Conical diamond compact, preparation method thereof and diamond composite cutting pick

Abstract

The invention discloses a conical diamond compact and a preparation method thereof and a diamond composite cutting pick, the conical diamond compact is composed of a hard alloy matrix and a polycrystalline diamond layer attached to the hard alloy matrix, the polycrystalline diamond layer is divided into a first area and a second area, and the first area and the second area are mutually embedded and cover the upper end face of the hard alloy matrix. Through a powder injection molding filling mode, the problem of density gradient easily occurring at the top of the conical tooth due to traditional powder mold pressing is solved, the impact resistance and the wear resistance of the top are improved, the synthesis conditions of the conical diamond compact are reduced with the assistance of iron-cobalt pre-alloyed powder, meanwhile, the optimized synthesis process is used for assistance, and the production cost is reduced. The stability in the synthesis of the conical diamond compact is effectively ensured, and the yield of products is correspondingly improved. The conical PDC prepared by the method has the advantages of high impact resistance, high wear resistance and the like, and is particularly suitable for rotary excavating and tunneling of soft and hard staggered layers and hard rocks.

Description

Technical Field

[0001] The invention relates to the technical field of superhard material manufacturing, in particular to a conical diamond composite piece and a preparation method thereof and a diamond composite piece pick. Background Art

[0002] With the widespread application of large-scale mining machinery in harsh working conditions such as coal mining, tunnel shield, trench excavation, road paving and waterway dredging in recent years, picks as key tools for cutting rock formations have received increasing attention.

[0003] There are two types of cemented carbide picks (hereinafter referred to as "alloy picks") and polycrystalline diamond picks (hereinafter referred to as "diamond picks") that are commonly used in the market. The alloy picks are made by brazing the pick base and the cemented carbide tooth head. Common failure forms of cemented carbide picks include: alloy tooth head falling off, pick handle fracture, tooth body wear, alloy head crushing, etc., among which tooth body wear and tooth head falling off account for about 80% of the total failures.

[0004] Polycrystalline diamond picks are high-performance picks made by fixing conical diamonds to the pick base, using the excellent wear resistance of polycrystalline diamond and the good impact toughness of cemented carbide. However, problems such as tooth wear and tooth head shedding are prone to occur during use. The reason is that the suitable welding temperature for diamond picks should not exceed 700℃, and in actual operation, high or low temperatures will affect the performance of diamond picks. In addition, polycrystalline diamond and cemented carbide have different thermal expansion coefficients. Improper post-welding treatment can easily cause diamond picks to delaminate during operation.

[0005] Therefore, the development of high-performance picks has become an important research topic. Summary of the invention

[0006] In order to overcome the shortcomings of traditional diamond picks such as tooth wear, easy cracking and delamination of the tooth head, and inability to meet the requirements of drilling under high impact loads, the present invention provides a conical diamond composite sheet and a preparation method thereof and a diamond composite pick. The diamond composite pick prepared by the method has the advantages of strong impact resistance and high wear resistance, and solves the problems of polycrystalline diamond layer cracking and falling off and easy wear of the pick body to a large extent. It is particularly used in rotary drilling and excavation of soft and hard misaligned layers and hard rocks.

[0007] To achieve the above object, the present invention is achieved through the following technical solutions: A conical diamond composite sheet consists of a cemented carbide substrate and a polycrystalline diamond layer attached to the cemented carbide substrate. The polycrystalline diamond layer is divided into a first area and a second area. The two areas are interlocked and cover the upper end surface of the cemented carbide substrate.

[0008] The first area and the second area are embedded in each other, which means that: a plurality of first areas are embedded in the second area, and the shape of the first area is spherical, semi-spherical, conical, cylindrical or spiral; or, the second area covers the upper end surface of the cemented carbide substrate, and the first area is embedded in the upper surface of the second area.

[0009] The first region of the polycrystalline diamond layer is composed of the following raw materials in weight percentage: 70-80 parts of diamond powder, 10-20 parts of FeCo70 powder, and 1-5 parts of tungsten carbide powder; the second region of the polycrystalline diamond layer is composed of the following raw materials in weight percentage: 50-70 parts of diamond powder, 20-35 parts of FeCo70 powder, and 5-15 parts of tungsten carbide powder.

