JPH06174052A - Slide surface constituting body - Google Patents

Abstract

PURPOSE:To enhance seizure resistance by letting both a high bearing pressure zone and a low bearing pressure zone existing in a slide surface faced to a mating member be composed of the aggregate of pyramid shaped metallic crystals and/or truncated pyramid shaped metallic crystals, and thereby setting the average grain size of each metallic crystal in the high bearing pressure zone to be larger than that of each metallic crystal in the lower bearing pressure zone. CONSTITUTION:A cam shaft 1 for an internal combustion engine includes a base member 2 made of cast iron, and a layer slide surface constituting body 8 having a slide surface 7 faced to a rocker arm slipper 6 acting as a mating member, is formed while being processed by plating in the slide surface of the cam 3 of the base member 2, that is, a nose section 4, and the outer circumferential surface of a base circular section 5. And there exist both a high bearing pressure zone A at the nose section 4 side and a low bearing pressure zone B at the base circular section 5 side in the slide surface 7 of the slide surface constituting body 8. In this case, let both the zones A and B be composed of the aggregate of metallic crystals including at least either one of a plurality of pyramid shaped metallic crystals and a plurality of trucated pyramid shaped metallic crystals (pyramid shaped metallic crystals 9 and 10 are shown in the figure). In addition, the average grain size of each metallic crystal 9 in the high bearing pressure zone is set to be larger than that of each metallic crystal 10 in the low bearing pressure zone.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding surface structure having a sliding surface with a mating member, and the sliding surface has a high surface pressure region and a low surface pressure region.

[0002]

2. Description of the Related Art Conventionally, as a sliding surface structure of this type, for example, in a cast iron camshaft for an internal combustion engine, a nitride layer is provided on the outer peripheral surface of the cam for the purpose of improving seizure resistance. .

[0003]

However, under the present circumstances where the internal combustion engine tends to have high speed and high output, the conventional sliding surface structure does not have sufficient oil retaining property, that is, oil retaining property. Further, since the initial conformability is poor, there is a problem that seizure resistance is poor particularly in the nose portion which is a high surface pressure region.

In view of the above, the present invention specifies the crystal structures in the high surface pressure region and the low surface pressure region, respectively, so as to provide both these regions with sufficient oil retaining property and good initial conformability, thereby making it possible to prevent the burning resistance. It is an object of the present invention to provide the above-mentioned sliding surface structure capable of improving the adherence.

[0005]

According to the present invention, there is provided a sliding surface structure having a sliding surface with a mating member, wherein the sliding surface has a high surface pressure region and a low surface pressure region. The surface pressure area and the low surface pressure area are constituted by an aggregate of at least one metal crystal of a pyramidal metal crystal and a truncated pyramidal metal crystal, and the average particle diameter of the metal crystal in the high surface pressure area is the low surface area. It is characterized in that it is set to be larger than the average grain size of the metal crystals in the pressure region.

[0006]

Since the high surface pressure region is composed of an aggregate of relatively large pyramidal metal crystals and the like, the high surface pressure region has a relatively large capacity due to the valley between the two adjacent crystals. An oil sump is formed. At the beginning of sliding, the initial conformability becomes good due to preferential wear of the tip side of the pyramidal metal crystal or the like.

[0007] The oil retaining property of the aggregate of pyramidal metal crystals or the like depends on the depth of the valley, and if the valley is too deep, a lubricating oil flow occurs in the valley and the oil retaining property deteriorates. On the other hand, if the depth of the trough is shallow, it goes without saying that the capacity of the oil sump is small, and therefore it is not possible to retain sufficient lubricating oil to cope with sliding under high surface pressure.

In the high surface pressure region, after the initial wear, the depth of the valley portion becomes an appropriate depth so as to prevent the flow of the lubricating oil, so that sufficient oil retaining property is ensured, whereby high surface pressure is obtained. Area wear is greatly reduced. As a result, the oil retaining property in the high surface pressure region is maintained so as to cope with the sliding under the high surface pressure.

On the other hand, since the low surface pressure region is composed of an aggregate of relatively small pyramidal metal crystals and the like, the capacity of the oil sump is smaller than that in the high surface pressure region. At the beginning of sliding, the initial conformability becomes good due to preferential wear of the tip side of the pyramidal metal crystal or the like. In this case, since the surface pressure is relatively low, the amount of wear is relatively small, and therefore sufficient oil retention is ensured even after the initial wear, so that the wear in the low surface pressure region is significantly suppressed. As a result, the oil retaining property in the low surface pressure region is maintained so as to cope with sliding under the low surface pressure.

In this way, the seizure resistance of the sliding surface structure can be improved.

If the high surface pressure region is composed of an aggregate of relatively small pyramidal metal crystals, which is similar to the low surface pressure region, at the stage of initial wear, the surface pressure of the crystal is high due to the high surface pressure. The amount of wear increases, and as a result, the troughs become shallower and the capacity of the oil sump becomes extremely small. Therefore, it is not possible to secure the oil retaining property that can cope with sliding under high surface pressure.

