High-pressure sintering method for diamond thin-wall drilling tool bit
By optimizing temperature and pressure parameters through high-pressure sintering, the problem of uneven temperature and pressure distribution during the sintering process of thin-walled diamond drill bits was solved, which improved the density, compressive strength and hardness of the drill bits, reduced production costs and broadened the application fields.
Patent Information
- Application Number
- CN202511680268.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-17
- Publication Date
- 2026-02-10
AI Technical Summary
In the manufacturing process of thin-walled diamond drill bits, how to reduce production costs and improve production efficiency while ensuring high performance, and how to solve the problems of strength and stability of thin-walled structures, especially the problem of uneven internal stress caused by uneven temperature and pressure distribution during sintering.
A high-pressure sintering process was adopted to prepare diamond thin-walled drill bit blanks by cold pressing, and pyrophyllite assembly blocks were assembled in graphite molds. High-pressure sintering was carried out using a six-sided top press, and the temperature and pressure parameters were optimized, including a pressure of 25~35MPa, a sintering power of 2500~4800W, and a pressure holding and temperature holding time of 150~300s.
It significantly improves the density, compressive strength, and hardness of thin-walled diamond drill bits, shortens sintering time, increases production efficiency, and extends service life.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of powder metallurgy technology, specifically relating to a high-pressure sintering method for diamond thin-walled drill bits. Background Technology
[0002] With the development of industrial technology, diamond drill bits are widely used in drilling and other fields. Diamond drill bits are usually manufactured by sintering diamond particles with a metal matrix through hot pressing. However, there are a series of challenges in the production of thin-walled drill bits, especially in ensuring the strength and stability of the thin-walled structure while maintaining high performance.
[0003] The manufacturing of thin-walled diamond drill bits faces challenges such as uneven temperature and pressure distribution during hot-pressing sintering, which can easily lead to uneven internal stress, resulting in drill bit deformation or cracking. Although traditional sintering processes can produce drill bits of a certain quality, the thin wall thickness and uncontrollable internal stress during sintering limit the mechanical properties and service life of the drill bits.
[0004] Currently, research on thin-walled diamond drill bits mainly focuses on the formulation of the metal matrix, optimization of the sintering process, and improvement of the strength of the thin-walled diamond drill bits. The optimized ratio of diamond particles to the metal matrix is crucial to the sintering effect. Researchers aim to improve the bonding strength and wear resistance after sintering by adjusting different ratios of metal matrices and diamond particles. Furthermore, precise control of sintering temperature, pressure, and time is also a core factor in optimizing the sintering process, effectively avoiding deformation and cracking caused by excessive temperature gradients.
[0005] Despite some research progress, how to reduce production costs and improve production efficiency while ensuring the high performance of thin-walled diamond drill bits remains a key problem that urgently needs to be solved in this field. Therefore, this invention develops a novel, efficient, and high-precision high-pressure sintering process, which solves the problems of low density, compressive strength, and hardness in thin-walled diamond drill bits, extending their service life and broadening their application areas to a certain extent, providing favorable technical support for the development of related industries. Summary of the Invention
[0006] To address the problems existing in the current hot pressing sintering method for preparing thin-walled diamond drill bits, this invention provides a high-pressure sintering method for thin-walled diamond drill bits.
[0007] The diamond thin-walled drill bit of the present invention is prepared by cold pressing diamond particles and metal matrix to obtain a green blank, loading the green blank into a graphite mold and assembling it into a pyrophyllite assembly block, and placing the pyrophyllite assembly block into a six-sided press and preparing it by high-pressure sintering process; the diamond thin-walled drill bit has a working layer and a welding layer.
[0008] The radius of the diamond thin-walled drill bit is Ф50~Ф80mm;
[0009] The diamond particles are 40-45 mesh diamond particles with Ti-plated surface.
[0010] The metal matrix is composed of 35-40 wt% copper powder, 10-15 wt% nickel powder and 3-5 wt% tin powder, with the balance being iron;
[0011] The graphite mold consists of four layers, each capable of holding four diamond thin-walled drill bits, with each layer separated by a 1mm graphite sheet. The graphite mold has a central through-hole with a straight side length of 18-20mm. The curvature of the through-hole matches the curvature of the diamond thin-walled drill bits, and the width of the through-hole is the same as the width of the diamond thin-walled drill bits.
