JP5053561B2 - Cutting tool and manufacturing method thereof - Google Patents

Description

  The present invention relates to a cutting tool, and more particularly to a cutting tool suitable for high-speed cutting of a high hardness steel material.

  In high-speed cutting of a hard steel material, the interface temperature between the cutting surface of the cutting tool and the workpiece increases to nearly 1000 ° C., and the component of the workpiece may seize on the cutting tool and adhesion may occur. When adhesion of the work piece component to the cutting tool occurs, the blade surface of the cutting tool is damaged, and the cutting function is significantly reduced.

  As a cutting tool that receives such a severe heat history, conventionally, a cemented carbide such as tungsten carbide or a cermet such as titanium carbonitride has been used as a base material and the surface thereof has been coated.

  For example, Patent Document 1 discloses that “a carbide layer, nitride layer, carbonitride of Ti which is formed by vapor deposition on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet. A lower layer having an average layer thickness of 3 to 20 μm, comprising a Ti compound layer composed of one or more of a physical layer, a carbonate layer and a carbonitride layer, and (b) vapor deposition A heat-transformed α-type aluminum oxide layer having a structure in which the heat-transformed aluminum oxide having a κ-type or θ-type crystal structure is subjected to a heat-transformation process to form an α-type crystal structure, and heat-transformation cracks are dispersed and distributed. And an upper layer having an average layer thickness of 3 to 15 μm, (c) a deposited κ-type aluminum oxide layer having a κ-type crystal structure in a vapor-deposited state, and a flat layer of 0.5 to 2 μm. A surface-coated cermet cutting tool having a thermal shock resistance with an excellent hard coating layer formed by forming a hard coating layer composed of a surface layer having a layer thickness as described above (a) to (c) ”has been proposed Yes.

  Patent Document 2 discloses that “a carbide layer, nitride layer, carbonitride layer of Ti formed by vapor deposition on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet” A lower layer composed of a Ti compound layer having an average layer thickness of 3 to 20 μm, and (b) formed by vapor deposition. In this state, aluminum oxide having a κ-type crystal structure is subjected to a heat transformation treatment to obtain an α-type crystal structure, which has a structure in which transformation cracks generated by the heat transformation treatment are distributed and distributed, and an average layer thickness of 3 to 15 μm. A composite 2 composed of a lower layer of a heat-transformed α-type aluminum oxide layer having an upper layer of a vapor-deposited α-type aluminum oxide layer having a vapor-deposited α-type crystal structure having an average layer thickness of 0.5 to 2 μm Heavy α-type aluminum oxide A surface-coated cermet having excellent thermal shock resistance, characterized in that a hard coating layer composed of an upper layer made of a humum layer, the lower layer (a) and the upper layer (b) is formed. A “cutting tool” has been proposed.

  Patent Document 3 states that “a carbide layer, nitride layer, carbonitride of Ti which is formed by chemical vapor deposition on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet. A lower layer composed of a Ti compound layer having a total average layer thickness of 3 to 20 μm, comprising one or more of a layer, a carbonate layer, and a carbonitride layer, and (b) chemical vapor deposition In the formed state, aluminum oxide having a κ-type crystal structure is subjected to a heat treatment to transform into an α-type crystal structure, and a structure in which transformation cracks generated by the heat treatment are distributed and distributed, and an average layer of 1 to 15 μm A lower layer of a heat-transformed α-type aluminum oxide layer having a thickness, and a vapor-deposited α-type aluminum oxide layer having an α-type crystal structure in a state of chemical vapor deposition and having an average layer thickness of 0.1 to 2 μm. Upper layer A hard coating comprising: an upper layer composed of a composite double α-type aluminum oxide layer, and a hard coating layer composed of the lower layer (a) and the upper layer (b). A surface-coated cermet cutting tool having excellent thermal shock resistance in a layer ”has been proposed.

