JPH05106061A - Method for modifying surface by friction coating - Google Patents

Abstract

PURPOSE:To execute good friction coating by a material hard to work at a high temp. CONSTITUTION:A doughnut-shaped induction coil 14 is arranged close to a coating material 10 hard to work at a high temp. The lower of the coating material 10 is pressed on the surface of a base material 12, and, while it is pressed on the surface in contact therewith by a thrust P, the above coating material 10 is rotated. Furthermore, the coating material 10 is moved parallel to the base material 12. Then, the above induction coil 14 is energized, by which induction heating and frictional heat are given to the coating material 10, the part in contact with the base material 12 is easily melted and softened and coating of required film thickness is applied to the surface of the above base material 12.

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 providing a good friction coating on a metal substrate even when the coating material is made of a material which is difficult to work at high temperature.

[0002]

2. Description of the Related Art The blade portion of a high speed cutting tool, the claw portion of a bucket for construction machinery, and the bending portion of a forming roll are required to have a high degree of durability. Coatings are generally applied. This coating is a type of modification treatment that imparts properties such as wear resistance, rust prevention, and corrosion resistance to the surfaces of tools and machine parts that use, for example, high speed steel or forging steel as a base material. In order to carry out the coating, various metal materials for coating 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, laser irradiation, etc. A method of applying a coating to the surface of a base material by melting is used.

However, in the high-speed steel and the forging die steel as the base material, hard particles are present in a dispersed state, and huge carbides are 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 gas welding described above, the metal structure (crystal grains) near the surface of the base material becomes coarse and softens. .. In this case, when mechanical stress is repeatedly applied to the product after the surface modification treatment, there is a big defect that the coarsened structure part is peeled off or hollowed out, resulting in a decrease in strength. In particular, the quenching effect is lost in the base material after the heat treatment for quenching, such as the blade portion of the tool.

Therefore, as a coating means capable of preventing the coarsening of crystal grains in the metal structure, a method utilizing frictional heat has been proposed and put to practical use. this is,
A desired coating material is pressed against the surface of the base material, and ultrasonic vibration, mechanical vibration by an electromagnetic coil, or the like is applied to the coating material, and relative sliding or rotation motion is applied between the two. There is. As a result, frictional heat is generated between the surface of the base material and the coating material, the coating material is softened by heating, and either of them is relatively moved to coat the surface of the base material in layers. Is a "surface modification method by friction coating". According to this surface modification method, since plastic working at a high temperature is applied to the surface of the base material and the coating material, coarsening of crystal grains occurs unlike the above-mentioned melting method such as gas welding. There is no advantage, and there is an advantage of making the particles finer. Therefore, even if the substrate has been subjected to heat treatment such as quenching,
The friction coating does not weaken the metal structure.

[0005]

By the way, in carrying out the above-mentioned friction coating method, a material which is difficult to work at high temperature such as stellite (alloy for surface hardening overlay of registered trademark CoCrA) is used as a coating material. Then, the disadvantage that a good friction coating is not provided is pointed out. That is, the friction coating method is shown in FIG.
As shown in (1), the lower end of the cylindrical coating material 10 is pressed against the surface of the base material 12 such as high-speed steel, and the coating material 10 is rotated while being pressed against it with the 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, even if the coating operation is performed, the coating material does not melt and soften due to frictional heat. Therefore, as shown in (2) of FIG.
The surface layer 2 has a serious drawback that it is only scraped off by friction with the coating material 10 and that the desired surface modification by friction coating is not performed at all.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve the above-mentioned drawbacks inherent in the prior art, and it is proposed to carry out a surface modification method by friction coating. It is an object of the present invention to provide a surface modification method capable of providing a good friction coating on a metal substrate even when the coating material used for is made of a material that is difficult to work at high temperature.

[0007]

SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems and preferably achieve an intended purpose, the present invention provides a coating material made of a dissimilar metal material on a surface of a metal base material while being frictionally pressure-bonded to each other. In the surface modification method in which the coating material is moved to apply a coating of a dissimilar metal material to the surface, when the coating material is made of a high temperature difficult-to-process material, the friction welding is performed while supplementarily heating the coating material. It is characterized by applying.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a surface modification method by friction coating according to the present invention will be described with reference to the accompanying drawings with reference to preferred embodiments. FIG. 1 is a schematic configuration diagram of an apparatus capable of suitably carrying out the method according to the present invention, in which the lower end portion of a vertically arranged coating material 10 is pressed against the surface of a required base material 12 and pressed with a thrust P. At the same time, the coating material 10 is rotated. Further, the coating material 10 is configured to horizontally move in the arrow direction with respect to the base material 12. The coating material 10 may have a circular cross section, a rectangular cross section, or another polygonal shape. In the basic configuration for carrying out such a friction coating method, it is assumed that a high temperature difficult-to-process material such as Stellite (registered trademark) described above is used as the coating material 10. In this case, a doughnut-shaped high-frequency induction heating coil 14 (hereinafter referred to as “induction coil”) is placed in the vicinity of the coating material 10 while maintaining a required annular gap, and the induction coil 14 is attached under the required conditions. Energize. That is, the induction coil 14 and the metallic coating material 10
An electromagnetic induction action works between the coating material 10 and
Is induction heated. Since this is originally a friction coating method, the coating material 10 causes frictional heat generation by contact rotation with the base material 12. Therefore, the induction heating due to the arrangement of the induction coil 14 has a meaning as auxiliary heating for the coating material 10.

