sintering ceramics, and has a sintering shaft portion and a sintering wheel portion rotated by the sintering shaft portion.

[Prior Art] Recently, ceramic turbine wheels have been developed for reasons such as improving transient response and raising driving temperature to improve fuel efficiency.

Conventionally, when manufacturing turbine wheels from ceramics, a forming process of forming a ceramic unsintered turbine wheel into a predetermined shape, sintering the unsintered turbine wheel at high temperature And a finishing step of finishing the sintering shaft portion of the sintering turbine wheel into a regular size and shape.

However, in the above-described manufacturing method, the sintered shaft portion having a small diameter is easily bent during sintering. It is not easy to accurately finish the warped sintered shaft portion into a proper size and shape in the finishing process. If it is not finished correctly, the turbine wheel will have problems such as swinging and uneven rotation during driving.

For example, the conventional typical manufacturing method is the first molding step,
As shown in FIG. 4, the unsintered shaft portion 1 and the unsintered wheel portion 2
An unsintered turbine wheel 3 having a and is molded from ceramics. Next, a center hole is machined at the end of the shaft portion 1 and the hub end of the wheel portion 2. Then, as shown in FIG. 4, the support tool P is fixed to the center hole at the end of the unsintered shaft portion 1, and the support tool Q (support (The same as the tool P) is fixed, and the outer peripheral surface of the unsintered shaft portion 1 is roughened in that state.

Next, in the sintering step, the unsintered turbine wheel 3 is sintered at a high temperature to form a sintered turbine wheel 3a. During sintering, the sintering shaft portion 1a is easily bent from the root portion P ₁ (shown in FIG. 5). The line R ₁ in FIG.
The center line of the warped sintered shaft portion 1a is shown.

Next, in the finishing step, as shown in FIG. 5, the support tools P and Q are fixed again to the center hole used in the first forming step in the same manner as described above, and in that state, the finishing process of the sintering shaft portion 1a is finished. I am going to do.

In this finishing process, the center hole used in the first molding process is used. Therefore, when the sintering shaft portion 1a of the sintering turbine wheel 3a is warped, as shown in FIG. 5, the sintering is performed with the hub back surface 4 of the sintering turbine wheel 3a inclined at an angle Θ. The shaft portion 1a will be finished. Therefore, as shown in FIG. 6, the hole 5 of the drive shaft 5 is
When the sintered shaft portion 1a is fitted to a, the hub back surface 4 is inclined by the angle Θ. Therefore, the center of mass P of the sintered wheel portion 2a is
₂ (see Fig. 5) also shifts by r. Therefore, there arises a problem of causing an imbalance with respect to the rotation center axis according to the deviation r. To suppress this, correction work may be performed, but this correction work is quite complicated and requires a long machining time. Further, when mounted on the turbocharger, the distance e with respect to the nozzle portion 8 of the scroll 7 of the turbine housing 6 is increased.
₁ and e ₂ do not match (e ₁ ≠ e ₂ ). Therefore, the ceramics turbine wheel swings at the time of driving, causing uneven rotation, and consequently, problems such as deterioration of aerodynamic performance of the turbine wheel.

[Problems to be Solved by the Invention] According to the present invention, even when the sintering shaft portion is bent during sintering, the sintering shaft portion can be easily finished to a predetermined size and shape. , Which causes the above-mentioned imbalance,
Another object of the present invention is to provide a method for manufacturing a ceramics turbine wheel capable of suppressing the occurrence of problems such as swinging, uneven rotation, and deterioration of aerodynamic performance.

[Means for Solving Problems] A method for manufacturing a ceramics turbine wheel according to the present invention comprises a ceramic unsintered shaft portion thicker than a regular dimension and the unsintered shaft portion integrally formed. A forming step of forming an unsintered turbine wheel having a formed unsintered wheel part, and sintering the unsintered turbine wheel body to form a sintered turbine wheel having a sintered shaft part and a sintered wheel part. A sintering step to obtain, an axis setting step of setting an axis for finishing the sintering shaft portion on the sintering shaft portion with reference to a rotation center of the sintering wheel portion, A finishing step of finishing the sintered shaft portion to a regular size with the shaft core as a processing standard is sequentially carried out.