[0010] In the first area, the diamond powder is composed of the following raw materials in weight percentage: 28-40 micron diamond powder accounts for 40-50%, 10-20 micron diamond powder accounts for 30-40%, and 1-5 micron diamond powder accounts for 10-20%.

[0011] In the second region, the diamond powder is composed of the following raw materials in weight percentage: 15-25 micron diamond powder accounts for 50-70%, 5-10 micron diamond powder accounts for 20-30%, and 1-3 micron diamond powder accounts for 10-20%.

[0012] In the first region and the second region, the particle size of the FeCo70 powder is 3-5 μm.

[0013] The axial cross section of the cemented carbide substrate is in the shape of an inverted cone, and the taper is 1:15 to 1:30.

[0014] A method for manufacturing a conical diamond composite sheet comprises the following steps: Step a, mixing: uniformly mixing the powders of the first region and the second region of the polycrystalline diamond layer according to their components; Step b, kneading: adding 0.05%-0.5% carboxymethyl cellulose, 0.5-1.5% zinc stearate and 5-50 ml high-purity water to the powder in the first region in step a, and stirring rapidly and uniformly at a stirring speed of 60-150 rpm for 10-30 minutes to obtain a filler; Step c, filling 1: the filling material obtained in step b is loaded into a spiral syringe, and injected into a proper position in the metal cup to obtain a first region green body; Step d, curing: The green body in the first region of step c is placed in a vacuum furnace for curing treatment, and the vacuum degree is 10 -2 -10 -3 MPa, temperature 100-200℃, treatment time 1-2h; Step e, filling 2: the powder in the second region is filled into the metal cup processed in step d, and the cemented carbide matrix is ​​filled into the metal cup to obtain a composite sheet green body; Step f, extrusion: sequentially placing a salt cup, a composite sheet green body, a salt tube and a salt sheet into an alloy steel mold, placing them on a four-column hydraulic press for extrusion molding to obtain a green body 2; the extrusion pressure is 10-20 MPa, and the holding time is 10-30 s; Step g, assembling: sequentially loading the blank 2 obtained in step f into the carbon tube and the pyrophyllite block to obtain a combined block; Step h, synthesis: placing the combined block obtained in step f on a six-sided top press for synthesis, with a synthesis pressure of 4-6 GPa, a synthesis temperature of 1200-1500° C., and a synthesis time of 300-650 seconds to obtain a product blank; Step i, machining: cylindrical grinding and flat grinding are performed on the product blank in step h to obtain a conical diamond composite sheet.

[0015] In step h, the synthesis pressure and synthesis temperature are respectively achieved by controlling the pressure curve and the power curve; The control pressure curve is as follows: firstly, the pressure is raised to the pause pressure, the pressure is maintained for 200-380s, then the pressure is increased, the pressure is raised to the final pressure within 120-240s, and then the pressure is released. The pause pressure is 92-96% of the final pressure, and the final pressure is 88-93MPa. The control power curve is as follows: first increase the power to the first pause power, maintain it for 60-90s, then increase it to the second pause power within 10-30s, maintain it for 200-300s, then set the power to decrease, adjust the final power within 100-200s, and then stop heating; the first pause power is 45-50% of the final power, the second pause power is 106-110% of the final power, and the final power is 2800-2930W.

[0016] A diamond composite pick using the conical diamond composite piece according to claim 1, which is formed by a pick base and the conical diamond composite piece through a conical assembly, wherein the axial cross-section of the blind hole at the top end of the pick base is conical, and the taper is 1:15 to 1:30.

[0017] Compared with the prior art, the present invention has the following beneficial effects: the present invention solves the density gradient problem of the top of the conical tooth due to traditional powder molding by powder injection molding filler, improves the impact resistance and wear resistance of the top, and uses iron-cobalt pre-alloyed powder to reduce the synthesis conditions of the conical diamond composite sheet. At the same time, it uses an optimized synthesis process to effectively ensure the stability of the conical diamond composite sheet during synthesis, and correspondingly improves the product yield. The conical PDC prepared by this method has the advantages of high impact resistance, high wear resistance, etc., and is particularly suitable for rotary drilling and tunneling of soft and hard staggered layers and hard rocks. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is another structural schematic diagram of the present invention; Figure 3 It is a schematic diagram of the structure of the base body of the pick of the present invention; In the figure: 1—polycrystalline diamond layer, 2—cemented carbide substrate, 11—first region, 12—second region, C—taper. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] like Figure 1 As shown, a conical diamond composite sheet is composed of a cemented carbide substrate 2 and a polycrystalline diamond layer 1 attached to the cemented carbide substrate 2. The polycrystalline diamond layer 1 is divided into a first area 11 and a second area 12. The two areas are interlocked and cover the upper end surface of the cemented carbide substrate 2.

