JP3135612B2 - Al alloy member and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy member and a method of manufacturing the same, and more particularly to a measure against wear.

[0002]

2. Description of the Related Art In recent years, internal combustion engines of automobiles and the like have tended to increase output and rotate at high speed. For this reason, the thermal load of the piston becomes high, and particularly when the piston ring groove is high temperature, when the piston is made of an Al alloy, Al adheres to the side surface of the piston ring groove and wear of the piston ring groove increases. Or the upper and lower surfaces of the piston ring groove are slackened, thereby impairing the sealing performance.

Therefore, as disclosed in, for example, Japanese Utility Model Laid-Open Publication No. 59-81756, a ceramic fiber is cast around the piston ring groove to improve the wear resistance and the like of the piston ring groove and to provide a seal. There is known a piston which ensures the performance.

Further, as disclosed in, for example, JP-A-1-190951 and JP-A-2-78752, a piston in which an alumite-treated layer is formed in a piston ring groove to secure a sealing property is also known. Proposed.

[0005]

However, it is very difficult in production to cast a ceramic fiber around the piston ring groove as in the former case, and the reliability is not necessarily sufficient. Absent. Further, in the latter case, since the Si particles are exposed on the surface of the piston ring groove, the adhesion of the alumite-treated layer is hindered, and the alumite-treated layer is easily peeled, so that its function cannot be exhibited sufficiently.

The present invention has been made in view of the above-mentioned point, and an object of the present invention is to adopt the latter method, and in this case, to alumite-treat a material of an Al alloy member such as a piston. The object of the present invention is to improve the adhesion of the alumite-treated layer by reducing or diluting Si particles exposed on the surface of the material in the previous stage.

[0007]

In order to achieve the above object, a first solution of the present invention according to claim 1 is to form an aluminum alloy material containing Si, and to use a Si surface of a sliding surface portion. That is, the particles were refined by re-melting with high-density energy heat rays, and an alumite treatment layer was formed on the sliding surface.

According to a second aspect of the present invention, in the first aspect, a piston for an internal combustion engine is targeted, and a sliding surface portion is a piston ring groove.

A third solution of the present invention according to claim 3 is to re-melt a portion to be a sliding surface portion of an Al alloy material containing Si with a high-density energy hot wire to refine Si particles. And an alumite treatment to obtain an Al alloy member.

According to a fourth aspect of the present invention, in the third aspect, the Al-based filler material is melted into a portion serving as a sliding surface portion of the Al alloy material when remelting. That is what we did.

[0011]

With the above arrangement, in the present invention according to the first to third aspects, the portion serving as the sliding surface of the Al alloy material containing Si is re-melted with high-density energy heat rays to reduce the size of the Si particles. And then alumite treatment.
In the present invention according to the present invention, at the time of remelting, since the Al-based filler material is melted into the above-mentioned sliding surface portion, the Si particles exposed on the material surface are reduced or diluted, and the adhesion of the alumite-treated layer is reduced. Will be better.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of an aluminum alloy member according to an embodiment of the present invention;

FIG. 2 shows a piston 1 for an internal combustion engine as an Al alloy member. Three piston ring grooves 3, 3, 3 as sliding surfaces are formed on the outer periphery of the upper part of the piston 1. The piston 1 is formed of a piston material 1 '(shown in FIG. 3) as a material made of an Al alloy containing Si, and as shown in FIG. The particles 5, 5,... Are refined by re-melting with high-density energy heat rays such as a laser, an electron beam, and a TIG.
Al-Mn, Al-Mg, Al-Cu-Mg, A
Rod-shaped Al-based filler metal 7 made of l-Zn-Mg-based alloy or the like
(Shown in FIG. 3) and an alumite treatment layer 9 is formed in each piston ring groove 3.

Next, the procedure for manufacturing the piston 1 according to Examples I and II will be described together with Comparative Examples.

<Embodiment I> First, as shown in FIG.
A piston material 1 'made of JIS AC8A obtained by gravity casting is prepared, and the piston material 1' is rough-worked so that a portion (ring groove 3 ') to become the piston ring groove 3 is machined to a width of 5 mm.

Next, the piston material 1 'is heated to 100 ° C.
And a filler material 7 made of pure Al having an outer diameter of 4 mm is interposed in the ring groove 3 ', and while the piston blank 1' is rotated three times, the ring groove 3 'is filled with argon, helium or the like using the TIG welding apparatus 11. An arc 17 is generated between the inert gas 13 and the tungsten electrode 15 in the atmosphere of the inert gas 13 and is re-melted by the high-density energy heat ray. Thereby, the ring groove 3 '
Of the Si particles 5 are refined and diluted by the penetration of the filler material 7. The remelting conditions at this time were as follows: the peripheral speed of the piston material 1 'was 100 to 150 mm / min, and the current value was 10
0 to 180 A, 9 mm bead width. At this time, the metal structure of the remelted portion is α phase 86% in area ratio, eutectic Si
The microstructure was 14% and the dendrite arm spacing was 8 μm. In FIG. 3, reference numeral 19 denotes a gas nozzle;
Is a conductor, and 23 is a gas shield.

After that, the piston blank 1 'is subjected to a T6 treatment, and then a finishing process is performed.

Thereafter, the piston material 1 'is degreased with acetone, and then immersed in a 25% sulfuric acid electrolyte solution (Al ion 0.3%) at 1 ° C., a DC current, a voltage of 20 to 35 V, and a current density of 2 A / The alumite treatment was performed for 25 minutes in dm ² , and the piston 1 was obtained by immersing in warm water and sealing. The roughness of the surface of each piston ring groove 3 of the piston 1 was Rmax 6 to 15 μm, and the thickness of the alumite treatment layer 9 was a uniform layer of 14 to 23 μm.

