JPS6330982B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high-hardness sintered body for cutting having cubic boron nitride and/or wurtz-type boron nitride crystals, and in particular, the impact resistance and thermal shock resistance are improved by improving the bonding material. It is something. Conventionally, this type of high-hardness sintered body for cutting has been obtained by sintering cubic boron nitride together with a binder under ultra-high pressure and high temperature. As a binding material, for example,
A metal type made of a specific aluminum alloy, as disclosed in Japanese Patent Application Laid-open No. 43846, and a ceramic type, as disclosed in JP-A-53-77811, are known. However, these bonding materials do not necessarily give satisfactory results in interrupted cutting or high-feed cutting, and therefore there is a need for improved bonding materials that can ensure impact resistance and thermal shock resistance. ing. The present invention has been made in view of the above-mentioned points, and is a cutting material using a binding material consisting of 40 to 95% by volume of cubic boron nitride crystal and/or wurtz-type boron nitride crystal, and the remainder being carbide-metal based. In a high-hardness sintered body, impact resistance and thermal shock resistance are improved by considering the composition of the carbide-metal type bonding material. Hereinafter, one embodiment of the high-hardness sintered body for cutting of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a high-hardness sintered body for cutting obtained according to the present invention, in which a cubic boron nitride crystal and/or a wurtz-type boron nitride crystal are combined with a carbide-metal binder under ultra-high pressure. It is sintered at high temperatures. In this case, the ultra-high pressure and high temperature state is usually obtained by an ultra-high pressure generator such as a four-way pressurization type, a six-way pressurization type, a piston cylinder type, or a belt type. The cubic boron nitride crystal and/or the Wurtzian boron nitride crystal account for 40% of the total amount of the sintered body 1.
~95% by volume (hereinafter referred to as %), and the remainder is a binder. Note that when cubic boron nitride crystals and wurtz-type boron nitride crystals coexist, more than half of the wurtz-type boron nitride blended as a raw material for the wurtz-type boron nitride crystals is It is converted into a cubic boron nitride crystal by sintering, and it exists as a residue of the cubic boron nitride crystal. This is due to cutting performance, especially impact resistance. As described above, the binder is composed of a carbide component and a metal component, with the carbide component accounting for 40% or more of the binder, and the metal component accounting for the remainder. In addition, carbide components are
It is made of a solid solution of TiC and TaC and/or NbC in which the volume ratio of TaC and/or NbC to TiC is within the range of 5:1 to 3:2. And some of these solid solution components are
carbides of group a, a and group a metals (TiC,
(excluding TaC and NbC), nitrides, and borides. In this case, the solid solution needs to account for 50% or more of the carbide components in order to impart toughness. In addition, examples of carbides (excluding TiC, TaC, and NbC), nitrides, and borides of group a, a, and group a metals include WC, Mo ₂ C, VC,
Carbides such as HfC, Cr ₃ C ₂ , ZrC, W ₂ N, Mo ₂ N,
Nitrides such as NbN, TiN, TaN, W ₂ B ₅ , TiB ₂ ,
Borides such as ZrB ₂ , CrB ₂ and TaB ₂ can be mentioned. Furthermore, the solid solution includes not only a raw material powder that has been converted into a solid solution in advance, but also a single raw material powder that has been blended in anticipation of being converted into a solid solution. Furthermore, the metal components include Nb, Ta,
The first group of Zr, Mo and Ti, the second group of Ni and Co
1 type or 2 types from the third group of groups Al and Si, respectively
More than one species consists of selected three-group components. The second group contains 40% or less of these metal components. This is because when the content is high, the adhesive strength increases, but the high temperature strength of the bonding material decreases. The high-hardness sintered body 1 for cutting is clamped by a shank 3 of a cutting tool 2 as shown in FIG. 2, for example, and participates in cutting. The one shown in FIG. 3 is fixed on a base 4 made of cemented carbide, and is used as a throw-away tip 5. In this fixation, when the high-hardness sintered body 1 for cutting is sintered under ultra-high pressure and high temperature, it is simultaneously fixed to the already sintered cemented carbide base 4. Example 1 A high-hardness sintered body 1 for cutting is made of 90% by volume (hereinafter referred to as %) of cubic boron nitride with a diameter of 4μ, and the remaining 10% as a binder. The binder consists of 4% TiC and TaC as carbide-based raw material powder and 6% as metal-based raw material powder.
Nb was selected from the first group, Ni was selected from the second group, and Al was selected from the third group at the same amount of 2%. In this case, the volume ratio of TiC powder to TaC powder was 3:2. Next, the mixed powder of boron nitride and the binder was mixed in a ball mill for 40 hours, degassed and preformed in a vacuum furnace, and then placed under ultra-high pressure and high temperature. At this time, the ultra-high pressure and high temperature state has a pressure of 60Kb and a temperature of 1400Kb.
