Polycrystalline diamond composite sheet, manufacturing method thereof, PDC bearing assembly and cutting tool

Abstract

The present invention provides a polycrystalline diamond composite sheet, a manufacturing method thereof, a PDC bearing assembly and a cutting tool. The polycrystalline diamond composite sheet includes an alloy matrix layer and a diamond layer, and the diamond layer is combined with the alloy matrix layer by high-temperature sintering; the polycrystalline diamond composite sheet also includes an alloy steel layer; the diamond layer, the alloy matrix layer and the alloy steel layer are arranged in sequence along a first direction, and the alloy matrix layer and the alloy steel layer are combined with each other by diffusion welding. The manufacturing method includes placing the powder raw material of the diamond layer, the alloy matrix layer and the alloy steel layer into a high-temperature and high-pressure device for synthesis. The PDC bearing assembly includes a polycrystalline diamond composite sheet. The cutting tool includes a polycrystalline diamond composite sheet. The alloy matrix layer and the alloy steel layer are combined by diffusion welding, the shear strength of the weld of the two material layers is effectively improved, and the overall strength of the polycrystalline diamond composite sheet with a three-layer structure is improved. In addition, no secondary welding is required, the production efficiency is improved, and secondary high temperature damage to the diamond layer is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of superhard composite materials, and in particular to a polycrystalline diamond composite sheet, a manufacturing method thereof, a PDC bearing assembly and a cutting tool. Background Art

[0002] Diamond composite sheets are made by sintering diamond powder and cemented carbide matrix (alloy matrix layer) together under high temperature and high pressure. Diamond powder is sintered into a polycrystalline diamond layer, which makes the composite sheet have the ultra-high hardness and wear resistance of diamond. Diamond composite sheets can be used in various working environments, such as diamond composite sheets can be used in PDC drill bits and PDC bearings.

[0003] Taking PDC bearings as an example, the diamond composite sheet needs to be installed and welded to the support ring of the PDC bearing. The support ring is provided with a mounting position. After the diamond composite sheet is placed in the mounting position, since the support ring is made of steel, the cemented carbide substrate and the support ring need to be brazed together by adding solder.

[0004] Another existing diamond composite sheet, in order to improve its installation ability, also includes a connecting layer connected to the alloy matrix layer, the connecting layer is made of steel, and the physical properties are similar to those of the support ring. The connecting layer is combined with the alloy matrix layer through secondary welding in the form of brazing. After the diamond composite sheet is placed in the installation position, the connecting layer and the support ring can be welded together by fusion welding.

[0005] The existing polycrystalline diamond composite sheet has the following problems: if the carbide substrate and the support ring are brazed, the weld strength between the carbide substrate and the support ring is low and the impact resistance is poor; if a connecting layer is set on the polycrystalline diamond composite sheet, due to the brazing between the connecting layer and the carbide substrate, the shear strength is low and the weld between the connecting layer and the carbide substrate is prone to fracture. In addition, when the secondary high-temperature welding of the connecting layer and the carbide substrate is performed, there is a possibility of damaging the diamond layer and reducing production efficiency. Summary of the invention

[0006] A first object of the present invention is to provide a polycrystalline diamond compact having improved installation strength, improved shear strength and improved production efficiency.

[0007] A second object of the present invention is to provide a method for manufacturing the polycrystalline diamond compact.

[0008] A third object of the present invention is to provide a PDC bearing assembly having the above-mentioned polycrystalline diamond compact installed therein and having improved strength.

[0009] A fourth object of the present invention is to provide a cutting tool having improved strength by mounting the above-mentioned polycrystalline diamond compact.

[0010] The polycrystalline diamond composite sheet provided by the first purpose of the present invention includes an alloy substrate layer and a diamond layer, and the diamond layer is combined with the alloy substrate layer by high-temperature sintering; the polycrystalline diamond composite sheet also includes an alloy steel layer; the diamond layer, the alloy substrate layer and the alloy steel layer are arranged in sequence along a first direction, and the alloy substrate layer and the alloy steel layer are combined with each other by diffusion welding.

