JPS603921B2 - Surface-coated cemented carbide cutting tools - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a surface-coated cemented carbide cutting tool that exhibits excellent wear resistance and chipping resistance, especially in cutting areas such as turning and profile rolling where strong impact forces are applied. be.

In general, a conventional cutting tool made of surface-coated cemented carbide is shown in Fig. 1 as a plan view, Fig. 2 as a front view, and Fig. 3 as an enlarged vertical cross-sectional view of the main part of Fig. 1 taken along line X-X. As illustrated,
Tungsten carbide base, titanium carbide base, titanium carbonitride base,
There are cutting tools IA made of cemented carbide such as titanium nitride base.
1 selected from the group consisting of metals of groups 4a, 5a, and 6a of the periodic table, poron, silicon, and aluminum carbides, nitrides, and oxides, and solid solutions of two or more of these. It consists of a coating layer IB consisting of a single layer of seeds or a multilayer of two or more types with a uniform layer thickness.

Surface-coated cemented carbide cutting tools with this structure (
For example, when the cutting mode is stopped, the tool is exposed to a thermal cycle of heating and cooling, and mechanical shock is applied due to the interrupted cutting mode. When used for machining, cracks occur in the above-mentioned coating layer, which has excellent wear resistance but poor impact resistance and heat damage resistance, relatively soon after cutting starts, and cracks occur once in this way. As a result, stress is concentrated at the tip, causing rapid propagation of cracks, which leads to chipping or breakage of the cutting edge.

Therefore, when we look at the occurrence and growth of cracks in more detail, we find that if it is mainly due to thermal factors, then
Almost perpendicular to the cutting edge ridge (honing part) lc,
A crack occurs on the rake surface la at a position slightly away from the cutting edge ridge, and then, as the crack grows, a crack occurs parallel to the cutting edge ridge, and this growth leads to the cutting edge breakage. there were. On the other hand, when it is caused by mechanical factors, cracks occur on the rake face parallel to the cutting edge ridges and grow, leading to chipping of the cutting edge. The generation and growth were particularly remarkable in coated cemented carbide tools compared to cemented carbide tools without a coating layer. Furthermore, when a cemented carbide tool is used for turning, problems such as significant wear on the flank face lb and both sides of the rake la, and chipping of the cutting edge due to the development of crater wear have been occurring. The above-mentioned problem also occurs when a coated carbide tool is used for turning, which is subject to a strong impact force, as well as milling. The present inventors, from the above-mentioned viewpoint,
In order to easily and inexpensively obtain coated carbide tools that exhibit excellent wear resistance and chipping resistance and can be used for a long period of time, especially in cutting areas where strong impacts are applied, the coating layer is As a result of research focusing on {a}, there is a close relationship between the thermal scratch resistance and impact resistance of the coating layer and its layer thickness, and the thicker the layer, the better the wear resistance. However, the thermal explosion resistance and impact resistance deteriorate, and the coating layer becomes more prone to cracking and chipping.

{b} Therefore, a thick coating layer is applied to the flank face where wear resistance is particularly required, while a relatively thin coating layer is formed on the rake face where burn resistance and impact resistance are required. Moreover, the occurrence of cracks is suppressed by substantially eliminating the presence of the coating layer in the part where cracks occur on the rake face of the coated carbide tool, that is, in the center of the rake face where cracks occur due to the presence of the coating layer as described above. As a result, the tool will have excellent wear resistance and chipping resistance, and even if crater wear occurs in the center of the rake face due to the absence of a coating layer, the crater wear will not reach the ridge of the cutting edge. The growth of the cutting edge is inhibited by the coating layer that exists near the cutting edge ridge, resulting in significantly improved resistance to cutting edge damage due to the development of crater wear.

'c} However, if the thickness of the coating layer is increased by more than 20 mm, the chipping resistance will be significantly reduced even though there is no effect of further improving wear resistance. Do not exceed the layer thickness.