In the forming step, a green turbine wheel having a green shaft portion and a green wheel portion integrally formed with the green shaft portion is formed of ceramics. here,
"Unsintered wheel part" means a member having a wing part, which is unsintered by simply molding ceramics into a predetermined shape. “Unsintered shaft portion” means a member that serves as a support shaft of the unsintered wheel portion and is simply sintered ceramics and not sintered. The green shaft is thicker than the regular size. The amount of thick wall is determined in consideration of the amount of warpage due to sintering. Therefore, when the amount of warpage due to sintering is large, the amount of thickening is usually set relatively large. When the amount of warp is small, the amount of thickening is usually set to be relatively small. As the ceramics, generally used materials can be used, but specifically, silicon nitride (Si ₃ N ₄ ) and silicon carbide (SiC) can be used.

In the sintering step, as before, the unsintered turbine wheel is sintered to obtain a sintered turbine wheel having a sintered shaft portion and a sintered wheel portion. The sintering temperature and the sintering time are appropriately set depending on the type of ceramics. When the sintering process is performed, the sintering shaft portion is often deformed with respect to the sintering wheel portion due to the influence of the sintering as described above, and is slightly bent.

In the axis setting step that characterizes the present invention, the axis for finishing the sintering shaft is set on the sintering shaft with reference to the rotation center of the sintering wheel. The "rotation center of the sintered wheel portion" is the rotation center of only the sintered wheel portion, and means an axis that does not cause imbalance when the sintered wheel portion rotates. The center of rotation of the sinter wheel can be defined as a line passing through the center point of the hub tip of the sinter wheel and perpendicular to the back of the hub. Further, the center of rotation of the sintered wheel portion can be regarded as the center of the radial dimension of the sintered wheel portion.

In the shaft center setting process, "to set the shaft center for the finishing process of the sintered shaft based on the center of rotation of the sintered wheel" means to extend the center of rotation of the sintered wheel to the end of the sintered shaft. However, it means that the extended portion is used as a shaft core for finishing the sintering shaft. Here, a shaft core processing tool that is coaxial with the rotation center of the sintering wheel portion and that rotates coaxially with the rotation center is provided, and the shaft core processing tool is used to cut the tip of the sintering shaft portion. The core setting step can be performed. The cutting of the front end of the sintering shaft portion is performed by cutting the outer peripheral end surface of the front end of the sintering shaft portion into a truncated cone shape. Further, in some cases, the cutting of the tip of the sintered shaft portion may be performed by cutting the end surface of the tip of the sintered shaft portion into a center hole shape which is generally used in the processing of a metal shaft portion.

In the finishing step, the sintered shaft portion is finished to a regular size by using the finishing shaft core as a processing reference. As a result, the thick portion formed on the unsintered shaft portion in the molding step is removed. Conventional finishing tools can be used in this step.

[Operation of the Invention] In the manufacturing method of the present invention, the shaft for finishing the sintering shaft portion is set to the sintering shaft portion based on the rotation center of the sintering wheel portion. Therefore, even if the sintering shaft portion is warped during the sintering process, the shaft for finishing the sintering shaft portion can be set without being affected by the bending of the sintering shaft portion.

In the present invention, since the sintered shaft portion is finished to a regular size with the above-described finishing shaft core as the processing reference, the sintered shaft portion is hardly affected by the bending of the sintered shaft portion. Can be finished.

