Polycrystalline diamond compact for grinding carbon steel, grinding tool and preparation method

Abstract

The invention belongs to the technical field of superhard materials, and particularly relates to a polycrystalline diamond compact for grinding carbon steel, a grinding tool and a preparation method. The polycrystalline diamond compact is prepared by taking 75-85wt% of diamond micro powder, 5-10wt% of boron-containing diamond fine powder and 10-15wt% of a binder as raw materials, uniformly mixing the raw materials, sintering and cutting, and has high wear resistance and thermal stability; the grinding tool comprises a grinding head and a base body which are fixedly connected through a vacuum brazing process, the grinding head is prepared from a polycrystalline diamond compact used for grinding carbon steel, and the base body is made of a hard alloy material. The tail end of the base body is used for being connected with grinding equipment, and the head end is fixedly connected with the grinding head. Grinding blades and chip grooves are alternately arranged on the grinding head, and staggered cooling holes are formed in the chip grooves. According to the tool, efficient cooling and smooth chip removal can be achieved under small-size constraint, firm and reliable connection between the grinding head and the base body is guaranteed, and therefore the requirement for high-precision and high-efficiency precise grinding machining is met.

Description

Technical Field

[0001] This invention belongs to the field of superhard materials technology, specifically relating to a polycrystalline diamond composite sheet for grinding carbon steel, a grinding tool, and a preparation method. Background Technology

[0002] In general, carbon steel is ground using tools made of common abrasives (such as corundum, silicon carbide, and CBN), which suffers from rapid tool wear and short lifespan. The hardness of these abrasives is much lower than the hard phase in carbon steel (such as cementite), causing the abrasive grains to wear rapidly under friction, resulting in short tool life, frequent replacements, reduced processing efficiency, and increased processing costs. To overcome the shortcomings of traditional abrasives in grinding carbon steel—short lifespan, easy clogging, and low efficiency—and to leverage the superior wear resistance and unique self-sharpening properties of polycrystalline diamond (PCD) to overcome the limitation of diamond tools being unable to process iron-based materials, there is an urgent need to develop a new type of PCD grinding head specifically designed for low-to-medium speed (10±5 m / s) grinding of carbon steel. Furthermore, the manufacturing method of this tool should address key technical challenges such as high-strength bonding between PCD and the matrix, optimized abrasive arrangement, and stable, economical large-scale production. Summary of the Invention

[0003] Based on this, the purpose of the present invention is to provide a polycrystalline diamond composite sheet for grinding carbon steel. The polycrystalline diamond composite sheet can maintain sufficient thermal stability in a high-temperature grinding environment of about 720°C, and can meet the medium and low speed (10±5m / s) grinding conditions for carbon steel.

[0004] This invention utilizes the polycrystalline diamond composite sheet in a grinding tool, providing a polycrystalline diamond grinding tool for grinding carbon steel. In this grinding tool, the grinding head is firmly connected to the substrate, and the grinding performance is excellent.

[0005] The present invention also provides a method for preparing a polycrystalline diamond composite sheet for grinding carbon steel and a method for preparing a polycrystalline diamond grinding tool for grinding carbon steel.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a polycrystalline diamond composite sheet for grinding carbon steel, which is prepared by mixing 75wt%~85wt% diamond micro powder, 5wt%~10wt% boron-containing diamond fine powder and 10wt%~15wt% binder, followed by sintering and cutting. The binder is a mixture of cobalt powder and silicon carbide. The total weight percentage of the raw materials is 100%.

[0007] Furthermore, the average particle size of the diamond micro powder is 40~50μm, the average particle size of the boron-containing diamond fine powder is 1~3μm, wherein the boron content is 1~2wt%, and the mass ratio of cobalt powder to silicon carbide in the binder is 2~4:1.

[0008] The present invention further provides a method for preparing the above-mentioned polycrystalline diamond composite sheet for grinding carbon steel, comprising the following steps: S1, the diamond micro powder, boron-containing diamond fine powder and binder are mixed in proportion to obtain a mixed raw material; S2, using a six-sided top press to sinter the mixed raw materials described in S1 to obtain polycrystalline diamond composite sheet base material; S3, the polycrystalline diamond composite sheet base material described in S2 is cut to obtain the polycrystalline diamond composite sheet used for grinding carbon steel.

