JP4673963B2 - Surface treatment method for a follower for an internal combustion engine - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a surface treatment method for a follower for an internal combustion engine having a sliding surface sliding with a rotating cam.
[0002]
[Prior art]
In order to improve the fuel efficiency of the internal combustion engine, it is effective to reduce the frictional resistance in each part of the internal combustion engine. In particular, it is effective to reduce the frictional resistance between the rotating cam that opens and closes the valve and the follower that slides with the rotating cam to an appropriate range.
[0003]
For example, as disclosed in JP-A-6-248915, there is a method of forming a phosphate film on a sliding surface of the follower after barrel polishing is performed on the sliding surface. In this method, the phosphate film avoids direct contact between the rotating cam and the sliding surface of the follower at the initial stage of operation after assembling, so that they are easy to become familiar with. Then, the phosphate film is peeled off after they slide to some extent, and the barrel-polished surface becomes a sliding surface that slides with the rotating cam.
[0004]
[Problems to be solved]
However, the conventional surface treatment method has the following problems.
That is, the one in which the phosphate film is formed after the barrel polishing process cannot always obtain a sufficient frictional resistance reduction effect after the phosphate film is peeled off. The reason for this is considered to be that when the phosphate coating is formed, the surface of the sliding surface that has been barrel-polished finish changes and becomes rough. This is particularly noticeable when a manganese phosphate film is formed. Therefore, it is difficult to reliably reduce the frictional resistance during the sliding.
[0005]
The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a surface treatment method for a follower for an internal combustion engine that has excellent lubricating oil retention performance and can perform excellent sliding with a small frictional resistance. To do.
[0006]
[Means for solving problems]
The invention according to claim 1 is a surface treatment method for a follower for an internal combustion engine having a sliding surface sliding with a rotating cam.
The follower material is carburized hardened steel, nitrided steel or alloy steel that has been heat-treated.
After barreling the sliding surface of the follower,
It contains phosphoric acid ions and molybdenum oxyacid ions and / or tungsten oxyacid ions, and the phosphorus content is 0.05 to 1 mol / liter, and the total content of molybdenum and / or tungsten is 0.1 to 0.1. A Mo · W-containing iron-based phosphate film containing at least one of molybdenum and tungsten is formed on the sliding surface by bringing the sliding surface into contact with an acidic aqueous solution of 50 mmol / liter. It is in the surface treatment method of the follower for internal combustion engines.
[0007]
The most notable point in the present invention is to form a Mo · W-containing iron phosphate coating on the sliding surface after barrel polishing is applied to the sliding surface of the follower.
As the material for the follower, carburized hardened steel, nitrided steel, or alloy steel subjected to heat treatment can be used. For example, materials such as SCM, SCR, SUJ, SKD, and SKH of JIS standards can be used for them.
The Mo / W-containing iron-based phosphate film is an inorganic composite film containing at least one of molybdenum (Mo) and tungsten (W).
[0008]
In order to form the Mo / W-containing iron-based phosphate film, the sliding surface is brought into contact with the acidic aqueous solution as described above. In the acidic aqueous solution at this time, the phosphorus content is 0.05 to 1 mol / liter.
If the phosphorus content is less than 0.05 mol / liter, the film formation reaction may not occur sufficiently.
On the other hand, when the phosphorus content exceeds 1 mol / liter, the etching reaction in the film formation reaction occurs vigorously, and the sliding surface may be roughened.
[0009]
In the acidic aqueous solution, the total content of molybdenum and / or tungsten is 0.1 to 50 mmol / liter.
When the total content of molybdenum and / or tungsten is less than 0.1 mmol / liter, molybdenum and / or tungsten oxide in the formed film may be insufficient and sufficient wear resistance may not be obtained. There is.
On the other hand, when the total content of molybdenum and / or tungsten exceeds 50 mmol / liter, the adhesion of the film to the steel material of the follower may be deteriorated.