[0012] The pyrophyllite assembly block consists of a pyrophyllite insulation layer, a dolomite insulation layer, a steel cap, a conductive graphite sheet, a conductive nickel sheet, a heating tube, an insulating tube, a graphite mold, and a diamond thin-walled drill bit.
[0013] The high-pressure sintering preparation process mainly includes the design of pressure, temperature and time, wherein the pressure is 25~35MPa, the sintering power is 2500~4800W, and the pressure holding and temperature holding time is 150~300s.
[0014] The high-pressure sintering preparation process, which is a key part of this invention, includes, but is not limited to, the following preferred embodiments:
[0015] Preferably, the high-pressure sintering preparation process has a pressure of 30 MPa, a sintering power of 4800 W, and a pressure holding and heat holding time of 300 s.
[0016] Preferably, the high-pressure sintering preparation process has a pressure of 25 MPa, a sintering power of 4800 W, and a pressure holding and heat holding time of 300 s.
[0017] Preferably, the high-pressure sintering preparation process has a pressure of 30 MPa, a sintering power of 4800 W, and a pressure holding and heat holding time of 150 s.
[0018] Preferably, the high-pressure sintering preparation process has a pressure of 35 MPa, a sintering power of 2500 W, and a pressure holding and heat holding time of 150 s.
[0019] Preferably, the high-pressure sintering preparation process has a pressure of 30 MPa, a sintering power of 2500 W, and a pressure holding and heat holding time of 150 s.
[0020] Preferably, the high-pressure sintering preparation process has a pressure of 30 MPa, a sintering power of 2500 W, and a pressure holding and heat holding time of 300 s.
[0021] As part of this invention, a high-pressure sintering method for a thin-walled diamond drill bit is provided, comprising the following steps:
[0022] (1) The cold-pressed diamond thin-walled drill bit blank is put into a graphite mold and assembled into a pyrophyllite assembly block. It is then placed in an oven and baked for 4 hours at a temperature of 120°C.
[0023] (2) The graphite mold described in step (1) is divided into four layers, each layer can hold four diamond thin-walled drill bits, and the layers are separated by 1mm graphite sheets.
[0024] (3) Place the pyrophyllite assembly block described in step (1) into a six-sided press, pressurize it to P1 over time t0~t1, and start the heating program at the same time. Then pressurize it to P2 at the same pressurization rate, and then hold the pressure. After time t1~t3, synthesize the power to T1, and then hold the temperature for time t3~t4. After the heat holding and pressure holding are completed, stop the heat and wait for time t4~t5. Then, after time t5~t6, the pressure drops to 0. Take out the pyrophyllite block to obtain the diamond thin-walled drill bit made by high pressure sintering.
[0025] Wherein P1 is 15~25 MPa, t1~t3 is 30~150 s, t4~t5 is 10~30 s, and t5~t6 is 60~150 s.
[0026] Compared with existing technologies, the high-pressure sintering method for diamond thin-walled drill bits involved in this invention has significant advantages, specifically the following advantages:
[0027] (1) The high-pressure sintering process provided by the present invention can effectively reduce the etching effect of the metal matrix on diamond, significantly improve the density, compressive strength, hardness and other properties of diamond thin-walled drill bits, and broaden the demand for diamond thin-walled drill bits in many fields.
[0028] (2) The high-pressure sintering process provided by the present invention effectively shortens the sintering time of diamond thin-walled drill bits and improves production efficiency by optimizing the coordinated control of temperature and pressure parameters. Attached Figure Description
[0029] Figure 1 The graphite mold used in this invention to prepare diamond thin-walled drill bits.
[0030] Figure 2 This is a schematic diagram of the pyrophyllite block assembly and component diagram used in the preparation of the diamond thin-walled drill bit of this invention.
[0031] Figure 3 Synthesis process curves for preparing diamond thin-walled drill bits according to the present invention. Detailed Implementation
[0032] The present invention will be further described below with reference to specific implementation examples. Of course, the implementation examples are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1
[0033] (1) The cold-pressed diamond thin-walled drill bit blank is put into a graphite mold and assembled into a pyrophyllite assembly block. It is then placed in an oven and baked for 4 hours at a temperature of 120°C.
