JPH0742488B2 - Method for manufacturing rod-shaped body of composite sintered material - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing a composite rod having a rigid head, preferably a cylinder of small diameter.

More specifically, the present invention provides a small head including a hard head such as a diamond sintered body or a high-pressure phase boron nitride sintered body, and a support portion integrally formed with the head and made of, for example, cemented carbide. The present invention relates to a method for manufacturing a composite material rod-shaped body having a cross section.

The composite material rod-shaped body obtained by the manufacturing method of the present invention can be used as a material for a high-performance small-diameter drill or a head portion for a dot printer.

2. Description of the Related Art Drills made of cemented carbide are widely used for drilling metal and non-metal materials. In particular, cemented carbide drills with a diameter of around 1 mm are used for drilling printed circuit boards, which are in rapid demand in recent years.

Although various materials are used for a printed circuit board, a mainly used resin is a reinforced resin obtained by impregnating glass fiber with an epoxy resin, which is generally called a glass epoxy substrate.

Drilling of such a printed circuit board is normally performed with a high-rigidity drill at a rotation speed of 50,000 to 60,000 rpm. However, the glass fiber contained in the circuit board causes the cemented carbide tool to wear very quickly, which is common. With 3000 to 5000 hits (hits are the number of holes drilled), a carbide drill reaches its end of life. Such a drilling machine is equipped with an automatic tool changer, and the drill that has reached the end of its life is automatically replaced, but in order to improve production efficiency, the time for this automatic tool change is also a problem and There is a strong demand to extend the number of tool changes, that is, to reduce the change time.

Considering the characteristics of printed circuit boards, there is a strong demand for further improvement in heat resistance and other functions, and such board materials can be actually manufactured, but in general, such high-performance materials are difficult to manufacture. Due to the grinding, the life of conventional cemented carbide drills becomes extremely short, and the actual situation is that this substrate material cannot be put to practical use.

Furthermore, it is desired to increase the rotation speed of the drill to make even more efficient drilling for ordinary glass-epoxy substrates, but this is also the case with conventional cemented carbide drills, where the life is sharply increased with increasing cutting speed. Therefore, the efficiency cannot be improved from this point.

On the other hand, sintered diamond tools, whose usage has been increasing rapidly in recent years, have dramatically higher hardness than cemented carbide tools and are excellent in wear resistance, and are extremely useful in cutting the above reinforced resin. Demonstrate high performance.

However, as shown in FIG. 1, this sintered diamond tool comprises a composite sintered body 13 in which a sintered diamond layer 11 is bonded to a cemented carbide support portion 12. When making a drill using this composite sintered body 13, as shown in FIG. 2, the composite sintered body 13 must be fixed to the tip of the shank 15 by some method.

However, the diameter of the tip of this drill is about 1 mm, and with such a small diameter, unless it has a very strong joining strength with the shank 15, it will come off from the joining portion 16 in the cutting edge grinding process after joining, which is good. I can't manufacture a drill. In particular, sintered diamond is difficult to grind, has a high grinding resistance, and is insufficient in strength at the level of ordinary silver brazing. Electron beam welding can be considered as a joining method with high joining strength, but if electron beam welding is implemented, the manufacturing process of the drill will be complicated and the cost will be high, and it will respond to the recent rapid increase in demand for high-performance drills. could not.

In order to strengthen the connection with the shank 15 and improve the machinability of the drill itself, the entire tip of the drill is cemented carbide,
It is ideal to have a hard sintered body such as diamond on its head. For that purpose, an elongated composite rod-shaped body having a hard head and made of cemented carbide is required. However, in the prior art, it was not possible to manufacture a composite sintered body having such a small cross section and a large axial length.

That is, when manufacturing a product having a large axial length with respect to the cross-sectional area, even if the powder material is pressed in the axial direction and hot pressed, the pressure loss due to the powder material layer is large, and it is necessary for the central portion in the axial direction. This is because no pressure is applied and a strong sintered body cannot be obtained. If this is further pressed in the axial direction and hot pressed with high pressure, the pressure distribution inside the container of the hot press becomes extremely irregular, so it is easy to cause buckling, deformation such as bending, and has sufficient dimensional accuracy. A sintered body cannot be obtained.

