JPH0373210A - High hardness cutting tool and manufacture and use thereof - Google Patents

Abstract

PURPOSE:To enable working in a high efficiency, even if the shape of an edge part is complicated, without causing the separation of tip while keeping the working accuracy by bonding an abrasive grain layer containing high-hardness abrasive grains such as diamond, CBN, or the like on the circumference of a core material, so that an edge part can be formed on the abrasive grain layer. CONSTITUTION:A cylindrical body of a high-hardness abrasive grain sintered body such as diamond, CBN, or the like which is made of cemented carbide or the like so as to be capable of being fitted on the small-diameter part 13b of a core material 13 and has a prescribed thickness is bonded on the circumference of the small-diameter part 13b by soldering or the like to form an abrasive grain layer 14. While the entire side surface of the small- diameter part 13b of the core material 13 is covered by the abrasive grain layer 14, in the end surface thereof, only the peripheral part is covered by it, and a hollow part 19 is formed in the central part so as to expose the core material 13 for forming a center hole 20. Then, the abrasive grain layer 14 is subjected to working using a tool grinder or the like, and the edge part 11 is provided with spiral twisted grooves 15 and spiral lands 16, and on the end periphery on the cutting side of each land 16, a twisted cutting edge provided, and further on the end of each land 16, a straight edge 18 is provided.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a high-hardness cutting tool, and more specifically, at least a portion of the blade portion is made of a high-hardness material such as diamond or cubic boron nitride (hereinafter referred to as CBN). The present invention relates to a cutting tool such as an end mill formed of an abrasive layer containing abrasive grains, and a method for manufacturing and using the same.

[Prior Art] In recent years, many tool materials have been developed and put into practical use in order to meet the demands for improved cutting efficiency and extended tool life. As one type of these tools, there has been known a tool in which a cutting portion of a tool body is provided with a sintered body of diamond or CBH, which has extremely high hardness and excellent wear resistance.

This sintered body is made of fine CBN or diamond particles formed by recrystallizing them under ultra-high pressure on a cemented carbide substrate, using tungsten carbide (WC) or cobalt (Co) as a binder, at a 40-5° angle. Kbar, 1400-160
It is sintered at a high temperature of 0'C and under ultra-high pressure. This sintered body is usually formed into a circular, semicircular, fan-shaped, triangular, etc. thin plate chip, and the chip is used by embedding and fixing it in a tool body made of cemented carbide or steel by brazing. That's what I do.

The aforementioned tools using diamond particles are used for cutting non-ferrous materials such as high silicon aluminum light alloys, plastics, and ceramics because they tend to chemically react with iron at high temperatures. The tool is mainly used for cutting heat-treated high-hardness steel with a Rockwell hardness (HRc) of 50 or more and chilled cast iron.

An example of such a conventional tool is shown in FIGS. 7 to 9.

Fig. 7 shows a twist drill, Fig. 8 shows a straight-edged grooved drill, and Fig. 9 shows a straight reamer, all of which have a cutting edge (1) and a shank (2). diamond or CB
The chip of the sintered body (3) of N particles is embedded and fixed by brazing in the part of the blade (1) that is subjected to the highest load during processing.

[Problem to be solved by the invention]

In this way, all of the conventional cutting tools described above have a tip made of a sintered body (3) of diamond or CBN particles in the blade part (1).
The tool material, such as cemented carbide, is only partially buried, and the other parts are exposed as they are. This is because the chips of the sintered body (3) are formed by sintering particles under high temperature and ultra-high pressure, so there are naturally limitations on shape, size, and volume. With the above method, it is not possible to manufacture products that are too large or have complicated shapes.

Therefore, the tip of the sintered body (3) cannot be provided so as to cover a wide area of the blade (1), and the tip of the sintered body (3) cannot be installed in a tool with a complicated shape (for example, a small diameter drill with a helical groove). For reamers and end mills with long blades,
It could not be used in practice because it could not be buried along the shape of the blade (1).