[0034] (2) The graphite mold described in step (1) is divided into four layers, each layer can hold four diamond thin-walled drill bits, and the layers are separated by 1mm graphite sheets.
[0035] (3) Place the pyrophyllite assembly block described in step (1) into a six-sided press, pressurize it to 20 MPa in 60 seconds, start the heating program at the same time, and then pressurize it to 30 MPa at the same pressurization rate. Then hold the pressure and synthesize the power to 4800 W in 150 seconds. Then hold the temperature for 300 seconds. After the heat holding and pressure holding are completed, stop the heat and wait for 10 seconds. Then, after 100 seconds, the pressure drops to 0 MPa. Take out the pyrophyllite block to obtain the diamond thin-walled drill bit made by high pressure sintering.
[0036] (4) The density was 7.9690 g / cm3, the hardness was 67.8RB, the bending strength was 610.6 MPa, the bending modulus was 465.9 MPa, and the wear rate was 9.95%. Example 2
[0037] Steps (1) to (2) are the same as in Example 1.
[0038] (3) Place the pyrophyllite assembly block described in step (1) into a six-sided press, pressurize it to 15 MPa in 60 seconds, start the heating program at the same time, then pressurize it to 25 MPa at the same pressurization rate, then hold the pressure, and after 150 seconds the power is increased to 4800W, and then hold the temperature for 300 seconds; after the heat holding and pressure holding are completed, stop the heat directly and wait for 10 seconds, and then after 100 seconds the pressure drops to 0 MPa. Take out the pyrophyllite block to obtain the diamond thin-walled drill bit made by high pressure sintering.
[0039] (4) The density was 7.9506 g / cm3, the hardness was 68.0 HRB, the bending strength was 674.4 MPa, the bending modulus was 420.5 MPa, and the wear rate was 7.81%. Example 3
[0040] Steps (1) to (2) are the same as in Example 1.
[0041] (3) Place the pyrophyllite assembly block described in step (1) into a six-sided press, pressurize it to 20 MPa in 60 seconds, start the heating program at the same time, then pressurize it to 30 MPa at the same pressurization rate, then hold the pressure, and after 150 seconds the power is increased to 4800W, and then hold the temperature for 150 seconds; after the heat holding and pressure holding are completed, stop the heat directly and wait for 10 seconds, and then after 100 seconds the pressure drops to 0 MPa. Take out the pyrophyllite block to obtain the diamond thin-walled drill bit made by high pressure sintering.
[0042] (4) The density was 7.9324 g / cm3, the hardness was 69.3 HRB, the bending strength was 747.5 MPa, the bending modulus was 477.8 MPa, and the wear rate was 7.81%. Example 4
[0043] Steps (1) to (2) are the same as in Example 1.
[0044] (3) Place the pyrophyllite assembly block described in step (1) into a six-sided press. First, pressurize it to 20 MPa in 60 seconds, and start the heating program at the same time. Then, pressurize it to 35 MPa at the same pressurization rate. Then, maintain the pressure and synthesize the power to 2500 W in 150 seconds. Then, maintain the temperature for 150 seconds. After the heat preservation and pressure maintenance are completed, stop the heat and wait for 10 seconds. Then, reduce the pressure to 0 MPa in 100 seconds. Take out the pyrophyllite block to obtain the diamond thin-walled drill bit made by high pressure sintering.
[0045] (4) The density was 7.9079 g / cm3, the hardness was 84.2 HRB, the bending strength was 807.6 MPa, the bending modulus was 476.4 MPa, and the wear rate was 7.38%. Example 5
[0046] Steps (1) to (2) are the same as in Example 1.
[0047] (3) Place the pyrophyllite assembly block described in step (1) into a six-sided press, pressurize it to 20 MPa in 60 seconds, start the heating program at the same time, then pressurize it to 30 MPa at the same pressurization rate, then hold the pressure, and after 150 seconds the power is increased to 2500W, then hold the temperature for 150 seconds; after the heat holding and pressure holding are completed, stop the heat directly and wait for 10 seconds, then after 100 seconds the pressure drops to 0 MPa, take out the pyrophyllite block to obtain the diamond thin-walled drill bit made by high pressure sintering.
