JPH049754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cylinder of composite sintered material with a hard head.

More specifically, the present invention includes a hard head such as a diamond sintered body or a high-pressure phase boron nitride sintered body;
The present invention relates to a small-diameter cylindrical body of composite sintered material that is integrally formed with the head and includes a support made of, for example, cemented carbide.

Such a small-diameter cylindrical body of composite sintered material, which is the object of the present invention, can be used as a material for a high-performance small-diameter drill or as a head portion of a dot printer.

Prior Art Drills made of cemented carbide are often used for drilling holes in metal and non-metal materials. Especially for drilling holes in printed circuit boards, the demand for which has been growing rapidly in recent years, the diameter is 1 mm.
The front and rear cemented carbide drills are used.

Various materials are used for printed circuit boards, but the main one used is a reinforced resin made by impregnating glass fiber with epoxy resin, which is generally referred to as a glass-epoxy board.

Drilling of such printed circuit boards is usually done using a highly rigid drill at a rotation speed of 50,000 to 60,000 rpm, but the glass fibers contained in the board wear out the carbide tools very quickly, and generally Carbide drills reach the end of their life after 3000 to 5000 hits (hits refers to the number of holes drilled). These drill machines are equipped with an automatic tool changer, and the drill that has reached the end of its service life is automatically replaced.However, in order to improve production efficiency, the time required for automatic tool change is also an issue, and the drill life is reduced. There is a strong demand to reduce the number of tool changes, that is, the tool change time.

Looking at the characteristics of printed circuit boards, there is a strong demand for higher functionality by further improving heat resistance, etc., and although it is actually possible to manufacture such board materials, it is generally difficult to produce such high-performance materials. Due to cutting, conventional ultra-hard drills have a very short lifespan, and the reality is that this type of substrate material cannot be put to practical use.

Furthermore, it is desired to increase the rotational speed of the drilling drill in order to drill even more efficiently into ordinary glass epoxy substrates, but this also means that the lifespan of conventional cemented carbide drills rapidly decreases as the cutting speed increases. Since this decreases, it is not possible to achieve high efficiency by increasing the drill rotation speed.

On the other hand, sintered diamond tools, whose usage has been rapidly increasing in recent years, have significantly higher hardness and wear resistance than carbide tools, and are extremely useful when cutting the above-mentioned reinforced resins. Demonstrates high performance.

However, as shown in FIG. 1, this sintered diamond tool holds as a chip a composite sintered body 13 in which a sintered diamond layer 11 is bonded to a support portion 12 of cemented carbide.

When manufacturing a drill using this composite sintered body 13, the composite sintered body 13 must be fixed to the tip of the shank 15 by some method as shown in FIG.

However, the diameter of the drill tip made from this composite sintered body 13 is generally about 1 mm, and if such a small diameter drill tip does not have a very strong bonding strength with the shank 15, the joint 16 will be damaged by grinding the cutting edge after bonding. The drill will fall off, making it impossible to manufacture a good drill. In particular, sintered diamond is difficult to grind, has high grinding resistance, and is insufficient in strength to the level of normal silver brazing. For example, electron beam welding can be considered as a bonding method with high bonding strength, but if electron beam welding were to be implemented, the drill manufacturing process would be complicated and the cost would be high, making it difficult to meet the rapid increase in demand for high-performance drills in recent years. Nakatsuta.

OBJECTS OF THE INVENTION The present invention aims to solve the problems of the prior art described above, and more specifically, to provide a small-diameter composite sintered material cylinder having a hard head, which has improved wear resistance and rigidity. The purpose of this invention is to make it possible to easily manufacture an excellent drill.

A further object of the present invention is to easily and efficiently drill holes in difficult-to-cut substrates such as glass epoxy substrates.
Our goal is to provide long-life drills at low prices.

A further object of the present invention is to provide a small diameter cylindrical body of composite sintered material as an intermediate product from which elongated members requiring ultra-hard tips, such as heads of dot printers, can be easily manufactured.

Structure of the Invention The present invention comprises a hard sintered part containing 50% or more of either diamond powder or cubic boron nitride powder and having a circular cross section, and one end joined to the hard sintered part. A cylindrical body of a composite sintered material is provided, which is provided with a supporting part having a cylindrical shape having approximately the same diameter as the hard sintered part.

