JP2006255848A - Cutting tool and cutting method for low carbon free-cutting steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool improved in the quality of a cut surfce in cutting low carbon non-lead free-cutting steel and improved in quality exceeding a level achieved in the conventional low carbon free-cutting steel. <P>SOLUTION: In this cutting tool, the cutting edge roundness of one or both of a main cutting edge and a sub-cutting edge has a radius of 50 μm or less, the partial or whole surface layer of the surface coming into contact with a material to be cut is coated with a hard film. The hard film contains N: 40 to 60% in atom % and Ti: 40 to 60% in atom %. The hard film further contains 40% or less one or two kinds of Al and Zr in atom %. When the cutting tool is used in cutting low-carbon non-lead free-cutting steel, since the steel is hard to cohere to the cutting edge, a built-up edge is hardly formed, and the cutting edge roundness has a radius of 50 μm or less, whereby good surface roughness not obtained in the past can be achieved and the breakage of the cutting edge is hardly caused to obtain an extremely favorable tool life. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cutting tool and a cutting method for improving the cutting surface roughness in cutting low-carbon free-cutting steel, particularly low-carbon lead-free free-cutting steel.

  There is an increasing demand for streamlined cutting, higher efficiency, and improved part finishing accuracy, and along with improvements in cutting tools, high-performance free-cutting steel is being adopted. Low-carbon free-cutting steel has a carbon concentration of 0.2% or less, and is low-carbon steel that can be easily cut. It is a steel that has been devised in terms of chemical composition in order to improve machinability, that is, the ease of cutting by machining chips by removing chips. Not only has a long cutting tool life, it has superior performance to other steels in terms of cutting surface quality such as surface roughness and chip disposal.

  Currently, the low-carbon free-cutting steel specified in JIS is sulfur and sulfur-lead composite free-cutting steel. Specifically, SUM22, SUM23, SUM24L, SUM25, etc. defined in JIS G 4804 are common.

  Sulfur free-cutting steel is the oldest free-cutting steel and contains 0.08 to 0.35% of S. Lead free-cutting steel is obtained by finely and uniformly distributing Pb in steel, and Pb is usually contained in a range of 0.10 to 0.35%. MnS of sulfur free-cutting steel extends in the rolling direction, whereas Pb of lead free-cutting steel has MnS adhering to the surroundings or is distributed in a fine granular form, so the anisotropy of mechanical properties is relatively The heat treatment characteristics are almost the same as the basic steel. Moreover, the cutting force is reduced and the chip crushability is improved by the lubrication effect and the notch effect of the Pb thin film on the tool surface. As conventional low-carbon free-cutting steel, lead-containing low-carbon lead free-cutting steel has been mainly used.

  As a cutting tool used when cutting low-carbon free-cutting steel, a high-speed steel tool or a cemented carbide tool obtained by sintering WC with Co has been mainly used. Alumina ceramics or cermet obtained by sintering TiC with Ni may also be used.

  High-speed steel easily wears tools, and it is easy to generate a component edge in the worn part. Therefore, frequent tool change / repolishing is necessary to maintain surface roughness and dimensional accuracy.

  A cemented carbide sintered tool equivalent to K01 to K30 (so-called K type) or V10 to V30 (V type) shown in JIS B 4053-1996 is excellent in wear resistance for lead free cutting steel. Therefore, good surface and dimensional accuracy can be obtained, and it is excellent in terms of cost including cutting performance and tool cost such as machined surface quality and tool life, and suitable for cutting of lead free cutting steel (e.g. SUM24L, SAE12L14 equivalent) ing.

  In Patent Document 1, manganese carbide sulfide on the tool surface is obtained by adding a cemented carbide mainly composed of WC and Co to Zr having a strong chemical affinity with S of manganese sulfide interposed in steel. An invention is described in which an excellent coating finish is formed by suppressing the formation of the constituent edge by forming an object film and suppressing the adhesion between the steel and the tool by using this manganese sulfide film. However, what is described in Patent Document 1 is a sintered body tool containing Zr, which has a problem in stability such as the chipping property of the tool, and has a small degree of freedom in the tool shape, so it can be used for cutting in a wide range. Was unsuitable.

A coated tool is known in which a single-layered or multilayered hard coating is applied to the surface of a tool base made of cemented carbide, high-speed steel, or special steel. Generally, a hard film of a coated tool is required to have excellent wear resistance and toughness, and therefore a film made of a carbide, nitride, or carbonitride of Periodic Tables 4, 5, and 6 metals is used. In addition, an aluminum oxide film having excellent oxidation resistance is also used. These hard coatings are formed by a CVD method or a PVD method. TiC, TiN, TiCN, Al ₂ O ₃ films, etc., which have been formed by the CVD method, have been put to practical use as coatings for turning tools and the like whose temperature increases to a relatively high temperature during cutting.

  When cutting a lead free-cutting steel as described above, the degree of adhesion with the steel is worse than that of a normal cemented carbide tool, so the surface roughness of the cutting surface is deteriorated. Further, since the coated tool is more expensive than the conventional tool, it is not very popular as a cutting tool for lead free cutting steel.

  In cutting low-carbon free-cutting steel, it is required that the surface roughness of the cutting surface be good. Generally, the surface roughness of the cutting surface can be improved by reducing the cutting edge roundness of the cutting edge and sharpening the cutting edge. However, even if the cutting edge roundness is reduced to 50 μm or less in radius, there is a limit to the degree of improvement in surface roughness. This is thought to be due to the formation of the component cutting edge. On the other hand, in brittle materials such as cemented carbide tools, if the cutting edge roundness is reduced to 50 μm or less in radius, the cutting edge tends to be chipped, and chipping occurs at a stage where the tool is used less frequently. There is even an adverse effect that the tool life is shortened due to the deterioration of the tool. Therefore, in the case of using a cemented carbide tool or the like for cutting low-carbon lead free-cutting steel, conventionally, the cutting edge of the cutting edge has a radius of about 100 μm, or a tip called a chamfer has a negative rake angle. For example, a technique that intentionally blunts the blade edge to avoid defects is used. With such a shape, a sufficiently good roughness could not be obtained. In addition, when the cutting edge tip is sharpened, in the case of a coated tool, the hard coating on the surface tends to be peeled off, so the cutting edge is often intentionally rounded. For example, commercially available coated tools often have a cutting edge radius of about 100 μm, and in the case of a chamfer, the cutting edge is locally set to a rake angle of about −45 °. Thereby, the balance between the surface roughness of the cutting surface and the tool life was maintained. Conventionally, the surface roughness of the cut surface when using low-carbon lead free-cutting steel has not reached a sufficiently good level for quality requirements.