In addition, in the case of diamond sintered compacts, there is a nearly three-fold difference in thermal expansion coefficient between the diamond sintered compacts and the cemented carbide substrate, so when the diamond sintered compacts are exposed to high temperatures, during cutting There is a possibility that stress will be concentrated at the interface between the diamond sintered chip and the cemented carbide substrate, causing a peeling phenomenon between the two. This situation can similarly occur when a diamond sintered chip with a substrate is brazed to a tool body made of cemented carbide.

The above circumstances are exactly the same in the case of CBN sintered bodies.

Therefore, an object of the present invention is to prevent the blade from having a complicated shape such as a drill or reamer with a twisted groove or an end mill with a long blade, since the blade is covered over a wide area with a highly hard material. It has excellent durability, and
It is an object of the present invention to provide a cutting tool capable of processing a workpiece with high precision and high efficiency, and a method for manufacturing the same.

Another object of the present invention is to provide a method of using a cutting tool in which the machining performance of the cutting tool is exhibited extremely effectively.

[Means to solve the problem]

A first cutting tool of the present invention includes: a core material; an abrasive grain layer containing high-hardness abrasive grains such as diamond or cubic boron nitride fixed around the core material; and a cutting tool provided in the abrasive grain layer. The present invention is characterized in that the blade part is rotated and brought into contact with the workpiece for cutting.

Further, a second cutting tool of the present invention includes: a rod-shaped core material; an abrasive grain layer containing high-hardness abrasive grains such as diamond or cubic boron nitride fixed around the core material; The abrasive grain layer is provided with a blade formed on the side surface of the layer and a groove for discharging machining waste, and the abrasive grain layer is brought into contact with the workpiece while being rotated, and the abrasive grain layer is rotated and brought into contact with the workpiece. It is characterized by the fact that it is made to do so.

It is preferable that the abrasive grain layer is provided with a depression at the center of the tip surface so that the core material is exposed from the depression.

Further, the width of the groove for discharging machining debris is preferably narrower than the width of the land formed on the side surface of the abrasive grain layer.

The abrasive grain layer can be formed from a sintered body formed by sintering fine particles of high-hardness abrasive grains such as diamond or cubic boron nitride, and this sintered body may include a resin-based or metal-based bond. , vitrified or cemented carbide may be included as a binder.

The method for manufacturing the first cutting tool of the present invention includes a step of forming and fixing an abrasive grain layer containing high-hardness abrasive grains such as diamond or cubic boron nitride around a core material, and a step of forming a machine on the abrasive grain layer. The method is characterized in that it includes a step of forming the blade portion by machining or electrical discharge machining.

Further, the method for manufacturing the second cutting tool of the present invention includes: forming and fixing an abrasive grain layer containing high-hardness abrasive grains such as diamond or cubic boron nitride around a rod-shaped core material; The method is characterized in that it includes a step of forming blades and grooves for discharging machining waste by machining or electrical discharge machining on the side surface of the grain layer.

Furthermore, the method of using a cutting tool of the present invention is characterized in that a workpiece is machined while rotating the cutting tool at a cutting speed of 20 m/sec or more.

[Effect]

As a result of the above configuration, in the cutting tool of the present invention, the blade portion is provided on the abrasive grain layer fixed around the core material, so the blade and groove can be formed into the desired shape after the abrasive grain layer is fixed over a wide range. By forming this, even if the blade part has a very complicated shape, a wide area can be covered with the high hardness material. This abrasive grain layer containing high-hardness material, i.e., high-hardness abrasive grains, has excellent wear resistance, and unlike conventional tools, the chips are not manufactured separately and embedded in the tool body, so the tool The durability can be greatly improved.

In addition, in the cutting tool of this invention, since the blade portion is provided in the abrasive grain layer, there are many recesses on the surface of the blade portion, and during machining, cutting oil accumulates in these recesses and acts as a lubricant. . Therefore, cutting efficiency and cutting accuracy can be increased.

