PcBN / cvd diamond composite material reinforced impregnated diamond bit

Abstract

The application belongs to the technical field of drill bits for geological and mineral exploration, and provides a PcBN / CVD diamond composite reinforced impregnated diamond drill bit, which comprises a steel body, a matrix body connected with the steel body, and diamond particles distributed in the matrix body; each matrix block of the matrix body is respectively embedded with a PcBN / CVD diamond composite column, which comprises: a strip-shaped CVD diamond located at a central part of the PcBN / CVD diamond composite; and a PcBN coating layer wrapped and sintered outside the strip-shaped CVD diamond; the lip surface of the drill bit forms a three-stage gradient cutting structure with increasing height from outside to inside, the diamond particle has the lowest cutting height, the PcBN coating layer has the second lowest cutting height, and the strip-shaped CVD diamond has the highest cutting height. The application forms a structure with a gradient decrease in wear resistance from the center to the outside, significantly prolongs the service life of the drill bit, improves the drilling efficiency, and reduces the secondary wear of the drill bit lip surface by rock debris.

Description

Technical Field

[0001] This invention belongs to the field of drill bit technology for geological and mineral exploration, and particularly relates to PcBN / CVD diamond composite reinforced impregnated diamond drill bits. Background Technology

[0002] As mineral resource exploration moves towards deeper exploration, drilling targets are gradually shifting from medium-hard rock formations to hard, dense, and poorly drillable strata such as granite and basalt.

[0003] Currently, the most commonly used ultrahard cutting materials in geological drilling are diamond particles and polycrystalline diamond composites (PDC). Drill bits using PDC as the rock-breaking material are called PDC drill bits. PDC drill bits perform well in soft to medium-hard formations, but their cutting teeth are prone to thermal wear and chipping in hard and highly abrasive formations. Another commonly used drill bit is the impregnated diamond drill bit. Although impregnated diamond drill bits are widely used in hard rock drilling, they rely on diamond particles dispersed in the matrix to grind and break the rock. However, they still suffer from low drilling efficiency, excessively fast diamond exit speed, or diamond detachment. Especially in highly abrasive hard rock, the drill bit wear rate is extremely high, resulting in a short lifespan and requiring frequent tripping in and out, increasing non-productive time. Therefore, developing a new type of ultrahard composite material drill bit that combines high wear resistance and high impact resistance, and can effectively improve the service life of impregnated drill bits in hard rock, is a key problem that urgently needs to be solved in current deep hard rock drilling technology.

[0004] Polycrystalline cubic boron nitride (PcBN) and chemical vapor deposition (CVD) diamond are two high-performance superhard materials, but neither has its limitations when used alone for drilling: PcBN has lower hardness and wear resistance than diamond, limiting its rock-breaking effectiveness when used alone; CVD diamond for tools is generally in millimeter-thick sheets, which are then cut into strips. While it has excellent hardness and wear resistance, it is brittle and has poor impact resistance, making it unsuitable as a standalone rock-breaking material for drilling. Current technology has not yet solved the problem of how to effectively combine these two materials and apply them to drill bit design. Summary of the Invention

[0005] The purpose of this invention is to provide PcBN / CVD diamond composite reinforced impregnated diamond drill bits, aiming to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] On the one hand, the present invention provides a PcBN / CVD diamond composite reinforced impregnated diamond drill bit, the drill bit comprising a steel body and a matrix connected to the steel body, wherein diamond particles are distributed in the matrix;

[0008] Each block of the tire carcass is embedded with a PcBN / CVD diamond composite material pillar, wherein the PcBN / CVD diamond composite material pillar comprises:

[0009] Strip-shaped CVD diamond is located at the center of the PcBN / CVD diamond composite material;

[0010] A PcBN coating layer is formed and sintered onto the outside of the strip-shaped CVD diamond.

[0011] The drill bit's lip surface forms a three-level gradient cutting edge structure with increasing height from the outside to the inside. The diamond particle cutting edge height is the lowest, followed by the PcBN coating layer, and the strip-shaped CVD diamond cutting edge height is the highest.

