JPH0966404A - Covered hard alloy tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve deficit resistance and wear resistance and attempt a long life by removing some layers counted from an upper side out of a ceramic film for constituting a cover and exposing the film having a larger crystal grain than a specific aspect ratio on the surface of this removed part. SOLUTION: In a covered hard alloy tool formed with the covered film 4 of multi-layer ceramic film on the surface of the mother material 5 consisting of a hard alloy and containing at least one layer of the cover having a crystal grain with the aspect ratio 5 or less in this covered film 4, out of the ceramic film for constituting the cover, some layers counted from an upper layer side are removed partially on the area (cutting edge ridgeline part A) in which the friction to a material to be processed is generated or across the entire area of a friction area. It is removed so that at least one layer of the cover having a crystal grain with the aspect ratio (1/d: l is the major axis diameter, d is the minor axis diameter) 5 or less may be contained in the removed layer and a film having a larger crystal grain than the aspect ratio 5 may be exposed on the surface of the removed part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated hard alloy tool used as a cutting tool or other wear resistant tool which is required to have wear resistance, and more particularly, to a coating having excellent peeling resistance and chipping resistance of a multilayer ceramic film. Hard alloy tools.

[0002]

2. Description of the Related Art Conventionally, as a material for cutting steel, cemented carbide (alloy in which carbonitrides of Ti, Ta and Nb are added to WC-Co alloy) has been used. With the increase in speed, cemented carbide, cermet, or alumina-based or silicon-nitride-based ceramic is used as the base material for CV on the surface.
The D or PVD method is used to form a film of a carbide, nitride, carbonitride, carbonitride, boronitride, oxide or a solid solution of IVa, Va, VIa group metals or Al of the periodic table of 3 to 3 The use rate of hard alloy tools coated to a thickness of 10 μm is increasing. At the beginning of the development of the coated tool, a tool coated with a high hardness titanium compound with excellent wear resistance on the flank appeared, but as the cutting conditions became faster, titanium was used to suppress crater wear on the rake face. A tool with Al ₂ O ₃ excellent in oxidation resistance coated on the coating of the system compound and gold TiN on the outer layer for identifying the cut (used) corner has appeared, and nowadays,
The coated hard alloy having this film structure occupies the majority, and the oxide film such as Al ₂ O _{3 in the} coating film is indispensable.

As described above, by increasing the thickness of the coating or by including the Al ₂ O ₃ film in the coating, the wear resistance of the tool is certainly improved, but the fracture resistance is decreased. There was a tendency. This is because the thickness of the coating film, which is a brittle material, becomes the crack length when the film is made thick, and the surface roughness of the coating film is reduced by coating the Al ₂ O ₃ film. It Therefore, in order to improve the fracture resistance, in JP-A-55-150941 and JP-B-5-9201, the coating is thinned only on the cutting edge ridge, or in JP-A-62-228305 and JP-A-5-57507.
Proposes that the surface roughness of the Al ₂ O ₃ film be below a certain specified value.

[0004]

The technique disclosed in the above publication has some effect on the fracture resistance, but has reached a sufficient effect on the wear resistance, particularly the peeling resistance of the film. However, the tool life was short because of damage caused by peeling of the film. Therefore, it has been desired to develop a coated hard alloy tool in which the peeling resistance of the film is sufficiently taken into consideration.

In view of the above conventional circumstances, the present invention improves the fracture resistance and wear resistance, in particular, the fracture resistance and the peeling resistance of the film in a well-balanced manner, thereby achieving excellent performance in cutting metal materials. It is an object of the present invention to provide a coated hard alloy tool which exhibits the above-mentioned and exhibits a long life.

[0006]

In order to achieve the above object, the present inventors have studied and studied the cutting mechanism in cutting a metal material, and as a result, have found that a multilayer ceramic film is formed on the surface of a base material made of a hard alloy. In the coated hard alloy tool, the coating comprises at least one coating having crystal grains with an aspect ratio of 5 or less, and the ceramic film constituting the coating is counted from the upper layer side. Several layers are partially or entirely removed over the region where friction with the work material occurs, and the removed layer includes at least one coating film having crystal grains with an aspect ratio of 5 or less, Aspect ratio of 5 on the surface of the removed part
It was found that the peeling resistance and the chipping resistance of the film can be improved significantly and in a well-balanced manner by making the structure in which the film having larger crystal grains is exposed.