On the other hand, when the low surface pressure region is formed of an aggregate of relatively large pyramidal metal crystals or the like similar to the high surface pressure region, the amount of wear of the crystal is small due to the low surface pressure. As a result, the depth of the valley portion is too deep, so that the flow of lubricating oil occurs and the oil retaining property is significantly reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a camshaft 1 for an internal combustion engine has a cast iron base material 2, and a cam 3 of the base material 2, and thus a nose portion 4 and a base circular portion 5 on the outer peripheral surface thereof, is a rocker arm which is a counterpart member. A layered sliding surface structure 8 having a sliding surface 7 with the slippers 6 is formed by plating. The sliding surface 7 of the sliding surface structure 8 has a high surface pressure area A on the nose portion 4 side and a low surface pressure area B on the base circular portion 5 side. The high surface pressure region A and the low surface pressure region B are, as shown in FIGS. 2 and 3, at least one of a pyramidal metal crystal and a truncated pyramidal metal crystal, in the illustrated example, a set of pyramidal metal crystals 9 and 10. Composed of the body. The average grain size of the metal crystals 9 in the high surface pressure region A is set to be larger than the average grain size of the metal crystals 10 in the low surface pressure region B.

As described above, when the high surface pressure area A is composed of an aggregate of relatively large pyramidal metal crystals 9, the high surface pressure area A is compared by the valley portion 11 between the adjacent crystals 9. A large oil reservoir is formed. At the initial stage of sliding, the initial conformability becomes good due to preferential wear of the tip side of the pyramidal metal crystal 9. After the initial wear, the depth of the valley portion 11 becomes an appropriate depth capable of preventing the flow of the lubricating oil, so that sufficient oil retaining property is secured, and thus the wear of the high surface pressure area A is significantly suppressed. It As a result, the oil retaining property of the high surface pressure region A is maintained so as to be able to cope with sliding under high surface pressure.

On the other hand, since the low surface pressure region B is composed of an aggregate of relatively small pyramidal metal crystals 10, the capacity of the oil sump by the valley 12 is smaller than that in the high surface pressure region A. At the initial stage of the sliding start, preferential wear on the tip side of the pyramidal metal crystal 10 improves the initial conformability. In this case, since the surface pressure is relatively low, the amount of wear is relatively small, and therefore sufficient oil retaining property is secured after the initial wear, so that the wear in the low surface pressure region B is significantly suppressed. As a result, the oil retaining property of the low surface pressure region B is maintained so as to cope with sliding under the low surface pressure.

In this way, the seizure resistance of the sliding surface structure 8 can be improved.

The pyramidal metal crystals 9 and 10 form the tips of the columnar crystals, and the inclination of the pyramidal metal crystals 9 and 10 affects the oil retaining property of the sliding surface structure 8. Therefore, as shown in FIG. 4, a virtual surface 13 along the sliding surface 7 is defined on the bottom surface side of the pyramidal metal crystals 9 and 10, and the apex a of the pyramidal metal crystals 9 and 10 and the central portion b of the bottom surface. When the inclination angle of the straight line c passing through is defined as θ with respect to the reference line d passing through the bottom surface central portion b and perpendicular to the virtual surface 13, the inclination angle θ is set to 0 ° ≦ θ ≦ 30 °. Tilt angle θ
Is θ> 30 °, the oil retaining property of the sliding surface structure 8 deteriorates.

As shown in FIG. 5, when the pyramidal, for example, triangular pyramidal metal crystals 9 and 10 have a body-centered cubic structure (bcc structure), the metal crystals 9 and 10 have Miller indices (hhh). (Hhh), (2hhh) oriented metal crystal with the surface or (2hhh) surface facing the sliding surface 7 side.

Further, as shown in FIG. 6, the pyramidal, for example, quadrangular pyramidal metal crystals 9 and 10 have a face-centered cubic structure (fcc structure).
In the case of having, the metal crystals 9 and 10 are (h00) and (3hhh) oriented metal crystals with the (h00) plane or the (3hhh) plane facing the sliding surface 7 side by the Miller index.

As a metal crystal having a bcc structure, F is
Examples thereof include crystals of e, Cr, Mo, W, Ta, Zr, Nb, V, etc., or alloys thereof. The metal crystals having the fcc structure include Pb, Ni, Cu, Pt, and A.
Crystals of a simple substance such as l, Ag and Au or an alloy thereof can be given.

Table 1 and Table 2 show the basic conditions for performing the electric Fe plating process in the plating process for forming the sliding surface structure 8 according to the present invention.

[0022]

[Table 1] As the organic additive, urea, saccharin or the like is used.

[0023]

[Table 2] Tables 3 and 4 show the case of electric Ni plating treatment.

[0024]

[Table 3]

[0025]

[Table 4] In the electric Fe and Ni plating treatments performed under the above-mentioned conditions, (hhh), (2hhh), (h00), depending on the cathode current density, the plating bath pH, the blending amount of the organic additive, etc.
(3hhh) Crystallization of oriented metal crystals, their abundance, average particle size, etc. are controlled.