[0011] It can be seen from the above scheme that in the press, under the conditions of high temperature and high pressure, the sintering of the diamond powder on the alloy matrix layer and the diffusion welding of the alloy matrix layer and the alloy steel layer can be completed in the same time period. The alloy matrix layer and the alloy steel layer are combined by diffusion welding, and the metal atoms diffuse with each other, the bonding force between the two material layers is greatly improved, and the shear strength of the weld of the two material layers is effectively improved, thereby ensuring the overall strength of the three-layer structure of the polycrystalline diamond composite sheet. In addition, there is no need for secondary welding, the production efficiency is improved, and the diamond layer will not be damaged due to the secondary high temperature.

[0012] A further solution is that the alloy steel layer includes a base and a connecting structure, the base is connected to the alloy matrix layer, and the connecting structure extends from the base away from the alloy matrix layer; in the projection in the first direction, the projection area of ​​the connecting structure is smaller than the projection area of ​​the base.

[0013] A further solution is that the connection structure is a plug-in column.

[0014] As can be seen from the above, cutting the alloy steel layer can form a connection structure, which can be a plug-in column, a threaded column or other structure suitable for snap-on installation. Taking the plug-in column as an example, a step through hole is set on the support ring. When the polycrystalline diamond composite sheet is placed in the step through hole, the plug-in column passes through the hole section with a smaller inner diameter, and the base and the alloy matrix layer are located in the hole section with a larger inner diameter. Subsequently, on the side where the plug-in column passes through, the plug-in column and the support ring are fusion-welded, and on the side where the alloy matrix layer is located, the alloy matrix layer and the support ring are brazed. The opposite sides of the polycrystalline diamond composite sheet are effectively welded to the support ring, and one side is combined by fusion welding. This setting can effectively improve the connection strength between the polycrystalline diamond composite sheet and the support ring, and further reduce the possibility of breakage or even falling off.

[0015] The second purpose of the present invention provides a method for manufacturing a polycrystalline diamond composite sheet, which is used to manufacture the above-mentioned polycrystalline diamond composite sheet; the manufacturing method includes a high temperature and high pressure step, and the powder raw material of the diamond layer, the alloy matrix layer and the alloy steel layer are placed in a high temperature and high pressure device for synthesis.

[0016] A further solution is that in the high temperature and high pressure step, the powder raw material of the diamond layer, the alloy substrate layer and the alloy steel layer are placed in a high temperature and high pressure device and synthesized at a pressure of not less than 5 MPa and a temperature of not less than 1000 degrees Celsius.

[0017] It can be seen from the above scheme that since the first pressure condition of the diffusion welding between the alloy matrix layer and the alloy steel layer is higher than the second pressure condition of the sintering of the diamond powder, and the diffusion welding between the alloy matrix layer and the alloy steel layer and the sintering of the diamond powder are carried out in the same period, the first pressure condition of the diffusion welding between the alloy matrix layer and the alloy steel layer is used as the set pressure in the press, and the process is performed by presetting a suitable set temperature according to the first temperature condition of the diffusion welding between the alloy matrix layer and the alloy steel layer and the second temperature condition of the sintering of the diamond powder, thereby realizing the integration of the diamond layer, the alloy matrix layer and the alloy steel layer in one process. This setting can effectively improve production efficiency, ensure the welding strength between the alloy matrix layer and the alloy steel layer and the shear strength at the weld, and avoid secondary high temperature from damaging the diamond layer.

[0018] A further solution is that after the high temperature and high pressure step, a cutting step is also included; the cutting step includes: cutting the alloy steel layer to form a connection structure on the alloy steel layer.

[0019] As can be seen from the above, taking the plug-in column as an example, after the synthesis of the polycrystalline diamond composite sheet is completed, it is only necessary to perform turning processing on the alloy steel layer to form a plug-in column with a smaller outer diameter in the center of the alloy steel layer.