[0010]
Next, the effects of the present invention will be described.
In the present invention, first, barrel polishing is applied to the sliding surface of the follower. By this barrel polishing process, a smooth surface having a ten-point average roughness Rz of about 0.4 μm or less can be formed, and dimples, which are minute concave portions, can be formed on the surface.
[0011]
And after performing the said barrel grinding | polishing process, a Mo * W containing iron-type phosphate membrane | film | coat is formed in the said sliding surface. Specifically, it contains phosphoric acid ions and molybdenum oxygenate ions and / or tungsten oxygenate ions, and the phosphorus content is 0.05 to 1 mol / liter, and the total content of molybdenum and / or tungsten. Is formed by bringing the sliding surface into contact with an acidic aqueous solution of 0.1 to 50 mmol / liter.
[0012]
With this Mo / W-containing iron-based phosphate coating, it is possible to avoid the direct contact between the rotating cam and the sliding surface of the follower at the initial stage of operation after assembly, and to make them familiar. The Mo / W-containing iron-based phosphate film is peeled off after being moderately slid, and the surface subjected to barrel polishing becomes the sliding surface.
[0013]
What should be noted here is that there is almost no change in the surface roughness of the sliding surface after barrel polishing after the formation of the Mo · W-containing iron phosphate coating. That is, the Mo / W-containing iron-based phosphate coating is formed on the sliding surface while maintaining the surface roughness before the coating is formed. Therefore, the Mo · W-containing iron-based phosphate film is formed while maintaining the uneven shape of the dimples formed by the barrel polishing process.
[0014]
Therefore, on the sliding surface of the follower, the minute uneven shape having the same dimple is maintained before and after the Mo · W-containing iron-based phosphate film is peeled off. And before and after a Mo * W containing iron-type phosphate film peels, the retention performance of lubricating oil can be improved because lubricating oil accumulates in a dimple.
Therefore, it is possible to perform excellent sliding with a small frictional resistance not only while the Mo · W-containing iron-based phosphate film is present but also after peeling.
[0015]
As described above, according to the present invention, it is possible to provide a surface treatment method for a follower for an internal combustion engine, which has excellent lubricating oil retention performance and can perform excellent sliding with a small frictional resistance.
[0016]
Next, as in the second aspect of the present invention, the Mo · W-containing iron-based phosphate film has an adhesion amount of molybdenum and / or tungsten oxide of 0.3 to 3 g / m ^2. Is preferred.
As a result, the Mo / W-containing iron-based phosphate coating is sufficiently maintained as a coating for a period required for familiarization at the initial stage of operation after assembly, and can then be peeled off at an appropriate time.
[0017]
When the adhesion amount is less than 0.3 g / m ² , the frictional resistance between the sliding surface on which the Mo / W-containing iron-based phosphate coating is formed and the rotating cam in the initial stage of operation after assembly is obtained. It becomes difficult to make it smaller.
On the other hand, when the adhesion amount exceeds 3 g / m ² , the sliding surface should be formed while the surface roughness before the film formation is substantially maintained after the Mo / W-containing iron-based phosphate film is formed. Becomes difficult.
[0018]
Next, as in the invention described in claim 3, the Mo · W-containing iron-based phosphate coating has a total content of the molybdenum and / or tungsten oxide of 1 to 20% by weight. preferable.
As a result, the Mo / W-containing iron-based phosphate film can be peeled off at a more appropriate time after being appropriately slid at the initial stage of operation after assembly.
[0019]
When the total content of the oxides is less than 1% by weight, the frictional resistance between the sliding surface on which the Mo / W-containing iron-based phosphate film is formed and the rotating cam in the initial stage of operation after assembling. It becomes difficult to make small.
On the other hand, when the total content of the above oxides exceeds 20% by weight, the sliding surface is maintained with the surface roughness before the film formation being substantially maintained after the Mo / W-containing iron-based phosphate film is formed. It becomes difficult to form.