Therefore, in the hot pressing of the elongated sintered material, the sintered material is laid out so that the axial direction of the sintered material is perpendicular to the pressing direction. In such a method, even when hot pressing was performed on the elongated composite material, the pressure in the direction perpendicular to the boundary surface between different material layers was small, and sufficient strength bonding between the material layers could not be obtained.

OBJECT OF THE INVENTION The present invention has an object of solving the above-mentioned problems of the prior art, and more specifically, has a head of a hard sintered body, and the head and the supporting portion are integrally formed by a sintering process. An object of the present invention is to provide a method for producing a joined rod-shaped body having a small cross-section and an elongated shape, preferably a columnar body having a small diameter, thereby making it possible to easily and inexpensively produce a drill having excellent wear resistance and rigidity. And

A further object of the present invention is to provide a long-life drill at a low price, which enables easy and high-performance drilling of a difficult-to-cut substrate such as a glass epoxy substrate.

Further, an object of the present invention is to provide a method for manufacturing a rod-shaped composite material having a small cross section as an intermediate product capable of easily manufacturing an elongated member which requires a hard tip portion such as a head of a dot printer. is there.

Configuration of the Invention The present inventors manufacture a composite sintered body block by hot pressing a composite material block having a large cross-sectional area, and cut it into a small-diameter columnar body by discharge wire cutting to make it small and elongated. It has succeeded in providing a rod-shaped body of a composite sintered material having a hard head.

That is, according to the present invention, the first for hard sintered bodies containing 50% or more of diamond powder or high-pressure phase boron nitride powder.
And a second material layer to be joined to the hard sintered body of the first material in the sintering process of the first material layer are mounted in the same hot press container in the pressing direction. Then, 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 side to obtain a hard sintered body having a predetermined thickness. A composite material block having a body layer is formed, the composite material block is cut in the material layer thickness direction by a discharge wire cutting method, and the thickness is 1/6 or less with respect to the material layer thickness direction thickness of the composite material block. Also provided is a method for producing an elongated composite material rod-shaped body, which comprises cutting out two or more elongated composite material rod-shaped bodies each having a hard sintered body having a cross section of an equivalent diameter of 3 mm or less at its head.

In hot pressing the composite material to sinter, according to the invention, the axial length of the composite material block is the equivalent diameter D.
It should be 3 times, preferably 2 times or less than E. When hot pressing a composite material block having an axial length of more than three times, the pressure distribution in the composite material block becomes irregular and bending occurs. In the present specification, the equivalent diameter means a value converted into the diameter of a circle having the same cross-sectional area.

The average particle size of the diamond powder or the high-pressure phase boron nitride powder is preferably 30 μm or less, and a diamond or high-pressure phase boron nitride sintered body having a particle size within this range can provide a composite sintered material having excellent wear resistance and rigidity.

However, when producing chips for cutting tools using diamond powder, if diamond powder with an average particle size of more than 10 μm is used as a raw material, the cutting edge of the cutting tool obtained by processing this composite sintered material cylindrical body Can not be formed sharply, and as a result, high performance cannot be achieved.
It is preferably composed of diamond or less m or high-pressure phase boron nitride.

According to a preferred feature of the invention, the axial length of the hard sintered part is 0.3-2 mm.

When the first material layer contains diamond powder as a main component, a diamond powder alone or a mixed powder containing 70% or more of diamond and the remainder being a binder powder containing Fe, Co or Ni as a main component is added. is there. A preferred example of the first material layer of diamond powder is a mixed powder of 70% or more diamond powder and WC-5 to 15% Co powder.

When powder of diamond alone is used as the material of the first material layer, the binder component in the second material layer dissolves in the powder of the first material layer when the first material layer is sintered. Sintering achieves sintering of the first layer of material.

When the first material layer is a high-pressure phase boron nitride-based material, high-pressure phase boron nitride powder alone or 50% or more of high-pressure phase boron nitride
There are those obtained by adding carbides, nitrides, carbonitrides, and aluminum and / or silicon of group a, 5a, and 6a elements as a binder and sintering them. Here, the high-pressure phase boron nitride is
It means cubic boron nitride and wurtzite boron nitride.