When using the cutting tool of the invention, the cutting speed is preferably 20 m/sec, higher than that of conventional cutting tools.
Rotate at high speed so that the rotation speed is higher than c.

In this way, even if the abrasive grain layer contains a binder with a hardness lower than that of high-hardness abrasive grains, the entire abrasive grain layer will be in almost the same state as if it were made of high-hardness abrasive grains, and the abrasive grain layer The blade provided on the machine can cut the workpiece in the same way as a conventional end mill or milling cutter.

When a workpiece is cut, the discharge of machining debris becomes a problem, but this problem can be easily solved by providing a groove for discharging machining debris in the abrasive grain layer.

[Example] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show a first embodiment in which a high-hardness cutting tool according to the present invention is configured as an end mill. This end mill (10) has a straight blade part (1
1) and a shank part (12), and the blade part (11) has four spiral helical grooves (1) arranged at equal intervals in the circumferential direction.
15) and four helically twisted lands (16) formed by these twisted grooves (15). The edge on the cutting side of each land (16) (the edge on the left when viewed from the tip side of the blade part (11)) has a twisted cutting edge (17
) is provided. Furthermore, at the tip of each land (16),
Straight blades (
18) is a provision.

As shown in Fig. 2, a recess (19) is formed in the center of the tip surface of the blade (11), so that four straight blades (
18) exists only around the tip surface. This depression (
19) is further provided with a center hole (20).

As is clear from FIGS. 1 and 2, in this end mill (10), the depth and width of the helical groove (15) are considerably large, and therefore the width of the land (16) is very narrow. .

As shown in Fig. 1, this end mill (10) is made of a steel cylindrical core material (
13) and an abrasive layer (14) formed and fixed around the small diameter portion (13b).
4) is provided with the blade portion (11). The abrasive layer as described above is not provided around the large diameter portion (13a) of the cylindrical core material (13), and the core material (13) is exposed as it is. ). On the tip surface of the blade portion (11), the abrasive layer (14) is formed only in the portion where the straight blade (18) is provided,
The core material (13) is not formed in the recess (19).
) is exposed.

By providing the recess (19) and the center hole (20), the core material (11
) has the advantage that the tool material formed by fixing the abrasive grains Ji (14) becomes easier to hold.

The abrasive grain layer (14) is made of diamond abrasive grains, which is one of the materials with very high hardness and excellent wear resistance. This abrasive grain layer (14) is made by adding a binder to fine diamond particles and sintering them by a known method. As the binder, it is preferable to use resin-based or metal-based bond, vitrified ceramics, or cemented carbide, but the binder does not necessarily have to be used.

Other than diamond, preferable abrasive grains constituting the abrasive grain layer (14) include CBN.

However, this invention is not limited to these.
Of course, abrasive grains other than these can also be used as long as they have excellent hardness and wear resistance.

The end straw reel (10) having the above structure is manufactured as follows.

First, a cylindrical core material (13) having a two-stage shape as shown in FIG. 3 is prepared. The core material (13) can be made of any known material such as steel or cemented carbide. At the same time, high hardness abrasive grains such as diamond and CBN are sintered to form a small diameter portion (13b) of the core material (13).
It is formed into a cylindrical shape that can be fitted into the cylinder and has a predetermined thickness.

Next, this cylindrical body of high-hardness abrasive grains is brazed around the small diameter portion (13b) of the core material (13), fixed with adhesive, etc., and the high-hardness abrasive grains are placed around the core material (13). The abrasive layer (
14). Ultra-high-pressure sintered bodies such as diamond used in conventional tools cannot achieve such adhesion, but since this invention uses abrasive grains such as diamond, adhesion to the core material (13) is possible. It is.

Here, the shape of the abrasive grain layer (14) covers the entire side surface of the small diameter portion (13b) of the core material (13), as shown in FIGS. It is covered, thus forming a depression (19) in the central part. Therefore, the core material (13) is exposed in the depression (19). Inside the recess (19), a center hole (20) is formed on the long sleeve (center axis) of the core material (13).

