JPH06228609A - Throwaway tip - Google Patents

Abstract

(57) [Summary] [Structure] An ultra-high hardness sintered body containing CBN as a main component and a cemented carbide containing WC as a main component are provided in a recess 23 formed in a base material 22 made of a cemented carbide. The cutting blade body 21 formed by stacking
The contact surfaces of the two are polished to a mirror surface of 0.5 S or less, and then the parts 21b made of cemented carbide are mounted so that they face the base material 22 side. The cutting blade 21 and the base material are heated to 1400 ° C., which is near the liquidus temperature of the cemented carbide, and held for 1 hour, and the base material 22 and the cutting blade 21 are made of cemented carbide.
1b is diffusion-bonded. [Effect] It is possible to join both without the interposition of a brazing layer, and the cutting blade body due to welding of chips, digging into the brazing layer due to this, or melting of the brazing layer at high temperature, etc. It is possible to prevent the peeling and the falling off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention laminates a superhard sintered body containing cubic boron nitride as a main component and a cemented carbide on a base material made of a cemented carbide containing tungsten carbide as a main component. The present invention relates to a throw-away tip in which cutting blade bodies formed by

[0002]

2. Description of the Related Art In the field of cutting of cast iron, heat-resistant alloys, tool steels, etc., cubic boron nitride (hereinafter
It is called CBN. ) Etc. as a main component, a super-hard hardness sintered body is attached to a cemented carbide containing tungsten carbide (hereinafter referred to as WC) etc. as a main component, and a cutting edge is attached to the portion of the super-hard hardness sintered body. The formed throw-away tip (hereinafter referred to as a tip) is often used. However, even if such a super-hard sintered body is directly joined to the base material made of a cemented carbide by brazing, such a super-hard sintered body generally does not have high wettability to a brazing agent, and therefore, it is not enough. There is a problem that it is difficult to obtain a high bonding strength.

On the other hand, even if an ultra-high hardness sintered body and a base material made of a cemented carbide are directly laminated to be integrally sintered and formed, the base material portion becomes the ultra-high hardness sintered body portion. Generally, since the wall thickness is inevitably large in comparison, the base metal part acts like a cushion on the high hardness sintered compact part during the high pressure pressurizing process during molding. This causes a large deformation, and accordingly, the portion of the ultra-high hardness sintered body is also deformed, which causes a problem that it cannot be formed to have a uniform thickness. Therefore, as a means for attaching such a super-hard sintered body to a base material made of a cemented carbide, first, a super-hard sintered body and a cemented carbide are laminated and sintered to form a layered cutting blade body. Along with the formation, a means is adopted in which a recess is formed in the cemented carbide serving as the base metal, and the cutting blade body is brazed in this recess so that the portion made of the cemented carbide faces the base metal. Has been.

FIG. 6 and FIG. 7 show an example of a cutting tool equipped with a chip constructed by such means and a cutting state by this cutting tool. In these figures, a chip 1 is formed on a base material 2 in the shape of a substantially quadrangular plate made of cemented carbide containing WC as a main component, and the rake face 3 facing the ridge line intersecting with the rake face 3 and the flank face 4. A recess 5 is formed so as to be recessed by one step, and a cutting blade body 6 formed by laminating a super-hard hardness sintered body containing CBN as a main component and a cemented carbide in the recess 5 has an ultra-high hardness. The portion 6a made of a sintered body is directed toward the rake face 3 and the portion 6 made of a cemented carbide is used.
The lower surface 6c on the b side is directed to the bottom surface 5a side of the recess 5 and is joined by brazing to be generally configured. Here, the rake face 7 and the flank face 8 on the side of the cutting blade 6 are formed so as to be respectively continuous with the rake face 3 and the flank face 4 of the base material 2, and the lower face 6c and the bottom face. The brazing layer 9 is interposed between the brazing layer 5a and 5a.

Further, a cutting edge 10 is formed at the ridge line intersection of the rake face 7 and the flank 8 of the cutting edge body 6, and therefore the cutting edge 10 is an ultra-high hardness burnt of the cutting edge body 6. It will be formed in the portion 6a made of a united body. As shown in FIG. 6, the chip 1 having such a structure is mounted on a chip mounting seat 12 formed at the tip of a cutting tool 11, and is constrained to the chip mounting seat 12 by a known clamp mechanism 13 such as a lever lock. In this state, the work W is cut by the cutting edge 10 protruding from the tip of the cutting tool 11.