[0022] It should be noted that the first region 11 and the second region 12 are embedded in each other, which means that a plurality of first regions 11 are embedded in the second region 12, and the shape of the first region 11 can be a sphere, a semisphere, a cone, a cylinder, a spiral or other shapes, such as Figure 1 Alternatively, the second region 12 covers the upper end surface of the cemented carbide substrate 2, and the first region 11 is embedded in the upper surface of the second region 12, as shown in FIG. Figure 2 shown.

[0023] The first region 11 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 70-80 parts of diamond powder, 10-20 parts of FeCo70 powder, and 1-5 parts of tungsten carbide powder. Its shape can be cone-shaped, cylindrical, spiral or spherical.

[0024] In the first area 11, the diamond powder is composed of the following raw materials in weight percentage: 28-40 micron diamond powder accounts for 40-50%, 10-20 micron diamond powder accounts for 30-40%, and 1-5 micron diamond powder accounts for 10-20%.

[0025] The second region 12 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 50-70 parts of diamond powder, 20-35 parts of FeCo70 powder, and 5-15 parts of tungsten carbide powder.

[0026] In the second region 12, the diamond powder is composed of the following raw materials in weight percentage: 15-25 micron diamond powder accounts for 50-70%, 5-10 micron diamond powder accounts for 20-30%, and 1-3 micron diamond powder accounts for 10-20%.

[0027] In the first region 11 and the second region 12, the particle size of the FeCo70 powder is 3-5 μm.

[0028] The axial cross section of the cemented carbide substrate 2 is an inverted cone, and the taper C is 1:15 to 1:30.

[0029] A method for manufacturing a conical diamond composite sheet comprises the following steps: Step a, mixing: uniformly mixing the powders of the first region 11 and the second region 12 of the polycrystalline diamond layer 1 according to their components; Step b, kneading: add 0.05%-0.5% carboxymethyl cellulose (CMC), 0.5-1.5% zinc stearate and 5-50 ml high-purity water to the powder in the first area 11 in step a, and stir quickly and evenly at a stirring speed of 60-150 rpm for 10-30 minutes to obtain a filler.

[0030] Step c, filling 1: the filling material obtained in step b is loaded into a spiral syringe, and injected into a proper position in the metal cup to obtain a green body of the first region.

[0031] Step d, curing: The green body in the first region of step c is placed in a vacuum furnace for curing treatment, and the vacuum degree is 10-2 -10 -3 MPa, temperature 100-200℃, treatment time 1-2h.

[0032] Step e, filling 2: the powder of the second region 12 is filled into the metal cup processed in step d, and the cemented carbide substrate 2 is filled into the metal cup to obtain a green composite sheet.

[0033] Step f, extrusion: the salt cup, the composite sheet green body, the salt tube and the salt sheet are sequentially loaded into the alloy steel mold, and placed on a four-column hydraulic press for extrusion molding to obtain the green body 2. The extrusion pressure is 10-20 MPa, and the holding time is 10-30 s. In this step, extrusion molding refers to extruding the salt cup, the salt tube and the salt sheet into shape, and the composite sheet green body is wrapped therein.

[0034] Step g, assembling: the blank 2 obtained in step f is sequentially loaded into the carbon tube and the pyrophyllite block to obtain a combined block.

[0035] Step h, synthesis: placing the combined block obtained in step f on a six-sided top press for synthesis, with a synthesis pressure of 4-6 GPa, a synthesis temperature of 1200-1500° C., and a synthesis time of 300-650 s to obtain a product blank.

[0036] Step i, machining: cylindrical grinding and flat grinding are performed on the product blank in step h to obtain a conical diamond composite sheet.

[0037] In step h, the synthesis pressure and synthesis temperature are achieved by controlling the pressure curve and the power curve respectively.

