JP2001349411A - Cam piece and method of manufacturing camshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cam piece having higher level abrasion resistance and scuffing resistance, and a manufacturing method of a camshaft. SOLUTION: This cam piece has a sliding surface satisfying the equation 1: 0.5<= Rvk×(100-Mr2)}/100<=2.0. Here, Rvk is a depth (depth of a groove part dislocated from an effective load roughness Rk) (μm) of an oil reservoir, and Mr2 is a load length ratio 2 (load length ratio corresponding to an lower limit of the effective load roughness Rk) (%). In this first manufacturing method of the camshaft, the cam piece having a sliding surface satisfying the equitation 1 is formed and then the cam piece is pressed into and engaged with a shaft. In the second manufacturing method, the camshaft comprising the cam piece and the shaft is formed, and then the sliding surface satisfying the equation 1 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cam piece used for an internal combustion engine or the like, and a method of manufacturing a cam shaft.
More specifically, manufacture of a cam piece with abrasion resistance and scuffing resistance improved by subjecting the sliding surface of the cam piece to roughening, etc., and a camshaft that exhibits excellent wear resistance based on the cam piece About the method.

[0002]

2. Description of the Related Art As a conventional camshaft for an internal combustion engine, an integrated camshaft made of chill cast iron, an integrated camshaft formed by forging or total cutting, or a cam piece and a shaft are separately provided. There are assembled camshafts etc. which are manufactured and joined by press fitting or diffusion bonding. These camshafts are subjected to a surface treatment or a heat treatment for the purpose of improving abrasion resistance and strength, as required, to give specific properties as a whole. Such camshafts usually use a sliding contact type rocker arm or tappet or a rolling contact type rocker arm or tappet as a mating member.

[0003] A camshaft is required to improve the wear resistance and scuffing resistance of a cam piece which comes into contact with a mating member, and as a means for this, conventionally, the sliding surface of the cam piece has been subjected to steam treatment or phosphate coating. Processing (Lubrite processing) is performed as needed. Camshafts that have been subjected to such treatment to form a steam-treated coating or a phosphate coating have abrasion resistance due to the inherent lubrication of the coating and the oil retention of the porous coating. And improved scuffing resistance.

[0004]

However, since the above steam treatment involves heat treatment, there is a possibility that the camshaft may be distorted or softened, and a further step of correcting the distortion and performing an inspection may be required, thus increasing the cost. There is a problem of bulking. Further, since the phosphate coating treatment is a wet treatment, there is a problem that a dedicated facility is required and management is difficult.
In addition, since the above-described processing is performed on the entire cam piece or the entire camshaft, it is necessary to apply masking or the like in advance to a portion that does not require the processed coating, or to remove the processed coating by paper wrapping or the like after the processing. In addition, there is also a problem that the cost increases because it is necessary to increase a new process.

[0005] Further, although these treated coatings can achieve a certain level of abrasion resistance and scuffing resistance, there is a limit in providing a higher level of abrasion resistance and scuffing resistance.

On the other hand, when a cam piece manufactured by heat treatment such as induction hardening or the like after plastic working by cold forging or the like without using the above-mentioned treatment is used as it is, the black scale formed on the cam piece ( Mill scale) wears over time, so it is difficult to provide a higher level of wear resistance and scuffing resistance, and even when a cam piece whose black scale is ground and removed is used as it is. However, there is a limit to providing a higher level of wear resistance and scuffing resistance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has been made to provide a cam block and a camshaft with a high level of wear resistance and scuffing resistance.
An object of the present invention is to provide a cam piece having excellent wear resistance and a method of manufacturing a camshaft exhibiting excellent sliding performance based on the cam piece.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have intensively studied the factors which affect the surface properties of the sliding surface of the cam piece on the wear resistance and scuffing resistance.

[0009] The surface properties of the conventional sliding surface of the cam piece are in accordance with JIS.
Arithmetic mean roughness R specified in B0601-1994
a, the maximum height Ry, the ten-point average roughness Rz, and the load length ratio tp are measured and compared.