Subsequently, the abrasive grain layer (14) is machined using a processing machine such as a known tool grinder, and a helical groove (15), a helical cutting edge (17) and a helical cutting edge (17) are formed on the abrasive grain layer (14). Straight blade (18
) to complete the blade part (11). Abrasive grain layer (14
) can be performed using a grindstone or cutting tool made of a high-hardness material such as diamond or CBN. At this time, the tool material shown in FIGS. 3 and 4 is held by gripping the large diameter portion (13a) of the core material (13) with the chuck of the processing machine, while gripping the center hole (19) with the rod of the tailstock. Processing is performed by pressing and locking.

Note that the method of machining the blade portion (11) is not limited to such machining, and electric discharge machining may also be used.

5 and 6 show a second embodiment of the high hardness cutting tool according to the present invention. This second embodiment is also similar to the first embodiment.
The core material (13) of the end mill (10) of the first embodiment is formed as an end mill (30) in the same manner as in the embodiment.
A similar cylindrical core material (33) and this cylindrical core material (33)
It consists of an abrasive layer (34) fixed to the outer periphery of the abrasive grain layer (34).

A blade portion (31) is formed in the abrasive grain layer (34), and a portion of the core material (33) that is not covered with the abrasive grains N (34) is defined as a shank portion (32). Four twisted grooves (35) and four lands (36) are provided on the surface of the abrasive grain layer (34), and a shear cutting edge (37) is provided at the edge of each land (36). It is a provision.

As shown in FIGS. 5 and 6, the helical groove (35) of this end mill (30) is similar to that of the end mill (10) of the first embodiment.
) is not deep and wide like the twisted groove (15), but is very shallow and narrow in width. Moreover, here the width of the twisted groove (35) is narrower than the width of the land (36). This is because by making the width of the land (36) as wide as possible, the abrasive grain layer (34) is brought into contact with the workpiece over a larger area.

Further, the twisted cutting edge (37) provided at the edge of each land (36) is not sharp like the cutting edge (17) of the end mill (10) of the first embodiment, but the cross section of the blade part is at a right angle. The angle is close to , and it is very blunt. By doing this, combined with the fact that the helical groove (35) is formed very shallow, the helical cutting edge (37)
This has the advantage that the strength of the cutting edge (37) can be increased, and there is no fear that the cutting edge (37) will break even when rotated at high speed.

On the tip surface of the blade part (31), an abrasive grain layer (34) is formed only around the periphery, similar to the end mill (10), and a depression (39) is provided in the center from which the core material ( 33) is exposed. In addition, in this depression (39), the core material (
33) is provided with a center hole (40). However, no equivalent to the straight blade (18) of the end mill (10) is provided. Therefore, during machining, the annular abrasive grain layer (34) on the tip surface of the blade (31) only rotates while being pressed against the workpiece, and therefore only grinding is performed on the tip surface without cutting. become.

This end mill (30) can be manufactured in exactly the same manner as the end mill (10).

The end mills (10) and (30) configured as described above can be used in the same way as a normal (conventional) end mill. That is, the end mill (10) (30) is attached to a known milling machine via the shank part (12) (32), and the blade part (11) (31), that is, the abrasive layer (14)
While pressing the tip and side surfaces of the end mill (34) against the workpiece, rotate the end mill (10)' (3
0) or the workpiece may be moved in a direction perpendicular to the long axis.

In the case of the end mill (10), the straight blade (18) and helical cutting edge (17) provided on the abrasive grain layer (14) cut the workpiece, and machining waste is discharged through the helical groove (15). be done.

The surface of the workpiece end mill (10) perpendicular to the long sleeve is processed by a straight blade (18), and the surface parallel to the long sleeve is processed by a helical cutting edge (17). In this way, the workpiece can be processed.

The case with the end mill (30) is almost the same, but
Since the end mill (30) does not have a straight edge on its tip surface and the helical cutting edge (37) is also formed to be blunt, the cutting speed needs to be slightly higher than that of the end mill (10).

