Polycrystalline diamond compact, preparation method and application of polycrystalline diamond compact in PDC drill bit

Abstract

The invention belongs to the technical field of superhard composite materials, and relates to a polycrystalline diamond compact, a preparation method and application of the polycrystalline diamond compact in a PDC drill bit. The polycrystalline diamond compact comprises a diamond layer and a hard substrate, the transition layer is arranged between the diamond layer and the hard substrate; the diamond layer comprises a hard-phase layer and a soft-phase layer, and the hard-phase layer is close to one side of the hard substrate; the hard-phase layer, the soft-phase layer and the transition layer which are different in component content, shape and structure and the selected use amount of prefabricated carbide are controlled, so that the whole polycrystalline diamond compact has high impact toughness and wear resistance, and the residual stress caused by the difference of thermal expansion coefficients of the diamond layer and the hard substrate is reduced due to the existence of the transition layer; the polycrystalline diamond compacts obtained through the machining method are uniform in quality and stable in performance, and can be widely applied to PDC drill bits.

Description

Technical Field

[0001] The invention belongs to the technical field of superhard composite materials and relates to a polycrystalline diamond composite sheet, a preparation method and application thereof in a PDC drill bit. Background Art

[0002] Polycrystalline diamond composite (PDC) is a super-hard composite material with a polycrystalline diamond layer arranged on a cemented carbide material substrate. It has the characteristics of high wear resistance of diamond and toughness and weldability of cemented carbide, and has the advantages of high hardness and good wear resistance.

[0003] "Polycrystalline diamond" refers to a type of material made by placing multiple diamond crystals under ultra-high pressure and temperature to cause intercrystalline bonding. Usually, a catalyst / binder is used to promote intercrystalline bonding. This material is often referred to as "sintered diamond" in the industry. "Preformed carbide" refers to grains containing a metal element from Group VIII (most commonly Co, Ni or Fe and their various alloys) and carbide that are pressed and heated to produce a whole carbide with high toughness. It can be used to form a binder for polycrystalline diamond. The most common and most easily available form of preformed carbide is tungsten carbide with a cobalt binder. "Substrate" is a cylindrical cemented carbide formed by sintering carbide and catalyst under sufficient temperature and impact force.

[0004] Polycrystalline diamond has superior properties to single crystal diamond, such as being more impact resistant than single crystal diamond, however, due to the high elastic modulus of diamond, the impact toughness of polycrystalline diamond is still relatively low. Therefore, the first industrial polycrystalline diamond products were in the form of composites formed by bonding polycrystalline diamond to a metal substrate or base plate. By far the most common form of this composite is a polycrystalline diamond disc "grown" directly onto a carbide substrate disc in a high temperature and high pressure process, the pre-prepared carbide substrate having a higher thermal expansion coefficient than the polycrystalline diamond. Since the polycrystalline diamond layer is less ductile than the substrate, these stresses will lead to cracking and spalling failure of the diamond layer, both during the cooling phase and during use. When polycrystalline diamond is impacted, microcracks usually form on the surface, which then extend to the entire composite to cause catastrophic failure. The higher surface packing density means high hardness and wear resistance, which has a positive effect on the cutting ability of the composite, but also leads to lower surface toughness, so that cracks often originate from the surface when impacted.

[0005] Chinese invention patent CN104690274B discloses a polycrystalline diamond-hard alloy composite sheet and its preparation method, including a hard alloy substrate and a polycrystalline diamond layer. The polycrystalline diamond layer is made of one or more materials of tungsten, rhenium, chromium, and titanium that can react with diamond to form carbides and have a thermal expansion coefficient close to that of diamond as an adhesive. Diamond powder is sintered under high temperature and high pressure, and the remaining diamonds are directly bonded through the catalytic effect of cobalt participating in the sintering. The cobalt content in the polycrystalline diamond layer is reduced, and the thermal stability of the polycrystalline layer can be improved. The polycrystalline diamond surface layer and polycrystalline diamond transition layer of a single-layer or multi-layer structure are formed by layered feeding and one-time sintering. The thermal stability, wear resistance, and impact resistance of the diamond surface layer or the diamond transition layer can be adjusted according to the working conditions.

[0006] However, research has found that the use of diamond alloy composite sheets and drill bits using them still have the following technical problems: composite sheets made of polycrystalline diamond are prone to peeling, the surface crack initiation period is short, the impact toughness and wear resistance need to be improved, and the impact resistance of PDC drill bits needs to be adaptively adjusted to increase service life. Summary of the invention

[0007] The present invention provides a wear-resistant and impact-resistant material based on diamond crystals and prefabricated carbides, which is used to solve the technical problems in the prior art that composite sheets prepared from polycrystalline diamond are prone to peeling, have a short surface crack initiation period, poor impact toughness and wear resistance, and the impact resistance of PDC drill bits needs to be adaptively adjusted to increase service life.

[0008] One of the technical solutions adopted by the present invention is:

[0009] A polycrystalline diamond composite sheet is provided, comprising a diamond layer and a hard substrate; the diamond layer comprises a hard phase layer and a soft phase layer, wherein the hard phase layer is close to one side of the hard substrate; the hard phase layer comprises diamond particles; the soft phase layer comprises: diamond particles, prefabricated carbide and adhesive.

[0010] Furthermore, the hard phase layer comprises 82-96 parts of diamond particles, 0-20 parts of prefabricated carbide and 0-6 parts of adhesive in terms of weight.

[0011] Furthermore, the soft phase layer comprises, by weight, 75-86 parts of diamond particles, 23-37 parts of prefabricated carbides and 1-15 parts of a binder.

[0012] Furthermore, the hard substrate comprises: any one of metal, alloy, ceramic and metal-based ceramic, as well as prefabricated carbide and adhesive.

[0013] Furthermore, the prefabricated carbide is prepared from a material containing a transition metal element and a carbide, and the specific preparation method is as follows:

[0014] (1) Mixing a material containing a transition metal element and a carbide to form a cylindrical compact, and setting a temperature rise program for sintering;

[0015] (2) cooling to 770-790° C. and applying axial pressure to the cylindrical compact; cooling to room temperature to obtain a multi-phase and multi-size composite material;

[0016] (3) The multi-phase and multi-size composite material is crushed, a hydrochloric acid solution is added, the mixture is allowed to stand, and suction filtered; the filter residue is washed and dried to obtain the obtained product.

[0017] Preferably, the material containing transition metal elements includes at least one of iron powder, cobalt powder, nickel powder, iron alloy, cobalt alloy and nickel alloy.