The feature of the present invention is that this composite sintered material cylinder is
A first material layer containing 50% or more of either diamond powder or cubic boron nitride powder with an average particle size of 10 μm or less, and carbides of elements of groups 4a, 5a, and 6a of the periodic table, or carbides of elements of groups 4a, 5a, and 6a of the periodic table. A second material layer consisting of a cemented carbide block in which mutual solid solution carbide is bonded with an iron group metal is stacked and housed in the same hot press container in the pressing direction, and then
A composite sintered body block with a large cross-sectional area in which a hard sintered part and a supporting part are joined is produced by hot pressing under high temperature and high pressure, and the obtained composite sintered body block is processed by electric discharge machining to form the above material. It is made by cutting in the stacking direction, and the axial length of the hard sintered part of this composite sintered material cylinder is 0.3 to 2.
mm, the axial length of the support part is at least 5 times the axial length of the hard sintered part, and the composite sintered material cylinder has a diameter of 3 mm or less and a total length of 10 mm.
That's all for now.

When making chips for cutting tools using diamond powder, if diamond powder with an average particle size exceeding 10 μm is used as a raw material, the cutting edge of the cutting tool obtained by processing this composite sintered material cylinder will be sharp. The hard sintered part is preferably made of diamond or high-pressure phase boron nitride with a diameter of 10 μm or less, since the hard sintered part cannot be molded into a material with a diameter of 10 μm or less, and therefore does not have high performance.

When the hard sintered part is sintered with diamond powder as the main component, it may be sintered with diamond powder alone or with a binder containing 70% or more of diamond, with the remainder being Fe, Co, or Ni as the main component. It is a result of the following. A preferable example of such a hard sintered part is one with a diamond content of 70% or more.
There is a sintered body of WC-5 to 15% Co.

In addition, when using diamond powder alone as the material for the hard sintered part, the binder component in the support part material will infiltrate into the hard sintered part material powder during sintering of the hard sintered part. Thus, sintering of the hard sintered part is achieved.

If the hard sintered part is mainly composed of high-pressure phase boron nitride powder, high-pressure phase boron nitride powder alone or 50%
There is a product obtained by adding carbides, nitrides, carbonitrides of elements of groups 4a, 5a, and 6a, and aluminum and/or silicon as binders to the above-mentioned high-pressure phase boron nitride and sintering them. Note that the powder of high-pressure phase boron nitride alone does not require a binder, and sintering of the hard sintered part can be achieved by itself. Here, high-pressure phase boron nitride means cubic boron nitride and wurtzite boron nitride.

The support part is made of so-called cemented carbide, that is, carbides, nitrides, carbonitrides, borides, silicides of elements of Groups 4a, 5a, and 6a of the periodic table, or mutual solid solution carbides of these elements, Fe, Co, or Ni. It is a sintered alloy or cermet bonded with iron group metals. An example of a cermet is a carbide of (Mo,W)C bonded with an iron group metal such as Ni or Co.

Still another support material is a sintered alloy called heavy metal, which contains 80 to 98% by weight of W and the remainder is Ni-Fe or Ni-Fe-Cu.

One important feature of the composite sintered material cylinder of the present invention
First, the bond between the hard sintered part and the support part is formed during the sintering process of the hard sintered part. Therefore, the component of the support part needs to be a material that can be bonded to the hard sintered part during the sintering process of the hard sintered part. However, within the range of the components of the hard sintered part and the support part mentioned above, such combinations are infinite, and in the sintering process of diamond or high-pressure phase boron nitride by hot pressing under high pressure and high temperature, the above-mentioned combinations are possible. The ferrous metal binding material in the support member is infiltrated, and the hard sintered part and the support part are easily joined. Therefore, it goes without saying that those skilled in the art can select the components of the hard sintered part and the supporting part as needed within the above-mentioned range.
Further, the high-pressure phase boron nitride powder can be sintered alone as described above, and the connection with the support part is achieved during the sintering process.

Furthermore, according to one embodiment of the present invention, the hard sintered part and the support part are joined via an intermediate joining layer having a thickness of 0.5 mm or less.

The intermediate bonding layer is made of less than 70% high-pressure phase boron nitride and the remainder is one of carbides, nitrides, carbonitrides, or borides of Ti, Zr, and Hf in group 4a of the periodic table, or a mixture thereof. Those mainly composed of solid solution compounds and those containing Al and/or Si.
Those containing 0.1% by weight or more are preferable.