It is most preferable to completely remove the coating film having crystal grains with an aspect ratio of 5 or less in the friction region, for example, the cutting edge ridge portion. However, when the removal form is local, or in the coating film, the aspect ratio is reduced. In a form in which a plurality of coating films having crystal grains with a ratio of 5 or less are present, at least one layer of the coating films having crystal grains with an aspect ratio of 5 or less is locally present at the cutting edge ridge portion or at the ridge portion. The effect of the invention can be obtained even when the entire area is removed.

The cutting edge ridge portion referred to here is a region where the cutting edge is strengthened, for example, as shown in FIGS.
It is a part A of (c). In both figures, 1 is a rake face and 2 is a flank face. Further, FIG. 1 (b) shows the strengthening process by round honing and FIG. 1 (c) shows the strengthening process by chamfer, but it seems that the chamfering of the plane of FIG. 1 (c) is replaced by a gentle arc surface. A ridge line portion that has undergone various strengthening treatments is also possible.

The aspect ratio was measured by taking a photograph of a thin film sample with a TEM (Transmission Electron Microscope) and using the photograph. The schematic diagram is shown in FIG. The aspect ratio was calculated by 1 / d. Here, 1 is the major axis diameter and d is the minor axis diameter.

The removal of the coating film having a crystal grain with an aspect ratio of 5 or less is effective if it is removed in a region of 10% or more of the cutting edge length involved in cutting, but the removal rate is 50.
% Or more, more preferably 100%, the effect is particularly remarkable. The removal rate here is determined by observing the tool edge with a scanning electron microscope from an appropriate angle and confirming the existence state of a film having crystal grains with an aspect ratio of 5 or less. An arbitrary line parallel to the cutting edge is drawn on the film, and a film having crystal grains with an aspect ratio of 5 or less at a portion of the cutting edge length related to cutting including the nose R portion 3 (see FIG. 1a) on that line Is expressed as a percentage of whether or not the disappearance has occurred.

FIG. 4 illustrates this definition.
Here, the case where the coating film has a three-layer structure of a TiCN film / Al ₂ O ₃ film / TiN film from the base material side is taken as an example. As a result of TEM observation, the aspect ratio of each film quality is Ti
CN film is about 10, Al ₂ O ₃ film is about 3, TiN film is about 1
Met. The range of α in FIG. 9A represents the length involved in cutting the cutting edge. (B) and (c) of the same figure are SEM composition images after the removal of the upper layer film in that portion. (D) is a cross-sectional view taken along the line XY in (b), and (e) is (c).
It is an XY cross section of a figure. In this composition image, TiN, Al ₂
O ₃ and TiCN appear to have different color tones. Therefore, the lines C parallel to the cutting edges are shown in FIGS. 4 (b) and 4 (c), respectively.
And see the part of this line where Al ₂ O ₃ or TiCN is exposed. In FIG. 4B, Al ₂ O is on the line C.
₃ is not present at all, therefore the removal rate of Al ₂ O ₃ is 10
0%. On the other hand, in the case of FIG. 4C, the cutting edge ridge line portion A
TiN, Al ₂ O ₃ , and TiCN are scattered and exposed in the inside. Since such a state occurs depending on the state of the removal process, in this case, the length a ₁ to a _{1 in} which the lower layer of TiCN appears on the surface on the line C (that is, Al ₂ O ₃ is removed). Add ₈ and (a ₁ + a ₂ + ...
a ₈₎ / cutting edge determining removal rate by the length expression.

It is not always necessary to completely remove the coating film having crystal grains with an aspect ratio of 5 or less contained in the coating layer when the film has several layers. However, the aspect ratio is 5
Among the coatings having the following crystal grains, the coating with the minor axis diameter of the crystal grains larger than 0.7 μm has peeling resistance when it is removed at least at a part of the cutting edge ridge line portion which is the designated area. Particularly preferred for improvement. Among them, an Al ₂ O ₃ film having an aspect ratio of 3 or less and a crystal grain minor axis diameter of more than 0.7 μm has particularly poor peeling resistance, and therefore, the Al ₂ O ₃ film and the Al ₂ O ₃ film are poor.
_It is preferable that the film mainly composed of ₃ does not exist at all on the outermost surface of the cutting edge ridge. The film mainly made of _{Al 2 O 3, Al 2 O} 3 and ZrO _2, Al ₂ O ₃ and TiC,
It is a composite film of Al ₂ O ₃ and AlN, etc., in which Al ₂ O ₃ is the main film.