  In recent years, there is concern about the harmfulness of lead to human bodies and organisms, and in recent years it is thought that it will remain even if it is treated as shredder dust, and from the idea of reducing the environmental burden considering the product life cycle, such as recycling, Regulations are also being considered for the slight amount of Pb contained in steel. Therefore, as Pb contained in lead free-cutting steel is also concerned about the environment, it has recently been requested to switch from low-carbon lead free-cutting steel to low-carbon non-lead free-cutting steel that does not contain lead. Yes.

  With such a trend to abolish lead in steel, cutting tools corresponding to lead-free work materials are being demanded.

Japanese Patent Laid-Open No. Sho 62-152614

  When a cemented carbide tool is used for cutting lead-free-cutting steel, a suitable surface roughness can be achieved, but it has never been sufficiently good. Moreover, when a cemented carbide tool is used for cutting low-carbon non-lead free-cutting steel, the surface roughness deteriorates, and there arises a problem that a sufficiently good surface roughness cannot be obtained as the quality of the cut surface.

  An object of the present invention is to provide a cutting tool that can be used for cutting low-carbon lead-free free-cutting steel and that can improve the quality of a cutting surface. Furthermore, the present invention provides a cutting tool capable of making the cutting surface quality of low-carbon non-lead free-cutting steel better than the level achieved with conventional low-carbon lead-free cutting steel. Objective.

  The reason why the cemented carbide tool was suitably used for cutting lead free-cutting steel was that Pb contained in the lead free-cutting steel formed a Pb thin film on the tool surface to ensure lubricity. On the other hand, when a cemented carbide tool is used for cutting lead-free free-cutting steel, the lubrication effect due to Pb cannot be obtained, and the steel tends to adhere to the tool surface, which is why the tool surface is configured. A cutting edge was formed, which caused the surface roughness of the cutting surface to deteriorate.

  When the surface of the tool in contact with the work material is a material mainly composed of Ti—Al—Zr-based nitride containing TiN, the work material is a lead-free free-cutting steel containing no Pb. It became clear that the adhesion of steel to the surface could be prevented.

  Furthermore, when combining low-carbon lead-free free-cutting steel and Ti-Al-Zr-based nitride tools, the degree of difficulty of adhesion is a combination of low-carbon lead-free cutting steel and cemented carbide tools. It became clear that it was better than the case of.

  When combining low-carbon lead-free free-cutting steel and Ti-Al-Zr-based nitride-based tools, the steel is difficult to adhere to the cutting edge, making it difficult to generate the cutting edge, and reducing the cutting edge roundness of the tool cutting edge. It has been found that the surface roughness is improved as the surface roughness is improved, and that the surface roughness is 50 μm or less in radius, so that an unprecedented surface roughness can be realized. Furthermore, it was found that since steel is less likely to adhere to the cutting edge, even when the cutting edge is rounded to a radius of 50 μm or less, chipping of the cutting edge is difficult to occur, and a sufficiently good tool life can be realized.

This invention is made | formed based on the said knowledge, The place made into the summary is as follows.
(1) Either one or both of the main cutting edge and the auxiliary cutting edge have a radius of 50 μm or less, and a part or all of the surface layer in contact with the work material is coated with a hard coating, The hard coating includes N: 40 to 60% and Ti: 40 to 60% in atomic%, and the balance is substantially made of inevitable impurities.
(2) Either one or both of the main cutting edge and the auxiliary cutting edge have a radius of 50 μm or less, and a part or all of the surface layer in contact with the work material is coated with a hard coating, The hard film contains N: 40 to 60% in atomic%, Ti: 10% or more and less than 60%, and includes one or two of Al or Zr in a range of 50% or less in atomic%, and the balance A cutting tool comprising substantially inevitable impurities.
(3) The rake angle of either one or both of the main cutting edge and the auxiliary cutting edge is in the range of −10 to 30 °, and the clearance angle is 2 to 15 °, (1) or ( The cutting tool according to 2).
(4) The cutting tool according to (3) above, wherein the base material disposed inside the hard coating is any one of tool steel, cemented carbide, cermet, and ceramics.
(5) One or both of the main cutting edge and the auxiliary cutting edge have a radius of cutting edge of 50 μm or less, and at least part or all of the surface layer in contact with the work material contains Ti-containing carbide, carbonitriding 50% by mass or more of the hard phase of the nitride, nitride and their composites, and 30% by mass or less of the hard phase of Ta, Nb, W carbide, carbonitride, nitride and their composites not containing Ti A cutting tool comprising: one or two of Co or Ni in a total of 20% by mass or less, and the balance being made of a sintered material substantially composed of inevitable impurities.
(6) The rake angle of one or both of the main cutting edge and the auxiliary cutting edge is in the range of −10 to 30 °, and the clearance angle is 2 to 15 °, as described in (5) above Cutting tools.
(7) The cutting tool according to any one of (1) to (6) above, which is for cutting low-carbon non-lead free-cutting steel.
(8) Using the cutting tool according to any one of (1) to (6) above, using low-carbon free-cutting steel as a work material, and cutting at a cutting speed of 1 to 400 m / min. Cutting method of charcoal free cutting steel.
(9) Low-carbon lead-free free cutting using the cutting tool described in (7) above, using low-carbon non-lead free-cutting steel as a work material, and cutting at a cutting speed of 1 to 400 m / min. Steel cutting method.

  The cutting tool of the present invention has a cutting edge with a radius of 50 μm or less, and is used for cutting low-carbon non-lead free-cutting steel by using TiN as a main component for the composition of the tool surface in contact with the work material. The surface roughness of the cutting surface can be improved and the tool life can be maintained at the same level as usual.

  The cutting tool of the present invention exhibits particularly excellent effects when used for cutting low-carbon non-lead free-cutting steel. Here, first, low-carbon non-lead free-cutting steel will be described.

  Low-carbon lead-free free-cutting steel is relatively low-carbon, and has been devised in terms of chemical composition to improve machinability (“easy to process steel by removing chips”) than ordinary steel. Among low-carbon free-cutting steel, it refers to steel that does not contain Pb. In other words, it is a steel that does not contain Pb among “low-carbon steel that can be easily cut”.

  Specific examples include SUM22, SUM23, and SUM25 defined in JIS G 4804. Moreover, even if it is outside JIS regulations, C ≦ 0.15%, Mn: 0.1 to 2.0%, P: 0.001 to 0.2%, S: 0.001 to 0.7%, N: 0.001 to 0.025%, Cr: 0.1 to 3.0%, Nb: 0.01 to 0.3%, Ti: 0.01 to 0.3%, B: 0.0002 -0.02%, V: 0.05-0.5%, Mo: 0.05-0.5%, W: 0.05-0.5%, Co: 0.05-0.5%, Cu: 0.01 to 0.5%, Ni: 0.01 to 0.5%, Te: One or more of 0.0002 to 0.05%, Mg: 0.0002 to One or two of 0.005%, Al: 0.002-0.04%, Ca: 0.0001-0.01%, Zr: 0.0001-0.01%, Si ≦ 0.1% Including the above, the remainder is impossible with Fe Manner consists impurities, a steel is limited to Pb ≦ 0.01%, it is also possible to use a steel excellent in free-cutting.

