COMPOSITE SINTERED BODY CUTTING TOOL

Abstract

A composite sintered body cutting tool, in which tungsten is reduced, is made of a TiCN-based cermet and WC-based cemented carbide. The cutting tool has an angle of less than 90 degrees formed by a rake face and a flank face. The rake face including a cutting edge contains WC-based cemented carbide including 4% to 17% by mass of iron group metal components with a remainder being WC. The thickness of the carbide is 0.05 to 0.3 times the thickness of the composite sintered body. The TiCN-based cermet which is a base body of the cutting tool includes 4% to 25% of the iron group metal components, less than 15% of W, 2% to 15% of Mo, 2% to 10% of Nb, and 0.2% to 2% of Cr. The cermet may contain iron group metal Co and Ni, where, Co/Co+Ni is 0.5 to 0.8.

Claims

1. A cutting tool made of a composite sintered body comprising: a rake face; and a flank face, wherein the cutting tool is made of TiCN-based cermet and WC-based cemented carbide, the rake face has a planar shape, which is a multangular shape, and an angle formed by the rake face and the flank face is less than 90 degrees, the rake face including a cutting edge of the cutting tool is configured made of WC-based cemented carbide including 4% to 17% by mass of iron group metal components with a remainder being WC as a principal hard phase component, a thickness of the WC-based cemented carbide is 0.05 to 0.3 times a thickness of the composite sintered body, and the TiCN-based cermet contains one or more TiCN-based cermet layers, in a case in which content proportions of constituent components of the cermet are represented by content proportions of metal components, the TiCN-based cermet layer adjacent to the WC-based cemented carbide includes at least 4% to 25% by mass of the iron group metal components, less than 15% by mass of W, 2% to 15% by mass of Mo, 2% to 10% by mass of Nb, and 0.2% to 2% by mass of Cr, and Co and Ni which are iron group metal components satisfy a content proportion of Co relative to a total content of Co and Ni being 0.5 to 0.8 (in terms of mass ratio).

2. The composite sintered body cutting tool according to claim 1, wherein a hard coating layer is deposited, at least, on a surface of a portion of the cutting tool made of the WC-based cemented carbide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein like designations denote like elements in the various views, and wherein:

[0061] FIG. 1 illustrates schematic diagrams of a composite sintered body cutting tool of this invention, in which FIG. 1(a) illustrates an example of the composite sintered body cutting tool of this invention, and FIG. 1(b) illustrates another example thereof.

[0062] FIG. 2 illustrates schematic diagrams of a composite sintered body surface-coated cutting tool of this invention, in which FIG. 2(a) illustrates an example of the composite sintered body surface-coated cutting tool of this invention, and FIG. 2(b) illustrates another example thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0063] Hereinafter, this invention will be specifically described on the basis of examples.

Examples

[0064] (a) First, WC-based cemented carbide raw material powder having an average grain size of 0.5 to 3 m in a formulation shown in Table 1 was prepared.

[0065] In addition, TiCN-based cermet raw material powder having an average grain size of 0.5 to 3 m in a formulation shown in Table 2 was prepared.

[0066] The WC-based cemented carbide raw material powder and the TiCN-based cermet raw material powder were laminated and pressed in an ISO insert-shaped mold for CCGT120408 materials in a combination shown in Table 3, thereby producing composite compacts 1 to 12.

[0067] Meanwhile, the produced composite compacts 1 to 12 were composite compacts 1 to 6 which were made of the WC-based cemented carbide raw material powder and one kind of TiCN-based cermet raw material powder and composite compacts 7 to 12 for which the WC-based cemented carbide raw material powder and two kinds of TiCN-based cermet raw material powder of raw material powder for a TiCN-based cermet layer 1 and raw material powder for a TiCN-based cermet layer 2 were used.

[0068] Next, these composite compacts 1 to 6 were sintered, thereby producing composite sintered bodies 1 to 6.

[0069] Similarly, the composite compacts 7 to 12 were sintered, thereby producing composite sintered bodies 7 to 12.

[0070] The sintering conditions are as described below in both cases.

[0071] When the composite compact was heated to the sintering temperature, the composite compact was heated from room temperature to 1,280 C. at a rising rate of 5 C./min, was heated in a range from 1,280 C. to 1,380 C. in which a liquid phase appears at a high rising rate of 30 C./min or more in both cases, and was heated from 1,380 C. to predetermined 1,420 C. at a rising rate of 5 C./min, and the composite compact was held at the sintering temperature of 1,420 C. for one hour in a nitrogen atmosphere of 0.1 kPa and is then cooled.