[0009] Furthermore, the sintering process described in S2 is as follows: S21, First stage sintering: Pressurize to sintering pressure of 6.0GPa~6.2GPa at a pressurization rate of 1GPa / min~1.2GPa / min, heat to 1400℃ at a heating rate of 20℃ / s~22℃ / s, and hold for 80~100s; S22, Second stage sintering: After the first stage sintering in S21 is completed, the temperature is raised to 1500℃~1620℃ within 35s~40s to continue sintering, and the holding time is 5min~6min; S23, end cooling: After the second stage of sintering in S22 is completed, the temperature is reduced to 680℃ at a rate of 20℃ / s~25℃ / s, held for 2min~4min, and then reduced to room temperature. The pressure is then reduced to atmospheric pressure at a rate of 0.8GPa / min~1GPa / min.

[0010] Furthermore, the polycrystalline diamond composite sheet base material obtained in S2 has a thickness of 5~12mm, and is cut into cylindrical polycrystalline diamond composite sheets of different thicknesses and diameters for grinding carbon steel by wire cutting (WEDM) or laser cutting.

[0011] The present invention further provides a polycrystalline diamond grinding tool for grinding carbon steel, comprising a grinding head and a substrate, wherein the grinding head is the aforementioned polycrystalline diamond composite sheet for grinding carbon steel; and the substrate is made of cemented carbide.

[0012] Furthermore, the grinding head and the substrate are fixedly connected by vacuum brazing. The tail end of the substrate is used to connect to the grinding equipment, and the head end is fixedly connected to the grinding head. The grinding head is provided with a grinding blade and a chip removal groove, and the chip removal groove is provided with cooling holes.

[0013] Furthermore, the substrate is a cylindrical substrate, and a through hole extending axially is provided at the center of the cylindrical substrate; the grinding head is a cylindrical grinding head, and a blind hole extending axially is provided at the center of the cylindrical grinding head, the blind hole communicating with the through hole in the cylindrical substrate; the cylindrical grinding head also has an oblique through hole, one end of the oblique through hole communicating with the blind hole, and the other end extending to the circumferential outer wall of the cylindrical grinding head to form the cooling hole.

[0014] Furthermore, the cylindrical grinding head has grinding blades and chip removal grooves alternately arranged on its circumferential surface; the number of grinding blades and chip removal grooves is ≥2 each, the cooling holes are located in each chip removal groove, and the cooling holes in each chip removal groove are staggered in both the axial and circumferential directions of the grinding head.

[0015] The present invention further provides a method for preparing the above-mentioned polycrystalline diamond abrasive tool for grinding carbon steel, comprising the following steps: (1) Grinding head pretreatment: First, the polycrystalline diamond composite sheet used for grinding carbon steel is ultrasonically cleaned, and then the blind hole, oblique through hole and cooling hole are processed by laser. Then, the welding surface is meshed. (2) Vacuum brazing: The pre-treated grinding head in step (1) is welded and fixed to the substrate; (3) Grinding head finishing and dynamic balance test: The grinding head welded in step (2) is laser turned and chip groove engraved, and a dynamic balance test is performed; (4) Grinding head passivation treatment: After the grinding head processed in step (3) is passivated by jet passivation, the polycrystalline diamond grinding tool for grinding carbon steel is obtained.

[0016] Further, the welding process described in step (2) is as follows: under vacuum conditions, the temperature is increased to 450~550℃ at a rate of ≥50℃ / min, and held for 5~6 minutes to preheat the brazing filler metal; then the temperature is increased from 450~550℃ to 700~750℃, and held for 3~5 minutes to melt the brazing filler metal. After that, the grinding head and the substrate are connected and fixed, and the head is taken out after cooling.

[0017] Furthermore, the test results of the dynamic balance test mentioned in step (3) must meet the following requirements: dynamic balance accuracy ≤ 2g / mm, and radial runout after processing ≤ 0.003mm.

[0018] Furthermore, the jet passivation process described in step (4) is as follows: using diamond micro powder of 14000~16000 mesh, at a pressure of 0.15~0.25MPa, and a passivation treatment time of 6~8 minutes.

[0019] The beneficial effects of this invention are: 1. The polycrystalline diamond composite sheet for grinding carbon steel provided by this invention has high wear resistance and thermal stability. When grinding Cr12 quenched steel, the wear ratio is over 80,000, which is more than 50 times that of traditional chromium corundum with similar particle size. The material has a long service life, high processing efficiency, and low cost. The surface quality of the processed workpiece is excellent and the dimensional consistency is high.