[0020] The third purpose of the present invention provides a PDC bearing assembly including a support ring and a polycrystalline diamond composite sheet fixed on the support ring; the polycrystalline diamond composite sheet adopts the above-mentioned polycrystalline diamond composite sheet; the support ring is provided with a mounting through hole, and the mounting through hole includes a first hole segment and a second hole segment arranged in sequence along its penetration direction, the inner contour of the first hole segment matches the outer contour of the substrate, and the inner contour of the second hole segment matches the outer contour of the connecting structure; the connecting structure is located in the second hole segment, and the base and the alloy substrate layer are located in the first hole segment.

[0021] A further solution is that the mounting through hole runs through between a first side and a second side opposite to each other on the support ring; on the first side, the connection structure is fusion-welded to the support ring.

[0022] A further solution is that, on the second side, the alloy base layer and the support ring are brazed.

[0023] It can be seen from the above scheme that, firstly, the alloy substrate layer and the alloy steel layer are welded by diffusion welding, and the strength of the polycrystalline diamond composite sheet itself is improved; under this premise, the opposite sides of the polycrystalline diamond composite sheet are effectively welded to the support ring, and one side is combined by fusion welding. This setting can effectively improve the connection strength between the polycrystalline diamond composite sheet and the support ring, and reduce the possibility of breakage or even falling off.

[0024] The fourth object of the present invention is to provide a cutting tool comprising a polycrystalline diamond compact, wherein the polycrystalline diamond compact adopts the above-mentioned polycrystalline diamond compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the first embodiment of the polycrystalline diamond compact of the present invention before cutting.

[0026] Figure 2 This is a schematic diagram of the first embodiment of the polycrystalline diamond compact after cutting.

[0027] Figure 3 It is a partial schematic diagram of the support ring in the first embodiment of the PDC bearing assembly of the present invention.

[0028] Figure 4 Schematic diagram of a first embodiment of a PDC bearing assembly according to the present invention.

[0029] Figure 5 This is a partial schematic diagram of the first embodiment of the PDC bearing assembly of the present invention before welding.

[0030] Figure 6 This is a partial schematic diagram of the first embodiment of the PDC bearing assembly after welding of the present invention.

[0031] Figure 7 FIG. 1 is a schematic diagram of a second embodiment of a polycrystalline diamond compact according to the present invention.

[0032] Figure 8 FIG. 4 is a schematic diagram of a third embodiment of a polycrystalline diamond compact according to the present invention.

[0033] Fig. 9 It is a structural exploded view of the second embodiment of the PDC bearing assembly of the present invention.

[0034] Fig.10 It is a structural exploded view of the third embodiment of the PDC bearing assembly of the present invention. DETAILED DESCRIPTION

[0035] First embodiment of polycrystalline diamond composite sheet

[0036] See also Figure 1The polycrystalline diamond composite sheet 100 synthesized in the press without cutting is cylindrical in shape as a whole. The polycrystalline diamond composite sheet 100 includes a diamond layer 1, an alloy matrix layer 2 and an alloy steel layer 3 which are sequentially combined along a first direction (the direction indicated by the arrow in the figure). The diamond layer 1 is formed by sintering a diamond powder raw material on the alloy matrix layer 2 at high temperature and high pressure. The raw material of the alloy matrix layer 2 is tungsten carbide. The alloy steel layer 3 is made of 40CrMoV alloy steel. The alloy matrix layer 2 and the alloy steel layer 3 are welded by diffusion welding.

[0037] See also Figure 2 After cutting the alloy steel layer 3 of the polycrystalline diamond composite sheet 100, the alloy steel layer 3 forms a base 31 and a connecting structure 32. The outer diameter of the base 31 is consistent with the outer diameter of the alloy matrix layer 2. The connecting structure 32 is an insertion column extending from the base 31 along a first direction away from the alloy matrix layer 2. The outer diameter of the connecting structure 32 is smaller than the outer diameter of the base 31. The extended end of the connecting structure 32 is provided with a second chamfer 321.

