JP3191362B2 - Local reinforcement method of aluminum casting parts - 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 locally strengthening an aluminum casting part by welding.

In recent years, with the high output of the engine, an increase in the mechanical load as well as the thermal load due to the temperature rise on the aluminum cylinder head has become a problem. That is, as shown in FIG. 12, the increase in the load causes the lower surface 2 of the cylinder head 1, particularly between the intake port 3 and the exhaust port 4, which are relatively thinner than other portions (interval valve portion), and In the part 6 between the fuel injection nozzle hole (or the pre-combustion chamber hole) 5 and the fuel injection nozzle hole, a heat crack occurs. Further, as shown in FIG. 13, the periphery of the combustion chamber 8 (shown by oblique lines in the figure) where the load is large also becomes the part to be strengthened in the piston 7.

[0003] As a countermeasure for this, there has been the following technique in a local strengthening method conventionally employed. Alloying: Add an appropriate amount of heat-resistant components (Cr, Mo, Cu, Ni, etc.) to improve heat-resistant strength. Casting: A steel material or a heat-resistant metal material is cast at the site where heat cracks occur. Improvement treatment: Add appropriate amount of strontium or titanium to refine the crystal grains
At the same time as increasing the tensile strength, the elongation characteristics are improved, and the heat resistance and sharpness are improved. Hard alumite treatment; heat resistance is improved by forming a hard alumite treatment coating around 100 μm. Remelting process; laser, electron beam, T
By melting and rapidly solidifying the aluminum base material with a high-density energy source such as IG, the crystal grains are refined and the heat resistance is increased. However, these conventional techniques have the following problems.

[0004] Alloying: In addition to the increase in cost, addition of an alloy deteriorates castability, and casting defects such as "shrinkage cavities" cause deterioration in productivity and yield. In addition, due to the deterioration of castability, the amount of microshrinkage that greatly affects the heat resistance increases, and the heat resistance rather deteriorates due to alloying. Casting: In order to ensure castability, aluminizing treatment is required as a pre-treatment of cast-in steel materials, oxidation prevention, thorough control of casting temperature, and non-destructive inspection after casting are required. Significant increase in man-hours. Improved processing: Simple method, but less effective. Hard alumite treatment: The heat resistance improvement effect is greater than that described above, but in order to treat only the part where cracks are generated, alumite removal treatment by masking other parts is required, which is a time-consuming and expensive treatment.
Remelting treatment: Although the treatment method is simple and has a large effect of improving heat resistance, it is insufficient for the currently required goal of improving heat resistance.

[0005]

As a solution to the problems of the prior art, the present applicant has previously devised and applied for a method and apparatus for modifying the surface of metallic parts. No. 2-139677). This proposal is to add a heat-resistant element by overlay welding such as MIG after melting the portion to be reformed by irradiation with high-density energy such as a TIG arc. And reforming without gas defects or the like is realized. In particular, in the step of adding the heat-resistant element, the homogenization of the alloyed layer and the like are achieved by using a welding wire formed by encapsulating different kinds of particles and filling the powder into an appropriate sheath material.

In order to locally strengthen aluminum parts by applying this modification method, a Cu sheath is filled with capsule particles made of Cu core particles and Al-coated particles, and the weight ratio is made 50:50. When build-up welding is performed using a welding wire, an intermetallic compound of Cu and Al precipitates in a lump due to subtle variations in welding conditions, and a crack may occur in the portion. When observing the position where the cracks are generated in detail by a build-up welding test on the bead-on plate and the groove, the cracks in the longitudinal direction of welding (welding direction) are dominant.
Further, in the case of welding of the combination of TIG + MIG, the depth of the sharpness does not enter the molten layer of the first TIG, but stops at the upper part of the alloy.

Accordingly, the present invention has been devised to provide a method for locally strengthening aluminum cast parts for improving the quality by taking measures against cracks in the alloy-finished part.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an aluminum casting part.
The site of enhanced receiver of goods, anti-containing heat-resistant components such as Cu
After the thermal aluminum alloy layer is formed by welding overlay, a pure aluminum welding layer is formed by welding overlay at the center of the surface of the heat resistant aluminum alloy layer .

[0009]

[Action] by the above method, pure Aluminum soluble adhesive layer is formed in the surface <br/> central portion of the heat resistant aluminum alloy layer acts as a cushion material for thermal stress.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for locally strengthening an aluminum cast part according to the present invention will be described below with reference to the accompanying drawings.

First, Al particles and Cu particles smaller in diameter are prepared, Cu particles are electrostatically adhered around the Al particles, and the Cu particles are placed in a container (centrifugal rolling device) equipped with 8,000 to 16,000 rpm rotating blades. And apply impact force in a high-speed air stream for 1 to 10 minutes. Due to this impact action, the Cu particles are firmly adhered to the Al particles, and as shown in FIG. 1, capsule particles 13 having the Al particles 11 as core particles and the Cu particles 12 as coating particles are obtained.

Next, as shown in FIG. 2, the powder of the capsule particles 13 is filled in a Cu pipe 14 serving as a sheath material.
This is drawn to form a welding wire 15 having a diameter of 0.8 to 1.6 mm as shown in FIG. The weight ratio between Cu and Al of the welding wire 15 containing the capsule particles 13 is, for example, 5
0:50.

Then, as shown in FIG. 4, the manufactured welding wire 15 is set in the MIG welding device 16, and a TIG welding torch 17 is arranged in series in front of the MIG welding device. M
The IG welding device 16 includes a nozzle 18 for blowing out an inert gas, and a wire supply mechanism 19 for sequentially sending out the welding wire 15, and performs arc welding using the welding wire 15 as a consumable electrode. . In addition, the TIG welding torch 17 includes an electrode 20 for generating an arc and a nozzle 21 for blowing out an inert gas.

