JP5094177B2 - Cutting tool and cutting method - Google Patents

Description

The present invention relates to a beauty switching cutting method Oyo cutting tool to form a coating layer on the surface of the substrate.

  Conventionally, the surface of a substrate made of a hard alloy such as tungsten carbide-based cemented carbide or titanium carbonitride-based cermet is made of a titanium-based compound such as titanium carbide, titanium nitride, or titanium carbonitride, and has wear resistance and mechanical properties. A cutting tool formed with a coating layer having excellent strength is widely used.

  Among them, the coating layer made of (Ti, Al) N has high hardness and excellent oxidation resistance when exposed to high temperatures, and is suitably used as the coating layer. Various proposals have been made to improve the performance of such a coating layer made of (Ti, Al) N.

For example, a coating layer has been proposed that has a laminated structure composed of (Ti, Al) N having three or more layers with different Al concentrations, and a layer with a low Al concentration sandwiched between layers with a high Al concentration ( For example, see Patent Document 1). A multilayer (Ti, Al) N layer in which a low hardness (Ti, Al) N layer and a high hardness (Ti, Al) N layer are alternately laminated has been proposed (for example, Patent Document 2). These techniques are used to disperse and relax strain and residual compressive internal stress in the coating layer by sandwiching a layer with high toughness and low oxidation resistance between layers with low toughness and high oxidation resistance. It is possible to suppress a decrease in fracture resistance due to the addition of.
JP-A-6-316756 JP-A-11-61380

  However, a layer with a low Al concentration is inferior in oxidation resistance as compared with a layer with a high Al concentration. Therefore, if the upper layer is worn and exposed during cutting, the oxidation progresses rapidly and the part deteriorates and wears. There is a problem that the wear resistance of the entire coating layer is not sufficient.

  In addition, the coating layer having a multilayer structure in which a plurality of (Ti, Al) N layers having different compositions as described in Patent Document 1 and Patent Document 2 are laminated is appropriately adjusted in the composition ratio of Ti and Al. In order to do so, it is necessary to install multiple targets with different compositions in the reaction system, which may impose significant restrictions on equipment and condition settings, and is difficult to implement on an industrial scale. is there.

An object of this invention is to provide the cutting tool provided with the coating layer which consists of a (Ti, Al) N layer excellent in abrasion resistance in view of the said problem .

  As a result of intensive research to solve the above problems, the present inventor provides an excellent cutting tool by coating the substrate surface in an appropriate state in consideration of the crystal plane orientation and crystallinity of the coating layer. I found out that I can do it.

That is, the cutting tool of the present invention includes a base and a coating layer containing Ti and Al formed on the surface of the base. The base has a rake face on an upper surface and a flank on a side face. In a cutting tool provided with a cutting edge on at least a part of the intersecting ridge line between the surface and the flank, the half width Bf of the peak belonging to the (111) plane in the X-ray analysis pattern of the coating layer on the flank is 0. 6
° with at least, of the X-ray diffraction pattern of the coating layer in the rake face, (111) Ri der FWHM Br is 0.9 ° or more peaks attributable to surface, the half width Bf and the The half-value width Br is in the range of Bf / Br = 0.6 to 0.85 .

  In the above invention, the half-value width Bf and the half-value width Br have an X-ray analysis pattern peak in a range of 2θ = 36.5 to 38.0.

  In the invention according to the first aspect, the coating layer in the vicinity of the cutting edge where the most wear resistance and fracture resistance are required among the cutting tools without using targets having different composition ratios of Ti and Al in the coating layer. By controlling the degree of crystallinity on the flank face, it is possible to provide excellent wear resistance as a whole coating layer. Therefore, a long-life cutting tool can be provided.

  Further, in the invention according to claim 2, the rake face of the coating layer is controlled by controlling the crystallinity of the rake face of the coating layer on which toughness is important compared to the flank face on which wear resistance is important. The functions required at each part of the flank can be sufficiently provided. Therefore, it is possible to provide a cutting tool having a longer life.