In order to form a uniform alumite-treated layer 9, it is preferable that the amount of eutectic Si in the metal structure be small. Therefore, it is preferable that the area ratio is 70% or more of α phase and 30% or less of eutectic Si. This is because if the eutectic Si exceeds 30%, the eutectic Si may be largely crystallized in the form of a net at the crystal grain boundary, and the formation of the alumite-treated layer 9 becomes poor at this crystallized portion, so that a uniform layer cannot be obtained. Because. In addition, dendrite arm sparing can determine the state of miniaturization of the metal structure, and in order to obtain a uniform alumite-treated layer 9, 5 to 20 μm is used.
m is preferred. This is because if it is less than 5 μm, the cooling rate at the time of re-melting is too fast, and defects such as pinholes are likely to occur, while if it exceeds 20 μm, the granular eutectic Si becomes large and the formation of the alumite treatment layer 9 is localized It is because it is inhibited.

<Embodiment II> First, a piston blank 1 'made of the same material as that of Embodiment I is roughly processed.

Next, the piston material 1 'is heated to 100 ° C.
The ring groove 3 'is re-melted with a high-density energy hot wire using the TIG welding device 11 while rotating the piston blank 1' three times. Thereby, the Si particles 5 in the ring groove 3 'are miniaturized. The remelting conditions at this time were as follows: the peripheral speed of the piston material 1 'was 100 to 150 mm / min, and the current value was 70 to 120.
A, The bead width is 5 mm. The metal structure of the remelted portion at this time was a fine structure having an area ratio of 57% of α phase, 43% of eutectic Si, and 8 μm of dendrite arm spacing.

Thereafter, the piston material 1 'was subjected to T6 treatment, finishing, alumite treatment and sealing treatment under the same conditions as in Example I to obtain the piston 1. The surface roughness of each piston ring groove 3 of the piston 1 is Rmax 8 to 18 μm.
The thickness of the alumite-treated layer 9 was a uniform layer of 12 to 23 μm.

<Comparative Example> The same procedure as in Example I was performed except that the ring groove 3 'was not re-melted by the TIG welding apparatus 11. The roughness of the surface of each piston ring groove 3 of this piston 1 was as large as Rmax 8 to 24 μm, and the thickness of the alumite treatment layer 9 was as widely as 7 to 27 μm. The metal structure of the base material was 53% in α phase, 47% in eutectic Si, and 27 μm in dendrite arm spacing in terms of area ratio.
It was a casting structure.

Then, endurance tests were performed on the pistons 1 according to Example I and Comparative Example obtained as described above, and the results are shown in FIG. In FIG. 4, the mark ○ indicates the amount of blow-by gas before the durability test of Example I, the mark ● indicates the amount of blow-by gas after the durability test of Example I, and the mark × indicates the amount of blow-by gas before the durability test of Comparative Example. The amounts are indicated respectively. As is clear from FIG. 4, after the endurance test of Example I, the blow-by gas amount was 5 × 10 ³ rp when the engine speed was 5 × 10 ³ rp.
Even when the engine speed exceeded 50 m / min, the blow-by gas amount suddenly increased and greatly exceeded 40 l / min when the engine speed exceeded 5 × 10 ³ rpm in the comparative example. It turns out that there is.

FIG. 5 shows the amount of wear of the piston ring groove (top ring groove) 3 after the durability test of the piston 1 according to Example I and the comparative example. As is clear from FIG. 5, the wear amount in Example I was as small as about 10 μm, but in the comparative example, it was as large as at least about 35 μm.

These facts show that in Examples I and II, the Si particles 5 in the ring groove 3 ′ are reduced in size or diluted, and the adhesion of the alumite treatment layer 9 is improved.

[0027]

As described above, according to the first to third aspects of the present invention, a portion to be a sliding surface portion of a Si-containing Al alloy material is re-melted with a high-density energy hot wire to form S
According to the fourth aspect of the present invention, the Al-based filler material is melted into the above-mentioned sliding surface portion at the time of re-melting while the i-particles are refined and then subjected to alumite treatment. Si particles to be formed can be made finer or diluted to improve the adhesion of the alumite-treated layer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a metal structure of a piston ring groove.

FIG. 2 is a front view of a piston.

FIG. 3 is a longitudinal sectional view showing a remelted state of a ring groove by a TIG welding device.

FIG. 4 is a diagram showing data of a blow-by gas amount.

FIG. 5 is a view showing data of a wear amount of a piston ring groove.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piston (member made of Al alloy) 1 '... Piston material (material made of Al alloy) 3 ... Piston ring groove (sliding surface portion) 3' ... Ring groove (location to be a sliding surface portion) 5 ... Si particles 7 ... melting Additive 9… Alumite treatment layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C25D 11/00-11/24 C22F 1/04 F02F 3/00 F16J 9/00

Claims (4)

(57) [Claims] 1. A sliding member formed of an Al alloy material containing Si, the Si particles on the sliding surface are refined by re-melting with a high-density energy heat ray, and an alumite treatment layer is formed on the sliding surface. Al
Alloy members. 2. A piston for an internal combustion engine, wherein a sliding surface portion is a piston ring groove.
An aluminum alloy member as described in the above. 3. An Al alloy material containing Si is re-melted with a high-density energy hot wire at a portion to be a sliding surface portion to refine the Si particles, and then subjected to an alumite treatment to form an Al alloy.
A method for producing an Al alloy member, comprising obtaining an alloy member. 4. The method for manufacturing an Al alloy member according to claim 3, wherein an Al-based filler material is melted into a portion to be a sliding surface of the Al alloy material when remelting.