As the plating treatment, in addition to electroplating treatment, vacuum plating treatment such as vapor phase plating method, PVD method,
The CVD method, the sputtering method, the ion plating and the like can be mentioned. Conditions for performing W and Mo plating by the sputtering method are, for example, Ar pressure 0.8 Pa, Ar acceleration power DC 1 kW, and base material temperature 100 ° C. The conditions for performing Pt and Al plating by the sputtering method are, for example, Ar pressure 0.8 Pa, Ar acceleration power DC 500 W, and base material temperature 100 ° C. Conditions for performing W plating by the CVD method are, for example, raw material WF ₆ ,
Gas flow rate 10 cc / min, chamber pressure 100P
a, Base material temperature is 500 ° C. In addition, by the CVD method
The conditions for performing the plating include, for example, the raw material Al (C
H ₃ ) ₃ , gas flow rate 2 cc / min, chamber pressure
It is 100 Pa and the base material temperature is 500 ° C.

A specific example will be described below.

Nose portion 4 and base circular portion 5 of cam 3 having a chill layer of cast iron base material 2 made of JIS FC25.
By applying an electric Fe plating treatment to the outer peripheral surface,
Forming a sliding surface structure 8 including a sliding surface 7 composed of an aggregate of crystals and having a high surface pressure area A on the nose portion 4 side and a low surface pressure area B on the base circular portion 5 side. Thus, a plurality of camshafts 1 for internal combustion engines were manufactured.

Tables 5 to 8 show examples 1 to 12 of the sliding surface structure 8.
The electric Fe plating processing conditions in FIG.

[0030]

[Table 5]

[0031]

[Table 6]

[0032]

[Table 7]

[0033]

[Table 8] Tables 9 and 10 show the crystal morphology of the sliding surface 4a in Examples 1 to 12, the grain size of Fe crystals, the abundance S of each oriented Fe crystal, and the hardness, respectively.

[0034]

[Table 9]

[0035]

[Table 10] The existence ratio S is obtained by the following method based on the X-ray diffraction diagrams of Examples 1 to 12 (the X-ray irradiation direction is the direction perpendicular to the sliding surface 7). Explaining Example 2 as an example, FIGS. 7 and 8 are X-ray diffraction diagrams of the high and low surface pressure regions A and B in Example 2, and the abundance S of each oriented Fe crystal is calculated from the following equation. Was given. Note that, for example, the {110} oriented Fe crystal means an oriented Fe crystal with the {110} plane facing the sliding surface 4a. {110} oriented Fe crystal: S ₁₁₀ = {(I ₁₁₀ / IA
₁₁₀ ) / T} × 100, {200} oriented Fe crystal: S ₂₀₀ = {(I ₂₀₀ / IA
₂₀₀ ) / T} × 100, {211} oriented Fe crystal: S ₂₁₁ = {(I ₂₁₁ / IA)
₂₁₁ ) / T} × 100, {310} oriented Fe crystal: S ₃₁₀ = {(I ₃₁₀ / IA
₃₁₀ ) / T} × 100, {222} oriented Fe crystal: S ₂₂₂ = {(I ₂₂₂ / IA)
₂₂₂ ) / T} × 100 where I ₁₁₀ , I ₂₀₀ , I ₂₁₁ , I ₃₁₀ , and I ₂₂₂ are the measured values (cps) of the X-ray reflection intensity of each crystal plane, and IA ₁₁₀ , IA ₂₀₀ , and IA. ₂₁₁ , IA ₃₁₀ , and IA ₂₂₂ are the X-ray reflection intensity ratios of each crystal plane in the ASTM card,
IA ₁₁₀ = 100, IA ₂₀₀ = 20, IA ₂₁₁ = 30,
IA ₃₁₀ = 12 and IA ₂₂₂ = 6. Furthermore, T is T
= (I ₁₁₀ / IA ₁₁₀ ) + (I ₂₀₀ / IA ₂₀₀ ) + (I
₂₁₁ / IA ₂₁₁ ) + (I ₃₁₀ / IA ₃₁₀ ) + (I ₂₂₂ /
IA ₂₂₂ ).

9 and 10 are photomicrographs (5000 times) showing the crystal structures of the high and low surface pressure regions A and B of Example 2. In the high surface pressure region A shown in FIG. 9, many triangular pyramid-shaped (hhh) oriented Fe crystals are observed. This (hhh) oriented Fe crystal is a {222} oriented Fe crystal, and the average grain size of the {222} oriented Fe crystal is
As shown in Table 9, it is about 4 μm. In the low surface pressure region B shown in FIG. 10, a large number of small pyramid-shaped (2hhh) oriented Fe crystals are observed. This small pyramid (2hhh)
The oriented Fe crystal is a {211} oriented Fe crystal,
The average particle size is about 1 μm as shown in Table 9.
Next, the camshafts of Examples 1 to 12 were incorporated into an engine and a seizure test was conducted to find {222} oriented Fe crystals in the high surface pressure region A and {211} oriented Fe crystals in the low surface pressure region B. When the relationship between the average particle size and the surface pressure at which seizure occurs was determined, the results shown in FIG. 11 were obtained. The test conditions are as follows. Camshaft speed 2000 rpm, oil supply 10 ml / min, oil temperature 100 ° C, rocker arm slipper material Fe-based sintered material. In the figure, points (1) to (12) correspond to Examples 1 to 12, respectively. The lines x _{1 to} x ₃ are
This is a case where the crystal structures in the low surface pressure region B are different from each other. Line y shows the case where the outer peripheral surface of the cam 3 is subjected to nitriding treatment, and therefore the nose portion 4 and the base circular portion 5 are not subjected to electric Fe plating treatment.

