A method for preparing a diamond cutter by warm-pressing high-temperature brazing sintering

Abstract

This invention discloses a method for preparing diamond cutting teeth by high-temperature brazing sintering under warm-pressing, belonging to the fields of powder metallurgy and brazing technology. The method involves preparing raw materials for the warm-pressed cutting teeth, warm-pressing them into high-density blanks with a density of 85%-98%; coating the surface with brazing flux and diamond; and then sintering the high-density blanks under warm-pressing in a reducing atmosphere or vacuum. The sintering process completes the warm-pressing of the blanks, while simultaneously melting and filling the gaps in the cutting teeth and brazing the diamonds onto the blank surface. The diamond cutting teeth produced by this method can be used in diamond cutting saw blades, diamond thin-walled drill bits, diamond grinding discs, and other products. They possess the long service life of diamond tools prepared by powder method, as well as the sharpness and broad applicability of brazed diamond tools. Furthermore, the product process is optimized, eliminating the need for ceramic grinding wheel sharpening of the cutting teeth.

Description

Technical Field

[0001] This invention belongs to the fields of powder metallurgy and brazing technology, and particularly relates to a method for preparing diamond cutting teeth by high-temperature brazing sintering under high-temperature pressure. Background Technology

[0002] With the advancement of science and technology and economic development, the organic integration of multiple processes is becoming increasingly important.

[0003] Warm pressing is a technique that combines increased density with the selection of high-performance materials. Increased density helps improve the mechanical properties and overall performance of parts, while directly producing parts with the final dimensions and shape, thus significantly reducing production costs. Warm pressing technology for metal powders has made significant progress in recent years, adapting to the development trend of high-density, low-cost, and easily precision-formed powder products.

[0004] Sintered diamond tools are made by mixing metal powders such as copper powder, iron powder, and nickel powder with diamond particles, and then bonding them through warm pressing and sintering. Sintering is a process in which the surface area of ​​powder particles decreases and the pore volume decreases when the powder or powder compact is sintered at a temperature below the melting point of the main components. Diamond cutting teeth prepared by sintering have diamond embedded in the metal powder. During the production process, grinding wheels are used to polish the cutting teeth to bring out the diamond's edge. The resulting diamond cutting teeth have a thick working layer, making them wear-resistant and durable.

[0005] Diamond brazing technology treats the superhard abrasive and the substrate as base materials, with an alloy solder added in between. After high-temperature heating, the solder melts and welds the superhard abrasive and substrate together. The most significant characteristic of this method of fixing superhard abrasives is the chemical reaction between the abrasive and the solder, which contains strong carbide-forming elements, producing carbides at the interface. This carbide layer acts as a bonding bridge, connecting the abrasive grains to the binder. Furthermore, the metallurgical reaction between the solder and the metal substrate, which also possesses metallic bonds, creates a strong bond between the abrasive grains and the substrate. This results in high abrasive weld strength, preventing the diamond from easily detaching from the substrate. Therefore, the abrasive can be firmly held even with a high exposure, and the cutting edge is sharp with ample chip removal space. This is the biggest difference between brazed diamond tools and sintered diamond tools. However, since most brazed diamond products are single-layered, although they are very sharp and have high cutting efficiency, their lifespan is much shorter than that of sintered products.

[0006] Each process has its own advantages and disadvantages, but by organically combining multiple processes, diamond cutting teeth with superior performance can be obtained. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing diamond cutting tools by high-temperature brazing and sintering under high-temperature pressure. By combining multiple processes, the prepared diamond cutting tools have advantages such as excellent performance, high production efficiency, simple operation, environmental protection and safety, and energy saving and consumption reduction.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing diamond cutting tools by high-temperature brazing and sintering under high-temperature pressure includes the following steps:

[0010] Step S1: Prepare raw materials for the warm-pressed cutting teeth: Mix two or more of the following metal elemental powders—Fe, Cu, Sn, Ni, Co, WC, Zn, Cr, and Mn—in a specific ratio to obtain a mixed metal powder. Then Add to diamond and mix evenly to obtain a mixed powder. ;

[0011] Step S2, Warm-press molding: The mixed powder from step S1 is molded using a steel mold. The process involves heating and compacting the material to obtain a compacted block.

