JP2000033512A - Cemented carbide tool and surface treatment method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of a thermal spraying layer for preventing fretting of a shaft part of a cermet cemented carbide tool. SOLUTION: After a first covered layer 3 made of Co self-melting alloy is formed by thermal spraying in a part 1a to be gripped of a tool main body 1 made of cermet having Co as binder, a second covered layer 2 made of Mo or alumina is formed by thermal spraying thereon. The second covered layer 2 made of Mo or alumina prevents fretting of the part 1a to be gripped effectively when a tool is used. The close adhesion property of the first covered layer 3 and the tool main body 1 is ensured by mutual chemical bonding of Co. The close adhesion property of the first covered layer 3 and the second covered layer 2 is ensured by the anchor effect. Owing to this configuration, the close adhesion property of a surface covered layer is improved when compared with the case where Mo or alumina is thermally sprayed on the tool main body 1 directly to improve the service life of the tool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cermet carbide tool and a surface treatment method thereof, and more particularly to a surface treatment technique for preventing fretting of a gripped portion of a tool gripped by a tool holder.

[0002]

2. Description of the Related Art Conventionally, when machining a material that is difficult to cut, a cermet cemented carbide tool is widely used (in this specification, the term “cermet” refers to a high melting point material). WC-Co, which is used as a general term for what is obtained by sintering refractories such as carbides, nitrides, borides and the like with metals, and is called "cemented carbide" from historical background
System alloys and the like. ). For example, when processing a molding die, a cermet ball mill is used. When a ball mill is mounted on a machining center to perform machining, there is no particular problem when machining in the depth direction (Z direction). However, when machining in the X and Y directions, stress in the bending direction is applied to the tool. That is, since the radial stress of the tool shaft is applied, the ball mill vibrates minutely with respect to the tool holder, and fretting occurs on the shaft surface of the ball mill. As the fretting proceeds, pitching occurs, and the shaft portion of the ball mill is broken starting from the pitching.

[0003] In order to solve such a problem of tool breakage, it is necessary to prevent the occurrence of fretting, which is the root cause of breakage. As a countermeasure against fretting, the inventors of the present application have found that it is effective to spray Mo or alumina on the surface of the shaft of the tool, and see the Journal of the Society of Lubrication of Japan (Vol. 29, No. 10, 1984, 775). Pp. 778).

[0004]

According to the above method,
Fretting can be effectively suppressed.
However, since the bonding strength between the object to be sprayed and the sprayed layer is not sufficient, there is a problem that the sprayed layer is peeled off during use of the tool, and a sufficient improvement in tool life cannot be obtained.

[0005] The present invention has been made to solve the above-mentioned problems of the prior art, and has as its object to improve the life of the shaft of a cermet tool.

[0006]

In order to achieve the above object, the present invention provides a tool body made of a cermet using Ni as a binder, and a Ni self-fluxing alloy formed on a surface of a portion to be gripped of the tool body. A first coating layer made of Mo or alumina formed on the surface of the first coating layer.
Provided is a carbide tool having a coating layer.

Further, the present invention provides a tool body made of a cermet using Co as a binder, a first coating layer made of a Co self-fluxing alloy formed on a surface of a portion to be gripped of the tool body, and the first coating layer. And a second coating layer made of Mo or alumina formed on the surface of the layer.

Further, the present invention provides a tool body made of a cermet using Co as a binder, a first coating layer made of a stellite alloy formed on a surface of a gripped portion of the tool body, and a first coating layer made of a stellite alloy. And a second coating layer made of Mo or alumina formed on the surface.

Further, the present invention provides a surface treatment method for improving the durability of a gripped portion of a cemented carbide tool made of a cermet using Ni as a binder. There is provided a surface treatment method comprising: a step of forming a first coating layer by spraying; and a step of forming a second coating layer by spraying Mo or alumina on the first coating layer.

The present invention also relates to a surface treatment method for improving the durability of a gripped portion of a cemented carbide tool made of a cermet using Co as a binder. There is provided a surface treatment method comprising: a step of forming a first coating layer by spraying; and a step of forming a second coating layer by spraying Mo or alumina on the first coating layer.

The present invention also relates to a surface treatment method for improving the durability of a gripped portion of a cemented carbide tool made of a cermet using Co as a binder, wherein a stellite alloy is welded to the gripped portion of the cemented carbide tool. The present invention provides a surface treatment method comprising: a step of forming a first coating layer; and a step of spraying Mo or alumina on the first coating layer to form a second coating layer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the present invention will be described below.

