JPH09323203A - Throw-away cutting tip which excels in resistance against chipping - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throw-away cutting tip which excels in resistance against chipping by forming a Co infiltrated layer which is formed in an upper layer of a cutting edge member and in which Co which is combined phase formation component of a lower layer is infiltrated to predetermined depth from a boundary face between the upper layer and the lower layer. SOLUTION: A Co infiltrated layer in which Co which is combined phase formation component of a lower layer of WC basic cemented carbide which contains Co as combined phase formation component is infiltrated to depth of 150μm or more from a boundary face between an upper layer of cBN basic sintered material and the lower layer at the time of sintering of the upper layer is formed in a boundary face part between the upper layer and the lower layer. The reason why the depth of Co infiltration is 150μm or more is because desired and excellent resistance against chipping cannot be ensured if the depth is less than 150μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throwaway cutting tip which has excellent fracture resistance and therefore exhibits excellent performance over a long period of time even when used for intermittent cutting of cast iron, super alloy, etc. It is about.

[0002]

2. Description of the Related Art Conventionally, generally, for example, Japanese Patent Laid-Open No. 3-170.
No. 206 publication and as shown in a schematic perspective view in FIG. 3, an upper layer 1a of a cubic boron nitride (hereinafter referred to as cBN) based sintered material and a tungsten carbide (hereinafter referred to as WC) based cemented carbide. A throwaway cutting tip formed by brazing 3 a cutting edge member 1 made of a two-layer composite sintered body of an alloy lower layer 1b to a stepped notch formed in a corner portion of a support member 2 of WC-based cemented carbide. It has been known. It is also known that the above conventional throwaway cutting tip is used for continuous cutting of various cast irons and super alloys.

[0003]

On the other hand, in recent years, FA has been remarkably changed to cutting in recent years, and there is also a strong demand for labor saving. Accordingly, the cutting tool can be applied not only to continuous cutting but also to intermittent cutting. However, although the conventional slow-away cutting tip described above exhibits excellent cutting performance in continuous cutting, it is prone to chipping or chipping in the cutting edge in intermittent cutting, so it can be used in a relatively short time. The current situation is that it reaches the end of its life.

[0004]

Therefore, the inventors of the present invention have paid attention to the above-mentioned conventional throwaway cutting tip from the above viewpoints, and have conducted research to make it applicable to intermittent cutting. As a result, the cutting blade member of the conventional throwaway cutting tip generally has a lower layer of a sintered body and an upper layer of a pre-sintered body (in this case, the lower layer may be a green compact or a pre-sintered body, and the upper layer may be a powder). (Or it may be a green compact) and charged into an ultra-high pressure sintering apparatus, and the sintering condition shown in FIG. 2, that is, when the pressure is first raised to a sintering pressure of 4 to 5 GPa, is increased. After starting the temperature and maintaining the sintering pressure, the temperature is raised to a sintering temperature of 1250 to 1350 ° C., and the sintering pressure and the sintering temperature are maintained for a predetermined time and then cooled. Sintering conditions for starting pressure reduction from the binding pressure (below Conventional sintering conditions), but the sintering conditions are those shown in FIG. 1, that is, when the pressure is increased to an intermediate pressure of 2 to 2.5 GPa, the temperature rise is started and the intermediate temperature is increased. While maintaining pressure 1
After raising the temperature to an intermediate temperature of 000 to 1100 ° C. and holding at this intermediate pressure and the intermediate temperature for a predetermined time, only the pressure is increased again to increase the sintering pressure to 4 to 5 GPa, at which point the temperature is further increased. Then, the temperature is raised to a sintering temperature of 1250 to 1350 ° C., and the sintering pressure and the sintering temperature are maintained for a predetermined time and then cooled, and after the cooling is completed, the pressure reduction from the sintering pressure is started. When the above cutting blade member is manufactured under the conditions (hereinafter referred to as the sintering conditions of the present invention), in the cutting blade member manufactured under the above conventional sintering conditions, the binder phase formation of the WC-based cemented carbide forming the lower layer is formed. The infiltration depth of Co as a component (generally, the content of Co is 3 to 20% by weight) into the upper layer is extremely shallow, and the upper layer has a depth of 50 μm or less from the interface with the lower layer. Insoluble Co
The only thing that the infiltration layer was formed is that the cutting blade member produced under the sintering conditions of the present invention described above has a bonding phase that constitutes the lower layer while being maintained at the intermediate pressure and the intermediate temperature for a predetermined time. Since the infiltration of Co as a constituent into the upper layer is significantly promoted even when the content thereof is usually 3 to 20% by weight, the Co content in the upper layer is 150% from the interface with the lower layer.
Infiltrate over a depth of μm or more (In this case, from the viewpoint of wear resistance, Co should not infiltrate over 50% of the thickness of the upper layer, preferably over 30%) A cutting blade in which Co, which is a binder phase forming component of the WC-based cemented carbide forming the lower layer, is infiltrated into the upper layer of the cutting member over a depth of 150 μm or more from the interface with the lower layer. The member comes to have excellent fracture resistance due to the formation of the Co infiltration layer. Therefore, the resulting throwaway cutting tip requires high toughness as well as continuous cutting of cast iron or super alloy. We obtained the research results that even in the intermittent cutting, the cutting edge is not chipped or chipped and excellent cutting performance is exhibited for a long period of time.