[0018] Preferably, the carbide is at least one of tungsten carbide, rhenium carbide, chromium carbide, titanium carbide, boron carbide, grit and flame sprayed pre-sintered sand.

[0019] More preferably, the material containing transition metal elements comprises, in terms of weight percentage of transition metal elements, 5-36 parts of iron powder and / or iron alloy, 2-12 parts of nickel powder and / or nickel alloy, and 1-6 parts of cobalt powder and / or cobalt alloy; further preferably, 32 parts of iron powder and / or iron alloy, 8 parts of nickel powder and / or nickel alloy, and 4 parts of cobalt powder and / or cobalt alloy.

[0020] When the material containing iron elements is iron powder and iron alloy, the total weight proportion of the iron powder and iron alloy is 5-36 parts; similarly, when the material containing nickel elements is nickel powder and nickel alloy, the total weight proportion of the nickel powder and nickel alloy is 2-12 parts; when the material containing cobalt elements is cobalt powder and / or cobalt alloy, the total weight proportion of the cobalt powder and / or cobalt alloy is 1-6 parts.

[0021] More preferably, the carbide comprises, by weight, 3-8 parts of chromium carbide, 1-4 parts of titanium carbide and 0.6-3 parts of boron carbide; further preferably, 5 parts of chromium carbide, 3 parts of titanium carbide and 1.5 parts of boron carbide.

[0022] The invention has good wear resistance, corrosion resistance and oxidation resistance in a high temperature environment through chromium carbide powder; titanium carbide powder is a typical transition metal carbide, and its crystal structure determines the basic characteristics of high hardness, high melting point, wear resistance and electrical conductivity; boron carbide powder has the characteristics of low density, high strength, high temperature stability and good chemical stability; by optimizing the ratio of iron powder, nickel powder, cobalt powder, chromium carbide powder, titanium carbide powder and boron carbide powder, a micro-nano mixed multi-scale composite material is formed through programmed heating, heat preservation sintering, hot pressing and acid corrosion, so that chromium carbide, titanium carbide and boron carbide present irregular polyhedron or nearly spherical morphology, and the elastic modulus of prefabricated carbides with various sizes and morphologies is lower than that of a polycrystalline diamond matrix, and can absorb more impact energy when dispersed in a polycrystalline diamond matrix, has good impact resistance, and alleviates stress caused by differences in thermal expansion coefficients.

[0023] Furthermore, in step (1), the heating program is: heating to 300-325°C at a rate of 40-55°C / min, vacuum degassing for 15-30min, then heating to 500-520°C at a rate of 40-55°C / min, keeping warm for 10-20min; heating to 950-1030°C at a rate of 35-50°C / min, keeping warm for 20-30min.

[0024] Preferably, in step (3), the concentration of the hydrochloric acid solution is 35-40wt%; the standing time is 16-20h; and the washing is performed using deionized water and anhydrous ethanol in sequence.

[0025] Furthermore, the diamond particles have a particle size of 1-100 microns, preferably 4-12 microns. Diamond particles with a small particle size have higher wear resistance and stronger cutting effect; the particle size of the diamond particles in the soft phase layer is ≥ the particle size of the diamond particles in the hard phase layer, and the larger particle size of the diamond particles can provide better impact toughness.

[0026] In the present invention, the binders used in the hard substrate, hard phase layer, soft phase layer and transition layer of the polycrystalline diamond compact are independently selected from elements of Group VIII and / or their corresponding compounds.

[0027] Furthermore, a transition layer is provided between the diamond layer of the polycrystalline diamond composite sheet and the hard substrate.

[0028] In the present invention, when steel or any other material that is chemically reactive or incompatible with the composition of polycrystalline diamond is selected, a transition layer can be used as a barrier between the hard substrate and the diamond layer.

[0029] Preferably, the transition layer comprises diamond particles, prefabricated carbide and a binder.

[0030] More preferably, the transition layer comprises, by weight, 32-47 parts of prefabricated carbide, 76-85 parts of diamond particles and 1-18 parts of binder.

[0031] In the present invention, the diamond content determines the hardness (wear resistance). The lower the prefabricated carbide content, the higher the diamond content, and thus the higher the hardness (wear resistance), the better the effect of cutting the formation. However, the impact resistance is lower; therefore, the soft phase layer has a high prefabricated carbide content and has better impact resistance; the combination of soft and hard has better comprehensive performance.

[0032] Furthermore, the diamond layer can be configured to have different structures according to the requirements of the drill bit.

[0033] In some embodiments of the present invention, a hard phase layer is disposed on one side of the hard substrate and the hard phase layer covers the side of the hard substrate, and a soft phase layer is disposed on the side of the hard phase layer away from the hard substrate and the soft phase layer covers the side of the hard phase layer;

[0034] In some embodiments of the present invention, a diamond layer is disposed on one side of the hard substrate, which is formed by a plurality of annular soft phase layers and hard phase layers nested in sequence along the radial direction, and the diamond layer distributed on the outermost side is the soft phase layer;

[0035] In some embodiments of the present invention, a plurality of hard phase layers with fan-shaped cross sections are arranged on one side of the hard substrate in an annular array and distributed on the periphery, and there is a spacing between adjacent hard phase layers, and the area where the diamond layer is located outside the hard phase layer is a soft phase layer;

[0036] In some embodiments of the present invention, a hard phase layer is disposed on one side of the hard substrate, wherein both the upper and lower surfaces are circular cuts and the chord length of the cross-section circular cut increases from far away from the hard substrate to close to the hard substrate, and the area where the diamond layer is located outside the hard phase layer is a soft phase layer.

[0037] The second technical solution of the present invention is:

[0038] A method for preparing the above-mentioned polycrystalline diamond compact is provided, comprising the following steps:

[0039] (1) preparing hard substrate material, hard phase layer material, soft phase layer material and transition layer material;

[0040] (2) According to the structure of the polycrystalline diamond composite sheet, the hard substrate material, the hard phase layer material, the soft phase layer material and the transition layer material are added into the mold, mechanically statically pressed, and molded into a blank;

[0041] (3) After the blank is sintered, it is cooled and demoulded.

[0042] Furthermore, in step (1), the hard substrate material, the hard phase layer material, the soft phase layer material and the transition layer material are prepared by mixing the raw materials in proportion and then ball milling.

[0043] Furthermore, in step (3), the sintering conditions are: impact force 5-10 GPa, temperature 1300-1700° C., and sintering time 0.5-10 min.

[0044] The third technical solution of the present invention is:

[0045] Provided is the use of the polycrystalline diamond compact or the polycrystalline diamond compact prepared by the preparation method in a PDC drill bit.