As a result of the research by the present inventors, the low adhesion of the Mo or alumina sprayed layer to the cermet is as follows.
(1) Even if Mo or alumina of the cermet is sprayed, chemical bonding due to diffusion cannot be obtained between the two due to the composition (component elements) of both, and (2) the surface of the cermet is very hard. It has been found that this is due to the fact that the anchor effect caused by the thermal spray layer biting into the cermet surface cannot be obtained.

Based on the above conclusions, the inventors of the present invention have made intensive studies and found that between the cermet and the Mo sprayed layer or the alumina sprayed layer, (1) a composition chemically bonded to the cermet, and (2) Mo Alternatively, by providing an intermediate layer (first coating layer) that satisfies the condition that the hardness is at least lower than that of the cermet so that a sufficient anchor effect can be obtained when alumina is sprayed, a Mo sprayed layer or alumina sprayed on the cermet is provided. It was concluded that the problem of adhesion of the layer (second coating layer) could be solved.

Hereinafter, the configuration of the carbide tool according to the present invention will be described. In the following description, all percentages indicating compositions are% by weight, unless otherwise specified.

FIG. 1 is a view showing a sectional structure of a carbide tool according to the present invention. As shown in FIG. 1, the cemented carbide tool is a gripped portion 1a held by a tool holder in the tool body 1.
First coating layer (intermediate layer) made of Ni self-fluxing alloy, Co self-fluxing alloy, or stellite alloy formed on the surface of
3 and a second coating layer 2 formed by spraying Mo or alumina on the first coating layer 3.

The cemented carbide tool body 1 is formed of a cermet comprising a dispersed phase such as WC as a hard material and Ni or Co as a binder.

The intermediate layer 3 is made of a Ni alloy (when the binder is Ni) or a Co alloy (when the binder is C), which can chemically bond with Ni or Co which is a cermet binder.
o)).

The intermediate layer 3 is preferably formed by thermal spraying or welding. When using a Ni self-fluxing alloy or a Co self-fluxing alloy for the intermediate layer 3, thermal spraying is used. When using a stellite alloy for the intermediate layer 3, overlay welding is used.

As the intermediate layer 3, a Ni self-fluxing alloy or Co
By using self-fluxing alloy or stellite alloy,
The formation of holes in the intermediate layer 3 can be prevented. Also,
Ni self-fluxing alloy, Co self-fluxing alloy and stellite alloy
Since the hardness is lower than that of the cermet, that is, the tool body 1, adhesion to the second coating layer 3, that is, the sprayed Mo layer or the sprayed alumina layer can be secured by the anchor effect.

Since the intermediate layer 3 made of a Ni self-fluxing alloy, a Co self-fluxing alloy, or a stellite alloy has an appropriate hardness (about 25 to 40 HRC), it has a high density (including almost no voids). In addition to this, it is also possible to prevent the occurrence of cracks in the Mo sprayed layer 2 or the alumina sprayed layer 2 due to the deformation of the intermediate layer 3.

As the Ni self-fluxing alloy, for example, JIS
SFNi1, SFNi2, SF defined in H8303
Ni3, SFNi4 and SFNi5 can be used.

As the Co self-fluxing alloy, for example, J
SFCo1 and SFC specified in IS H8303
o2 can be used.

Further, as the stellite alloy, Stellite No. 11 (Cr: 28 to 32%, W: 18% or more,
C: 3.0% or less; Fe: 3.0% or less); 33 (Cr: 28 to 32%, W: 8% or more, C:
1.8% or less, Fe: 2.5% or less), Stellite N
o. 66 (Cr: 25 to 30%, W: 3% or more, C:
1.2% or less, Fe: 1.0% or less), Stellite N
o. 7 (Cr: 25 to 30%, W: 5% or more, C: 0.
4% or less, Ni: 8 to 12%, Fe: 1.0% or less),
Stellite D-2 (Cr: 18 to 22%, W: 13% or more, C: 0.2% or less, Ni: 8 to 12%, Fe: 1.
0% or less) and Stellite D-6 (Cr: 25 to 31)
%, W: 3% or more, C: 0.2% or less, Fe: 1.0%
The following can be used.

The carbide tool having the above configuration is manufactured as follows.

First, the outer peripheral portion of the gripped portion 1a of the tool body (carbide tool) 1 is removed by grinding a predetermined amount.

Thereafter, the tool body 1 is preheated to a predetermined temperature,
The first coating layer 3 is formed by spraying a Ni self-fluxing alloy or a Co self-fluxing alloy on the surface by thermal spraying or by overlay welding a stellite alloy. When a self-fluxing alloy is used, a remelting process is performed.

