JPH05306602A - Surface treating method for aluminum alloy valve lifter and aluminum alloy valve lifter - Google Patents

Abstract

PURPOSE:To provide a highly reliable light valve lifter, which is excellent in sliding properties, eliminates unevenness in the thickness of a film such as build-up and the need for post machining, and is used for the valve gear of an internal combustion engine. CONSTITUTION:An aluminum alloy valve lifter 1 is provided with an aluminum alloy valve lifter 1a having a cylinder-like section 1b and partition section 1c in the direction to cross the axial direction of the cylinder-like section 1b and letting one side of the partition section 1c be a crown face section 1b and the other side be a skirt section 1e. The aluminum alloy also has chamfered sections 1g and 1g comprising each external peripheral side end of the crown face section 1d and the skirt section 1e of the valve lifter body 1a notched and has a Ni electric plating film 8 formed by electric plating on the external periphery of the cylinder-like section 1b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve lifter used in a valve operating mechanism of an internal combustion engine, and more specifically, it directly transfers a cam lift amount due to rotation of a cam shaft to an intake valve or an exhaust valve. The present invention relates to a surface treatment method for an aluminum alloy valve lifter of a drive type valve mechanism and an aluminum alloy valve lifter.

[0002]

2. Description of the Related Art As a valve lifter used in a valve operating mechanism of an internal combustion engine, there is, for example, one used in a valve operating mechanism as shown in FIG.

FIG. 3 is a longitudinal sectional view of an external shim type direct drive valve operating mechanism which is often used in internal combustion engines. In the figure, 1 is a valve lifter, 2 is a cylinder head, 3 is a valve spring, and 4 is a valve spring. Is a stem of an intake / exhaust valve, 5 is an adjusting shim, and 6 is a camshaft.

Conventionally, as the valve lifter 1, a valve lifter body made of chromium steel or chromium molybdenum steel, which is excellent in wear resistance and fatigue strength, is carburized and quenched. However, the specific gravity (density) of steel is 7.8 (g
/ Cm ³ ), the inertial weight is large, and the spring load must be increased in order to accurately transmit the cam lift amount to the valve under high-speed operating conditions of the internal combustion engine. However, the increase of spring load has a drawback of increasing friction loss and increasing fuel consumption.

Therefore, in order to reduce the fuel consumption,
In order to reduce the weight of the valve lifter and thereby reduce the load of the valve spring, various proposals have been made to manufacture the valve lifter from a lightweight material having a small specific gravity.

In particular, many proposals have been made to make the valve lifter main body made of an aluminum alloy (for example, JP-A-58-101204 and JP-A-62-62).
107213, Japanese Patent Laid-Open No. 62-63105, Shokai Sho 6
2-183005, JP-A-1-106909, JP-A-3-149304).

However, when the valve lifter body is made of aluminum alloy, the following problems occur.

That is, as shown in FIG. 3, the outer peripheral side of the valve lifter 1 slides on the wall surface of the guide hole 2a provided in the cylinder head 2 by reciprocating motion. Since aluminum alloy is generally used for the cylinder head 2, as a result, the aluminum alloy slides on the outer peripheral surface of the valve lifter and the wall surface of the guide hole. The sliding characteristics due to the combination of such aluminum alloys are poor, and wear and seizure are likely to occur.

Therefore, when the valve lifter main body is made of an aluminum alloy, it has been proposed to perform a surface treatment on the outer peripheral side.

The surface treatment method of the valve lifter body is roughly classified into electroplating, electroless plating and thermal spraying, and various treatments using these methods have been proposed.

However, these processing methods have various problems.

That is, in the thermal spraying method, the method of bonding the coating film and the base material is mechanical bonding by causing molten particles constituting the coating composition to collide with the base material at high speed, and the coating is also formed by depositing the molten particles. It Further, in the film formation process, the molten particles that have collided solidify and shrink as they cool, so that pores are created in the film. Therefore, with regard to the adhesiveness of the film, problems such as peeling are constantly eliminated,
This is an unreliable method. Furthermore, the uniformity of the coating is poor, and it must be machined after thermal spraying, which complicates the process.