However, these evaluations do not provide a sufficient logical explanation of the effect of the surface texture on the friction and wear between the cam piece and the cam follower, and such a surface texture indicates the abrasion resistance and scuffing resistance. Was insufficient to say that it was

The present inventors have examined the relationship between the surface properties and the wear resistance and scuffing resistance, and found that D
Load curve (BAC), oil sump depth (Rvk), load length ratio 2 specified in IN4776 (German standard)
It has been found that the relationship between the wear resistance and the scuffing resistance can be well explained by using the oil pool area (A2) derived from (Mr2).

Further, it has been found that the characteristic value (A value) of the following equation 2 obtained from the ratio of the oil reservoir area: A2 shows a good correlation with respect to its wear resistance and scuffing resistance. When the A value satisfies the range of 0.5 to 2.0, it was found that excellent abrasion resistance and scuffing resistance were obtained.

[0013]

(Equation 2)

Here, Rvk: oil pool depth (depth of a groove portion deviating from effective load roughness Rk) (μm), Mr2: load length ratio 2 (load length corresponding to the lower limit of effective load roughness Rk) (%).

That is, the cam piece of the first aspect is characterized in that the sliding surface satisfies the following equation (1).

[0016]

(Equation 3)

Here, Rvk is the oil sump depth (the depth of the groove that deviates from the effective load roughness Rk) (μm).
Is the load length ratio 2 (load length ratio corresponding to the lower limit of the effective load length Rk) (%).

According to the present invention, the cam piece sliding surface that satisfies the A value (see Equation 2) within the above range has a sliding surface having an “oil sump” that can effectively hold oil. It is a property. Therefore, when the cam piece of the present invention actually operates as a constituent member of the camshaft, does the action of the cam piece sliding surface excellent in oil retention exert a higher level of wear resistance and scuffing resistance? it can.

A method of manufacturing a camshaft according to a second aspect is characterized in that after forming a cam piece having a cam piece sliding surface satisfying the above formula 1, the cam piece is press-fitted to the shaft. .

According to the present invention, before the cam piece is press-fitted onto the shaft, the cam piece having the cam piece sliding surface that satisfies the A value within the above range is formed. Has a surface property in which an “oil pool” that provides oil retention is formed. Since the camshaft of the present invention is manufactured by press-fitting a cam piece having such a surface property to the camshaft, by the action of the cam piece sliding surface excellent in oil retention,
A higher level of wear resistance and scuffing resistance can be exhibited.

According to a third aspect of the present invention, there is provided a method of manufacturing a camshaft, comprising: forming a camshaft including a cam piece and a shaft;
It is characterized in that a cam piece sliding surface that satisfies the above equation 1 is formed.

According to the present invention, after the camshaft including the cam piece and the shaft is formed, the cam piece sliding surface satisfying the A value within the above range is formed. The surface properties are such that an “oil pool” that provides oil retention is formed. Since the camshaft of the present invention is provided with the cam piece having such a surface property, it exerts a higher level of wear resistance and scuffing resistance by the action of the cam piece sliding surface excellent in oil retention. I can do it.

According to a fourth aspect of the present invention, in the method for manufacturing a camshaft according to the second or third aspect, the sliding surface of the cam piece satisfying the above formula 1 has a particle size of 100 to 250 μm. It is characterized by being formed using a grid or a steel shot of the same size.

According to the present invention, the cam piece sliding surface having the above-mentioned surface properties can be easily formed by performing a roughening treatment using a steel grid having a particle size of 100 to 250 μm or a steel shot having the same size. Thus, a camshaft exhibiting excellent wear resistance and scuffing resistance can be manufactured.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a cam piece 1 and a camshaft 10 according to the present invention will be sequentially described.
FIG. 1 is a perspective view showing an example of a cam piece 1 of the present invention,
FIG. 2 is a perspective view showing an example of the camshaft 10 in which the cam piece 1 and the shaft 11 are integrated.

(1) Cam Piece In the cam piece 1 of the present invention, the cam piece sliding surface 2 has a surface property satisfying the above formula (1). As long as the surface properties are satisfied, the cam piece 1 manufactured by any method or the cam piece 1 having any outer diameter may be used.

That is, the A value (=
{Rvk × (100−Mr2)} / 100) is 0.5
As described above, the cam piece 1 having the cam piece sliding surface 2 that satisfies the range of 2.0 or less is capable of effectively holding oil.
Therefore, when the cam piece 1 actually operates as a constituent member of the camshaft 10, a higher level of wear resistance and scuffing resistance is achieved by the action of the cam piece sliding surface 2 having excellent oil retention. Can be demonstrated.