[0020] 2. The polycrystalline diamond grinding tool for grinding carbon steel provided by this invention uses a vacuum brazing process to fix the polycrystalline diamond grinding head to a cemented carbide substrate. The connection interface is strong and reliable, and can withstand centrifugal force under high-speed rotation and complex grinding forces. The substrate is made of cemented carbide, which provides good toughness support, while the grinding head is made of polycrystalline diamond, which has excellent grinding performance. This increases product lifespan, improves processing efficiency, reduces costs, and results in workpieces with excellent surface quality and high dimensional consistency.

[0021] 3. The polycrystalline diamond grinding tool for grinding carbon steel provided by this invention has a through hole in the base and blind holes, oblique through holes, and cooling holes in the grinding head. These cooling holes are staggered within the chip removal groove. During grinding, coolant or cooling gas can pass through the through holes and blind holes in the base and grinding head, and be sprayed directly from the cooling holes in the chip removal groove through the oblique through holes. This rapidly removes grinding heat, reduces the temperature rise of the tool and workpiece, prevents thermal damage to the workpiece material, and reduces graphitization wear of the grinding head due to high temperatures, thus extending tool life. Simultaneously, the high-speed outflowing coolant promptly flushes away the generated fine chips from the chip removal groove, fundamentally avoiding problems such as chip clogging, secondary grinding, and surface scratches, ensuring the quality and precision of the machined surface.

[0022] 4. The polycrystalline diamond grinding tool for grinding carbon steel provided by the present invention has grinding blades and chip removal grooves on the grinding head arranged in an axially parallel strip-shaped alternating or spiral-shaped alternating manner. The structure design is simple, the chip removal is smoother, the processing is stable, and the product can be ground quickly.

[0023] 5. The preparation method of the polycrystalline diamond composite sheet and grinding tool for grinding carbon steel provided by the present invention has a simple process flow and is easy to mass-produce. Attached Figure Description

[0024] To more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Appendix Figure 1This is a product image of the polycrystalline diamond composite sheet for grinding carbon steel in this invention; Appendix Figure 2 This is a SEM image of the polycrystalline diamond composite sheet used for grinding carbon steel in this invention, with a scale bar of 10 μm. Appendix Figure 3 This is a schematic diagram of the overall structure of the polycrystalline diamond grinding tool (straight-line grinding head) for grinding carbon steel according to the present invention; wherein, 1 is the grinding head, 2 is the base body, 3 is the grinding blade, 4 is the chip removal groove, and 5 is the cooling hole; Appendix Figure 4 This is a cross-sectional view of the polycrystalline diamond grinding tool (straight-row grinding head) for grinding carbon steel according to the present invention; wherein, 1 is the grinding head, 2 is the base, 5 is the cooling hole, 6 is the through hole, 7 is the blind hole, and 8 is the oblique through hole; Appendix Figure 5 This is an enlarged structural diagram of the grinding head in the polycrystalline diamond grinding tool (straight-line grinding head) for grinding carbon steel according to the present invention; wherein, 3 is the grinding blade, 4 is the chip removal groove, and 5 is the cooling hole; Appendix Figure 6 This is a cross-sectional view of the grinding head in the polycrystalline diamond grinding tool (straight-line grinding head) for grinding carbon steel according to the present invention; wherein, 3 is the grinding blade and 4 is the chip removal groove; Appendix Figure 7 This is a cross-sectional view of the polycrystalline diamond grinding tool (spiral grinding head) for grinding carbon steel according to the present invention; wherein, 1 is the grinding head, 2 is the base, 5 is the cooling hole, 6 is the through hole, 7 is the blind hole, and 8 is the oblique through hole; Appendix Figure 8 This is an enlarged structural diagram of the grinding head in the polycrystalline diamond grinding tool (spiral grinding head) for grinding carbon steel according to the present invention; wherein, 3 is the grinding blade, 4 is the chip removal groove, and 5 is the cooling hole; Appendix Figure 9 This is a cross-sectional view of the grinding head in the polycrystalline diamond grinding tool (spiral grinding head) for grinding carbon steel according to the present invention; wherein, 3 is the grinding blade and 4 is the chip removal groove. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All mentioned embodiments are implemented based on the technical solutions of the present invention, and detailed implementation processes are given. However, it should be stated that the scope of protection of the present invention is not limited to the following embodiments.

