Cobalt removal sealing injection mold for polycrystalline diamond compact

Abstract

The utility model relates to the technical field of injection molding, in particular to a sealing injection mold for removing cobalt from a polycrystalline diamond compact. A polycrystalline diamond compact cobalt removal sealing injection mold comprises an upper mold block and a lower mold block, an injection molding inner cavity is defined by the upper mold block and the lower mold block after the upper mold block and the lower mold block are oppositely combined, and a positioning groove which is equal to a diamond layer of a polycrystalline diamond compact in outer diameter and matched with the diamond layer of the polycrystalline diamond compact in end face shape is formed in the injection molding inner cavity in the lower mold block. The positioning groove is used for positioning and placing an adaptive polycrystalline diamond compact in a posture that a diamond layer faces downwards, the depth of the positioning groove is not greater than the height of the diamond layer of the polycrystalline diamond compact, and an injection port is formed in the upper module. Therefore, the polycrystalline diamond compacts are supported by the positioning grooves of the lower module, and the polycrystalline diamond compacts can be stably placed in the injection molding inner cavity regardless of the structural thickness or shape of the polycrystalline diamond compacts, so that a better injection molding effect is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of injection molding, in particular to a polycrystalline diamond composite sheet decobaltized sealing injection mold. Background Art

[0002] Polycrystalline diamond composite sheet is a new type of functional material. It is made of diamond micropowder, cemented carbide substrate and binder catalyst powder sintered under high pressure and high temperature conditions. It has the high hardness, high wear resistance and thermal conductivity of diamond, and the strength and impact toughness of cemented carbide. It is currently widely used in high-tech fields such as mechanical processing, fossil energy mining, geological exploration and advanced manufacturing. It is an ideal material for manufacturing cutting tools, drilling bits and other wear-resistant tools.

[0003] The commonly used binder catalyst powder is cobalt. As a catalyst, cobalt can promote the formation of diamond-diamond bonds (DD bonds) between diamond particles during sintering. However, in the high-temperature environment of geological drilling, cobalt as a catalyst can promote the graphitization of diamond, reducing the thermal stability of polycrystalline diamond composite sheets. In addition, the thermal expansion coefficients of cobalt and diamond are quite different, and large thermal stresses are easily generated in high-temperature environments, which may directly lead to the failure of diamond composite sheets.

[0004] Based on this, it is necessary to remove cobalt from polycrystalline diamond composite sheets to improve their comprehensive performance. Commonly used methods for removing cobalt include chemical methods and electrolytic methods. Chemical methods generally use strong acid and strong alkali etching; electrolytic methods use electrochemical principles to promote the separation of cobalt in the electrolyte. Among them, the electrolytic method has defects such as high equipment requirements and complex processes, while the acid leaching method has relatively low costs, easy operation, and is convenient for large-scale application.

[0005] However, the cemented carbide part is more likely to react chemically with acids and alkalis, leading to product corrosion. Therefore, the key to decobalting is to protect the cemented carbide and avoid corrosion. Another focus of decobalting of polycrystalline diamond composite sheets is the sealing technology of cemented carbide. Traditional sealing methods use sealing rings and sealing fixtures to seal cemented carbide. Most of these sealing methods require manual operation and have unstable operation factors, which may cause large fluctuations in the decobalting depth of the product and affect the consistency of product performance.

[0006] The utility model patent with authorization announcement number CN214324039U discloses a cobalt removal sealing device for a polycrystalline diamond composite sheet, including an upper mold core and a lower mold core, the lower mold core is provided with an injection port, a positioning groove is provided in the inner middle part of the upper mold core, the upper mold core and the lower mold core are combined together to form an injection cavity inside the two, the injection cavity is a frustum-shaped structure, the external leakage section of the polycrystalline diamond composite sheet is fixedly embedded in the positioning groove, and the polycrystalline diamond composite sheet is suspended in the injection cavity by a suction cup provided in the positioning groove. Since the shapes of the surfaces of different polycrystalline diamond composite sheets are different, and many of them are not planar structures, this method of suspension by suction cups is structurally unstable during use, which can easily cause the polycrystalline diamond composite sheet to fall and affect injection molding. Utility Model Content

[0007] The utility model aims to provide a polycrystalline diamond composite sheet decobaltization sealing injection mold, which is used to solve the problem that the existing polycrystalline diamond composite sheet decobaltization sealing device is structurally unstable during use by suspending through a suction cup, which easily causes the polycrystalline diamond composite sheet to fall and affect injection molding.

