JPH02149477A - Method for joining ceramic rotor and metallic shaft - Google Patents

Abstract

PURPOSE:To prevent the stress deviation at the joining part by inserting the projecting insertion part formed in the groove of a ceramic rotor into the recessed engaging part of a metallic shaft member with a first stress relieving layer formed on its inner surface, forming a second stress relieving layer in the gap between both parts, and applying shrinkage fitting. CONSTITUTION:The inner surface of the recessed engaging part 14 (metal ring) of the metallic shaft member 10 is plated with a first soft metal (e.g. Cu) to form the first stress relieving layer 22. The surface is lapped to uniformize the plating thickness, and then the projecting insertion part 18 formed in the groove 20 of the ceramic rotor 16 is inserted. The engaging part 14 is heated to a shrinkage fitting temp., the molten second soft metal (e.g. Cu-Ag alloy) is filled into the gap between the engaging part 14 and the insertion part 18 and into the groove 20 to form a second stress relieving layer 24, the engaging part 14 is shrinkage-fitted on the insertion part 18, and the engaging part 14 is welded to the rotating shaft 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of joining a ceramic rotating body and a metal shaft member used in turbochargers, gas turbines, drills, etc.

(Conventional technology) Ceramic members, especially sintered bodies of norconia, silicon carbide, silicon, and silicon nitride, have high-temperature strength, wear resistance,
It has excellent heat resistance, low specific gravity, and good response, making it suitable for rotating bodies such as turbochargers, gas turbines, and drills. However, ceramics are generally hard, brittle, have poor formability, and lack toughness, so they cannot be used as members that are subject to repeated bending stress during rotation, such as shafts.

Therefore, it has been considered to construct a shaft member such as a rotating shaft from a metal material with high strength, excellent toughness and workability, and to combine the ceramic rotating body and the metal shaft member.

Conventionally, methods for joining a ceramic rotating body and a metal shaft member include fitting a convex fitting part of the ceramic rotating body and a concave fitting part of a metal shaft member, that is, 1] - shrink fitting, cold fitting. There are known methods of making a conjugate using the following methods.

However, in this method, if the machining accuracy of the ceramic member is poor, a uniform contact surface with the metal member cannot be obtained, and stress is unevenly distributed, which tends to cause 1R fracture. Therefore, an invention described in Japanese Patent Application Laid-Open No. 5855/1983 was proposed. Therefore, this is a method of plating the fitting part of the metal j1≦material with tth soft metal.

In addition, as a method of joining a ceramic member and a metal member, a method is used that first applies a metal plate or metal ligth to the joint part of the ceramic member, and then joins it with a metal 73 (material) by brazing. Since this method requires highly accurate coaxiality between the ceramic material and the metal member, the joints of the ceramic members are generally polished.
- to be lost.

This caused a decrease in bonding strength. In order to overcome this drawback, Jitsuma I16293343 was proposed.
In the fourth proposal of the publication, the polished part of the ceramic member is inserted into a hole formed in a flat metal material, the gap in the insertion part is filled with a brazing material, and the parts are joined through the brazing material. 4.

1 Problem to be Solved by the Invention 1 However, in the rotating body, such as a turbo rotor, constructed according to the invention of JP-A-58-55382, 1
When rotating at a speed of t, if the balance is not completely maintained, bending stress will be concentrated on the ceramic rotor paste 51 due to the eccentric load, causing problems that may lead to destruction. In order to avoid this, increasing the p/m of the plating layer reduces the important shrink fit force.

In addition, the combined body constructed according to the η plan of Japanese Utility Model Publication No. 62-93343 requires polishing and simple jointing by brazing, which requires minute condition control. However, it has the disadvantage that it requires a large number of losses to manage IX conditions.

The present invention has been made to solve the above-mentioned problems regarding the method of joining a ceramic rotating body and a metal shaft member. It is an object of the present invention to provide a method for joining a ceramic rotating body and a metal shaft member in which the shrink fit force does not decrease even when the stress relaxation layer is thickened in order to avoid excessive eccentricity.

[Means for Solving the Problems] A method of coupling a ceramic rotating body and a metal shaft according to the present invention includes concave fitting of a metal shaft member: plating a first soft metal on the inner surface and forming a first stress relaxation layer. The process of inserting the concave fitting part of the metal shaft member into the groove-formed convex insertion part of the ceramic rotating body, and the process of inserting the concave fitting part of the metal shaft member into the groove-formed convex part of the ceramic rotary body. A second soft metal in a molten state is injected into the gap of the convex fitting portion of the body and solidified to form a second stress relaxation layer, and the convexity of the ceramic rotating body is injected into the concave fitting portion of the metal shaft member. The gist is that the shape-fitting part consists of four degrees of shrink-fitting.