[0027] like Figures 1-9 As shown, the present invention provides a polycrystalline diamond composite sheet for grinding carbon steel. Figure 1 and Figure 2The polycrystalline diamond composite sheet was used in a grinding tool to obtain a polycrystalline diamond grinding tool for grinding carbon steel. Figures 3-9 ).

[0028] The polycrystalline diamond composite sheet used for grinding carbon steel in this invention is a small cylindrical composite sheet. Figure 1 Its surface microstructure shows that the diamond phase (dark color) exhibits a continuous polycrystalline morphology, while the binder phase (white color) is uniformly distributed in the gaps between the diamond particles. The interface between the diamond phase and the binder phase is tightly bonded. Figure 2 ).

[0029] The polycrystalline diamond grinding tool for grinding carbon steel in this invention includes a grinding head 1 and a base 2. The tail end of the base 2 is used to connect to a grinding device, and the head end is fixedly connected to the grinding head 1. The grinding head 1 is provided with a grinding blade 3 and a chip removal groove 4, and the chip removal groove 4 is provided with a cooling hole 5. Figure 3 The substrate 2 and the grinding head 1 are fixedly connected by a vacuum brazing process. The substrate 2 is made of cemented carbide, and the grinding head 1 is made of polycrystalline diamond. Vacuum silver-based solder paste is preferred for welding, with main components of 60wt% silver, 20wt% indium, 4wt% titanium, and the remainder copper. The thickness of the welded area is preferably about 0.05mm. The resulting interface is strong and reliable, capable of withstanding centrifugal force and complex grinding forces under high-speed rotation. The cemented carbide substrate 2 provides good toughness support, and the grinding head 1 is prepared from the polycrystalline diamond composite sheet used for grinding carbon steel in this invention, exhibiting excellent grinding performance. This increases product lifespan, improves processing efficiency, reduces costs, and results in excellent workpiece surface quality and high dimensional consistency.

[0030] The substrate 2 is a cylindrical substrate with an axially extending through hole 6 at its center, providing a channel for the delivery of coolant or cooling gas. The substrate 2 is preferably an elongated cylinder, which can be a cylinder with a uniform diameter throughout, or it can be composed of two cylindrical sections, one thicker and one thinner, connected by a transition. The tail end of the thicker section is connected to the welding equipment, and the head end of the thinner section is fixedly connected to the grinding head 1.

[0031] The grinding head 1 is a cylindrical grinding head. A blind hole 7 extending axially is provided at the center of the cylindrical grinding head 1, and the blind hole 7 communicates with a through hole 6 in the cylindrical base 2. An oblique through hole 8 is provided in the cylindrical grinding head 1. One end of the oblique through hole 8 communicates with the blind hole 7, and the other end extends to the circumferential outer wall of the cylindrical grinding head 1 to form a cooling hole 5. Figure 4 ).

[0032] In one embodiment of the present invention, the circumferential surface of the cylindrical grinding head 1 is alternately provided with grinding blades 3 and chip removal grooves 4 along the axial direction. Figure 5 and Figure 6The grinding blade 3 is a strip-shaped protrusion parallel to the axis of the grinding head 1; the chip removal groove 4 is a long strip-shaped groove. In another embodiment, the circumferential surface of the cylindrical grinding head 1 is provided with a spirally extending grinding blade 3 and a chip removal groove 4. The grinding blade 3 is a spiral protrusion, and the chip removal groove 4 is a spiral groove, and the two are alternately distributed along the circumference of the grinding head (e.g., Figures 7-9 The depth of the chip removal groove 4 is designed based on the grinding amount. For precision grinding, the preferred number of chip removal grooves 4 is 8 to 12; for general grinding, 4 to 6 are selected. The grinding blades 3 and chip removal grooves 4 on the grinding head 1 are arranged in an axially parallel strip-like or spiral-like alternating pattern. This simple structural design ensures smoother chip removal, a stable machining process, and enables rapid product grinding. Cooling holes 5 are located in each chip removal groove 4, and the cooling holes 5 in each chip removal groove 4 are staggered in both the axial and circumferential directions of the grinding head 1. Figure 5 and Figure 8 Preferably, the ligament width of the grinding blade 3 is 0.2~0.3mm, the depth of the chip removal groove 4 is 0.5~1mm, and the diameter of the grinding head 1 is 3~10mm. This gives the grinding blade 3 sufficient strength and sharpness, and the chip removal groove 4 the necessary chip-carrying space, making the tool particularly suitable for precision grinding, polishing, and deburring in fields such as micro-holes and precision molds.