Here, in the chip 1 having the above-mentioned structure, a cutting blade body 6 obtained by laminating and sintering a super-hard sintered body and a cemented carbide is joined to the recess 5 of the base material 2. Therefore, as compared with the case where the super-hard sintered body is directly laminated on the base material and sintered and formed as described above, in the cutting blade body 6, the portion 6a made of the super-hard sintered body is made of cemented carbide. The wall thickness of the portion 6b can be reduced. As a result, the cushioning effect of the portion 6b made of the cemented carbide on the portion 6a made of the ultra-hard sintered body is suppressed, so that the portion 6a made of the ultra-hard sintered body is prevented from being deformed and its wall thickness is made uniform. It becomes possible to Further, the cutting blade 6 is brazed so that the portion 6b made of the cemented carbide is directed toward the base material 2 side made of the cemented carbide, that is, both are brazed to each other at the cemented carbide portions. It is joined. Therefore, according to the tip 1 having the above-described configuration, it is possible to secure good wettability of the brazing agent to the objects to be joined, and to obtain a necessary and sufficient joining strength in a normal cutting state, and the cutting blade body 6 Base material 2
It is possible to hold it securely.

[0007]

By the way, in the applicable range of such a tip 1, for example, in cutting a heat-resistant alloy,
Prevention of welding is mentioned as an important factor that affects the life of the chip. The frequency of occurrence of this welding differs depending on the surface roughness of the rake face 3, 7 and the flanks 4, 8 of the chip 1, but it becomes high especially in the portion where the brazing layer 9 is exposed to the outer surface of the chip 1. Has been pointed out.

However, the brazing layer 9 intervenes in the above-described conventional chip 1 in the first place is the cutting edge 10.
This is because the cutting blade body 6 in which is formed is joined to the base material 2,
Therefore, in the chip 1, the flank 8 on the side of the cutting body 6 which is continuous with the cutting edge 10 and the base material 2 which is further continuous with the flank 8
The brazing layer 9 is inevitably exposed at the joint with the flank 4 on the side. Therefore, as shown in FIG. 8, the powdery chips C generated at the time of cutting are clogged in the gaps between the flanks 4 and 8 and the processed surface P, which easily causes welding on the brazing layer 9. It cannot be avoided. When the welding is left as it is, the brazing layer 9 is gradually dug into a groove G as shown in FIG. 9, whereby the cutting blade body 6 is peeled off, or the welded material grows. Then, there arises a problem that the processed surface P is roughened.

On the other hand, in the tip 1 in which the cutting blade 6 is joined to the base material 2 through the brazing layer 9 as described above, the tip 1 is exposed to a high temperature of about 700 ° C., for example, in the case of dry heavy cutting. If this happens, there is a risk that the brazing layer 9 will melt, and this also causes the problem that the cutting blade body 6 peels off and falls off. The problems such as the welding of the chips C and the melting of the brazing layer 9 are not limited to the cutting tool described above, but are common to other throw-away cutting tools such as a face milling cutter.
The present invention has been made under such a background, while maintaining the uniformity of the bonding strength between the base material and the cutting blade and the thickness of the ultra-high hardness sintered body forming the cutting blade, An object of the present invention is to provide a chip capable of avoiding peeling / falling off of a cutting blade body from a chip and deterioration of surface roughness of a work material processed surface.

[0010]

The inventor of the present invention has conducted various studies in order to achieve the above-mentioned object, and as a result, when the cemented carbides are joined to each other without brazing, By directly adhering the hard alloys to each other and raising the temperature to near the temperature at which the cemented carbides assume the liquid phase, the particles forming the cemented carbides are diffused at the boundary between the cemented carbides and bonded to each other. Therefore, we have come to the knowledge that it becomes possible to firmly bond both cemented carbides. The present invention was made to solve the above problems based on such findings, in the recess formed in the base material made of cemented carbide, cemented carbide and cemented carbide A cutting edge body formed by laminating the cemented carbide with its part made of cemented carbide facing the base metal side, and forming a cutting edge on the part of the ultra-high hardness sintered body of the cutting edge body. In this chip, the base material and the portion of the cutting blade made of cemented carbide are heated to a temperature close to the liquidus temperature of the cemented carbide and diffusion-bonded.

[0011]

In such a chip, first, an ultra-high hardness sintered body on which a cutting edge is formed is laminated with a cemented carbide to form a cutting edge body, and the cutting edge body is made of cemented carbide. Since it is joined to the recess formed in the base material and integrated with the base material, it is possible to make the wall thickness of this ultra-high hardness sintered body uniform, as in the conventional case.