[0012] Step S3: Prepare a polymeric organic adhesive: 1-5 parts polyvinyl butyral, 100 parts anhydrous ethanol or isopropanol, heat to 40-70℃, stir, and wait until the polyvinyl butyral is completely dissolved.

[0013] Step S4: Prepare the raw materials for brazing: Mix two or more of the elemental powders of Fe, Cu, Sn, Ni, Cr, Mn, and Ti in a certain proportion to obtain a mixed metal powder. ;

[0014] Step S5, Prepare the soldering flux: The powder is added to the polymer organic adhesive and stirred evenly to prepare a paste-like brazing flux;

[0015] Step S6: Coat the surface of the blank pressing block from step S2 with the brazing flux prepared in step S5, then evenly adhere diamonds to the surface of the brazing flux, and let it dry.

[0016] Step S7, reducing atmosphere or vacuum sintering: Place the diamond-coated block from step S6 into a reducing atmosphere furnace or vacuum sintering furnace for a period of time, and then slowly cool it to room temperature.

[0017] Step S8, Post-processing: The sintered diamond block is sandblasted and then processed to produce diamond cutting teeth.

[0018] A further improvement of the technical solution of the present invention is that the weight percentages of Fe, Cu, Sn, Ni, Co, WC, Zn, Cr and Mn metal element powders in step S1 are as follows: Fe: 25-75 wt%, Cu: 0-35 wt%, Sn: 0-5 wt%, Ni: 5-75 wt%, Co: 5-35 wt%, WC: 0-10 wt%, Cr: 0-5 wt%, Zn: 0-4 wt%, Mn: 0-3 wt%.

[0019] A further improvement to the technical solution of the present invention lies in: in step S1, the diamond and the mixed powder The weight ratio ranges from 1 to 5 g / 100g.

[0020] A further improvement of the technical solution of the present invention is that: in step S2, the mold temperature during the pressing process is 150-190 degrees, and the density of the compacted block of diamond cutting teeth is 85%-95%.

[0021] A further improvement of the technical solution of the present invention is that: the two sides and the top surface of the hot-pressed billet are in the form of a plane or a groove, and the brazing flux and the bonded diamond are covered on the sides and the top surface or the groove of the billet, or the brazing flux and the bonded diamond are locally coated on the billet according to a certain pattern.

[0022] A further improvement of the technical solution of the present invention is that: in step S4, the weight percentages of Fe, Cu, Sn, Ni, Cr, Mn and Ti metal elemental powders in the brazing raw materials are Fe: 5-20wt%, Cu: 0-25wt%, Sn: 0-5wt%, Ni: 50-90wt%, Cr: 1-5wt%, Mn: 1-5wt%, and Ti: 1-5wt%. The mixed powder is added to the binder prepared in S3 at a ratio of 5-20g / 100g and stirred at high speed until it is uniform and forms a paste.

[0023] A further improvement to the technical solution of the present invention is that the brazing flux in step S5 can be replaced with nickel-based brazing paste Ni-6, containing 89% nickel, with a brazing temperature of 925℃~1095℃; or replaced with Ni-7, containing 76% nickel, with a brazing temperature of 980℃~1095℃.

[0024] A further improvement of the technical solution of the present invention is as follows: in step S6, the flux is coated: the flux is coated onto the surface of the warm-pressed block, the diamond is evenly sprinkled on the block coated with the flux, the diamond is adhered to the block by the flux, and then dried.

[0025] A further improvement of the technical solution of the present invention is that: the pressed block prepared in step S6 is placed flat on a graphite pad, and graphite strips with the same thickness as the design of the cutting teeth are placed around the periphery of the graphite pad. The heating temperature is 850-1050℃ in a reducing atmosphere furnace or a vacuum sintering furnace, and the heating time is 1-4h.

