JP3254976B2 - Internal-combustion engine tappet member having high joining strength with chip material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine comprising a tip material made of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide and a low-alloy steel tappet body which is diffusion-bonded with a strong bonding strength. It relates to an engine tappet member.

[0002]

2. Description of the Related Art Conventionally, tappet members of internal combustion engines such as diesel engines and gasoline engines have been generally used.
For example, as described in Japanese Patent Application Laid-Open No. Sho 62-182406 and illustrated in a schematic longitudinal sectional view in FIG. 1, a tappet body usually formed by cold forging and made of carbon steel, alloy steel, or the like. And at least one of metal carbides, nitrides, and borides and N
There is known a tappet member formed by joining a chip material 2 made of an i or Ni alloy simultaneously with liquid phase sintering thereof.

[0003]

On the other hand, in recent years, the output and performance of an internal combustion engine have been remarkably increased, and accordingly, the tappet member, which is a structural member of the internal combustion engine, has been used under more severe conditions. In the conventional tappet member described above, the bonding strength between the tappet body and the tip material is not sufficient in the above-described conventional tappet member, so that under severe operating conditions, peeling is apt to occur between the two, and the reliability is low. There is a problem in the point.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above-mentioned viewpoints, as a result of conducting research to improve the joining strength of the tip material constituting the tappet member to the tappet body, the tappet body was determined by weight% (hereinafter,%
Indicates weight%), C: 0.13 to 0.5%, S
i: 0.15 to 0.35%, Mn: 0.3 to 1.2%,
Cr: 0.4 to 3.5%, and if necessary, Ni: 0.4 to 4.5%;
15 to 0.7% of one or two of the following,
The remainder is specified as a low alloy steel having a composition consisting of Fe and unavoidable impurities, and C
o: 20 to 30%, Ni: 3 to 15%, (however, Co + Ni: 25 to 35%), P: 0.1 to 1
%, Chromium carbide (hereinafter referred to as Cr ₃ C ₂ ): 0.1 to
When a tip material made of a WC-based cemented carbide made of a sintered body having a composition of 10%, if necessary Fe: 0.1 to 3%, and WC: remaining, is diffusion bonded, the resulting tappet member has The interaction between Si of the tappet body and P constituting the tip material significantly improves the wettability of the tip material to the tappet body at the time of diffusion bonding, and solidifies in Co + Ni constituting the bonding phase of the tip material. Melted Cr
The action of ₃ C ₂ significantly improves the adhesion of the tip material to the tappet body, and the tip material is extremely firmly bonded to the tappet body, and is excellent because the WC-based cemented carbide is hard. The research results show that it also has abrasion resistance.

[0005] The present invention has been made based on the above research results, wherein C: 0.13 to 0.5%,
Si: 0.15 to 0.35%, Mn: 0.3 to 1.2
%, Cr: 0.4-3.5%, and if necessary, Ni: 0.4-4.5%, Mo:
0.15 to 0.7% of the low-alloy steel tappet body containing one or two of the following components and having a balance of Fe and inevitable impurities, Co:
20-30%, Ni: 3-15%, (however, Co + Ni: 25-35%) P: 0.1-1%, C
r ₃ C ₂ : 0.1 to 10%, if necessary, Fe: 0.1
~ 3%, WC: The remaining material is obtained by diffusion bonding of a WC-based cemented carbide chip material consisting of a sintered body having a compounding composition consisting of: It is.

Next, in the tappet member of the present invention, the reason why the component composition of the tappet body and the compounding composition of the tipping material are limited as described above will be described. A. Ingredient Composition of Tappet Body (a) C The C component has a function of improving the strength by forming a solid solution in a base material. However, if the content is less than 0.13%, a desired strength improving effect cannot be obtained. If the content exceeds 0.5%, the toughness will decrease.
It was determined to be 13 to 0.5%. Preferably, 0.2 to
The content of 0.3% is good.

(B) Si The Si component has the effect of improving the wettability with the tip material by the coexistence of P in the tip material during the diffusion bonding, thereby improving the adhesion of the tip material to the tappet body. There is,
If the content is less than 0.15%, the desired effect cannot be obtained in the above-mentioned action, while if the content exceeds 0.35%, the strength is reduced.
It was determined as 5 to 0.35%. Desirably 0.2-0.3%
Is good.

(C) Mn The Mn component has a function of improving the toughness by forming a solid solution in the base material, but if its content is less than 0.3%, the desired effect of improving the toughness cannot be obtained. If the amount exceeds 1.2%, the strength rapidly decreases, so the content was determined to be 0.3 to 1.2%. Desirably 0.7-1%
Is good.

(D) Cr The Cr component has a function of improving the heat resistance by forming a solid solution in the base material, but if its content is less than 0.4%, the desired effect of improving the heat resistance cannot be obtained. If the content exceeds 3.5%, the toughness will decrease, so the content was determined to be 0.4 to 3.5%. Preferably, 1-3%
Is good.