[0033] When using the polycrystalline diamond grinding tool of this invention to grind an object, coolant or cooling gas can be sprayed directly from the cooling hole 5 of the chip removal groove 4 through the through hole 6 and blind hole 7 in the base 2 and grinding head 1, via the oblique through hole 8. This can quickly remove the grinding heat, reduce the temperature rise of the tool and the workpiece, prevent thermal damage to the workpiece material, and reduce graphitization wear of the grinding head caused by high temperature, thus extending the tool life. At the same time, the high-speed flowing coolant can promptly flush away the generated fine chips from the chip removal groove 4, fundamentally avoiding problems such as chip blockage, secondary grinding, and surface scratches, ensuring the quality and precision of the processed surface.

[0034] The following examples provide detailed procedures for preparing the polycrystalline diamond composite sheet for grinding carbon steel and the polycrystalline diamond grinding tool for grinding carbon steel. Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0035] Example 1 1. Preparation of polycrystalline diamond composite sheets for grinding carbon steel (1) Sintering: Diamond micro powder with an average particle size of 45 μm and a weight percentage of 80 wt% is used as the skeleton, and boron-containing diamond fine powder with an average particle size of 2 μm and a weight percentage of 8 wt% (boron element percentage of 1~2 wt%) is added as the filler phase. Cobalt powder and SiC are mixed in a 3:1 ratio as binder (accounting for 12 wt% of the total weight). The sum of the weight percentages of each component reaches 100%. After uniform mixing, sintering is carried out using a six-sided top press. During sintering, the pressure was increased to 6.0 GPa~6.2 GPa at a pressurization rate of 1 GPa / min in the first stage, and the temperature was increased at a heating rate of 22℃ / s for high-temperature sintering. After holding at 1400℃ for 90s, the temperature was increased to 1500℃~1620℃ within 35s~40s. After sintering, the temperature was decreased to 680℃ at a cooling rate of 25℃ / s, held for 3min, and then reduced to room temperature. Finally, the pressure was reduced to atmospheric pressure at a depressurization rate of 1 GPa / min to prepare polycrystalline diamond composite sheet base material.

[0036] (2) Cutting: First, pre-processing is carried out by double-end face grinding, and then the synthesized 25mm diameter polycrystalline diamond composite sheet base material is cut into small cylinders with a diameter of 8mm according to the design requirements by a blanking laser machine, which are polycrystalline diamond composite sheets used for grinding carbon steel. Figure 1 ).

[0037] The surface morphology was measured using SEM, and the test results are as follows: Figure 2 As shown, from Figure 2 As can be seen, the diamond matrix (dark color) exhibits a continuous polycrystalline morphology, while the Co-SiC binder phase (white color) is uniformly dispersed in a network and dotted pattern between the diamond particles. There is no obvious aggregation or localized absence of the binder phase, indicating that the binder effectively wets and fills the diamond micropowder during sintering. No obvious macroscopic defects such as pores or cracks were observed in the overall morphology. The interface between the diamond phase and the binder phase is tightly bonded, with no obvious gaps or separation. This reflects that under the high-temperature, high-pressure sintering process of the six-sided press, boron-doped diamond micropowder and the Co-SiC binder achieved good sintering densification and interfacial bonding, exhibiting a good microstructure.

[0038] 2. Preparation of polycrystalline diamond grinding tools for grinding carbon steel (1) Grinding head pretreatment: The small cylindrical polycrystalline diamond composite sheet used for grinding carbon steel is ultrasonically cleaned, and then blind holes, oblique through holes, and cooling holes are machined by laser. A mesh pattern is made on its welding surface to increase the contact area during welding, thereby improving the bending strength of the grinding tool after vacuum welding. A cylindrical substrate made of cemented carbide is prepared for use, and a through hole is machined in the center of the substrate. The diameters of the through hole, blind hole, oblique through hole, and cooling hole are all 0.5 mm.

