JP3230138B2 - 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 a tip material made of tungsten carbide (hereinafter referred to as WC) based cemented carbide, which is diffusion bonded to a low alloy steel tappet body with a strong bonding strength. The present invention relates to an internal combustion 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 at the same time as a 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: 0.4-3.5%, Ni: 0.4-4.5%, Mo: 0.
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 the top surface of the cam contact surface side of the low alloy steel is
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 ): 0.5
~10%, Nb, V, Ti , Mo, and Ta carbide (hereinafter, each represent _{NbC, VC, TiC, Mo 2} C, and at TaC, these are collectively referred to as metal carbides) one or more of : 0.1 to 7%, if necessary, F
e: 0.1 to 3%, WC: Remaining, when a WC-based cemented carbide chip material made of a sintered body having a composition composition of diffusion bonding is performed, in the resulting tappet member, Si and the chip of the tappet body are chipped. Due to the interaction of P constituting the material, the wettability of the chip material to the tappet body during diffusion bonding is remarkably improved, and Cr ₃ C ₂ dissolved in Co + Ni constituting the bonding phase of the chip material is improved. By this action, the adhesion of the tip material to the tappet body is remarkably improved, and the effect of improving the adhesion is further promoted by the coexistence of the metal carbide. In addition, since the WC-based cemented carbide is hard, a research result that excellent wear resistance is obtained is obtained.

[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 to 3.5%, and if necessary, Ni: 0.4 to 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%,
Cr ₃ C ₂ : 0.5 to 10%, one or more of metal carbides: 0.1 to 7%, if necessary, Fe:
0.1 to 3%, WC: Remaining, a WC-based cemented carbide chip material made of a sintered body having a compounding composition consisting of diffusion bonding is performed. It has.

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 dissolving in the base material to further improve the strength, they are contained as necessary. Less than 4% and Mo:
If the content is less than 0.15%, the desired strength-improving effect cannot be obtained. On the other hand, if the content exceeds Ni: 4.5% and Mo: 0.7%, the toughness is reduced. Ni: 0.4 to 4.5%, Mo: 0.15 to 0.7
%. Preferably, Ni: 2-3%, Mo:
The content of 0.3 to 0.5% is good.

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%. Preferably, the ratio is 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) In the PP component, the sinterability is improved to enable liquid phase sintering, and the coexistence of Si with the tappet body allows the tip material to wet the tappet body during diffusion bonding. 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) Cr ₃ C _{2 The} 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 of the tip material by P during 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 5%, the desired effect cannot be obtained, and if the content exceeds 10%, the strength decreases. Therefore, the content is set to 0.5 to 10%. Desirably, the ratio is 4 to 8%.

(E) Metal Carbide The metal carbide has the function of further improving the above-mentioned action of Cr ₃ C _2. If the content is less than 0.1%, the desired improvement effect cannot be obtained. Exceeds 7%, the strength is reduced.
It was determined as 1 to 7%. Preferably, the ratio is 0.5 to 3%.

(F) Fe Since the Fe component has a function of improving the hardness by forming a solid solution in the binder phase, it is contained as necessary. Since the desired effect of improving the hardness cannot be obtained and the strength whose ratio exceeds 3% decreases, the ratio is set to 0.1 to 3%. Desirably, the ratio is 0.3 to 1%.

In addition, the tappet member of the present invention generally has the above-mentioned WC-based cemented carbide tip material mounted 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.

[0018]

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 the chip material, WC powder, Cr ₃ C ₂ powder, various metal carbide powders, Co-P alloy (containing 35% P) powder, Fe— P alloy (P: 25%
Containing) powder, Fe powder, Co powder, Ni powder, and graphite powder, blending these raw material powders in the composition shown in Tables 2 and 3 and mixing, and then, at a pressure of 5 ton / cm ² , a diameter of 31 mm. ^φ × thickness: Press-molded into green compacts having a dimension of 3 mm, and these green compacts were heated to a predetermined temperature in the range of 1200 to 1300 ° C. in a vacuum of 1 × 10 ⁻² torr.
By sintering under the condition of holding for one minute, 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. Then, these were placed as shown on the top surface of the cam contact surface side of the tappet body A~P tip material a~q in combinations respectively shown in Table 4, in this state, 1 × 10 ^- After holding at a temperature of 1250 ° C. for 80 minutes in a vacuum of ² torr, a diffusion bonding treatment of forced cooling by spraying nitrogen gas was performed, and then in a normal carburizing gas atmosphere at a temperature of 880 ° C. for 180 minutes, and then The tappet members 1 to 15 of the present invention and the comparative tappet members 1 to 5 are manufactured by subjecting oil quenching immersed in oil at a temperature of 130 ° C. and tempering at 120 ° C. for 120 minutes in the air. did.