(E) Ni and Mo Since these components have a function of further improving the strength by forming a solid solution in the base material, they are contained as necessary. Less than 4% and Mo:
If it is less than 0.15%, the desired effect of improving the strength cannot be obtained, while if its content exceeds 4.5% Ni and 0.7% Mo, the toughness is reduced. Ni: 0.4 to 4.5%, Mo: 0.15 to 0.7
%. Preferably, Ni: 2-3%, Mo:
The content is preferably 0.3 to 0.5%.

B. Composition of chip material (a) Co The Co component is an essential component for enabling sintering and ensuring toughness, but if its ratio is less than 20%, the desired effect can be obtained in the above-mentioned operation. On the other hand, if the ratio exceeds 30%, the hardness decreases, so the ratio is set to 20 to 30%. The ratio is preferably 23 to 25%.

(B) Ni The Ni component has an effect of improving the strength in the coexistence with the Co component. However, if the proportion is less than 3%, the desired effect of improving the strength cannot be obtained. Is 2
If it is less than 5%, the desired effects of the above-mentioned effects of Co and Ni cannot be obtained. On the other hand, if the proportion of Ni exceeds 15%, the toughness decreases, and in this case, the total amount of Ni and Co is 35%. Is exceeded, the abrasion resistance is reduced, so that the Ni content is 3 to 15%, preferably 5 to 7%.
%, The total amount of Ni and Co is 25 to 35%, preferably 28
３２32%.

(C) For the PP component, liquid phase sintering is made possible by improving the sinterability, and the tip material is wetted to the tappet body during diffusion bonding by coexistence with Si of the tappet body. However, if the ratio is less than 0.1%, the desired effect cannot be obtained, and if the ratio exceeds 1%, the embrittlement phenomenon appears. The ratio was defined as 0.1-1%. Preferably, 0.3
A ratio of ~ 0.7% is good.

(D) The Cr ₃ C ₂ Cr ₃ C ₂ component forms a solid solution with the binder phase, and is combined with Si of the tappet body and the effect of improving the wettability by the P of the tip material at the time of diffusion bonding. It has an effect of remarkably improving the adhesion to the main body, but the ratio is 0.1%.
If the content is less than 1%, the desired effect cannot be obtained, and if the content exceeds 10%, the strength is reduced. Therefore, the content is set to 0.5 to 10%. Desirably, the ratio is 4 to 8%.

(E) Fe The Fe component forms a solid solution in the binder phase and has the effect of improving its hardness. Therefore, the Fe component is contained as necessary. Since the desired effect of improving the hardness cannot be obtained, and if the ratio exceeds 3%, the strength decreases, the ratio is set to 0.1 to 3%. Desirably, the ratio is 0.3 to 1%.

Further, the tappet member of the present invention generally has a tip material made of a WC-based cemented carbide placed on the top surface of the low-alloy steel tappet body on the cam contact surface side. In a vacuum or reducing atmosphere, or in a non-oxidizing atmosphere, a temperature of 1200 to 1300 ° C.
After holding for 20 minutes, a diffusion bonding process is performed under cooling conditions, and then, in a normal carburizing gas atmosphere, at a temperature of 850 to 900 ° C. for 150 to 200 minutes, and then immersed in oil having an oil temperature of 120 to 140 ° C. It is manufactured by performing oil quenching and heat treatment of tempering in air at a temperature of 150 to 200 ° C. for 100 to 150 minutes.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the tappet member of the present invention will be specifically described with reference to embodiments. First of all, the shape and outer diameter shown in FIG.
× Length: Tappet bodies A to 51 having dimensions of 51 mm and made of low alloy steel having the component compositions shown in Table 1, respectively.
P was prepared. In addition, in order to form a chip material, WC powder, Cr ₃ C ₂ powder, and Co-P alloy (P: 35% content) each having a particle size of 100 mesh or less are used as raw material powders.
Powder, Fe-P alloy (containing 25% P) powder, Fe powder, Co powder, Ni powder and graphite powder were blended in the composition shown in Table 2 and mixed. Diameter: 31mm ^φ × thickness: 3mm under pressure of cm ²
Pressed into green compacts having the following dimensions, and sintering these green compacts in a vacuum of 1 × 10 ^-2 torr at a predetermined temperature in the range of 1200 to 1300 ° C. for 60 minutes do it,
Chip materials a to q each made of a WC-based cemented carbide made of a sintered body having a theoretical density ratio of 95% or more were manufactured. Next, these tip materials a to q are mounted as shown in the drawing on the top surfaces of the tappet bodies A to P on the cam contact surface side in combinations shown in Table 3, respectively.
After holding at a temperature of 1250 ° C. for 80 minutes in a vacuum of × 10 ^-2 torr, diffusion bonding treatment of forced cooling by blowing nitrogen gas was performed, and then in a normal carburizing gas atmosphere, temperature: 880.
After holding at 180 ° C. for 180 minutes, the tappet members 1 and 2 of the present invention are subjected to oil quenching immersed in oil at an oil temperature of 130 ° C. and tempering in air at 120 ° C. for 120 minutes.
15 and comparative tappet members 1 to 5 were manufactured, respectively.