  The first feature of the present invention is that a cutting tool for cutting the low-carbon non-lead free-cutting steel has a part or all of the surface layer in contact with the work material coated with a hard coating, The hard coating is characterized in that it uses a cutting tool characterized by containing N: 40 to 60% and Ti: 40 to 60% in atomic%, and the balance being substantially made of inevitable impurities. The hard coating also includes N: 40 to 60% in atomic%, Ti: 10% or more and less than 60%, and a total of one or two of Al or Zr in a range of 50% or less, and the balance is substantially It is preferable to consist of inevitable impurities. Hereinafter, this hard coating may be referred to as “TiN-containing hard coating”.

  In the case of cutting lead free-cutting steel, Pb in lead free-cutting steel forms a Pb thin film on the tool surface, and even when a cemented carbide tool in which WC is sintered with Co is used as a cutting tool, it is good. It showed lubrication properties and realized a moderate surface roughness of the cutting surface with less steel adhesion on the tool rake face.

  However, when the above cemented carbide tool is used for cutting lead-free free-cutting steel, Fe adheres to the tool surface in contact with the work material, and the growth of the component cutting edge is promoted on the tool surface, resulting in the surface of the cutting surface. The result is that the roughness is very worse.

  On the other hand, when the tool having the TiN-containing hard coating of the present invention is used for cutting low-carbon non-lead free-cutting steel, Fe hardly adheres to the tool surface in contact with the work material, and Mn and S adhere. Is seen. It is thought that manganese sulfide inclusions in free-cutting steel adhered. Since the adhered material is not Fe, the adhesion force between the chips and the tool is also reduced, and the generation of the constituent cutting edge is suppressed. This tendency is remarkable when the low-carbon lead-free free-cutting steel of the work material contains sulfur, but even when the low-carbon lead-free free-cutting steel does not contain sulfur, the work material The adhesion of Fe to the tool surface in contact with is extremely small.

  The combination of the low-carbon lead-free free cutting steel and the cutting tool having the hard coating containing TiN of the present invention is better than the combination of the lead free-cutting steel and the cemented carbide tool in the difficulty of adhesion. Can be obtained. On the other hand, the combination of low-carbon lead-free free-cutting steel and cemented carbide tool resulted in the worst results in terms of difficulty in adhesion.

  The combination of the low-carbon lead-free free-cutting steel and the cutting tool having the TiN-containing hard coating of the present invention has the feature that adhesion to the tool surface is very low, The characteristic was derived. That is, when the cutting edge of the cutting edge is reduced to sharpen the cutting edge, the surface roughness of the cutting surface continues to improve as the cutting edge is sharpened even in the region where the radius of the cutting edge is 50 μm or less, exceeding the conventional limit. Thus, it has become possible to realize extremely good surface roughness that could not be realized in the past. Furthermore, coupled with the fact that the adhesion is very small, even if the radius of the cutting edge roundness is 50 μm or less, chipping of the cutting edge does not occur, and a good tool life can be maintained.

  With the combination of conventional lead free-cutting steel and cemented carbide tool, the improvement in surface roughness is saturated when the radius of the cutting edge is about 50 μm, and even when sharpened, the improvement in surface roughness is slight. . On the other hand, when the radius of the cutting edge roundness is 50 μm or less, the generation of chipping of the cutting edge becomes severe and the tool life is deteriorated. The same applies to a combination of a cutting tool having a lead free cutting steel and a hard coating containing TiN. Therefore, in order to realize the good surface roughness of the present invention, it is important that the work material has a low lead content.

  The cutting tool of the present invention has a radius of 50 μm or less in either or both of the main cutting edge and the auxiliary cutting edge, and as a result, extremely good cutting when cutting low-carbon non-lead free cutting steel. Surface roughness can be realized. More preferably, the radius of the rounded edge is 30 μm or less. More preferably, the radius of the cutting edge roundness is 20 μm or less.

  In the past, in order to improve the surface roughness of the cutting surface, it was often improved by devising the tool shape and cutting conditions. For example, if the cutting edge of the tool is sharpened (specifically, the cutting edge roundness is reduced and the rake angle is increased), the finished surface roughness is improved. However, a tool with a sharp edge tends to be damaged in shape. Even relatively soft, low-carbon free-cutting steel has a large adhesion force, and if the contact area between the tool and work material increases, the tip tends to be damaged, so in order to achieve both tool life and surface properties, the cutting edge is generally used. Is generally rounded, or the rake angle called chamfer or negative land is locally obtuse, and the surface roughness has to be reduced.

  On the other hand, in the present invention, it is possible to reduce the adhesion force and friction force generated between the tool and the work material (steel) at the time of cutting by designing a combination of the work material steel and the tool material in contact therewith. As a result, the cutting resistance can be reduced as compared with conventional tools, so that even a fragile tool grade like the present invention can be cut with a sharp cutting edge, which can improve the cutting surface roughness. ing.

  The inventive tool shown in the present invention is particularly effective in reducing the adhesion force and frictional force when cutting low-carbon free-cutting steel that does not contain Pb, so that the tool edge roundness can be reduced, resulting in tool life. The effect of improving the surface roughness is also large while maintaining the above.

  Here, the cutting tool shape will be described. FIG. 1 (a) shows the shape of the work material 11 cut by the plunge cutting tool 1 of the lathe, (b) shows the relationship between the cutting edge and the finished surface in plunge cutting, and (c) shows the shape of the plunge cutting tool 1 and (D) shows a tool cross section of the cut surface 23. The surface roughness in question is a finished surface 21 by the main cutting edge 2 and a finished surface 22 by the sub-cutting edge 3 in the figure. In the cross section, the cutting edge portion is generally provided with a cutting edge roundness 7 or a chamfer.

  FIG. 2A shows the shape of the work material 11 cut by the longitudinal turning of the lathe, FIG. 2B shows the relationship between the cutting edge and the finished surface in the longitudinal turning, FIG. 2C shows the shape of the cutting tool 1, and FIG. Shows a tool cross section of the cut surfaces 23a and 23b. As for the surface roughness which becomes a problem, the main cutting edge is the finishing surface 21 by the main cutting edge 2 and the finishing surface 22 by the sub cutting edge 3 in the figure. In the cross section, in the same way as the plunge cutting tool, in the case of the longitudinal turning tool, generally, the cutting edge portion is generally provided with a cutting edge roundness 7 or a chamfer. In the case of turning rather than the plunge cutting tool, the secondary cutting edge 3 has a feature that the influence on the surface roughness is increased.