Besides, although the lower layer film is naturally exposed at the portion where several layers of film are removed from the upper side in this way,
The exposed film is mainly composed of nitride or carbonitride, and in particular, TiCN having a C: N molar ratio in the range of 5: 5 to 7: 3.
A membrane is particularly preferable.

It is particularly preferable that the residual stress in the film exposed on the surface of the removed portion is -5 to 10 kgf / mm ² . Further, the average value of the surface roughness Ra of the exposed film is 0.
It is also very preferable that the thickness is 05 μm or less, and it is further preferable that the exposed film is a TiCN film having the maximum diffraction intensity on the (422) plane or the (311) plane.

It is particularly preferable that the aspect ratio of the crystal grains in the film exposed on the surface of the removed portion is 10 or more.

[0016]

In the cutting of metal materials, especially the cutting of steel, the maximum temperature of the rake face may be as high as 1000 ° C. or higher, and it is necessary to coat the oxide with excellent oxidation resistance. For this reason, coating of an oxide film represented by Al ₂ O ₃ is applied to commercially available tools. As a result of observing the damage condition of such a tool in detail, it was found that there are many cases in which the tool is disposed as a used chip although the amount of wear is very small. When the cutting edges of these chips were observed with a scanning electron microscope, it was found that fine chipping occurred at the ridgeline of the cutting edge and the cemented carbide base material was exposed at that part. In other words, if such a chip is used continuously even if the wear amount is small, welding will occur due to the exposed cemented carbide base material, or rapid wear or breakage will occur. Since troubles occur in the line, it is estimated that the tool was judged to have reached the end of its life even with such a small amount of wear. Therefore, if the chipping phenomenon of such a film can be suppressed, the tool life can be extended and the damage mechanism of the film was investigated.
As a result, the cutting temperature of the cutting edge ridge is not as high as that of the rake face, which creates an environment in which adhesive wear is likely to occur with temperature, and the frictional stress generated on the rake face is the maximum at the cutting edge ridge. Therefore, it is concluded that after the chips first adhere to the ridge of the cutting edge, the frictional stress acts as a shearing stress that peels off the coating film, resulting in minute chipping of the coating film. It was Therefore, we thought that if we could find a film structure or film quality that does not easily adhere to the edge of the cutting edge, it would be possible to suppress the minute chipping found in the damaged parts of the used chips, that is, the film peeling. .

Therefore, the present inventors have found out the present invention by variously examining methods for suppressing adhesive wear. In other words, the occurrence of adhesion is associated with physical unevenness represented by surface roughness. From this viewpoint, JP-A-62-22830
5 and JP-A-5-57507, the surface roughness of the Al ₂ O ₃ film is improved by post-treatment to prevent peeling, strength deterioration and welding of the film. However, the Al ₂ O ₃ film is likely to grow as crystal grains having an aspect ratio of 5 or less, and is likely to drop off in a lump (block) shape by adhesion or welding. For this reason,
Even if the surface roughness is improved before cutting, the present inventors have found that when Al ₂ O ₃ falls off in a lump form during cutting, large unevenness is formed and adhesion occurs in the dropout portion, and film peeling proceeds rapidly. I found it. On the other hand, it has been found that when a coating film having crystal grains with an aspect ratio of greater than 5 is exposed on the surface, the film is unlikely to fall off and the peeling resistance is very excellent. Therefore, the present inventors locally or entirely remove the coating film having crystal grains with an aspect ratio of 5 or less such as Al ₂ O ₃ from the cutting edge ridge portion where the frictional stress is the largest, and the aspect ratio is removed in the removed portion. Attempts were made to expose a film with grains larger than 5. Then, it was confirmed that this structure reduces the loss of the film, significantly improves the peeling resistance of the coating film, prevents chipping, and greatly extends the tool life.