[0072] Next, for the obtained composite sintered bodies 1 to 6 and 7 to 12, the WC-based cemented carbide was used as the rake face, and the cutting edge portion was honed to R=0.04, thereby producing composite sintered body cutting tools 1 to 6 and 7 to 12 having a CCGT120408 shape (hereinafter, referred to as invention tools 1 to 6 and 7 to 12).

[0073] On cross-sections of the WC-based cemented carbide and TiCN-based cermet parallel to the lamination direction in the invention tools 1 to 6 and 7 to 12, the composition was analyzed using an electron beam micro-analyzer at a location 100 m away from the interface between the WC-based cemented carbide and the TiCN-based cermet toward the WC-based cemented carbide side and at a location 100 m away from the interface toward the TiCN-based cermet side respectively, and the average value from measurement at ten points was obtained, thereby obtaining the component compositions of the WC-based cemented carbide and the TiCN-based cermet.

[0074] These values are shown in Tables 5 and 6.

[0075] In addition, the thicknesses of the WC-based cemented carbide and the TiCN-based cermet in the invention tools 1 to 6 and 7 to 12 were observed using an optical microscope and were measured. The thicknesses were measured at five different points and were averaged, thereby obtaining the thicknesses.

[0076] These values are shown in Tables 5 and 6.

[0077] Next, for the invention tools 4 to 6 and 10 to 12, a hard coating layer made of a composite nitride of Ti and Al (here, the contents of Ti and Al were 50% by atom respectively) was deposited on the surface of the WC-based cemented carbide by means of arc ion plating.

[0078] The layer thicknesses of the deposited hard coating layers are shown in Tables 5 and 6.

[0079] For comparison, WC-based cemented carbide raw material powder having a formulation shown in Table 1 and TiCN-based cermet raw material powder having a formulation shown in Table 2 were laminated and pressed in a combination shown in Table 4 so as to produce comparative example composite compacts 1 to 6, and then these composite compacts were sintered under the same conditions as in the examples, thereby producing comparative example composite sintered bodies 1 to 6.

[0080] In addition, comparative example sintered bodies 7 to 9 made only of WC-based cemented carbide (for convenience, referred to as comparative example composite sintered bodies 7 to 9) were produced using WC-based cemented carbide raw material powder having a formulation shown in Table 1 alone without using TiCN-based cermet raw material powder.

[0081] Next, for the obtained comparative example composite sintered bodies 1 to 6 and 7 to 9, the WC-based cemented carbide was used as the rake face, and the cutting edge portion was honed to R=0.04, thereby producing composite sintered body cutting tools 1 to 6 and 7 to 9 having a CCGT120408 shape (hereinafter, referred to as comparative example tools 1 to 6 and 7 to 9).

[0082] Next, in the same manner as in the cases of the invention tools 1 to 12, for the comparative example tools to 6, the composition was analyzed using an electron beam micro-analyzer at a location 100 m away from the interface between the WC-based cemented carbide and the TiCN-based cermet toward the WC-based cemented carbide side and at a location 100 m away from the interface toward the TiCN-based cermet side respectively, and the average value from measurement at ten points was obtained, thereby obtaining the component compositions of the WC-based cemented carbide and the TiCN-based cermet.

[0083] Furthermore, the thicknesses of the WC-based cemented carbide and the TiCN-based cermet in the comparative example tools 1 to 6 were observed using an optical microscope and were measured. The thicknesses were measured at five different points and were averaged, thereby obtaining the thicknesses.

[0084] These values are shown in Table 7.

[0085] Next, for the comparative example tools 4 to 6, a hard coating layer made of a composite nitride of Ti and Al (here, the contents of Ti and Al were 50% by atom respectively) was deposited on the surface of the WC-based cemented carbide by means of arc ion plating.

[0086] The layer thicknesses of the deposited hard coating layers are shown in Table 7.