[0020]
Next, as in the invention described in claim 4, it is preferable that the acidic aqueous solution has a pH adjusted to 3-4.
Thereby, a Mo * W containing iron-type phosphate membrane | film | coat can be efficiently formed in the said sliding surface.
The pH can be adjusted by adding an appropriate amount of alkali metal hydroxide or aqueous ammonia to the Mo / W-containing iron phosphate.
When the pH is less than 3, the acidity is too strong, and the etching reaction in the film formation reaction may occur vigorously, resulting in roughening of the sliding surface.
On the other hand, when the pH is higher than 4, the acidity is weak and the film formation reaction may not occur sufficiently.
[0021]
Next, as in the invention described in claim 5, the temperature of the acidic aqueous solution is preferably 50 to 80 ° C.
Thereby, a Mo * W containing iron-type phosphate membrane | film | coat can be efficiently formed in the said sliding surface.
In addition, when temperature is lower than 50 degreeC, there exists a possibility that the adhesion amount of the membrane | film | coat formed may be insufficient.
On the other hand, when the temperature is higher than 80 ° C., the etching reaction in the film formation reaction occurs vigorously, and the sliding surface may be roughened.
[0022]
Next, as in the invention described in claim 6, the contact time between the acidic aqueous solution and the sliding surface is preferably 10 to 15 minutes.
Thereby, a Mo * W containing iron-type phosphate membrane | film | coat can be efficiently formed in the said sliding surface.
In addition, when the contact time is shorter than 10 minutes, there is a possibility that the amount of the formed film is insufficient.
On the other hand, when the contact time is longer than 15 minutes, the etching reaction in the film formation reaction occurs vigorously, and the sliding surface may be roughened.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1
A surface treatment method for a follower for an internal combustion engine according to an embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1A, in the surface treatment method in this example, the treatment is performed on the sliding surface 30 of the internal combustion engine follower 3 that slides with the rotary cam 2 in the internal combustion engine.
First, barrel polishing is applied to the sliding surface 30 of the follower 3. Thereafter, the phosphoric acid ions and molybdenum oxyacid ions and / or tungsten oxyacid ions are contained, the phosphorus content is 0.05 to 1 mol / liter, and the total content of molybdenum and / or tungsten is 0.00. The sliding surface 30 is brought into contact with an acidic aqueous solution of 1 to 50 mmol / liter to form a Mo / W-containing iron-based phosphate film on the sliding surface 30.
[0024]
This is described in detail below.
As shown in FIG. 1A, a lift portion 1 that opens and closes an engine valve 41 in response to sliding caused by rotation of a rotary cam 2 in an internal combustion engine includes a follower 3, a valve spring retainer 42, a valve spring 43, and the like. Has been.
The follower 3 is provided with an outer shim 31 on the outer end surface that slides with the rotating cam 2, and the side wall 32 of the follower 3 surrounds the outer periphery of the valve spring 43 and the like.
[0025]
The valve spring 43 biases the engine valve 41 in the closing direction, and presses the follower 3 against the rotating cam 2 via the valve spring retainer 42. The rotary cam 2 opens the engine valve 41 against the urging force of the valve spring 43.
In this example, barrel polishing and formation of a Mo / W-containing iron phosphate film are performed on the sliding surface 30 of the outer shim 31 as surface treatment.
[0026]
As shown in FIG. 1 (b), the surface treatment does not have an outer shim 31 on the sliding surface 30 with the rotating cam 2, and is between the tip of the engine valve 41 and the inner surface of the follower 3. This can also be performed when the inner shim 33 is provided. In this case, the sliding surface 30 that slides with the rotating cam 2 becomes the outer end surface of the follower 3, and the surface treatment is performed directly on the outer end surface.
[0027]
Next, barrel polishing will be described.