Since nitrides and carbonitrides have excellent seizure resistance with metals, when these films appear on the surface of the coating removal portion, the effect of improving peeling resistance is high. Among them, TiC having a C: N molar ratio in the range of 5: 5 to 7: 3.
The N film has not only seizure resistance, but also the wear resistance of the film itself. Therefore, the one that exposes this film on the surface of the removed part shows extremely excellent peeling resistance and significantly extends the tool life. it can. A TiCN film having such a composition ratio can be formed by a normal HT (HIGH TEMPERATURE) -CVD method, but a CVD method using an organic CN compound as a reaction gas can more stably form a film having this composition ratio.

The molar ratio of C: N is ESCA (ELECTR
ON SPECTROSCOPY FOR CHEMICAL ANALYSIS) and EPMA
(ELECTRON PROBE MICRO ANALYZER) analysis or X-ray analysis to determine the lattice constant of the TiCN film. According to the results obtained by the inventors by X-ray analysis, Ti having a C: N molar ratio in the range of 5: 5 to 7: 3 is used.
The CN film had a lattice constant in the range of 4.275 to 4.295 angstroms, and at this time, particularly excellent seizure resistance and abrasion resistance were exhibited. Although this result includes a deviation when considering TiCN having a stoichiometric composition, such a deviation may occur because the TiCN film may have a non-stoichiometric composition such as Ti (CN) _0.9. It seemed to have occurred.

In addition, the reason why the residual stress in the film exposed on the surface of the removed portion is preferably in the range of -5 to 10 kgf / mm ² is because the peeling resistance of the film is further improved. This has been confirmed by experiments. If the residual stress is less than -5 kgf / mm ² , the film may be damaged by compression, and if it is greater than 10 kgf / mm ² , the effect of improving peeling resistance is small. .

Further, when the average value of the surface roughness Ra of the film exposed on the surface of the removed portion is 0.05 μm or less, the peeling resistance of the film was more excellent, but Ra was more than 0.05 μm. The effect of improving peel resistance was small. Furthermore, the film exposed on the surface of the removed portion has a (422) plane or a (31) plane.
In the case of the TiCN film having the maximum diffraction intensity on the 1) plane, the effect of improving the peel resistance was particularly remarkable.

Further, when the aspect ratio of the film exposed on the surface of the removed portion was 10 or more, the effect of improving the peeling resistance was large.

Next, on the flank, the film having crystal grains with an aspect ratio of 5 or less becomes a lump when falling off, rubbing the flank and lowering the wear resistance, so from the viewpoint of wear resistance. It is preferable to make the coating removal width on the flank side larger than that on the rake side. On the other hand, from the viewpoint of fracture resistance, on the contrary, the removal width on the rake face side may be made larger than that on the flank face side, or the removal width on the nose R portion may be made larger than the removal width on the cutting edge straight line portion. Good. From the viewpoint of sharpness and boundary wear resistance,
The removal surface width at the nose R portion is preferably smaller than the removal width at the cutting edge straight line portion, and the removal width varies depending on what is important in terms of performance.

The thinning of the cutting edge ridge in the present invention is carried out by coating the hard alloy by a known CVD method or PVD method, and then barrel polishing, shot blasting, shot peening, an elastic grindstone, and grinding. It may be achieved by a method such as a resin brush having particles, a roller finish, a vanish finish, a treatment with a chemical agent, an ultrasonic vibration method, or a laser processing.

Next, the residual stress in the film is determined by X-ray analysis using si.
It can be obtained by the n ² φ method. Further, the average value of the surface roughness Ra of the film is accurate because the contact type surface roughness meter does not allow the stylus to enter the exposed portion when the oxide film remains as shown in FIG. 4C. Uneven SEM because measurement is impossible
(ERA4000 manufactured by Elionix) was used to measure the surface roughness Ra using an electron beam. The measurement magnification was 5000 times, and the sample was arranged so that the cutting edge ridge was horizontal. The average value of the surface roughness Ra referred to here is the average value of the surface roughness Ra of 180 horizontal lines having a measurement visual field of 18 × 24 mm, and the number of measurement points per line was 240 points.

