JPH1162517A - Sliding component for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce thermal stress generated in a TiC group cermet at joining with a metallic member by containing a proper quantity of Ni in the TiC group cermet. SOLUTION: A rocker arm chip 6 provided with a cermet member 3 made of TiC group cermet containing Ni of 51-40 wt.%, and a rocker arm 4 main body provided with a metallic member 2 are integratedly joined together to form a sliding component 1 for internal combustion engine. Hereby, thermal stress generated at joining together the cermet member 3 and the metallic member 2 is effectively lightened, and in addition to improve the adhesive strength of both members 2, 3, while maintaining abrasive resistance as a sliding component for internal combustion engine, abnormal abrasion of the sliding partner material can be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding part for an internal combustion engine, and more particularly to a sliding part for an internal combustion engine using a TiC-based cermet having a high joining strength with a metal member as a rocker arm and a tappet. It is about.

[0002]

2. Description of the Related Art Heretofore, for materials requiring wear resistance, cemented carbides, ceramics, cermets, and the like having excellent properties such as wear resistance, heat resistance, and corrosion resistance have been frequently used. Is a brittle material, so it is usually rarely used alone, and is applied only to surfaces that require abrasion resistance. Had been used.

On the other hand, there has been a remarkable increase in output and performance of internal combustion engines in recent years, and accordingly, sliding parts for internal combustion engines have been forced to operate under more severe conditions. For this purpose, for example, in sliding parts such as rocker arms, tappets, and valve shims of internal combustion engines, various studies have been made to configure the sliding surface with the wear-resistant member.

[0004] In this connection, when joining a wear-resistant member such as a cemented carbide or ceramics to a metal member, a shrink-fitting method, a brazing method, a diffusion bonding method, or the like is generally adopted. Since it is necessary to heat to a high temperature of 600 ° C. or more in a legal method or the like, a large thermal strain is generated due to a difference in coefficient of thermal expansion between the abrasion-resistant member and the metal member, thereby breaking a joint or causing a joint There were problems such as easy deformation.

[0005] Therefore, in order to reduce the residual stress due to the difference in thermal expansion, the two members are joined via an intermediate layer having a coefficient of thermal expansion intermediate between the wear-resistant member and the metal member, or by elastic deformation or plastic deformation. Various joining methods have been proposed, such as joining the two via a soft material that relieves the stress.

However, under the severe operating conditions required for the recent internal combustion engines as described above, the cemented carbide as a wear-resistant member is insufficient in wear resistance, while having excellent mechanical strength. Also, ceramics such as silicon nitride-based, silicon carbide-based, and alumina-based ceramics are not satisfactory in bonding strength with a metal member, and are liable to peel off between the two members and lack reliability of a bonded portion. there were.

Therefore, the wear resistance is superior to the cemented carbide,
It is considered that the bonding strength with metal members is higher than ceramics. For example, a cermet such as TiC base generally known as a material for cutting tools and an inexpensive iron-based metal member are bonded to form a composite. For example, it is necessary to reduce the formation of a compound layer or the like at the joint interface by reducing thermal strain that impairs joint strength and obtain a joined body of a metal member and a cermet member without deformation or breakage of the joint. Has been proposed (see Japanese Patent No. 2519578).

[0008]

However, the above-mentioned T
When iC-based cermet is applied to the sliding part of sliding parts for internal combustion engines, it is possible to improve seizure resistance and wear resistance by considering the lubrication conditions during operation and the processed surface of the sliding part. Usually, TiC for the cutting tool
When exposed to severe operating conditions such as internal combustion engines, the base cermet is not only easily peeled off due to lack of strength due to thermal stress at the time of joining with metal members, but also causes unilateral damage to the sliding partner material. There is a problem that the sliding partner material is easily worn and damaged in a short time.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a sliding member for an internal combustion engine with a metal member even under severe use conditions required for an internal combustion engine in recent years. Sliding parts for internal combustion engines, which have excellent connection reliability and wear resistance consisting of a joined body of a TiC-based cermet member and a metal member that has a sufficiently high joining strength and does not unilaterally wear the sliding partner. Is to provide.

[0010]

Means for Solving the Problems In view of the above-mentioned problems, the present inventor has made various studies and found that the TiC-based cermet contains Ni.
By containing an appropriate amount, in the direction of reducing the thermal stress generated in the cermet member at the time of joining with the metal member, the coefficient of thermal expansion and Young's modulus can be controlled,
The present inventors have found that sufficient joining reliability with a metal member can be obtained and that damage to a sliding partner material can be reduced, and the present invention has been accomplished.