[0039] (2) Vacuum Brazing: In a vacuum furnace, a special contour welding centering fixture is used to ensure the alignment of the through holes in the substrate and the blind holes in the grinding head. Then, vacuum silver-based solder paste (composition: 60 wt% silver, 20 wt% indium, 4 wt% titanium, and the remainder Cu) is used for vacuum brazing. Vacuum brazing includes six stages: pre-vacuuming, first heating (preheating), first holding, second heating, second holding, and cooling. Pre-vacuuming stage: Before heating, the vacuum level in the furnace needs to be evacuated to 4×10⁻² Pa to reduce oxidation caused by residual gas and ensure the wettability of the brazing filler metal. First heating stage: The temperature is increased to 500℃ at a rate of 50℃ / min. First holding stage: In the brazing holding active zone, 500℃ is maintained for 5 minutes to fully preheat the brazing filler metal. Second heating stage: The temperature is increased from 500℃ to 720℃ in 5 minutes. Second heat preservation stage: Maintain at a brazing temperature of 720℃ for 3~5 minutes to allow the brazing filler metal to fully melt and fill the gap, while promoting the interface reaction to form a stable bond. Cooling stage: Cool slowly with the furnace at a cooling rate of 30℃ / min, remove the welded material, and obtain a polycrystalline diamond grinding tool for grinding carbon steel to be optimized. After the tool is processed by the following steps (3) and (4), a polycrystalline diamond grinding tool for grinding carbon steel is obtained.

[0040] (3) Grinding head finishing and dynamic balancing test: Laser turning was used to ensure the accuracy of the outer contour of the grinding head, and laser engraving was used to process the chip removal grooves on the grinding head, resulting in a grinding edge width of 0.3 mm and a chip removal groove depth of 0.8 mm, with a quantity of 6 grooves. The dynamic balancing test results met the following requirements: dynamic balancing accuracy ≤ 2 g / mm, and radial runout ≤ 0.003 mm after machining.

[0041] (4) Grinding head passivation treatment: After laser processing, the circumferential cutting edge of the grinding head is passivated to ensure the stability of the cutting edge quality. The treatment method is to use 15000 mesh diamond micro powder and passivate it for 7 minutes with a pressure of 0.2MPa through jet passivation.

[0042] Using the polycrystalline diamond grinding tool for grinding carbon steel obtained in this embodiment, Cr12 quenched steel was ground using wet grinding with 10 bar coolant pumped out from the cooling hole. The linear speed during grinding was 10 m / s. Compared with using YG8 grit (hard alloy material) with a particle size of 45 μm, the wear was reduced by more than 96.7%. Previously, the grinding head needed to be replaced once a day. Now, after 75 days of continuous testing, stable production can be achieved for at least 30 days.

[0043] Comparative Example 1 The difference between this comparative example and Example 1 is that the polycrystalline diamond composite sheet formulation uses a mixed particle size of 45μm adjusted to 30μm + 2μm, and the binder is pure cobalt-based; the grinding tool lacks cooling holes and external cooling is used. Wet grinding is employed, with 10 bar coolant applied externally to the grinding head, and a linear velocity of 10 m / s during grinding. Compared with using YG8 particle size (hard alloy material) 45μm, the wear is reduced by approximately 25%.

[0044] Comparative Example 2 The difference between this comparative example and Example 1 is that the chip removal grooves on the grinding head of the grinding tool were not machined, cylindrical grinding was used, and the cooling holes were not staggered. Wet grinding was used, with 10 bar coolant ejected from the outside of the grinding head. The linear velocity during grinding was 10 m / s. Compared with using YG8 grit (hard alloy material) with a particle size of 45 μm, the wear was reduced by about 40%, and polycrystalline diamond detached from the body and broke (5 out of 50 pieces detached and 6 pieces broke).

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polycrystalline diamond composite sheet for grinding carbon steel, characterized in that, The product is prepared by mixing 75wt%~85wt% diamond micro powder, 5wt%~10wt% boron-containing diamond fine powder and 10wt%~15wt% binder, followed by sintering and cutting. The binder is a mixture of cobalt powder and silicon carbide. The total weight percentage of the raw materials is 100%.

2. The polycrystalline diamond composite sheet for grinding carbon steel as described in claim 1, characterized in that, The diamond micro powder has an average particle size of 40-50 μm, the boron-containing diamond fine powder has an average particle size of 1-3 μm, the boron content is 1-2 wt%, and the mass ratio of cobalt powder to silicon carbide in the binder is 2-4:

1.