From FIG. 11, as in Examples 1 and 2, the average grain size of {222} oriented Fe crystals in the high surface pressure region A on the nose portion 4 side was increased, and the low surface on the base circular portion 5 side was increased. Pressure area B
It can be seen that the seizure-occurring surface pressure is improved by setting the average grain size of the {211} -oriented Fe crystals in 3) to be small.

FIG. 12 shows X in another example of the low surface pressure region B.
FIG. 13 is a line diffraction diagram, and FIG. 13 is a photomicrograph (5000 times) showing its crystal structure. In the low surface pressure region B shown in FIG. 13, many small pyramid-shaped (hhh) orientations F
An e crystal is observed, and this (hhh) oriented Fe crystal is a {222} oriented Fe crystal. {222} orientation F
The abundance S of the e crystals is S = 45.9%, and the average particle size is about 1 μm. The combination of the low surface pressure region B having the {222} oriented Fe crystals and the high surface pressure region A having the {222} oriented Fe crystals in Examples 1 and 2 also results in the same camshaft as above. The seizure resistance can be improved.

Tables 11 and 12 show the conditions for electroplating Fe in the low surface pressure region B shown in FIG.

[0040]

[Table 11]

[0041]

[Table 12] As shown in FIG. 14, the metal crystals 9 and 10 may have a truncated pyramid shape, and the inclination angle θ in this case passes through a straight line g passing through the upper bottom central portion e and the lower bottom central portion f and a lower bottom central portion f. It is defined as an angle formed by a reference line d perpendicular to the virtual surface 13. The range of the inclination angle θ is 0 ° ≦ θ ≦ 30 ° as described above. Further, the sliding surface structure 8 may be composed of an aggregate of pyramidal and truncated pyramidal metal crystals.

The average grain size D ₁ of the metal crystals 9 in the high surface pressure region A is 4 μm ≦ D ₁ ≦ 10 μm, and the metal in the low surface pressure region B is different depending on the surface pressure acting on the sliding surface structure 8. The average particle size D ₂ of the crystal 10 is 0.5 μm ≦ D ₂ ≦
3 μm is suitable. For example, the surface pressure P _{1 in} the high surface pressure area A is P ₁ ≧ 100 MPa, and the surface pressure P ₂ in the low surface pressure area B is P ₂
When <100 MPa, the abundance S of the metal crystals 9 having an average particle diameter D ₁ of D ₁ = 4 μm is S ≧ 40%, and the abundance S of the metal crystals 10 having an average particle diameter D ₂ of D ₂ <4 μm S Is S ≧
When it is 40%, sufficient oil retention can be secured and seizure resistance can be improved.

The present invention is not limited to camshafts, but also piston pins, gears, crankshafts, differential pinion shafts, connecting rods, pistons (skirts, lands, ring grooves), rocker arms, valve lifters, bearing metals, bearing inner cases, bearings. Also applicable to outer cases, metal belts, pulleys, etc.

[0044]

According to the present invention, when the sliding surface has a high surface pressure area and a low surface pressure area, the seizure resistance is excellent by specifying the crystal structure of these areas as described above. It is possible to provide a sliding surface structure.

[Brief description of drawings]

FIG. 1 is a sectional view of a camshaft.

FIG. 2 is an enlarged view of a portion indicated by an arrow 2 in FIG.

FIG. 3 is an enlarged view of a portion indicated by an arrow 3 in FIG.

FIG. 4 is an explanatory diagram showing a tilt of a pyramidal metal crystal.

FIG. 5: Body-centered cubic structure and its (hhh) plane, (2h
It is a perspective view which shows the hh) surface.

FIG. 6 is a face-centered cubic structure and its (h00) plane, (3h
It is explanatory drawing which shows the hh) surface.

FIG. 7 is an X-ray diffraction diagram of a high surface pressure region.

FIG. 8 is an X-ray diffraction diagram in an example of a low surface pressure region.

FIG. 9 is a micrograph showing a crystal structure in a high surface pressure region.

FIG. 10 is a micrograph showing a crystal structure in an example of a low surface pressure region.

FIG. 11 is a graph showing the results of a burn-in test.

FIG. 12 is an X-ray diffraction diagram in another example of the low surface pressure region.

FIG. 13 is a micrograph showing a crystal structure in another example of the low surface pressure region.

FIG. 14 is an explanatory diagram showing a tilt of a truncated pyramidal metal crystal.

[Explanation of symbols]

 6 Rocker Arm Slipper (Mating member) 8 Sliding surface structure 8a Sliding surface 9,10 Metal crystal A High surface pressure area B Low surface pressure area

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[Procedure amendment]

[Submission date] April 6, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title of invention Sliding surface structure

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding surface structure having a sliding surface with a mating member, and the sliding surface has a high surface pressure region and a low surface pressure region.