The present invention was made based on the above research results, and is a two-layer composite of an upper layer of a cBN-based sintered material and a lower layer of a WC-based cemented carbide containing Co as a binder phase forming component. A throwaway cutting tip obtained by brazing a cutting blade member made of a sintered body to a stepped notch formed in a corner portion of a support member made of WC-based cemented carbide, in an upper layer constituting the cutting blade member. At the interface with the lower layer, a Co infiltration layer was formed by infiltrating Co that is a binder phase forming component of the lower layer to a depth of 150 μm or more from the interface with the lower layer during sintering of the upper layer, It features a throw-away cutting tip with excellent fracture resistance. In addition, in the throwaway cutting tip of the present invention, C in the upper Co infiltration layer constituting the tip
The reason why the infiltration depth of o is 150 μm or more is that if the depth is less than 150 μm, desired excellent fracture resistance cannot be ensured, and this Co infiltration depth is
By adjusting the Co content of the lower layer, the above intermediate pressure and intermediate temperature during sintering, and the holding time under these conditions, etc., it is desirably adjusted within the range of 250 μm to 50% of the thickness of the upper layer. Is desirable.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the throwaway cutting tip of the present invention will be specifically described by way of examples. First,
As raw material powders, cBN powder, TiC powder, TiN powder, TiCN powder, TiB ₂ powder, TaC powder, TaN, each having a predetermined average particle size within the range of 1 to 10 μm
Powder, TaCN powder, NbC powder, HfC powder, HfN
Powder, HfCN powder, Al ₂ O ₃ powder, and AlN powder were prepared, and these raw material powders were blended to the blending composition shown in Table 1 and wet-blended in a ball mill for 48 hours,
After drying, at a pressure of 200 MPa, diameter: 20 mm x
Thickness: formed into a disk-shaped green compact having a size of 1.5 mm, and the green compact was placed in a vacuum of a pressure of 3 × 10 ⁻³ torr,
The calcination was performed at a temperature of 950 ° C. for 30 minutes to form the upper layer forming temporary sintered bodies A to I of the cutting blade member.
Moreover, 1 × 10 ⁻³ t of a green compact having the composition shown in Table 2 was used.
Sintered body a for forming a lower layer of a cutting blade member obtained by sintering at a predetermined temperature within a range of 1380 to 1450 ° C. in a vacuum of orr
i prepared.

Next, these upper layer forming temporary sintered bodies A to I are formed.
And the lower layer forming sintered bodies a to i are superposed in the combinations shown in Table 3, respectively, and charged into a usual belt type ultra high pressure sintering apparatus, and the sintering conditions shown in FIG. When the pressure inside the cell is raised to an intermediate pressure of 2 GPa, the temperature rise is started, and while maintaining the intermediate pressure, the temperature is raised to an intermediate temperature of 1000 ° C. and kept at this intermediate pressure and the intermediate temperature for 30 minutes. Then, only the pressure is increased again to increase the sintering pressure to 5 GPa, at which point the temperature is further increased to the sintering temperature of 1350 ° C. After holding for a minute, cooling is carried out, and after cooling is completed, sintering is carried out under the sintering conditions in which the pressure drop from the sintering pressure is started to form a cutting edge member composed of a two-layer composite sintered body of an upper layer and a lower layer. With the cutting blade member divided into four and the cross section polished The Co infiltration layer formed at the interface with the lower layer of the upper layer was observed with an X-ray microanalyzer, and the maximum infiltration depth and the minimum infiltration depth in the upper layer of Co, which is the binder phase forming component of the lower layer, were measured. The WC-based cemented carbide support member (Co: 8% content) is formed by forming a stepped notch having a dimension corresponding to the cutting blade member that has been measured, and then the stepped cutting member is measured. Cu: 1 in the notch
9.5%, In: 5%, Ti: 3%, Ag + unavoidable impurities: A composition having the composition of the rest: a thickness of 0.35 mm, and a plate-like brazing material is sandwiched between them and placed at 1 × 10 ⁻³ torr. Brazing is performed in vacuum at a temperature of 950 ° C. for 5 minutes, and finally subjected to polishing to JIS / TNMA3.
With the shape of 32, the throwaway cutting chips of the present invention (hereinafter, referred to as the present chips) 1 to 9 were manufactured.