In the state shown in FIG. 4C, the remaining A
When the surface roughness including the l ₂ O ₃ film is measured, the surface roughness is very poor, and Rmax becomes larger than the film thickness of the removed film. In the present invention, the peeling resistance of the film is controlled by controlling the surface roughness of the film exposed in the removed portion to a certain specified value or less (preferably 0.05 μm or less) instead of the surface roughness including the residual film. Have been found to improve.

[0027]

Embodiments of the present invention will be described below in detail.

Example 1 Various hard alloys (a) to (f) shown in Table 1 and HT (HIGH TEMPERATURE) -CVD shown in Table 2 in the shape of the model number CNMG433
Table 4 consisting of combinations of various hard coating films prepared by the method
The coated hard alloy tools (tips) of Sample Nos. 1 to 13 shown in 1 were prepared. Then, first, the aspect ratio of the coating film shown in Table 2 was measured using TEM and the above-described calculation formula. Table 3 shows the results.

Next, the tip of sample No. 1 in Table 4 was subjected to a treatment of removing the coating film on the ridge line of the cutting edge using a vibrating barrel machine, and the treatment time was changed to obtain the cutting edge shown in Table 5. Comparative product 1 and invention products 1 to 6 having different removal ratios of TiN (aspect ratio 0.9) and Al ₂ O ₃ (aspect ratio 3.5) films having crystal grains with an aspect ratio of 5 or less at the ridge portion. Got the tool. After the Al ₂ O ₃ film is removed, the ridgeline of the cutting edge has a TiC ratio of about 15
It was confirmed that N was exposed by observation with a backscattered electron image of TEM and SEM. FIG. 2 is an example of a cross section of the cutting edge portion of the product of the present invention, wherein 5 is a base material and 4 is a coating film of a multilayer ceramic. Next, using the tools of the comparative product 1 and the products 1 to 6 of the present invention obtained here, the SCM415 work material shown in FIG. 5 (a round bar material having four grooves on the outer circumference and intermittent cutting)
Was cut under the following conditions, and the life of each tool was compared.

Cutting conditions Cutting speed: 250 m / min Feed: 0.3 mm / rev Depth of cut: 1.5 mm Cutting form: Wet Holder used: PCLNR2525-43 The life is determined by SEM reflection electron image observation,
The life time was defined as the time when the base material was exposed. As a result, Table 5
As shown in FIG. 5, the invention products 1 to 6 show excellent peeling resistance as compared with the comparative product 1 which was not subjected to any treatment, and particularly, 50% or more of the film having crystal grains with an aspect ratio of 5 or less was removed. The tools of Nos. 4 to 6, in which the film having crystal grains with an aspect ratio of 5 or less was 100% removed from the cutting edge ridge portion, showed 6 times as much peeling resistance as Comparative product 1.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

Example 2-Al ₂ O ₃ film having crystal grains with a minor axis diameter of more than 0.7 μm and an aspect ratio of 5 or less from the cutting edge ridges of the chips of Sample Nos. 1 and 6 in Table 4 and ZrO. ₂ films 100%
The removed invention products 6 and 7 were prepared using a diamond brush so that the film structure and film thickness at the cutting edge ridge line portion and the blade edge treatment amount were almost the same, and subjected to the same cutting test as in Example 1. As a result, as shown in Table 6, the peel resistance after treatment showed the same performance, but the peel resistance of the untreated product was
The comparative product 1 is worse than the comparative product 2, and the effect of improving the peeling resistance by the treatment is that the invention product 6 from which Al ₂ O ₃ is removed is Z
It can be seen that the effect of removing AlO ₂ is larger than that of the invention product 7 in which rO ₂ was removed, and the effect of removing Al ₂ O ₃ was larger than that in removing ZrO ₂ .

[0037]

[Table 6]

Example 3 Inventive product 8 in which the Al ₂ O ₃ film having an aspect ratio of 1.8 was removed from the ridge of the cutting edge of the sample No. 5 in Table 4 and Al ₂ O ₃ , TiCN and the aspect ratio 3 Zr of 1
Inventive product 9 from which the O ₂ film was removed was prepared by shot blasting with glass beads, and was subjected to the same cutting test as in Example 1 together with comparative product 3, which was an untreated chip of sample No. 5. As a result, as shown in Table 7, the peeling resistance after the treatment showed that the invention product 9 in which the coating film having all the crystal grains with the aspect ratio of 5 or less at the cutting edge ridge was removed was Al ₂ O.
Only the ₃ was removed, and ZrO ₂ showed better performance than the invention product 8 in which the cutting edge ridge line portion remained.