The second material layer forming the support portion is a so-called cemented carbide, that is, carbides or nitrides of elements of groups 4a5a and 6a of the periodic table,
It is a sintered alloy or cermet in which a carbonitride, a boride, a silicide or a mutual solid solution carbide thereof is bound by an iron group metal of Fe, Co or Ni, or a powder raw material thereof. As an example of cermet, (Mo, w) C carbide is Ni or Co.
There is one that is bound by the iron group metal.

Still another second material layer is a so-called heavy metal sintered alloy containing 80 to 98% by weight of W and the balance of Ni-Fe or Ni-Fe-Cu, or a powder raw material thereof.

The second material layer may be a solid cemented carbide that has already been sintered, or a powder of cemented carbide material. However, it is preferable to use a sintered cemented carbide block in consideration of handling convenience in hot pressing and ease of application of high pressure.

One of the important features of the method for producing a rod-shaped composite material according to the present invention is that the hard sintered portion and the support portion are joined in the sintering process of the hard sintered portion. Therefore, the components of the second material layer are
It is necessary that the material is a material that can be bonded to the first material layer during the sintering process of the first material layer.

However, such combinations are endless within the range of the components of the hard sintered portion and the support portion described above, and in the sintering process of diamond or high pressure phase boron nitride by hot pressing under high pressure and high temperature, Thus, the ferrous metal binder in the support member is infiltrated, so that the hard sintered portion and the support portion are easily joined. Therefore, it goes without saying that those skilled in the art can select the components of the hard sintered portion and the support portion as needed within the above-described range. Further, the high-pressure phase boron nitride powder can be sintered alone as described above, and the connection with the supporting portion is achieved during the sintering process.

Further, according to one aspect of the present invention, an intermediate bonding layer having a thickness of 0.5 mm or less is arranged between the first material layer and the second material layer, and hot pressing is performed.

As the intermediate bonding layer, a high-pressure phase boron nitride of less than 70% and the balance being one of Ti, Zr, and Hf carbides, nitrides, carbonitrides, or borides of Group 4a of the Periodic Table, or a mixture thereof or mutual mutual. It is preferable to use a solid solution compound as a main component and a material containing Al and / or Si in an amount of 0.1% by weight or more.

Furthermore, according to one aspect of the present invention, the second material layer, that is, the support portion, is composed of two or more material layers in the axial direction. As an example of such a case, the support side layer of the second material layer is WC-Co, and the hard head side layer is a (Mo, w) C carbide bonded with an iron group metal of Ni or Co. Some are made of cermet.

Further, the first material layer is arranged above and below the second material layer, hot press is performed, and the obtained composite material block is cut into a rod-shaped body having a small cross section in the coaxial direction, and hard heads are provided at both upper and lower ends. It is also possible to manufacture a rod-shaped body having the same.

Next, the shape of the composite sintered material rod-shaped body obtained by the manufacturing method of the present invention will be described.

3 (a) and 3 (b) attached herewith are perspective views of examples of composite material rods obtained by the production method of the present invention.

The composite sintered material rod-shaped body shown in FIG. 3 (a) has a cylindrical shape as a whole, and the hard sintered portion 21 is directly joined to the support portion 22.

On the other hand, in the composite sintered material rod-shaped body shown in FIG. 3 (b), the hard sintered portion 21 and the support portion 22 are joined via the intermediate joining layer 24.

However, it goes without saying that the composite material rod-shaped body obtained by the manufacturing method of the present invention is not limited to the cylindrical shape and may be a prismatic shape.

The composite sintered material rod-shaped body obtained by the method of the present invention has a cross section with an equivalent diameter of 3 mm or less. A composite material rod having a cross section with an equivalent diameter of more than 3 mm is not suitable as a material for a drilling hole for a printed circuit board, and even if it is ground and used, the grinding allowance is large and it is uneconomical.

The axial length of the hard sintered part 21 is in the range of 0.3 to 2 mm. If it is less than 0.3 mm, improvement in machinability cannot be expected when used as a drill tip, and if it exceeds 2 mm, a large amount of expensive diamond powder or the like is used, which is uneconomical. Further, a rod-shaped body having a diameter of more than 3 mm can be manufactured by a conventional method other than the method of the present invention.

Further, the length of the support portion 22 needs to be 5 times or more the length of the hard sintered portion 21. When manufacturing a drill, it is necessary to secure the face length of the drill and bury the end in the shank, so that a supporting portion having a length of 5 times or more is required as described above.