Further, according to one aspect of the invention, the support may be composed of two or more layers of material in the axial direction.
As an example of this, the support side layer of the second material layer is a WC-Co sintered alloy, and the hard head side layer is a (Mo,w)C carbide with a Ni or Co iron group. Some are made of cermets bonded with metal.

As described above, in the present invention, it is important that the bond between the hard sintered part and the support part be formed during sintering of the hard sintered part. For this reason, when hot pressing (sintering) the hard sintered part, it is necessary to place the material powder of the hard sintered part on the support part material and perform hot pressing. At this time, the material serving as the support portion may be a solid cemented carbide that has already been sintered, or may be a powder of a cemented carbide material.

The composite sintered material cylindrical body of the present invention has been described above based on the components of its hard sintered part before hot pressing, but the hard sintered part after sintering, the support part, and their joint parts have not been specified. . However, the composition of the hard sintered part, the support part, and their joint parts after sintering varies slightly depending on the combination itself and the temperature, pressure, and duration of the hot press, and those skilled in the art will be able to understand this. When carrying out the invention, it is easier and more accurate to understand the content of the invention if it is based on the ingredients before hot pressing. Therefore, further explanation of the components of the hard sintered part, the support part, and their joint parts after sintering will be omitted.

Next, the dimensional characteristics of the composite sintered material cylinder of the present invention will be explained.

The cylindrical body of the composite sintered material of the present invention needs to have a diameter of 3 mm or less. Cylindrical bodies of composite sintered material with a diameter exceeding 3 mm are unsuitable as materials for drilling holes in printed circuit boards. Moreover, even if it is used after grinding, the grinding allowance becomes large and it is uneconomical.

In addition, the axial length of the hard sintered part is 0.3 to 2 mm.
is within the range of At the end of 0.3mm, the required face cannot be formed when used as the tip of a drill.
If the length exceeds 2 mm, a large amount of expensive diamond powder etc. will be used, which is uneconomical.

Further, the length of the supporting part of the cylindrical body of the composite sintered material of the present invention needs to be at least five times the length of the hard sintered part. When making a drill, it is necessary to ensure the length of the cutting edge of the drill and embed the end in the shank.
A support part that is more than twice as long is required.

The elongated composite sintered material cylinder of the present invention as described above has never existed before. The reason for this is that for materials such as the cylindrical body of the composite sintered material of the present invention, which has a large axial length relative to its cross-sectional area, even if hot pressing is performed by applying pressure in the axial direction, the pressure loss due to the powder material layer is large. This is because the necessary pressure is not applied to the central portion, and a strong sintered body cannot be obtained. Furthermore, for materials with a small cross-sectional area and a large axial length, hot pressing can be performed at a higher pressure by applying pressure in the axial direction to maintain a stable temperature and pressure of diamond or high-pressure phase boron nitride. This is because the pressure distribution inside becomes extremely irregular, which tends to cause deformation such as bending, making it impossible to obtain a sintered body with sufficient dimensional accuracy.

Therefore, in hot pressing of elongated sintered material, the sintered material is arranged so that the axial direction of the sintered material is perpendicular to the pressing direction. When an elongated composite material like the one of the present invention is sintered using such a hot press,
The pressure in the direction perpendicular to the interface between different material layers was small, and a bond of sufficient strength could not be obtained.

In contrast, as will be described later, the present inventors manufactured a composite sintered body block by hot pressing a composite material block with a large cross-sectional area, and then cut this into a small-diameter cylindrical body using electric discharge wire cutting. A cylindrical body of a composite sintered material having a small diameter, elongated, and hard head was successfully provided.

Figures 3a and 3b of the accompanying drawings each show the external appearance of the composite sintered material cylinder of the present invention.

The composite sintered material cylindrical body 23 shown in FIG. It is joined.

On the other hand, the composite sintered material cylinder 23 shown in FIG. 3b
Here, the hard sintered part 21 and the support part 22 are joined with an intermediate joining layer 24 interposed therebetween.

Next, a method for manufacturing a cylindrical composite sintered material according to the present invention will be explained.

