JP3696521B2 - Cylinder head repair method for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylinder head repair method for an internal combustion engine, for example, an internal combustion engine for ships.
[0002]
[Prior art]
The cylinder head of the internal combustion engine is formed with a valve box insertion portion and an exhaust port portion in the lateral direction. When the internal combustion engine is operated for a long period of time, the valve box insertion part and the valve box of the cylinder head are corroded by exhaust, and in the worst case, a hole is formed between the cooling water passage and the cooling water leaks due to corrosion. There was a case of trouble. In addition, the internal combustion engine has been inspected at regular intervals.
[0003]
[Problems to be solved by the invention]
In the periodic inspection of the internal combustion engine, when corrosion and its progress are found in the valve box insertion portion and the valve box of the cylinder head, they are generally replaced, but replacement of the valve box is relatively easy. Replacing the cylinder head has been problematic in that it is time consuming and expensive. Therefore, it is conceivable to repair and use the cylinder head, but no effective repair method has been provided.
[0004]
In view of the above circumstances, an object of the present invention is to provide an effective method for repairing a cylinder head, and it is economical to improve the durability of the cylinder head. In addition, it has been confirmed by periodic inspections that the corrosion of the cylinder head frequently occurs in the valve box insertion portion.
[0005]
[Means to solve the problem]
To achieve the above object, a cylinder head repairing method for an internal combustion engine of the present invention shown in claim 1, covering the upper and lower opening peripheral surface of the valve body insertion portion of the cylinder head in a jig and heat Ma liked Ngute flop, the A shot blasting process is performed on the valve box insertion portion, and a metal spraying process is further performed on the shot blasting surface.
[0006]
According to the first aspect of the present invention, of the valve box insertion portion of the cylinder head, the inner peripheral surface of the upper opening portion where the valve box is hermetically attached via the O-ring and the slide rod inserted through the valve box The shot blasting process and the metal spraying process can be performed on the other part of the valve box insertion portion without performing the shot blasting process and the metal spraying process on the inner peripheral surface of the lower opening close to the opening / closing valve at the lower end. Further, since the shot blasting process is performed as a previous step without performing the metal spraying process directly, the adhesion of the metal spraying is improved.
[0007]
Shirindahe' de complement Osamu method of the present invention shown in claim 2, covers the upper and lower opening peripheral surface of the valve body insertion portion of the cylinder head in a jig and heat Ma liked Ngute flop, the valve body insertion portion, the upper opening The shot blasting process and the metal spraying process are performed on the shot blasting surface from the opening, the lower opening, and the exhaust port.
[0008]
According to one embodiment of the present invention, the shot blasting and metal spraying can be performed effectively. That is, the shot blasting and the metal spraying are performed from three directions, and it is possible to prevent the sit blasting leakage and the metal spraying leakage from the valve box insertion portion. The shot blasting process and the metal spraying process from the three directions are preferably performed by changing the shot grain radiation direction and the metal spraying direction at each position in the three directions.
[0009]
An embodiment shown in claim 3 is characterized in that the sprayed metal contains nickel, chromium, iron and silicon. According to one embodiment of the present invention, it is possible to provide an extremely dense alloy film having excellent heat resistance and corrosion resistance.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a cylinder head, FIG. 2 is an X-ray diffraction diagram of a thermal spray coating, and FIG. 3 is a diagram showing the relationship between the depth from the surface of the thermal spray coating and hardness.
[0011]
In the figure, C is a cylinder head, and 1 is a valve box insertion part. Although not shown, the valve box insertion part 1 has a valve box with a slide rod having an open / close valve at the lower end, with a small gap. Inserted and fixed. In the figure, 2 is an exhaust port, and 3 is a cooling water channel.
[0012]
