CN104278953A - Polycrystalline diamond composite tooth, preparation method and down-hole drill bit - Google Patents

Abstract

The invention discloses a polycrystalline diamond composite tooth, a preparation method and a down-the-hole drill bit. The polycrystalline diamond composite tooth includes a cemented carbide substrate and a polycrystalline diamond layer. An impact-resistant layer is provided, and the impact-resistant layer is composed of the following components in mass percentage: 75%-80% of diamond, 10%-15% of WC, and the balance is adhesive. The polycrystalline diamond composite tooth of the present invention is provided with an impact-resistant layer between the cemented carbide substrate and the polycrystalline diamond layer, and the impact-resistant layer is composed of diamond, WC and adhesive, and the impact-resistant layer improves The bonding force between the matrix and the polycrystalline diamond layer effectively reduces the concentration of tensile stress, improves the impact toughness of the polycrystalline diamond composite tooth, and thus improves the quality of the polycrystalline diamond composite tooth and prolongs the service life.

Description

A kind of polycrystalline diamond composite tooth, preparation method and down-the-hole drill bit

technical field

The invention belongs to the technical field of drilling equipment, specifically relates to a polycrystalline diamond composite tooth and a preparation method thereof, and also relates to a down-the-hole drill using the polycrystalline diamond composite tooth.

Background technique

The down-the-hole bit is the key component in the down-the-hole rock drilling project. It is used in open-pit and underground mines, quarries, hydropower projects, well drilling, mineral exploration, rock mass cable anchor hole drilling, geothermal excavation, and subway engineering excavation. , Side pile support and other construction sites are widely used; at the same time, it is also one of the main consumable parts. According to statistics, in the cost of rock drilling, the cost of drill bits accounts for more than 20%. At present, the main products on the market are down-the-hole drills inlaid with cemented carbide column teeth, which are mostly made of cemented carbide ball teeth, conical teeth, parabolic teeth, etc. embedded in the front part of the steel substrate. This kind of down-the-hole drill bit can meet the engineering needs in medium hardness and soft rock formations, but when encountering hard rock formations (such as granite), the cemented carbide wears seriously, the service life of the drill bit is short, and it needs to be replaced frequently, which is inefficient. It not only affects the progress of the project, but also causes a lot of waste of manpower, material resources and raw materials. In response to the above problems, the polycrystalline diamond composite tooth down-the-hole bit has been developed.

The polycrystalline diamond composite tooth down-the-hole drill adopts polycrystalline diamond composite tooth instead of the traditional carbide column tooth head. Polycrystalline diamond composite teeth are sintered by artificial diamond powder and cemented carbide substrate (conical, spherical, wedge-shaped, parabolic, etc.) crystal diamond layer. Compared with the cemented carbide column tooth head, the polycrystalline diamond composite tooth has excellent mechanical properties such as high strength and high wear resistance, and has been widely used in various fields such as drilling and mining. However, due to the difference in performance parameters such as thermal expansion coefficient and elastic modulus between the cemented carbide substrate and the diamond layer, the internal residual stress of the sintered polycrystalline diamond composite tooth is relatively large, which weakens the bonding force between the cemented carbide substrate and the diamond layer. , resulting in poor impact toughness, prone to abnormal damage such as cracking and delamination, which seriously affects the quality of polycrystalline diamond composite teeth, thereby affecting the performance of polycrystalline diamond composite teeth down-the-hole drill bits.

Contents of the invention

The purpose of the present invention is to provide a polycrystalline diamond composite tooth, which solves the problems of poor bonding force between the cemented carbide matrix and the diamond layer of the existing polycrystalline diamond composite tooth and poor impact toughness of the polycrystalline diamond composite tooth.

The second object of the present invention is to provide a method for preparing polycrystalline diamond composite teeth.

The third object of the present invention is to provide a down-the-hole drill using the polycrystalline diamond composite teeth.

In order to achieve the above objectives, the technical solution adopted in the present invention is: a polycrystalline diamond composite tooth, including a cemented carbide substrate and a polycrystalline diamond layer, and an impact-resistant tooth is provided between the cemented carbide substrate and the polycrystalline diamond layer. The impact-resistant layer is composed of the following components in mass percentage: 75%-80% of diamond, 10%-15% of WC, and the balance is adhesive.

The binders are Co, Ni and TiC.

The impact-resistant layer is composed of the following components in mass percentage: 75%-80% of diamond, 10%-15% of WC, 3%-10% of Co, 1%-4% of Ni, and 1%-3% of TiC.