[Effects of the Invention] In the manufacturing method of the present invention, as described above, the sintered shaft portion can be finished without being substantially affected by the bending of the sintered shaft portion. Therefore, the imbalance that has conventionally occurred in the sintered wheel portion can be suppressed as much as possible. Therefore, the subsequent correction work can be eliminated or can be significantly reduced. Furthermore, it is possible to suppress problems such as swinging of the sintered wheel portion, uneven rotation, and deterioration of aerodynamic performance of the turbine wheel, which have been conventionally caused.

[Embodiment] FIGS. 1 and 2 are views for explaining the steps of the present invention.

In the molding step, the unsintered turbine wheel 30 is molded from silicon nitride (Si ₃ N ₄ ) as in the conventional case. The unsintered turbine wheel 30 has the unsintered shaft portion 10 as in the conventional case.
And a green wheel portion 20 formed integrally with the green shaft portion 10. The unsintered wheel portion 20 is the hub 2
1 and wings 22 formed on the hub 21.

Then, similarly to the conventional method, first, a center hole is machined and formed in the end portion of the unsintered shaft portion 10 and the end portion of the hub 21 as a reference for processing the unsintered shaft portion. Then, the support tool P is fixed in the center hole at the end of the unsintered shaft 10, and the support tool Q is fixed in the center hole at the end of the hub 21. Roughing the outer peripheral surface. In the sintering process, as before,
The unsintered turbine wheel 30 is sintered to form a sintered turbine wheel 30a having a sintered shaft portion 10a and a sintered wheel portion 20a. The sintering of this example is 1750
It was carried out at ℃ for 4 hours. Under the influence of sintering, the sintering shaft portion 10a may be warped from the root portion P ₁ of the sintering shaft portion 10a as a starting point as shown in FIG. In FIG. 1, the alternate long and short dash line R ₁ indicates the center line of the curved sintering shaft portion 10a.

In the axial core setting process that characterizes this example, the sintered wheel 2
An axis Y for finishing the sintering shaft portion is set on the sintering shaft portion 10a with reference to the rotation center X of 0a. In the case of this example, this step is performed as follows. That is, the support tool Q is fixed to the center hole 40 at the tip of the sintered wheel portion used in the previous molding step, and the support tool S having a flat tip is attached to the hub 21.
It is closely fixed to the back surface 24 of the. Here, the support tool S forms a plurality of contact surfaces on the entire circumference or on the circumference, and is provided concentrically around the support tool Q. If the above is done, as shown in FIG. 1, the bab 2 of the sintered wheel portion 20a is
The back surface 24 of 1 is in the vertical direction. The rotation center X of the sintered wheel portion 20a is defined as a line passing through the center point of the center hole 40 at the tip of the hub 21 of the sintered wheel portion 20a and perpendicular to the back surface 24 of the hub 21.

By the way, in FIG. 1, 50 is an example of a shaft core processing tool. This is held coaxially with the rotation center X of the sintered wheel portion 20a and rotates coaxially with the rotation center X. The shaft core processing tool 50 is operated in the direction of arrow A along the rotation center X of the sintered wheel portion 20a. Then, the outer peripheral end surface of the front end of the sintered wheel portion 20a is cut into a truncated cone shape as shown in FIG. 1 by the axial core processing tool 50, and a truncated cone shaped cutting portion 51 is formed. As a matter of course, various methods other than this example can be considered for the processing for forming the truncated cone shape. Next, the support tool T which is coaxial with the support tool Q is operated to fix the cutting portion 51 by the support tool T having the hole 52.

If the support Q and the support T are fixed in this way,
The shaft Y for finishing the sintered shaft portion is composed of the sintered wheel portion 2
It is set on an extension of the rotation center X of 0a. Here, even if the sintered shaft portion 10a is bent, the axis Y
Is aligned with the center X of rotation of the sintered wheel portion 20a.

In the finishing step, as described above, with the rotation center X of the sintering wheel portion 20a and the axis Y for finishing the sintering shaft portion aligned, the sintering shaft portion 10a of Finish the outer peripheral surface to the specified size.

