JP4817044B2 - Cutting tool manufacturing method - Google Patents

Description

The present invention relates to a method for producing a cutting tool. Specifically, it is a manufacturing method of a cutting tool used for various cutting processes such as turning, drilling, end milling, and milling, and can largely suppress adhesion of a workpiece to be contacted, and further, a base material and a film. It is related with the manufacturing method of the cutting tool which is excellent in adhesiveness of this and can ensure the outstanding abrasion resistance by this.

  As the required characteristics of various industrial products such as steel pipes become more sophisticated, it is required to improve the wear resistance of various cutting tools such as those for threading a steel pipe end.

  More specifically, in order to further increase the cutting efficiency, there is a demand for a cutting tool that can ensure good wear resistance even when cutting at high speed. Further, there is a cutting tool having an excellent cutting function without causing adhesion to a high-strength material such as 13Cr martensitic stainless steel, and difficult-to-cut materials such as austenitic and ferritic stainless steel. It is requested.

In order to cope with such a demand, conventionally, carbide, nitride and carbonitride such as Ti and Zr, Al ₂ O _{3 and the} like are used as a hard protective film on the surface of a substrate made of cemented carbide. It is made to form. Specifically, the above-mentioned hard protective film is formed as a single layer or multiple layers on the surface of the base material by a chemical vapor deposition method (CVD method) or a physical vapor deposition method (PVD method) with a thickness of several μm to several tens of μm. Forming is performed to suppress wear of the cutting tool and adhesion to the workpiece.

However, conventional hard protective films such as TiN, Ti (C, N), TiAlN, and Al ₂ O ₃ have excellent adhesion and wear resistance at room temperature, but are processed at high speed. When cutting high-strength materials, the contact surface with the material to be cut rises to a high temperature of 1000 ° C. or higher, which causes oxidative decomposition and chemical reaction with the material to be cut, resulting in a decrease in adhesion. . As a result, a decrease in wear resistance, adhesion of the workpiece, and the like occur, and the function as the hard protective film is significantly impaired.

  For this reason, the hard protective film is required to have higher oxidation resistance and adhesion than before, and several new techniques have been proposed to meet this demand.

For example, Patent Document 1 discloses a technique for suppressing oxidative decomposition of a hard protective film, in other words, a technique for improving oxidation resistance characteristics by increasing an oxidation start temperature. More specifically, Patent Document 1 discloses nitriding one or more elements selected from the group consisting of Group 4a elements, Group 5a elements, Group 6a elements, and Al formed on a substrate. B ₄ C, BN, TiB ₂ , TiB, TiC, WC, SiC, SiN _X (X = A cutting tool containing at least one ultrafine compound selected from the group consisting of 0.5 to 1.33) and Al ₂ O ₃ has been proposed.

Patent Document 2 discloses a technique for improving the plastic deformability in the vicinity of the surface of a base material (base material) and improving the adhesion with a film. That is, Patent Document 2 describes a coated cemented carbide in which a hard composite layer composed of a hard phase particle and a coating particle of a base material is provided between a cemented carbide base material and a hard coating.

  More specifically, in Patent Document 2, the hard phase particles are tungsten carbide, or carbide, tungsten carbide and carbides of group 4a element, group 5a element and group 6a metal of the periodic table, nitride and carbonitride, In addition, a cubic compound composed of one or more of these mutual solid solutions and having a cemented carbide whose binder phase is an iron group metal as a base material, and having a depth of 3 to 20 μm from the base material surface to the inside. In addition, the amount of the binder phase is 2% by weight or less, and the hard phase particles of the base material and the 4a group element, 5a group element, 6a group element, Al and Si carbides, nitrides and oxides of the periodic table, And a uniform hard composite layer composed of one or more kinds of compound particles selected from these mutual solid solutions, and further carbide, nitride from the group 4a element to Si on the surface of the base material And oxides, and their mutual solid solutions Coated cemented carbide coated with a single layer or a 0.5~20μm hard film of consisting of two or more layers of the multilayer consisting of one or more compounds selected from have been proposed.

  Patent Document 3 discloses a high-hardness carbon film having a specific density. The carbon film proposed in Patent Document 3 can improve the wear resistance and durability of a cutting tool in place of a diamond film or a diamond-like carbon film.