[0008] The utility model adopts the following technical scheme: a polycrystalline diamond composite sheet de-cobaltized sealing injection mold, comprising an upper module and a lower module, wherein the upper module and the lower module are matched to form an injection cavity inside, and a positioning groove having an outer diameter equal to that of the diamond layer of the polycrystalline diamond composite sheet and an end face shape matching that of the lower module is provided in the injection cavity, the positioning groove is used for positioning and inserting an adapted polycrystalline diamond composite sheet with the diamond layer facing downward, the groove depth of the positioning groove is not greater than the height of the diamond layer of the polycrystalline diamond, and an injection port is provided on the upper module.

[0009] Furthermore, the lower module includes a mold sleeve and a mold core that are separately arranged, and the positioning groove is arranged on the mold core.

[0010] Furthermore, a pushing structure for material removal is provided inside the mold core at a position corresponding to the positioning groove and guided to slide in the up and down directions.

[0011] Furthermore, a magnetic attraction structure is provided on the top of the push structure.

[0012] Furthermore, the push structure is arranged below the bottom of the positioning groove in a natural state to maintain a gap with the polycrystalline diamond compact.

[0013] Furthermore, the ejection structure is located in the middle of the mold core.

[0014] Furthermore, the injection port is arranged corresponding to the top center position of the injection cavity.

[0015] Furthermore, an outer boss is arranged at the bottom of the mold core, the mold sleeve is placed on the outer boss, and the mold sleeve is sleeved on the mold core.

[0016] The polycrystalline diamond composite sheet decobaltization sealing injection mold of the utility model improves the existing polycrystalline diamond composite sheet decobaltization sealing injection mold, and the beneficial effect of the polycrystalline diamond composite sheet decobaltization sealing injection mold of the utility model is: an injection cavity is enclosed by an upper module and a lower module, an injection port is provided on the upper module, and a positioning groove is provided on the lower module, the positioning groove is equal to the outer diameter of the diamond layer of the polycrystalline diamond composite sheet, and the end face shape matches, and is used for inserting an adapted polycrystalline diamond composite sheet, and the diamond layer of the polycrystalline diamond composite sheet is placed into the positioning groove with one end facing downward. Since the groove depth of the positioning groove is not greater than the height of the diamond layer of the polycrystalline diamond, the remaining part leaking out of the positioning groove is injection-sealed by the sealing fluid of the injection port, and finally the diamond layer of the polycrystalline diamond composite sheet is decobalted, so that the polycrystalline diamond composite sheet is supported by the positioning groove of the lower module, and no matter how the structural thickness or shape of the polycrystalline diamond composite sheet is, it can be ensured to be stably placed in the injection cavity to achieve a better injection molding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of an embodiment of a polycrystalline diamond composite sheet decobaltization sealing injection mold of the utility model when in use;

[0018] Figure 2 It is a structural schematic diagram of a mold core having a planar groove;

[0019] Figure 3 It is a structural schematic diagram of a mold core having a V-shaped groove;

[0020] Figure 4 A schematic diagram of the structure of a flat-tooth type polycrystalline diamond composite sheet;

[0021] Figure 5 A schematic diagram of the structure of a polycrystalline diamond composite sheet for ridge teeth;

[0022] Figure 6 It is a schematic diagram of the structure of the polycrystalline diamond composite sheet of the flat gear after injection molding;

[0023] Figure 7 Schematic diagram of the structure of the polycrystalline diamond composite sheet of the roof tooth after injection molding.

[0024] In the figure: 1. ejector structure; 2. mold core; 3. diamond layer; 4. carbide base; 5. mold sleeve; 6. positioning groove; 7. injection molding cavity; 8. injection port; 9. upper mold module; 10. external boss. DETAILED DESCRIPTION

[0025] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0026] First, the technical solution of the utility model is generally described as follows:

[0027] The mechanism of diamond-diamond bond (DD bond) in sintered polycrystalline diamond can be summarized as follows: when the synthesis chamber is heated to a specific temperature, the metal catalyst cobalt powder will melt and penetrate the gaps between the diamond powders, graphitizing the surface of the diamond grains. When the liquid is supersaturated with carbon and the sintering environment is in the stable zone of the diamond phase, carbon atoms will precipitate to form diamond. As the liquid cobalt migrates, the carbon atoms on the surface of the diamond continue to dissolve and precipitate, forming more and more DD bonds, and the diamond grains are bonded to each other through DD bonds.