Further, from the comparison between the invention products 6 and 9, the invention product 6 in which only the film mainly composed of nitride or carbonitride is present on the cutting edge ridge portion where the film of the upper layer disappears after the removal treatment The peeling resistance was superior to that of Inventive product 9 in which only the film mainly containing carbide was present on the ridgeline of the cutting edge.

[0040]

[Table 7]

-Example 4-Al ₂ O ₃ and the Al ₂ O ₃ located in the uppermost layer of the coatings having crystal grains with an aspect ratio of 5 or less from the cutting edge ridges of the chips of Nos. 2 to 4 and Nos. 7 and 8 in Table 4 In order to remove the TiN film, an elastic grindstone was used by pressing it from above the chip rake face, and the invention products 10 to 14 were prepared by exposing the coating film having crystal grains with an aspect ratio of greater than 5 at the cutting edge ridge. Obtained. Using those chips, S
The mold material made of KD62 was cut under the following conditions.

Cutting Conditions Cutting Speed: 150 m / min Feeding: 0.2 mm / rev Cutting Depth: 2 mm The cutting form and holder used are the same as in Example 1.

The life criterion was the cutting time until the base material was exposed. Table 8 shows the results. Inventive products 10 and 11 both have a structure in which the Al ₂ O ₃ film does not exist at the cutting edge ridge line, and the film thickness at the cutting edge ridge line is almost the same, No. 11 showed excellent peeling resistance. This result is particularly excellent because invention product 10 has a carbide, nitride, or carbonitride film at the cutting edge ridge, whereas invention product 11 has only carbonitride. It is considered that the peeling resistance was exhibited. In addition, it can be seen from Table 8 that the products of the present invention also show excellent peeling resistance with respect to the untreated products in the ISO K20 cemented carbide and the cermet base material.

[0044]

[Table 8]

Example 5-In order to remove the film having crystal grains with an aspect ratio of 5 or less from the cutting edge ridges of the chips of Sample Nos. 9 to 11 in Table 4, all the cutting edges were cut using a centrifugal barrel. Invention products 15 to 17 were prepared by removing the coating film having crystal grains with an aspect ratio of 5 or less. Using those chips, the ductile cast iron FCD30 was cut under the following conditions.

Cutting Conditions Cutting Speed: 250 m / min Feeding: 0.3 mm / rev Cutting Depth: 2 mm Cutting Form: Dry Type The holder life standard is the same as in the other examples.

The results are shown in Table 9. From the table, it can be seen that also with respect to various ceramic base materials, the product of the present invention exhibits excellent peeling resistance as compared with the untreated product.

[0048]

[Table 9]

Example 6 A chip of Sample No. 12 different from Sample 1 only in that a TiCN film was formed by the CVD method using the organic CN compound as a reaction gas with the same base material and the same film structure as those of Sample 1 in Table 4. It was created. The aspect ratio of this TiCN film is T
It was about 33 when measured by EM. Also, when the C: N molar ratio of the TiCN films of Samples 1 and 12 was measured by ESCA, the C: N ratio of Sample 1 was 8: 2, and Sample 12 was 6: 4. Inventive products 18 to 20 having different removal rates of Al ₂ O ₃ having an aspect ratio of 3.5 and TiN having an aspect ratio of 0.9 in the cutting edge ridge portion were prepared in the same manner as in Example 1, and Example 1 was prepared. The same cutting test was performed. In addition, after the Al ₂ O ₃ and TiN films are removed, the cutting edge ridges are locally or entirely covered with TiC.
The exposure of N was confirmed by observation with a backscattered electron image of the SEM.

The results are shown in Table 10. Comparison of Comparative Product 1, Comparative Product 4 in which chips of Sample 12 were used without treatment, Invention Products 1 to 6 and 18 to 20 revealed that some or all of the parts on the cutting edge ridge due to removal of the upper layer film. And Ti with a C: N molar ratio in the range of 5: 5 to 7: 3.
It was found that the chip in which the CN film was exposed had particularly excellent peeling resistance.