[0046] The fourth technical solution of the present invention is:

[0047] Provided is a PDC drill bit, which is prepared using the polycrystalline diamond composite sheet or the polycrystalline diamond composite sheet prepared by the preparation method as a buffer head material.

[0048] Furthermore, the PDC drill bit is provided with an upper joint, a drill bit body, a lower joint and a blade in sequence from top to bottom; the inner cavity of the drill bit body is provided with a buffer energy storage mechanism; the lower joint is connected to the drill bit body through a rotating bearing; a plurality of groups of cutting teeth are distributed on the outer wall of the blade, and an impact-resistant buffer mechanism is provided inside the blade.

[0049] Furthermore, the impact-resistant buffer mechanism includes a buffer plate, a connecting plate and a plurality of buffer columns, and a buffer head is provided at the end of the buffer column; the buffer plate is fixedly connected to the bottom of the lower joint, and the bottom center of the buffer plate is fixedly connected to the top center of the connecting plate through a spring damper; the plurality of buffer columns are fixed to the bottom of the connecting plate and extend toward the outer wall of the blade.

[0050] Furthermore, the buffer plate and buffer column are prepared from prefabricated carbide, diamond particles and adhesive; the connecting plate is prepared from diamond particles and adhesive; and the buffer head is a polycrystalline diamond composite sheet.

[0051] Furthermore, the inner cavity of the blade is provided with a connecting cavity, a plurality of first hydraulic cavities and a plurality of second hydraulic cavities near the outer edge; the first hydraulic cavity and the second hydraulic cavity correspond one to one, the first hydraulic cavity, the connecting cavity and the second hydraulic cavity are sequentially connected from top to bottom and are filled with hydraulic medium; a plurality of L-shaped slow flow tubes are provided in the first hydraulic cavity, and a plurality of damping springs are connected to the top of the slow flow tube in the first hydraulic cavity through a sliding plate.

[0052] Furthermore, the top periphery of the connecting plate is rotatably connected to one end of the connecting column through a plurality of fixed seats, and the other end of the connecting column is rotatably connected to one end of the movable column through a rotating shaft; the other end of the movable column is connected to a hydraulic plug extending into the second hydraulic chamber, and the hydraulic plug is sealed and assembled with the inner wall of the second hydraulic chamber.

[0053] The working principle of the PDC drill bit of the present invention is as follows:

[0054] After the upper joint is assembled with the drilling equipment, the upper joint, the drill bit body, the lower joint and the blade rotate synchronously, and the multiple groups of cutting teeth rotate and cut synchronously. Since each group of cutting teeth is subjected to different impact forces, the buffer column is subjected to different impact forces, and the buffer column shrinks to squeeze the connecting plate. The spring damper cooperates with the buffer plate to play a good role in vibration reduction and impact resistance. The multiple fixed seats adaptively drive the connecting column and the moving column to move. The moving column squeezes the hydraulic medium in the second hydraulic chamber through the hydraulic plug, so that the hydraulic plug moves in the second hydraulic chamber. After the hydraulic medium is subjected to the impact force, it squeezes the sliding plate and the damping spring.

[0055] When the impact force on the cutting teeth is reduced, the energy stored in the damping spring, spring damper and hydraulic medium promotes the rebound recovery of the buffer column, thereby improving the impact resistance of the cutting teeth;

[0056] The blade and the drill body are subjected to impact force, which causes the torsion spring in the energy storage chamber to be compressed and store energy; when the PDC drill bit overcomes the resistance and reduces the rotation speed, the torsion spring releases energy, reduces the vibration of the blade and cutting teeth, and reduces the work done by the drill bit.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. The polycrystalline diamond composite sheet of the present invention is capable of meeting drill bits with different performance requirements by arranging the diamond layer into a hard phase layer and a soft phase layer, and designing hard phase layers and soft phase layers with different component contents and shape structures; in particular, the prefabricated carbides dispersed in the hard phase layer and the soft phase layer form bonds with the diamond grains. Since the elastic modulus of the carbides is lower than that of the polycrystalline diamond substrate, the impact energy is absorbed to alleviate the damage caused by the impact, a longer crack initiation period is provided, and the impact toughness is improved;

[0059] 2. When the hard substrate is a material incompatible with the polycrystalline diamond component, a transition layer is provided between the hard substrate and the hard phase layer, and prefabricated carbides are added in the transition layer, which can relieve the stress caused by the difference in thermal expansion coefficients between the hard phase layer and the hard substrate. The combined effect of the prefabricated carbides in the transition layer and the grooves on the surface of the hard substrate reduces the residual stress between the diamond layer and the hard substrate; further, by increasing the number of transition layers so that the content of prefabricated carbides is gradually reduced, the stress caused by the difference in thermal expansion coefficients can be further relieved;

[0060] 3. The composition of each soft phase layer, the particle size, shape, weight ratio of the preformed carbide and the binder of the present invention are the same or slightly different, and after forming multiple soft phase layers, the soft phase layers have successively progressive impact toughness or wear resistance; and the impact resistance of the soft phase layer is further improved by increasing the thickness of the soft phase layer and the content of the preformed carbide, and even the preformed carbide added to the hard phase layer increases the particle size of the diamond particles in the soft phase layer and the hard phase layer, thereby improving the overall impact resistance of the diamond layer;

[0061] 4. In the process of preparing prefabricated carbides, the types and ratios of raw transition metals and carbides are optimized, and a micro-nano mixed multi-scale composite material is formed by adopting a specific programmed heating, heat preservation sintering, hot pressing, and acid corrosion, so that the carbides present an irregular polyhedron or nearly spherical morphology. The elastic modulus of prefabricated carbides with various sizes and morphologies is lower than that of the polycrystalline diamond matrix. They can absorb more impact energy when dispersed in the polycrystalline diamond matrix, have good impact resistance, and relieve stress caused by differences in thermal expansion coefficients;

[0062] 5. The hard alloy material, hardened layer material, softened layer material and transition layer material of the present invention are obtained by ball milling, and can be assembled and processed into materials with different hierarchical structures, sizes and shapes according to the mold. The prepared polycrystalline diamond composite sheet has uniform quality and stable performance.