On the other hand, the electroless plating method has the advantage that the film thickness is more uniform than other methods, but the plating solution is easily affected by temperature, impurities, etc. Is often difficult. Further, if the solution life is short and the plating solution is expensive, the cost is greatly affected.

In Japanese Patent Laid-Open No. 3-217603, which discloses "a method for treating wear resistance of a direct-type valve lifter",
It describes the difficulty of applying the electroless plating method to the outer peripheral side of the valve lifter, and the adhesion between the base material and the film is poor.
It is described that peeling is likely to occur. The reason for this is not clear, but the effects of the above factors are considered to be sufficient. Further, it also describes a coating in which ceramic particles are composited, and the content of the ceramic particles varies in the electroless plating method. This is also an example of the difficulty of liquid management.

On the other hand, in the electroplating method, since ions are electrically generated and bonded to the object to be plated, there is no difficulty of liquid management as in the electroless plating method, and the life of the liquid can be semipermanently used. , Excellent in cost performance.

In the above-mentioned Japanese Patent Laid-Open No. 3-217603, the advantages of the electroplating method are good adhesion and stability of the ceramic particle content when the ceramic particles are compounded.

However, a drawback of the electroplating method is that build-up (as shown in FIG. 4), the valve lifter body 1a is
As represented by the phenomenon that the film 8 becomes thicker at the corners of
The non-uniformity of the film thickness is included.

As a measure against this, in JP-A-1-106909 which discloses "aluminum alloy valve lifter", electroless plating and electroplating are used together in surface treatment of the valve lifter in order to obtain good dimensional accuracy and sliding characteristics. I am going to do it. That is, electroless plating is applied to a portion that cannot be processed and requires dimensional accuracy.

This "aluminum alloy valve lifter"
In the examples, the Fe-P plating is mentioned as the electroplating, but the Fe plating solution used for this has the problem of oxidation, the solution management is difficult, the problem of adhesion occurs, etc. If you combine the above two times, it can be said that the cost is quite severe.

Further, in the above-mentioned Japanese Patent Laid-Open No. 3-217603, the outer peripheral side of the valve lifter is electroplated and then finished. Again, this is not a good idea when considering the cost, because the number of finishing steps increases and becomes complicated.

As described above, when the valve lifter main body is made of an aluminum alloy, it is apparent that surface treatment on the outer peripheral side is necessary to obtain good sliding characteristics.

[0022]

As described above, when the valve lifter main body is made of an aluminum alloy, surface treatment methods for obtaining good sliding characteristics include thermal spraying, electroless plating and electroplating. However, in thermal spraying, there is a problem of reliability due to peeling, etc., in electroless plating, there is a problem of reliability of the film due to difficulty of liquid management, and in electroplating, there is a problem of non-uniformity of film thickness. Come on.

As a surface treatment method for the valve lifter body,
The most reliable method is electroplating, if non-uniformity of the coating is not taken into consideration.

Therefore, in the electroplating method, if the nonuniformity of the film thickness is improved, a surface treatment having a higher reliability than other methods can be provided at a low cost without including a post-processing step. And to improve the non-uniformity of the film thickness,
By forming a film in which ceramic particles are dispersed as described in JP-A-3-149304 which discloses "aluminum alloy valve lifter", it is possible to obtain sufficiently excellent sliding characteristics even if the film thickness is thin. It is effective to use electroplating which can be performed.

Such an electroplating method is superior in adhesion to other surface treatment methods, ie, electroless plating method and thermal spraying method, and is also excellent in sliding property (for example, a film).
As described above, it is possible to reliably obtain a film made of composite plating in which ceramic particles are dispersed.
It cannot be said that the problem of non-uniformity of the film thickness such as the build-up shown in Fig. 4 has been sufficiently solved.
There is a problem that it is difficult to obtain the accuracy of the clearance with the guide hole of the cylinder head without the post-processing.

[0026]

SUMMARY OF THE INVENTION The present invention has been conceived in view of the problem of the electroplating method in the surface treatment on the outer peripheral side of such an aluminum alloy valve lifter body. A lightweight aluminum alloy that is difficult to build up at the corners, eliminates the problem of non-uniformity of the electroplating film thickness applied to this part, and has excellent valve clearance without finishing. The purpose is to provide a valve lifter made from it.