If the A value is less than 0.5, sufficient oil retaining property cannot be obtained, and when actually operating as a constituent member of the camshaft 10, more excellent wear resistance and scuffing resistance may not be exhibited. . On the other hand, when the A value exceeds 2.0, remarkable initial wear occurs due to a rise in surface pressure based on the coarsely generated cam piece sliding surface 2 when actually operating as a constituent member of the camshaft 10. Sometimes. Note that a more preferable range of the A value is 0.8 to 1.5. The sliding surface 2 having the A value in this range hardly abraded, and exhibited particularly excellent wear resistance and scuffing resistance.

In the present invention, the A value is evaluated by a value derived from a measured value of DIN 4776 which is a German standard. The A value is obtained by the following procedure.

First, a surface roughness curve as shown in FIG. 3A is measured, the value of the load length ratio (tp) is plotted on the horizontal axis, and the direction of the height (cutting height) of the measurement curve is determined. A graph as shown in FIG. 3B is created by plotting the vertical axis.
This graph corresponds to an abscissa of the amplitude distribution curve (ratio of n to N) accumulated from above. Next, as shown in FIG. 4, in the graph, a straight line having the smallest slope among straight lines passing through two points (A, B) where the difference in tp value becomes 40% is obtained. % Tp and 100% t
The points of intersection with p are point C and point D, respectively, and the point of intersection with the cutting level BAC passing through point D is point E.
The point of intersection with% tp is point F. At this time, a point G on 100% tp is determined such that the area surrounded by the line segment DE, the line segment DF, and the curve EF is equal to the area of the triangle DEG. The distance between the points G and D is called Rvk (oil pool depth), the tp value of the point E is called Mr2 (load length ratio), and the area of the triangle DEG is called A2 (oil pool area).

Accordingly, the A value is obtained by calculation based on the Rvk value and the Mr2 value, as shown in the above equation (2).
When the value of A2 is compared with a value α based on a certain measurement result and a value β based on another measurement result, the measurement length of the surface roughness measurement that is the basis of the calculation is If they are different, they cannot be simply compared. Therefore, the value α and the value β are converted into values per unit length, and the same terms are arranged to obtain an A value that is a characteristic value.

As described above, the value A defining the surface properties of the cam piece sliding surface 2 is greatly affected by Rvk (oil pool depth) and Mr2 (load length ratio 2). Rv
Regardless of the magnitude of k and the magnitude of Mr2, ten-point average roughness (Rz, JIS) which is a general evaluation factor of surface roughness
B0601) and center line average roughness (Ra),
As a result, if the A value is within the above-mentioned predetermined range, the intended object of the present invention can be achieved.

In the cam piece 1 of the present invention, its material is
Any material may be used as long as it is used as a general cam piece material, and is not particularly limited. For example, SC material (carbon steel material), SCr material (chromium steel material), SCM material (chromium molybdenum steel material), sintered steel material and the like can be preferably used. In addition, these steel materials can be subjected to quenching and tempering treatment as necessary to improve mechanical properties such as fatigue resistance properties.

As described above, as long as the cam piece sliding surface 2 satisfies the above surface properties, the cam piece 1 manufactured by any method can be any cam piece 1 having any outer diameter. You may. Therefore, (i) when the cam piece 1 is formed, even if the sliding surface 2 satisfying the above formula 1 is formed simultaneously with the formation of the cam piece 1, (ii) after the cam piece 1 is formed. Even if the cam piece 1 has the cam piece sliding surface 2 that satisfies the above equation 1, (iii) after forming the camshaft 10 including the cam piece 1 and the shaft 11, 1 is a cam piece sliding surface 2 that satisfies the above equation 1.
May be formed and is not particularly limited.

As a method of forming the cam piece sliding surface 2 that satisfies the above formula 1, after forming the cam piece 1 or after forming the cam shaft 10 composed of the cam piece 1 and the shaft 11, A roughening process performed on the cam piece sliding surface 2 of the piece 1 can be exemplified.