[0012] On the other hand, the present invention provides a method for preparing a PcBN / CVD diamond composite reinforced impregnated diamond drill bit, comprising the following steps:

[0013] S1. Preparation of mixed particle size cBN (cubic boron nitride) raw materials: Mixed particle size cBN powder is prepared by ball milling. The mixed particle size cBN powder is formed by uniformly mixing three types of cBN particles with particle size concentrations of 20μm, 8μm and 2μm in a mass ratio of 10:7:3.

[0014] S2. Preparation of PcBN powder raw materials: Mix cBN powder of mixed particle size with Al powder, add anhydrous ethanol and wet mix in a ball mill, vacuum dry and then sieve to obtain mixed powder;

[0015] S3. The mixed powder is pre-pressed into a cylindrical blank on a tablet press. A cuboid groove is made along the axial direction in the center of the blank, and a strip of CVD diamond is inserted. The blank is pre-pressed and fixed again. The blank is placed in a six-sided press and held at 5.5 GPa and 1500℃ for 10 min. After sintering, it is ground and polished to obtain a PcBN / CVD diamond composite column.

[0016] S4. Mix diamond particles and matrix powder evenly, load the resulting matrix mixture into a graphite mold, pre-reserve a hole at the center of each matrix block, insert a PcBN / CVD diamond composite column, fill the surrounding area with matrix mixture, place a steel body on top, place the graphite mold in a hot pressing sintering equipment, and perform hot pressing sintering at 850-950℃ and 15-25MPa to firmly bond the PcBN / CVD diamond composite column with the matrix, open a water gate on the drill bit lip, and embed diamond polycrystals on the outer and inner diameters of the matrix respectively.

[0017] Compared with the prior art, the specific beneficial effects of the present invention are as follows:

[0018] This invention embeds PcBN / CVD diamond composite material pillars into the drill bit matrix. By utilizing the high wear resistance and gradient-change wear resistance of the composite material pillars, the contact mode between the drill bit lip and the rock at the bottom of the hole is changed, so that the drill bit forms a structure with wear resistance gradient decreasing from the center to the outside, which significantly extends the life of the drill bit.

[0019] During the drilling process, the strip-shaped CVD diamond core with the highest hardness is pressed into the rock first, generating stress concentration and causing brittle fracture of the rock; then the PcBN coating layer plows the broken rock; finally, the fine diamond particles in the matrix are ground and trimmed, realizing a composite rock breaking mode of fracturing, shearing, plowing and grinding, which improves rock breaking efficiency.

[0020] Because the wear resistance of the composite material core is higher than that of the matrix, a multi-level gradient cutting edge structure of strip-shaped CVD diamond-PcBN-matrix diamond is formed on the drill bit lip during drilling. This cutting edge structure has a good self-sharpening function: when the strip-shaped CVD diamond wears down to the PcBN coating layer, the PcBN coating layer takes over the cutting task; as the PcBN coating layer wears down, the strip-shaped CVD diamond core is exposed again, restoring the cutting ability.

[0021] The presence of composite material columns increases the gap between the drill bit lip and the rock, which facilitates drilling fluid flow and cuttings removal, reduces secondary wear of the drill bit lip by cuttings, and reduces drilling torque by 10-15%.

[0022] This invention employs a powder metallurgy secondary sintering process. First, the PcBN / CVD diamond composite material column is sintered and formed under high temperature and pressure, and then embedded in the matrix for hot pressing sintering. This avoids the high-temperature damage to the strip-shaped CVD diamond during the drill bit sintering process and ensures a reliable bond between the composite material column and the matrix. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a PcBN / CVD diamond composite reinforced impregnated diamond drill bit provided in an embodiment of the present invention;

[0024] Figure 2 This is a cross-sectional view of the drill bit matrix provided in an embodiment of the present invention;

[0025] Figure 3 This is a top view of the drill bit lip surface provided in an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of a PcBN / CVD diamond composite column provided in an embodiment of the present invention;

[0027] Figure 5The following are actual pictures of the drill bit provided in Embodiment 3 of the present invention: a is a lip view of the drill bit before use, b is a front view of the drill bit before use, and c is a lip view of the drill bit after use.