JP 2001-293601 A JP 2002-38205 A JP 2003-147508 A

By using the cutting tool proposed in Patent Document 1 described above, excellent wear resistance and high lubricity can be secured even in high-speed cutting at 250 m / min, and an effect of suppressing adhesion can be obtained. However, the base material of the cutting tool is mainly composed of the nitride or carbonitride of the specific element, and includes at least selected from B ₄ C to Al ₂ O ₃ described above. It is necessary to provide a film containing one kind of ultrafine compound. For this reason, there exists a problem that manufacture by industrial mass-production scale is very difficult.

  Next, the coated cemented carbide proposed in Patent Document 2 has a hard composite layer that suppresses plastic deformation of the base material and at the same time enhances the adhesion between the base material and the hard film. Even at extremely high cutting speeds of minutes, excellent wear resistance can be ensured and a long tool life can be obtained. However, this coated cemented carbide first removes the iron group metal that is the binder phase from the surface of the cemented carbide that is the base material, and then covers the hard film described above, and between the hard film and the base material. It is necessary to form the hard composite phase in the range of 3 to 20 μm from the surface of the base material. For this reason, it is very difficult to manufacture on an industrial mass production scale, and the manufacturing cost is increased.

  The technique proposed in Patent Document 3 is mainly intended for cold working with a tool use temperature of 400 ° C. or lower, and is not suitable for hot working. That is, since the carbon film reacts with oxygen and vaporizes as carbon dioxide gas at 400 ° C. or higher, there is a problem that the function as the hard protective film is remarkably impaired.

The present invention has been made to solve such problems of the prior art, can greatly suppress the adhesion of the workpiece to be contacted, and is excellent in adhesion between the substrate and the film, and thereby excellent. All cutting tools capable of ensuring wear resistance, and to provide a manufacturing method of the cutting tool which enables the production on an industrial mass production scale.

  In order to solve the above-mentioned problems, the inventors of the present invention have studied in detail the chemical composition of a hard protective film covering the surface of the base material using a base material made of cemented carbide and a method for generating the film. did. As a result, the following findings (a) to (g) were obtained.

  (A) In order to suppress wear and further suppress adhesion of the workpiece to be contacted, it is necessary that the oxidative decomposition start temperature of the film which is a hard protective film is high, and the film is It is necessary to be able to suppress chemical reaction with the workpiece to be contacted, in particular, liquid phase precipitation.

  (B) SiC has an oxidation decomposition starting temperature of 1200 ° C. or higher, and can maintain a very stable state even at high temperatures.

  (C) SiC is thermally stable. For this reason, even if exposed to high temperature, it is excellent in adhesiveness with a base material, and does not peel. And, since the linear expansion coefficient of SiC is sufficiently small compared to the cemented carbide that is the base material, when exposed to high temperature, tensile stress is generated at the interface between the base material and the film, and the adhesion with the base material is Very good.

  (D) SiC is mechanically stable and excellent in hardness, Young's modulus, thermal shock resistance, and the like, and is therefore suitable as a hard protective film.

  (E) For example, if a steel material coated with SiC is used as a cutting tool for various steel materials, SiC has a very low reactivity with Fe as the main component of the steel material that is the material to be cut. It can exist in a chemically stable state even at high temperatures during high-speed cutting.

  (F) In order to make the chemical composition of SiC less likely to change and to be applied as a film without impairing the above-mentioned physical properties, after high-purity SiC is sufficiently sintered, this is used as a raw material, that is, a composition. What is necessary is just to produce | generate a membrane | film | coat on the base-material surface by a physical vapor deposition method as a film | membrane source (henceforth a "target"). In other words, the physical properties of the film obtained by depositing cluster ions excited from the above target by the physical vapor deposition method on the surface of the substrate are the same as the above physical properties of SiC.

  (G) By adopting the physical vapor deposition method, accurate mass transfer from the target to the coating becomes possible, and the use of a raw material fine powder sintered compact target having a particle size of 0.4 μm or less is preferable. Therefore, it is possible to directly generate a dense film regardless of the surface irregularity state of the substrate.

The present invention has been completed based on the findings of the inventors.
That is, according to the present invention, a film whose outermost layer is made of SiC is formed on the surface of a base material made of cemented carbide at room temperature using a laser deposition method using a YAG laser having an oscillation wavelength of 266 nm using SiC as a film forming source. The present invention provides a method for manufacturing a cutting tool .

By producing a cutting tool made of SiC at the outermost layer of the coating at least on the contact surface or flank surface in contact with the workpiece by the manufacturing method according to the present invention, adhesion of the workpiece to be contacted can be greatly suppressed. The adhesion between the substrate and the film is excellent, and it is possible to ensure excellent wear resistance . According to the method for manufacturing a cutting tool according to the present invention, it is possible to stably and surely obtain a cutting tool having the above-described characteristics and to manufacture it on an industrial mass production scale.