[0002]

2. Description of the Related Art Conventionally, as a sliding surface structure of this type, for example, in a cast iron camshaft for an internal combustion engine, a nitride layer is provided on the outer peripheral surface of the cam for the purpose of improving seizure resistance. .

[0003]

However, under the present circumstances where the internal combustion engine tends to have high speed and high output, the conventional sliding surface structure does not have sufficient oil retaining property, that is, oil retaining property. In addition, since the initial conformability also bad, especially, Roh
There is a problem of poor Oite seizure resistance to high surface pressure area of over's side.

In view of the above, the present invention specifies the crystal structures in the high surface pressure region and the low surface pressure region, respectively, so as to provide both these regions with sufficient oil retaining property and good initial conformability, thereby making it possible to prevent the burning resistance. It is an object of the present invention to provide the above-mentioned sliding surface structure capable of improving the adherence.

[0005]

According to the present invention, there is provided a sliding surface structure having a sliding surface with a mating member, wherein the sliding surface has a high surface pressure region and a low surface pressure region. surface pressure region and Teimen pressure region a number of pyramid-shaped metal crystals and metal crystal aggregate having at least one of a number of truncated pyramid-shaped metal crystals
Formed by, Oyo the pyramid in the high surface pressure region
And the average particle size of the truncated pyramidal metal crystal in the low surface pressure region .
It is set to be larger than the average grain size of the pyramidal and truncated pyramidal metal crystals.

[0006]

Since the high surface pressure region is formed by, for example , a metal crystal aggregate having a large number of relatively large pyramidal metal crystals, the high surface pressure region is formed between the adjacent pyramidal metal crystals. large oil reservoir of relatively capacity by valleys to exist. In the sliding start early, initial conformability is improved by preferential wearing of pyramid-shaped metal crystals in the tip side.

The oil retaining property of the metal crystal aggregate depends on the depth of the valley, and if the valley is too deep, a lubricating oil flow occurs in the valley and the oil retaining property deteriorates. On the other hand, if the depth of the trough is shallow, it goes without saying that the capacity of the oil sump is small, and therefore it is not possible to retain sufficient lubricating oil to cope with sliding under high surface pressure.

In the high surface pressure region, after the initial wear, the depth of the valley portion becomes an appropriate depth so as to prevent the flow of the lubricating oil, so that sufficient oil retaining property is ensured, whereby high surface pressure is obtained. Area wear is greatly reduced. As a result, the oil retaining property in the high surface pressure region is maintained so as to cope with the sliding under the high surface pressure.

On the other hand, the low surface pressure region is formed by, for example , a metal crystal aggregate having a large number of relatively small pyramidal metal crystals.
Because it is formed, the capacity of the oil reservoir in comparison with the high surface pressure area is small. In the sliding start early, initial conformability is improved by preferential wearing of the preceding <br/> end side of the pyramid-shaped metal crystals. In this case, since the surface pressure is relatively low, the amount of wear is relatively small, and therefore sufficient oil retention is ensured even after the initial wear, so that the wear in the low surface pressure region is significantly suppressed. As a result, the oil retaining property in the low surface pressure region is maintained so as to cope with sliding under the low surface pressure.

In this way, the seizure resistance of the sliding surface structure can be improved.

The high surface pressure region is formed into a metal crystal aggregate having a large number of relatively small pyramidal metal crystals as in the low surface pressure region.
If it is formed, the amount of wear of the crystals increases due to the high surface pressure at the stage of initial wear, and as a result, the valley becomes shallower and the oil reservoir capacity becomes extremely small. It is not possible to secure sufficient oil retention to cope with sliding in the.

[0012] On the other hand, a low surface pressure region, as well as high surface pressure area
Collection of metal crystals with a large number of relatively large pyramidal metal crystals
When formed by coalescence, the amount of wear of the crystals is small due to the low surface pressure, and as a result, the flow of lubricating oil occurs because the depth of the valley is too deep, and the oil retention is significantly reduced. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a camshaft 1 for an internal combustion engine has a cast iron base material 2, and a cam 3 of the base material 2, and thus a nose portion 4 and a base circular portion 5 on the outer peripheral surface thereof, is a rocker arm which is a counterpart member. A layered sliding surface structure 8 having a sliding surface 7 with the slippers 6 is formed by plating. The sliding surface 7 of the sliding surface structure 8 has a high surface pressure area A on the nose portion 4 side and a low surface pressure area B on the base circular portion 5 side. Its high surface pressure area A and Teimen pressure region B is 2, as shown in FIG. 3, multi
At least one of a number of pyramidal metal crystals and a large number of truncated pyramidal metal crystals, in the illustrated example, a large number of pyramidal metal crystals 9, 1.
It is formed by a metal crystal aggregate having 0. The average particle size of the pyramidal metal crystal 9 in the high surface pressure region A is set to be larger than the average particle size of the pyramidal metal crystal 10 in the low surface pressure region B.