[0028] In the attached diagram: 1-matrix, 2-PcBN coating layer, 3-strip CVD diamond, 4-diamond particles, 5-sprue, 6-diamond polycrystal, 7-steel body. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0031] Example 1: A PcBN / CVD diamond composite reinforced impregnated diamond drill bit, such as... Figures 1 to 3 As shown, the drill bit includes a steel body 7 and a matrix 1 connected to the steel body 7, wherein diamond particles 4 are distributed in the matrix 1.

[0032] Each block of the tire carcass 1 is respectively inlaid with a PcBN / CVD diamond composite material pillar at its center. The PcBN / CVD diamond composite material pillar is as follows: Figure 4 As shown, it specifically includes:

[0033] The strip-shaped CVD diamond 3 is located in the center of the PcBN / CVD diamond composite material, and can be a cuboid with a side length of 1mm and a length of 4mm.

[0034] The PcBN coating layer 2 is sintered on the outside of the strip-shaped CVD diamond 3, and can be a cylinder with a diameter of 3 mm and a height of 4 mm.

[0035] The outer and inner diameters of the matrix 1 are respectively inlaid with polycrystalline diamond 6;

[0036] The drill bit has a water inlet 5 on its lip surface, and the water inlet 5 is located between adjacent blocks.

[0037] The drill bit's lip surface forms a three-level gradient cutting edge structure with increasing height from the outside to the inside. The diamond particle 4 has the lowest cutting edge height, followed by the PcBN coating layer 2, and the strip-shaped CVD diamond 3 has the highest cutting edge height. This three-level gradient cutting edge structure enables the drill bit to break rocks in a composite rock breaking mode that combines the fracturing and shearing volumetric crushing of the strip-shaped CVD diamond 3, the plowing and grinding of the PcBN coating layer 2, and the cutting and grinding of the diamond particle 4.

[0038] Example 2: A method for preparing a PcBN / CVD diamond composite reinforced impregnated diamond drill bit, comprising the following steps:

[0039] S1. Preparation of mixed particle size cBN raw materials: Mixed particle size cBN powder was prepared by ball milling. The mixed particle size cBN powder was formed by uniformly mixing three types of cBN particles with particle size concentrations of 20μm, 8μm and 2μm in a mass ratio of 10:7:3. Its particle size distribution was designed based on the Dinger-Funk close packing model, with a distribution index n=0.37.

[0040] S2. Preparation of PcBN powder raw materials: Mix cBN powder with Ti2AlC powder and Al powder with a diameter of 1μm at a ratio of 80wt%, 16wt%, and 4wt%, respectively. Add anhydrous ethanol and wet mix in a planetary ball mill at 400rpm for 2h. After vacuum drying at 80℃, sieve the mixture. Pre-press the mixed powder into a cylindrical blank with a diameter of 3.3mm and a height of 9mm on a tablet press. Make a 1mm×1mm groove along the axial direction in the center of the blank and insert a 1mm×1mm×4mm CVD diamond strip 3. Pre-press again to fix it. Place the blank in a six-sided top press and heat it at 5.5GPa and 1500℃ for 10min. After sintering, grind and polish to obtain a PcBN / CVD diamond composite column with a diameter of 3mm.