[0028] There is a huge difference in the thermal expansion coefficients of cobalt and diamond. When polycrystalline diamond is prepared under high temperature and high pressure, there is a large amount of thermal stress inside it. A large amount of thermal stress may cause the diamond skeleton to tear and the diamond grains to fall off during the application of polycrystalline diamond composite sheets. In addition, when the application temperature reaches above 700°C, cobalt will catalyze the conversion of diamond to graphite. The higher the cobalt content, the more obvious the catalytic effect. Based on this, the polycrystalline diamond composite sheet needs to be decobalted to improve its overall performance.

[0029] The utility model is based on the problem that the polycrystalline diamond composite sheet decobaltization sealing device in the prior art is unstable in structure during use by suspending through a suction cup, which easily causes the polycrystalline diamond composite sheet to fall and affect the injection molding. A polycrystalline diamond composite sheet decobaltization sealing injection mold is designed, comprising an upper module and a lower module, which are combined to form an injection molding inner cavity. The key point of the utility model is that an injection port is arranged on the upper module, and a positioning groove is arranged on the lower module. The positioning groove is used to be equal to the outer diameter of the diamond layer of the polycrystalline diamond composite sheet and match the end face shape. The groove depth of the positioning groove is not greater than the height of the diamond layer of the polycrystalline diamond. The adapted polycrystalline diamond composite sheet is placed in the positioning groove with the diamond layer facing downward, so that the polycrystalline diamond composite sheet can be stably placed in the positioning groove of the lower module without causing it to fall, and the positioning groove blocks the injection fluid from flowing to the surface of the diamond layer of the polycrystalline diamond composite sheet, so as to realize the injection molding sealing of the cemented carbide substrate of the polycrystalline diamond composite sheet, and protect the cemented carbide substrate during the decobaltization process.

[0030] Specific embodiment of the polycrystalline diamond composite sheet cobalt removal sealing injection mold of the utility model:

[0031] The structural schematic diagram of the polycrystalline diamond composite sheet decobaltization sealing injection mold of the utility model is as follows Figure 1As shown, a polycrystalline diamond composite sheet decobaltization sealing injection mold comprises an upper module 9 and a lower module, the upper module 9 and the lower module are arranged in a matched manner, and the upper module 9 and the lower module are matched to form an injection cavity 7, a positioning groove 6 is provided on the lower module, the positioning groove 6 is equal to the outer diameter of the diamond layer 3 of the polycrystalline diamond composite sheet, and the end face shape matches, the groove depth of the positioning groove 6 is not greater than the height of the diamond layer 3 of the polycrystalline diamond, so that after the injection molding is completed, the cemented carbide substrate 4 is protected by the sealing material to prevent the cemented carbide substrate 4 from being corroded during the decobaltization treatment of the diamond layer 3, and an injection port 8 is provided on the upper module 9.

[0032] The lower module is an integrated structure and is easy to manufacture. However, since the surface shapes of different polycrystalline diamond composite sheets are different, replacing the lower module as a whole wastes materials. Therefore, preferably, the lower module includes a mold sleeve 5 and a mold core 2. The mold sleeve 5 and the mold core 2 are separately arranged, and the positioning groove 6 is arranged on the mold core 2. In this way, when using the structure of polycrystalline diamond composite sheets with different surface shapes, the mold core 2 can be replaced separately, which saves materials, has a compact structure, and is easy to replace.

[0033] The mold core 2 is configured as an integral structure with a positioning groove 6 on the top for assembling the polycrystalline diamond composite sheet. The structure is simple, but after the injection molding is completed, part of the polycrystalline diamond composite sheet is in the positioning groove 6 of the mold core 2, which is not convenient for disassembly. Preferably, the mold core 2 is provided with a pushing structure 1 for guiding and sliding in the up and down directions corresponding to the positioning groove 6. In this way, after the injection molding is completed, the polycrystalline diamond composite sheet is pushed by the pushing structure 1, which is convenient to operate and makes it easy to disassemble the polycrystalline diamond composite sheet after the injection molding.

