JP2757565B2 - Method of strengthening valve spacing of cylinder head made of aluminum alloy casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aluminum alloy casting
By locally re-melting treatment to Rukoto the valve space portion manufacturing cylinder heads relates valve between strengthening treatment method of cast aluminum alloy cylinder head which is utilized to improve the thermal fatigue strength between the valve unit .

[0002]

2. Description of the Related Art Among various castings, aluminum alloy castings are lightweight, have good thermal conductivity and corrosion resistance, and are excellent in castability.

In such a cylinder head which is a cast aluminum alloy part, the thermal fatigue at the intermediate portion between the intake port and the exhaust port, that is, the so-called inter-valve portion is large and the durability is insufficient. To TI
A re-melting process is performed to locally re-melt by a G arc, reduce casting defects and refine the structure, thereby improving the thermal fatigue strength of the inter-valve portion.

[0004]

In such a re-melting process , it is necessary to increase the melting depth and the melting width of the re-melting portion as much as possible in order to improve the efficiency of the re-melting process.
Alternatively, it is desirable to increase the micronized region of the structure to more effectively improve the thermal fatigue strength.

The remelting depth and remelting width are generally affected by the arc current, electrode running speed, stand-off (base material-electrode distance), electrode diameter, and the like. This is most remarkable, and it is most effective to increase the arc current in order to increase the melting depth and the melting width to increase the processing efficiency and the processing effect.

However, when the arc current is increased, the melting depth and the melting width are increased, but bead defects and blowholes are liable to occur. However, there has been a problem for improving the processing efficiency of the remelting process.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been made in consideration of the above-mentioned problems .
Re-melt the cylinder head valve area locally to
When strengthening the inter-valve portion of the nozzle head, a remelted portion with a large melting depth and a wide melting width is obtained without generating defects such as blowholes, and the thermal fatigue characteristics of the inter-valve portion are efficiently improved. It is an object of the present invention to provide a method for strengthening an inter-valve of a cylinder head made of an aluminum alloy casting .

[0008]

Means for Solving the Problems The aluminum alloy according to the present invention
The method of strengthening the gap between valves of a cast aluminum alloy cylinder head is as follows:
A valve between the portion of the aluminum alloy casting manufactured by the cylinder head is treated locally remelting strengthen the valve space portion of the cylinder head
Upon, the valve between unit is obtained by an arrangement of re-melting treatment is provided a thin walled portion, prior to the construction of the valve between the strengthening method of the cast aluminum alloy cylinder head described above object to solve It is characterized by the means.

[0009]

In the method for strengthening the distance between valves of an aluminum alloy cast cylinder head according to the present invention, a thin portion having a predetermined thickness in accordance with remelting conditions is added to the distance between the valves of the cylinder head. The inter-valve portion is re-melted from above the thin portion.

Therefore, the amount of heat generated by the arc in the thickness direction
Since there is almost no diffusion in directions other than the above , and the arc heat is effectively used for remelting the inter-valve portion, the melting depth and melting width of the remelted portion increase without increasing the arc current,
The micronized region of the structure is enlarged without generating defects such as blowholes, and the thermal fatigue strength of the inter-valve portion is efficiently improved.

The thickness of the thin portion formed in the inter-valve portion is such that the above-described effect of expanding the fused portion is maximized and the inter-valve portion is not melted down by the arc. Thickness range is defined as arc current, electrode running speed,
It is necessary to determine experimentally in advance according to remelting processing conditions such as stand-off.

[0012]

FIG. 1 shows an aluminum alloy casting according to the present invention.
FIG. 3 shows the results of an investigation on the relationship between the thickness of a thin portion formed in an inter-valve portion and the melting depth and melting width of a re-melted portion when the method for strengthening a valve between valves of a product cylinder head is performed.