[0038] Combination Figure 1 and Figure 2 When manufacturing the polycrystalline diamond composite sheet 100, the powder raw material of the diamond layer 1, the alloy substrate layer 2 and the alloy steel layer 3 are placed in a press and synthesized under high temperature and high pressure conditions. During the synthesis process, the sintering of the diamond layer 1 is completed, and the diffusion welding of the alloy substrate layer 2 and the alloy steel layer 3 is completed.

[0039] In the manufacturing method, a pre-pressing step is first performed, in which the diamond powder raw material is placed in a metal round cup, and the diamond powder raw material in the metal round cup is pre-pressed by a pressing block, the pre-pressing number is ≥ 1, preferably, the pre-pressing number is 2 times, and the pre-pressing pressure is 0.1MPa to 1MPa. After the pre-pressing is completed, the diamond powder raw material forms a working layer preform.

[0040] Then, a high temperature and high pressure step is performed, wherein the cobalt sheet as an adhesive, the carbide substrate (alloy substrate layer) and the alloy steel column (alloy steel layer) are placed in a metal round cup with a working layer preform, and the working layer preform, the cobalt sheet, the carbide substrate and the alloy steel column are abutted in sequence. Then, the metal round cup with the working layer preform, the cobalt sheet, the carbide substrate and the alloy steel column is placed in a press for high temperature and high pressure synthesis.

[0041] In the high temperature and high pressure step, the synthesis pressure is above 5 MPa, and the synthesis temperature is above 1000 degrees Celsius. Since the first pressure condition of the diffusion welding between the cemented carbide substrate (alloy substrate layer) and the alloy steel column (alloy steel layer) is higher than the second pressure condition of the sintering of the diamond powder, and the diffusion welding between the cemented carbide substrate and the alloy steel column and the sintering of the diamond powder are carried out in the same period, the press is set to a higher first pressure condition, that is, a synthesis pressure of 5 MPa or more. In addition, the process is performed by presetting a suitable set temperature in combination with the first temperature condition of the diffusion welding between the cemented carbide substrate (alloy substrate layer) and the alloy steel column and the second temperature condition of the sintering of the diamond powder, so as to realize the synthesis of the diamond layer 1, the alloy substrate layer 2 and the alloy steel layer 3 in one process.

[0042] Then, a cutting process is performed to cut the alloy steel layer 3 to form a base 31, a connection structure 32, and a second chamfer 321 on the extended end of the connection structure 32 on the alloy steel layer 3. The manufacturing method can improve the production efficiency of the polycrystalline diamond composite sheet, and can also avoid the damage of the diamond layer 1 caused by the secondary high temperature, while ensuring the welding strength between the alloy substrate layer 2 and the alloy steel layer 3 and the shear strength at the weld. According to the shear strength test, the shear strength of the weld between the alloy substrate layer 2 and the alloy steel layer 3 is above 170 MPa.

[0043] See also Figure 3 to Figure 4 The PDC bearing assembly of this embodiment is an assembly in a PDC thrust bearing. The PDC bearing assembly includes a support ring 4 and a polycrystalline diamond composite sheet 100. The support ring 4 is provided with a plurality of mounting through holes 400 evenly arranged along its circumference and axially penetrating between the first side 41 and the second side 42 of the support ring 4. The mounting through holes 400 are step holes. The mounting through holes 400 include a first hole section 401 and a second hole section 402 connected in sequence along the axial direction. The outer diameter of the first hole section 401 is greater than the outer diameter of the second hole section 402. In addition, a first chamfer 403 is provided at the periphery of the mounting through hole 400 on the first side 41.