As described above, the high surface pressure area A is formed by a metal crystal aggregate having a large number of relatively large pyramidal metal crystals 9.
Once formed , in the high surface pressure area A, adjacent pyramidal gold
Large oil reservoir of relatively capacity by the valleys 11 between the group crystal 9 is exist. At the beginning of sliding, pyramidal metal crystals 9
The initial conformability is improved by the preferential wear of the tip end side of the. After the initial wear, the depth of the valley portion 11 becomes an appropriate depth capable of preventing the flow of the lubricating oil, so that sufficient oil retaining property is secured, and thus the wear of the high surface pressure area A is significantly suppressed. It As a result, the oil retaining property of the high surface pressure region A is maintained so as to be able to cope with sliding under high surface pressure.

On the other hand, the low surface pressure region B is formed by a metal crystal aggregate having a large number of relatively small pyramidal metal crystals 10.
Because it is formed, compared to the high surface pressure area A, the capacity of the oil reservoir by the valleys 12 is small. At the beginning of sliding,
The preferential wear on the tip side of the pyramidal metal crystal 10 improves the initial conformability. In this case, since the surface pressure is relatively low, the amount of wear is relatively small, and therefore sufficient oil retaining property is secured after the initial wear, so that the wear in the low surface pressure region B is significantly suppressed. As a result, the oil retaining property of the low surface pressure region B is maintained so as to cope with sliding under the low surface pressure.

In this way, the seizure resistance of the sliding surface structure 8 can be improved.

The pyramidal metal crystals 9 and 10 form the tips of the columnar crystals, and the inclination of the pyramidal metal crystals 9 and 10 affects the oil retaining property of the sliding surface structure 8. Therefore, as shown in FIG. 4, a virtual surface 13 along the sliding surface 7 is defined on the bottom surface side of the pyramidal metal crystals 9 and 10, and the apex a of the pyramidal metal crystals 9 and 10 and the central portion b of the bottom surface. When the inclination angle of the straight line c passing through is defined as θ with respect to the reference line d passing through the bottom surface central portion b and perpendicular to the virtual surface 13, the inclination angle θ is set to 0 ° ≦ θ ≦ 30 °. Tilt angle θ
Is θ> 30 °, the oil retaining property of the sliding surface structure 8 deteriorates.

As shown in FIG. 5, when the pyramidal, for example, triangular pyramidal metal crystals 9 and 10 have a body-centered cubic structure (bcc structure), the metal crystals 9 and 10 have Miller indices (hhh). (Hhh) oriented metal crystal or (2hhh) oriented metal crystal with the surface or the (2hhh) surface facing the sliding surface 7 side.

Further, as shown in FIG. 6, the pyramidal, for example, quadrangular pyramidal metal crystals 9 and 10 have a face-centered cubic structure (fcc structure).
In the case of having, the metal crystals 9 and 10 are (h00) oriented metal crystal or (3hhh) oriented metal crystal in which the (h00) plane or the (3hhh) plane is oriented toward the sliding surface 7 side by the Miller index. Is.

As a metal crystal having a bcc structure, F is
Examples thereof include crystals of e, Cr, Mo, W, Ta, Zr, Nb, V, etc., or alloys thereof. The metal crystals having the fcc structure include Pb, Ni, Cu, Pt, and A.
Crystals of a simple substance such as l, Ag and Au or an alloy thereof can be given.

Table 1 and Table 2 show the basic conditions for performing the electric Fe plating process in the plating process for forming the sliding surface structure 8 according to the present invention.

[0022]

[Table 1] As the organic additive, urea, saccharin or the like is used.

[0023]

[Table 2] Tables 3 and 4 show the case of electric Ni plating treatment.

[0024]

[Table 3]

[0025]

[Table 4] In the electric Fe and Ni plating treatments performed under the above-mentioned conditions, depending on the cathode current density, the plating bath pH, the amount of the organic additive, etc., (hhh) oriented Fe crystals and (2hh)
h) oriented Fe crystals or (h00) oriented Ni crystals
And (3hhh) oriented Ni crystals of crystallization, its abundance,
Control the average particle size.

[0026] As the plating process, the outside of the electroplating process, may be mentioned PVD method is an example Ebakisho plating method, CVD method, sputtering method, ion plating or the like. Conditions for performing W and Mo plating by the sputtering method are, for example, Ar pressure of 0.2 to 1.0 Pa, Ar acceleration power of DC 0.5 to 1.5 kW, and base material temperature of 80 to 300.
℃. The conditions for performing Pt and Al plating by the sputtering method are, for example, Ar pressure of 0.8 to 1.0 P.
a, Ar accelerating power: DC 200 to 1000 W, base material temperature 80 to 300 ° C. Conditions for performing W plating by the CVD method are, for example, raw material WF ₆ and gas flow rate.
2 to 15 cc / min, chamber internal pressure 50 to 300 P
a, the base material temperature is 300 to 600 ° C. The conditions for performing Al plating by the CVD method are, for example, raw materials.
Al (CH ₃ ) ₃ , gas flow rate 1 to 10 cc / min, chamber internal pressure 50 to 300 Pa, base material temperature 300 to
It is 600 ° C.

