JPH07145459A - Manufacture of aluminum cylinder head - Google Patents

Abstract

PURPOSE:To machine a drilling part without generating thermal cracking by starting the high density heating energy irradiation from a region in the vicinity of the peripheral part of a valve intermediate part of a cast cylinder head stock. CONSTITUTION:A cylinder head stock 1 is manufactured where a suction hole 2 and an exhaust hole 3 are pierced by casting, and a drilling part 4 for a subsidiary chamber is formed. Then, the irradiation by TIG arc is started from a part (a) close to a valve part 5 of a narrow part between the suction hole 2 and the exhaust hole 3, and the re-melting treatment in A1 direction is executed to work the surface. In addition, after a hole-to-hole part 6 between the valve intermediate part 5, the exhaust hole 3 and the hole working part 4 is re-melted by moving the TIG arc in A2 direction, the TIG arc is moved in A3 direction and the working is completed when the TIG arc reaches the hole working part 4. After the re-melting treatment is completed, the drilling part 4 for the subsidiary chamber is machined, and craters formed in the range where the irradiation is completed are removed, and thermal cracks or the like can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of remelting an aluminum cylinder head for manufacturing a cylinder head of a diesel engine.

[0002]

2. Description of the Related Art In recent years, with the increase in engine output, cracking due to thermal fatigue between intake and exhaust holes in a cylinder head has become a serious problem. As a countermeasure against this, for example, Japanese Patent Application Laid-Open No. 64-218 has been proposed. As shown in the publication, a remelting process for a cylinder head has been developed. In this treatment, the surface layer of the cylinder head is re-melted by locally irradiating the surface of the cylinder head with high-density energy such as TIG arc. Removal of casting defects such as shrinkage cavities and refinement of metal structure. The effect can prevent the occurrence of cracks.

[0003]

By the way, generally, at the end of the remelting process, a so-called crevice is formed on the surface of the cylinder head, and if it is left after machining, it causes a thermal crack. Therefore, it was necessary to remove the creator. As a method of suppressing the generation of such a creter, a sloping mechanism is used to reduce the arc current near the remelting end portion when remelting using a high energy beam. There is a known method of increasing the moving speed of the arc, but this method not only prevents the generation of craters but also cannot secure the depth of the remelting treatment layer. However, there is a problem that sufficient heat crack resistance cannot be obtained.

[0004]

The present invention adopts the following means in order to achieve such an object. That is, in the method for remelting an aluminum cylinder head according to the present invention, a molten metal is poured into a mold to form a cylinder head material, and then a portion of the cylinder head material where thermal fatigue properties are required is heated at high density. Remelting is performed by energy, and irradiation of high-density heating energy is terminated at the hole processing portion for the auxiliary combustion chamber, and then the remelting completion portion is subjected to hole processing.

[0005]

With the above-described means, the crater generated at the remelting end portion when the cylinder head material is remelted with a high energy beam can be removed by making holes for the auxiliary combustion chamber. .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In addition, in this embodiment, since the process for the remelting process will be described, a method widely known in the art can be adopted for the casting process of the cylinder head itself. Is omitted.

The cylinder head material 1 for a diesel engine shown in FIG. 1 is for a four-cylinder diesel engine and is made of JIS AC2B equivalent alloy, and the cylinder head is manufactured through the following processing. In the cylinder head material 1, an intake hole 2 and an exhaust hole 3 are formed in the casting process, and a hole processing portion 4 for the auxiliary combustion chamber is formed.
Further, although not shown, through holes for attachment to the cylinder block are provided, and ribs are formed on the back surface. The inter-valve portion 5 which is a narrowed portion sandwiched between the intake hole 2 and the exhaust hole 3 and the inter-hole portion 6 sandwiched between the exhaust hole 3 and the hole processing portion 4 for the auxiliary combustion chamber are shown in FIG. As shown in, the surface of that portion is processed by the remelting process started from the starting portion a in the vicinity of the peripheral edge portion 5a of the intervalve portion 5.

The remelting treatment is carried out by irradiating the surface-processed portion with a TIG arc which is a high-density heating energy.
Irradiation of the TIG arc is performed using an AC TIG welding machine. In this case, a tungsten electrode rod having a diameter of 6.4 mm was used as an electrode, and argon gas was passed as a shield gas at a rate of 30 liters per minute (30 l / min.).
Adjust the toque current to 420A, the base current to 380A, and the crater current to adjust the torch moving speed to 1.4mm /
As a second, the down-slop time is 20 seconds. The path for moving the TIG arc is to move the intervalve portion 5 toward the hole processing portion 4 for the auxiliary combustion chamber (starting from the starting portion a) (in the direction of arrow A1 in FIG. 2), and then to the interhole portion 6 The portion near the exhaust hole 3 is moved in the direction away from the intake hole 2 (direction of arrow A2 in FIG. 2), and along the vicinity of the peripheral edge portion 6a of the inter-hole portion 6 toward the hole processing portion 4 for the auxiliary combustion chamber. When it moves (in the direction of arrow A3 in FIG. 2) and the TIG arc reaches the hole processing portion 4 for the auxiliary combustion chamber, the processing ends. Under the TIG irradiation conditions shown above, T
The crater 7 formed at the irradiation end portion of the IG arc is
The depth is 2.5 mm.

After the remelting process is completed, the hole forming portion 4 for the auxiliary combustion chamber is processed into the auxiliary combustion chamber in the machining process.
The crater 7 is removed. In this way, when the remelting process is completed at the hole forming portion for the auxiliary combustion chamber, it is possible to remove the creator that deteriorates the mechanical properties in the subsequent machining, and also to remove the crater. The cylinder head can be manufactured at low cost without the need for a special process or the shape deformation of the cylinder head material.

[0010]

According to the present invention, the irradiation of the high-density heating energy started from the portion in the vicinity of the peripheral portion of the constricted portion is finished at the hole processing portion for the auxiliary combustion chamber, so that the crease at the end position. Even if the metal is formed, the auxiliary combustion chamber is formed in the mechanical process, so that thermal cracks and the like due to deterioration of mechanical properties at that portion are prevented. Also,
The cylinder head can be manufactured at low cost because no special process is required to remove the water.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a cylinder head material of the present invention.

FIG. 2 is a schematic plan view showing a remelting process step of a main part of the embodiment.

FIG. 3 is a conceptual diagram showing a process of forming auxiliary combustion chamber holes.

[Explanation of symbols]

 1 Cylinder Head Material 2 Intake Hole 3 Exhaust Hole 4 Hole Processing Portion for Secondary Combustion Chamber 5 Intervalve Area 5a Peripheral Area 6 Interhole Area 7 Crater 8 Secondary Combustion Chamber

Claims (1)

[Claims] 1. A method of injecting a molten metal into a mold to form a cylinder head material, remelting a portion of the cylinder head material required for thermal fatigue characteristics by high density heating energy, and performing the high density heating. A method for manufacturing an aluminum cylinder head, characterized in that the irradiation of energy is terminated at a hole-forming portion for the auxiliary combustion chamber, and then the remelting-finished portion is subjected to hole-forming.