The cam piece 1 to be subjected to such a roughening process
Are cold forged, integrally forged with shaft, heat treated such as induction hardening after cold forging, cast, integrally cast with shaft, cutting Molded, integrally cut with shaft, sintered, diffusion bonded to shaft, integrally sintered with shaft, or press-fitted to shaft etc,
The cam piece 1 may be formed by various processing methods.
In particular, those subjected to induction hardening after cold forging are excellent in the sliding characteristics of the cam pieces, and thus can be more preferably used.

Also, the cam piece sliding surface 2 of the cam piece 1 before the surface roughening treatment may be any sliding surface formed to a predetermined dimensional accuracy. ), A surface obtained by grinding and removing the black scale, and a sliding surface formed by paper wrapping, and are not particularly limited. In addition, the cam piece 1 in which the sliding surface where black scale was generated by the quenching and tempering treatment was subjected to the roughening treatment as it was, could exhibit more excellent wear resistance and the like.

The method of the surface roughening treatment is not particularly limited, but a method such as shot blasting or shot peening can be preferably applied. In the following,
Unless otherwise specified, it is described that the surface is roughened by a method such as shot blasting or shot peening, but the present invention is not limited to such a method.

The surface properties of the cam piece sliding surface 2 after the surface roughening process vary depending on the type, size or shape of the particles projected on the cam piece sliding surface 2 and the injection pressure of the particles. By controlling these conditions, the surface properties of the cam piece sliding surface 2 can be controlled.
In particular, shot blasting and shot peening
Since it is a physical treatment method, the reproducibility of the treatment is higher than the chemical treatment method, and the cam piece 1 with stable quality such as the surface properties of the sliding surface 2 can be manufactured, which is extremely effective. is there.

The particles used may be spheres or grids obtained by finely cutting wires, and are not particularly limited. The grids are inexpensive and have a sliding surface 2 having an A value in the above-mentioned predetermined range. Is preferably used because it can be easily formed.

When using a grid as particles,
Its size (in this case, used synonymously with the particle size, the size of the sieve is limited, and the size after passing through is shown) is 10
It is preferably in the range of 0 to 250 μm. A grid having a size in this range can easily form the cam piece sliding surface 2 having the A value in the above range. If the grid size is less than 100 μm, it is difficult to form the A value in the above range on the cam piece sliding surface 2. On the other hand, if the grid size is 250
If it exceeds μm, the ejection speed of the grid decreases, and it is difficult to form the A value in the above range on the cam piece sliding surface 2. As such a grid, usually, a steel grid is preferably applied. In the case where spherical particles are used, similarly to the case of the grid described above, particles having a size (diameter) in the range of 100 to 250 μm can be preferably used. For such spherical particles, glass beads, steel shot, alumina, or the like can be used.

The injection pressure of the particles is sequentially set in consideration of the type, size or shape of the particles to be injected and the A value in the above range to be formed. As a specific example, 200
When a steel grid having a size of about μm is used, 0.44 to 0.54 MPa (4.5 to 5.5 kgf
/ Cm ² in the same. It is preferable that the pressure is applied to the cam piece sliding surface 2 by the pressure of (2).

Such a roughening process is usually performed only on the cam piece 1.

For example, with respect to an integrated camshaft integrally manufactured by casting, cutting, or the like, or an assembled camshaft after a cam piece and a shaft are joined, the integrated camshaft 10 is roughened. By setting the nozzle on the rotary table provided in the surface roughing processing device and controlling the nozzle for ejecting particles to eject the particles when the nozzle comes to the position of the cam piece 1, the roughening treatment can be performed only on the cam piece 1. it can. The camshaft 10 rotates on a rotary table about a shaft axis, and is controlled so that one of the camshaft and the nozzle slides continuously or intermittently in the longitudinal direction of the camshaft. At this time, it is preferable to control or mask the journal piece 12 and the end piece 13 attached to the camshaft 10 and the shaft 11 so that the ejected particles do not hit the journal piece 12 and the end piece 13.

In the case of the cam piece 1 used for an assembling type camshaft, the cam piece 1 before being integrated with the shaft 11 is stacked on a jig on a rotary table provided in the roughening device. It is preferable to perform a surface roughening treatment by continuously or intermittently ejecting particles from a nozzle while setting and rotating. At this time, the cam piece sliding surface 2 can be uniformly roughened by moving the jig up and down or moving the nozzle up and down.