[0038] The control pressure curve is as follows: firstly, the pressure is raised to the pause pressure, and the pressure is maintained for 200-380s before setting the pressure increase, and the pressure is raised to the final pressure within 120-240s, and then the pressure is released. The pause pressure is 92-96% of the final pressure, and the final pressure is 88-93MPa.

[0039] The control power curve is as follows: first, the power is raised to the first pause power, maintained for 60-90 seconds, then raised to the second pause power within 10-30 seconds, maintained for 200-300 seconds, the power is set to decrease, the final power is adjusted within 100-200 seconds, and then the heating is stopped. The first pause power is 45-50% of the final power, the second pause power is 106-110% of the final power, and the final power is 2800-2930W.

[0040] A diamond composite pick is formed by a pick base and the above-mentioned conical diamond composite piece through conical assembly, wherein the axial section of the blind hole at the top end of the pick base is conical, and the taper is 1:15-1:30.

[0041] Example 1 A method for manufacturing a conical diamond composite sheet comprises the following steps: Step a, mixing: the powders of the first region 11 and the second region 12 of the polycrystalline diamond layer 1 are mixed evenly according to the components; wherein the first region 11 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 70 parts of diamond powder, 10 parts of FeCo70 powder, and 1 part of tungsten carbide powder. In the first region 11, the diamond powder is composed of the following raw materials in weight percentage: 40% of 28-40 micron diamond powder, 30% of 10-20 micron diamond powder, and 10% of 1-5 micron diamond powder. The second region 12 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 50 parts of diamond powder, 20 parts of FeCo70 powder, and 5 parts of tungsten carbide powder. In the second region 12, the diamond powder is composed of the following raw materials in weight percentage: 50% of 15-25 micron diamond powder, 20% of 5-10 micron diamond powder, and 10% of 1-3 micron diamond powder.

[0042] Step b, kneading: add carboxymethyl cellulose (CMC), zinc stearate and high-purity water to the powder in the first area 11 in step a, and stir quickly and evenly at a stirring speed of 60 to 150 rpm for 10 to 30 minutes to obtain a filler.

[0043] Step c, filling 1: the filling material obtained in step b is loaded into a spiral syringe, and injected into a proper position in the metal cup to obtain a green body of the first region.

[0044] Step d, curing: The green body in the first region of step c is placed in a vacuum furnace for curing treatment, and the vacuum degree is 10 -2 -10 -3 MPa, temperature 100-200℃, treatment time 1-2h.

[0045] Step e, filling 2: the powder of the second region 12 is filled into the metal cup processed in step d, and the cemented carbide substrate 2 is filled into the metal cup to obtain a green composite sheet.

[0046] Step f, extrusion: the salt cup, the blank 1, the salt tube and the salt sheet are sequentially placed in the alloy steel mold, and placed on a four-column hydraulic press for extrusion molding to obtain the green body 2. The extrusion pressure is 10-20 MPa, and the holding time is 10-30 s.

[0047] Step g, assembling: the blank 2 obtained in step f is sequentially loaded into the carbon tube and the pyrophyllite block to obtain a combined block.

[0048] Step h, synthesis: placing the combined block obtained in step f on a six-sided top press for synthesis, with a synthesis pressure of 4-6 GPa, a synthesis temperature of 1200-1500° C., and a synthesis time of 300-650 s to obtain a product blank.

[0049] Step i, machining: cylindrical grinding and flat grinding are performed on the product blank in step h to obtain a conical diamond composite sheet.

[0050] Example 2 A method for manufacturing a conical diamond composite sheet comprises the following steps: Step a, mixing: the powders of the first region 11 and the second region 12 of the polycrystalline diamond layer 1 are mixed evenly according to the components; wherein the first region 11 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 80 parts of diamond powder, 20 parts of FeCo70 powder, and 5 parts of tungsten carbide powder. In the first region 11, the diamond powder is composed of the following raw materials in weight percentage: 50% of 28-40 micron diamond powder, 40% of 10-20 micron diamond powder, and 20% of 1-5 micron diamond powder. The second region 12 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 70 parts of diamond powder, 35 parts of FeCo70 powder, and 15 parts of tungsten carbide powder. In the second region 12, the diamond powder is composed of the following raw materials in weight percentage: 70% of 15-25 micron diamond powder, 30% of 5-10 micron diamond powder, and 20% of 1-3 micron diamond powder.

