JPH08141850A - Surface layer reinforcing method for cutting tool material - Google Patents

Abstract

PURPOSE: To provide a cutting tool material excellent in surface hardness without the interface existing by submerging a surface-roughened edge part in an organic metallic solution, and then applying heat treatment to the cutting tool material for diffusion reaction. CONSTITUTION: A hard metal or cermet edge part is degreased with an alkali solution (step S2). The edge part after degreasing treatment is surface-roughened with an acid solution (step S3). The edge part is then submerged in a metallic salt solution formed of one kind or more selected from among Cr, W in a VIA group, Mn in a VIIA group and Fe, Ni, Co in a VIII group in a periodic table or the compound thereof and salt, and/or an organic metallic solution containing organic substance combined with metal formed of one kind or more selected from among Al in a III group, Ti, Zr in a IV group, V in a VA group and Cr in a VIA group or the compound thereof (step S4), and then heat treatment is applied to cutting tool material (step S6) for diffusion reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for strengthening a surface layer of a cutting tool material in which a ceramic layer is provided on the surface and a metal diffusion layer is provided inside.

[0002]

Cutting tools such as indexable inserts, drills and reamers are widely used for machining steel, cast iron or non-ferrous metals and the like. As a material for this type of cutting tool, cemented carbide, cermet, diamond, CBN and the like are used, and among them, the proportions of cemented carbide and cermet are large.

By the way, in the case of cemented carbide and cermet, wear is particularly rapid when cutting iron or steel, and tipping of the cutting edge occurs depending on the work material. The coating process is performed by the chemical vapor deposition method).

[0004]

However, the above-mentioned P
The coating process by VD or CVD raises the cost and, for example, when the film thickness is about 30 μm as in the case of coating a cutting tool, peeling between the coating interface and the base material interface may occur.

Therefore, as disclosed in JP-B-4-24424, a composite of a coating layer formed by an arc evaporation type ion plating method and a coating layer formed by a melt vapor deposition type ion plating method on the surface of a base material. Techniques for providing layers are known. However, in the above-mentioned conventional technique, the use and size of the material to be treated are limited, the cost increase is not eliminated, and moreover, the high technology is required, which makes the work complicated. A problem has been pointed out.

The present invention solves this kind of problem, and provides a method for strengthening a surface layer of a cutting tool material which is excellent in surface hardness, does not have an interface, and is inexpensive and simple. With the goal.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is to clean an edge of a cemented carbide or cermet formed on a cutting tool material with an alkali and to roughen it with an acid. And the treated blade portion, Cr, W and Mn and VIII of VIIA group of the periodic table.
Solution of a metal salt consisting of a salt of one or more selected from group Fe, Ni and Co, and / or a compound thereof, and / or group III Al and group IV Ti, Zr and group VA groups V and VIA. A step of immersing in an organic metal solution in which a metal and an organic compound consisting of one or more selected from Cr or their compounds are combined, and a step of subjecting the cutting tool material subjected to the immersion treatment to a heat treatment to cause a diffusion reaction, It is characterized by having.

[0008]

In the method for strengthening the surface layer of a cutting tool material according to the present invention, first, after the blade portion is subjected to cleaning and roughening treatment,
Metal salt and / or organic metal is placed on this blade,
Heat treatment is applied after drying. Therefore, metal salts and /
Alternatively, the organic metal reacts with the blade portion and diffuses inside the blade portion, and a metal diffusion layer is formed by alloying or fine precipitation, and the surface layer of the blade portion is nitrided, carbonized, carbonitrided or oxidized. Made into ceramics. As a result, the wear resistance, slidability, and heat resistance of the surface layer are improved, and the internal strength can be increased to prevent peeling.

[0009]

The method for strengthening the surface layer of a cutting tool material according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a flow chart showing a processing procedure of the method of the present invention, which will be schematically described. First, a cutting tool material on which a blade portion of cemented carbide or cermet is formed is prepared (step S1). Cutting oil or the like is attached to the surface of the blade portion during processing of cemented carbide or cermet, and the cutting oil or the like causes problems such as uneven adhesion of the grain growth promoting material or the ceramic film forming material. There is a degreasing treatment with an alkaline solution (step S2).
After the degreasing treatment, the surface of the blade is roughened by an acid solution (etching treatment), and a roughening treatment is performed (step S3). This is to improve the adhesion of the grain growth promoting material and the ceramic film forming material to the surface of the blade.