When the internal combustion engine is operated for a long period of time, it is confirmed by periodic inspection or the like that corrosion occurs in the valve box insertion portion 1 of the cylinder head C indicated by the slanted line S in FIG. Therefore, the present invention is carried out in a timely manner when the corrosion is discovered, and improves the durability of the cylinder head C.
[0013]
In the present invention, first, the jig and Ma liked Ngute flop 6 respectively the inner peripheral surface 4a and 5a have a heat resistance of the upper opening 4 and the lower opening 5 of the valve body insertion portion 1 of the cylinder head C, 7 Covered by.
[0014]
Next, shot blast process is performed on another portion of the valve box insertion portion 1 excluding the portion of the jig and Ma liked Ngute flop 6, 7. In the shot blasting process, steel balls are used as shot grains, and the upper opening 4, the lower opening 5, and the exhaust port 2 of the valve box insertion portion 1 of the cylinder head C are sequentially used. It was carried out by radiating and so on, and also at the positions in the three directions, the shot grain emission direction was changed, and the same was carried out.
[0015]
Next, a metal spraying process is performed on the shot blasting surface. The metal spraying process is performed by mixing a sprayed metal powder containing 17% nickel, 4% chromium, 4% iron, 3.5% silicon, and other metals in a mixed combustion gas flame of propane and oxygen. The powder is uniformly heated and melted by the mixed combustion gas flame of propane and oxygen at about 2760 ° C., accelerated to a gas flame speed of 1350 m / sec, and collided with each part of the valve box insertion portion 1 of the cylinder head C. It was.
[0016]
The metal spraying process is performed sequentially from the three directions of the upper opening 4, the lower opening 5 and the exhaust port 2 of the valve box insertion portion 1 of the cylinder head C, similarly to the shot blasting, Further, even in the positions in the three directions, the gas frame direction was changed and the operations were performed equally. The temperature of the cylinder head C during work was 80 ° C. or lower.
[0017]
The sprayed coating formed by the metal spraying was observed at the center and the end of the valve box insertion portion. As a result, the thickness of the sprayed coating was confirmed by a micrograph and averaged around 0.1 mm, and the components of the sprayed coating were composed mainly of nickel, as shown in the X-ray diffraction diagram of FIG. The subcomponent was chromium and the trace component was iron.
[0018]
Further, it was confirmed that each component was evenly distributed, dense and strong adhesion, and good adhesion. By carrying out the repair method of the present invention, a so-called nickel-chromium steel film is formed, and the heat and corrosion resistance of the valve box insertion portion of the cylinder head is improved.
[0019]
FIG. 3 shows the result of hardness measurement from the surface of the sprayed coating. The hardness of the thermal spray coating was around Hv510 at both the center and end of the valve box insertion part, and the base material of the cylinder head C was around Hv180.
[0020]
【The invention's effect】
According to the cylinder head repairing method for an internal combustion engine of the present invention, the corrosion of the cylinder head and its progress can be prevented, the durability of the cylinder head can be improved, and an economical effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a cylinder head.
FIG. 2 is an X-ray diffraction pattern of a thermal spray coating.
FIG. 3 is a diagram showing the relationship between the depth from the surface of the thermal spray coating and the hardness.
[Explanation of symbols]
1 valve box insertion portion 2 outlet portion 4 upper opening 4a in the (upper opening) of the circumferential surface 5 lower opening 5a (the lower opening) peripheral surface 6 jig and heat Ma liked Ngute flop 7 jig and heat Ma liked Ngute-flops C cylinder head

Claims (3)

Covering the upper and lower opening peripheral surface of the valve body insertion portion of the cylinder head in a jig and heat Ma liked Ngute flop, shot blasting process to said valve body insertion portion, is subjected to metal spraying process to further the shotblasting surfaces A method for repairing a cylinder head of an internal combustion engine. Covering the upper and lower opening peripheral surface of the valve body insertion portion of the cylinder head in a jig and heat Ma liked Ngute flop, the valve body insertion portion, a shot blast process and the from the upper opening, a lower opening and an exhaust opening A method of repairing a cylinder head of an internal combustion engine, characterized by subjecting a shot blasting surface to metal spraying.   The method for repairing a cylinder head of an internal combustion engine according to claim 1 or 2, wherein the sprayed metal component contains nickel, chromium, iron and silicon.

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