Patent Document 4 discloses that “(a) an aluminum oxide layer having an average layer thickness of 0.2 to 3 μm as an upper layer on the surface of a cermet substrate made of a tungsten carbide base cemented carbide or a titanium carbonitride cermet, (b ) Surface-coated cermet cutting formed by physical vapor deposition of a composite nitride layer of Al and Ti having an average layer thickness of 0.8 to 8 μm as a lower layer, and a hard coating layer composed of (a) and (b) above In the tool, in the lower layer, along the layer thickness direction, the Al highest content point and the Al lowest content point are alternately present repeatedly at a predetermined interval, and the Al minimum content is from the Al highest content point. Point, a component concentration distribution structure in which the content ratios of Al and Ti continuously change from the lowest Al content point to the highest Al content point, respectively, and the lowest Al content point is represented by a composition formula: (Al _{1 -X} Ti _X N (provided that an atomic ratio, X is shows a 0.35-.60), the Al highest content point, the composition _{formula: (Al 1-Y Ti Y} ) N ( provided that an atomic ratio, Y is 0 0.05 and 0.30), and the interval between the adjacent Al minimum content point and Al maximum content point adjacent to each other is 0.01 to 0.1 μm. A surface-coated cermet cutting tool that exhibits excellent wear resistance with a hard coating layer by high-speed cutting characterized by comprising the above.

  Patent Document 5 states that “in a diamond-coated hard member in which a diamond and / or diamond-like carbon coating is coated on a substrate, the average surface roughness of the substrate adjacent to the coating is 0.1 μm to Ra in terms of Ra”. The average surface roughness of the coating is adjusted to 1.5 μm or less in Ra display, and the average surface roughness of the coating is expressed as Ra (c). A diamond-coated hard member with an adjusted surface roughness, characterized in that Ra (c) ≦ Ra (s) when the average surface roughness is expressed as Ra (s) ”has been proposed.

JP 2004-188502 A JP 2004-188500 A JP 2004-188575 A JP 2004-351540 A Japanese Patent Laid-Open No. 10-287491 Japanese Patent No. 3376334

  The surface-covered cermet cutting tools proposed in Patent Documents 1 to 4 above are based on the study of the composition of the hard protective film layer. In any document, the mother before forming the hard protective film layer is used. There is no mention of pre-treating the material. Further, in Patent Document 5, by adjusting the surface roughness, diamond nuclei can be easily formed in a large amount at the time of film formation on the surface of the substrate, and a dense film can be obtained. The advantages and the point that it is excellent in film quality are mentioned as advantages.

  However, as will be described later, the inventors' research has revealed that the cutting life of cutting tools used for high-speed cutting of high-hardness steel materials cannot be explained only by adjusting the surface roughness.

  From the viewpoint of improving the cutting life, the inventors have intensively studied the pretreatment applied to the tool base material (metal sintered body) before forming the hard protective film layer, and completed the present invention.

  The present invention has been made to solve such a problem, and an object thereof is to provide a cutting tool having an excellent tool life.

  The gist of the present invention is a cutting tool shown in the following (1) and a manufacturing method of the cutting tool shown in the following (2).

(1) abrasive grains collide morphism injection soft particles formed by the composite using a polymeric resin sintered metal surface composed of superhard material, a mirror surface shape of that in the submicron range meter A cutting tool characterized by forming a hard protective film layer by dry coating after processing.

(2) abrasive grains collide morphism injection soft particles formed by the composite using a polymeric resin sintered metal surface composed of superhard material, a mirror surface shape of that in the submicron range meter A manufacturing method of a cutting tool, wherein a hard protective film layer is formed by dry coating after processing.

  In the above (1) and (2), it is desirable that the hard protective film layer is a coating layer mainly composed of metal carbide, metal nitride, metal oxide or a composite compound thereof. Further, the cutting tool can be used as, for example, a thread cutting chether.

  According to the present invention, since the adhesion between the tool base material (metal sintered body) and the hard protective film layer can be improved, a cutting tool having a long tool life can be provided. This cutting tool is particularly useful for a thread cutting chaser used for severe cutting conditions such as thread cutting of high hardness steel materials.

1. Surface cleaning and surface shape processing by soft particle injection Surface cleaning and surface shape processing by soft particle injection (hereinafter referred to as vapor-phase injection lapping method) is a method in which soft particles are injected and collided with an abrasive at high speed. In this method, the surface of the material to be polished is cleaned and the surface shape is mirror-finished in a submicrometer range. The soft particles are particulate abrasives in which a micrometer diameter abrasive grain is used as a core material, and the periphery of the core material is covered with a polymer resin.

