JPH03107470A - Production of sliding member - Google Patents

Abstract

PURPOSE:To obtain the member having required sliding and strength characteristics in the formation of a surface hardening layer on a base material by remelting or buildup welding by quenching the remelted part or weld zone with a liquefied inert gas. CONSTITUTION:The surface of a base material is remelted or buildup welding is applied on the surface to form a surface hardening layer, and a sliding member is produced. In this method, buildup welding is applied on the surface of the base material 1, and the weld zone 2 is quenched immediately after welding by blowing a liquefied inert gas supplied from a nozzle 5 through a hose 4. By this method, the structure of the remelted part or weld zone is refined, a carbide is hardly grown or graphite crystallized, a surface hardening layer having high hardness and an excellent sliding characteristic is obtained, and consequently an excellent sliding member is obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a sliding member, and particularly to a method for manufacturing a sliding member that has excellent sliding properties and strength even under severe usage conditions such as high temperature and high surface pressure in high-output engines. The present invention relates to a method for manufacturing a sliding member that exhibits the following characteristics.

(Prior Art) For example, the seal mechanism of a rotary engine includes a side seal corresponding to the pressure ring of a reciprocating engine, an apex seal for maintaining airtightness between adjacent working chambers, and a joint between these side seals and the apex seal. Consists of corner seals to make it airtight.

All of these seals are supported on the rotor and slide along the inner wall surface of the housing as the rotor rotates.

Conventionally, these sliding members have generally been manufactured from a cast iron base material, and the sliding portion is remelted using a high-density energy source (e.g., electron beam, laser, plasma, arc, etc.) or It was manufactured by overlaying the sliding part by overlay welding, etc., and then hardening it (Japanese Patent Application Laid-open No. 197701/1984, etc.).

At this time, the cooling rate after remelting or overlay welding has a great effect on the quality of the isthmus layer.

In other words, if cooling is slow, carbides may grow in the remelted or overlay welded areas due to the large amount of carbon present in the cast iron base material, or the carbides may decompose to form graphite. Phenomena such as this occur.

When such a phenomenon occurs, the sliding properties and strength properties are inferior to those that have been well cooled, making it impossible to obtain a high-quality sealing material.

Conventionally, in order to achieve good cooling, the base material is held between cooling metals, and the above-mentioned remelting or overlay welding is performed while indirectly cooling the sliding parts to be processed by cooling the base material. It was done.

(Problems to be Solved by the Invention) However, the above-described method of cooling the base material by clamping it between chillers has the following problems.

(1) Since the chiller clamps the lower part of the base material and cools the clamped part, the upper part of the base material that is not clamped by the chiller is insufficiently cooled.

(2) When the base material becomes large, as in (1), there is a portion that is not clamped by the cooling metals, and this portion becomes insufficiently cooled.

(3) When the base material is in the form of a strip, such as an apex seal of a rotary engine, shrinkage occurs in the remelted or overlay welded portion due to the high-density energy described above, and the base material is deformed into a concave shape. As a result, the substrate may become detached from the chiller, resulting in insufficient cooling of the detached portion.

If the cooling is insufficient as described in (1) to (3) above, as mentioned above, coarsening of carbides and crystallization of graphite will occur.
The wear resistance and strength required for sliding members are significantly reduced. In particular, there is a concern that the tip of an apex seal for a rotary engine may break.

The present invention has been made in view of the above points, and its purpose is to provide a sliding member that has both the sliding characteristics and strength characteristics required for sliding members of high-output engines such as rotary engines. The purpose is to propose a method for manufacturing parts.

(Means for Solving the Problems) In order to achieve the above object, the method for manufacturing a sliding member according to the present invention remelts the surface of the base material or deposits a hardened surface layer on the surface of the base material. The method for manufacturing a sliding member is characterized in that the re-melting part or the overlay welding part is rapidly cooled with liquefied inert gas immediately after the remelting or overlay welding.

(Function) Generally, in remelting or overlay welding of the surface of a base material, the remelted portion or overlay weld of the base H is likely to be oxidized due to the high temperatures caused by these treatments.

Therefore, N2. Ar.

The above-mentioned treatment is performed while inert gas such as He is ejected to shield the remelted portion from an oxidizing atmosphere such as air.

Since this inert gas is used to simply shield from the oxidizing atmosphere as described above, there is no need to consider temperature at all, and gas at room temperature is generally used.

The method according to the present invention differs from the method in which inert gas is jetted to the treated part to shield the oxidizing atmosphere, and the method of the present invention sprays liquefied inert gas directly to the remelted part or overlay weld part after treatment. This remelted portion is rapidly cooled.

That is, liquefied inert gas is a cooled and condensed inert gas, and is generally a cryogenic liquid.

Therefore, the temperature of the treated area to which the liquefied inert gas is blown drops rapidly.

In the method according to the present invention, the above-mentioned cryogenic liquefied inert gas is directly sprayed onto the high-temperature remelting or overlay welding area immediately after the surface of the base material has been remelted or overlay welded using high-density energy. Then, this re-melted part etc. is rapidly cooled.

Through this rapid cooling, the structure of the remelted area becomes finer, and a hardened surface layer with extremely little carbide growth and graphite crystallization, high hardness, and excellent sliding properties can be obtained, resulting in a good surface hardening layer. A sliding member can be manufactured.

(Embodiments) Preferred embodiments of the present invention will be described below with reference to the drawings.

The shape shown in the front view of FIG. 2 (A) and the side view showing only one side of the cooling metal 10 of FIG. Fe-
Overlay material 2 of Mo-C type or alloy cast iron (acicular cast iron) type was supplied in powder form from a plasma torch 3 and overlay welding was performed.