TABLE-US-00001 TABLE 1 Formulation (% by mass) Iron group metal Type Co VC TaC NbC Cr.sub.3C.sub.2 WC WC-based A 4 2 1 remainder cemented B 10 remainder carbide raw C 17 1 0.5 remainder material D 2 2 1 remainder powder E 20 1 0.5 remainder F 20 remainder

TABLE-US-00002 TABLE 2 Formulation (% by mass) Iron group metal Type Co Ni Fe WC ZrC NbC TaC Mo.sub.2C Cr.sub.3C.sub.2 TiCN TiCN-based A 14 5 12 5 10 1 remainder cermet raw B 2 2 15 11 15 2 remainder material C 16 4 5.5 3 4 3 0.3 remainder powder D 10 5 1 15 2 6 6 remainder E 5 10 10 1 8 10 remainder F 5 5 10 5 23.5 remainder G 15 5 30 2 3 4 2.5 remainder H 1 2 14 13 17 3 remainder I 15 15 15 4 1 remainder

TABLE-US-00003 TABLE 3 TiCN-based TiCN-based WC-based cermet raw cermet raw cemented material powder material powder carbide (for forming (for forming raw material TiCN-based TiCN-based powder cermet layer 1) cermet layer 2) Thickness Thickness Thickness Type Type (mm) Type (mm) Type (mm) Invention 1 B 0.5 A Remainder composite 2 A 0.25 B Remainder compact 3 C 1.4 C Remainder 4 A 1 A Remainder 5 B 0.7 C Remainder 6 C 1.2 B Remainder 7 B 0.5 A 1 D Remainder 8 A 0.25 B 1.5 E Remainder 9 C 1.4 C 1.2 F Remainder 10 A 1 A 2 D Remainder 11 B 0.7 C 1 E Remainder 12 C 1.2 B 1.5 F Remainder (Note) According to JIS Standards, the CCGT120408 shape has a thickness of 4.76 mm, and thus some of the layer thicknesses are indicated as remainder.

TABLE-US-00004 TABLE 4 WC-based cemented TiCN-based carbide raw cermet raw material powder material powder Thickness Thickness Type Type (mm) Type (mm) Comparative example 1 A 0.5 G Remainder composite compact 2 B 0.25 H Remainder 3 C 1.4 I Remainder 4 D 1 A Remainder 5 E 0.7 B Remainder 6 F 1.2 C Remainder 7 A 8 B 9 C (Note) According to JIS Standards, the CCGT120408 shape has a thickness of 4.76 mm, and thus some of the layer thicknesses are indicated as remainder.

TABLE-US-00005 TABLE 5 WC-based cemented TiCN-based cermet.sup.(note) carbide Component composition Component Content composition of iron (Thickness of WC- Thickness Content of group based cemented of hard Type of iron group metals W Mo Nb Cr carbide/thickness of coating composite metals Thickness (% by Co/ (% by (% by (% by (% by composite sintered layer Type compact (% by mass) (mm) mass) (Co + Ni) mass) mass) mass) mass) body) (m) Invention 1 1 10 0.5 19 0.7 11 9 4 1.0 0.1 tool 2 2 4 0.25 4 0.5 14 15 10 2.0 0.05 3 3 17 1.4 20 0.8 5 3 3 0.3 0.3 4 4 4 1 19 0.7 12 10 5 0.9 0.2 2 5 5 10 0.7 20 0.8 15 2 2 0.2 0.15 2 6 6 17 1.2 4 0.5 6 15 9 1.8 0.25 1 .sup.(note)TiCN-based cermet corresponds to cermet produced using TiCN-based cermet raw material powder A to C in Table 2.

TABLE-US-00006 TABLE 6 TiCN-based cermet TiCN-based cermet layer 2.sup.(note 2) Component composition Content (Thickness of iron of WC- Thickness WC-based cemented TiCN-based cermet group W Mo Nb Cr based cemented of hard Type of carbide layer 1.sup.(note 1) metals (% (% (% (% carbide/thickness coating composite Component Thickness Component Thickness by by by by by of composite layer Type compact composition (mm) composition (mm) mass) mass) mass) mass) mass) sintered body) (m) Invention 7 7 Same as in invention tool 1 1 15 15 6 2 0 0.1 tool 8 8 Same as in invention tool 2 1.5 15 10 9 0 0 0.05 9 9 Same as in invention tool 3 1.2 10 9 22 0 0 0.3 10 10 Same as in invention tool 4 2 14 14 5 1 0 0.2 2 11 11 Same as in invention tool 5 1 14 9 10 0 0 0.15 2 12 12 Same as in invention tool 6 1.5 10 10 23 0 0 0.25 1 .sup.(note 1)TiCN-based cermet layer 1 corresponds to a layer produced using TiCN-based cermet raw material powder A to C in Table 2. .sup.(note 2)TiCN-based cermet layer 2 corresponds to a layer produced using TiCN-based cermet raw material powder D to F in Table 2.