Further, in the present invention, this cutting blade has a portion made of the cemented carbide facing the base metal side, and the cutting blade and the base metal are brought to near the liquidus temperature of the cemented carbide. By raising the temperature, the portions made of cemented carbide of the cutting body and the base material are diffusion-bonded to each other, that is, at the boundary between the cemented carbides, the particles constituting the cemented carbide diffuse to each other. Will be combined with each other. As a result, the structure of both cemented carbides progresses to such an extent that the above-mentioned boundaries almost disappear, the cutting blade and the base metal are integrated, and as a result, the base metal and the base metal made of cemented carbide are cut. It is possible to obtain a chip which is obtained by directly laminating an ultra-high hardness sintered body on which a blade is formed and integrally sintering and molding. Therefore, according to the present invention,
While keeping the thickness of the portion of the ultra-high hardness sintered body uniform, it is possible to hold the cutting blade by joining the cutting blade and the base material with high bonding strength without brazing, Therefore, the brazing layer is not exposed on the flank of the chip, and chips are not welded to such a brazing layer. Further, since the brazing layer itself does not exist, even if the chip is exposed to high temperature, the cutting blade body does not peel off due to melting of the brazing layer.

[0013]

EXAMPLES Examples of the present invention will be described below. In this example, first, 94 wt% of WC powder having an average particle diameter of 2 μm and Co powder 6 having an average particle diameter of 1.0 μm were placed in a container.
30 g of a uniform mixed powder consisting of 1 wt% and 50% of CBN powder having an average particle diameter of 3 μm is placed on the powder and spread.
50% w of TiC powder with an average particle size of 1.0 μm
6 g of a uniform mixed powder of t% was charged and filled.
Then, the container filled with these mixed powders is placed in an ultrahigh pressure and high temperature generator, and the pressure is 45 kb and the temperature is 130.
It was held for 20 minutes under the condition of 0 ° C. for sintering, and this was cooled to obtain a two-layered sintered body. Then, after subjecting this sintered body to post-treatment, it is appropriately divided and cut into a fan-shaped flat plate shape as shown in FIG. 1, which is made of an ultra-high hardness sintered body containing CBN as a main component. 21a and a portion 21b made of a cemented carbide containing WC as a main component each have a uniform thickness and are stacked along the thickness direction to form a cutting blade body 21.

Separately from the cutting blade 21, 94 wt% of WC powder having an average particle size of 1.0 μm and an average particle size of 1.0 μm
15 g of a uniform mixed powder consisting of 6 wt% of Co powder of m was molded and held in a vacuum for 30 minutes under the condition of a temperature of 1460 ° C. to sinter, and as shown in FIG. A rectangular flat plate-shaped base material 22 was obtained. Next, at one corner of the upper surface 22a of the base material 22, the cutting blade body 21 is recessed one step from the upper surface 22a and in plan view from the upper surface 22a side.
The fan-shaped recess 23 having a congruent plan shape was formed. However, the depth from the upper surface 22a to the bottom surface 23a of the recess 23 is set to be substantially equal to the thickness of the cutting blade body 21.

Further, in this embodiment, the bottom surface 23a and the wall surface 23b of the recess 23 of the base material 22, the lower surface 21c of the cutting body 21 on the side of the portion 21b made of cemented carbide and the peripheral surface 21d having an arc surface shape. In addition, after polishing with a # 1200 diamond grindstone to obtain a mirror surface with a surface roughness of 0.5S or less, the cutting blade body 21 is made so that the portion 21b made of the cemented carbide faces the base material 22 side. That is, that is, the lower surface 21c of the cutting blade 21 and the peripheral surface 21d of the cutting blade 21 are closely attached to the bottom surface 23a of the recess 23 and the wall surface 23b of the recess 23, respectively. . Then, in a vacuum of 10 ⁻³ torr or less, the temperature is raised to around the liquidus temperature of the WC-based cemented carbide, specifically, 1400 ° C. and held for 1 hour. The cutting blade body 21 was fixed to the base material 22 by diffusion-bonding the formed portion 21b and the base material 22. Thereafter, this is subjected to a treatment such as polishing so that the surfaces of the cutting blade 21 and the base material 22 exposed to the outside of the chip are flush with each other.
The cutting edge 24 is formed on the ridge line portion of the portion 21a made of the ultra-high hardness sintered body No. 1 as shown in FIG.
Got

4 and 5 show the chip 25.
Cutting surface of the cutting blade body 21 and the base material 22 perpendicular to each other, that is, a bonding surface of the lower surface 21c of the portion 21b of the cutting blade body 21 made of cemented carbide and the bottom surface 23a of the recess 23 of the base material 22. FIG. 4 is an enlarged view of a cut surface perpendicular to the plane, which is polished by a diamond wheel, and FIG. 4 shows a magnification of 50 times, and FIG. 5 shows a magnification of 500.
It is an enlarged view of 0 times. However, the chain line indicated by symbol S in these figures and FIG. 5 is the position of the joint surface between the lower surface 21c and the bottom surface 23a.

