JP3412527B2 - Manufacturing method of indexable cutting insert with excellent chipping resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent chipping resistance, and is especially useful for high-speed cutting of Ni-base heat-resistant alloys and tungsten carbide-base cemented carbides (hereinafter simply referred to as cemented carbides). The present invention relates to a method for producing a throw-away cutting tip (hereinafter, simply referred to as a cutting tip) that exhibits excellent cutting performance for a long period of time without chipping (fine chipping).

[0002]

2. Description of the Related Art Conventionally, as shown in schematic perspective views of FIGS. 1 (a) and 1 (b), generally, the whole is composed of a high-purity boron nitride (hereinafter referred to as BN) sintered body. Cutting blade [Fig. 1
(A)] or a cutting edge piece composed of a high-purity BN sintered body cutting edge layer and a cemented carbide underlayer integrally sintered and joined thereto [(b) in FIG. 1]. Manufactured by using the ultra-high pressure sintering device of No. 1, and brazed with a brazing material such as Ag-based alloy or Cu-based alloy to the cutting edge piece attachment part of the chip body made of cemented carbide. The following cutting tips are widely known, and it is well known that these cutting tips are used for continuous cutting and intermittent cutting of Ni-base heat-resistant alloys and cemented carbides.

[0003]

On the other hand, in recent years, there has been a strong demand for labor saving and energy saving in the cutting work, and along with this, the cutting work tends to be speeded up. However, when this is used for high-speed cutting, chipping is likely to occur on the cutting edge, and due to this, the service life is reached in a relatively short time.

[0004]

Therefore, the present inventors have
From the above viewpoint, the entire cutting edge piece is made of a high-purity BN sintered body, or the cutting edge piece and a cutting edge layer of the high-purity BN sintered body are integrally sintered and joined together. Focusing on the above-mentioned conventional cutting tip composed of a hard alloy underlayer, a study was conducted to improve the chipping resistance of the cutting tip, and as a result, high-purity hexagon Crystalline BN powder was used, and when super-high pressure sintering was performed with a green compact of Al powder superposed on the upper face of the green compact or with the upper face covered with an Al foil, high Purity BN
Aluminum nitride (hereinafter referred to as AlN) and aluminum boride (hereinafter referred to as AlB ₂ ) formed by the reaction of BN and Al were crystallized from hexagonal to cubic on the upper surface portion of the sintered body. A sinter reaction layer having a distributed structure is formed on the BN substrate, and such a sinter reaction layer is brazed to a cutting edge piece formed on the upper surface (rake surface). The research results show that the cutting tip does not exhibit chipping on the cutting edge even when it is used for high-speed cutting of a Ni-base heat-resistant alloy or cemented carbide, and exhibits excellent cutting performance.

The present invention has been made on the basis of the above research results. (A) A state in which an Al powder compact is superposed on the upper surface of a high-purity hexagonal BN powder compact, or the upper surface thereof. Was covered with Al foil, charged into an ultra-high pressure sintering apparatus, sintered, and measured on the upper surface portion with a scanning electron microscope.
Forming a cutting piece material in which a sintering reaction layer having a structure in which AlN and AlB ₂ are dispersed and distributed is formed on a base material of BN crystal-transformed from hexagonal crystal to cubic crystal over a depth of 1 to 0.5 mm. Then, this is machined to form a cutting edge piece, and this cutting edge piece is brazed to the cutting edge piece attachment part of the tip body made of cemented carbide, which is a cutting tip with excellent chipping resistance. Production method. (B) A high-purity hexagonal BN powder compact for forming a cutting edge layer is laid on a green compact for forming an underlayer composed of a cemented carbide,
Further, with the upper surface of this high-purity hexagonal BN powder green compact being overlaid with the Al powder green compact or being covered with the Al foil, it was placed in an ultra-high pressure sintering apparatus and sintered. hand,
AlN and AlB ₂ are dispersed on the surface of the upper surface of the BN matrix which has been transformed from hexagonal crystal to cubic crystal over a depth of 0.1 to 0.5 mm from the surface as measured by a scanning electron microscope. A cutting edge layer formed with a sintered reaction layer having a texture,
A cutting blade material composed of a cemented carbide underlayer integrally sintered with this was formed, and this was machined into a cutting blade piece, and this cutting blade piece was composed of cemented carbide. A method of manufacturing a cutting tip with excellent chipping resistance, which is brazed to the cutting edge piece mounting portion of the tip body. The method is characterized by the above-mentioned manufacturing methods of the cutting tip (a) and (b).