The mass ratio of the impact-resistant layer to the polycrystalline diamond layer is 1:2-5.

The cemented carbide substrate is WC-Co alloy.

The cemented carbide matrix is composed of the following components in mass percentage: Co 6%-10%, WC 90%-94%.

The grain size of the WC is 2.5-5.0 μm.

The polycrystalline diamond layer is composed of the following components by mass percentage: 40% to 50% of diamonds with a particle size of 50 to 60 μm, 30% to 40% of diamonds with a particle size of 30 to 40 μm, and 5% of diamonds with a particle size of 10 to 20 μm ~20%, Co4%~10%.

The cemented carbide substrate has a conical, spherical, wedge or parabolic structure.

The surface of the cemented carbide substrate is provided with a concave spherical surface. The number of the concave spherical surfaces is an even number. The concave spherical surfaces are symmetrically distributed on the surface of the cemented carbide substrate. The central axis of the concave spherical surface is perpendicular to the tangent direction of the surface of the cemented carbide substrate.

A method for preparing the above-mentioned polycrystalline diamond composite tooth, comprising the following steps:

1) Take diamond micropowder, WC powder and adhesive to make impact-resistant layer powder, set aside;

2) Assemble and compact the cemented carbide substrate, impact-resistant layer powder, and polycrystalline diamond layer powder in sequence to obtain an assembly;

3) Place the assembly obtained in step 2) in the pyrophyllite synthetic block, and put in the conductive steel ring to form a synthetic mold;

4) Place the synthetic mold obtained in step 3) in a six-sided top press for synthesis, cool down, release the pressure, and take it out.

In step 1), the binder is Co, Ni and TiC.

In step 1), the particle size of the diamond powder is 20-50 μm, the grain size of the WC powder is 2.5-5.0 μm, the particle size of the Co powder is 5-20 μm, the particle size of the Ni powder is 1.0-10 μm, and the particle size of the TiC powder is 1.0 to 10 μm.

The preparation method of the impact-resistant layer powder is as follows: after ball milling diamond micropowder, WC powder and binder for 8-10 hours, it is stored in a vacuum drying oven at 100-150° C. for later use.

The polycrystalline diamond layer powder is composed of the following components by mass percentage: 40%-50% of diamond powder with a particle size of 50-60 μm, 30%-40% of diamond powder with a particle size of 30-40 μm, and 10-20 μm 5% to 20% of diamond fine powder, 4% to 10% of Co powder with a particle size of 5 to 20 μm.

The preparation method of the polycrystalline diamond layer powder is as follows: after ball milling the diamond micropowder and Co powder for 10-15 hours, the powder is placed in a vacuum drying oven and stored at 100-120° C. for later use.

In step 4), the synthesis pressure is 5.2-6.0 GPa, the temperature is 1450-1550° C., and the synthesis time is 2-5 minutes.

In step 4), the cooling time is 5-10 minutes.

A down-the-hole drill bit using the above-mentioned polycrystalline diamond composite tooth, comprising a down-the-hole drill bit base body, the down-the-hole drill bit base body is provided with at least one tooth hole, and the polycrystalline diamond composite tooth is embedded in the tooth hole .

The base body of the down-the-hole drill bit is prepared sequentially through base forging, base normalizing, base machining, base secondary heat treatment, and base gear hole processing.

The polycrystalline diamond composite tooth of the present invention is provided with an impact-resistant layer between the cemented carbide substrate and the polycrystalline diamond layer, and the impact-resistant layer is composed of diamond, WC and adhesive, and the impact-resistant layer improves the The bonding force between the matrix and the polycrystalline diamond layer effectively reduces the concentration of tensile stress, improves the impact toughness of the polycrystalline diamond composite tooth, and thus improves the quality of the polycrystalline diamond composite tooth and prolongs the service life.

In the polycrystalline diamond composite tooth of the present invention, the impact-resistant layer uses Co, Ni, TiC mixed powder as the adhesive, which has strong adhesive force, not only makes the cemented carbide substrate and the polycrystalline diamond layer have stronger adhesion At the same time, the impact toughness of polycrystalline diamond composite teeth is improved. The polycrystalline diamond layer adopts diamond mixed powder with different particle sizes, which improves the overall hardness and wear resistance of the polycrystalline diamond layer, and further improves the impact toughness of the polycrystalline diamond composite tooth.