First, cold forging, iron plate punching or round bar cutting is performed on the material to form an intermediate product having an outer shape larger than the size of the outer shim 31 to be formed.
As the material of the outer shim 31, carburized and hardened steel, nitrided steel or alloy steel that has been heat-treated can be used. For example, materials such as SCM, SCR, SUJ, SKD, and SKH of JIS standards can be used for them.
[0028]
Next, rough polishing is performed on the surface of the intermediate product which becomes the sliding surface 30 of the outer shim 31, and then heat treatment is performed to improve hardness, toughness and the like.
Next, finish polishing is performed on the entire intermediate product to adjust the outer shape.
Next, centrifugal fluid barrel polishing is performed on the intermediate product in two stages, a rough barrel and a finished barrel. This barrel polishing is performed for a total of about 40 minutes.
[0029]
Specifically, the rough barrel is performed for about 30 minutes using HBS-5 (Chipton) as the abrasive media, AL-203 (Takeyama Technology) as the compound, and Steel Powder (Chipton) as the additive. It was. Further, the finishing barrel was performed for about 10 minutes using PS-5 (made by Chipton) as a medium, TH33L (made by Chipton) as a compound, and steel powder (made by Chipton) as an additive.
[0030]
As described above, by performing barrel polishing, a smooth surface having a ten-point average roughness Rz of about 0.4 μm or less can be formed, and dimples that are minute concave portions are formed on the surface. Can be formed.
[0031]
Next, the formation method of the Mo * W containing iron-type phosphate membrane | film | coat which is an inorganic composite membrane | film | coat is demonstrated.
First, in the alkali degreasing step, the outer shim 31 is immersed in an alkaline type degreasing agent solution having a temperature of 60 to 70 ° C. for about 10 minutes, and oil, dust, etc. are discharged from the sliding surface 30 of the outer shim 31 after barrel polishing. Remove the deposits. Then, clean with water at room temperature for about 1-2 minutes.
Examples of the alkaline type degreasing agent include Fine Cleaner 301 manufactured by Nihon Parka.
[0032]
Next, as a chemical conversion step, the sliding surface 30 of the outer shim 31 is brought into contact with an acidic aqueous solution whose temperature is adjusted to 68 to 72 ° C. and pH is adjusted to 3 to 4 for about 15 minutes. The iron-containing phosphate film is formed. Then, clean with water at room temperature for about 1-2 minutes.
Next, as a rust prevention step, the outer shim 31 is immersed in a solution of a triazole type rust prevention agent or the like at 85 to 95 ° C. for about 3 to 5 minutes to perform a rust prevention treatment of the sliding surface 30. Thereafter, the outer shim 31 is left in a constant temperature bath at 100 to 120 ° C. for about 10 minutes to dry the entire surface.
[0033]
The Mo · W-containing iron phosphate film thus formed had an adhesion amount of molybdenum and tungsten oxide of about 1.5 g / m ² . The total content of the oxides was 1.96% by weight.
Further, as described above, after the outer shim 31 is subjected to the surface treatment, the outer shim 31 is assembled to the follower 3. Then, the follower 3 is assembled to the lift portion 1 for use.
[0034]
Next, the effect in this example is demonstrated.
In this example, the Mo / W-containing iron-based phosphate film avoids direct contact between the rotating cam 2 and the sliding surface 30 of the outer shim 31 at the initial stage of operation after assembly. It can be made easier. In addition, the Mo / W-containing iron-based phosphate film is peeled off after being moderately slid, and the surface subjected to barrel polishing becomes the sliding surface.
[0035]
In addition, after forming the Mo / W-containing iron-based phosphate film, there is almost no change in the surface roughness of the sliding surface 30 after barrel polishing. The sliding surface 30 is formed while maintaining the previous surface roughness. Therefore, the Mo · W-containing iron-based phosphate film is formed while maintaining the uneven shape of the dimples formed by the barrel polishing process.