That is, the sliding part for an internal combustion engine of the present invention has a T content of at least 5 to 40% by weight of nickel (Ni).
It is a sliding component in which a cermet member made of an iC cermet is joined and integrated with an inexpensive metal member having excellent toughness.

Particularly, when the content of nickel (Ni) is 1
More preferably, the content is 5 to 30% by weight. In particular, as a sliding part for an internal combustion engine using a cermet member made of the TiC-based cermet as a sliding part, the TiC-based cermet is used in a sliding part of a rocker arm or a tappet. Is most preferable.

[0013]

The sliding component for an internal combustion engine of the present invention is obtained by joining a cermet member made of a TiC-based cermet containing at least nickel (Ni) in an amount of 5 to 40% by weight to a metal member. System cermet is Ni
As the content increases, the thermal expansion coefficient tends to increase from about 7 to 7.8 × 10 ⁻⁶ / ° C., which is the thermal expansion coefficient of a general TiC-based cermet for cutting tool materials. The difference in thermal expansion from the metal member is reduced, and the TiC
The Young's modulus of the base cermet of about 4.2 to 4.5 × 10 ⁴ kg / mm ² also tends to decrease, and as a result, the thermal stress generated at the time of joining is reduced.

On the other hand, the inclusion of Ni reduces the wear resistance of the cutting tool itself, but when it is used as a sliding part for an internal combustion engine, there is a risk that the sliding partner material will be worn. It is less desirable and more wear-resistant, and has a sufficient wear resistance as a sliding part for an internal combustion engine.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The sliding parts for an internal combustion engine according to the present invention will be described below in detail.

The cermet member of the present invention is made of a TiC-based cermet containing at least nickel (Ni) in an amount of 5 to 40% by weight, and the TiC-based cermet contains WC and Mo ₂ C as other components in an amount of 5 to 5%. It may be contained in the range of 20% by weight, and particularly as an auxiliary for promoting sintering,
From the viewpoint of improving toughness and strength, 1 to 7% by weight of Co is used.
Is desirable.

If the Ni content is less than 5% by weight, the strength decreases due to the coexistence with the contained Co component, resulting in insufficient strength as a sliding part for an internal combustion engine.
If the content exceeds 40% by weight, the wear resistance with the sliding partner material is reduced, and the toughness of the sliding member is reduced.

Accordingly, the content of Ni is specified to be 5 to 40% by weight, but more preferably 15 to 30% by weight from the viewpoint of maintaining the consistency of the coefficient of thermal expansion and the wear resistance.

As a result, the coefficient of thermal expansion is 7.5 × 10 ⁻⁶ / ° C.
Thus, a cermet member made of a TiC-based cermet having a Young's modulus of 4.5 × 10 ⁴ kg / mm ² or less can be obtained.

As the metal member for joining and integrating the cermet member, an inexpensive metal material such as an iron-based or aluminum-based material can be used. From the viewpoint of ensuring the heat resistance, chromium-molybdenum-based carbon steel having a high hardness of 750 or more is desirable. If it is possible to secure the hardness by performing heat treatment on the valve contact surface in the rocker arm manufacturing process. For example, a cold forged product using general carbon steel,
It is also preferable in terms of material cost and mass production cost.

Therefore, the metal member to be joined and integrated with the cermet member constituting the sliding part for an internal combustion engine of the present invention is, specifically, a cold forged product such as SCM415 or a portion of S50C to S55C in consideration of a partial heat treatment. The most suitable is carbon steel.

In addition to the above rocker arms and tappets, piston heads, piston rings, cylinders, various valves, shims, and the like can be used as sliding parts for an internal combustion engine. From the mass productivity and cost reduction of forming a sliding part by joining a cermet to the minimum necessary sliding part, the sliding part of the rocker arm, tappet, shim, etc. is made a cermet member, and a metal member and It is most effective to apply them by joining them together.

Next, an embodiment of the method for manufacturing a sliding part for an internal combustion engine according to the present invention will be specifically described.

First, at least nickel (Ni) is added
The bonding surface of the cermet member and the metal member made of the TiC-based cermet containing 40% by weight is cleaned with a cleaning agent such as an organic solvent to remove components that inhibit bonding such as oils and fats, and dried.

Then, after a brazing material made of an Ag-Cu wire is washed on the joining surface in the same manner as the joining surface of the cermet member and the metal member, the brazing material is sandwiched between the cermet member and the metal member.

Then, the joint between the two members sandwiching the brazing material is locally heated so that the brazing material is melted and brazed.