  The normal lapping process is a process performed while sandwiching and rotating the upper and lower surfaces of the material to be polished with flat plates. At this time, since an aqueous dispersion of alumina or glass fine powder having a particle size on the order of submicron is poured into the sliding interface as an abrasive, a wet process is performed. Since such a lapping process is limited to the lapping of a planar body, lapping of the R portion, the inclined portion, etc. is difficult in terms of structure. From such a viewpoint, the present inventors paid attention to a vapor-phase injection wrapping method that can also wrap the R region and the inclined region.

  Therefore, as a result of studying the lapping of the tool base material (metal sintered body composed of super hard material) by the vapor injection lapping method, the vapor injection lapping uniformly adjusts the tool base surface roughness, In addition to improving the adhesion to the hard protective film layer, it has been found that impurities on the surface of the tool base material that cannot be removed by normal wet cleaning can be physically removed. That is, according to the vapor phase injection lapping method, the adhesion between the tool base material and the hard protective film layer, which cannot be explained only by the surface roughness, can be improved, and the tool life can be dramatically improved. It can be done. For this reason, in the present invention, the tool base material before forming the hard protective film layer is subjected to a lapping process by a vapor-phase injection lapping method.

  Here, as the abrasive grains, one or more of diamond, silicon carbide, and alumina can be used. As a grain size of this abrasive grain, it is good to use a 3000-10000 mesh thing. Although it does not specifically limit as multicorn, The gelatin which has desired elasticity and adhesiveness by containing water can be used. When gelatin is used, the diameter of the multi cone is preferably 0.1 to 2 mm. The multi-liquid can contain water-soluble oil as an evaporation preventing material. As the evaporation inhibitor, for example, ethylene glycol, sorbitol and the like can be used.

In addition, although it does not specifically limit as a cemented carbide material which comprises a tool base material, the cemented carbide represented by WC-TiC-5% Co etc., TiC-20% TiN-15% WC-10% Mo ₂ The cermet represented by C-5% Ni etc. is mentioned. Among these, it is desirable to use cemented carbide from the viewpoint of thermal conductivity and from the viewpoint of alleviating thermal stress at the interface with the hard protective film layer during cutting.

2. Regarding the hard protective film layer The cutting tool of the present invention includes a physical vapor deposition method (PVD method) represented by a sputtering method, an arc ion plating method, or the like, or a thermal CVD method and a plasma CVD method. A hard protective film layer is formed by a chemical vapor deposition method (CVD method) represented by There is no restriction | limiting in particular in the chemical composition of this hard protective film layer.

In particular, a hard protective film layer composed of an underlayer composed of AlTiN, an intermediate layer composed of TiN, and an outermost layer composed of Al ₂ O ₃ is desirable. This is due to the following reason.

AlTiN constituting the underlayer is excellent in heat resistance and wear resistance, these performances are stable up to 1000 ° C., and excellent in adhesion to the substrate. In addition, Al in the underlayer dissociates due to temperature rise during cutting, diffuses outward, reacts with oxygen in the outside air, and a protective film composed of Al ₂ O ₃ in the surface layer (outermost layer) of the coating Form. Therefore, it is desirable that the underlayer is made of AlTiN. The underlayer is mainly composed of AlTiN and may contain some impurities.

  Since TiN constituting the intermediate layer has an oxidation temperature as low as 700 ° C., it is originally a material suitable for cutting at a low speed or a medium speed with relatively little heat generation. However, since it is a substance that has excellent adhesion and is effective for mechanical peeling, it is desirable to form it as an intermediate layer. The intermediate layer is mainly composed of TiN and may contain some impurities.

Al ₂ O ₃ constituting the outermost layer is weak against mechanical peeling, but has excellent heat resistance and wear resistance, and this performance is stable up to 2000 ° C. Therefore, it is desirable that the outermost layer be composed of Al ₂ O ₃ . The outermost layer is mainly composed of Al ₂ O ₃ and may contain some impurities.

  As described above, the hard protective film layer described above is composed of a material having the highest heat resistance and wear resistance, an intermediate layer is composed of a material having the best adhesion, and an underlying layer is composed of adhesion and heat resistance. In addition, it is made of a material that has a certain degree of wear resistance and that dissociates and diffuses outwardly by heat during cutting. For this reason, even if the outermost layer and the intermediate layer are peeled off, the Al dissociated from the underlayer immediately reacts with oxygen on the surface layer of the coating to supplement the protective film of the outermost layer. Abrasion resistance is obtained.