The comparative tappet members 1 to 5 are components that affect the joining strength between the tappet body and the tip material, ie, Si of the tappet body and P and (C) of the tip material.
(r ₃ C ₂ + metal carbide) 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 hp diesel engine.
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 4 shows the results of these measurements.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

[0024]

[Table 4]

[0025]

As can be seen from the results shown in Tables 1 to 4, the tappet members 1 to 15 of the present invention have excellent abrasion resistance without any peeling phenomenon of the tip material from the tappet body despite high-speed operation. whereas showing the sex, as seen in comparison tappet member 1 to 5, P and (Cr ₃ C ₂ + metal carbide Si and chip material greatly affects the tappet body junction of the tappet body and the tip member It is clear that if any one of the contents of (1) and (2) deviates from the range of the present invention, a strong bonding strength cannot be secured. As described above, according to the tappet member of the present invention, the tip member constituting the tappet member is extremely strongly bonded to the top surface of the tappet body on the cam contact surface side, so that the speed and performance of the internal combustion engine can be improved. They can respond satisfactorily and exhibit excellent performance over the long term.

[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.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁷ Identification code FI C22C 38/52 C22C 38/52 F01L 1/14 F01L 1/14 BF // B23K 103: 18 B23K 103: 18 (56) Reference Document JP-A-6-200715 (JP, A) JP-A-4-132806 (JP, A) JP-A-3-294452 (JP, A) JP-A-60-63349 (JP, A) JP-A-59-1984 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 rest of the tappet body made of a low alloy steel having a composition consisting of Fe and inevitable impurities, on the top surface on the cam contact surface side, Co: 20 to 30%, Ni: 3 to 15%,
(However, Co + Ni: 25 to 35%), P: 0.1 to 1%, chromium carbide: 0.5 to
10%, one of carbides of Nb, V, Ti, Mo, and Ta
Species or two or more: 0.1 to 7%, Tungsten carbide: Tungsten carbide: A cemented carbide tip material made of a sintered body with a blended composition consisting of: An internal combustion engine tappet member having: 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%, one or two of which are Fe,
And a low alloy steel tappet body having a composition of unavoidable impurities, on the top surface on the cam contact surface side, Co: 20 to 30%, Ni: 3 to 15%,
(However, Co + Ni: 25 to 35%), P: 0.1 to 1%, chromium carbide: 0.5 to
10%, one of carbides of Nb, V, Ti, Mo, and Ta
Species or two or more: 0.1 to 7%, Tungsten carbide: Tungsten carbide: A cemented carbide tip material made of a sintered body with a blended composition consisting of: An internal combustion engine tappet member having: 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 rest of the tappet body made of a low alloy steel having a composition consisting of Fe and inevitable impurities, on the top surface on the cam contact surface side, Co: 20 to 30%, Ni: 3 to 15%,
(However, Co + Ni: 25 to 35%), P: 0.1 to 1%, chromium carbide: 0.5 to
10%, one of carbides of Nb, V, Ti, Mo, and Ta
Species or two or more: 0.1 to 7%, Fe: 0.1 to 3%, Tungsten carbide: Tungsten carbide: Tungsten carbide-based cemented carbide chip material consisting of a sintered body having the composition of: An internal combustion engine tappet member having a chip material having a high bonding strength. 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: 0.4-4.5%, Mo: 0.15-0.4%.
7%, one or two of which are Fe,
And a low alloy steel tappet body having a composition of unavoidable impurities, on the top surface on the cam contact surface side, Co: 20 to 30%, Ni: 3 to 15%,
(However, Co + Ni: 25 to 35%), P: 0.1 to 1%, chromium carbide: 0.5 to
10%, one of carbides of Nb, V, Ti, Mo, and Ta
Species or two or more: 0.1 to 7%, Fe: 0.1 to 3%, Tungsten carbide: Tungsten carbide: Tungsten carbide-based cemented carbide chip material consisting of a sintered body having the composition of: An internal combustion engine tappet member having a chip material having a high bonding strength.