At the time of the heating, the cermet member and the metal member are heated by a general brazing connection so as to heat the entire sliding component composed of the two members. In addition to the problem of reduced hardness,
There is a drawback that large-scale facilities and equipment such as a reduction furnace and a high-frequency induction heating device are required, and the production cost increases.
In addition, when the whole is heated and joined, in order to secure the wear resistance of the sliding component body after the joining, heat treatment such as high frequency heating is performed on a necessary portion to secure a predetermined hardness. Because it must be done, it is most convenient to heat locally.

The method of locally heating is not particularly limited, and a well-known torch heating method, a high-frequency induction heating method, a laser irradiation method, or the like can be employed. The laser irradiation method is superior in that the influence of the laser beam is stopped at the joint as much as possible.

Thus, a sliding part for an internal combustion engine in which the cermet member and the metal member of the present invention are joined and integrated is obtained.

[0030]

Next, the sliding parts for an internal combustion engine of the present invention were evaluated as follows.

Embodiment 1 First, a sliding part for an internal combustion engine according to the present invention will be described in detail based on an embodiment applied to a rocker arm. FIG. 1 is a side view showing an example in which the sliding component for an internal combustion engine of the present invention is applied to a rocker arm. In the drawing, 1 is a rocker arm 4 made of a metal member 2 and a rocker arm chip 6 made of a cermet member 3.
And a sliding part for an internal combustion engine in which the above components are joined and integrated.

In evaluating the rocker arm as a sliding part for an internal combustion engine according to the present invention, a rocker arm body made of S50C structural carbon steel having a shape as shown in the figure and a sliding part of the rocker arm are joined. A rocker arm tip comprising the following cermet member was prepared.

The rocker arm tip is a cermet member having TiC as a main component, having the composition shown in Table 1, and sintering with various amounts of Ni. The amount ratio in the table is the component ratio of the sintered body. Is shown.

Incidentally, the surface of the rocker arm tip was polished to reduce abrasion to a sliding partner material, and the surface roughness was set to Ra 0.3 or less.

[0035]

[Table 1]

Using the rocker arm tip, which is a TiC-based cermet member for evaluation, obtained as described above, the coefficient of thermal expansion was determined by the push-bar differential method using quartz glass as a standard sample, and the diameter of the rocker arm tip processed was 4 mm. ,
The Young's modulus was measured by an ultrasonic pulse method using a sample having a length of 10 mm.

The above results are shown in FIG. 2 with the Ni content on the horizontal axis and the coefficient of thermal expansion and Young's modulus on the vertical axis.

Next, C1 chamfering was performed on each joint surface between the rocker arm tip and the rocker arm main body, a 1.2 mm diameter Ag-Cu-based linear brazing material was sandwiched, and the device was mounted on a high-frequency induction heating device. And apply a load of 10 kgf,
Heat bonding was performed.

Note that a chip made of a silicon nitride sintered body is
A comparative example was prepared by coating a metallized layer of -Ag-Cu system and then bonding the same brazing material to a rocker arm body made of the same metal member in a vacuum furnace using the same brazing material.

With respect to the thus obtained rocker arm, which is a sliding part for an internal combustion engine, for evaluation, the load when the metal member constituting the body is gripped and the joined rocker arm tip is peeled off by pressing from the side. Was evaluated as the bonding strength.

Further, each rocker arm for evaluation prepared under the same conditions as described above was incorporated into the head of a diesel engine, and the engine oil was mixed with soot assuming EGR.
Using a SAE30 oil heated to 0 ° C. and a cycle mode in which the driving speed is 1000 to 3000 rpm,
A motoring test for 00 hours was conducted, and the state of the joint after the test was inspected for abnormalities, and the abrasion state of the sliding surface of the sliding partner material was visually inspected to determine the wear marks and the rocker arm tip material. The presence or absence of adhesion was investigated.

The height of the cam nose as the sliding partner was measured by a dial gauge before and after the motoring test, and the difference in the height was evaluated as the wear amount of the sliding partner.

The state of the sliding surface of the rocker arm tip material when the rocker arm of Sample No. 5 which is a typical example of the sliding part for an internal combustion engine for evaluation according to the present invention was used was evaluated by the motoring test. The surface profile of the main part of the sliding surface before and after was measured by a surface roughness meter, and the results are shown in FIG.

[0044]

[Table 2]

As is clear from the table, in the sample No. 10 of the comparative example in which the chip made of the silicon nitride sintered body was joined, a part was peeled off at the joined portion by the motoring test, and the invention claimed In sample No. 1 outside the range, a large wear mark was observed on the sliding surface of the sliding partner material along with peeling from the joint by the motoring test, and the amount of wear was extremely large at 110 μm. Although no exfoliation of the portion occurs, adhesion is recognized on the sliding surface of the sliding partner material.