[0063] 6. In the PDC drill bit of the present invention, the impact-resistant buffer mechanism arranged inside the blade can buffer the impact force borne by multiple groups of cutting teeth and their gaps and adaptively adjust, thereby improving the impact resistance of the cutting teeth and increasing the service life of the PDC drill bit. The buffer energy storage mechanism arranged in the inner cavity of the drill bit body can accumulate impact energy during the operation of the drill bit, promote the rebound work of the blade, and reduce the work of the drill bit. When the buffer head made of wear-resistant and impact-resistant material is subjected to impact load, the dispersed carbides absorb the impact work to alleviate the damage caused by the impact, provide a longer crack initiation period, and improve the wear resistance and impact toughness of the PDC drill bit. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a schematic structural diagram of the wear-resistant and impact-resistant material of Example 1 of the present invention;

[0065] Figure 2 This is a schematic structural diagram of the wear-resistant and impact-resistant material of Example 2 of the present invention;

[0066] Figure 3 This is a schematic structural diagram of the wear-resistant and impact-resistant material of Example 3 of the present invention;

[0067] Figure 4 This is a schematic structural diagram of the wear-resistant and impact-resistant material of Example 4 of the present invention;

[0068] Figure 5This is a schematic structural diagram of the wear-resistant and impact-resistant material of Example 5 of the present invention;

[0069] Figure 6 This is a schematic structural diagram of the wear-resistant and impact-resistant material of Example 6 of the present invention;

[0070] Figure 7 It is a side view of the wear-resistant and impact-resistant material of Example 6 of the present invention;

[0071] Figure 8 Schematic diagram of the structure of a PDC drill bit according to Example 9 of the present invention;

[0072] Fig. 9 It is a schematic diagram of the impact-resistant buffer mechanism of the PDC drill bit of the present invention;

[0073] Fig.10 For the present invention Fig. 9 A partial enlarged view of the middle A;

[0074] Fig.11 It is a bottom view of the PDC drill bit of the present invention.

[0075] Figure numerals: 1. hard substrate; 2. diamond layer; 3. hard phase layer; 4. soft phase layer; 5. transition layer; 11. upper joint; 12. drill body; 13. lower joint; 14. blade; 15. cutting tooth; 16. buffer plate; 17. connecting plate; 18. buffer column; 19. spring damper; 20. buffer head; 21. fixed seat; 22. connecting column; 23. rotating shaft; 24. moving column; 25. first hydraulic chamber; 26. connecting chamber; 27. second hydraulic chamber; 28. hydraulic plug; 29. ​​sliding plate; 30. damping spring; 31. energy storage chamber; 32. torsion spring; 33. heat dissipation chamber; 34. rotating bearing; 35. slow flow tube. DETAILED DESCRIPTION

[0076] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0077] Example 1

[0078] like Figure 1 As shown, the polycrystalline diamond composite sheet structure of this embodiment comprises a hard substrate 1 and a diamond layer 2 arranged in sequence from bottom to top; the diamond layer 2 comprises a hard phase layer 3 and a soft phase layer 4 from bottom to top.

[0079] Example 2

[0080] like Figure 2As shown, the polycrystalline diamond composite sheet structure of this embodiment comprises a hard substrate 1, a transition layer 5 and a diamond layer 2 arranged in sequence from bottom to top, and the diamond layer 2 comprises a hard phase layer 3 and a soft phase layer 4 from bottom to top;

[0081] In order to relieve the stress between the hard substrate 1 and the hard phase layer 3 , a transition layer 5 is added on the basis of Example 1.

[0082] The transition layer 5 and the soft phase layer 4 are both a mixture of diamond particles, preformed carbides and a binder that are ball-milled; wherein the content of preformed carbides in the transition layer 5 is lower than that in the hard phase layer 3, and higher than that in the hard substrate 1, and can alleviate the stress caused by the difference in thermal expansion coefficients between the hard phase layer 3 and the hard substrate 1; the combined effect of the preformed carbides in the transition layer 5 and the grooves on the surface of the hard substrate 1 reduces the residual stress between the diamond layer and the hard substrate 1.

[0083] Example 3

[0084] like Figure 3 As shown, the polycrystalline diamond composite sheet structure of this embodiment comprises a hard substrate 1 and a diamond layer 2 arranged from bottom to top, and the diamond layer 2 is formed by a plurality of annular soft phase layers 4 and hard phase layers 3 nested in sequence, with the soft phase layer 4 being the outermost one.

[0085] The prefabricated carbide is dispersed in the polycrystalline diamond matrix of the soft phase layer 3 and forms a bond with the diamond grains. Since the elastic modulus of the carbide is lower than that of the polycrystalline diamond matrix, the carbide dispersed in the polycrystalline diamond matrix can absorb more impact energy.

[0086] When the wear-resistant and impact-resistant material is subjected to an impact load, the soft phase layer 4 distributed on the outermost side provides a certain amount of deformation to alleviate the damage caused by the impact and provide a longer crack initiation period; after the crack initiates, the multiple annular soft phase layers 4 repeatedly delay the crack expansion rate to further extend the service life. The crack has a slow expansion rate in the soft phase layer 4, so that the wear-resistant and impact-resistant material can still work normally after being subjected to multiple impact loads.

[0087] This embodiment can increase the impact toughness by successively increasing the content of preformed carbides and the particle size of diamond particles to effectively prevent the generation and expansion of cracks; or increase the wear resistance of the wear-resistant and impact-resistant material by successively reducing the content of preformed carbides and the particle size of diamond particles; so that multiple soft phase layers 4 have successively progressive impact toughness or wear resistance.

[0088] Example 4

[0089] like Figure 4As shown, the structure of the polycrystalline diamond composite sheet in this embodiment is improved on the basis of embodiment 3, and a transition layer 5 is provided between the hard substrate 1 and the diamond layer 2, and the transition layer 5 is a mixture formed by ball milling of prefabricated carbides, diamond particles, and a binder for forming polycrystalline diamond. The content of prefabricated carbides in the transition layer 5 is greater than that in the diamond layer 2, which can relieve the stress caused by the difference in thermal expansion coefficients between the diamond layer 2 and the hard substrate 1. The prefabricated carbides in the transition layer 5 and the surface grooves of the hard substrate 1 work together to reduce the residual stress between the diamond layer 2 and the hard substrate 1.

[0090] Example 5

[0091] like Figure 5 As shown, the polycrystalline diamond composite sheet structure of this embodiment is composed of a hard substrate 1 and a diamond layer 2. The diamond layer 2 includes a plurality of hard phase layers 3 with fan-shaped cross sections distributed in a ring array on the periphery, with spacing between adjacent hard phase layers 3. The area on the diamond layer 2 outside the hard phase layer 3 forms a soft phase layer 4.

