JP3055260B2 - Surface modification method by friction coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface modification method capable of applying a good friction coating to a metal substrate even when the coating material is made of a material which is difficult to process at high temperatures.

[0002]

2. Description of the Related Art Blades of high-speed cutting tools, claws of buckets of construction machines, and other bent portions of forming rolls are required to have a high degree of durability. A coating is generally applied. This coating is a type of modification treatment that imparts properties such as wear resistance, rust prevention and corrosion resistance to the surface of tools and machine parts based on, for example, high-speed steel or forging die steel. In order to carry out the coating, various coating metal materials are applied to the surface of the substrate to be modified, and the metal material is subjected to gas welding, arc welding, plasma powder welding, electron beam welding, or other laser irradiation. Is applied to coat the surface of the base material by melting.

[0003] However, the high-speed steel and the forging die steel used as the base material have hard particles dispersed therein and have a large carbide precipitated as a structure. Therefore, in order to perform the coating for modification, when the surface of the base material is heated by means such as the gas welding described above, the metal structure (crystal grains) near the surface of the base material is coarsened and softened. . In this case, when a mechanical stress is repeatedly applied to the product after the surface modification treatment, the coarse tissue portion is peeled off or hollowed out, and there is a great disadvantage that the strength is reduced. In particular, the quenching effect is lost in a substrate that has been subjected to a quenching heat treatment, such as a blade portion of a tool.

Accordingly, a method utilizing frictional heat has been proposed as a coating means capable of preventing coarsening of crystal grains in a metal structure, and has been put to practical use. this is,
A required coating material is pressed against the surface of the base material, and the coating material is subjected to ultrasonic vibration, mechanical vibration by an electromagnetic coil, and the like, and a relative sliding or rotating motion is given between the two. I have. Thereby, frictional heat is generated between the surface of the base material and the coating material, and the coating material is heated and softened, and any one of them is relatively moved to be coated in a layer on the surface of the base material. Is a "method of surface modification by friction coating". According to this surface modification method, since the surface of the base material and the coating material are subjected to plastic working at a high temperature, unlike the above-described melting methods such as gas welding, coarsening of crystal grains occurs. There is no advantage, but rather an advantage of finer graining. Therefore, even if the substrate has been subjected to heat treatment such as quenching,
This friction coating does not weaken the metallographic structure.

[0005]

In carrying out the friction coating method described above, a material which is difficult to process at high temperatures such as Stellite (trademark CoCrA alloy for surface hardfacing) is used as a coating material. Then, it is pointed out that a good friction coating cannot be formed. That is, the friction coating method is shown in FIG.
As shown in (1), the lower end of the columnar coating material 10 is pressed against the surface of a base material 12 such as high-speed steel, and the coating material 10 is rotated while being pressed against with a thrust P. At this time, by moving the coating material 10 or the base material 12 relatively horizontally in the direction of the arrow, a part of the coating material 10 is coated on the surface of the base material 12 with a required film thickness. However, when the coating material 10 is the above-mentioned high-temperature difficult-to-process material, the coating material does not melt and soften due to frictional heat even if the coating operation is performed. Therefore, as shown in FIG.
The surface layer portion 2 has a serious disadvantage that it is only scraped off by friction with the coating material 10 and the desired surface modification by the friction coating is not performed at all.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned drawbacks inherent in the prior art, and has been proposed to solve the problem in a favorable manner. It is an object of the present invention to provide a surface modification method capable of applying a good friction coating to a metal substrate even when the coating material used for the coating is made of a material that is difficult to process at high temperatures.

[0007]

SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems and to achieve the intended object, the present invention provides a method in which a coating material made of a dissimilar metal material is relatively moved on a surface of a metal substrate while being friction-welded. Te a surface modification method as a coating of dissimilar metallic materials to the surface, characterized in that the pre-Symbol coating material applying the friction welding while heating auxiliary directly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for modifying a surface by a friction coating according to the present invention will be described with reference to the accompanying drawings by way of preferred embodiments. FIG. 1 is a schematic configuration diagram of an apparatus capable of suitably performing a method according to the present invention, in which a lower end portion of a vertically arranged coating material 10 is pressed against a surface of a required base material 12 and pressed with a thrust P. While rotating, the coating material 10 is rotated. Further, the coating material 10 is configured to move horizontally in the direction of the arrow with respect to the base material 12. The shape of the coating material 10 may be any of a circular cross section, a rectangular cross section, and other polygons. In the basic configuration for performing such a friction coating method, a high-temperature hard-to-process material such as Stellite (registered trademark) described above is used as the coating material 10. In this case, a donut-shaped high-frequency induction heating coil 14 (hereinafter referred to as an “induction coil”) is extrapolated close to the coating material 10 while maintaining a required annular gap, and the induction coil 14 is placed under the required conditions. Energize. That is, the induction coil 14 and the metal coating material 10
Between the coating material 10
Is heated by induction. In addition, since this is essentially a friction coating method, the coating material 10 generates frictional heat by contact rotation with the substrate 12. Therefore, induction heating by disposing the induction coil 14 has a meaning as auxiliary heating for the coating material 10.

