JPH01306064A - Manufacture of sliding member - Google Patents

Abstract

PURPOSE:To improve wear resistance on sliding surface without damaging rigidity in the sliding part base material by forming the base material part in the sliding part with air-quenching steel and executing build-up welding with surface hardening material on the sliding face arranged at one end of the base material. CONSTITUTION:The air-quenching steel of SNCM, etc., is used as raw material and the sliding part base material 3 is formed by forging, etc. Successively, the sliding part base material 3 is set at the position corresponding to the sliding part in a die for die casting of a main body part 2 and for example, molten A alloy is cast and fitting part 3b in the sliding part base material 3 is included as cast-in together with the main body part 2 and the sliding part base material 3 is stuck to the main body part 2. Then, after removing by cutting unnecessary parts of sprue, etc., the casting flash is removed. Successively, the main body part 2 is fixed to a welding jig and the build-up welding is executed on the sliding surface 3a in the sliding part base material 3 with the surface hardening material. Therefore, build-up welding layer 4 having high hardness is formed on the sliding surface 3a to improve the wear resistance. Further, the base material 3 is heated and the temp. thereof is raised by heat input at the time of the build-up welding and after that, by executing natural cooling, the base material 3 is quenched and hardened to improve the rigidity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a sliding member having a sliding portion in a portion thereof.

[Prior Art] As is well known, sliding parts such as rocker arms and camshafts, which constitute the main parts of the valve train of a vehicle engine, are required to maintain sufficient engine performance over a long period of time. In order to achieve this, sliding characteristics that can withstand harsh usage conditions are required.

Conventionally, for example, regarding the above-mentioned rocker arm,
The main body part that is attached to the rocker arm shaft is made of a light alloy such as an aluminum alloy, and only the sliding part that makes sliding contact with the cam part of the camshaft is made of a material with excellent wear resistance, such as a sintered alloy member. are generally well known (for example, Japanese Patent Application Laid-Open No. 177159/1983)
(see publication).

According to this method, by using a light alloy for the main body portion, it is possible to contribute to reducing the weight of the engine, reduce the inertial weight of the rocker arm, and reduce the load on the sliding portion. A predetermined wear resistance can be imparted to the part.

Incidentally, in recent years, the operating conditions have become more severe as engines have increased in speed and output, and in particular, the amount of valve lift has increased due to the increased number of valves and variable valve timing. In order to maintain engine performance, each sliding part is required to have better wear resistance than ever before.

[Problems to be Solved by the Invention] For this reason, it is conceivable to weld a harder and more wear-resistant material to the sliding portion to improve the wear resistance of the sliding surface, but in this case, Conventionally, although it is true that high hardness can be obtained for the sliding surface, the base material of the sliding part is softened by the heat input during overlay welding, resulting in a decrease in its rigidity, especially at high speeds of engines. There has been a problem in that durability may be impaired, such as causing depping on the sliding surface in the rotation range.

This invention has been made in view of the above problems, and when manufacturing a sliding member in which a sliding portion is provided in a part thereof, the sliding surface can be resistant to damage without impairing the rigidity of the sliding portion base material. It is an object of the present invention to provide a manufacturing method that can improve wear resistance.

[Means for Solving the Problems] Therefore, the present invention includes a sliding part base material provided with a sliding part and a main body part holding the sliding part base material, and the main body part is cast into a casting slot. A sliding part base material made of air-hardened steel is placed in a part of the mold corresponding to the sliding part, one end of the sliding part base material is cast together with the main body part using a die-casting method, and then Furthermore, a surface hardening material is overlay-welded to the sliding surface provided at the other end of the sliding portion base material.

[Effects of the Invention] According to the present invention, the base material portion of the sliding part is formed of so-called air-hardened steel, which can be quenched and hardened simply by allowing it to cool naturally in the atmosphere after being heated. Since the surface hardening material is overlay welded to the sliding surface provided at one end of the base material, a hard overlay layer can be formed on the sliding surface to improve its wear resistance. Second, the base material can be quenched and hardened by raising the temperature of the base material by heat input during the overlay welding and then allowing it to cool naturally, thereby improving the rigidity of the base material.

[Example] Hereinafter, a case where an example of the present invention is applied to manufacturing a rocker arm used in a valve mechanism of a vehicle engine will be described with reference to the accompanying drawings.

As shown in FIG. 3, the rocker arm l according to this embodiment includes a main body 2 that is attached to a rocker arm shaft (not shown), and a cam l (not shown) of a camshaft that is attached to one end of the main body 2. (illustrated) and a sliding part base material 3 having a sliding surface 3a that comes into sliding contact.

The main body part 2 is formed by die-casting using a light alloy such as an aluminum alloy, and the sliding part base material 3 is formed in a mold when the main body part 2 is cast. Sliding part 3
It is disposed at a location corresponding to the mounting portion 3b and is fixed to the main body portion 2 by casting around the mounting portion 3b.

In this embodiment, the sliding part base material 3 is formed of so-called air-hardened steel, which can be quenched and hardened simply by allowing it to cool naturally in the atmosphere after being heated. A hardened surface material is overlaid and welded onto the sliding surface 3a of the sliding surface 3a.

Hereinafter, a method of manufacturing the rocker arm 1 according to this embodiment will be described.

(1) Formation of the sliding part base material First, for example, nickel chromium molybdenum W4 (SNC
M) Alternatively, a sliding part base material 3 as shown in FIG. 1 is formed using air-hardened steel such as alloy tool steel by forging or precision casting.