[0027]

A surface treatment method for an aluminum alloy valve lifter according to the present invention has a tubular portion and a partition portion in a direction intersecting the tubular axis direction of the tubular portion, When performing a surface treatment on the outer peripheral side of the tubular portion of the aluminum alloy valve lifter body in which one side of the partition portion is a crown surface portion and the other side is a skirt portion,
Before the surface is formed, the outer peripheral side end of each of the crown surface portion and the skirt portion of the valve lifter body is cut out to form a chamfered portion, and then electroplating is performed as a surface treatment so that the outer peripheral side of the tubular portion is formed. Si ₃ in the Ni-P base
N ₄ and that the particles are dispersed, is characterized in that Si ₃ N ₄ particles in Ni-P-Co-based base is configured to form a Ni-based electroplated film made of those dispersed.

In one embodiment of the surface treatment method for an aluminum alloy valve lifter according to the present invention, the valve lifter main body is subjected to the surface treatment on the outer peripheral side of the cylindrical portion of the valve lifter main body before the surface treatment. Of the crown surface and the skirt are cut out to form chamfers at the outer peripheral ends thereof, and then electroplating is performed as a surface treatment, whereby Ni is the main component on the outer peripheral side of the tubular portion and a Ni-P system is used. It is possible to form a particle-dispersed composite Ni-based electroplating film having a thickness of 5 to 15 μm in which ceramic particles are dispersed in a matrix, and in another embodiment, before performing the surface treatment, a valve lifter is used. By forming a chamfer by notching the outer peripheral side end of each of the crown surface portion and the skirt portion of the main body, and then performing electroplating as surface treatment, A particle-dispersed composite Ni-based electroplating film containing Ni as a main component and ceramic particles dispersed in a Ni-P-Co-based matrix and having a thickness of 5 to 15 μm may be formed on the outer peripheral side of the cylindrical portion. it can.

The aluminum alloy valve lifter according to the present invention has a tubular portion and a partition portion in a direction intersecting the tubular axis direction of the tubular portion, and one side of the partition portion is a crown surface portion. And a valve lifter body made of an aluminum alloy having the other side as a skirt portion, each of which has a chamfered portion in which the outer peripheral side end of the crown surface portion and the skirt portion of the valve lifter body is cut out, and the outer peripheral side of the cylindrical portion is electrically _Si 3 _{N 4} particles in Ni-P-based base by plating and which is dispersed, Si ₃ in Ni-P-Co-based base
The present invention is characterized in that a Ni-based electroplating film made of, for example, N ₄ particles dispersed therein is formed.

In one embodiment of the aluminum alloy valve lifter according to the present invention, each of the crown surface portion and the skirt portion of the valve lifter main body has a chamfered portion at the outer peripheral side end portion and the outer peripheral side of the cylindrical portion. Particle-dispersed composite Ni having a thickness of 5 to 15 μm in which Ni is the main component on the outer peripheral side of the tubular portion and ceramic particles are dispersed in the Ni-P matrix, by electroplating
In another embodiment, the valve lifter main body has a chamfered portion in which the outer peripheral side end portions of the crown surface portion and the skirt portion are cut out, and the cylinder is formed. Since the outer peripheral side of the cylindrical portion is electroplated, the outer peripheral side of the tubular portion has N
A particle-dispersed composite N containing i as a main component and ceramic particles dispersed in a Ni-P-Co base with a thickness of 5 to 15 m.
The i-type electroplating film may be formed.

The aluminum alloy valve lifter according to the present invention has a tubular portion and a partitioning portion in a direction intersecting the tubular axis direction of the tubular portion, and one side of the partitioning portion serves as a crown surface portion and An aluminum alloy valve lifter body having a skirt on the other side is provided. Examples of the aluminum alloy as a material of the valve lifter body include, for example, Al-Si alloys, Al-Cu alloys,
Al-Cu-Mg-based alloys, Al-Zn-Mg-Cu-based alloys, and the like are used, and these are manufactured by a melting method, a powder metallurgy method, or the like. Further, a composite material in which a hard substance such as ceramic particles is dispersed by the above manufacturing method can also be used.