[0092] The multiple fan-shaped hard phase layers 3 can provide good cutting performance, and the soft phase layer 4 provides good impact toughness. According to the performance requirements of the wear-resistant and impact-resistant material, the present embodiment can design hard phase layers 3 of different shapes and volumes, and can also change the content of prefabricated carbides in the soft phase layer 4; for example, the volume of the hard phase layer 3 can be increased or the content of prefabricated carbides in the soft phase layer 4 can be reduced to improve wear resistance; or the volume of the hard phase layer 3 can be reduced or the content of prefabricated carbides in the soft phase layer 4 can be increased to improve impact toughness.

[0093] Example 6

[0094] like Figure 6-7 As shown, the polycrystalline diamond composite sheet structure of this embodiment is composed of a hard substrate 1 and a diamond layer 2. The diamond layer 2 includes a hard phase layer whose upper and lower surfaces are both circular cuts and the chord length of the cross-section circular cut increases from far away from the hard substrate to close to the hard substrate. The area of ​​the diamond layer outside the hard phase layer is a soft phase layer.

[0095] The diamond layer 2 is located outside the hard phase layer 3 to form a soft phase layer 4, the soft phase layer 4 is a mixture of prefabricated carbide, diamond particles and adhesive by ball milling, and the hard phase layer 3 is a mixture of diamond particles and adhesive by ball milling; the hard phase layer 3 has an impact toughness that continuously increases from the inside to the outside. When subjected to an impact load, the hard phase layer 3 at the top outer edge of the diamond layer 2 provides deformation from the outside to the inside to alleviate the damage caused by the impact, thereby increasing the crack initiation period and extending the service life.

[0096] Example 7

[0097] This embodiment provides a method for processing a polycrystalline diamond compact, comprising the following steps:

[0098] Step 1: According to weight, 80 parts of diamond particles, 37 parts of prefabricated carbides and 4 parts of binder (cobalt powder) are weighed, mixed and then ball-milled to obtain a hard substrate material; according to weight, 92 parts of diamond particles and 2 parts of binder (cobalt powder) are weighed, mixed and then ball-milled to obtain a hard phase layer material; according to weight, 82 parts of diamond particles, 32 parts of prefabricated carbides and 5 parts of binder (cobalt powder) are weighed, mixed and then ball-milled to obtain a soft phase layer material; according to weight, 45 parts of diamond particles, 40 parts of prefabricated carbides and 1 part of binder (cobalt powder) are weighed, mixed and then ball-milled to obtain a transition layer material; wherein the prefabricated carbide is prepared from a material containing a transition metal element and a carbide, and the specific preparation process is as follows:

[0099] (1) According to weight parts, 32 parts of iron powder, 8 parts of nickel powder, 4 parts of cobalt powder, 5 parts of chromium carbide powder, 3 parts of titanium carbide powder and 1.5 parts of boron carbide powder are mixed to form a cylindrical compact, which is placed in a graphite mold for vacuum sintering, heated to 315° C. at a rate of 50° C. / min, vacuum degassed for 22 minutes, heated to 510° C., and kept warm for 16 minutes; heated to 1010° C. at a rate of 45° C. / min, kept warm for 26 minutes, and then stopped heating;

[0100] (2) When the temperature drops to 780°C, an impact force of 62 MPa is applied to the axial direction of the cylindrical compact, the pressure is maintained for 80 seconds, and the compact is cooled to room temperature to obtain a multiphase and multiscale composite material;

[0101] (3) the multiphase and multiscale composite material is crushed and placed in distilled water, a hydrochloric acid solution with a concentration of 38 wt% is added, the mixture is allowed to stand for 18 hours, filtered, washed with deionized water and anhydrous ethanol under ultrasound, and dried in vacuum to obtain a multiphase and multiscale granular prefabricated carbide;

[0102] Step 2: according to the hierarchical structure, size and shape specifications of the composite sheets of Examples 1-6, the hard alloy material, the hardened layer material, the softened layer material and the transition layer material are added into a mold adapted to the composite sheet, and mechanical static pressure is used to assemble and mold the blank;

[0103] Step three, sintering the blank at an impact force of 8 GPa and a temperature of 1580° C. for 3 minutes, cooling, and demolding to obtain a polycrystalline diamond composite sheet 1-6 having a hard substrate, a diamond layer, and a transition layer.

[0104] Example 8

[0105] This embodiment provides a method for processing a polycrystalline diamond compact, comprising the following steps:

[0106] Step 1, according to weight, weigh 80 parts of silicon carbide ceramics, 37 parts of prefabricated carbides and 4 parts of adhesives (iron powder and nickel powder are composed of 1:1 by mass), mix them evenly and then ball mill to obtain a hard substrate material; according to weight, weigh 87 parts of diamond particles and 3 parts of adhesives (iron powder and nickel powder are composed of 1:1 by mass), mix them evenly and then ball mill to obtain a hard phase layer material; according to weight, weigh 85 parts of diamond particles, 28 parts of prefabricated carbides and 8 parts of adhesives (iron powder and nickel powder are composed of 1:1 by mass), mix them evenly and then ball mill to obtain a soft phase layer material; according to weight, weigh 62 parts of diamond particles, 43 parts of prefabricated carbides and 2 parts of adhesives (iron powder and nickel powder are composed of 1:1 by mass), mix them evenly and then ball mill to obtain a transition layer material; wherein the prefabricated carbide is prepared from a material containing a transition metal element and a carbide, and the specific preparation process is as follows:

[0107] (1) According to weight parts, 10 parts of iron powder, 8 parts of nickel powder, 6 parts of cobalt powder, 5 parts of chromium carbide powder, 5 parts of niobium carbide powder and 3 parts of titanium carbide powder are mixed to form a cylindrical compact, which is placed in a graphite mold for vacuum sintering, heated to 315° C. at a rate of 50° C. / min, vacuum degassed for 22 minutes, heated to 510° C., and kept warm for 16 minutes; heated to 1010° C. at a rate of 45° C. / min, kept warm for 26 minutes, and then stopped heating;

[0108] (2) When the temperature drops to 790°C, an impact force of 65 MPa is applied to the axial direction of the cylindrical compact, the pressure is maintained for 100 seconds, and the compact is cooled to room temperature to obtain a multiphase and multiscale composite material;

[0109] (3) the multiphase and multiscale composite material is crushed and placed in distilled water, a hydrochloric acid solution with a concentration of 38 wt% is added, the mixture is allowed to stand for 18 hours, filtered, washed with deionized water and anhydrous ethanol under ultrasound, and dried in vacuum to obtain a multiphase and multiscale granular prefabricated carbide;

[0110] Step 2: according to the hierarchical structure, size and shape specifications of the composite sheets of Examples 1-6, the hard alloy material, the hardened layer material, the softened layer material and the transition layer material are added into a mold adapted to the composite sheet, and mechanical static pressure is used to assemble and mold the blank;

[0111] Step three, sintering the blank at an impact force of 7 GPa and a temperature of 1470° C. for 6 minutes, cooling, and demolding to obtain a polycrystalline diamond composite sheet 7-12 having a hard substrate, a diamond layer, and a transition layer.