As shown in FIG. 4, in this embodiment, the portion 21b made of cemented carbide and the base material 22 of the cutting blade body 21 are
In appearance, the boundary is integrated to such an extent that it disappears, and no trace of the joint surface S is observed. Further, as shown in FIG. 5, the WC particles forming the cemented carbides of both the cemented carbide portion 21b of the cutting blade 21 and the base material 22 diffuse to the other at the boundary between these cemented carbides. And are bonded to each other, and both of them are structurally structurally the above-mentioned joint surface S.
It is so integrated that no trace of it can be seen. Also,
The Co phase that constitutes the cemented carbide together with the WC particles is also uniformly dispersed in the structure of both cemented carbides. For example, the Co layer is deposited at the position of the joint surface S, and thus it is heterogeneous in the structure. There is no such thing as parts.

That is, in the tip 25 of this embodiment, the portion 21b made of cemented carbide of the cutting blade 21 and the base material 22 are macroscopically and microscopically molded together in the same mold together. As a single member, they are joined and integrated like sintered cemented carbide. As a result, according to the present embodiment, the base material 22 and the cutting blade 2 made of cemented carbide are used.
It is possible to obtain a chip which is directly laminated with the portion 21a made of the ultra-high hardness sintered body 1 and integrally sintered and molded. Moreover, the portion 21 made of this ultra-high hardness sintered body
Originally, a is sintered as the cutting blade 21 together with the portion 21b made of the cemented carbide, and the tip 25 of the present embodiment is a mother body obtained by sintering the cutting blade 21 separately from this. Since the material 22 is diffusion-bonded to the material 22, the cushioning effect of the base material on the above-mentioned ultra-high hardness sintered body does not occur. Therefore, this cushioning effect causes the thickness of the portion 21a of the ultra-high hardness sintered body to be increased. It does not cause unevenness.

As described above, according to this embodiment, there is no need for brazing, and therefore, no intervening brazing layer,
Cutting blade body 21 formed by laminating a cemented carbide and a super-hard sintered body
Can be attached to a base material 22 made of cemented carbide. Therefore, the brazing layer is not exposed on the outer surface of the tip 25, and therefore, the powdery chips produced during cutting are not welded on the exposed brazing layer, and thus the welding is performed. It is possible to prevent the brazing layer from being dug by the chips and the cutting blade body 21 from peeling off, or the welded material from growing to roughen the machined surface.

Further, in this embodiment, the portion 21b made of cemented carbide of the cutting blade 21 and the base material 22 are heated to 1400 ° C., which is near the liquidus temperature of the cemented carbide, and diffusion bonded. However, as described above, these are integrated in terms of microstructure like cemented carbide that is sintered and molded as one member. Therefore, according to the present embodiment, the cutting edge 24 formed in the portion 21a made of the ultra-high hardness sintered body achieves extremely excellent cutting performance, while the tip 25 is cut like in the case of dry heavy cutting. Even under cutting conditions such as exposure to high temperatures, the cutting body does not peel off due to melting of the brazing layer unlike conventional chips, and it consists of ordinary WC-based cemented carbide for heat resistance. It is possible to exhibit performance comparable to chips.

In the present embodiment, as the cemented carbide that constitutes the part 21b of the cutting blade 21 made of cemented carbide and the base material 22, WC-based cemented carbide containing WC as a main component and Co added thereto. The case where the cutting blade body 21 and the base material 22 are diffusion-bonded to each other is 1400 ° C.
However, the joining temperature in this case is 1300 to 145.
It is desirable to set in the range of 0 ° C. This is because when the joining temperature is lower than 1300 ° C., there is a possibility that diffusion of WC particles and the like between the base material 22 and the portion 21b made of the cemented carbide of the cutting blade 21 does not proceed sufficiently. On the contrary, even if joining is performed at a temperature higher than 1450 ° C., not only the joining property between the cutting blade 21 and the base material 22 is not significantly improved, but also if both are kept at a temperature higher than this, the cemented carbide is This is because the constituent Co phase is completely transformed into the liquid phase, which may rather impair the good bondability.