  1 is a schematic perspective view of a cutting tool, FIG. 2 is a schematic cross-sectional view of a cutting tool according to an embodiment of the present invention, and the base body and the coating layer of FIG. This will be described with reference to FIG. 3 which is an enlarged view of the interface portion (E portion).

  In addition, as said cutting tool, the thing provided with the cutting blade part which contributes to cutting, such as the cutting insert used for a brazing type or a throw away type turning tool, a solid type drill, or an end mill, is pointed out. In addition, in the Example described below, the cutting insert attached to a holder is illustrated and demonstrated as a cutting tool.

  According to FIG. 1, a cutting tool (hereinafter simply referred to as “tool”) 1 of the present invention has a rake face 3 as a main surface, a flank face 4 on a side surface, and a cross ridge line between the rake face 3 and the flank face 4. The cutting edge 5 is provided, and the coating layer 6 is formed on the surface of the substrate 2.

  The coating layer 6 of the present invention is composed of a material made of a composite compound containing at least titanium element (Ti) and aluminum element (Al), which is excellent in properties necessary for cutting such as hardness, toughness, and oxidation resistance. The Specific examples include (Ti, Al, Cr) N, (Ti, Al, W, Nb, Si) N, and (Ti, Al) N. Among these, (Ti, Al) N is particularly preferable because of its high hardness and excellent oxidation resistance when exposed to high temperatures.

  Here, according to the present invention, the half-value width Bf of the peak attributed to the (111) plane in the X-ray analysis pattern of the covering layer 6 on the flank 4 is 0.6 ° or more. That is, among the particles constituting the coating layer 6, the (111) plane particles are atomized and the growth direction of the particles is uniform. Thereby, the abrasion resistance of the flank 4 can be improved.

  Further, the half width Bf is preferably in the range of 0.6 ° to 0.8 °. As a result, the particles constituting the coating layer 6 become columnar crystals that uniformly grow substantially perpendicular to the substrate 2 and have a substantially uniform crystal width, so that stress concentration is less likely to occur in the film. That is, by having a structure that is uniformly aligned, a structure in which particles are not easily dropped by impact or friction can be obtained, and therefore, wear resistance can be improved especially on a flank where wear progresses due to frictional wear.

  Here, as a method of measuring the half width Bf, it can be measured by X-ray diffraction analysis (XRD). As analysis conditions, for example, CuKα rays can be used, the X-ray output can be 40 kV, 40 mA, and the step width can be 0.02 °.

  Further, in the X-ray analysis pattern of the coating layer 6 on the rake face 3, the half-value width Br of the peak attributed to the (111) plane is 0.9 ° or more, particularly in the range of 0.9 ° to 1.2 °. In addition, it is preferable that the half-value width Bf and the half-value width Br are in the range of Bf / Br = 0.6 to 0.85, particularly 0.7 to 0.8. By adjusting the coating layer 6 to the said range, the toughness of the coating layer in a rake face can be improved.

  That is, by setting the half-value width Br to 0.9 or more, the crystal of the coating layer 6 formed on the rake face grows at random, so that the progress of cracks that progress through the interface between the particles is easily deflected. As a result, the toughness of the coating layer 6 on the rake face where a large impact is easily applied is improved.

  In addition, by setting Bf / Br to be 0.6 or more and 0.85 or less, sufficient wear resistance can be exhibited on the flank surface, and sufficient chipping resistance can be exhibited on the rake surface. The balance between wear and fracture resistance can be optimized.

  At this time, it is preferable that the half-value width Bf and the half-value width Br have a peak of the (111) plane X-ray analysis pattern in the range of 2θ = 36.5-38.0 °. Thereby, the residual compressive stress generated at the time of film formation can be optimized. That is, by adjusting 2θ of the half width Bf and the half width Br within the range of 36.5 ° or more and 38.0 ° or less, peeling and chipping of the coating layer due to compressive stress can be suppressed and compression can be performed. The peeling of the film due to the decrease in stress can be suppressed.