When shot peening is applied as the surface roughening treatment, conventionally known effects of shot peening, that is, an increase in the compressive stress on the metal surface, an improvement in the surface strength due to work hardening, etc. And, by changing the cam piece sliding surface 2 to a predetermined surface property, the oil retaining property can be provided, and the wear resistance and the scuffing resistance, which are superior to those of a conventionally known cam, can be exhibited. Can be.

Since the cam piece sliding surface 2 that has been subjected to the surface roughening has a fine and uniform satin-like uneven shape, it can be easily distinguished by external observation.

The cam piece 1 having such excellent characteristics is
The characteristics of the cam piece sliding surface 2 can be remarkably improved by a physical method based on a relatively simple principle of surface roughening treatment. A stable cam piece 1 can be efficiently manufactured.

The cam piece 1 of the present invention not only exhibits excellent wear resistance and scuffing resistance based on the surface properties of the cam piece sliding surface 2 itself, but also has excellent anti-matter attack against a mating member. Properties (the property that the partner member is unlikely to cause scratches, etc.)
have. Such an effect is also based on the surface properties of the cam piece sliding surface 2 described above, and is because the frictional resistance is reduced, and the oil retaining property is improved and the oil film is less likely to break. The mating member of the cam piece 1 of the present invention may be any material as long as it is a wear-resistant material generally employed as a rocker arm or tappet. Specifically, bearing steel such as SUJ2 (JIS symbol) can be given.

Since the cam piece 1 of the present invention is characterized by the surface properties of the cam piece sliding surface 2, the shape of the entire cam piece and the shape of the inner peripheral surface 3 of the cam piece 1 are particularly limited. The present invention is not limited thereto, and can be applied to any shape of the cam piece 1. For example, the cam piece inner peripheral surface 3 has a circular, elliptical, flat, or other curved surface shape, or a hexagonal, octagonal, decagonal, or other rectangular shape. The present invention is also applicable to a device provided with a unit. Further, the material and the structure of the cam piece 1 are not limited, and the present invention can be applied to any cam piece (including one integrated with the shaft 11). And, as long as the cam piece has a characteristic portion of the present invention, it is included in the scope of the present invention.

(2) Manufacturing Method of Camshaft The camshaft 10 can be formed by a method capable of providing a cam piece having the cam piece sliding surface 2 satisfying the above formula (1).
It may be manufactured by any method and may have any shape.

For example, (a) a cam shaft 1 manufactured by forming a cam piece 1 having a sliding surface 2 that satisfies the above formula 1 and joining the cam piece 1 to a shaft;
To a shaft 11 to form a camshaft 10;
A camshaft 10 manufactured by processing the cam piece sliding surface 2 of the camshaft 10 so as to satisfy the above equation (1).
(C) A camshaft 10 manufactured by integrally forming a camshaft 11 composed of the cam piece 1 and the shaft 11, and then processing the cam piece sliding surface 2 of the camshaft 11 so as to satisfy the above equation (1). And the like. In addition,
Methods for manufacturing the camshaft 10 by joining include a method by press fitting and a method by diffusion joining.
As a method of integrally forming the camshaft 10, forging,
There are methods such as casting, cutting, and sintering.

At this time, the method of forming the cam piece 1 and the cam piece sliding surface 2 that satisfies the above equation 1 on the cam piece 1 is as follows.
As described above.

In the present invention, as a first method of manufacturing a camshaft, after forming a cam piece 1 having a cam piece sliding surface 2 satisfying the above formula 1, the cam piece 1 is press-fitted onto a shaft 11. Preferably, a method of combining them can be mentioned.

More specifically, of the camshafts corresponding to the above (a), in the assembled camshaft manufactured by joining the cam piece 1 and the shaft 11 by mechanically press-fitting the same, A cam piece 1 formed by plastic working such as forging is prepared, and its sliding surface is roughened to form a cam piece 1 having a cam piece sliding surface 2 having a predetermined surface property. 1 are sequentially press-fitted onto the shaft 11,
The camshaft 10 is manufactured. The shaft 11 used here is formed by processing a drawn steel pipe into a predetermined size by machining, and then performing a rolling process such as knurling at a predetermined position of the steel pipe to form a protruding portion. The protrusion and the inner peripheral surface of the cam piece are joined by press-fitting.