  In addition, although there is no restriction | limiting in the thickness of a hard protective film layer, It is desirable that the total thickness of the hard protective film layer in a flank is 2-80 micrometers. Since the flank is the portion where the load is most applied during cutting and the heat generation is large, the hard protective film layer on the flank should be as thick as possible.

  In particular, the hard protective film layer on the flank is desirably 2 μm or more in total thickness. However, when the total thickness of the hard protective film layer on the flank surface exceeds 80 μm, it becomes easy to peel off and becomes weak against mechanical impact. In addition, the time required for film formation becomes longer. Therefore, the total thickness of the hard protective film layer on the flank is desirably 2 to 80 μm.

It is desirable that the thicknesses of the base layer (AlTiN), intermediate layer (TiN), and outermost layer (Al ₂ O ₃ ) on the flank of the cutting tool are 0.5 to 35 μm, 1.0 to 40 μm, and 0.5 to 5 μm, respectively.

  If the thickness of the underlying layer (AlTiN) on the flank surface is less than 0.5 μm, sufficient heat resistance may not be obtained. However, if the thickness of the base layer (AlTiN) on the flank surface exceeds 35 μm, it becomes easy to peel off, and only the time required for film formation becomes long. Therefore, the thickness of the base layer (AlTiN) on the flank is desirably 0.5 to 35 μm.

  When the thickness of the intermediate layer (TiN) on the flank surface is less than 1.0 μm, the heat resistance may be insufficient. However, when the thickness of the intermediate layer (TiN) on the flank surface exceeds 40 μm, it becomes easy to peel off, and only the time required for film formation becomes long. Therefore, the thickness of the intermediate layer (TiN) on the flank is desirably 1.0 to 40 μm.

In order to obtain sufficient heat resistance, the thickness of the outermost layer (Al ₂ O ₃ ) on the flank is desirably 0.5 μm or more. However, if the thickness of the outermost layer (Al ₂ O ₃ ) on the flank surface exceeds 50 μm, it becomes easy to peel off and only the time required for film formation becomes longer. Therefore, the thickness of the outermost layer (Al ₂ O ₃ ) on the flank is desirably 0.5 to 5 μm.

  On the other hand, the total thickness of the hard protective film layer on the rake face is desirably 2 to 40 μm. The rake face has a small heat generation at the time of cutting, but it should be small in surface roughness since it is a place where chips after cutting come into contact. For this reason, it is preferable to make the hard protective film layer as thin as possible.

  In particular, the hard protective film layer on the rake face is desirably 40 μm or less in total thickness. However, if the total thickness of the hard protective film layer on the rake face is less than 2 μm, it wears early during cutting, so that sufficient heat resistance may not be obtained. Therefore, the total thickness of the hard protective film layer on the rake face is desirably 2 to 40 μm.

The thickness of the base layer (AlTiN), intermediate layer (TiN), and outermost layer (Al ₂ O ₃ ) on the rake face of the cutting tool is preferably 0.01 to 2 μm, 1 to 20 μm, and 1 to 20 μm, respectively.

  When the thickness of the ground layer (AlTiN) on the rake face is less than 0.01 μm, there is a possibility that sufficient heat resistance and adhesion cannot be obtained. However, when the thickness of the ground layer (AlTiN) on the rake face exceeds 2 μm, it becomes easy to peel off and it takes a long time for film formation. Therefore, the thickness of the foundation layer (AlTiN) on the rake face is desirably 0.01 to 2 μm.

  When the thickness of the intermediate layer (TiN) on the rake face is less than 1 μm, sufficient heat resistance and adhesion may not be obtained. However, when the thickness of the intermediate layer (TiN) on the rake face exceeds 20 μm, not only is it easy to peel off, but a long time is required for film formation. Therefore, the thickness of the intermediate layer (TiN) on the rake face is desirably 1 to 20 μm.

If the thickness of the outermost layer (Al ₂ O ₃ ) on the rake face is less than 1 μm, sufficient heat resistance and adhesion may not be obtained. However, when the thickness of the outermost layer (Al ₂ O ₃ ) on the rake face exceeds 20 μm, not only is it easy to peel off, but a long time is required for film formation. Therefore, the thickness of the outermost layer (Al ₂ O ₃ ) on the rake face is desirably 1 to 20 μm.