[0034] The positioning groove 6 on the mold core 2 has a good positioning effect on the polycrystalline diamond composite sheet, but in order to further ensure the stability of the polycrystalline diamond composite sheet and better separate the upper module 9 from the sealing material on the polycrystalline diamond composite sheet after the injection molding is completed, preferably, a magnetic attraction structure is provided on the top of the push structure 1 to prevent the product from falling off and being damaged during the injection molding process, to ensure that the friction force in the positioning groove 6 is large and does not rotate, and when separating from the upper module 9, the magnetic attraction structure will attract the polycrystalline diamond composite sheet, so that the upper module 9 can be separated from the polycrystalline diamond composite sheet. Specifically, in this embodiment, the magnetic attraction structure is a magnet, which generates a strong magnetic force on the polycrystalline diamond composite sheet.

[0035] Since the magnetic attraction structure may generate a large suction force on the polycrystalline diamond composite sheet at the moment of placement, in order to avoid a large collision impact on the polycrystalline diamond composite sheet that may cause it to break, preferably, the pushing structure 1 is naturally lower than the bottom of the positioning groove 6 to maintain a gap with the polycrystalline diamond composite sheet, so that a small gap is generated between the pushing structure 1 and the polycrystalline diamond composite sheet to prevent the polycrystalline diamond composite sheet from being shattered due to the instantaneous suction force when the polycrystalline diamond composite sheet is placed. The small gap protects the polycrystalline diamond composite sheet.

[0036] Since the polycrystalline diamond composite sheet is placed in the positioning groove 6 to have a circumferentially uniform and symmetrical structure, in order to make the magnetic attraction more uniform, preferably, the push structure 1 is located in the middle of the mold core 2, which can ensure a better magnetic attraction effect, and the push force is located in the center during the push process, which is convenient for pushing the polycrystalline diamond composite sheet out of the positioning groove 6. Of course, in other embodiments, the push structure 1 can also be located beside the mold core 2, or multiple push structures 1 can be arranged circumferentially.

[0037] During the injection molding process, in order to achieve more uniform injection molding and better sealing effect, preferably, the injection port 8 is set corresponding to the top center position of the injection cavity 7, specifically, the injection port 8 is located at the top of the upper module 9, and is vertically set at the middle position of the top, so that it is facing the carbide substrate 4 of the polycrystalline diamond composite sheet, so that the injection molding is more uniform, the coating effect is better, and the sealing reliability is improved. Of course, in other embodiments, according to the actual situation on site, the injection port 8 can also be set at the side position of the top of the upper module 9, or at the side position of the upper module 9.

[0038] In order to ensure the compactness of the structure and facilitate disassembly, preferably, an outer boss 10 is provided at the bottom of the mold core 2, and the mold sleeve 5 is placed on the outer boss 10, and the mold sleeve 5 is sleeved on the mold core 2. In this way, when disassembling and replacing the mold core 2, since the mold sleeve 5 is sleeved on the mold core 2 and placed on the outer boss 10 of the mold core 2, it is convenient to remove the mold sleeve 5 and ensure the stability of the structure of the mold core 2. Of course, in other embodiments, the mold sleeve 5 can also be provided with an inner boss, and the mold core 2 is passed through the mold sleeve 5 and placed on the inner boss.

[0039] In this embodiment, the mold core 2 is a hollow cylindrical structure, a positioning groove 6 is provided on the top of the mold core 2, and the push structure 1 is a columnar structure, so that the outer circumference of the push structure 1 fits with the inner circumference of the mold core 2, and the guiding sliding effect of the cylindrical structure is better and the fit is tighter. The upper module 9 is a cylinder with an opening facing downward, and the outer diameter of the upper module 9 is the same as the outer diameter of the mold sleeve 5. The upper module 9 is fitted with the mold sleeve 5, and the injection cavity 7 is the space above the mold core 2 corresponding to the top position of the upper module 9. The overall structure is compact and complete.