In manufacturing a valve lifter body made of such an aluminum alloy, for example, a shape close to the shape of the valve lifter body is cold or hot forged by using a molten material or an extruded material of powder, and then, After the heat treatment of T6 or T7, cutting is performed into the shape of the final valve lifter body. Then, in this case, the chamfered portion is formed by notching the outer peripheral side end portions of the crown surface portion and the skirt portion of the valve lifter body.

After the chamfered portions are formed by notching the outer peripheral sides of the crown surface portion and the skirt portion of the valve lifter body as described above, the valve lifter body is set on a plating jig and subjected to degreasing, pickling, base treatment, and electroplating treatment. Sequentially applied, and on the outer peripheral surface is formed a Ni-based electroplating film containing Ni as a main component and P, and optionally Co and the like, and further including ceramic particles such as Si ₃ N ₄ dispersed therein. A baking process is performed.

Although the recess for inserting the tip made of the iron-based alloy may be provided in the sliding contact portion with the valve stem by machining, it is preferable to form it in the forging step in terms of strength and reduction of manufacturing cost. Desirable.

Then, a tip made of an iron-based alloy is integrated into the recess of the valve lifter body by press fitting or crimping, and then finished into a final valve lifter shape by machining.

As the hard particles and reinforcing fibers contained in the aluminum alloy, powders of carbides, oxides, nitrides, silicides, borides and the like, alloy powders and fibers can be used.

In the present invention, using Ni as the main component of the plating film is superior to Fe-based plating in terms of rust prevention and stabilization in the manufacturing process, and wear resistance of the valve lifter body is also improved. This is because it is possible to provide a valve lifter that exhibits sufficient wear resistance to the cylinder even if the plating is mainly made of Ni by improving the properties.

By the way, the end portion (edge portion) on the outer peripheral side of the valve lifter is usually chamfered in order to enhance the lubrication effect during operation or to cause a partial contact between the valve lifter and the guide hole. However, this manufacturing step is performed after the plating step because build-up occurs in the chamfering step when surface treatment such as electroplating that makes the film thickness uneven is performed. However, if this is done by cutting, cracks occur at the edges of the film, and there is a problem with the reliability of the film in terms of adhesion and the like.

Furthermore, in order to prevent cracks at the edge of the film,
When this is done by polishing, it cannot be done under the same conditions because the hardness of the aluminum alloy and the plating film are different, and as a result, the processing time increases or the number of processes increases. Will end up.

Although such a problem is associated with nonuniformity of the film thickness of electroplating, particularly build-up, the problem of nonuniformity of the film thickness is eliminated to improve reliability. A film having excellent properties can be provided at low cost.

Therefore, in the present invention, this chamfering step is carried out in advance before the electroplating treatment step, and chamfering is performed by polishing or the like, and after the electroplating treatment, post-machining such as chamfering is not performed. It was decided to. That is, as shown in FIG. 4, build-up is caused by a thick film formed on the edge portion (corner portion) of the aluminum alloy valve lifter body that is the object of electroplating. Therefore, buildup can be prevented or reduced by removing the edge portion by chamfering or the like before the electroplating process.

However, since the outer peripheral side of the valve lifter has severe sliding characteristics, excellent sliding characteristics are required for this electroplating film. Therefore, even if the edges are chamfered before electroplating, the coating is required to have a thickness commensurate with the performance of the sliding characteristics.If the performance is poor, the coating thickness must be increased. However, if the thickness is increased, the effect of reducing build-up disappears, and even if the effect of reducing build-up is obtained, a problem occurs in the non-uniformity of the film thickness other than at the edge portion. As a result, post-processing is required, leading to an increase in processing steps.

Therefore, in the present invention, the effect of reducing buildup is enhanced by using an electroplating film having excellent sliding characteristics even if the film thickness is thin. That is, if the film thickness is thin, the effect of buildup reduction by chamfering is enhanced accordingly, and further, by obtaining an appropriate film thickness, the problem of buildup is eliminated. Also,
The non-uniformity of the film thickness other than at the edge part does not become a problem by reducing the film thickness. Therefore, the problem of clearance between the valve lifter and the guide hole of the cylinder head can be solved without post-processing.

