JPH09295205A - Throw away insert made of coated cemented carbide and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesiveness of a base body and a hard film, and to prolong the lifetime of a tool by including a specified quantity of Cr in the base body cemented carbide. SOLUTION: Base body cemented carbide of a throw away insert made of coated cemented carbide, which is coated with a hard film, includes Cr at 0.01-5.0% of weight ratio. For example, WC powder, Co powder, TiC powder, TaC powder is used for the raw material, and Cr variable at 0.02-4.50wt.% is blended by using Cr powder, and mixed by a ball mill for 72hr so as to obtain the composition corresponding to JIS P30. Continuously, the mixture is formed into a predetermined shape of compressed powder material, and sintered at a predetermined temperature within a range at 1350-1450C for about 1hr, and the alloy, which includes Cr variable at the same variable of the blending added variable of Cr, is obtained, and thereafter, all circumference is polished so as to form a cemented carbide base body. After performing the predetermined washing, arc ion plating method is used so as to coat the cemented carbide base body with a hard film of TiN, TiCN, TiAlN at 2.0μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw away insert made of coated cemented carbide, which has extremely excellent adhesion between a hard coated layer and a cemented carbide substrate.

[0002]

2. Description of the Related Art Generally, in cutting with a face mill or a lathe, a ceramic coating using a CVD (chemical vapor deposition) method or a PVD (physical vapor deposition) method is applied to a throw-away insert made of cemented carbide. However, in order to respond to high speed and high efficiency in cutting in recent years, we are trying to deal with the above by applying ceramic coating to the throwaway insert made of cemented carbide, but there is an important Adhesion between the hard alloy substrate and the ceramic coating film. With respect to these high speeds and high efficiency, studies have been conducted to improve the adhesiveness of ceramic coatings, so-called hard coatings, such as those found in JP-A-8-39317.

However, in recent years, there is a strong tendency to directly process a high hardness material such as steel after heat treatment (after quenching), and in cutting such a high hardness material, cutting stress is extremely high. The current situation is that the adhesiveness that is sufficiently satisfied and the tool life that is strong enough are not obtained.

[0004]

In the case where the work piece becomes hard as described above or when a high feed rate is imparted for high efficiency, the cutting stress is high and the hard coating easily peels off. There is a tendency. In such a case, the peeling of the coating film causes abnormal wear in the peeled portion, leading to the end of the tool life. An object of the present invention is to significantly improve the adhesion between the hard coating and the cemented carbide substrate in order to obtain a longer tool life even under such cutting conditions.

[0005]

In recent years, due to environmental problems and the like, fluorocarbons cannot be used for cleaning before coating, and cleaning with acid or an alkaline aqueous solution or water is becoming mainstream. The inventors of the present invention have conducted extensive studies on this water cleaning in order to significantly improve the adhesion between the hard coating and the cemented carbide substrate, and as a result, have obtained the following findings. Usually PV such as arc ion plating method
In the D (physical vapor deposition) method, an alkaline aqueous solution or water is used to clean the surface of the throw-away insert processed as necessary in the coating pretreatment step.
The metal Co used in the cemented carbide reacts with the amine in the solvent by the washing with the alkaline solvent, forms a Co complex, and is eluted from the cemented carbide. Therefore,
While the grinding fluid, oil, dust, etc. adhering during the processing of the throw-away insert are removed during cleaning, Co, which is the binder phase surrounding WC in the cemented carbide, is eluted at the same time. The part where is eluted becomes a defect (pore) and remains.

When a hard film is coated on the surface having such a defect, between the WC hard layer in the cemented carbide and the film,
Although good adhesion can be obtained, the surface of the substrate and immediately below the hard coating, that is, the interface between the substrate and the coating, is in a microscopically extremely porous state. Therefore, even if a cutting process is performed using such a throw-away insert, the coating itself does not peel off, but the coating containing the substrate component from this porous portion with the aforementioned WC still attached to the coating. Peeling will occur. For example, 90 wt% WC-10 wt% Co cemented carbide is washed with an alkaline aqueous solution and water to mechanically peel the film,
When component analysis was performed on the peeled back side,
Although 25 wt% W was detected, on the other hand, when the fluorocarbon-cleaned product was similarly investigated, 2 wt% W was detected. As described above, it is clear that the elution of Co in the substrate due to the washing with the alkaline aqueous solution and water remarkably deteriorates the adhesion between the film and the substrate, and it is remarkable that the elution of Co in the substrate is significantly suppressed. The adhesion of the film can be improved.

[0007]

As a result of further intensive research from such a viewpoint, the present inventors have obtained the finding that the inclusion of Cr in the cemented carbide as the base material is remarkable and the elution of Co in the base material is suppressed. It was Therefore, it has been found that in the coated cemented carbide throw-away insert, adding Cr to the cemented carbide substrate significantly improves the adhesion between the substrate and the hard coating, resulting in a significantly longer tool life. .

[0008] In addition, in the process of coating using the above-mentioned cemented carbide substrate, it is usual to have a process of cleaning → heating → bombarding → coating → cooling. Grinding liquid, oil, other dust, and defects (pores) that cannot be removed by the cleaning process
Undergoes further surface cleaning due to the bombardment of the coating process. This bombardment also varies depending on the coating method, but the coating method using the bombarding method using an inert gas such as Ar ions is not sufficient, and in order to bring about a harder surface cleaning action, it is necessary to use an arc ion plate. The target material bombarded by the Ting method had a greater surface cleaning force than the other methods, and the effect was remarkably observed. However, even if the above-mentioned arc ion plating method is adopted, the conventional cemented carbide substrate (mainly JIS / P
However, even if the residual grinding fluid, oil, and other dust on the surface could be removed, it was insufficient to remove the surface defects. According to the present invention, by adding Cr to this conventional cemented carbide substrate, the surface defects due to the cleaning process are significantly reduced, and the surface defects are sufficiently removed by the bombarding treatment by the arc ion plating method. It was found that it is possible.

