JPH0513772B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the technical field of manufacturing the inner surface of a piston sliding bore of an aluminum cylinder block of an engine installed in an automobile.

In this invention, the inner surface of the piston sliding bore of an aluminum cylinder block mounted on an automobile, etc. is honed for finishing, and then ECM treatment is applied to prevent scuffing of the cylinder bore to remove aluminum on the inner surface of the bore. This invention relates to a bore method that exposes Si particles by melting and removing them. In particular, when performing ECM treatment on the inner surface of the bore after honing, it is necessary to remove the Si particles to a depth of 30 to 50 μm, which is approximately equal to the diameter of the Si particles. Processing is performed to remove Si particles with cracks during honing along with melted aluminum, expose Si particles without cracks, and in this state, expose the Si particles without cracks in a protruding state on the inner surface of the bore. This invention relates to a method for boring an aluminum cylinder block, in which a soft jig such as a buff is used to perform finish honing.

<Prior art> As is well known, engines installed in automobiles are required to have high strength due to demands for improved fuel efficiency and increased horsepower.
In addition, lightweight materials are being used, and aluminum cylinder blocks have recently come into use due to their good workability.

In the case of an aluminum cylinder block, there is a potential problem that a so-called scuff occurs due to material compatibility with the relatively sliding piston or piston ring.

Therefore, in order to solve this problem, we created a group of Si particles on the inner surface of the bore in order to solve the problem of aluminum remaining on the inner surface of the bore and melting of the aluminum due to sliding between the piston and piston ring, which is a cause of scuff occurrence. A technique has been developed to avoid scuffing with aluminum by protruding Si particles in the form of fine particles and causing relative sliding between the Si particles and the piston or piston ring. One of these is ECM (ELECTRIC CHEMICAL).
MACHINING) treatment technology, which is basically an effective countermeasure technology for preventing scathing.

The ECM treatment method will be explained with reference to FIGS. 4, 5, and 6. For example, an aluminum cylinder block 1 made of A390 aluminum alloy will be described.
When the bore inner surface 2 is formed by performing a predetermined honing process on the aluminum base 2 of the aluminum alloy, an exposed surface with Si particles 4 scattered on the aluminum base 2 of the aluminum alloy is formed on the bore inner surface 2. 4 is 30-50μm
With the current honing technology, nearly 100% of the Si particles on the bore surface crack 5, and
Thereafter, by performing the basic ECM process described above, the aluminum base 2 is melted and removed, leaving Si particles 4 with cracks 5 formed on the bore inner surface 2.

In this state, a bore inner surface 2' as shown in FIG. 5 is formed, and it is true that Si
Although particles 4, 4... are exposed in a protruding state,
Almost all of them have cracks 5,
Therefore, when the engine is operated, the piston or piston ring slides relative to the inner surface 2' of the bore of the aluminum cylinder block.
As mentioned above, almost all of the protruding Si particles 4 have cracks 5, so almost all of them break down over time.
The Si particles 4 break down and fall off, leaving the aluminum base exposed on the inner surface 2' of the bore.
There was a drawback that scathing inevitably occurred.

<Problems to be Solved by the Invention> When analyzed and examined in detail based on experiments, this problem is found to be due to the fact that all of the Si particles exposed on the inner surface of the bore after honing are formed with cracks. Although the root cause of this problem is related to the temporal processing depth in the ECM treatment process after honing, the falling off of protruding Si particles during the ECM treatment process is said to be the cause. It has gradually become clear that this is due to the fact that the thickness was set at 2 to 3 μm to avoid this problem.

The purpose of this invention is to solve the technical problem of scarfing, which is caused by Si particles formed during boring by honing based on the above-mentioned conventional technology, and to solve the basic problem of ECM processing. While taking advantage of the excellent theoretical aspects, we ensured that the protruding Si particles exposed on the inner surface of the bore were exposed without cracks, ensuring that the Si particles were not connected to the piston or piston ring. An excellent bore machining method for aluminum cylinder blocks that can reliably prevent the occurrence of scuffs by avoiding relative sliding with the aluminum component, and that is beneficial to the field of engine technology application in the automobile industry. This is what we intend to provide.

<Means/effects for solving the problems> In order to solve the above-mentioned problems, the structure of the present invention, which is based on the above-mentioned claims, is to provide an aluminum cylinder used in an engine installed in a car, etc. The inner surface of the bore of the block is honed to expose the Si particles with cracks formed on the inner surface of the bore, scattered in the aluminum, and then
When applying ECM treatment to the inner surface of the bore,
In addition, cracks exposed on the inner surface of the bore after honing were formed by performing ECM treatment to a depth equal to the diameter of the Si particle from the inner surface of the bore, that is, a depth of 30 to 50 μm. All Si particles are removed together with the dissolved aluminum, and Si particles with no cracks formed are exposed in a protruding shape on the inner surface of the bore to prevent the inner surface of the bore from becoming rough due to ECM treatment at the depth. As a treatment, finish honing is performed using a soft jig such as a buff to scatter crack-free Si particles on the inner surface of the bore, allowing relative sliding of the piston, piston ring, etc., and preventing relative sliding with the aluminum component. Technical measures have been taken to ensure that scathing is prevented.

