JPS6322922B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Technical field The present invention relates to cutting processing of metal materials, that is, turning processing,
The present invention relates to coated alloy tools used for milling, thread cutting, drilling, etc. The coated cemented carbide mentioned here is a hard sintered alloy such as a cemented carbide whose base is made of WC, TiC, TaC, etc. and an iron group metal, or a cermet whose main component is TiC, TiN, etc. Provides a coating layer made of carbides, nitrides, carbonates, carbonitrides of metals from groups IVa, Va, and Va of the periodic table of elements, which are harder and more wear-resistant than the base, and oxides such as Al and Zr, or solid solutions thereof. It is something that (b) Background of the technology In the field of metal cutting, the processing conditions are becoming stricter year by year, and cutting tools used in this field are desired to have improved hardness, wear resistance, and heat resistance. Cemented carbide tools are a material that satisfies this requirement, but in response to the above requirements, coated cemented carbide tools in which the surface of this cemented carbide is coated with various hard coating layers have become popular in recent years. As a typical shape, a rectangular chip 1 is often fixed to a holder, as shown in FIG. This is called a throw-away chip, and after using its 8 cutting edges, it is discarded and replaced with a new chip. Of course, there are various types of chip shapes, such as triangles, diamonds, irregular shapes, and total shapes. The coating of such a coated cemented carbide tool is generally applied to the surface of an ordinary sintered cemented carbide chip 4 by a CVD method, a PVD method, or the like. Figure 1 B is chip 1 A.
- Shows cross-section A, its cutting edge 2 (near dotted line B)
Enlarged views of are shown in Figs. 2 and 3. As shown in the figure, the conventional coated cemented carbide tip is thicker in the vicinity of the cutting edge 2 than in other parts, although it varies somewhat depending on the shape of the cutting edge of the base. Particularly when the coating film is Al ₂ O ₃ , it is normal for the coating to be thick. Generally, as the coating becomes thicker, the wear resistance improves, but the toughness decreases and chipping is more likely to occur. In other words, chips with a coating layer near the cutting edge ridge as shown in Figures 2 and 3 have lower toughness, resulting in damage to the finished surface of the workpiece due to damage to the cutting edge and irregular wear due to microchipping. There were problems such as deterioration. Various proposals have been made to solve this problem. Special Public Service 1977-
The method described in No. 37553 is a method in which the coating layer remains only in the chip breaker recess, and the coating layer on the land portion at the boundary between the cutting edge 2 and the breaker is removed by polishing. However, this method cannot be applied to chips without chip breakers or chips with protruding chip breakers. In addition, as an invention similar to the present invention, a patent application filed in 1973-
There are 92732. As shown in FIG.
Although this is a coated cemented carbide chip that has a scooping surface with no coating film disposed within it, such a large removal amount causes crater wear to develop on the scooping surface, significantly reducing tool life. (c) Purpose of the invention The present invention provides a stable and long-life coated cemented carbide tool by removing the coating film on the scooping surface side near the cutting edge of a conventional coated cemented carbide tool in a width of 10 μm or more and 100 μm or less. The purpose is to provide cutting tools. (d) Disclosure of the invention The present invention provides a conventional coated cemented carbide cutting tool with a coating film of 10 μm or more on the scooping surface side after coating.
It is characterized by improving not only the strength of the cutting edge but also the wear resistance by removing it within a range of 100 μm or less. Conventional tools that do not have a coating film with a width of 3000 μm (3 mm) or less have a marked decline in crater wear resistance, which is one of the characteristics of coated tools, and are difficult to use when machining highly hard work materials or during high-speed or high-feed machining. In contrast, the tool of the present invention had improved toughness and flank wear resistance, and was able to maintain crater wear resistance. . As shown in FIGS. 5A, 5B, and 5C, the effects of the present invention are exhibited when the removal width W of the coating film is 100 μm or less, and when it exceeds 100 μm, it deteriorates rapidly. This test was conducted using the material with symbol E in Table 1. Furthermore, as shown in FIG. 6, when the removal width W is less than 10 μm, the damage rate increases, and the effect of the present invention is
It is exhibited in the range of 10 μm or more. Figure 6A shows a cross-sectional view of the work material used in the test, and Figure 6B shows the relationship between removal width and failure rate. The effect of the present invention is particularly remarkable when the coating film is maximized near the edge of the cutting edge, as shown in FIG. Reference numeral 6 in FIG. 3 is usually one or more hard substances selected from metal carbides, nitrides, oxides, and solid solutions of metals such as titanium, and the film thickness thereof is generally nearly uniform. The outer layer 7 is a layer whose main component is an oxide or oxynitride of Al or Zr, and the film thickness tends to increase particularly at the edge of the cutting edge. Therefore, the method of the present invention can be used to remove the coating layer to reduce the maximum film thickness near the cutting edge of a multi-layer coated tool in which Al or Zr oxides or oxynitrides are combined with a hard compound such as titanium. Preferably, the substrate is exposed. Figures 4A, 4B, 4C and 4C are cross-sectional views of cutting edges of various chips to which the present invention can be applied. In A, only the coating film is removed, but since it is difficult to control the amount of removal, even the base material may be removed as in B. In addition, after forming a burr-like protrusion around the edge of the cutting edge of the base body, coating is performed, and the protrusion is removed by grinding in figure C, and figure D is a figure in which the scooping surface is processed until it becomes flat. It is easier to manufacture if the protrusion is left slightly as shown in C. Next, embodiments of the present invention will be described in more detail. EXAMPLE Cemented carbide chips made of various materials in the shape of model number ISO and SNMA120408 were coated with various hard coating films shown in Table 1. As a treatment for the cutting edge of each coated cemented carbide chip before coating, only those that were not processed after coating were round honed to a radius of 0.03 mm by the barrel method as shown in FIG. 2C. For the products of the present invention, no cutting edge treatment was performed before coating, and after coating, the products were left in the state shown in FIG. Toughness tests and wear resistance tests were conducted on the various coated cemented carbide chips described above, and the results are shown in Table 2. The toughness test was conducted using four grooves as shown in Figure 6A.
Cutting speed 70 using SCM435 round material with 1.0
m/min, depth of cut 2mm, feed 0.18mm/rotation, cutting time max. 30 seconds, cut for 30 seconds and check for defects.

