JP2925945B2 - Method of manufacturing valve for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a valve for an internal combustion engine, and more particularly to a method for improving the hardness of an umbrella face of a valve.

[0002]

2. Description of the Related Art An umbrella face of an intake / exhaust valve for an internal combustion engine is required to have wear resistance and high temperature corrosion resistance in order to open and close a combustion chamber by contacting a valve seat. In response to the umbrella face, stellite 6,1
An overlay of a Co-based material such as 2,20 and an overlay of a Ni-based material such as Colmonoy # 6 were applied. However, in recent years, in internal combustion engines, high temperature combustion has been promoted,
There is a problem that the durability is not sufficiently satisfied with such a bank.

Therefore, Japanese Patent Publication No. 60-34607 and Japanese Patent Publication No. 64-8699 disclose techniques for improving the wear resistance and high temperature corrosion resistance of a valve of an internal combustion engine. The technique disclosed in the former publication uses a precipitation hardening type Ni-based alloy having a specific composition ratio as a material, and the final hot working end temperature is 700 to 900 ° C. and the working rate is 25 to 75%. Hot working, followed by 650
The gist of the invention is that heat treatment is performed at a temperature condition of up to 825 ° C. The gist is to form by forging of 20% or more and to perform age hardening treatment.

However, the techniques disclosed in these publications have the following technical problems.

[0005]

That is, according to the technique disclosed in the above publication, although the wear resistance and the high-temperature corrosion resistance are improved, the average hardness is about 420 in Vickers hardness. With this degree of hardness, there is a problem that the hardness is insufficient, the combustion residue penetrates into the umbrella face, indentations are generated relatively early, and the blow-through resistance is deteriorated. Satisfactory performance was not able to be demonstrated in the diesel engine which does. Further, even when the above-described technique is applied to an intake valve, improvement in wear resistance is not satisfactory due to insufficient hardness.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a valve for an internal combustion engine capable of sufficiently improving blow-through resistance and abrasion resistance. It is to provide a manufacturing method.

[0007]

In order to achieve the above object, the present invention uses a precipitation hardening type Ni-based alloy as a material, and uses the material in an internal combustion engine within a temperature range of 20 to 500 ° C.
From the inner circumference of the umbrella face that comes in contact with the Seki valve seat
Forging or roll processing in which slip deformation occurs toward the outer peripheral side is performed. Here, the reason for defining the temperature condition in the range of 20 to 500 ° C. when performing forging or roll working in which umbrella face undergoes slip deformation is as follows.
If the temperature is lower than ℃ (room temperature), forging or roll processing becomes difficult. If the temperature is higher than 500 ° C., the forging or roll processing becomes annealed and the hardness of the umbrella face cannot be increased. Therefore, it is necessary to perform forging or roll working within the above temperature range.

At this time, the working ratio of forging or roll working can be set to 20 to 80% on the outer peripheral side of the umbrella face and 10 to 30% on the inner peripheral side of the umbrella face. As for the processing rate of forging or roll processing in which slip deformation occurs, the hardness increases as the rate is increased, but if the processing rate is less than 10%, the effect of increasing the hardness is not sufficiently obtained. When the rate exceeds 80%,
Since the increase in hardness increases rapidly and processing becomes difficult, and the toughness of the material deteriorates remarkably, the processing rate becomes 1
It is desirable to set within the range of 0 to 80%.

In this case, when the working ratio of the outer peripheral side of the umbrella portion face is made larger than that of the inner peripheral side, the increase in hardness on the outer peripheral side becomes large, and the occurrence of indentation is reduced. It is desirable that the upper limit of the processing rate on the inner peripheral side of the umbrella part face does not exceed 30%. The reason is that when the working ratio is increased, although the hardness increases as described above, the toughness of the material is reduced, which leads to a valve breakage accident. Therefore, it is desirable to suppress the working ratio to 30% or less.

[0010] In the manufacturing method of the present invention, after the forging or the roll processing, the temperature is 12 to 400 ° C. and 700 ° C.
A heat treatment of 0 to 300 minutes can be performed. By performing such a heat treatment, the hardness of the umbrella portion face is increased, and the processing strain is made uniform. In this case, 400 ° C
If the temperature is lower than this, the effect of increasing the hardness cannot be sufficiently obtained. If the temperature exceeds 700 ° C., the steel is in an annealed state, and the effect of increasing the hardness becomes similarly insufficient.