Then, in step S3, the blade portion is dipped in the grain growth promoting material and the hard ceramics film forming material (immersion treatment) to form a film on the surface of the blade portion. At that time, in order to further improve the adhesion of the grain growth promoting material and the ceramic film forming material to the surface of the blade portion, it is possible to add a thickener or a small amount of binder.

Therefore, the process proceeds to step S5, the drying process is performed, the solvent is removed, and then the process proceeds to the heat treatment process (step S6). In this heat treatment step, the metal salt and / or the organic metal is diffused into the base material (blade portion) by thermal diffusion or reaction diffusion to form a metal diffusion layer. On the other hand, in the surface layer of the blade portion, atmospheric gas or Nitriding, carbonization, carbonitriding by decomposition products, and ceramicization by oxidation proceed. As a result, the surface layer strengthening treatment of the blade portion is completed, and the blade portion is subjected to a processing treatment as needed (step S7), the chip,
Products such as drills or reamers are obtained. <Example 1> A commercially available carbide tip (JI
S-P-10 equivalent) was selected. This cemented carbide chip is a square chip having an inscribed circle of 12.7 mm and a thickness of 4.76 mm, and after being sufficiently degreased with a 20% aqueous solution of NaOH, it was immersed in a 25% aqueous solution of hydrochloric acid and The surface was etched.

Cemented carbide chips are prepared from the metal salt solutions A to A shown in Table 1.
After being immersed in F and dried, it was selectively immersed in the organometallic solutions g to o shown in Table 2. The combinations of these impregnants are shown in Experimental Examples 2 to 24 in Table 3.

Therefore, the cemented carbide chips selectively impregnated with the organometallic solutions g to o are subjected to a drying treatment for 12 hours in a dryer at 80 ° C. and then a firing treatment (heat treatment). It was The firing conditions are 450 ° C. and 650 ° C.
After holding for 5 minutes and 30 minutes, at 1240 ° C for 10 minutes,
Hold at 1320 ° C for 15 minutes. The processing conditions so far were a vacuum atmosphere at a temperature rising rate of 10 ° C./min.

Then, at a temperature rising rate of 10 ° C./min, 13
The temperature is raised to 60 ° C and held for 30 minutes, and further 5 ° C / mi
The temperature was raised to 1380 ° C. at a heating rate of n and held for 90 minutes. The atmosphere is 3 to 5 Torr below 1380 ° C.
Under reduced pressure nitrogen, above and under 1 bar nitrogen pressure at higher temperatures. Also, after holding at 1380 ℃, 1000 ℃
To 60 ° C., held for 60 minutes, and then rapidly cooled to room temperature. During this rapid cooling, the pressure was 3.5 bar with nitrogen gas.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

As shown in Table 3, the hardness of these cemented carbide chips was measured. This hardness was a micro Vickers hardness with a load of 1 kgf. As a comparative example,
A product treated with the same composition and the same sintering temperature was manufactured (see Experimental Example 1).

As described above, according to Example 1, Experimental Example 2
In Nos. 24 to 24, the hardness changed in a gradual manner, and each hardness became a significantly higher value as compared with the comparative example (Experimental Example 1). <Example 2> A commercially available carbide tip (JI
S-K-10 equivalent product and JIS-P-10 equivalent product) were selected. Each carbide tip is a square tip with an inscribed circle of 12.7 mm and a thickness of 4.76 mm.
After being sufficiently degreased with a 20% aqueous solution of H, 25% of hydrochloric acid
It was immersed in an aqueous solution and its surface was subjected to etching treatment.

Next, the cemented carbide tip is made of nickel nitrate 25
% Solution and aluminum isopropoxide-titanium isopropoxide mixed solution (30:70), and a 25% solution of nickel nitrate, zirconium imide and chromium amide (solution concentration 70% each). Further, the cemented carbide chips were dried and fired under the same conditions as in Example 1.