[0051] Example 3 A method for manufacturing a conical diamond composite sheet comprises the following steps: Step a, mixing: the powders of the first region 11 and the second region 12 of the polycrystalline diamond layer 1 are mixed evenly according to the components; wherein the first region 11 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 75 parts of diamond powder, 15 parts of FeCo70 powder, and 3 parts of tungsten carbide powder. In the first region 11, the diamond powder is composed of the following raw materials in weight percentage: 45% of 28-40 micron diamond powder, 35% of 10-20 micron diamond powder, and 15% of 1-5 micron diamond powder. The second region 12 of the polycrystalline diamond layer 1 is composed of the following raw materials in weight percentage: 60 parts of diamond powder, 28 parts of FeCo70 powder, and 10 parts of tungsten carbide powder. In the second region 12, the diamond powder is composed of the following raw materials in weight percentage: 60% of 15-25 micron diamond powder, 25% of 5-10 micron diamond powder, and 15% of 1-3 micron diamond powder.

[0052] Compared with the prior art, the advantages of the present invention are: 1. Use powder injection molding fillers to replace traditional powder fillers: To a certain extent, it solves the density gradient problem that is easy to occur in traditional powder molding, and solves the problem of poor wear resistance and impact resistance caused by density gradient on the top of the product. Through injection molding, orderly filling the mold at a specified position can improve the uniformity of the organization, density and product performance at that position, thereby improving product performance.

[0053] 2. Use iron-cobalt pre-alloyed powder instead of traditional cobalt powder: The distribution of iron and cobalt elements in the pre-alloyed powder is more uniform, which not only avoids the metal segregation caused by the uneven mixing of elemental iron + cobalt powder, but also takes into account the characteristics of the two powders. Iron has better wettability to both diamond and tungsten carbide than cobalt. Under high temperature and high pressure, the graphitization process of diamond micropowder with the participation of iron and cobalt will be faster than that of pure diamond powder. Diamond micropowder undergoes dissolution and regrowth, and finally forms a dense polycrystalline material. In addition, the participation of iron elements reduces the synthesis conditions of diamond composite sheets to a certain extent (lowering the synthesis temperature and shortening the synthesis time).

[0054] 3. Optimized synthesis process: In the later stage of the synthesis process, measures of slow temperature reduction and slow pressure increase were taken to solve the problem of deterioration of the synthesis quality of conical PDC caused by the accumulation of pressure reduction and temperature increase in the high-pressure cavity during the high-pressure synthesis of conical PDC. This greatly improved the growth environment of the conical PDC and ensured the uniformity of the pressure field and temperature field in the conical PDC synthesis cavity, thereby correspondingly improving the product yield.

[0055] The present invention solves the density gradient problem of the cone tooth top due to traditional powder molding by powder injection molding filler, improves the impact resistance and wear resistance of the top, and uses iron-cobalt pre-alloyed powder to reduce the synthesis conditions of the cone diamond composite sheet. At the same time, it uses an optimized synthesis process to effectively ensure the stability of the cone diamond composite sheet during synthesis, and correspondingly improves the product yield. The cone PDC prepared by this method has the advantages of high impact resistance, high wear resistance, etc., and is particularly suitable for rotary drilling and tunneling of soft and hard staggered layers and hard rocks.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, which should also be regarded as the scope of protection of the present invention.

Claims

1. A conical diamond composite sheet, comprising a cemented carbide substrate (2) and a polycrystalline diamond layer (1) attached to the cemented carbide substrate (2), characterized in that: The polycrystalline diamond layer (1) is divided into a first region (11) and a second region (12), and the two regions are interlocked and cover the upper end surface of the cemented carbide substrate (2).

2. The conical diamond composite sheet according to claim 1, characterized in that: The first region (11) and the second region (12) are embedded in each other, which means that: a plurality of first regions (11) are embedded in the second region (12), and the shape of the first region (11) is spherical, semi-spherical, conical, cylindrical or spiral; or, the second region (12) covers the upper end surface of the cemented carbide substrate (2), and the first region (11) is embedded in the upper surface of the second region (12).