[0026] A further improvement of the technical solution of the present invention is that: the diamond briquettes sintered in step S7 are cooled in the furnace, and the furnace exit temperature is 80-150℃. The sintered diamond cutting teeth can be directly used for high frequency or laser welding, and the surface diamond is fully exposed.

[0027] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0028] Compared to the high-temperature and high-pressure sintering method using graphite mold resistance heating, this invention uses warm pressing to produce high-density preforms with a density of 85%-95%, resulting in higher strength. By coating the surface with a diamond layer, the metallurgical sintering of the high-density preforms and surface diamond brazing are carried out simultaneously during the sintering process. Some of the brazing flux is immersed into the preforms, increasing the forming density of the preforms to 90%-99%. Brazed diamond tools have initial sharpness, but with only a single layer of diamond, they cannot achieve long service life. The initial speed of diamond tools produced by powder metallurgy warm pressing is affected by the sharpening of the surface ceramic grinding wheel, resulting in a low diamond exposure height and low cutting speed in the initial stage of use.

[0029] The diamond composite cutting teeth with surface brazing in this application not only meet the initial cutting sharpness requirements of diamond tool products, but also meet the long-life cutting requirements of warm-pressed blocks. It combines the advantages of warm-pressing and brazing processes, while compensating for each other's disadvantages.

[0030] This application describes diffusion alloying and brazing of diamond during the sintering stage in a vacuum or reducing atmosphere. During sintering, Sn and Zn in the warm-pressed compact melt and undergo multi-element alloying with Fe, Co, Cu, and Ni. The multi-element alloyed metal structure increases the wettability of the diamond. The brazing flux Fe, Cu, Sn, Ni, Cr, Mn, and Ti on the surface of the compact undergo multi-element alloying simultaneously. In particular, the addition of Cr and Ti increases the activity of the multi-element metals, promoting surface and interfacial diffusion of the powder. The brazing flux in a semi-molten state encapsulates the diamond bonded to the surface, while some of the brazing flux is immersed into the warm-pressed compact, increasing the density of the compact and the bonding force to the diamond.

[0031] Compared to powder metallurgy methods for producing diamond cutting tools, this application fully exposes the diamond, achieving a cutting edge height similar to brazed diamond products. Compared to powder metallurgy, it reduces the diamond cutting tool sharpening process, lowers costs, improves the working environment, and results in a sharper product. Compared to brazed diamond products, it features multiple layers of diamond participating in cutting, with uniform and continuous cutting edge extension, increasing product lifespan and offering superior cost-effectiveness. Attached Figure Description

[0032] Figure 1 This is a diagram showing the actual thickness of the diamond cutting teeth measured in Embodiment 1 of the present invention;

[0033] Figure 2 This is a diagram showing the actual thickness of the diamond cutting teeth measured in Embodiment 2 of the present invention;

[0034] Figure 3 These are the front view, side view, and top view of the diamond cutting tooth obtained in Embodiment 1 of the present invention;

[0035] Figure 4 These are the front view, side view, and top view of the diamond cutting tooth obtained in Embodiment 2 of the present invention;

[0036] Figure 5 This is a schematic diagram of the diamond cutting teeth produced by partially coating a certain pattern with brazing flux and diamond according to the present invention. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to embodiments:

[0038] A method for preparing diamond cutting teeth by high-temperature calcination includes the following steps:

[0039] S1: Preparation of raw materials for the hot-pressed cutting teeth: Mix Fe, Cu, Sn, Ni, Co, WC, Zn, Cr and Mn metal elemental powders or alloy powders composed of two or more of these powders in a certain proportion to obtain a mixed metal powder. The weight percentages of the elemental metal powders were Fe: 25–75 wt%, Cu: 0–35 wt%, Sn: 0–5 wt%, Ni: 5–75 wt%, Co: 5–35 wt%, WC: 0–10 wt%, Cr: 0–5 wt%, Zn: 0–4 wt%, and Mn: 0–3 wt%. Then, P1 was added to diamond and mixed thoroughly to obtain mixed powder P2.