[0040] Specifically, the shape of the positioning groove 6 is set according to the surface shape of the polycrystalline diamond composite sheet. Figure 4 The flat-toothed polycrystalline diamond composite sheet shown in FIG. 1 has a diamond layer 3 whose surface is flat and a mold core 2 whose specific shape is as follows: Figure 2 As shown, the positioning groove 6 of the mold core 2 is a flat groove, which can be formed by injection molding as shown in FIG. Figure 6 The polycrystalline diamond composite sheet of the partially sealed flat gear shown in the figure; when the polycrystalline diamond composite sheet is as Figure 5 The polycrystalline diamond composite sheet of the roof tooth type shown in the figure has a surface of the diamond layer 3 of the polycrystalline diamond composite sheet in the shape of a roof, and the specific shape of the mold core 2 is as follows Figure 3 As shown, the positioning groove 6 of the mold core 2 is a V-shaped groove, which can be formed by injection molding as shown in FIG. Figure 7 A partially sealed roof tooth type PCD compact is shown.

[0041] Through the above description of the specific embodiment of the polycrystalline diamond composite sheet decobaltization sealing injection mold of the utility model, it can be seen that the polycrystalline diamond composite sheet decobaltization sealing injection mold of the utility model is composed of an upper module and a lower module that are matched with each other, and the upper module and the lower module form an injection cavity, and an injection port is provided on the upper module. The positioning groove provided on the lower module is used to support the polycrystalline diamond composite sheet, and the positioning groove is equal to the outer diameter of the diamond layer of the polycrystalline diamond composite sheet, and the end face shape matches, and the diamond layer of the polycrystalline diamond composite sheet is placed in the positioning groove with the diamond layer facing downward. The depth of the positioning groove is not greater than the height of the diamond layer of the polycrystalline diamond, and the remaining part is injection-sealed through the injection port. Finally, the diamond layer of the polycrystalline diamond composite sheet is decobalted, so that the polycrystalline diamond composite sheet is supported by the positioning groove of the lower module to ensure stable placement in the injection cavity to achieve better injection molding effect. Since the mold core is provided with a push structure, the push structure corresponds to the top center position of the injection cavity. When the injection molding is completed, the molded model is pushed out of the mold by sliding on the mold core through the push structure. The overall operation is convenient, saving time and effort.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the description and drawings of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polycrystalline diamond composite sheet decobaltization sealing injection mold, comprising an upper module and a lower module, wherein the upper module and the lower module are combined to form an injection molding cavity, wherein: A positioning groove having an outer diameter equal to that of the diamond layer of the polycrystalline diamond composite sheet and an end face shape matching that of the polycrystalline diamond composite sheet is provided in the injection molding inner cavity of the lower module. The positioning groove is used for positioning and inserting the adapted polycrystalline diamond composite sheet with the diamond layer facing downward. The depth of the positioning groove is not greater than the height of the diamond layer of the polycrystalline diamond. An injection port is provided on the upper module.

2. The polycrystalline diamond composite sheet decobaltized sealed injection mold according to claim 1, characterized in that: The lower module comprises a mold sleeve and a mold core which are separately arranged, and the positioning groove is arranged on the mold core.

3. The polycrystalline diamond composite sheet decobaltized sealed injection mold according to claim 2, characterized in that: The mold core is internally provided with a push-up structure for material removal at a position corresponding to the positioning groove and guiding and sliding in the up and down directions.

4. The polycrystalline diamond composite sheet decobaltized sealed injection mold according to claim 3, characterized in that: A magnetic attraction structure is arranged on the top of the push structure.

5. The polycrystalline diamond composite sheet decobaltized sealed injection mold according to claim 4, characterized in that: The push structure is arranged below the bottom of the positioning groove in a natural state to maintain a gap with the polycrystalline diamond composite sheet.

6. The polycrystalline diamond composite sheet decobaltized sealed injection mold according to claim 3, 4 or 5, characterized in that: The push structure is located in the middle of the mold core.

7. The polycrystalline diamond composite sheet decobaltized sealed injection mold according to any one of claims 1 to 5, characterized in that: The injection port is arranged corresponding to the top center position of the injection cavity.

8. The polycrystalline diamond composite sheet decobaltized sealed injection mold according to any one of claims 2 to 5, characterized in that: The bottom of the mold core is provided with an outer convex platform, the mold sleeve is placed on the outer convex platform, and the mold sleeve is sleeved on the mold core.

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