[0051]

[Table 10]

-Example 7-Sample No. 1 (Comparative Product 1) prepared in Example 1 and Inventive Product 1
3 to 6 were used to cut a round bar material having four grooves of SCM435 shown in FIG. 3 under the following conditions.

[0053]

The life criterion was the occurrence of chipping, and the average life of the four corners of the chip was the cutting possible time. Table 11 shows the results. From this, it is understood that the product of the present invention has excellent fracture resistance, unlike the comparative product which is not treated with a coating.

[0055]

[Table 11]

-Example 8- From the cutting edge ridge of the tip of sample No. 13 in Table 4,
An outer layer of TiN with an aspect ratio of 1.2 and an aspect ratio of 3.
Invention product 21 from which the Al ₂ O ₃ film of No. 4 was removed was prepared using a vibrating barrel machine and subjected to the same cutting test as in Example 1. As a result, as shown in Table 12, Inventive product 21 leaving the Al ₂ O ₃ film of the inner layer of the aspect ratio 4.1, the outer layer Al ₂
Even though only O ₃ was removed, the exfoliation resistance was superior to that of Comparative product 5.

[0057]

[Table 12]

-Example 9-A chip (invention products 22 to 25) in which 100% of the film having crystal grains with an aspect ratio of 5 or less was removed from the cutting edge ridge of the chip of sample No. 3 in Table 4 prepared in Example 1 Inventive product 22 was removed by blasting, invention 23 was removed by centrifugal barreling, invention 24 was vibrating barreling, and invention 25 was rotating barreling. It is a thing.

For each of the chips of the invention products 22 to 25, the residual stress in the exposed non-oxide film at the ridgeline of the cutting edge was measured as X.
Si on the TiC (311) plane using the line (Cr-Kα)
When measured by the n ² φ method, the results shown in Table 13 were obtained.

Further, when the same cutting test as in Example 1 was carried out on these samples, as shown in Table 13, the invention product 23 in which the residual stress in the film is in the range of -5 to 10 kgf / mm ² , No. 24 showed superior performance in terms of durability to invention products 22 and 25 out of the range.

[0061]

[Table 13]

Example 10 The chips of Sample No. 1 in Table 4 used in Example 1 were subjected to steel ball blasting with an average particle size of about 200 μm at an aspect ratio of 0. 9 TiN
And invention 2 from which Al ₂ O ₃ having an aspect ratio of 3.5 was removed
Inventive products 27, 28 and 29 in which TiN and Al ₂ O ₃ were removed by polishing the same sample as No. 6 with a burnishing compound while changing the treatment time using a rotating barrel. Then, the average value of the surface roughness Ra of the TiCN film exposed at the cutting edge ridges of these chips is calculated by Elionix Co., Ltd.
It was measured at a magnification of 5000 times with an ERA4000 manufactured by K.K.

The results are shown in Table 14.

Table 14 also shows the results obtained by subjecting these samples to the same cutting test as in Example 1 and examining the peel resistance (cuttable time) of the film. As can be seen, the average value of the surface roughness Ra of the film exposed by the removal treatment is 0.05 μm.
Inventive products 27, 28, and 29 having an average particle size of m or less exhibit superior performance in terms of durability than the inventive product 26 having an average roughness of 0.05 μm or more.

[0065]

[Table 14]

Example 11 A TiCN film having the film quality G shown in Table 2 was prepared by changing the coating temperature, gas composition, gas composition ratio and manufacturing process, and the samples shown in Table 15 were obtained. The maximum diffraction intensity surface in the table is X
By a line (Cu-Kα), it means the surface showing the maximum peak intensity in the range of 10 ° to 140 °.

[0067]

[Table 15]

In each of the samples, except for Comparative product 7, a part of ZrO ₂ having an aspect ratio of crystal grains of 3.2 and TiN having an aspect ratio of 0.9 was partially removed from the edge of the cutting edge using a centrifugal barrel. .