  In order to improve the surface roughness of the cutting surface in the present invention, the main cutting edge 2 is usually important. On the other hand, finishing surface properties may be regarded as important for the auxiliary cutting edge 3 as well. As shown in FIG. 1 or 2, when the side wall of the groove 12 is important even in plunge cutting as shown in FIG. Further, as shown in FIG. 2B, in the longitudinal turning, the cylindrical cutting surface 13 is a finished surface, and the cutting edge that directly contacts is the secondary cutting edge 3. Therefore, when the accuracy of the cylindrical surface is important, the shape of the secondary cutting edge 3 is also important. For these reasons, the shape of the cutting edge that comes into contact with the cutting surface, which is regarded as important in the product, is important. When the surface created by the main cutting edge is important, the radius of the cutting edge of the main cutting edge should be 50 μm or less. If it is necessary to adjust, and similarly the generation surface by the secondary cutting edge is important, it is necessary to adjust the roundness of the cutting edge of the secondary cutting edge to a radius of 50 μm or less.

  The preferred properties of the TiN-containing hard coating of the present invention will be described.

  Specifically, in the case of a coating on the tool surface, N: 40 to 60% in atomic%, Ti content includes 40 to 60%, and the balance is substantially composed of inevitable impurities. Further, when one or two of Al or Zr are included, these elements are replaced with Ti, and therefore the Ti content may be reduced depending on the content thereof. That is, N: 40 to 60% in atomic%, Ti: 10% or more and less than 60%, further including 50% or less of the total of one or two of Al or Zr, with the balance being substantially composed of inevitable impurities It is a hard film. When Al or Zr is contained, it refers to a hard film of HV1000 or more in which a part of TiN or Ti is substituted with Al or Zr. In addition, even if oxygen is contained as an unavoidable impurity by 5% or less, there is no problem with the characteristics of the hard coating.

  When neither Al nor Zr is contained, sufficient hardness and adhesion cannot be obtained if the Ti content is less than 40%. If it exceeds 60%, Ti will be excessive and the ratio of N will collapse, and a hard coating that can withstand the severe environment of cutting will not be obtained. On the other hand, when one or two of Al or Zr are included, if Ti is less than 10%, sufficient hardness or coating cannot be obtained. If Ti is 60% or more, Ti is excessive, the ratio with N is lost, and a hard coating that can withstand the severe environment of cutting cannot be obtained. Therefore, in the present invention, the range of Ti content is set to 10% or more and less than 60%.

  When N is less than 40%, the hardness of nitrides of Ti, Al, and Zr is insufficient, wear resistance and adhesion characteristics are lowered, and good surface roughness cannot be obtained. If it exceeds 60%, the hardness of the hard film is saturated, and excessive N deteriorates the toughness of the film and decreases the adhesion to the substrate. Therefore, in the present invention, the range of N content is set to 40 to 60%.

  As described above, it is preferable that the hard coating of the present invention substitutes a part of Ti to contain one or two of Al or Zr in a range of 50% or less in atomic percent. Even if Al and Zr in these hard coatings are not contained, good surface roughness may be obtained. However, while ensuring the wear resistance and adhesion to the base material, the work material is low charcoal non-carbonized. It is preferable to contain it also in order to suppress adhesion with lead free-cutting steel, and the content is preferably 10% or more in total of Al and Zr.

  If Al exceeds 50%, the amount of Ti in the hard coating is relatively reduced, wear resistance and adhesion characteristics are lowered, and good surface roughness cannot be obtained, so the upper limit is made 50%.

  Similarly, if Zr exceeds 50%, the amount of Ti in the hard coating decreases, wear resistance and adhesion characteristics deteriorate, and good surface roughness cannot be obtained, so the upper limit is made 50%.

  These are generally formed as a film on a hard substrate, and can be formed by a CVD process or the like, but it is preferable to form a film of 1 μm or more by a so-called PVD process such as ion plating. In particular, in order to increase the adhesion to the substrate, it is preferable to deposit a slight amount of metal such as Ti or Zr at the interface between the substrate and the coating.

  The hard coating of the present invention covers a surface layer of a cutting tool and a part or all of the surface layer in contact with the work material. It is important to cover the rake face among the surfaces in contact with the work material. It is not necessary to cover the entire rake face, as long as it covers the place where the cutting edge comes into contact with the work material and chips. It is also effective to cover the flank of the cutting tool. In cutting, since the work material is also in contact with the flank due to the effect of elastic deformation, adhesion of the flank can be suppressed. There is an effect of suppressing resistance. When the coated tool is re-polished, the film may remain only on either the flank or rake face, but if any of the film remains, adhesion to the work material can be suppressed, and the effect of the coating Is seen. In particular, the effect is greater when the film remains on the rake face. However, it is not essential to cover the flank.

  Next, the rake angle 8 and clearance angle 9 shown in FIGS. 1D and 2D among the cutting edge shapes will be described.

  As described above, the shape of the main cutting edge and the auxiliary cutting edge among the cutting tool shapes has an important role. The shape of the cutting edge that comes into contact with the cutting surface, which is regarded as important in the product, is important. When the surface created by the main cutting edge is important, the shape of the main cutting edge is important, as well as the creation by the secondary cutting edge. If the surface is important, the shape of the secondary cutting edge becomes important. In the present invention, it is preferable that the rake angle of one or both of the main cutting edge and the auxiliary cutting edge is in the range of −10 to 30 °, and the clearance angle is 2 to 15 °.

  If the rake angle exceeds 30 °, defects tend to occur, so this was set as the upper limit. When the rake angle is smaller than -10 °, the cutting resistance increases, the tool life decreases and the surface roughness decreases. The rake angle suitable for cutting centering on turning and milling is -10 to 30 °, and the surface roughness and tool life can be secured in a well-balanced manner. In order to further improve the surface roughness, a larger rake angle is better, a rake angle of 3 ° or more is preferable, and a rake angle of 10 ° or more is more preferable.

  In the tool shape, a plane called a chamfer may be formed. However, in the cutting tool of the present invention, the steel and the tool hardly adhere to each other, so that this chamfer can be made small. In addition, since the chamfer makes the rake angle of the blade edge an obtuse angle, it is necessary to adjust the rake angle α within the range of −10 to 30 ° of the present invention even when the chamfer is attached.

  If the clearance angle is 2 ° or less, the contact area with the work material becomes too large, increasing the resistance and promoting tool wear. If it exceeds 15 °, the cutting edge becomes sharp and tool wear easily occurs. Therefore, the clearance angle was set to 2 to 15 °. If the cutting edge shape is too sharp, chipping may occur easily, so the clearance angle is preferably 10 ° or less. It is preferable to use about 5 °.

  The details of these tool shapes are the nature of the work material, the chipping property of the tool material, the coating peelability in the case of a coated tool, the finished product accuracy (surface roughness and dimensional accuracy), and the processing machine capability (rigidity and spindle output). Etc.) should be adjusted precisely.