  Hereinafter, a cutting tool and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the accompanying drawings as appropriate.

  FIG. 1 is a diagram illustrating a schematic configuration of a cutting tool according to the present embodiment. FIG. 1A schematically illustrates a state in which a cylindrical workpiece is cut by the cutting tool according to the present embodiment. FIG. 1B schematically shows a cross section near the flank of the cutting tool shown in FIG. As shown to Fig.1 (a), the cutting tool 1 which concerns on this embodiment has a substantially rectangular parallelepiped shape, The four side surfaces are made into a flank and the upper and lower surfaces are rake faces. And the corner | angular part which the two flank 1a, 1b and the upper rake face 1c cross | intersect is made into a cut location, and the outer peripheral surface of the workpiece M is cut by this cut location. More specifically, the cutting material 1 is rotated in the circumferential direction while the cutting portion of the cutting tool 1 is in contact with the outer peripheral surface of the cutting material M, and the cutting tool 1 is moved to the cutting material M. The outer peripheral surface of the workpiece M is cut by feeding it at a predetermined speed in the axial direction.

  The cutting tool according to the present invention includes a base material made of a cemented carbide and a film formed on the surface of the base material, and at least an outermost layer of the film is made of SiC at a contact surface in contact with a workpiece. Alternatively, the outermost layer of the film is made of SiC at least on the flank. In the present embodiment, the outermost layer of the coating is formed at least on the flank in consideration of the fact that the other two flank surfaces other than the flank surfaces 1a and 1b may be used for cutting by changing the above-described cut portions. Is made of SiC. That is, as shown in FIG.1 (b), the cutting tool 1 which concerns on this embodiment is equipped with the base material 1A which consists of a cemented carbide, and the membrane | film | coat formed in the surface of the base material 1A, At least in a flank The outermost layer of the coating 1B is made of SiC. Hereinafter, the outermost layer is appropriately referred to as “SiC layer”.

  Base material 1A consists of a cemented carbide as mentioned above, for example, the cemented carbide which has WC and WC-TiC as a main component can be used.

  The coating 1B can adopt either a single layer structure or a multilayer structure, but in any case, the outermost layer (in the case of a single layer, the layer) is composed of SiC as described above. As described above, SiC has a high oxidative decomposition temperature of 1200 ° C. or higher, and is thermally and mechanically stable, so that it has excellent adhesion to the substrate 1A even when exposed to high temperatures, and peels off. And stable mechanical properties can be exhibited. In addition, when the material to be cut M is various steel materials, SiC has a very low reactivity with Fe as a main component of the steel material that is the material to be cut M, so that it is chemically stable even in a high temperature state during high speed cutting. Can exist in the state. Therefore, according to the cutting tool 1 according to the present embodiment, the adhesion of the workpiece M to be contacted can be greatly suppressed, and the adhesiveness between the base material 1A and the coating 1B is excellent, thereby providing excellent wear resistance. Can be secured.

  In addition, when the thickness of a SiC layer is less than 0.5 micrometer, sufficient abrasion resistance may not be acquired. On the other hand, even if the thickness of the SiC layer exceeds 10 μm, the wear resistance is saturated and the cost is increased. Therefore, the thickness of the SiC layer is preferably 0.5 to 10 μm, more preferably 1 to 5 μm.

  As a manufacturing method of the cutting tool 1 (SiC layer generation method), a coating 1B in which the outermost layer is a SiC layer on the surface of a base material 1A made of cemented carbide using a physical vapor deposition method using SiC as a film forming source. Is preferably formed. By producing a SiC layer by physical vapor deposition, various characteristics of SiC, that is, characteristics such as high oxidative decomposition temperature, thermal and mechanical stability, and chemical stability in high temperature conditions during high-speed cutting, etc. Can be secured.

  More specifically, in an inert gas atmosphere introduced into the vacuum chamber, the cluster ions are excited with a SiC sintered body as a target, and the excited cluster ions are deposited (preferably with a thickness of 0.5 to 10 μm) to obtain a film (SiC layer).

Here, it is preferable to perform the treatment under an inert gas atmosphere introduced into the vacuum chamber in order to prevent unnecessary oxidation of SiC. In addition, as an inert gas, nitrogen gas, Ar gas, etc. should just be selected suitably according to a target. For example, these gases may be introduced into a vacuum chamber evacuated to 10 ⁻³ Pa or less, and the pressure in the vacuum chamber may be maintained at about 10 ⁻³ Pa.