It was kept at ℃ for 30 minutes. As a result, a high-hardness sintered body 1 for cutting as shown in FIG. 1 was obtained, which was used as a cutting tool 2 as shown in FIG. 2 for a cutting test. Cutting test was conducted using hardened SKH-3 (HRc66)
This is a sample that was machined for 10 minutes in a wet machine using cutting fluid. The cutting conditions at this time are
Cutting speed V = 90 m/min, depth of cut d = 0.5 mm, and feed f = 0.1 mm/rev. The cutting test results showed flank wear of 0.1 mm and crater wear of 0.016 mm. In contrast, the conventional product had flank wear of 0.14 mm and crater wear.
As a result, the effect of the present invention was recognized. In this case, the conventional product is 90% CBN + 10% binder (Ni + Al). In addition, the volume ratio of TiC and TaC is 5:1 to 3:2.
A similar effect was observed when the temperature was varied within the range of . In this case, the volume ratio hardly changed during the mixing of the raw materials and after sintering. In addition, the Ni powder of the second group mentioned above and the Al powder of the third group
Although the powders were blended as individual powders, alloy powders may also be used, and Ni 3 Al, Ni ₃ Al,
It may also be an intermetallic compound such as NiAl or Ni ₂ Al ₃ . In this case, the strength is the first
This is effective because Nb in the group has a solid solution function. Example 2 A high-hardness sintered body 1 for cutting was made of 50% 3μ cubic boron nitride, 30% 3μ Wurtz type boron nitride,
The remaining 20% is a binding material. The binder is 10% TiC and NbC as carbide raw material powder, and 10% TiC and NbC as carbide raw material powder.
2% Nb from the 1st group, 1% Ta from the 2nd group
4% Ni and 3% Al from the third group were selected. In this case, the volume ratio of TiC and NbC is 5:1. Then, the high-hardness sintered body 1 for cutting is sintered on a base 4 made of cemented carbide that has already been sintered, and the third
After the throw-away tip 5 shown in the figure was manufactured, it was used for turning a chilled roll (HRc62). The cutting conditions are: cutting speed V=90m/min;
Depth of cut d = 0.5 mm and feed f = 0.1 mm/rev were selected. The results of the cutting test showed that flank wear occurred after 10 minutes of cutting.
Continuous cutting was possible with a diameter of 0.15 mm, but the comparative product suffered from chipping of the cutting edge in 6 to 8 minutes and became unable to cut. This comparative product is similar to the above-mentioned Example 1,
90% CBN + 10% binder (Ni + Al). It was also applied to intermittent turning and milling, and the impact resistance and thermal shock resistance, which are the objectives of the present invention, were sufficiently observed. Incidentally, even when various combinations of cubic boron nitride and wurtz-type boron nitride were used, similar trends to those described above were observed, and the effects of the present invention were evident. Similarly, the volume ratio of TiC to NbC was also varied, but a range of 3:2 to 5:1 was suitable. In addition, when the metal composition was kept the same at 10% of the total amount and the Ni of the second group was increased to more than 4%, it was subjected to the cutting test described above, but chipping occurred after 10 minutes of cutting. This caused a problem. As a result, for the components of the second group,
It was confirmed that 40% or less is preferable in the metallic composition. This is thought to be because a high content increases adhesive strength, but lowers the high-temperature strength of the binder. Example 3 A high-hardness sintered body 1 for cutting was made of 70% 6μ cubic boron nitride and 30% binder. The binder is carbide-based raw material powder with TiC and NbC at 24% and metal-based raw material powder at 9%.
2% Ti from the 1st group, 2% each of Ni and Co from the 2nd group, and 2.5% each of Al and Si from the 3rd group.
Selected by %. In this case, the volume ratio of TiC and MbC was 5:2. The high hardness sintered body 1 for cutting is 60Kb,
It was obtained by sintering at 1450°C, and was applied to the throw-away chip 5 in the same manner as in Example 2, and was used for turning the outer circumference of SNCM8 (HRc58). The cutting conditions are cutting speed V=150m/min.
Depth of cut d = 0.5 mm and feed f = 0.125 mm/rev were selected. The cutting test results showed that the flank wear was 0.08 mm after 10 minutes of cutting and 0.12 mm after 20 minutes of cutting, whereas the conventional product (same as the conventional product in Example 1) had flank wear of 0.12 mm and 0.27 mm, respectively. The amount of wear in mm is shown. this is,
This is due to improvements in high-temperature properties, toughness, etc. of the high-hardness sintered body 1 for cutting of the present invention. Example 4 A high-hardness sintered body 1 for cutting was made of 60% 3μ cubic boron nitride and 40% binder. The binder is carbide-based raw material powder with 30% TiC and TaC and 10% metal-based raw material powder.