The comparative tappet members 1 to 5 are components that affect the bonding strength between the tappet body and the tip material, ie, Si of the tappet body and P and Cr of the tip material.
The content ratio of any one of ₃ C ₂ is out of the range of the present invention.

Next, the Vickers hardness of the tip material was measured for the various tappet members obtained as a result, and this was assembled in a 6-cylinder 12-valve, 8200 cc, 210 horsepower diesel engine, and the number of revolutions was 3000 rpm.
pm, operation time: 200 hours of high-speed rotation conditions, actual machine tests were performed to measure the maximum wear depth of the tip material on the cam sliding surface and to evaluate the joining strength of the tip material to the tappet body. The joint surface between the two was observed along the outer periphery, and the number of cracks caused by peeling was measured. Further, for the purpose of evaluating the bonding strength, the shear strength of the bonding surface was also measured. Table 3 shows the results of these measurements.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

As can be seen from the results shown in Tables 1 to 3, the tappet members 1 to 15 of the present invention have excellent abrasion resistance without causing a peeling phenomenon of the tip material from the tappet body despite high-speed operation. As shown in the comparative tappet members 1 to 5, any one of Si of the tappet body and P and Cr ₃ C ₂ of the tip material, which greatly affect the joining between the tappet body and the tip material, as shown in the comparative tappet members 1 to 5. It is clear that if the content ratio deviates from the range of the present invention to the lower side, a strong bonding strength cannot be secured to them. As described above, the tappet member of the present invention
Since the tip material constituting this is remarkably firmly joined to the top surface of the tappet body on the side of the cam abutting surface, it can sufficiently cope with high speed and high performance of the internal combustion engine, and is excellent for a long time. It demonstrates its performance.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view illustrating a tappet member of an internal combustion engine.

[Explanation of symbols]

 1 Tappet body, 1a Top surface of tappet body on cam contact surface side, 2 Tip material.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C22C 38/00 304 C22C 38/00 304 38/18 38/18 38/44 38/44 F01L 1/14 F01L 1/14 BF // B23K 103: 18 B23K 103: 18 (56) References JP-A-6-200715 (JP, A) JP-A-4-132806 (JP, A) JP-A-3-294452 (JP, A) JP JP-A-60-63349 (JP, A) JP-A-59-9148 (JP, A) JP-A-53-80319 (JP, A) JP-A-60-39149 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) B23K 20/00-20/227 F01L 1/14

Claims (4)

(57) [Claims] C .: 0.13 to 0.5%, Si: 0.15 to 0.5% by weight.
35%, Mn: 0.3 to 1.2%, Cr: 0.4 to 3.5
%, And the remainder is composed of a low-alloy steel tappet body having a composition of Fe and inevitable impurities, Co: 20 to 30%, Ni: 3 to 15%, , Co + Ni: 25-35%), P: 0.1-1%, chromium carbide: 0.5-
10% Tungsten Carbide: An internal-combustion engine tappet member having a high joining strength, formed by diffusion-bonding a tungsten carbide-based cemented carbide chip material made of a sintered body having a composition of the following: 2. C .: 0.13-0.5% by weight, Si: 0.15-0.
35%, Mn: 0.3 to 1.2%, Cr: 0.4 to 3.5
%, Ni: 0.4-4.5%, Mo: 0.15-0.4%.
7%, and one or two of the following, and the remainder is made of a low-alloy steel tappet body having a composition consisting of Fe and unavoidable impurities. Ni: 3 to 15% (however, Co + Ni: 25 to 35%) P: 0.1 to 1%, chromium carbide: 0.1 to
10% Tungsten Carbide: An internal-combustion engine tappet member having a high joining strength, formed by diffusion-bonding a tungsten carbide-based cemented carbide chip material made of a sintered body having a composition of the following: C .: 0.13 to 0.5%, Si: 0.15 to 0.5% by weight.
35%, Mn: 0.3 to 1.2%, Cr: 0.4 to 3.5
%, And the remainder is composed of a low-alloy steel tappet body having a composition of Fe and inevitable impurities, Co: 20 to 30%, Ni: 3 to 15%, , Co + Ni: 25-35%), P: 0.1-1%, chromium carbide: 0.1-
10%, Fe: 0.1-3%, Tungsten carbide: Remaining, Tungsten carbide-based cemented carbide made of a sintered body having a composition of: Internal combustion engine tappet member. 4. C .: 0.13 to 0.5% by weight, Si: 0.15 to 0.5% by weight.
35%, Mn: 0.3 to 1.2%, Cr: 0.4 to 3.5
%, Ni: 0.4 to 4.5%, Mo: 0.15 to 0.5%.
7%, and one or two of the following, and the remainder is made of a low-alloy steel tappet body having a composition consisting of Fe and unavoidable impurities. Ni: 3 to 15% (however, Co + Ni: 25 to 35%) P: 0.1 to 1%, chromium carbide: 0.1 to
10%, Fe: 0.1-3%, Tungsten carbide: Remaining, Tungsten carbide-based cemented carbide made of a sintered body having a composition of: Internal combustion engine tappet member.