JPS6112964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a composite sintered material having excellent toughness and heat and wear resistance, and which is suitable for use by being attached to the cutting edge of a cutting tip, especially when cutting difficult-to-cut materials. It concerns pieces.

Conventionally, high-hardness steel, Ni-based or Co
For cutting difficult-to-cut materials such as base superalloy, cubic boron nitride (hereinafter referred to as CBN) of equal wall thickness is used.
A cutting edge layer made of a sintered material based on
A cutting chip is used in which a composite sintered piece with an equal-thickness laminated structure consisting of a layer composite is attached to the cutting edge by brazing, etc., with the cutting edge layer of the CBN-based sintered material positioned at the top. has been done.

However, in the above-mentioned conventional composite sintered piece, the retaining layer constituting it is exposed on the flank when attached to the cutting edge of the cutting tip, and does not have sufficiently satisfactory toughness. Abnormally elongated grain growth of WC grains is observed at the interface between the holding layer and the cutting edge layer, and CBN is observed at the interface between both layers.
There are pores that cause the decomposition of
Since the interfacial bonding strength between the two layers is poor, there is a problem in that when it is subjected to cutting, it does not exhibit the desired satisfactory cutting characteristics.

From the above-mentioned viewpoint, the present inventors conducted research to solve the problems of the above-mentioned conventional composite sintered pieces for cutting edges of cutting chips. It is made of special steel that has good bondability with CBN-based sintered materials such as steel and alloy tool steel, and has high toughness.However, in this case, the part that becomes the flank when attached to the cutting edge of the cutting tip If the special steel is exposed on the flank surface, the heat and wear resistance of the flank surface during cutting will be significantly reduced. part of
By creating a laminated structure with uneven thickness consisting of a cutting edge layer of CBN-based sintered material, the resulting composite sintered piece has extremely high interfacial bonding strength between the cutting edge layer and the retaining layer, and has high toughness and heat resistance. They found that it has excellent abrasion resistance.

Therefore, the present invention has been made based on the above knowledge, and the composite sintered piece attached to the cutting edge of the cutting chip has a cutting edge layer made of a CBN-based sintered material and a special steel. This is a laminated structure with uneven thickness, consisting of a two-layer composite with a retaining layer, and the portion that becomes the flank and rake surface when attached to the cutting edge of a cutting tip is occupied by the cutting edge layer of CBN-based sintered material. It is characterized by having the following.

Next, the composite sintered piece of the present invention will be explained with reference to examples.

Example 1 Fe powder with an average particle size of 3.0 μm: 71.5%, 3.5%
μm Cr powder: 10%, 0.6 μm Mo powder: 5
%, 0.8 μm W powder: 10%, 5.0 μm V powder: 1%, and 0.3 μm carbon powder: 2.5%
From a mixed powder consisting of (more than 1% by weight), 1.0ton/
It has dimensions of 12 mmφ in diameter x 3.0 mm in thickness under a pressure of cm ² , and has a shape shown in the perspective view in Figure 1, that is, a center depth of 3.0 mm formed by cutting with the tip of the drill bit.
A compacted powder piece 1 for forming a retaining layer having a conical recess 1a of mm is prepared, this compacted powder piece 1 is charged into a cylindrical thin-walled container made of Zr, and the average particle diameter CBN powder with 1μm: 80% by volume, same 2μm
TaN powder: 20% by volume Mixed powder for forming a cutting edge layer: 60mg After charging and filling, the entire container was inserted into a normal ultra-high pressure and high temperature generator, pressure: 50kb, temperature: 1300 ℃, storage time: 60 minutes, then quenched and finally reached a temperature of 600℃.
The composite sintered piece material T of the present invention was manufactured by holding it for 30 minutes and applying a treatment to impart hardness to the retaining layer.

The resulting composite sintered piece material T of the present invention
has dimensions of 12 mmφ in diameter x 2.5 mm in thickness, and as shown in the longitudinal cross-sectional view in Fig. 2, the cutting edge layer A is made of CBN-based sintered material and high-speed steel (JIS/SKH-9
It consisted of an uneven thickness laminated composite with a retaining layer B (corresponding to the above).

In addition, for the purpose of comparison, the shape of the compacted powder piece 1' for forming the retaining layer was assumed to be a disk shape as shown in the perspective view in Fig. 3, and its dimensions were 12 mmφ x thickness: 2.0 mm.
Except for mm, the above-mentioned composite sintered piece material T of the present invention
Under the same manufacturing conditions as the manufacturing conditions of
The wall thickness of A′ is 0.5 mm, and the wall thickness of retaining layer B′ is 2.0 mm.
A comparative composite sintered piece material T′ was produced.

Furthermore, for the purpose of comparison, the composition of the mixed powder for forming the retention layer was the same as above, except that the composition was 94% by volume of WC powder with an average particle size of 1.5 μm and 6% by volume of Co powder with an average particle size of 1.5 μm. Under the same manufacturing conditions as the comparative composite sintered piece material T', the same cross-sectional structure as the comparative composite sintered piece material T' shown in FIG. 4, that is, the cutting edge layer of CBN-based sintered material A conventional composite sintered part with an equal thickness laminated structure consisting of a two-layer composite of A'' and a retaining layer B'' of WC-based cemented carbide, each having a uniform thickness of 0.5 mm and 2.0 mm. piece material
T″ was manufactured.