As the electroplating film used in the present invention,
P: 1 to 10 wt%, for example, as the ceramic particles in the Ni-P-based base balance of Ni _Si 3 _{N 4} particles at an area ratio of 10 to 25 vol% Dispersed particle dispersed composite N
An i-based electroplating film can be used. in this case,
If the P content is less than 1% by weight, the seizure resistance becomes insufficient, and if it is more than 10% by weight, the toughness of the plating film is reduced and peeling may occur in a valve lifter with high stress.

In addition to the above P: 1 to 10% by weight,
In order to further improve the heat resistance of the film, Co is added to 20 to
You may add 70 weight%. In this case, the Co content is 2
If it is less than 0% by weight, the effect of improving the heat resistance is not obtained so much, and if it is more than 70% by weight, the hardness decreases and the cost becomes expensive, which is not preferable.

With such an electroplating film, a film thickness of 5 to 15 μm is sufficient, and by chamfering before the surface treatment, there is no buildup problem or a slight buildup problem. As a result, no post-process is required, and further, a highly reliable and excellent valve lifter can be provided at a low cost by improving productivity and reducing material cost by applying thin plating.

Here, as the electroplating film, the above N
It is preferable to select the one in which Si ₃ N ₄ particles are dispersed in the i-P-based matrix or the one in which the Si ₃ N ₄ particles are dispersed in the Ni-P-Co-based matrix. _{Even if 3} P is deposited and hardness is not increased, Si ₃ N
_This is because excellent sliding characteristics are exhibited by dispersing the ₄ particles. Furthermore, because of its excellent sliding properties, the film thickness is 5
˜15 μm is sufficient, and therefore, the dimensional accuracy is extremely good, and the coating surface is smooth, so that it can be used as it is after plating. By having.

When the hard particles are dispersed in the above electroplated film matrix, SiC, alumina or the like can be used, but Si ₃ N ₄ is much more preferable than these. Conventionally, Si having an average particle size of about 3 to 10 μm
A film in which C is dispersed in a Ni-P system plating is also known, but since it tends to wear the mating cylinder head material and has poor adhesion, it is used in combination with a conventional aluminum alloy. Has a problem. Further, there is a drawback that the plated surface becomes rough and finishing by machine processing such as centerless polishing is required.

On the other hand, since Si ₃ N ₄ has a lower hardness than SiC, it does not wear the cylinder head material of the other party and is excellent in seizure resistance. Si _{3 with the} above particle size
The amount of N ₄ dispersed is preferably 10 to 25 area%,
If it is less than 10% by area, the performance in terms of seizure or wear may be insufficient, and if it exceeds 25% by area, the film becomes brittle and chipping or peeling easily occurs, and the surface roughness after plating is It can grow.

The Si ₃ N ₄ dispersion-plated film has a high temperature (350 to 40) like a conventionally known Ni-P-SiC film.
By holding at 0 ° C.), Ni ₃ P is precipitated, and even if the hardness is not increased, the sufficiently dispersed sliding properties of Si ₃ N ₄ exhibit sufficiently excellent sliding characteristics.

Therefore, the valve lifter body made of an aluminum alloy will not be overaged. And Si ₃
Since the N ₄ dispersed plating layer has excellent sliding properties, the thickness of the plating film is sufficient to be 5 to 15 μm. Therefore, the dimensional accuracy is extremely good and the film surface may be smooth. Can be used as it is, or can be used simply by smoothing the surface of the valve lifter as a lot with a vibrating barrel or the like. As a result, conventionally, a method of providing a thick surface coating such as thermal spraying or Fe plating and then performing centerless grinding in order to improve dimensions and surface roughness was also performed. However, in the present invention, centerless grinding is also performed. It is not necessary, and it is not necessary to increase the wall thickness of the valve lifter for the cylinder.

