JPH0120305B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Light alloy parts for internal combustion engines are generally manufactured by aluminum die casting. One such example is the intake system surge tank, and it is important to properly attach the lid plate to the tank body. The present invention relates to such a tank-shaped part for an internal combustion engine, and includes a die-cast tank body and a cover plate made of expanded aluminum material.
It is characterized by being joined by means suitable for the characteristics of MIG welding.

When the tank body is die-cast aluminum alloy, the molten metal flows into the mold cavity at high speed and high pressure, so gas generated from air and mold release agent enters the molten metal during the transitional period of flow. This results in the formation of fine cavities. Although some of the gases encapsulated in metals are occasionally visible to the naked eye, most of them are scattered in such a way that they are difficult to discern even with a microscope. This gas is then confined under high pressure.

When MIG welding is performed on a tank body in a gaseous state as described above, when the die-casting base material is melted, fine air bubbles are aggregated and then rapidly released, resulting in blowholes due to bubble bursting at the weld bead. , breaks may occur in the bead, which should run smoothly. If there is such a defect in the surge tank or the like of an internal combustion engine, intake air leakage will occur, which will impede the desired engine performance.

Furthermore, such bursting of bubbles disturbs the flow of the shielding gas, making the original shielding function insufficient and causing irregularities in the shape of the arc itself, making it impossible to obtain uniform and high-quality beats. A problem arises.

Hereinafter, the present invention will be explained in detail with reference to the embodiments of the drawings, which take a surge tank as an example. of
It was MIG welded and placed in the position shown in Figure 3.
Welding is performed by bringing the MIG torch 4 close, and the second
A weld bead 5 as shown in the figure is formed. When the cover plate 3 is matched with the tank body 2, the positional relationship between the two must be set in a predetermined relationship as described later, so a stepped portion 6 is provided as shown in FIG. 3. FIG. 4 shows a case where a support protrusion 7 is provided on the inner surface of the tank body 2 instead of the stepped portion 6. Note that an inlet pipe 8 is integrally molded into the tank body 2.
Further, an outlet hole 9 is formed in the cover plate 3, and intake pipes 10 and 11 are connected to each of the outlet holes 9.

The dimensions of surge tank 1 are 210mm wide and 180mm tall.
The depth is 55 mm, the tank body 2 has a wall thickness of 4.5 mm, and the cover plate 3 has a wall thickness of 4 mm. Moreover, FIG. 5 is an enlarged cross-sectional view of the welding local area, and the dimensions of each part are a=
4.5mm, b=4mm, c=3mm, d=1mm, e=8
mm, f=7 mm. The most important point in the welded joint structure shown in the figure is the provision of dimension g. This means that when the cover plate 3 is aligned with the tank body 2 as shown in Figures 3 to 5, the surface 1 of the cover plate 3
2 is raised above the surface 14 of the thick portion 13,
That is, the positional relationship between the two is set so that the position is close to the MIG torch 4 side. In the case of FIG. 5, the height difference g is 1 mm. Note that the surface 14 means the opening surface of the tank body.

In Figure 5, e=8mm. The reason why the portion indicated by reference numeral 13 is formed as a thick portion by setting f=7 mm is to set the thermal mass of this portion to be large and to reduce the amount of melting on the die-cast member side.

The MIG torch 4 in FIG. 5 is in a position separated from the item, but the welding wire 15 is
As is clear from the weld bead 5 in FIG.
The trajectory is set to move above. This locus position changes slightly depending on various conditions, but here it is set to h=1 mm. The installation posture of the welding local area is set in a horizontal state in consideration of the flow phenomenon of molten metal.

The conditions for MIG welding, the chemical composition of the tank body and lid plate, etc. are extremely common, but are listed below for reference.

Melting conditions: Arc current 120A Arc voltage 20V Arc pulse 60 cycles Wire Diameter 1.2mm Material JISZ3232A4043 Shielding gas Ar, Ar+He Ar+O ₂ , etc. Shielding gas flow rate 20/min Torch movement speed (average) 60cm/min Tank body material: JISH5302ADC12 with some aluminum casting scraps Expanded aluminum material for cover plate: JASH4000A1050P The state of change in localized welding parts is explained according to Figures 6 to 8. In the initial melting stage as shown in Figure 6, ,
The molten pool is a relatively narrow area, and the amount of metal melted is small. What is particularly noteworthy is that since the movement locus of the welding wire 15 is positioned as shown in FIG.
At this stage, the molten pool 16 remains within the range of the cover plate 3. As the melting progresses further and the molten pool 16 becomes wider and deeper, the amount of molten metal also reaches the seventh level.
It increases as shown in the figure. In this case, the surface 12 of the lid plate
Since the water is placed closer to the MIG torch side than the surface 14 of the thick portion, it flows down to the surface 14 side located at a lower position and covers a part of the surface 14.
In this state, since the amount of heat directed toward the thick portion 13 is small, the surface 14 has not yet reached the level of melting. As such welding action further progresses, the surface 14 side is also melted as shown in FIG. 8, metal is also supplied from the welding wire, and the material gradually solidifies into a cross-sectional shape as shown in the same figure.

According to the present invention, the joint structure is such that the surface of the lid plate protrudes outward from the opening surface of the tank body, and the MIG torch extends inward from the outer periphery of the lid plate toward the outer periphery. Since it is designed to move along the same line, it has the following effects. In other words, by appropriately setting the dimension h as shown in Figure 5, melting is preferentially started from the lid plate located one step higher, and the heat transfer to the opening surface side of the tank body and the amount of melting there are minimized. As a result, bubble bursting on the die-casting material side can be kept as small as possible and on a small scale. Furthermore, the flowing metal from the end of the lid plate is
Since it is a molten metal that has been sufficiently heated and has good fluidity, and does not contain gas, even if air bubbles from the die-casting material burst at the bead, that part will be immediately compensated for. This phenomenon occurs, improving the welded appearance of the surge tank and providing a highly airtight part. Further, due to the above-described effects, there is no disturbance in the shielding gas flow, and a highly stable arc can be obtained.

The present invention rationally solves the original problem through the above-described structural action and provides an excellent tank-shaped component.

[Brief explanation of drawings]

Figure 1 is a side view of the surge tank, Figure 2 is a plan view of the same, Figures 3 and 4 are sectional views taken along line 3-3 in Figure 2, Figure 5 is an enlarged sectional view of the welding area, and Figure 6. ~ Figure 8 is a sectional view showing the melting process of a welded local area. 2...tank body, 3...cover plate, 12...cover plate surface, 14...opening surface, 4...MIG torch.

Claims (1)

[Claims] 1. In a method for manufacturing a tank-like part such as a surge tank, which is formed by joining a die-cast aluminum tank body and a cover plate made of expanded aluminum material by MIG welding, the tank body and the cover plate are connected to the The surface of the lid plate is arranged so as to protrude outward from the opening surface of the tank body, and the MIG torch is placed a predetermined amount inward from the outer periphery of the lid plate and along the outer periphery. A method for manufacturing a tank-shaped part such as a surge tank, characterized in that it is movable.