  The peak of the X-ray analysis pattern on the rake face can be measured by X-ray diffraction analysis under the same conditions as the method for measuring the half-value width Bf, but the rake face of the cutting tool is attached to the mounting surface of the holder. In order to prevent the occurrence of rattling, there is a portion that is polished, and if an X-ray diffraction analysis of that portion is performed, it is difficult to obtain an accurate value. For this reason, it is desirable to perform X-ray diffraction analysis in a state where the polishing portion is masked or the polishing portion is removed by processing.

[Production method]
Next, as an example of the method for manufacturing a cutting tool of the present invention, a method for manufacturing a throw-away tip for a cutting tool using a tungsten carbide base cemented carbide as a base will be described.

  First, tungsten carbide (WC) powder and cobalt (Co) or nickel (Ni) iron group metal powder are used as raw materials, and the additive is selected from Group 4, 5, 6 metal, Si, Al in the periodic table A mixed powder is prepared by mixing and pulverizing a compound powder of elemental carbide, nitride, oxide, carbonitride, or the like, or a compound compound powder, platinum group element powder or the like.

  The prepared mixed powder is formed by a general forming method and fired in a reducing atmosphere such as vacuum firing or nitrogen atmosphere firing to produce a substrate made of a sintered body.

  A first surface that is a rake face of the cutting tool of the base body, and at least one second surface that is continuous with the first surface and that is a flank face of the cutting tool, and the ridge line between the rake face and the flank face However, it functions as a cutting edge of a cutting tool.

  The obtained substrate may be subjected to blade edge processing such as R-plane honing or C-plane honing as desired.

  Here, according to the present invention, the average arithmetic surface roughness (Ra) of the upper surface (first surface) of the substrate that becomes the rake face 3 as the pretreatment for forming the coating layer 6 is 0.03 to 0.2 μm, By applying a surface treatment so that the average arithmetic surface roughness (Ra) of the side surface (second surface) of the substrate serving as a flank surface is 0.01 to 0.15 μm, the half widths Bf and Br of the coating layer 6 are obtained. Can be easily adjusted within the scope of the present invention.

  As the surface treatment method, it is desirable to perform the processing by a processing method such as shot blasting or a brush because the processing can be evenly performed on the recesses such as the breaker groove for chip disposal.

  At this time, when the surface roughness of the flank 4 is Rf and the surface roughness of the rake face 3 is Rr, the flank 4 is formed when the coating layer 6 is formed by processing so that Rf <Rr. This is desirable because the wear resistance and fracture resistance of the rake face 3 are optimized.

  Here, the measurement method of the surface roughness of the substrate 2 is a stylus type surface roughness measuring device using a stylus type surface roughness measuring device in accordance with JIS B0601'01, with a cutoff value of 0. It can be measured at 25 mm, reference length: 0.8 mm, and scanning speed: 0.1 mm / second.

  When the measurement is performed after forming the coating layer, the interface 9 between the substrate and the coating layer is observed with a scanning electron microscope (SEM) at a magnification of 15000 to measure the surface roughness of the substrate. Specifically, as shown in FIGS. 2 and 3, at the interface 9 between the substrate and the coating layer, the straight line A that is substantially parallel to the substrate passing through the highest point at which the substrate protrudes most and the lowest indented substrate. A straight line B passing through the point and substantially parallel to the substrate is formed. A straight line that passed through the midpoint of the shortest distance between A and B and was substantially parallel to the substrate was defined as a reference line C. Next, the shortest distance between the highest part of the undulating mountain and the deepest part of the valley at the interface between the substrate and the coating layer and the reference line is measured for each mountain and valley, and the average value of the distances is measured on the surface of the substrate. It was rough. The surface roughness of the substrate can be measured in a pseudo manner by measuring the surface roughness of the substrate on each of the rake face and the flank face by the above method and calculating the average.