[0040] S2: Warm pressing: The mixed powder from step S1 is formed using a steel mold. The process involves heating and compacting the material, with the mold heated to 150-190 degrees Celsius, to produce a compacted block with a density of 85%-95%.

[0041] S3: Prepare a high-molecular organic adhesive: 1-5 parts polyvinyl butyral, 100 parts anhydrous ethanol or isopropanol, heat to 40-70 degrees Celsius, stir, and wait until the polyvinyl butyral is completely dissolved to the required viscosity.

[0042] S4: Prepare the raw materials for brazing: Mix Fe, Cu, Sn, Ni, Cr, Mn, Ti elemental powders or alloy powders composed of two or more of these powders in a certain proportion to obtain a mixed metal powder. The weight percentages of the powders are Fe: 5-20 wt%, Cu: 0-25 wt%, Sn: 0-5 wt%, Ni: 50-90 wt%, Cr: 1-5 wt%, Mn: 1-5 wt%, and Ti: 1-5 wt%.

[0043] S5: Prepare the soldering flux: ... The powder is added to the polymer organic adhesive and stirred until it forms a paste.

[0044] S6: Coat the surface of the preformed block from step S2 with the brazing flux prepared in S5, and apply the brazing flux to the surface or groove of the warm-pressed block in an integral or specific shape. Then, evenly adhere diamonds to the surface of the brazing flux.

[0045] S7: Reducing atmosphere or vacuum sintering: Place the bonded diamond block from step S6 into a reducing atmosphere furnace or vacuum sintering furnace and heat to 850-1050℃ for 1-4 hours. Cool with the furnace, and remove from the furnace at 80-150℃.

[0046] S8: Post-processing: The sintered diamond blocks are sandblasted and then processed to produce diamond cutting teeth.

[0047] The above-mentioned brazing flux can be commercially available nickel-based brazing paste Ni-6, containing 89% nickel, with a brazing temperature of 925℃~1095℃; or nickel-based brazing paste Ni-7, containing 76% nickel, with a brazing temperature of 980℃~1095℃.

[0048] Example 1:

[0049] The specific steps for fabricating diamond cutting teeth with a theoretical thickness of 3.2mm are as follows:

[0050] S1: Raw material preparation: Mix Fe, Cu, Sn, Ni, Co, and WC elemental metal powders in a specific ratio to obtain mixed metal powder P1. The weight percentages of the Fe, Cu, Sn, Ni, Co, and WC elemental metal powders are Fe: 55wt%, Cu: 25wt%, Sn: 2wt%, Ni: 10wt%, Co: 3wt%, and WC: 5wt%. Then... Add to diamond and mix evenly to obtain a mixed powder. In step S1, diamond and mixed powder The ratio range is 1.8g / 100g;

[0051] S2: Warm pressing: The raw materials are pressed through a warm pressing mold to form the mixed powder from step S1. The compaction operation is performed, with a pressing temperature of 180℃ and a pressure of [missing information]. It is pressed into a preform with a density of 88% and a thickness of 2.7-2.8 mm;

[0052] S3: Prepare the polymer organic adhesive: Take 4g of polyvinyl butyral and 100g of anhydrous ethanol, heat in a water bath to 60℃, stir evenly, and wait until the polyvinyl butyral is completely dissolved.

[0053] S4: Prepare the raw materials for brazing: Mix Fe, Cu, Sn, Ni, Cr, Mn, Ti elemental powders or alloy powders composed of two or more of these powders in a certain proportion to obtain a mixed metal powder. The powder's weight percentages are Fe: 10wt%, Cu: 15wt%, Sn: 3wt%, Ni: 55wt%, Cr: 2wt%, Mn: 3wt%, and Ti: 2wt%.

[0054] S5: Prepare the soldering flux: ... The powder is added to the polymeric organic adhesive and stirred until it forms a paste. In step S5... The ratio to polymeric organic adhesives is in the range of 20g / 100g;

[0055] S6: Coat the surface of the preformed block from step S2 with the brazing flux prepared in S5, and evenly brush the brazing flux onto both sides and the outer arc top surface of the warm-pressed block. Then, evenly sprinkle diamonds onto the surface of the block coated with brazing flux, and evenly adhere the diamonds to the surface of the block. Let it dry. In step S6, the diamonds selected are 35 / 40 grit.