Further, in the manufacturing method of the present invention, the material may contain an age hardening element such as Ti, Al, or Nb. If such an age hardening element is included in the material, when the valve is used in an internal combustion engine, 700 ° C.
When the temperature reaches a certain level, the aging characteristics can be utilized to increase the hardness during operation.

[0012]

According to the method of manufacturing a valve for an internal combustion engine having the above structure, a precipitation hardening type Ni-based alloy is used as a material, and the material is applied to the valve of the internal combustion engine within a temperature range of 20 to 500 ° C.
From the inner circumference to the outer circumference of the umbrella face in contact with the sheet
Since forging or roll processing that causes slip deformation occurs, the hardness of the umbrella face can be improved. Ma
In addition, sliding changes from the inner circumference to the outer circumference of the umbrella face
When it is shaped, the range of improvement in hardness is
First, it can be made shallower on the inner peripheral side.

According to the second aspect of the invention, the working ratio of forging or roll working is set to 20 to 80% on the outer peripheral side of the umbrella face and 10% on the inner peripheral side of the umbrella face. Since it is set to 30%, the outer peripheral side of the umbrella portion face can have higher hardness than the inner peripheral side. Further, according to the configuration of claim 3, after forging or roll working, the temperature is set to 120 to 300 in a temperature range of 400 to 700 ° C.
Since the heat treatment is performed for a minute, the hardness of the umbrella face can be further improved. Furthermore, according to the configuration of the fourth aspect, since the material contains an age hardening element such as Ti, Al, or Nb, the hardness of the head portion face can be further improved during operation.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 9 show one embodiment of a method for manufacturing a valve for an internal combustion engine according to the present invention. The manufacturing method shown in FIG. 1 is a method of manufacturing a valve 3 in which a valve stem 1 and an umbrella portion 2 are integrally formed on the distal end side of the valve stem 1 as shown by a solid line in FIG. On the back side of the umbrella part 2, a face part 5 is formed which is continuous with the neck part 4 and abuts on a valve seat of the internal combustion engine.

In the manufacturing method of the present invention, first, a raw material is processed into a shape shown by a dotted line in FIG. The material used at this time is a precipitation hardening type Ni-based alloy, for example,
NCF80A, NCF751, etc. are used. The material formed in a predetermined shape is cut into a shape shown by a dashed line in FIG. 1, and then set in a mold and subjected to forging.

The shape shown by the two-dot chain line in FIG. 1 is a state after the forging, and in this forging, the slip deformation is particularly generated in a portion corresponding to the face portion 5 of the valve 3. It is done. That is, forging is performed so that the portion A indicated by hatching in FIG. 1 moves to the portion B indicated by dots in FIG. Forging in this case, for example, conducted at room temperature (20 ° C.), working rate of forging, for example, 20-80% in the portion corresponding to the outer peripheral side 5a of Fe y scan unit 5, Fe y scan unit 5 is set to 10 to 30% at a portion corresponding to the inner peripheral side 5b.

The working ratio in this case, the height of the portion corresponding to Fe y <br/> scan unit 5 before forging and h _0, the face portion 5
The height h ₁ after processing the portion corresponding to the outer peripheral side 5a of the inner circumferential side 5b corresponding height after machining portion of the full <br/> E Lee scan unit 5 When h _2, ( _{h 0 -h 1) / h 0} × 100% and _{(h 0 -h 2) / h} 0 × can be determined as 100%.

The forged valve intermediate product is thereafter subjected to a cutting process on an outer peripheral portion to be processed into a final product valve 3 shown by a solid line in FIG. 2 and 3, using NCF80A as a material, about 37% of working ratio of a portion corresponding to the outer peripheral side 5a of Fe y scan unit 5, corresponding inner peripheral side 5b of Fe y <br/> scan unit 5 It is an enlarged photograph of a metal structure of a finished valve product forged so as to generate slip deformation at room temperature by setting the processing of a portion to be processed to about 12%.