[0112] Comparative Example 1

[0113] The control composite tablet was prepared according to the preparation method of Example 2 of patent CN201410846572.1.

[0114] Comparative Example 2

[0115] A polycrystalline diamond composite sheet 13 is obtained by adopting the hierarchical structure, size and specification of the composite sheet of Example 1 and referring to the preparation method of Example 7, except that the impact pressure in step 3 of Example 7 is increased from 8 GPa to 12 GPa.

[0116] Test Case

[0117] Hardness test: Process a cylindrical test piece with a diameter of 20 mm and a height of 15 mm; load a force of 10 N and maintain the pressure for 20 seconds, make 10 indentations, and use a micro hardness tester to test the average hardness.

[0118] Wear weight test: Fix the cylindrical test piece on the lathe tool holder, fix the cylindrical rock on the lathe turntable, and cut the rock with the cylindrical test piece while rotating the rock. Measure the wear amount of the cylindrical test piece when it travels a certain distance or removes a certain volume of rock; the rock used in the experiment is granite.

[0119] The hardness and wear ratio test results are shown in Table 1;

[0120] Table 1 Hardness and wear ratio of polycrystalline diamond composite sheets of embodiment and comparative example

[0121]

[0122] It can be seen from Examples 1-6 that the performance of the wear-resistant and impact-resistant material can be easily adjusted and controlled to adapt to a wide range of working conditions; if it is necessary to increase the impact resistance of the wear-resistant and impact-resistant material, the content of the prefabricated carbide can be gradually reduced by increasing the number of transition layers to alleviate the stress caused by the difference in thermal expansion coefficients, or the impact resistance of the soft phase layer can be further improved by increasing the thickness of the soft phase layer and the content of the prefabricated carbide, and even the prefabricated carbide added to the hard phase layer can increase the particle size of the diamond particles in the soft phase layer and the hard phase layer, thereby improving the overall impact resistance of the diamond layer.

[0123] The processing method of the polycrystalline diamond composite sheet in the embodiment of the present invention adopts a ball milling mixing method to obtain a cemented carbide material, a hardening layer material, a softening layer material and a transition layer material. After assembling the materials of each layer according to the specifications of the composite sheet, the materials are sintered at high temperature and high pressure, cooled, and demolded to obtain the wear-resistant and impact-resistant material. Compared with the prior art, the adapted mold assembly can process materials of different hierarchical structures, sizes, and shapes while maintaining uniform quality and stable performance. By adding prefabricated carbides into the softening layer and the transition layer, the elastic modulus of the prefabricated carbides is lower than the elastic modulus of the polycrystalline diamond matrix. When the wear-resistant and impact-resistant material is subjected to an impact load, the carbides dispersed in the soft phase layer absorb the impact energy to alleviate the damage caused by the impact, providing a longer crack initiation period, and improving the impact toughness and wear resistance relative to the prior art.

[0124] Example 9

[0125] like Figure 8 As shown, this embodiment provides a PDC drill bit, including an upper joint 11, a drill bit body 12, a lower joint 13 and a blade wing 14 arranged in sequence from top to bottom; the lower joint 13 is connected to the drill bit body 12 through a rotating bearing 34; a plurality of groups of cutting teeth 15 are distributed on the outer wall of the blade wing 14 (the bottom view is as shown in FIG. Fig.11 As shown), the interior of the blade 14 is provided with an impact-resistant buffer mechanism; the inner cavity of the drill body 12 is provided with a buffer energy storage mechanism.

[0126] The PDC drill bit improves the basic structure of the upper joint 11, the drill bit body 12, the lower joint 13 and the blade wing 14. The impact-resistant buffer mechanism arranged inside the blade wing 14 can buffer the impact force borne by multiple groups of cutting teeth 15 and the gaps therein and adjust adaptively, thereby improving the impact resistance of the cutting teeth 15 and increasing the service life of the PDC drill bit. The buffer energy storage mechanism arranged in the inner cavity of the drill bit body 12 can accumulate impact energy during the operation of the drill bit, promote the rebound work of the blade wing 14, and reduce the work of the drill bit.

[0127] Specifically, Figure 8 , Fig. 9 As shown, the impact-resistant buffer mechanism includes a buffer plate 16, a connecting plate 17 and a buffer column 18; the buffer plate 16 is fixedly connected to the bottom of the lower joint 13, and the bottom center of the buffer plate 16 is fixedly connected to the top center of the connecting plate 17 through a spring damper 19; a plurality of buffer columns 18 are fixed to the bottom of the connecting plate 17 and extend toward the outer wall of the blade 14, and a buffer head 20 is provided at the end of the buffer column 18. The material of the buffer plate 16 and the buffer column 18 is a mixture of prefabricated carbide, diamond particles and adhesive ball milling.

[0128] The preparation method of the prefabricated carbide in the buffer plate 16 and the buffer column 18 is:

[0129] Step 1: According to weight parts, 25 parts of iron powder, 6 parts of nickel powder, 5 parts of cobalt powder, 7 parts of chromium carbide powder, 3 parts of titanium carbide powder and 2 parts of boron carbide powder are mixed to form a cylindrical compact, which is placed in a graphite mold for vacuum sintering, heated to 315°C at a rate of 50°C / min, vacuum degassed for 22 minutes, heated to 510°C, and kept warm for 16 minutes; heated to 1010°C at a rate of 45°C / min, kept warm for 26 minutes, and then stopped heating;

[0130] Step 2, when the temperature drops to 780°C, an impact force of 62 MPa is applied to the axial direction of the cylindrical compact, the pressure is maintained for 80 seconds, and the compact is cooled to room temperature to obtain a multi-phase and multi-scale composite material;

[0131] Step three, crush the multiphase and multiscale composite material and place it in distilled water, add a 38wt% hydrochloric acid solution, let it stand for 18 hours, filter it, wash it with deionized water and anhydrous ethanol under ultrasound, and vacuum dry it to obtain a multiphase and multiscale granular prefabricated carbide.

[0132] According to the weight percentage, 8 parts of prefabricated carbide, 15 parts of 15-20um diamond powder, and 3 parts of cobalt binder are ball-milled and sintered at 1400°C and 7.2GPa for 18 minutes. The product is demolded to obtain the buffer plate 16 and the buffer column 18.