[0048] (4) The density was 7.8959 g / cm3, the hardness was 78.7 HRB, the bending strength was 784.2 MPa, the bending modulus was 446.5 MPa, and the wear rate was 6.68%. Example 6
[0049] Steps (1) to (2) are the same as in Example 1.
[0050] (3) Place the pyrophyllite assembly block described in step (1) into a six-sided press, pressurize it to 20 MPa in 60 seconds, start the heating program at the same time, and then pressurize it to 30 MPa at the same pressurization rate. Then hold the pressure and synthesize the power to 2500 W in 150 seconds. Then hold the temperature for 300 seconds. After the heat holding and pressure holding are completed, stop the heat and wait for 10 seconds. Then, after 100 seconds, the pressure drops to 0 MPa. Take out the pyrophyllite block to obtain the diamond thin-walled drill bit made by high pressure sintering.
[0051] (4) The density was 7.9230 g / cm3, the hardness was 85.6 HRB, the bending strength was 833.1 MPa, the bending modulus was 472.2 MPa, and the wear rate was 4.47%.
[0052] Comparing Examples 1-6, it can be seen that the optimal density, hardness, bending strength, flexural modulus, and wear rate of the high-pressure sintered diamond thin-walled drill bit are 7.9690 g / cm³, 85.6 HRB, 833.1 MPa, 477.8 MPa, and 4.47%, respectively. Furthermore, the diamond thin-walled drill bit exhibits the best overall performance when the sintering pressure is 35 MPa, the sintering time is 150 s, and the sintering power is 2500 W (Example 4). Compared to Comparative Example 1, Example 4 shows a 1.3% increase in density, a 16.5% increase in hardness, a 17.8% increase in bending strength, a 2.4% increase in flexural modulus, and a 1.6% reduction in wear rate. In summary, this invention utilizes a domestically produced six-sided top press for high-pressure sintering of diamond drill bits, successfully replacing the traditional hot-pressing sintering process with high-pressure sintering technology, significantly optimizing the overall performance of the diamond drill bit.
[0053] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.
Claims
1. A thin-walled diamond drill bit, characterized in that, The diamond thin-walled drill bit has an arc of Ф50~Ф80mm. The cold-pressed diamond thin-walled drill bit blank is put into a graphite mold and assembled into a pyrophyllite assembly block. It is then placed in an oven and baked for 4 hours at a temperature of 120℃, and then subjected to high-pressure sintering.
2. The diamond thin-walled drill bit according to claim 1, characterized in that, The diamond particles are 40-45 mesh diamond particles with Ti-plated surface; the metal matrix is composed of 40-50 wt% iron powder, 35-40 wt% copper powder, 10-15 wt% nickel powder and 3-5 wt% tin powder.
3. The diamond thin-walled drill bit according to claim 1, characterized in that, The graphite mold in the assembly block is divided into four layers, each layer can hold four diamond thin-walled drill bits, and the layers are separated by 1mm graphite sheets. The center of the graphite mold is a through hole with a straight side length of 18~20mm. The arc of the arc side is the same as the arc of the diamond thin-walled drill bit, and the width of the through hole is the same as the width of the diamond thin-walled drill bit.
4. The diamond thin-walled drill bit according to claim 1, characterized in that, The high-pressure sintering process mainly includes pressure, temperature and time, wherein the pressure is 25~35MPa, the sintering power is 2500~4800kW, and the pressure holding and temperature holding time is 150~300s.
5. As described in claim 4, characterized in that, The pyrophyllite assembly block is placed in a six-sided press, and the pressure is first increased to P1 over time t0~t1, while the heating program is started at the same time. Then the pressure is increased to P2 at the same pressure increase rate, and then the pressure is maintained. The combined power is increased to T1 over time t1~t3, and then the temperature is maintained for time t3~t4. After the heat preservation and pressure holding are completed, the heat is stopped and the process is allowed to wait for time t4~t5. Then, after time t5~t6, the pressure drops to 0, and the pyrophyllite block is removed to obtain the diamond thin-walled drill bit made by high-pressure sintering.
6. As described in claim 5, characterized in that, Wherein P1 is 15~25 MPa, t1~t3 is 30~150 s, t4~t5 is 10~30 s, and t5~t6 is 60~150 s.