The preparation method of the polycrystalline diamond composite tooth of the present invention is to assemble the cemented carbide substrate, the impact-resistant layer powder, and the polycrystalline diamond layer powder sequentially and then synthesize them at high temperature and high pressure. An impact-resistant layer is set between the diamond layers, which increases the bonding force between the cemented carbide substrate and the polycrystalline diamond layer, effectively reduces the concentration of tensile stress, improves the impact toughness of the polycrystalline diamond composite tooth, and further improves the polycrystalline diamond. The quality of the diamond composite tooth prolongs the service life; the method is one-step synthesis, the process is simple, the operation is convenient, and it is suitable for large-scale industrial production.

The down-the-hole drill bit of the present invention is obtained by inlaying the above-mentioned polycrystalline diamond composite tooth in the tooth hole of the down-the-hole drill bit matrix. The polycrystalline diamond composite tooth has good impact resistance toughness and hardness, so that the down-the-hole drill bit has a higher The wear resistance and impact resistance improve the quality of the down-the-hole bit, prolong the service life, improve the working efficiency of down-the-hole rock drilling, and reduce the production cost.

Description of drawings

Fig. 1 is the structural representation of the polycrystalline diamond composite tooth of embodiment 1;

Fig. 2 is the structural representation of the polycrystalline diamond composite tooth of embodiment 2;

Fig. 3 is the top view of cemented carbide substrate in Fig. 2;

Fig. 4 is a structural schematic diagram of the down-the-hole drill bit of embodiment 2.

Detailed ways

The present invention will be further described below in combination with specific embodiments.

Example 1

The polycrystalline diamond composite tooth of this embodiment comprises a cemented carbide substrate and a polycrystalline diamond layer, and an impact-resistant layer is arranged between the cemented carbide substrate and the polycrystalline diamond layer, and the impact-resistant layer consists of the following mass percentage Component composition: Diamond 75%, WC15%, Co6%, Ni2%, TiC2%. The cemented carbide matrix is composed of the following components in mass percentage: 10% Co, 90% WC; wherein the grain size of WC is 2.5-5.0 μm. The mass ratio of the impact-resistant layer to the polycrystalline diamond layer is 1:2. The polycrystalline diamond layer is composed of the following components in mass percentage: 50% of diamond with a particle size of 50-60 μm, 30% of diamond with a particle size of 30-40 μm, 10% of diamond with a particle size of 10-20 μm, and 10% of Co.

The structure of the polycrystalline diamond composite tooth of this embodiment is shown in Figure 1, including a cemented carbide substrate 3 and a polycrystalline diamond layer 2, and an impact-resistant layer is arranged between the cemented carbide substrate 3 and the polycrystalline diamond layer 2 1. One end of the cemented carbide substrate 3 is a cylinder, and the other end is a hemispherical tooth head 4. The outer surface of the tooth head 4 is a hemispherical surface. The impact-resistant layer 1 is located on the hemispherical surface of the tooth head 4. The impact-resistant layer 1 above is polycrystalline diamond layer 2.

The preparation method of the polycrystalline diamond composite tooth of the present embodiment comprises the following steps:

1) Take diamond powder with a particle size of 20-50 μm, WC powder with a particle size of 2.5-5.0 μm, Co powder with a particle size of 5-20 μm, Ni powder with a particle size of 1.0-10 μm, and TiC powder with a particle size of 1.0-10 μm , add a planetary ball mill, the parameters of the planetary ball mill: revolution 40 rpm, rotation 80 rpm, ball mill 10h after mixing evenly, put it in a vacuum drying oven at 150 ℃ and save it for later use;

2) Take diamond powder with a particle size of 50-60 μm, diamond powder with a particle size of 30-40 μm, diamond powder with a particle size of 10-20 μm, and Co powder with a particle size of 5-20 μm, add it to a planetary ball mill, and mix it evenly after ball milling for 10 hours. Store in a vacuum oven at 120°C for later use;

3) Assemble the cemented carbide substrate, impact-resistant layer powder, and polycrystalline diamond layer powder sequentially and compact them with a 5-ton press to obtain an assembly;

4) Place the assembly obtained in step 3) in the synthetic block of pyrophyllite, and put in the conductive steel ring to form a synthetic mold;

5) Place the synthetic mold obtained in step 4) in a six-sided top diamond press, synthesize it at a pressure of 5.8GPa and a temperature of 1500°C for 5 minutes, cool for 5 minutes, release the pressure and take out the sample, and after sandblasting, mechanically process it to make it The diameter tolerance is ±0.01mm, and the height tolerance is ±0.05mm.