Next, the surface of the thermal spraying or overlay welding layer is removed by grinding or cutting until the thickness of the first coating layer 3 reaches a predetermined value.

Next, the tool body 1 is heated to a predetermined temperature,
Spraying Mo or alumina on the first coating layer 3,
The second coating layer 2 is formed.

Thereafter, the surface of the sprayed layer is ground so that the diameter of the gripped portion 1a is the same as the diameter of the portion of the tool body 1 other than the gripped portion 1a. Thus, a carbide tool according to the present invention is obtained.

[0031]

The present invention will be described in more detail with reference to the following examples.

[First Embodiment] The outer peripheral portion of a cermet (carbide alloy) (WC: 95%, Co: 5%) ball end mill having a diameter of 20 mm was removed by grinding 0.5 mm.
Thereafter, the ball end mill was preheated to 300 ° C., and a stellite alloy (Cr: 20%, W: 10%, Ni:
8%, Co: balance).

Next, the thickness of the overlay welding layer is 0.3 mm.
The surface of the build-up welding layer was removed by cutting until the thickness became. The surface hardness after cutting was HRC35.

Next, the tool was heated to 250 ° C., and after performing Mo spraying on the overlay welding layer, the surface of the sprayed layer was finished by grinding to a diameter of 20 mm.

The ball end mill having been subjected to the surface treatment as described above is mounted on a machining center, and the cutting depth is 5 m.
m, feed speed 600mm / f, spindle speed 30
After cutting at 00 rpm for 1000 hours, no fretting occurred on the shaft of the ball end mill, and no peeling of the sprayed layer was observed.

[Second Embodiment] The outer peripheral portion of a 20 mm diameter cermet (carbide alloy) (WC: 95%, Co: 5%) ball end mill was removed by 0.5 mm grinding.
Thereafter, the ball end mill was preheated to 300 ° C., and a stellite alloy (Cr: 18%, W: 6%, Ni: 1)
2%, Co: balance) was build-up welded.

Next, the thickness of the build-up welding layer is 0.3 mm.
The surface of the build-up welding layer was removed by cutting until the thickness became. The surface hardness after cutting was HRC30.

Next, the tool was heated to 300 ° C., and alumina spraying was performed on the build-up welded layer, and the surface of the sprayed layer was finished by grinding to a diameter of 20 mm.

The ball end mill having been subjected to the surface treatment as described above is mounted on a machining center, and the cutting depth is 5 m.
m, feed speed 600mm / f, spindle speed 30
The cutting process was performed for 1000 hours at 00 rpm, but there was no fretting on the shaft of the ball end mill.
No peeling of the sprayed layer was observed.

[0040]

As described above, according to the present invention,
The life of the cermet tool can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view along the axial direction showing a configuration of a carbide tool (ball end mill) according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tool main body 2 Second coating layer 3 First coating layer (intermediate layer)

Claims (6)

[Claims] 1. A tool body made of a cermet using Ni as a binder, a first coating layer made of a Ni self-fluxing alloy formed on a surface of a gripped portion of the tool body, and a surface of the first coating layer. And a second coating layer formed of Mo or alumina. 2. A tool body made of a cermet having Co as a binder, a first coating layer made of a Co self-fluxing alloy formed on a surface of a gripped portion of the tool body, and a surface of the first coating layer. And a second coating layer formed of Mo or alumina. 3. A tool body made of a cermet using Co as a binder, a first coating layer made of a stellite alloy formed on a surface of a portion to be gripped of the tool body, and formed on a surface of the first coating layer. And a second coating layer made of Mo or alumina. 4. A surface treatment method for improving the durability of a gripped portion of a cemented carbide tool made of a cermet using Ni as a binder, wherein a Ni self-fluxing alloy is sprayed on a gripped portion of the cemented carbide tool, First
A surface treatment method comprising: a step of forming a coating layer; and a step of spraying Mo or alumina on the first coating layer to form a second coating layer. 5. A surface treatment method for improving the durability of a gripped portion of a cemented carbide tool made of a cermet using Co as a binder, wherein a Co self-fluxing alloy is sprayed on a gripped portion of the cemented carbide tool, First
A surface treatment method comprising: a step of forming a coating layer; and a step of spraying Mo or alumina on the first coating layer to form a second coating layer. 6. A surface treatment method for improving the durability of a gripped portion of a cemented carbide tool made of a cermet using Co as a binder, wherein a stellite alloy is weld-welded on the gripped portion of the cemented carbide tool, A surface treatment method comprising: forming a first coating layer; and spraying Mo or alumina on the first coating layer to form a second coating layer.