JP4583222B2 - Hard sintered body cutting tool and manufacturing method thereof - Google Patents

Description

The present invention relates to a hard sintered cutting tool and a manufacturing method, and more particularly to a cutting tool in which a cutting edge is formed using an electron beam and a manufacturing method thereof.

A cutting tool made of a diamond sintered body and / or a cubic boron nitride sintered body, or a ceramic, which is a hard material, often has no chip breaker. Machining using such tools cannot process the generated chips, so machining defects in automated lines and the like due to chip entanglement on the workpiece and holder and chip accumulation inside the machine tool ( Machine stoppage, degradation of machined surface quality, etc.). As a result, a reduction in processing efficiency was inevitable. In order to eliminate such trouble due to chips, it is very effective to have a chip breaker formed in a convex shape or a combination of convex and concave shapes on the tool rake face.

As shown schematically in FIG. 5, the prior art in this type of tool has a complicated three-dimensional shape formed on the surface of a diamond sintered body and / or a cubic boron nitride sintered body by a specially adjusted laser beam machine. The chip breaker is constructed, and the surface damage layer on the surface is reduced or removed by the free abrasive polishing method, thereby obtaining a long-life throw-away tip with less tool chipping and welding (for example, Patent Document 1). reference).
JP 2004-223648 A

In the throw-away tip disclosed in Patent Document 1, roughening or thermal cracking of the tool rake face surface due to a thermal drop between the heating region by laser processing locally reaching 1000 to 3000 ° C. and its periphery. As a result, the cutting edge is lost at a relatively early stage of cutting. In addition, chipping on the tool rake face due to deterioration of surface roughness on the surface of the damaged layer formed by laser processing, conversion of diamond to graphite, or conversion of cubic boron nitride to hexagonal boron nitride, etc. Therefore, the chip rake face is welded and chip disposal becomes difficult. In order to solve these problems, the damage layer is reduced or removed by polishing the entire tool rake face of the hard sintered body with a polishing method using loose abrasive grains. It is carried out.

However, since the processing damage layer remains in a deep region from the surface in the heating region of the laser that reaches 1000 to 3000 ° C. locally, the processing damage layer is reduced to an extent that does not adversely affect the cutting performance of the tool. A very long polishing process is required for removal. On the other hand, if the temperature in the heating area of the laser is suppressed to about 1000 ° C in order to make the processing damage layer shallow, a chip breaker formed in a convex shape or a combination of convex and concave shapes on the tool rake face is formed. It takes a very long time. In addition, diamond that cannot be converted to graphite or cubic boron nitride that cannot be converted to hexagonal boron nitride remains on the surface of the tool rake face, which lowers the efficiency of subsequent polishing.

The present invention has been made in view of the above circumstances, and its object is to provide a hard sintered body cutting tool capable of efficiently reducing and removing a processing damage layer on a tool rake face in a short time, and It is in providing the manufacturing method.

In order to solve the above problems, the present invention provides a hard sintered body cutting tool having at least a cutting edge made of a diamond sintered body and / or a cubic boron nitride sintered body, at least on the tool rake face surface of the cutting edge. After irradiation with the electron beam, diamond and / or cubic boron nitride within a depth of 20 μm or less from the tool rake face surface is converted into a ceramic structure, and then the tool rake face surface contains free abrasive grains. The hard sintered body cutting tool is characterized in that the ceramic structure is reduced or removed by being polished by the polishing method used, and the tool rake face is finished smoothly.

According to another invention, in a hard sintered body cutting tool having at least a cutting edge made of ceramic, at least a tool rake face surface of the cutting edge is irradiated with an electron beam, so that the depth of the tool rake face is within 20 μm. After the surface modification of the ceramics in the range, the tool rake face is polished by a polishing method using loose abrasive grains, so that the tool rake face is finished smoothly. This is a sintered body cutting tool.

In the hard sintered body cutting tool, a chip breaker is preferably formed on the surface of the tool rake face before the electron beam is irradiated. Moreover, it is preferable that the surface roughness of the smooth tool rake | polishing surface grind | polished by the grinding | polishing method using the said loose abrasive grain exists in the range of the maximum height Rz (JIS B0601) 0.5-15 micrometers.

The manufacturing method of the present invention irradiates at least the tool rake face surface of the cutting edge of a hard sintered body cutting tool having at least a cutting edge made of a diamond sintered body and / or a cubic boron nitride sintered body. Thus, a first step of converting diamond and / or cubic boron nitride within a range of 20 μm or less from the tool rake face into a ceramic structure, and polishing of the tool rake face surface using loose abrasive grains A method for producing a hard sintered body cutting tool, comprising a second step of reducing or removing the ceramic structure and finishing to a smooth tool rake face by polishing by a method.