[Table] 10 points if not found, 6 if found missing
If a point is lost within 30 seconds, the time is t, and the score is t/5 points.If the number of repetitions is n, and the score is s, then [Breakage rate] = (1-S/10・Evaluated as n)×100%. FIG. 6B shows the damage rate when the removal width w is changed. The material is E in Table 1, and the model number is SNMA4325N.
These are the results of testing a coated chip using a PSBNR2525 holder under the above cutting conditions. The wear resistance test conditions were as follows: using the same chip as above, S40C as the work material, cutting speed 220 m/min, depth of cut 2 mm, feed 0.42 mm/rotation, cutting time 15 minutes at 0.55 mm/rotation. Figure 5 b shows the removal width of the coating layer w
It shows the change in flank wear width f (see Figure 5 A) when changing , and the feed rate is 0.50 mm/rotation (M),
The case when 0.36mm/rotation (N) is shown. The results in Table 2 show the case where the feed rate was 0.36 mm/rotation under the above conditions. FIG. 5C shows the relationship between the maximum crater depth d (see FIG. 5A) and the removal width w when the feed rate is 0.55 mm/rotation (K) and 0.42 mm/rotation (L).
It is clear that the chips of the present invention with each number marked with a circle in Table 2, which shows the results when the feed rate was 0.42 mm/rotation, exhibit excellent toughness and wear resistance.

【table】

【table】 [Brief explanation of the drawing]

Fig. 1A is a perspective view of a coated cemented carbide throw-away chip that is the object of the present invention, B is a sectional view taken along line A-A, Fig. 2A, B, C, D, and Fig. 3 are various conventional Fig. 4 A, B, C, and D are enlarged cross-sectional views of the vicinity of the cutting edge of various coated cemented carbide chips of the present invention; Fig. 5 6 shows the wear resistance test results, FIG. 6A is a cross-sectional view of the work material used in the toughness test, and FIG. 6B shows the test results. 1...Coated cemented carbide throw-away tip, 2
... Cutting edge ridge, 4 ... Base, 5, 6, 7 ... Coating film, C ... Scooping surface side, D ... Flank surface side, 8 ... Holder, 9 ... Work material, 10 ... ...Groove, K...Feed
Maximum crater depth at 0.55mm/rotation, L...
...Maximum crater depth at feed rate of 0.42 mm/rotation, M...Flank wear width at feed rate of 0.05 mm/rotation, N...Flank wear width at feed rate of 0.42 mm/rotation, w...Coating layer removal width, d...Crater Maximum depth, f... Flank wear width.

Claims (1)

[Scope of Claims] 1. A cutting tool whose base is made of cemented carbide and whose surface is coated with a substance harder than the base, in which the coating near the cutting edge of the tool is removed on the scooping surface side, A coated cemented carbide tool having a removal width of 10 μm or more and 100 μm or less. 2. Claim 1, characterized in that the coating film consists of two or more multilayers, and at least one layer of the multilayer film has an oxide or oxynitride of Al or Zr as a main component. The coated cemented carbide tool described in .