A specific example will be described below.

Nose portion 4 and base circular portion 5 of cam 3 having a chill layer of cast iron base material 2 made of JIS FC25.
Layered by electroplating Fe on the outer surface
A plurality of cam shuffs for internal combustion engines are formed by forming the sliding surface structure 8.
1 was manufactured. The sliding surface 7 of the sliding surface structure 8 is
High surface pressure area A on the rise portion 4 side and low surface pressure area on the base circular portion 5 side
Area B and both areas A and B are Fe crystal aggregates.
Is formed.

Tables 5 to 8 show examples 1 to 12 of the sliding surface structure 8.
The electric Fe plating processing conditions in FIG.

[0030]

[Table 5]

[0031]

[Table 6]

[0032]

[Table 7]

[0033]

[Table 8] Tables 9 and 10 show the crystal morphology of the sliding surface 7 , the particle size of pyramidal Fe crystals, and the abundance S of each oriented Fe crystal in Examples 1 to 12 , respectively.

[0034]

[Table 9]

[0035]

[Table 10] The existence ratio S is obtained by the following method based on the X-ray diffraction diagrams of Examples 1 to 12 (the X-ray irradiation direction is the direction perpendicular to the sliding surface 7). Explaining Example 2 as an example, FIGS. 7 and 8 are X-ray diffraction diagrams of the high and low surface pressure regions A and B in Example 2, and the abundance S of each oriented Fe crystal is calculated from the following equation. Was given. Note that, for example, the {110} oriented Fe crystal means an oriented Fe crystal with the {110} plane facing the sliding surface 4a. {110} oriented Fe crystal: S ₁₁₀ = {(I ₁₁₀ / IA
₁₁₀ ) / T} × 100, {200} oriented Fe crystal: S ₂₀₀ = {(I ₂₀₀ / IA
₂₀₀ ) / T} × 100, {211} oriented Fe crystal: S ₂₁₁ = {(I ₂₁₁ / IA)
₂₁₁ ) / T} × 100, {310} oriented Fe crystal: S ₃₁₀ = {(I ₃₁₀ / IA
₃₁₀ ) / T} × 100, {222} oriented Fe crystal: S ₂₂₂ = {(I ₂₂₂ / IA)
₂₂₂ ) / T} × 100 where I ₁₁₀ , I ₂₀₀ , I ₂₁₁ , I ₃₁₀ , and I ₂₂₂ are the measured values (cps) of the X-ray reflection intensity of each crystal plane, and IA ₁₁₀ , IA ₂₀₀ , and IA. ₂₁₁ , IA ₃₁₀ , and IA ₂₂₂ are the X-ray reflection intensity ratios of each crystal plane in the ASTM card,
IA ₁₁₀ = 100, IA ₂₀₀ = 20, IA ₂₁₁ = 30,
IA ₃₁₀ = 12 and IA ₂₂₂ = 6. Furthermore, T is T
= (I ₁₁₀ / IA ₁₁₀ ) + (I ₂₀₀ / IA ₂₀₀ ) + (I
₂₁₁ / IA ₂₁₁ ) + (I ₃₁₀ / IA ₃₁₀ ) + (I ₂₂₂ /
IA ₂₂₂ ).

9 and 10 are photomicrographs (5000 times) showing the crystal structures of the high and low surface pressure regions A and B of Example 2. In the high surface pressure area A shown in FIG. 9, a number of triangular pyramidal
( Hhh) oriented Fe crystals are observed. This (hh
h) The oriented Fe crystal is a {222} oriented Fe crystal, and the average grain size of the {222} oriented Fe crystal is shown in Table 9.
Is about 4 μm. In the low surface pressure region B shown in FIG. 10, a large number of small pyramidal ( 2hhh) oriented Fe crystals are observed. This small pyramidal (2hhh) oriented Fe
The crystal is a {211} oriented Fe crystal, and the average particle size thereof is about 1 μm as shown in Table 9.

Next, the camshafts of Examples 1 to 12 were assembled in an engine and a seizure test was conducted. The {222} oriented Fe crystals in the high surface pressure region A and the {211} orientation in the low surface pressure region B were tested. When the relationship between the average grain size of the Fe crystals and the surface pressure at which seizure occurred was determined, the results shown in FIG. 11 were obtained. The test conditions are as follows. Camshaft speed 200
0 rpm, oil supply amount 10 ml / min, oil temperature 100 ° C, rocker arm slipper material Fe-based sintered material. Point (1) in the figure
(12) correspond to Examples 1 to 12, respectively. Line x
_{1 to} x ₃ are cases where the crystal structures in the low surface pressure region B are different from each other. Line y shows the case where the outer peripheral surface of the cam 3 is subjected to nitriding treatment, and therefore the nose portion 4 and the base circular portion 5 are not subjected to electric Fe plating treatment.

From FIG. 11, as in Examples 1 and 2, the average grain size of the triangular-pyramidal {222} -oriented Fe crystals in the high surface pressure region A on the nose portion 4 side was increased and the base circular portion 5 side was increased. It can be seen that the seizure-occurring surface pressure is improved by setting the average grain size of the small pyramidal {211} -oriented Fe crystals in the low surface pressure region B of 1.