In another manufacturing method of the present invention, at least a tool rake face surface of the cutting edge of a hard sintered body cutting tool having at least a cutting edge made of ceramics is irradiated with an electron beam so that the tool rake face can be removed. A first step of modifying the surface of the ceramic within a depth of 20 μm and a surface of the tool rake face polished by a polishing method using loose abrasive grains to finish a smooth tool rake face. It is a manufacturing method of the hard sintered compact cutting tool characterized by including 2 processes.

According to the above-mentioned hard sintered body cutting tool and method for manufacturing the same, diamond and / or cubic boron nitride constituting the cutting blade is formed on the surface of the tool rake surface of the cutting blade irradiated with the electron beam, respectively, in graphite, hexagonal form. A ceramic structure converted into crystalline boron nitride is formed within a depth within 20 μm, preferably within 10 μm, from the surface of the tool rake face. Since the ceramic structure has a lower hardness than diamond and cubic boron nitride, the surface of the rake face of the tool can be efficiently smoothed by a polishing method using loose abrasive grains. The consumption of the member is suppressed.

The above electron beam machining can be performed on the tool rake face on which the chip breaker is formed. The chip breaker is formed in one of a convex shape, a concave shape or a combination of a convex shape and a concave shape, and as a processing method for forming the chip breaker, a die pressing process in a press sintering stage, a press sintering process is performed. Examples include grinding with a later grinding wheel, laser processing after press molding, etc. Among these processing methods, laser processing increases the efficiency of forming a chip breaker with a high-power laser, and so-called three-dimensional. This is preferable in that it can easily cope with a relatively complicated shape called a chip breaker or a fine shape.

Regardless of the unevenness of the chip breaker formed on the rake face of the tool, the depth of the ceramic structure is formed almost uniformly in the electron beam processed part, so that the ceramic structure can be efficiently reduced or removed by subsequent polishing. can do. In particular, when a chip breaker is formed on the surface of a tool rake face by laser processing, rough or thermal cracks on the surface of the tool rake face, which are the causes of chipping at the initial stage of cutting, remain. It is possible to reduce or remove the roughening and thermal cracks in a short time. When the chip breaker is formed on the tool rake face, in the chip breaker formed in a convex shape, the wall surface constituting the convex portion restrains the chip, thereby promoting the curl of the chip and improving the chip discharging property. In the chip breaker formed to have a concave shape, the concave portion increases the rake angle of the cutting edge, thereby reducing the cutting resistance. When formed into a shape combining a convex shape and a concave shape, the above-described effects can be achieved.

If the surface roughness of the tool rake face is not more than the maximum height Rz 15 μm, the friction with the chip can be suppressed, so that the occurrence of welding is suppressed and the life of the cutting edge is improved. When the maximum height Rz is less than 0.5 μm, it becomes difficult to restrain the chips by the chip chip breaker formed in a convex shape, and there is a concern that the chip disposal is deteriorated.

The diamond sintered body in the present invention refers to a polycrystalline diamond sintered body containing diamond crystal grains in a range of 80 to 98% by volume and sintered using a binder phase such as Co or WC. Further, the cubic boron nitride sintered body in the present invention contains 35% by volume or more of cubic boron nitride, and includes a binder phase such as TiC-Al, TiCN-Al, WC-Co-Al, TiN-WC-Al. A cubic boron nitride sintered body sintered using or a cubic boron nitride sintered body obtained by sintering only cubic boron nitride in which no binder phase as described above is used. Further, the ceramic in the present invention refers to silicon nitride ceramics, alumina ceramics, or known ceramics other than the above ceramics.

An embodiment of a hard sintered body cutting tool according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram of a state of electron beam machining in the manufacturing process of the hard sintered body cutting tool, and FIG. 2 is an enlarged view schematically showing a state after electron beam machining in part A of FIG. . FIG. 3 is an enlarged view schematically showing a state of the polishing process in the portion A of FIG. FIG. 4 is an enlarged view schematically showing a state after the polishing process in the portion A of FIG. FIG. 5 is a view schematically showing a state of laser processing on the tool rake face of the hard sintered body cutting tool.

