JPH02166225A - Manufacture of sliding member made or cast iron - Google Patents

Abstract

PURPOSE:To form the sliding part having no blowholes and having excellent pitching resistance, at the time of casting a sliding member by spheroidal graphite cast iron, subjecting the sliding part to remelting and rapid cooling and forming a hard chilled layer, by regulating the grain size of spheroidal graphite after remelting to specific value or below. CONSTITUTION:To manufacture a sliding member such as a cam shaft with spheroidal graphite cast iron and to improve the wear resistance by increasing the hardness at the sliding part with mating members, the sliding part is remelted by a high energy beam or the like and is thereafter rapidly cooled to chill the structure. In such a case, when the stock is spheroidal graphite cast iron, the stock has the characteristics that blowholes are hard to generate and it has high rigidity by the residue of Mg as a graphite spheroidizing agent, but, on the other hand, pitching resistance is deteriorated by the residue of unmolten spheroidal graphite. Thus, as a raw material, spheroidal graphite cast iron having 300 pieces/mm<2> graphite grain numbers is used and the graphite grain size at the remelting part is regulated to <=15mum, by which the sliding part having no presence of blowholes and having excellent rigidity and pitching resistance can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a cast iron sliding member used in automobile engines and the like.

(Prior art) With the recent increase in the output of automobile engines, harsh conditions are being required for sliding members that require wear resistance, such as camshafts and tappets among automobile engine parts. .

Therefore, in order to cope with such harsh conditions, as a manufacturing method for cast iron sliding parts, instead of the conventional method of cooling and chilling the sliding parts, we re-melted the sliding parts with a high-energy beam and chilled them. A method has been proposed.

More recently, as shown in Japanese Patent Application Laid-Open No. 58-50354, a material of spheroidal graphite cast iron with excellent rigidity has been used, and the sliding parts of this material are remelted using a high-energy beam as described above. A method has been proposed for chilling.

(Problem to be solved by the invention) However, the sliding member obtained by remelting spheroidal graphite cast iron has
Due to the deoxidizing effect of residual Mg, blowholes are less likely to occur.
In addition, although it has the characteristic of high rigidity, when the particle size of spheroidal graphite is large, there is a problem that spheroidal graphite cast iron graphite remains in an unmelted state after remelting treatment, worsening pitting resistance. be.

In view of the above, an object of the present invention is to provide spheroidal graphite cast iron that is free from blowholes, has high rigidity, and has excellent pitting resistance.

(Means for Solving the Problems) In order to achieve the above object, the present invention limits the number of particles of spheroidal graphite in the material and limits the particle size of the spheroidal graphite after remelting.

Specifically, the solution taken by the present invention is that the number of graphite particles is 300.
00 mm2 or more of a material for a sliding member made of spheroidal graphite cast iron is cast, the sliding part of this material is remelted and chilled with a high energy beam, and the graphite particle size after remelting is set to 15 μm or less. It is something to do.

(Function) With the above configuration, the number of graphite grains in the material of the spheroidal graphite cast iron sliding member is set to 3'00 pieces/m'm2 or more, and the graphite grain size after remelting is set to 15 μm or less. Therefore, cast iron sliding members have excellent pitting resistance.

In addition, since this cast iron sliding member is made of spheroidal graphite cast iron,
Blowholes are less likely to occur and the rigidity is high.

(Example) Embodiments of the present invention will be described below based on the drawings.

The present invention involves casting a material for a spheroidal graphite cast iron sliding member having a spheroidal graphite grain count of 300 particles/m2 or more, remelting the sliding part of this material with a high-energy beam to chill it, The graphite particle size after remelting is set to 15 μm or less.

As a preliminary step to the present invention, C: 34%, S
i: 2.6%, Mn: 0.3%, CuO 13%, Mg:
A cast iron alloy containing 0.045% Fe and the balance Fe was prepared. Next, by changing the casting method or inoculating these cast iron alloys, the shapes shown in Figures 3 (a) and (b) are obtained.
Length: 150mm, diameter: 29mm round bar), the first
First to fifth test materials having the number of graphite particles shown in the second column of the table and the graphite particle size shown in the third column were obtained.