According to such a manufacturing method, with respect to the rotation center X of the sintered wheel portion 20a and the axis Y for finishing the sintered shaft portion, the back surface 2 of the bab 21 of the sintered wheel portion 20a is formed.
4 can be made vertically.

The turbine wheel manufactured by the above manufacturing method,
As shown in FIG. 3, when it is installed in the hole 5a of the metallic drive shaft 5, the rear surface 24 of the hub 21 of the sintered wheel 20a is attached.
Is perpendicular to the axis of the drive shaft 5. Therefore, in this example, unlike the prior art shown in FIG. 6, since the inclination of the back surface 24 of the hub 21 of the sintered wheel portion 20a is suppressed, the occurrence of balance is suppressed. Therefore, unlike the prior art, the subsequent correction work is unnecessary or can be significantly reduced. It is possible to suppress the occurrence of problems such as swinging and uneven rotation during driving, and consequently to suppress the occurrence of problems such as deterioration in aerodynamic performance of the turbine wheel.

In this example, the center hole 41 formed at the tip of the sintering shaft portion 10a is left in the molding process. The amount of eccentricity of the center hole 41 with respect to the axis Y makes it possible to estimate the amount of warpage of the sintered shaft portion 10a.

[Brief description of drawings]

1 to 3 show one embodiment of the present invention, FIG. 1 is a side view showing a shaft center setting step, FIG. 2 is a side view showing a finishing step, and FIG. 3 is a turbine wheel rotating shaft. FIG. 3 is a side view showing a state in which the state of being incorporated into is partially broken. 4 and 5 are views showing a conventional manufacturing method.
FIG. 5 is a side view showing a molding process, FIG. 5 is a side view showing a state in which a conventional sintered turbine wheel is fixed by a support tool,
FIG. 6 is a partially cutaway side view showing a state in which the manufactured conventional turbine wheel is incorporated in a drive shaft, and FIG. 7 is an enlarged side view showing a state in which a conventional turbine wheel is incorporated in a turbocharger. Is. In the figure, 10a is a sintered shaft portion, 20a is a sintered wheel portion, 3
Reference numeral 0a represents a sintered turbine wheel, X represents the center of rotation of the sintered turbine wheel, and Y represents an axis for finishing.

Claims (5)

[Claims] 1. A non-sintered turbine wheel made of ceramics, comprising a non-sintered shaft portion thicker than a regular size and a non-sintered wheel portion integrally formed with the non-sintered shaft portion. A forming step of forming, a sintering step of sintering the unsintered turbine wheel to obtain a sintered turbine wheel having a sintered shaft portion and a sintered wheel portion, and a rotation center of the sintered wheel portion as a reference As an axial core setting step for setting a shaft for sintering shaft finishing to the sintering shaft, and for finishing the sintering shaft to a regular dimension using the shaft shaft for finishing as a processing reference. A method for manufacturing a ceramic turbine wheel, which comprises sequentially performing a finishing process. 2. The ceramic according to claim 1, wherein the center of rotation of the sintered wheel portion is defined as a line which passes through the center point of the hub tip of the sintered wheel portion and is perpendicular to the back surface of the hub. Turbine wheel manufacturing method. 3. A shaft core for finish machining is a shaft core machining tool which is coaxial with the center of rotation of the sintered wheel and rotates coaxially with the center of rotation, and the end of the sintered shaft is cut or ground. The method for manufacturing a ceramics turbine wheel according to claim 1, wherein the ceramic turbine wheel is formed by performing (the following description is represented by cutting). 4. The manufacturing method according to claim 3, wherein the cutting of the front end of the sintered shaft portion is performed by cutting the outer peripheral end surface of the front end of the sintered shaft portion into a truncated cone shape. 5. The method of manufacturing a ceramics turbine wheel according to claim 3, wherein the tip of the sintered shaft portion is cut by cutting the tip of the sintered shaft portion into a center hole shape.