JPS629808A - Composite machining tip - Google Patents

Abstract

PURPOSE:To improve machining performance for the continuous and intermittent process of super hard steel by constituting a composite machining tip wherein a cutter is made of boron nitride group super high pressure sintered material and a support material is made of cermet such as tungsten carbide group sintered hard alloy. CONSTITUTION:A cutter of boron nitride group super high pressure sintered material is bonded to a support material of tungsten carbide group sintered hard alloy or cermet via a bonding layer of 0.1-100mum mean thickness consisting of a metal layer of 4a and 5a group metals in the periodic table and the double layer of a high fusion point compound made from 4a and 5a group metal nitride or carbide nitride, or the alternate multi-layer thereof in order to constitute a composite machining tip. In this case, the mean thickness of the bonded layer is limited to a range of 0.1-100mum. This is because desired effect cannot be maintained with the layer thickness less than 0.1mum and the thickness over 100mum causes a drop in the rigidity of the tip itself, leading to the easy plastic deformation thereof. By the application of the aforesaid constitution, the composite machining tip when used for the intermittent machining of super hard steel, becomes free from the break of the cutting edge and machining performance can be ensured for a long time.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is characterized in that the cutting edge is made of an ultra-high pressure sintered material of boron nitride C (hereinafter referred to as BN), and the support material that supports this material is carbonized. Composed of cermets such as tungsten (hereinafter referred to as WC) cemented carbide and titanium carbide (hereinafter referred to as TiC)-based cermets, it is of course suitable for continuous cutting of high-hardness steels such as die steel and high-speed steel. The present invention relates to a composite cutting tip that exhibits excellent cutting performance even when used for interrupted cutting such as milling and end face cutting.

[Conventional technology]

Conventionally, cubic BN (hereinafter referred to as CBN) and hexagonal BN (
B containing TiC, TiN, AJ, 03, etc. as binder phase forming components.
A cutting edge made of NN ultra-high pressure sintered material is simultaneously bonded to a supporting material made of WCC cemented carbide 1fC cermet during sintering, and a composite cutting tip made of high hardness steel is bonded to a supporting material made of cermet. It is well known that when used as a cutting tool for continuous cutting, it exhibits excellent wear resistance.

[Problem that the invention seeks to solve]

However, although the above-mentioned conventional composite cutting inserts exhibit excellent cutting performance in continuous cutting of high-hardness steel, chipping occurs on the cutting edge when used for interrupted cutting of high-hardness steel. Currently, it is difficult to put it into practical use due to the lack of reliability and ease of use.

[Means for solving problems]

Therefore, from the above-mentioned viewpoint, the present inventors proposed that the cutting edge be made of BNN ultra-high pressure sintered material, and that the supporting material be made of W.
Focusing on the above-mentioned conventional composite cutting tips made of CC cemented carbide or cermet, we have found that this composite cutting tip can be used as a cutting tool not only for continuous cutting of high-hardness steel but also for interrupted cutting. As a result of extensive research, we found that (a) When the conventional composite cutting inserts mentioned above are used for interrupted cutting, the reason why chipping is more likely to occur on the cutting edge is due to the Co contained in the support material as a binder phase forming component. When the cutting blade is sintered, metal components such as Ni and Ni are diffused and infiltrated into the cutting blade, and the high-temperature strength of the cutting blade infiltrated with metal components is not only reduced during cutting, but also caused by this infiltration. The cause is thought to be that tensile stress is more likely to occur in the cutting edge due to the infiltrated metal components and bond phase.

(b) There is a periodic rule between the cutting edge and the supporting material of the above-mentioned conventional composite cutting tip, which has extremely low wettability to CO, Ni, and any metal components, and does not easily cause softening and diffusion phenomenon when the cutting edge is sintered. By interposing a high melting point compound layer consisting of nitride or carbonitride of group 4a and 5a metals in the table, infiltration of the metal components from the support material to the cutting edge during sintering can be significantly suppressed. As a result, chips caused by infiltrated metal components will not occur on the cutting edge.

(c) The high melting point compound layer has particularly low bonding strength to the BNN ultra-ultra high pressure sintered material constituting the cutting edge, but the metal layer consisting of metals from groups 4a and 5a of the periodic table!
When interposed, this metal layer has extremely high bonding strength to both, so a strong bond is ensured between the cutting edge and the support material.