As described in the patent application "Method for manufacturing composite sintered material rod-shaped body" dated the same date as this application, the present inventors
First, a composite material block with a large cross-sectional area is hot-pressed to produce a composite sintered body block, which is then cut into a small-diameter cylindrical body using electrical discharge wire cutting. We succeeded in providing a cylindrical body of sintered material.

That is, in the method described in the patent application "Method for manufacturing rod-shaped composite sintered material" dated the same date, a first material layer for a hard sintered body containing 50% or more of diamond powder or high-pressure phase boron nitride powder is used. and a second material layer to be bonded to the hard sintered body of the first material in the sintering process of the first material layer, and stacked in the pressing direction in the same hot press container, At the same time, the first material layer is sintered by hot pressing under high temperature and high pressure, and the obtained hard sintered body is joined to the second material layer to form a layer of hard sintered body with a predetermined thickness. Form a composite material block having the following properties, and cut the composite material block in the material layer thickness direction by a discharge wire cutting method to obtain a composite material block with a thickness of 1/5 or less and 3 mm or less with respect to the material layer thickness direction of the composite material block. Two or more elongated composite material rods having a cross section with an equivalent diameter DE and having a hard sintered body at the head are cut out.

When hot-pressing and sintering this composite material, according to the invention, the axial length of the composite material block must be no more than 3 times, preferably no more than 2 times, the equivalent diameter DE. This is because if a composite material block with an axial length exceeding three times is hot-pressed, the pressure distribution within the composite material block will become irregular, resulting in bending or the like. In the present invention, the term "equivalent diameter" refers to a value converted to the diameter of a circle having the same cross-sectional area.

A method of cutting out the composite material cylinder shown in FIG. 3 will be explained. The composite sintered body block 33 obtained by hot pressing as described above, as shown in FIG. In the case where an intermediate bonding layer is included, the diamond sintered body layer 31 and the cemented carbide 32 are bonded via the intermediate bonding layer 34, as shown in FIG. 4b. Although the illustrated example shows a cylindrical composite sintered body block, it goes without saying that the composite sintered body block may be cylindrical or prismatic.

As shown in Fig. 5, these composite sintered blocks have an equivalent diameter of 3 in the coaxial direction with the composite sintered blocks.
A rod-shaped body having a cross section of 1 mm or less is cut by the electric discharge wire cutting method to obtain a composite material rod-shaped body having a hard head as shown in FIGS. 3a and 3b.

In this electric discharge wire cutting method, a high voltage is applied between the wire and the composite sintered block, and the wire is run under tension to cut the block. Please refer to No. 4103137.

Hereinafter, a specific manufacturing example of a cylindrical body of a composite sintered material having a hard sintered body at the head of the present invention will be described.

Manufacturing example 1 WC-12%Co with an outer diameter of 18 mm, an inner diameter of 14 mm, and a height of 15 mm.
Cemented carbide ring, outer diameter 14mm, height 12mm WC−
12%Co cemented carbide cylinder block, outer diameter 14mm, thickness 0.5mm WC-12%Co cemented carbide disc and grain size 0.5μ
A mixed powder was prepared, consisting of 85% diamond powder with a particle diameter of 0.5 μm or less and WC-15% Co cemented carbide powder with a particle size of 0.5 μm or less.

A superalloy cylindrical block is inserted into the inner diameter of the superalloy ring, and the mixed diamond powder is filled into a recess with a diameter of 14 mm and a depth of 3 mm formed by the inner surface of the cemented carbide ring and the top surface of the cemented carbide cylindrical block, and then processed. The mixed powder was pressed to a height of 1.5 μm, and after being covered with a cemented carbide disk, it was placed in an ultra-high pressure sintering device and heated under pressure.
Sintering was performed for 15 minutes at a temperature of 55 kb and 1370°C.
After cooling, the upper cemented carbide disk of the enclosure was removed by depressurization and removed by grinding, and a 1 mm thick sintered diamond layer was bonded to the top surface of the 12 mm high cemented carbide support and formed around it. A composite block was obtained in which the cemented carbide ring was also bonded to the support and to the sintered diamond layer.

As shown in Fig. 5, this composite block was mounted on an electric discharge wire cutting machine, and after cutting the electric discharge wire, a round bar with a diameter of 1 mm and a length of 13 mm was used to cut the support part from the axial direction of the composite block. WC−12%
A cylindrical body made of Co cemented carbide and having a 1 mm long sintered diamond layer fixedly formed at one end was obtained.