TABLE-US-00007 TABLE 7 WC-based cemented TiCN-based cermet.sup.(note) carbide Component composition Component Content composition of iron (Thickness of WC- Thickness Content of group based cemented of hard Type of iron group metals W Mo Nb Cr carbide/thickness coating composite metals Thickness (% by Co/ (% by (% by (% by (% by of composite layer Type compact (% by mass) (mm) mass) (Co + Ni) mass) mass) mass) mass) sintered body) (m) Comparative 1 1 4 0.5 20 0.8 30 2 3 0 0.1 example tool 2 2 10 0.25 3 0.3 13 16 13 3 0.05 3 3 17 1.4 30 0.5 14 1 0 0 0.3 4 4 2 1 20 0.7 11 9 5 1 0.2 2 5 5 20 0.7 4 0.5 14 14 11 2 0.15 2 6 6 20 1.2 10 0.8 5 3 3 0.3 0.25 2 7 7 4 1 2 8 8 10 1 2 9 9 17 1 1 .sup.(note)TiCN-based cermet corresponds to cermet produced using TiCN-based cermet raw material powder A to C and G to I in Table 2.

[0087] Next, on the invention tools 1 to 12 and the comparative example tools 1 to 9, wet milling tests for alloy steels were carried out under the conditions of

[0088] Workpiece: Block materials of JISSCM440

[0089] Cutting speed: 325 m/min,

[0090] Depth of cut: 1.0 mm,

[0091] Feed: 0.13 mm/rev., and

[0092] Cutting time: 12 minutes, and

[0093] the flank wear width or the cutting time taken until the end of the service life was measured.

[0094] Furthermore, for the invention tools 1 to 12 and the comparative example tools 1 to 6, the reduced fractions of the W usage (% by mass) in a case in which the cermet was not laminated and all of the respective tools were made of the WC-based cemented carbide were computed from the values of (the thickness of the WC-based cemented carbide)/(the thickness of the tool) shown in Tables 5 and 6.

[0095] These results are shown in Table 8.

TABLE-US-00008 TABLE 8 Reduced Reduced fraction of W fraction of W Flank wear usage (% by Flank wear usage (% by Type width (mm) mass) Type width (mm) mass) Invention tool 1 0.11 78 Comparative example 1 *3.7 61 2 0.14 79 tool 2 *3.2 80 3 0.16 66 3 *1.3 58 4 0.09 69 4 *4.3 69 5 0.08 80 5 *4.5 69 6 0.10 61 6 *4.9 70 7 0.13 75 7 0.12 0 8 0.14 83 8 0.15 0 9 0.18 63 9 0.11 0 10 0.10 68 11 0.09 77 12 0.12 64 The sign * for the comparative example tools indicates the cutting time (minutes) taken until the end of the service life due to the generation of abnormal damage such as thermal cracks.

[0096] From the results shown in Tables 5 to 8, it is found that, in the invention coating tools, in spite of the reduction of the tungsten usage, when the component composition ranges of the TiCN-based cermet and the WC-based cemented carbide are optimized, and the thickness ratio of the WC-based cemented carbide constituting the rake face including the cutting edge is optimized, the thermal crack resistance does not degrade, in the wet intermittent cutting of alloy steel and the like in which an intermittent and impact high load and a thermal load are exerted on the cutting edge, the propagation and development of cracks are prevented, excellent abnormal damage resistance and wear resistance are exhibited throughout long-term use, and cutting performance as favorable as that of the comparative example tools 7 to 9 produced using the WC-based cemented carbide alone (that is, tools having a reduced fraction of the W usage of 0%) is exhibited.

[0097] In contrast, it is evident that, in the comparative example tools 1 to 6, although the tungsten usage is reduced, the thermal crack resistance deteriorates, and the service life ends within a short period of time.

INDUSTRIAL APPLICABILITY

[0098] The cutting tool of the present invention in which a composite sintered body is used as the tool body is capable of reducing the tungsten usage, which is a rare metal, and, even in a case in which the cutting tool is used in wet intermittent cutting in which an intermittent and impact high load and a thermal load are exerted on the cutting edge, the thermal crack resistance is excellent, abnormal damages such as chipping, fracture, and peeling does not occur, excellent cutting performance can be exhibited throughout long-term use, and it is possible to sufficiently satisfactorily handle the demand for energy saving and cost reduction in cutting.