The concave fitting portions of the metal shaft member form four parts into which the convex fitting portions of the ceramic rotating body fit, and are usually formed in a ring shape or a cylinder shape and are coupled to the rotating shaft by welding. Since ceramics generally have a smaller coefficient of thermal expansion than metal materials, a metal material having a low coefficient of thermal expansion and high temperature strength, such as ink [1], is used for this concave first junction.

The first soft metal forming the first stress relaxation layer may be any metal that is soft enough to sufficiently absorb the stress of is used. Further, the first soft metal needs to have a melting point that is 1 minute higher than the shrink fit temperature. The thickness of the first stress relaxation layer formed by plating is preferably 50 to 200 μm.

Further, the second soft metal forming the second stress relaxation layer is
The melting temperature is close to the shrink-fitting temperature, and at the shrink-fitting temperature, it is possible to melt and fill the 4" gap created when the concave fitting part of the metal shaft member is inserted into the convex fitting part of the ceramic rotating body.
It is necessary that Ag, ): or Cu be I
: A soft metal is used as a component. The thickness of the second stress relaxation layer is preferably 10 to 200 lt.

The grooves formed in the convex fitting part of the ceramic rotary body may be in the direction perpendicular to the axis of the ceramic rotary body or in the direction of skewering, and the depth of the groove is determined according to the convex fitting part of the convex Ii1 body. The depth may be sufficient as long as it is sufficient to act as a pull-out or rotation stopper.

Effect] By plating the first soft metal on the inner surface of the concave fitting part of the metal shaft 4< material to form a first stress relaxation layer, when the convex fitting part of the ceramic rotating body is shrink-fitted. , local plastic deformation of the first stress relaxation layer reduces the stress at the joint.
A uniform joint can be obtained.

In addition, if a second soft metal is melted and filled into the gap of the fitting part during shrink fitting and solidified to form a second stress relaxation layer, J(
By the process of shrink-fitting the convex fitting part of the ceramic rotating body into the concave fitting part of the metal shaft member, the shrink-fitting force between the metal shaft member and the ceramic rotating body is reduced by the solidification of the second soft metal. This appears as a difference in thermal contraction between the inserted part of the metal shaft member and the inserted part of the ceramic rotating body from temperature to room temperature. Moreover, this shrink fit force is determined by the solidification temperature of the second soft metal, and therefore does not depend on the thickness of the stress relaxation layer. Therefore, local eccentricity A
The stress relaxation layer can be made thicker to avoid IR,
Polishing 1' of the convex fitting portion of the ceramic rotating body is completely unnecessary.

Further, since the method of the present invention is not a joining by brazing but a shrink fit by metal filling, no joining is obtained between the second soft metal and the ceramic. As the stress relaxation layer becomes thicker, the shrink fit force decreases, but in order to prevent this, in the method of the present invention, a groove is formed in the convex thorn part of the ceramic rotating body, and a second soft metal is inserted into this groove. 1).

The metal shaft member and the ceramic rotating body are strongly connected to each other.

[Embodiment J] An integrated embodiment of the present invention will be described with reference to the drawings.

Figure 1 is a cutaway side view of the joint where the ceramic rotating body is joined to the metal shaft member, Figure 2 is a sectional view taken along the line 11-■ of the joint in Figure 1, and Figure 3 is the Figure combination z
FIG. 1 is an enlarged side sectional view showing dimensions of 1<.

The rotating shaft 12 of the metal shaft member lO is a structural j! 4 materials for example 5
It is made of C1t40, and a metal ring 14 made of Incoloy 903 is fixed by welding to the tip as a concave fitting part.

The ceramic rotating body +6 is made of silicon nitride, and has an eleventh V-shaped convex fitting portion 18 protruding from the axis of rotation. Two grooves 20 are provided in this convex fitting portion 18 in a direction perpendicular to the axis of the ceramic rotating body 16.