Next, FIG. 4 shows an example in which the composite material rod-like body obtained by the manufacturing method of the present invention is applied to a drill.

As shown in FIG. 4 (a), a hole 26 having substantially the same diameter as that of the composite material rod-shaped body (cylindrical body in the illustrated example) is formed at the tip of the shank 25 of the drill. The end of the composite material rod-shaped body 23 on the support portion side is pushed into this hole 26 and fixed. At this time, a brazing material may be dropped into the holes 26 and then brazed.

As shown in FIG. 4 (a), the composite material rod 23 fixed to the shank was bladed to obtain a drill as shown in FIG. 4 (b).

The method of cutting out the composite material rod-shaped body shown in FIGS. 3 and 4 will be described. The composite sintered body block 33 obtained by hot pressing as described above has a thickness as shown in FIG. 5 (a). It is composed of a 1 mm diamond sintered body layer 31 and a cemented carbide layer 32 bonded to the diamond sintered body layer 31, and the fifth layer in the case of including an intermediate bonding layer.
Diamond sintered body layer 31 and cemented carbide layer as shown in FIG.
It is joined to 32 with an intermediate joining layer. In the illustrated example, a cylindrical composite sintered body block is shown, but it goes without saying that the composite sintered body block may be a cylindrical body or a prismatic body.

As shown in FIG. 6, these composite sintered body blocks were cut into a rod-shaped body having a cross-section with an equivalent diameter of 3 mm or less in the direction coaxial with the composite sintered body block by a discharge wire cutting method to form a third rod.
A composite rod having a hard head as shown in FIGS. (A) and (b) is cut.

In this electric discharge wire cutting method, a high voltage is applied between the wire and the composite sintered body block, and the wire is run in a tensioned state to cut the block. For details, see U.S. Pat.No. 4,103,137. I want to be done.

Hereinafter, the production method of the present invention will be described with reference to examples. However, these examples are merely examples of the present invention and do not limit the scope of the present invention in any way.

In the present specification,% is shown as a volume percentage unless otherwise specified.

Example 1 WC-12% Co cemented carbide ring of outer diameter 18 mm, inner diameter 14 mm, height 15 mm, WC-12% Co cemented carbide column block of outer diameter 14 mm, height 12 mm, outer diameter 14 mm, thickness Prepared a mixed powder consisting of a 0.5 mm thick WC-12% Co cemented carbide disc, 85% diamond powder with a particle size of 0.5 μm, and the balance WC-15% Co cemented carbide powder with a particle size of 0.5 μm or less. .

Insert the superalloy cylinder block into the inner diameter of the superalloy ring, and add the mixed diamond powder to the recess of 14mm in diameter and 3mm in depth formed by the inner surface of the superhard alloy ring and the upper surface of the superhard alloy column block, and then add. Press to raise the height of the mixed powder to 1.5 μm
After covering with a cemented carbide disc, it was placed in an ultra-high pressure sintering apparatus and sintered under conditions of a pressure of 55 kb and a temperature of 1370 ° C. for 15 minutes. After cooling, decompressing and removing the upper cemented carbide disk of the enclosed container removed by grinding, a sintered diamond layer with a thickness of 1 mm was formed on the upper surface of the cemented carbide support with a height of 12 mm and formed around it. A composite block was obtained in which the cemented carbide ring was also bonded to the support and the sintered diamond layer.

As shown in FIG. 6, this composite block is mounted on an electric discharge wire cutting machine, and the electric discharge wire is cut. A support bar is a round bar with a diameter of 1 mm and a length of 13 mm from the axial direction of the composite block. A rod-shaped body made of WC-12% Co cemented carbide and having a 1 mm long sintered diamond layer fixedly formed on one end thereof was obtained.

Example 2 Outer diameter 18 mm and inner diameter made of WC-12% Co cemented carbide
14mm, height 20mm ring, outer diameter 14mm, height 18mm cylinder block, outer diameter 14mm, thickness 0.5mm disc, grain size 3μ
m 90% diamond powder and the balance Co powder, 3% high-pressure phase boron nitride powder (hereinafter cubic boron nitride is abbreviated as CBN) powder 60% and the balance (TiN-10% by weight) A mixed powder composed of powder having a composition of Al) was prepared.