3. About the manufacturing method of the cutting tool which concerns on this invention Although the manufacturing method of the cemented carbide or cermet as a tool base material is not specifically limited, For example, after each metal powder of a raw material is sized and mixed, this is made into predetermined shape. It can be produced by pressure-molding and punching with a mold and firing the obtained molded body in a vacuum. The above-described pretreatment is performed on the tool base material thus produced.

  Although there is no restriction | limiting in the manufacturing method of a hard protective film layer, For example, the following dry coating methods are employable. That is, a mixed powder using only the metal elements constituting the hard protective film layer is pressed into a predetermined disk shape, vacuum-sintered, and then used as a target, and physical vapor deposition represented by sputtering, arc ion plating, etc. The target component is electrically vapor-phase excited using a method (PVD method) or a chemical vapor deposition method (CVD method) typified by a thermal CVD method and a plasma CVD method. Thereafter, the gas phase of the apparatus is filled with nitrogen gas or the like, and chemically bonded on the surface of the film body with the target component excited in the gas phase. As a result, a predetermined hard protective film component is deposited on the surface of the film body, and the deposited component becomes a chemically stable composition by heat-treating it to form a desired hard protective film layer in close contact with the film body. be able to.

  In order to confirm the effect of the present invention, a 5% Ni-containing alloy (S13Cr steel) was cut out of the VAM-TOP at a cutting speed of 90 m / min with four cutting machines using a screw cutting chaser manufactured by the following method. Diameter screw cutting was performed, and the tool life at that time was investigated.

  First, after sizing and mixing each metal powder as the raw material of the tool base material, this is pressure-molded and punched with a mold of a predetermined shape, and the resulting molded body is fired in vacuum at 1,450 ° C. for 1.0 hour. A tool base material was produced. A tool in which a hard protective film layer is formed without performing any treatment on the base material (Comparative Example) and a tool in which a hard protective film layer is formed after the base material is subjected to a lapping process by a vapor-phase injection lapping method ( An example of the present invention was prepared.

  The lapping process by the vapor jet lapping method was performed using an abrasive having a particle size of 0.5 to 2.0 mm formed by combining 3000 mesh diamond abrasive grains with a polymer resin.

Each tool base material is placed in a PVD apparatus, and a mixed gas of Al and Ti is used as a target to fill nitrogen gas to react each discharge excited metal with nitrogen, and the tool base material is made of AlTiN. A formation was formed. Thereafter, in the PVD apparatus, the Ti target is discharged and excited in a nitrogen gas atmosphere, and the intermediate layer composed of TiN is further excited and the Al target is discharged and excited in an oxygen gas atmosphere, and composed of Al ₂ O ₃ . An outermost layer was formed to produce a thread cutting chase.

The cutting life of each cutting tool thus produced was investigated. The cutting life means the number of pieces that can be cut before reaching any one of the following conditions (1) to (3). Based on this criterion, the average value of the cutting life and the standard deviation of the four cutting machines were obtained.
(1) Breakage of the cutting tool body (breaking or chipping of the cutting edge)
(2) Peeling of hard protective film layer on cutting tool surface
(3) Adhesion of work piece components to hard protective film

  In the comparative example in which the vapor-phase injection lapping method was not performed, the average value of the cutting life was 60.8 and the standard deviation was 18.5, but in the present invention example in which the vapor-phase injection lapping method was performed, the average value of the cutting life was The standard deviation was 77.0 and 2.5, indicating that a stable and long cutting life can be obtained.

According to the present invention, since the adhesion between the tool base material and the hard protective film layer can be improved, a cutting tool having a long tool life can be provided. This cutting tool is particularly useful for a thread cutting chaser used for severe cutting conditions such as thread cutting of high hardness steel materials.

Claims (4)

And abrasive grains collided morphism injection soft particles formed by the composite using a polymeric resin sintered metal surface composed of superhard material, mirror finished processing the surface shape of that in the submicron range meter Thereafter, a hard tool layer is formed by a dry coating technique.   The cutting tool according to claim 1, wherein the hard protective film layer is a coating layer mainly composed of metal carbide, metal nitride, metal oxide, or a composite compound thereof.   The cutting tool according to claim 1 or 2, wherein the cutting tool is a thread cutting chaser. And abrasive grains collided morphism injection soft particles formed by the composite using a polymeric resin sintered metal surface composed of superhard material, mirror finished processing the surface shape of that in the submicron range meter Then, the manufacturing method of the cutting tool characterized by forming a hard protective film layer with a dry-coating method.