In order to connect the metal shaft member IO and the ceramic rotating body I6, first, Cu is used as the first soft metal on the inner surface of the metal ring 14 before welding to the rotating shaft 12, and the first stress relaxation is achieved by plating. 422 was formed. In order to equalize the plating thickness of this first stress relaxation layer 22, after surface polishing, the convex fitting part 18 of the ceramic rotating body 16 is inserted, and the metal ring 14 is baked at 850°C in a vacuum furnace. Heat to fitting temperature, metal ring +4 and convex fitting part! 8 and the groove 20, an Ag alloy (28, Cu1 (
alA'g) was melt-filled to form the second stress relaxation layer 24, and the shrink fit was completed. The shrink-fitted metal ring 14 was bonded to the rotating shaft 12 by electric r-beam welding.

Next, in order to ensure the effects of the present invention, the thickness of the first stress relaxation layer 22 and the second stress relaxation layer 24, the whiteness of the ceramic groove 20, the metal ring, etc. By changing the length Q, inner diameter D, and outer diameter 1) of 4 under the conditions shown in Table 1, the unbalance of the turbo manufactured by the method of the present invention was measured using a balance tester. Correct Fd to less than 081g-c-,
A high-temperature, high-speed rotation durability test was conducted at an engine exhaust gas temperature of 950° C. to check for damage. The obtained results are also shown in Section 1A.

In Table 1, turbos that were destroyed are shown as x1, and those that were not destroyed are shown as zero.

In addition, sample number 1 on the front of the basket is a comparative example in which the first stress relaxation layer is thin and no second stress relaxation layer is formed, and sample number 2.
Sample No. 3 is a comparative example in which the first stress relaxation layer is thick (-) but the second stress relaxation layer is not formed. This is a comparative example in which a second stress relaxation layer was formed, but grooves were not provided in the ceramic rotating body.

From the results in Table 1, Sample No. 1, which is a comparative example, broke at 180,000 rpm, and Sample No. 2 and 3, which are also comparative examples, broke at 200,000 rpm. On the other hand, in the example of the present invention, sample number I2.14 for which the ・r method was inappropriate for the metal ring
．． Except for No. 15, no damage occurred at 200,000 rpm, confirming the excellent effects of the present invention.

In addition, according to this embodiment, the length Q and inner diameter of the metal ring are determined.

The ratio of is 03≦C/I), and the ratio of inner diameter I) and outer diameter is I), /I), X I O
It has been confirmed that 010-80 and 4' are effective.

1 Effect of the invention 1 The method of joining the ceramic rotating body and metal shaft member of the present invention is as follows:
As described above, by forming the first stress relaxation layer by plating the first soft metal, uneven stress at the joint can be prevented and a uniform joint can be obtained. Also,
During shrink-fitting, by melt-filling the joint and the ceramic with a second soft metal, it is possible to apply a shrink-fitting force of 4-minutes, thereby reducing local eccentric loads. In order to avoid this, it is possible to obtain a joint between the ceramic rotating body and the metal shaft member that does not reduce the shrink fit force even if the stress relaxation layer is thickened. Since alignment accuracy is not required, 1i1F friction of the ceramic rotating body is not required.In addition, since the jM provided on the side of the ceramic rotating body is also filled with the second soft alloy, the stress relaxation layer is Even if it becomes thicker, it acts as a gap and the connection between the ceramic rotating body and the metal shaft seat material is strong.

[Brief explanation of the drawing]

Figure 1 is a cutaway side view of the joint where the ceramic rotating body is joined to the metal shaft seat material, Figure 2 is a cross-sectional view of the joint in Figure 1 taken along the l'l-11 line, and Figure 3 2 is an enlarged side sectional view showing the .r method of the joint shown in FIG. 1; FIG. 10... Metal shaft +9 (material, 12... Rotating shaft, 14...
...metal ring, 16...ceramic rotating body,! 8...
Convex inset portions, 20...11, 22...first stress relief layer, 24...second stress relief layer Fig. 1 Fig. 3 Fig. 2 Fig. 18 Convex intoxication

Claims (1)

[Claims] (1) Plating the inner surface of the concave fitting part of the metal shaft member with a first soft metal to form a first stress relaxation layer, and forming the concave fitting part of the metal shaft member into the groove of the ceramic rotating body. a step of inserting a second soft metal into the formed convex fitting portion, and injecting a second soft metal in a molten state into the gap between the concave fitting portion of the metal shaft member and the convex fitting portion of the ceramic rotating body and solidifying the second soft metal. A method for joining a ceramic rotating body and a metal shaft, comprising the steps of forming a stress relaxation layer and shrink-fitting a convex fitting portion of the ceramic rotating body into a concave fitting portion of the metal shaft member. Method.