The findings shown in (a) to (C) above were obtained.

Therefore, the present invention has been made based on the above knowledge, and includes a BN-based ultra-high pressure sintered material cutting edge, a metal layer of metals of groups 4a and 5a of the periodic table, and metal layers of metals of groups 4a and 5a of the periodic table. Average layer thickness consisting of double layers of high melting point compound layers of metal nitrides or carbonitrides or alternating multiple layers of these: 0.1 to 100
It is characterized by a composite cutting tip that is bonded to a supporting material made of WCC cemented carbide or cermet through a bonding layer of .mu.m.

In addition, in the composite cutting tip of the present invention, the average layer thickness of the bonding layer is limited to 0.1 to 100 μm because if the thickness is less than 0.1 μm, the desired effect cannot be achieved in the above action. First, if the thickness exceeds 100 .mu.m, the rigidity of the chip itself decreases and it becomes susceptible to plastic deformation, so the thickness was set at 0.1 to 100 .mu.m.

〔Example〕

Next, the composite cutting tip of the present invention will be specifically explained using examples.

Each has the composition shown in Table 1, and diameter: 10
Prepare a support material with dimensions of Dragon X thickness: 21111,
A bonding layer having the composition and thickness also shown in Table 1 is formed on the joint surface of this supporting material with the cutting edge by a normal physical vapor deposition method, and the bonding layer having the composition and thickness also shown in Table 1 is formed on the joint surface of the supporting material with the cutting blade. A powder compact having the composition and dimensions of diameter: 101rlφ x thickness: 2H is prepared, and then the cutting blade compact and the supporting material are sandwiched between the bonding layer and subjected to a normal process. Composite cutting chips 1 to 13 of the present invention were manufactured by charging the chips into an ultra-high pressure and high temperature generator and sintering them under predetermined conditions at a temperature of 1200 to 1400° C. and a pressure of 30 to 60 kb.

For comparison purposes, conventional composite cutting tips 1 and 2 were each manufactured under the same conditions except that no bonding layer was formed.

Next, these composite cutting tips were cut into four parts by wire cutting, brazed to a WCC cemented carbide base metal, and polished to form a 5NP432 shape! Manufactures cutting tools made of high speed steel (SKD-11, hardness: HRC60)
, Cutting speed: 150 m/ring, Feed: 0.2 dragon/rev.

Continuous cutting test of high hardness steel round bar under the following conditions: depth of cut: 0.2 mm, cutting time: 15 minutes, work material: die steel, cutting speed: 40 m/mm, feed: 0.08 III/ rev.

An interrupted cutting test was conducted on a high-hardness steel square material under the conditions of depth of cut = 0.1. In the former continuous cutting test, the flank wear width of the cutting edge was measured, and in the latter interrupted cutting test, the width of flank wear on the cutting edge was measured. The cutting time until this occurred was measured. The results of these measurements are shown in Table 1.

〔Effect of the invention〕

From the results shown in the first column, the composite cutting tips 1 to 1 of the present invention
Although both 13 and the conventional composite cutting chips 1 and 2 exhibit excellent wear resistance in continuous cutting of high-hardness steel, the composite cutting chips 1 to 13 of the present invention exhibit excellent wear resistance in continuous cutting of high-hardness steel. In contrast, conventional composite cutting inserts 1 and 2 both exhibited chipping on most of their cutting edges and reached the end of their useful life in a short period of time.

As mentioned above, the composite cutting tip of the present invention can be used not only for continuous cutting of high-hardness steel, but also for interrupted cutting of high-hardness steel, without causing any chipping on the cutting edge, and for an extremely long period of time. It exhibits excellent cutting performance and is extremely reliable.

Claims (1)

[Claims] The cutting blade made of boron nitride-based ultra-high pressure sintered material is 4a of the periodic table.
Average layer thickness consisting of a double layer of a metal layer of a Group 5a metal and a high melting point compound layer of a nitride or carbonitride of a Group 4a and 5a metal, or an alternating multilayer of these: 0.1 to
A composite cutting tip bonded to a tungsten carbide-based cemented carbide or cermet support via a 100 μm bonding layer.