FIG. 2 is an enlarged photograph of a macrostructure of a longitudinal section of a forged valve finished product, in which a line of slip deformation is recognized in a portion serving as a face portion of the valve. FIG.
FIG. 3A is an enlarged photograph of the microstructure of a plurality of portions in FIG. 2, and FIG. 3A is a photograph of a portion close to the slip line indicated by reference numeral 1 in FIG. FIG. 3B is a photograph of a portion corresponding to the surface side of the portion, and FIG.
(C).

As is clear from the photographs of FIG. 3, dense and organized bonding of metal crystals is observed in portions not related to the slip deformation, and in the portions close to the slip line, the metal crystals are disturbed. It is recognized that the metal crystal is deformed on the surface side. The present inventors presume that such a change in the metal crystal contributes to improving the hardness.

The inventors of the present invention have conducted a hardness test on a finished valve product that has been prototyped to take the above-mentioned metallographic photograph. FIG. 5 shows the results of the hardness test. In this hardness test, a hardness test was also performed on a finished valve product that was processed using the same material by a method that did not cause slip deformation. FIG. 6 shows the results of the hardness test.

In this hardness test, as shown in FIG. 5, measurement points are set at the center of a portion corresponding to the face portion of the completed valve and 1.5 mm and 3 mm before and after the center, respectively. The surface and depth are 0.
The hardness was measured at points of 5, 1, 2, 3, 4, and 5 mm using a Vickers hardness tester. Looking at the results of the hardness test shown in FIG. 5, in the manufacturing method of the present invention, the Vickers hardness is 50%.
Very many measurement points of 0 or more are recognized, but the maximum value does not reach 400 in the case of FIG. In FIG. 5, the hardness pattern is higher at a portion corresponding to the outer peripheral side of the face portion than at a portion corresponding to the inner peripheral side.
FIG. 6 does not show such a tendency.

Further, in FIG. 5, a portion having a Vickers hardness of 500 or more from the surface to a deep portion is recognized in a portion corresponding to the outer peripheral side of the face portion, and a Vickers hardness of 500 or more is recognized in a portion corresponding to the inner peripheral side. Is in a relatively shallow area. As is clear from the hardness test, it was confirmed that when forging was performed to cause slip deformation as in the manufacturing method of the present invention, the hardness was significantly improved.

FIGS. 7 to 9 show that the above-mentioned valve intermediate product (working rate is not the same) is subjected to a predetermined heat treatment (aging treatment).
The results of measuring the change in hardness before and after that are shown. In this test, NCF80A was used as a material, and NMC490 (40Ni-25Cr-T), a material developed by the present applicant, was used.
i-Al-Nb). The measurement points of the hardness, the three points P _1, P _2, P ₃ shown in FIG. 9, the Vickers hardness to a point a distance of 6mm from the surface at each of these measuring points P _1, P _2, P ₃ Was measured.

The aging treatment is performed at a temperature of 500 ° C., 600 ° C.,
The temperature was set to 700 ° C., and the treatment was performed under these temperature conditions for 5 hours. In FIGS. 7 and 8, white circles, □, and □ indicate Vickers hardness before the aging treatment, and black circles, ▲, and で indicate Vickers hardness after the aging treatment. As is clear from the test results of FIGS. 7 and 8, it is recognized that the aging treatment increases the Vickers hardness in each part, and the hardness increase is most increased when the NCF80A is at 500 ° C.
And NMC490 was 600 ° C.

FIG. 10 shows the production of a valve of the present invention in which a slip deformation has occurred and a valve using a bank material Colmonoy # 6, which is generally evaluated as having the highest blow-through property, respectively. It shows the test results when attempting a market test. In this test, a plurality of valves having different diameters were manufactured, each of which was mounted on an actually used marine internal combustion engine, and an operation period until blow-by occurred was measured.

In FIG. 10, a white circle represents a valve obtained by the production method of the present invention, and a black circle represents Colm.
This is a valve with onoy♯6. As is evident from the test results, the valve obtained by the production method according to the present invention has no blow-through at all diameters even after about 6000 hours has passed, but Colmonoy # 6 was embossed. In the valve, blow-through occurs before and after the lapse of 2000 hours, which indicates that the blow-through resistance of the valve obtained by the manufacturing method of the present invention is greatly improved.