1.5% each of Zr and Nb from the first group, 3% Ni from the second group, and 4% Al from the third group, 3% Mo from the first group, and Co from the second group.
3% and 4% Al from the third group. In this case, TiC and TaC have been made into a solid solution in advance, and their volume ratios are 5:2 and 3:2, respectively. Then, the high-hardness sintered body 1 for cutting was applied to the throw-away tip 5 as in Example 2, and subjected to milling. That is, this milling was performed to examine toughness, and a work material (SKD-11, HRc60) with a cutting surface of 100 mm x 80 mm was cut with a single blade. The cutting conditions at this time are cutting speed V = 250
m/min, constant depth of cut d=0.3mm, feed f
The sizes were increased sequentially to 0.05mm/blade and 0.15mm/blade. As a result, both products of the present invention did not cause chipping at 0.15 mm/blade, whereas the comparative product (same as the conventional product of Example 1) caused small chipping at 0.1 mm/blade, and / Severely damaged by the blade. Therefore, the effect of the product of the present invention was clearly observed even in milling. This means that the high-hardness sintered body 1 for cutting according to the present invention has particularly high impact resistance and
This is because it has excellent thermal shock resistance. Example 5 A high-hardness sintered body 1 for cutting was made of 55% 4μ cubic boron nitride and 45% remaining binder. The binder was made of carbide-based raw material powder, 35% TiC and TaC at a volume ratio of 5:1, 10% metal-based raw material powder, 4% Ta from the first group, and 4% Ni from the second group. 2%, and 2% each of Al and Si were selected from the third group. The high hardness sintered body 1 for cutting is 55Kb,
It was obtained by sintering at 1400°C, and was applied to the throw-away chip 5 in the same manner as in Example 2. The workpiece was a spline shaft (HRc62) made of induction-hardened carbon steel, and the outer circumference of this was subjected to intermittent turning. The cutting conditions are: cutting speed V = 70 to 120 m/min;
The depth of cut d was 0.2 to 0.4 mm, and the feed f was 0.12 mm/rev. As a result, the product of the present invention has a flank wear _VB of 0.2mm.
The conventional product (same as the comparative product in Example 1) showed chipping at the tip after 10 minutes. Similarly, when the volume ratio of TiC and TaC was varied up to 3:2, almost the same tendency was observed.
For those outside the range of 5:1 to 3:2,
Under the cutting conditions described above, chipping was observed after approximately 20 minutes of cutting, and the impact resistance and thermal shock resistance were poor. This is because the high-temperature strength and high-temperature hardness during cutting are inferior to the products of the present invention. Example 6 A high-hardness sintered body 1 for cutting was made of 50% 4μ cubic boron nitride and 50% binder. The binder is a carbide-based raw powder component.
A solid solution of NbC and TaC added to TiC.
41%, the metal-based raw material powder component was 9%, and Nb was selected from the first group, Ni was selected from the second group, and Al was selected from the third group in equal amounts of 3% each. in this case,
The volume ratio of the solid solution of NbC and TaC to TiC was 3:1. Then, the high-hardness sintered body 1 for cutting is applied to the throw-away tip 5 as in Example 2,
Used for milling SKD11. The cutting conditions were as follows: cutting speed V = 150 m/min, depth of cut d = 0.5 mm, feed f = 0.1 mm/tooth, and from the observation of damage to the cutting edge, a single blade was used. The cutting test results were determined by the number of impacts, and the product of the present invention recorded 16,000 impacts. On the other hand, the conventional product (same as the conventional product of Example 1) was 8000 times, which was half. This result also shows that the objectives of the present invention, which are improvements in impact resistance and thermal shock resistance, have been achieved. In addition, as a carbide-based powder component, a part of the solid solution component is replaced with one or more of carbides (excluding TiC, TaC, and NbC), nitrides, and borides of Group A and Group A metals. was also applied, and similar effects were observed. Here, we applied WC, Mo ₂ C, Mo ₂ N, NbN, TiN,
_TiB2 , _ZrB2, etc. In this case, it is necessary that the amount of the solid solution component be equal to or greater than the amount of the replacement component. Examples 7 and 8 in which part of the solid solution components were replaced will be specifically described below. Example 7 In Example 7, CBN was varied from 40 to 95%, and the carbide-based binder was
A part of the solid solution of TiC and TaC and/or NbC is replaced with one or more of carbides (excluding TiC, TaC, and NbC), nitrides, and borides of Group A, A, and A metals. It is something.
Further, the volume ratio of the solid solution between TiC and TaC and/or NbC is within the range of 5:1 to 3:2. The specific composition, cutting test results, etc. of the product of the present invention are shown in Table 1. As a result, the products of the present invention (No. 1 to No. 7) are as follows:
Both products were confirmed to be superior to conventional products made of 90% CBN + 10% binder (Ni + Al).