The down-the-hole bit of this embodiment includes a down-the-hole bit base body, and 14 tooth holes are arranged on the down-the-hole bit base body, and the polycrystalline diamond composite teeth are embedded in the tooth holes.

The preparation method of the down-the-hole drill comprises sequentially preparing the down-the-hole drill base by forging the base, normalizing the base, machining the base, secondary heat treatment of the base, and processing the tooth holes of the base, and then inlaying the polycrystalline diamond composite teeth Into the tooth hole of the DTH bit base, after the quality inspection. Spray paint packaging, that is.

Example 2

The polycrystalline diamond composite tooth of this embodiment comprises a cemented carbide substrate and a polycrystalline diamond layer, and an impact-resistant layer is arranged between the cemented carbide substrate and the polycrystalline diamond layer, and the impact-resistant layer consists of the following mass percentage Composition: Diamond 80%, WC10%, Co3%, Ni4%, TiC3%. The cemented carbide matrix is composed of the following components in mass percentage: Co8%, WC92%, wherein the grain size of WC is 2.5-5.0 μm. The mass ratio of the impact-resistant layer to the polycrystalline diamond layer is 1:3. The polycrystalline diamond layer is composed of the following components in mass percentage: 40% diamond with a particle size of 50-60 μm, 40% diamond with a particle size of 30-40 μm, 16% diamond with a particle size of 10-20 μm, and 4% Co.

The structure of the polycrystalline diamond composite tooth of the present embodiment is as shown in Figure 2, differs from embodiment 1 in that: the hemispherical surface of tooth head 4 is provided with 24 concave spherical surfaces 5, surrounds the center of tooth head 4 surfaces (hemispherical The center of the surface) is three-layer annular symmetrically distributed (as shown in Figure 3), and each layer is 8; the central axis of the concave spherical surface 5 is perpendicular to the tangential direction of the outer surface of the tooth head 4 of the cemented carbide substrate 3; The impact layer 1 is located between the tooth head 4 of the cemented carbide substrate 3 and the polycrystalline diamond layer 2 , and fills the groove of the hemisphere formed by the concave spherical surface 5 .

The preparation method of the polycrystalline diamond composite tooth of the present embodiment comprises the following steps:

1) Take diamond powder with a particle size of 20-50 μm, WC powder with a particle size of 2.5-5.0 μm, Co powder with a particle size of 5-20 μm, Ni powder with a particle size of 1.0-10 μm, and TiC powder with a particle size of 1.0-10 μm , adding a planetary ball mill, the parameters of the planetary ball mill: 40 revolutions per minute, 80 revolutions per minute, ball milled for 8 hours and mixed evenly, then placed in a vacuum drying oven at 140 ° C for future use;

2) Take diamond powder with a particle size of 50-60 μm, diamond powder with a particle size of 30-40 μm, diamond powder with a particle size of 10-20 μm, and Co powder with a particle size of 5-20 μm, add it to a planetary ball mill, and mix it evenly after ball milling for 12 hours. Store in a vacuum oven at 110°C for later use;

3) Assemble the cemented carbide substrate, impact-resistant layer powder, and polycrystalline diamond layer powder sequentially and compact them with a 5-ton press to obtain an assembly;

4) Place the assembly obtained in step 3) in the synthetic block of pyrophyllite, and put in the conductive steel ring to form a synthetic mold;

5) Place the synthetic mold obtained in step 4) in a six-sided top diamond press, synthesize it at a pressure of 5.2GPa and a temperature of 1550°C for 2 minutes, cool for 10 minutes, release the pressure and take out the sample, and after sandblasting, machine it to make it The diameter tolerance is ±0.01mm, and the height tolerance is ±0.05mm.

The down-the-hole bit of the present embodiment, as shown in Figure 4, comprises the down-the-hole bit base body 6, and the described down-the-hole bit base body 6 is provided with 12 toothed holes 8, and described polycrystalline Diamond composite teeth7. The polycrystalline diamond composite tooth 7 is the polycrystalline diamond composite tooth shown in FIG. 1 .

The preparation method of the down-the-hole drill comprises sequentially preparing the down-the-hole drill base by forging the base, normalizing the base, machining the base, secondary heat treatment of the base, and processing the tooth holes of the base, and then inlaying the polycrystalline diamond composite teeth Into the tooth hole of the DTH bit base, after the quality inspection. Spray paint packaging, that is.