In the method of manufacturing a cutting tip of the present invention, the depth of the sintering reaction layer formed on the surface portion of the rake face (upper face) of the cutting edge piece constituting the cutting tip is mainly determined by the super high pressure firing. It is controlled by adjusting the binding conditions. In this case, if the depth is less than 0.1 mm, desired excellent chipping resistance cannot be secured, while if the depth exceeds 0.5 mm, This sintering reaction layer reaches the flank (side surface) of the cutting edge piece, and the wear resistance of the flank suddenly decreases, so the depth thereof is 0.1 to 0.5 m.
It was defined as m.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a method for manufacturing a cutting tip according to the present invention will be specifically described with reference to Examples. First, for the purpose of manufacturing the chip body, as a raw material powder, each has a predetermined average particle size within the range of 0.5 to 3 μm, W
C powder, TaC powder, and Co powder were used, and these raw material powders were Co: 5%, TaC: 5%, W by weight%.
C: compounded to the compounding composition consisting of the rest, 72 in a ball mill
After wet-mixing for a period of time and drying, press-molding into a green compact having a predetermined shape at a pressure of 1 ton / cm ² , and holding the green compact at 1400 ° C. for 1 hour in a vacuum of 1 × 10 ⁻³ torr. CIS standard TNGA33 by being sintered under the conditions
A chip body having the shape 2 (thickness: 3.18 mm × length of one side: equilateral triangle of 16 mm) was manufactured.

Further, for the purpose of producing a cutting edge piece, a high-purity hexagonal BN powder having an average particle size of 5 μm and a purity of 99.95% was used as a raw material powder, and 3 ton /
Pressed into a high-purity hexagonal BN powder compact having a size of diameter: 20 mm × thickness: 2 mm at a pressure of cm ² , and further as a raw material powder, average particle diameter: 30 μm and purity:
High purity Al powder with 99.7% was used and
At a pressure of on / cm ² , diameter: 20 mm × thickness: 0.1 m
It is press-formed into Al powder green compacts having a size of m, and these green powders are formed into an ordinary powder in the state where the Al powder green compact is superposed on the upper surface of the high-purity hexagonal BN powder green compact. Charged into a belt type ultra-high pressure sintering machine, pressure: 7 GPa, temperature:
Sintering was carried out under the conditions of 2200 ° C. and a holding time of 30 minutes, and the upper surface portion was measured with a scanning electron microscope to give a value of 0.
A sintering reaction layer having a structure in which AlN and AlB ₂ are dispersed and distributed is formed on a base material of BN that has been crystal-transformed from hexagonal crystal to cubic crystal over a depth of 4 mm, and has a diameter of 20 mm.
× Thickness: 1.5mm cutting piece material is formed and machined using an ultrasonic cutter, and the side length is 5mm
Of the equilateral triangular shaped cutting blade, and this cutting blade is
And Ag-29.8% Cu-4.9% Ti-9.7% I.
Using an Ag-based brazing filler metal having a composition of n, 1 × 1 in a state of being pressurized by a hot press at a pressure of 1 kg / cm ^2.
A cutting tip A of the present invention was manufactured by carrying out the method of the present invention by brazing to the cutting edge piece attachment part of the above-mentioned tip body under the condition of holding at 950 ° C for 5 minutes in a vacuum of 0 ^-3 torr. For comparison purposes, the Al powder compact is not superposed with the high-purity hexagonal BN powder compact, that is, the high-pressure hexagonal BN is subjected to ultra-high pressure sintering.
A conventional cutting tip a was manufactured by performing the conventional method under the same conditions except that only the powder compact was used.

Further, the above-mentioned chip is used except that the above-mentioned high-purity hexagonal BN powder compact is used for forming the cutting edge layer and the dimension is 20 mm × thickness: 1.5 mm for forming the underlayer. Using the green compacts formed under the same conditions as the main body, the green compacts for forming the underlayer are laminated with the high-purity hexagonal BN powder green compacts, and the high-purity hexagonal BN powder is further added. The upper surface of the powder compact is 30 μm thick Al
With the foil covered, it was put into a normal belt type ultra-high pressure sintering machine, pressure: 7 GPa, temperature: 2200 ° C., holding time:
After sintering for 30 minutes, the surface of the upper surface was measured with a scanning electron microscope, and AlN was added to the base material of BN crystal-transformed from hexagonal to cubic over a depth of 0.3 mm from the surface. A
A sinter reaction layer having a structure in which 1B ₂ was dispersed and distributed was formed, and the thickness of the cutting edge layer: 0.7 mm × the thickness of the underlayer:
1.5 mm x diameter: A cutting piece material having a size of 20 mm is formed, and this is machined using an ultrasonic cutter to form an equilateral triangular cutting piece with a side length of 5 mm. The cutting blades were made of Ag-29.7% Cu-28.
Using an Ag-based alloy brazing filler metal having a composition of 1% Zn-2.0% Ni, in a state of being pressurized by a hot press at a pressure of 1 kg / cm ² , in a vacuum of 1 × 10 ⁻³ torr, 950 ° C.
The cutting tip B of the present invention was manufactured by carrying out the method of the present invention by brazing to the cutting edge piece attachment part of the above-mentioned tip body under the condition of holding for 5 minutes. Further, for the purpose of comparison, the upper surface of the high-purity hexagonal BN powder compact is not covered with the Al foil at the time of charging into the ultrahigh-pressure sintering apparatus, that is, the ultrahigh-pressure sintering is performed to form the cutting edge layer. High Purity Hexagonal BN
A conventional method was carried out under the same conditions except that the powder compact and the green compact for forming the underlayer were subjected to the conventional method to produce the conventional cutting tip b.