3. A method for preparing a polycrystalline diamond composite sheet for grinding carbon steel as described in claim 1 or 2, characterized in that, Includes the following steps: S1, the diamond micro powder, boron-containing diamond fine powder and binder are mixed in proportion to obtain a mixed raw material; S2, using a six-sided top press to sinter the mixed raw materials described in S1 to obtain polycrystalline diamond composite sheet base material; S3, the polycrystalline diamond composite sheet base material described in S2 is cut to obtain the polycrystalline diamond composite sheet used for grinding carbon steel.

4. The method for preparing polycrystalline diamond composite sheets for grinding carbon steel as described in claim 3, characterized in that, The sintering process described in S2 is as follows: S21, First stage sintering: Pressurize to sintering pressure of 6.0GPa~6.2GPa at a pressurization rate of 1GPa / min~1.2GPa / min, heat to 1400℃ at a heating rate of 20℃ / s~22℃ / s, and hold for 80~100s; S22, Second stage sintering: After the first stage sintering in S21 is completed, the temperature is raised to 1500℃~1620℃ within 35s~40s to continue sintering, and the holding time is 5min~6min; S23, end cooling: After the second stage of sintering in S22 is completed, the temperature is reduced to 680℃ at a rate of 20℃ / s~25℃ / s, held for 2min~4min, and then reduced to room temperature. The pressure is then reduced to atmospheric pressure at a rate of 0.8GPa / min~1GPa / min.

5. A polycrystalline diamond grinding tool for grinding carbon steel, characterized in that, It includes a grinding head and a substrate, wherein the grinding head is a polycrystalline diamond composite sheet for grinding carbon steel as described in claim 1 or 2.

6. The polycrystalline diamond abrasive tool for grinding carbon steel as described in claim 5, characterized in that, The grinding head and the substrate are fixedly connected by vacuum brazing. The tail end of the substrate is used to connect to the grinding equipment, and the head end is fixedly connected to the grinding head. The grinding head is provided with a grinding blade and a chip removal groove, and the chip removal groove is provided with a cooling hole.

7. The polycrystalline diamond grinding tool for grinding carbon steel as described in claim 5, characterized in that, The substrate is a cylindrical substrate, and a through hole extending axially is provided at the center of the cylindrical substrate; the grinding head is a cylindrical grinding head, and a blind hole extending axially is provided at the center of the cylindrical grinding head, the blind hole communicating with the through hole in the cylindrical substrate; the cylindrical grinding head is also provided with an oblique through hole, one end of the oblique through hole communicating with the blind hole, and the other end extending to the circumferential outer wall of the cylindrical grinding head to form the cooling hole.

8. The polycrystalline diamond grinding tool for grinding carbon steel as described in claim 5, characterized in that, The cylindrical grinding head has grinding blades and chip removal grooves alternately arranged on its circumferential surface; the number of grinding blades and chip removal grooves is ≥2 each, and the cooling holes are located in each chip removal groove, and the cooling holes in each chip removal groove are staggered in the axial and circumferential directions of the grinding head.

9. A method for preparing a polycrystalline diamond abrasive tool for grinding carbon steel according to any one of claims 6 to 8, characterized in that, Includes the following steps: (1) Grinding head pretreatment: First, the polycrystalline diamond composite sheet used for grinding carbon steel is ultrasonically cleaned, and then the blind hole, oblique through hole and cooling hole are processed by laser. Then, the welding surface is meshed. (2) Vacuum brazing: The pre-treated grinding head in step (1) is welded and fixed to the substrate; (3) Grinding head finishing and dynamic balance test: The grinding head welded in step (2) is laser turned and chip groove engraved, and a dynamic balance test is performed; (4) Grinding head passivation treatment: After the grinding head processed in step (3) is passivated by jet passivation, the polycrystalline diamond grinding tool for grinding carbon steel is obtained.

10. The method for preparing a polycrystalline diamond abrasive tool for grinding carbon steel as described in claim 9, characterized in that, The welding process described in step (2) is as follows: under vacuum conditions, the temperature is increased to 450~550℃ at a rate of ≥50℃ / min and held for 5~6 minutes to preheat the brazing filler metal; then the temperature is increased from 450~550℃ to 700~750℃ and held for 3~5 minutes to melt the brazing filler metal. After that, the grinding head and the substrate are connected and fixed, and the head is taken out after cooling.

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