Manufacturing example 2 Outer diameter made of WC-12%Co cemented carbide
18mm, inner diameter 14mm, height 20mm ring, outer diameter 14
mm, 18 mm height cylindrical block, outer diameter 14 mm, thickness
0.5mm disk and 90 diamond powder with particle size of 3μm
Mixed powder consisting of % and remainder Co powder, particle size 3μm
High-pressure phase boron nitride (hereinafter referred to as cubic boron nitride)
60% powder (abbreviated as CBN) and the remainder (TiN−10
A mixed powder consisting of a powder having a composition of (wt% Al) was prepared.

After applying a solution of the CBN mixed powder in a solvent to a thickness of 50 μm on the top surface of a cemented carbide cylindrical block, the solvent was removed by heating, and the cemented carbide cylindrical block subjected to this treatment was made into a cemented carbide ring with an inner diameter of 50 μm. inserted into.

Next, after filling the recess formed by the inner surface of the cemented carbide ring and the top surface of the cemented carbide cylindrical block coated with the CBN mixed powder, the diamond mixed powder is press-molded to form a diamond with a thickness of 1.8 mm. After forming the mixed powder layer, it was covered with a cemented carbide disk.

Next, this container was placed in an ultra-high pressure sintering device and sintered at a pressure of 55kb and a temperature of 1400℃ for 10 minutes.
After cooling and reducing the pressure, the container was taken out. When the upper cemented carbide disk of the container is removed by grinding, a 1.2 mm thick sintered diamond layer is bonded to the top surface of the 18 mm high cemented carbide support via a 25 μm thick sintered CBN layer, and the surrounding A composite block was obtained in which the cemented carbide ring was bonded to the support and to the sintered diamond layer.

This composite block was mounted on a discharge wire cutter and a processing machine, and the support part was made of WC-12%Co cemented carbide using a round bar with a diameter of 2 mm and a length of 19.2 mm from the axial direction of the composite body. , at one end there is a sintered diamond layer 1.2 mm long and 25 μm thick.
A cylindrical body was obtained which was bonded through the sintered CBN interface layer.

Manufacturing example 3 (Mo ₇ , W ₃ ) Made of C-11%Co cemented carbide,
A cylindrical block with an outer diameter of 24 mm and a height of 25 mm with a circular recess of 20 mm in diameter and 3 mm in depth on the top surface, a WC-12% Co cemented carbide disk with an outer diameter of 20 mm and a thickness of 0.5 mm, and a grain size of 0.5 μ.
A mixed diamond powder was prepared, consisting of 80% diamond powder of m and the remainder WC-15% Co cemented carbide powder with a particle size of 0.5 μm or less.

This diamond mixed powder was filled into the recess on the upper surface of the cemented carbide cylindrical block and then pressurized to a height of 2.3 mm.
A layer of diamond mixed powder was formed. Next, this was covered with a cemented carbide disk, placed in an ultra-high pressure sintering device, and sintered at a pressure of 55 kb and a temperature of 1400°C for 15 minutes.

After sintering, the sealed container is taken out and the cemented carbide lid on the top surface is ground and removed to reveal a sintered diamond layer with a thickness of _1.5 mm in the circular recess on _the top surface. A composite block was obtained that was firmly bonded to the %Co alloy container.

This composite block was mounted on an electrical discharge wire cutting machine, and the supporting body part was (Mo ₇ , W ₃ ) C-11 with a round bar having a diameter of 2 mm and a length of 23.5 mm from the axial direction of the composite block. A cylindrical body made of %Co cemented carbide and having a 1.5 mm long sintered diamond layer fixedly formed on one end was obtained.

Manufacturing example 4 WC-12%Co with an outer diameter of 18 mm, an inner diameter of 14 mm, and a height of 15 mm.
Cemented carbide ring, outer diameter 14mm, height 12mm 96% by weight
Cylindrical block made of W-3wt%Ni-1wt%Cu alloy, WC-12%Co with outer diameter 14mm and thickness 0.5mm.
Cemented carbide disc and 85% CBN with grain size 3μm and the remainder
After mixing TiN _0.82 powder and Al powder at a weight ratio of 80:20, heat treatment was performed in a vacuum furnace at 1000℃ for 30 minutes, and the powder was ground to 0.3 μm and CBN was obtained.
A mixed powder was prepared.