The average particle size of the Si ₃ N ₄ particles is 0.5.
It is desirable to set the thickness to 2 μm, and if it is within this range, it is possible to prevent wear of the mating cylinder head material, and to disperse the stress when subjected to thermal expansion or mechanical stress, and to prevent the peeling of the plating film. It is hard to wake up. Further, if the average particle size is smaller than 0.5 μm, the sliding properties are poor, and if it is larger than 2 μm, the surface of the plating film becomes rough,
In addition to requiring finishing work, the stress dispersion effect decreases,
There is also a risk of plating peeling or chipping.

Further, if it is less than 0.5 μm, it is too fine and the sliding characteristics are not good, and if it is more than 2 μm, it is difficult to obtain a uniform dispersion, and the surface of the film after plating becomes rough and the finish by centerless polishing is performed. Since machining may be required, it becomes necessary to increase the thickness of the cylindrical portion, which hinders weight reduction.

The portion of the valve lifter that is in sliding contact with the valve stem is preferably made of an iron-based material. Since aluminum alloy has a lower strength than iron-based materials, it is desirable to prevent deformation. Then, among the iron-based material, hardness of appropriate ones of H _R C50 or higher materials,
For example, a carburized and hardened material of SCM420 and a liquid phase sintered iron-based sintered material containing a large amount of chromium are optimal.

In the structure of the present invention, the outer peripheral end of the valve lifter is chamfered by polishing or cutting before the surface treatment, and the subsequent surface treatment on the outer peripheral side of the valve lifter is performed by electroplating. The coating of 5 is a particle-dispersed composite electroplated coating in which ceramic particles such as Si ₃ N ₄ are dispersed in a Ni-P base or a Ni-P-Co base containing Ni as a main component.
The thickness is 15 μm.

As a result, the nonuniformity of the film thickness such as build-up, which is a problem in the electroplating method, can be completely eliminated. As a result, no post-processing is required and no chamfering is performed, so that the film is not cracked. Since it does not occur, it is possible to obtain a valve lifter having excellent adhesion and high reliability and also excellent sliding characteristics.

As described above, the surface treatment used in the present invention has a large coating thickness, as represented by thermal spraying.
Not suitable for surface treatment methods with poor surface roughness. Also, as in the electroless plating method, although the film thickness is uniform or the surface roughness is excellent, there is a problem in the reliability of the film adhesion and performance (in this case, sliding characteristics are the main). Even if one is applied to the present invention, the effect cannot be expected.

A surface treatment method which can sufficiently obtain the effects of the present invention is electroplating. In other words, by solving the problems due to non-uniformity of the film thickness in the electroplating method and applying a film with excellent adhesion and sliding characteristics to the valve lifter, an aluminum alloy with high reliability and excellent cost performance To provide a valve lifter made.

However, it is not always necessary to use the electroplating method. That is, the object of the present invention is to focus on the problem of non-uniformity of the film thickness in the valve lifter surface treatment, to provide a film of uniform thickness, excellent in reliability and inexpensive without post-processing. To do. For this reason,
Even if it is electroless plating, it can be applied if there is a problem of non-uniformity of the film such as build-up. Furthermore, even in the case of the film by electroplating, it has excellent sliding characteristics and it is sufficient even if it is thinly applied. It is not always necessary to use the coating of the present invention as long as it has characteristics, and it is difficult to apply the present invention to those having a thick coating due to the sliding characteristics.

Further, the present invention is mainly aimed at improving the film thickness of the surface treatment. Therefore, the valve lifter body is not necessarily made of an aluminum alloy, but may be a light alloy which can be electroplated. That is why.

[0061]

EXAMPLES Hereinafter, the aluminum alloy valve lifter according to the present invention will be described with reference to examples.

FIG. 1 shows a valve lifter of a direct drive type valve operating mechanism embodying the present invention. In the valve lifter 1 of this embodiment, the valve lifter body 1a is made of an aluminum alloy, has a tubular portion 1b, and has a partition portion 1c in a direction intersecting the tubular axis direction of the tubular portion 1b. Si ₃ N ₄ particles were dispersed in the Ni-P matrix by electroplating on the outer peripheral side of the cylindrical portion 1b of the valve lifter body 1a having one side of the partition 1c as the crown surface 1d and the other side as the skirt 1e. Monoya, Ni-P-Co
It has a structure in which a Ni-based electroplating film 8 made of, for example, Si ₃ N ₄ particles dispersed in a system base is formed, and an adjusting shim that comes into contact with a cam is inserted into the crown surface portion 1d. A ring-shaped recess 1f is formed in the skirt portion 1e in contact with the valve stem, and a pad 9 made of an iron-based or ceramic-based hard material is fixed to the recess 1f by caulking or the like. There is.