Although a hard sintered body cutting tool to which the present invention is applied is not shown, for example, a diamond sintered body and / or a cubic boron nitride sintered body is formed into a two-layer structure integrated with a cemented carbide substrate, which is made of cemented carbide. A throw-away tip brazed to a corner portion of an alloy tip body, or a cutting tool such as a cutting tool, a milling cutter, or a drill, which is brazed directly to a holder body. The sintered body may be brazed directly to the chip body without using the cemented carbide substrate. In the case of a throw-away tip, the throw-away tip is fixed to a tip seat formed on the tool holder by using a known fixing means such as a wedge member, a screw member, or a presser foot to constitute a cutting tool. The embodiment of the present invention to be described below relates to a characteristic configuration of a cutting edge vicinity, particularly a tool rake face, which greatly affects cutting performance in the above cutting tool.

In the hard sintered body cutting tool according to the present embodiment, at least the cutting edge 4 contains 35% by volume or more of cubic boron nitride, TiC—Al, TiCN—Al, TiN—Al, WC—Co—Al, TiN—. The cubic boron nitride sintered body is sintered using a binder phase such as WC-Al. Moreover, the sintered compact which sintered only the cubic boron nitride in which the above binder phases are not used at all may be sufficient. A chip breaker 3 having a convex shape, a concave shape, or a combination of a convex shape and a concave shape is formed in advance on the surface of the tool rake face 2 of the cutting edge 4. As a method of forming the chip breaker 3 in the cubic boron nitride sintered body, for example, press molding by press sintering, molding by grinding using a grindstone after press sintering, electric discharge machining, laser beam or electron beam is used. This is done by the melt removal process. If the chip breaker 3 is formed by irradiating a laser beam or an electron beam to melt and remove the surface structure of the tool rake face as schematically shown in FIG. 5, the above chip breaker is formed by a high-power laser beam or electron beam. 3 has a high processing efficiency, can be molded in a complicated and fine shape, and has the advantage that the degree of freedom of the shape of the chip breaker 3 is increased.

As schematically shown in FIG. 1, the electron beam 10 is applied to the surface of the tool rake face 2. An electron beam is applied to the surface of the tool rake face 2 that is present at least in the vicinity of the cutting edge 4 including the ridgeline of the cutting edge 4 and is in contact with the chip. As already known, electron beam machining is performed by irradiating the surface of the work piece set on a table in a vacuum vessel with an electron beam emitted from an electron gun in a vacuum state. In this embodiment, the surface of the tool rake face 2 heated by irradiating the electron beam 10 whose output is adjusted and the region in the vicinity of the surface are heated by melting or removing the surface of the part. Rather than being melted away, the cubic boron nitride is simply converted into a ceramic structure 7 containing hexagonal boron nitride. Further, the electron beam is heated so that the region is not removed and is heated to such a temperature that a range within 20 μm, preferably within 10 μm, from the surface of the tool rake face 2 is converted into the ceramic structure 7. 10 outputs are adjusted.

After electron beam machining, as schematically shown in FIG. 2, a ceramic structure 7 containing hexagonal boron nitride remains on the surface of the tool rake face 2 and in the vicinity of the surface. Thereafter, as shown in FIG. 3, the surface of the tool rake face 2 is polished by a polishing method using loose abrasive grains 20, and the ceramic structure 7 is reduced or removed, and the surface roughness of the surface of the tool rake face 2 is reduced. Is improved (see FIG. 4). The surface roughness of the tool rake face 2 finished by the polishing process is preferably in the range of the maximum height Rz (JIS B0601) of 0.5 to 15 μm.

As other embodiment, the hard sintered compact cutting tool 1 in which at least the cutting edge 4 consists of a diamond sintered compact may be sufficient. That is, the diamond sintered body contains diamond crystal grains having an average grain size in the range of 3 to 50 μm in a range of 80 to 98% by volume, and is sintered using a binder phase such as Co or WC. It is a crystalline diamond sintered body. A chip breaker 3 having a convex shape, a concave shape, or a combination of a convex shape and a concave shape is formed in advance on the surface of the tool rake face 2 of the cutting edge 4, and the forming method will be described in the previous embodiment. A molding method similar to that described above is applied.

As schematically shown in FIG. 1, the electron beam 10 is applied to the surface of the tool rake face 2. The electron beam 10 is applied to the surface of the tool rake face 2 that is present at least in the vicinity of the cutting edge 4 including the ridgeline of the cutting edge 4 and is in contact with the chip, at least the part that is deeply involved in the cutting performance. Even in this case, the surface of the tool rake face 2 heated by irradiating the electron beam 10 whose output is adjusted and the region near the surface are not melted and removed, but the diamond is converted into a ceramic structure 7 containing graphite. Just do it. Further, the electron beam is heated so that the region is not removed and is heated to such a temperature that a range within 20 μm, preferably within 10 μm, from the surface of the tool rake face 2 is converted into the ceramic structure 7. 10 outputs are adjusted.