In the above-described embodiment, forging using a mold has been exemplified as a processing means for causing slip deformation. However, the present invention is not limited to this.
For example, even when the slip deformation is caused by the roll processing, the same operation and effect as the above embodiment can be obtained.

[0029]

As described above in detail in the embodiments,
According to the method for manufacturing a valve for an internal combustion engine according to the present invention,
Since the hardness of the umbrella portion Fe y scan is significantly improved, not easily attached indentation very by combustion residues, and at the same time resistance to blow resistance is improved, also greatly improved wear resistance. In addition, the present invention
Then, slide from the inner circumference to the outer circumference of the umbrella face.
Because it is deformed, the range of improvement in hardness is deep on the outer peripheral side,
In addition, the inner peripheral side can be made shallower, greatly extending valve life.
Can be extended.

According to the second aspect of the present invention, the umbrella section
By varying the processing rate the outer peripheral side and inner peripheral side of Lee scan,
While the hardness balance can be set arbitrarily,
When the processing rate on the outer peripheral side is higher than that on the inner peripheral side, the hardness increases on the outer peripheral side, making it very difficult for indentations to occur and keeping the toughness on the inner peripheral side high. it can.

According to the third aspect of the present invention, the hardness is improved by forging or roll working to cause slip deformation, and the hardness is further improved by aging treatment, so that abrasion resistance and blow-through resistance are improved. Can be further remarkably improved. Still further, according to the configuration of claim 4,
Since the hardness can be further increased during operation, the life of the valve can be extended.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a working process of an embodiment of a method for manufacturing a valve for an internal combustion engine according to the present invention.

FIG. 2 is an enlarged photograph instead of a drawing of a metal structure in a state in which slip deformation has been generated by the manufacturing method of the present invention.

FIG. 3 is a drawing-substituted enlarged photograph of a metal structure in a main part of FIG. 2;

FIG. 4 is an explanatory diagram of a photographing location of the enlarged substitute photograph of FIG. 3;

FIG. 5 is an explanatory diagram showing a measurement result of a hardness test in a state where slip deformation is generated by the manufacturing method of the present invention.

FIG. 6 is an explanatory diagram showing a measurement result of a hardness test in a state where processing is performed without causing slip deformation.

FIG. 7 is an explanatory view showing measurement results of a hardness test before and after heat treatment when heat treatment is performed after a slip deformation is generated by the manufacturing method of the present invention.

FIG. 8 is an explanatory view showing measurement results of a hardness test before and after heat treatment when a heat treatment is performed after a slip deformation is generated with a material different from that shown in FIG. 6 in the manufacturing method of the present invention. is there.

FIG. 9 is an explanatory diagram of measurement points of the hardness test shown in FIGS.

FIG. 10 is a glove showing a test result of blow-through resistance when a valve obtained by the manufacturing method of the present invention and a valve obtained by a conventional manufacturing method are subjected to a market test.

[Explanation of symbols]

1 stem 2 valve head 3 Valve 5 Fe y scan unit 5a Fe y scan outer circumferential side 5b Fe y scan inner peripheral side

Claims (4)

(57) [Claims] An internal combustion engine using a precipitation hardening type Ni-based alloy as a material within a temperature range of 20 to 500 ° C.
From the inner circumference of the umbrella face that comes in contact with the Seki valve seat
A method for manufacturing a valve for an internal combustion engine, comprising performing forging or roll processing in which slip deformation occurs toward an outer peripheral side . 2. The processing rate of the forging or roll processing,
2. The method for manufacturing a valve for an internal combustion engine according to claim 1, wherein the outer peripheral side of the umbrella face is set to 20 to 80%, and the inner peripheral side of the umbrella face is set to 10 to 30%. . 3. After the forging or rolling, 40
The method for manufacturing a valve for an internal combustion engine according to claim 1 or 2, wherein a heat treatment is performed in a temperature range of 0 to 700 ° C for 120 to 300 minutes. 4. The method according to claim 1, wherein the material contains an age hardening element such as Ti, Al, or Nb.
A method for manufacturing a valve for an internal combustion engine according to any one of the preceding claims.