  In the cutting tool of the present invention, in the cutting tool in which a part or all of the surface layer in contact with the work material is coated with a hard coating, the inner portion of the hard coating is constituted by a base material. For base materials, even if the surface is covered with a hard coating, it is affected by cutting heat, etc., and it is necessary to maintain high-temperature strength, and stable cutting is possible even if the coating is locally worn or peeled off. In order to continue the time until the tool change, the base material is also preferably a general tool material. Further, it is preferable as the base material that the adhesiveness with the surface layer film is good. That is, any of tool steel, cemented carbide, cermet and ceramics including high speed steel is good, and cemented carbide, cermet and high speed steel are particularly suitable.

  The tool steel, cemented carbide, cermet, and ceramic of the base material here are materials generally used as a cutting tool, and tool steel: a material specified by JIS G 4401/4403, cemented carbide: It is a material specified by JIS B 4104 or the like. The cermet is composed of titanium carbide (TiC), titanium nitride (TiN), and titanium carbonitride (TiCN) as the main components, and these are sintered with a metal such as Co or Ni. Ceramics are those in which the basic components are metal oxides, carbides, etc., sintered by heat treatment at high temperature.

  As described above, the cutting tool in which the TiN-containing hard coating is formed on the surface in contact with the work material has been described as the cutting tool of the present invention. In the present invention, not only a cutting tool having a hard coating on its surface but also a sintered ceramic itself having no hard coating on its surface can be used as a tool.

  When the sintered ceramic itself is used as the cutting tool of the present invention, at least a part of or the entire surface layer in contact with the work material has a hard phase of carbide, carbonitride, nitride, and a composite thereof containing Ti. 50% by mass or more, Ta, Nb, W carbides, carbonitrides, nitrides and composites thereof containing no Ti, 30% by mass or less, and one or two of Co or Ni in total The balance is 20% by mass or less, and the balance is made of a sintered material substantially composed of inevitable impurities.

  When the carbide, carbonitride, nitride and their composite hard phase containing Ti are less than 50% by mass, the hardness as a tool is insufficient, wear resistance decreases, and the work material Since the adhesion of the surface cannot be suppressed, good surface roughness cannot be obtained, or the tip of the blade edge is damaged. The hard phase here refers to the hard phase shown in JIS B 4053-1996 P8 Reference Tables 1-4. The same applies hereinafter.

  By containing the hard phase of Ta, Nb, W carbide, carbonitride, nitride and their composites that do not contain Ti, the balance between hardness and toughness can be adjusted. The content may be 0%, but is preferably 5% or more. However, if it exceeds 30%, the content of the hard phase containing Ti must be suppressed, the adhesion characteristics are lowered, and good surface roughness cannot be obtained. In addition, wear resistance is reduced, making it difficult to balance the hardness and toughness of the tool.

  One or two kinds of Co or Ni are contained as a binder. The content is preferably 2% or more. However, if it exceeds 20%, Ti, Ta, Nb carbides, carbonitrides, nitrides and their composite hard phases are relatively reduced, so that the hardness is insufficient, and the wear resistance and adhesion properties are reduced. To do.

  As the tool shape of the sintered tool of the present invention, the shape condition that the coated tool of the present invention should have, including the point that the radius of the cutting edge of one or both of the main cutting edge and the auxiliary cutting edge is 50 μm or less is included. It is the same. Therefore, it is preferable that the rake angle of one or both of the main cutting edge and the auxiliary cutting edge is in the range of −10 to 30 °, and the clearance angle is 2 to 15 °. The reason is the same as the reason described for the coated tool.

  The cutting tool of the present invention exhibits particularly excellent effects when used for cutting low-carbon non-lead free-cutting steel. When the cutting tool of the present invention is used for cutting low-carbon non-lead free-cutting steel, adhesion between the steel and the tool is particularly difficult to occur, coupled with the cutting edge roundness of the cutting edge being 50 μm or less, This is because excellent surface roughness of the cutting surface can be realized.

  That is, among the low-carbon free-cutting steels, the low-carbon lead-free free-cutting steels that do not contain Pb are particularly effective in improving the surface roughness, achieving both tool life and surface roughness, and industrially high quality. Cutting becomes possible. This low-carbon lead-free free-cutting steel is superior in cutting tool life and surface roughness compared to other steel types, and is easy to cut short and easy to cut.

  In particular, the limitation of the Pb content is important. It is well known that machinability is improved when Pb is added to steel, but the cause is said to be the lubrication effect of Pb. In the conventional hard metal tool material equivalent to K type, unless Pb is added, the adhesion force with the tool is increased, and a good machined surface cannot be obtained.

  Conversely, when cutting low-carbon free-cutting steel containing Pb with the cutting tool of the present invention having adhesion characteristics suitable for low-carbon non-lead free-cutting steel, compared to cutting low-carbon non-lead free-cutting steel Therefore, it is difficult to obtain a good cutting surface, and even if the tool is sharper than usual and a good cutting surface can be obtained, the adhesion force is large, so the effect of improving the surface roughness by changing the tool shape The tool life is small or the tool life cannot be obtained. Therefore, in order to obtain a good cutting surface, it is preferable to limit Pb of the work material, which is very important.

  Next, a method for cutting low-carbon free-cutting steel using the cutting tool of the present invention will be described.

  In the cutting method of the low-carbon free-cutting steel of the present invention, it is preferable that the cutting tool of the present invention is used, low-carbon free-cutting steel is used as a work material, and cutting is performed at a cutting speed of 1 to 400 m / min. In general, it is said that the surface roughness is improved because the cutting edge is less likely to be generated when the cutting speed is increased. However, the tool life and the roughness and accuracy of the cutting surface are reduced because the tool life decreases as the cutting speed increases. It is better to cut under balanced conditions. Specifically, it is preferably 10 to 100 m / min for a coated tool based on high-speed steel, and 10 to 300 m / min for a coated tool or sintered body tool based on cemented carbide or cermet. If possible, 30 m / min or more is preferable, and when the tool life is given priority, 250 m / min or less is preferable.

  The other cutting conditions are complicated depending on the cutting method and shape, but in the case of a plunge cutting (cut-off cutting) when the cutting width is 5 mm or less, the tool feed amount in the radial direction is about 0.005 to 0.1 mm / rev, When the cutting width is wider, the tool feed amount in the radial direction is preferably suppressed to about 0.001 to 0.01 mm / rev.

  Furthermore, in longitudinal turning, the cut amount is 0.005 to 1.0 mm, the feed amount in the longitudinal direction is about 0.005 to 0.7 mm / rev, and if the cut amount is large, the feed amount should be small, Conversely, if the feed amount is large, the cutting amount should be suppressed small.