(2) Casting of the main body Next, the sliding part base material 3 is placed in a part corresponding to the sliding part of a mold for die-casting the main body 2, and molten aluminum alloy, for example, is poured into the mold. The mounting part 3b of the sliding part base material 3 is cast together with the main body part 2, and the sliding part base material 3 is fixed to the main body part 2.

After removing unnecessary parts such as sprues using a trimming device, cast burrs are removed by steel ball shot blasting.

(3) Overlay welding Next, the main body part 2 is fixed to a welding jig, and the sliding part base material 3 is
A surface hardening material is overlaid and welded onto the sliding surface 3a.

As the overlay method, gas overlay welding or plasma overlay welding can be applied, and as the surface hardening material, for example, C such as Stellite (registered trademark) can be used.
o-based alloys, Ni-based alloys such as Fullmonoy (registered trademark),
Alternatively, these alloys may contain Cr 3 C 2 , W C , N
b A material in which carbide such as C is dispersed can be used.

In the above manufacturing method, overlay welding is performed on the sliding portion 3a after the sliding portion base material 3 is cast into the main body portion 2, because overlay welding is performed on the sliding portion base material 3 alone. When performing welding, is the shape and dimensions stable? For this reason, when casting the main body part 2 and the hole, it may be difficult to set it in a certain part (gee) in the mold, or there may be a lot of casting burrs on the sliding surface 3a. This is because it may lead to problems such as generation errors.

A specific example of the above manufacturing method will be described below.

First, the sliding portion 3 was formed by forging using, for example, an alloy tool j148KD61 specified in JIS G 4404 as a material (see FIG. 1). The Vickers hardness of the sliding portion base material 3 in this state was approximately Hv400.

Next, the attachment part 3b of the sliding part base material 3 is set in a predetermined part of the die-casting mold of the rocker arm main body part 2, and a molten metal made by heating and melting aluminum alloy ADC1O to 690°C is then placed. The main body portion 2 was cast by pouring the metal into the cavity of the mold, and the mounting portion 3b of the sliding portion base material 3 was cast.

After unnecessary parts such as 40 were cut and removed, cast burrs were removed by John Doblasting to obtain the rocker arm l shown in FIG. 2.

Next, the main body part 2 is fixed in a vise, and the sliding part 3a of the sliding part 3 is coated with Crack: 15% by weight, B;
Ni-based alloy powder consisting of 4% by weight, 5% by weight of Sl, 17% by weight of Cr, the remainder being substantially Ni, and having an average grain size of 80μ was deposited by plasma deposition welding.

The overlay welding conditions were as follows.

, current/50A ・Voltage: 30V ・Welding speed: 500 mm/min.

・Powder feeding amount: to g/min.

When we investigated the Vickers hardness (H) of the sliding part base material 3 of the rocker arm l (see Figure 3) obtained as described above and the built-up layer 4 on the surface of the base material, we found that Material 3 is I
(V560, Hv770 for the build-up layer 4, which made it possible to obtain high hardness for the sliding part and to improve the hardness of the base material 3.

In addition, in order to check the bonding state between the sliding part base material 3 and the built-up layer 4, a gold-metal microscope photograph (magnification: 1
As shown in FIG. 4, no harmful cavities or the like were observed in the joint, confirming that the joint was in good condition.

Furthermore, the same material as in the above example (alloy tool steel 5KD61)
When the base material of the sliding part was formed by casting, the bonding condition between the base material and the built-up layer was investigated. I was able to confirm that

In addition, in Figures 4 and 5 of ``2'', the white part of the build-up layer is a matrix whose main component is Ni, and the black part is carbide (CR3CT).

As described above, according to this embodiment, the sliding part base material 3 is formed of air-hardened steel, and the sliding part 3a provided at one end of the sliding part base material 3 is coated with a surface hardening material. Since overlay welding is performed, it is possible to form a hard overlay layer 4 on the sliding portion 3a to improve its wear resistance, and the heat input during overlay welding can reduce the sliding portion. By heating the base material 3 to raise its temperature and then allowing it to cool naturally, the base material 3 of the sliding part can be quenched and hardened, and the rigidity of the base material 3 can be improved.

Incidentally, the above embodiment was applied to the manufacture of rocker arms used in the purchase of valve train for vehicle engines.
It goes without saying that the present invention can be applied not only to the above-mentioned rocker arm but also to the manufacture of other moving members in which a sliding portion is provided in a portion thereof.

[Brief explanation of the drawing]

The drawings are for detailed explanation of the present invention.
FIG. 1 is a front view of the sliding part base material, FIGS. 2 and 3 are front explanatory views of the rocker arm, partially shown in cross section, before and after overlay welding, respectively. The figure shows a micrograph at 100x magnification of the metal structure of the joint between the base material of the sliding part formed by forging and the overlay layer, and Figure 5 shows the base material of the sliding part formed by casting and the overlay layer. Magnification of the metal structure of the joint: 100
This is a photomicrograph magnified. l...Rocker arm, 2...Main body part, 3...Sliding part base material, 3a...Sliding surface, 3b...Mounting part, 4...Build-up layer.

Claims (1)

[Claims] (1) A sliding part base material provided with a sliding part and a main body part holding the sliding part base material, and air is applied to a part corresponding to the sliding part of a mold for casting the main body part. A sliding part base material formed of hardened steel is arranged, one end of the sliding part base material is cast together with the main body part by a die-casting method, and then the other end of the sliding part base material is provided. A method of manufacturing a sliding member, comprising overlaying and welding a hardened surface material onto the sliding surface.