A W alloy cylindrical block is inserted into the inner diameter of the cemented carbide ring, and the CBN mixed powder is filled into a recess with a diameter of 14 mm and a depth of 3 mm formed by the inner surface of the cemented carbide ring and the upper surface of the W alloy cylindrical block. Pressurize to height
A 1.7 mm CBN mixed powder layer was formed. Next, a cemented carbide disk is placed over the lid, and the entire cemented carbide container is placed in an ultra-high pressure sintering device, after which pressure is applied.
Sintering was performed at 50kb and 1250℃ for 20 minutes.

After sintering, take out the cemented carbide container and remove the WC on the top surface.
-12%CO When the cemented carbide lid is removed by polishing, the height is 12 mm.
A composite block was obtained in which a sintered CBN layer with a thickness of 1 mm was bonded to the upper surface of the W alloy support part, and a cemented carbide ring was bonded to the support body and the sintered CBN layer around the periphery.

This composite block was mounted on an electrical discharge wire cutting machine, and the supporting part was cut from the axial direction of the composite block using a round bar with a diameter of 1 mm and a length of 13 mm, which was 96% W - 3% Ni - 1% by weight. %
Made of Cu alloy, sintered with a length of 1 mm at one end.
A cylindrical body with a fixed CBN layer was obtained.

Manufacturing example 5 WC-12%Co with outer diameter 40mm, inner diameter 36mm, and height 40mm
Cemented carbide ring, outer diameter 36mm, height 34mm WC-12
%CO cemented carbide cylindrical block, outer diameter 36mm, thickness 0.5
mm WC-12%Co cemented carbide disk and grain size 3μm
CBN powder 60% by volume and remainder (TiN-10% by weight Al)
A CBN mixed powder consisting of powder with the following composition was prepared.

First, the CBN mixed powder was pressure-molded into a disk with a diameter of 36 mm and a thickness of 2.5 mm, and the inner diameter of the cemented carbide ring was molded from the bottom to the cemented carbide disk, CBN molded body, cemented carbide cylindrical block, and CBN molded body. , cemented carbide disks were stacked in this order, and the entire container was placed in an ultra-high pressure sintering device and sintered at a pressure of 40 kb and a temperature of 1200° C. for 20 minutes.

After sintering, when the block is taken out and the top and bottom cemented carbide lids are ground and removed, a sintered CBN layer with a diameter of 36 mm and a thickness of 1.5 mm is firmly formed on the top and bottom surfaces of the 34 mm high cemented carbide cylindrical block, and the surrounding area is made of cemented carbide. A composite block covered with an alloy ring was obtained.

Next, this composite block was mounted on an electric discharge wire cutting machine, and by electric discharge wire cutting, a diameter of 2.5 mm and a length of 37 mm were cut from the axial direction of the composite block.
A sintered CBN layer with a length of 1.5 mm was firmly formed on both ends of a round bar of 1.5 mm in length.

This round bar was further cut into two parts at the center in the length direction, resulting in a round bar with a diameter of 2.5 mm and a length of 18 mm.The support part was made of WC-12%Co cemented carbide and one end had a length of 1.5 mm.
A rod-shaped body was obtained in which a sintered CBN layer of mm thick was firmly formed.

In this specification, % is expressed in volume percent unless otherwise specified.

Effects of the Invention As explained above, the present invention consists of a hard sintered part made of diamond or high-pressure phase boron nitride and a supporting part joined to the hard sintered part. The present invention provides an elongated cylindrical body of composite sintered material having a diameter of 3 mm or less, which is characterized in that it is formed in the process of sintering a sintered part.

By using the composite sintered material cylindrical body of the present invention, a high-performance drill with excellent wear resistance and rigidity can be easily manufactured.

For example, FIG. 6 shows an example in which the composite sintered material cylindrical body 23 of the present invention is applied to a drill.

As shown in FIG. 6a, a hole 2 having approximately the same diameter as the cylindrical body of the composite sintered material is formed at the tip of the shank 25 of the drill.
Drill 6. One end of the supporting portion of the cylindrical composite sintered material 23 of the present invention is pushed into this hole 26 and fixed. At this time, brazing material may be dropped into the hole 26 and brazing may be performed.