Further, for comparison purposes, the sintering conditions of the superposed body of the above-mentioned upper layer forming temporary sintered bodies A to I and the above lower layer forming sintered bodies a to i are as follows: first, the pressure is 5 GPa. When the temperature rises to 1, the temperature rise is started, and while maintaining the sintering pressure, the temperature is raised to a sintering temperature of 1350 ° C., and the sintering pressure and the sintering temperature are maintained for 30 minutes, followed by cooling and cooling. Conventional throwaway cutting chips (hereinafter referred to as conventional chips) 1 to 9 were manufactured under the same conditions except that the sintering conditions were such that the pressure reduction from the sintering pressure was started at the end.

[0009]

[Table 1]

[0010]

[Table 2]

[0011]

[Table 3]

[0012]

[Table 4]

Next, the chip 1 of the present invention obtained as a result of this
~ 9 and conventional chips 1 to 9, Work material: JIS / FC250 (pearlite cast iron) round bar, Cutting speed: 700 m / min. Notch: 0.25 mm. Feed: 0.4 mm / rev. Cutting time: 60 minutes, wet continuous cutting test of cast iron under the following conditions: Work material: Cr: 14%, Fe: 6%, Ni: balance, Ni-based alloy round bar, cutting speed : 250 m / min. Incision: 0.5 mm. , Feed: 0.3 mm / rev. Cutting time: 20 minutes, Wet continuous cutting test of Ni-based alloy under the following conditions,

Workpiece material: JIS FC250, four longitudinally equidistant round bars with V grooves, cutting speed: 300 m / min. Notch: 0.25 mm. , Feed: 0.3 mm / rev. Cutting time: 30 minutes, wet intermittent cutting test of cast iron under the following conditions, and work material: Ni-based alloy having the above composition 2 in the longitudinal direction V
Round bar with groove, cutting speed: 100 m / min. Notch: 0.25 mm. Feed: 0.4 mm / rev. Cutting time: 20 minutes, a wet interrupted cutting test was performed on the Ni-based alloy, and the flank wear width of the cutting edge was measured in each cutting test. These measurement results are shown in Tables 3 and 4 together with the measurement results of the maximum infiltration depth and the minimum infiltration depth of the Co infiltration layer in the upper layer.

[0015]

From the results shown in Tables 3 and 4, the chips 1 to 9 of the present invention exhibit excellent wear resistance in both continuous cutting and intermittent cutting, while the conventional chips 1 to 9 show continuous cutting. Shows excellent wear resistance equivalent to that of the chips 1 to 5 of the present invention, but it is clear that intermittent cutting causes chipping or chipping of the cutting edge and reaches a service life in a relatively short time. As described above, the throwaway cutting tip of the present invention is a Co-forming component of the lower layer formed in the upper layer of the cutting blade member constituting the lower layer over a depth of 150 μm or more from the interface with the lower layer. Since the Co infiltrated layer formed by infiltrating the steel exhibits excellent cutting performance in both continuous cutting and interrupted cutting for a long period of time,
It has industrially useful properties such as that it greatly contributes to A conversion and labor saving.

[Brief description of drawings]

FIG. 1 is a diagram showing sintering conditions of a throwaway cutting tip of the present invention.

FIG. 2 is a diagram showing sintering conditions of a conventional throwaway cutting tip.

FIG. 3 is a schematic perspective view of a throwaway cutting tip.

[Explanation of symbols]

 1 Cutting Blade Member 1a Upper Layer 1b Lower Layer 2 Support Member 3 Brazing

Claims (1)

[Claims] 1. A cutting blade member comprising a two-layer composite sintered body comprising an upper layer of a cubic boron nitride based sintered material and a lower layer of a tungsten carbide based cemented carbide containing Co as a binder phase forming component,
In the throwaway cutting tip brazed to the stepped notch formed in the corner of the support member of the tungsten carbide based cemented carbide, in the interface with the lower layer in the upper layer constituting the cutting blade member, A Co infiltration layer is formed by infiltrating Co as a binder phase forming component of the lower layer to a depth of 150 μm or more from the interface with the lower layer during sintering of the upper layer. Excellent throwaway cutting tip.