Therefore, for each of the cemented carbide chips, the cemented carbide chip of Example 1, a commercially available P-10 equivalent product, a commercially available cermet, a commercially available PVD and a CVD treated product, the hard ceramic layer formed on the surface of these The thickness, the graded composition width by EPMA analysis, and the hardness H _{RA of the} cutting edge surface were detected, and the results are shown in Table 4. The commercially available cermet was subjected to the same treatment as the cemented carbide tip, and the results are shown. In this cermet, cobalt nitrate was used in place of nickel nitrate.

[0023]

[Table 4]

Further, FIGS. 2 to 4 show the results of a cutting life test as an actual performance test, and FIG. 5 shows
The results of the abrasion resistance test are shown. From these results, it was found that Examples 1 and 2 exhibited a far superior value to the commercially available P-10 equivalent product and still had higher performance than the commercially available PVD and CVD treated products.

Moreover, in Examples 1 and 2, the improvement of the physical properties was observed. This is presumed to be a value close to that of actual ceramics because the ceramic hard coating formed on the surface is tough. Further, if the generated layer is porous, the hardness value becomes small, but from the obtained value, it is estimated that the generated film is dense.

Moreover, in Examples 1 and 2, since the component diffusion layer, which greatly affects the adhesion and durability of the coating film, is provided, it actually has an inclined function and reliably prevents the occurrence of peeling. be able to. Also, in Examples 1 and 2, no special device is required, unlike the multi-layer coating, it is not necessary to clean the inside of the chamber every time the coating structure is changed, and an inexpensive and high-performance carbide tip for cutting is provided. And the effect that a cermet chip can be obtained was acquired. <Example 3> 56 wt% of WC powder having an average particle size of 2 μm
%, 30 wt% of TiC powder having an average particle size of 1.5 μm,
5 wt% of TiN powder having an average particle size of 1.2 μm, 3 wt% of TaC powder having an average particle size of 1.5 μm, and 6 wt% of metallic Co powder having an average particle size of 0.8 μm were mixed.
Wet mixed well. After this mixing, a molded body having a diameter of 12.5 mm and a length of 100 mm was molded by a wet pressure molding method.

This molded product was added with 0.1 as an alcohol and an anti-friction material of the solvent body used at the time of pressure molding.
% Ammonium stearate to remove 10%, 10 minutes, 15 minutes, 30 minutes respectively at 250 ° C., 350 ° C., 450 ° C. and 650 ° C. under a pressure of 3 to 5 Torr while flowing nitrogen in nitrogen gas. It was held for a minute, further heated to 1000 ° C., and held at that temperature for 30 minutes. As a result, a calcined body was obtained, and then the calcined body was subjected to the main calcination treatment. The firing conditions were such that the temperature rising rate was 10 ° C./min, the temperature was maintained at 650 ° C. for 45 minutes, then at 1250 ° C. and 1320 ° C. for 15 minutes and 30 minutes, respectively, and further at 1360 ° C. for 30 minutes and 1 minute.
Hold at 380 ° C for 60 minutes. The firing atmosphere is 1320
The temperature was a vacuum up to ° C, and the temperature was over 1320 ° C under a nitrogen gas pressure of 1 bar.

The fired body after firing was processed into a drill shape and a reamer shape, and was subjected to a blade treatment. As a result, a drill and a reamer as cutting tool materials were formed.

Next, the drill and reamer are thoroughly degreased with a 20% aqueous solution of NaOH together with a commercially available P type drill material, and then immersed in a 25% aqueous solution of hydrochloric acid and the surface thereof is subjected to etching treatment. It was The drill, reamer and drill material that have been subjected to the etching treatment are washed with water, then immersed in a 25% solution of nickel nitrate for 30 minutes, further immersed in a mixed solution of aluminum isopropoxide and titanium isopropoxide, and dried. After being applied, a firing process (heat treatment) was performed. The firing conditions are such that the temperature rising rate is 10 ° C./min, the temperature is maintained at 650 ° C. for 45 minutes, and then 1250 ° C. and 1320 ° C. for 15 minutes.
Hold for 30 minutes, then at 1360 ° C for 30 minutes, 138
Hold at 0 ° C. for 60 minutes. The firing atmosphere was a vacuum up to 1320 ° C., and was under a nitrogen gas pressure of 1 bar at a temperature exceeding 1320 ° C.