As a result of a cutting test using these samples under the same cutting conditions as in Example 4, the cuttable time of each sample was as shown in Table 15. This result shows that TiCN
It is clearly shown that the invention products 32 and 33 whose films have the maximum diffraction intensity at (311) or (422) exhibit particularly excellent cutting performance. Further, the invention product 32 having a large aspect ratio exhibits excellent cutting performance as compared with the invention product 35 in which the aspect ratio of the film exposed on the surface of the removed portion is smaller than 10.

The effects of the present invention have been described above with reference to some examples, but the present invention is not limited to these examples.

For example, not only milling tools, milling tools such as drills and end mills, but also wear resistant tools other than cutting applications such as punches, dies, and slitters have great effects. That is, the punch, slitter has an edge corresponding to the cutting edge ridge portion of the cutting tool, while the die has no such edge, but since the work material has a wide surface to rub, According to the present invention for removing a film having a crystal grain with an aspect ratio of 5 or less, which easily causes a falling phenomenon, an excellent effect can be expected also in this kind of tool.

[0072]

As described above, in the coated hard alloy tool of the present invention, a coating having crystal grains with an aspect ratio of 5 or less contained in a multilayer ceramic film for improving wear resistance is used as a work material. By removing it at the part where friction occurs, a film having crystal grains with an aspect ratio of greater than 5 appears on the exposed part, and peeling of the film that starts from falling off of the film and chipping of the cutting edge are reduced. The life of the product is greatly extended, and the roughness of the machined surface is improved.

[Brief description of drawings]

FIG. 1A is a perspective view showing a part of a cutting tool (tip). FIG. 1B is an enlarged view of an XY cross section of FIG. 1A. FIG. The figure which expands and shows the other example of Y cross section.

FIG. 2 is an enlarged view showing an example of a cross section of a chip of an example.

[Fig. 3] Explanatory drawing of the aspect ratio of the film

[Fig. 4] Explanatory diagram of the film removal rate

FIG. 5 is a diagram showing a cross-sectional shape of a work material used in a cutting test.

[Explanation of symbols]

 1 rake face 2 flank face 3 nose R part 4 multilayer ceramic coating 5 base metal A cutting edge line

Front page continuation (72) Inventor Kazuo Yamagata 1-1-1 Kunyokita, Itami-shi Sumitomo Electric Industries Itami Works

Claims (9)

[Claims] 1. A coated hard alloy having a coating of a multilayer ceramic film on the surface of a base material made of a hard alloy, and the coating film containing at least one coating having crystal grains with an aspect ratio of 5 or less. In the tool, among the ceramic films constituting the coating, some layers counted from the upper layer side are removed in at least a part of the region where friction with the work material occurs, and the aspect ratio of the removed layer is 5 A coated hard alloy tool, characterized in that at least one coating film having the following crystal grains is included, and a film having crystal grains with an aspect ratio of 5 or more is exposed on the surface of the removed portion. 2. The aspect ratio included in the removal layer is 5.
The coated hard alloy tool according to claim 1, wherein the minor axis diameter of the crystal grains of at least one of the coating layers having the following crystal grains is 0.7 μm or more. 3. An aspect ratio of 5 included in the removal layer.
A coating having the following crystal grains is Al ₂ O ₃ or Al ₂ O
The coated hard alloy tool according to claim 1, which is a coating containing ₃ as a main component. 4. The coated hard alloy tool according to claim 1, wherein the film exposed on the surface of the removed portion is a film mainly composed of nitride or carbonitride. 5. The film exposed on the surface of the removed portion is C:
The coated hard alloy tool according to claim 1, which is a TiCN film in which the molar ratio of N is in the range of 5: 5 to 7: 3. 6. The residual stress in the film exposed on the surface of the removed portion is −5 to 10 kgf / mm ² .
The coated hard alloy tool according to 3, 4, or 5. 7. The surface roughness Ra of the film exposed on the surface of the removed portion has an average value of 0.05 μm or less.
The coated hard alloy tool according to 3, 4, 5 or 6. 8. The film exposed on the surface of the removed portion is (42)
T having the maximum diffraction intensity on the (2) plane or the (311) plane
The coated hard alloy tool according to any one of claims 1 to 7, which is an iCN film. 9. The coated hard alloy tool according to claim 1, wherein the aspect ratio of the film exposed on the surface of the removed portion is 10 or more.