In addition, the machining conditions require that the end mill be rotated at a high speed and the cutting speed must be several times higher than that of conventional end mills made of steel or cemented carbide. Adequate machining cannot be achieved at the low cutting speeds commonly used. This is, firstly, the cutting edge (17) (37)
and that the straight blade (18) is made of abrasive grains 1i (14) (34) rather than metal such as steel or cemented carbide; Although the hardness of abrasive grains such as , CBN, etc. is extremely high, the hardness of the binder that binds the abrasive grains is much lower than that, so the cutting edge (17) is lower than that of conventional end mills.
This is due to the small cutting ability of (37) and the straight blade (18).

However, by increasing the cutting speed, this point is completely resolved. This means that when the cutting speed is increased, that is, the rotational speed of the end mill (10) (30) is increased, the cutting edge (17
) (37) and the entire straight edge (18) become extremely hard, equivalent to abrasive grains such as diamond, and the cutting edge (17) becomes extremely hard.
) (37) and the straight blade (18) exhibit cutting ability equivalent to or greater than that of conventional end mills.

According to experiments, the cutting speed should be set at 20 m/5ec (
1200m/min) or more,
Preferably 20~45m/sec (1200~27m/sec
00 m/n+in). Although this cutting speed is approximately 3 to 10 times higher than that of a conventional end mill, it is sufficiently possible using a recently developed high frequency spindle or magnetic bearing spindle.

Thus, the end key of this invention (10) (30)
Now, the cutting edge (17) provided on the abrasive grain layer (14) (34)
) (37) and the straight blade (18), cutting waste must be discharged during machining. Therefore,
Twisted grooves (17) (37) on blade parts (11) (31)
is the provision.

Conventionally, disc-shaped grindstones to which high-hardness abrasive grains such as diamond or CBN are attached have been known, but the purpose of these grindstones is to grind the workpiece with the abrasive grains, and the machines that can be used with them are not suitable for grinding. limited to the board. Furthermore, it is completely unknown in the art to attach these disc-shaped grindstones to a milling machine and use them for end milling or milling. Therefore, this invention is completely different from the disc-shaped grindstone described above.

Furthermore, conventional disc-shaped grindstones perform abrasive processing,
The processing principle is clearly different from cutting processing such as end milling and milling.

In addition, in the above explanation, only the case where this invention is implemented as an end tool is explained, but this invention is not limited to this, and it can be used with known cutting tools such as twist drills, reamers, and ordinary parallel and face mills. Of course, it can also be applied to

Further, the abrasive grain layer (14) (34) may be provided on the entire blade portion (11) (31) as in the above-mentioned embodiment,
It may be done only near the tip where the burden during machining is large.

〔Effect of the invention〕

As described above, in the cutting tool of the present invention, an abrasive grain layer containing high-hardness abrasive grains such as diamond, CBN, etc. is fixed around the core material, and a blade portion is formed in the abrasive grain layer. ,
Even if the shape of the blade part is complicated, such as a drill hammer with a twisted groove or an end mill with a long blade length, the blade part is covered over a wide area with a high hardness material, and
Unlike conventional cutting tools with embedded high-hardness chips, there is no fear that the abrasive grain layer will peel off due to thermal expansion during cutting operations.

Therefore, it has excellent durability and can stably exhibit excellent cutting performance over a long period of time.

In addition, since the blade part is provided on an abrasive grain layer containing high-hardness abrasive grains, cutting oil can accumulate in many recesses on the surface of the abrasive grain layer during machining, and therefore the hardness of the blade part is high. In combination, it is possible to process the workpiece with high efficiency while maintaining high processing accuracy.

When a depression is provided at the center of the tip surface of the abrasive grain layer, the tool material can be easily held during machining of the blade portion.

By providing a groove for discharging machining waste in the blade part and making the width narrower than the width of the land, there is no fear that the blade will be damaged during machining even when machining is performed at high speed.

In addition, in the cutting tool manufacturing method of the present invention, the blade portion is formed by performing machining or electrical discharge machining on the abrasive grain layer fixed around the core material, so even if the blade portion has a complicated shape, the blade and grooves can be manufactured easily and accurately.