Next, an example of a method for manufacturing the valve lifter will be described.

First, the composition equivalent to JIS A 4032 (A
(1-12% Si-1% Cu-1% Mg) continuous casting material (round bar) is molded into a forging material shape, and this forging material is forged into a shape close to the valve lifter body, and T-6 treatment is performed. After being applied, cutting is performed to form the valve lifter body 1a shown in FIG.

At this time, in addition to cutting into the shape of the valve lifter body 1a, the crown surface portion 1d of the valve lifter body 1a is cut.
The chamfered portions 1g and 1g are formed by cutting out the outer peripheral side end portions of the skirt portion 1e. In this case, it is desirable that the angle, length, shape, etc. of the chamfered portions 1g, 1g be appropriately selected according to the thickness of the Ni-based electroplating film 8 formed on the outer peripheral side. Then, the angle of the chamfered portions 1g and 1g is set to 20 °.

Next, the concave portions on the side of the crown surface 1d and the skirt portion 1e were masked so that the plating solution would not attach, and the average particle diameter was 0.8 μm in the Ni-2 wt% P alloy.
The particle-dispersed composite Ni-based electroplating film 8 in which the Si ₃ N ₄ particles were dispersed in an area ratio of 16.5% was formed by an electroplating method. At this time, in addition to the film thickness of 10 μm,
We manufacture films with film thicknesses of 20 μm and 50 μm,
An aluminum alloy valve lifter 1 was obtained.

FIG. 2 shows the cross-sectional structure of the coating on the valve lifter 1 at this time. The observed portion is the outer peripheral side end of the crown portion 1d, the outer peripheral side end of the skirt portion 1e, and the central portion. When the coating thickness is 10 μm, there is no build-up on the outer peripheral side end portion, and the central portion has a uniform coating thickness. On the other hand, when the film thickness is 20 μm, a slight build-up is recognized at the outer peripheral side end, and when it is 50 μm, a clear build-up is recognized despite the chamfering, and the center part It can be seen that the film thickness becomes non-uniform and the surface is wavy.

When the valve lifter subjected to these surface treatments was not post-processed and mounted in an actual machine in this state and a durability test was carried out, the valve lifter with a film thickness of 10 μm showed almost no wear and the cylinder head -There was almost no wear on the guide holes.

On the other hand, when the coating thickness was 20 μm, the outer peripheral end of the crown surface and the outer peripheral end of the skirt were strongly hit and the wear was large. In addition, the cylinder head and guide holes were also heavily worn, and many scratches that were scratched with hard objects were seen. Furthermore, 50 μm
Then, it was confirmed that the outer peripheral side end of the crown surface portion and the outer peripheral side end of the skirt portion were significantly worn, and the central portion also had a locally large amount of wear. Then, the cylinder head and the guide hole were also significantly worn.

Thus, the film thickness is 20 μm, and 5
In a 0 μm valve lifter, the contact surface pressure with the cylinder head / guide hole is locally high due to the non-uniformity of the film thickness, which causes significant wear to the valve lifter and the cylinder head / guide hole. Admitted.

In the durability test, the outer diameter of the valve lifter body is adjusted in advance according to the film thickness in order to keep the clearance between the cylinder head and the guide hole constant.

[0072]

As described above, according to the present invention, since it is possible to eliminate the occurrence of uneven film thickness such as build-up, it is possible to eliminate the need for post-processing and to improve the sliding characteristics. It is possible to provide a highly reliable and lightweight valve lifter at low cost, which is a remarkably excellent effect.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view of an aluminum alloy valve lifter according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a state of the electroplated film when the film thickness is set to 10 μm, 20 μm and 50 μm by the electroplating method in the example of the present invention.