Example 3

The polycrystalline diamond composite tooth of this embodiment comprises a cemented carbide substrate and a polycrystalline diamond layer, and an impact-resistant layer is arranged between the cemented carbide substrate and the polycrystalline diamond layer, and the impact-resistant layer consists of the following mass percentage Component composition: Diamond 78%, WC12%, Co7%, Ni2%, TiC1%. The cemented carbide matrix is composed of the following components in mass percentage: Co6%, WC94%, wherein the grain size of WC is 2.5-5.0 μm. The mass ratio of the impact-resistant layer to the polycrystalline diamond layer is 1:4. The polycrystalline diamond layer is composed of the following components in mass percentage: 40% diamond with a particle size of 50-60 μm, 33% diamond with a particle size of 30-40 μm, 20% diamond with a particle size of 10-20 μm, and 7% Co.

The preparation method of the polycrystalline diamond composite tooth of the present embodiment comprises the following steps:

1) Take diamond powder with a particle size of 20-50 μm, WC powder with a particle size of 2.5-5.0 μm, Co powder with a particle size of 5-20 μm, Ni powder with a particle size of 1.0-10 μm, and TiC powder with a particle size of 1.0-10 μm , adding a planetary ball mill, the parameters of the planetary ball mill: 40 revolutions per minute, 80 revolutions per minute, ball milled for 9 hours and mixed evenly, then placed in a vacuum drying oven at 130 ° C for future use;

2) Take diamond powder with a particle size of 50-60 μm, diamond powder with a particle size of 30-40 μm, diamond powder with a particle size of 10-20 μm, and Co powder with a particle size of 5-20 μm, add it to a planetary ball mill, and mix it evenly after ball milling for 14 hours. Store in a vacuum oven at 105°C for later use;

3) Assemble the cemented carbide substrate, impact-resistant layer powder, and polycrystalline diamond layer powder sequentially and compact them with a 5-ton press to obtain an assembly;

4) Place the assembly obtained in step 3) in the synthetic block of pyrophyllite, and put in the conductive steel ring to form a synthetic mold;

5) Place the synthetic mold obtained in step 4) in a six-sided top diamond press, synthesize it at a pressure of 5.5GPa and a temperature of 1500°C for 3 minutes, cool for 8 minutes, release the pressure and take out the sample, and after sandblasting, mechanically process it to make it The diameter tolerance is ±0.01mm, and the height tolerance is ±0.05mm.

The down-the-hole bit of this embodiment includes a down-the-hole bit base body, and 13 tooth holes are arranged on the down-the-hole bit base body, and the polycrystalline diamond composite teeth are embedded in the tooth holes.

The preparation method of the down-the-hole drill comprises sequentially preparing the down-the-hole drill base by forging the base, normalizing the base, machining the base, secondary heat treatment of the base, and processing the tooth holes of the base, and then inlaying the polycrystalline diamond composite teeth Into the tooth hole of the DTH bit base, after the quality inspection. Spray paint packaging, that is.

Example 4

The polycrystalline diamond composite tooth of this embodiment comprises a cemented carbide substrate and a polycrystalline diamond layer, and an impact-resistant layer is arranged between the cemented carbide substrate and the polycrystalline diamond layer, and the impact-resistant layer consists of the following mass percentage Composition: 76% diamond, 12% WC, 10% Co, 1% Ni, 1% TiC. The cemented carbide matrix is composed of the following components in mass percentage: Co7%, WC93%, wherein the grain size of WC is 2.5-5.0 μm. The mass ratio of the impact-resistant layer to the polycrystalline diamond layer is 1:5. The polycrystalline diamond layer is composed of the following components in mass percentage: 45% diamond with a particle size of 50-60 μm, 40% diamond with a particle size of 30-40 μm, 5% diamond with a particle size of 10-20 μm, and 10% Co.