After the electron beam machining, as schematically shown in FIG. 2, a ceramic structure 7 containing graphite remains on the surface of the tool rake face 2 and in the vicinity of the surface. Thereafter, as shown in FIG. 3, the surface of the tool rake face 2 is polished by a polishing method using loose abrasive grains 20, and the ceramic structure 7 is reduced or removed and the surface roughness of the surface of the tool rake face 2 is reduced. Is improved (see FIG. 4). The surface roughness of the tool rake face 2 finished by the polishing process is preferably in the range of the maximum height Rz 0.5 to 15 μm.

In the two embodiments described above, as a polishing method for the tool rake face 2 on which the chip breaker 3 is formed, a polishing method using loose abrasive grains 20 is preferable. For example, alumina, silicon carbide, boron nitride, A method of irradiating free abrasive grains 20 made of a material such as diamond with a medium such as compressed air or high-pressure fluid, and the above-mentioned free abrasive grains 20 are made of nylon, polypropylene, pyrene wool, enviro, polyester or aramid as illustrated in FIG. A method of rotating or swinging with a resin 30 such as horse hair, pig hair, wool, or the like, or a brush 30 made of plant fiber such as fern or palm, or the above-described free abrasive 20 A polishing method using In the case where the loose abrasive grains 20 made of diamond are used, high polishing power and durability are particularly obtained in the grinding of the hard sintered body cutting tool 1 made of a hard diamond sintered body and / or a cubic boron nitride sintered body. Is demonstrated.

According to each of the above-described embodiments, the surface of the tool rake face 2 is heated by the electron beam 10 whose output is adjusted, so that a diamond is placed within a depth of less than 10 μm from the surface of the tool rake face 2 and the surface. In addition, a ceramic structure having a hardness lower than that of cubic boron nitride remains, so that the ceramic structure 7 is reduced or removed in the polishing process using the free abrasive grains 20 and the surface of the tool rake face 2 is removed. The time required to improve the surface roughness is greatly reduced, and the efficiency of improving the surface roughness is greatly improved. In particular, when the chip breaker 3 is formed on the surface of the tool rake face 2 by laser processing, a long time polishing process is required to reduce or remove the surface roughness and thermal cracks of the tool rake face 2. After forming the chip breaker 3 by the electron beam machining on the surface of the tool rake face 2, the roughness of the tool rake face 2 is improved and the hardness of the tool rake face 2 is relatively shallow from the surface. Since the low ceramic structure 7 remains, the time required for the polishing process can be greatly shortened and the life of the brush rotating or swinging together with the loose abrasive 20 and the flow-off abrasive 20 is extended.

The present invention is also applicable to the hard sintered body cutting tool 1 in which the cutting edge 4 is made of ceramics. As the ceramic, silicon nitride ceramic or alumina ceramic is typically used, but other known ceramics may be used. The electron beam 10 is applied to the surface of the tool rake face 2. By irradiation of the electron beam 10 whose output is adjusted to the surface of the tool rake face 2 that exists in the vicinity of the cutting edge 4 including at least the ridgeline of the cutting edge 4 and that is in contact with the chip, at least a part deeply involved in the cutting performance The surface of the heated tool rake face 2 and the area near the surface are dissolved. Thereafter, when irradiation with the electron beam 10 is completed and the melted area is cooled, surface roughness and thermal cracks on the tool rake face 2 caused by grinding, electric discharge machining or laser machining before the electron beam machining are reduced. Alternatively, the time required for polishing the surface of the tool rake face 2 by polishing after the electron beam processing is shortened. The surface of the tool rake face 2 and the region in the vicinity of the surface are heated to a temperature at which the depth of the tool rake face 2 is not removed and the range within the depth of 20 μm, preferably within 10 μm, is melted from the surface of the tool rake face 2. Thus, the output of the electron beam 10 is adjusted. Furthermore, the output of the electron beam 10 is also adjusted according to the ceramic composition.