The CBN mixed powder dissolved in a solvent is applied to the upper surface of a cemented carbide column block to a thickness of 50 μm, and then the solvent is removed by heating, and the cemented carbide column block that has undergone this treatment is processed into a cemented carbide ring inner diameter. Inserted in.

Next, after filling the diamond mixed powder in the recess formed by the inner surface of the cemented carbide ring and the upper surface of the cemented carbide columnar block coated with the CBN mixed powder, pressure molding to a thickness of 1.
After forming an 8 mm diamond mixed powder layer, the lid was covered with a cemented carbide disc.

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

This composite block was mounted on a discharge wire cutting and processing machine, and by discharge wire cutting, it was a round bar with a diameter of 2 mm and a length of 19.2 mm from the axial direction of the composite, and the support part was made of WC-12% Co cemented carbide. A rod-shaped body was obtained in which a sintered diamond layer having a length of 1.2 mm was joined and formed at one end thereof through a sintered CBN interface layer having a thickness of 25 μm.

Example 3 (Mo ₇ , W ₃ ) C-11% Co cemented carbide with a diameter of 2
Cylinder block with an outer diameter of 24 mm and a height of 25 mm, which has a circular recess of 0 mm and a depth of 3 mm, an outer diameter of 20 mm and a thickness of 0.5 mm, made of WC-12% Co cemented carbide disc and a diamond powder with a particle size of 0.5 μm. A diamond mixed powder consisting of WC-15% Co cemented carbide powder with a particle size of 80% and the remainder of 0.5 μm or less was prepared.

This diamond mixed powder was filled in the recess in the upper surface of the cemented carbide column block and then pressed to form a diamond mixed powder layer having a height of 2.3 mm. Next, after covering with a cemented carbide disc on this, place it in the ultra-high pressure sintering equipment, pressure 55 kb, temperature
Sintered at 1400 ° C for 15 minutes.

After sintering, the enclosure was taken out and the cemented carbide lid on the upper surface was ground and removed, and there was a sintered diamond layer with a thickness of 1.5 mm in the circular recess on the upper surface, which was around (Mo ₇ , W ₃ ) C-11. A composite block was obtained that was firmly bonded to the% Co alloy container.

This composite block is mounted on an electric discharge wire cutting machine, and by electric discharge wire cutting, the support part is a round bar with a diameter of 2 mm and a length of 23.5 mm from the axial direction of the composite block.
o ₇ , W ₃ ) C-11% Co cemented carbide, with a length at one end
A rod-shaped body on which a 1.5 mm sintered diamond layer was firmly formed was obtained.

Example 4 WC-12% Co cemented carbide ring having an outer diameter of 18 mm, an inner diameter of 14 mm, and a height of 15 mm, an outer diameter of 14 mm and a height of 12 mm, 96 wt% W-3 wt% Ni-
Cylindrical block made of 1 wt% Cu alloy, outer diameter 14 mm, thickness
0.5mm WC-12% Co cemented carbide disc and 3μm grain CBN 85%
CBN mixed powder consisting of the following: TiN _0.82 powder and Al powder were mixed at a weight ratio of 80:20, heated at 1000 ° C for 30 minutes in a vacuum furnace, and then ground to 0.3 μm. I prepared.

Inserting the W alloy columnar block into the inner diameter of the cemented carbide ring, filling the CBN mixed powder into a recess of 14 mm in diameter and 3 mm in depth formed by the inner surface of the cemented carbide ring and the upper surface of the W alloy columnar block, A pressure was applied to form a CBN mixed powder layer having a height of 1.7 mm. Then, cover with a cemented carbide disc and cover, place the entire cemented carbide container in the ultra-high pressure sintering device, and then apply a pressure of 50.
Sintering was performed for 20 minutes at kb and a temperature of 1250 ° C.

After sintering, take out the cemented carbide container and grind off the WC-12% Co cemented carbide lid on the top surface to form a 1 mm thick sintered CBN layer on the top surface of the 12 mm high W alloy support. Then, a composite block was obtained in which a cemented carbide ring was bonded to the support and the sintered CBN layer around it.