3. The conical diamond composite sheet according to claim 1, characterized in that: The first region (11) of the polycrystalline diamond layer (1) is composed of the following raw materials in weight percentage: 70-80 parts of diamond powder, 10-20 parts of FeCo70 powder, and 1-5 parts of tungsten carbide powder; the second region (12) of the polycrystalline diamond layer (1) is composed of the following raw materials in weight percentage: 50-70 parts of diamond powder, 20-35 parts of FeCo70 powder, and 5-15 parts of tungsten carbide powder.

4. The conical diamond compact according to claim 3, characterized in that: In the first area (11), the diamond powder is composed of the following raw materials in weight percentage: 28-40 micron diamond powder accounts for 40-50%, 10-20 micron diamond powder accounts for 30-40%, and 1-5 micron diamond powder accounts for 10-20%.

5. The conical diamond compact according to claim 3, characterized in that: In the second region (12), the diamond powder is composed of the following raw materials in weight percentage: 15-25 micron diamond powder accounts for 50-70%, 5-10 micron diamond powder accounts for 20-30%, and 1-3 micron diamond powder accounts for 10-20%.

6. The conical diamond compact according to claim 3, characterized in that: In the first region (11) and the second region (12), the particle size of the FeCo70 powder is 3-5 μm.

7. The conical diamond compact according to claim 1, characterized in that: The axial cross section of the cemented carbide substrate (2) is in the shape of an inverted cone, with a taper of 1:15 to 1:

30.

8. A method for manufacturing a conical diamond composite sheet, characterized in that: The following steps are involved: Step a, mixing: uniformly mixing the powders of the first region (11) and the second region (12) of the polycrystalline diamond layer (1) according to their components; Step b, kneading: adding 0.05%-0.5% carboxymethyl cellulose (CMC), 0.5-1.5% zinc stearate and 5-50 ml high-purity water to the powder in the first area (11) in step a, and stirring rapidly and uniformly at a stirring speed of 60-150 rpm for 10-30 minutes to obtain a filler; Step c, filling 1: the filling material obtained in step b is loaded into a spiral syringe, and injected into a proper position in the metal cup to obtain a first region green body; Step d, curing: The green body in the first region of step c is placed in a vacuum furnace for curing treatment, and the vacuum degree is 10 -2 -10 - 3 MPa, temperature 100-200℃, treatment time 1-2h; Step e, filling 2: the powder of the second region (12) is filled into the metal cup processed in step d, and the cemented carbide substrate (2) is filled into the metal cup to obtain a composite sheet green body; Step f, extrusion: sequentially placing a salt cup, a composite sheet green body, a salt tube and a salt sheet into an alloy steel mold, placing them on a four-column hydraulic press for extrusion molding to obtain a green body 2; the extrusion pressure is 10-20 MPa, and the holding time is 10-30 s; Step g, assembling: sequentially loading the blank 2 obtained in step f into the carbon tube and the pyrophyllite block to obtain a combined block; Step h, synthesis: placing the combined block obtained in step f on a six-sided top press for synthesis, with a synthesis pressure of 4-6 GPa, a synthesis temperature of 1200-1500° C., and a synthesis time of 300-650 seconds to obtain a product blank; Step i, machining: cylindrical grinding and flat grinding are performed on the product blank in step h to obtain a conical diamond composite sheet.

9. The method for manufacturing a conical diamond composite sheet according to claim 8, characterized in that: In step h, the synthesis pressure and synthesis temperature are respectively achieved by controlling the pressure curve and the power curve; The control pressure curve is as follows: firstly, the pressure is raised to the pause pressure, the pressure is maintained for 200-380s, then the pressure is increased, the pressure is raised to the final pressure within 120-240s, and then the pressure is released. The pause pressure is 92-96% of the final pressure, and the final pressure is 88-93MPa. The control power curve is as follows: first increase the power to the first pause power, maintain it for 60-90s, then increase it to the second pause power within 10-30s, maintain it for 200-300s, then set the power to decrease, adjust the final power within 100-200s, and then stop heating; the first pause power is 45-50% of the final power, the second pause power is 106-110% of the final power, and the final power is 2800-2930W.

10. A diamond composite pick using the conical diamond composite piece according to claim 1, which is formed by a pick base and the conical diamond composite piece being assembled in a conical shape, wherein: The axial section of the blind hole at the top end of the pick base is conical, and the taper is 1:15 to 1:30.

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