  After performing the surface treatment, the coating layer 6 is formed under the following conditions by physical vapor deposition (PVD).

  For example, the basic conditions for forming a (Ti, Al) N film are controlled such that the gas pressure during film formation is 2 to 5 Pa, the bias voltage is 15 to 300 V, and the film formation temperature is 500 to 600 ° C.

  Here, according to the present invention, the bias voltage applied to the substrate at the time of film formation is set to 15 to 50 V only for an initial period of about 1 minute, and then changed to 100 to 300 V, whereby the inert gas content in the film is set. Can be controlled within a predetermined range, and the peak intensity due to the (111) plane of the crystal among the peaks detected by the X-ray diffraction method of the coating layer can be maximized.

  In particular, the flow rate ratio of nitrogen and inert gas as the reaction gas introduced during film formation is such that the inert gas / nitrogen = 1 to 3 has a finer crystal structure and abnormally grown particles. Can be reduced, which is desirable.

  Here, when a plurality of types of inert gas are used, the ratio of the flow rate of nitrogen and the total flow rate of the inert gas is adjusted to the above ratio.

Furthermore, the target to be used is preferably a titanium aluminum alloy having a composition (x: 0.4 to 0.7) made of (Ti _x , Al _1-x ).

  Further, a hard layer made of titanium nitride (TiN), titanium carbonitride (TiCN), aluminum oxide (Al 2 O 3) or the like is formed on the surface of the coating layer 6 of the present invention or between the substrate 2 and the coating layer 6. Also good.

[Cutting method]
4 to 6 show process diagrams of the cutting method of the present invention. First, as shown in FIG. 4, the cutting tool 11 (in the drawing, a turning tool in which a cutting insert is attached to a holder is described as an example) is brought close to the work material 10. Note that the cutting tool 11 and the work material 10 may be relatively close to each other. For example, the work material 10 may be close to the cutting tool 1.

  Thereafter, at least one of the work material 10 and the cutting tool 11 is rotated. In addition, in the figure, what the workpiece 10 rotates is illustrated. Next, as shown in FIG. 5, the work piece 10 is cut by bringing the cutting edge portion of the cutting insert into contact with the work material 10. Thereafter, the cutting tool 11 is separated from the work material 10 as shown in FIG. In addition, when continuing a cutting process, the state which rotated the cutting tool 11 and the cut material 10 relatively is hold | maintained, and the process which makes the cutting blade of the cutting tool 11 contact the location used as the cut material 10 repeat.

  Examples of the invention will be described below.

Example 1
Crushing and mixing 87% by mass of WC powder with an average particle size of 0.7 μm, 10% by mass of Co powder, 2% by mass of TiC powder, and 1% by mass of NbC powder, and forming the resulting mixed powder into CNMG120408 shape by press molding Then, it was fired in a vacuum atmosphere to prepare a cemented carbide substrate.

The rake face and flank face of the obtained cemented carbide substrate were subjected to surface treatment by shot blasting so as to have the surface roughness shown in Table 2, and then the film formation conditions shown in Table 1 using the arc ion plating method. (Ti, Al) N film was formed at

Next, the half-value width Bf of the (111) plane X-ray analysis peak on the flank of the obtained sample and the half-value width Br of the (111) plane X-ray analysis peak on the rake face are calculated using CuKα rays. The X-ray output was 40 kV, 40 mA, and X-ray diffraction analysis was performed under the condition of a step width of 0.02 °. Bf, Br, and Bf / Br are shown in Table 2, respectively. The interface 9 was observed with a scanning electron microscope (SEM) at 15000 times, and the surface roughness of the substrate was measured. Specifically, at the interface 9 between the substrate and the coating layer, a straight line A that is substantially parallel to the substrate passing through the highest point from which the substrate protrudes and a straight line that is substantially parallel to the substrate through the lowest point where the substrate is most recessed. B is formed. A straight line that passed through the midpoint of the shortest distance between A and B and was substantially parallel to the substrate was defined as a reference line C. Next, the shortest distance between the highest part of the undulating mountain and the deepest part of the valley of the interface 9 between the substrate and the coating layer and the reference line is measured for each mountain and valley, and an average value of the distances is measured. The surface was rough. According to the above method, the surface roughness of the substrate was measured at five points on each of the rake face and the flank face, and the average was calculated for each sample. The results are shown in Table 2.