As a second method for manufacturing a camshaft, a camshaft 10 comprising a cam piece 1 and a shaft 11 is formed, and then a cam piece sliding surface 2 which satisfies the above equation (1).
The method of forming is preferably mentioned.

Specifically, of the camshafts corresponding to (b) and (c) above, the cam piece 1 is joined to the shaft 11 to form an integral part of the camshaft 10 having a predetermined size.
Alternatively, after the cam piece 1 and the shaft 11 are cast, forged, or cut as a single piece to form a camshaft of a predetermined size, the cam piece sliding surface 2 of the camshaft 10 satisfies the above equation Thus, the camshaft 10 is manufactured. In this case, the cam piece sliding surface 2
Preferably, only the roughening treatment is performed. As the means, as described above, the shape, size, position, etc. of the injection nozzle are selected so that the injection nozzle of the surface roughening device can be applied only to the cam piece sliding surface 2. A method of controlling or controlling or a method of masking a part other than the main part can be adopted.

The material constituting the shaft 11 or the shaft portion used for manufacturing the assembled camshaft and the integral camshaft is not particularly limited, and any commonly used material can be used. Can be. The obtained camshaft 10 can be provided with a journal piece 12, an end piece 13, and the like, if necessary, in addition to the cam piece 1 of the present invention.

[0059]

The present invention will be described more specifically with reference to the following examples and comparative examples.

(Example 1) As a raw material for a cam piece, S50C material, which is a carbon steel material, was used. This raw material was cold forged and formed to a predetermined size, and then induction hardened to prepare a cam piece having a black scale (mill scale). Shot blasting was performed on the sliding surface of this cam piece as a roughening treatment to produce a cam piece of Example 1 which is a product of the present invention. Shot blasting is performed using a steel grid (crushed grains having a size (grain size) of 180 μm and a hardness of Hv700 or more).
And use 0.49 MPa (5.0 kg) on the cam piece sliding surface.
f / cm ² ). After the shot blast, the black scale on the sliding surface of the cam piece had disappeared.

Example 2 A cam piece of Example 2 of the present invention was manufactured in the same manner as in Example 1 except that the size of the steel grid was changed to 230 μm and shot blasting was performed.

Example 3 A cam piece according to Example 3 of the present invention was manufactured in the same manner as in Example 1 except that the size of the steel grid was changed to 130 μm and shot blasting was performed.

Comparative Example 1 A high-frequency hardened cam piece of Example 1 was used as it was to obtain a sample of Comparative Example 1. Therefore, the cam piece sliding surface 2 had a black scale (mill scale).

Comparative Example 2 The sliding surface of the induction hardened cam piece of Example 1 was subjected to paper lapping to produce a cam piece of Comparative Example 2.

Comparative Example 3 The sliding surface of the induction hardened cam piece of Example 1 was ground to produce a cam piece of Comparative Example 3.

Comparative Example 4 Shot blasting was performed on the sliding surface of the high-frequency hardened cam piece of Example 1 to obtain a comparative example 4.
Was manufactured. Note that the shot blast here uses spherical glass beads having a particle size of about 150 μm, and the sliding surface of the cam piece is 0.49 MPa (5.0 kgf / c).
m ² ).

Comparative Example 5 A cam piece of Comparative Example 5 was manufactured in the same manner as in Example 1, except that the steel grid was changed in size to 300 μm and roughened.

Comparative Example 6 A cam piece of Comparative Example 6 was manufactured in the same manner as in Example 1 except that the steel grid was changed in size to 80 μm and roughened.

(Evaluation Method) For each of the above test samples,
A motoring test was performed on the engine head alone to evaluate the wear. As the testing machine, an engine head single motoring testing machine was used. Oil temperature: 100 ° C., oil pressure: 0.36
MPa (3.7 kgf / cm ² ), lubricating oil: 10 w3
The test was performed under the following conditions: 0, the number of revolutions of the camshaft: 1350 rpm, and the test time: 300 hours.