[0133] The material of the connecting plate 17 is a mixture of 15-25um diamond particles and nickel adhesive ball-milled; the structure and material of the buffer head 20 are selected from any one of the polycrystalline diamond composite sheets of Examples 1-6. The elastic modulus of the prefabricated carbide of the polycrystalline diamond composite sheet is lower than the elastic modulus of the polycrystalline diamond matrix. When the polycrystalline diamond composite sheet is subjected to an impact load, the carbide dispersed in the soft phase layer 4 absorbs the impact energy to alleviate the damage caused by the impact, providing a longer crack initiation period, and improving the impact toughness relative to the prior art.

[0134] like Fig. 9 , Fig.10 As shown, the top periphery of the connecting plate 17 is rotatably connected to one end of the connecting column 22 through a plurality of fixing seats 21, and the other end of the connecting column 22 is rotatably connected to one end of the moving column 24 through a rotating shaft 23; the inner cavity of the blade 14 is provided with a plurality of first hydraulic chambers 25, connecting chambers 26 and second hydraulic chambers 27 near the outer edge, and each blade of the drill bit has at least one first hydraulic chamber 25, connecting chamber 26 and second hydraulic chamber 27. In this embodiment, each blade has a set of first hydraulic chamber 25, connecting chamber 26 and second hydraulic chamber 27, and there are a total of 6 sets of first hydraulic chamber 25, connecting chamber 26 and second hydraulic chamber 27. The hydraulic chambers 27 are connected in sequence from top to bottom and are filled with hydraulic medium; the other end of the movable column 24 is connected to a hydraulic plug 28 extending into the second hydraulic chamber 27, and the hydraulic plug 28 is sealed and assembled with the inner wall of the second hydraulic chamber 27; wherein, the cross-sectional area of ​​the connecting chamber 24 is smaller than the cross-sectional area of ​​the first hydraulic chamber 24 and the second hydraulic chamber 27, and the cross-sectional area of ​​the second hydraulic chamber 24 is smaller than the cross-sectional area of ​​the first hydraulic chamber 24; a plurality of L-shaped slow flow tubes 35 are arranged in the first hydraulic chamber 24, and a plurality of damping springs 30 are connected to the top of the slow flow tube 27 in the first hydraulic chamber 24 through a sliding plate 29.

[0135] When the PDC drill bit is drilling, multiple groups of cutting teeth 15 are synchronously rotated and cut. Due to the difference in the material of the drilling rock and soil, each group of cutting teeth 15 is subjected to different impact forces, and the buffer head 20 is subjected to different impact forces. The buffer column 18 shrinks to squeeze the connecting plate 17, and the spring damper 19 cooperates with the buffer plate 16 to play a good role in damping and resisting impact forces. Multiple fixed seats 21 adaptively drive the connecting column 22 and the moving column 24 to move. The moving column 24 squeezes the hydraulic medium in the second hydraulic chamber 27 through the hydraulic plug 28, so that the hydraulic plug 28 moves in the second hydraulic chamber 27. After the hydraulic medium is subjected to the impact force, it squeezes the sliding plate 29 and the damping spring 30. When the impact force on the cutting tooth 15 is reduced, the energy stored in the damping spring 30, the spring damper 19 and the hydraulic medium promotes the rebound recovery of the buffer column 18, thereby improving the impact resistance of the cutting tooth 15.

[0136] like Fig. 9 As shown, the buffer energy storage mechanism includes an energy storage chamber 31 located at the periphery of the inner cavity of the drill body 12, a torsion spring 32 is fastened and assembled in the energy storage chamber 31, and the top of the energy storage chamber 31 is connected to a heat dissipation chamber 33 that penetrates the upper joint 11; when the PDC drill bit accelerates and rotates, the blade 14 and the drill body 12 are subjected to the impact force so that the torsion spring 32 in the energy storage chamber 31 is compressed and energy is stored; when the PDC drill bit overcomes the resistance and reduces the rotation speed, the torsion spring 32 releases energy, reduces the vibration of the blade 14 and the cutting tooth 15, and reduces the work done by the cutting tooth 15.

[0137] The PDC drill bit of the present invention has an impact-resistant buffer mechanism arranged inside the blade wing, which can buffer the impact force borne by multiple groups of cutting teeth and the gaps therein and adaptively adjust, thereby improving the impact resistance of the cutting teeth and increasing the service life of the PDC drill bit. The buffer energy storage mechanism arranged in the inner cavity of the drill bit body can accumulate impact energy during the operation of the drill bit, promote the rebound work of the blade wing, and reduce the work of the drill bit. When the buffer head made of wear-resistant and impact-resistant material is subjected to impact load, the dispersed carbides absorb the impact work to alleviate the damage caused by the impact, provide a longer crack initiation period, and improve the wear resistance and impact toughness of the PDC drill bit.

[0138] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A polycrystalline diamond composite sheet, characterized in that: It comprises a diamond layer and a hard substrate; the diamond layer comprises a hard phase layer and a soft phase layer, wherein the hard phase layer is close to one side of the hard substrate; The hard phase layer comprises diamond particles; the soft phase layer comprises: diamond particles, prefabricated carbide and adhesive.

2. The polycrystalline diamond compact according to claim 1, characterized in that: The hard phase layer comprises 82-96 parts of diamond particles, 0-20 parts of prefabricated carbide and 0-6 parts of adhesive in terms of weight; the soft phase layer comprises 65-86 parts of diamond particles, 23-37 parts of prefabricated carbide and 1-15 parts of adhesive in terms of weight.

3. The polycrystalline diamond compact according to claim 1, characterized in that: The hard substrate includes: any one of metal, alloy, ceramic and metal-based ceramic, as well as prefabricated carbide and adhesive.

4. The polycrystalline diamond compact according to claim 1, characterized in that: The prefabricated carbide is prepared from a material containing a transition metal element and a carbide, and the specific preparation method is as follows: (1) Mixing a material containing a transition metal element and a carbide to form a cylindrical compact, and setting a temperature rise program for sintering; (2) cooling to 770-790°C and applying axial pressure to the cylindrical compact; Cooling to room temperature, a multi-phase and multi-size composite material is obtained; (3) The multi-phase and multi-size composite material is crushed, a hydrochloric acid solution is added, the mixture is allowed to stand, and suction filtered; the filter residue is washed and dried to obtain the obtained product.