As shown in FIG. 6a, the composite sintered material cylindrical body 23 fixed to the shank is processed with a blade,
A drill as shown in Figure b was obtained. A drill manufactured using the cylindrical body of the composite sintered material of the present invention does not include joints made by complicated electron beam welding, and has a strong and robust structure as a whole. Therefore,
It is possible to drill holes with high efficiency even in high-performance printed circuit boards such as glass epoxy boards.

A composite sintered material cylinder having a diameter of 2 mm and having a composite sintered material portion 21 having a thickness of 1 mm and a cemented carbide support 22 having a length of 14 mm was manufactured by the above-described method of the present invention. Using a drill with this composite sintered material cylindrical body fixed to a shank, a hole drilling test was performed on a glass epoxy printed circuit board.

For comparison, a composite sintered material cylindrical body in which the thickness of the composite sintered material part was 1 mm and the thickness of the cemented carbide support was 3 mm was manufactured using the same manufacturing method as in the present invention, and the cemented carbide support side was was made of cemented carbide with a diameter of 3 mm and a length of 9 mm, silver brazed and electron beam welded, and the same drilling test as above was conducted.

As a result of the drilling test, the joints of the comparative silver-brazed drill sample group fell off after 10 hits and were completely unusable.

In addition, some of the electron beam welded drill samples were able to drill more than 100,000 hits, but about one-third of them fell off after 1000 hits, making it impossible to guarantee the product. It was hot.

For the drill sample group of these comparative examples,
All of the drills of the present invention were confirmed to have a lifespan of 100,000 hits or more.

Furthermore, since the cylindrical body of the composite sintered material of the present invention has a circular cross section, no special processing is required when it is pushed into a hole drilled at the tip of the shank of a drill, as shown in Figure 6a. It can be installed without cutting, and the amount of cutting required for cutting the cutting edge is small, making it economical.

[Brief explanation of drawings]

FIG. 1 shows the structure of a conventional composite diamond sintered body. FIG. 2 shows a drill in which a conventional composite sintered body is fixed to the cutting edge. Figures 3a and 3b each show a composite sintered material cylinder according to an embodiment of the present invention. FIGS. 4a and 4b are perspective views of the composite sintered material block before cutting out the composite sintered material cylinder of the present invention, respectively. FIG. 5 shows the position where a small cross-section cylinder is cut out from the composite material block. Figure 6a shows the cylindrical body of the composite sintered material of the present invention fixed to the shank of a drill, and Figure 6b
shows the drill obtained in this way. (Main reference numbers), 11... Sintered diamond layer of conventional diamond tool, 12... Cemented carbide support, 13... Conventional composite sintered diamond chip, 15... Shank, 21... ...Hard sintered part of the composite sintered material cylindrical body of the present invention, 22... Supporting part, 23... Composite sintered material cylindrical body of the present invention, 2
4... Intermediate joint part, 31... Hard sintered part of composite material block, 32... Support part, 33... Composite material block, 34... Intermediate joint part.

Claims (1)

[Scope of Claims] 1. A hard sintered part containing 50% or more of either diamond powder or cubic boron nitride powder and having a circular cross section, and one end joined to this hard sintered part. In the composite sintered material cylinder, the composite sintered material cylinder has an average particle size of 10 μm.
A first material layer containing 50% or more of either diamond powder or cubic boron nitride powder or both of the following, and a carbide of a group 4a, 5a, or 6a element of the periodic table or a mutual solid solution carbide of these elements. A second block consisting of cemented carbide blocks bonded with iron group metals.
A composite material with a large cross-sectional area in which the hard sintered part 21 and the support part 22 are joined by hot pressing at high temperature and high pressure after storing the material layers in the same hot press container in a stacked manner in the pressing direction. It is made by manufacturing a sintered body block and cutting the obtained composite sintered body block in the lamination direction of the above materials by electric discharge machining, and the axial length of the hard sintered part 21 is The axial length of the supporting part 22 is at least 5 times the axial length of the hard sintered part 21, and the cylindrical body of the composite sintered material has a diameter of 3 mm or less and a total length of 0.3 to 2 mm. A cylindrical body of composite sintered material having a diameter of 10 mm or more. 2 The hard sintered part 21 and the support part 22 have a thickness
The composite sintered material cylindrical body according to claim 1, which is bonded via an intermediate bonding layer of 0.5 mm or less.