The depth of the ceramic structure 7 remaining in the vicinity of the surface of the tool rake face 2 by the electron beam machining is almost uniform without being affected by the uneven shape of the chip breaker 3. Smoothness is also improved. Further, in the case of a complicated shape such as a three-dimensional chip breaker or for a finish cutting in which a complicated and fine concave and / or convex shape is formed at a position very close to the cutting edge, during polishing, Although it is difficult for the brush to hit the corner where the wall surfaces constituting the chip breaker 3 intersect in a concave shape like the A portion in 1, the depth is uniform from the surface of the tool rake face 2 to a very shallow range as described above. The remaining ceramic structure 7 can be uniformly reduced or removed.

The effect of the chip breaker 3 formed on the surface of the tool rake face 2 on the cutting performance is as follows. When the chip breaker 3 is formed in a convex shape, the wall surface constituting the convex portion restrains the chip, thereby promoting the curling of the chip and improving the chip discharging property, and has a concave shape. When formed, the concave portion increases the rake angle of the cutting edge 4, so that the cutting resistance is reduced. When formed into a shape combining a convex shape and a concave shape, the effects of both the convex portion and the concave portion are exhibited.

In each embodiment, the surface roughness of the tool rake face 2 finished by polishing is preferably in the range of the maximum height Rz of 0.5 to 15 μm. This is because if the surface roughness of the tool rake face 2 has a maximum height Rz of 15 μm or less, the friction with the chips can be suppressed, so that the occurrence of welding is suppressed and the life of the cutting edge 4 is improved. When the maximum height Rz is less than 0.5 μm, it becomes difficult to restrain the chips by the chip breaker 3 formed in a convex shape, and there is a possibility that long elongated chips are generated and the chip processability is deteriorated.

It is the figure which showed typically the state of the electron beam irradiation in the manufacture process of the hard sintered compact cutting tool to which this invention is applied. It is the enlarged view which showed typically the state after the electron beam irradiation in the A section of FIG. It is the enlarged view which showed typically the state of the grinding | polishing process in the A section of FIG. It is the enlarged view which showed typically the state after the grinding | polishing process in the A section of FIG. It is the figure which showed typically the state of the laser processing to the tool rake face of a hard sintered compact cutting tool.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hard sintered body cutting tool 2 Tool rake face 3 Chip breaker 4 Cutting edge 5 Relief face 6 Diamond and / or cubic boron nitride crystal grain 7 Ceramic structure 10 Electron beam 11 Laser beam 20 Free abrasive grain 30 Brush 100 Electron beam Processing equipment 110 Laser processing equipment

Claims (6)

In a hard sintered body cutting tool in which at least the cutting edge is composed of a diamond sintered body and / or a cubic boron nitride sintered body,
After at least the surface of the tool rake face of the cutting edge is irradiated with an electron beam, diamond and / or cubic boron nitride within a depth of 20 μm or less from the surface of the tool rake face is converted into a ceramic structure, The tool rake face surface is polished by a polishing method using loose abrasive grains to reduce or remove the ceramic structure, and the tool rake face is smoothly finished. Combined cutting tool. In a hard sintered cutting tool with at least the cutting edge made of ceramics,
At least the tool rake face surface of the cutting edge is irradiated with an electron beam, so that the ceramic in the range of 20 μm or less from the tool rake face surface is surface-modified, and then the tool rake face surface is free abrasive grains. The hard sinter cutting tool, wherein the tool rake face is finished smoothly by being polished by a polishing method using The hard sintered body cutting tool according to claim 1 or 2, wherein a chip breaker is formed on a surface of the tool rake face before the electron beam is irradiated. The surface roughness of the smooth tool rake face polished by the polishing method using the loose abrasive grains is in the range of the maximum height Rz (JIS B0601) of 0.5 to 15 µm. The hard sintered compact cutting tool according to any one of 3. By irradiating at least the tool rake face surface of the cutting edge of the hard sintered body cutting tool, at least the cutting edge of which is a diamond sintered body and / or cubic boron nitride sintered body, with the electron beam, the tool rake face Polishing the surface of the tool rake face by a polishing method using loose abrasive grains, and a first step of converting diamond and / or cubic boron nitride within a depth of 20 μm or less into a ceramic structure, A method for manufacturing a hard sintered body cutting tool, comprising: a second step of reducing or removing the ceramic structure and finishing a smooth tool rake face. By irradiating at least the tool rake face surface of the cutting edge of the hard sintered body cutting tool having a cutting edge made of ceramics with an electron beam, the surface modification of the ceramic within a depth of 20 μm or less from the tool rake face is performed. Hard sintering characterized by including the 1st process which makes quality, and the 2nd process which finishes the said tool rake face surface by the grinding | polishing method using a loose abrasive to make a smooth tool rake face. Manufacturing method of body cutting tool.

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