Next, the above-mentioned composite sintered piece material T of the present invention, comparative composite sintered piece material T', and conventional composite sintered piece material T'' were each equally divided into four pieces as shown in the perspective view of FIG. After dividing into the present invention composite sintered piece P, comparative composite sintered piece P', and conventional composite sintered piece P'', as shown in the plan view in FIG. 6, the planar dimensions are: 127mm□×Thickness: 4.8mm WC-based cemented carbide cutting tip (throw-away tip) H
In the case of the composite sintered piece P of the present invention, the flank face f and the rake face C are CBN-based sintered, as shown in a partial perspective view in FIG. occupied by the cutting edge layer A of the material, while for the comparative composite sintered piece P′ and the conventional composite sintered piece P″,
As shown in the same partial perspective view in FIG.
With the cutting edge layers A′ and A″ of CBN-based sintered material positioned at the top, solder is applied using silver solder, and this is then attached to a cutting tool.Then, workpiece material: carburized and hardened steel. (Rockwell hardness H _R C: 62), Cutting speed: 100m/min, Feed: 0.1mm/rev, Depth of cut:
A cutting test was conducted under the condition of 1.0 mm, and the cutting time until the flank wear width of the cutting tip reached 0.1 mm was measured.

As a result, the composite sintered piece P of the present invention required an extremely long time of 100 minutes to reach the predetermined amount of wear, whereas the comparative composite sintered piece P in which the retaining layer B' of high-hardness steel is exposed on the flank f Piece P' reached the specified wear amount in 30 minutes, and conventional composite sintered piece P'', which had the same structure but had a retaining layer B'' of WC-based cemented carbide exposed on the flank f, reached the specified wear amount in 40 minutes. It was hot.

Example 2 The distribution ratio of the mixed powder for forming the retention layer was 67.2% for Fe powder with an average particle size of 4.5 μm and 67.2% for Cr powder with an average particle size of 3.0 μm.
Powder: 18%, 0.6 μm Mo powder: 10%, 5.0
Under the same manufacturing conditions as the composite sintered piece P of the present invention in Example 1 above, except that the V powder of μm: 2% and the carbon powder of 0.3 μm: 2.8% (weight%) , produced the composite sintered piece of the present invention, which is composed of a two-layer composite of a cutting edge layer of CBN-based sintered material and a retaining layer of alloy tool steel (equivalent to JIS/SKD11), and has an uneven thickness laminated structure. did.

The resulting composite sintered piece of the present invention was attached to a cutting tip in the same manner as in Example 1, and this was further attached to a cutting tool to cut the workpiece material: carburized and hardened steel (hardness H _R C: 55). A cutting test was conducted under the conditions of cutting speed: 100 m/min, feed: 0.15 mm/rev, and depth of cut: 2 mm, and the cutting time until the flank wear width reached 0.3 mm was measured.

Further, cutting tests were also conducted on the comparative composite sintered piece P' produced in Example 1 and the conventional composite sintered piece P'' under the same conditions.

As a result, the composite sintered piece of the present invention reached the specified amount of wear due to normal wear after 24 minutes, whereas the comparative composite sintered piece P' reached the specified wear amount after 18 minutes, and the conventional composite sintered piece reached the specified amount of wear after 24 minutes.
P'' reached the specified wear amount in 15 minutes, and its cutting characteristics were poor.

As mentioned above, in the composite sintered piece of the present invention, the retaining layer is made of special steel that has significantly superior toughness compared to WC-based cemented carbide and high interfacial bonding strength with CBN-based sintered material, In addition, the cutting edge layer is made of a CBN-based sintered material, and when attached to the cutting edge of the cutting tip, the cutting edge layer has a laminated structure with uneven thickness that occupies the flank and rake surfaces, so it has excellent toughness. It has heat and wear resistance, so when it is attached to the cutting edge of a cutting chip and used for cutting difficult-to-cut materials, it exhibits extremely excellent cutting performance.

[Brief explanation of drawings]

FIGS. 1 and 3 are perspective views showing compacted powder pieces;
Figures 2 and 4 are longitudinal sectional views showing the composite sintered piece material, Figure 5 is a perspective view showing how the composite sintered piece material is divided, and Figure 6 is a cutting tip of the composite sintered piece. FIGS. 7 and 8 are partial perspective views showing how the cutting tip of the composite sintered piece is attached to the cutting edge. 1,1'...Powder compact piece, T...Composite sintered piece material of the present invention, T'...Comparative composite sintered piece material, T''...
...Conventional composite sintered piece material, A, A', A''... Cutting edge layer, B, B', B''... Holding layer, P... Composite sintered piece of the present invention, P'... Comparison Composite sintered piece, P″... Conventional composite sintered piece, H... Cutting tip, f... Flank surface, C... Rake face.

Claims (1)

[Claims] 1 A composite sintered piece that is attached to the cutting edge of a cutting tip, and this composite sintered piece has two layers: a cutting edge layer made of cubic boron nitride-based sintered material and a retaining layer made of special steel.
The uneven thickness laminated structure is composed of a layer composite, and the portions that become the flank and rake surfaces when attached to the cutting edge of the cutting tip are occupied by the cutting edge layer of the cubic boron nitride-based sintered material. A composite sintered piece for the cutting edge of a cutting tip, which is characterized by having: