JPH05337831A - Shot peening method for aluminum connecting rod - Google Patents

Abstract

PURPOSE:To reduce the abrasion and breakage of particles blasted onto the surface of an aluminum connecting rod so as to compositionally deform the surface thereof in order to enhance a fatigue resistance strength, by specifying an arc height value and particles. CONSTITUTION:In the case of shot-peening an aluminum connecting rod, an arc height value which is an index for a draft based upon a curvature of a test piece during shot-peening is set in a range of 0.09 to 0.195mmA. Further, as particles 5 blasted onto the aluminum connecting rod 1 from a shot peening device 13, cast iron particles having a particle size of 0.25 to 0.45mm are used. With this arrangement, a fatigue resistance strength sufficient for the aluminum connecting rod can be obtained, and the abrasion and daynage of the shot- peening particles can be remarkably reduced, thereby it is possible to reuse the particles so as to enhance the economics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shot peening method used to increase the fatigue strength of a connecting rod made of an aluminum alloy (hereinafter referred to as "aluminum connecting rod").

[0002]

2. Description of the Related Art In general, when shot peening is applied to a connecting rod made of an iron-based material, steel particles having a particle size of about 1 mm are used. However, when shot peening is applied to an aluminum connecting rod, When the above-mentioned steel particles are used, the arc height becomes too large and the effect of obtaining fatigue strength is reduced, resulting in an overpeening state. Therefore, glass beads have been used as particles having a smaller specific gravity than the steel particles.

It should be noted that although shot peening is sometimes performed on aircraft parts made of aluminum alloy, in this case, shot peening is performed for the purpose of pretreatment of chromium plating, removal of the surface layer, and the like.

[0004]

By the way, in the conventional shot peening method for the aluminum connecting rod using the glass beads as described above, the glass beads themselves are expensive, and the glass beads are not damaged or worn. Significant and difficult to recycle, and not economical, have created the need to take other steps.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and it is possible to obtain sufficient fatigue strength as an aluminum connecting rod, and at the same time economically good shots of the aluminum connecting rod. It is intended to provide a peening method.

[0006]

A method for shot peening an aluminum connecting rod according to the present invention is a shot peening method for projecting particles on the surface of an aluminum connecting rod and plastically deforming the surface to improve fatigue strength.
The arc height value is set in the range of 0.09 to 0.195 mmA, and the particle size of shot peening particles is 0.25 to 0.
Shot peening is performed using 45 mm cast iron particles, and the above configuration is used as a means for solving the problem.

The arc height value in the above configuration is revised by the Japan Spring Manufacturers Association on September 1, 1982.
As described on pages 4 to 5 of the "shot peening work standard" issued as a plate, a special steel strip (G3311, SK5M to SK7M) has a length of 76 m.
A test piece "A" formed to have a m, a width of 19 mm, and a thickness of 1.295 mm was used to measure the amount of warpage of the test piece when shot peening was applied to the test piece. The unit is expressed as mmA and is used as an index of the workability.

Therefore, for the above-mentioned test piece "A",
Using cast iron particles with a particle diameter of 0.25 to 0.45 mm, each arc height value when shot peening was performed by changing the conditions such as the particle projection time and the projection speed was measured, and under the same conditions If shot peening is performed on an aluminum connecting rod, the degree of processing will correspond to the arc height value.

The grounds for limiting the numerical values of the arc height value and the particle size in the above structure are that cast iron particles having a particle size of 0.15 to 0.45 mm are used and the arc height value is 0.025 to 0.2.
Shot peening was performed on the aluminum connecting rods under various conditions in the range of mmA, and the aluminum connecting rods were subjected to a tensile / compression test.
9 to 0.195 mmA, and a particle size of 0.25 to 0.
This is because high durability can be obtained for those using 45 mm cast iron particles.

[0010]

In the shot peening method for aluminum connecting rods according to the present invention, the arc height value is 0.09-.
By using cast iron particles having a particle size of 0.25 to 0.45 mm as the shot peening particles in the range of 0.195 mmA, sufficient fatigue strength as an aluminum connecting rod can be obtained, and further, wear and damage of the particles can be prevented. Very few occurrences.

[0011]

[Example] Shot peening of aluminum connecting rod
As shown in FIG. 1, the aluminum connecting rod 1 is erected on a rotationally driven base 11, and a large end 2 of the aluminum connecting rod 1 is fixed by using a fixing tool 12 to rotate the base 11. The cast iron particles 5 are projected from the shot peening device 13 while being allowed to move. As a result, as shown in FIG. 2, shot peening is applied to the portion from the connecting rod 3 portion of the aluminum connecting rod 1 to the small end portion 4.

In this case, No. 10 aluminum connecting rods 0 to 9 were prepared, and No. 0 is unprocessed, N
o. For 1 to 9, the arc height value is 0.0
The projection speed and the projection time of the particles, which are the conditions for obtaining the respective workability, are adjusted so as to be different from each other in the range of 25 to 0.2 mmA, and further cast iron particles having a particle size of 0.15 to 0.45 mm Shot peening was done.

The condition for obtaining the desired arc height value can be experimentally obtained by shot peening using a test piece, and if the particle projection speed and projection time are adjusted based on this, Good.

After that, each aluminum connecting rod was subjected to a tension / compression test, and the number of repetitions of tension / compression until breakage was obtained.

The data of the processing conditions and the results of the tension / compression test for each aluminum connecting rod are shown in the table and the graph of FIG. Here, the coverage shown in the table is a value according to the projection time, with 95% coverage measured in shot peening using a test piece as 100%.

[0016]

[Table 1]

As is apparent from the above table and the graph of FIG. 3, the arc height value is 0.90 to 0.195 mmA.
No. which was shot peened using cast iron particles having a particle size of 0.25 to 0.45 mm. It was confirmed that the aluminum connecting rods Nos. 5 to 8 each had a number of repetitions of tension and compression exceeding 1 million times, and that sufficient fatigue strength, that is, sufficient durability was obtained.

No. Even with the aluminum connecting rod of No. 2, the number of repetitions of tension and compression exceeded 1 million times, but the arc height value was significantly smaller than the target range, and the arc height value was larger than this. No. In the connecting rods of Nos. 3 and 4, the number of repetitions of tension / compression is obviously small, and therefore, considering the above-mentioned limited range where reliable reliability can be obtained, No. The treatment condition of 2 was out of the limited range.

[0019]

As described above, according to the shot peening method for an aluminum connecting rod of the present invention, it is possible to obtain sufficient fatigue strength as an aluminum connecting rod, and at the same time, it is possible to prevent wear or breakage of shot peening particles. Since it can be made extremely small and the cast iron particles can be reused, there are excellent effects such as a significant saving in manufacturing cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a state where shot peening is performed on an aluminum connecting rod.

FIG. 2 is a front view showing an aluminum connecting rod after shot peening.

FIG. 3 is a graph showing the durability of shot peened aluminum connecting rods as a function of the arc height and the number of repetitions in a tension / compression test.

[Explanation of symbols]

 1 Aluminum connecting rod 5 Cast iron particles

Claims (1)

[Claims] 1. A particle is projected onto the surface of an aluminum connecting rod,
In the shot peening method for improving the fatigue strength by plastically deforming the surface, the arc height value is 0.09.
To 0.195 mmA, and cast iron particles having a particle diameter of 0.25 to 0.45 mm are used as the shot peening particles.