JPH0715135B2 - Tungsten carbide based cemented carbide drill - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tungsten carbide (hereinafter referred to as WC) based cemented carbide drill having excellent wear resistance as well as excellent breakage resistance.

[Conventional technology]

Generally, in the manufacture of drills, weight percent (below% is weight percent
), Co: 5 to 25%, one or more of TaC, NbC, and TiC: 0.2 to 2%, and the balance is WC and unavoidable impurities. It is used.

[Problems to be solved by the invention]

However, the drills made of the above-mentioned conventional WC-based cemented carbides have excellent wear resistance, but do not show satisfactory results in terms of breakage resistance under the present circumstances.

[Means for solving problems]

Therefore, the present inventors, from the above viewpoint, as a result of conducting research to develop a WC-based cemented carbide drill excellent not only in wear resistance but also in breakage resistance, the above-mentioned conventional of
In WC-based cemented carbide drill, vanadium carbide (VC) replaces TaC, NbC, and TiC contained as alloy components
If the average particle size of the hard dispersed phase composed of components other than Co is 1.5 to 5 μm in the conventional WC-based cemented carbide alloy, and 0.2 to 1 μm, the breakage resistance is It has been found that the wear resistance is significantly improved and the wear resistance is also excellent.

The present invention has been made based on the above findings, and contains Co: 5 to 20%, VC: 0.2 to 10%, with the balance consisting of WC and unavoidable impurities, and components other than Co. This is characterized by a WC-based cemented carbide drill having a fine structure in which the average particle size of the constituent hard dispersed phases is 0.2 to 1 μm, and particularly excellent in breakage resistance and wear resistance. .

Next, the reasons why the component composition and the average particle size of the hard dispersed phase are limited as described above in the WC-based cemented carbide drill of the present invention will be described.

Component A composition (a) Co The Co component is a component that forms a binder phase and is essential for ensuring the toughness of the alloy. However, if the content is less than 5%, the desired toughness cannot be ensured. If the content exceeds 20%, the wear resistance will decrease, so the content was defined as 5 to 20%.

(B) VC The VC component has the effect of significantly improving the breakage resistance without impairing the wear resistance of the alloy, but its content is 0.2
If it is less than 10%, the desired effect of improving the breakage resistance cannot be obtained, while if it exceeds 10%, the wear resistance tends to decrease, so the content is set to 0.2-10%.

B Average particle size of hard dispersed phase It is technically difficult to produce a WC-based cemented carbide with an average particle size of the hard dispersed phase of less than 0.2 μm, while if the average particle size exceeds 1 μm, Since the breakage resistance suddenly decreases, the average particle size was set to 0.2 to 1 μm.

〔Example〕

Next, the WC-based cemented carbide drill of the present invention will be specifically described by way of examples.

As the raw material powder, WC powder, VC powder, TaC powder, NbC powder, and TiC, each of which has an average particle size within the range of 0.2 to 1.0 μm
Powders and Co powders were prepared, and these raw material powders were blended to the blending composition shown in Table 1, mixed in a ball mill and molded into a rod-shaped green compact, and then these green compacts were By sintering in a vacuum of × 10 ^-2 mmHg at a predetermined temperature within the range of 1330 to 1450 ° C for 1 hour,
Has substantially the same composition and average particle size as the blended composition,
And a rod with the dimensions of diameter: 3.555 mm × length: 38.8 mm was made, and this rod was ground to a total length: 38.1 mm, shank diameter: 3.
175 mm, cutting edge diameter: 0.4 mm, cutting edge length: 6 mm of the present invention WC-based cemented carbide miniature drill (hereinafter referred to as the present invention drill) 1
-9, comparative WC-based cemented carbide miniature drills (hereinafter referred to as comparative drills) 1 to 5 and conventional WC-based cemented carbide miniature drills (hereinafter referred to as conventional drills) 1 to 4 were manufactured.

Using the drills 1 to 9 of the present invention, the comparative drills 1 to 5 and the conventional drills 1 to 4, two 4-layer plates made of a mixed resin of glass and epoxy resin having a thickness of 1.5 mm are stacked to obtain a total thickness. After making 5000 hits with a work material of 3 mm, the number of revolutions: 7000 r.pm, drill feed: 2100 mm / min., The reduction in cutting edge diameter of the miniature drill was measured to measure wear resistance. In addition, three layers of mixed resin consisting of the above glass and epoxy resin were stacked on top of each other, and the work material with a total thickness of 4.5 mm was rotated at a rotation speed of 7000 rpm and drill feed: The breakage rate of 20 miniature drills after 1000 hits was measured under the processing conditions of 3000 mm / min., And the breakage resistance was evaluated. The results are shown in Table 1.

[Effects of the Invention] From the results shown in Table 1, the comparative drill 1 containing no VC, the comparative drill 3 having a Co content outside the range of the present invention, and the average particle size of the hard dispersed phase were The comparative drill 5 which is out of the range of the invention has a poor breakage resistance, while the comparative drills 2 and 4 having a high VC and Co content outside the range of the invention have a small breakage resistance. Wear resistance is poor, and the average particle size of the hard dispersed phase is relatively outside the scope of the present invention, and at least one of TaC, NbC, and TiC is used as an alloy component instead of VC. In the conventional drills 1 to 4 containing Cr, the breakage rate is high due to lack of fracture resistance under the severe conditions described above, whereas in the drills 1 to 9 of the invention, the breakage rate is halfway during the test. And not only show excellent fracture resistance, but also excellent wear resistance It is clear that the show also.

As described above, the WC-based cemented carbide drill of the present invention exhibits excellent wear resistance and breakage resistance, and exhibits excellent cutting performance for a remarkably long time.

Claims (1)

[Claims] 1. A composition containing Co: 5 to 20%, vanadium carbide: 0.2 to 10%, and the balance consisting of tungsten carbide and unavoidable impurities (above wt%), and the above components other than Co. A tungsten carbide-based cemented carbide drill having excellent breakage resistance, which has a fine structure in which the average particle size of the hard dispersed phase is 0.2 to 1 μm.