The value of S indicated by the contact area of the tool / work material geometrically calculated from the following formula may be about 0.001-1, preferably about 0.01-0.5, and cutting efficiency and good Can ensure a smooth surface.
In the case of plunge cutting, S = [blade width w (mm)] × [feed amount per rotation of work material f (mm / rev)]
In the case of longitudinal turning, S = [cutting amount d (mm)] × [feed amount per rotation of work material f (mm / rev)]

  The cutting method of the low-carbon free-cutting steel of the present invention can, of course, exhibit the maximum effect when applied to cutting low-carbon non-lead free-cutting steel.

  The result of cutting low-carbon free-cutting steel using the cutting tool of the present invention is shown below.

  The cutting tools having the TiN-containing hard film of the present invention (hereinafter also referred to as “coated tools”) shown in Table 1 were used. Similarly, the base material shown in Table 1 was coated with the surface layer material shown in Table 1 to a thickness of 2 μm to obtain a cutting tool. About the sintered cutting tool of this invention, the component is shown in each following example. A JIS B 4053-1996 P8 reference table 1 equivalent to K10 type (WC: 94.5%, Co: 5.5%) without coating was used as a K-type cemented carbide tool as a comparative material.

  Steels shown in Table 2 were used as low-carbon, lead-free free cutting steels for work materials. Here, the lead-free free-cutting steel-1 in the table means that the sulfur content of sulfur free-cutting steel SUM23 equivalent steel shown in JIS G 4808 is increased to 0.4% and B and N are 0.009% and 0, respectively. .01% added steel. SUM23 is sulfur free-cutting steel SUM23 equivalent steel shown in JIS G 4808. About steel other than the component of Table 2, the component is shown in each Example.

  The tool life of low-carbon free-cutting steel is different from that of structural steel tools, and even when the tool can withstand cutting, if the surface roughness is not sufficient, the tool life is judged and replaced. It is common to be done. Therefore, in this example, when the work steel is low-carbon non-lead free-cutting steel-1, the surface roughness Ry exceeds 7 μm, and when the work steel is SUM23, the surface roughness Ry is 20 μm. The tool life is indicated by the number of cuts by the tool when exceeding the limit.

  Specifically, the 20th and 50th roughnesses from the start of cutting were measured, and then the 100th, 150th and 50th roughnesses were measured. When the roughness exceeded the above standard for each work steel, it was determined that the tool life had been reached. At that time, machining was performed up to 600 pieces, and if the roughness was not deteriorated, the tool life was not reached, and the number of machining was set to> 600.

Example 1
In the plunge cutting, when the coated tool of the present invention was used, the effect of the shape of the cutting tool including the size of the cutting edge roundness of the cutting edge on the surface roughness of the cutting surface was compared. The cutting conditions, tools used, and work material are as shown in Table 3. In Table 3, numbers outside the scope of the present invention are underlined. The same applies to Table 4 and below.

  Among the coated tools shown in Table 1, the tool used is a K-type cemented carbide base material. The basic tool shape is a parting-off cutting tool having a cutting width of 5 mm, a main cutting edge rake angle of 15 °, and a clearance angle of 6 °. The work material shown in Table 2 is used.

  FIG. 3 shows an outline of the cutting method. The work material was free-cutting steel to which lead was not added, and a round bar having a work material diameter of φ50 mm was attached to a lathe and plunge-cut (grooved). One grooving cut (0.3 sec cut) was repeated 20 times, and the cut surface at the bottom of the groove was evaluated with a stylus roughness meter. Other cutting conditions are a cutting speed of 80 m / min, a feed of 0.05 mm / rev, and wet cutting using an oil-based cutting fluid.

  As is clear from Table 3, all of the examples having a cutting edge radius of 50 μm or less achieve a good roughness Ry. On the other hand, when the shape of the tool edge is out of the specified range, such as when the edge radius exceeds 50 μm or the rake angle is less than −10 °, the surface roughness of each work material extremely decreases.

  Comparing the results of the two types of work materials, the roughness Ry in SUM23 is slightly larger than the value of the roughness Ry of non-lead free cutting steel-1. On the other hand, when comparing the comparative example having a cutting edge radius of more than 50 μm and the present invention example having a cutting edge radius of 50 μm or less in each type, the roughness is improved by setting the cutting edge radius to 50 μm or less in all types. The effect of the present invention is exhibited by setting the cutting edge radius to 50 μm or less in any type of carbon-free free-cutting steel.

  A tool life of 600 times or more was achieved under all conditions including a cutting edge radius of 5 μm or less, and a good tool life was realized.

(Example 2)
In the longitudinal cutting, when the coated tool of the present invention was used, the influence of the shape of the cutting tool including the size of the cutting edge roundness on the surface roughness of the cutting surface was compared. The cutting conditions, tools used, and work material are as shown in Table 4. Other conditions are the same as in the first embodiment.

  FIG. 4 shows an outline of the cutting method. The work material was a wire drawing material having a diameter of 10 mm, and the outer periphery was cut 10 mm from the tip, and the tool was observed and surface roughness was evaluated after cutting 20 pieces.

  The tool shape is a peripheral cutting tool. The tool shape is the main cutting edge rake angle 5 °, clearance angle 5 °, secondary cutting edge rake angle 5 °, clearance angle 5 °, as shown in detail in Fig. 5, the front cutting edge angle is rotated by 2mm at the tip. This tool is parallel to the axis and has a so-called front cutting edge angle of 0 °. Cutting conditions are cutting speed: 60 m / min, cutting depth 1 mm, feed amount 0.05 mm / rev wet (water-soluble cutting oil).

  As can be seen from Table 4, all of the examples having a cutting edge radius of 50 μm or less achieve a good roughness Ry. On the other hand, a good surface cannot be obtained when the angle where the edge of the blade edge is easy is outside the specified range.

  A tool life of 600 times or more was achieved under all conditions including a cutting edge radius of 5 μm or less, and a good tool life was realized.

(Example 3)
In the plunge cutting, when the sintered tool of the present invention was used, the influence of the shape of the cutting tool including the size of the cutting edge roundness of the cutting edge on the surface roughness of the cutting surface was compared. The cutting conditions, tools used, and work material are as shown in Table 5.

  Table 3 shows the results of evaluating the influence of the shape of the sintered tool. The shape of the sintered tool adjusted to the specified material was changed, and the plunge cutting test shown in FIG. 3 was performed to evaluate the surface roughness of the groove surface. Cutting conditions and the like are a cutting speed of 80 m / min, a feed of 0.05 mm / rev, and wet cutting using an oil-based cutting fluid.

  As shown in Table 5, even in the case of a sintered tool, a good surface roughness cannot be obtained if the shape is insufficient as in the case of a coated tool.

  A tool life of 600 times or more was achieved under all conditions including a cutting edge radius of 5 μm or less, and a good tool life was realized.