Surface overlay welding conditions table Composition of overlay material The chiller 10 shown in FIGS. 1 can be held in a downwardly inclined manner, and a cooling water passage 11 is formed directly below the base material 1.

Note that instead of the chiller 10 shown in FIGS. 2(A) and 2(B) having a flat upper surface and slanting grooves, a chiller 10a having the structure shown in FIG. 3 may be used.

The upper surface 10b of the chiller 10a shown in FIG.
As in FIG. 2(A), the base material 1 is clamped deeper and deeper in the welding direction.

When the chilled metals 10.10a having the above configuration are used, even if the base material 1 is deformed by high-density energy during overlay welding, the base material 1 will not come off from the chilled metals 10, 10a. In this way, the base material 1 can be prevented from coming off the chiller 10.10a, so the base material 1 can be sufficiently cooled.

Then, as shown in FIG. 1, liquefied helium gas supplied from the gas supply source to the gas nozzle 5 via the hose 4 is sprayed onto the overlay welding part 2 immediately after overlay welding under the condition of 50β/1n. Immediately after spraying, the surface temperature of the overlay welded part 2 was measured.

Also, from the sliding member obtained in this way, 2X 36
A test piece was cut into a rectangular shape with dimensions of 3 mm x 3 mm, and a transverse bending test was performed by three-point bending with a span of 30+++ m using an autograph.

The above results were as shown in Table 3.

For comparison, overlay welding was performed on the surface of the base material in the same manner and under the same conditions as above, except that liquefied helium gas was not sprayed, and the surface temperature of the overlay weld immediately after welding was measured. A bending test similar to that was conducted.

The results are also shown in Table 3.

FIG. 4 shows micrographs (1000x magnification) of the overlay welded portion 2 of the sliding member obtained by the method according to the present invention obtained as described above and the overlaid welded portion of the sliding member according to the comparative example. (A
) and (B).

FIG. 4(A) shows an overlay welded portion 2 of a sliding member according to the present invention, and FIG. 4(B) shows an overlaid welded portion of a sliding member of a comparative example.

As is clear from the figures (A) and (B), compared to the build-up weld part 2 of the sliding member according to the present invention, the build-up weld part of the sliding member of the comparative example is made of carbide (dark gray). The growth is remarkable, and it can be seen that the carbides are connected to each other.

Furthermore, as is clear from Table 3, there is a difference of about 200° C. in the surface temperature of the overlay welded portion 2 between the method according to the present invention and the comparative example.

In the above example, helium was used as the liquefied inert gas, but the same effect as above can be obtained even when argon or nitrogen is used.

Reference Example Using chiller 10.10a with the configuration shown in Figures 2 (A), (B) or Figure 3, the procedure and conditions were the same as in the example (however, liquefied helium gas was not sprayed). In , overlay welding of alloy cast iron (acicular cast iron) type or 30Cr iron type overlay material having the composition shown in the example was applied to the surface of the base material 1 similar to that in the example.

For comparison, overlay welding was performed using a commonly used chilled metal in the same manner and under the same conditions as above.

Regarding the above-mentioned double overlay welding examples, the amount of deformation, amount of graphite crystallization, and bending strength of the base material 1 were evaluated.

The results are shown in Table 4.

2 The amount of deformation of the base material 1 in Table 4 is indicated by the dimension H of the portion shown in FIG. The amount of graphite produced was determined by polishing a cross section of the built-up layer and measuring the area of graphite appearing on the surface using an image analysis device. The bending strength was determined by a bending test conducted under the same conditions as in the example after strain relief annealing treatment (550°C x 2.5 hours - furnace cooling) was performed on the final built-up part of the built-up layer. Shown in the results.

As is clear from Table 4, the reference example using the chilled metals 10, 10a having the configuration shown in FIGS. 2(A), (B) or 3 has a higher Good results were shown in terms of the amount of deformation of the base material 1, the amount of graphite crystallization, and the bending strength.

In addition, in a comparative example using a conventional chiller, the base material came off the chiller, and cooling during solidification of the overlay weld became slow. As a result, it can be inferred from Table 4 that carbides tend to grow and graphite also tends to crystallize, resulting in a decrease in strength.

(Effects of the Invention) According to the method according to the present invention detailed above, the remelting part or the overlay welding part is rapidly cooled with cryogenic liquefied inert gas immediately after the remelting or overlay welding. It is possible to suppress the growth of carbides caused by carbon in the base material in the fusion zone or overlay weld zone, and crystallization of graphite due to the decomposition of carbides does not occur. Therefore, a sliding member having excellent sliding properties, wear resistance, and strength properties can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of an apparatus for implementing the method according to the present invention, and FIGS. 2 (A) and (B) are diagrams showing the configuration of a chiller used in the apparatus of FIG. The same figure (A) is a front view,
Figure (B) is a side view showing only one side of the chilled metal.
The figure is a side view showing the configuration of a chilled metal that replaces the chilled metal shown in Figure 2, FIG. (B) is a micrograph showing the metal structure of the overlay welded part of the comparative example using the conventional method, and FIG. 5 is a diagram showing the procedure for measuring the amount of deformation of the base material in the reference example. 5 1...Base material 2... Overlay welding part

Claims (1)

[Claims] In a method for manufacturing a sliding member in which a hardened surface layer is formed by remelting the surface of the base material or by overlay welding on the surface of the base material,
A method for manufacturing a sliding member, characterized in that a remelted part or an overlay welded part is rapidly cooled with liquefied inert gas immediately after remelting or overlay welding.