[0044] See also Figure 2 , Figure 3 and Figure 5 After the polycrystalline diamond compact 100 is installed in the installation through hole 400, the base 31 and the alloy matrix layer 2 are located in the first hole section 401, and the inner contour of the first hole section 401 matches the outer contour of the base 31 and the alloy matrix layer 2. The connection structure 32 is located in the second hole section 402, and the inner contour of the second hole section 402 matches the outer contour of the connection structure 32. A fusion welding groove 404 is formed between the first chamfer 403 and the second chamfer 321.

[0045] Recombination Figure 6On the first side 41, the outer periphery of the extended end of the connection structure 32 is fusion welded to the outlet edge of the second hole section 402 on the support ring 4. The weld is located at the fusion welding groove 404, and the molten material 309 of the connection structure 32 and the support ring 4 are fused at the fusion welding groove 404 and combined after cooling. The setting of the fusion welding groove 404 can prevent the fusion welding process from affecting the outer contour of the PDC bearing assembly. On the second side 42, the outer peripheral surface of the alloy matrix layer 2 and the inlet edge of the first hole section 401 on the support ring 4 are brazed, and the solder 209 combines the alloy matrix layer 2 with the support ring 4.

[0046] Firstly, the alloy matrix layer 2 and the alloy steel layer 3 are welded by diffusion welding, and the strength of the polycrystalline diamond composite sheet 1 itself is improved; under this premise, the opposite sides of the polycrystalline diamond composite sheet 1 with the alloy steel layer 3 added are effectively welded to the support ring 4, and one side is combined by fusion welding. This setting can effectively improve the connection strength between the polycrystalline diamond composite sheet 1 and the support ring 4, and reduce the possibility of breakage or even falling off.

[0047] Second embodiment of polycrystalline diamond composite sheet

[0048] See also Figure 7 In this embodiment, in the alloy steel layer 513 of the polycrystalline diamond composite sheet 51, the connection structure 514 is a threaded column, and the outer periphery of the connection structure 514 is provided with an external thread 515. Correspondingly, in the PDC bearing assembly, in the mounting through hole of the support ring that matches the polycrystalline diamond composite sheet 51, an internal thread that matches the external thread 515 is provided on the inner wall surface of the second hole section with a smaller inner diameter. When the connection structure 514 is located in the second hole section, the external thread 515 matches the internal thread on the inner wall surface of the second hole section, which can improve the assembly strength of the polycrystalline diamond composite sheet 51 and the support ring.

[0049] In addition, after the polycrystalline diamond composite sheet 51 is installed on the support ring, the extended end of the threaded column is fusion-welded to the outlet edge of the second hole section on the support ring; further, the alloy matrix layer and the support ring are brazed.

[0050] Third embodiment of polycrystalline diamond composite sheet

[0051] See also Figure 8 In this embodiment, the alloy steel layer 523 of the polycrystalline diamond composite sheet 52 includes two connection structures 524, and the connection structures 524 are plug-in columns. Correspondingly, the mounting through hole provided on the support ring includes a first hole segment and two second hole segments. Both of the two second hole segments are connected to the first hole segment in the penetration direction, and the two second hole segments are adjacently arranged in a direction perpendicular to the penetration direction.

[0052] In other embodiments, the connection structure may also be other protruding structures other than the cylinder, such as a protruding structure of a cubic column.

[0053] In other embodiments, the number of connection structures is three or more.

[0054] PDC bearing assembly second embodiment

[0055] See also Fig. 9 The PDC bearing assembly provided by the present invention can also be used as an assembly of a PDC radial bearing. The support ring 81 is an outer support ring of the PDC radial bearing. The support ring 81 is provided with a mounting through hole 810 that penetrates in its radial direction. The polycrystalline diamond composite sheet 71 is inserted into the mounting through hole 810 from the inner periphery of the support ring 81. The polycrystalline diamond composite sheet 71 is welded to the outer peripheral surface of the support ring 81 by fusion welding. In addition, the surface 710 of the diamond layer of the polycrystalline diamond composite sheet 71 installed on the outer support ring is set as an inner concave arc surface.