[0036]
For this reason, on the sliding surface 30 of the outer shim 31, a minute uneven shape having the same dimple is maintained both before and after the Mo · W-containing iron-based phosphate film is peeled off. And before and after a Mo * W containing iron-type phosphate film peels, the retention performance of lubricating oil can be improved because lubricating oil accumulates in a dimple.
Therefore, it is possible to perform excellent sliding with a small frictional resistance not only while the Mo · W-containing iron-based phosphate film is present but also after peeling.
[0037]
Embodiment 2
As described above, after the Mo · W-containing iron-based phosphate coating is peeled off, the outer shim 31 in the first embodiment becomes the sliding surface 30 after the barrel polishing process.
Therefore, in this example, the frictional resistance of the sliding surface 30 of the outer shim 31 (invention product) after barrel polishing is changed to the frictional resistance of the sliding surface 30 of the outer shim 31 (comparative product) after grinding wheel polishing. A test was carried out to confirm how much it was reduced.
[0038]
Specifically, the friction torque between the sliding surface 30 of the outer shim 31 and the rotary cam 2 was measured and compared.
As the material of the outer shim 31, carburizing and tempering material of SCM415 was used for both the inventive product and the comparative product.
[0039]
The friction torque was measured by changing the combined roughness of the sliding surface 30 of the outer shim 31 and the contact surface of the rotating cam 2 from 0.2 to 2 μm. The composite roughness is represented by (Rzs ² + Rzc ² ) ^{1/2 where} Rzs is the ten-point average roughness of the sliding surface 30 of the outer shim 31 and Rzc is the ten-point average roughness of the contact surface of the rotating cam 2. The value is represented by.
[0040]
The result of the measurement is shown in FIG.
As can be seen from the figure, the invention product as a whole has a smaller friction torque than the comparative product, regardless of the difference in the synthetic roughness. This is because even if the synthetic roughness is the same, the invention that has been barrel-polished has dimples that are minute recesses on the sliding surface on one side, and lubricating oil accumulates on these dimples. It is thought that the friction torque is reduced.
[0041]
Embodiment 3
In this example, a Mo / W-containing iron-based phosphate coating is formed on the sliding surface 30 of the outer shim 31 in the first embodiment (invention product), and a manganese-based phosphate coating is formed. For the case (conventional product), the surface roughness of the sliding surface 30 was measured and compared.
[0042]
As shown in FIG. 3A, the ten-point average roughness Rz of the sliding surface 30 of the outer shim 31 after the barrel polishing of the invention product was 0.28 μm.
And as shown in FIG.3 (b), the 10-point average roughness Rz of the sliding face 30 of the outer shim 31 after forming a Mo * W containing iron-type phosphate film was 0.28 micrometer.
Further, as shown in FIG. 3C, when the film of the outer shim 31 after film formation was peeled off and the ten-point average roughness Rz of the underlayer was measured, there was almost no change from before film formation. .29 μm.
[0043]
On the other hand, as shown in FIG. 4A, the ten-point average roughness Rz of the sliding surface 30 of the outer shim 31 after the grinding wheel polishing finish in the conventional product was 0.20 μm.
And as shown in FIG.4 (b), 10-point average roughness Rz of the sliding surface 30 of the outer shim 31 after forming a manganese-type phosphate membrane | film | coat became coarse, and was 1.40 micrometers.
Further, as shown in FIG. 4C, the above-mentioned film of the outer shim 31 after the film formation was peeled off, and the ten-point average roughness Rz of the underlayer was measured. As a result, the film became further rough and was 1.65 μm. .
Such a result of the conventional product was the same even when the manganese phosphate coating was formed on the sliding surface 30 subjected to barrel polishing instead of the grinding wheel polishing.