FIG. 3 is a cross-sectional explanatory view showing a valve mechanism of an internal combustion engine.

FIG. 4 is a cross-sectional explanatory view showing a state of a film thickness (a state in which a buildup portion is formed) by an electroplating method that occurs when a valve lifter body has a corner portion.

[Explanation of symbols]

 1 Valve lifter 1a Valve lifter main body 2b Cylindrical part 1c Partition part 1d Crown face part 1e Skirt part 1g Chamfer part 8 Ni-based electroplating film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masayuki Chosei, 1-37 Hokuto-cho, Kashiwazaki-shi, Niigata Riken Kashiwazaki Plant (72) Inventor Takashi Watanabe 1-37, Hokuto-cho, Kashiwazaki-shi, Niigata Inside the Kashiwazaki Plant of RIKEN Co., Ltd.

Claims (6)

[Claims] 1. An aluminum having a tubular portion and a partition portion in a direction intersecting a tubular axis direction of the tubular portion, wherein one side of the partition portion is a crown surface portion and the other side is a skirt portion. When performing a surface treatment on the outer peripheral side of the tubular portion of the alloy valve lifter main body, a chamfered portion is formed by notching the outer peripheral side end portions of the crown surface portion and the skirt portion of the valve lifter main body before performing the surface treatment, A surface treatment method for an aluminum alloy valve lifter, characterized by forming an Ni-based electroplating film on the outer peripheral side of the tubular portion by applying electroplating as a surface treatment thereafter. 2. When the outer peripheral side of the tubular portion of the valve lifter main body is subjected to surface treatment, before the surface treatment, each of the crown surface portion and the skirt portion of the valve lifter main body is cut out to form a chamfered portion. Then, by electroplating as a surface treatment, Ni is formed on the outer peripheral side of the tubular portion.
The aluminum alloy valve lifter according to claim 1, wherein a particle-dispersed composite Ni-based electroplating film having a thickness of 5 to 15 μm in which ceramic particles are dispersed in a Ni—P-based matrix as a main component is formed. Surface treatment method. 3. When a surface treatment is applied to the outer peripheral side of the tubular portion of the valve lifter body, the chamfered portion is formed by notching the outer peripheral side end portions of the crown surface portion and the skirt portion of the valve lifter body before the surface treatment. Then, by electroplating as a surface treatment, Ni is formed on the outer peripheral side of the tubular portion.
5-15 .mu.m thick particle-dispersed composite Ni containing Ni as a main component and ceramic particles dispersed in a Ni--P--Co matrix.
A system-based electroplating film is formed.
The method for treating the surface of an aluminum alloy valve lifter according to 1. 4. Aluminum having a tubular portion and a partition portion in a direction intersecting the tubular axis direction of the tubular portion, wherein one side of the partition portion is a crown surface portion and the other side is a skirt portion. An alloy valve lifter body is provided, and a chamfered portion is formed by notching the outer peripheral side end of each of the crown surface portion and the skirt portion of the valve lifter body, and a Ni-based electroplating film is formed on the outer peripheral side of the tubular portion by electroplating. Aluminum alloy valve lifter characterized by 5. The valve lifter main body has a chamfered portion formed by cutting out the outer peripheral side end portions of the crown portion and the skirt portion, and the outer peripheral side of the tubular portion is electroplated, so that the tubular portion of the tubular portion is formed. Ni as the main component on the outer peripheral side and N
Thickness of ceramic particles dispersed in i-P base 5 to 5
The aluminum alloy valve lifter according to claim 4, wherein a particle-dispersed composite Ni-based electroplating film having a thickness of 15 μm is formed. 6. The valve lifter main body has a chamfered portion formed by cutting out the outer peripheral side end portions of the crown surface portion and the skirt portion, and the outer peripheral side of the tubular portion is electroplated so that the tubular portion Ni as the main component on the outer peripheral side and N
The aluminum alloy valve lifter according to claim 4, wherein a particle-dispersed composite Ni-based electroplating film having a thickness of 5 to 15 μm in which ceramic particles are dispersed is formed in an i-P-Co based matrix.