  Further, a cutting test was performed on the prepared sample under the following conditions.

(Continuous cutting conditions)
Work material: SUS304 Cylindrical tool shape: CNMG120408
Cutting speed: 200 m / min Feed speed: 0.25 mm / rev
Cutting depth: 1.5mm
Cutting time: 15 minutes Cutting state: Wet evaluation with a mixture of emulsion 15% + water 85% Item: Observe the cutting edge with a microscope and measure the amount of flank wear and tip wear (intermittent cutting conditions)
Work material: SUS304 Four grooved cylindrical material Tool shape: CNMG120408
Cutting speed: 120 m / min Feed speed: 0.2 mm / rev
Cutting depth: 1mm
Cutting state: Wet evaluation item with a mixture of 15% emulsion + 85% water: Observation of the state of the cutting edge when the number of impacts leading to the defect and the number of impacts reached 1000 times

  From Table 3, Sample No. whose half width Bf is outside the range of the present invention is shown. In Nos. 15 to 18, the progress of flank wear and tip wear was rapid, and the strength of the blade edge was lowered by the rapid progress of wear, and both the wear resistance and fracture resistance were low.

  On the other hand, sample Nos. With half width Bf within the scope of the present invention. 1 to 14 exhibited high performance in both wear resistance and fracture resistance. In particular, a particularly high performance was exhibited in a sample in which the half-value width Br of the rake face was adjusted.

As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to the said embodiment, It cannot be overemphasized that it can be made arbitrary, unless it deviates from the objective of invention.

It is a schematic perspective view of the cutting tool concerning one Example. It is a schematic sectional drawing of the cutting tool concerning one Example. It is an enlarged view of the interface part (E part) of the base | substrate and coating layer of FIG. It is process drawing of the cutting method of this invention. It is process drawing of the cutting method of this invention. It is process drawing of the cutting method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Cutting tool 2 Base | substrate 3 Rake face 4 Relief face 5 Cutting edge 6 Covering layer 9 Base | substrate surface (interface of base | substrate and coating layer)
10 Work material

Claims (4)

A substrate and a coating layer containing Ti and Al formed on the surface of the substrate;
In the cutting tool, the base body has a rake face on an upper surface, a flank face on a side surface, and a cutting edge on at least a part of an intersecting ridge line between the rake face and the flank face.
Among the X-ray analysis patterns of the coating layer on the flank, the half width Bf of the peak attributed to the (111) plane is 0.6 ° or more, and among the X-ray analysis patterns of the coating layer on the rake surface, The half-value width Br of the peak attributed to the (111) plane is 0.9 ° or more, and the half-value width Bf and the half-value width Br are within the range of Bf / Br = 0.6 to 0.85. A cutting tool characterized by being. 2. The cutting tool according to claim 1 , wherein the half-value width Bf and the half-value width Br have a peak of an X-ray analysis pattern in a range of 2θ = 36.5 to 38.0. The coating layer, cutting tool according to claim 1 or 2, characterized in that it consists of (Ti, Al) N. A cutting method of cutting a work material using the cutting tool according to any one of claims 1 to 3,
A proximity process for relatively bringing the cutting tool and the work material close together;
A cutting step of cutting the work material by rotating at least one of the cutting tool and the work material, bringing the cutting blade of the cutting tool into contact with the work material; and
A cutting method comprising: a separation step of relatively separating the work material and the cutting tool.

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