[d- When forming a coating layer on the surface of a carbide tool by applying a method such as a normal chemical vapor deposition method, ion plating method, or sputtering method, the coating layer is applied to the surface of the carbide tool in close contact with or in close proximity to the rake face. If you install a protective plate made of materials such as graphite, oxides, super hard alloys, nitride ceramics, or metals that do not deform at high temperatures, the layer thickness will be thinner on the rake face than on the flank face, and the cutting edge will be thinner. A coating layer is formed that gradually decreases from the ridge toward the center of the rake face so that the layer thickness at the center of the rake face becomes substantially zero.

In this case, the thickness of the coating layer on the rake face can be controlled by adjusting the distance between the rake face and the protection plate. The findings shown in 'a} to {d} have been obtained above.

This invention has been made based on the above findings, and will be specifically explained below using Examples.

Example 1 ISO use classification P3 drop saddle hard alloy cutting tool (shape: SN
P432, barrel honing: 0.03 ribs) IA is mounted on a board 3 arranged in parallel at a predetermined interval by four pillars 2, as shown in a plan view in Fig. 4 and in a front view in Fig. 5.
and the ceramic protection plate 4.

In this case, a constant interval of 0.3 ribs existed between the upper surface (rake surface la) of the carbide tool IA and the inner surface of the protection plate 4. Next, the thus-set state was charged into a surface coating treatment furnace, the temperature inside the furnace was heated to 1000°C, and the gas composition was TIC 14:3%, N2: 37%, and 2:60 p.m.
% (or more by volume) and held for 3 hours to form a TIN coating layer IB on the surface of the cemented carbide tool IA.
A coated carbide tool 1 of the present invention was manufactured by forming a coated carbide tool 1 of the present invention. In the coated carbide tool 1 of the present invention obtained as a result, as shown in FIG. 8, which is an enlarged vertical cross-sectional view of the same part as shown in FIG. A TIN coating layer IB with a thickness of From this, a chambered layer with a layer thickness of 0.1 mm or less was formed over a range of 1 to 2 fences, and there was substantially no coating layer in the center of the rake surface la.

Furthermore, as shown in a plan view in FIG. 6 and in a front view in FIG. The coated carbide tool 2 of the present invention was manufactured under the same manufacturing conditions as the coated carbide tool 1 of the present invention described above, except that the coated carbide tool 2 of the present invention was set.

In this coated carbide tool 2 of the present invention, a TIN coating layer with a thickness of 5 is formed on the flank face lb, and a thick layer is formed on the rake face la extending from the cutting edge ridge to the 2nd to 3rd sides. A TIN coating layer was formed in which the value gradually decreased from one mountain surface, and no coating layer was qualitatively present in other parts of the rake surface la.

Furthermore, for the purpose of comparison, a comparative coated carbide tool 1 was manufactured under the same manufacturing conditions as the coated carbide tool 1 of the present invention, except that no protection plate was used.

Therefore, in this comparative coated carbide tool 1, both the rake face la and the flank face lb have a layer thickness of 5 mm.
An IN coating layer was formed. Next, regarding the coated carbide tools 1 and 2 of the present invention manufactured in this way, the comparative coated carbide tool 1, and the above carbide tool that was not subjected to coating treatment, the workpiece thickness: SCM-4 (hardness HB: 280 ), Cutting speed: 130 mjn, Feed per tooth: 0.2 ribs/blade, Depth of cut: 3 willow, Cutter: Single blade, Flea: 25 broadside, Radial rake;-
A cutting test was conducted under the following conditions: 50, axial rake: -50, cutting oil: not used, and the time required for crater wear to reach 100 degrees was measured, which was defined as the life time.

The results are shown in the table below. As shown in the above table, the coated carbide tools 1 and 2 of the present invention have excellent wear resistance and chipping resistance, so compared to the comparative coated carbide tool 1 and the coating layer, which have a uniform coating layer thickness. It is clear that the tool exhibits a significantly longer service life than a carbide tool without it.