As described above, the auxiliary heating of the coating material 10 which is difficult to process at a high temperature under the electromagnetic induction action enables
The coating material 10 is provided with induction heating in addition to the original frictional heat. Therefore, the coating material 10
Has a large temperature difference with the substrate 12, and the portion of the coating material 10 that is in contact with the substrate 12 is easily melt-softened and gradually moved horizontally. The surface of the substrate 12 is coated with a required film thickness. Therefore, the base material 12 is provided with useful properties of the coating material 10,
The desired surface modification is suitably achieved.

In the embodiment shown in FIG. 1, the surface modification method using the friction coating according to the present invention was carried out under the following conditions. Coating material: Stellite (registered trademark) made of CoCrA Substrate: Free-cutting stainless steel (SUS304) Thrust P: 9 tons Rotation speed: 2000 RPM Induction heating temperature: 800 to 1100 ° C. The coating layer 16 with the required film thickness
Was formed. The thickness of the coating layer 16 can be controlled in the range of 0.3 to 1.2 mm by adjusting the speed at which the coating material 10 moves horizontally with respect to the base material 12. In the embodiment, Stellite (registered trademark) is used as the coating material 10. However, a high melting point metal such as molybdenum (Mo), tungsten (W), or niobium (Nb), or a composite material containing any of these may be used. Good. Further, the atmosphere may be carried out not only in the air but also in an inert gas such as Ar.

FIG. 2 shows another configuration example in which the method of the present invention can be carried out. The thrust on the coating material 10 is given by a weight W having a required weight. The vibration to the coating material 10 is the ultrasonic horn 1
The coating material 10 is horizontally moved in the direction of the arrow with respect to the base material 12. In such a basic configuration, an electric heater 20 is externally inserted into the coating material 10 while maintaining a required annular gap. Therefore, when performing the friction coating method, the heater 2
0, the coating material 10
Radiation heat from 0 leads to auxiliary heating. FIG. 3
As shown in FIG. 5, the thrust P is applied to the coating material 10 without using the weight W, the side of the substrate 12 is rotated, and the base material 12 is horizontally moved with respect to the coating material 10. Needless to say, this may be done.

FIG. 4 shows still another configuration example in which the method of the present invention can be carried out. A required voltage is applied between a coating material 10 and a substrate 12. At this time, when the electric resistance value of the coating material 10 is sufficiently larger than the resistance value of the base material 12, the coating material 10
Is heated by the above-mentioned current flow. In each of the cases of FIGS. 2 to 4, the coating material 10 is provided with auxiliary heating such as radiant heat or resistance heat in addition to the original frictional heat. Therefore, the portion of the coating material 10 that is in contact with the substrate 12 is easily melt-softened, and the surface of the substrate 12 is coated with the coating layer 16 with a required thickness.

[0013] As shown in FIG.
0, high-temperature difficult-to-process material 10 having two different properties
a and 10b are vertically moved and horizontally moved while sliding friction is applied.
2, two coating layers 16a and 16b are formed on the surface of the second. This is suitably adopted, for example, when the surface of the base material 12 is modified with graphite or the like so that the surface of the base material 12 has a lubricating effect. However, high temperature difficult processing material 1
Needless to say, it is necessary to make the deformation resistances 0a and 10b different from each other.

[0014]

As described above, according to the surface modification method using the friction coating according to the present invention, when the friction coating is applied to the base material using the coating material which is difficult to process at a high temperature, the coating material is induced. By performing auxiliary heating by heating, radiant heat or other resistance heating, etc., friction coating of high-temperature difficult-to-process materials, which was conventionally difficult, can be suitably performed without causing coarsening of the structure of the substrate or surface shaving. There are significant advantages that can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for suitably performing a surface modification method using a friction coating according to the present invention.

FIG. 2 is a schematic view showing another configuration example in which a surface modification method using a friction coating according to the present invention can be performed.

FIG. 3 is a schematic diagram showing a modification of the configuration shown in FIG. 2;

FIG. 4 is a schematic view showing still another configuration example in which a surface modification method using a friction coating according to the present invention can be performed.

FIG. 5 is a schematic view when a high-temperature hard-to-process material having two different properties is used as a coating material.

FIG. 6 is a schematic diagram for explaining the inconvenience of using a high-temperature difficult-to-process material as a coating material when performing a surface modification method by friction coating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Coating material 12 Substrate 14 High frequency induction heating coil 16 Coating layer

Claims (5)

(57) [Claims] A coating material comprising a dissimilar metal material is relatively moved on a surface of a metal substrate while being friction-welded,
In the surface modification method as a coating of dissimilar metallic materials on the surface, a surface modification method according friction coating, characterized in that the pre-Symbol coating material applying the friction welding while heating auxiliary directly. 2. The coating material according to claim 1, wherein said coating material is hardly workable at high temperatures.
Surface modification by the friction coating according to claim 1
Quality way. 3. The friction of claim 1 or 2 , wherein the direct auxiliary heating of the coating material is provided as direct induction heating caused by an induction coil disposed proximate to the coating material. Surface modification method by coating. Wherein the auxiliary heating of the coating material is a surface reforming method according friction coating of a given claim 1 or 2, wherein the radiation heat by the electric heater disposed close to the coating material. 5. The auxiliary heating of the coating material, according to claim 1 is provided as a direct resistance heating by energization between said metal substrate and said coating material or
3. A method for surface modification by the friction coating according to 2 .