[0041] S4. Drill bit preparation: Using drill bit design parameters of 59mm outer diameter, 41mm inner diameter, and 9mm working layer height, diamond particles 4 and matrix powder are mixed evenly according to the FB-YX-60 / 41.5-C9-K9 series conventional impregnated diamond drill bit matrix formula. A graphite mold is designed with a bottom mold inner diameter of 59.19mm and a core mold outer diameter of 41.13mm. The matrix mixture is loaded into the graphite mold, and a 3.1mm diameter hole is reserved in the center of each matrix block. The aforementioned P is then inserted. The PcBN / CVD diamond composite column is surrounded by a matrix mixture, and a steel body 7 is placed on top. The graphite mold is placed in a hot pressing sintering equipment and hot pressing sintered at 900℃ and 20MPa to firmly bond the PcBN / CVD diamond composite column to the matrix 1. Six sprue 5s are opened on the lip of the drill bit. The specific dimensions of the sprue 5 can be 5mm wide and 9.5mm high. Three polycrystalline diamond 6s are inlaid on the outer diameter of the matrix 1 and two polycrystalline diamond 6s are inlaid on the inner diameter.

[0042] Drilling Test: On a geological core drilling rig, drilling was conducted on granite with a drillability grade of VIII using parameters of 10 kN drilling pressure, 574 rpm rotation speed, and 30 L / min flushing fluid pump flow rate. The results showed that the wear per meter of the drill bit provided in this embodiment of the invention was 0.23 mm / m; while the wear per meter of the conventional impregnated diamond drill bit of the same specification was 1.08 mm / m. The unit wear of the drill bit provided in this embodiment of the invention was only 21.3% of that of the conventional drill bit. Within the effective working layer of the PcBN / CVD diamond composite column, the drill bit life was increased by 4.69 times, and the average torque during drilling was 93 N·m, which was 14.2% lower than that of the conventional drill bit (108.4 N·m).

[0043] After drilling, the drill bit lip surface is observed to show that the strip-shaped CVD diamond 3 in the center of the PcBN / CVD diamond composite column is exposed, and the surrounding PcBN coating layer 2 forms a wear-resistant support. The diamond particles 4 in the matrix 1 are distributed in a streamlined cutting edge distribution, forming an obvious multi-level gradient cutting edge structure.

[0044] When the drilling target was changed to granite with a drillability grade of VII, the results showed that the wear per meter of the drill bit provided in this embodiment of the invention was 0.14 mm / m, while the wear per meter of the conventional drill bit was 0.32 mm / m. The life of the drill bit in this embodiment of the invention was increased by 2.28 times compared with the conventional drill bit, and the average torque was 91.8 N·m, which was 12.3% lower than that of the conventional drill bit (104.7 N·m).

[0045] Example 2: Compared with Example 1, the only difference is that in S2, cBN powder and Al powder with mixed particle size are mixed in a ratio of 80wt% and 20wt%, respectively.

[0046] Drilling test: Drilling was conducted on granite with a drillability grade of VIII under the same conditions. The lip surface of the drill bit before use was as follows: Figure 5 As shown in Figure a, the front view of the drill bit before use is as follows. Figure 5 As shown in Figure b, the lip surface of the drill bit after use is as follows: Figure 5 As shown in Figure c, the wear per meter of the drill bit in this embodiment of the invention is 0.17 mm / m, and its lifespan is increased by approximately 6.37 times compared to conventional drill bits.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A PcBN / CVD diamond composite reinforced impregnated diamond drill bit, characterized in that, The drill bit includes a steel body (7) and a matrix (1) connected to the steel body (7), wherein diamond particles (4) are distributed in the matrix (1). Each block of the carcass (1) is inlaid with a PcBN / CVD diamond composite material pillar, wherein the PcBN / CVD diamond composite material pillar comprises: Strip-shaped CVD diamond (3) is located at the center of the PcBN / CVD diamond composite material; A PcBN coating layer (2) is sintered over the outside of the strip-shaped CVD diamond (3); The lip of the drill bit forms a three-level gradient cutting edge structure with increasing height from the outside to the inside. The diamond particle (4) has the lowest cutting edge height, followed by the PcBN coating layer (2), and the strip-shaped CVD diamond (3) has the highest cutting edge height.