That is, as shown in FIG.
Using a Cu-Si-based aluminum alloy casting 1 having a plate thickness of 23 mm corresponding to AC2A established in 202, the width 8 of which the depth is changed to the back side (lower side in the figure) on the side to be remelted.
mm groove 2 is cut, and T (not shown) is
The re-melting process is performed by the IG torch under the conditions of an arc current of 220 A, an electrode running speed of 100 mm / min, a stand-off of 4 mm, and a tungsten electrode diameter of 3.2 mm. The relationship between the thickness and the thickness T of the thin portion was investigated. FIG. 3 shows a typical example of the penetration shape of the remelted portion 3 when the thickness T is changed from 15 mm to 8 mm.

At this time, the shielding gas is Ar-He.
A mixed gas was used, and the polarity of the power source was DC positive (electrode minus).

As a result, as shown in FIG. 1, when the thickness T of the thin portion exceeds 15 mm, as shown in FIG. 3A, a thin portion is provided for both the melting depth P and the melting width W. Although there is no substantial difference from the case where there is no melt width, the melt width P starts increasing when the melt depth P becomes 15 mm or less, and as shown in FIG.
In the following cases, as shown in FIG. 3 (c) or FIG. 3 (d), it was found that both the melting depth P and the melting width W greatly increased. However, when the thickness T is 8 mm, as shown in FIG. 3E, the remelted portion 3 melts down and the surface of the remelted portion 3 is depressed. It was confirmed that the thickness T of the portion could not be reduced to about 8 mm or less.

Based on this result, the inter-valve portion 1 between the intake port 12 and the exhaust port 13 of the cylinder head 11 shown in FIG.
4, a thin portion 15 having a thickness of 10 mm was formed at a position indicated by a broken line in the figure.

Next, a remelting portion 16 is formed on the inter-valve portion 14 by using a TIG torch (not shown) according to the remelting process conditions as shown in FIG. 5, and a test piece is cut out from the cylinder head 11. The melting depth and the melting width of the melting part 16 were investigated.

As a result, when the thin portion 15 was not formed, the melting depth was 5 to 6 mm and the melting width was 9 to 10 mm. In this case, the melt depth is about 8mm and the melt width is about 12m
m remelted portions were obtained, and it was confirmed that the inter-valve portion 14 could be made into a finely textured region over a wide range and the remelting treatment efficiency could be greatly improved.

[0019]

As described above, according to the present invention, A according to the present invention
According to the method for strengthening the distance between valves of a cylinder head made of aluminium alloy casting, the inter-valve portion of the cylinder head made of an aluminum alloy casting is locally re-melted and the distance between the valves of the cylinder head is reduced.
Upon strengthen the parts, the valve between portions from those where the structure remelting process provided a thin walled portion, the melt depth and the melt width remelting portion without defects such as blow holes are generated This has an excellent effect that the microstructure region of the inter-valve portion is enlarged and the thermal fatigue strength of the inter-valve portion can be efficiently improved.

[Brief description of the drawings]

FIG. 1 is a graph showing an experimental result of a relationship between a thickness of a thin portion and a melting depth and a melting width of a remelted portion in an inter-valve strengthening treatment method for a cylinder head made of an aluminum alloy casting according to the present invention. is there.

FIG. 2 is a view showing an experimental procedure for obtaining the graph shown in FIG.

FIG. 3 is a view showing a shape of a fused portion when the thickness of a thin portion is sequentially changed in the experiment shown in FIG. 1;

4 is an explanatory view showing the shape of a thin-walled portion provided in the valve space portion in one embodiment of the valve between the reinforcement treatment method of cast aluminum alloy cylinder <br/> Daheddo according to the present invention.

FIG. 5 is an explanatory view showing a re-melting processing position in the embodiment shown in FIG. 4;

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Claims (1)

(57) [Claims] 1. A cylinder head made of an aluminum alloy casting.
Of upon the valve space portion is treated locally remelting strengthen the valve space portion of the cylinder head, made of aluminum alloy casting, which comprises re-melting treatment in the valve between portions provided thin walled portion <br /> Cylinder head inter-valve strengthening treatment method.