[Table] Example 8 Example 8 deals with a mixture of both CBN and WBN, and regarding the carbide composition, a part of it is mixed with carbides of group a, group a, and group metals (TiC, TaC, (excluding NbC), nitrides, and borides. Further, the volume ratio of the solid solution between TiC and TaC and/or NbC is within the range of 5:1 to 3:2. The specific composition, cutting test results, etc. of the product of the present invention are shown in Table 2. As a result, the products of the present invention (No. 8 to No. 11) were
Both products were confirmed to be superior to conventional products made of 90% CBN + 10% binder (Ni + Al).

【table】

[Table] Same as the product of the present invention.
Regarding the high-hardness sintered body 1 for cutting of the present invention, the following items were confirmed from the above-mentioned examples and various experiments. Cubic boron nitride crystals and/or Wurtzian boron nitride crystals should be suitable for a range of 40-95% by volume. The range is appropriately selected depending on the workpiece material and cutting conditions. In Examples 1 to 6, 50 to 90% is explained, but in another example (Example 7 Experiment No. 7), it was applicable to a wider range of 40 to 95%. In the case of a mixed crystal, it is preferable that about half or more of the Wurtz-type boron nitride powder blended as a raw material is converted into cubic-type boron nitride crystals by sintering under ultra-high pressure and high temperature. This is a judgment based on the trend of cutting tests. Carbide-based components are generally contained in higher amounts than metal-based components. This means that a large amount of carbide components are included, except when boron nitride crystals are mixed in a high proportion as seen in Example 1. This is to make effective use of the high temperature properties characteristic of carbide components. According to various Examples and Experimental Examples, 40% or more of the carbide-based components were required. The carbide component as a binder is TiC and
constitutes a solid solution with TaC and/or NbC,
The volume ratio of TaC and/or NbC to TiC is within the range of 5:1 to 3:2. This means that TiC is the main component,
This is because improvements in impact resistance and thermal shock resistance were considered as a result of cutting tests. The composition of the metal system as a binder is Nb,
Group 1 of Ta, Zr, Mo and Ti, Ni and Co
A three-group component in which one or more types are selected from the second group of Al and Si and the third group of Al and Si is applied, and in the composition of these metals, the second group accounts for 40% or less, The first group and the second group occupy the rest. These may be combined as single metal powders, alloy powders, or intermetallic compounds. In this case, the components of the first group serve to enhance toughness by promoting solid solution formation with respect to the components of the second and third groups. In addition, the components of the second group and the third group form an alloy or an intermetallic compound to increase high-temperature strength and improve wettability to boron nitride crystals. In this case, the second group of components was a problem because it lowered the high temperature strength of the binder if it exceeded 40% in the metallic composition. These components act as bonding agents for the carbide components, resulting in a strong bond. In addition, Al and Si are used as the raw material components of the third group.
If an alloy or intermetallic compound of
It is desirable that Si accounts for 30% or less of Al by volume.
This is because Al has good bonding properties and Al compounds do not make the high hardness sintered body more brittle than Si compounds. As explained above, the present invention is a high-hardness sintered body for cutting, in which a specific range of carbide-metal bonding materials is selected so as to particularly improve impact resistance and thermal shock resistance. For interrupted turning, high-feed cutting, and milling of high-hardness workpiece materials,
It is effective.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the high-hardness sintered body for cutting of the present invention, Fig. 2 is a perspective view when it is assembled into a clamp bit, and Fig. 3 is a perspective view showing an embodiment of the high-hardness sintered body for cutting of the present invention. FIG. 1... High hardness sintered body for cutting, 2... Bit, 4
...Base, 5...Throwaway tip.

Claims (1)

[Claims] 1. 40 to 95% by volume (hereinafter referred to as %) of cubic boron nitride crystals and/or Wurtzian boron nitride crystals
The remaining 5 carbide-metal binders
In the high-hardness sintered body for cutting, which accounts for ~60%, the binder has a carbide-based composition of 40% or more, and a metal-based composition that accounts for the remainder, and the carbide-based composition Minutes are TiC and TaC and /
or solid solution with NbC, or 50% of this solid solution
% or less (excluding 0%) is replaced with one or more of carbides (excluding TiC, TaC, and NbC), nitrides, and borides of group a, group a metals, and TiC and TaC and/or
The volume ratio between NbC and NbC is in the range of 5:1 to 3:2, and the metal compositions include Nb, Ta, Zr,
A first group of Mo and Ti, a second group of Ni and Co,
1 type or 2 types each from the third group of Al and Si
In addition, in these metal-based compositions, the second group accounts for 40% or less (0%
A high-hardness sintered body for cutting, characterized in that the first group and the third group account for the remainder (not including 0%).