(Hereinafter, blank space) The first test material in Table 1 was made using the sand casting method, and the number of graphite grains was 1.
A material having a size of 1010 mm2 and a graphite particle size of 40 μm was obtained.

As a second test material, a material having a graphite particle number of 236 pieces/mn]2 and a graphite particle size of 24 μm was obtained by the same sand casting method.

The third test material was inoculated by pouring, and the number of graphite particles was:
A material having a size of 44,545 mm2 and a graphite particle size of 12 μm was obtained.

As a fourth test material, a material having a graphite particle number of 34 pieces/mm2 and a graphite particle size of 10 μm was obtained by a die casting method.

As a fifth test material, a material having a graphite particle number of 98989 mm2 and a graphite particle size of 9 μm was obtained by the same die casting method.

Next, these first to fifth test materials were preheated to 200° C., and then TIG treatment, which is a high-energy beam treatment, was performed on a 50 mm long portion in the center. the result,
As shown in the fourth and fifth columns of Table 1, the first test material has a graphite number of 42 pieces/mm2, graphite particle size: 36, and the second test material has a graphite particle size of 20404 mm2, Graphite particle size 20μm
, the third test material has graphite particle number: 23030 mm2, graphite particle size: 10 μm1, and the fourth test material has graphite number 21919 mm2.
2. Graphite particle size: 8 μm, 5th test material has graphite particle number: 28
484 mm2, graphite particle size: 8 μm.

Next, these test materials were machined into the shape shown by the dashed line in FIG. 3 (diameter at the center: 28 mm) to obtain test piece 1. Then, using a pitching tester, as shown in Figure 4, SUJ steel 2 (diameter 130 mm)
) and conducted a pitching test. The results are shown in column 6 of Table 1, and the pitching strength (Kgf/mtn2) was 205 for the first sample and 205 for the second sample.
The test material is 2101, the third test material is 255, and the fourth test material is 2.
601 The fifth test shrine was 260.

FIG. 1 shows the relationship between the number of TIG-treated lead particles and the pitting strength according to the pitching test described above. As is clear from this Figure 1, the number of lead particles treated with TIG is 300.
When the number of particles/mm2 decreases, the pitching strength suddenly decreases. As a result, it was found that remelting a material with a TIG-treated lead particle count of 300 pieces/mm'' or more provides excellent pitting resistance.

A material having a graphite grain count of 300 particles/mm 2 or more before remelting can be obtained by performing so-called in-mold inoculation, pouring flow inoculation, or die casting.

FIG. 2 shows the relationship between the graphite particle size and pitting strength after TIG treatment according to the pitting test.

As is clear from FIG. 2, when the graphite particle size after TIG treatment becomes less than 15 μm, the pitting strength suddenly decreases. As a result, it was found that pitting resistance is excellent when the graphite particle size after TIG treatment is set to 15 μm or more.

(Effects of the Invention) As explained above, according to the method for manufacturing a cast iron sliding member according to the present invention, the number of spheroidal graphite particles is 300 pieces/m m
2 or more, and the graphite particle size after remelting of this material is set to 15 μm or less, so it is a spheroidal graphite cast iron with no blowholes, high rigidity, and excellent pitting resistance. can be easily manufactured.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the number of lead particles treated with TIG treatment and pitting strength, Figure 2 is a diagram showing the relationship between graphite particle size and pitting strength after TIG treatment, Figure 3 (A) and (
B) shows the shape of the test material, (A) is a front view, (B) is a side view, and a cross-sectional view showing the chingutist. Figure 4 shows the pitch

Claims (1)

[Claims] (1) A material for a sliding member made of spheroidal graphite cast iron with a graphite grain count of 300 pieces/mm^2 or more is cast, the sliding part of this material is remelted and chilled using a high energy beam, and after remelting A method for manufacturing a cast iron sliding member, characterized in that the graphite particle size of the graphite is set to 15 μm or less.