Example 4
In longitudinal cutting, when the sintered tool of the present invention was used, the effect of the shape of the cutting tool including the size of the cutting edge roundness on the surface roughness of the cutting surface was compared. The cutting conditions, tools used, and work material are as shown in Table 6.

  Table 6 shows the results of evaluating the influence of the shape of the sintered tool. The shape of the sintered tool adjusted to the specified material was changed, and the longitudinal cutting test shown in FIG. 4 was performed.

  Tool shape is main cutting edge rake angle 5 °, clearance angle 5 °, secondary cutting edge rake angle 5 °, clearance angle 5 °, front cutting edge 4 is provided as shown in detail in FIG. This is a tool with a so-called front cutting edge angle of 0 °, which is parallel to the workpiece rotation axis by 2 mm. Cutting conditions are cutting speed: 60 m / min, cutting depth 1 mm, feed amount 0.05 mm / rev wet (water-soluble cutting oil).

  As shown in Table 6, a good surface cannot be obtained if the angle of the edge of the blade is easily outside the specified range.

  A tool life of 600 times or more was achieved under all conditions including a cutting edge radius of 5 μm or less, and a good tool life was realized.

(Example 5)
The materials of various components including lead free cutting steel were used as the work material, the conventional cemented carbide tool and the coated tool of the present invention were used as the cutting tool, and the surface roughness of the cutting surface was compared. The work material and cutting tool are as shown in Table 7. No. in Table 7 Nos. 54 to 59 are plunge cutting, No. Reference numerals 60 to 65 denote longitudinal turning, which are the same as those shown in FIGS. 3 and 4, respectively.

  That is, for longitudinal turning, the tool shape is a cutting edge radius of the main cutting edge of 5 μm or less, a rake angle of 5 °, a clearance angle of 5 °, a cutting edge radius of the secondary cutting edge of 5 μm or less, a rake angle of 5 °, a clearance angle of 5 °, As shown in detail in FIG. 5, the tool has a so-called front cutting edge angle of 0 ° in which the front cutting edge angle is parallel to the workpiece rotation axis by 2 mm at the tip. Cutting conditions are cutting speed: 60 m / min, cutting depth 1 mm, feed amount 0.05 mm / rev wet (water-soluble cutting oil).

  For plunge cutting, the tool shape is a radius of the cutting edge of the main cutting edge of 5 μm or less, a rake angle of 15 °, and a clearance angle of 6 °. Cutting conditions are a cutting speed of 80 m / min, a feed of 0.05 mm / rev, and wet cutting using an oil-based cutting fluid.

  No. in Table 7 Nos. 54 to 57 and 60 to 63 are low-carbon non-lead free cutting steels. 58, 59, 64 and 65 are low-carbon lead free cutting steels. More specifically, no. Nos. 54 and 60 are SUM23 equivalent steel. 55-57 and 61-63 are so-called low-carbon non-lead free-cutting steel in which S, Cr, B, etc. are added to SUM23 without containing lead. No. 58, 59, 64 and 65 are all SUM24L equivalent steel containing lead.

  In Table 7, “WC (K type)” of the conventional tool is a K type cemented carbide tool containing no Ti-based hard particles with a tool edge rounded to 50 μm or less, and TiAlN-1 and TiZrN— in the tool of the present invention. 1. TiN-1 used the tool shown in Table 1.

  In Table 7, Ry represents the surface roughness of the cut surface. ΔRy represents the difference between Ry of the tool of the present invention and Ry of the conventional tool.

  When comparing the present invention tool and the conventional tool between the lead-free free cutting steel to which Pb is not added and the lead free-cutting steel to which Pb is added, the tool material is changed from the conventional tool to the tool of the present invention. When the seed is changed, the surface roughness is greatly improved, but in the case of lead free cutting steel containing Pb, the surface roughness hardly changes. That is, it is understood that the component of the target work material should be specified.

  In addition, when observing the behavior of Ry for each type of low-carbon non-lead free-cutting steel, there is a difference in the level of Ry for each type. On the other hand, Ry of the tool of the present invention is a small value, and ΔRy is a large value. That is, the superiority of the tool of the present invention is obvious when low-carbon non-lead free-cutting steel is used as the work material.

  In this example, the tool life was measured for the 20th and 50th roughnesses from the start of cutting, and then the 100th, 150th and 50th roughnesses were measured. In Examples 54, 57, 60, and 63, when Ry exceeded 20 μm, the tool life was determined. In the other examples shown in Table 7, the tool life was determined when Ry exceeded 7 μm. As a result, when the conventional tool was used in the comparative example, the tool life was reached within 300 machining, and good surface roughness could not be obtained even with the first 20 tools. Further, even when the conventional lead free-cutting steel was cut with the inventive tool, the surface roughness was not so much improved, and no tool with a tool life exceeding 600 was found. On the other hand, in the case where the inventive tool was used in the invention example, the life was not reached even when the number of processing exceeded 600, and good surface roughness could be maintained.

(Example 6)
In the plunge cutting for cutting low-carbon lead-free free-cutting steel, the effect of each component condition of the coated tool and sintered tool was evaluated. Two kinds of component materials shown in Table 2 were used as work materials.

  No. in Table 8 Nos. 66 to 77 are coated tools. Reference numeral 78 denotes a K-type cemented carbide tool (comparative example) having no coating. The coating layer component was changed, and the cutting surface roughness was evaluated for each work material. No. 76 and 77 are comparative examples in which the components of the coating layer are outside the scope of the present invention. Table 9 shows sintered tools. 79 and 80 are examples of the present invention. 81 and 82 are comparative examples in which the Ti carbide component is outside the scope of the present invention. Tables 8 and 9 show the effect of the tool material type on the surface roughness. The tool shape is a plunge cutting (for parting off) tool, which has a cutting width of 5 mm, a radius of cutting edge of the main cutting edge of 5 μm or less, a rake angle of 15 °, and a clearance angle of 6 °. Other cutting conditions are a cutting speed of 80 m / min, a feed of 0.05 mm / rev, and wet cutting using an oil-based cutting fluid.

  In any case, if the specification of the material component of the tool surface layer is outside the range of the present invention, good surface roughness cannot be obtained. Further, in the case of a coated tool, not only the case where good surface roughness cannot be obtained outside the range, but also the coating may be peeled off and a sufficient tool life may not be obtained. As in Comparative Example 83, in the case of a high-speed steel tool, even if the lead-free free-cutting steel-1 has a good surface, SUM23 may not provide good performance.

  Such adhesion characteristics can be evaluated by measuring the contact area between the tool and the chips. The contact area varies depending on the components and materials of both the work material and the tool. Furthermore, the contact area of various steel materials and various tool material types in plunge cutting is shown in FIG. In the conventional combination K-type cemented carbide tool and Pb additive, the K-type cemented carbide tool is a suitable tool. However, in the specified tool of the present invention, the contact width 18 may be increased. It was. On the other hand, it can be seen that the lead-free free-cutting steel has a smaller contact width than the K-type cemented carbide in the invention-specified tools other than the K-type cemented carbide. These contact widths are finally reflected in the surface roughness, as shown in Tables 3 to 9 of the examples.