[0056] PDC bearing assembly third embodiment

[0057] See also Fig.10 The PDC bearing assembly provided by the present invention can also be used as an assembly of a PDC radial bearing. The support ring 82 is an inner support ring of the PDC radial bearing. The support ring 82 is provided with a mounting through hole 820 that penetrates in its radial direction. The polycrystalline diamond composite sheet 72 is inserted into the mounting through hole 820 from the outer periphery of the support ring 82. The polycrystalline diamond composite sheet 72 is welded to the outer periphery of the support ring 82 by fusion welding. In addition, the surface 720 of the diamond layer of the polycrystalline diamond composite sheet 72 installed on the inner support ring is set as an outer convex arc surface.

[0058] In addition, the polycrystalline diamond composite sheet provided by the present invention can also be used in cutting tools such as drill bits, and the present invention also seeks to protect a grinding tool comprising the polycrystalline diamond composite sheet of the present invention.

[0059] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for manufacturing a polycrystalline diamond composite sheet, characterized in that: The manufacturing method is used to manufacture a polycrystalline diamond composite sheet of a PDC bearing assembly, wherein the PDC bearing assembly comprises a support ring and the polycrystalline diamond composite sheet fixed on the support ring, wherein the polycrystalline diamond composite sheet comprises an alloy matrix layer and a diamond layer, wherein the diamond layer is combined with the alloy matrix layer by high-temperature sintering; The polycrystalline diamond composite sheet also includes an alloy steel layer; The diamond layer, the alloy matrix layer and the alloy steel layer are sequentially arranged along a first direction, the alloy matrix layer and the alloy steel layer are bonded to each other by diffusion welding, and the powder raw material of the diamond layer, the hard alloy matrix of the alloy matrix layer and the alloy steel column of the alloy steel layer are placed in a press for synthesis at a pressure of not less than 5 MPa and a temperature of not less than 1000 degrees Celsius, the sintering of the diamond layer is completed during the synthesis process, and the diffusion welding of the alloy matrix layer and the alloy steel layer is completed at the same time; The alloy steel layer comprises a base and a connection structure, wherein the base is connected to the alloy matrix layer, and the connection structure extends from the base away from the alloy matrix layer; In the projection of the first direction, the projection area of ​​the connection structure is smaller than the projection area of ​​the base, and the connection structure is a plug-in column; The support ring is provided with a mounting through hole, and the mounting through hole includes a first hole segment and a second hole segment sequentially arranged along the penetration direction thereof, the inner contour of the first hole segment matches the outer contour of the base, and the inner contour of the second hole segment matches the outer contour of the connecting structure; The connecting structure is located in the second hole segment, and the base and the alloy matrix layer are located in the first hole segment; The manufacturing method comprises: In the high temperature and high pressure step, the powder raw material of the diamond layer, the cemented carbide substrate of the alloy substrate layer and the alloy steel column of the alloy steel layer are placed in a high temperature and high pressure device for synthesis, during which the sintering of the diamond layer is completed and diffusion welding of the alloy substrate layer and the alloy steel layer is completed.

2. The method for manufacturing a polycrystalline diamond compact according to claim 1, characterized in that: In the high temperature and high pressure step, the powder raw material of the diamond layer, the alloy substrate layer and the alloy steel layer are placed in a high temperature and high pressure device and synthesized at a pressure of not less than 5 MPa and a temperature of not less than 1000 degrees Celsius.

3. The method for manufacturing a polycrystalline diamond compact according to claim 1 or 2, characterized in that: After the high temperature and high pressure step, a cutting process step is also included; The cutting step includes: cutting the alloy steel layer to form a connection structure on the alloy steel layer.

4. The method for manufacturing a polycrystalline diamond compact according to claim 1, characterized in that: The mounting through hole runs through between the first side and the second side opposite to each other on the support ring; On the first side, the connection structure is fusion welded to the support ring.

5. The method for manufacturing a polycrystalline diamond compact according to claim 4, characterized in that: On the second side, the alloy matrix layer is brazed to the support ring.

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