The thus treated drill, reamer and drill material have a surface hardness H _RA of 96.8 to 98.4.
Was a value far exceeding that of the P-type commercially available material. Further, a coating layer was formed on the surface of each treatment material, and the thickness thereof was about several μm to 12 μm.

Therefore, when each processed drill and drill material are cut in the cross-sectional direction and the physical properties thereof are measured, the result is that the hardness changes corresponding to the change in the distance from the surface, as shown in FIG. Was given. The element concentrations of Ni and Ti are shown in FIGS. 7 and 8. Since the reamer and the drill are treated in the same manner, the above physical properties were measured using only the drill. As a result, it was found that the treated drills and drill materials had a graded property from the surface to the inside.

Further, the cutting life of the processed drill and the drill material was measured, and the result is shown in FIG. As a result, it was found that the treated drills and drill materials had a much longer cutting life than the commercially available JIS-P-10 equivalent products. Further, an abrasion resistance test was conducted using the processed drill and drill material and a conventional P type CVD processed product. The result is shown in FIG. From this, it was found that the treated drills and drill materials have wear resistance performance exceeding that of conventional PVD and CVD treated products.

[0033]

As described above, according to the method for strengthening the surface layer of a cutting tool material according to the present invention, the following effects can be obtained.

The roughened blade portion reacts with the metal salt and / or organic metal to diffuse inside the blade portion, and a metal diffusion layer is formed by alloying or fine precipitation, and
The surface layer of the blade portion is made into ceramics by nitriding, carbonizing, carbonitriding, or oxidizing. As a result, the abrasion resistance, slidability, and heat resistance of the surface layer of the blade can be improved by inexpensive and simple work, and the internal strength of the blade can be increased to ensure peeling. Can be stopped.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining a manufacturing method according to the present invention.

FIG. 2 is an explanatory diagram of a life line in steel turning.

FIG. 3 is an explanatory diagram of a life line in turning cast iron.

FIG. 4 is an explanatory diagram of a life line of ductile cast iron.

FIG. 5 is a diagram for explaining wear resistance.

FIG. 6 is a diagram showing a relationship between a change in distance from the surface and a change in hardness.

FIG. 7 is a diagram showing a relationship between a distance change from the surface and a Ni element concentration change.

FIG. 8 is a diagram showing a relationship between a distance change from the surface and a Ti element concentration change.

FIG. 9 is a diagram for explaining a cutting life test.

FIG. 10 is a diagram for explaining wear resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiro Funaki 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd.

Claims (3)

[Claims] 1. A step of cleaning a blade portion of cemented carbide or cermet formed on a cutting tool material with an alkali and roughening the surface with an acid, and treating the blade portion with a VIA group of the periodic table. Of Cr, W and MIA of Group VIIA and Fe, Ni and Co of Group VIII or a metal salt solution consisting of a compound and a salt thereof, and / or Al and I of Group III.
A step of immersing in a metal-organic solution in which a metal and an organic compound consisting of one or more kinds selected from Ti, Zr of group V, V of group VA and Cr of group VA, or a compound thereof, and the immersion treatment A method for strengthening a surface layer of a cutting tool material, the method comprising: subjecting the cutting tool material to a heat treatment to cause a diffusion reaction. 2. The surface layer strengthening method according to claim 1,
The surface layer strengthening method for a cutting tool material, wherein the salt of the metal salt solution is a nitrate salt, an acetate salt or a chloride salt. 3. The surface layer strengthening method according to claim 1,
The said organic salt is ethoxide, propoxide, butoxide, imide, or amide, The surface layer strengthening method of the cutting tool material characterized by the above-mentioned.