The evaluation was performed by examining the appearance of the cam piece and the roller as the mating member after the test, and the surface roughness of the cam piece and the roller.
The value A was calculated from the surface roughness measurement data before and after the test by measuring with a surface roughness measuring device. Further, the wear amount was directly calculated from the surface roughness measurement chart before and after the test. Table 1 also shows the ten-point average roughness (Rz) before and after the test and the oil pool depth (Rvk) after the test.

(Results) The evaluation results are shown in Table 1.

[0072]

[Table 1]

According to the external appearance observation results, the cam pieces 1 of Examples 1 to 3 were the nose top, the open lamp, the base,
No sliding flaw was observed on any of the sliding surfaces 2 of the closed lamp, indicating excellent wear resistance. On the other hand, in the cam pieces 1 of Comparative Examples 1 to 6, sliding flaws were observed on the cam piece sliding surface 2 and the roller surface as compared with Example 1. In particular, in Comparative Examples 2 and 3, a slightly deep sliding flaw was observed.

Regarding the amount of wear, in the cam pieces 1 of Examples 1 to 3, no difference was observed in the measurement chart, and the amount of wear could not be measured.
It was recognized that the cam piece 1 of No. 6 was abraded compared to the cam pieces 1 of Examples 1 to 3. In particular, Comparative Example 1,
The wear of the cam piece 1 of No. 4 was remarkable.

[0075]

As described above, the cam piece 1 according to the present invention is provided.
According to the above, the cam piece sliding surface 2 which satisfies the A value in the predetermined range
Has a surface property capable of holding oil effectively. Therefore, when the cam piece 1 of the present invention actually operates as a constituent member of the camshaft 10, a higher level of wear resistance and scuffing resistance is exhibited by the action of the cam piece sliding surface 2 having excellent oil retention. can do.

According to the first method of manufacturing the camshaft 10 of the present invention, before the cam piece 1 is press-fitted onto the shaft 11, the cam having the cam piece sliding surface 2 satisfying the A value within a predetermined range. The cam piece 1 is formed, and then the cam piece 1 is press-fitted onto the shaft 11 to produce a high level of wear resistance and scuffing resistance by the action of the cam piece sliding surface 2 having excellent oil retention. And stable and easy production.

According to the second method of manufacturing the camshaft 10, after the camshaft 10 including the cam piece 1 and the shaft 11 is formed, the cam piece sliding surface 2 is set to an A value within a predetermined range. Since it is formed so as to satisfy, it is possible to exhibit a high level of wear resistance and scuffing resistance by the action of the cam piece sliding surface 2 having excellent oil retention.
Easy and stable manufacturing can be performed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a cam piece of the present invention.

FIG. 2 is a perspective view showing an example of a camshaft in which a cam piece and a shaft are integrated.

FIG. 3 shows a surface roughness curve (a) measured for calculating an A value and a load length ratio (t) based on the surface roughness curve.
It is the graph (b) created by plotting p) and the height of the measurement curve.

FIG. 4 is a graph for calculating an A value.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cam piece 2 Cam piece sliding surface 3 Inner peripheral surface 4 Side surface 5 Nose part 6 Base part 10 Cam shaft 11 Shaft 12 Journal piece 13 End piece

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F01L 1/04 F01L 1/04 C J 1/08 1/08 A

Claims (4)

[Claims] 1. A cam piece having a sliding surface that satisfies the following equation (1). (Equation 1) Here, Rvk is the oil sump depth (the depth of the groove portion deviating from the effective load roughness Rk) (μm), and Mr2 is the load length ratio 2 (the load length corresponding to the lower limit of the effective load length Rk). rate)
(%). 2. A method for manufacturing a camshaft, comprising: forming a cam piece having a cam piece sliding surface that satisfies Expression 1 according to claim 1; and then press-fitting the cam piece to a shaft. 3. A method of manufacturing a camshaft, comprising: forming a camshaft comprising a cam piece and a shaft, and then forming a cam piece sliding surface satisfying the expression 1 according to claim 1. 4. The cam piece sliding surface satisfying the expression 1 according to claim 1 is formed by using a steel grid having a particle size of 100 to 250 μm or a steel shot having the same size. A method for manufacturing the camshaft according to claim 2 or 3.