Furthermore, the method of using the cutting tool of the present invention allows the performance of the cutting tool to be exhibited extremely effectively simply by increasing the cutting speed compared to conventional cutting tools, and therefore the above-mentioned effects of the cutting tool are achieved. can be fully demonstrated.

[Brief explanation of drawings]

1 to 4 show a first embodiment of a cutting tool according to the present invention, in which FIG. 1 is a half-sectional front view, FIG. 2 is a side view of the cutting tool as seen from the tip side, and FIG. FIG. 3 is a half-sectional front view of the tool material showing a state in which the abrasive grain layer is fixed to the small diameter portion of the core material, and FIG. 4 is a side view of the tool material seen from the tip side. 5 and 6 show a second embodiment of the present invention, with FIG. 5 being a front view and FIG. 6 being a side view seen from the tip side of the blade. 7 to 9 show conventional cutting tools, and FIG.
) is a front view of the twist drill, FIG. 7(b) is a side view as seen from the tip side, FIG. 8(a) is a front view of the straight fluted membrane drill, and FIG. 8(b) is a side view from the tip side. Side view, Figure 8 (
c) is a sectional view of the stepped portion, FIG. 9(a) is a front view of the straight reamer, and FIG. 9(b) is a side view seen from the tip side. (10) (30)... End mill (11) (
31)...Blade part (12) (32)...Shank part (13) (33)...Core material (13a)...Large diameter part (13b)...Small diameter part (14) ( 3
4)...Abrasive grain layer (15) (35)...Twisted groove (16) (36)...Land

Claims (1)

[Claims] 1. A core material; an abrasive grain layer containing high-hardness abrasive grains such as diamond or cubic boron nitride fixed around the core material; and a blade provided in the abrasive grain layer. 1. A high-hardness cutting tool comprising: a cutting tool that cuts a workpiece by bringing the blade into contact with the workpiece while rotating the blade. 2. A rod-shaped core material, an abrasive grain layer containing high-hardness abrasive grains such as diamond or cubic boron nitride fixed around the core material, and a blade and processing formed on the side surface of the abrasive grain layer. A high-hardness cutting tool, comprising: a groove for discharging debris; the abrasive layer is brought into contact with the workpiece while rotating, and machining is performed by the side and tip surfaces of the abrasive layer. . 3. The high-hardness cutting tool according to claim 1 or 2, wherein a depression is provided in the center of the tip surface of the abrasive grain layer, and the core material is exposed from the depression. 4. The high-hardness cutting tool according to claim 2 or 3, wherein the width of the machining waste discharge groove is narrower than the width of the land formed on the side surface of the abrasive grain layer. 5. High-hardness cutting according to any one of claims 1 to 4, wherein the abrasive grain layer is formed from a sintered body formed by sintering fine particles of high-hardness abrasive grains such as diamond and cubic boron nitride. tool. 6. The cutting tool according to claim 5, wherein the sintered body contains a material selected from the group consisting of resin bond, metal bond, vitrified, and cemented carbide as a binder. 7. A step of forming and fixing an abrasive grain layer containing high hardness abrasive grains such as diamond or cubic boron nitride around the core material, and a step of forming a blade part in the abrasive grain layer by machining or electrical discharge machining. The method for manufacturing a high-hardness cutting tool according to claim 1, comprising the steps of: 8. Forming and fixing an abrasive grain layer containing high-hardness abrasive grains such as diamond and cubic boron nitride around a rod-shaped core material, and forming a blade and a blade on the side surface of the abrasive grain layer by machining or electric discharge machining. 3. The method for manufacturing a high-hardness cutting tool according to claim 2, further comprising the step of forming a groove for discharging machining waste. 9. The cutting tool according to any one of claims 1 to 6,
A method of using a high-hardness cutting tool, which comprises machining a workpiece while rotating the tool at a cutting speed of 20 m/sec or more.