  In addition, the excitation of cluster ions may be performed by irradiating the target SiC sintered body with a laser beam, an electron beam, or various ions accelerated at high speed. In particular, it is preferable to employ a laser deposition method that uses a laser beam for excitation of cluster ions in that the generation temperature of the SiC layer can be about room temperature (20 ° C.). In other words, if the generation temperature of the SiC layer is high, a dimensional change occurs in the substrate 1A due to thermal stress. As a result, the adhesion at the interface with the coating 1B may be reduced, and the wear resistance may be reduced. According to the deposition method, the generation temperature can be set to about room temperature, and there is no possibility that the above situation will occur.

  As the sintered body of SiC as a target, it is preferable to use a sintered body of fine powder having a particle size of 0.4 μm or less and a purity of 97% or more at a theoretical density of 95% or more. By using the above sintered body, various characteristics of the SiC layer can be secured stably and reliably. The particle size of the powder is the diameter of the particles having a particle size distribution of 50% or more, and the theoretical density of sintering is the single lattice volume calculated from the lattice constant and the content in the single lattice. The density calculated from the atomic mass.

  Here, the particle size is preferably set to 0.4 μm or less because it is possible to reduce the film formation energy by miniaturizing the cluster ions excited from the target. In addition, since the film formation energy becomes so low that ions serving as nuclei during film formation are easily generated, miniaturization of cluster ions is effective.

  Moreover, it is preferable to use a fine powder having a purity of 97% or more in order to improve the uniformity of the film quality after film formation. Furthermore, it is preferable to use a material sintered at 95% or more of the theoretical density. If the target sintered at less than 95% of the theoretical density is used as a target, The gas constituting the inert gas atmosphere may thermally expand when irradiated with laser light, electron beam, or various ions accelerated at high speed for cluster ion excitation, and may cause cracks or cracks in the target. This is to avoid this situation.

  As described above, according to the cutting tool 1 according to the present embodiment, the outermost layer of the coating 1B is made of SiC at least on the flank surface, thereby greatly suppressing adhesion of the workpiece M to be contacted. In addition, the adhesion between the substrate 1A and the coating 1B is excellent, and it is possible to ensure excellent wear resistance. Moreover, according to the manufacturing method of the cutting tool 1 which concerns on this embodiment, while being able to obtain the cutting tool 1 which has said characteristic stably and reliably, manufacture on an industrial mass-production scale is possible.

  Hereinafter, the features of the present invention will be further clarified by showing examples and comparative examples.

<Example 1>
A WC cemented carbide with a chip size of ISO model SNMN120408 with a width of 12.7 mm, a length of 12.7 mm and a thickness of 4.76 mm is used as a base material, and a film made of SiC is applied to this by physical vapor deposition (specifically Was generated by the laser deposition method. Details of film formation by the laser deposition method are as follows.

  That is, as the SiC raw material powder, a commercially available powder composition having a purity of 97% or more and a particle size (that is, an average diameter) of 0.4 μm or less was prepared. Next, these raw material powders are granulated using polyvinyl alcohol as an organic binder, and a cemented carbide mold is used so that the size after sintering becomes a pellet shape with a diameter of 30 mm and a thickness of 10 mm. And molded under pressure.

  The binder removal and firing conditions were such that the sintered density was 95% or more of the theoretical density calculated from the lattice constant of a single lattice by XRD (X-ray diffraction pattern) measurement. Specifically, firing was performed in a neutral atmosphere at 1500 ° C. × 1.0 hour.

  Using a pellet-like sintered body having a diameter of 30 mm and a thickness of 10 mm obtained as described above, a SiC film was formed on a WC cemented carbide as a substrate by a laser deposition method.

  That is, as shown in a schematic configuration in FIG. 2, the substrate 1 </ b> A was placed on the turntable 4 on the substrate film forming stage 5 provided in the sealed chamber 3. The substrate 1A was previously washed with pure water and ethanol, and then sufficiently dried, and 20 pieces on the turntable 4 so that the rake face side of the chip was on (in FIG. 2, one substrate for convenience) 1A is shown).

Next, evacuation was performed until the pressure in the chamber 3 became 10 ⁻³ Pa, and then an inert gas (Ar gas) was introduced into the chamber 3 to keep the inside of the chamber 3 at 10 ⁻³ Pa.