In this embodiment, the case where the cemented carbide made of WC and Co is used as the cemented carbide forming the part 21b made of cemented carbide of the cutting blade 21 and the base material 22 has been described. You may use what added high melting point carbides, such as titanium carbide (TiC) and tantalum carbide (TaC) to this. The external shape and size of the tip 25 shown in this embodiment, the cutting blade body 21 and the base material 22.
The shapes and dimensions of the above are merely examples, and needless to say, these can be appropriately changed as necessary.

Next, the tip 25 of this embodiment is attached to a cutting tool as shown in FIG. 6, a work material FC25, a cutting speed of 700 m / min, a feed of 0.1 mm / rev, a cutting depth of 0.3 mm, and cutting oil used. The continuous cutting was carried out for 60 minutes under the conditions described above, and the presence or absence of chip welding on the chips at this time was investigated. On the other hand, as a comparative example to this, a cutting body and a base material having the same material, shape and size as the cutting body 21 and the base material 22 of the present embodiment are formed, and these are brazed and joined by silver brazing. A chip having the same shape and size as the chip 25 of this example was formed. Then, using this tip, continuous cutting was performed under the same cutting conditions as above, and the presence or absence of welding was investigated. As a result, in the chip of the comparative example, powdery chips produced during cutting were welded to the flank exposed portion and its periphery on the flank as shown in FIG. In Fig. 9, the formation of grooves by digging the brazing layer as shown in Fig. 9 was observed, whereas in the chip 25 of this example, welding of chips to the flanks was not observed.

Next, the same chips as the chips 25 of the present example and the comparative example are attached to the cutting tools, respectively, and the work material SKH11 (HRC62) and the cutting speed 30 are set.
m / min, feed 0.1 mm / rev, depth of cut 4 mm,
Continuous cutting was performed under the condition of dry heavy cutting without using cutting oil. As a result, in the chip of the comparative example, after 5 minutes had elapsed from the start of cutting, the cutting blade was separated and dropped from the base metal due to melting of the brazing layer, whereas in the chip 25 of the example, 60 minutes had elapsed. After that, no abnormality was found in the chip. By the way, the tip of the comparative example reached a temperature of about 650 ° C. at the time when the cutting blade fell off the base material, and the tip 25 of the above-mentioned example reached about 7 at 60 minutes.
A temperature of 00 ° C. had been reached.

[0025]

As described above, according to the present invention, it is possible to join the cutting body and the base material without interposing the brazing layer, whereby welding of chips to the chip and It is possible to prevent the cutting blade from peeling and falling due to digging into the brazing layer due to welding, or melting of the brazing layer at high temperatures, etc. It is possible to provide a chip that can perform stable cutting for a long time or under severe cutting conditions while maintaining excellent cutting performance by the cutting edge formed in the above.

[Brief description of drawings]

FIG. 1 is a perspective view of a cutting blade body 21 according to an embodiment of the present invention.

FIG. 2 is a perspective view of a base material 22 according to an embodiment of the present invention.

FIG. 3 is a perspective view of a chip 25 showing an embodiment of the present invention.

FIG. 4 is an enlarged view (50 times) of a cutting surface perpendicular to a bonding surface S between the cutting blade body 21 and the base material 22 of the embodiment shown in FIG.

5 is an enlarged view (5000 times) of a cutting surface perpendicular to a bonding surface S between the cutting blade 21 and the base material 22 of the embodiment shown in FIG.

FIG. 6 is a plan view showing a cutting tool 11 on which a chip 1 of a conventional example is mounted.

7 is a side view showing a cutting state by the cutting tool 11 shown in FIG.

8 is a side view showing a state in which welding has occurred in the cutting tool 11 shown in FIG.

9 is a side view showing a state in which welding has progressed in the cutting tool 11 shown in FIG.

[Explanation of symbols]

21 cutting blade 21a portion made of super-hard sintered body 21b portion made of cemented carbide 22 base material 23 recess 24 cutting blade 25 tip S cutting blade 21 portion made of cemented carbide 21b and base material Joining surface

Claims (1)

[Claims] 1. A cutting blade body formed by laminating a cemented carbide and a cemented carbide in a recess formed in a base material made of cemented carbide. In a throw-away tip which is joined toward the base material side and a cutting edge is formed in a portion of the cutting edge body made of the ultra-high hardness sintered body, a cemented carbide of the base material and the cutting edge body is formed. A throw-away tip characterized in that a portion made of an alloy is heated to a temperature near a liquidus temperature of the cemented carbide and diffusion-bonded.