Next, regarding the cutting tips A and B of the present invention and the conventional cutting tips a and b obtained as a result, the work material: Rockwell hardness A scale: 84 having a hardness of 84: Co: 20% Cemented carbide round bar containing, cutting speed: 30 m / min. , Feed: 0.1 mm / rev. , Depth of cut: 0.1 mm, cutting time: 15 minutes, wet continuous high-speed cutting test of cemented carbide, and work material: Rockwell hardness C scale: Ni-based heat resistance with hardness of 45 Alloy with 4 equal intervals in the length direction Round bar with flutes, Cutting speed: 150 m / min. , Feed: 0.1 mm / rev. The incision: 0.3 mm, the cutting time: 20 minutes, the wet intermittent high-speed cutting test of the Ni-base heat-resistant alloy was performed, and the flank wear width of the cutting blade was measured. The results of these measurements are shown in the table below.

[0011]

[0012]

From the results shown in the above table, the cutting chips A and B of the present invention produced by the method of the present invention are both formed on the surface portion of the rake face (upper face) of the cutting blade pieces constituting the cutting chips. Due to the presence of the sintered reaction layer, even when high-speed cutting of hard-to-machine materials such as cemented carbide and Ni-based heat-resistant alloys, normal wear is exhibited without chipping of the cutting edge and excellent wear resistance is exhibited. Thus, it is clear that the conventional cutting tips a and b manufactured by the conventional method all reach the service life in a relatively short time due to the chipping generated on the cutting edge. As described above, according to the method of the present invention, cemented carbide or Ni
Not only cutting under normal conditions such as base heat resistant alloys, but also showing excellent chipping resistance even when cutting these work materials at high speed, cutting that exhibits excellent cutting performance for a long time It is possible to manufacture chips, which can contribute to labor saving and energy saving in cutting.

[Brief description of drawings]

1A and 1B are schematic perspective views of a cutting tip.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-182242 (JP, A) JP-A-61-77670 (JP, A) JP-A-61-141672 (JP, A) JP-A-61- 146763 (JP, A) JP 9-323203 (JP, A) JP 8-336705 (JP, A) JP 8-197308 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23B 27/14 C04B 35/583

Claims (2)

(57) [Claims] 1. A high-purity hexagonal boron nitride powder green compact is superposed with an Al powder green compact or is covered with an Al foil in an ultrahigh pressure sintering apparatus. Then
Sintered, on the upper surface part, measured by a scanning electron microscope, over a depth of 0.1 to 0.5 mm from the surface, to a substrate of boron nitride crystal transformed from hexagonal to cubic Aluminum nitride and aluminum boride Forms a cutting edge piece material on which a sintering reaction layer having a structure in which is dispersedly distributed is formed,
Excellent chipping resistance, characterized by being machined into a cutting edge piece and brazing this cutting edge piece to the cutting edge piece attachment part of the chip body made of tungsten carbide based cemented carbide. Method for manufacturing throw-away cutting tips. 2. A high-purity hexagonal boron nitride powder compact for forming a cutting edge layer is laid on a green compact for forming an underlayer composed of a tungsten carbide based cemented carbide, and the high-purity hexagonal hexagon The upper surface of the crystalline boron nitride powder compact was superposed with the Al powder compact or the upper surface of the powder compact was covered with an Al foil, charged into an ultra-high pressure sintering apparatus, and sintered to obtain the upper surface. The surface area is measured with a scanning electron microscope,
Aluminum nitride and aluminum boride were added to a boron nitride substrate which had been transformed from hexagonal crystal to cubic crystal over a depth of 0.5 mm. A cutting edge layer formed of a sintered reaction layer having a dispersed distribution structure and a tungsten carbide based cemented carbide underlayer integrally sintered and joined to form a cutting edge piece material, It has excellent chipping resistance, characterized by being machined into a cutting edge piece and brazing this cutting edge piece to the cutting edge piece attachment part of the chip body made of tungsten carbide based cemented carbide. Method of manufacturing throw-away cutting tips.