[0056] S7: Reducing atmosphere or vacuum sintering: Place the bonded diamond compact from step S6 flat on a graphite pad, arrange them neatly, and side-press and limit them. The limiting height should be 0.2-0.5 mm lower than the bonded diamond compact. Place it in a reducing atmosphere furnace and heat to 950℃ for 1.5 hours. Cool with the furnace, and remove it at 120℃.

[0057] S8: Post-treatment: The surface of the sintered diamond block is sandblasted to obtain diamond cutting teeth with uniform diamond exposure.

[0058] Measuring the thickness of diamond cutting teeth.

[0059]

[0060] Example 2:

[0061] The specific steps for fabricating diamond cutting teeth with a theoretical thickness of 3.2mm are as follows:

[0062] S1: Raw material preparation: Mix Fe, Cu, Sn, Ni, Co, and WC elemental metal powders in a specific ratio to obtain mixed metal powder P1. The weight percentages of Fe, Cu, Sn, Ni, Co, WC, Zn, and Mn elemental metal powders are Fe: 55wt%, Cu: 25wt%, Sn: 2wt%, Ni: 10wt%, Co: 3wt%, and WC: 5wt%. Then... Add to diamond and mix evenly to obtain a mixed powder. In step S1, diamond and mixed powder The ratio range is 1.8 g / 100g;

[0063] S2: Warm pressing: The raw materials are compacted using a warm pressing mold to press the mixed powder P2 from step S1. The pressing temperature is 180℃ and the pressure is... It is pressed into a preform with a density of 88% and a thickness of 2.7-2.8 mm;

[0064] S3: Prepare the flux: Use commercially available nickel-based brazing paste Ni-6 (containing 89% nickel), brazing temperature: 925℃~1095℃;

[0065] S4: Coat the surface of the preformed block from step S2 with the above-mentioned brazing flux, and evenly brush the brazing flux onto both sides and the outer arc top surface of the warm-pressed block. Then evenly sprinkle diamonds onto the surface of the block coated with brazing flux, and evenly adhere the diamonds to the surface of the block. Let it dry. The diamonds should be 35 / 40 grit.

[0066] S5: Reducing atmosphere or vacuum sintering: Place the diamond-coated blocks flat on a graphite pad, arrange them neatly, and place them in a reducing atmosphere furnace. Heat to 950℃ for 1.5 hours. Cool in the furnace, and remove from the furnace at 120℃.

[0067] S8: Post-processing: The surface of the sintered diamond block is sandblasted and then subjected to final processing to obtain diamond cutting teeth with uniform diamond exposure.

[0068] The thickness of diamond cutting teeth is measured in the table below.

[0069]

[0070] Comparative Example

[0071] Diamond cutting teeth were prepared using conventional methods (referring to the preparation method in CN113182523A). The materials for the cutting teeth were the same as those in Example 2. The finished products were then tested.

[0072]

[0073] The diamond cutting teeth produced by this method can be used in diamond cutting saw blades, diamond thin-walled drill bits, diamond grinding discs, and other products. They have the long service life of diamond tools prepared by powder method, as well as the sharpness and wide applicability of brazed diamond tools. At the same time, the product process is optimized, and the cutting teeth do not need to be sharpened with ceramic grinding wheels. This invention has the advantages of excellent performance, high production efficiency, simple operation, environmental protection and safety, and energy saving and consumption reduction.