<Example> Next, an example of the present invention will be described below based on FIGS. 1 to 3. In addition, 4th to 6th
Components having the same features as those in the drawings will be described using the same reference numerals.

The aluminum cylinder block 1 of an automobile engine shown in Fig. 1 is made of A390 aluminum alloy, and the aluminum base 3 has Si particles 4 with a grain size of 30 to 50 μm dispersed in a predetermined manner, and is subjected to a predetermined honing process. By doing this, the aluminum base 3 and the Si particles 4 with cracks 5 formed thereon are exposed in a dispersed state on the bore inner surface 2 according to the current state of the art, similar to the conventional method.

Therefore, as shown in Figure 2, ECM treatment is basically carried out in the same manner as in the conventional method, but as mentioned earlier, the treatment depth from the inner surface of the bore is 2 to 3 μm in the conventional method, whereas the treatment depth is longer over time. Si particles 4 depending on the processing means
The processing depth is 30 to 50 μm, which is equal to the particle size of The inner surface of the bore 2', which has been peeled off, washed away, and subjected to a long ECM treatment over time, is rough, and Si particles 4, 4, . . . without cracks are exposed on the surface.

Therefore, as shown in Figure 3, finish honing is performed on the bore inner surface 2' using a soft jig such as a buff, and crack-free Si particles 4, 4... are applied to the bore inner surface 2'' that has been finish honed. A residual shape is obtained with an adhesively fixed and protruding shape.

The aluminum cylinder block 1 which has been finish-honed in this manner has the piston or piston ring exposed in a protruding manner from the bore inner surface 2'' when used for engine operation. Since a sliding relationship with the piston ring is created and direct sliding against the aluminum base is avoided, scuffing due to melting of the aluminum base 3 is prevented.

Moreover, since each Si particle 4 in the protruding state is bonded to the aluminum base by molecular engineering as an aluminum alloy, peeling due to sliding with the piston or piston ring can be avoided over time.

It goes without saying that the embodiments of the present invention are not limited to the above-mentioned embodiments, and various embodiments can be adopted.

Furthermore, it goes without saying that the application target is not limited to engines installed in automobiles.

<Effects of the Invention> As described above, according to the present invention, Si particles without cracks are basically formed on the inner surface of the bore during the ECM treatment application process after honing in the bore machining of aluminum cylinder blocks for use in automobile engines, etc. In order for the exposed state to be maintained,
An excellent effect is achieved in that the risk of the Si particles being peeled off due to cracks when the piston or piston ring slides on the Si particles, resulting in scuffing, can be avoided.

Therefore, the lightweight of the aluminum cylinder block,
The effect is that good points such as rigidity retention are utilized as designed.

Therefore, by applying ECM treatment to the inner surface of the bore after honing, the exposed Si
Although cracks are formed in the particles, by performing ECM treatment over time to a depth approximately equal to the particle size of the Si particles, Si particles with unavoidable cracks after initial honing can be removed from the aluminum matrix by ECM treatment. The Si particles are peeled off and removed as they flow out due to melting, and the unbroken Si particles inside are exposed.
The subsequent finish honing process has the excellent effect of correcting and smoothing the roughness of the inner surface of the bore due to the long time ECM process.

Furthermore, since the ECM treatment and the subsequent finish honing can be performed using conventional techniques, special techniques and equipment are not required, and in particular, there is no risk of increased costs, which is an excellent effect.

[Brief explanation of the drawing]

Figures 1 to 3 are process diagrams of the bore machining method of the present invention, where Figure 1 is a sectional view after honing, Figure 2 is a sectional view after ECM treatment, and Figure 3 is after finish honing. FIG. Figure 4 and the following are process diagrams of the bore machining method based on the conventional technology, and Figure 4 is a cross-sectional view after honing.
FIG. 5 is a cross-sectional view after ECM treatment, and FIG. 6 is a cross-sectional view of the inner surface of the bore after Si particles have been peeled off due to internal cracks formed by the piston or piston ring during actual use after FCM treatment. 1... Aluminum cylinder block, 2... Bore inner surface, 4... Si particles, 5... Cracks, 2'... Finish honed surface.

Claims (1)

[Claims] 1 In a bore processing method in which the inner surface of the bore of an aluminum cylinder block is honed and then subjected to ECM treatment to expose Si particles on the inner surface of the bore, the ECM treatment is applied to the inner surface of the bore to a depth approximately equal to the Si particle diameter. 1. A method for boring a bore in an aluminum cylinder block, characterized in that the hole machining process is carried out to expose crack-free Si particles, and then performs finish honing while maintaining the exposed state of the crack-free Si particles.