FIG. 12 shows X in another example of the low surface pressure region B.
FIG. 13 is a line diffraction diagram, and FIG. 13 is a photomicrograph (5000 times) showing its crystal structure. In the low surface pressure region B shown in FIG. 13, a large number of small pyramid- shaped ( hhh) oriented Fe crystals are observed, and the (hhh) -oriented Fe crystals are {22
2} oriented Fe crystals. The abundance S of {222} oriented Fe crystals is S = 45.9%, and the average grain size is
Is about 1 μm. The low surface pressure region B having such {222} oriented Fe crystal and {22
The seizure resistance of the camshaft can be improved in the same manner as described above by combining with the high surface pressure region A having the 2} oriented Fe crystal.

Tables 11 and 12 show the conditions for electroplating Fe in the low surface pressure region B shown in FIG.

[0041]

[Table 11]

[0042]

[Table 12] The average particle diameter D ₁ of the pyramidal metal crystal 9 in the high surface pressure area A is 4 μm ≦ D ₁ ≦ 10 μm, and the pyramidal shape in the low surface pressure area B is different depending on the surface pressure acting on the sliding surface structure 8. The average grain size D ₂ of the metal crystal 10 is 0.5 μm ≦ D ₂ ≦
3 μm is suitable. For example, the surface pressure P _{1 in} the high surface pressure area A is P ₁ ≧ 100 MPa, and the surface pressure P ₂ in the low surface pressure area B is P ₂
When <100 MPa, the average particle size D ₁ is D ₁ = 4 μm
When the abundance S of the pyramidal metal crystals 9 is S ≧ 40%, and the abundance S of the pyramidal metal crystals 10 having an average particle diameter D ₂ of D ₂ <4 μm is S ≧ 40%, sufficient protection is obtained. It is possible to secure oiliness and improve seizure resistance.

As shown in FIG. 14, there are many metal crystal aggregates.
May have the truncated pyramidal metal crystals 9 and 10, and the inclination angle θ in this case is a straight line g passing through the upper bottom central portion e and the lower bottom central portion f and a virtual surface 13 passing through the lower bottom central portion f. Is defined as an angle formed by a reference line d perpendicular to. The range of the inclination angle θ is 0 ° ≦ θ ≦ 30 ° as described above. Money again
The genus crystal aggregate is composed of a large number of pyramids and a large number of truncated pyramids
It may have a metal crystal.

The present invention is not limited to camshafts, but also piston pins, gears, crankshafts, differential pinion shafts, connecting rods, pistons (skirts, lands, ring grooves), rocker arms, valve lifters, bearing metals, bearing inner cases, bearings. Also applicable to outer cases, metal belts, pulleys, etc.

[0045]

According to the present invention, when the sliding surface has a high surface pressure area and a low surface pressure area, the seizure resistance is excellent by specifying the crystal structure of these areas as described above. It is possible to provide a sliding surface structure.

[Brief description of drawings]

FIG. 1 is a sectional view of a camshaft.

FIG. 2 is an enlarged view of a portion indicated by an arrow 2 in FIG.

FIG. 3 is an enlarged view of a portion indicated by an arrow 3 in FIG.

FIG. 4 is an explanatory diagram showing a tilt of a pyramidal metal crystal.

FIG. 5: Body-centered cubic structure and its (hhh) plane, (2h
It is a perspective view which shows the hh) surface.

FIG. 6 is a face-centered cubic structure and its (h00) plane, (3h
It is explanatory drawing which shows the hh) surface.

FIG. 7 is an X-ray diffraction diagram of a high surface pressure region.

FIG. 8 is an X-ray diffraction diagram in an example of a low surface pressure region.

FIG. 9 is a micrograph showing a crystal structure in a high surface pressure region.

FIG. 10 is a micrograph showing a crystal structure in an example of a low surface pressure region.

FIG. 11 is a graph showing the results of a burn-in test.

FIG. 12 is an X-ray diffraction diagram in another example of the low surface pressure region.

FIG. 13 is a micrograph showing a crystal structure in another example of the low surface pressure region.

FIG. 14 is an explanatory diagram showing a tilt of a truncated pyramidal metal crystal.

[Explanation of Codes] 6 Rocker Arm Slipper (Mating member) 7 Sliding surface 8 Sliding surface structure 9,10 Pyramidal, truncated pyramidal metal crystal A High surface pressure area B Low surface pressure area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Hirose 1-4-1 Chuo, Wako City, Saitama Prefecture Honda R & D Co., Ltd.

Claims (1)

[Claims] 1. A sliding surface structure having a sliding surface with a mating member, wherein the sliding surface includes a high surface pressure region and a low surface pressure region, wherein the high surface pressure region and the low surface pressure region are provided. Is composed of an aggregate of at least one of pyramidal metal crystals and truncated pyramidal metal crystals, the average particle size of the metal crystals in the high surface pressure region, the average of the metal crystals in the low surface pressure region A sliding surface structure characterized by being set larger than the particle size.