  Next, the laser beam 7 was irradiated from the laser light source 6 to the target 2 to excite the cluster ions 8, and the excited cluster ions 8 were deposited on the substrate 1A to form a film having a thickness of 5 μm. As the laser light source 6, a YAG laser having an oscillation wavelength of 266 nm was used, and the output of the laser light 7 was controlled to about 500W.

  Note that the temperature in the chamber 3 was set to 20 ° C. throughout the processing by the laser deposition method.

  As described above, a chip having a SiC film was produced.

<Example 2>
As physical vapor deposition, RF (Radio Frequency) sputtering using high frequency current to excite cluster ions 8 from the target 2 is used, and the temperature in the chamber 3 is set to 300 ° C. Under the conditions, a SiC film was formed on the WC cemented carbide as the base material to produce a chip.

<Comparative Example 1>
A chip was produced by forming a TiN film on a WC cemented carbide as a base material by RF sputtering under substantially the same conditions as in Example 2 except that the target 2 was a TiN sintered body.

<Comparative example 2>
The WC cemented carbide as the base material itself was used as a chip without forming a film.

<Evaluation test>
The adhesion of each of the coating films of Examples 1 and 2 and Comparative Example 1 was evaluated. In addition, a turning test was performed using the tip provided with each coating of Examples 1 and 2 and Comparative Example 1 and the tip of Comparative Example 2, and the amount of wear was investigated. Moreover, about the chip | tip of Examples 1, 2 and the comparative example 1, the adhesion state of a to-be-cut material was investigated.

  The adhesion of the film was investigated by a normal scratch method. That is, a 2.0 μm diameter needle was brought into contact with the surface of the film, and a scratch test was performed by load sweeping of 0 to 100 N to investigate the presence or absence of a signal indicating a decrease in adhesion.

そして、上記の切削試験を行った後、光学顕微鏡を用いて、チップ逃げ面の平均摩耗量を計測した。 The turning test was performed under the following conditions using a round bar having a chemical composition shown in Table 1 and having a diameter of 100 mm and a Vickers hardness (HV) of 250 as a test material.
Feed amount: 0.1 mm / rev,
Cutting depth: 1.5 mm,
Cutting speed: 200 m / min,
Cutting time: 540 seconds Lubrication: Dry (no lubrication)

And after performing said cutting test, the average abrasion loss of the chip flank was measured using the optical microscope.

<Evaluation results>
Table 2 and FIG. 3 show the results of the above tests.

(1) Adhesiveness As shown in Table 2, in the case of the chip having the SiC film according to Examples 1 and 2, even when the upper limit is 100 N load, no signal of lowering the adhesive force is detected, and the film is good. It had adhesion. On the other hand, in the case of the chip having the TiN film according to Comparative Example 1, a signal for decreasing the adhesion was observed at 80 N, and the film adhesion was inferior. From the above results, it is clear that the cutting tool according to the present invention is excellent in adhesion.

(2) Amount of wear As shown in Table 2 or FIG. 3, in the case of the chip having the SiC film according to Examples 1 and 2, the amount of wear (the amount of wear after 180 seconds from the start of cutting) is 7 μm, Whereas the chip having a TiN film according to Comparative Example 1 was extremely small as 10 μm, it was as large as 15 μm, and the ground (base material) was completely exposed. From the above results, it is clear that the cutting tool according to the present invention is excellent in wear resistance.

(3) Adhesion In the case of the chip having the TiN film according to Comparative Example 2, adhesion of the work material was observed. Then, when the chip surface was observed in detail using SEM (scanning electron microscope), it became clear that not only the adhesion to the chip surface but also the TiN film was peeled off. On the other hand, no adhesion was observed on the chip surface having the SiN film according to Examples 1 and 2. Also, no peeling of the film was observed.

FIG. 1 is a diagram showing a schematic configuration of a cutting tool according to an embodiment of the present invention. FIG. 2 is a diagram showing a schematic configuration of a cutting tool manufacturing apparatus (film generating apparatus) according to an embodiment of the present invention. FIG. 3 is a graph showing an example of a wear amount evaluation result of cutting tools according to examples and comparative examples of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cutting tool 1A ... Base material 1B ... Film | membrane 2 ... Target 3 ... Chamber 4 ... Turntable 5 ... Base material film-forming stage 6 ... Laser light source 7. ..Laser beam 8 ... Cluster ion M ... Work material

Claims (1)

  Using a laser deposition method with a YAG laser having an oscillation wavelength of 266 nm using SiC as a film formation source, a coating film made of SiC is formed on the surface of a substrate made of cemented carbide at room temperature. Cutting tool manufacturing method.

Images