2. The PcBN / CVD diamond composite reinforced impregnated diamond drill bit according to claim 1, characterized in that, The outer and inner diameters of the matrix (1) are respectively inlaid with diamond polycrystals (6).

3. The PcBN / CVD diamond composite reinforced impregnated diamond drill bit according to claim 1, characterized in that, The drill bit has a water inlet (5) on its lip surface, and the water inlet (5) is located between adjacent blocks.

4. The PcBN / CVD diamond composite reinforced impregnated diamond drill bit according to claim 1, characterized in that, The preparation method of the PcBN / CVD diamond composite column includes the following steps: S1. Preparation of mixed particle size cBN raw material: Mixed particle size cBN powder is prepared by ball milling. The mixed particle size cBN powder is formed by uniformly mixing three types of cBN particles with particle size concentrations of 20μm, 8μm and 2μm respectively. S2. Preparation of PcBN powder raw materials: Mix cBN powder with Al powder of mixed particle size, add anhydrous ethanol and wet mix in a ball mill, vacuum dry and then sieve to obtain mixed powder; S3. The mixed powder is pre-pressed into a cylindrical blank on a tablet press. A rectangular groove is opened along the axial direction in the center of the blank, and a strip of CVD diamond (3) is inserted. The blank is pre-pressed and fixed again. The blank is placed in a six-sided top press and sintered under high pressure and high temperature. After sintering, it is ground and polished to obtain a PcBN / CVD diamond composite column.

5. The PcBN / CVD diamond composite reinforced impregnated diamond drill bit according to claim 4, characterized in that, In S1, the three types of cBN particles are uniformly mixed in a mass ratio of 10:7:

3.

6. The PcBN / CVD diamond composite reinforced impregnated diamond drill bit according to claim 4, characterized in that, In S2, cBN powder and Al powder with mixed particle sizes are mixed at a volume ratio of 4:

1.

7. The PcBN / CVD diamond composite reinforced impregnated diamond drill bit according to claim 4, characterized in that, In S2, Ti2AlC powder is also added during the process of mixing cBN powder with Al powder of mixed particle size. The mixed particle size cBN powder was mixed with Ti2AlC powder and Al powder at a mass ratio of 20:4:

1.

8. The PcBN / CVD diamond composite reinforced impregnated diamond drill bit according to claim 4, characterized in that, In S3, the specific parameters for high-pressure high-temperature sintering are: 5.5 GPa, holding at 1500℃ for 10 min.

9. A method for preparing a PcBN / CVD diamond composite reinforced impregnated diamond drill bit as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Preparation of mixed particle size cBN raw material: Mixed particle size cBN powder is prepared by ball milling. The mixed particle size cBN powder is formed by uniformly mixing three types of cBN particles with particle size concentrations of 20μm, 8μm and 2μm in a mass ratio of 10:7:

3. S2. Preparation of PcBN powder raw materials: Mix cBN powder of mixed particle size with Al powder, add anhydrous ethanol and wet mix in a ball mill, vacuum dry and then sieve to obtain mixed powder; S3. The mixed powder is pre-pressed into a cylindrical blank on a tablet press. A cuboid groove is opened along the axial direction in the center of the blank, and a strip of CVD diamond (3) is inserted. The blank is pre-pressed and fixed again. The blank is placed in a six-sided press and kept at 5.5 GPa and 1500℃ for 10 min. After sintering, it is ground and polished to obtain a PcBN / CVD diamond composite column. S4. Mix diamond particles (4) with matrix powder evenly, load the obtained matrix mixture into a graphite mold, reserve a hole in the center of each matrix block, insert a PcBN / CVD diamond composite column, fill the surrounding matrix mixture, place a steel body (7) on top, place the graphite mold in a hot pressing sintering equipment, and perform hot pressing sintering at 850-950℃ and 15-25MPa to firmly bond the PcBN / CVD diamond composite column with the matrix (1), open a water gate (5) on the lip of the drill bit, and embed diamond polycrystals (6) on the outer diameter and inner diameter of the matrix (1) respectively.

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