Next, the reason why the amount of Cr added is limited will be described. When Cr is added in an amount of less than 0.01 wt%, it forms a solid solution in the base bonding phase, but a significant effect on Co elution cannot be obtained. Further, if added in excess of 5.0 wt%, depending on the cooling rate in the sintering furnace after sintering, etc., it precipitates as a carbide of the third phase, leading to a decrease in toughness of the cemented carbide itself. Limited to the claims. Therefore, the amount of added Cr does not cause deterioration of the toughness of the cemented carbide itself because Cr does not precipitate as carbides and forms a solid solution in the binder phase. Hereinafter, the present invention will be described in detail based on embodiments.

[0010]

【Example】

Example 1 The present invention uses WC powder, Co powder, and Ti as raw material powders.
C powder and TaC powder were used, and a Cr amount (wt%) as shown in Table 1 was added to a composition equivalent to JIS P30, and the mixture was mixed for 72 hours in a ball mill.
By molding into a green compact having the shape of a 2TN type throw-away insert and sintering at a predetermined temperature within a range of 1350 to 1450 ° C. for about 1 hr, the amount of Cr added in the sintered body is the same as that of the sintered body. The SEE42TN type throw-away insert was prepared by polishing the entire circumference after obtaining an alloy having a Cr content.

[0011]

[Table 1]

Further, for comparison at this time, 7 to 9 to which the amount of Cr was added and 10 (without addition of Cr) as a conventional material were prepared. Perform predetermined washing using these samples, and
By HCD (hollow cathode discharge) method in D (physical vapor deposition) method, TiN coating is applied in a range of 1.5 to 2.0 μm, and a face milling machine is used to perform milling cutting at a cutting speed of 100 m.
/ Min, feed amount per blade 0.1 mm / blade, cutting depth 2 mm, work material SKD61 (HRC45) material,
A dry milling cutting test was performed using a width of 125 mm and a length of 250 mm, and the machinable distances before the peeling of the hard coating and the peeling from the cemented carbide substrate were compared, and the results are also shown in Table 1. From the results shown in Table 1, in comparison with the conventional product, the cemented carbide throw-away insert which is the product of the present invention significantly improves the adhesion to the hard coating by the addition of Cr in the range defined in the claims. The cutting performance could be improved. This is because, in the comparative product or the conventional product, Co elution cannot be suppressed in the cleaning step before coating, so that the adhesion is deteriorated. Also,
Excessive addition deteriorates the toughness of the substrate itself, resulting in chipping during cutting, and a satisfactory tool life could not be obtained.

Example 2 Next, after performing a predetermined cleaning using the cemented carbide substrate prepared in Example 1, a hollow cathode discharge method and an arc ion plating method among PVD (physical vapor deposition) methods are used. , DC magnetron sputtering method was used to coat the hard coating of TiN, TiCN, and TiAlN on the cemented carbide substrate by 2.0 μm in each method, and the milling machine was used to perform the milling cutting at a cutting speed of 120 m / min. Feed rate per blade 0.1 mm / blade, depth of cut 2 mm, work material SKD61 (HRC50) material, 125 mm width, 2
A dry cutting test was performed using a length of 50 mm, and the machinable distances until the hard coating peeled and the cemented carbide substrate peeled were compared, and the results are shown in Tables 2, 3, and 4.

[0014]

[Table 2]

In Table 2, when TiN is coated, Table 3
Shows the results when TiCN was coated, and Table 4 shows the results when TiAlN was coated. For each coating method in the table,
Hollow cathode discharge method = HCD, arc ion plating method = Arc, DC magnetron sputtering method = DC
-Indicated as MS.

[0016]

[Table 3]

[0017]

[Table 4]

Also, in the coating method, in the coating by the hollow cathode discharge method or the direct current magnetron sputtering method, the bombardment of these methods does not show the effect of sufficiently removing the surface defects of the substrate, so that the subsequent coating is performed. However, even if the adhesion between the hard coating and the WC in the substrate is good, the pores formed at the interface cause peeling or chipping during cutting, and a sufficient tool life cannot be obtained. Further, in the method capable of high energy bombardment with the target material such as the arc ion plating method, even if a defect is formed on the substrate surface after cleaning, it can be removed, and therefore,
The adhesion between the hard coating and the surface of the substrate is improved, and a sufficient tool life can be obtained even in cutting.

[0019]

As described above, using the cemented carbide throwaway insert of the present invention, the one coated with a hard coating by the arc ion plating method, that is, the coated cemented carbide throwaway insert is used. If so, a remarkably excellent tool life can be obtained.

Claims (2)

[Claims] 1. A coated cemented carbide throw-away insert coated with a hard coating, characterized in that the base cemented carbide contains 0.01 to 5.0% by weight of Cr. Alloy throw-away insert. 2. A coated cemented carbide throwaway insert coated with a hard film, wherein the base cemented carbide contains 0.01 to 5.0% by weight of Cr. In the away insert, a method for producing a throw away insert made of a coated cemented carbide, wherein a hard coating layer is formed by an arc ion plating method.