On the other hand, in the present invention, no abnormality was observed in the joints, and no wear marks or adhesion were observed on the sliding surface of the sliding partner.

Embodiment 2 An embodiment applied to a tappet as a sliding part for an internal combustion engine according to the present invention will be described. FIG. 4 is a sectional view showing an example in which the sliding component for an internal combustion engine of the present invention is applied to a tappet. In the figure, reference numeral 1 denotes a sliding part for an internal combustion engine in which a main body of a tappet 5 made of a metal member 2 and a cermet member 3 forming a tappet chip are joined and integrated.

In evaluating a tappet as a sliding part for an internal combustion engine of the present invention, an S50 having a shape as shown in FIG.
Tappet body made of carbon steel for structural use of C, and TiC to be joined to the sliding portion of the tappet as a main component, Ni being 15% by weight, WC being 10% by weight, Mo ₂ C being 10% by weight and Co being 10% by weight.
A tappet chip having a composition containing 2% by weight was prepared.

Then, after each of the joining surfaces of the tappet body and the tappet tip was chamfered with C1, the diameter was 1.2 m.
An Ag-Cu brazing wire having a length of m was sandwiched and heated and joined by a laser irradiation method using N ₂ gas.

A comparative example was obtained by joining a tappet chip made of a silicon nitride sintered body to a tappet body made of the same metal member as in Example 1.

The load obtained when the metal member portion of the tappet body, which is the sliding part for an internal combustion engine for evaluation thus obtained, was gripped and the tappet tip was peeled off by pressing it from the side was obtained. In contrast to 150 MPa, in the present invention, a high bonding strength of 280 MPa was obtained.

Further, the tappet for evaluation produced under the same conditions as described above was incorporated into a body of a diesel engine, and a continuous durability test was conducted at a driving speed of 1200 rpm for 300 hours using SAE30 oil mixed with soot.

As a result, in the comparative example after the continuous durability test, the tappet chip was peeled due to insufficient bonding strength, whereas in the present invention, no abnormality was recognized in the bonding portion. The amount of wear of the chill cast iron cam material as the mating material was 10 μm or less, no abnormal wear was observed, and it was confirmed that damage to the sliding mating material was extremely low.

The sliding part for an internal combustion engine according to the present invention is not limited to the above-mentioned embodiment, but can be applied to any sliding part for an internal combustion engine as long as it is in accordance with the gist of the present invention. Needless to say, there is.

[0055]

The sliding part for an internal combustion engine according to the present invention has a TiC content of at least 5 to 40% by weight of nickel (Ni).
Since the cermet member composed of the system cermet is joined and integrated with the metal member, the thermal stress generated at the time of joining the cermet member and the metal member is effectively reduced, and the adhesive strength between the two members is improved, and the internal combustion engine is improved. It is possible to suppress abnormal wear of the sliding partner material while maintaining the wear resistance as a sliding part for use in internal combustion engines, and to provide a long-life sliding part for internal combustion engines as a sliding member with high joining reliability. Obtainable.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment in which a sliding part for an internal combustion engine of the present invention is applied to a rocker arm in which a rocker arm tip is a cermet member and a main body is integrally joined as a metal member made of structural carbon steel. is there.

FIG. 2 is a diagram showing the thermal expansion coefficient and the Young's modulus of a cermet member in which the sliding component for an internal combustion engine of the present invention is applied to a rocker arm, in relation to the Ni content.

FIG. 3 is a diagram showing a surface profile of a main part of a sliding surface of a rocker arm chip before and after a motoring test in a case where a sliding component for an internal combustion engine of the present invention is applied to a rocker arm.

FIG. 4 is a cross-sectional view showing an embodiment in which a sliding part for an internal combustion engine of the present invention is applied to a tappet in which a tappet tip is a cermet member and a main body is integrally joined as a metal member made of structural carbon steel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sliding part for internal combustion engines 2 Metal member 3 Cermet member 4 Rocker arm 5 Tappet

Claims (3)

[Claims] 1. A sliding part in which a cermet member and a metal member are joined and integrated, wherein said cermet member is made of a TiC-based cermet containing at least 5 to 40% by weight of nickel (Ni). Sliding parts for engines. 2. The sliding part for an internal combustion engine according to claim 1, wherein said cermet member is made of a TiC-based cermet containing at least 15 to 30% by weight of nickel (Ni). 3. The sliding part for an internal combustion engine according to claim 1, wherein the sliding part is one of a rocker arm and a tappet.