5. The polycrystalline diamond compact according to claim 4, characterized in that: The material containing transition metal elements includes at least one of iron powder, cobalt powder, nickel powder, iron alloy, cobalt alloy and nickel alloy; the carbide is at least one of tungsten carbide, rhenium carbide, chromium carbide, titanium carbide, boron carbide, gravel and flame sprayed pre-sintered sand.

6. The polycrystalline diamond compact according to claim 5, characterized in that: The material containing transition metal elements includes, by weight of the transition metal elements, 5-36 parts of iron powder and / or iron alloy, 2-12 parts of nickel powder and / or nickel alloy, and 1-6 parts of cobalt powder and / or cobalt alloy; the carbide includes, by weight, 3-8 parts of chromium carbide, 1-4 parts of titanium carbide, and 0.6-3 parts of boron carbide.

7. The prefabricated carbide according to claim 4, characterized in that: The temperature raising procedure is: raising the temperature to 300-325°C at a rate of 40-55°C / min, vacuum degassing for 15-30min, then raising the temperature to 500-520°C at a rate of 40-55°C / min, and keeping the temperature for 10-20min; Raise the temperature to 950-1030°C at a rate of 35-50°C / min and keep warm for 20-30 minutes.

8. The polycrystalline diamond compact according to claim 4, characterized in that: In step (3), the concentration of the hydrochloric acid solution is 35-40wt%; the standing time is 16-20h; and the washing is carried out using deionized water and anhydrous ethanol in sequence.

9. The polycrystalline diamond compact according to any one of claims 1 to 8, characterized in that: A transition layer is provided between the diamond layer of the polycrystalline diamond composite sheet and the hard substrate.

10. The polycrystalline diamond compact according to claim 9, characterized in that: The transition layer includes diamond particles, prefabricated carbide and a binder.

11. The polycrystalline diamond compact according to claim 9, characterized in that: The transition layer comprises 40-67 parts of diamond particles, 32-47 parts of prefabricated carbides and 1-18 parts of adhesives in terms of weight.

12. The polycrystalline diamond compact according to claim 1, characterized in that: The structure of the polycrystalline diamond composite sheet is: A hard phase layer is disposed on one side of the hard substrate and the hard phase layer covers the side of the hard substrate, and a soft phase layer is disposed on the side of the hard phase layer away from the hard substrate and the soft phase layer covers the side of the hard phase layer; Or a diamond layer is arranged on one side of the hard substrate, which is composed of multiple annular soft phase layers and hard phase layers nested in sequence along the radial direction, and the diamond layer distributed on the outermost side is the soft phase layer; Or a plurality of hard phase layers with fan-shaped cross sections are arranged on one side of the hard substrate in an annular array and distributed on the periphery, with spacing between adjacent hard phase layers, and the area where the diamond layer is located outside the hard phase layer is the soft phase layer; Or a hard phase layer is arranged on one side of the hard substrate, with both the upper and lower surfaces being circular cuts and the chord length of the cross-section circular cuts increasing from far away from the hard substrate to close to the hard substrate, and the area where the diamond layer is located outside the hard phase layer is the soft phase layer.

13. The method for preparing a polycrystalline diamond compact according to any one of claims 1 to 12, characterized in that: The following steps are involved: (1) preparing hard substrate material, hard phase layer material, soft phase layer material and transition layer material; (2) According to the structure of the polycrystalline diamond composite sheet, the hard substrate material, the hard phase layer material, the soft phase layer material and the transition layer material are added into the mold, mechanically statically pressed, and molded into a blank; (3) After the blank is sintered, it is cooled and demoulded.

14. The preparation method according to claim 13, characterized in that: In step (1), the hard substrate material, hard phase layer material, soft phase layer material and transition layer material are prepared by mixing raw materials in proportion and then ball milling.

15. The preparation method according to claim 13, characterized in that: In step (3), the sintering conditions are: impact force 5-10 GPa, temperature 1300-1700° C., and sintering time 0.5-15 min.

16. Use of the polycrystalline diamond compact according to any one of claims 1 to 12 or the polycrystalline diamond compact prepared by the preparation method according to any one of claims 13 to 15 in a PDC drill bit.

17. A PDC drill bit, characterized in that: The drill bit is prepared by using the polycrystalline diamond composite sheet described in any one of claims 1 to 12 or the polycrystalline diamond composite sheet prepared by the preparation method described in any one of claims 13 to 15 as the buffer head material.

18. The PDC drill bit according to claim 17, characterized in that The PDC drill bit is provided with an upper joint, a drill bit body, a lower joint and a blade from top to bottom in sequence; a buffer energy storage mechanism is provided in the inner cavity of the drill bit body; the lower joint is connected to the drill bit body through a rotating bearing; a plurality of groups of cutting teeth are distributed on the outer wall of the blade, and an impact-resistant buffer mechanism is provided inside the blade.

19. The PDC drill bit according to claim 18, characterized in that The impact-resistant buffer mechanism includes a buffer plate, a connecting plate and a plurality of buffer columns; a buffer head is provided at the end of the buffer column; the buffer plate is fixedly connected to the bottom of the lower joint, and the bottom center of the buffer plate is fixedly connected to the top center of the connecting plate through a spring damper; the plurality of buffer columns are fixed to the bottom of the connecting plate and extend toward the outer wall of the blade.

20. The PDC drill bit according to claim 19, characterized in that The buffer plate and buffer column are prepared from prefabricated carbide, diamond particles and adhesive; the connecting plate is prepared from diamond particles and adhesive; and the buffer head is a polycrystalline diamond composite sheet.

21. The PDC drill bit according to claim 18, characterized in that The inner cavity of the blade wing is provided with a connecting cavity, a plurality of first hydraulic cavities and a plurality of second hydraulic cavities near the outer edge; the first hydraulic cavity corresponds to the second hydraulic cavity one by one; the first hydraulic cavity, the connecting cavity and the second hydraulic cavity are connected in sequence from top to bottom and are filled with hydraulic medium; a plurality of L-shaped slow flow tubes are provided in the first hydraulic cavity, and a plurality of damping springs are connected to the top of the slow flow tube in the first hydraulic cavity through a sliding plate; there is at least one hydraulic cavity in each blade wing.

22. The PDC drill bit according to claim 19, characterized in that The top periphery of the connecting plate is rotatably connected to one end of the connecting column through a plurality of fixed seats, and the other end of the connecting column is rotatably connected to one end of the moving column through a rotating shaft; the other end of the moving column is connected to a hydraulic plug extending into the second hydraulic chamber, and the hydraulic plug is sealed and assembled with the inner wall of the second hydraulic chamber.

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