The TIG welding torch 17 and the MIG welding device 16 are moved along a portion to be modified, for example, an inter-valve portion 22 of an aluminum cylinder head. Thus, the aluminum base material 23 is melted by the preceding TIG welding torch 17 to form a molten layer 24, and the molten layer 24 is formed.
The droplets of the welding wire 15 are added to the
An alloyed layer (alloyed portion) 25 to which (Cu) is added is obtained.

The TIG arc precedes the aluminum base material 2
Since the surface of No. ₃ is covered with an oxide (Al ₂ O ₃ ), it is destroyed. When a new layer of the base material comes out on the surface, the overlaying by MIG welding becomes possible. It is a thing. That is, the advantage of MIG welding, which has a high welding speed, can be utilized without prior cutting, and gas is eluted in the process of re-melting, thereby preventing the occurrence of blow holes due to porosity defects. Also, due to the residual heat effect of the TIG arc, conformity between the base material 23 and the welding wire 15 is improved, and the penetration depth can be increased.

After this build-up welding, as shown in FIG. 5, a MIG welding device 28 is used to form a build-up weld again on the central portion 26 of the alloy build-up portion 25 using a pure aluminum welding wire 27. I do. At this time, as shown in FIG.
If a sharpness 29 is formed in the central portion 26 of the alloy embossing portion 25, the portion is cut and removed (see FIG. 8), and rebuilding is performed so as to fill the groove 30, and the pure aluminum welding layer 3 is formed.
1 (see FIG. 9). Note that this cutting and removal may be performed by forming a groove 32 extending beyond the alloy embossed portion 25 (see FIG. 10), and rebuilding the groove to form a pure aluminum welded layer 33 (see FIG. 10). FIG.
1). Also, even after the center portion 26 has been cut and removed even if no cracks have occurred, the center portion 26 of the alloy embossed portion 25 may be re-overlaid with pure aluminum.
It is also conceivable to perform rebuilding so that it is included in the.

As shown in FIG. 6, an alloy embossed portion 25 containing a large amount of Cu is substantially T-shaped at a portion 22 between the intake port 3 and the exhaust port 4 of the cylinder head and the hot plug 34. And a pure Al-based welding layer 33 is distributed along the center thereof. By rebuilding the pure aluminum welding layer 33 in this way, not only does the shrinkage of the weld metal and the sharpening at the time of solidification occur,
Pure Al Re padding portion of the central portion 26 is-out work as relaxation material (cushion material) of the thermal stress, improves the lower surface of the heat cracking life of the cylinder head. That is, the performance and quality of the weld overlay of a heat-resistant aluminum alloy containing a large amount of heat-resistant components such as Cu are achieved.

In the above embodiment, the welding overlay is performed using the welding wire 15 containing the capsule particles 13. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention is also applicable to the case where the powder is added to form a buildup, and the heat-resistant substance to be added is also applied to metals and elements having similar characteristics in addition to Cu.

[0019]

In summary, according to the present invention, the following excellent effects are exhibited.

[0020] The part to be reinforced of the cast aluminum part is made of Cu or the like.
After forming a layer of welding buildup of heat resistant aluminum alloy containing refractory components, so it formed by welding buildup pure aluminum welding layer on the surface center of the heat resistant aluminum alloy layer, crack-free alloy prime gold unit Is obtained, and the quality is improved by relaxing the thermal stress.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing capsule particles for explaining one embodiment of a method for locally strengthening an aluminum cast part according to the present invention.

FIG. 2 is a perspective view of a sheath material for explaining a next step of FIG. 1;

FIG. 3 is a perspective view of a welding wire for explaining the next step of FIG. 2;

FIG. 4 is a side sectional view for explaining build-up welding using the welding wire of FIG. 3;

FIG. 5 is a side sectional view for explaining a step subsequent to FIG. 4;

FIG. 6 is a bottom view of the cylinder head modified by the process of FIG.

FIG. 7 is a plan view showing an alloy fill layer for explaining the step of FIG. 5;

FIG. 8 is a plan view for explaining a step subsequent to FIG. 7;

FIG. 9 is a plan view for explaining a step subsequent to FIG. 8;

FIG. 10 is a plan view showing another embodiment of FIG. 8;

FIG. 11 is a plan view for explaining the next step of FIG.

FIG. 12 is a bottom view of a cylinder head for describing a problem of the related art.

FIG. 13 is a perspective view of a piston for explaining a problem of the related art.

[Explanation of symbols]

 22 Inter-valve portion of cylinder head (part to be strengthened) 25 Alloy metal part 26 Central part

──────────────────────────────────────────────────続 き Continuing from the front page (72) Akira Tsujimura, Inventor 8 at Fujisawa City, Kanagawa Prefecture Inside Isuzu Central Research Institute Co., Ltd. (72) Tadashi Uemura 8 at Doha, Fujisawa City, Kanagawa Prefecture Isuzu Central Research Inc. In-house (56) References JP-A-62-21465 (JP, A) JP-A-49-121743 (JP, A) JP-A-62-161493 (JP, A) JP-A-56-2060 (JP, A) JP-A-53-137045 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/04 B23K 103: 10

Claims (1)

(57) [Claims] [1] A part to be strengthened of an aluminum casting part ,
After forming a layer of a heat-resistant aluminum alloy containing a heat- resistant component such as u by welding overlay, a pure aluminum welding layer is formed by welding overlay at the center of the surface of the heat-resistant aluminum alloy layer. <br/> A method for locally strengthening aluminum cast parts.