Claims

1. A method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure, characterized in that: Includes the following steps: Step S1: Prepare raw materials for the warm-pressed cutting tool teeth: Mix alloy powder composed of two or more of the following powders in a certain proportion to obtain a mixed metal powder. Then Add to diamond and mix evenly to obtain a mixed powder. ; Step S2, Warm-press molding: The mixed powder from step S1 is molded using a steel mold. The process involves heating and compaction to obtain a compacted block; in step S2, the mold temperature during the pressing process is 150-190℃, and the density of the compacted block with diamond cutting teeth is 85%-95%. Step S3: Prepare a polymeric organic adhesive: 1-5 parts polyvinyl butyral, 100 parts anhydrous ethanol or isopropanol, heat to 40-70℃, stir, and wait until the polyvinyl butyral is completely dissolved to the required viscosity. Step S4: Prepare the raw materials for brazing: Mix two or more of the elemental powders of Fe, Cu, Sn, Ni, Cr, Mn, and Ti in a certain proportion to obtain a mixed metal powder. ; Step S5, Prepare the soldering flux: The powder is added to the polymer organic adhesive and stirred evenly to prepare a paste-like brazing flux; Step S6: Coat the surface of the blank pressing block from step S2 with the brazing flux prepared in step S5, then evenly adhere diamonds to the surface of the brazing flux, and let it dry; Brazing flux coating in step S6: Coat the surface of the warm-pressed pressing block with the brazing flux, evenly sprinkle diamonds on the pressing block coated with the brazing flux, and adhere the diamonds to the pressing block through the brazing flux, and let it dry. Step S7, reducing atmosphere or vacuum sintering: Place the diamond-coated block from step S6 into a reducing atmosphere furnace or vacuum sintering furnace for a period of time, and then slowly cool it to room temperature. Step S8, Post-processing: The sintered diamond block is sandblasted and then processed to produce diamond cutting teeth.

2. The method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure according to claim 1, characterized in that: In step S1, the weight percentages of Fe, Cu, Sn, Ni, Co, WC, Zn, Cr, and Mn powders are as follows: Fe: 25-75 wt%, Cu: 0-35 wt%, Sn: 0-5 wt%, Ni: 5-75 wt%, Co: 5-35 wt%, WC: 0-10 wt%, Cr: 0-5 wt%, Zn: 0-4 wt%, and Mn: 0-3 wt%.

3. The method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure according to claim 1, characterized in that: In step S1, diamond and mixed powder The weight ratio ranges from 1 to 5 g / 100g.

4. The method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure according to claim 1, characterized in that: The sides and top of the hot-pressed billet are either flat or grooved. The brazing flux and the bonded diamond are applied to the sides and top or grooves of the billet, or the brazing flux and the bonded diamond are applied locally to the billet according to a certain pattern.

5. The method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure according to claim 1, characterized in that: In step S4, the weight percentages of Fe, Cu, Sn, Ni, Cr, Mn, and Ti elemental powders in the brazing raw materials are as follows: Fe: 5-20 wt%, Cu: 0-25 wt%, Sn: 0-5 wt%, Ni: 50-90 wt%, Cr: 1-5 wt%, Mn: 1-5 wt%, and Ti: 1-5 wt%. The mixed powders are added to the adhesive prepared in S3 at a ratio of 5-20 g / 100 g and stirred at high speed until homogeneous, forming a paste.

6. The method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure according to claim 1, characterized in that: The flux in step S5 can be replaced with nickel-based brazing paste Ni-6, containing 89% nickel, with a brazing temperature of 925℃~1095℃; or replaced with Ni-7, containing 76% nickel, with a brazing temperature of 980℃~1095℃.

7. The method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure according to claim 1, characterized in that: The compressed block prepared in step S6 is placed flat on a graphite pad, and graphite strips with the same thickness as the cutting teeth are placed around the perimeter of the graphite pad. The block is heated in a reducing atmosphere furnace or a vacuum sintering furnace at a temperature of 850-1050℃ for 1-4 hours.

8. The method for preparing diamond cutting teeth by high-temperature brazing and sintering under high-temperature pressure according to claim 1, characterized in that: The diamond briquettes sintered in step S7 are cooled in the furnace at a temperature of 80-150°C. The sintered diamond cutting teeth are sandblasted and can be directly used for high-frequency or laser welding, with the surface diamonds fully exposed.

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