The preparation method of the polycrystalline diamond composite tooth of the present embodiment comprises the following steps:

1) Take diamond powder with a particle size of 20-50 μm, WC powder with a particle size of 2.5-5.0 μm, Co powder with a particle size of 5-20 μm, Ni powder with a particle size of 1.0-10 μm, and TiC powder with a particle size of 1.0-10 μm , adding a planetary ball mill, the parameters of the planetary ball mill: 40 revolutions per minute, 80 revolutions per minute, ball milled for 10 hours and mixed evenly, then placed in a vacuum drying oven at 120 ° C for future use;

2) Take diamond powder with a particle size of 50-60 μm, diamond powder with a particle size of 30-40 μm, diamond powder with a particle size of 10-20 μm, and Co powder with a particle size of 5-20 μm, add it to a planetary ball mill, and mix it evenly after ball milling for 15 hours. Store in a vacuum oven at 100°C for later use;

3) Assemble the cemented carbide substrate, impact-resistant layer powder, and polycrystalline diamond layer powder sequentially and compact them with a 5-ton press to obtain an assembly;

4) Place the assembly obtained in step 3) in the synthetic block of pyrophyllite, and put in the conductive steel ring to form a synthetic mold;

5) Place the synthetic mold obtained in step 4) in a six-sided top diamond press, synthesize it at a pressure of 6.0GPa and a temperature of 1450°C for 4 minutes, cool for 7 minutes, release the pressure and take out the sample, and after sandblasting, mechanically process it to make it The diameter tolerance is ±0.01mm, and the height tolerance is ±0.05mm.

The down-the-hole bit of this embodiment includes a down-the-hole bit base body, and 16 tooth holes are arranged on the down-the-hole bit base body, and the polycrystalline diamond composite teeth are embedded in the tooth holes.

The preparation method of the down-the-hole drill comprises sequentially preparing the down-the-hole drill base by forging the base, normalizing the base, machining the base, secondary heat treatment of the base, and processing the tooth holes of the base, and then inlaying the polycrystalline diamond composite teeth Into the tooth hole of the DTH bit base, after the quality inspection. Spray paint packaging, that is.

Claims (10)

1. a polycrystalline diamond composite tooth, is characterized in that: comprise cemented carbide substrate and polycrystalline diamond layer, be provided with impact-resistant layer between described cemented carbide substrate and polycrystalline diamond layer, described impact-resistant layer consists of The components are composed of the following mass percentages: 75%-80% of diamond, 10%-15% of WC, and the balance is binder. 2. The polycrystalline diamond composite tooth according to claim 1, characterized in that: the binder is Co, Ni and TiC. 3. The polycrystalline diamond composite tooth according to claim 2, characterized in that: the impact-resistant layer is composed of the following components in mass percentage: 75%-80% of diamond, 10%-15% of WC, 3%-10% of Co %, Ni1%~4%, TiC1%~3%. 4. The polycrystalline diamond composite tooth according to claim 1 or 3, characterized in that: the mass ratio of the impact-resistant layer to the polycrystalline diamond layer is 1:2-5. 5. The polycrystalline diamond composite tooth according to claim 1, characterized in that: the cemented carbide matrix is a WC-Co alloy. 6. The polycrystalline diamond composite tooth according to claim 5, characterized in that: the cemented carbide matrix is composed of the following components in mass percentage: Co6%-10%, WC90%-94%. 7. The polycrystalline diamond composite tooth according to claim 1 or 3, characterized in that: the polycrystalline diamond layer is composed of the following components in mass percentage: 40% to 50% of diamonds with a particle size of 50 to 60 μm, 40% to 50% of diamonds with a particle size of 30% to 40% of diamonds with a particle size of 30 to 40 μm, 5% to 20% of diamonds with a particle size of 10 to 20 μm, and 4% to 10% of Co. 8. A method for preparing polycrystalline diamond composite teeth as claimed in claim 1, characterized in that: comprising the following steps: 1) Take diamond micropowder, WC powder and adhesive to make impact-resistant layer powder, set aside; 2) Assemble and compact the cemented carbide substrate, impact-resistant layer powder, and polycrystalline diamond layer powder in sequence to obtain an assembly; 3) Place the assembly obtained in step 2) in the pyrophyllite synthetic block, and put in the conductive steel ring to form a synthetic mold; 4) Place the synthetic mold obtained in step 3) in a six-sided top press for synthesis, cool down, release the pressure, and take it out. 9. The preparation method of polycrystalline diamond composite teeth according to claim 8, characterized in that: in step 4), the synthesis pressure is 5.2-6.0 GPa, the temperature is 1450-1550 ° C, and the synthesis time is 2-6. 5min. 10. A down-the-hole drill bit using the polycrystalline diamond composite tooth as claimed in claim 1, characterized in that: it comprises a down-the-hole drill base body, said down-the-hole drill bit base body is provided with at least one tooth hole, and said tooth hole Inlaid with the polycrystalline diamond composite teeth.