[0044]
As described above, the surface roughness of the sliding surface 30 of the invention product hardly changes even after the Mo / W-containing iron-based phosphate film is formed. Therefore, even after the Mo / W-containing iron-based phosphate film is peeled off by sliding between the rotating cam 2 and the sliding surface 30 of the outer shim 31, excellent sliding can be performed with a small frictional resistance. .
[0045]
On the other hand, in the conventional product, it is understood that the surface roughness of the sliding surface 30 on which the grinding wheel polishing finish is performed becomes extremely rough when the manganese-based phosphate film is formed. That is, the conventional film forming method cannot maintain a smooth surface after polishing.
[0046]
In addition, when the film formation process of an invention is represented as an image diagram, it is as shown in FIGS. That is, as shown in FIG. 5 (a), the surface roughness of the sliding surface 30 of the outer shim 31 before film formation hardly changes even after the film formation as shown in FIG. 5 (b). Represents.
[0047]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a surface treatment method for a follower for an internal combustion engine that is excellent in lubricating oil retention performance and can perform excellent sliding with a small frictional resistance.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams showing a rotating cam and a lift portion in an internal combustion engine in Embodiment 1, wherein (a) an outer shim is provided on the follower, and (b) an outer shim is not provided on the follower. Figure.
FIG. 2 is a graph showing the relationship between synthetic roughness and friction torque in Example 2;
FIG. 3 is a diagram showing the surface roughness of the sliding surface of the outer shim in the invention product in Embodiment 3, and after (a) barrel polishing, (b) Mo / W-containing iron-based phosphoric acid Explanatory drawing which shows the surface roughness of the sliding surface after forming the salt film and (c) peeling the film after film formation.
FIG. 4 is a diagram showing the surface roughness of a sliding surface of an outer shim in a conventional product in Embodiment 3, wherein (a) grinding stone polishing finish is performed, and (b) a manganese phosphate film is formed. (C) Explanatory drawing which shows the surface roughness of the sliding surface after peeling the film | membrane after film formation.
FIGS. 5A and 5B are diagrams showing a sliding surface of an outer shim in Embodiment 3, and are explanatory views showing (a) before film formation and (b) after film formation. FIGS.
[Explanation of symbols]
1. . . Lift section,
2. . . Rotating cam,
3. . . Followers,
30. . . Sliding surface,
31. . . Outer shim,

Claims (6)

In a surface treatment method for a follower for an internal combustion engine having a sliding surface sliding with a rotating cam,
The follower material is carburized hardened steel, nitrided steel or alloy steel that has been heat-treated.
After barreling the sliding surface of the follower,
It contains phosphate ions and molybdenum oxyacid ions and / or tungsten oxyacid ions, and the phosphorus content is 0.05 to 1 mol / liter, and the total content of molybdenum and / or tungsten is 0.1 to 0.1. A Mo / W-containing iron-based phosphate film containing at least one of molybdenum and tungsten is formed on the sliding surface by bringing the sliding surface into contact with an acidic aqueous solution of 50 mmol / liter. Surface treatment method for a follower for an internal combustion engine. ^{2. The} follower for an internal combustion engine according to claim 1, wherein the Mo · W-containing iron-based phosphate coating has an adhesion amount of molybdenum and / or tungsten oxide of 0.3 to 3 g / m ² . Surface treatment method.   3. The surface of a follower for an internal combustion engine according to claim 2, wherein the Mo / W-containing iron-based phosphate coating has a total content of the molybdenum and / or tungsten oxide of 1 to 20% by weight. Processing method.   The surface treatment method for a follower for an internal combustion engine according to any one of claims 1 to 3, wherein the acidic aqueous solution has a pH adjusted to 3 to 4.   The surface treatment method for a follower for an internal combustion engine according to any one of claims 1 to 4, wherein the temperature of the acidic aqueous solution is 50 to 80 ° C.   6. The surface treatment method for a follower for an internal combustion engine according to claim 1, wherein the contact time between the acidic aqueous solution and the sliding surface is 10 to 15 minutes.

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