In addition, for the above-mentioned coated carbide tool 2 after use, since there is substantially no coating layer on the rake face only near the cutting edge ridges, polishing is performed only on the flank face (outer periphery) with a width of 4 ribs. to remove the residual coating layer and the arming layer (C-type intermetallic compound) that exists when a coating layer is formed by ordinary chemical vapor deposition on the surface of the carbide tool directly under this coating layer. After that,
When the coating layer was regenerated under the same manufacturing conditions as the coated carbide tool 2 of the present invention and a cutting test was conducted again under the above conditions, the life span was 6 mm, which was almost the same as the coated carbide tool 2 described above. From these results, it can be seen that the cost is extremely low and it can be easily reused.
Example 2 ISO usage classification KI inkstone alloy cutting tool (shape: SN
P432, barrel honing: 0.03 side) As shown in Figures 6 and 7, set the upper and lower surfaces of the IA with a smaller board 3 sandwiched between SUS309 step protection plates 4. , and placed in a vacuum container.

Next, the temperature inside the vacuum container was heated and maintained at 400 qo,
While introducing a mixture of Ar and N2 gases, the atmospheric pressure was increased to 2.
x 10-3 ton, apply the voltage of shoe V to the target Ti plate (99.99% purity) so that it is negative relative to the wall of the vacuum chamber, and hold it for 3 hours to coat the present invention. Carbide tool 3 was manufactured. In the coated carbide tool 3 of the present invention obtained as a result, the flank face lb is coated with a TIN layer with a thickness of 4.0 mm, and the width of 2 yanagi from the cutting edge ridge on the rake face la is coated with a layer thickness of 1 mm. TIN of layer thickness gradually decreasing from
covered with a layer.

For comparison purposes, under the same manufacturing conditions as the coated carbide tool 3 of the present invention, except that no protection plate was used, the rake face la and the flank face lb were made to have a layer thickness of 4.04 mm. various T
A comparative coated super-isolated tool 2 coated with an IN coating layer was manufactured.

Next, regarding the coated carbide tool 3 of the present invention and the comparative coated carbide tool 2, work material: FC25 (hardness HB: 200
) "Cutting speed: 160/mjn, Feed per tooth: 0.2 side/tooth, Depth of cut: 3 ribs, Cutter: Single blade, Diameter: 25mm, Radial rake: -
50, Axial rake: -50 Cutting oil: When a cutting test was conducted under the following conditions, the coated carbide tool 3 of the present invention had a flank wear amount of 0.4 6 minutes after the start of cutting.
In contrast, the comparative coated carbide tool 2 reached the end of its life due to normal wear on the 2nd side, while the comparative coated carbide tool 2 reached the end of its life due to damage due to the development of thermal cracks after only 3 powders after the start of cutting.

Further, when the above-mentioned KI-made carbide tool without the formation of a coating layer was subjected to a cutting test under the same conditions, the flank wear reached 0.4 mm after 15 minutes, and the tool life was reached.

As described above, according to the present invention, a coated carbide tool can be manufactured at an extremely low cost, with easy operation, excellent wear resistance and chipping resistance, and an extremely long service life.
It can be reproduced.

[Brief explanation of drawings]

Figure 1 is a plan view of a conventional surface-coated cemented carbide cutting tool (coated carbide tool), Figure 2 is a front view of the same, and Figure 3 is Figure 1
FIG. 4 is a plan view showing an embodiment of manufacturing the coated carbide tool of the present invention; FIG.
6 is a plan view showing another embodiment, FIG. 7 is a front view of the same, and FIG. 8 is an enlarged view of the same portion as shown in FIG. 3 of the coated carbide tool of the present invention. FIG. In the drawings, IA... Carbide tool before coating treatment, I
B...Covering layer, la...Rake face, l
b... flank face, lc... cutting edge ridge, 2...
...Strut, 3...Substrate, 4...Protection plate. Figure 8 Younger brother l Figure Younger brother 2 Figure 3 Figure 4 Figure 5 Figure 6 Starting diagram

Claims (1)

[Claims] 1 4a and 5a of the periodic table on the surface of a cemented carbide cutting tool
, and carbides, nitrides, and oxides of group 6a metals, boron, silicon, and aluminum, and solid solutions of two or more of these, either as a single layer or as a multilayer. In a cutting tool made of a surface-coated cemented carbide coated with a coating layer having a thickness of 20 μm or less, the thickness of the coating layer on the rake face is thinner than that on the flank face, and A surface-coated cemented carbide cutting machine characterized in that the thickness of the coating layer is gradually reduced toward the center of the rake face so that the thickness of the coating layer at the center of the rake face is substantially zero. tool.