As described above, by supplementarily heating the high temperature difficult-to-process coating material 10 under the action of electromagnetic induction,
The coating material 10 is given induction heating in addition to the original frictional heat. Therefore, the coating material 10
Has a large temperature difference with the base material 12, and the portion of the coating material 10 in contact with the base material 12 is easily melted and softened, and is gradually moved horizontally. Therefore, the surface of the base material 12 is coated with a required film thickness. Therefore, the base material 12 is provided with the 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 by friction coating according to the present invention was carried out under the following conditions. Coating material: Stellite (registered trademark) made of CoCrA Base material: Free-cutting stainless steel (SUS304) Thrust P: 9 tons Rotation speed: 2000 RPM Induction heating temperature: 800 to 1100 ° C. , Coating layer 16 with required film thickness
Was formed. The film 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 is moved horizontally with respect to the base material 12. Although Stellite (registered trademark) is used as the coating material 10 in the embodiment, a refractory metal such as molybdenum (Mo), tungsten (W), niobium (Nb) or a composite material containing these may also be used. Good. Further, the atmosphere may be not only the air but also an inert gas such as Ar.

FIG. 2 shows another structural example in which the method of the present invention can be carried out. The thrust force on the coating material 10 is given by the weight W having a required weight. Further, the vibration applied to the coating material 10 is the ultrasonic horn 1.
8 and 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, the electric heater 20 is externally fitted to the coating material 10 with a required annular gap. Therefore, when performing the friction coating method, the heater 2
When the electric current is applied to 0, the coating material 10 is applied to the heater 2
Radiant heat from 0 leads to auxiliary heating. Figure 3
As shown in, 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. Of course, it is okay.

FIG. 4 shows still another structural example in which the method of the present invention can be carried out. A required voltage is applied between the coating material 10 and the base material 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
The above-mentioned energization causes counter heat generation. In any of these FIGS. 2 to 4, in addition to the original frictional heat, the coating material 10 is given auxiliary heat such as radiant heat or resistance heat. Therefore, the portion of the coating material 10 that is in contact with the base material 12 is easily melted and softened, and the coating layer 16 is applied to the surface of the base material 12 with a required film thickness.

As shown in FIG. 5, the coating material 1
0, high temperature difficult-to-process material 10 having two different characteristics
If the vertically bonded a and 10b are moved horizontally with sliding friction, the base material 1
Two coating layers 16a and 16b are formed on the surface of No. 2. This is suitably used, 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-to-process material 1
Of course, the deformation resistances of 0a and 10b need to be different from each other.

[0014]

As described above, according to the surface modification method by 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 work at high temperature, the coating material is induced. By performing auxiliary heating by heating, radiant heat or other resistance heat generation, friction coating of high temperature difficult-to-process materials, which was difficult in the past, is preferably carried out without causing coarsening of the structure of the base material or surface scraping. There are great benefits that can be done.

[Brief description of drawings]

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

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

FIG. 3 is a schematic diagram showing a modified example of the configuration shown in FIG.

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

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

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

[Explanation of symbols]

 10 coating material 12 base material 14 high frequency induction heating coil 16 coating layer

Claims (4)

[Claims] 1. A coating material made of a dissimilar metal material is frictionally welded to a surface of a metal base material and relatively moved,
In the surface modification method in which the surface is coated with a different metal material, when the coating material is made of a material that is difficult to work at high temperature, the friction welding is performed while supplementarily heating the coating material. A surface modification method using a friction coating. 2. The method for surface modification by friction coating according to claim 1, wherein the auxiliary heating for the coating material is given as induction heating generated by an induction coil arranged in the vicinity of the coating material. 3. The surface modification method by friction coating according to claim 1, wherein the auxiliary heating for the coating material is given as radiant heat by an electric heater arranged in the vicinity of the coating material. 4. The surface modification method by friction coating according to claim 1, wherein the auxiliary heating for the coating material is given as resistance heat generation by energization between the metal base material and the coating material.