This composite block was mounted on an electric discharge wire cutting machine, and by discharge wire cutting, it was a round bar with a diameter of 1 mm and a length of 13 mm from the axial direction of the composite block.
A rod-shaped body made of a W-3 wt% Ni-1 wt% Cu alloy and having a 1 mm long sintered CBN fixedly formed at one end thereof was obtained.

Example 5 WC-12% Co cemented carbide ring with outer diameter 40 mm, inner diameter 36 mm, height 40 mm, WC-12% Co cemented carbide column block with outer diameter 36 mm, height 34 mm, outer diameter 36 mm, thickness 0.5 A WC-12% Co cemented carbide disc having a diameter of 3 mm, a CBN powder having a composition of 60% by volume of a CBN powder having a particle diameter of 3 μm and a balance (TiN-10 wt% Al) was prepared.

First, the CBN mixed powder is pressure-molded into a disc having a diameter of 36 mm and a thickness of 2.5 mm, and the cemented carbide ring, the CBN molded body, the cemented carbide column block, and the CBN molded body are inserted into the inner diameter of the cemented carbide ring from the bottom. Then, the cemented carbide discs were laminated in this order, and the entire set container was placed in an ultrahigh pressure sintering apparatus and sintered at a pressure of 40 kb and a temperature of 1200 ° C. for 20 minutes.

After taking out after sintering and grinding and removing the upper and lower cemented carbide lids, a sintered CBN layer with a diameter of 36 mm and a thickness of 1.5 mm is fixedly formed on the upper and lower surfaces of the cemented carbide column block with a height of 34 mm. 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 a discharge wire cutting, from the axial direction of the composite block, a 2.5 mm diameter and 37 mm long round bar was used to form a sintered CBN layer of 1.5 mm length at both ends. Was adhered and formed.

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

[Brief description of drawings]

FIG. 1 shows the structure of a prior art composite diamond sintered body. FIG. 2 shows a drill in which a composite sintered body of the prior art is fixed to the cutting edge. 3 (a) and 3 (b) each show an example of a composite sintered material rod-shaped body manufactured by the method of the present invention. FIG. 4 (a) illustrates a method of making a drill using the composite material rod obtained by the method of the present invention, and FIG. 4 (b) shows the drill. FIG. 5 (a) shows an example of a composite material block obtained according to the method of the present invention, and FIG. 5 (b) shows an example of a composite material block having an intermediate joint portion. FIG. 6 shows a position where a rod-shaped body is cut out from a composite material block according to the present invention. (Main reference number) 11 …… Sintered diamond layer of conventional diamond tool,
12 …… Cemented Carbide Support, 13 …… Conventional Composite Sintered Diamond Tip, 15 …… Shank, 21 …… Hard Sintered Part of Composite Sintered Rod by the Method of the Present Invention, 22 …… Supporting part, 23 ... Composite sintered material rod-shaped body of the present invention, 24 ... Intermediate joining part, 31 ... Hard sintering part of composite material block, 32 ... Supporting part, 33 ... Composite material block, 34 ... ... intermediate joints,

Claims (2)

[Claims] 1. A layer of a first material for a hard sintered body containing 50% or more of diamond powder or high-pressure phase boron nitride powder having an average particle size of 10 μm or less, and a periodic table 4a, 5a or
The second material layer made of cemented carbide in which the carbides of 6a group elements or their mutual solid solution carbides are bound by an iron group metal is placed in the same hot press container in the pressurizing direction and stacked under high temperature and high pressure. Hot-pressing with to sinter the layer of the first material, and in the process of sintering the layer of the first material, the hard sintered body of the first material into a cemented carbide layer obtained from the second material. A composite material block having a layer of a hard sintered body having a predetermined thickness is formed by joining, and the obtained composite material block is cut in the material layer thickness direction by a discharge wire cutting method to form a composite material block material layer. Elongated composite material characterized in that two or more elongated composite rod-shaped bodies each having a hard sintered body on the head having a cross section with an equivalent diameter of 1/6 or less and 3 mm or less with respect to the thickness direction are cut out. Material A method for manufacturing a rod-shaped body. 2. The method according to claim 1, wherein an intermediate bonding layer having a thickness of 0.5 mm or less is arranged between the first material layer and the second material layer and hot pressing is performed. .