  As for the tool life, Example No. of the present invention. 66 to 75, 79, and 80 all had good results with a lifetime exceeding 600 times. Comparative Example No. Nos. 76 and 77 were deteriorated in surface roughness because peeling of the coating occurred in the initial stage of use. Comparative Example No. 78 and 81 to 83 all had a lifetime of less than 600 times.

(Example 7)
Table 10 shows the influence of the cutting method on the surface roughness. Using low-carbon lead-free free-cutting steel as a work material, the coated tool and sintered tool of the present invention shown in Table 10 were used, the cutting conditions were as shown in the table, and wet longitudinal turning was performed. The cutting edge radius of the main cutting edge is 5 μm or less, the rake angle is 15 °, and the clearance angle is 6 °. As the cutting condition, the cutting speed has a great influence, and therefore, the cutting speed was greatly changed for each tool material type. The work materials are non-lead free-cutting steel-1 and SUM23 shown in Table 2, and the tool shape is the same as that of FIG. 5 used for the longitudinal turning. In addition, No. A tool 82 is a sintered tool using cermet as a material. Cermet is composed mainly of carbides, carbonitrides, nitrides or composites of Ti, Ta, and Nb shown in Reference Table 2 in the lower part of JIS B 4053-1996 P8. It is a material sintered by connecting with a binder. Therefore, the surface layer constitutes the sintered tool of the present invention containing Ti.

  The work material was hot forged or rolled at φ80 mm in order to cut at a high speed, and then subjected to so-called low carbon steel normalization at 920 ° C. × 1 hr → cooling.

  As a result, as shown in Table 10, No. 1 of the present invention. 78-84 was able to realize good surface roughness. Comparative Example No. In 85-87, the cutting speed exceeded 400 m / min, and almost no cutting was possible.

(Example 8)
Using a conventional cutting method that uses low-carbide free-cutting steel as the work material, uses a K-type cemented carbide tool (the same as that used in Example 5) as the cutting tool, and has a radius of cutting edge exceeding 50 μm. And cut. Cutting conditions other than the cutting edge radius were the same as in Example 5 above.

  Table 11 shows the components of the work material, the cutting edge radius, and the cutting surface roughness results Ry for each cutting method. As is apparent from Table 11, the cutting surface roughness is not good as compared with the above-described embodiment of the present invention. On the other hand, the tool life exceeded 600 times as a result of increasing the cutting edge radius.

It is a figure which shows the relationship between the finished surface and tool shape in plunge cutting, (a) is a perspective view which shows the plunge cutting situation, (b) is a figure which shows the relationship between the cutting edge and finished surface in plunge cutting, (c) is The perspective view which shows the detail of the tool for plunge cutting, (d) is a figure which shows cutting-edge cross-sectional shape. It is a figure which shows the relationship between the finishing surface and tool shape in longitudinal turning, (a) is a perspective view which shows a longitudinal turning situation, (b) is a figure which shows the relationship between the cutting edge and finishing surface in longitudinal turning, (c) is The perspective view which shows the tool for longitudinal turning details, (d) is a figure which shows cutting-edge cross-sectional shape. It is a figure which shows a plunge cutting and an evaluation surface, (a) is a perspective view which shows a plunge cutting situation, (b) is an evaluation surface. It is a figure which shows a longitudinal turning and an evaluation surface, (a) is a perspective view which shows a longitudinal turning situation, (b) is an evaluation surface. It is a figure which shows a longitudinal turning tool, (a) is a schematic diagram, (b) is a detailed figure. It is a figure which shows the contact width observation example of the rake face in cutting, (a) is sectional drawing which shows the outline | summary of the chip | tip production | generation part near a tool blade edge, (b) is for measuring the contact width of the tool rake face in cutting FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cutting tool 2 Main cutting edge 3 Sub cutting edge 4 Front cutting edge 5 Rake face 6 Side relief face 7 Cutting edge roundness 8 Rake angle 9 Relief 10 Nose radius 11 Work material 12 Groove 13 Cutting face 14 Feed direction 15 Work material feed Direction 16 Chip 17 Component edge 18 Contact width 21 of rake face Finished surface 22 with main cutting edge Finished face 23 with minor cutting edge Cutting face 24 Evaluation surface

Claims (9)

  Either one or both of the main cutting edge and the auxiliary cutting edge have a radius of 50 μm or less, and a part or all of the surface layer in contact with the work material is coated with a hard coating, A cutting tool comprising: N: 40 to 60% and Ti: 40 to 60% in atomic%, and the balance substantially consisting of inevitable impurities.   Either one or both of the main cutting edge and the auxiliary cutting edge have a radius of 50 μm or less, and a part or all of the surface layer in contact with the work material is coated with a hard coating, In addition to N: 40 to 60% in atomic%, Ti: 10% or more and less than 60%, a total of one or two of Al or Zr is included in a range of 50% or less in atomic%, and the balance is substantially A cutting tool comprising inevitable impurities.   Cutting according to claim 1 or 2, wherein the rake angle of either or both of the main cutting edge and the auxiliary cutting edge is in the range of -10 to 30 °, and the clearance angle is 2 to 15 °. tool.   The cutting tool according to claim 3, wherein the base material disposed inside the hard coating is one of tool steel, cemented carbide, cermet, and ceramics.   One or both of the main cutting edge and the auxiliary cutting edge have a radius of cutting edge of 50 μm or less, and at least a part or all of the surface layer in contact with the work material has carbide, carbonitride, nitridation containing Ti And a hard phase of Ta, Nb, W carbide, carbonitride, nitride and their composites containing no Ti, and 30% by mass or less of Co, A cutting tool comprising one or two kinds of Ni in a total of 20% by mass or less, and the balance being made of a sintered material substantially composed of inevitable impurities.   6. The cutting tool according to claim 5, wherein the rake angle of one or both of the main cutting edge and the auxiliary cutting edge is in the range of −10 to 30 °, and the clearance angle is 2 to 15 °.   The cutting tool according to any one of claims 1 to 6, wherein the cutting tool is for cutting low-carbon non-lead free-cutting steel.   Cutting of low-carbon free-cutting steel using the cutting tool according to any one of claims 1 to 6, using low-carbon free-cutting steel as a work material, and cutting at a cutting speed of 1 to 400 m / min. Method.   A cutting method for low-carbon non-lead free-cutting steel, characterized by using the cutting tool according to claim 7 and using low-carbon non-lead free-cutting steel as a work material and cutting at a cutting speed of 1 to 400 m / min. .